■01 130° I. Cape St Elias «•« (|Jome< *N*> Montague I , ...... , ^ -n i . a Middleton Seldowa ^ pe BARREN *» .# . & ... luglas ' ISLANDS Ls .~> Alognak PortlockBank Island £l Pamplona «V» >• \ Fairweatl - - Ground -■'^\/~- Prince Ruperty-^ V «^\ \ H0DGKIN^\ /W SEAMOUNTS QUEEN CHARLOT '000 (->. GILBERT SEAMOUNTS ■*<*' >^' x"7 -^ -30* )ry Lopy . ,45« The Gulf of Alaska Digitized by the Internet Archive in 2012 with funding from LYRASIS Members and Sloan Foundation http://archive.org/details/gulfofalaskaphyOOhood The Gulf of Alaska Physical Environment and Biological Resources Edited by Donald W. Hood and Steven T. Zimmerman (*2fiS^ U.S. Department of Commerce National Oceanic and Atmospheric Administration National Ocean Service Office of Oceanography and Marine Assessment Ocean Assessments Division Alaska Office U.S. Department of the Interior Minerals Management Service Alaska OCS Region Published in 1986 by (he Alaska Office, Ocean Assessments Division, National Oceanic and Atmospheric Administration, LIS Department of Commerce, with Financial support from the Alaska OCS Region Office, Minerals Management Service, U.S. Department of the Interior This document has been reviewed by the U.S. Department of the Interior, Minerals Management Service, Alaska OCS Region Office and die U.S. Department of Commerce, National Oceanic and Atmospheric Administration's Ocean Assessments Division Alaska Office, and approved for publication. The interpretations of data and opinions expressed in this document are those of the authors. Approval does not necessarily signify that the contents reflect the views and policies of the Department of the Interior or those of the Department of Commerce. The Federal government does not approve, recommend, or endorse any proprietary product or proprietary material mentioned in this publication. No reference shall be made to the National Oceanic and Atmospheric Administration, Minerals Management Service, or to this publication in any advertising or sales promotion which would indicate or imply that the Federal government approves, recommends, or endorses any proprietary product or material mentioned herein, or which has as its purpose an intent to cause directly or indirectly the advertised product to be used or purchased because of this publication. Minerals Management Service publication number: OCS study, MMS 86-0095 Library of Congress Cataloging-in-Publication Data The Gulf of Alaska. (OCS study) Includes bibliographies and index. "Minerals Management Service publication number: OCS study, MMS 86-0095"— T.p. verso. 1. Marine biology — Alaska — Alaska, Gulf of. 2. Oceanography — Alaska — Alaska, Gulf of. 3. Alaska, Gulf of (Alaska) I. Hood, D. W. (Donald Wilbur), 1918- . II. Zimmerman, S. T. III. United States. Ocean Assessments Division. Alaska Office. IV. United States. Minerals Management Service. Alaska OCS Region. QH95.35.G85 1987 508.3164'34 86-63313 For sale by Superintendent of Documents U.S. Government Printing Office Washington, D.C. 20402 Available in paper or microfiche (Order Number PB87-103230) from the National Technical Information Service U.S. Department of Commerce Springfield, Virginia 22161 Printed in the United States of America Contents Foreward vii Preface ix Dedication xi Section One: Introduction 1 Physical Setting and Scientific History 5 Donald W. Hood Section Two: Physical Environment 2 Meteorology 3 1 Judith G. Wilson and James E. Overland 3 Physical Oceanography 57 Ronald K. Reed and James D. Schumacher 4 Chemical Distributions and Signals in the Gulf of Alaska, Its Coastal Margins and Estuaries William S. Reeburgh and George W Kipphut 5 Geomorphology, Sediment, and Sedimentary Processes 93 Monty A. Hampton, Paul R. Carlson, Homa J. Lee, and Richard A. Feely 6 Seismicity, Tectonics, and Geohazards of the Gulf of Alaska Regions 1 45 Klaus H. Jacob 7 Interactions Between Silled Fjords and Coastal Regions 1 87 David C. Burrell Section Three: Biological Resources 8 Microbiology 221 Ronald M. Atlas and Robert P. Griffiths 9 Phytoplankton and Primary Production 249 Raymond N. Sambrotto and Carl J. Lorenzen 10 Zooplankton 285 R. Ted Cooney 1 1 Biogeography and Ecology of the Intertidal and Shallow Subtidal Communities 305 Charles E. O'Clair and Steven T Zimmerman 12 The Subtidal Benthos 347 Howard M. Feder and Stephan C. Jewett 13 The Nearshore Fish 399 Donald E. Rogers, BrendaJ. Rogers, and Richard J. Rosenthal v 14 Marine Fisheries: Resources and Environments 41 7 OCSEAP Staff 15 Pacific Salmon 461 Donald E. Rogers 16 Marine Birds 479 Anthony R. DeGange and Gerald A. Sanger 17 Marine Mammals 527 Donald G. Calkins 18 Ecological Relations 561 Timothy R. Parsons Section Four: Issues and Perspectives 19 Environmental Issues 575 Laurie E. Jarvela 20 Management Needs of Scientific Data 597 M. Jawed Hameedi Glossary 619 Index 637 Foreword In response to President Nixon's 1974 national goal of attaining energy self-sufficiency by the end of the 1980s, the nation's outer continental shelf (OCS) regions were targeted for immediate petroleum development. Because a large proportion of the nation's OCS is located adjacent to Alaska and because this area was estimated to contain vast quantities of both oil and gas, development of Alaska's OCS resources was given high priority. The Gulf of Alaska in particular was identified as very promising and, in 1974, it was the first Alaska area to be considered for leasing by the Bureau of Land Management. Although it was recognized that the development of energy resources on the Alaska OCS was essen- tial to the national interest, it was also recognized that this development could endanger Alaska's marine environment and its living resources. There was a question concerning the extent to which oil and gas development would effect the environment. As a result of the public concern about the poten- tial effects, the Department of the Interior's manager of the OCS leasing program (then the Bureau of Land Management and now the Minerals Management Service) initiated an environmental studies pro- gram which was designed during a series of planning meetings held by both the BLM and NOAA in 1974. The program became the Alaska Outer Continental Shelf Environmental Assessment Program (OCSEAP). This program was managed by the Department of Commerce (through the National Oceanic and Atmospheric Administration) as part of an interagency agreement with the Department of the Interior's Minerals Management Service. The study, which started in 1975, was multidisciplinary in design. This approach was necessary in order to provide the Secretary of the Department of the Interior, other decision makers, and members of the public with a source of information to use both for managing OCS oil and gas development and for minimizing potential effects on both the marine and the coastal environments. The data that were collected and analyzed under the OCSEAP program substantially aided the deci- sion makers in the design and execution of the leasing program on the Alaska OCS. From 1975 to 1985 there were over 100 studies either directly or indirectly applied to Gulf of Alaska issues. Numerous scientists from a wide range of disciplines participated in these studies. The area they investigated was found to have one of the richest assemblages of biological resources on the Alaska outer continental shelf. Prior to the advent of OCSEAP, much of the data were collected by those agencies that managed the commercial fisheries, and integrated multidisciplinary studies had never been performed. By 1982, six lease sales had been held in the Gulf of Alaska, and the subsequent exploratory drilling had resulted in over 20 dry wells. This lack of success dampened enthusiasm and contributed to a shift in emphasis away from this area to other OCS regions of Alaska, namely the Bering, Chukchi, and Beaufort Seas. However, the information collected in the Gulf of Alaska under OCSEAP has contributed greatly to the advancement of knowledge about this rich marine environment. Based largely on the results of OCSEAP studies, this volume constitutes the most current and the most comprehensive description of the OCS physical and biological environment in the Gulf of Alaska. It provides a consolidated source of scientific data and information previously unavailable for the Gulf of Alaska and it will be of great use to the scientific community as well as to resource managers for many years. Jerry Imm Chief, Environmental Studies Section Alaska OCS Region Minerals Management Service Department of Interior Robert Bl \\i \ Manager, Alaska Office Ocean Assessments Division Office of Marine Assessment National Ocean Sen ice National Oceanic and Atmospheric Administration Department of Commen e Preface "To the majority of mankind . . . the sea is little else than a vast abyss without limits or bottom" Elisee Reclus (1873) Much has been learned of the oceans in the century since those words were written. But until the 1960s, the Gulf of Alaska remained largely a frontier, and knowledge of it came mainly from expedition reports, the yearly cruises of fishery research vessels, and from the lonely vigil at the Canadian Ocean Weather Station 'P'. Following Alaska's admission to statehood in 1959, several geographically limited studies were con- ducted in the Gulf. Most of these studies were in response to events such as the Great Alaskan Earth- quake of 1964 and the proposed development of a petroleum loading facility at Port Valdez. However, it was not until the inception of the Outer Continental Shelf Environmental Assessment Program (OCSEAP) in 1974 that attempts were made to undertake a truly comprehensive examination of the oceanography of the Gulf of Alaska. OCSEAP was an outgrowth of President Nixon's Project Independence — a program whose goal was to make the United States self-sufficient in oil production. Following the call for Project Independence, inter- est in the Gulf of Alaska ran quite high because Alaska's first producing oil fields had been developed there — near Katalla in the eastern Gulf in 1902 and in Cook Inlet several years later. In anticipation of the oil and gas leases for the outer continental shelf, which had been scheduled for the northeastern Gulf of Alaska in 1976, the Bureau of Land Management (BLM; now the Minerals Management Serv- ice— MMS) asked the National Oceanographic and Atmospheric Administration (NOAA) to undertake a research program that would determine resources that would be at risk if oil development began in that area. OCSEAP grew out of this cooperative effort between NOAA and MMS. Most of the early OCSEAP work took the form of broad-scale environmental assessments — either extensive plant- and animal- distribution studies or descriptions of the physical, chemical, or geo- logical properties found over wide geographic areas. Much of this research, because it was 'mis- sion-oriented' in style and therefore not easily publishable in scientific journals, has since languished in the gray literature — buried in quarterly or annual reports, summarized in difficult-to-obtain syn- thesis reports and environmental impact statements, or archived in file drawers. It is to the credit of the early leaders of OCSEAP that they recognized the problem of gray literature and required that the data collected be archived in repositories such as the National Oceanographic Data Center, the National Geophysical and Solar-Terrestrial Data Center, and the National Institutes of Health. But even though the data are available, recovering them is a lengthy process that is not under- taken by many scientists — especially those just entering the field or those seeking quickly available information. That, then, is the purpose of this volume: to provide an authoritative, comprehensive, and readily available reference for those wishing to acquaint themselves with what is currently known about the Gulf of Alaska. We asked knowledgeable scientists to synthesize and summarize what is known about their research disciplines in a manner that is understandable to the non-specialist. To help in this regard, a glossary of difficult-to-find terms has been included. We have also asked the authors to document extensively the sources of their information, particularly those sources where the information and data were still contained in unpublished documents. There will be gaps in such an endeavor and, because not all insights will survive the summarizing process, some specialists may feel the treatments are incomplete. It is our hope, however, that this book will be of value in providing both a beginning point for the newcomer and a ready reference for the academic veteran of Alaska's south- ern coast. The roots of this book can be traced back to the establishment of OCSEAP and to the millions of dollars worth of oceanographic research that the program supported in the ensuing years. But the final form of this book was influenced by the fact that none of the Gulfs lease sales ever yielded commercial quantities of gas or oil. As a result, oil-industry interest in the area was virtually gone by the early 1980s, and OCSEAP's research in the region nearly ceased. Concurrent with the de facto completion of OCS research in the Gulf of Alaska was the publication, in 1981, of The Eastern Bering Sea Shelf: Oceanography and Resources, edited by D.W. Hood and J. A. Calder. The purpose of that two-volume treatise — also OCSEAP-sponsored — was to compile current information about the eastern Bering Sea shelf. The success of that endeavor, as measured by demand and refer- ences to it in the literature, led us to consider preparation of a similar treatise for the Gulf of Alaska. We felt that the largely completed nature of OCSEAP-funded research in the Gulf of Alaska would allow a more broadly topical and integrated approach than had been possible in the Bering Sea treatise, where much of the research was still underway when the document was being written. Approval to begin this project occurred at research planning meetings held by MMS and NOAA in 1982. The initial funding was made available by MMS in 1983. In late 1983, the editors met in Friday Harbor, Washington to draw up a list of potential chapter titles and authors, and in March 1984, the first general meeting was held in Seattle to bring together the prospective authors. At this meeting, the struc- ture and overall purposes of the project were defined, and the general outlines of individual chapters were finalized. In January 1985, a second general meeting was held so that the authors could both verbally and graphically present drafts of their chapters. Discussions at this meeting focused on how each chapter might be integrated and cross-referenced with the others. During the following months, drafts suitable for peer review were prepared. During summer and fall of 1985, the editors were busy marking up manuscripts and involved in dialogues with reviewers and authors. By the end of 1985, virtually all of the final drafts were complete. In the meantime, Northwest Car- tography, Inc. was retained to undertake the technical editing and graphics production, and to prepare the book for printing. By late 1986, this process was complete, and the book was ready for printing. This compendium of research could not have been brought to fruition by the two editors alone. We are pleased to acknowledge the efforts of many others who contributed their energies to this project, and without whom the book could not have been completed. Foremost among these is Laurie Jarvela, who was involved in the project from its inception, and who has served as the OCSEAP project man- ager. Others who encouraged and supported the production of this volume include the three directors of OCSEAP since 1981 — Herbert Bruce, Jawed Hameedi, and Robert Bunney. They are joined by the two managers of BLM's (later MMS's) Alaska Studies Program who served during that same period — Jerry Imm and Cleveland Cowles. Each of the reviewers who provided detailed comments on the chapters are also gratefully acknowl- edged here, as are the efforts of Betty Hood, Heidi Sickles, Cheri Hendren, and Billie Barb who attended to the many administrative matters that arose during the project. The outstanding efforts of Northwest Cartography, Inc., led by William E. Shiels, Project Manager, are also gratefully acknowledged. Donald W. Hood Steven T. Zimmerman Dedication Steller Sea Cow Gentle Martyr to Northern Discovery Steller Sea Cow (Hydrodamalis gigas) Discovered 1741 Extinct 1768 Advances in human understanding are often achieved slowly, and man's desire to exploit new frontiers has nearly always exceeded his attempts to understand them. So it was with the Steller sea cow. The existence of this behemoth was documented by a single scientist on a single voyage of discovery. Before Western man had even a slight understanding of the animal it was gone, consumed as part of the chase after otters and seals in a newly discovered territory. This volume is dedicated to the memory of the Steller sea cow. We hope that the information synthesized herein will provide a basis to better understand the impor- tant links binding all the species that remain in northern waters. Features of a Northern Sea Cow as described by Georg Wilhelm Steller Hydrodamalis gigas Order: Sircnia Family: Dugongidae Size: Length— to 35 ft; weight— to 10 t; girth— to 25 ft; heart — 18 kg, stomach — 2 m long by 1.5 m wide; length of intestinal tract — 152.6 m; body fat — up to 16.5 cm thick. Head: Appearance likened to that of Buffalo; long snout with bristles around mouth; double, bifurcated lips; small eyes; no external ear. Forelimbs: Sixty-one centimeters in length, terminating in skin-covered stubby forefeet; bristles on bottoms of forelimb termin instead of external digits or nails. Hindquarters: Horizontally flattened tail fin in place of hind limbs. Dentition and nutrition: No teeth, but broad, furrowed, horny, gum plates covering palate and anterior part of mandible. Herbivorous dietary preference for selected species of seaweed, including Nereocystis and Laminaria. Reproduction: Low reproductive rate; only one young born at a time; gestation period presumed to be more than a year; dual mammae; behavioral indications of monogamy; conjugal courtship. Social features: Observed to travel and forage as family units of three (male, female, and small calf) within small herds; docile, passive temperament except when injured or harrassed. Discovery and Natural History Western man's encounter with the Steller sea cow hap- pened quite by accident, and the experience might never have been recorded but for the presence of Georg Wilhelm Steller, ship's surgeon and naturalist aboard the Russian ship St. Peter. While sailing home in 1741 from a voyage in the North Pacific Ocean, the scurvy-scourged crew aboard the St. Peter, under the command of Vitus Bering, was ship- wrecked on a small island (later known as Bering Island) 100 miles from Amchitka Island. The already tattered ship was wrecked almost beyond repair, necessitating reconstruction through the long winter. The first days after landing saw the death of Captain Bering and many of his crew as a result of sicknesses caused by poor nutrition and foul water aboard the St. Peter. The survivors initially obtained adequate food from the otters, seals, and vegetation found close at hand, but as time went on this became more difficult, and hunger began to invade the camp. However, in nearby shallow waters the crew noticed large animals grazing in "sea cabbage meadows." These enor- mous creatures were a species of sirenian mammal. When feeding in the shallows, the animals appeared much like overturned boats, with their broad backs fully exposed above water. Although these docile animals could be stroked as they calmly grazed in their slow, bovine manner, the huge bulk and fierce struggle that occurred when the animals were 'hooked', along with their vigorous attempts to save each other, made capture difficult. After many failures in which wounded animals escaped, a man in a rowboat finally managed to use a large hook forged from some of the ship's metal to harpoon an animal. The attached line held by thirty men on shore connected predator and prey for a lengthy tug-of-war until finally the sea cow was dragged ashore and butchered. In later struggles to beach the sea cows, the impaled animals' companions, as a group, tried to dislodge the harpoon, break the rope, and disrupt the men's efforts to bayonet, club, and knife the struggling animal. The sea cows provided a savory meat and sweet oil, which enabled the 45 surviving sailors of Bering's last cruise to complete the reconstruction of the wrecked St. Peter and return home singing the praises of a bountiful treasure in sea otter and seal furs and of the food provided by the gentle Steller sea cow. While awaiting reconstruction of the St. Peter, Steller painstakingly documented in Latin his dissections of a female sea cow along with other unique observations he made during his ten-month stay on Bering Island — obser- vations that included the famous ornithological finds of the rare sea eagle and spectacled cormorant. Evolutionary Speculations Origin The sirenians are believed to be descended from a hoofed beast that probably lived during Paleocene time roughly 50- or 60 million years ago. Their common ancestor might have resembled a primitive Egyptian animal (Moeritherium), which was the size of a pig and which had the lifestyle of a hippopotamus. Only two families of Sirenia exist today, both of them tropical forms: the manatees (Trichechidae) of the Atlantic and Caribbean, and the dugong (Dugongidae) of the Indian Ocean and waters of Africa and Australasia Indo-Malaysia. Largest of any sirenian, the Steller sea cow was the only member of the dugong family to adapt to cold water. Hydro- damalis' ancestral stock migrated to the Pacific, where it evolved during the Pliocene and Pleistocene epochs by adapting both to cold water and to a diet of coastal algae spe- cies. As teeth gave way to broad palatal plates suited for grinding soft plant material, slender finger digits were also replaced by stubby, bristled forefeet that facilitated move- ment and helped tear kelp from along the bottoms of shal- low coastal inlets. Distribution It is conjectured that the Pleistocene distribution of Hydrodamalis might have coincided with that of the sea otter, which ranged along the coast of the North Pacific Ocean from japan to Baja California. A supportive ecological tie existed between the otter and sea cow in coastal habitats, in that the otter was a natural predator of the sea urchin, which competed with the sea cow for kelp. The sea cow's adaptation to cold water may have begun in California!) latitudes during a late Miocene interlude of presumed cooling. The sea cow grazed along the California coast as recently as 20,000 years ago, before it began to die off for reasons that are still not clear. By the eighteenth cen- tury, however, its last bastion of survival was the protective shallow waters around the Commander Islands (Bering Island and Copper Island). Skeletal remains of three Hydrodamalis gigas specimens were found in 1969 in a small interglacial deposit on Amchitka Island, Alaska. This was the first discovery of this species in Pleistocene deposits outside the Commander Islands. This finding suggests that the sea cow might have been widely distributed in the Aleutian Islands and could conceivably explain both the rapid westward migration of the Aleut and the disappearance of the sea cow from the Aleutian Islands. The discovery also gives evidence that the water was apparently warm enough to sustain the kelp growth required to support the sea cow, despite the icecaps which occurred on at least some of the Aleutian Islands. Although it remains a puzzle as to why the bones of Hydro- damalis have not shown up in the Aleut middens, favored explanations are insufficient excavation or submergence of older sites with rising sea levels. Disappearance After the St. Peter's shipwreck survivors returned home in 1742, they spread the word of their serendipitous discovery. Soon the Commander Islands became the annual winter headquarters for fur hunting expeditions that subsisted on sea cow meat for months at a time. The killing of the last Steller sea cow was recorded in 1768, at the end of an unreg- ulated process of wasteful slaughter in which it was esti- mated that only one in every five animals was actually con- sumed. The rest of the wounded animals escaped to the open ocean, where they died of their wounds. Although it is possible that this giant sirenian was on its way to extinction before the intervention of modern man, the hunting pres- sure that led to its extinction a mere 27 years after its discov- ery is unprecedented in the history of man's interaction with large mammals. Bibliography Domning, D.P. 1972 Steller's sea cow and the origin of North Pacific aboriginal whaling: Syesis 5:187-189. Ford, C. 1966 Steller's sea cow. In: Where the Sea Breaks Its Hark. Little, Brown & Co., Boston, MA. pp. 153-165. Colder, F.A. 1922 Bering's Voyages. An Account of the Efforts of the Rus- sians to Determine the Relationship of Asia and A mer- ica, Vol. 1: Log books and Official Reports of First and Second Expeditions, 1724-1730 and 1733-1742. American Geographical Society, New York, NY. 371 pp. Golder, F.A. 1925 Bering's Voyages. An Account of the Efforts of the Rus- sians to Determine the Relationship of Asia and Amer- ica, Vol. II: Steller's Journal of the Sea Voyage from Kamchatka to America and Return on the Second Expedition, 1741-1742. American Geographical Society, New York, NY. 291 pp. Goodwin, G.G. 1946 The end of the great northern sea cow. Natural History (February 1946):56-61. Haley, D. 1978 Steller sea cow. In: Marine Mammals of Eastern North Pacific Waters. D. Haley, editor. Pacific Search Press, Seattle, WA. pp. 11, 19, 236-241. Haley, D. 1980 The great northern sea cow: Steller's gentle siren. Oceans 13:7-9. Hall, E.S., Jr. 1971 Kangiguksuk — a cultural reconstruction of a sixteenth century Eskimo site in northern Alaska. Arctic Anthropology 8(1):1— 101. Jones, R.E. 1967 A Hydrodamalis skull fragment from Monterey Bay, California. Journal of Mammalogy 48(1): 143-144. Scheffer, V.B. 1973 The last days of the sea cow. Smithsonian 3(10):64-67. Scheffer, V.B. 1976 A natural history of marine mammals. Charles Scribners 8c Sons, New York, NY. 130 pp. Shikama, T. and D.P. Domning 1970 Pliocene Sirenia in Japan. Transactions and Pro- ceedings of the Palaeontological Society of Japan. New Series 80:390-396. Stejneger, L. 1887 How the great northern sea-cow (Rytina) became exterminated. American Naturalist 21(12):1047-1054. Stejneger, L. 1936 Georg Wilhelm Steller: The Pioneer of Alaskan Natu- ral History. Harvard Press, Cambridge, MA. pp. 353-357.' Steller, G.W. 1751 De bestiis marinis. Acad. Sci. Imp. Petropolitanae, Novi commentarii 2:289-398. Whitmore, F.C., Jr. and L.M. Gard,Jr. 1977 Steller's sea cow (Hydrodamalis gigas) of late Pleistocene age from Amchitka, Aleutian Islands, Alaska. Geological Survey Professional Paper 1036, U.S. Government Printing Office, Washington, D.C. 19 pp. plus 8 plates. XIV The Gulf of Alaska Section 1 Introduction Physical Setting and Scientific History 1 Donald W Hood School of Oceanography University of Washington Friday Harbor, Washington Roll on, thou deep and dark blue ocean - roll! Ten thousand fleets sweep over thee in vain; Man marks the earth with ruin - his control Stops with the shore. Lord Byron (1788-1824) Introduction Though ten thousand fleets, both peaceful and war- minded, may fail to change powerful ocean processes, the collective waste-making capacity of nearly five billion people who impact earth's shore does make inroads. No longer can man's indiscriminate use of earth's resources be ignored. It is the responsibility, and privilege, of marine scientists/philosophers to explore and understand how the natural processes of the ocean function — and to share their understanding with ocean users and managers. As a highly emotional and often irrational being, man tends to follow the swing of a giant pendulum in extremes of attitude towards environmental issues. Compare, for instance, the historically unregulated exploitation of marine mammals with today's general moratorium on their use. Or compare the nearly uncontrolled ocean dumping of wastes in the past with some of today's tightly restrictive practices. Clearly, well-informed management of earth's resources is needed to avoid the mistakes that are both environmentally and economically costly. Under utilization can be as inexcusable as over utilization if it is at the expense of other resources. Sir Francis Bacon wrote, "Nature, to be commanded, must be obeyed."3 But man is often unwilling or unprepared to obey. Much of the problem rests with our limited understanding of how nature works. An in-depth understanding requires insight, perseverance, and the resources required to investigate. The particular challenge of understanding how the ocean functions requires a long-term commitment on the part of highly skilled scien- tists who must often cross conventional disciplinary bound- aries in applying the most advanced technology towards goals not always discernible to the unskilled. The terms 'mission oriented' or 'applied research' have evolved to describe research which is financed by industrial or government entities seeking to further specific goals. These terms reflect society's skepticism concerning investi- gations proposed "merely for the sake of knowledge." Fre- quently the limited perspective of these 'mission-oriented' studies has resulted in a less than adequate understanding of ocean processes: studies have often been incomplete, parochial in scale, or have been inadequately or improperly reported. It is curious how goals that sidestep basic under- standing can be justified in studying an ocean that works as an integrated system. A case, perhaps, of trying to command without a willingness to obey This book attempts to provide a comprehensive and inte- grated summary of the available oceanographic data from sources encompassing not only the historic and traditional literature, but also unpublished reports and material from relevant disciplines of natural science. This introductory chapter provides an historic and scientific framework for the Gulf of Alaska, intended to orient the reader toward the subject matter that will follow. Initially, prominent geo- graphic and oceanographic features of the Gulf of Alaska are discussed, then geographic orientation, maps, and descriptions of each region are provided. To lend perspec- tive on the historical development of scientific knowledge, a background summary describing the course of scientific inquiry — beginning with the early period of discover) and settlement — is provided. Then, the exploratory and early development phases of research in the region are summa- rized. Finally, the chapter closes with a section reflecting on the present level of understanding of this region and sug- gesting areas of research which might be undertaken to enhance our understanding and use of the Gulf of Alaska. Prominent Geographic and Oceanographic Features The topography along the Gulfs continental margin is extremely irregular, reflecting both tectonic and glacial influences. It includes many of the most spectacularly scenic coastal features on the North American continent. Contrib- Introduction uting to the overall beauty of the region are such areas as the Misty Fjords National Monument near Ketchikan; Glacier Bay National Park and Preserve in the northern panhandle; the prominent scenic Mendenhall, Muir, Malaspina, and Columbia Glaciers; glacial fjords such as Tracy and Endicott Arms, Taylor Bav, and the recently glacially blocked Russell Fjord; and many mountainous islands and other coastal vis- tas, such as Mount Pavlof on the Alaska Peninsula. Dominat- ing the coastal horizon of the northeast Gulf, whether seen bv air or by sea, are the imposing mountain peaks of Mount Fairweather (4,663 m), rising abruptly from Glacier Bay, and Mount St. Elias (5,489 m) near Icy Bay. As one of the most active meteorological regions on earth, the coastal area is characterized by a very severe and variable climate, caused primarily by the passage of storm systems along a well-defined Aleutian storm track. Domi- nant and often severe winds gust from the south along the eastern Gulf, prevail easterly in the central Gulf, and are highly variable from the western Gulf near the Aleutian Islands and associated mountain ranges. The area is fre- quented by ocean storms with wave heights of seven or more meters — as severe as any in the Northern Hemisphere (Brower, Diaz, Prechtel, Searby, and Wise 1977; Danielsen, Burt, and Rattray 1957). In these waters, catastrophic losses to shipping have been common and are well documented (McDonald 1984). A most notable disaster was the sinking of the S.S. Pennsylvania in January 1952. The ship went down with 45 men aboard in an unusually severe storm with gale winds of nearly 60 kt and wave heights of 15 m (Danielsen et al. 1957). Storm prediction in the Gulf is particularly complicated, partly owing to lack of sufficient weather reporting stations but also to the configuration of the coastal mountain ranges. Many storms stall for periods of days and sometimes dissi- pate within the Gulf. Ocean temperatures in the winter are generally warmer than the surrounding land masses, lead- ing to persistent fog coverage. Annual precipitation is about one meter, although combinations of more than eight meters of rain and snow are not uncommon in the coastal mountains (Wilson and Overland, Ch. 2, this volume). Coastal runoff finds its source in the snow and ice stored in the Alaska coastal ranges, together with high but variable rainfall. This runoff causes salinity gradients which drive the Alaska Coastal Current, a current that extends from British Columbia, Canada to Unimak Pass in the Aleutian Islands. Such currents are rare in the world's oceans but may be duplicated off the Norwegian coast (Reed and Schumacher, Ch. 3, this volume). Flow in the Alaska Coastal Current is between 0.1- and 1.2 x 106 m3/s at speeds of 13 to 133 cm/s; maximum values occur in the early fall near the Kenai Peninsula. Formed by the bifurcation of the North Pacific Current near 50°N, the Alaskan Current lies offshore from the Alas- kan Coastal Current and is the dominant transport system of surface waters in the Gulf. Its movement parallels the shelf break at velocities between 30 and 100 cm/s, with high- est speeds observed west of Kodiak Island where it becomes the Alaskan Stream, as the width narrows from about 400 km in the east to 100 km in the west. In contrast to the upwell- ing situations off the coast of the western United States, downwelling occurs in the Gulf of Alaska when dominant easterly winds converge the surface waters near the shore (except for short periods of the summer when weak west- erlies occur). On casual observation it would appear that the downwell- ing effect of cross-shelf coastal transport and subsequent sinking would cause the depletion, rather than the supply, of nutrient-rich deeper waters to the productivity regime of the continental shelf. Other physical processes, however, provide a very rich environment for the support of abun- dant and diverse biological species in most regions of the Gulf (Sambrotto and Lorenzen, Ch. 9, this volume). Another important feature of the Gulf that influences the circulation and transport of its waters is the persistent occur- rence of an atmospheric low over the Gulf during the winter, which causes a cyclonic gyre in the wind system. This leads to a divergence in Ekman transport, causing onshore transport of surface waters near the coast and upwelling in the central Gulf. Favorite (1970) estimates a five-fold increase in the circulation of the central gyre between sum- mer and winter based on wind-stress transport. The system is driven when dry, cold, Arctic air masses from the continents flow out over the warm Gulf waters where heat and moisture are rapidly exchanged. Most pro- nounced in winter, the heating leads to vertical convection with attendant horizontal divergence and cyclonic vorticity. This major atmospheric influence, coupled with other phe- nomena, resupplies surface nutrients to the highly produc- tive continental shelf and coastal regions on both an annual and seasonal basis. The deep waters of the Gulf of Alaska contain the world ocean's most developed oxygen minimum zone and the highest concentrations of dissolved silicate, phosphorus, and nitrate (Mantyla and Reid 1983). As is the case elsewhere in oceanic deep water, the oxygen and nutrient concentra- tions result from the decomposition of surface-fixed organic matter. The concentrations differ markedly, how- ever, and do not result from higher productivity in the sur- face waters. Rather, the cause is the slow circulation of deep waters from other oceans which enter the Gulf of Alaska. The Gulf contains the oldest abyssal waters in the world ocean in terms of the greatest distance removed from bottom-water formation and ventilation (Reeburgh and Kipphut, Ch. 4, this volume). Nutrient concentrations that do not usually occur above the 1,000-m depth in the North Atlantic Ocean, for example, may be found at less than 250 m in the Gulf of Alaska (Hood 1978). Controlled by movement of the Pacific Plate in a north- northwesterly direction at speeds of about 5 to 7 cm/y, the Gulf of Alaska region is tectonically one of the most active in the world. The Pacific Plate is outlined along the Aleutian Trench by seismic zones which dip to 250 km beneath the Alaska Peninsula, Cook Inlet, and Prince William Sound. Movements of the Pacific Plate manifest themselves in numerous earthquakes, some of which reach extraor- dinarily high magnitudes about once each century (e.g., Mw = 9.2 registered by the Great Alaskan Earthquake of 1964, one of the largest ever recorded worldwide; see Jacob, Ch. 6, this volume). Local devastation caused by shaking, subsi- dence, landslides, avalanching, seiches, and soil liquefaction PlIYSK A.I Si I !IN(, AND S( IINIIIK HlSIOKV is accompanied by tsunamis that can strike as far away as California, Hawaii, and Japan. Volcanic eruptions are also frequent, the most recent occurring at Mount Augustine in lower Cook Inlet in March 1986. Although the long-term geomorphic evolution of the Gulf of Alaska basin has been controlled by tectonism (localized uplift of up to 15 m occurred during the Great Alaskan Earthquake of 1964), the modern seafloor owes its geomorphology more to glaciation than to tectonism. Grounded ice extended to the shelf break at least once dur- ing Pleistocene time, covering most of the shelf and sculp- turing broad flat banks and deep elongated troughs. During the advance of the ice cover, glacial-marine and glacial-fluvial sediments were deposited on most of the shelf. After the ice retreated, the area was inundated by the sea, and gradually the present environment was established. Remnant glaciers, aided by a few large rivers, still contribute a heavy sediment load to the coastal regions. A strong ver- tical gradient of suspended sediment exists over much of the shelf. Surface coastal waters are often so heavily loaded with suspended sediments that they limit light transmission and thus inhibit primary production. This is particularly true in embayments and glacier-fed fjords. Since sediment distribution varies widely throughout the Gulf (Hampton, Carlson, Lee, and Feely, Ch. 5, this volume), an understand- ing of the complex sedimentary processes can be gained only through careful study on a region-by-region basis. Primary production — the dominant source of energy for biological systems of the marine environment — is very high in the Gulf of Alaska when compared with other oceanic regions. In some coastal regions, such as lower Cook Inlet and the Kenai shelf, daily values of over 7 g C/m2 have been measured and annual values over 300 g C/m2y have been estimated. Frequent storms, high tidal energy, and per- sistent currents appear to be the primary mechanisms that enhance vertical mixing along the coastal shelf. This mixing supplies essential nutrients to the euphotic zone in support of high production throughout the summer season. In the central oceanic region of the Gulf, yearly production may exceed 100 g C/m2. Here productivity is not limited by nutrient supply (which always remains high in the euphotic zone), but by herbivores. Zooplankton, in particular, can graze down enough phvtoplankton to result in chlorophyll a values in the water column of less than 1 mg/m3 (Sambrotto and Lorenzen, Ch. 9, this volume). Zooplankton abundance varies both geographically and seasonally. In the open ocean, at Ocean Station 'P', abun- dance values ranging from 1.5 g/m2 in winter to 30 g/m2 in summer have been observed. In the deep (>900 m) coastal waters of Prince William Sound, values ranged from 1,320 g/m2 in winter to 1,600 g/m2 in summer. Zooplankton pro- duction on the shelf probablv does not exceed 60 g C/m2y, resulting mostly from growth of 30 dominant species (Coonev, Ch. 10, this volume). Phvtoplankton production in the temperate, fertile waters of both the continental shelf and the coastal regions of the Gulf provides the basic energy that supports a varied and abundant pelagic and benthic biological community. Probably the most intensely studied area of the entire region is lower Cook Inlet, which includes Kachemak and Kamishak Bays. In all aspects, this large estuary benefits from the interaction of vigorous physical factors such as high tidal currents and supporting offshore conditions (Sambrotto and Lorenzen, Ch. 9, this volume). These factors lead to an unusually rich biological regime. While lower Cook Inlet owes much of its source of energy to high primary production (7.8 g C/m2d from May to August), allochthonous carbon is also derived from both land runoff and coastal macrophytes. This contribution to the benthic detrital load amounts to an annual contribution of 60 gC/m2 in Kachemak Bay, 17 gC/m2 in the central Inlet, and 40 g C/m2 in Kamishak Bay. Because of the vigorous cur- rents and coarse bottom sediments here, most of the macro- benthic biomass (52-400 g C/m2) is contributed by suspen- sion-feeding benthic organisms dominated by echinoderms and mollusks. Other areas which have been examined in detail — such as the eastern shelf of the Kodiak Archipelago — show a somewhat lower benthic biomass but are still rich in epifaunal organisms, particularly Tanner crabs (Feder and Jewett, Ch. 12, this volume). The Gulf of Alaska contributes significantly to the world fisheries. It is the main oceanic habitat for most North American salmon stocks, as well as for some Asian stocks, for a significant part of their life cycles. Salmon constitute about 95% of the large epipelagic fish caught in offshore waters, leading all other species in economic importance (Rogers, Ch. 15, this volume). Major fisheries for demersal species include those for Alaskan pollock, sablefish, Pacific cod, Atka mackerel, flatfish, Pacific ocean perch, and halibut. Except for Pacific ocean perch, the present catch of all spe- cies appears to be stable or on a slight increase, yielding a total annual combined catch of about 3.6 x 105 metric tons. A relatively new fishery for Alaska pollock in Shelikof Strait is on the incline and is expected to increase the total annual catch in the Gulf significantly. This, however, must occur in face of a severe decline in the shellfish fisherv. King crab catch in Kodiak was 9.07 x 103 mt in 1980 but had fallen to 50 mt in 1983, and the shrimp catch reached a high of 5.23 x 104 mt in the northern Gulf in 1972, but had declined to 5 x 103 mt in 1982. The 'boom and bust' nature of fisheries in the Gulf of Alaska is closely associated with several environmental fac- tors. Our inability to predict potential harvests (a failing of fishery biologists throughout history), is well illustrated in the Gulf of Alaska fishery (OCSEAP Staff, Ch. 14, this vol- ume) and indicates our continuing lack of an overall under- standing of oceanic processes. Marine birds and mammals abound in the Gulf. Over 20 million waterbirds visit the deltas of the Copper and the Ber- ing Rivers to fatten up and rest during spring migration. Dominant species include the western sandpiper, dunlin, and northern pintail duck — a favorite of waterfowl hunters. Over nine million seabirds representing 26 species nest in the Gulf, making it one of the largest marine bird resources in the Northern Hemisphere (DeGange and Sanger, Ch. 16, this volume). This combination of birds forms an important group of apex predators in the food chain. They consume ~ Introduction 8.3 x 105 mt of their prey in nearshore and shelf habitats and 2.5 x 10"' mt of prey in the oceanic habitat during the 120-day summer season. The rich and diverse inventory of marine mammals includes seven species of large cetaceans, 12 medium and small cetaceans, six pinniped species, and one marine mus- telid (Calkins, Ch. 17, this volume). These animals use the Gulf as a migratory corridor, as summer feeding grounds, or as a year-round range. All seven species of great whales that inhabit the Gulf for some part of the year are on the endangered species list. The gray whale now appears to be reaching pre-exploitation population levels, although the Pacific right whale is at such low levels that recovery is uncertain. The marine mammals' food-consumption rate is estimated to be 7.8 x 106 mt/y, about 10 times that of birds or eight times the amount of car- bon taken in the ground-fish harvest. Areal Description The northeastern extremity of the Pacific Ocean, bor- dered bv the mainlands of British Columbia and Alaska, had not yet been identified as the Gulf of Alaska at the time that a now-classic volume, The Oceans, was published (Sverdrup, Johnson, and Fleming 1946). In early Russian history the waters bounding southern Alaska were known as Alaska Bay. This region — now recognized as the Gulf of Alaska — can be designated as lying north of 52°N and between about 127°30'W on the east, where it meets the British Columbia coast, and 176° W on the west, near Great Sitkin Island in the Aleutian Islands. The arc formed between these longitudes by latitude 52°N extends nearly 3,600 kilometers. Its most northern extension is at about 62°N in Cook Inlet, near the city of Anchorage (note inside front or back cover for a detailed map of the Gulf of Alaska). Included within these boundaries are the southern coast of most of the Aleutian Islands, the coast and offshore islands south of the Alaska Peninsula, (including the Shum- agin and Kodiak Island groups), Cook Inlet, Prince William Sound, and the Alexander Archipelago. The area of the Gulfs continental shelf is estimated to be 3.69 x 105 km2 (107,536 nmi2) (Lynde 1986), which is 16.9% of the entire Alaskan shelf (2,860,000 km2 total) (McRoy and Goering 1974) or equivalent to 12.5% of the total continental shelf of the United States (3,860,000 km2 total). Regions of the Gulf of Alaska Literature on the Gulf of Alaska is not consistent with respect to the boundaries that have been used to delineate regional areas. Standardized regional designations would not only reduce uncertainties for the reader, but they would allow investigators to compare data on an equal areal basis. In the absence of an existing set of regional areas, descrip- tive standards for the following four regions are defined here as a framework of reference for material presented in this book: 1) The western Gulf of Alaska begins at 176°W longi- tude, near Great Sitkin Island, and extends eastward to Cape Igvak on the west side of Shelikof Strait at 153°3'W longitude and 57°25'N latitude (Fig. 1-1). 2) The central Gulf of Alaska extends from Cape Igvak eastward to Cape St. Elias at 144°37'W longitude and 59°48'N latitude (Fig. 1-2). 3) The northeastern Gulf of Alaska (NEGOA) lies between Cape St. Elias on the west and Cape Spencer at 136°38'W longitude and 58°18'N latitude (Fig. 1-3). 4) The southeastern Gulf of Alaska extends from Cape Spencer on the northwest to 52°N latitude on the Canadian mainland, near the south end of Queen Charlotte Island (Fig. 1-4). The International North Pacific Fisheries Commission (INPFC) has designated specific areas within the 200-mile Fisheries Conservation Zone (FCZ) as fisheries management areas (Forrester, Bakkala, Okada, and Smith 1983). The INPFC partitions shown for the coastal area of the Gulf of Alaska in Figure 1-5 generally correspond to those regions listed above for the entire Gulf. Differences (other than the 200-mile limitation) are that the western Gulf region is equivalent to Areas 7B and 7C combined, except for a por- tion of 7B which falls into the Central Gulf region. The INPFC areas have been further classified into shelf regimes according to their distance from shore: inshore (shore to 50 m); inner shelf (50-100 m); middle shelf (100-200 m); and outer shelf (200-1,000 m). The area of each of these divi- sions has been carefully estimated (Lynde 1986); these data, presented in Table 1 -1 , indicate that the total Fisheries Con- servation Zone (FCZ) of the Gulf is 3.69 x 105 km2. The dif- ference between the area of the FCZ as defined here and the area of the continental shelf as given by McRoy and Goering (1974) probably occurs because the FCZ includes only the area to 200 miles offshore, whereas the continental shelf includes all the area to the shelf break. The western Gulf is characterized by steep rugged moun- tains (Fig. 1-6) that descend to the sea, a highly irregular coastline, and many islands and island groups. It includes Unimak Pass, gateway to the Bering Sea, and the Shumagin Islands. The coastline is heavily indented by inlets, fjords, bays, and many natural harbors. Occasional narrow beaches mark shallow-water habitats nestled between predominant stretches of rocky pinnacles and sea cliffs. The continental shelf south of the Alaska Peninsula is about 250 km wide, breaking rapidly to the Aleutian Trench and the abyssal plain (Wahrhaftig 1965). Circulation is dominated by west- erly flow of the Alaska Coastal Current near shore and by the Alaskan Stream near the shelf break. The Central Gulf encompasses the Kodiak Archipelago, Shelikof Strait, Cook Inlet, Prince William Sound, and the Copper River Delta and estuary. Cook Inlet is separated from Prince William Sound by the Kenai Peninsula, and it penetrates the Alaska mainland approximately 370 km toward the Alaska Range and Mount McKinley (6,194 m), the highest mountain in North America. The northern part of Cook Inlet, including Knik and Turnagain Arms, has a tidal range of about 9 m, one of the highest in the world. The Susitna River, with a drainage basin of 68,400 km2 and aver- age flow of 1 ,300 m3/s, is the largest river that drains into the Gulf of Alaska. Combined with the Knik and other smaller Physical Sftting and Scientific History rivers, the Susitna provides large quantities of freshwater that flow in a direction that opposes the tidal flow from the south. The result is strong horizontal stratification in the sys- tem north of the Forelands, with denser seawater occupying the eastern portion. The highly productive southern portion of Cook Inlet is hounded by Kachemak Bay on the east, Kamishak Bay on the west, and Shelikof Strait to the south. The continental shelf in this region is about 220 km wide, reaching to the 600-m depth contour and the eastwardly shallowing Aleu- tian Trench. Here the Alaska Current sweeps westward along the continental shelf parallel to the Alaska Coastal Current which intensifies as it flows toward Shelikof Strait past the Kenai Peninsula and becomes known as the Kenai Current (Reed and Schumacher, Ch. 3, this volume). Although the Copper River is best known as an impor- tant habitat for migrating birds, it is also a major route for anadromous fish between their freshwater spawning grounds and the sea. Prince William Sound, where Captain Cook and his flagship HMS Resolution first landed in the Gulf of Alaska, includes the Columbia Glacier and Port Val- dez, site of the trans-Alaska pipeline terminal. The Great Alaskan Earthquake of 1964 was also centered in this region, at 61°N, 147°30'W, just north of Montague Island. During that earthquake, the land mass southeast of a line between this epicenter and Kodiak Island rose as much as 1 5 m, while land northwest of the line sank as much as 1.5 meters. The northeastern Gulf of Alaska (NEGOA), which derived its designation largely from the Outer Continental Shelf Environmental Assessment Program (OCSEAP), has been the subject of extensive study in recent years due to the interest in oil and gas development. The region encom- passes two of the world's largest individual glaciers, the Mal- aspina and the Bering, as well as many smaller ones that directly enter tidal waters or drain into the coastal domain. The continental shelf in this area narrows to less than 100 km on the east. The offshore currents are northerly in the east (as a result of bifurcation of the North Pacific Current), and then they turn westerly near Yakutat Bay. Near the coast, the freshwater-driven Alaska Coastal Current is well established bv the time it flows north past Cross Sound (Rover 1982). ' The southeastern Gulf of Alaska, consisting mostly of the Alexander Archipelago, is a labyrinth of inlets, passages, and fjords that exist among hundreds of forested islands. An annual rainfall of 100 to 200 inches ( — 2.5-5.1 m) is common in this region, and North America's largest icefields supply the many glaciers that empty their meltwater and sediments into the coastal regime. Currents offshore are northerly along a continental shelf that is less than 100 km wide. The oceanography of this complex region has received relatively little study. Exploration and Early Human History The first European to see the Pacific Ocean was Balboa, who claimed it for King Ferdinand of Spain in 1513 and named it the South Sea because of the orientation of the coast from which he observed it. Before Balboa's explora- tion there was little information written or transmitted about the Pacific Ocean, despite the substantial knowledge that had been acquired by the Japanese, Malayans, Polyne- sians, Incas, and Aleuts. Ferdinand Magellan was the firsl explorer to navigate around the world and, in 1581, became the first European to sail into the North Pacific. The next circumnavigator. Sir Francis Drake, explored the northwest coast of North America in 1578 as far north as the present state of Washington and claimed the west coast, which he called New Albion, for Queen Elizabeth. After an initial voyage through the Bering Strait in 1728, Vitus Bering made The Great Northern Expedition in 1741, sailing aboard the St. Peter as far east as Cape St. Elias and landing on Kayak Island (Colder 1922, 1925). Meanwhile, the sister ship St. Paul, under the command of Lt. Alexsei Chi- rikov, became separated from the St. Peter and sailed to the lower tip of the Alexander Archipelago. This completed the discovery of the North American continent. Some of the additional voyages made into the North Pacific during the discovery period included those by: Bezerra and Grijalva, 1532; Valle, 1536; d'Ulloa, 1539; Cabrillo, 1542; Mendaha, 1567-1569; Cavendish, 1586-1588; Mendaha and Quiros, 1595-1596; Quiros, 1605-1606; Spilbergen, 1614-1617; Hamel, 1653; Nowosilzoff, 1745; Byron, 1764-1766; de Pages, 1767; Wallis, 1766-1768; Carteret 1766-1769; Bragin, 1772; and Hecta and Ayala, 1775. Few of these voyages reached the northeast Pacific Ocean, how- ever, and few had any impact on discovery in the Gulf of Alaska. Additional information on North Pacific expedi- tions is contained in Humboldt (1836-1839), Murray (1895), Beaglehole (1966), and Kenyon (1980). During this early period of geographic exploration, mari- ners were actively seeking out new lands. They plotted the locations of islands and continental coastlines and described the hydometeorological conditions they encoun- tered. At the discretion of the ship's captain, data important to navigation were often entered into the ship's log, includ- ing information on winds, waves, currents, and variations in shoreline heights. Magellan, in the first of manv efforts that would follow, attempted to measure the ocean depth; 2,500 ft (762 m) of manila rope was let out without reaching the bottom. More serious scientific studies of the North Pacific Ocean began in about 1776 with the voyages of Captainjames Cook (Rienits and Rienits 1968), who remains todav (with the pos- sible exception of Lord Nelson) the most famous of British captains. Cook's superb cartography, his acute and accurate observations, and his matchless seamanship set a standard for all to follow. Cook's third voyage, in quest of a northwest passage between Baffin Bay or Hudson Bay and the North Pacific Ocean, first touched the North American continent at 44°33'N, on what is now the coast of Oregon. In his passage at night, Cook failed to discover the Strait of Juan de Fuca, an oversight which afforded his midshipman George Van- couver a later opportunity to explore this region. As he sailed further north, Cook named Cape Edgecumbe, Mount Edgecumbe, Cross Sound, Cape Fairweather, Mount Fair weather, and Mount St. Elias. He anchored to repair his ves- sel, the Resolution, in an area he named Sandwich Sound, now known as Prince William Sound. 10 Introduction Little Tanaga I. ■=%«■ UEUT^N Andreanof Islands Chagulak 10 Figure 1-1. Detailed map of the western Gulf of Alaska. (Map scale 1:3,125,000; approximately 1 inch to 49 miles.) Physical Setting and Scientific History II >UtcMHarbor -.tie** [paUka Vvve oj G« if 165 160 12 Introduction Physical Setting and S( iiniiik HISTORY 13 WRANGELL I Ml Bona 1&421 \fy 140 o -~£ZA I N s m "v. 'icier 'acirr ~8 iM.sm* , Ba«'ey '«**> \ f * 10619 mi M a A: r.W- — .X «/. Seward Glacier fkTl I ' ?*/ \^\ f— Ml. Hubfiard^—- ,;Mi Cook -\ •• ^V, „ ^ V' .13760 A*V •' le„a"'9' O r?\ Yukon Torntorv Mt Armour \ /* l\ . 8770 \ ^ SlV \vlN A \\3.\ ^ $•■ ' Ocean C:api^«Yakutat %:& 3=^ Skagway Figure 1-3. Detailed map of the northeastern Gulf of Alaska. (Map scale 1:3,125,000; approximately 1 inch to 49 miles.) On his journey westward, he explored Cook Inlet before continuing along the Alaska Peninsula to Unimak Pass and into the Bering Sea, also exploring the Bering Strait and Chukchi Sea. This completed the first recorded exploration of the Gulf of Alaska. On returning from the Bering Sea journey, the Resolution called at the village of Unalaska, where Russian fur traders were well established and were able to add detail to some of Cook's charts of the North Pacific coastline. Cook's mariner skills and tenacity provided the information needed to establish the gross features of North American borders. Dur- ing the next one hundred years, scientific investigations became a primary or secondary objective of many subse- quent expeditions to the North Pacific. Detail continued to be added in the course of many voyages, sparked with cour- age and the same curiosity that has advanced our level of understanding to the present bv verifying and correcting existing knowledge (Table 1-2). Among the many voyages that added to our geographic knowledge of the eastern Pacific north of 40°N are two that are notable for their length and thoroughness: that of Ales- sandro Malaspina, an Italian who sailed under the flag of Spain, and that of George Vancouver. Malaspina, with the ships Descubierta and Atrevida, spent 1790 and part of 1791 looking, as had so many others, for a passage into Hudson Bay from the Gulf of Alaska. The scientific discoveries that Malaspina made on this cruise were among the most impor- tant made under the flag of Spain. Vancouver examined the west coast (New Albion) as far as the Alaska Peninsula with the Discovery and Chatham between April 1791 and October 1795 (Anderson 1960). As a result of his meticulous and painstaking efforts, Van- couver's explorations are now ranked among the best ever accomplished. In 1792 he passed through the Strait of Juan de Fuca, discovered the Strait of Georgia, and circumnavi- gated the island that now bears his name. It was during the 1793 exploration of the Alexander Archipelago that a party from the Discovery and Chatham became involved in the first recorded case of paralytic shellfish poisoning near what is now called Carter's Bay in northern British Columbia. After consuming mussels, John Carter, a crewman, died after all efforts to save him failed. Other cases have occurred even to Introduction Queen Charlotte Sound o "BeflaJBejU Figure 1-4. Detailed map of the southeastern Gulf of Alaska. (Map scale 1:3,125,000; approximately 1 inch to 49 miles.) Pi iv sk m Si i mm . \m> S< iiniiik I Iistoky 15 Figure 1-5. Pacific Marine Fisheries Commission and International North Pacific Fisheries Commission management areas for the Gulf of Alaska (from Forrester?/ al. 1983). the present time. Vancouver continued to survey the west coast of America, reaching as far as Cook Inlet in 1794. As a result of Vancouver's work, this very complicated coast became so well documented that the notion of a passage through the continent was dispelled. Early Human History When Europeans first entered the coastal regions of the Gulf of Alaska, they found a diverse native population. Chugachimiut Eskimos inhabited Kodiak Island, the Alaska Peninsula, and northwestern Prince William Sound. The western Gulf region was occupied by Aleuts, who had settled as far east as the southwestern part of the central Gulf shores. Tanaina Indians were the principal inhabitants of Cook Inlet, and Athabascan-speaking Ahtna people were the principal inhabitants of the Copper River basin. The Eyak people were distributed from the Copper River Delta to the eastern part of Prince William Sound, which was also raided extensively bv the Tlingits of southeastern Alaska. Archaeological findings in Kachemak Bay (Yukon Island) indicate that this area was first occupied by Eskimos (from about 1500 B.C. to 1000 A.D.), and then by Athabascan Indians, who were probably ancestors of the Tanaina who moved into the coastal regions from Alaska's interior. The Eskimos of Kodiak Island subsisted primarily on salmon and marine mammals, but also consumed mollusks, cephalopods, and sea urchins when these species were avail- able (Hrdlicka 1941; Allen 1960; and Boucher I960). The great wave of European exploration and exploita- tion touched the Gulf of Alaska with the discovery7 voyage of Vitus Bering in 1741. Bering's discovery of Alaska was quickly followed by conquest and colonization of the entire area by Russia, which occupied the area for 126 years until its cession to the L nited States in 1867. The Russians generally left the aboriginal Alaskans much as they had found them. An exception to this pattern was the Aleut inhabitants of the Aleutian Islands, the Alaska Peninsula, and some western offshore islands. Russian fur traders killed and enslaved many Aleuts in these areas, leaving the Eskimos along the Bering Sea and Arctic coasts, the Tanainas of Cook Inlet, the Athabascans of the central Gulf, and the Tlingits of South- east Alaska relatively undisturbed. Since the Russians were interested only in furs, they did not penetrate far inland and their principal settlements were along the Gulf of Alaska coast. In the spring of 1784 the first Russian colony was founded on Kodiak Island's Three Saints Bay. Hunting parties were dispatched to Prince William Sound and Cook Inlet the following year. In 1792 Table 1-1. Area of shelf regimes, expressed in square nautical miles, of the Gulf of Alaska INPFC fisheries management areas. Values in parentheses represent percent of total area within each INPFC management area (from Lynde 1986). INPFC Inner Middle Outer Total Area Inshore Shelf Shelf Shelf Area Shore-50m 50-100m 100-200m 200- 1,000m 6A 9,823.4a 3,346.9 3,761.1 16,931.4 (58.02) (19.77) (22.21) 6B 2,465.9 1,457.4 9.143.8 3,252.3 16.319.4 (15.11) (8.93) (56.03) (19.93) 7A 12,367.2" 15.483.6 4.000.3 3 1 ,85 1 .4 (38.83) (48.61) (12.56) 7B 1.909.1 6.199.6 6.953.0 2,501.3 17,563.2 (10.87) (35.30) (39.59) (14.22) 7C 2.871.2 8,894.6 10.325.5 2.779.7 24,871 0 (11.54) (35.76) (41.52) (11.18) All 7,246.2 38,742.2 45,352.8 16.294.7 107.536.4 1 Shore !o 11)0 m all considered inner shelf. 16 Introduction Figure 1-6. Probably the first photograph of Mount Pavlof on the Alaska Peninsula (from Harriman Alaska Series of The Smithsonian Institution 1910. Vol. 4). the settlement was moved to the present location of the city of Kodiak. A trading post established at Sitka by the Rus- sian-American Company in 1799 was permanently settled five years later under the name of New Archangel. Other permanent Russian villages include Nikolski, Unalaska, Chernofski, and Belkofski in the Aleutians; and Kasilof, Ninilchik, and Kenai on the Kenai Peninsula. All that cur- rently remains from the Russian period are some sturdy log cabins and a few Orthodox churches with their bulbous stee- ples and double-barred crosses. Alexander A. Baranof, the first Governor of Russian America, was the most important and memorable indi- vidual in shaping early Alaskan history (Chevigny 1965). In 1799 he took possession of what is now called Baranof Island in the Alexander Archipelago. The present town of Sitka is located on the northwest corner of this Island. Here he began developing trade with natives, eventually extending his operations to such distant places as the Hawaiian Islands, Canton (China), Boston, and New York. Baranof died at sea in 1819 while returning to Russia. The Russian governors that followed were of lesser stature and left little mark on Alaska. Under the congressional influence of William H. Seward, the United States Congress purchased Alaska from the Rus- sians in 1867. Although Seward's purpose in promoting this acquisition was to enlarge the United States' strategic hold- ings in the Pacific arena, the congressional focus of interest at the time was on the area's vast resource wealth. For nearly a third of a century following its purchase, Alaska was all but forgotten by the American people. The Russians had left nothing, and the Americans brought noth- ing other than a penchant for furs and whales. Then came the gold rush near the end of the nineteenth century, which marked the beginning of economic interest in Alaska. Dis- criminator)' actions against Alaska as an 'incorporated ter- ritory', however, greatly limited self-government and were especially harmful to marine transportation interests. Until the beginning of commercial air service in 1940, maritime shipping was the only means of transportation between Alaska and the lower 48 states. The Merchant Marine Act of 1920 (also known as the Jones Act after its sponsor, Senator Wesley Jones of the State of Washington) provided for the interchange of domestic or foreign carriers both on land and sea "except for Alaska." Passage of this strange law meant that all shipping in and out of Alaska had to be passed through Seattle before continuing to its destination. The resulting benefit to Seattle was at a very high cost to Alaska's development, because goods transported through Seattle then cost up to five times as much as they would have to or from other points in the Pacific (Gruening 1959). Alaskan statehood in 1958 lifted many of the previous ter- ritorial restrictions, and significant progress began to occur in all areas of human services. Most significant in the marine field was the establishment (by an act of the Alaska Legisla- ture) of the Institute of Marine Science at the University of Table 1-2. Scientific expeditions conducted between 1776 and 1876 in the North Pacific Ocean. Observers listed first are expedition leaders; those listed second are chief scientists. Date Observer Ship 1776-80 Cook, Burney Resolution, Discovery 1785-88 La Perouse Boussole 1791-92 Marchand, Fleurieu Solide 1790-95 Vancouver Discovery 1794 Malaspina Descubierta 1803-06 Krusentern, Horner Nadiejeda, Neva 1815-18 Kotzebue, Lentz Predpriatie 1825-28 Beechey Blossom 1826-28 Lutke, Erman Ssenjavin 1826-29 D'Urville Astrolabe 1831-36 Fitzroy, Darwin Beagle 1836 Vaillant Bonite 1836-39 Du Petit, Thouars Venus 1837-42 Belcher Sulfur 1839-42 Wilkes, Dana Vincennes, Peacock, Porpoise 1843-46 Velcher Samarang 1845-51 Kellet Herald 1850-54 McClure, Armstrong Investigator 1857-60 Wullerstorf Novara 1873-75 Belknap Tuscarora 1874-76 Hensen, Rottok Gazelle 1872-76 Nares, Thomson Challenger Physical Setting and Scientific History V Alaska in 1962. This brought together a skilled faculty, and prompted the development of modern facilities so that work on ocean sciences could be conducted from closer proximity than was previously possible. Scientific History General North Pacific Investigations Aboard the St. Peter with Vitus Bering in command, Georg Wilhelm Steller spent the summer of 1741 as the first trained scientist to examine the flora and fauna of the Ber- ing Sea, Aleutians Islands, and Alaska mainland (Kayak Island). The voyage of the St Peter was dampened by clashes of temperament between an arrogant Steller and the crew, sickness due to scurvy and bad water, and general frustra- tion with the foul weather found in the Gulf of Alaska. Nev- ertheless, Steller grasped his opportunity to describe many new findings, the most notable of which are the Steller's jay, Steller (northern) sea lion, and the Steller sea cow. Steller's hard-won fame rests on his accurate descrip- tions of the sea cow and other marine mammals as pub- lished in his De Bestiis Marinis (Steller 1751). His dissection of a female sea cow in July 1742 represents the only scientific record of this northern manatee except for the few skel- etons that were found years later. Twenty-seven years after its discover)' by the Bering expedition, this magnificent spe- cies was extinct (see Dedication, this volume). After the discovery voyage of Malaspina in 1794 (Table 1-2), greater emphasis was placed on determining oceanographic parameters — especially water depth and temperature. The first extensive oceanographic observa- tions in the North Pacific were made by Kruzenstern on the Sadiejeda from 1803 through 1806. His water temperature measurements down to 400 m and his observations of atmo- spheric pressure stimulated him (25 years later) to prepare an atlas on the northeast Pacific. The Kotzebue-Lentz expedition on the Predpriatie (1815-1818) resulted in the first systematic measurements of water temperature, salinity, density, and oxygen content at depth using a device called the Lentz barometer. The observed decrease in temperature with depth in the low lati- tudes suggested to Lentz (1847) that the direction of flow was towards the equator for the low-temperature water below the surface and poleward in the high-temperature surface water. Continuing these studies, Vaillant observed after many ocean temperature measurements and meteorological observations, that except for areas near the equator, sea sur- face temperatures in the Pacific were frequently higher than air temperatures (Prestwich 1876). It is now known that there is a long-term annual mean difference of about 20C in sur- face temperature between 20 and 60°N, as well as a max- imum mean annual temperature range of about 10C at mid-latitude locations (Kenyon 1980). Although the Challenger Expedition (1872-1876) never reached as far north in the Pacific as the Gulf of Alaska, its general contributions to the science of oceanography justify a brief discussion. As the first systematic interdisciplinary study of the world's oceans, the Challetiger project gathered data that were to set a standard for the oceanographic stud- ies that followed. Of a total of 362 deep-water stations sampled on the expedition, seawater was analyzed for chem- ical constituents at 77 sites (more than half located in the Pacific Ocean). This procedure established the principle of constant relative proportion of the 11 major ions in seawater (independent of evaporation and precipitation) for all the seas, a principle of fundamental importance to modern chemical oceanography. The comprehensive examination of bottom samples ini- tiated on the Challenger Expedition began the science of marine geology and the formulation of a classification scheme for marine sediments. Large amounts of biological material were also collected, especially deep-water animal specimens. Nearshore biological communities were also first observed and catalogued on this expedition. Measurements made by Makarov aboard the Vityaz (1886-1889), together with his organization of all tem- perature data obtained to that time, provided information for the first surface temperature maps of the Pacific Ocean to 45°N (U.S. Hydrographic Office 1878). Makarov (1894) documented the broad geographic distribution of surface water temperatures and densities in the Pacific Ocean. Following the Challenger, several other large oceanographic vessels continued work in the North Pacific until the 1920s. The advent of trans-ocean cables provided a practical impetus for geological studies of the ocean bottom. Likewise, the rapid development of ocean shipping in inter- national trade influenced the applied aspects of physical, biological, and chemical studies of the ocean. During this period, extensive biological studies were conducted aboard the U.S. Fish Commission's steamer Albatross in the North Pacific Ocean as far north as San Francisco Bay and also around the Hawaiian and Philippine Islands. From the work carried out over a period of nearly 40 years on the Albatross, extensive information was obtained about the composition of plankton, benthos, and nekton, including the description of many new species (Albatross 1902-1911). Other expeditions were conducted on the English ship 7>rra Nova and German vessels Eddy, Stephen, and Palanet. Not only did expeditions of this period continue to develop the inventory of biological forms found in the ocean, but they established vertical and geographic distributions for the separate groups of organisms both in the open ocean and along the sea floor. They described the feeding habits of commercially important fishes and marine animals, together with many of the biological interactions between plankton, benthos, and nekton. Physical and chemical meas- urements often accompanied the collection of biological samples, and in this way, ecologically oriented data slowly accumulated. Due to the remoteness of the area, the lack of established shipping zones, and the distance from marine research cen- ters, few of the large oceanographic expeditions to the North Pacific Ocean reached as far north and east as the Gulf of Alaska. None of the major oceanographic expedi- tions reached the Gulf of Alaska (Wxist 1964). Special efforts to investigate this area began with the Northeast Pacific (NORPAC) Oceanographic Program in 1955; however. Introduction many investigations conducted in other parts of the Pacific Ocean were important to future studies of more specific focus on the northeastern area. The 1920s marked a period of detailed study of the world ocean. What had been separate, disjunct, and often inciden- tal expeditions became well-planned, multidisciplinary, sys- tematic investigations. Development of new methodologies and equipment played an important role in bringing about increased understandings in all areas of oceanography, as new underwater devices and methodologies were intro- duced. Prior to the 1920s measurement of such parameters as water depth required several hours using a winch and cable, and therefore only a few soundings could be made. The resulting paucity of data led to the erroneous concept of a flat ocean floor. When sonic devices that could make continuous measurements came into use, however, it was quickly determined that the ocean floor had canyons, ridges, trenches, and seamounts. Important to our understanding of the oceanography of the North Pacific were the expeditions of the American ships Carnegie and Ramapo, the Dutch ship Snellius, the Danish ship Dana, the English Discoverer II, and the Japanese vessels Shintoka Mam and Mansyu Maru. Most of these ships did not reach the northernmost part of the eastern Pacific, nor were their efforts coordinated; but personnel on all ships participated in an interdisciplinary program during 1927 to 1929, which included the study of bottom topogra- phy and sediments, chemical and physical measurements from samples in the water column, and the collection of bio- logical samples at horizontal and vertical intervals. Important discoveries in the 1920s and 1930s included the observations that: 1) phytoplankton depend on nutrients in the euphotic zone for growth and development, and 2) the vertical distribution of plankton is closely related to tem- perature and salinity. Classical work in the ocean, especially that conducted by Cooper (1933) in the English Channel, showed that phytoplankton biomass depends on the amount of plant nutrients in the surface-water column. Geophysical methods such as pendulum gravitational and magnetic measurements were beginning to develop, and description of the hydrographic structure of the ocean was essentially completed (McEwen, Thompson, and Van Cleve 1930; Thompson, McEwen, and Van Cleve 1936; and Sverdrup et al. 1946). During World War II, extensive oceanographic studies were undertaken in support of national defense. The ver- tical thermal structure of the surface ocean water, wave pre- diction, and bathymetric charting of vital areas of the ocean were emphasized. After the war came rapid development of complex data buoy stations and the development of devices that could measure temperature and salinity while the ship was moving, and other devices that could measure both sur- face and deep-water currents. In biological research, trawl- ing techniques were perfected for use at specific depths and many new net systems appeared. The precision of chemical determinations reached 10 |ig/l, both stable and radioactive isotopes found extensive use as tracers, and attention began to focus on trace components in seawater — particularly on dissolved organic matter and heavy metals. Geologists began using echosounders, and magne- tometers, as well as piston corers capable of obtaining sedi- ment cores that reached up to 20 m in length. This period was capped with three around-the-world expeditions which passed through the Pacific Ocean: the Swedish Albatross (1947-1948), the English Challenger II (1950-1952), and the Danish Galathea (1950-1952). These expeditions determined the direction of geological investigations for subsequent expeditions by revealing that the relatively shal- low depths of the sediments (only a few hundred meters) were many times less than had been theoretically estimated. Together with information provided by work aboard the American vessels Midpacific and Capricorn, these studies showed that the earth's crust beneath the Pacific Ocean is only 5 to 9 km thick as compared with the continental crust of between 30 and 40 kilometers. On these same expedi- tions, specimens of many bottom-dwelling and fossil fauna were obtained from submarine plateaus and trenches, giv- ing heavy support to the field of paleontology. Gulf of Alaska Investigations Oceanographic work occurred in the northeast Pacific even though none of the classical large scientific expedi- tions reached as far North as the Gulf of Alaska (the Carnegie came closest, north of 50°N at 155°W). Many of the ships involved with research in the Gulf, the institutions that oper- ated them, the period of investigation, the size of the vessel, and an indication of the kind of work accomplished are listed in Table 1-3. Despite these efforts, the number of oceanographic stations sampled north of 58°N and east of Kodiak Island between 1926 and 1969 was very sparse, as indicated in Figure 1-7 (Royer 1972). Activity has greatly increased since that period, largely as a result of the Outer Continental Shelf Environmental Assessment Program which began in 1974. The most significant research effort in the Gulf during the late nineteenth century was undertaken by the Har- riman Alaska Expedition (1910), which occurred duringjune and July 1899. Organized by E.H. Harriman of New York City and conducted at his expense, the expedition was planned originally as a holiday excursion for the Harriman family and a few friends interested in hunting. The plan was enlarged to include scientific work and later modified fur- ther to give the scientific group practical control of expedi- tion details such as the route (Fig. 1-8) and other details affecting their work. Participants included 25 scientists rep- resenting a wide range of specialties such as ethnology, zool- ogy, botany, geology, and geography. Among the scientific party were persons now well-known in Gulf of Alaska his- tory: Dr. W.H. Dall, Mr. John Muir, Prof. B.K. Emerson, Dr. C. Palache, and Prof. W. Trelease. Much of the cruise was spent near the coast, with almost daily landings of shore parties. From this expedition came much of the early marine-science literature on the coast and on the major island features of the Gulf of Alaska. Docu- mentation of various scientific aspects, with an emphasis on biology and geology, was published in 13 volumes by the Smithsonian Institution (Harriman Alaska Expedition 1910). Pi i>m< al Setting and Scientihc Hisioky 19 From the tiraeoftheHarriman Expedition until 1955, the bulk of field research in the Gulf was undertaken by the Bureau of Commercial Fisheries (now the National Marine Fisheries Service) using the vessels Albatross I and // (Fable 1-3); the Fisheries Research Board of Canada, Pacific Oceanographic Group using the vessels Cedarwood and Ekhon; the Faculty of Fisheries, Hokkaido University using the vessels Ryofii Maru and Oslioro Maru II; and the University of Washington using the vessels Broom Bear and John Cobb. Independently, the Soviets undertook a major oceanographic program in the western North Pacific aboard the Vitiaz (1949-1965). The results of biological stud- ies conducted on the more than 40 cruises of the Vitiaz in the northern Pacific Ocean during this period constitute a major part of our knowledge of the area; both the quantity and the variety of data obtained during these surveys are probably unexcelled in the annals of oceanography (Moiseev 1955-1970). In 1965, major oceanographic studies of the coastal Gulf of Alaska were undertaken by the University of Alaska using the Acotm. Among these studies were the first ever made in Cook Inlet, Prince William Sound, and the Alexander Archi- pelago. In 1971, the Acona established the long, trans-Gulf of Alaska section line (GAK) south of Resurrection Bay. Infor- mation obtained with each succeeding oceanographic cruise along this transect has made the GAK line increasinglv valuable to broad-scale Gulf studies. The first documented physical oceanographic studies in the Gulf of Alaska were done for the International Fisheries Commission in 1927-1929 by McEwen et al. (1930). The sta- tion lines for the three cruises are given in Figure 1-9. In 1927, data were collected only at Stations 1 through 6 on the Ocean Cape section; in 1928 all lines were extended into the Gulf of Alaska. Salinity and temperature data obtained in Januarv, during the halibut spawning season, delineated three water classifications: 1) coastal water having salinities of 32.5°/(x) or less and temperatures of less than 5C, 2) inter- mediate water with salinities between 32.5 and 33.8°/oo and a temperature maximum, and 3) ocean water with salinities greater than 33.8°/oo and temperatures between those of coastal and intermediate water types. This work was continued by Thompson et al. (1936), who deduced from dynamic-height computations that flow is generally westward in January with a maximum speed of one knot immediately off the continental shelf. Further cur- rent studies bv Thompson and Van Cleve (1936) through drift-bottle experiments, elucidated the general directions of surface drift, but there was little information on flow rate because of the lag-time uncertainty connected with bottle recovery. The next significant studies in the Gulf did not occur until 1954, the beginning of a surge of activity that continued until 1959 (Figure 1-7). This period included NORPAC stud- ies and studies carried out during the International Geo- phvsical Year (IGV). Research by University of Washington personnel aboard the Brown Bear mid John Cobb in the north- east Pacific Ocean is summarized in Dodimead (1961), Favor- ite and Love (1957), and Bennett (1959). Unfortunately, except for a Februarv 1957 cruise (Dodimead 1958), data were collected only during the summer months. Analyses of these and other data collected during this period appeared regularly in the literature. A description of the dynamics of the halocline was reported bv Fleming (1958). Oceanogra- phy of the region was reviewed bv Fleming (1955) and Dodimead, Favorite, and Hirano (1963). Using data from the Oslioro Maru III and other sources, Uda (1935, 1963) began extensive studies of the ocean as related to fisheries. Tully and Barber (1960) forwarded the far reaching concept of estuarine circulation— fresh water from the coast invades the deep ocean water much like rivers in an estuary — for the subarctic Pacific Ocean. Dodimead (1958) published some of the first data on surface concentrations of phosphate, nitrate, and silicate anionic nutrients. Although another hiatus in Gulf cruise activity occurred during the 1960s, many important contributions to oceanographic understanding appeared in the literature. El Wardani (1960) described the organic/inorganic distribu- tion of phosphorus; and Stephens (1964) reported on stud- ies of primary productivity as related to chemical and phys- ical parameters at Station P (50°N, 145°W). Studies of minor components of seawater also began to appear in the liter- ature during the 1960s and 1970s. Bogdanov (1965) reported on Russian studies of suspended organic matter; Loder (1971) described extensive studies of both dissolved and par- ticulate organic matter; and Natarajan (1968) discussed the distribution of thiamine, biotin, and niacin. Data on trace metals were published by Ali, Burrell, and Wood (1969), who examined the zinc distribution in fjords; Burrell and Hadley (1970), who described the partitioning of trace metals between solid and liquid phases; and Wood (1971), who reported on the chemical forms of gold in seawater. Shellfish toxicity studies gained prominence with Schantz's (1965) research on the chemical structure of para- lytic shellfish toxin and Chang's (1971) ecological study of the distribution of toxic butter clams. The first oceanographic studies of Cook Inlet (Hood, Natarajan, Rosenberg, and Wallen 1968) and of Prince William Sound (Hood 1969) also occurred during this period. Reid (1962) made one of the earliest analyses of the relationship of circulation, nutrients (phosphate), and biological populations (zooplankton); and Roden (1969) considered the wintertime circulation in the Gulf of Alaska. In the mid-1970s, a new surge of oceanographic activity occurred in the Gulf — an involvement far more intense than any previous level of research. Pressure to develop potential oil and gas fields on the outer continental shelf, along with a strong mandate from the U.S. Government dur- ing the Nixon and Carter administrations to become energy independent, led to an oil and gas leasing program in the Alaskan outer continental shelf. Because it is the responsi- bility of the Department of Interior to protect the marine environment from adverse effects as a consequence of oil and gas development, the Bureau of Land Management (BLM), in May 1984, requested the National Oceanographic and Atmospheric Administration (NOAA) to initiate an environmental assessment program in the northeastern Gulf of Alaska. Later that year a major expansion of the pro- gram occurred in order to respond to additional sales on the Aleutian shelf, near Kodiak, and in lower Cook Inlet in the 20 Introduction Table 1-3. Sonic vessels used in occanographic research in the eastern North Pacific Ocean from 1880 to 1980. \ \\n ok Vessel Nationality or Institution Period of Tonnage or Speciality Study (Length) Jamestown Albatross Hassler Patterson McArthur Pathfinder Concord Elder Carnegie Catalyst Ekhon Cedarwood E. W. Scripps Ryofu Mar u Albatross II Garnet Oceanographer (formally Corsair II) Hydrographer Explorer George B. Kelez Oregon Horizon Spencer Baird Stranger Commando Brown Bear John N. Cobb \ itiaz Oshoro Maru III Oshoro Maru IV Acona Cayuse U.S. Navy U.S. Fish Commission Coast and Ceodetic Survey U.S. Navy Individual E.H. Harriman U.S.A. University of Washington 1880 1,150 1882-1921 1,075 1928-1929 Fisheries Research Board of Canada 1936-? 1950-1952 Surveyed Sitka Harbor Marine biology 1872-1895 (159.5 ft) Coastal survey of Alaska Fox Islands survey in Aleutians 1894-1920 1,710 1899 568 1928-1938 (75 ft) Scripps Institute of Oceano graphy 1937-1955 140 Japanese 1937-1955 1,206 U.S. Bureau of Fisheries 1926-1934 (150 ft) U.S. Navy Summers 1926-1935 950 Coast and Geodetic Survey 1938-1944 1,600 (304 ft) Coast and Geodetic Survey 1931-1966 1,044 Coast and Geodetic Survey 1939-1944 1,900 NMFS 1944-1966 760 (176 ft) NMFS 1946-1984 219 (100 ft) Scripps Institute of Oceano graphy 1948-1969 900 Scripps Institute of Oceano graphy 1952-1965 997 Scripps Institute of Oceano graphy 1955-1962 405 University of Washington/ Bureau of Commercial Fish eries 1950- (65 ft) University of Washington 1950-1965 270 Bureau of Commercial Fish eries 1950- (-90 ft) U.S.S.R. 1957-1967 5,700 Japanese 1962-1983 1,180 Japanese 1983- University of Alaska 1963-1980 (85 ft) Oregon State University 1967 (80 ft) Fur seal studies and protection Biology and geology of the coast of Alaska Physics, biology, sediments Trans-Pacific north of 40°N Oceanography of Puget Sound Fisheries Assessment Oceanography Oceanography of Puget Sound Physics Hydrography and chemistry Gulf of Alaska Areal survey support Gulf of Alaska Surveys and Survey charting off Alaska Hydrographic surveys Aleutian Islands Hydrographic surveys in Aleutian Islands Fisheries oceanography Fisheries assessment Oceanography of North Pacific Ocean Oceanography of North Pacific Ocean Oceanography of North Pacific Ocean Coastal biology Oceanography of Gulf of Alaska Fisheries research Detailed oceanographic cruises in North Pacific Ocean Fisheries oceanography Fisheries oceanography Coastal oceanography Coastal oceanography Physical Sftting and Scientiik Histoky 21 Namf Oh Vksskj Nation \i m ok INSTITUTION Pkriodot Tonnac.i- or Study (Length) Si'k lAi.m Alpha Helix University ol Alaska 1965- (125 ft) Miller Freeman NMFS 1967- 1,920 Surveyor NOAA 1960- 3,440 (heatwgraplier NOAA 1966- 3,959 (303 ft) Mum NMFS 1965- (78 ft) Thomas G. Thompson University of Washington 1965- 1,362 (208 ft) Hakuro Main University ofTokyo 1969- 3,200 Melville Scripps Institute of Oceanogi aph\ 1969- 1 ,806 Coastal oceanography Fisheries research Survey and support of OCSEAP Oceanography and support of OCSF.AP Coastal fisheries Oceanography of North Pacific Ocean Some cruises to North Pacific Ocean and Bering Sea OEOSECS cruise 1949 1951 1953 1955 1957 1959 1961 1963 1965 1967 1969 Figure 1-7. Oceanographic stations sampled per year, by quarters, north of 58°N and between 130° and 150°W (from Rover 1972). Gulf of Alaska. It was out of this joint BLM/NOAA research initiative that the Outer Continental Shelf Environmental Assessment Program (OCSEAP) was created. The pattern of leasing in the Gulf dictated the location and timing of OCSEAP studies. The disciplinary content and geographical intensity of the study program was heavily influenced by the 'need to know' as determined by local issues. As a result, a large data base was obtained in the NEGOA sale area, Kodiak area, and in lower Cook Inlet. Rel- atively little work was done, however, in areas of low inter- est, such as Shelikof Strait, the southern Aleutian shelf, Yakutat, or in the southeastern Gulf of Alaska. OCSEAP studies provide much of the subject matter for this book and will be treated in detail in the disciplinary chapters that fol- low. The abundance of data which resulted, though uneven in both geographic and disciplinary coverage, contains a wealth of information that is useful in building an under- standing of the oceanography of the Gulf of Alaska. In each of the chapters which follow, the authors have drawn heavily upon OCSEAP data as well as other sources in an attempt to synthesize all of the available information into a single, coherent document which describes our present level of knowledge of the Gulf of Alaska. The Status of Science in The Gulf of Alaska Far out of the usual path of oceanographic ships and remote to shore-based laboratories, the Gulf is rendered even more inaccessible by persistent heavy seas and fog cover. As a result, it has received relatively little scientific attention in comparison with other parts of the world ocean that are similar in size and importance. Even the neighbor- ing Bering Sea, also inhospitable to man, has fared better in terms of documentation of scholarly findings; the eastern continental shelf of the BeringSea is probably as well under- stood as any in the world. A serious lack of such basic Gulf of Alaska data as nutrient levels and cycling rates limits the effectiveness of modern modeling procedures in this area. With insufficient information it is not possible, for exam- ple, to adequately develop trophic-level simulation models, particularly for the apex consumers. Our inability to under- stand more fully the processes that control the productivity of commercially exploited Gulf species has led to 'boom and bust' fisheries throughout history. Perhaps the most baffling scientific uncertainties at this time surround the recent sharp declines of the king crab and shrimp populations (OCSEAP Staff, Ch. 14, this volume). The recent development of an Alaskan pollock fishery in the central and western Gulf has resulted in the ongoing Fishery Oceanography Experiment (FOX), which focuses on interdisciplinary studies of the biotic and abiotic environment as they relate to year-class variations (Wilson, Inze, Macklin, and Schumacher 1986). Perhaps this kind of research program can eventually be applied broadly enough to provide the level of understanding necessary to manage the many environmental uses to which the Gulf is inextricably subjected. Multiple use demands on the ocean and its resources are ever increasing. A thorough understanding of ocean proc- esses and the natural variability which occurs in them is fun- damental to the development of satisfactory policies for wise ocean use. The value of any studies proposed for the Gulf of Alaska (or any ocean) should be weighed in terms of what they can contribute to the basic understanding of 22 Introduction Figure 1-8. Cruise tracks of the Harriman Alaska Expedition of 1889 (from Harriman Alaska Series of The Smithsonian Institution 1910. Vol. 4). ocean processes. Although much superficial descriptive knowledge is available, we are presently poorly prepared to respond to larger ocean-use questions. Although now pristine in a practical sense, the Gulf of Alaska will probably come under increasing human demands in the future. Because of its remoteness to popula- tion centers, the Gulf is unlikely to be called upon to bear an immediate burden of waste disposal for the escalating human population; however, adequately feeding the global population will require fuller use of all ocean resources. Enhancement of the ocean's productivity appears to be a definite development for the future, and some mariculture (aquaculture) is inevitable. Other than disease prevention and structural contain- ment, the most limiting factor in mariculture development is a reliable, low-cost, high-quality supply of feed that does not compete with livestock feeds. Careful examination of the coastal areas of the Gulf of Alaska reveals an unusual oceanographic situation. High nutrient levels reach nearer to the surface than in any other part of the world ocean. Annually, the surface waters are enriched by vertical mixing in the winter, leading to the annual vernal primary produc- tivity. In regions where vertical mixing continues through the summer, such as in lower Cook Inlet and on the Kenai shelf, exceedingly high levels of primary productivity ( S:300 g C/m2y) occur naturally. Could similar levels of productiv- ity be reached in other regions, such as inlets and fjords, by some artificial means? Here the opportunity clearly exists. In the development of scientific understanding there are three steps in progress that mark levels of achievement. First, the discovery phase which finds and identifies the problem. Then, the data collecting and experimental phase which describes and characterizes the system and, finally, the analytical phase which brings all data and experiment into focus to describe and predict the processes which con- trol the system. Only in a few oceanographic systems has the Physical Setting and Scientific History 23 152 148 Figure 1-9. Surface currents (at 100-m depth) at stations along three 1929 cruise transects in the Gulf of Alaska (from Thompson et al. 1936). level of achievement reached the final phase, but like all sci- ence, movement occurs on a broad front and success in one area is often generic and of value to other areas. While broad progress in oceanography will contribute heavily to a better understanding of the Gulf of Alaska, there are pri- ority areas of research which should be addressed in order to attain the level of understanding needed for the ana- lvtical phase indicated above. Briefly, these are: • data acquisition for development of simulation mod- els for all trophic levels • data acquisition concerning the natural history and population levels of apex consumers • an integration of the dynamics of biology, chemistry, and physics into a systems understanding that includes natural variability • increased application of known methods, and devel- opment of new ones, to enhance resource enhance- ment and utilization. The Gulf of Alaska has many features, as discussed ear- lier, that make it a highly significant part of the world's oceans. Our level of understanding of the Gulf is probably less than for most other ocean areas. Therefore, if — in the words of Francis Bacon — we are to command it wisely for man's use, we must better understand its natural processes and learn to obey and abide by the natural phenomena which occur there. Lynde for supplying information on the International North Pacific Fisheries Commission boundaries in the Gulf of Alaska. In addition, I acknowledge the useful information and suggestions received from authors of the disciplinary chapters. Support for the preparation of this chapter was furnished by the Minerals Management Service, Depart- ment of the Interior, through an interagency agreement with the National Oceanic and Atmospheric Administra- tion, Department of Commerce, as part of the Outer Conti- nental Shelf Environmental Assessment Program. a Bacon's Novum Organum (1620) has done more perhaps than any other work to inculcate into science unbiased, accurate, and careful observa- tion and experimentation. Acknowledgments The author wishes to thank Dr. Steven Zimmerman (the coeditor), Mr. Laurie Jarvela, Ms. Eleanor Kelley, and Mr. William Shiels for their helpful discussions and review of the manuscript. I also wish to thank Marcelle (Van Houten) 24 Introduction References Albatross 1902- U.S. National Museum Proceedings, Wash- 1911 ington, D.C. Vols. 26-38. Ali, S.A., D.C. Burrell, and G.G. Wood 1969 The zinc budget within an active glacial fiord: preliminary data. In: Clay-organic and organic-inorganic associations in aquatic environments, Part I. D.C. Burrell and D.W. Hood, editors. Report No. R69-10, Institute of Marine Science, University of Alaska, Fair- banks, AK. pp. 126-148. Allen, E.K. 1960 Prehistoric man in the Americas. In: The Alaska Book.yC. Frohlicher, editor. J.G. Ferguson Pub- lishing Co., Chicago, IL. pp. 97-103. Anderson, B. 1960 Surveyor of the Sea: The Life and Voyages of Captain George Vancouver. University of Washington Press, Seattle, WA. 268 pp. Bacon, F. 1620 Novum Organum (in Latin). In: Collected Works of Francis Bacon. Blackborne, London (1730). Beaglehole,J.C. 1966 The Exploration of the Pacific, 3rd edition. Stan- ford University Press, Stanford, CA. 346 pp. Bennett, E.B. 1959 Some oceanographic features of the northwest Pacific Ocean during August 1955. Journal of the Fisheries Research Board of Canada 16:565-633. Bogdanov, Yu.A. 1965 Suspended organic matter in the Pacific. Oceanology 5:77-85. Boucher, V.A. 1960 Those stone age fellows. In: The Alaska Book.J.C Frolicher, editor. J.G. Ferguson Publishing House, Chicago, IL. pp. 91-96. Brunn, A.F., S.V. Greve, H. Mielche, and R. Sparck, editors 1953 The Galathea Deep Sea Expedition, 1950-1952. Translated from the Danish by R. Spink. The MacMillan Co., New York, NY. 296 pp. Brower, W.A. Jr., H.F. Diaz, A.S. Prechtel, H.W. Searby, andJ.L. Wise 1977 Climatic Atlas of the Outer Continental Shelf Waters and Coastal Regions of Alaska. Publication B-77, Arctic Environmental Information and Data Center, University of Alaska, Anchorage, AK. 3 volumes. Burrell, D.C. and R.S. Hadley 1970 Suspended solid-liquid partition of metals in fjord environments. In: Clay-metal associa- tions in sub-arctic and Arctic marine environ- ments. D.C. Burrell, editor. Report. No. R70-10, Institute of Marine Science, University of Alaska, Fairbanks, AK. pp. 19-23. Challenger Expedition 1872- Report of the results of the voyage of the HMS 1876 Challenger during the years 1873-1876 under the Command of Captain George M. Nares. Printed in H.M. Stationery Office, London. Multiple volumes. Chang,J.C. 1971 An ecological study of butter-clams (Saxidomus giganteus) toxicity in Southeast Alaska. M.S. Thesis, Institute of Marine Science, University of Alaska, Fairbanks, AK. 94 pp. Chevigny, H. 1965 Russian America: The Great Alaskan Venture, 1741-1867. The Viking Press, New York, NY. 274 pp. Cooper, L.H.N. 1933 Chemical constituents of biological impor- tance in the English Channel, November, 1930, to January, 1932. Part I. Phosphate, silicate, nitrate, nitrite, ammonia./owrna/ of the Marine Biological Association of the United Kingdom 18:677-728. Danielsen, E.F., W.V. Burt, and M. Rattray, Jr. 1957 Intensity and frequency of severe storms in the Gulf of Alaska. Transactions, American Geophysi- cal Union 38:44-49. Dodimead, A J. 1958 Report on oceanographic investigations in the northeast Pacific Ocean during August 1956, February 1957, and August 1957. Fisheries Research Board of Canada Manuscript Report Series (Oceanographic and Limnological) No. 20. 14 pp. plus 35 figures. Dodimead, A.J. 1961 Some features of the upper zone of the sub- arctic Pacific Ocean. International North Pacific Fisheries Commission Bulletin No. 3. pp. 11-24. Dodimead, A.J., F. Favorite, and T. Hirano 1963 Salmon of the North Pacific Ocean. Part II. Review of the oceanography of the subarctic Pacific region. International North Pacific Fisheries Commission Bulletin No. 13. 155 pp. Physic ai Settinc, and Scientific History 25 el Wardani, S.A. 1960 Total and organic phosphorus in waters of the Bering Sea, Aleutian Trench and Gulf of Alaska. Deep-Sea Research 7:201-207. Fleming, R.H. 1955 Review of the oceanography of the northern Pacific. International North Pacific Fisheries Commission Bulletin No. 2. 43 pp. Fleming, R.H. 1958 Notes concerning the halocline in the north- eastern Pacific Ocean. Journal of Marine Research 17:158-173. Favorite, F. 1970 Fishery oceanography — VII: estimation of flow- in the Gulf of Alaska. Commercial Fisheries Review 32(7):23-29. Favorite, F. and C.M. Love 1957 Northeast Pacific Ocean and Gulf of Alaska physical and chemical data, summer and fall 1955. Department of Oceanography Special Report No. 28, University of Washington, Seattle, WA. 88 pp. Forrester, C J., R.G. Bakkala, K. Okada, and J.E. Smith 1983 Groundfish, shrimp, and herring fisheries in the Bering Sea and northeast Pacific — histor- ical catch statistics, 1971-1976. International North Pacific Fisheries Commission Bulletin No. 41. 100 pp. Golder, F.A. 1922 Bering's Voyages. An Account oftlie Efforts of the R us- sians to Determine the Relationship of Asia and Amer- ica, Vol. I: Log Books and Official Reports of the First and Second Expeditions, 1 725-1 730 and 1 733-1 742. American Geographical Society, New York, NY. 371 pp. Golder, F.A. 1925 Bering's Voyages. An Account of the Efforts of the Rus- sians to Determine the Relationship of Asia and Amer- ica, Vol. II: S teller's Journal of the Sea Voyage from Kamchatka to America and Return on the Second Expedition, 1741-1742. American Geographical Society, New York, NY. 291 pp. Gruening, E. 1959 Alaska: the forty-ninth state. In: The Alaska Book.].C Frohlicher, editor. J.G. Ferguson Pub- lishing Co., Chicago, IL. pp. 9-42. Harriman Alaska Expedition 1910 Haniman Alaska Series of the Smithsonian Institu- tion, Washington, D.C. Krause Reprint Co., New York, NY., 1972. Vols. I-XII. Hood, D.W. 1969 Baseline data survey for Valdez pipeline termi- nal study. Report No. R-69-17, Institute of Marine Science, University of Alaska, Fair- banks, AK. 121 pp. Hood, D.W. 1978 Upwelled impoundments as a means of enhancing primary production. Rapports et Pro- ces-verbaux des Reunions, Conseil International pour I'Exploration del la Mer 173:22-30. Hood, D.W., editor 1986 Processes and resources of the Bering Sea shelf (PROBES). Continental Shelf Research 5:1-288. Hood, D.W., K.V. Natarajan, D.H. Rosenberg, and D.D. Wallen 1968 Summary report on Collier Carbon and Chem- ical Corporation studies in Cook Inlet, Alaska. Report No. 68-9, Institute of Marine Science, University of Alaska, Fairbanks, AK. 180 pp. Hrdlicka, A. 1941 The Eskimo child. Annual Report of the Board of Regents of the Smithsonian Institution, 1941. pp. 557-562. Humboldt, A., von 1836- Examen critique de Vhistoire de la geographie du 1839 nouveau continent et des progres de I 'astronomie nati- que au 15e et 16e siecles. Paris. 3 volumes. Kenyon, K.E. 1980 North Pacific sea surface temperature observa- tions: a history. In: Oceanography, the Past. M. Sears and D. Meriman, editors. Springer- Verlag, New York, NY. pp. 267-279. Lentz, E. 1847 Bemerkiingen uber die Temperature des Walt- meers in verschiedenen tiefon. Bulletin Academy Science St. Petersburg 5:65-74. Distribution of dissolved and particulate organic carbon in Alaska polar, sub-polar and estuarine waters. Ph.D. Thesis, Institute of Marine Science, University of Alaska, Fair- banks, AK. 236 pp. Lynde, M.V. 1986 The historical annotated landings (HAL) data- base: documentation of annual harvest of groundfish from the northeast Pacific and east- ern Bering Sea from 1956-1980. NOAA Tech- nical Memorandum NMFS/NWC2. Loder, T.C. 1971 26 Introduction Makarov, S.O. 1894 Le "Vitiaz" et VOcean Pacific. Obsewations Hydro- logiques Faites par les Officiers de la Corvette "Vitiaz " Pendant un Voyage Autour du Monde, Execute de 1886 a 1889, et Recueil des Observations sur la Tem- perature et le Poids Specefique de VEau de VOcean Pacifique Nord. St. Petersburg. 2 volumes, (in French and Russian) Mantyla, AAV. andJ.L. Reid 1983 Abyssal characteristics of the world ocean waters. Deep-Sea Research 30A:805-833. McDonald, L. 1984 Alaska steam. Alaska Geographic 11:1-144 McEwen, G.F., T.G. Thompson, and R. Van Cleve 1930 Hydrographic sections and calculated currents in the Gulf of Alaska, 1927 and 1928. Report of the International Fisheries Commission No. 4. 36 pp. McRoy, C.P. and J.J. Goering 1974 Coastal ecosystems of Alaska. In: Coastal Ecologi- cal Systems of the United States, Vol. 3. H.T. Odum, B.J. Copeland, and E.H. McMahan, editors. The Conservation Foundation, Washington, D.C. pp. 124-145. Moiseev, P.A., editor 1955- Soviet Fisheries Investigations In the Northeast 1970 Pacific. In Russian, translations available from National Technical Information Service, TT-67-51204, Springfield, VA. 70 volumes. Murray, J. 1895 Historical introduction. In: Report of Scientific Results of HMS Challenger during the Years 1872-1876. A Summary of Scientific Results. Eyre and Spottiswoode, London, pp. 1-106. Natarajan, K.V. 1968 Distribution of thiamine, biotin, and niacin in the sea. Applied Microbiology 16:366-369. Prestwich,J. 1876 Tables of temperatures of the sea at different depths beneath the surface, reduced and corre- lated from various observations made between the years 1749 and 1868, discussed. Philosophical Transactions of the Royal Society of London 165:587-674. Reid,J.L.,Jr. 1962 On circulation, phosphate-phosphorus con- tent, and zooplankton volumes in the upper part of the Pacific Ocean. Limnology and Oceanography 7:287-306. Rienits, R. and T. Rienits 1968 The Voyages of Captin Cook. Paul Hamlyn, London. 157 pp. Roden, G. 1969 Winter circulation in the Gulf of Alask'A.Journal of Geophysical Research 74:4523-4534. Royer, T.C. 1972 Physical oceanography of the northern Gulf of Alaska. In: A review of the oceanography and renewable resources of the northern Gulf of Alaska. D.H. Rosenberg, editor. Report R72-73, Institute of Marine Science, University of Alaska, Fairbanks, AK. 690 pp. Royer, T.C. 1982 Coastal fresh water discharge in the northeast Pacific. Journal of Geophysical Research 87:2017-2021. Schantz, EJ. 1965 Chemical studies on shellfish poisons. In: Pro- ceedings of Joint Sanitation Seminar on North Pacific Clams, September 24-25, 1965. Alaska Depart- ment of Health and Welfare and U.S. Depart- ment of Health, Education, and Welfare, pp. 5-7. Steller, GW. 1751 De Bestiis Marinis. Academy Science Imp. Petropolitanae, Novi Commentarii 2:289-398. Stephens, K. 1964 Productivity measurements in the north- west Pacific with associated chemical and phys- ical data, 1958-1964. Fisheries Research Board of Canada Manuscript Report Series (Oceanographical and Limnological) No. 179. 168 pp. plus 16 figures. Sverdrup, H.U., M.V.Johnson, and R.H. Fleming 1946 The Oceans: Their Physics, Chemistry, and General Biology. Prentice-Hall, Inc., New York, NY. 1087 pp. Thompson, T.G. and R. Van Cleve 1936 Life history of Pacific halibut: (2) Distribution and early life history. International Pacific Halibut Commission. 184 pp. Thompson, T.G, McEwen, G.F., and R. Van Cleve 1936 Hydrographic sections and calculated currents in the Gulf of Alaska, 1929. Report of the Inter- national Fisheries Commission No. 10. 32 pp. Tully, J.P. and F.G. Barber 1960 An estuarine analogy in the sub-arctic Pacific Ocean. Journal of the Fisheries Research Board of CanadaY! -.91-112. Uda,M. 1935 On the distribution, formation, and movement of the dichothermal water in the north- western Pacific. Umi to Sora 15:445-452. KMYSKAI V I IIN(, MMI) S( IINIIIK HlsIOKY 17 Uda, M. 1963 Oceanography of the subarctic Pacific Ocean. Journal of the Fisheries Research Board of Canada 20:119-179. U.S. Hydrographic Office 1878 Meteorological charts of the North Pacific Ocean from the equator to latitude 45 degrees north and from the American coast to the 180th meridian. U.S. Government Printing Office, Washington, D.C. 20 pp. Wahrhaftig, C. 1965 Physiographic divisions of Alaska. U.S. Geo- logical Survey Professional Paper No. 482. 52 pp. plus maps. Wilson, J.G., L.S. Inze, S.A. Macklin, andJ.D. Schumacher 1986 FOX 1985, the northwest Gulf of Alaska fishery oceanography experiment. NOAA Data report ERL/PMEL-15. 133 pp. Wood, E.D. 1971 Gold in seawater. Ph.D. Thesis, Institute of Marine Science, University of Alaska, Fair- banks, AK. 162 pp. Wust, G. 1964 Deep-sea expeditions and research vessels, 1873-1960. Progress in Oceanography 2:1-52 . Section 2 Physical Environment Meteorology Judith G.Wilson James E. Overland Pacific Marine and Environmental Laboratory National Oceanic and Atmospheric Administration Seattle, Washington Abstract The Gulf of Alaska is one of the most active meteorological regions on earth. The types of weather found there are primarily caused by the passage of storm systems along the Aleutian storm track. Many of these storms are stalled by the high coastal mountains that ring the Gulf and are subsequently dissipated. Variability in the weather of the Gulf of Alaska is largely determined by planetary-scale motions, in particular by the presence of a high-pressure system that blocks the normal passage of storms. Large interannual variations are the norm. Throughout the year, offshore winds are predominantly from the south in the east- ern Gulf, from the east in the northcentral region, and from the west, but highly vari- able, near the Aleutian Islands. Wind intensity is the greatest in the winter months of October through April. The nearshore wind field can be quite variable due to the presence of the high mountain barrier to onshore flow. Examples of nearshore wind phenomena include coastal wind jets, gap winds, and katabatic winds. Winter air temperatures over the ocean are generally warmer than at continental stations at the same latitude due to relatively warm ocean-water temperatures. Fre- quently during the winter cold, continental air will stream over the region, bringing a dramatic drop in air temperature. The Gulf of Alaska is almost always cloud covered and the precipitation away from the coast is on the order of 100 cm/y. Storms that cross the Gulf drop as much as 800 cm/y of precipitation in the form of rain and snow in the high coastal mountains. These mountains provide substantial storage for runoff. The weather in the Gulf of Alaska affects the regional oceanography by means of both wind-induced currents and coastal currents driven by differences in water den- sity from the large runoff of fresh water along the coast of southeast Alaska. Because the weather influences the Gulf current systems and ocean stability, it has a major impact on the variability of the oceanic biological community. Introduction The Gulf of Alaska is one of the most active mete- orological regions on earth. Winter storms create 15-m seas, cause devastating coastal winds, and produce enough rain to classify some coastal areas as extratropical rain forests. The Gulf of Alaska is also a graveyard for storms: weather systems propagating eastward and northward across the North Pacific Ocean encounter a wide, continuous belt of mountains with peaks as high as 3,000 to 6,000 meters. In this chapter we describe the meteorology of the Gulf by con- sidering dominant weather patterns, storm tracks, winds, precipitation, air temperature, and other secondary vari- ables. We also discuss regional features such as coastal winds and give an introduction on the influence of the atmos- phere on the ocean. The meteorology of the Gulf of Alaska is dominated by the passage of storms that are characterized by low sea-level pressure and associated cold fronts. There are basically two seasons: winter extends from October through April and summer from May through September. During the winter, an average of one storm every four or five days (Hartmann 1974) crosses the Gulf, generally from west to east. With these storms come winds of up to 40 m/s and nearly continuous cloud cover. In addition, warm, moist air mov- ing ahead of the various cold fronts drops as much as 800 cm of precipitation annually in the high coastal mountains. Behind the cold fronts, cold, drv continental air streams J1 32 Physical Environment southward, enhancing cloud convection on scales of 2 to 100 km and producing gustv winds. A region of high sea-level pressure (a ridge) can often develop over the region in the winter and deflect storms to the north or south. The sum- mer pattern in the Gulf of Alaska is typified by light winds and the fog or low stratus clouds commonly associated with oceanic high-pressure systems. Along the coast, the high mountains modify and impede the onshore passage of storms. This condition sets up local wind fields such as strong gap winds in low-level channels, alongshore wind jets, and the outflow of continental air over the ocean. Outflows are greatest during the large-scale, winter pressure pattern, which features low pressure over the ocean and cold air over the interior continental plateaus. The meteorology of the Gulf of Alaska has a dramatic effect on the regional oceanography. Precipitation rates between 40 and 800 cm/y produce an annual-mean-runoff rate of ~ 23 x 103 m3/s from Southeast Alaska. The runoff is confined in a narrow current jet that is held against the coast by the wind-induced, onshore Ekman transport typical of storm systems in the eastern Gulf. Current speeds reach 100 cm/s during peak runoff in the autumn. Wind and density gradients induce an alongshore current that transports nutrients and biota counterclockwise around the Gulf. Year-to-year ocean variability depends largely on inter- annual changes in storminess. Large-Scale Meteorology Semi-Permanent Atmospheric Systems The meteorology of the Gulf of Alaska is influenced by the relative positions of three semi-permanent atmospheric features: the Aleutian low-pressure region and the east Pacific and Siberian high-pressure regions (Fig. 2-1). The Aleutian low-pressure region is caused by intense storms (low-pressure systems) that pass through this area at a higher frequency than almost any other place on earth. This low is a statistical low-pressure area in the sense that the monthly average sea-level pressure along the Aleutian Island chain is lower than surrounding areas. The statistical low has an elliptical shape with the long axis oriented west to east. The shape indicates the west-to-east passage of indi- vidual low-pressure centers (Grubbs and McCollum 1968). The elliptical shape is also due to low-pressure systems reaching their maximum intensity (lowest pressure) in the western and central Gulf. The Aleutian low occurs 25% of the time, making it the dominant influence on Gulf of Alaska weather throughout the year (Overland and Heister 1980). By averaging 80 years of monthly-mean data on a 5° latitude-longitude grid, Angell and Korshover (1982) found the average position of the Aleutian low at 56°N, 168°W with an average central pressure of 1,002 millibars. Its position is described by Favor- ite, Dodimead, and Nasu (1976) as moving southeastward Aleutian Low and Siberian High 70 160 East Pacific. High 170 160 Noon (GMT)" January 1, 1984 Gulf of Alaska suich area Figure 2-1. Examples of the Aleutian low, Siberian high, and east Pacific high-pressure systems. These three semi-permanent atmo- spheric features influence the weather over the Gulf of Alaska. Contours refer to sea-level pressure in millibars (mb). Mi m >ki ii oo 33 from the Bering Sea into the Gulf between August and December. In January, the low-pressure center moves to the western Aleutians where it slowly weakens through July. During summer, cyclonic low-pressure systems are weaker and tend to migrate further north due to the decreased difference in temperature between the Equator and the pole. The oceanic region is cooler than the adjacent land masses and a large high-pressure system is established over the Gulf of Alaska. This east Pacific high-pressure sys- tem is present throughout the year off the California and Baja California coasts. It reaches maximum intensity and northward position in June through August, when it domi- nates almost the entire North Pacific including the Gulf of Alaska (Favorite et al. 1976). Its 80-year average position is 35°N, 143°W with an average central pressure of 1,024 mb (Angell and Korshover 1982). The Siberian high-pressure system influences the Gulf of Alaska from October through March. The high, which reaches its maximum intensity in January, is associated with the huge pool of very cold winter air over eastern Asia and northern Alaska. Although rarely present in the Gulf, its influence is felt through a southward shift in the location of the Aleutian storm track and an increase in cold winds blow- ing from the north over the western Gulf. Cyclonic Weather Systems Because of its importance to all aspects of Gulf of Alaska weather, we provide a brief description of the meteorology associated with individual storms. An idealized surface low-pressure system and a frontal structure in a mature stage of storm growth are shown in Figure 2-2. Storm sys- tems in the northern hemisphere are cyclonic, with the winds flowing counterclockwise around a low-pressure cen- ter. Surface geostrophic winds are caused by a balance between the force of the sea-level pressure gradient and the Coriolis force. Surface winds over the ocean are typically 80% of the magnitude of the geostrophic wind and are ori- ented ~ 20° to the left of the geostrophic wind direction (toward a low-pressure center, out of a high-pressure cen- ter) due to the influence of surface friction. As shown in the idealized view of a low-pressure area, the winds in the eastern sector ahead of the cold front are south- erly. The winds behind the cold front are northwesterly, and the winds north of the low and ahead of the warm front are northeasterly and easterly. East of the cold front, moist warm air is advected northward by surface winds. Behind the cold front, cold air moves southwest into warmer regions. There is a net transport of heat and moisture north- ward near the surface due to a storm passage. Inclement weather is associated both with the north and east sector of a low-pressure system and with the cold front. This idealized view is accurate for an area over the ocean away from the coast. Near the coast ( < 100 km offshore) the picture is complicated because the geostrophic balance is blocked by high coastal mountains (Overland 1984), and spe- cial wind and precipitation phenomena are induced by the topography of the coast. Fronts are regions of air temperature contrast. As storms cross the North Pacific, the air flowing from the east in the Cold Front Figure 2-2. Idealized view of a low-pressure system. The heavy solid lines that encircle the low pressure center (L) arc isoh.us (lines of constant pressure) decreasing in magnitude towards the center. Shaded area is approximate cloud cover, and the dashed line encloses the area where rain is expected along the fronts and near the low center. Winds blow counter-clockwise (Northern Hemisphere; cyclonic) around the low. The last stage before a low-pressure system dissipates is the occluded stage where the low center moves deep into the cold air sector. northeast sector of the storm (north of the warm front in Fig. 2-2) is similar to the air flowing from the south (south of the warm front in Fig. 2-2). This similarity occurs because air on both sides of the warm front is modified when it flows over areas of similar ocean temperature. Under these conditions, when there is relatively little temperature contrast between the northeast and eastern sectors, storms entering the Gulf do not usually have pronounced warm fronts. The cold front tends to maintain its identity. As wind blows over the ocean surface, momentum is transferred to ocean waves and currents. Another term for momentum transfer is stress, which is defined as the vertical flux of momentum per unit area. Since there are few loca- tions where stress has been measured directly over the ocean, most oceanic estimates are computed from meas- ured or geostrophically derived surface winds. Momentum transfer is related to the square of the wind speed adjacent to the ocean surface (Businger 1973) by a drag (or transfer) coefficient (CD) that increases slowly witli increasing wind speed (Han and Lee 1983). The transfer of sensible heat and moisture (latent heat) between the ocean and atmosphere is important to the energetics of a cyclonic weather system. These transfers depend on 1) the tern- 34 Physical Environment Wind Stress (N/m-) Sensible Heat Flux (W/m2) Latent Heat Flux (W/m2) 155 150 145 140 135 155 150 145 140 135 155 150 145 140 135 Figure 2-3. Six-storm composite in the vicinity of Station P (50°N, 145°W) showing wind stress, sensible heat flux, and latent heat flux. Arrows indicate direction of air flow and dashed lines are contours of the magnitude of the wind stress. (Modified from Fleagle and Nuss 1985.) perature and moisture differences between the air and the sea, 2) the wind speed, and 3) transfer coefficients. Fleagle and Nuss (1985) present composite patterns of streamlines (lines of constant wind direction), wind stress, sensible heat flux, and latent heat flux derived from observa- tions of six winter storms in the Gulf (Fig. 2-3). The max- imum wind stress occurs in the region of highest wind speeds; in the Gulf this is frequently in the warm sector to the east of the low-pressure center. In the warm sector east of the cold front, where warm air is flowing from the south over the ocean, the flux of sensible heat (Fig. 2-3) is from the air to the sea. In the cold air sector to the west and north of the cold front, the heat flux is from the sea to the air. In the warm sector, latent heat transfer is at a minimum where the air is warm and moist (Fig. 2-3). To the west of the cold front, the air originating over more northerly latitudes is cold and dry, which produces a maximum of transfer of moisture and heat from the ocean to the atmosphere. Just as there are low-pressure areas in the atmosphere, there are also regions of high pressure. A high-pressure area (also called a ridge or anticyclone) has clockwise flow (in the Northern Hemisphere) and tends to be an area where high-level air is warmed through compression as it sinks toward the surface. This warm, dry air from above diverges near the surface, bringing warmer-than-normal temperatures to the region under the ridge. A low-level temperature inversion may keep the air from above away from the surface (Treidl, Birch, and Sajecki 1981). When the center or axis of the ridge is over the North Pacific Ocean, northerly winds east of the ridge bring cold, continental air over the Gulf. In addition, anomalously strong, southerly winds west of the ridge produce conditions that are warmer and wetter than average. The surface weather associated with high-pressure ridges in the Gulf of Alaska is frequently fog or low clouds. Annual Cycle of Pressure and Storm Tracks Storms tend to form in specific regions in the Pacific, most notably along the east coast of Asia where warm ocean currents pass southeast of cold land masses. Additional storm formation regions are in the central Pacific along the oceanic front located near 35°N (Roden 1970). These are regions of strong horizontal temperature gradients and unstable air masses. Once formed, storms can either inten- sify or weaken as they move generally eastward. Storms crossing the North Pacific usually intensify as they slowly gather heat and moisture from the ocean surface. A storm may, however, undergo rapid development in conditions where deep vertical mixing is fueled by cloud processes (Gyakum 1983; Mullen 1983). Almost all rapid-development events occur in early winter, with the largest number occur- ring in October (Murty, McBean, and McKee 1983). Early winter is a likely time for conditions of unstable atmosphere and deep convection to occur since the sea surface remains warm and transfers its heat to the adjacent atmosphere underneath a region of southward flowing cold air in the upper atmosphere. Low-pressure systems that move into the Gulf of Alaska during early and late winter often stall and dissipate. A quasi-stationary low-pressure center is maintained in the Gulf by the presence of coastal mountains. Transient, low-pressure systems entering the Gulf often lose their sep- arate identity to this persistent feature. Figure 2-4 shows the Figure 2-4. Annual distribution of cyclone dissipation posi- tions. Contours show the number of cyclone dissipations for the period February 1980 to January 1981. (Modified from Roebber 1984.) Mi IK )!•!< IK K,1 35 tW ^Ps> \ April /" 55 L_-£*-*~~*'"'^ 1010.1 1 \ 1 . 4^ / /V // y 50 j> , o ^ ' — 1012 •> ' / ^' / ' s s *T /* ^t-, Xlf 1 Assy^r \ \ V w ) ] 1 \ W< / } J X * \ August "is. ,-\ Figure 2-5. Monthly mean sea-level pressure (mb; solid contours) and surface-air temperature (C; dashed contours) maps over the Gulf of Alaska. The time period of observations varies at each station. (Modified from Brower et al. 1977.) Gulf of Alaska as a major storm-dissipation area in the Northern Hemisphere for the period February 1980 tojanu- ary 1981 (Roebber 1984). Monthly-mean pressure and temperature patterns over the Gulf of Alaska are presented in Figure 2-5 (Brower, Diaz, Prechtel, Searby, and Wise 1977). The winter presence of the Aleutian low is clearly seen in the pressure field from October through December. Higher pressures in January than in either December or February are associated with the frequent development of a high-pressure area over the Gulf in January. Pressure rises from a low in late winter to a max- imum in July — corresponding to the influence of the east Pacific high as the Aleutian low retreats into the north- western Bering Sea. The pressure gradient increases in August and September as the Aleutian low moves southeast- ward once again to dominate the region in the winter. Cyclones that originate in the same area usually follow similar paths called storm tracks. Storm tracks are charac- terized by poleward fluxes of heat, moisture, and angular momentum. Monthly cyclone frequencies and storm tracks are shown in Figure 2-6 (Whittaker and Horn 1982). Cyclone frequency was determined by counting the number of low-pressure centers in 5° latitude-longitude boxes for a 15-year period between 1958 and 1977. Primary tracks are defined as those tracks showing the highest occurrence of minimum-pressure systems along the track. Lesser counts are considered as secondary tracks. Few cyclones actual 1\ follow these tracks from beginning to end, but statistically, cyclones are most likely to appear along these trajectories. Tracks from Whittaker and Horn (1982) for 1958 to 1977 can be compared to tracks from Klein (1957) for the years 1909 to 1914 and 1924 to 1937. 36 Pi-nsicvi Environment 60 160 150 140 130 ^1 ~*"~T- "^October Y~ — W~ // 4^=~T--^.- s. a< x- 55 '- " so- // ; i ^v<. ^r' ^f / 60 x 50 r — ^ '•' / / \ ^ / 1 -> / 60 55 50 60 55 1 i April ■j^'^^d ^ •• 60 yS - / / u< \ -~~ -20 i Jul>' j*p* , *-— \ \ ' N40 SfK ^ / \ / \ v / 1R0 150 140 130 November r^V--yy\ I -^k // \ I I I ^ -'^ /-^ ' I I / / ,60 — , 1 *1 K-/- 0^ I ~~ " February. Us£ .60' s/^\ ^\ '^"" i J Y December %\ t A \ September ~40- -^Q ' y\— \ >. is -\ ^l-,*- v?iN L25 m/s), although winds average 8 to 11 m/s from October through February (Fig. 2-12). We have chosen to connect all the monthly-mean data in Figure 2-12 with lines to accentuate the annual cycle, although this is not strictly correct. Summer winds result mainly from the east Pacific high-pressure system or weak low-pressure systems in the Gulf. Figure 2-12 shows how mean winds decrease through the spring to a low of from 6 to 7 m/s in June, and also shows large standard deviations for all months. Schumacher and Reed (1983) note a marked difference between the mean winds in the northcentral Gulf and those along the Alaska Peninsula, especially in the winter storm season. This difference is attributed to the location of the storm track along the Alaska Peninsula and south of the Alaska coast. In the vicinity of the storm track across the western Gulf, the wind direction is highly variable, depend- ing on whether the low center is north, south, east, or west of a specific location. The mean-vector winds in this region have a westerly component in all months (Fig. 2-13). In the northcentral Gulf the wind is almost always from the south or east, because lows cross the Gulf to the south. The south- erly component is especially pronounced in the months of transition between the two seasons (October and April). The eastern Gulf winds are predominantly southeasterlv in the winter. In the summer, the mean-vector winds are smaller 56°N148°\V 52°N156°W 51°N136°VV j- Q Z OCT No\ Mar Apr JUN |l 1 AUG Mr Figure 2-12. Monthly-mean surface wind speed at three Gulf of Alaska offshore NDBO buoys for the period 1972 to 1981. The vertical bars are the monthly standard deviations .it the 56°N, 148° W buoy and have similar magnitudes at the Other two stations. (Modified from Gilhousen et al. 1983.) 40 Physical Environment Eastern Gulf (Marine Area F) V M / M Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Figure 2-13. Monthly-mean vector winds (m/s) for the western, northern, and eastern Gulf. Marine area A is an average of observations (mostly by ships) in the area bounded by 157°W to 165°W and 52°N to the Alaska Peninsula. Similarly, marine area F is bounded by 54°N and 138°W to the southeast Alaska coast. The central northern Gulf is represented by observa- tions at Middleton Island (59.4°N, 146.3°W). (Modified from Brower et at. 1977.) radiation that reaches the surface (minus the radiation that is reflected), as well as sensible and latent heat transferred from the sea to the adjacent atmosphere. Talley (1984) dis- cusses the many problems associated with computing the energy balance over such a data-sparse region as the Gulf of Alaska. Budyko (1974) has mapped the terms of the energy balance equation over the earth. Many subsequent authors believe that Budyko (1974) underestimated the cloud correc- tion factor by between 17 and 25% , thereby producing a 6 to 23% underestimate of the amount of incoming solar radia- tion. Given the uncertainties, Budyko's (1974) estimates of 80 to 105 W/m2 for incoming solar radiation, 40 to 50 W/m2 for long wave radiation, 25 to 55 W/m2 for latent heat, and 6 to 16 W/m2 for sensible heat transfer over a year indicate the relative importance of these processes in the Gulf of Alaska. The temperatures of the lower atmosphere and adjacent ocean are important in describing the climatology of the Gulf region and are related to the passage of storms across the region through their influence on modifying the bal- ance of energy at the sea surface. The monthly average spatial distributions of surface-air temperatures are shown in Figure 2-5 (Brower et al. 1977). A fairly steady winter temperature distribution lasts from November through April. The summer patterns show a warming through August of the region centered near the Alaska Peninsula. May and October are the two transition months that encompass most of the changes in temperature between the two seasons. The prevailing southerly winds in Western Gulf 52° to 54°N 155° to 160°W and more south to southwesterly. In addition to the passage of storms, the nearshore wind field is also influenced by topography as discussed in the following section on local meteorology. The annual cycle of monthly-mean wind stress based upon monthly averaged winds observed from ships over the 15-year period from 1961 to 1975 is shown in Figure 2-14 (Kutsuwada and Sakurai 1982). Momentum transferred from the atmosphere to the ocean is directed toward the east in the western Gulf. This is a region of high winds both ahead of (southwesterlies) and behind (northwesterlies) the cold fronts that cross the region. In the southeastern Gulf, the stress is directed toward the northeast through the year. Note that this subregion is shifted to the west relative to marine area F in Figure 2-13. The stress pattern in the cen- tral Gulf has high variability from month to month. The stress estimates from Han and Lee (1983) and Hellerman and Rosenstein (1983) qualitatively agree with Figure 2-14. Radiation, Air Temperature, Sea-Surface Temperature, and Heat Fluxes The balance of thermal energy flux at the sea surface depends on several factors, including the amount of solar Northern Gulf 56° to 58° 145°tol50°W 4 X-., / f Eastern Gulf 50° to 52° 135° to 140°W 50 10(1 (xl0~sN/m2) OCT NOV DK Figure 2-14. Monthly-mean wind stress (x 10"5 N/m2) for the western, northern (central), and eastern Gulf of Alaska for the period 1961 to 1975. (Modified from Kutsuwada and Sakurai 1982.) Meteorology 41 U 56°N148°W 52°N156°W 51°N136°W \ \ \ \ V V \ s X N / ()( 1 \()\ DK Feb mar Apr mai |i \ jui Aug sf.p Figure 2-15. Monthly-mean surface air temperature at three Gull of Alaska offshore NDBO buoys for the period 1972 to 1981. The vertical bars are the monthly standard deviation at 56°N, 148°W. (Modified from Gilhousen et al. 1983.) the eastern Gulf produce a tongue of warmer air along the west coast of North America throughout the year. The annual cycle of air temperature at three open-ocean buoys (Gilhousen, Quayle, Baldwin, Karl, and Brines 1983) is depicted in Figure 2-15. The stations in the central and west- ern Gulf are very similar, and thev are colder than the east- ern station throughout the year. High summer temperatures for the area correspond with a minimum in variability compared with winter tem- peratures due to the decrease in the number and the inten- sity of passing storms. The air temperature over the Gulf is moderated by the ocean and is considerably warmer than continental stations at the same latitude during the winter months. Frequently throughout the winter, cold continental air will stream over the Gulf and bring a dramatic drop in temperature over the region. The rise in temperature at all three stations in January may be associated with the fre- quent occurrence of a blocking ridge over the Gulf during this month. Annual-mean air temperatures show no long-term trend along the northcentral Gulf coast and southeast Alaska coast (Fig. 2-16). The annual-mean temperature of 6.3C for the period 1828 to 1876 is the same as the annual mean for the mid-1970s (Ingraham, Bakun, and Favorite 1976). The mean of the three ocean stations in Figure 2-15 is 7.1C for the years 1972 to 1981. The annual-mean air tem- perature was found by Ingraham et al. (1976) to have short fluctuations of from one to four years, such as the dramatic cooling episode from 1934 to 1936 along the south coast of Alaska and longer trends such as the cooling event that lasted from 1944 to 1955. We have chosen to present the air-sea temperature dif- ference instead of sea-surface temperature, because the transfer of sensible heat between the atmosphere and the ocean is directly proportional to this quantity (Businger 1973). The monthly-mean air-sea temperature differences at three ocean buoys (Fig. 2-17) (Gilhousen et al. 1983) are fairly constant from March through September, before decreasing through early winter to a minimum in December when cold, continental air flows over water that still retains some heat from the summer. The ocean continues to cool throughout the winter. The small air-sea temperature dif- ferences in January are a reflection of the warmer air tem- peratures at the buoys (Fig. 2-15) and the cooler water tem- peratures of mid-winter. The difference may be the result of the frequent occurrence of blocking highs over the Gulf in that month. The February values drop to a level between the December minimum and the summer values. Note the large variability (standard deviation) of air-sea temperature dif- ference associated with the passage of different storm sec- tors during the winter months. As with air temperature (Fig. 2-15), the mean values contain individual events when cold, continental air flows over the warmer ocean. These out- breaks induce fluxes of heat that are additive with respect to the total transfer of heat from the ocean to the atmosphere over the winter season. Latent-heat transfer depends on the difference in spe- cific humidity between the ocean surface and the adjacent atmosphere. There are very few measurements available from over the open ocean. The composite latent heat flux shown in Figure 2-3 (Fleagle and Nuss 1985) emphasizes how important latent heat is (relative to sensible heat) to the total heat flux associated with individual storms: 120 W/m2 behind the cold front compared with 20 W/m- for the sensi- ble heat flux (Fig. 2-3). At present, there are major difficul- ties in estimating the monthly, regional heat transfer over the North Pacific, and there are no agreed-upon param- eters (R.K. Reed, PMEL/NOAA, pers. comm.). Cloud Cover, Fog, and Coastal Visibility The Gulf of Alaska is almost always what meteorologists refer to as 'mostly cloudy'. Figure 2-18 shows monthly cloud cover estimates at three locations taken from Favorite et al. (1976) that are based on shipboard observations taken from 1948 to 1967 on a 5° latitude-longitude grid. The cloud cover is a minimum in the winter increasing through the spring to a maximum in July, then decreasing in late sum- mer and early winter. Over the main body of the Gulf there is a cold, low-level stratus deck in mid- and late-winter (Grubbs and McCollum 1968). 1930 1940 1950 1960 1970 1980 Figure 2-16. Annual-mean surface air temperatures along Southeast Alaska (defined as the Canadian holder to south of Yakutat) and southcoast Alaska (defined as Yakutat to ir>5°W) for the period 1931 to 1979. (Modified from Royer 1982.) 42 Physical Environment s 2 z I | ° Q Hi x H < -2 a! * 3 =- V. u H < i T ' • "v / _^^ *=■-- ■^Ai* • 56°N 148°W 52°N156°W 51°N136°W ()( i Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Figure 2-17. Monthly-mean air-sea temperature difference at three Gulf of Alaska offshore NDBO buoys for the period 1972 to 1981. The vertical bars are the monthly standard deviations at 56°N, 148°W. (Modified from Gilhousenrta/. 1983.) 8/8- 7/8- 56°N148°W 52°N156°W ,-'"* — , 51°N136°W .'f'~ X \ 6/8- /^i^f \ Oct Nov Dec Jan Feb Mar Apr May Jun Jul Auc Sep Figure 2-18. Monthly-mean cloud cover estimates in eighths at three Gulf of Alaska offshore NDBO buoys for the period 1948 to 1967. (Modified from Favorite et al. 1976: Fig. 31, data drawn from 5° latitude-longitude grid.) Winter cloudiness is associated with the passage of cyclonic systems and with the flow of cold, continental (rela- tively dry) air off the Alaskan continent over the relatively warm Gulf waters. The winds that originate over the conti- nent or over the Bering Sea seasonal ice field are associated with cloud streets and cumulus convective cells over much of the Gulf (Walter 1980; Overland and Wilson 1984). Cumulus convection is typical after the passage of a cold front. The north and northeastern sectors of a storm are typ- ified by solid overcast (Fig. 2-2). Under the east-Pacific high-pressure system in summer, moist air near the surface is trapped by a low-level temperature inversion resulting in persistent fog and low stratus clouds over the Gulf. The average number of clear days (less than one-eighth cloud cover) along the Gulf of Alaska coast is four to seven per month (Grubbs and McCollum 1968). In the summer, Grubbs and McCollum (1968) found that some cloudiness along the coast was present throughout most of the day and increased in the evening. Fog occurs over the Gulf of Alaska in every month of the year. It is most prevalent in the summer and the early winter months (Grubbs and McCollum 1968; Guttman 1975). Dur- ing the winter, supercooled fog occurs in the vicinity of ice-covered Cook Inlet. Visibility in the coastal regions is often restricted by fog, rain, or snow. The increased shower activity both in early winter and in late winter (a secondary maximum) brings low visibility (Grubbs and McCollum 1968). In general, early summer is the time of year with the greatest visibility. Precipitation and Runoff The precipitation over the Gulf of Alaska varies between 0.8 and 100 cm/y, except along the Southeast Alaska coast where oceanic precipitation exceeds 100 cm/y (Reed and Elliott 1979). The maximum monthly mean precipitation occurs during the winter, in association with the maximum in cyclone activity, with 8 to 10 cm/mo during December, Jan- uary, and February and greater than 10 cm/mo falling near Southeast Alaska. The precipitation amount is reduced to 7 to 8 cm/mo in March, April, and May, less than 5 cm/mo in the summer, and rises to 7 to 8 cm/mo in September, October, and November. These averages are based on sparse temporal and spatial precipitation-frequency data from almost a century of observations. The Reed and Elliott (1979) and the Elliott and Reed (1984) annual estimates of 100 cm/y near the Southeast Alaska coast contrast with the Dor- man and Bourke (1978) estimate of 180 cm/y. The latter, how- ever, was corrected with coastal data that showed higher pre- cipitation rates due to the proximity of the mountains. This is a persistent problem in making open-ocean precipitation estimates. The annual precipitation distribution over Alaska is shown in Figure 2-19 (Reed and Elliott 1979; Royer 1983). Near the coast, the onshore flow of moist, marine air is forced up the slope of coastal mountains. As the air cools, precipitation is enhanced. Air cooling over glaciers also enhances precipitation. There is a large variation in pre- cipitation in mountainous regions where the amount is determined both by the height to which air is lifted and by the presence of glaciers. A maximum of over 800 cm/y of precipitation occurs in the mountains of Southeast Alaska (Fig. 2-19). Grubbs and McCollum (1968) report that the pre- cipitation in coastal regions generally occurs from 14 to 16 Figure 2-19. Annual-mean precipitation (cm) for the Gulf of Alaska (after Reed and Elliott 1979), and over Alaska (after Royer 1983, courtesy of Larry Mayo). Meteorology 43 3 | /^Southeast [\ < g 2 s ft. V /Southcoast < Z 1 < 0 i i i i 1930 1940 1950 I960 1970 1980 Figure 2-20. Annual-mean precipitation along Southeast Alaska (defined as the Canadian holder to south of Yakutat) and southcoast Alaska (defined as Yakutat to 155°W) for the period 1931 to 1979. (Modified from Rover 1982.) d/mo in the mid-winter and from 18 to 22 d/mo in the late summer and early winter. The annual mean precipitation for a 49-year period at stations along the south and south- east coast of Alaska is shown in Figure 2-20 (Royer 1982). A result of the high precipitation rates along the Alaskan coast is a high rate of freshwater runoff into the Gulf of Alaska. Precipitation that falls in the coastal mountains either runs off or is stored in the mountains in the form of snow and ice. Glaciers that cover —20% of the coastal drainage area (Royer 1982) retain the precipitation that falls there for periods ranging from months to years. It is impossible to measure all or even most of the fresh- water discharge into the Gulf because of the large number of rivers and streams along the Alaskan coast. However, Royer (1982) uses monthly mean precipitation rates, air tem- peratures, area of the drainage regions, and the interannual growth and ablation rates of glaciers to compute runoff. Maximum runoff occurs in late summer and early winter due to a combination of meltwater runoff and the increased precipitation that occur during winter (Royer 1982) (Fig. 2-21). The runoff rates decrease quickly after November when the air temperature drops below the freezing level and precipitation is stored as snow. Royer (1982) found that the discharge is at a minimum in February and March, then increases to the maximum in October with a secondary max- imum occurring in May. This secondary maximum is due to summer snow melt in the mountains and is more pro- nounced south of the Gulf region where less precipitation is retained in glaciers. Royer's (1982) annual discharge rates for 49 years along the Alaska coast are shown in Figure 2-22. The mean dis- charge rate for the period is 2.3 x l(f m%. These estimates exclude the Gopper River (1.05 x 10:i m3/s) and the runoff that enters the Gulf of Alaska from British Columbia (Fraser River rate is 2.69 x 103 m%) or the northwest United States. The Copper River was found to be less than 5% of the total discharge for the region, which is well within the error esti- mates. Rover (1982) believes, however, that the freshwater input from British Columbia and the northwest United States is probably significant. Also plotted in Figure 2-22 is the pressure index from Emery and Hamilton (1985) and the NFO years from Rogers (1981). The correlation coefficient is 0.43 for the discharge and pressure-index time series. Of special interest are years when a high-pressure index and/or a 'B' NPO index (intensified Aleutian low) are coincident with high runoff (1940, 1944, 1953, 1960, 1975, and 1976). Other Means and Variabilities In addition to means and variabilities in the categories of wind, radiation, cloud cover, and other topics we have cov- ered in this section, there are three additional categories to address: 1) superstructure icing, 2) sea ice, and 3) waves. Superstructure Icing. When the air temperature is below the freezing temperature of seawater ( - 1.7C at a sali- 50 20 Jan Feb mar Apr May Jin Jit alc Sep Oct Nov dec Figure 2-21. Monthly-mean discharge of freshwater into the Gulf of Alaska for the period 1931 to 1979. (Modified from Royer 1982.) 38 X 30 26 > 22 I North Pacific Oscillation (NPO) Index A — Weak Aleutian low B — Strong Aleutian low 30 1930 1940 1950 19o<) 1970 1980 Figure 2-22. Annual-mean discharge ol freshwater into the Gulf of Alaska for the period 1931 to 1979 (solid line). (Modified from Royer 1982.) Superimposed is the F.mcrv and Hamilton (1985) pressure index and the Rogers (1981) North Pacific Oscillation (NPO) index. 44 Physical Environment 2 28 Si RK\( K WlM) Sl'H 1) (kt) 55 45 35 25 No icing e icing categories used by the NWS are: Light 0.4-1.4in/24hr Moderate 1.4-2. 6in/24hr Heavy 2.6-5.7in/24hr Very Heavy over 5.7in/24hr Instructions: Sav that you estimate that the air temperature is 14°F, wind velocity is 30 knots, and the sea temperature is 32°F. Enter the nomograph on the 14°F line. Follow this line to the 30 knot wind velocity line. From the intersection of the two lines, follow thediago- nal line to the 32 F sea temperature line. At the intersection read off the icing categorv, in this case, heavy icing. Figure 2-23. Superstructure icing nomogram uses wind speed and air and sea temperatures to predict ice accumulation on ships and other structures. (Modified from Comiskey 1976.) nity of 35°/oo), any water in the air (e.g., fog, rain, and sea spray) will freeze to structures on ships, platforms, and low-flying aircraft. The accumulation of ice on structures due to sea spray is a complicated process depending on air and sea temperatures, wind speed, wave direction relative to the structure, and structure configuration. Comiskey (1976) developed an icing nomogram using wind speed along with air and water temperatures for forecasting ice accumulation from sea spray (Fig. 2-23). A more recent algorithm (Over- land, Pease, Preisendorfer, and Comiskey 1986) predicts icing rates of more than three times those predicted by the Comiskey nomogram. Although the water temperature in the southern reaches of the Gulf is generally warm enough to avoid icing prob- lems, near Kodiak Island and along the Alaska Peninsula during the winter a ship can accumulate ice on its super- structure that makes it top-heavy and susceptible to sinking. Locations where superstructure-icing have occurred, as reported by Wise and Comiskey (1980), are shown in Figure 2-24. The actual area where conditions favor icing may be broader, but other data are not available. The lack of data is especially important north of the Alaska Peninsula where there has been little winter shipping traffic. Recent evalua- tions suggest that values shown in Figure 2-23 may under- estimate icing rates. Sea Ice. Cold temperatures and freshwater runoff com- bine to cause many inlets and embayments to be frozen over in the winter. The onset of ice at the head of Cook Inlet is most highly correlated with the meteorological parameter, adjusted-frost-degree-days (Poole and Hufford 1982). The southern extent of the ice in Cook Inlet was determined to be dependent on the rate of freshwater inflow, the tem- 130 60 Figure 2-24. Estimated zones of icing categories under the most extreme conditions in the Gulf of Alaska. Black dots are locations of known icing events from January 1976 to January 1980. (Modified from Wise and Comiskey 1980.) Meteorology 45 perature of Gulf of Alaska water, and the local winds that advect the ice. Maximum ice extent usually occurs in Febru- ary. In the period of the Poole and Hufford study (1969-1980), the ice edge during minimal-ice years was in the vicinity of Kalgin Island in Cook Inlet. In abundant-ice years, the ice edge extended from north of Anchor Point on the Kenai Peninsula to Cape Douglas on the Alaska Peninsula. Occasionally, pieces of ice break away either from glaciers or from the seasonal ice pack in one of the many ice-filled inlets along the coast (e.g., Prince William Sound and Vakutat Bay) and drift into the warm Gulf of Alaska water. Waves. Wave size is determined by the wind speed, wind duration, and the distance that the waves have traveled over the surface (fetch). Waves generated locally are called 'seas', and waves that continue with no relation to the local wind are termed 'swell'. Swell travels on great circular courses. Waves are reported bv significant wave height, defined as the mean height of the highest 1/3 of the waves observed over a 20-minute period (Shepard 1973). The annual cycle of sig- nificant wave height at three buoys in the Gulf of Alaska is shown in Figure 2-25 (Gilhousen et al. 1983). The pattern is very similar to that of the surface wind speed (Fig. 2-12), with a broad maximum occurring in the winter months and a minimum occurring in June and July. Maximum-signifi- cant-wave heights (Fig. 2-26; the 99th percentile) at these same buoys show a similar pattern. The low maximum- wave heights in January and February are related to the lighter winds associated with blocking highs that can develop during these months (Fig. 2-10). The Aleutian Islands block the propagation of swell from the west into the Gulf and limit the fetch for westerly winds. Maximum wave heights occur when a storm moves into the Gulf from the south and when the winds have a south or southwesterly fetch associated with a slow-moving, intense cold front (Cardone 1980). In the Gulf of Alaska, it is important to consider the inter- action of waves with tidal and other currents. Wind oppos- ing water movement alters the shape and speed of waves. Coastal inlets of the Gulf are typified by large tidal-height ranges with associated tidal current speeds of up to 150 cm/s (Cook Inlet; Muench and Schumacher 1980). The waves steepen when incoming seas or swell is opposed by the ebb flow from inlets and straits. The predominant surface cur- rent is westward around the perimeter of the Gulf in response to the cyclones that dominate the region. Locally generated seas opposing this flow may steepen from their interaction with the current and may become an important hazard to navigation. Local Meteorology The mountain arc that bounds three sides of the Gulf of Alaska has a dominant influence upon the meteorology of the coastal zone. Topography modifies wind fields, pre- cipitation, and visibility associated with a particular storm y ^^ ----- ^x. !1= x> 56°N 148°W 52°Ni:>60W 51°N136°W Nov Dk< Jan Fkb Mar Apr May |i \ |i i \i <. sip Figure 2-25. Monthly-mean significant wave height (in< lud- ing seas and swell) at three Gulf of Alaska NDBO buoys foi the period 1972 to 15)81. The vertical bars are the monthh standard deviations at 56°N, 148°W. (Modified from Gilhousen el al. 1983.) structure; the storm structure itself is modified by the pres- ence of the mountain arc. Over the open ocean, low-pressure cyclones have hori- zontal scales of from 500 to 1,000 km (Fig. 2-2). On these scales there is a very strong balance between the pres- sure-gradient force (the field of mass) and the Coriolis force (the field of motion). This results in the geostrophic balance. When imbalances occur due to variations in sea-surface temperatures, small-scale radiation, or latent-heat release in clouds, the wind field and the mass field will return to a geostrophically balanced state. This occurs within about 12 hours through a process called geostrophic adjustment. If, however, a high coastal mountain arc is present, the wind field near the surface cannot flow through the mountain barrier. Therefore, a geostrophic balance cannot be main- tained with a pressure gradient oriented parallel to the mountain chain. This imbalance has major consequences both for the modification of storm systems as they approach the coast and for the resulting coastal wind fields. < 56°N 148°W 52°N1560W 51°N 136°W Oct Nov Dec Jan Feb Mar Apr May |i N |i i \i <. Sep Figure 2-26. Maximum significant wave heights (including seas and swell) at the same three Gulf of Alaska offshore NDBO buoys as shown in Figure 2-25. The 99 percentile values for each month were used because they had an average of 16 occur- rences (vs. 1 for the 100 percentile) in the period from 1972 to 1981. (Modified from Gilhousen etal 1983.) 46 Physical Environment Nearshore Winds Analysis of the equations of atmospheric motion (Over- land 1984) shows that wind fields within a distance of 80 km of a 1,500- to 2,000-m high coastal mountain range are sys- tematically modified by the presence of the topography. Beyond this distance (technically known as the Rossby radius of deformation), air flow is cyclonic around a low-pressure system as shown in Figure 2-2. Within the Rossby radius, the response of the wind depends upon the orientation of the lines of constant sea-level pressure (isobars) to the coastline. If the isobars are aligned parallel to the coastline, the winds can continue to flow parallel to the isobars in a near-geostrophic momen- tum balance. If, however, the isobars are perpendicular to the coastline, the winds cannot blow through the mountain wall. They will tend to flow, instead, from regions of high atmospheric pressure to regions of low pressure. A special case is marine straits whose widths are the same or smaller than the Rossby radius (Fig. 2-27). Here winds tend to accel- erate from regions of high pressure to regions of low pres- sure when the pressure gradient is parallel to the axis of the strait (i.e., the isobars are perpendicular to the strait). For example, in the vicinity of Kodiak Island, on 4 March 1983, the NOAA WP-3D research aircraft rapidly mapped the spatial variation of the surface wind field and sea-level pressure field (Fig. 2-28) (Macklin, Overland, and Walker 1984). The wind field to the east (seaward) of the Kennedy and Stevenson entrances to Cook Inlet showed winds roughly parallel to the isobars over the open ocean. The winds in Cook Inlet flowed from high pressure in the north to low pressure further south. In Shelikof Strait there was some turning of the winds at the northeast entrance, but in the Strait proper, winds increased in magnitude toward the southwest as they accelerated down the pressure gradient, the so-called gap wind (Overland and Walter 1981). There are abrupt changes in the wind field at the exits to straits, such as the southern end of Shelikof. Such rapid changes in the wind field produce very confused wave fields and must 2300m Alaska Peninsula Kodiak Island Figure 2-27. Topography of Kodiak Island and the Alaska Pen- insula thai bound Shelikof Strait (on a 10-km grid). Vertical exaggeration x 40. Midnight (GMT) March 4, 1983 Wind speed at 90m 20m/s Figure 2-28. Sea-level pressures (mb) and 90-m wind meas- urements (mis) from the NOAA WP-3D aircraft (additional pressures from large-scale analysis). Winds in Shelikof Strait turn toward the pressure gradient parallel to the axis of the Strait with rapid readjustment to geostrophic conditions at the southern exit region. The offshore wind field is seen on the right side of the figure. (Modified from Macklin et al. 1984.) certainly have an influence on local ocean upwelling patterns. Katabatic Winds A second class of coastal winds is katabatic flow, charac- terized by cold air masses at higher elevations that accelerate down slope as a result of gravity and a large-scale pressure gradient. These flows funnel through straits and fjords and influence coastal regions (Reynolds, Macklin, and Heister 1981). Historically, katabatic flow is divided by length scale into fall (also called bora or Taku) winds and gravity winds. Fall winds are a large-scale phenomenon driven by the large-scale pressure gradient and a reservoir of cold air in an elevated interior of the coastal mountains. The air in the interior is cold enough to remain cold relative to the sur- rounding air mass as it descends, despite the tendency of descending air to warm due to higher pressure at lower altitudes. As the cold air flows down to the sea, it accelerates and becomes highly turbulent (Defant 1951). A typical winter weather situation is shown in Figure 2-29 (Reynolds et al. 1981), where high pressure and cold temperatures exist inland with a low-pressure center offshore. This situation where the cold air is accelerated down slope by gravity rein- forced by the pressure-gradient forces is favorable for wide-spread katabatic flow throughout Southeast Alaska (Kilday 1970). In Figure 2-29, the wind barb northeast of 'A' and lines of clouds at 'B' are both perpendicular to the lines Meteorology 47 200km Figure 2-29. Satellite photograph of the Gulf of Alaska show- ing winds blowing away from the coast and their modification into the synoptic scale pattern. (Modified from Reynolds el al. 1981.) On the wind barb, short crossbars indicate 5-kt wind speed increment; long bars indicate 10 knots. of constant pressure, indicating katabatic winds. Observa- tions show that wind onset times and maximum velocities are both independent of time of day. Often, large land/sea temperature differences are suffi- cient to produce near-continuous offshore flow. A cold con- tinental air mass maintains the interior pressure higher than the warmer ocean regions. Often, these winds flow down large river valleys such as the Susitna Valley at the head of Cook Inlet. In the vicinity of Anchorage, the winds are channeled down Cook Inlet and dominate the winter wind field as far south as Augustine Island (Macklin, Lindsay, and Reynolds 1980). When the pressure gradient is increased by an approaching oceanic cyclone, the winds can become quite intense. The gravity wind is a local katabatic flow. Interchange- ably called 'drainage wind', 'mountain wind', or 'katabatic wind', it is caused by greater air density next to a mountain slope than at the same elevation away from the slope. Highly dependent on net radiation at the surface, the air flows downhill in balance with frictional drag, the Coriolis force, and the large-scale pressure field. Because of the earth's rotation, the flow is inclined away from the line of steepest descent (Ball I960), but is still focused into valleys and estu- aries where violent winds can occur. In many locations, katabatic winds are highly intense and short-lived. One particular type of gravity wind is the glacier wind, which is a continuous flow down the surface of the glacier. Glacier winds are relatively independent of solar heating (Defant 1951). Its thermal gradient is due to the tem- perature difference between the ice surface and free air at the same elevation. In general, these winds are relatively light, but there are dramatic exceptions. Virtually every Alaskan estuary along the mountainous coastline is dominated by outflow resulting from katabatic drainage. Winds at the mouths of estuaries such as Icy Bay on the southeast coast of Alaska often exhibit up to 50-m/s velocities (Searby 1969). When the estuary is the terminus of one or more glaciers, outflow winds show little diurnal varia- tion and are relatively persistent, especially in the winter months. Estuaries without glaciers exhibit more diurnal katabatic winds, called nocturnal winds. At the coast, an off- shore wind often flows under the prevailing maritime air mass. An example of the offshore persistence of katabatic flow off of Malaspina Glacier is shown in Figure 2-30 (Reynolds el al. 1981). Data for this example were measured on a tran- sect completed by the NOAA Ship Discoverer. A transition to a marine air mass occurred between 19 and 29 km offshore. One can only speculate that the abrupt transition to a nearly geostrophic flow occurs at a distance where the coastal mountain influence on geostrophic adjustment is diminished. There is onshore flow when high pressure exists over the Gulf and a low-pressure center is present over Alaska. This is one of the few situations when there is flow inland through the gaps in the mountains (Overland and Heister 1978). Storm/Mountain Interaction The lack of geostrophic adjustment in the surface layers of the atmosphere adjacent to a mountainous coastline must not only modify the surface wind but modify the storm structure as well. When a storm such as the one shown in Figure 2-31 (top) (Reynolds 1983) strikes the coast, a second- ary low-pressure feature can often be observed later to the north of the original low-pressure center (Fig. 2-31. middle and bottom). As the parent storm is impeded by the Alaskan coastline, two phenomena result: 1) the low is distorted due to a tightening of the low-level pressure gradient normal to the shore, and 2) the distorted low then combines with favor- able conditions for offshore-katabatic winds to create an intense, shallow front, which generally resides within 60 km of the coast. The presence of a secondary low (Fig. 2-31) can be the result of several conditions, including: 1) northward propa- gation of energy from the parent low along the moun- tainous coast, 2) local storm development due to the low-level convergence of the wind field, and 3) instability associated with extreme horizontal-temperature gradients at the front. Clearly, this area requires more research. 48 Phisicm Environment Yakulal Bay Ft. Manby ,-0206 ""= 0644 Wind speed(kt) ^^ <7.5 ^ 7.5-12.5 ^ 12.5-17.5 Pressure (mb) I emperature (C) I Station ^2-202Lm"b -6.4 1230 -thm] / Dew point (C) Time (GMT) 0 10km Figure 2-30. Weather map for the northeast Gulf of Alaska, 1200 GMT, 9 March 1976 (top). Temperatures (above circles) and dewpoints (below circles) are in F, pressure contours in mb - 1000. Surface observations for the NOAA ship Discoverer 9 March 1976 trackline (bottom). Open circles indicate clear skies; atmospheric pressure coded as (mb- 1000) x 10. (Modi- fied from Reynolds et al. 19X1.) Conclusions Effect of Weather on Ocean Circulation One of the most obvious effects the weather has on the ocean is in the generation of wind-induced currents. Research has established that weather in the Gulf is domi- nated by the presence of low-pressure atmospheric systems in winter and that cyclone activity exists throughout the year. A low-pressure center in the Gulf of Alaska along with its associated counter-clockwise winds induce divergent flow at the ocean surface. Because the Gulf is ringed by land to the east, north, and west, the divergence of surface flow is Midnight (GMT) March 7, 1977 1 1 \ \ 1 1 Midnight (GMT) / \ 1 March 8, 1977 / •^c^O 1 / 60 ^~\^r- ^N / / \ / \ &> l\ N^ \ \ \ ) 8k ' \ \ w "A jWfi 55 / _ -5100- 1 i / / ' 1 \ Noon (GMT) | / March 8, 1977 \^^—<^ ' 60 1 \ I \ \ I 1 V. 1 -984 -"^CyQ ' / 55 - 1 / © / / / 1 #\ /? 145 140 135 130 Figure 2-31. Three weather maps showing the northwestward shift of a surface low-pressure center as the system impacts the coast. There is an associated northward propagation of a wave in the 500-mb height field. The solid lines are contours.of sea- level pressure (mb); the clashed lines are heights (m) of the 500-mb pressure surface. (Modified from Reynolds 1983.) Ml IK)KOIO(A 49 trapped by the coast. As water piles up along the coast, sea-level height increases. A barotropic pressure gradient develops perpendicular to the coast and generates a west- ward-flowing alongshore current called the Alaska Coastal Current (Rover 1983; Schumacher and Reed 1983). Along the Aleutian Islands, the picture changes because the coastal area is no longer persistently to the north or east of passing low-pressure centers. Averaged over a winter sea- son, the coastal current along the Aleutians is not as nar- rowly confined to the coast as the Alaska Coastal Current (Rover 1983) and mean transport is small. However, indi- vidual storms induce strong transport on- or offshore (J.D. Schumacher, PMEL/NOAA, pers. comm.). In the summer months, anticyclonic winds associated with the east Pacific high-pressure system and the cyclonic winds of weak low-pressure systems are much less intense than those produced by winter cyclones. For this reason, sur- face currents driven by summer winds in the northern and eastern Gulf are much weaker (Reed and Schumacher, Ch. 3, this volume). Downwelling and upwelling in the ocean are related to the component of the surface wind that runs parallel to the shoreline. The mean alongshore wind component is south- erly in the eastern Gulf and easterly along the Kenai Penin- sula and northcentral Gulf coast, favoring coastal con- vergence and downwelling in the ocean. It is westerly at Unimak Pass, favoring upwelling and offshore transport of water (J.D. Schumacher, PMEL/NOAA, pers. comm.) (Fig. 2-32). Strickland and Sibley (1984) used the upwelling index in Ingraham et al. (1976) to produce Figure 2-33. Downwell- ing is clearly indicated east of Kodiak Island throughout the winter, with weak upwelling from May through September. Upwelling, albeit weak, dominates the pattern in the vicinity of Unimak Pass. In addition to wind-driven currents, cyclones in the Gulf of Alaska influence the coastal currents through the runoff of precipitation (Fig. 2-21). Freshwater runoff is added to the coastal waters, thereby inducing a salinity (density) gra- dient that enhances the density-driven component of the coastal current (Rover 1982; Schumacher and Reed 1983). The swift current extends from Southeast Alaska to Kodiak Island. The current is maintained as a narrow jet along the coast by the onshore Ekman transport associated with winds over the northcentral and eastern Gulf. The seasonal cycle and anomalies of sea level and transport are well correlated with precipitation and runoff rates (Rover 1979). Precipita- tion runoff along the coast of the Gulf of Alaska is one of the major contributors to the seasonal variability of the Alaskan Stream and Alaska Coastal Current. In the eastern Gulf, sea-surface temperature anomalies may be caused by a wave-like coastal propagation of warm water northward from the tropical Pacific. However, the anomalies are more likely caused by increased southeastern winds. Such winds are associated with an intensified Aleu- tian low that induces a northward transport of relatively warm water (Emery and Hamilton 1985). Anomalies in the western and central Gulf are the result of local air-sea transfer. During episodes of cold-air outflow through river valleys like the Copper River, the water column is quickly cooled. kt'iiai Peninsula S\V Kodiak Island Shumagin Islands Jan Feb Mar Apr May Jin Jll Aug Sep OCT No\ m< Jan Figure 2-32. Monthly-mean along-shelf (240°) wind compo- nent of the geostrophic wind for the period from l'.)7*i to 1980 (from J.D. Schumacher, PMEL/NOAA, pers. comm.). Winds are derived from hemispheric gridded pressure data. Positive val- ues favor coastal convergence and downwelling in the ocean. The cold, fresh water contains a huge volume of suspended sediments and may become unstable and sink toward the sea floor. This process may be an important consideration in understanding the distribution of suspended sediments in coastal areas (Feely, Baker, Schumacher, Massoth, and Landing 1979). Effect of Weather on Regional Biology The Gulf of Alaska is a very important world fishery (OCSEAP Staff, Ch. 14, this volume; Rogers, Ch. 15, this vol- ume). Understanding the physical environment of the Gulf is important to fishery management. One important factor in determining the reproductive success for many species of fish is the transport by water motion of eggs and larvae in nursery regions. The dominant 170 160 150 140 130 Figure 2-33. Monthly distribution of coastal upwelling and downwelling (m3/s per kilometer of coast) in the Gulf of Alaska. (Modified from Strickland and Sibley 1984: Fig. 21.) Positive val- ues (shaded) denote upwelling. (Modified after Ingraham rt al. l'lTli.) 50 Physical Environment winds associated with lows crossing the Gulf generally favor coastal convergence, so that fish eggs and larvae remain in their coastal nursery areas over the continental shelf. Bailey (1981) studied the Pacific whiting and found that the distance of larvae from shore was positively correlated with the wind-driven Ekman transport. Since the juvenile nurseries are inshore, offshore Ekman transport is negatively corre- lated with year-class strength (a measure of the number of adult fish available to the fishery in any one year). Strong winds associated with storms that induce offshore transport in the coastal regions of the Gulf of Alaska may be catastrophic for pelagic fish eggs and larvae. This is because thev will be transported away from their nutrient-rich nurs- eries over the shelf into either the swift Alaskan Stream or Alaska Coastal Current. Wind-driven coastal convergence also affects sea level, where high sea levels correspond both to onshore con- vergence and to reduced offshore transport. Mysak, Hsieh, and Parsons (1982) found a high positive correlation between the year-class strength of herring and the sea level in northern British Columbia. High sea level is also well cor- related with the survival of herring larvae in inshore nurs- eries (Stevenson 1962). Storm winds mix the upper layers of the ocean. In shal- low regions, this mixing may extend to the sea floor. In years when storms are frequent, Sambrotto and Goering (1983) found high biological production levels and an increase in total organic matter that reached the benthos (ocean bottom community). During annual phytoplankton blooms, the upper ocean stratification (which is roughly inversely pro- portional to mixing) is important to the rate of nitrate uptake by the plankton (Sambrotto and Goering 1983). Stratification increases under calm conditions, thus short- ening the period of high nitrate uptake and limiting the period of the phytoplankton bloom. While it is important to consider both mean quantities and any significant deviations from these means, one must not forget that a single storm of sufficient magnitude can alter ocean stratification, water properties, and transport. It is the sum of these individual events that affect the survival of living organisms. An understanding of the atmospheric environment provides valuable explanations for variability in the biological populations of the ocean. across the region. This phenomenon is most common in January and is associated with higher air temperatures, lower wind speeds, and reduced heat fluxes from the ocean. Winter winds in the western Gulf are highly variable depending on where the low-pressure center of a storm is located. The central and eastern portions of the Gulf (domi- nated by dissipating low-pressure systems) are charac- terized by winds that are southwesterly to southeasterly along Southeast Alaska and easterly in the northcentral Gulf. These winds vary in magnitude with the storm system. In the summer, winds are generally light. Acknowledgments This study is a contribution to the Marine Services Proj- ect at the Pacific Marine Environmental Laboratory of the National Oceanic and Atmospheric Administration (NOAA). It was funded in part by the Minerals Management Service, Department of the Interior, through an interagency agreement with NOAA, as part of the Outer Continental Shelf Environmental Assessment Program. We wish to thankJ.D. Schumacher and R.K. Reed for their help in com- posing a coherent view of the Gulf of Alaska. We also thank our two anonymous reviewers and S.A. Macklin, N.A. Bond, and L.A. McMurdie for their valuable comments, L.K. Lu and R.L. Whitney for typing the manuscript, and J.G. Regis- ter for providing the graphics. This chapter is published as contribution number 754 from the NOAA/Pacific Marine Environmental Laboratory. General Weather Review Statistically, the movement of low-pressure systems across the Gulf of Alaska is determined by two factors: 1) the relative position of the Siberian high-pressure system in the winter, and 2) the east Pacific high in the summer. At any one time, the track of an individual low-pressure center is controlled by upper-level flow. Many of the cyclones that enter the Gulf are stalled by the high mountains that encir- cle the region, causing them to dissipate. The weather in the western Gulf in winter is determined by frequent storm pas- sage (Aleutian low) and is highly variable. The eastern Gulf is characterized by steady conditions associated with dis- sipating lows. Weather changes are mainly due to the pres- ence or absence of a high-pressure ridge over the Gulf or North Pacific that blocks the normal progression of storms Meteorology 51 References Angell,J.K. and J. Korshover 1982 Comparison of year-average latitude, long- itude and pressure of the four centers of action with air and sea temperature, 1899-1978. Monthly Weather Review 110:300-303. Bailey, K.M. 1981 Larval transport and recruitment of Pacific hake Merluccius product/us. Marine Ecology — Pro- gress Series 6:1-9. Ball, F.K. 1960 Winds on the ice slopes of Antarctica. In: Ant- arctic Meteorology: Proceedings of the Symposium held in Melbourne. Pergamon Press, London, pp. 9-16. Blackmon, M.L., J.M. Wallace, N.-C. Lau, and S.L. Mullen 1977 An observational study of the Northern Hemi- sphere wintertime circulation. Journal of Atmo- spheric Science 34:1040-1053. Brower, W.A., Jr., H.F. Diaz, A.S. Prechtel, H.W. Searby, andJ.L. Wise 1977 Climatic Atlas of the Outer Continental Shelf Waters and Coastal Regions of Alaska, Vol. 1, Gulf of Alaska. Arctic Environmental Information and Data Center, University of Alaska, Anchorage, AK. National Climate Center, Environmental Data Service, NOAA, Asheville, NC. 439 pp. Budyko, M.I. 1974 Climate and Life. International Geophysics Review, Vol. 18. D.H. Miller, editor (English ver- sion). Academic Press, San Francisco, CA. 508 pp. Businger,J.A. 1973 Turbulent transfer in the atmospheric surface layer. In: Workshop on Micrometeorology. Ameri- can Meteorological Society, Boston, MA. pp. 67-100. Cardone, V.J. 1980 Case studies of four severe Gulf of Alaska storms. NOAA Technical Memorandum ERL/ PMEL-19. 68 pp. Comiskey, A.L. 1976 Vessel icing — know when to expect it. Alaska Seas and Coasts 4:6-7. Defant, F. 1951 Local winds. In: Compendium of Meteorology. T.F. Malone. editor. American Meteorological Soci- ety, Boston, MA. pp. 655-672. Dorman, C.E. and R.H. Bourke 1978 A temperature correction for Tucker's ocean rainfall estimates. Quarterly Journal of the Royal Meteorological Society 104:765-773. Egger>J- 1978 Dynamics of blocking highs. Journal of Atmo- spheric Science 35:1788-1801. Elliott, W.P. and R.K. Reed 1984 A climatological estimate of precipitation for the world ocean. Journal of Climate and Applied Meteorology 23:434-439. Emery, W.J. and K. Hamilton 1985 Atmospheric forcing of interannual variability in the northeast Pacific Ocean: connections with El Nino. Journal of Geophysical Research 90C:857-868. Favorite, F., A.J. Dodimead, and K. Nasu 1976 Oceanography of the subarctic Pacific region, 1960-71. International North Pacific Fisheries Commission Bulletin No. 33. 187 pp. Feely, R.A., E.T. Baker, J. D. Schumacher, G.J. Massoth, and W.M. Landing 1979 Processes affecting the distribution and trans- port of suspended matter in the northeast Gulf of Alaska. Deep-Sea Research 26:445-464. Fleagle, R.J. and W.A. Nuss 1985 The distribution of surface fluxes and bound- ary layer divergence in mid-latitude ocean storms.Journal of Atmospheric Science 42:784-799. Gilhousen, D.B., R.G. Quayle, R.G. Baldwin, T.R. Karl, and R.O. Brines 1983 Climatic summaries for NOAA data buoys. National Climatic Data Center, National Weather Service, NOAA Data Buoy Center, NSTL Station, MS. 214 pp. Grubbs, B.E. and R.D. McCollum, Jr. 1968 A climatological guide to Alaskan weather. Unpublished report, Scientific Services Sec- tion, 11th Weather Squadron, Elmendorf Air Force Base, AK. Guttman, N.B. 1975 Study of fog and stratus for selected cold regions. U.S. Naval Weather Service Com- mand, National Climate Center, Asheville, NC. 85 pp. Gyakum,J.R. 1983 On the evolution of the QEII Storm. II: Dynamic and thermodynamic structure. Monthly Weather Review 111:1156-1173. Han, Y.-J. and S.-W. Lee 1983 An analysis of monthly mean wind stress over the global ocean. Monthly Weather Review 111:1554-1566. Hartmann, D.L. 1974 Time spectral analysis of mid-latitude distur- bances. Monthly Weather Review 102:348-362. 52 PinsicAL Environment Hartmann, D.L. and S.J. Ghan 1980 A statistical study of the dynamics of blocking. Monthly Weather Review 108:1144-1159. Hellerman, S. and M. Rosenstein 1983 Normal monthly wind stress oyer the world ocean with error estimates. Journal of Physical Oceanography 13:1093-1104. Holopainen, E. 1984 Statistical local effect of synoptic-scale tran- sient eddies on the time-mean flow in the northern extratropics in winter. Journal of Atmo- spheric Science 41:2505-2515. Ingraham, W.J. Jr., A. Bakun, and F. Favorite 1976 Physical Oceanography of the Gulf of Alaska. Environmental Assessment of the Alaskan Continen- tal Shelf Final Reports of Principal Investigators 3:845-978. Kikuchi, Y. 1969 Numerical simulation of the blocking process. Journal of the Meteorological Society of Japan 47:29-54. Kikuchi, Y. 1971 Influence of mountains and land-sea distribu- tion on blocking action. Journal of the Mete- orological Society of Japan 49:564-572. Kilday, G.D. 1970 Taku winds at Juneau, Alaska. National Weather Service Office Memo, Juneau, AK. 8 pp. Klein, W.H. 1957 Principal tracks and mean frequencies of cyclones and anticyclones in the Northern Hemisphere. Research Paper No. 40, U.S. Weather Bureau, U.S. Government Printing Office, Washington, D.C. 60 pp. Kutsuwada, K. and K. Sakurai 1982 Climatological maps of wind stress field over the North Pacific Ocean. The Oceanographical Magazine 32:25-46. Lau, N.-C. 1981 A diagnostic study of recurrent meteorological anomalies appearing in a 15-year simulation with a GFDL general circulation model. Monthly Weather Review 109:2287-2311. Lejenas, H. and H. Okland 1983 Characteristics of northern hemisphere block- ing as determined from a long time series of observational data. Tellus 35A:350-362. Macklin, S.A., R.W. Lindsay, and R.M. Reynolds 1980 Observations of mesoscale winds in an orographically-dominated estuary: Cook Inlet, Alaska. In: Second Conference on Coastal Mete- orology, January 30-February 1, 1980. American Meteorological Society, Boston, MA. pp. 176-180. Macklin, S.A., J.E. Overland, andJ.P. Walker 1984 Low-level gap winds in Shelikof Strait. In: Third Technical Conference on Meteorology of the Coastal Zone, American Meteorological Society, 9-13 January, 1984, Miami, FL. Paper JC-7.4. pp. 97-102. McClain, D.R. 1983 Coastal ocean warming in the Northeast Pacific, 1976-83. In: The Influence of Ocean Condi- tions on the Production of Salmonids in the North Pacific: A Workshop. W.G. Pearcy, editor. Sea Grant College Program, ORESU-W-83-001, Oregon State University, Corvallis, OR. pp. 61-83. Muench, R.D. andJ.D. Schumacher 1980 Physical oceanographic and meteorological conditions in the northwest Gulf of Alaska. NOAA Technical Memorandum ERL/PMEL- 72. 147 pp. Mullen, S.L. 1983 Explosive cyclogenesis associated with cyclones in polar air streams. Monthly Weather Review 111:1537-1553. Murty, T.S., G.A. McBean, and B. McKee 1983 Explosive cyclogenesis over the northeast Pacific Ocean. Monthly Weather Review 111:1131-1135. Mysak, L.A., W.W. Hsieh, and T.R. Parsons 1982 On the relationship between interannual bar- oclinic waves and fish populations in the north- east Pacific. Biological Oceanography 2:63-103. Overland, J.E. 1984 Scale analysis of marine winds in straits and along mountainous coasts. Monthly Weather Review 112:2530-2534. Overland, J.E. and T.R. Heister 1978 A synoptic climatology for surface winds along the southern coast of Alaska. OCSEAP report, Research Unit 140. Environmental Research Laboratory/Pacific Marine Environmental Lab- oratory, NOAA, Seattle, WA. 112 pp. Overland, J.E. and T.R. Heister 1980 Development of a synoptic climatology for the northeast Gulf of Maska.Journal of Applied Mete- orology 19:1-14. Meteorology 53 Overland, J. E. and t.H. Pease 1982 Cyclone climatology of the Bering Sea and its relation to sea ice extent. Monthly Weather Review 110:5-13. Overland, J.E. and B.A. Walter, Jr. 1981 Gap winds in the Strait ofjuan de Fuca. Monthly Weather Review 109:2221-2233. Overland, J.E. andJ.G. Wilson 1984 Mesoscale variability in marine winds at mid- latitude, journal of Geophysical Research 89C:10599-10614. Overland, J.E., C.H. Pease, R.W. Preisendorfer, and A.L. Comiskey 1986 A robust algorithm for prediction of vessel icing. Journal of Climate and Applied Meteorology (in press). Poole, F.W. and G.L. Hufford 1982 Meteorological and oceanographic factors affecting sea ice in Cook InletJoumal of Geophys- ical Research 87C:2061-207(). Reed, R.K. and W.P. Elliott 1979 New precipitation maps for the North Atlantic and North Pacific oceans. Journal of Geophysical Research 84C:7839-7846. Reitan, C.H. 1974 Frequencies of cyclones and cyclogenesis for North America, 1951-1970. Monthly Weather Review 102:861-868. Rex, D.F. 1950 Blocking action in the middle troposphere and its effect upon regional climate. II. The cli- matology of blocking action. Tellus 2:275-301. Reynolds, R.M. 1983 Occurrence and structure of mesoscale fronts and cyclones near Icy Bay, Alaska. Monthly Weather Review 111:1938-1948. Reynolds, R.M., S.A. Macklin, and T.R. Heister 1981 Observations of South Alaskan coastal winds. NOAA Technical Memorandum ERL/PMEL- 31. 49 pp. Richardson, R.W. 1936 Winter air-mass convergence over the North Roden, G. 1970 Pacific. Monthly Weather Review 64:199-203. Aspects of the mid-Pacific transition zone. Journal of Geophysical Research 75:1097-1109. Rogers, J.C. 1981 The North Pacific oscillation, journal oj Cli- matology 1:39-57. Royer, T.C. 1979 On the effect of precipitation and runoff on coastal circulation in the Gulf of Alaska. Journal of Physical Oceanography 9:555-563. Royer, T.C. 1982 Coastal fresh water discharge in the northeast Pacific. Journal of Geophysical Research 87:2017-2021. Royer, T.C. 1983 Observations of the Alaska Coastal Current. In: Coastal Oceanography, H.G. Gade, A. Edwards, and H. Svendsen, editors. Plenum Press, New York, NY. pp. 9-30. Sambrotto, R.N. and J.J. Goering 1983 Interannual variability of phytoplankton and zooplankton production on the southeast Ber- ing Sea shelf. In: From Year to Year: Interannual Variability of the Environment and Fisheries of the Gulf of Alaska and the Eastern Bering Sea. W.S. Wooster, editor. Washington Sea Grant Pub- lication 83-3, University of Washington, Seattle, WA. pp. 161-177. Schumacher, J.D. and R.K. Reed 1983 Interannual variability in the abiotic environ- ment of the Bering Sea and the Gulf of Alaska. In: From Year to Year: Interannual Variability of the Environment and Fisheries of the Gulf of Alaska and the Eastern Bering Sea. W.S. Wooster, editor. Washington Sea Grant Publication 83-3, Uni- versity of Washington, Seattle, WA. pp. 111-133. Searby, H.W. 1969 Coastal weather marine data summary for the Gulf of Alaska, Cape Spencer westward to Kodiak Island. U.S. Department of Commerce Environmental Science Services Administra- tion Technical Memorandum 8. 30 pp. Shepard, F.P. 1973 Submarine Geology. Harper & Row, San Fran- cisco, CA. 517 pp. Stevenson, J.C. 1962 Distribution and survival of herring larvae (Clupea pallasi Valenciennes) in British Colum- bia waters. Journal of the Fisheries Research Board of Canada 19:735-810. Roebber, P.J. 1984 Statistical analysis and updated climatology' of explosive cvclones. Monthly Weather Review 112:1577-1589. 54 Physical Environment Strickland, R. and T. Sibley 1984 Projected effects of C02-induced climate change on the Alaska Pollock (Theragra chal- cogramma) fishery in the eastern Bering Sea and Gulf of Alaska. Final report to Lawrence Berke- ley Laboratory. Contract No. 4524910. Report FRI-UW-8411, Fisheries Research Institute, University of Washington, Seattle, WA. 112 pp. Talley, L.D. 1984 Meridional heat transport in the Pacific Ocean. Journal of Physical Oceanography 14:231-241. Treidl, R.A., E.C. Birch, and P. Sajecki 1981 Blocking action in the Northern Hemisphere: a climatological study. Atmosphere-Ocean 19:1-23. Tung, K.K. and R.S. Lindzen 1979 A theory of stationary long waves. Part I: a sim- ple theory of blocking. Monthly Weather Review 107:714-734. Walker, G.T. and E.W. Bliss 1932 World weather V. Memoirs of the Royal Mete- orological Society 4:53. Walter, B.A. 1980 Wintertime observations of roll clouds over the Bering Sea. Monthly Weather Review 108:2024- 2031. White, W.B. and N.E. Clark 1975 On the development of blocking ridge activity over the central North Pacific. Journal of Atmo- spheric Science 32:489-502. Whittaker, L.M. and L.H. Horn 1982 Atlas of Northern Hemisphere extratropical cyclone activity, 1958-1977. Department of Meteorology, University of Wisconsin, Madison, WI. 65 pp. Wise, J.L. and A.L. Comiskey 1980 Superstructure icing in Alaskan waters. NOAA Special Report, Pacific Marine Environmental Laboratory, Seattle, WA. 30 pp. Physical Oceanography Ronald K. Reed James D. Schumacher Pacific Marine Environmental Laboratory National Oceanic and Atmospheric Administration Seattle, Washington Abstract We review the state of both the circulation and the physical property knowledge for the Gulf of Alaska. The largest-scale feature we cover is the offshore boundary current. This current is relatively wide ( ~ 400 km) and slow ( ~ 30 cm/s) on the east side of the Gulf, but it narrows to less than 100 km from Kodiak Island westward, with peak speeds of ~ 100 cm/s. Although occasional large changes occur in the path, trans- port, and properties of the Alaskan Stream, high-frequency variability is not typical. The Stream may transfer heat and momentum into coastal waters, although the rela- tive importance of this process has not been established. Other features covered by our review include a continental shelf circulation system which is generally separate from the Alaskan Stream. On the outer shelf, there is weak net flow, but circulation seems to be steered by the bathymetry in large troughs which transect the shelf. On the east side of the Gulf, the flow tends to be variable but is probably stronger in winter than in summer as a result of local wind forcing. Along the Kenai Peninsula there is a distinct narrow current flowing westward with typical speeds of 20 cm/s, but which can range as high as 100 cm/s in the fall. This rapid fall spin-up results from a maximum freshwater discharge in September-October, and is accompanied by surface salinities as low as 25 parts per thousand. Winds may constrain the relatively dilute flow along the coast. This geostrophic coastal flow first enters Shelikof Strait where the barotropic mode may be important, then continues west along the Alaska Peninsula. These features of coastal circulation are clearly seen in seasonal sea level cycles at various tide stations. Large interannual changes also occur in the Gulf of Alaska. In general, the wind regime along the coast produces downwelling at the coast rather than upwelling. Introduction This chapter both reviews previous investigations and synthesizes the results obtained from recent measurements in the northern Gulf of Alaska. The focus of this work is a description of 1) the large-scale features of flow and circula- tion, and 2) the distribution of physical properties. We feel that this description is central to any effort to integrate our knowledge and that the results presented here will be of value to researchers in other fields. In addition, certain facets of physical oceanography such as the determination of eddy fluxes of momentum and properties, analysis of the tidal regime, and development of heat and moisture bud- gets are not dealt with in detail. In the chapter, we stress observational rather than theoretical aspects of physical oceanography. The term 'Gulf of Alaska' is here taken as the area north of 52°N and east of 176° W. We discuss offshore circulation and properties, but emphasize coastal oceanography because of the comprehensive Outer Continental Shell Environmental Assessment Program (OCSEAP) on the con- tinental shelf. Readers should note that this shelf (shoreward of the 200-m isobath; see Fig. 3-1) is a vast area in the Gulf of Alaska and is not the narrow feature typical of much of west- ern North America. Investigations before the OCSEAP work, which started in 1974, were summarized by Dodimead, Favorite, and Hirano (1963) and by Favorite, Dodimead, and \asu (1976). Prior to 57 58 Phnsk \i Environment the 1930s, work in the Gulf was carried out by the Interna- tional Fisheries Commission. For example, McEwen, Thompson, and Van Cleve (1930) inferred the existence of a counterclockwise gyre; Goodman and Thompson (1940) investigated conditions in the area; Sverdrup, Johnson, and Fleming (1942) discussed circulation and water properties; and Robinson (1957) analyzed bathythermograph data col- lected in the region through 1952. Dodimead et al. (1963) examined the extensive observa- tions from 1955 through 1959. A considerable amount of observational and analytical work was done in connection with a hydrographic time series at Ocean Station 'P' at 50°N, 145°W (Tabata 1961; Fofonoff and Tabata 1966) (Fig. 3-1). L'da (1963) summarized information on the subarctic Pacific, including the Gulf of Alaska. An interesting aspect of most of this earlier work is that few observations were made in the coastal waters of the Gulf, and conditions on the shelf were virtually ignored. It is tempting to speculate that this omission may have partially resulted from the belief that the geostrophic relation for computing flow was only valid in deep water (Dodimead et al. 1963). However, we now use the relation in water depths of 100 m or less. Favorite et al. (1976) compiled information on the entire subarctic Pacific, including the Gulf of Alaska, and they give numerous data presentations, analyses, and references to earlier studies. Of special interest is a map showing the dis- tribution of hydrocasts as of December 1972, because few observations were available as of that late date in coastal waters of the Gulf. Bogdanov (1961) examined water circula- tion in the Gulf, and Roden (1969) presented results from a synoptic survey conducted in the winter of 1967. In addition, Favorite et al. (1976) list a number of atlases that have treated some aspects of the oceanography of the Gulf of Alaska. An especially useful compilation on the Gulfs marine cli- mate is that of Brower, Diaz, Prechtel, Searby, and Wise (1977). A recent atlas of worldwide subsurface oceanographic data was presented by Levitus (1982). Oceanographic Monthly Summary (produced by NOAA's National Weather Service and National Environmental Sat- ellite, Data, and Information Service) is an ongoing publica- tion that contains monthly maps of sea surface tem- peratures and temperature anomalies for the world's oceans. Sea level information has recently been published by Hicks, Debaugh, and Hickman (1983). The great majority of available data consists of temperature and salinity obser- vations; direct current measurements and water chemistry data are relatively rare. Satellite sensors are steadily being improved, and a considerable increase in observational capability seems imminent. In this review, we will first discuss the offshore circulation and water properties. This offshore system is a major oceanic feature, and understanding it is crucial to under- standing the coastal processes. Next, we examine hydro- graphic data in the coastal waters. As part of this exam- ination, we review the results from direct current measurements on the shelf, as well as analyses of sea level data. Finally, we explore certain aspects of the coastal cir- culation system. 50 Gulf of Alaska study area • Ocean Station I' 50 160 150 Figure 3-1. Schematic representation of the major currents in the Gulf of Alaska. The depth contours are from International Hydro- graphic Office Chart 5.03. Physical Oceanography 59 Offshore Circulation and Properties Offshore water circulation in the Gulf of Alaska is domi- nated by the Alaska Current/Alaskan Stream (e.g., Favorite et al. 1976). This feature is the eastern and poleward boundary of the large-scale, counterclockwise rotating subarctic gyre (see Fig. 3-1). The flow generally parallels the continental slope, taking first a northward and then a westward direc- tion. The flow varies in width from perhaps 300 km near the head of the Gulf to less than 100 km from Kodiak Island west- ward. The waters flowing into the Gulf often exhibit a large clockwise eddy off Sitka, with large eddies or bends also occurring in other areas nearby (Tabata 1982). Reed (1980a) showed the existence of a large eddy near Pratt Seamount ( ~ 56° 30'N, 143° W). On the eastern side of the Gulf, we use the term Alaska Current, but we prefer Alaskan Stream (Dodimead et al. 1963; Favorite 1967) west of about 150°W, because this term seems more descriptive of this high- speed, narrow, deep boundary flow. In general, the Alaskan Stream does not have large velocities in water depths less than 300 m (Reed, Muench, and Schumacher 1980). Although the Stream may affect the inshore circulation, coastal features often seem to be separate, or at least differ- ent, from those offshore. South of the Alaskan Stream is the North Pacific Current, a weak eastward flow. Although recent work has been more concerned with cir- culation and conditions near the coast, rather than offshore, an appreciable amount of data on the Alaskan Stream was collected in the vicinity of Kodiak Island (Reed et al. 1980; Rover 1981a). Furthermore, two surveys of virtually the entire Stream system (Reed 1984) helped redress the limited spatial coverage in much of the work near Kodiak Island. Finally, long-term current measurements in the Stream have increased our understanding of the major charac- teristics of this system (Reed and Schumacher 1984). Property Distributions and Geostrophic Flow Some tvpical distributions of the physical properties in the Alaskan Stream are shown in Figures 3-2 and 3-3; Fig- ure 3-2 is based on data taken in February 1980 near 164°W (just south of Unimak Pass) (Wright 1981), and Figure 3-3 shows conditions off Kodiak Island in September 1981 (Reed 1984). The winter section shows a zone of cold (<4C), low-salinity (<33°/oo) water near the surface which forms as a result of winter cooling and convection (Dodimead et al. 1963). A zone of relatively warm (>5C) water underlies the cold, near-surface water. In general, winter surface tem- peratures decrease from 5 to 6C in the head of the Gulf to less than 3C near the Aleutian Islands. Surface salinity typ- ically decreases toward shore, with values less than 32°/oo on the shelf in winter. The marked similarity of salinity and sig- ma-t or density slopes in Figure 3-2 shows the strong influ- ence of salinity on the density structure in this region. Iso- lines of all properties slope downward sharply near the continental slope, a fact that is reflected bv the maximum computed geostrophic flow of over 80 cm/s. Values in excess of 100 cm/s are often found, especially near the Aleutian Islands (Reed 1984). The summer section (Fig. 3-3) shows sea-surface tem- peratures in excess of 12C and surface salinity generally less than 32.2"/.k>; both values are typical for late summer. Note also the temperature minimum near 100 m depths, which results from failure of near-surface warming to remove all Temperature (C) S SI A I IONS 61 62 64 N 69 ~ 600 Q 800 1000 1200 1400 ~i — ■ — v ■ v • •i Sai.im I \ ("/oo) S S I \ IIONS 61 62 64 N 69 Density (a,) Geostrophic: Flow (cm/s) so 80- 200 600 2 800 1200 D Westward flow [] Eastward lli>\\ Figure 3-2. Vertical sections of temperature, salinity, density, and geostrophic flow (referred to 1,500 db = 0/1.500 db) across the Alaskan Stream at approximately 164°\V, 24-25 February 1980. 60 PmsitAi Environmint Temperature (C) Salini i v (%<>) SE Stations N\V SE Stations NW 94 97 100 106 94 97 100 106 0 200 400 1000 1200 Density (o,) Geostrophic Flow (cm/s) o- L „c 1 1 1 > _a,J-() ^j. a. ^f 24.0 """^ =- — 25.8 -^^ 200 ' 26.8 400 - * — 27.(1 — ' A £ 600 -_27.2^ J X U 800 Q 1000 1200 1400 - | □ -10- J -50 1"7 . I 1 LS0 0 1 — o— " - 1 1(1 — 0- 1 ( i - I I Southwestward flow 1 I Northeastward flow Figure 3-3. Vertical sections of temperature, salinity, density, and geostrophic flow (0/1,500 db) across the Alaskan Stream off Kodiak Island, 6-7 September 1981. vestiges of the cool layer from the previous winter. Two fea- tures of this section are not typical of summer conditions, however: 1) the maximum velocities were relatively weak ( ~ 50 cm/s), and 2) the deep water (even to depths of 1,000 m) was warmer and less saline than the water shown in Figure 3-2. These conditions resulted from the large-scale change in circulation (Reed 1984) that is discussed below. The distribution of surface salinity in the Gulf of Alaska and along the Aleutian Islands in winter 1980 and summer 1981 is shown in Figure 3-4. The large-scale patterns are influenced by factors such as variations in freshwater runoff and precipitation, the structure and intensity of the Alaskan Stream and coastal currents, and the exchange of water through passes between the Aleutian Islands. In offshore waters, the values in summer 1981 were generally about 0.5"/oo less than in winter 1980. This appears to be a typical seasonal difference (Royer 1981a) resulting from increased freshwater discharge in late summer or fall. The most strik- ing difference in these maps is the very dilute water ( < 26°/<>o) that was present along the Kenai Peninsula in September 1981 compared with that in February 1980. While these huge differences clearly reflect the seasonal differences in fresh- water discharge (Schumacher and Reed 1980; Royer 1981b), they will be discussed later in connection with coastal processes. Reed el al. (1980) examined the volume transport of the Stream near Kodiak Island. They attempted to adjust the computations for the existence of density slopes near the bottom in depths less than the reference level (1,500 db). On that basis, a mean adjusted transport of 12 x 106 m3/s was determined for 17 sections. Although temporal variations in transport were present, they were not correlated with the large seasonal variations in integrated wind-stress trans- port. Hence, Reed et al. (1980) drew the conclusion that there were no significant seasonal variations in transport of the Alaskan Stream. Royer (1981a) used these and other data, but he did not adjust the computations for near-bottom density slopes. He inferred that transport does vary seasonally by about 13% of the mean, with a maximum occurring in March. The exis- tence of such a signal is difficult to confirm; the number of hydrocast sections is still quite limited, and the estimates are influenced by spatial as well as temporal variations of the Stream. Some recent results, however, show that seasonal differences are considerably smaller than interannual or year-to-year changes. Geopotential topography of the sea surface (referred to 1,500 db) from cruises in February-March 1980 and August- September 1981 is shown in Figure 3-5. Both maps show westward flow from the head of the Gulf to the western Aleu- tian Islands, but the relief across the flow (and hence speeds and transports) east of 160°W on the second cruise was only about half of the relief recorded on the first cruise. (This dif- ference in flow also explains the relatively warm, fresh sub- surface water noted earlier in Figure 3-3; the normal cold, saline subarctic water was not present just offshore from the Stream.) Normally, the inflowing source waters of the Stream (Alaska Current) flow northward along the east side of the Gulf so that transport is relatively constant from the head of the Gulf westward (as on the upper map). Water flowing into the Stream as far west as 165°W is quite rare (Reed 1984). Thus, the Stream in August-September 1981 had a transport in the Gulf of only about 6 x 106 m3/s, but typical transport of 12 x 106 m3/s occurred along the Aleutian Islands (west of 165° W). This disrupted or split inflow is not a normal seasonal occurrence (Dodimead et al. 1963; Favor- ite et al. 1976; and Ingraham, Bakun, and Favorite 1976). If it does occur preferentially, even though rarely, in summer, it could account for the seasonal signal inferred by Royer (1981a). This change, which is believed to be a sporadic or inter- annual one, was suggested by Reed (1984) to result from an unusual tilt of the pycnocline brought about by the effects of differential Ekman pumping in the region of the inflowing source waters. That is, in summer 1981, wind stress over the east side of the Gulf essentially collapsed, but at the same time, wind stress increased greatly to the west. This created a tendency to divert the inflow northwestward rather than along the eastern boundary. Although the frequency of such Physical Oceanography 61 BO Winter so // oj Alaska ■ CTD casts . Surface water samples 50 Figure 3-4. Distribution of surface salinity (°/oo) during winter (9 February to 9 March 1980) and summer (25 August to 16 September 1981). events is not known, the resulting weak flows and relatively warm, fresh waters in the Gulf may affect biota in the region. We have not presented data on dissolved oxygen and nutrients; however, this information is included in the chap- ter on chemical oceanography (Reeburgh and Kipphut, Ch.4, this volume). We have not shown traditional water- mass analyses (temperature-salinity diagrams and other methods) either, but these are presented in considerable detail in Dodimead et al. (1963), Favorite et at. (1976), Emery and Dewar (1982), and other studies. Direct Current Measurements A number of direct current measurements have been made in the Alaskan Stream. Most of the observations were made using drogued drifting devices and were of very short duration (see F^gs. 14-15 and 14-16, OCSFAP Staff, Ch. 14, this volume). Although much of the information obtained was not highly definitive, investigators found relatively high velocities that were in agreement with geostrophic flow computations (for example, Reed and Taylor 1965). Some drifters were tracked by satellite for longer periods, and thev provided conclusive evidence of recirculation around the Gulf of Alaska gyre (Reed 1980b). During February through August 1980, Reed, Schumacher, and Blaha (1981) obtained a current record at 1,000 m in a depth of about 1,700 m off Kodiak Island. Ten-month records at this site, plus records at an inshore location, were later obtained at four levels: these data have been analyzed (Reed and Schumacher 1984) and are examined here in some detail. Information on these records is presented in Table 3-1. As expected, the data indicate flow to the southwest that decreases with depth. The measured shear was in excellent agreement with the computed geostrophic shear (Reed and Schumacher 1984), but the results imply that the baroclinic flow does not vanish until a depth of about 3,000 meters. On this basis, true transport of the Alaskan Stream in the Gulf of Alaska is about 15 x 106 m:Vs rather than 12 x 106 m3/s (referred to 1,500 db) (Reed 1984). Thus the subarctic gyre 62 Physic :ai Environmi nt Winte Gulf of Alaska Figure 3-5. Geopotential topography (AD, dyn m) of the sea surface (0/1,500 db) during winter (11 February to 3 March 1980) and sum- mer (25 August to 16 September 1981). appears to have a transport about one-third that of the Pacific subtropical gyre. Vector plots of the data from these moorings (Fig. 3-6) indicate remarkable flow stability, especially at the deep Table 3-1. Information on current meter moorings near Kodiak Island (from Reed and Schumacher 1984). Meter Water Net Station Location Depth Depth Dates Flow Variance (m) (m) (cm/s, deg) (cm2/s2) 1 56°39'N 151°46'W 230 700 13Sep81- 11 July 82 28,207 312 2 56°31'N 151°40'W 305 1,730 13Sep81- 22July82 24,219 166 520 13Sep81- 19 Feb 82 19,230 158 1,020 13Sep81- 22 July 82 8,224 54 mooring. Furthermore, the features were extremely coherent vertically, and even small ones tend to be present at all levels. (This similarity of flow in the vertical does not imply a barotropic flow, however; speeds clearly decreased with depth and were in good agreement with computed geo- strophic or baroclinic flow.) Although the flow was relatively stable with time, some low-frequency variations were pre- sent. For example, records from the first two months reveal relatively weak flow, which appears to agree with the time of disrupted inflow to the Stream (Reed 1984). Spectral analysis of these data indicates that the variations were predomi- nantly at the lower frequencies (typically < 0.02/d), whereas a record at 300 m depth on the edge of the Stream (Niebauer, Roberts, and Royer 1981) showed relatively more high-frequency energy. In general, the Stream appears to be considerably more stable (and have lower levels of eddy energy or variance) than typical western boundary currents such as the Gulf Stream and the Kuroshio Current (Reed and Schumacher 1984). We concluded that this probably results from relatively little planetary wave activity in -most of the Stream. Physic ai (J< ianockaphy 63 50 -50 --. 50 Station 1. 230m -50 \/ , /////r'"ir T" nyrr "•*■ "^^^F^^Ffy^^^ rWffF!fltWW'l'FWF tffWf"' wilf^mw''''m'^M Station 2.3<):>m .\\\u -^\. *%r T'/\ir~ " y/jmi^^ m^^w/m//^jT ~^" J~ 50 g o -50 25 Station 2, 520m vs-jf" ' v/yr- W- Station 2. 1020m T^T" — ■ ▼* pjjrsr' '/ » f~'jp/\wvjy/y7 x'/yv ""■■»" */v">/>»#>/? x" r//" [yevr/f 25 Sep ()( i No\ 1981 Dec Jan Ft » Mar Apr 1982 May jUN J' Figure 3-6. Dail) net current vectors (after use of a 35-h filter) at Stations 1 and 2 (Table 3-1), 15 September 1981 to 21 July 1982. Note- scale change for the 1,020-m depth at Station 2. The data at these sites were further used to examine the eddy fluxes of momentum, heat, and salt. The fluxes were generally much smaller than those on the inshore edge of western boundary currents (Reed and Schumacher 1984). Momentum was being transferred from the mean flow to smaller scales, unlike in the Gulf Stream, but our estimate of eddy viscosity was only about 106 cm2/s. As expected, eddy heat flux was onshore; since we did not have data in the upper 200 m. it was not possible to quantify the likely impact of this flux on the shelf waters. In summary, the Alaskan Stream is a high-speed, off- shore boundary for the coastal circulation systems in the Gulf of Alaska. The Stream seems to be quite stable but does occasionally undergo large changes. On the east side of the Gulf, the flow is usually about 400 km wide with peak speeds of about 30 cm/s; near Kodiak Island and westward, the Stream is typically less than 100 km wide and has peak speeds of 100 cm/s. Coastal Circulation and Properties As we noted earlier, a very limited amount of data had been obtained in coastal waters of the Gulf of Alaska prior to 1974, and few detailed analyses had appeared. Sea level data as well as temperature and density observations at tide stations existed, of course, but only limited efforts (Reid and Mantyla 1976) had been made to interpret them in terms of oceanographic conditions on the shelf. While there was a large increase in the number of hvdrocasts as a result of OGSEAP-sponsored field studies in the Gulf, an even more striking change took place in the availability of direct cur- rent measurements. We will attempt to summarize and extend these results. Property Distributions and Geostrophic Flow Distribution of surface salinity in both the Alaskan Stream and over a sizable portion of the shelf is shown in Figure 3-4. This figure shows that the salinity of coastal waters may change seasonally as much as seven parts per thousand. Although the surface temperature of coastal waters varies by about 7C from winter to summer, this only alters density by about one sigma-t unit, whereas the change in salinity affects density four to five times as much. Thus, variations in salinity generally have the largest effects on density distribution and baroclinic flow in this region (Royer 1981a). The distribution of surface salinity has long been used as an index of the offshore circulation (Dodimead et al. 1963), and it appears to be equally useful for inferring coastal flow. In fact, Royer (1979, 1981b, and 1982) concluded that the nearshore, westward coastal current around the Gulf is the result of salinity gradients that are controlled by freshwater discharge from land. Furthermore, this coastal flow or Alaska Coastal Current (Royer 1981b) has a strong seasonal signal with maximum flow in fall during the maximum discharge. The salinity (density) gradients attenuate rapidly with depth, however, so that surface geo- strophic flow (referred to 50 or 100 db) appears to be a good approximation of actual circulation (Royer, Hansen, and Pashinski 1979; Reed and Schumacher 1981). Large amounts of data were not collected in the north east Gulf, but Reed, Schumacher, and Wright (1981) found enough limited information to prepare maps over areas of varying size near Yakutat. Salinity at 10 m and geostrophic flow of the sea surface (referred to 90 db) are shown in Fig- ure 3-7. In March, June, and November the range of salinit) inshore of the 915-m isobath, excluding values inside Yakutat Bay, was only l°/oo or less. In September, there were much lower salinities in a narrow zone nearshore. The geop- otential topography for all periods indicates a weak. 64 Physical Environment Swi\m \i 10 Mi iikM'Voo) 142 140 138 Geopotential Topography at Surface (dyn m) 142 140 138 142 140 138 / J).24- C-\ " September November 138 138 Figure 3-7. Salinity (°/oo) at 10 m and geopotential topography (AD, dyn m) of the sea surface (0/90 db) for the periods: 2 to 22 March 1977 (squares) and 23 to 31 March 1979 (circles); 5 to 12 June 1975; 9 to 11 September 1976 (squares) and 12 to 15 September 1977 (circles); and 1 to 2 November 1975. Figure 3-8. Geopotential topography (AD, dyn m) of the sea surface (0/100 db) during September 1976. (Modified from Royer et al. 1979.) Arrow denotes direction of current flow. Physical Oceanography 65 alongshore flow to the northwest with no apparent increase in How in September. (Use of 50 db as the reference level allows one to extend the data about 20 km farther inshore, an area of low-salinity water during September. This only adds about 3 dyn cm to the range, however, which suggests there was no intense flow inshore.) Although more data would be useful for making these inferences, it seems unlikely that a major increase in speed and transport occurs during the fall, as is typical for the central and western Gulf. Royer et al. (1979) compared maps of dynamic topogra- phy over the central Gulf using results from satel- lite-tracked drifting buoys. Figure 3-8 shows a map of geop- otential topographv at the surface (referred to 100 db). Those contours less than 0.30 dyn m represent the inshore part of the Alaskan Stream; east of Kayak Island ( ~ 144°W), there was little relief shoreward of the Stream. An intense (>50 cm/s) clockwise eddy was present in the lee of Kayak Island, and the coastal flow extended seaward to merge with the oceanic flow. To the west the flows were separate, but there was a large increase in relief across the coastal flow. Royer (1983a) noted that the Kayak eddv appears to be a per- manent feature, and the waters in the eddy should have a relatively long residence time. Surface salinitv distributions are shown in Figure 3-9 along with the salinity at 50 m, and the sigma-t difference between the surface and 50 m for an area along the Kenai Peninsula and in lower Cook Inlet-upper Shelikof Strait during October 1978 (Schumacher and Reed 1980). Salinitv was slightly less along the Kenai Peninsula than in lower Cook Inlet, as shown in Figure 3-4. However, salinities may be even lower at certain times. Horizontal salinity gradients were reduced at depth, and the sigma-t differences were greatest along the Kenai Peninsula where investigators found the lowest surface salinities. The water had no measurable vertical density gradient over Portlock Bank, where tidal mixing is relatively efficient, and scattered zero-gradients existed elsewhere. Vertical sec- tions of temperature, salinity, and sigma-t along the line of stations crossing Portlock Bank for March and October 1978 are shown in Figure 3-10. The typical seasonal range of sur- face temperature is apparent, but the most striking feature is the marked decrease in salinitv nearshore during the fall. All properties were completely mixed vertically over Port- lock Bank. Another interesting feature is the increase in salinity that occurs in the fall at a level of about 100 m just offshore from the low-salinity water. This increase seems to be in response to the decrease in salinity and consequent increase in west- ward velocity that is needed to satisfy continuity of momen- tum and mass (Schumacher and Reed 1980; Pietrafesa and Janowitz 1979). Geopotential topographv (0/100 db) for this region dur- ing March 1978 and October 1978 is shown in Figure 3-11. In March, relief across the westward flow was only 5 dyn cm, but it increased to 20 dyn cm in October. In fall, the water moved through Kennedy Entrance (the northernmost chan- nel to Cook Inlet-Shelikof Strait) and turned south near Cape Douglas. This later flow is in agreement with flows inferred by Muench, Mofjeld, and Charnell (1978). They con- Salinit) \i Surfai I ("/<><>) 154 Salinity at 50 Mri ers ("/(») o. (W ^^j°j^, Density (Ao,) Figure 3-9. Distributions of surface salinity, salinity at 50 m. and densitv difference between 50 m and the surface during 9 to 22 October 1978. (Modified from Schumacher and Reed 1980.) eluded that Cook Inlet has an estuarine circulation with the outflow concentrated on the western side. Schumacher and Reed (1980) reported the results of data analyzed from six sections south of the Kenai Peninsula. They found that peak speeds varied from 13 to 30 cm/s dur- ing winter, spring, and summer, but during October of 1977 and 1978, they found maximum computed flows of 89 and 66 Physical Environment rEMPERA 1 1 Kl (C) N SI ITIOKS 119 128 i i i i i I I I I I 200 300 SE N 131 134 59 Til I >5.25 March Stations SE 66 68 70 73 LJ I U-J I I I I I U l_ SAUNITY (°/oo) 0- — 100- ^-Sl.73,) &2.0 i 1 32.25 4/V ,fs~r i i i i f _£ W/\£^2.75 \ ""200 March LJ I I I I I I I U L March Figure 3-10. Vertical sections of temperature, salinity, and den- sity off the Kenai Peninsula on 20 March 1978 and on 10 October 1978. (Modified from Schumacher and Reed 1980.) 133 cm/s, respectively. Volume transport varied in a similar manner from 0.1 to 1.2 x 106 m3/s. Royer (1981b) reported sim- ilar transports off Seward and a maximum computed geo- strophic speed of 66 cm/s. We (Schumacher and Reed 1980) earlier called this coastal geostrophic current the 'Kenai Current' because it is quite distinct from the Alaskan Stream. Royer (1981b), how- ever, used the term 'Alaska Coastal Current,' and we now concur with this designation because of recent evidence for its considerable westward extent. The most intense part of the flow, with its dramatic increase in speed and transport in fall, seems to form near 145°W and is most readily apparent along the Kenai Peninsula. We do not imply that a westward coastal current does not exist east of 145°W, but the avail- able data suggest that it is less developed and lacks the marked seasonal change found farther west. Royer (1979) first provided evidence of the mechanism that produces the large seasonal change in the Alaska Coastal Current. He demonstrated that changes in flow were highly correlated with freshwater discharge in the form of local precipitation and accumulated drainage from land. He also produced a hydrological model that showed maximum discharge in September or October (see also Royer 1981b and 1982). This discharge produces a marked lowering of surface salinity and a consequent increase in geopotential gradient across the flow. Although winds were not as highly correlated with flow as freshwater discharge, it is our belief that winds are impor- tant to the coastal current. This conclusion was also drawn by Royer (1983a), who suggested that the action of winds is necessary to constrain the westward flow in a narrow coastal stream. Winds near the Kenai Peninsula are from the east, except during one or two months in summer, and they pro- duce coastal convergence. On the other hand, they do not produce intense coastal convergence except in winter on the east side of the Gulf (Brower et al. 1977). This difference in winds may explain why the flow is weak and the low-salinity water is not concentrated along the coast (Ingraham 1979) on the east side of the Gulf. How far westward does the Alaska Coastal current extend? The salinity distributions in Figure 3-4 show low-salinity water on the shelf all along the Alaska Penin- OCTOBF.R Figure 3-11. Geopotential topography (AD, dyn m; 0/100 db) during 13 to 21 March 1978 and 9 to 22 October 1978. Italicized numbers denote sampling stations. (Modified from Schumacher and Reed 1980.) Physical Oceanography 67 sula to Unimak Pass. Geostrophic flow data computed from the coastal stations on these cruises also show westward flow. Schumacher, Pearson, and Overland (1982) analyzed results from both current moorings (with bottom pressure meas- urements) and hydrographic data near Unimak Pass and concluded that fluctuations in flow through the pass were largely barotropic as a result of wind-induced sea level vari- ations. Thev also concluded that there was a westward net flow as an extension of the Alaska Coastal (anient. Schumacher and Reed (in press) examined conditions along the Alaska Peninsula for evidence of continuity of this flow. Data from seven current moorings between 155 and 159°W provide evidence for westward flow. The seasonal signal of sea level at Sand Point (Shumagin Islands) is best explained by a fall increase that is highly correlated with upstream stations, and property distributions suggest west- ward baroclinic flow. A vertical section of sigma-t density normal to the Peninsula near 158°W, with profiles of the geopotential anomaly, is presented in Figure 3-12. We inter- pret the Alaska Coastal Current as being that water (with lowest density and greatest geopotential anomaly) inshore from Station 29. Westward flow continued offshore to Sta- tion 23, but there was an eastward flow of equal intensity immediately offshore. This latter feature seems likely to be a bathymetrically trapped, counter-clockwise gyre that results from vorticity constraints on motion in the trough. Lagerloef (1983) examined an apparently similar feature in a trough offshore from Kodiak Island. Density (o,) 200 Geopoten i ial Anomai ^ (dvn m) 0.30- 0 20 11/75(11) 0/125db 0 40 030 Figure 3-12. Vertical section of density and geopotential anom- aly off the Alaska Peninsula near 158°W during 28 to 29 October 1977. Direct Current Measurements Investigators have used several satellite-tracked drifters in the shelf waters to provide current estimates of shoi i duration. During September 1975 to September 197(5, nine buoys were released near 140° W and drogued at an effe< i i\ e depth of about 35 meters. These buoys generally followed the coastal current westward (Rover et al. 1979). The driftei s confirmed the general alongshore movement indicated In geostrophic flow, although drifter speeds were usually greater than those computed. This discrepancy is to be expected because of inadequate spacing of the CTD stations. Most of the buoys moved shoreward into Prince William Sound. This movement was not indicated by geopotential topography and was attributed to an entrainment process resulting from an upper layer that moved offshore while a lower layer moved onshore (Royer et al. 1979). Muench and Schumacher (1980) reported the results from six other drift- ers: two of them moved along the Kenai Peninsula into Shelikof Strait; one had little movement; two moved along the shelf southeast of Kodiak Island; and one was in the Alas- kan Stream. During the period from 1974 to 1978, moored cur- rent-meter measurements were made at 27 sites on the shelf. Measurements were also made at 12 other sites in lower Cook Inlet. In 1980, a mooring was also deployed near Unimak Pass, and an additional site was occupied off south- east Alaska near Yakutat. The results from all of these meas- urements (with durations longer than approximately 2 mo) are presented in Table 3-2; the locations are shown in Fig- ure 3-13. With one exception, the information in Table 3-2 is based on 35-h filtered data; hence the effects of tidal and inertial motion have been essentially removed. (The 2.9-h filtered variance includes the effects of tidal motion; it is apparent that it is often several times greater than the 35-h variance because of strong but variable tidal currents.) As discussed above (Table 3-1 and Fig. 3-6), measure- ments were also made at two sites in the Alaskan Stream off Kodiak Island, and an additional mooring was occupied in the edge of the Alaskan Stream off Seward (Niebauer et al. 1981). Finally, a program of long-term measurements in the coastal flow off Seward has been completed (T. C. Rover. University of Alaska, pers. comm, 1984), but results are not yet available. Our attempt to generalize the results of the current meas- urements in Table 3-2 is illustrated in Figure 3-14. This pre- sentation gives approximate net flow vectors for each site. These vectors were formed by taking vector averages of flow from all of the meters at approximately the same levels at each site and then taking a final average of results from all of the levels. No attempt was made to weight or adjust the data for their duration. Some of the data in the northeast Gulf were analyzed by Haves (1979), Hayes and Schumacher (1976), and Lagerloef. Muench, and Schumacher (1981). Net flow (Table 3-2 and Figure 3-14) was generally alongshore with speeds typically between 5 and 20 cm/s. The eddy kinetic energy (one-half the 35-h filtered variance) was relatively large, especialh in comparison with the mean kinetic energy (one-half the net 68 Physical Environment 50 60 50 170 160 150 Figure 3-13. Location of current meter moorings given in Table 3-2. 140 130 Table 3-2. Results from OCSEAP current moorings on the continental shelf in the Gulf of Alaska. Results are based on low pass (35-h) filtered records except for the 2.9-h fdtered variance. Meter Water Net Flow Variance Variance Lat. Long. Depth Depth Speed DlR. (cm2/s2) (cm2/s2) Mooring (deg- - min) (m) (m) Start End (cm/s) (deg) (35-h filter) (2.9-h filter) 60 60-05 145-41 20 100 2Jul74 3Sep74 6.1 270 124 284 50 2Jul74 29Aug74 2.7 255 18 99 90 2Jul74 4Sep74 1.4 149 14 121 60B 60-08 145-46 20 103 3Mar76 18May76 2.1 277 149 325 50 3Mar76 18May76 2.6 212 130 289 100 3Mar76 18May76 3.7 165 57 130 60C 60-08 145-49 20 100 19May76 19Aug76 0.2 91 39 181 50 19May76 19Aug76 1.8 111 27 125 90 19May76 19Aug76 2.8 107 17 86 61 59-32 145-47 20 173 16Aug74 20Nov74 28.3 257 678 1091 50 16Aug74 20Nov74 20.8 258 432 793 100 16Aug74 20Nov74 4.6 273 55 103 61B 59-34 145-53 20 203 13Mar76 19May76 18.6 250 160 500 100 13Mar76 19May76 16.8 249 122 575 61C 59-32 145-50 163 168 18May76 19Aug76 8.5 199 25 685 62A 59-34 142-10 50 188 17Aug74 40ct74 1 0.9 312 109 279 100 17Aug74 13Nov74 14.8 311 110 304 62E 59-34 142-10 24 188 20Sep75 20Nov75 19.4 308 108 357 54 20Sep75 20Nov75 16.7 310 67 274 104 20Sep75 20Nov75 13.2 310 61 263 177 20Sep75 20Nov75 5.0 334 53 177 62G 59-35 142-06 20 181 6Mar76 16May76 19.7 323 330 568 30 6Mar76 16May76 17.7 313 279 481 50 6Mar76 16May76 15.0 317 165 315 62H 59-38 142-06 20 186 15May76 21Aug76 3.4 311 117 241 50 15May76 21Aug76 4.8 316 138 243 100 15May76 21Aug76 4.3 315 68 110 173 1 5May76 21Aug76 3.6 346 27 72 62J 59-38 142-06 50 185 220ct76 16Mar77 28.6 302 326 549 100 220ct76 16Mar77 21.6 301 192 380 Physical Oceanography 69 Ml- I 1 K WA 1 1 K \i i 1 ■iou Variant i Y \KI \\( 1 Lat. Long. Depth Depth Speed DlR. (cm2/s2) dm 7s 'i Mooring (deg - • mill) (m) (m) Si AKi End (cm/s) (deg) (35-h filter) (2.9-h filter) 62K 59-38 142-06 20 188 17Mar77 8Jun77 15.4 307 305 412 50 17Mai"7 8Jun77 13.2 308 266 352 Kin 17Mar77 22Ma\77 10.4 320 1 26 189 17S 17M.1.77 8)uii77 4.9 3 1 5 58 1 10 62L 59-38 1 12-07 61 194 9Jun77 12Sq.77 10.7 296 127 22 1 1.1 9Jun77 12Sep77 7.0 293 107 183 184 9Jun77 12Sep77 3.1 321 38 79 69 59-50 145-42 20 93 3Mar76 17May76 6.6 322 127 495 69 B 59-50 145-43 20 97 18May76 19Aug76 4.8 328 66 5 Hi 50 18May76 19Aug76 3.2 30 1 18 2 1 0 87 18Ma\76 !9Aug76 1.8 271 1 1 126 SAI 58-32 1 38-22 2 1 18 25Oci80 lAprSl 8.7 66 274 391 10 25Oct80 lAprSl 5.9 78 154 238 SLSA*19 59-46 141-34 20 51 230ct76 17Mar77 29.7 289 405 906 40 23()ct76 17Mar77 18.6 288 217 426 Wl 59-47 1 11-37 45 55 18Mar77 8Jun77 8.1 293 158 269 53 18Mar77 15May77 8.1 282 114 180 SLSB*8 59-40 141-39 49 99 4Mar76 14May76 10.6 301 63 1 22 74 8Mar76 13May76 9.8 299 51 107 #14 59-40 141-40 50 100 15May76 22Sep76 5.8 299 71 175 77 15May76 24Sep76 5.4 300 50 171 #20 59-40 141-42 50 102 220ct76 17Mar77 23.5 300 174 310 W2 59-40 111 -41 58 108 18Mar77 8Jun77 16.1 300 183 267 83 18Mar77 8Jun77 12.9 297 125 208 98 18Mar77 8Jun77 10.2 291 92 171 105 18Mar77 8Jun77 7.9 283 62 120 SLSC#9 59-19 142-02 51 251 7Mar76 12May76 5.6 333 446 526 100 7Mar76 12May76 5.6 328 325 396 200 7Mar76 12May76 7.2 317 1 36 256 #21 59-20 142-07 100 251 220ct76 16Mar77 10.8 301 320 383 SLSD*16 59-59 142-19 22 52 22Aug76 6Nov76 25.6 285 619 963 42 22Aug76 15Mar77 11.5 281 150 229 SLSE*17 59-50 142-31 45 99 22Jul76 25Jan77 26.9 296 210 321 70 22Jul76 12Feb77 25.4 290 168 265 CIA 59- 1 1 153-18 20 42 60ct77 15Mar78 1 5.9 199 124 1459 34 60ct77 15Mar78 9.0 198 86 678 C1B 59- 1 1 153-19 18 40 28May78 23Aug78 9.2 202 48 1043 35 28May78 180ct78 4.3 193 35 383 C2A 59-14 153-02 20 64 60ct77 10Feb78 8.2 227 135 1 048 C2B 59-14 153-08 18 62 28May78 180ct78 14.6 218 176 1817 C3A 59-24 152-53 20 59 70ct77 15Mar78 8.3 234 48 2392 50 70ct77 15Mar78 1.7 230 26 990 C3B 59-25 152-53 25 64 28May78 180ct78 17.2 232 11 1 2942 55 28May78 2Sep78 0.6 095 24 762 C4A 59-17 152-54 20 84 70ct77 15Mar78 3.2 273 120 1865 65 70ct77 15Mar78 1.6 239 80 886 C4B 59-17 152-55 19 83 2Jun78 180ct78 3.0 246 50 1205 64 30May78 180ct78 1.3 158 71 898 C5A 59-10 152-56 20 128 70a77 15Mar78 21.0 250 296 1039 65 70ct77 15Mar78 16.3 240 185 806 C5B 59-10 152-54 27 135 31May78 20Sep78 19.1 252 433 2388 127 31May78 28Sep78 2.5 200 55 299 C6A 59-18 152-38 20 71 7C>ct77 18Mar78 2.5 275 142 2516 C6B 59-19 1 52-38 26 77 31May78 17C)ct78 0.6 256 95 2586 71 31May78 170ct78 3.2 119 31 804 C7A 59-19 152-12 65 71 80ct77 3Feb78 1.5 353 23 3650 C7B 59-19 152-11 17 68 31May78 160ct78 4.2 310 81 6430 62 31May78 160ct78 1.8 237 14 2047 C8B 59-02 152-04 63 190 29May78 140ct78 22.1 287 419 4765 64 29Mav78 19Aug78 14.2 284 108 3360 179 29Mav78 140ct78 7.8 259 33 1734 C9B 58-47 152-16 66 124 29May78 1 40ct78 10.6 300 164 3499 67 29May78 140ct78 10.4 297 166 3473 1 1 1 29Mav78 140ct78 11.4 300 91 1 369 C10A 58-30 1 53- 1 1 20 170 50ct77 13Mar78 27.8 230 573 799 65 50ct77 13Mar78 23.4 229 368 490 CI OB 58-30 153-12 25 175 28Ma\78 90ct78 14.4 222 222 366 70 28May78 90ct78 12.0 221 185 255 165 28Ma\78 90ct78 4.3 200 117 166 70 Physical Environmlnt Ml- 1 ER W.\ 1 1 R Net I 'low Variam 1 Variance 1.A1. Long. Depth Dhl" 1 H Speed Dir. (cm2/s2) (cm'-/s-) Mooring (deg nun) (m) (111) Start End (cm/s) (deg) (35-h filter) (2.9-h filler) C.12A 59-32 152-14 20 50 28May78 17Aug78 3.8 42 10 3865 46 28May78 160ct78 4.0 30 10 2393 C13A 59-28 152-41 26 68 28May78 160ct78 5.2 189 75 4108 K1A 57-45 154-44 100 228 160ct76 30Mar77 26.7 237 339 585 K2A 58-37 153-05 20 164 160ct76 31Mar77 42.5 214 535 951 100 160ct76 31Mar77 26.7 228 281 470 K5A 56-33 152-40 20 95 180ct76 25Mar77 15.0 192 175 789 80 180ct76 25Mar77 13.5 184 95 292 K6A 57-13 1 52-26 23 75 190ct77 9Mar78 21.5 283 274 799 65 190ct77 9Mar78 14.5 272 112 324 K6B 57-14 1 52-23 32 82 21May78 50ct78 15.6 278 60 399 72 21May78 50ct78 8.3 263 18 188 K7A 57-04 152-18 28 80 190ct77 10Mar78 10.6 337 155 670 70 190ct77 10Mar78 7.7 326 54 259 K7B 57-05 152-13 29 84 21May78 30ct78 9.0 319 48 380 K.8A 57-07 152-45 25 150 190ct77 9Mar78 25.1 202 228 422 K8B 57-05 152-43 30 155 21May78 30ct78 17.9 216 60 156 75 21May78 30ct78 10.7 220 32 115 K9A 57-01 152-37 25 158 190ct77 9Mar78 2.8 300 170 436 K9B 56-59 152-34 13 146 21May78 50ct78 5.0 222 107 424 58 21May78 50ct78 4.4 260 94 356 142 21May78 50ct78 3.8 293 15 77 K10A 56-51 152-26 144 154 190ct77 9Mar78 5.6 332 60 148 K10B 56-50 152-23 24 153 21May78 40ct78 4.7 291 44 198 69 21May78 40ct78 5.8 307 48 207 149 21May78 40ct78 6.3 339 18 85 K11B 56-02 155-06 25 60 22May78 28Jul78 10.1 224 46 3179 K12A 55-59 156-18 18 213 240ct77 8Mar78 24.6 203 797 1862 205 240ct77 8Mar78 6.9 182 233 563 K13B 56-24 156-49 28 115 22May78 70ct78 13.9 220 152 666 111 22May78 70ct78 2.7 202 35 191 MIA 55-47 158-39 51 71 280ct77 7Mar78 16.1 219 151 343 MIB 55-25 157-59 90 110 280ct77 6Mar78 7.3 29 105 333 MID 55-46 157-31 70 118 280ct77 6Mar78 10.6 324 93 428 WGC-1A 54-02 163-00 20 188 5Sep75 lNov75 27.2 264 320 732 103 5Sep75 1Nov75 14.9 257 106 268 WGC-1B 54-01 163-00 20 194 2Nov75 12Mar76 12.2 243 236 340 100 2Nov75 30Dec75 21.5 263 465 671 WGC-1C 54-01 163-00 20 186 13Mar76 HJun76 25.1 254 206 564 50 13Mar76 1 ljun76 24.4 254 158 445 100 13Mar76 1 ljun76 19.1 243 113 278 175 13Mar76 1 ljun76 7.7 225 60 123 WGC-1D 54-01 163-06 20 89 12Jun76 90ct76 11.2 253 103 446 50 12Jun76 90ct76 10.3 255 69 361 WGC-1E 54-03 163-06 18 88 10ct76 29Apr77 23.6 258 431 1203 78 10ct76 18Dec76 12.2 250 98 290 WGC-1F 54-04 163-06 20 88 30Apr77 8Sep77 16.2 262 110 511 76 29Api77 7Sep77 7.1 249 35 143 WGC-2A 57-27 150-29 20 185 22Sep75 17Nov75 33.5 226 120 1027 100 22Sep75 17Nov75 25.7 224 51 353 WGC-2C 57-27 150-29 24 185 10Mar76 8Jun76 21.8 227 194 586 54 10Mar76 8Jun76 24.1 232 152 457 104 10Mar76 10May76 24.8 235 77 390 179 10Mar76 8Jun76 13.0 182 114 661 WGC-2D 57-34 150-49 20 92 8Jun76 180ct76 3.2 245 32 1320 50 8Jun76 180ct76 3.7 235 18 1133 WGC-2E 57-34 150-49 20 90 190ct76 24Mar77 2.3 241 138 1857 VVGC-2F 57-34 150-50 20 90 25Mar77 8Sep77 4.7 221 45 1350 80 25Mar77 8Sep77 2.8 179 12 510 VVGC-3B 55-11 156-58 20 111 10Jun76 17C)ct76 21.4 256 170 1816 VVGC-3C 55-12 156-57 28 112 180ct76 6Mar77 26.1 229 661 1289 90 180ct76 21Mar77 19.8 232 171 1052 WGC-3D 55-12 156-58 20 112 10Jul77 18Nov77 24.1 255 168 1664 UP3 54-10 164-00 47 67 22Mar80 15Aug80 2.0 229 78 262 Physical Oceanography 71 50 Current speed 50 170 160 130 Figure 3-14. Approximate net current speeds and directions derived from the current data in Table 3-2. speed squared). There was a tendency for flow in the same direction throughout the water column; often the speeds did not decrease in the vertical until quite near the bottom. Net flow tends to be considerably greater in winter than summer as discussed by Lagerloef et al. (1981). These various characteristics suggest flow that is significantly affected by eddies (also noted by Rover 1983a) and has large effects from local wind forcing. There may be an appreciable compo- nent of barotropic flow, especially during the strong winter winds, as suggested by Lagerloef^ al. (1981) and Reed and Schumacher (1981). Results from moorings in the western Gulf (K1-K13, MI numbers, and WGC-1, 2, and 3 on Fig. 3-13) are somewhat unsatisfactory in that none of them sampled the nearshore Alaska Coastal Current before that flow moved into Ken- nedy Entrance and Shelikof Strait. The results are interest- ing, however, and reveal at least two subtle differences from results obtained in the northeast Gulf. First, the eddv-energy level seems to be generally lower than that to the east. Second, the open-shelf moorings appear to have net flows that, although also alongshore, decrease more rapidly in the vertical than those to the east. These features suggest rather stable flow that is not strongly affected by local winds. However, the possibility of remote wind forc- ing, which alters large-scale pressure gradients and flow (as discussed by Battisti and Hickey 1984), cannot be ruled out. Moorings K5-10 were located in the vicinity of Kiliuda Trough off Kodiak Island; the results reveal a bathymetrically trapped eddy (Lagerloef 1983). Data from the MI moorings seem to reflect a similar feature. The exis- tence of numerous deep troughs in the western Gulf may produce complexities in the flow field at several sites. We have not attempted to analyze the results from the moorings in detail here, but the data are listed for possible use by others. Sea Level Adjusting sea level variations for the static effects of atmospheric pressure changes results in a variable that reflects the density of nearby waters. Favorite et al. (1976) and Ingraham et al. (1976) provided information on sea level in the Gulf of Alaska, and Reid and Mantyla (1976) used data at Yakutat to infer aspects of subarctic circulation. Reed and Schumacher (1981) examined spatial differences in the sea- sonal cycles of sea level around the Gulf and interpreted the features in terms of coastal currents. Enfield and Allen (1980) and Chelton and Davis (1982) analyzed interannual variations in the Pacific, including some stations in the Gulf of Alaska. They, along with Cannon, Reed, and Pullen (1985), detected changes in west coast and Alaskan sea level that appear to be linked to El Nino events. Reed and Schumacher (1981) examined the seasonal cycles of adjusted sea level at Sitka, Yakutat, Seward, Sel- dovia, Kodiak, and Dutch Harbor (Table 3-3). Annual max- imum sea levels at Seward and Seldovia approximately coin- cide with seasonal minimum salinities (densities) as well as maximum flows of the Alaska Coastal Current. Both stations are just inshore of this flow and should be affected b\ it. Sitka and Yakutat, however, have maxima later in the year, near the time when coastallv convergent winds are at their maximum. Kodiak and Dutch Harbor are not located in the path of the Alaska Coastal Current, so neither their phase nor their small range reflects its effect. A correlation analv- 72 Physical Environment Table 3-3. Summary of features in the adjusted mean monthly sea-level deviations from the annual means (from Reed and Schumacher 1981). Locai ION Time of Time of Ann UAL Range of Minimum Maximum De\ iaitons (cm) Sitka June December 14 Vakutat April November 14 Seward April October 14 Seldovia April September 13 Kodiak March December 9 Dutch Harbor April December 8 sis showed that the pairs Sitka-Yakutat, Seward-Seldovia, and Kodiak-Dutch Harbor were highly correlated with each other, but not with other stations. A long series of monthly anomalies (from the long-term means) of adjusted sea level are shown in Figure 3-15 for sta- tions off our west coast from southern California to the head of the Gulf of Alaska. This figure resulted from an examina- tion of the effects of El Nino events at high latitudes. The large events of 1941, 1958, and 1982-83 are readily apparent in the spatially coherent, rapid rises of sea level. The last two events produced large changes in Alaskan waters. Royer and Xiong (1984) also reported positive temperature anomalies of approximately 2C off Seward in early 1983 and also in early 1977. Not all large changes in sea level are related to El Nino events, however. Numerous anomalies, often spatially incoherent, are also apparent in Figure 3-15. Regardless of their cause, large interannual, as well as seasonal, changes do occur in the Gulf of Alaska. -20 Crescent City, CA . M|U| A M\ Ah. Jd JNMA. It J «!.. /Uifr JL(\Jlb Al it L k J (fm fwfN jY 1920 1930 1940 1950 1960 1970 1980 Figure 3-15. Monthly anomalies of sea level from California to the Gulf of Alaska. The data were adjusted for variations in atmo- spheric pressure, and the time series were detrended. Shading indicates sites having El Nino events in 1941,1958, and 1982-83. (Modi- fied from Cannon el al. 1985.) Physical Ocfanography 73 Some Implications The Alaska Coastal (anient is a permanent system oi coastal flow lh.it exists from southeast Alaska around the Gulf to L'nimak Pass. The largest seasonal changes and high est velocities, however, occur in the northern Gulf near the Kenai Peninsula. It would seem that such a feature would have an effect on water exchange in the inshore estuaries and fjords. Although this appears to be the case, the details have not been well documented. Rover (1983a) suggested that the absence of strong winds in summer in the northern Gulf eliminates downwelling of near-surface waters and permits the relatively warm and salty offshore waters to move inshore. Such movement into Prince William Sound was observed by drifters (Rover et al. 1979). Surface waters tend to move seaward, but are apparently constrained by winds, except in the Kayak eddy where they move well offshore. Coastal winds around the Cult of Alaska vary greatly with time, of course, but also have considerably different sea- sonal cycles in different regions. In the northern Gulf of Alaska, the winds produce near-shore downwelling. Upwelling occurs only for two to three months in summer when winds are very weak (Royer 1983b; Schumacher and Reed, in press). West of Kodiak Island, however, wind stress is generallv in the proper direction to produce upwelling (Schumacher and Reed, in press). Monthly mean speeds (and stress) are small, however, which supports the lack of observational evidence for upwelling in the western Gulf. The Alaska Coastal Current shows both very large sea- sonal changes in salinity and very high velocities at times. It is primarily these two features that make it an atypical conti- nental shelf current. Does it have an analogue elsewhere? Rover (1983b) suggested that the Norwegian Coastal Current has strong similarities to the system in the Gulf of Alaska. Large amounts of freshwater discharge and high velocities occur off Norway, but the coastal current there has flow reversals and seems to be strongly affected by wavelike eddy- motions (McClimans and Nilsen 1983). Further comparisons of these systems might provide additional insight into the dynamics of coastal flow in the Gulf of Alaska. Acknowledgments We thank the many researchers whose efforts and analy- ses were vital to this study. Many people also contributed to the field work, data processing, and the preparation of reports. The crews of the vessels engaged in this work were both helpful and enthusiastic. We also acknowledge the many stimulating conversations we had with T. C. Royer. Funding for this report was provided by the Minerals Man- agement Service, Department of the Interior, through an interagency agreement with the National Oceanic and Atmospheric Administration, Department of Commerce, as part of the Outer Continental Shelf Environmental Assess- ment Program. This is contribution no. 737 from the Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Seattle, Washington. References Battisti, D.S. and B.M. Hickey 1984 Application of remote wind-forced coastal trapped wave theory to the Oregon and Wash- ington coasts. Journal of Physical Oceanography 14:887-903. Bogdanov, K.T. 1961 Tsirkulyatsiya vod v zalive Alyaska i ee sezon- naya izmenchivost [Water circulation in the Gulf of Alaska and its seasonal variability]. Okeanologiya 1:815-824. Brower, W.A., Jr., H.F. Diaz, A.S. Prechtel, H.W. Searby, and J.L. Wise 1977 Climatic Atlas of the Outer Continental Shelf Waters and Coastal Regions of Alaska, Vol. 1: Gulf of Alaska. Arctic Environmental Information and Data Center, University of Alaska, Anchorage, AK. 439 pp. Cannon, G.A., R.K. Reed, and P.E. Pullen 1985 Comparison of El Nino events off the Pacific Northwest. In: El Nino North: Nino Effects in the Eastern Subarctic Pacific Ocean. W.S. Wooster and D.L. Fluharty, editors. Washington Sea Grant Publication WO 85-3, University of Wash- ington, Seattle, WA. pp. 75-84. Chelton, D.B. and R.E. Davis 1982 Monthly mean sea-level variability along the west coast of North America. Journal of Physical Oceanography 12:757-784. Dodimead, A.J., F. Favorite, and T. Hirano 1963 Salmon of the North Pacific Ocean, part II, review of oceanography of the subarctic Pacific region. International North Pacific Fisheries Commission Bulletin No. 13. 195 pp. Emery, W.J. andJ.S. Dewar 1982 Mean temperature-salinity, salinitv-depth and temperature-depth curves for the North Atlan- tic and North Pacific. Progress in Oceanography 11:219-305. Enfield, D.B. andJ.S. Allen 1980 On the structure and dynamics of monthly mean sea level anomalies along the Pacific coast of North and South America. Journal of Physical Oceanography 10:557-578. Favorite, F. 1967 The Alaskan stream. International North Pacific Fisheries Commission Bulletin No. 21. pp. 1-20. Favorite, F., A.J. Dodimead, and K. Nasu 1976 Oceanography of the subarctic Pacific region. 1960- 71. International North Pacific Fisheries Commission Bulletin No. 33. 187 pp. 74 Physical Environmint Fofonoff, N.P. and S. Tabata 1966 Variability of oceanographic conditions between Ocean Station P and Swiftsure Bank off tbe Pacific coast of Canada. Journal of the Fisheries Research Board of Canada 23:825-868. Goodman, J. R. and T.G. Thompson 1940 Characteristics of waters in sections from Dutch Harbor, Alaska to the Strait of Juan de Fuca and from the Strait of Juan de Fuca to Hawaii. University of Washington Publications in Oceanography 3:81- 103. Hayes, S.P. 1979 Variability of current and bottom pressure across the continental shelf in the northeast Gulf of Alaska. Journal of Physical Oceanography 9:88-103. Hayes, S.P. andJ.D. Schumacher 1976 Description of wind, current, and bottom pres- sure variations on the continental shelf in the northeast Gulf of Alaska from February to May 1975. Journal of Geophysical Research 81:6411-6419. Hicks, S.D., H.A. Debaugh, Jr., and L.E. Hickman, Jr. 1983 Sea level variations for the United States, 1855- 1980. U.S. Department of Commerce, NOAA, National Ocean Service, Rockville, MD. 170 pp. Ingraham, W.J., Jr. 1979 The anomalous surface salinity minima area across the northern Gulf of Alaska and its rela- tion to fisheries. Marine Fisheries Review 41(5-6):8-19. Ingraham, W.J., Jr., A. Bakun, and F. Favorite 1976 Physical oceanography of the Gulf of Alaska, final report. Research Unit 357. Environmental Assessment of the Alaskan Continental Shelf, Quar- terly Reports of Principal Investigators July- September 3:845-978. Lagerloef, G. 1983 Topographically controlled flow around a deep trough transecting the shelf off Kodiak Island, Alaska. Journal of Physical Oceanography 13:139-146. Lagerloef, G.S.E., R.D. Muench, andJ.D. Schumacher 1981 Low-frequency variations in currents near the shelf break: northeast Gulf of A\aska Journal of Physical Oceanography 11:627-638. Levitus, S. 1982 Climatological atlas of the world ocean. Geo- physical Fluid Dynamics Laboratory, NOAA. NOAA Professional Paper 13. 173 pp. McClimans, T.A. andJ.H. Nilsen 1983 Whirls in the Norwegian Coastal Current. In: Coastal Oceanography. H.G. Gade, A. Edwards, and H. Svendsen, editors. Plenum Press, New York, NY. pp. 311-320. McEwen, G.F., T.G. Thompson, and R. Van Cleve 1930 Hvdrographic sections and calculated currents in the Gulf of Alaska, 1927 and 1928. Report of the International Fisheries Commission 4:5-36. Muench, R.D. andJ.D. Schumacher 1980 Physical oceanographic and meteorological conditions in the northwest Gulf of Alaska. NOAA Technical Memorandum ERL/PMEL- 22. 147 pp. Muench, R.D., H.O. Mofjeld, and R.L. Charnell 1978 Oceanographic conditions in lower Cook Inlet: spring and summer 1973. Journal of Geo- physical Research 83C:5090-5098. Niebauer, H.J., J. Roberts, and T.C. Royer 1981 Shelf break circulation in the northern Gulf of Alaska. Journal of Geophysical Research 86C4231-4242. Pietrafesa, L.J. and G.S. Janowitz 1979 On the effects of buoyancy flux on continental shelf circulation.yo;/r»«/ of Physical Oceanography 9:911-918. Reed, R.K. 1980a Recent observations of a large eddy in the Gulf of Alaska. Marine Fisheries Review 42(6):29-31. Reed, R.K. 1980b Direct measurement of recirculation in the Alaskan Stream. Journal of Physical Oceanography 10:976-978. Reed, R.K. 1984 Flow of the Alaskan Stream and its variations. Deep-Sea Research 31:369-386. Reed, R.K. andJ.D. Schumacher 1981 Sea level variations in relation to coastal flow around the Gulf of Alaska.yoMraa/ of Geophysical Research 86G6543-6546. Reed, R.K. andJ.D. Schumacher 1984 Additional current measurements in the Alas- kan Stream near Kodiak Island./oimw?/ of Phys- ical Oceanography 14:1239-1246. Reed, R.K. and N.E. Taylor 1965 Some measurements of the Alaska Stream with parachute drogues. Deep-Sea Research 12:777-784. Physical Oceanography 75 Reed, R.K., R.D. Muench, and J.D. Schumacher 1980 On haroclinic transport of the Alaskan Stream near Kodiak Island. Deep-Sea Research 27:509-52:5. Reed, R.K., J.D. Schumacher, andJ.P. Blaha 1981 Eulerian measurements in the Alaskan Stream near Kodiak Island. Journal of Physical Oceanogra- phy 11:1591-1595. Reed, R.K., J.D. Schumacher, and C. Wright 1981 On coastal flow in the northeast Gulf of Alaska near Yakutat. Atmosphere-Ocean 19:47-53. Reid, J.L. and A.W. Mantyla 1976 The effect of the geostrophic flow upon coastal sea elevations in the northern North Pacific Ocean. Journal of Geophysical Research 81:3100- 3110. Robinson, M.K. 1957 Sea temperature in the Gulf of Alaska and in the northeast Pacific Ocean, 1941-1952. Bulletin of the Scripps Institution of Oceanography 7:1-98. Roden, G.I. 1969 Winter circulation in the Gulf of Alaska Journal of Geophysical Research 74:4523-4534. Rover, T.C. 1979 On the effect of precipitation and runoff on coastal circulation in the Gulf of Alaska./owrafl/ of Physical Oceanography 9:555-563. Rover, T.C. 1981a Baroclinic transport in the Gulf of Alaska. Part I. Seasonal variations of the Alaska Current. Journal of Marine Research 39:239-250. Rover, T.C. 1981b Baroclinic transport in the Gulf of Alaska. Part II. A fresh water driven coastal curr em. Journal of Marine Research 39:251-266. Rover, T.C. 1982 Coastal fresh water discharge in the northeast Pacific. Journal of Geophysical Research 87G2017-2021. Royer, T.C. 1983a Northern Gulf of Alaska. Review of Geophysics and Space Physics 21:1153-1155. Rover, T.C. 1983b Royer, T.C. and Q. Xiong 1984 A possible warming in the Gulf of Alaska due to the 1982-83 El Nino Southern Oscillation. Tropical Ocean-Atmosphere Newsletter 24:4-5. Royer, T.C, DA'. Hansen, and D.J. Pashinski 1979 Coastal flow in the northern Gulf ol Alaska as observed by dynamic topographv and satel- lite-tracked drogued drift buoys. Journal of Phys- ical Oceanography 9:785-801. Schumacher, J.D. and R.K.. Reed 1980 Coastal flow in the northwest Gulf of Alaska: the Kenai Current. Journal of Geophysical Research 85:6680-6688. Schumacher, J.D. and R.K. Reed 1986 On the Alaska Coastal Current in the western Gulf of Maska.Journal of Geophysical Research (in press). Schumacher, J. D., C.A. Pearson, andJ.E. Overland 1982 On the exchange of water between the Gulf of Alaska and the Bering Sea through Unimak Pass. Journal of Geophysical Research 87C:5785-5795. Sverdrup, H.U., M.W.Johnson, and R.H. Fleming 1942 The Oceans: Their Physics, Chemistry and General Biology. Prentice-Hall, New York, NY. 1087 pp. Tabata, S. 1961 Temporal changes of salinity, temperature, and dissolved oxygen content of the water at station "P" in the northeast Pacific Ocean, and some of their determining factors. Journal of the Fisheries Research Board of Canada 18:1073-1124. Tabata, S. 1982 The antic) clonic, baroclinic eddy off Sitka, Alaska, in the northeast Pacific Ocean. Journal of Physical Oceanography 12:1260-1282. Uda, M. 1963 Oceanography of the subarctic Pacific Ocean. Journal of the Fisheries Research Board of Canada 20:119-179. Wright, C. 1981 Observations in the Alaskan Stream during 1980. NOAA Technical Memorandum ERL/ PMEL-23. 34 pp. Observations of the Alaska Coastal Current. In: Coastal Oceanography. H.G. Gade, A. Edwards, and H. Svendsen, editors. Plenum Press, New York, NY. pp. 9-30. Chemical Distributions and Signals in the Gulf of Alaska, its Coastal Margins and Estuaries William S. Reeburgh George W. Kipphut Institute of Marine Science University of Alaska Fairbanks, Alaska Abstract This chapter combines the limited chemical data for the Gulf of Alaska, its coastal margins, and its estuaries with recent physical oceanographic studies to determine how these distinct domains interact. We suggest how the interactions may be detected and quantified chemically. A basic understanding exists for the circulation and inter- action of all domains. An improved understanding of these interactions and their importance will result if future chemical studies are: 1) closely integrated with physical oceanographic measurements of transport and circulation, and 2) careful to involve measurements of radioactive and transient tracers. Introduction A surprisingly small amount of chemical work has been clone on the deep Gulf of Alaska. The most extensive chem- ical data sets exist for coastal fjords and estuaries adjacent to the shelf, and the fewest chemical data are available for the continental shelf of the Gulf of Alaska. This chapter synthe- sizes chemical oceanographic studies in the Gulf of Alaska bv treating the deep sea, the shelf, and the fjords and estu- aries as distinct oceanographic domains. In the chapter, we consider circulation, chemical distributions, and variability in each domain. We also consider how each of these domains interacts physically with adjacent domains and how the interactions may be detected and quantified chem- ically. This approach summarizes what is known about chemical processes in the Gulf of Alaska and, at the same time, points the way to future work. We will rely heavily on physical oceanographic studies that shed light on how these domains circulate and interact since there are few chemical data for the Gulf of Alaska, its continental shelf, and coastal inlets. This chapter contains little new data, and includes data from studies performed prior to the introduction of reliable analytical methods for nutrients, trace metals, dissolved gases and radioisotopes. Note that it is necessary to depart from the geographic con- straints of this volume (i.e., north of 52°X and east of Great Sitkin Island, 176°W) in order to make use of the valuable time-series data collected at Ocean Station 'P'. Deep Waters The locations of the chemical data used in this chapter are shown in Figure 4-1; the types of data are listed in Table 4-1. Some of the earliest chemical data for the Gulf of Alaska region were collected during 1933-1934 (Barnes and Thompson 1938). There have been two major field efforts in the Gulf of Alaska, separated by some 20 years, whose results can be used to produce sections of large-scale chemical dis- tributions (NORPAC 1960, 1965; Reid 1973; and Cline, Feelv. Kelly-Hansen, Gendron, Wisegarver, and Chen 1985). Many of the earlier data (collected before the development of con- tinuous CTD profilers) were collected at 'standard' depths and did not sample either the oxygen minimum or the deeper waters with good resolution. Reid (1973), using prin- cipally the NORPAC data, presented chemical sections of the western Gulf of Alaska as part of a larger effort aimed at determining the source of Pacific Intermediate Water. The GEOSECS program performed comprehensive chemical measurements in the Atlantic and Pacific oceans; part of this data set (Broecker, Spencer, and Craig 1982; Craig, Broecker, and Spencer 1981) includes a 1973 section along the far-western edge of the Gulf of Alaska (176° W). This sec- tion contains the most comprehensive chemical data avail- able for this area. The chemical and current measurements of Warren and Owens (1985), taken some 100 km east of the GEOSECS section, are an important complement to the GEOSECS data. Station P (50°00'N, 145°00'W) has been 77 78 Physical Environmeni 60 120 170 160 150 140 Figure 4-1. Location of oceanographic sampling stations and sections in the Gulf of Alaska. occupied for more than 25 years, beginning in 1950, and provides the only data set that allows consideration of annual and longer-term variability in the deep Gulf of Alaska. Published data for Station P consists mainly of T, S, and oxygen depth distributions (Tabata 1981). Other chem- ical data have been collected, but are not yet available for distribution (C.S. Wong, Sidney, B.C., pers. comm., 1984). Deep waters are not formed in the North Pacific (Reid 1965, 1973; Warren 1983) because low salinity in the near- surface water reduces its density and prevents it from sink- ing to great depth. However, Pacific Intermediate Water is formed during winter convection (Reid 1973). It occurs in N-S sections of the Pacific Ocean as a low-temperature, low-salinity tongue centered at depths of 300 to 600 m at middle and low latitudes. The processes governing the pres- ence of this low-salinity surface water are not completely clear. For example, Warren (1983) emphasizes processes that result in a low regional evaporation rate, while Royer (1979, 1982) presents a case for high terrestrial runoff. Depth distributions from a station located in the approxi- mate center of the Gulf of Alaska (ENP-2, Cline et al. 1985) are presented in Figure 4-2. Distinctive chemical features of the deep Gulf of Alaska include some of the highest oceanic silicate, phosphate, and nitrate concentrations, as well as the best-developed oxygen minimum to be found in the world ocean. While the depth of the oxygen minimum varies somewhat with location (doming in the central Gulf), it occurs consistently at sigma-t values between 27.3 and 27.4. The oxygen and phosphate distributions result from the decomposition of particulate organic matter that sinks from surface ocean waters. While this is also the case elsewhere, concentrations of oxygen and phosphate in the Gulf of Alaska differ substantially from concentrations in other ocean waters at similar latitudes. The oxygen minimum is well developed in the Gulf of Alaska — not because of higher surface water productivity Table 4-1. Gulf of Alaska Data Sources. Reference Notes Barnes and Thompson (1938) NORPAC(1960) NORPAC(1965) Reid (1965) Dodimeadrfa/. (1962) Kort(1966) Hokkaido University (1957-1984) Anderson et al. (1977) Broeckerrfa/. (1982) Craig et al. (1981) Feely and Chen (1982) Chen (1982) Warren and Owens ( 1 985) Cline et al. (1985) Some of the earliest data for the Gulf of Alaska. Mostly surface T, S, P04, andSi(OH)4. Compilation of data collected in the North Pacific prior to 1955, mostly T, S, and 02. Data collected in the North Pacific during 1959, mostly T, S, and Oa. Synthesis of NORPAC (1960, 1965) data plus additional data. Contains chemical sections of Gulf of Alaska. Extensive T, S, and 02 data for the Gulf of Alaska collected during summer 1962. Extensive T, S, Oa, nutrient, organic carbon, fallout isotope, and trace metal data for the entire Pacific Ocean. Few Gulf of Alaska data. T, S, Oa, N03, P04, and Si(OH)4, at many locations in the Gulf of Alaska, usually to maximum of 1,500 meters. Long-term averages of nutrients and chlorophyll for many locations in the Gulf of Alaska. GEOSECS Hydrographic Report GEOSECS Atlas Total C02 and alkalinity sections along 150° W longitude. T, S, 02, NO.,, P04, Si(OH).,, and currents along 175° W longitude. T, S, O.,, NO,, PO„ Si(OH).,, alkalinity, total C02, Freon-1 1, and Freon-12 in western (~ 170° E), central (170° W) and eastern (150° W) North Pacific sections. Chemical Distributions 79 DlSOl VED OXYCI N ((iMOg/kg) 0 100 200 300 Phospha 1 1 (HM HsPO«-P/kg) 0 12 3 Nl I R \ I I (HM NOs~-N/kg) 10 20 30 40 30 31 32 33 34 Salinity (°/oo) 35 0 100 200 300 Silicate (liM Si(OH)4-Si/kg) Figure 4-2. Chemical profiles for the central Gulf of Alaska, Station ENP-2 (15 June 1981; 54° 20'N, 151° 15'W). (Modified from Cline el al. 1985.) (Sambrotto and Lorenzen, Ch. 9, this volume) — but because the deep waters circulate poorly, and because they carry the accumulated products of decomposed organic matter from the deep waters of other ocean areas (Broecker and Peng 1982). The abyssal waters of the northeast Pacific share several characteristics: • they are the farthest from areas of bottom water for- mation and ventilation • they are very uniform in their major properties • they are the oldest abyssal waters in the world ocean (Mantyla and Reid 1983) Abyssal waters enter the Gulf of Alaska from three possible directions: 1) from the west along the Aleutian Trench (War- ren and Owens 1985); 2) from the southwest through the Emperor Seamount Chain; and 3) from southeast of the Hawaiian Islands (Mantyla and Reid 1983). Pytkowicz and Kester (1966) have analyzed the extensive NORPAC oxygen and phosphate data to determine both the sources and the flow direction for the intermediate and deep waters of the northeast Pacific, including the Gulf of Alaska. They calculated horizontal gradients of apparent oxygen utilization (AOU) (Redfield, Ketchum, and Richards 1963) in order to determine directions for intermediate water motion east of 150° W. They also used horizontal gra- dients of phosphate in a similar manner. Their results indi- cate that water moves into the Gulf from the south and southwest at a depth of 1,000 m, and moves out of the Gulf to the south at depths of 1,500 and 2,000 meters. Reid and Man- tyla (1978) considered the entire North Pacific and used maps of geopotential anomaly at 1,000 db to show anti- cyclonic circulation. The recent direct current observations of Warren and Owens (1985) at 175° W show a zonal eastward flow into the Gulf with a westward flow adjacent to the Aleutian Islands. The Pytkowicz and Kester study and the Warren and Owens study cover widely separated parts of the Gulf of Alaska, and both appear to be in general agreement. However, they key- note the need for more direct current measurements in deep and intermediate waters. The movement of abyssal water into the Northeast Pacific Ocean and the Gulf of Alaska requires both upwell- ing and a compensating surface flow of water in the reverse direction along the coastal margin. Evidence of upwelling is provided by the doming of the oxygen minimum (Reid 1965), whereas the compensating surface flow is represented by the Alaskan Stream. Results of measurements at GEOSECS Station 218 (part of a section along the western edge of the Gulf of Alaska) are presented in Figure 4-3. This station includes many of the same parameters shown in Figure 4-2, but also includes car- bon isotope data. This station shows a very intense oxygen minimum/nutrient maximum at about 1,000 m (sigma-t = 27.4). Both the current meter measurements and the oxygen and silicate data from the Warren and Owens (1985) stud) indicate that water is moving into the Gulf of Alaska (50° N) at velocities between 1 and 3 cm/s at all depths. This means 80 Physicai Environment Temperature (C) 0 2 4 6 8 Disoi \n> Oxygen (HM (>„/kg) 0 100 200 300 Phosphate (liM H3P04-P/kg) 12 3 4 G5 32 33 34 35 Salinity (°/oo) AMC (°/oo) ■ 200 - 100 0 -100 Alkalinity (mEQ/kg) 2.2 2.3 2.4 2.5 NO., Alk /IC02 100 200 300 Silicate (liM Si(OH)4-Si/kg) 15 25 35 Nitrate (LiMNCV-N/kg) -1 o +1 8UC (°/oo) 2.1 2.2 2.3 2.4 Total Carbon Dioxide (mM IC02-C/kg) Figure 4-3. Chemical profiles at GEOSECS Station 218. Data are from Broecker, Spencer, and Craig (1981); Ostlund and Stuiver (1980); and Kroopnick (1985). that the western boundary must be a source of low-oxygen, high-nutrient waters that are characteristic of depths greater than 500 m in the Gulf of Alaska. The measurements of Warren and Owens (1985) also confirm the presence of a narrow, westward-flowing surface current along the south slope of the Aleutian Islands that carries high-oxygen, low-silica water out of the Gulf. Fluxes across the southern boundary of the Gulf of Alaska cannot be constrained as well as those on the western boundary, but questions about long-term variability in the Gulf can be addressed using the Station P data. Studies of nutrients (Anderson, Lam, Booth, and Glass 1977), primary productivity (McAllister, Parsons, and Strickland 1960), and 222Rn (Peng, Takahashi, and Broecker 1974) have been per- formed at this station. Anderson et al. (1977) measured annual variations in nitrate and showed that surface nitrate was never less than 10 p.M, even during peak uptake. Other observations of surface waters (Hokkaido Univer- sity 1981) confirm the fact that measurable nitrate is always present, and indicate that nitrate probably does not limit surface productivity. A well-established population of pel- agic grazers appears to be responsible for the relatively high surface-nutrient concentrations (Miller, Frost, Batchelder, demons, and Conway 1984). An analysis of nearly 25 years of T, S, and oxygen data from Station P (Tabata 1981) showed that surface tem- peratures varied annually from 5 to 12C, and that salinity varied between 32.65 and 32.85°/oo, although there are instances of brief incursions of higher-salinity water. These analyses extend to approximately 1,000 m, and the sigma-t surface associated with the oxygen minimum frequently moves between depths of 900 and 1,000 m (Fig. 4-4). As expected, variations in T, S, and oxygen are much smaller at depth than at the surface, but several long- and short-term trends are evident. Three trends in the oxygen data were identified by Tabata: 1) above average values dur- ing 1958 to 1964, 2) below average values during 1968 to 1970, and 3) a subsequent return to normal values. The oxygen changes did not correlate well with temperature, and Tabata suggested that periods of below-average oxygen were related to the intrusion of oxygen-deficient water that formed along the Pacific coast of North America. If Tabata's assumption is confirmed, it could be evidence for a link between deep-water and coastal-water processes. 100 |iM02 200 300 E Sea Floor Figure 4-4. Dissolved oxygen profile at Station P (April 1978; 50° N, 145° W). Institute of Ocean Sciences (1978) data. Chemical Distributions 81 Distributions of natural and fallout radioisotopes can be used to estimate process rates, but there are only a few meas- urements of radioactive species in the Gulf of Alaska. Silker (1972) reported surface concentrations and a few vertical profiles of the fallout isotopes ""Sr, "'/a, "r,Nb, l06Ru, ' ' 'Ce, and the natural cosmogenic isotope "Be for the North Pacific Ocean, but only a few of these measurements were made north of 50°N. Silker used 7Be profiles to estimate ver- tical vdd\ diffusivities of 0.5 to 0.7 cm-Is. Michel and Suess (1975) determined tritium in surface water for a number of locations in the North Pacific during the 1970s, but none of their stations were located in the Gulf of Alaska. Fine and Ostlund (1977) and Fine, Reid, and Ostlund (1981) reported tritium data for approximately the same area. Both studies inferred that tritium concentrations in surface waters of the Gulf of Alaska should be among the highest in the world ocean. Radiocarbon was measured (M. Stuiver and P. Quay, Uni- versity of Washington, pers. comm., 1984) in surface samples collected during a transit between Dutch Harbor and Seattle in June 1982; the results are shown in Figure 4-5. In the absence of modern or fossil carbon inputs, A14C values reflect radioactive decay and are useful in determining rela- tive ages of water masses. The radiocarbon data of Stuiver and Quav clearly suggest the influence of older, deeper water on surface waters in the Gulf of Alaska central gyre. These data are in agreement with the chemical section data of Reid (1965). The negative AMC in their easternmost sam- ple could be the result of two processes: 1) Columbia River input, or 2) coastal upwelling. More depth-distribution data are necessary before the source of this older water can be determined. Similar A14C values occur at depths of ~ 100 m in the GEOSECS data (Ostlund and Stuiver 1980). The upwelling rate (Craig 1969) and source-water depth for the upwelled water could be obtained in the central Gulf il vertical profiles of A"C, nutrients, and total CO., were available. The GEOSECS Pacific radiocarbon section of Ostlund and Stuiver (1980) shows a distinct lens of very old (A"C = -240°/oo) water at depths of 2,000 to 3,000 m along the western boundary of the Gulf of Alaska. Kroopnick's (1985) analyses of stable carbon isotopes (l:,C/''-'C) of total CO., for the same GFOSECS samples show a lens of water with the lowest 81SC values found in the world ocean. Organic matter undergoes isotopic fractionation during respiration in which the light isotope (12C) is selectively added to the total (X),, reservoir. These negative or light 8,3C values reflect the fact that this water is very old. The cur- rent measurements of Warren and Owens (1985) suggest that this water is carried into the Gulf, so radiocarbon and l3C could be valuable tracers for physical processes in the Gulf of Alaska. The carbon dioxide system in the Gulf of Alaska has been studied in some detail. The partial pressure of C02 in sur- face waters has been measured in underway transects across the Gulf of Alaska (Gordon, Park, Hager, and Parsons 1971; Gordon, Park, Kelley, and Hood 1973; and Kelley and Hood 1971). These studies showed elevated CO., partial pressures that are consistent with upwelling of deep water. Recent carbonate system data (Feely and Chen 1982; Chen 1982; and Feely, Byrne, Betzer, Gendron, and Acker 1984) suggest that deep Gulf of Alaska waters are particu- larly susceptible to increases in atmospheric C02. These authors calculated that the degree of aragonite and calcite supersaturation is lowest in the surface and intermediate waters north of 50°N in the Gulf of Alaska, as a result of the high total CO.,-to-alkalinity ratio. Further, Feely et al. (1984) provide calculations that suggest that the surface waters could become aragonite-undersaturated during the next century as increases in atmospheric C02 cause further decreases in surface-water carbonate ion activitv. Betzer, 170 60 60 120 120 Figure 4-5. Surface l4C data (collected June 1982) of Stuiver and Quay (unpubl. data). Data are reported as A14C (°/oo) and are plotted on the surface circulation scheme of Dodimead, Favorite, and Hirano (1963). 82 Pmsii-M Enmkonmint Bv rne, Acker, I ,ewis, Jolley, and Feely (1984) showed that ara- gonite pteropod tests are quite soluble at depth in the west- ern Pacific and suggested that biogenic particle fluxes through the euphotic /one are almost large enough to bal- ance the Pacific Ocean alkalinity budget. Anthropogenic chlorofluoromethanes (Freon-11 (CC13F) and Freon-12 (CC1.,F._,)) have been measured in the North- east Pacific (Gammon, Cline, and Wisegarver 1982). These compounds are biologically inert and are stable over time scales exceeding 1,000 years. Since their atmospheric input function is known, they can be used as transient tracers. Chlorofluoromethanes appear to be in saturation equi- librium with surface waters (Wisegarver and Cline 1985). The recent chlorofluoromethane solubility determinations of Warner and Weiss (1985) cover the temperature range of from 0 to 40C for both pure water and seawater. These val- ues appear to supersede those of Wisegarver and Cline (1985). Cline et al. (1985) used a one-dimensional model (which considered the vertical advection and diffusion of an expo- nentially driven conservative tracer) with these data in order to estimate both vertical diffusivities (Kz = 0.3-0.7 cm2/s) and upwelling velocities (w = 9-10 m/y). These are the best estimates for these important parameters in the Gulf of Alaska at the present time and are in agreement with Silker's (1972) estimate for Ky. Freons were used as surrogate tracers of CO<, in conjunc- tion with precise measurements of carbon dioxide system components (Cline et al. 1985) and were used to estimate the amount of excess CO<, in North Pacific gyre waters. Unlike radiocarbon, ,3C, and tritium, chlorofluoromethanes can (and must) be analyzed at sea. Improvements in blank reduc- tion should lower the detection limit to less than 10~H micro- moles. This improvement, coupled with the fact that the transient from bomb-introduced tritium is decaying, makes chlorofluoromethanes an important tracer for future work. Chlorofluoromethanes have been used successfully to trace bottom and intermediate water in the Atlantic (Bullister and Weiss 1983; Weiss, Bullister, Gammon, and Warner 1985), and could be a valuable tool in studies of the origin of Pacific Intermediate Water. Continental Shelf Waters Most chemical studies on the Gulf of Alaska shelf have been conducted in limited areas, such as the northeast Gulf shelf near Icy Bay, lower Cook Inlet, or Shelikof Strait (Lar- rance, Tennant, Chester, and Ruffio 1977; Atlas, Ven- katesan, Kaplan, Feely, Griffiths, and Morita 1983), and address specific questions, making it difficult to generalize using these data. Much of our understanding of seasonal changes in Gulf of Alaska shelf waters is the result of: 1) the time-series occupation of a hydrographic section (the GAK line) across the shelf from Resurrection Bay (Royer 1975), and 2) measurements from a single station (GAK-1) located at the mouth of Resurrection Bay. While limited nutrient data are available for this region of the shelf, summer and winter profiles for a station near GAK-1 are shown in Figure 4-6. Although the station has been occupied irregularly M.M N03"-N 10 20 30 HM NCV-N 10 20 30 September 1973 January 1975 Figure 4-6. Summer and winter nutrient profiles from a sta- tion near the mouth of Resurrection Bay (RES-5: 59° 50'N, 149° 28'W). since 1970 (Xiong and Royer 1984; Royer and Xiong, Univer- sity of Alaska, unpubl. data), it still provides time-series data sufficient both to resolve seasonal changes in water types on the shelf and to detect several El Nino/Southern Oscillation events in the Gulf of Alaska. This data base was enlarged by OCSEAP-sponsored observations, which included exten- sive hydrographic measurements, satellite-tracked drifters (Royer, Hansen, and Pashinski 1979), and moored current meter observations (Reed and Schumacher, Ch. 3, this volume). The large-scale seasonal changes in the bottom water of the coastal Gulf of Alaska depend on seasonal changes in the meteorological regime (Royer 1975) and are controlled by the relative positions of the Aleutian Low and the North Pacific High. The dominance of the Aleutian Low during winter causes a series of severe storms and strong easterly winds. As a result of the storms, Ekman transport leads to coastal convergence and downwelling (Royer 1981a). The convergence and downwelling then cause both the accumulation of low-density surface waters along the coast and the replacement of warm, high-salinity bottom waters on the shelf. The surface waters become densest during winter due to lack of coastal runoff and due to cooling. The dominance of the Pacific High in summer brings fair weather and possibly a weak reversal of the wind field, per- mitting warm, relatively high-salinity waters from the cen- tral Gulf to move back over the shelf at depths of 100 to 200 meters. Thus, the relative positions of the Aleutian Low and the North Pacific High meteorological systems lead to sea- sonal changes in the temperature and salinity of Gulf shelf waters, as shown in Figure 4-7. Muench and Heggie (1978) have shown that a combination of tidal action and waters of varying density is important in the bottom water renewal of fjords adjacent to the Gulf of Alaska. These waters originate from no deeper than about 250 m in the central Gulf, and although they do have low-oxygen, high-nutrient sig- natures, the unique waters from the deep Gulf of Alaska are not transported across the shelf and into the coastal inlets. The Alaska Current flows westward along the shelf break (Hayes and Schumacher 1976); and a portion of the coastal flow is diverted offshore by Kayak Island to join the Alaska Current. Two quasi-permanent gyres to the west of Kayak Chemical Distributions 83 U 5 h < at 8 7 - JAN FEB MAR APR MAY Jl N JUL AUG SLP OCT Jan Feb Mar Apr May jun Jul Aug Sep Oct Nov dh Figure 4-7. Monthly means (1970-1983) of temperature and salinity at selected depths from a station near the mouth of Resurrection Bay (GAK-1: 59° 5()'N, 148° 50'W). (Modified from Xiong and Royer 1984.) Island influence coastal circulation and the distribution of suspended particulate matter (Feely, Baker, Schumacher, Massoth, and Landing 1979). The nearshore cyclonic gyre transports suspended matter from the Copper River west along the coast and into Prince William Sound. The off- shore antic.) clonic gyre combines with the coastal flow diver- ted by Kavak Island (which contains suspended matter from glaciers to the east), to transport suspended matter from both sides of Kayak Island off the shelf. Downslope movements of near-bottom water during winter also transport suspended material offshore. Niebauer, Roberts, and Royer (1981) analyzed a current- meter record from the shelf break that showed both current veering and rotation occurring from July through Sep- tember. They hypothesized that the fluctuations were eddies, which may also be an important shelf mixing and transport process. Runoff from major rivers entering the Gulf of Alaska has been summarized by Roden (1967). Precipitation is high along the Gulf coast, averaging some 240 cm/y, some glacial fields receive over 800 cm/y (Royer 1982, 1983; Wilson and Overland, Ch. 2, this volume). Freshwater discharges esti- mated to average 23,000 m3/s enter the coastal Gulf of Alaska through numerous ungauged streams and rivers, reaching a maximum in October (Royer 1982) (Fig. 4-8). This freshwater runoff appears to be a driving mechanism for a coastal current, which has recently been identified (Rover 1979, 1981b; Schumacher and Reed 1980). The influ- ence of the Aleutian Low tends to confine this current to the coast in the northern Gulf of Alaska. This feature has been termed the 'Kenai Current' (Schumacher and Reed 1980) because it reaches its maximum intensity adjacent to the Kenai Peninsula. However, additional work (Royer 1983) has shown that this feature extends from Southeast Alaska to the Bering Sea (Schumacher, Pearson, and Overland 1982) and is sufficiently large to make the term Alaska Coastal Current more appropriate. The Alaska Coastal Current may have a volume transport in excess of 106 m:5/s at velocities in excess of 150 cm/s. It is one of the major avenues for influx of freshwater to the North Pacific Ocean. The Alaska Coastal Current could also be important in the transport and dispersion of eggs, larval forms, and chemical species in coastal waters and fjords. The OCSEAP program conducted during the 1970s on the Gulf of Alaska shelf focused on impacts related to petroleum exploration and production. As a result, a number of studies were directed toward determining accu- rate baseline concentrations of natural petroleum com- pounds in the water, the sediments, and the biota of the region. Petroleum transport mechanisms were also studied in the field and the laboratory. Most field studies were con- ducted in the nearshore and shelf waters that were expected to be heavily impacted by petroleum development. Cline (1977) measured Cj to C4 hydrocarbons both at the surface and at near-bottom for a number of nearshore transects from Yakutat to Resurrection Bay. These measurements were directed toward detection of petroleum seeps in areas of seismic activity. Concentrations were typically in the range of 0.001 to 0.010 micromolar. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DEC Figure 4-8. Mean monthly freshwater discharge for southeast and southcoast Alaska estimated from precipitation. (Modified from Royer 1982.) 84 Physical Environment Cline (1977) suggested that methane might hold promise as an indicator of natural seeps since its concentration was quite variable and methane-enriched plumes could be fol- lowed for considerable distances. Shaw (1977) measured hydrocarbon concentrations in water, sediments, biota, and seston at a number of locations in the Gulf of Alaska and Cook Inlet. These measurements emphasized the heavier, aromatic hydrocarbons and buoyant 'tar particles. Typical concentrations in sediments were in the |ig/kg range; tissue concentrations were a few micrograms per gram. The results of these and other studies indicate that hydro- carbon concentrations in the Gulf of Alaska are similar to those found in other marine environments (Shaw 1977), and that the Gulf of Alaska cannot be considered heavily impacted by petroleum-related hydrocarbons at this time. A large body of hydrocarbon data exists, and a baseline for comparing future hydrocarbon concentrations is estab- lished, but uncertainty concerning natural sources, sinks, and transport mechanisms appears to preclude the use of hydrocarbons as quantitative tracers. Landing and Feely (1981) investigated the chemical com- position of both trapped suspended particles and bottom sediments in the vicinity of Icy Bay and were able to quantify fluxes of trace metals, silica, carbon, and nitrogen. Their study showed that fluvial inputs of continental material dominated the inorganic fraction of the suspended parti- cles. By comparing the trapped particulate material and the underlying sediments, Landing and Feely quantified several key factors, including elemental accumulation rates, the remineralization of particulate organic matter, and the remobilization of trace elements. They found that the majority of remineralization occurs within the sediments below the zone influenced by resuspension, and appears to be biologically mediated. Fjords and Estuaries Of all the areas in the Gulf of Alaska, the fjords have been studied most extensively. Pickard (1961) summarized oceanographic features of British Columbia inlets and some of the larger inlets of Southeast Alaska (1967), and Pickard and Stanton (1980) summarized Pacific fjords studied by the University of British Columbia. Study locations of Alaskan fjords and inlets adjoining the Gulf of Alaska are presented in Figure 4-9. Table 4-2 summarizes these studies and gives information on sill depths, locations, the types of data col- lected, indication of the frequency of sampling, and the duration of the studies. This table presents two noteworthy points about studies on Alaskan fjords in general. First, the observation time-scale is just sufficient to resolve seasonal changes, and second, the duration of the studies rarely exceeds two to three years, so no time-series data set that per- mits interannual comparisons has resulted. There are few observations of chemical species like nutrients, and only a few current measurements. Exceptions to the above points are Boca de Quadra, Port Valdez, and Resurrection Bay. Port Valdez and Boca de Quadra have been the foci of comprehensive interdisciplinary studies due to actual or impending industrial development. Burrell (Ch. 7, this vol- ume) considers seasonal cycles in Boca de Quadra. The Port Valdez studies have spanned almost a decade (Hood, Shiels, and Kelley 1973; Colonell 1982). Resurrection Bay has also been frequently sampled, largely because of its proximity to University of Alaska Institute of Marine Science facilities and also because of the effort put into maintaining the time series at Station GAK-1, near the mouth of Resurrection Bay. The emphasis of most studies on other fjords listed in Table 4-2 has been on explaining their circulation well enough to: 150 145 140 135 130 Figure 4-9. Study locations of fjords and inlets adjacent to the Gulf of Alaska (refer to Table 4-2 for study descriptions). Chemical Distributions 85 • employ them as locations for the study of high sedi- mentation rates associated with glaciers (Hoskin. Bur- rell. and Frcitag 1976, 1978) • use them as "geocheinical buckets' (Heggie 1 * ) 7 7 ) where studies on trace element cycles may be undertaken under conditions of minimum advection • use them for studies of unusual concentrations of marine mammals or crustaceans (Carpenter 1983). Anoxic conditions have not been observed in Alaskan fjords, indicating that their bottom waters are renewed at least annually (Muench and I leggie 1978). Muench and Heggie (1978) provided a basic explanation for both the time and the duration of circulation in fjords fronting on the Gulf of Alaska shelf. This explanation serves as a very good departure point for generalizing how the bot- tom waters of these fjords interact with Gulf of Alaska shelf waters. The Muench and Heggie study built upon results of a study of Russell Fjord (Reeburgh, Muench, and Cooney 1976) and then used an expanded data base to explain the circulation of virtually all fjords on the southcentral Alaskan coast. The Russell Fjord study showed that there was little or no slope in the isopleths along the Fjord's long axis, indicat- ing a lack of entrainment Each tide added boluses of water over the sill that could be identified using 'NO' (Broecker 1974). (This conservative parameter is produced by combin- ing observations of dissolved oxygen and nitrate in the proper ratio.) The seasonal change in the density ol shelf waters (Rover 1975) was also tracked by changes in the value of 'NO' (Reeburgh il a/. 1970), providing a seasonal signature for the boluses. During April, these boluses were sufficienth dense to sink to the bottom of the fjord, but as source waters became less dense during summer, the boluses interleaved at both intermediate and near-surface depths. Muench and Heggie (1978) considered fjords with 1) shal- low sills, 2) intermediate-depth sills (about 150 m), and 3) deep or unrestricted sills. Bottom waters in shallow-silled fjords, such as Russell Fjord and Aialik Bay, are renewed between February and April when surface shelf-waters are most dense. Reduced freshwater input and winter cooling produce these dense waters. Deep and bottom waters in fjords with intermediate-sill depths (such as Port Valdcz) closely follow shelf-water density changes and lead to fairly continuous flushing. Fjords with deep or unrestricted sills (such as Prince William Sound or Resurrection Bay) are flushed between July and October when warm, saline water Table 4-2. Studies of fjords and inlets adjacent to the Gulf of Alaska (refer to Fig. 4-9 for location map). ] Location Controlling Sampling Duration/ Name N Latitude W Longitude Study Sill Depth (m) Data Types3 Frequency Boca de Quadra 55° 10' 130° 40' Burrell (this volume) 85 Comprehensive, Cur 40 Cruises/4 Years Smeaton Bay 55° 20' 130° 45' Burrell (this volume) 140 Comprehensive, Cur Silver Bay 57° 15' 135° 12' McAlister ?/ a/. (1959) 64 T,S,02, Nut.Alk.Cur 2 Cruises/1 Year Endicott Arm 57° 40' 133° 20' Nebert(1972) 33 T, S, Oa, Cur 5 Cruises/2 Years N. Dawes Inlet 57° 31' 133° 01' Loder and Hood DOC, POC Glacier Bay (1972) Muir Inlet 59° 136° 10' Quinlan(1970); Matthews and Quinlan(1975) 62 T,S,02 1 1 Cruises/2 Years Queen Inlet 59° 136° 40' Hoskin ?< al. (1976) 115 T, S, SS 2 Cruises/1 Year Vakutat Bay 59° 139° Burrell, Unpubl. data 25 T,S 1 Cruise Russell Fjord 59° 45' 139° 15' Reeburgh etal. (1976) 30 T,S,02,Nut 4 Cruises/1 Year Prince William Sound 60° 40' 147° Schmidt (1977) 300 T, S, 02, Nut 10 Cruises/3 Years Port Valdez 61° 05' 146° 28' Hood et al. (1973) Colonell(1982) 110-128 Comprehensive, Cur Comprehensive, Cur 6 Cruises/1 Year 1 2 Cruises/2.5 Years Blue Fjord 60° 28' 148° 15' Hoskin et al. (1978) 115 T, S, SS 2 Cruises/1 Year Unaquik Inlet 61° 147° 30' Muench and Heggie (1978) 4 T, S 1 Cruise Resurrection Bay 60° 149° 25' Heggie (1977); Heggie etal. (1977) 185 T,S, 02,Nut,Cu, Mn, Cur 24 Cruises/2.5 Years Aialik Bay 59° 50' 149° 40' Carpenter (1983) 6-10 T, S, Biological 6 Cruises/2 Years Cook Inlet 60° 153° Rosenberg and Hood (1967) Feely and Massoth (1982) T,S T.S.SS 2 Cruises 4 Cruises » Symbols for parameters measured are: Cur (currents); T (temperature); S (salinity); Oa (disolved oxygen); Nut (nutrients); Alk (alkalinity); DOC (dissolved organic carbon); POC (particulate organic carbon); SS (suspended solids); Cu (copper); Mn (manganese). 86 Physical Environment from the central Gulfreoccupies the shelf under conditions of reduced convergence. This water from depths greater than 150 in is denser than winter surface water, but is unavailable to the shallow-silled fjords. This means that the bottom waters of both shallow and deep-silled fjords are renewed during high density 'windows' that occur in winter and summer, respectively. This flushing scheme is depicted schematically in Figure 4-10. August — October October — April North Pacific High VVi si /TnWinds Runoff^ 33°/o» /-v /32.5"U ■* id w Aleutian Low UGUS'i-OcroBER Water Figure 4-10. Schematic diagram showing response of bottom waters of deep, intermediate, and shallow-silled fjords to sea- sonal changes in shelf-water density. (Modified from Heggie 1977.) Similar generalizations for Southeast Alaska fjords are hampered by the lack of a shelf- or source-water density time series, as well as by more complicated source-water hydrography and circulation. However, Nebert (1972) con- cluded that the flushing of Endicott Arm was driven by both density and the tides as in the examples above. It appears that the bottom waters of fjords with the shallowest sills and the most restricted circulation are replaced at rates of — 1%/d (Reeburgh et al. 1976). During summer, fjords are a large (but unquantified) source of freshwater to the coastal Gulf of Alaska. Several recent studies have reported the processes con- trolling copper (Cu) and manganese (Mn) in distinctly dif- ferent Alaskan coastal inlets. Feely, Chester, Paulson, and Larrance (1982) used collections from short-term sediment trap deployments in Kachemak Bay (Cook Inlet) to demon- strate a seasonal cycle in organically bound Cu and Mn. The organically bound metals were associated with fecal pellets, and showed strong enrichments late in the year. Feely et al. (1982) suggested that fecal pellets governed transport of Cu and Mn to the sediments and deeper waters. Copper (Heg- gie 1983) and manganese (Owens, Burrell, and Weiss 1980) were studied in Resurrection Bay, where bottom waters remain effectively isolated during part of the year. These studies emphasized removal and remobilization in surface sediments; both studies showed short residence times for both metals (Cu ~ 21 d; Mn ~ 10 d) in the deeper waters and indicated that input and removal processes rather than recy- cling controlled their geochemistry in this environment. Interaction Between Domains Although this chapter has emphasized the small chemical data base available for the Gulf of Alaska, it has also shown that we do have a first-order understanding of the major distributions and circulation patterns for the deep waters and the continental shelf, as well as for the coastal inlets and fjords. The physical oceanography of the Gulf of Alaska and its margins appears to be well-enough defined to permit the application of several isotopic tracers that, when combined with current and other water property measurements, could lead to a vast improvement in our state of knowledge. We submit that the system lends itself more to a careful applica- tion of selected tracers than to remedial chemical surveys. In this section, we address interactions between domains and suggest several chemical measurements that should be employed in future work to better understand mixing rates and interactions. Gulf of Alaska/Pacific Ocean Interaction Most of the information on interactions between the Gulf of Alaska and the Pacific Ocean has been obtained from deep sections (the GEOSECS and NORPAC data) and the recent work of Warren and Owens (1985). Good hypotheses for deep circulation have been advanced (Reid and Mantyla 1978), but none have been confirmed or quantified. Detailed observations of currents, nutrients, radiocarbon, and perhaps other parameters in specific, selected deep- water areas could lead to a quantum jump in understanding fluxes and mixing rates in the deep Gulf of Alaska. The Gulf of Alaska has been shown to be a major source — perhaps one of the most striking examples in the world ocean — of freshwater to the North Pacific, but estimates of the fluxes have been obtained indirectly. This freshwater input is important in the formation of Pacific Intermediate Water (Reid 1973), and future work should include using conservative tracers such as tritium (Fine and Ostlund 1977) and 180/160 ratios (Fairbanks 1982) to quantify the source function and fluxes of this freshwater. It is especially important to continue following the chloro- fluoromethane transient with improved analytical tech- niques. Chlorofluoromethane measurements similar to those reported for the Atlantic (Bullister and Weiss 1983; Weiss et al. 1985) should be taken in the North Pacific coastal waters, as well as in the Pacific Intermediate Water. Gulf of Alaska/Continental Shelf Interaction The Alaska Current, eddies on the continental shelf, and the Alaska Coastal Current are all known to be important elements in mixing processes and in the transport of sus- pended sediments. However, there is no information on the scales of interaction between the shelf and the central Gulf. Radium -228 is a tracer whose introduction mechanism (dissolution from sediments) and decay rate (~7-y half- life) make it a potential tracer for quantifying mixing between the continental shelf and Gulf of A laska (Kaufman, Chemical Distributions 87 Trier, Broecker, and Feely 1973). Seasonal cross-shelf trans- ects of228 Ra could show the influence of coastal waters on the Gulf of Alaska. Chlorofluoromethanes should also be good tracers of shelf-water inputs to the subsurface central ( iulf. As above, oxygen isotope ratios would be important in resolving shelf/Gulf interactions, as well as in determining how effectively the freshwater inputs are confined to the coast by both current and wind systems. Continental Shelf/Fjord Interaction The interactions between the continental shelf and the fjords are probably the best understood of the domains con- sidered in this chapter. However, our information is still very descriptive. A good understanding of annual cycles is available, but for events occurring on time scales of days — or even weeks — there are few instances where any resolu- tion has been reached. Time-series measurements should be attempted in the future using moored fluorometers and ncphelometers, and chemical sensors currently under development. Fjords are large sources of freshwater to the Gulf of Alaska and are logical places to obtain seasonal source-function information on conservative water tracers like tritium and l80/160 ratios. To date, the Alaska Coastal Current has only been traced using salinity. It may be possi- ble to include compounds from terrestrial runoff, such as terpenes (Button 1984), as well as tritium and oxygen isotope ratios as tracers. Since all are runoff-related, they should have similar seasonal source functions and should become an independent, high-sensitivity means of tracing the Alaska Coastal Current. Acknowledgments This chapter was prepared with support from the Miner- als Management Service, Department of the Interior, through an interagency agreement with the National Oceanic and Atmospheric Administration, Department of Commerce, and through a Memorandum of Understanding with the University of Alaska, and with support from the State of Alaska, as part of the Alaska Outer Continental Shelf Environmental Assessment Program. We thank M. Stuiver and P. Quay for making their unpublished radiocar- bon data available, and thank T. Royer, R. Feely, and R. Gammon for helpful discussions. This is contribution number 620 from the Institute of Marine Science, University of Alaska, Fairbanks, Alaska. References Anderson, G.C., R.K. Lam, B.C. Booth, and J.M. Glass 1977 A description and numerical analysis of factors affecting processes of production in the Gulf of Alaska. Research Unit 58. Environmental Assess- ment of the Alaskan Continental Shelf, Annual Reports of Principal Investigators 7:477-798. Atlas, R.M., M.I. Venkatesan, I.R. Kaplan, R.A. Feeley, R.P. Griffiths, and R.Y. Morita 1983 Distribution of hydrocarbons and microbial populations related to sedimentation proc- esses in Lower Cook Inlet and Norton Sound, Alaska. Arctic 36:251-261. Barnes, C.A. and T.G. Thompson 1938 Physical and chemical investigations in Bering Sea and portions of the North Pacific Ocean. University of Washington Publications in Oceanogra- phy 3:39-163. Betzer, P.R., R.H. Byrne, J.G. Acker, C.S. Lewis, R.R. Jolley, and R.A. Feely 1984 The oceanic carbonate system: a reassessment of biogenic controls. Science 226:1074-1077. Broecker, W.S. 1974 "NO", a conservative water-mass tracer. Earth and Planetary Science Letters 23:100-107. Broecker, W.S. and T.-H. Peng 1982 Tracers in the Sea. Lamont-Doherty Geological Observatory, Palisades, NY. 690 pp. Broecker, W.S., D.W. Spencer, and H. Craig 1982 GEOSECS Pacific Expedition, Vol. 3: Hydrographic Data, 1973-1979. Washington, D.C. 137 pp. Bullister, J.L. and R.F. Weiss 1983 Anthropogenic chlorofluoromethanes in the Greenland and Norwegian seas. Science 221: 265-268. Button, D.K. 1984 Evidence for a terpene-based food chain in the Gulf of Alaska. Applied and Environmental Micro- biology 48:1004-1011. Carpenter, T.A. 1983 Pandalid shrimp in a tidewater glacier fjord. M.S. Thesis, University of Alaska, Fairbanks, AK. 122 pp. Chen, C.-T.A. 1982 Oceanic penetration of excess CO., in a cross section between Alaska and Hawaii. Geophysical Research Letters 9:117-119. 88 Physical Environment Cline,J.D. 1977 Distribution of light hydrocarbons, C,-C.|, in the northeast Gulf of Alaska, lower Cook Inlet, and southeastern Chukchi Sea. Research Unit 153. Environmental Assessment of the Alaska Conti- nental Shelf, Annual Reports of Principal Investiga- tors 13:180-268. Cline, J.D., R.A. Feely, K. Kelly-Hansen, J.F. Gendron, D.P. Wisegarver, and C.T. Chen 1985 Current inventory of anthropogenic carbon dioxide in the North Pacific subarctic gyre. NOAA Technical Memorandum ERL/PMEL- 60. 46 pp. Colonell, J.M., editor 1982 Port Valdez, Alaska: Environmental Studies 1976-79. Occasional Publication No. 5, Insti- tute of Marine Science, University of Alaska, Fairbanks, AK. 373 pp. Craig, H. 1969 Abyssal carbon and radiocarbon in the Pacific. Journal of Geophysical Research 74:5491-5506. Craig, H., W.S. Broecker, and D.W. Spencer 1981 GEOSECS Pacific Expedition, Vol. 4: Sections and Profiles. U.S. Government Printing Office, Washington, D.C. 251 pp. Dodimead, A.J., F. Favorite, and T. Hirano 1963 Review of oceanography of the subarctic Pacific region. Bulletin of the International North Pacific Fisheries Commission No. 13. 195 pp. Dodimead, A.J., F.W. Dobson, N.K. Chippindale, and HJ. Hollister 1962 Oceanographic Data record, North Pacific Sur- vey: May 23 to July 5, 1962. Fisheries Research Board of Canada Manuscript and Report Series (Oceanographic and Limnological) No. 138. 384 pp. Fairbanks, R.G. 1982 The origin of continental shelf and slope water in the New York Bight and Gulf of Maine: evi- dence from H2180/H2160 ratio measurements. Journal of Geophysical Research 87C:5796-5808. Feely, R.A., and C.-T.A. Chen 1982 The effect of excess C02 on the calculated cal- cite and aragonite saturation horizons in the northeast Pacific. Geophysical Research Letters 9:1294-1297. Feely, R.A. and GJ. Massoth 1982 Sources, composition and transport of sus- pended particulate matter in lower Cook Inlet and northwest Shelikof Strait, Alaska. NOAA Technical Report ERL 415-PMEL 34. 28 pp. Feely, R.A., A.J. Chester, A.J. Paulson, and J.D. Larrance 1982 Relationships between organically bound Cu and Mn in settling particulate matter and bio- logical processes in a subarctic estuary. Estuaries 5:74-80. Feely, R.A., E.T. Baker, J.D. Schumacher, G.J. Massoth, and W.M. Landing 1979 Processes affecting the distribution and trans- port of suspended matter in the northeast Gulf of Alaska. Deep-Sea Research 26:445-464. Feely, R.A., R.H. Byrne, P.R. Betzer, J.F. Gendron, and J.G Acker 1984 Factors influencing the degree of saturation of the surface and intermediate waters of the North Pacific Ocean with respect to aragonite. Journal of Geophysical Research 89C:10,631- 10,640. Fine, R.A. and H.G. Ostlund 1977 Source function for tritium transport models in the Pacific. Geophysical Research Letters 4:461- 464. Fine, R.A., J.L. Reid, and H.G. Ostlund 1981 Circulation of tritium in the Pacific Ocean. Journal of Physical Oceanography 11:3-14. Gammon, R.H., J. Cline, and D. Wisegarver 1982 Chlorofluoromethane in the northeast Pacific Ocean: measured vertical distributions and application as transient tracers of upper ocean mixing. Journal of Geophysical Research 87C: 9441-9454. Gordon, L.I., P.K. Park, S.W. Hager, and T.R. Parsons 1971 Carbon dioxide partial pressures in north Pacific surface waters - time variations.yowrraz/ of the Oceanographical Society of Japan 27:81-90. Gordon, L.I., P.K. Park, J.J. Kelley, and D.W. Hood 1973 Carbon dioxide partial pressures in north Pacific surface waters. 2. General late summer distribution. Marine Chemistry 1:191-198. Hayes, S.P. andJ.D. Schumacher 1976 Description of wind, current and bottom pres- sure variations on the continental shelf in the northeast Gulf of Alaska from February to May 1975. Journal of Geophysical Research 81:6411- 6419. Heggie, D.T. 1977 Copper in the sea: a physical-chemical study of reservoirs, fluxes and pathways in an Alaskan fjord. Ph.D. Dissertation, University of Alaska, Fairbanks, AK. 214 pp. Heggie, D.T. 1983 Copper in the Resurrection Fjord. Estuarine, Coastal and Shelf Science 17:613-635. Chfmical Distributions 89 Heggie, D.T., D.W. Boisseau, and D.C. Burrell 1977 Hydrography, nutrient chemistry, and primary productivity of Resurrection Bay, Alaska, 1972-75. Report R77-2, Institute of Marine Science, University of Alaska, Fairbanks, AK. Ill pp. Hokkaido University 1981 Hokkaido University Faculty of Fisheries. Data Record of Oceanographic Observations and Exploratory Fishing No. 24. 351 pp. Hood, D.W., W.E. Shiels, and E.J. Kelley, editors 1973 Environmental Studies of Port Valdez . Occasional Publication No. 3, Institute of Marine Science, University of Alaska, Fairbanks, AK. 495 pp. Hoskin, CM., D.C. Burrell, and G.R. Freitag 1976 Suspended sediment dynamics in Queen Inlet Glacier Bay, Alaska. Marine Science Communica- tions 2:95-108. Hoskin, CM., D.C Burrell, and G.R. Freitag 1978 Suspended sediment dynamics in Blue Fjord, Western Prince William Sound, Alaska. Estuarine and Coastal Marine Science 7:1-16. Institute of Ocean Sciences 1978 Oceanic observations at Ocean Station P, 24 March-10 May 1978. Pacific Marine Science Report Series No. 78-20. Kaufman, A., R.M. Trier, W.S. Broecker, and H.W. Feely 1973 Distribution of 228Ra in the world ocean. Journal of Geophysical Research 78:8827-8848. Kelley, J.J. and D.W. Hood 1971 Carbon dioxide in the Pacific Ocean and Ber- ing Sea: upwelling and mixing. Journal of Geo- physical Research 76:745-752. Kort, V.G., editor 1966 Chemistry of the Pacific Ocean, Vol. Ill . Akademiya Nauk SSSR, Trudy Instituta Okeanologii Im. P.P. Shirshova, Moscow. 358 pp. (in Russian) (English version: The Pacific Ocean, Vol. Ill, Chem- istry of the Pacific Ocean . Translated for the U.S. Naval Oceanographic Office, Washington, D.C. 349 pp.) Kroopnick, P.M. 1985 The distribution of l3C of ECOL, in the world oceans. Deep-Sea Research 32:57-84. Landing, W.M. and R.A. Feely 1981 The chemistry and vertical flux of particles in the northeastern Gulf of Alaska. Deep-Sea Research 28A49-37. Larrance, J.D., D.A. Tennant, A.J. Chester, and P.J. Ruffio 1977 Phytoplankton and primary productivity in the northeast Gulf of Alaska and lower Cook Inlet. Research Unit 425. Environmental Assess- ment of the Alaska Continental Shelf Annual Reports of Principal Investigators 10:1-136. Loder, T.C and D.W. Hood 1972 Distribution of organic carbon in a glacial estu- ary in Alaska. Limnology and Oceanography 17:349-355. McAllister, CD., T.R. Parsons, and J.D.H. Strickland 1960 Primary productivity and fertility at Station "P" in the north-east Pacific Ocean. Journal du Conseil Permanent International pour VExploration de la Mer 25:240-259. McAlister, W.B., M. Rattray, Jr., and C.A. Barnes 1959 The dynamics of a fiord estuary: Silver Bay, Alaska. University of Washington Department of Oceanography Technical Report No. 62. Reference 59-28. 70 pp. Mantyla, A.W. and J.L. Reid 1983 Abyssal characteristics of the world ocean waters. Deep-Sea Research 30:805-833. Massoth, G.J., R.A. Feely, P.Y. Appriou, and S.J. Ludwig 1979 Anomalous concentrations of particulate man- ganese in Shelikof Strait, Alaska: an indicator of sediment-seawater exchange processes. Transactions, American Geophysical Union 60:852. (Abstract only) Matthews, J.B. and A.V. Quinlan 1975 Seasonal characteristics of water masses in Muir Inlet, a fjord with tidewater glaciers. Journal of the Fisheries Research Board of Canada 32:1693-1703. Michel, R.L. and H.E. Suess 1975 Bomb tritium in the Pacific Ocean. Journal of Geophysical Research 80:4139-4152. Miller, C.B., B.W. Frost, H.P. Batchelder, M.J. Clemons, and R.E. Conway 1984 Life histories of large grazing copepods in a subarctic ocean gyre: Neocalanus plumchrus, Neo- calanus cristatus, and Eucalanus bungii in the northeast Pacific. Progress in Oceanography 13:201-243. Muench, R.D. and D.T. Heggie 1978 Deep water exchange in Alaskan subarctic fjords. In: Estuarine Transport Processes. B. Kjerfve, editor. Belle W. Baruch Institute for Marine Biology and Coastal Research. Univer- sity of South Carolina Press, Columbia, SC pp. 239-267. 90 Physical Environment Xebert, D.L. 1972 A proposed circulation model for Endicott Arm, an Alaskan fjord. M.S. Thesis, University of Alaska, Fairbanks, AK. 90 pp. Niebauer, H.J..J. Roberts, and T.C. Royer 1981 Shelf break circulation in the northern Gulf of Alaska. Journal of Geophysical Research 86C: 4231-4242. NORPAC Committee 1960 Oceanic Observations of the Pacific: 1955, The NOR- PAC Data. Scripps Institution of Oceanography of the University of California, University of California Press, Berkeley, CA. 532 pp. NORPAC Committee 1965 Oceanic Observations of the Pacific: 1959. Scripps Institution of Oceanography of the University of California, University of California Press, Berkeley, CA. 901 pp. Ostlund, H.G. and M. Stuiver 1980 GEOSECS Pacific Radiocarbon. Radiocarbon 22:25-53. Owens, T.L., D.C. Burrell, and H.V. Weiss 1980 Reaction and flux of manganese within the oxic sediment and basin water of an Alaskan fjord. In: Fjord Oceanography. H.J. Freeland, D.M. Farmer, and CD. Levings, editors. NATO Con- ference Series IV, Vol. 4. Plenum Press, New York, NY. pp. 667-673. Peng., T.-H., T. Takahashi, and W.S. Broecker 1974 Surface radon measurements in the North Pacific Ocean Station Papa. Journal of Geophysi- cal Research 79:1772-1780. Pickard, G.L. 1961 Oceanographic features of inlets in the British Columbia mainland coast.Journal of the Fisheries Research Board of Canada 18:907-999. Pickard, G.L. 1967 Some oceanographic characteristics of the larger inlets of southeast Alaska. Journal of the Fisheries Research Board of Canada 24:1475-1506. Pickard, G.L. and B.R. Stanton 1980 Pacific Fjords — a review of their water charac- teristics. In: Fjord Oceanography. H.J. Freeland, D.M. Farmer and CD. Levings, editors. NATO Conference Series IV, Vol. 4. Plenum Press, New York, NY. pp. 1-51. Pytkowicz, R.M. and D.R. Kester 1966 Oxygen and phosphate as indicators for the deep intermediate waters in the northeast Pacific Ocean. Deep-Sea Research 13:373-379. Quinlan, A.V. 1970 Seasonal and spatial variations in the water mass characteristics of Muir Inlet, Glacier Bay, Alaska. M.S. Thesis, University of Alaska, Fair- banks, AK. 145 pp. Redfield, A.C, B.H. Ketchum, and FA. Richards 1963 The influence of organisms on the composi- tion of sea-water. In: The Sea, Vol. 2. M.N. Hill, editor. Interscience Publishers, New York, NY. pp. 26-77. Reeburgh, W.S., R.D. Muench, and R.T. Cooney 1976 Oceanographic conditions during 1973 in Rus- sell Fjord, Alaska. Estuarine and Coastal Marine Science 4:129-145. Reid,J.L.,Jr. 1965 Intermediate Waters of the Pacific Ocean. The Johns Hopkins Oceanographic Studies, No. 2. Johns Hopkins Press, Baltimore, MD. 85 pp. Reid,J.L.,Jr. 1973 Northwest Pacific Ocean Waters in Winter. The Johns Hopkins Oceanographic Studies, No. 5. Johns Hopkins Press, Baltimore, MD. 96 pp. Reid, J.L., Jr. and A.W. Mantyla 1978 On the mid-depth circulation of the North Pacific Ocean. Journal of Physical Oceanography 8:946-951. Roden, G.L 1967 On river discharge into the northeastern Pacific Ocean and the Bering Sea. Journal of Geo- physical Research 72:5613-5629. Rosenberg, D.H. and D.W. Hood 1967 Descriptive oceanography of Cook Inlet, Alaska. Transactions of the American Geophysical Union 48:132. (Abstract only) Royer, T.C. 1975 Seasonal variations of waters in the northern Gulf of Alaska. Deep-Sea Research 22:403-416. Royer, T.C. 1979 On the effect of precipitation and runoff on coastal circulation in the Gulf of Alaska./owrn<2/ of Physical Oceanography 9:555-563. Royer, T.C. 1981a Baroclinic transport in the Gulf of Alaska. Part I. Seasonal variations of the Alaska Current. Journal of Marine Research 39:239-250. Royer, T.C. 1981b Baroclinic transport in the Gulf of Alaska. Part II. Fresh water driven coastal current. Journal of Marine Research 39:251-266. Chimkai Distrikuiions 91 Royer, T.C. 1982 Coastal fresh water discharge in the northeast Pacific. Journal of Geophysical Research 87C 2017-2021. Rover, T.C. 1983 Observations of the Alaska Coastal Current. In: Coastal Oceanography- H. Cade, A. Edwards, and H. Svendsen, editors. Plenum Press, New York, NY. pp. 9-30. Royer, T.C, D.V. Hansen, and D.J. Pashinski 1979 Coastal flow in the northern Gulf of Alaska as observed by dynamic topography and satel- lite-tracked drogue drift buoys. Journal of Phys- ical Oceanography 9:785-801. Schmidt, CM, III 1977 The exchange of water between Prince William Sound and the Gulf of Alaska. M.S. Thesis, Uni- versity of Alaska, Fairbanks, AK. 116 pp. Schumacher, J.D., and R.K. Reed 1980 Coastal flow in the Northwest Gulf of Alaska: the Kenai Current. Journal of Geophysical Research 85:6680-6688. Schumacher, J.D., C.A. Pearson, andJ.E. Overland 1982 On exchange of water between the Gulf of Alaska and the Bering Sea through Unimak Pass. Journal of Geophysical Research 87C5785- 5795. Warner, M.J. and R.F. Weiss 1985 Solubilities of chlorofluorocarbons 11 and 12 in water and seawater. Deep-Sea Research 32:1485- 1497. Weiss, R.F., J.L. Bullister, R.H. Gammon, and M.J. Warner 1985 Atmospheric chlorofluoromethanes in the deep equatorial Atlantic. Nature (London) 314:608-610. Wisegarver, D.P. andJ.D. Cline 1985 Solubility of trichlorofluoromethane (F— 11) and dichlorofluoromethane (F-12) in seawater and its relationship to surface concentrations in the North Pacific. Deep-Sea Research 32A: 97-106. Xiong, Q. and T.C Royer 1985 Coastal temperature and salinity in the north- ern Gulf of Alaska, 1970-1983.Journal of Geophys- ical Research 89O8061-8068. Shaw, D.C 1977 Hydrocarbons: natural distribution and dynamics on the Alaska Outer Continental Shelf. Research Unit 275. Environmental Assess- ment of the Alaskan Continental Shelf, Annual Reports of Principal Investigators 8(Contaminant Baselines):507-757. Silker, W.B. 1972 Horizontal and vertical distributions of radi- onuclides in the North Pacific Ocean Journal of Geophysical Research 77:1061-1070. Tabata, S. 1981 Oceanic time-series measurements from sta- tion P and along line P in the northeast Pacific Ocean. In: Time Series of Oceanographic Measure- ments. Ellett, editor. WCP-21. pp. 171-192. Warren, B.A. 1983 Whv is no deep water formed in the North ¥ acinic? Journal of Marine Research 41:327-347. Warren, B.A. and W.B. Owens 1985 Some preliminary results concerning deep northern-boundary currents in the North Pacific. Progress in Oceanography 14:537-551. Geomorphology, Sediment, and Sedimentary Processes Monty A. Hampton Paul R. Carlson HomaJ. Lee United States Geological Survey Menlo Park, California Richard A. Feely Pacific Marine and Environmental Laboratory National Oceanic and Atmospheric Administration Abstract The Gulf of Alaska continental margin, from Cross Sound in the east to Chirikof Island in the west, has been shaped directly and indirectly by the forces of ice, plate tectonics, and ocean currents. Grounded ice extended to the shelf break at least once during the Pleistocene epoch, covering most or all of the shelf and sculpting broad flat banks and elongated troughs. Glacial, glacial-marine, and glacial-fluvial sediment was deposited in nearly all areas as the ice advanced. As the climate warmed and the ice retreated, the region was inundated by the sea, giving rise to the present geologic environments. The high, youthful mountains to the north of the Gulf provide a plentiful source of sediment that is delivered to the coastline by a few large rivers and remnant glaciers. The major input of sediment occurs in the northeastern Gulf (Copper River, Alsek River, Bering Glacier, and Malaspina Glacier sources) and at the head of Cook Inlet (Knik, Matanuska, and Susitna River sources). Ocean currents in the northeastern Gulf carry the sediment predominantly to the west, depositing much of the load near the shore and in the troughs but delivering some sediment into Prince William Sound and Shelikof Strait. Large embayments in the eastern Gulf coastline accumulate thick, underconsolidated deposits of sediment delivered by local high-gradient streams and glaciers. The coarse sediment from the rivers at the head of Cook Inlet is deposited near the points of entry and, along with the relict glacial sediment in the remainder of the Inlet, is reworked by strong tidal currents. As a result, fields of large sand waves and other current-related bed forms have developed. The fine sediment from the rivers is transported south down the Inlet and is deposited as a progressively sorted sediment blanket throughout Shelikof Strait. The Kodiak Shelf receives little modern sediment, but ocean currents rework the relict glacial debris, leaving coarse-grained lag deposits on the shallow banks and winnowed, fine-grained sediment in the troughs. Collision between the North American and Pacific lithospheric plates generates strong tectonic forces throughout the region. Over long durations of geologic time, these forces cause changes in seafloor elevation that create deep sedimentary basins and uplifted banks and islands. In the short term, strong and frequent earthquakes trigger submarine sediment slides in the deposits of soft sediment on the north- eastern Gulf shelf and along the entire upper continental slope. 93 94 Physical Environment Introduction The geomorphology, the sediment, and the sedimentary processes of the north central Gulf of Alaska continental margin have been studied by numerous investigators for a variety of purposes. The general nature of the geo- morphology and surficial sediment throughout the entire Gulf of Alaska was first described by Gershanovich (1968) from data obtained on reconnaissance cruises by Russian vessels. A more recent compilation was presented by Sharma (1979). In addition, several area-specific geologic studies have been conducted: Cook Inlet (Sharma and Bur- rell 1970); Nuka Bay (von Huene 1966); Prince William Sound (von Huene, Shor, and Reimnitz 1967); Glacier Bay (Powell 1983); and elsewhere. Large, comprehensive data sets were collected in conjunction with studies preparatory for outer continental shelf (OCS) petroleum leasing in four major geographic areas: 1) the northeastern and north cen- tral Gulf of Alaska, from Cross Sound to Montague Island, 2) the Kodiak Shelf, from Amatuli Trough to Chirikof Island, 3) lower Cook Inlet, south of the Forelands, and 4) Shelikof Strait, between the Alaska Peninsula and the Kodiak island group (see summaries by Carlson and Schwab 1982; Hampton 1982a; Hampton 1982b; and Hampton, Johnson, Torresan, and Winters 1981). Figure 5-1 shows the area of study, including the four major geographic areas men- tioned above. This chapter summarizes the geologic studies of the north central Gulf of Alaska continental margin. In addition to a discussion of the entire region, each of the four major geographic areas is considered individually in separate sec- tions. Within each section, the geomorphology of the sea floor, the nature and distribution of the sedimentary depos- its, and the processes by which sediment is transported and deposited are also discussed. Most of the information in this chapter applies to the continental shelf, but data for both the continental slope and the outlying geographic areas are also included. Finally, an overview of the entire region is presented, pointing out the pervasive geologic factors while emphasizing those that make each area unique. While present-day geologic features and processes are the primary focus of this discussion, a certain amount of his- torical perspective is necessary to clearly understand the present geology. An erosional unconformity that most likely occurred during the late Pleistocene age separates struc- turally deformed bedrock from overlying, relatively undeformed and presumably unconsolidated sediment throughout the region. This unconformity and the overly- ing sedimentary deposits are considered herein. Methods Seismic-reflection profiles and sediment samples are the primary data sources for geologic studies of the Gulf of Alaska. The large-scale aspects of geologic framework are deciphered mostly from deep-penetration, low-resolution records from 12- and 24-channel seismic-reflection sys- tems, whereas the details of near-surface stratigraphy and geomorphology are studied with profiles from shal- low-penetration, high-resolution systems such as sparkers, air guns, boomers, and tuned transducers. The thickness and spatial distribution of sedimentary units are deter- mined using these seismic profiles, and the sediment trans- port and deposition processes are inferred from both the geometry and the amplitude of the seismic reflections. Sediment samples from both on and beneath the seabed (collected with vibratory and gravity corers as well as grab samplers) are analyzed to determine the sediment's physical and chemical properties. Most samples are collected from large ships that cannot work safely in the shallow and rough waters near shore; therefore, there are few samples from this zone. Chemical and physical analyses are performed on samples of suspended sediment from the water column. These samples are collected using 0.4-mm pore-size mem- brane filters. Although sedimentary processes and sedimen- tary history are the two main items deduced from the analy- ses of sediment samples, geotechnical, hydrocarbon, and pollutant studies are also conducted. Specialized instrumentation is used for certain purposes. For example, side-scanning sonar provides a plan view of the sea floor from which geomorphic features and sediment type can be discerned. Television and still photography can give similar information for small areas. Oceanographic instruments such as current meters, pressure transducers, and transmissometers yield data for quantification of sedi- mentary dynamics. Sediment strength properties can be measured with in situ probes, but strength and consolidation properties are measured in the laboratory using soil- mechanics testing equipment. Regional Aspects The north central Gulf of Alaska continental margin is a complex and dynamic subpolar geologic environment. Tec- tonic forces, climate, and oceanographic circulation are the major controls on geomorphology and sedimentation. Tec- tonic forces associated with the convergent-to-transform plate-margin setting of the Gulf of Alaska have produced rugged mountains along the entire coastline, as well as large sedimentary basins offshore. Continuing deformation gen- erates large earthquakes and causes changes in sea-floor ele- vation, both of which modify the geomorphology and sedi- mentary environments. Active volcanoes, born from melted subducted lithosphere, line the Alaska Peninsula and north- west coast of Cook Inlet, and also exist farther east in the Wrangell Mountains (Arctic Environmental Information and Data Center 1974). The subpolar climate maintains alpine glaciers near the shoreline in the vicinity of Cape Douglas on the Alaska Pen- insula, along the south coast of the Kenai Peninsula, and in the Chugach and St. Elias Ranges east of the Copper River. Elsewhere, glaciers occur farther inland. Regional glaciation began in Miocene time, proceeding through several stages of advance and retreat. Grounded ice has extended out to the seaward edge of the continental shelf at least once (Karlstrom 1964; Pewe 1975; Plafker and Addicott 1976; von Huene, Crouch, and Larson 1976; Molnia and Sangrey 1979; Thrasher 1979; and Armentrout 1983). Within historic time, Geomorphology, Sediment and Sedimentary Processes 95 < 3 o u 0 Q. (« E o i So 96 Physical Environment local advances across the present shoreline have occurred in the northeast Gulf of Alaska (Molnia 1977). The maritime climate in the Gulf of Alaska is typified by heavy precipitation, strong winds, and relatively mild tem- peratures (see Wilson and Overland, Ch. 2, this volume). The Gulf lies along a major winter storm track. Heavy fall rainstorms and spring snowmelt produce peaks in the sea- sonally variable freshwater runoff, which generally increases to the east (Kramer, Clark, and Cannelos 1978). Regional oceanic circulation is controlled by the west- ward-flowing Alaskan Stream, which has a mean speed of 50 to 100 cm/s and is swiftest near the shelf break (Favorite 1967; Thomson 1972; Reed and Schumacher, Ch. 3, this vol- ume). Circulation across the open shelf is relatively sluggish, with typical current speeds of less than 10 cm/s. The bar- oclinic Kenai Current flows close to the coast along the Kenai Peninsula westward into lower Cook Inlet (Schumacher and Reed 1980). Strong tidal currents are pre- sent in Cook Inlet, and estuarine conditions are created by fresh water entering the head of the inlet (Rosenburg, Bur- rell, Natarajan, and Hood 1967; Muench, Schumacher, and Pearson 1981). Flow from Cook Inlet (along with the regional pressure gradient set up by the Alaskan Stream) drives the circulation in Shelikof Strait where the mean current speed is 10 to 20 cm/s (Muench and Schumacher 1980). Large storm waves periodically traverse the Gulf of Alaska shelf. Max- imum significant wave height for a 5-year recurrence inter- val is 13 m and for a 100-year interval, 22 m; extreme wave heights for 5- and 20-year recurrence intervals are 22 and 40 m, respectively (Brower, Searby, and Wise, Diaz, and Pre- chtel 1977). Waves of this magnitude exert significant force on the sea floor in shallow water and can cause sediment erosion and mass failure (Rappeport 1981; Schwab and Lee 1983). The Gulf of Alaska continental margin has a moun- tainous, glaciated coast with major embayments such as Prince William Sound and Cook Inlet that are structurally controlled and erosionally modified. The arcuate continen- tal shelf from Cross Sound to Chirikof Island generally widens from east to west, from 30 km near Cross Sound to 220 km west of Kodiak Island (Fig. 5-2). The shallow regional unconformity on the Gulf of Alaska continental shelf appears clearly in seismic-reflection pro- files as a discordant juncture between stratified and folded beds below and the stratified, horizontal or folded units above. The youngest known age for either the sedimentary deposits below the unconformity or for the ice-carved mor- phology of the surface itself has been used to deduce that this hiatal feature is of the late Pleistocene age and of glacial origin (McClellan, Arnal, Barron, von Huene, Fisher, and Moore 1980; Molnia and Carlson 1980; Quinterno, Carlson, and Molnia 1980; Carlson et al. 1982; and Hampton 1985). The depth of the unconformity below present sea level in the northeastern Gulf of Alaska, the Kodiak Shelf, lower Cook Inlet, and Shelikof Strait is depicted in Figure 5-3. Although the relief is subdued over broad areas, several basins and U-shaped channels exist. The maximum depth is over 1,100 m in Shelikof Strait. Although the sedimentary sequence over the unconfor- mity can be up to 800 m thick, a typical sedimentary deposit is less than 100 m thick (Fig. 5-4). Many areas lack a sedimen- tary cover, and the bedrock surface is exposed at the sea floor. Samples of the underlying semi-lithified to lithified bedrock are composed of diamicton, sandstone, and mudstone (McClellan et al. 1980; Molnia and Carlson 1978, 1980). Sediment cores from the sequence above the uncon- formity are highly varied, both within and between geo- graphic areas. Gravel- to clay-sized terrigenous material is the most abundant component, but volcanic ash and micro- and megafaunal shells are widespread. In places, volcanic or biogenic material is concentrated in distinct layers. The dis- tribution of textural sediment types is shown in Figure 5-5. Certain sedimentary and erosional events are inferred to have occurred in common over the entire Gulf of Alaska region. Pleistocene glaciers extended out to the shelf break, and platforms, troughs, and basins were eroded into the underlying bedrock. The initial retreat of the grounded ice from the shelf has been documented at about 12,000 years ago in the northeast Gulf of Alaska (Molnia, Levy, and Car- lson 1980), and it probably occurred at nearly the same time on the Kodiak Shelf. When the Holocene sea-level rise began, the ice retreated rapidly across the open shelf because a grounded marine ice sheet is inherently unstable under these conditions (Thomas and Bentley 1978; Thomas 1979). However, due to the pinning effect of landmasses (Thomas 1979), ice may have remained for an extended time around the islands and in land-bounded areas such as Shelikof Strait and Cook Inlet. In any case, each area col- lected glacial and glacial-marine sediment before and dur- ing ice retreat. As the marine transgression swept through the region, the sediment accumulations were reworked and redistributed. Despite these common aspects, each of the four areas under discussion is a unique sedimentary system. This was especially true during Holocene time. The main differences between each of the areas lie in the oceanographic condi- tions and the sediment supply rate. Northeastern Gulf of Alaska Geomorphology General. The northeastern and part of the central Gulf of Alaska continental shelf between Cross Sound and Mon- tague Island has an average gradient of about 0° 15' from shore to shelf break (Atwood et al. 1981). The shelf is cut by eight prominent valleys; from east to west they are Yakobi Valley, Alsek Valley, Yakutat Valley, the two Pamplona Troughs, Bering Trough, Egg Island Trough, and Hinchinbrook Seavalley (Fig. 5-1). The valleys are separated by islands, banks, and ridges that are underlain by folded and faulted late Cretaceous and Cenozoic rocks. The valleys have a U-shaped cross section and each is underlain by an ancestral valley. All but four (Alsek Valley, the Pamplona Troughs, and Egg Island Trough) have a con- cave-upward longitudinal profile with shoaling at the sea- ward end and closed depressions on the valley floor. Egg Island Trough has a convex-upward longitudinal profile, and Alsek Valley and the Pamplona Troughs have a uniform gentle longitudinal profile. The troughs are sediment sinks Geomorpholocy, Sediment and Sedimentary Processes 97 98 Physical Environment V E u s; a •a cu u D w cu c CO ni m % 00 O) 0 a G c V n ■o CU c CU £ re u 0 CM on Ol cu ^^ Oh a £ S J£ c n a ^ fi )h _* r~, u < £ 1+4 o c Lb t+H -1 Im 0 C3 a, c V _g re re u re CO 0 a CU CU cu B c G Si CO JZ CU cu Q- c 0 X M >v -c cu E u a; 1-1 a 4-c re g c o 3 o CO G ••"■' 3 K'- Pi 0 S- u n T) &! 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F* — *J — O o * s c - c rt u- o H - regi vvhe: pton CD - c £ 2 c «3 r- Ca CD CD X ^ c o F re o X. £ B 2 re p 2 *i w o CD Cd 33 c £ in CD -C 2 (O W ^J "*- bo.2 0 C c , c« _*: c i cd re *- c p «* ^ « T3 .y C C jp H re H § § O c/3 . in B S re C B,^* 100 Physical Environment ^^W TD u r rt rt H >* a :_J — 73 ■c e 0 3 e « E mi CO -~ eo " ' >-. >^ >- en V ~ - - 3 - c ra >- c/5 o o 1IDDDID be C O bo fS J2 en ^^ en rrt U C en O g a* a E g cfl en I ;- r^ £ — U '- « CS T) «u a C 3 o o 6fl X ■- en en tfl U C I o G « jj* ti T3 Oh en C en is rt 0 rt x: T3 en &j CD 1 — ' a C o tSb eU * hfl 1 ■ G c -< M u Xj c l-i 0 rfl UJ ~r IS XI en -3 5 u en eU t/3 U ex 0- E >n -, *^ en 4-) i- C o CD ~H £ en -a 1- "o S C C o r! U CD en C O Oh E R) -c c Ri rJ s 3 O 03 rs O O u c - Ceomorpholocy, Sediment and Sedimentary Processes 103 a-. 2 mm in diame- ter) ranges from almost 75% in some samples to nil in oth- ers. The principal areas of gravel accumulation are on the moraines at the mouth of Lituya, Icy, and Yakutat bays, the top and flanks of Pamplona Ridge, and the Tarr Bank-Mid- dleton Island platform. The highest concentration of sand (0.0625-2 mm in size) occurs along the continually changing barrier islands that are prograding westward at the mouth of the Copper River (Reimnitz 1960), where many samples consist of more than 90% sand. Most of the sand is moderately well-sorted and medium- to fine-grained. Hayes (1976) classified the miner- alogically immature sand of the barrier islands as litharenite, containing about equal parts of quartz and meta- morphic rock fragments. Tarr Bank samples also have a rela- tively high sand content that ranges from 10 to 50%, with most of the samples in the 25 to 35% range. The Kayak Island platform is covered by sediment consisting of as much as 88% sand. Other areas of sand dominance are the nearshore zone off the Malaspina Glacier, a patch on the floor of Yakutat Valley, and the nearshore zone across the mouth of the Alsek River. Concentrations of up to 80% silt (0.004-0.0625 mm in size) occur east of Kayak Island, especially seaward of the Malaspina and Bering Glaciers. Much of the shelf in this area is blanketed by clayey silt, a condition that can be attributed largely to the vast quantity of rock flour supplied by glacial meltwater. West of Kayak Island, the highest con- centration of silt (60-72%) is in Kayak and Egg Island Troughs and in Hinchinbrook Seavalley. The highest con- centration of clay (< 0.004 mm in size), 30 to 50%, occurs in Egg Island Trough, Kayak Trough, Hinchinbrook Seavalley, and on much of the shelf between Kayak Island and Pam- plona Spur, a distribution similar to that of silt. The coastal areas have a variety of sediment types. As mentioned above, the barrier islands at the mouth of the Copper River are covered with fine- to medium-grained sand. The beaches that front morainal cliffs are composed of coarse sand to gravel, and some areas southeast of Lituya Bay have bedrock outcrops at the beach surface (Boothroyd and Ashley 1975; Hayes 1976; Reimnitz and Plafker 1976; and Molnia and Wheeler 1978). Further classification of north- east Gulf of Alaska beaches, on the basis of composition, beach slope, and biological cover, is given in an atlas by Sears and Zimmerman (1977). The average clay-mineral assemblage in the sea-floor sediment on the shelf includes 61% kaolinite + chlorite, 37% illite, and 2% smectite (Molnia and Hein 1982). An exception is off the Copper River, where illite content of 65% and kaolinite + chlorite values of 35 to 48% have been measured. Similar high illite (58%) and kaolinite + chlorite (36%) contents have been reported from the suspended load of the Copper River (Griffin, Windom, and Goldberg 1968). Molnia and Hein (1982) suggested that this Copper River anomaly is due to a recent flood event, perhaps as a result of the emptying of a glacial lake. Both groups of authors attribute the high kaolinite + chlorite concentra- tions at high latitudes to the effects of low-intensity chem- ical weathering processes and to glacial transport. Forty sediment samples were analyzed for carbon con tent by Carlson et al. (1977). The highest concentration of carbonate carbon they found was 2.1% from a gravelly mud collected on Tarr Bank. The highest organic carbon content was 0.8% from a clayey silt sampled near the south end of Kayak Island. In general, sandy sediment contained the least carbonate and organic carbon, with values for each ranging from 0.1 to 0.5 percent. The presence of bubble-phase gas (gas charging) has been inferred by analyzing the acoustic anomalies on high- resolution seismic-reflection records. Many of these pro- jected gas occurrences are in areas of sediment slides (Carl- son and Molnia 1977; Hampton, Bouma, Carlson, Molnia, Clukey, and Sangrey 1978; Molnia, Carlson, and Kvenvolden 1978; Molnia 1979a; and Carlson, Molnia, and Wheeler 1980). However, only 2 of 31 core samples analyzed for bio- genic methane by Golan-Bac and Kvenvolden (1983) had the unusually high concentrations that indicate the pres- ence of bubble-phase gas. One of the cores was from a fault zone southeast of Kayak Island and the other core came from an area west of the Alsek River prodelta failure area. Physical Properties. The physical properties of about 150 gravity and vibratory core samples were determined from the northeastern Gulf of Alaska shelf by Lee and Schwab (1983). Also, they conducted nine in-place static cone penetration tests and five in-place vane shear tests. The geotechnical coring and testing stations are grouped into eight study areas (Fig. 5-9), which cover much of the continental shelf and most of the large submarine slides and slumps. The study areas are almost entirely within the Holo- cene silt and sand because most of the sediment failures occur there. 145 140 145 140 Figure 5-9. Geotechnical test areas in the northeastern Gulf of Alaska. A: Copper River prodelta. B: Kayak Trough, C: Bering Trough, D: Icy Bay, E: Icy Bay-Malaspina Glacier, F: Yakutat Bay, G: Yakutat. and H: Alsek River. 108 Physical Environment In the northeastern Gulf, the natural water content is by far the most commonly measured physical property of sedi- ment samples. The saturated sediment of the shelf has a uni- form grain density of about 2.8 g/cm3, and therefore, the water content uniquely determines its bulk density, poros- ity, and void ratio. The water content of near-surface ( < 6 m sub-bottom) sediment in the northeastern Gulf can be used as an index physical property for classifying sediment types. The more sophisticated strength and compression param- eters, as well as other index properties, vary systematically with water content. For example, Figure 5-10 shows the aver- age plasticity index for a core compared with the average water content for the same core. The water content serves as a good classification parameter because the Holocene sedi- ment has low compressibility and is normally consolidated or only slightly underconsolidated throughout the region. The physical properties of the Holocene sediment vary with water depth, distance offshore, sub-bottom depth, and location along shore. Of these four factors, water depth pro- duces the widest variations in the sediment's properties. For each area in which there are enough data to define a trend, average water content increases with water depth (Fig. 5-11A). This fact reflects a transition from nearshore sand (water content less than about 32%) to increasingly finer-grained silt. The Yakutat, Kayak Trough, and Copper River study areas share a common variation in water content, which increases from about 30% at a depth of 50 m to around 50% at 200 meters. Such a consistent variation probably repre- sents a common equilibrium between the supply of sedi- ment and the intensity of bottom currents that resuspend and redistribute the sediment. The Icy Bay-M alaspina study area shoyvs lower water content (less plastic or coarser sedi- ment) than the Yakutat, Kayak Trough, and Copper River areas at the same water depths. Such a shift perhaps indi- cates a slower supply of sediment or more intense bottom currents. The Alsek study area shows much higher water content (more plastic or fine grained sediment) for the same water depths, possibly because of the large quantities of glacial rock flour introduced by the Alsek River. Plasticity Index = Liquid Limit - Plastic Limit (in weight %) £K * • / • • • • • • • • • • • • 20 30 40 50 60 Sediment Water Content (% dry weight) Figure 5-10. Relation of average plasticity index to average sediment water content. Each point represents a separate grav- ity core in the northeastern Gulf of Alaska. A. Sediment Water Content versus Water Depth 60 6S h Z 40 0 u ■ ■ ■ • V • ■■': ■ ■ ■ ■ o • •* _■•••• • • Of • A«« • • • o • V V o OA VB oC ■■ • • t AD • E • • o • G ■ H 0 I 100 200 I 30 Water Depth (m) B. Plasticity Index versus Liquid Limit (Plasticity Chart) 35 ^25 E 20 X u Q 5 15 0J Liquid Limit s water content above which a soil deforms as a liquid 20 40 50 Liquid Limit (weight %) 60 C. Sediment Clay Content versus Sediment Water Content 100-, es XI 80 be a 60 H z U < 40 J u z u S 20 5 u 30 40 50 60 70 80 Sediment Water Content (% dry weight) 90 Figure 5-1 1. Relations between various index properties among the geotechnical test areas in the northeastern Gulf of Alaska (see Figure 5-9 for definition of letters designating test areas) (data, in part, from Lee and Schwab 1983). Geomorpholocy, Sediment and Sedimentary Processes 109 The Bering Trough area has only two water content/ water depth data points, hut these are anomalous. Low water contents (25-35%, indicative of coarser-grained sedi- ment) occur in deep water (250 m), probably because deep water exists close to shore (10 km). One Icy Bay data point (60% water content at 150 m water depth) is anomalously high and likelv represents underconsolidation. A series of linear-regression analyses (separated accord- ing to study area) were performed on plasticity-index/ liquid-limit data that are used in the Unified Soil Classifica- tion System (Lamhe and Whitman 1969: p. 35). Figure 5-11B shows this series, which was used to classify fine-grained sediment. Almost all of the northeastern Gulf of Alaska data, and all of the regression lines, fall above the A-line, which in this engineering classification designates low-to-high plas- ticity clay to silty or sandy clay. Note that the 'clay' designa- tion here refers to plasticity behavior and not grain size. Among the regression plots (excluding the embayments and the anomalous Bering Trough), there is a consistent trend toward greater distance above the A-line as the Kayak Trough study area is approached from either side. Such a trend probablv results from fundamental mineralogical changes, with more active clay minerals corresponding to greater distances above the A-line (Holtz and Kovacs 1981). Figure 5-11C shows a similar trend in the variation of the abundance of clay-sized particles with water content. Lin- ear regression plots for each study area show less clay-sized sediment at the same water content when approaching Kayak Trough from either side. This trend may be a result of increased smectite content in Kayak Trough (Molnia and Hein 1982). Although the smectite content is low throughout the Gulf of Alaska shelf, the up-to-5% smectite content of the Kayak Trough clay fraction is sufficient to influence index properties (Seed, Woodward, and Lundgren 1964). There also are significant subbottom depth fluctuations of geotechnical properties. Figure 5-12 shows typical water content profiles for water depths from 23 to 221 meters. Downcore fluctuations are large, ranging from 15% to over 40%, and indicating alternating layers of relatively plastic and less plastic sediment. In shallow-water cores, bedding is graded (2- to 2.5-m-thick beds are present in core 615A1). Such deposits may result from resuspension and redeposi- tion of a part of the sediment column during major storms. The relationships of consolidation and strength proper- ties to water content are shown in Figure 5-13. The compres- sion index, Cc, determines the settlement potential for struc- tures set on the glacial-marine sediment. Figure 5-13A shows how the compression index varies consistently with natural water content. A similar previous correlation, shown by the plotted curve in Figure 5-13A (Lambe and Whitman 1969, p. 321), would have predicted slightly greater compressibilities. The coefficient of consolidation, cv, deter- mines the rate at which settlement will occur and is useful in predicting underconsolidation from sedimentation rates (Gibson 1958). The coefficient has a great deal of scatter but generally decreases with water content (Fig. 5-13B). The cor- relation roughly matches typical values presented pre- viously, as shown bv the diagonal line in Figure 5-13B (Lambe and Whitman 1969, p. 412; Lee and Schwab 1983). 20 Skimmkn i WaikrComfm (% dry weight) 30 40 50 40 50 60 40 50 60 Core 615 Al off Dangerous River Water depth— 23m Average water content— 26% Core 88G Yakutat area Water depth— 112m Average water content— 42% Core 633G1 Malaspina area Water depth— 221m Average water content— 48% Figure 5-12. Downcore variation in water content in three environments (data, in part, from Lee and Schwab 1983). Maximum past consolidation stress was obtained from over 100 consolidation tests using the Casagrande (1936) pro- cedure. In only 10% of the tests did the maximum past stress significantly exceed the in-place overburden stress, indicat- ing a state of overconsolidation. Of these tests, several are suspect due to high sand content. About 25% of the tests indicate that in-place overburden stress was slightly greater than the calculated maximum past stress, which implies that the consolidation of the sediment had not yet reached an equilibrium state with the overburden stress (underconsolidation). Lee and Schwab (1983) estimated areal variations in the degree of consolidation by using the sedimentation rate information of Molnia and Carlson (1980), the coefficient of consolidation data of Figure 5-13B, and the methods of Gib- son (1958). The Kayak Trough, eastern Alsek, and eastern Icy Bav-Malaspina areas were predicted to have a degree of consolidation ranging from 80 to 90%, and approaching 100% for the remaining shelf areas. The two embayment study areas (Yakutat Bay and Icy Bay) have highly undercon- solidated sediment, with an estimated degree of consolida- tion of 20 and 30% , respectively. Earlier calculations by San- grey, Clukey, and Molnia (1979) indicate higher levels of no Physical Environment A. Compression Index versus Sediment Water Content 06 04 U U 5 0.3 z 0 X 0.2 0.1 B. Coefficient of Consolidation versus Sediment Water Content 100 u z~ 0 P < a 3 <— • o ? c S U -S 1 30 40 50 60 70 Sediment Water Content (% dry weight) 80 c 6 0 u C. Effective Angle of Internal Friction versus Sediment Water Content ° 1 " fee V z* 0 w 35 30- 25 -Plasticity . Index = 10% — Plasticity Index = 15% •.. 20 30 40 50 60 70 Sediment Water Content (% dry weight) 80 E. Critical Earthquake Acceleration versus Sediment Water Content 0 3 3 0.2 <^ 2 So W j < P 5 U 01 20 25 30 35 40 45 50 55 Sediment Water Content (% dry weight) .01 20 30 40 50 60 70 Sediment Water Content (% dry weight) Ratio of Strength to Consolidation Stress for Normal Consolidation, and Cyclic Degradation Factor versus Sediment Water Content 1.2- r Q Z z c < < < c Q Z 0 p H - C u < V < z 0 — U 0 - 0 - < H / u - 0 o < rl O J u z u < 0 z 3 Bi u -i u >< 0 en U - c H u. ■< pd 0.6 0.2 AD S,, D ■ o • Yakutat study area n ■ Icy Bay — Malaspina study area — r~ 45 — I- 50 20 25 30 35 40 45 50 55 60 Sediment Water Content (% dry weight) Figure 5-13. Correlation of various engineering properties with sample water content in the northeastern Gulf of Alaska (data, in part, from Schwab and Lee 1983). Geomorphology, Sediment and Sedimentary Processes TT1 underconsolidation for most areas, but their values of cv appear anomalously low and were not included in the analy- sis (Fig. 5-13B). The fully drained shearing strength corresponding to long-term loading conditions is expressed by the effective stress friction angle, 0'. A slight correlation with water con- tent is evident (Fig. 5-13C). The measured values of 30 to 40° are representative of or slightly higher than those com- monly reported for low plasticity soils, indicated in the fig- ure by two horizontal lines for plasticity index of 10 and 15% (Lambe and Whitman 1909: p. 307). The effective stress fric- tion angles would represent the long-term (drained) angle of repose of these sedimentary deposits. Because failure is occurring on slopes of less than 1° (Carlson and Molnia 1977; Schwab and Lee 1983), long-term drained loading clearly is not a factor. Rather, more rapid and transient earthquake and storm wave loads, coupled with cyclic strength degradation resulting from excess pore-water pressure generation, must be causing failure on such gentle slopes. Lee and Schwab (1983) evaluated the undrained static shearing strength of several hundred core samples on ship- board, using a miniature laboratory vane shear apparatus. Thev found that in 10% of the samples, the static shearing strength exceeded 15 kiloPascals (kPa). By this measure, almost all of the Holocene clayey silt would be considered very soft (Terzaghi and Peck 1967: p. 30). These measure- ments are of limited value in dealing with silty sediment because of coring disturbance (Lee 1979). Indeed, four in-place vane shear tests in the northeastern Gulf of Alaska clavev silt yielded strength values about twice those of the core samples measured by Lee and Schwab (1983). A preferable way of assessing undrained shearing strength is the normalized soil parameter (NSP) approach (Ladd and Foott 1974; Lee, Edwards, and Field 1981). Such an approach not only uses triaxial test results, but partially compensates for coring disturbance and may allow extrapo- lation below the level of sampling. For the generally nor- mally consolidated Holocene clayey silt, the critical nor- malized soil parameter is the ratio of undrained strength to consolidation stress for normal consolidation, SNC. The parameter SNt- varies directly with water content (Fig. 5-13D). Because cyclic loading from earthquakes and waves probablv generates most slope failures, a cyclic strength deg- radation factor, AD, is needed to estimate the appropriate reduced strength (Lee et al. 1981). This degradation factor varies inversely with water content (Fig. 5-13D). The prod- uct of AD, SNC, and a density term determines the level of seismic acceleration, kc , needed to cause failure during an earthquake (Lee et al. 1981; Schwab and Lee 1983). A some- what more complex function determines the storm-wave height needed for failure (Schwab and Lee 1983). The criti- cal earthquake acceleration, kt, varies with water content (Fig. 5-13E) (Lee and Schwab 1983). The factor kc has a mini- mum of about ().14gr, corresponding to a critical water con- tent range of 37 to 50 percent. Lee and Schwab (1983) found that core samples from several of the major slumps have water contents predominantly in this critical range. Sedi- ment outside the slumps tends to have water content above or below the critical range. The shoreward edge of the Holocene sediment is pre- dominantly sand. Several static cone-penetration tests in the sand disclose a very dense sediment (Lee and Schwab 1983), close to the maximum value (Schmertmann 1978). Suspended Sediment. The suspended sediment in the northern and part of the north central Gulf of Alaska has been studied extensively using both satellite imagery (Reim- nitz and Carlson 1975; Sharma, Wright, Burns, and Burbank 1974) and discrete water-column measurements (Feely, Baker, Schumacher, Massoth, and Landing 1979; Feely, Mas- soth, and Landing 1981; and Landing and Feely 1981). East of Kayak Island, surface suspended-matter distribution is dominated by the discharge of sediment from the coastal streams that drain the Bering, Guyot, and Malaspina Glaciers (Fig. 5-14). Near the Copper River, plumes of highly turbid water (>2.0 mg/1 suspended sediments) extend as far as 40 km offshore. The highest concentration of suspended sediment occurs in July and August when maximum dis- charge occurs. The plume can be traced west along the coast, where a portion diverges into Prince William Sound through channels on either side of Hinchinbrook Island as well as to the southwest along the southern coast of Mon- tague Island. A strong vertical gradient of suspended sediment exists over most of the shelf. A pronounced suspended-matter minimum at about 50 m separates the surface plumes from the near-bottom nepheloid layer, which spans the bottom 50 to 80 m of the water column. In the near-bottom water, the suspended-matter distribution shows evidence for a decreasing concentration away from the coast (Fig. 5-15). Near-bottom concentration is highest south of the Copper River Delta and on either side of Kayak Island, varying between 1 and 10 mg/1. In the vicinity of the shelf break, near- bottom concentrations are generally below 0.5 mg/1. The near-bottom turbid plumes in the area east of Kayak Island are situated primarily over modern accumulations of silty clay and bear little resemblance to the surface plumes. For example, a comparison of the elemental composition of sed- iment trap and bottom sediment samples collected 30 km south of Icy Bay suggests that the near-bottom suspended matter more closely resembles the sediment than the sur- face plumes, although the number of measurements is lim- ited (Table 5-1). Embayments. Sedimentary deposits within the embay - ments in the northern Gulf of Alaska are as diverse as those on the open shelf. Seismic-reflection profiles show two dis- tinct stratigraphic units above bedrock (Fig. 5-8J). The lower unit has hummocky and discontinuous reflectors, with some parallel-bedded sequences, and the deposits have irregular morphology. The overlying unit is typified by continuous and parallel reflectors, and the deposits fill depressions in the underlying sedimentary deposits or bed- rock. The combined thickness of the two sedimentary units is commonly several tens of meters; the maximum observed thickness is greater than 200 m in Glacier Bay. 120 m in Lituya Bay, 350 m in Yakutat Bay, and 400 m in Prince William Sound (von Huene et al. 1967; Carlson, Molnia, Hampson, Post, and Atwood 1978; Carlson, Wheeler, T12 Physical Environment II. Octobkr — November 1975 145 Octobkr — November 1975 145 58 Total suspended matter*(mg/l) LIJ >2.0 I I 1.0—2.0 I I <1.0 Figure 5-14. Distribution of total suspended matter at the sea surface in the northeastern and part of the northcentral Gulf of Alaska. (Modified from Feely et al. 1979.) Molnia, and Atwood 1979; Mackiewicz, Powell, Carlson, and Molnia 1984; and Molnia 1979b). Sediment in the embayments ranges widely in grain size. In Glacier Bay, for example, coarse diamict sediment has been sampled in front of glaciers, gravel and coarse sand have been sampled near the mouth of meltwater streams, and mud with sand interbeds was found on the flat floor of the central Bay (Carlson, Wheeler, Molnia, Post, and Powell 1983; Molnia 1983; and Powell 1983). Wright (1972) collected 74 samples in Yakutat Bay. They ranged from 100% gravel on moraines to 99% mud in the central basin. 58 Total suspended matter (mg/1) f □ >2.0 I I 1.0—2.0 I I Feely, Massoth. and Landing (1981) c Burrell (1977) d Landing and Feely (1981) Glacial deposits include the muddy gravel exposed at the sea floor on the bathvmetric highs and at the edge of the shelf. These deposits are relict (Quinterno et al. 1980) and till-like, similar to those mapped by Miller (1953) on Mid- dleton Island. Similar muddv conglomerate occurs onshore in the Yakataga Formation (Plafker and Addicott 1976). This coarse debris offshore probably was deposited during the Pleistocene when lobes of the massive piedmont glaciers extended seaward. The resulting pebbly or gravelly mud (diamicton) makes up a significant part of the sea-floor sedi- ment on Tarr Bank, Middleton Island platform, and Pam- plona Spur. The uplifting of these positive relief features and the winnowing action of waves and currents have kept the diamicton from being covered by the fine sediment being deposited elsewhere on the shelf. The modern sediment on the shelf is principally clayey silt, derived from glaciers and transported bv meltwater streams (Molnia and Carlson 1980). The four main sources of Holocene sediment are the Copper River, which annually supplies 97 x 106 mt of detritus (Reimnitz 1966), the Alsek River, which cuts through the St. Elias Mountains to drain part of Yukon Territory, and the two large piedmont glaciers, Bering and Malaspina. Sediment from the two glaciers is at present primarily transported as suspended matter, the plumes of which easily can be detected more than 30 km from shore using satellite imagery (Reimnitz and Carlson 1975). The similarity between the elemental com- position of the one sample of Copper River suspended mat- ter and the samples of nearshore suspended matter (Table 5-1) supports the notion that this river is a major source of sediment. A secondary but significant source of fine sediment is wind. For example, in the fall of the year it often blows down the Copper River gorge with sufficient force to pick up sedi- ment from the flood plain and carry dark clouds of silt as much as 40 to 50 km offshore (Carlson, Molnia, and Reim- nitz 1976; Post 1976; and Swift, Molnia, and Jackson 1978). The sediment, whether transported by rivers, glaciers, or wind, is subject to the rigors of the nearshore currents (Alaska Coastal Current System) that primarily move in a westward direction, similar to the offshore Alaska Stream (Reimnitz and Carlson 1975). Much of the Copper River sed- iment is being carried into Prince William Sound through channels to the north and south of Hinchinbrook Island (Burbank 1974; Carlson and Molnia 1978). Sediment con- tained in the Bering, Guyot, and Malaspina Glacier runoff plumes is carried along the coast until it reaches Kayak Island, where it is deflected offshore. Complex gyres of tur- bid water have been seen on both sides of Kayak Island on satellite imagery (Burbank 1974; Reimnitz and Carlson 1975). Occasionally, counterclockwise eddies form in the nearshore region between Yakutat Bay and Kayak Island. These eddies transport terrigenous material as much as 50 km offshore. Similarly, a clockwise gyre due west of Kayak Island transports a significant amount of suspended sedi- ment to the southwest, past the outer edge of the shelf. Con- servative estimates suggest that 3,000 to 24,000 mt of ter- rigenous sediment are transported offshore daily when the gyre is positioned near Kayak Island (Feely et al. 1979). The near-bottom turbid plumes of sediment on the shelf might be derived partly by resuspension of the underlying fine sediment, as has been documented on the United States east coast shelf (Meade, Sachs, Manheim, Hathaway, and Spencer 1975; Biscaye and Olsen 1976). This is supported by the resemblance of the elemental composition of sediment trap samples to the sea-floor sediment (Table 5-1) and the existence of near-bottom plumes over modern accumula- tions of silty clay. TM Physical Environment High-resolution seismic profiles, sea-floor television images, and bottom samples indicate that little of the sus- pended matter from either the Copper River or from sources east of Kayak Island accumulates on Tarr Bank or on the Middleton Island platform (Carlson, Molnia, and Levy 1980). The lack of sediment on these topographic highs probablv is due to the scouring action of the large and force- ful storm waves that are particularly frequent during the winter season of intense low pressure activity in the Gulf of Alaska (Wilson and Overland, Ch. 2, this volume). The high sand content in the entrance between Hinchinbrook and Montague Islands (10-15%), and between Hinchinbrook Island and the mainland to the east (>50%), is related to the transport of sand from the Copper River along shore and into Prince William Sound (Carlson et al. 1977). Tidal action in the entrance probably winnows the fines from this sandy sediment. Further evidence of sedi- ment transport into Prince William Sound is provided by a wedge of Holocene sediment building into the Sound (Carl- son and Molnia 1978) and plumes of suspended matter that extend into the Sound (Reimnitz and Carlson 1975; Sharma et al. 1974). Clay-sized sediment is not so prevalent on the north- eastern Gulf of Alaska shelf as it is on shelves in many other parts of the world. The primary reason for this deficiency is that the source sediment is largely glacial flour, which is dominated by the silt fraction. In addition, the high wave energy in this dynamic environment may keep the clay in suspension and aid its transport off the shelf into abyssal depths. However, in some bays the energy is low enough to allow the clay-sized fraction to settle out of suspension. For example, Wright (1972) reported that sediment from parts of Yakutat Bay contains up to 85% clay-sized particles. The rate of modern sediment accumulation, based on 210Pb analyses of samples from two box cores, ranges from 17 mm/y for mud on the inner shelf near the Copper River pro- delta to 2 mm/y for sediment on the outer shelf near Mid- dleton Island (Charles Holmes, U.S. Geological Survey, pers. comm., 1977). The Holocene sediment east of the Copper River is 150 to 200 m thick on the inner shelf and has been accumulating for about 10,000 years. The calculated rate of accumulation is 15 to 20 mm/y, equivalent to that obtained with the 210Pb technique (Carlson et al. 1977; Molnia et al. 1980). Sedimentation rates at the mouth of Prince William Sound exceed 18 mm/y. Other areas of high sedimentation are south of Icy Bay ( > 20 mm/y) and south of Bering Glacier (> 14 mm/y), areas that receive large quantities of locally pro- duced glacial sediment. The sediment accumulation rates for the shelf sediment range from 0 to more than 28 mm/y, and the average rate is 4.5 mm/y (Molnia et al. 1980). The sediment failures on the open shelf occur on slopes that are too gentle to have been caused solely by static grav- itational force, according to a geotechnical analysis by Lee and Schwab (1983). Instead, a repeated-loading mechanism, such as earthquakes or water waves, is more probable. Val- ues of the critical acceleration factor, kc, indicate that sedi- ment characterized by water content in the range of 37 to 50% is most susceptible to failure, and indeed, samples from some of the known failure areas contain more sedi- ment with water content in this range than do samples from adjacent areas. Further analysis by Schwab and Lee (1983) differentiated locations that would be subject to earthquake-induced failure from those that would tend toward storm-wave- induced failure. Shallower areas that are more likely to experience failure due to storm waves were separated by 35 to 75 m of water depth from the deeper areas where earth- quakes are more likely to initiate failures. Only the Alsek study area contains significant clayey silt (water content greater than —32% and therefore relatively susceptible to failure) in water depth less than 75 m (Fig. 5-12). Likewise, only the Alsek study area contains intricate mudflows and channels (Molnia and Rappeport 1980, 1984). Failures in the other study areas are more typically rotational slumps. The unique morphology of these Alsek failures is likely related to storm-wave initiation. The longer duration of major storms allows pore water movement, partial fluidization of the silty sediment, and flow over a considerable distance. The high relative density indicated by the static cone- penetration tests in the sandy sediment at the shoreward edge of the Holocene sediment implies little likelihood of failure under either earthquake or wave loading. In fact, the scarps at the head of the Icy Bay-Malaspina slump (Carlson 1978) probably correspond to the boundary between stable sand and less stable clayey silt. There appears to be no correlation between the occur- rence of acoustic anomalies and the locations of sampled gas-charged sediment, except for the sediment off Kayak Island. Whether gas accumulation, the development of high pore pressure, and the subsequent degradation of sediment shearing strength is a significant factor in causing sediment failure on the northeastern Gulf of Alaska shelf is unknown. However, the extent of observed gas charging certainly is much less than the extent of mass instability. Repeated load- ing-strength degradation in the glacial silt deposits (Fig. 5-13D) is a more likely explanation for the widespread occurrence of sediment failures. The coastal and nearshore zones comprise a variety of sedimentary environments. Hayes and Ruby (1977) divided the coastline between the Alsek River and Prince William Sound into three major classes: depositional (19%), ero- sional (23%), and neutral (58%). Examples of depositional shorelines are the barrier islands of the Copper River Delta and smaller deltas and spits within Yakutat and Icy Bays. The most dramatic erosion of shoreline has occurred both northwest and southeast of Icy Bay (Boothroyd, Cable, and Levy 1976; Molnia 1977). The shoreline northwest of Icy Bay has retreated 4.8 km since 1922, and the southeast shoreline along the Malaspina foreland has receded about 1.3 km since 1941 (Molnia 1977). The moderately well-sorted sand deposits of the nearshore zone reflect a dynamic environ- ment. Storm waves and alongshore currents resuspend or keep the fine particles in suspension, and offshore currents transport them westward. The embayments in the northeastern Gulf of Alaska have similar sedimentation histories, although the timing and rates differ (Molnia 1979b). Glacial scour produced a rough and channeled bedrock surface, and moraines and other Ceomorpholocy, Sediment and Sedimentary Processes T15 irregular to chaotic deposits of glacial sediment have accu- mulated (/>., the lower stratigraphic unit observed in seis- mic-reflection profiles; see Fig. 5-8J). After ice retreat, the modern regime includes copious input of glacial rock flour transported by mcltwater streams (i.e., the upper strat- igraphic unit in Fig. 5-8J) and some direct ice deposition at the terminus of tidewater glaciers (von Huene et al. 1976; Molnia 1983). Minor ice rafting continues. Ice retreat from Icy Bay occurred as recently as 80 years ago (TaiT and Martin 1914; Molnia 1977). In Glacier Bay, ice retreat from the open bay began 200 years ago, but glaciers still remain in marginal fjords where the retreat history has been well documented (American Geographical Society 1966; Garlson, Wheeler, Molnia, and Atwood 1979). Mor- aines left by the retreating ice serve as barriers to the disper- sal of bed-load outwash material, and thick sedimentary deposits have been observed behind them (Garlson et al. 1983; Molnia, Atwood, Carlson, Post, and Vath 1984). The meltwater streams are laden with rock flour; Powell (1983) measured a suspended-sediment concentration greater than 23 g/1 in streams that flow into Glacier Bay, and a suspended load concentration of greater than 1 g/1 has been measured in the Bay itself (Hoskin and Burrell 1972). Consequently, the sediment accumulation rate is high. Max- imum measured values are 4 cm/y in Taylor Bay (Cross Sound) to more than 400 cm/y in Muir Inlet (Glacier Bay) (Molnia 1979b; Carlson, Wheeler, Molnia, and Atwood 1979; and Molnia et al. 1984). Sangrey et al. (1979) and Molnia (1979b) measured an accumulation rate of 140 cm/y in Icy Bay, indicating a highly underconsolidated sediment. Turbidity currents and other sediment-gravity-flow processes occur frequently in the bays and inlets. Diamicton deposits near the terminus of glaciers have been interpreted as debris-flow (Powell 1980, 1983), whereas the coarse sand layers cored farther from land have been interpreted as tur- bidity-current deposits (Mackiewicz et al. 1984). Von Huene et al. (1976) detected many buried slump deposits in Nuka Bay, a fjord in the northern Gulf of Alaska, and attributed their presence to a mass sediment failure from material that was originally deposited on the steep fjord walls. Enormous earthquake-generated rockslides following a magnitude 7.9 event in 1958 deposited a significant amount of sediment in Lituya Bay. One rockslide involved 31 x 106 m3, and a survey in the Bay showed that some channels received up to 79 m of fill (Miller 1960; Jordan 1962). Sediment slides were also triggered by the Great Alaskan Earthquake of 1964, in particular on the outwash fan and delta at Port Valdez in Prince William Sound (Coulter and Migliaccio 1966) and in Resurrection Bay (Lemke 1967). The slide at Port Valdez involved about 7.5 x 10" m3 of uncon- solidated gravel, plus disseminated silt and sand beds that compose the delta. A seismic-reflection profile shows that the toe of the slide now rests in 230 m of water, and the deposit is 40 m thick at its up-slope end and about 5 m thick at the toe (Carlson and Molnia 1978). The south side of the Port Valdez area was investigated geotechnically by Singh and Quigley (1983). Cyclic triaxial tests of a rock-flour deposit, the 'Valdez silt', disclosed a cyclic loading response nearly identical to that of the most vulnerable sediment on the continental shelf. However, the slopes in Port Valdez are much greater than those on the shelf, ranging up to 26° (Pal- mer 1981). In a stability analysis, Singh and Quigley (1983) found that even the mild wave environment (maximum wave height of 3 m) of Port Valdez could cause a fairly deep (4 m) failure in the silt. Also, much of the silt is highly suscep- tible to failure during an earthquake. In Resurrection Bay, a slide mass 15 to 120 m wide, along with docks and harbor facilities, moved into the Bay as a consequence of the 1964 earthquake. Submarine slopes are now steeper in some places than before the sliding occurred, implying the likelihood of failure during future large seismic events. Kodiak Shelf Geomorphology General. The geomorphology of the Kodiak Shelf con- sists of a series of banks, generally 50 to 100 m deep, cut by transverse troughs up to 300 m deep. The banks are flat and dip gently seaward over broad areas, although many low hills and shallow depressions do exist (Turner, Thrasher, Shearer, and Holden 1979; Dunlavey, Childs, and von Huene 1980). Closed depressions also exist in the troughs. The sea floor is nearly horizontal on most parts of the banks and rarely exceeds 2° inclination on the flanks of troughs (Hampton 1983a). A notable exception is Sitkinak Trough, where the gradient reaches 10 degrees. The upper continen- tal slope is also relatively steep, with typical gradients between 5 and 20 degrees. Troughs on the Kodiak Shelf are similar to the troughs in the northeastern Gulf of Alaska. They have a broad, U-shaped cross section and contain closed depressions on the trough floor. Anticlinal folding in bedrock has uplifted the sea floor to form sills near the mouths of Kiliuda, Chiniak, and Stevenson troughs and across the mid-portion of Amatuli Trough. The sill in Stevenson Trough is deeply breached in two places; the other sills are breached to shal- lower levels. The anticlines also have sea-floor expression on the banks. They have relief of more than 60 m in places and have been eroded to expose bedrock. The series of anti- clines that forms the sill across both Kiliuda and Chiniak troughs forms a ridge parallel to and near the shelf break of southern and middle Albatross Bank. The ridge extends landward adjacent to the southwest edge of Chiniak Trough. A similar ridge exists near the shelf break of Port- lock Bank; it extends landward, along the northeast side of Stevenson Trough. Other uplifted exposures of bedrock occur on the banks (von Huene, Hampton, Fisher, Varchol, and Cochrane 1980) (Fig. 5-4). The bedrock is middle or late Miocene to Pleistocene age (McClellan et al. 1980). The morphology of the troughs has been modified by sedimentation. Sediment eroded from the banks has been deposited as inclined strata that prograde laterally into the sides of the troughs, significantly narrowing them (Fig. 5-16A). The floor of the troughs is aggrading from the ongoing sediment deposition. The sill across the troughs is ri6 Physical Environment ["wo- Way Travel Time (s) Two- Way Travel Time (s) '"II1 E o -, Two- Wav Travel Time (s) Two- Way Travel Time (s) Two- Way Travel Time (s) < sS - CU 0, c - o 53 7J c CU s- G u c (X o M CJ 3 s- CU H o- a. o 3 0 CU 53 1 -C cfl c 100m) Sand waves Sand waves with superimposed bedforms Sand bands 152 \\\\ Sand ribbons Wt Comet marks •••:: Boulders cO> Flat field, little relief — ► Bedform orientation refiecting net current flow- Figure 5-19. Distribution of bedforms in lower Cook. Inlet. (Modified from Orlando 1984.) The sea floor in the central part of lower Cook Inlet is covered by a variety of bedforms (Fig. 5-19). Numerous pub- lications have reported on the classification, morphology, distribution, and dynamics of these features (e.g., Bouma, Hampton, and Orlando 1977; Bouma, Hampton, Wen- nekens, and Dygas 1977; Bouma, Hampton, Frost, Torresan, Orlando, and Whitney 1978; Bouma, Hampton, Rappeport, Whitney, Telaki, Orlando, and Torresan 1978; Bouma, Rap- peport, Gacchione, Drake, Garrison, Hampton, and Orlando 1979; Bouma, Rappeport, Orlando, and Hampton 1980; Whitney, Noonan, Bouma, and Hampton 1980; Mahmood, Ehlers, and Cilweck 1981; Rappeport 1981; and Orlando 1984). Listed below are descriptions of the major bedform types that have been observed in lower Cook Inlet (Orlando 1984): Sand waves (Fig. 5-20A) are wavy accumulations of sand with a straight or sinuous crest oriented perpendicularly to current flow. Wave height ranges to 14 m in lower Cook Inlet 122 Physical Environment Horizontal Scale (m) c i- U 3 u -o c o c JO o c T5 1- «J ffl "0 J3 >. (4-1 o o 1- rt I-. t) < •- a tn c n x x 0 0 ^ « I 12 S « X! a. ^ 2 00 C en o i— CO -a Q a O x; a, a t* bb - 0 a o o £ y: Cu W fe -a c Rl C/3 TJ 1! o a x: 3 H u bo s o m o £ x - o, -S | g Q- > a z o 5 o o a. -5 a. I co fee o c o CO < CQ U go Geomorpholocy, Sediment and Sedimentary Processes 123 and wave length ranges to 950 meters. Sand waves are fur- ther classified as small (wave length < 20 m), medium (wave length 20-100 m), and large (wave length > 100 m). Length- to-height ratio typically exceeds 20 to 1, but a ratio as low as 10 to 1 has been reported (Rappeport 1981). Small and medium sand waves can be superimposed on large sand waves and other bedforms such as sand ribbons. Ripples (Fig. 5-20B) are small wavy forms in sand with heights less than 10 cm and wave lengths less than 20 cen- timeters. These small bedforms are detectable only with photographic or television systems. Sand bands (Fig. 5-20C) are Fields of sand waves elongate in the direction of flow and relatively sharply bounded by fields of other sand waves of different size. A sand band may be straight and have parallel sides, but it also can bifurcate. Sand ribbons (Fig. 5-20D) are narrow, typically thin ( < 1 m), current-parallel bodies of sand overlying hard bottom (see below). Sand within a ribbon commonly is formed into small, transverse- to oblique-trending sand waves. Comet marks (Fig. 5-20E) are scour depressions extending down-current from obstructions to flow, such as large boulders. Hard bottom (Fig. 5-20F) is more-or-less flat sea floor cov- ered with a gravel pavement. Sediment Stratigraphy and General Distribution. The nature of the sediment on the sea floor of Cook Inlet is known from samples collected throughout the entire area (Sharma and Burrell 1970; Hampton 1982a). However, the features of the sedimentary units beneath the sea floor and above the regional unconformity are known only for lower Cook Inlet, where extensive seismic-reflection profiling has been done (Rappeport 1981). Four seismic-stratigraphic units were identified in seis- mic-reflection profiles throughout lower Cook Inlet by Rappeport (1981): 1 ) The first (and lowest) unit is 75 m thick and is charac- terized by irregular and discontinuous reflectors. It was interpreted to be composed of unsorted glacial debris such as ground moraine. 2) The second unit is thin (<3 m) with a strong reflector at the lower boundary but with no other internal reflectors, and is interpreted to be a layer of outwash. 3) The third unit (up to 20 m thick) has large sand waves, both at the sea floor and buried beneath it. The sedi- ment type is well-sorted sand with some shells, and occurs in areas of high-energy currents. 4) The fourth (uppermost) unit is up to 75 m thick, has well defined, continuous reflectors and was inter- preted as glacial-marine, glacial-fluvial, or glacial-lacustrine deposits. Rappeport (1981) did not map the distribution of these units. Texture and Composition. The coarsest sediment in Cook Inlet is in the area of the Forelands, where gravelly deposits occur that include boulders up to a few meters in size (Ceopfert 1969). The grain size decreases in both direc- tions away from there. The sediment grades to sand that generally is fine-grained and well sorted in upper Cook Inlet (Sharma and Burrell 1970). South of the Forelands, in lower Cook Inlet, sand- and gravel-sized material is domi- nant (Bouma and Hampton 1976; Orlando and Martin 1981; and Hampton 1982a). Mean grain size generally decreases from north to south and shows certain associa- tions with bathymetry and physiography. The most abun- dant size class is sand (0.0625-2 mm). Sediment covering the central area, including the trough and the ramp, contains more than 80% sand-sized grains. The greatest amount of gravel-sized sediment ( >2 mm) occurs to the north, toward the Forelands. Mud-sized material (< 0.0625 mm) occurs largely to the south, particularly in the deep water south of the ramp and along the Inlet's borders. The textural classification map (Fig. 5-5) indicates that gravel with mud (gravelly mud, muddy sandy gravel, and gravelly muddy sand) blankets the borders of the Inlet. Sand with gravel (gravel, sandy gravel, and gravelly sand) occurs in the central area. Sand is found in and flanking the central trough and on the ramp. Silty sand was sampled at a few scat- tered locations, and sandy silt occurs in the deep water south of the ramp, along with some sand and gravelly sand. Sediment along the coast of lower Cook Inlet has a wide range of grain size (Hayes and Michel 1982). Most beach sedi- ment is a mixture of sand and gravel, but clasts up to several meters in size lie at the base of erosional scarps, whereas fine sand and silt occur on low-energy tidal flats. The sand grains in lower Cook Inlet contain an abun- dance of microtextural features that are interpreted to be of glacial origin (Hampton, Bouma, Torresan, and Colburn 1978). These features either occur alone or are overprinted by inferred chemical and mechanical-impact features. Grains that exhibit glacial features are most common in the northern areas, while those exhibiting mechanical-impact features are most common in the central area of large wavy bedforms where high-energy bed-load transport occurs. Those grains exhibiting chemical features are dominant in southern areas and in protected areas around the edge of the Inlet, where current energy is relatively low. Suspended Sediment. The distribution, the elemental composition, and the sedimentation patterns of suspended sediment in Cook Inlet have all been described using a vari- ety of techniques, including: 1) satellite studies (Sharma et al. 1974; Gatto 1976; and Burbank 1977); 2) water-column proc- ess studies (Feely, Massoth, Paulson, Lamb, and Martin 1981; Feely and Massoth 1982; and Feely, Chester, Paulson, and Larrance 1982); and 3) sediment studies (Sharma and Bur- rell 1970; Bouma and Hampton 1976; Hein et al 1979; and Atlas, Venkatesan, Kaplan, Feely, Griffiths, and Morita 1983). Hein etal. (1979) identified two end-member suites of clay minerals in one lower Cook Inlet sea-floor sediment. One suite is relatively rich in chlorite + kaolinite and the other is rich in illite. The former occurs in northern and western areas and is derived from rivers at the head of Cook Inlet, whereas the latter occurs in eastern and southern areas and is derived from the Copper River. 124 Physical Environment The suspended material from upper and western Cook Inlet has nearly the same elemental composition as the sus- pended sediment from the Susitna, Knik, and Matanuska Rivers that enter the head of Cook Inlet (Table 5-3). This is especially true for the major rock-forming elements (Al, K, Ti, and Fe), which are primarily associated with aluminosili- cate minerals of terrestrial origin (Price and Calvert 1973). The distribution of suspended matter throughout the water column is characterized by horizontal gradients that reflect both the estuarine and the embayment charac- teristics of the flow patterns in lower Cook Inlet (Fig. 5-21). On the eastern side of the Inlet, the concentration of sus- pended matter is relatively low, ranging from 0.5 mg/1 near the tip of the Kenai Peninsula to about 5 mg/1 off Cape Ninilchik. On the western side of the Inlet, the water proper- ties are characterized by low salinity and very high suspen- ded-matter concentrations that range to more than 50 mg/1 just north of Tuxedni Bay. Throughout most of this region the water column is virtually unstratified, and tidal currents are sufficiently high to resuspend almost all fine-grained sediment (Fig. 5-22). Sedimentary Processes The Cook Inlet sedimentary environment is charac- terized by strong tidal currents and sediment reworking. The Susitna, Knik, and Matanuska Rivers at the head of the Inlet provide a large supply of sediment, much of which travels in suspension and bypasses the Inlet entirely. Sand-sized grains from these sources, however, settle to the sea floor within about 25 km of the head of the Inlet (Sharma and Burrell 1970). The gravelly sediment farther south and extending past the Forelands appears to be winnowed relict glacial mate- rial. The dominantly glacial microtextures on sand-grain surfaces support this idea. The currents are strong in this area because the Inlet is narrow and the net circulation is south. Therefore, most of the winnowed sediment moves into lower Cook Inlet where the coarser sand-sized grains are deposited in the central area of large sand waves (Fig. 5-19). Reflectors beneath the arcuate ramp incline to the south, attesting both to the net southerly transport of bed- load sand and to the southerly progradation of this sedi- ment body (Hampton et al. 1978). Sand grains from the area Table 5-3. Averaged 1977-1978 chemical composition data (expressed as weight %, ± la) and elemental ratios for surface suspended-matter samples from selected regions in Cook Inlet and Shelikof Strait (data from Feely and Massoth 1982). Number Estimated Region OF Biogenic alumino- Samples Mg Al Si K Ca Ti Fe Si SLliCATE Susitna-Knik- Matanuska River 13 3.73 10.39 33.41 2.26 1.98 0.607 6.39 0.00 104 Systems ±0.61 ±2.03 ±3.42 ±0.63 ±0.58 ±0.059 ±0.40 Kalgin Island-upper 9 3.05 8.59 28.57 1.95 1.73 0.505 5.33 0.94 86 Cook Inlet ±0.61 ±1.91 ±6.05 ±0.38 ±0.38 ±0.085 ±0.90 Kamishak Bay 5 3.69 9.84 34.82 2.09 1.77 0.483 5.31 3.15 98 ±0.59 ±1.66 ±3.76 ±0.36 ±0.25 ±0.084 ±0.79 Kachemak Bay 6 2.15 4.85 30.38 0.81 1.74 0.287 2.95 14.75 49 ±1.02 ±2.78 ±8.72 ±0.53 ±0.95 ±0.159 ±1.68 Kennedy-Stevenson 9 1.68 3.91 27.82 0.65 1.36 0.205 2.03 15.24 39 Entrances ±1.11 ±2.55 ±5.48 ±5.48 ±0.48 ±0.55 ±0.126 ±1.58 NW Shelikof Strait 6 2.98 7.02 33.46 1.32 1.71 0.353 3.64 10.87 70 ±0.73 ±2.14 ±4.01 ±0.47 ±0.55 ±0.118 ±1.32 Copper River 5 4.65 9.25 27.91 1.78 4.42 0.638 6.70 0.00 93 ±0.17 ±0.19 ±0.54 ±0.03 ±0.09 ±0.013 ±0.16 Region Mg/Al Si/Al K/Al Ca/Al Ti/Al Fe/Al K/Ca Susitna-Matanuska- Knik River System Kalgin Island-upper Cook Inlet Kamishak Bay Kachemak Bay Kennedy-Stevenson Entrances NW Shelikof Strait Copper River 0.359 3.22 0.218 0.191 0.058 0.615 1.14 0.355 3.33 0.218 0.201 0.059 0.621 1.13 0.375 3.54 0.212 0.182 0.049 0.540 1.17 0.443 6.26 0.167 0.359 0.059 0.608 0.47 0.430 7.12 0.166 0.348 0.052 0.519 0.48 0.424 4.77 0.188 0.244 0.050 0.519 0.77 0.503 3.01 0.192 0.478 0.069 0.724 0.40 NOTE: Excess (biogenic) Si% was determined relative toSusitna-Knik-Matanuska River System Si/Al value of 3.22. Estimated aluminosilicate % values were obtained by multiplication of respective regional Al% by 10 (after Sackett and Arrhenius 1962). Ceomorpholocy, Sediment and Sedimentary Processes 125 Total suspended matter (mg/l) ■I >;>o.i) I I 5.0— .">().() I I 1.0—5.0 I I <1.0 W Trinity Is. 56 154 152 150 Figure 5-21. Distribution of total suspended matter in surface water of lower Cook. Inlet and Shelikof Strait. 4 to 16 April 1977. (Modified from Feely and Massoth 1982.) show abundant abrasional microtextural features acquired during this transport. Southerly transport is further indi- cated by the asymmetry of the large sand waves; the steep side of most waves faces south (Bouma, Hampton, and Orlando 1977; Orlando 1984). Rappeport (1981) analyzed current velocities recorded over a three-month period in lower Cook Inlet during the summer of 1978. He reported that currents reached their maximum speed in the ebb direction. Also, current speeds near the sea floor were greatest at the crest of a large sand wave compared to speeds near the trough. Currents exceeded the theoretical threshold velocity necessary to ini- tiate sediment transport about 35% of the time. This fact was supported by television observations made at the start of the study period, which showed that sediment movement took place only during 1 to 1.5 hours around peak ebb and flood currents (Bouma et al. 1979). Rappeport (1981) also calculated sediment transport rates and deduced that the largest sand waves might migrate only 30 to 40 cm/y, which equals one wave length every 500 to 600 years. This slow rate was corroborated in a study by Whitney et al. (1979), which compared sand-wave positions on side- scan sonographs taken four years apart over coincident tracklines. No net movement greater than 10 m (the preci- sion of the comparison) could be detected. Two alternative conclusions can be drayvn from these studies: 1) the sand waves are virtually inactive under the present hydraulic regime and their morphology is relict from a lower position of sea level, or 2) they move more today during periods of extreme current conditions, such as during large storms or spring runoff, but move at a slow rate that cannot be observed over a short period of years. The protected areas around the boundaries of lower Cook Inlet have a relatively low sedimentation rate, and mud is deposited where the sea floor evidently is shielded from intense currents even though the water depth is shal- low. Mud is also deposited in deeper areas south of the rani p where there is a higher sedimentation rate. Sand grains in these environments typically show chemically induced microtextures. A relatively low sediment accumulation rate is inferred in areas where glacial debris is still exposed on the sea floor (e.g., gravelly mud, muddy sandy gravel, and gravelly muddy sand, Fig. 5-5). Higher accumulation rates are inferred yvhere the glacial debris has been completely covered by a blanket of sediment. This sediment is made up of material in which the coarsest size grade is sand (e.g., silty sand and sandy silt, Fig. 5-5). A few geological studies have been conducted in coastal areas of Cook Inlet. Hayes, Michel, and Brown (1977) classi- fied 1,216 km of the lower Cook Inlet coastline into three cat- egories: 1) erosional (45%), 2) neutral (38%), and 3) deposi- tional (17%). They conducted their studies as part of an effort to evaluate the oil-spill vulnerability of the coastal environments. Rocky headlands and other areas where there is evidence of coastal retreat were classified as ero- sional shorelines. Embayments that are backed by moun- tains or hills were classified as neutral shorelines. Deposi- tional shorelines included spits, deltas, and bayhead zones. Distance From Western Shore of Kamishak Bay (km) Distance From Western Shore of Kamishak Bay (km) 0 50 100 150 154°,2'w Stations ,50°59'w ,54°,2'w Stations 29 28 27 26 25 2i 29 26 27 26 25 24 I1 j A. Salinity (°/oo) B. Temperati re (C) C. SlGMA-t Total Si spended Mai (mg/1) Figure 5-22. Vertical cross sections of salinity, temperature, density, and total suspended matter for six stations between Kamishak and Kachemak Bays in lower Cook Inlet. 4 to 16 April 1977. (Modified from Feely and Massoth 1982.) 126 Physical Environment Hayes and Michel (1982) concluded that sedimentation along depositionaJ shorelines in lower Cook Inlet is related to the tectonic setting. High-gradient streams deliver abun- dant heterogeneous mixtures of sediment from actively ris- ing, glaciated mountains northwest and southeast of the Inlet. Wave action is the most important process in shaping sedimentary deposits along the shoreline. Lobate fan deltas form where sediment-laden streams empty along sections of coast that are exposed to high wave energy. Arcuate- cuspate deltas form where similar streams enter areas of low wave energy. The effects of the large tidal range are not evi- dent in the deposits of coarse-grained coastal sediment. Recurved and cuspate spits build along a few sections of shoreline where coarse sediment extends into deeper water. Jordan (1962) analyzed repeated bathymetric surveys of the surface of a tidal flat near Anchorage. The studies were conducted from 1910 to 1959 and showed that significant net erosion and a 2.8-km retreat of the tidal flat occurred dur- ing that period. Tidal scour was proposed as a possible rea- son for the retreat, but earthquake-triggered slumping was mentioned as an alternative possibility. The major controlling forces affecting suspended-mat- ter distribution and transport in the Inlet are the strong semidiurnal tidal currents. These currents are augmented by estuarine and embayment circulation patterns. Clear, saline water transports chlorite-rich aluminosilicate mate- rial and biogenic matter from the Gulf of Alaska into the mouth of the Inlet along the east coast. Part of the material settles to the bottom in outer Kachemak Bay, and the rest is transported across the Inlet and eventually mixes with the outflowing turbid water (Fig. 5-21). The outflowing estuarine water that originates in upper Cook Inlet carries a large amount of suspended sediment and flows south along the west coast. The horizontal concentration gradient in this region is primarily due to dilution of the turbid estuarine water by the relatively clean oceanic water from the Gulf of Alaska. Some of the sediment settles out in the Kamishak Bay region, and the remainder is transported past Cape Douglas into Shelikof Strait. The elemental data for the suspended material provide more detailed information about the principal sources of suspended material in the Inlet (Table 5-4). The high con- centration of the major rock-forming elements indicates that aluminosilicate minerals are the predominant phases in suspension, ranging from —50% in outer Kachemak Bay to 98% in Kamishak Bay. The remaining material consists of organic material and biogenic tests of microscopic organ- isms. Furthermore, the K/Ca and Ca/Al ratios in the sus- pended matter provide further evidence that the Susitna- Knik-Matanuska River system is the principal source of the illite— rich aluminosilicate material in the Kalgin Island and Kamishak Bay regions, whereas the Copper River is the pri- mary source of the aluminosilicate fraction in the sus- pended matter in the regions of Kennedy Entrance and outer Kachemak Bay. Shelikof Strait Geomorphology The trough at the mouth of Cook Inlet continues into the parallel-sided Shelikof Strait (Fig. 5-2). The Strait itself is 200 km long and 50 km wide. The coastline on both sides of the Strait is indented with silled fjords. Adjacent to land are shallow (<50 m) shelves. Seaward, the sea floor slopes at between 1 and 4° to the bottom of the central trough. The trough is 30 to 35 km wide. It extends the entire length of the Strait and then curves across the continental shelf to the shelf break west of Chirikof Island (Fig. 5-2). Morphologically, the floor of the trough consists of a plat- Table 5-4. Summary of the elemental composition of particulate matter from lower Cook Inlet and Shelikof Strait (R/V Acona-245, 28 June-12 July 1977). Precision is given at the 1 o level (from Feely, Massoth, Paulson, Lamb, and Martin 1981). Element C (wt%) N (wt%) Mr (wt%) Al (wt%) Si (wt%) K (wt%) Ca (wt%) Ti (wt%) Cr (ppm) Mn (ppm) Fe (wt%) Ni (ppm) Cu (ppm) Zn (ppm) Pb (ppm) Lower Cook Inlet Shelikof Strait Average OF 51 Average of 1 6 Average of 50 Samples i FROM 5 m Average of 17 Samples from 5 m Surface Samples Above the ] Bottom Surface Samples Above the Bottom 10.77 ± 11.0 6.18 ± 9.10 31.17 ± 11.2 8.40 ± 5.8 1.98 ± 2.0 0.99 ± 1.4 4.89 ± 1.5 1.24 ± 0.8 2.86 ± 1.41 3.59 ± 0.82 1.89 ± 0.91 4.01 ± 1.22 6.98 ± 4.24 8.88 ± 2.34 3.72 ± 2.46 9.49 ± 1.22 35.75 ± 5.56 38.09 ± 4.92 28.67 + 10.10 44.71 ± 3.60 1.86 ± 0.86 2.24 ± 0.45 0.89 ± 0.43 2.19 ± 0.63 1.84 ± 0.63 2.23 ± 0.32 1.54 ± 0.35 2.08 ± 0.33 0.46 ± 0.20 0.58 ± 0.10 0.27 ± .09 0.53 ± 0.12 99 ± 30 115 ± 24 75 ± 36 116 ± 29 1138 ± 574 1460 ± 362 981 ± 709 4174 ± 7642 5.14 ± 2.11 6.50 ± 0.95 3.15 ± 1.14 6.39 ± 1.71 70 ± 25 81 ± 16 59 ± 19 77 ± 13 99 ± 33 100 ± 31 94 ± 27 112 ± 30 352 ± 158 343 ± 194 — — 65 ± 19 69 ± 13 60 ± 10 76 ± 22 Geomorpholocy, Sediment and Sedimentary Processes 127 form bordered by marginal channels. The platform is gener- ally smooth and is gently inclined from 160 m at the north- east end of the Strait to 200 m at the southwest end. Two areas of major escarpments rise from the platform in the vicinity of 58°45'N, 153°00'W and 58°28'N, 153°28'W (Figs. 5-6 and 5-23A), with maximum sea-floor offset in excess of 100 meters. Both escarpments have a depression (moat) with a relief of 20 to 40 m adjacent to their southeast side. The marginal channels are up to 300 m deep and have closed depressions. The southeast marginal channel extends the entire length of the Strait, whereas the north- west channel begins about 60 km down the Strait. Bedforms and other small topographic features cover a limited area of the sea floor within the Strait. Only a single occurrence of small sand waves, covering an area less than 0.02 km2, appears in side-scan sonographs. Comet marks, continuous with those in lower Cook Inlet, occur at the head of the Strait and trend southwest down the Strait. A few boulders, with no associated comet marks, appear in side- scan sonographs. Circular depressions (pockmarks), typ- ically 50 m in diameter and 5 m deep, are dispersed over an area of 1,500 km'-' on the southwest part of the central platform. Other than the features mentioned above, the sea floor of Shelikof Strait is remarkably smooth. Fields of the large wavy bedforms that exist in other areas of the Gulf of Alaska are not present here. Furthermore, high-frequency bathymetric profiles of the sea floor have none of the small hyperbolic reflections that indicate the presence of ripples, small sand waves, or furrows (Damuth and Hayes 1977). p - f n»"iii i7m . i . «-■ — Platform r 0 » H 2 < a. H i Lo.5 H 59 58 f Figure 5-23. Seismic-reflection profiles of geologic features in Shelikof Strait. M denotes sea-floor multiple reflection. A. Seismic-reflection profile showing faults with large sea-floor offset. B. Seismic-reflection profile showing stratigraphic relation of acoustic units. UB and SB are unstratified and stratified bedrock, respectively. Stratigraphic contacts are emphasized by dashed lines. A, B, C, and D indicate four different sediment. u\ units above bedrock. 128 Physical Environment Sediment Stratigraphy and General Distribution. The seismic stratigraphy of Shelikof Strait was analyzed in detail by Hampton (1985). He described and mapped four distinct units in the sedimentary section above bedrock (Fig. 5-23B). The section's thickness is about 80 m over much of the northeast half of the Strait, adjacent to Cook Inlet, but it reaches more than 800 m in the southwest half (Fig. 5-4). The first and lowermost unit (Unit A in Fig. 5-23B) has com- plex seismic stratigraphy, with intervals of a few strong reflectors separated by thicker intervals of weak, discon- tinuous reflectors. The reflectors have hummocky geometry in places, but their geometry ranges from planar to broadly folded in others. Although this unit occurs mainly in a deep erosional basin in the southwest half of the Strait, it also occurs in incised channels and other limited areas in the northeast half (Fig. 5-24A). It has an onlap-fill relation to the underlying bedrock and was inferred to be composed of glacial-marine deposits of late Pleistocene age. The second, next highest unit (Unit B in Fig. 5-23B) is thin, typically less than 20 m but ranging to 60 m in places. It is spread over much of the central Strait, with a separate deposit near Cape Douglas (Fig. 5-24B). The unit has weak, continuous internal reflectors, and it is constrained within low areas in the underlying surface. The lateral margins of the unit are onlap-fill, whereas the leading, southwest mar- gins are tapered. Mounded, fan-like buildups are located off Afognak and Shuyak Islands. This unit was inferred to have been deposited in a restricted marine environment that existed in early Holocene time, after ice retreated from the Strait but before onset of the modern circulation system. The third, overlying unit (Unit C in Fig. 5-23B) blankets most of the present sea floor up to 200 m thick (Fig. 5-24C). Internal reflectors are strong and continuous, and strata drape the underlying topography. Many of the present top- ographic features of the sea floor reflect the morphology of this unit. The platform in the central trough is the main loca- tion of deposition. Strata underlying the platform pinch out laterally to form the seaward boundaries of the marginal channels, which themselves are underlain by blanket-like deposits at the base of the unit. Strata also pinch out toward the moat at the base of the fault blocks. This sedimentary environment evolved from the previous one when the mod- ern circulation system became established. The fourth unit (Unit D in Fig. 5-23B) occurs along the sides of the Strait, beneath the shallow shelves and adjacent slopes. The base of the unit cannot be seen in seismic-reflec- tion profiles, but the stratigraphic range is that of Units B and C described above. The internal reflectors typically are short and discontinuous. Their inclination conforms closely to the sea floor: horizontal beneath the shelves and inclined beneath the slopes. Its lateral contact with other units is abrupt in some places and gradational in others. A distinct interfingering occurs prominently near Cape Douglas. The sediment for this unit has been emplaced by lateral pro- gradation of sediment derived from the landmasses adja- cent to the Strait. Although progradation appears to be lim- ited today, it probably was more intense in the past when glaciers were more abundant. 59 58 Cx^y?^ Figure 5-24. Thickness of seismic-stratigraphic units in Shelikof Strait. Isopleths in meters. Dashed line indicates approximate boundary of unit (from Hampton 1985). A. Unit A in Figure 5-23B. B. Unit Bin Figure 5-23B. C. Unit C in Figure 5-23B. Texture and Composition. Surficial sediment in the central trough of Shelikof Strait is derived mainly from Cook Inlet. It is progressively sorted starting with muddy sand at the boundary with Cook Inlet, and ranges to sandy mud at the southwest end of the Strait (Fig. 5-5). In addition, a detectable fining occurs across the Strait, from northwest to southeast. Detailed grain-size distributions show two dis- Geomorpholocy, Sediment and Sedimentary Processes 129 tinct populations (bed load and intermittent-suspension load) that appear as straight-line segments on cumulative probability plots (Hampton 1985). Clay minerals found in the sea-floor sediment contain the illite— rich suite found along the west side of lower Cook Inlet. A layer of Katmai ash up to 20 cm thick was recovered in several sediment cores. Its burial depth depends on the local, post-1912 sediment accumulation rate (Fig. 5-25). The rate is greatest along the Alaska Peninsula at the southwest end of the Strait and approaches zero at places in the mar- ginal channel along the Kodiak Island Group. Hydrocarbon gas was measured in 15 sediment cores, and only one core showed an amount that indicated saturation (Hampton et al. 1981). Acoustic anomalies have been identi- fied mainly in the northeast end of the Strait, but they show no evidence of being related to gas-charging (Hampton et al. 1981). Physical Properties. Physical-property measurements were made on sediment cores from the central trough (Hampton 1983c) (Fig. 5-26). Water content, plastic limit, liquid limit, plasticity index, and organic carbon content all increase down and across the Strait (Fig. 5-26A through E), with a strong inverse correlation to mean grain size. Vane shearing strength has the opposite trend, and grain specif- ic-gravity shows no discernible trend or correlation, except that the lowest values tend to cluster in the central part of the Strait (Fig. 5-26F and G). Certain properties show down- core trends; water content decreases, and vane shear strength increases (Hampton 1983c). The average compression index in cores ranges from 0.27 to 0.87— close to the range of 0.20 to 0.87 reported by Richards (1962) for measurements on samples of marine sediment from many geographic areas. The compression Figure 5-25. Depth beneath sea floor (cm) of Katmai ash in sed- iment cores from Shelikof Strait. Calculated sediment accumulation rate (cm/lOOy) in parentheses. (Modified from Hampton 1985.) index increases down the Strait; not enough data are avail- able to determine an across-Strait variation (Fig. 5-26H). The overconsolidation ratio exceeds 1.0 for all determina- tions (Hampton 1983c), probably indicating interparticle bonding rather than unloading (Richards and Hamilton 1967). Static triaxial strength tests give high values of 35 to 43° for the effective angle of internal friction, implying a high shearing strength under conditions of drained loading. Val- ues increase farther down the Strait (Fig. 5-261) in direct correlation with a decrease in grain size. Undrained strength is nearly constant (as shown by the values for the ratio of undrained strength to overburden stress). All but one of these ratios is 0.4 (Fig. 5-26J). Samples have a moder- ate strength degradation of 20 to 40% for 10 cycles under conditions of undrained, repeated loading (Hampton 1983c). Suspended Sediment. Suspended-matter studies in Shelikof Strait have been limited to spring and summer cruises from 1977 through 1979 (Massoth, Feely, Appriou, and Ludwig 1979; Feely, Massoth, Paulson, Lamb, and Mar- tin 1981; and Feely and Massoth 1982). Surface suspended- matter concentrations are relatively low, ranging from 0.3 to 2.0 mg/1 (Fig. 5-21). However, the data show evidence of a cross-channel temperature, salinity, and suspended-matter gradient that is consistent with a similar gradient observed in lower Cook Inlet during the same sampling periods (Feely and Massoth 1982). There is evidence of a near-bottom nepheloid layer, with a sediment concentration greater than 2.0 g/1 in the lower 50 to 60 m of the water column (Fig. 5-27) (Feely and Massoth 1982). The layer is associated primarily with bottom water- masses in the Strait and apparently is the result of resuspen- sion and redistribution of bottom sediment. The chemical data for the surface and near-bottom sus- pended matter show a higher percentage of biogenic silica and organic matter in the Strait than in lower Cook Inlet (Table 5-4). The enrichment of biogenic silica in the sus- pended phases is also reflected in the organic carbon con- tent of the sediment (Hampton et al. 1981). There is a strong enrichment in the Mn content (up to 12,000 ppm) of the near-bottom suspended matter along the main axis of the channel (Fig. 5-27) (Massoth etal. 1979). The Mn enrichment can be used to calculate the sediment accumulation rate. Sedimentary Processes The contemporary depositional conditions at the mouth of Cook Inlet continue south throughout Shelikof Strait. However, the retrospective view provided by the seismic profiles testifies that a succession of erosional and sedimen- tary regimes has occurred since Pleistocene time (Hampton 1985). The morphology of the bedrock surface is indicative of glacial erosion. In particular, the incised channels have broad cross sections and closed depressions. Valleys cut the steep northwest margin of the deep bedrock basin in the southern half of the Strait. These valleys extend outward from fjords on the adjacent coastline and have bedrock spurs, or bastions (Flint 1971). projecting from them. The 130 Physical Environment Geomorphology, Sediment and Sedimentary Proc esses 131 Salinity ("/<>o) SW NE NW |SE W E 2 3 6 8 9 10 12 4 5 6 7 11 12 13 Temperature (C) z f- a. u Q 200 300 Total Particulate Manganese (ng/1) o -)_j j i i i i a Total Suspended Matter (mg/1) Figure 5-27. Vertical cross sections of salinity, temperature, particulate Mn, and total suspended matter for stations in Shelikof Strait. Stations 2, 3, 6, 8, 9, 1 0, and 1 2 represent a longi- tudinal section along the main axis of the Strait. Stations 4 through 7 and 11 through 13 represent transverse sections at mid-Strait and upper-Strait locations, respectively. (Modified from Feelv, Massoth, Paulson, Lamb, and Martin 1981.) bastions were formed where ice that was flowing down the valleys deflected the southward flow of the main ice mass, thereby shielding part of the basin margin from erosion. Regional glaciation is believed to have commenced in Miocene time (Pewe 1975), and Shelikof Strait was last occupied by ice during the Naptowne glaciation, which occurred 48,000 to 5,500 years B.P. (Karlstrom 1964). A con- tinuous ice cover connected the Alaska Peninsula, (look Inlet, Shelikof Strait, and the Kodiak Islands (Capps 1937). According to Karlstrom (1964), the surface of the ice sloped southward from an elevation of more than 600 m on the Alaska Peninsula to 300 m on Kodiak Island. Channels incised into the bedrock unconformity in the northeast half of the Strait suggest that the main ice mass flowed south from Cook Inlet and the adjacent Alaska Peninsula. As the ice was deflected by the islands of the Kodiak Archipelago, the major portion continued southwest down the Strait, but some flowed through Stevenson Entrance. Erosion of the deep basin in southwest Shelikof Strait might have been due to either weak bedrock or to the addi- tion of ice from the adjacent landmasses. The bedrock strata are clearly truncated at the margin of the basin, but there is no evidence of the downwarping or marginal faulting that would indicate a structural origin. Glacial and glacial-marine deposits fill the deep basin and the incised channels in the bedrock surface. Deposits around the basin margin are mounded, hummocky, and chaotically stratified, particularly within and extending from the spur-bounded canyons. The deposits probably were emplaced near a grounded ice margin. Most of the basin fill has strong, continuous subparallel reflectors that are separated by thicker units of weak reflectors. These deposits probably were emplaced by remobilization and mass flow of the mounded-chaotic facies, by density flows associated with sediment-laden meltwater, and by the release of sediment from floating ice sheets or bergs (see Carey and Ahmad 1961; Drewry and Cooper 1981; Anderson, Brake, Domack, Myers, and Wright 1983; and Visser 1983). Deposits in the incised channels appear to be ice-contact or meltwater deposits. After ice retreated from the Strait, restricted marine con- ditions prevailed during early Holocene time. Sediment prograded into the sides of the Strait to form the discon- tinuously stratified unit (Unit D in Fig. 5-23B), and a few feeder canyons funneled sediment to the floor of the central trough. Fan deltas formed at the mouth of these canyons, and sediment prograded beyond these fans in the form of bedload. The sedimentation continued on through shallow, sinuous low areas and was finally deposited as a weakly strat- ified unit (Unit B in Fig. 5-23B). Sediment also encroached into the Strait from Cook Inlet (Fig. 5-24B). The contemporary sedimentary environment began rather abruptly when the Kenai Current (Schumacher and Reed 1980) breached the sill through Kennedy and Steven- son Entrances, flowed arcuately across the mouth of Cook Inlet, and encountered the sediment-laden estuarine out- flow on the west side near Cape Douglas. Then, as now-, the Cook Inlet sediment was dispersed throughout Shelikof Strait as suspension and intermediate-suspension load to accumulate as a sediment blanket across the floor of the Strait (Unit C in Fig. 5-23B). This sediment is constructing the platform on the floor of the trough. The marginal chan- nels and the moat around the uplifted fault blocks resulted from flow distortions. The current is accelerated through these features, causing reduced deposition relative to adja- cent areas (Hampton 1985). 132 Physical Environment Sedimentation in Shelikof Strait is progressing toward a state of dynamic equilibrium between the hydraulic condi- tions and the elevation of" the sea floor. This means that the regime becomes purely transportation^. The sediment accumulation rate (calculated from the burial depth of the Katmai ash layer) implies that in proximal areas at the northeast end of the Strait, the level of the platform has aggraded to a near-equilibrium elevation where current velocity nearly precludes deposition (accumulation rate is low) (Hampton 1985) (Fig. 5-25). In more distal areas to the southwest, sediment accumulation is more rapid (highest calculated rate is 122 mm/y), as sediment fills the low areas in the depositional surface that are farthest from equilibrium. The platform is prograding down the Strait to bring the entire sea floor closer to equilibrium. Most of the sediment transported laterally into the Strait from the Alaska Peninsula and the Kodiak Archipelago is being deposited behind sills in the fjords, so the discon- tinuously stratified unit (Unit D in Fig. 5-23B) is not pro- grading significantly at the present time. Southwest of Cape Douglas, however, sills are absent, and the discontinuously stratified material is being dispersed across the shallow shelf to mix with the well-stratified deposits derived from Cook Inlet. The Mn enrichment measured in the near-bottom sus- pended matter of Shelikof Strait has also been observed in other coastal areas. This phenomenon has been attributed to Mn remobilization from rapidly accumulating fine-grained sediment, with subsequent precipitation of the Mn on suspended matter in the water column (Graham, Bender, and Klinkhammer 1976; Aller and Benninger 1981; Yeats, Sunby, and Brewers 1979; Feely, Massoth, and Paulson 1981; Tefry and Presley 1982; and Feely, Massoth, Paulson, and Gendron 1983). Tefry (1977) showed that interstitial Mn flux from recent sediment in the Gulf of Mexico varies directly with the mass sediment accumulation rate. Massoth et al. (1979) found a similar relation for Mn flux from Shelikof Strait sediment. Figure 5-28 shows a plot of the relation between the calculated Mn flux at the sedi- ment-seawater interface and mass sediment accumulation rate for both the Gulf of Mexico and Shelikof Strait data. The high degree of correlation indicates that a linear rela- tion exists between the mass sediment accumulation rate and the Mn flux at the sediment-seawater boundary. This is primarily due to a corresponding increase in organic-mat- ter accumulation that acts as a reducing agent for the man- ganese. Thus, the near-bottom Mn enrichment in Shelikof Strait is a direct result of diagenetic processes in the underly- ing sediment and therefore can act as a sensitive indicator of these processes. Indeed, near-bottom enrichment of partic- ulate Mn has been observed elsewhere in the Gulf of Alaska and near the entrance to Prince William Sound where the sediment is accumulating at a rate that is similar to the rate along the main axis of Shelikof Strait. (R.A. Feely, NOAA/ PMEL, unpubl. data). Because newly formed hydrous Mn oxides in suspended matter are known to have a major role in scavenging and removal of a number of different trace metals in natural waters (Longathan and Burau 1973; Feely, Massoth, and Paulson 1981; and Feely, Massoth, Paulson, and Gendron 1983), this process may be an important mecha- Stations ■ Gulf of Mexico • Shelikof Strait 1.0 2.0 3.0 Sediment Accumulation Rate (g/cm2y) Figure 5-28. Relation between calculated fluxes of Mn from Shelikof Strait and Gulf of Mexico sediments, and sediment accumulation rates determined by 210Pb geochronology. nism for maintaining the low level of trace metal concentra- tion in Shelikof Strait as well as in the Gulf of Alaska (Mas- soth, Feely, Appriou, Ludwig, and Gendron, NOAA/PMEL, unpubl. data; Heggie 1983). Discussion and Conclusions Extensive knowledge has been obtained about the geol- ogy of the Gulf of Alaska. The focus of the preceding discus- sion is the surficial geology, that is, the geology from the sea floor to a relatively shallow depth beneath it. Corres- pondingly, the time frame is small, extending back into the late Pleistocene. The frameivork geology of the Gulf encom- passes a larger time frame and is concerned with the larger-scale aspects of structure, tectonism, and stratigra- phy. This framework geology is well known as a result of a large body of literature that has been summarized in a com- panion paper by Jacob (Ch. 6, this volume). Few data have been collected on the open shelf southeast of Cross Sound, between Montague Island and Amatuli Trough (the area between the northeastern Gulf and the Kodiak Shelf), or on the Shumagin Shelf southwest of Chi- rikof Island. The most significant knowledge gap in a spe- cific subject area is in the nature of the subsurface sediment. Inferences from seismic-reflection stratigraphy have been used to outline the general nature of sedimentary deposits and processes, but drill sampling is necessary in order to obtain specific information about lithology and detailed stratigraphy. In spite of these information needs, the evidence is clear for a consistent, though complex, interaction of tectonism, glaciation, and subpolar climate in controlling the surficial geology of the region. This includes important local con- trasts in oceanography and the sedimentary environment, particularly during the Holocene, that serve to distinguish each geographic area. The Gulf of Alaska Shelf (an area of intense tectonic force) lies at the margin of the Pacific and North America lithospheric plates. The present configuration of the Pacific Geomorphology, Sediment and Sedimentary Processes 133 crust (that moves northwest relative to North America) became established in early Tertiary time (Byrne 1979; Engebretson, Cox, and Gordon 1984). The long-term geo- morphic evolution of the sea floor has been primarily con- trolled by tectonic forces, which have formed deeply sub- sided basins and intervening uplifted highs (Fisher and von Huene 1980; Brims 1982, 1985). Even today the sea floor is being actively deformed; as much as 15 m of uplift was docu- mented after the Cheat Alaskan Earthquake of 1964 (Plafker 1972; Malloy and Merrill 1972; and von Huene et al 1972). The modern sea floor owes its geomorphology more to glaciation than to tectonism. Ice sheets have waxed and waned across the region since Miocene time, and have advanced out to the shelf break at least once (Karlstrom 1964; Thrasher 1979; and Carlson et al. 1982). While it occupied the shelf, the ice severely eroded bedrock into forms that are typical of glacial action. Seismic-reflection profiles in confined areas such as Nuka Bay (von Huene 1966) and Shelikof Strait (Hampton 1985) display deeply eroded basins far below the lowest sea level. On the open shelf, deformed strata that compose bedrock have been truncated along extensive flat surfaces that are liberally incised with broad, flat-floored valleys, most of which align with fjords and probably mark the position of ancient ice streams (Carlson et al. 1982; Hampton 1983a). Capping the erosion surface are linear moraines and blankets of other ice-contact and meltwater deposits (Thrasher 1979; Molnia and Carlson 1978, 1980). At the beginning of Holocene time, ice retreated, the sea level rose, and the modern geologic, climatic, and oceanographic setting developed. The rugged, glaciated mountains throughout the area became an abundant source of sediment that is now deposited in coastal embayments or delivered to the sea by a few major rivers and glaciers. The sediment is dispersed by currents that tend to be sluggish on the open shelf except when driven by waves from fierce storms that frequent the area (Reed and Schumacher, Ch. 3, this volume). Certain current velocities in the area are rela- tively strong, both as a consequence of seasonally variable freshwater runoff from the rivers and as a result of modify- ing influences of the wind. Currents are particularly strong near the shelf break and throughout most of the Gulf, at the location of the Alaska Stream (Favorite 1967; Thomson 1972), and within baroclinic coastal currents that flow along the south side of the Kenai Peninsula (Schumacher and Reed 1980; Rover, Luick, andjohnson 1984). The continental shelf in the northeastern Gulf of Alaska is characterized by large areal variation in sedimentation rate, from nil in areas of repeated strong storm currents (Tarr Bank) to extreme in some coastal embayments (Icy Bay) and the mouth of large rivers (Copper River and Alsek River) (Molnia 1979b; Molnia and Sangrey 1979). Much of the suspended sediment introduced by rivers is carried west- ward by regional currents (Reimnitz and Carlson 1975). The unconsolidated sediment on the shelf is unstable in many places; large sediment slides and flows have been triggered both by earthquakes and b\ waves (Schwab and Lee 1983). The Kodiak Shelf is receiving only a small amount of modern sediment because it is isolated from major fluvial or glacial sources. Biologic and volcanic activity are providing some material, and deposits of diatom tests and volcanic ash are important locally. The sedimentary environment is typ- ified by material that has been reworked on the shallow banks and then rcdeposited in glacial troughs (Hampton 1983a). Tectonically uplifted areas are devoid of significant accumulations of unconsolidated sediment, but it is unclear whether this is because no material is deposited in these areas, or because of subaerial or submarine erosion. Estuarine conditions with strong tidal currents exist in Cook Inlet. Also, the Alaska Coastal Current (locally called the Kenai Current) plays a major role in circulation in the lower Inlet (Muench et al. 1981). Sedimentation varies system- atically throughout the Inlet. Coarse sediment from rivers that empty into the head of the Inlet is deposited near the source, whereas most of the suspended load is carried south into Shelikof Strait (Sharma and Burrell 1970). Strong cur- rents in the constricted Forelands area cause winnowing of all but the coarsest sediment, and most of the winnowed material is carried south to the lower Inlet where there are large fields of sand waves in the central portions (Bouma et al. 1980). Fine sediment accumulates in the deep water at the mouth of the Inlet and in quiescent areas around the margin. Circulation in Shelikof Strait is driven by the Kenai Cur- rent and the Alaskan Stream, and the net water and sedi- ment movement is to the southwest. The major source of sediment is from Cook Inlet. Deposits of sandy bedload sedi- ment decrease down the Strait, but intermittent-suspension and suspended-load deposits increase (Hampton 1985). Surficial sediment is progressively sorted from muddy sand adjacent to lower Cook Inlet to mud at the southwest end of the Strait. Acknowledgments Terry Bruns, Rodney Combellick, Bruce Molnia, and Erk Reimnitz reviewed the manuscript and made helpful sug- gestions for improvement. We are grateful to the crews of the USGS and NOAA research vessels Sea Sounder, S.P. Lee, and Discoveror for their skillful and willing support in achiev- ing the goals of these investigations. Funding was jointly provided by the United States Geological Survey and the Minerals Management Service, Department of the Interior, through an interagency agreement with the National Oceanic and Atmospheric Administration, Department of Commerce, under which a multi-year program responding to needs of petroleum development of the Alaska continen- tal shelf is managed by the Outer Continental Shelf Environ- mental Assessment Program Office. 134 Physical Environment References Aller, R.C. and L.R. Benninger 1981 Spatial and temporal patterns of dissolved ammonium manganese, and silica fluxes from bottom sediments of Long Island Sound, U.S.A. Journal of Marine Research 39:295-314. American Geographical Society 1966 Glacier Bay, Alaska - Map showing former positions of termini, 1760-1966. American Geo- graphical Society, New York, NY. Anderson, K.H., J.H. Pool, S.F. Brown, and W.F. Rosenbrand 1980 Cyclic and static laboratory tests on Drammen clay. American Society of Civil Engineers, Journal of the Geotechnical Engineering Division 106:499-529. Anderson, J.B., C.F. Brake, E.W. Domack, N.C. Myers, and R. Wright 1983 Development of a polar glacial-marine sedi- mentation model from Antarctic Quaternary deposits and glaciological information. In: Glacial- Marine Sedimentation. B.F. Molnia, edi- tor. Plenum Press, New York, NY. pp. 233-264. Arctic Environmental Information and Data Center 1974 The Western Gulf of Alaska: A Summary of Available Knowledge. University of Alaska, Anchorage, AK. 599 pp. Armentrout,J.M. 1983 Glacial lithofacies of the Neogene Yakataga Formation, Robinson Mountains, southern Alaska Coast range. In: Glacial-Marine Sedimen- tation. B.F. Molnia, editor. Plenum Press, New York, NY. pp. 629-665. Atlas, R.M., M.I. Venkatesan, I.R. Kaplan, R.A. Feely, R.P. Griffiths, and R.Y. Morita 1983 Distribution of hydrocarbons and microbial populations related to sedimentation proc- esses in lower Cook Inlet and Norton Sound, Alaska. Arctic 36:251-261. Atwood, T.J., T.R. Bruns, P.R. Carlson, B.F. Molnia, and G. Plafker 1981 Bathymetric maps of the northern Gulf of Alaska. U.S. Geological Survey Miscellaneous Field Studies Map MF-859. 3 sheets (1:250,000). Biscaye, P.E. and C.R. Olsen 1976 Suspended particulate concentrations and compositions in the New York Bight. In: Middle Atlantic Continental Shelf and the New York Bight. M.G. Gross, editor. American Society of Lim- nology and Oceanography Special Symposium Vol. 2, Lawrence, KS. pp. 124-137. Boothroyd, J.C. and G.M. Ashley 1975 Processes, bar morphology, and sedimentary structures on braided outwash fans, north- eastern Gulf of Alaska. In: Glaciofluvial and Glaciolacustrine Sedimentation. A.V. Jopling and B.C. McDonald, editors. Special Publication No. 23, Society of Economic Paleontologists and Mineralogists, Tulsa, OK. pp. 193-222. Boothroyd, J.C, M.S. Cable, and R.A. Levy 1976 Coastal morphology and sedimentation, Gulf coast of Alaska (glacial sedimentation). Research Unit 59. Environmental Assessment of the Alaskan Continental Shelf, Annual Reports of Prin- cipal Investigators 12:87-372. Bouma, A.H. 1981 Submarine topography and physiography of lower Cook Inlet, Alaska. U.S. Geological Sur- vey Open-File Report 81-1335. 31 pp. Bouma, A.H. and M.A. Hampton 1976 Preliminary report on the surface and shallow subsurface geology of lower Cook Inlet and Kodiak Shelf, Alaska. U.S. Geological Survey Open-File Report 76-695. 36 pp. Bouma, A.H, M.A. Hampton, and R.C. Orlando 1977 Sand waves and other bedforms in lower Cook Inlet, Alaska. Marine Geotechnology 2:291-308. Bouma, A.H., M.A. Hampton, M.P. Wennekens, and J.A. Dygas 1977 Large dunes and other bedforms in lower Cook Inlet, Alaska. Proceedings of the Ninth Annual Offshore Technology Conference, May 2-5, 1977, Houston, Texas, Vol. 1. pp. 79-90. Bouma, A.H., M.L. Rappeport, R.C. Orlando, and M.A. Hampton 1980 Identification of bedforms in lower Cook Inlet, Alaska. Sedimentary Geology 26:157-177. Bouma, A.H., M.A. Hampton, T.P. Frost, M.E. Torresan, R.C. Orlando, andJ.W. Whitney 1978 Bottom characteristics of lower Cook Inlet, Alaska. U.S. Geological Survey Open-File Report 78-236. 93 pp. Bouma, A.H., M.A. Hampton, M.L. Rappeport, J. W. Whitney, P.G. Teleki, R.C. Orlando, and M.E. Torresan 1978 Movement of sand waves in lower Cook Inlet, Alaska. Proceedings of the Tenth Annual Offshore Technology Conference, May 8-10, 1978, Houston, Texas, Vol. 4. pp. 2271-2285. Bouma, A.H., M.L. Rappeport, D.A. Cacchione, D.E. Drake, L.E. Garrison, M.A. Hampton, and R.C. Orlando 1979 Bedform characteristics and sand transport in a region of large sand waves, lower Cook Inlet, Alaska. Proceedings of the Eleventh Annual Offshore Technology Conference, April 30- May 3, 1979, Houston, Texas, Vol. 2. pp. 1083-1094. Geomorphology, Sediment and Sedimentary Processes 135 Brower, W.A., H.W. Searby, J.L. Wise, H.F. Diaz, and A.S. Prechtel 1977 Climatic Atlas of the Outer Continental Shelf Waters and Coastal Regions of Alaska, Vol. I, Calf of Alaska. Arctic Environmental Information and Data Center, University of" Alaska, Anchorage, AK. 439 pp. Bruns, T.R., editor 1982 Hydrocarbon resource report for proposed OCS lease sale 88: southeastern Alaska, north- ern Gulf of Alaska, Cook Inlet, and Shelikof Strait, Alaska. U.S. Geological Survey Open- File Report 82-928. 133 pp. Bruns, T.R. 1983 Structure and petroleum potential of the Yakutat segment of the northern Gulf of Alaska continental margin. U.S. Geological Survey Miscellaneous Field Studies Map MF-1480. 3 sheets (1:500,000) and 22 pp. Bruns, T.R. 1985 Tectonics of the Yakutat Block, an allochthonous terrane in the northern Gulf of Alaska. U.S. Geological Survey Open-File Report 85-13. 112 pp. Bruns, T.R. and W.C. Schwab 1983 Structure maps and seismic stratigraphy of the Yakataga segment of the continental margin, northern Gulf of Alaska. U.S. Geological Sur- vey Miscellaneous Field Studies Map MF-1424. 4 sheets (1:250,000) and 25 pp. Burbank, D.C. 1974 Suspended sediment transport and deposition in Alaskan coastal waters. M.S. Thesis, Univer- sity of Alaska, Fairbanks, AK. 222 pp. Burbank, D.C. 1977 Circulation studies in Kachemak Bay and lower Cook Inlet, Alaska. Alaska Department of Fish and Game, Anchorage, AK. 207 pp. Burrell, D.C. 1977 Natural distribution of trace heavy metals and environmental background in Alaskan shelf and estuarine areas. Research Unit 162. Environ- mental Assessment of Alaskan Continental Shelf, Annual Reports of Principal Investigators 13:290-481. Byrne, T. 1979 Late Paleocene demise of the Kula-Pacific spreading center. Geology 7:341-344. Capps, S.R. 1937 Kodiak and adjacent islands. U.S. Geological Survey Bulletin No. 880-C. 73 pp. Carey, S.W. and N. Ahmad 1961 Glacial marine sedimentation. In: Proceedings of the First International Symposium on Arctic Geology, Vol. 2. G. Raasch, editor. University of Toronto Press, Toronto, pp. 865-894. Carlson, P.R. 1978 Holocene slump on continental shelf off Mal- aspina Glacier, Gulf of Alaska. American Associa- tion of Petroleum Geologists Bulletin 62:2412-2426. Carlson, P.R. and B.F. Molnia 1977 Submarine faults and slides on the continental shelf, northern Gulf of Alaska. Marine Geo- technology 2:275-290. Carlson, P.R. and B.F. Molnia 1978 Minisparker profiles and sedimentologic data from R/V Acona cruise (April, 1976) in the Gulf of Alaska and Prince William Sound. U.S. Geo- logical Survey Open-File Report 78-381. 2 sheets and 32 pp. Carlson, P.R. and W.C. Schwab 1982 Northern Gulf of Alaska environmental geol- ogy. In: Hydrocarbon resource report for pro- posed OCS lease sale 88: southeastern Alaska, northern Gulf of Alaska, Cook Inlet, and Shelikof Strait, Alaska. T.R. Bruns, editor. U.S. Geological Survey Open-File Report 82-928. pp. 73-86. Carlson, P.R., B.F. Molnia, and W.P. Levy 1980 Continuous acoustic profiles and sedimen- tologic data from R/V Sea Sounder cruise (S-l-76), eastern Gulf of Alaska. U.S. Geo- logical Survey Open-File Report 80-65. 3 sheets (1:250,000) and 41 pp. Carlson, P.R., B.F. Molnia, and E. Reimnitz 1976 Dispersal, distribution and thickness of Holo- cene sediment on the continental shelf, north- ern Gulf of Alaska. In: The Neogene Symposium: Selected Technical Papers on Paleontology, Sedimen- tology, Petrology, Tectonics, Geologic History of the Pacific Coast of North America. A.E. Fritsche, H.T. Best, Jr., and W.W. Wornardt, editors. Pacific Section of the Society of Economic Paleon- tologists and Mineralogists, Los Angeles, CA. pp. 63-64. Carlson, P.R., B.F. Molnia, and M.C. Wheeler 1980 Seafloor geologic hazards in OCS lease area 55, eastern Gulf of Alaska. Proceedings of the Twelfth Annual Offshore Technology Conference, May 5-8, 1980, Houston, Texas, Vol. 4. pp. 593-603. Carlson, P.R., G. Plafker, and T.R. Bruns 1985 Map and selected seismic profiles of the sea- ward extension of the Fairweather Fault, east- ern Gulf of Alaska. U.S. Geological Survey Miscellaneous Field Studies Map MF-1722. 2 sheets (1:500,000). 136 Physical Environment Carlson, P.R., T.R. Bruns, B.F. Molnia, and W.C. Schwab 1982 Submarine valleys in the northeastern Gulf of Alaska: characteristics and probable origin. Marine Geology 47:217-242. Carlson, P.R., B.F. Molnia, S.C. Kittleson, and J.C. Hampson 1977 Map of distribution of bottom sediments on the continental shelf, northern Gulf of Alaska. U.S. Geological Survey Miscellaneous Field Studies Map MF-876. 2 sheets (1:500,000) and 13 pp. Carlson, P.R., G. Plafker, T.R. Bruns, and W.P. Levy 1979 Seaward extension of the Fairweather Fault. In: The United States Geological Survey in Alaska: Accomplishments During 1978. K.M.Johnson and J.R. Williams, editors. U.S. Geological Survey Circular 804-B. pp. B135-B139. Carlson, P.R., M.C. Wheeler, B.F. Molnia, and T.J. Atwood 1979 Neoglacial sedimentation in Glacier Bay, Alaska. In: The United States Geological Survey in Alaska: Accomplishments During 1978. K.M. John- son and J.R. Williams, editors. U.S. Geological Survey Circular 804-B. pp. B114-B116. Carlson, P.R., B.F. Molnia, J.C. Hampson, A. Post, and T.J. Atwood 1978 Post-deglaciation sedimentation in Yakutat Bay, Alaska. Transactions of the American Geophysi- cal Union 59:296. (Abstract only) Carlson, P.R., M.C. Wheeler, B.F. Molnia, A. Post, and R.D. Powell 1983 Maps showing post-Neoglacial sediment thick- ness and bathymetry in Tarr Inlet, Glacier Bay, Alaska. U.S. Geological Survey Miscellaneous Field Study Map MF-1456. 1 sheet (1:31,680). Casagrande, A. 1936 The determination of the pre-consolidation load and its practical significance. Proceedings, First International Conference of Soil Mechanics and Foundation Engineering, p. 60. Coulter, H.W. and R.R. Migliaccio 1966 Effects of the earthquake of March 27, 1964, at Valdez, Alaska. U.S. Geological Survey Profes- sional Paper 542-C. 36 pp. Damuth, J.E. and D.E. Hayes 1977 Echo character of the east Brazilian continental margin and its relationship to sedimentary processes. Marine Geology 24:73-95. Drewry, D.J. and A.P.R. Cooper 1981 Processes and models of Antarctic glaciomarine sedimentation. Annals ofGlaciology 2:117-122. Dunlavey, J.M., J.R. Childs, and R.E. von Huene 1980 Bathymetric map of the western Gulf of Alaska. U.S. Geological Survey Open-File Report 80-1093. 13 sheets (1:250,000). Engebretson, D.C., A. Cox, and R.G. Gordon 1984 Recent motions between oceanic plates of the Pacific Basin. Journal of Geophysical Research 89B:10,291-10,310. Favorite, F. 1967 The Alaskan Stream. Bulletin of the North Pacific Fisheries Commission No. 21. pp. 1-20. Feely, R.A. and GJ. Massoth 1982 Sources, composition, and transport of sus- pended particulate matter in lower Cook Inlet and northwestern Shelikof Strait, Alaska. NOAA Technical Report ERL-415 PMEL-34. 28 pp. Feely, R.A., G.J. Massoth, and W.M. Landing 1981 Major- and trace-element composition of sus- pended matter in the north-east Gulf of Alaska: relationships with major sources. Marine Chemistry 10:431-453. Feely, R.A., GJ. Massoth, and A.J. Paulson 1981 The distribution and elemental composition of suspended particulate matter in Norton Sound and the northeastern Bering Sea shelf: implica- tions for Mn and Zn recycling in coastal waters. In: The Eastern Bering Sea Shelf: Oceanography and Resources, Vol. 1. D.W. Hood andJ.A. Calder, editors. Office of Marine Pollution Assessment/ NOAA. Distributed by University of Wash- ington Press, Seattle, WA. pp. 321-337. Feely, R.A., A.J. Chester, A.J. Paulson, andJ.D. Larrance 1982 Relationships between organically bound Cu and Mn in settling particulate matter and bio- logical processes in a subarctic estuary. Estu- aries 5:74-80. Feely, R.A., GJ. Massoth, A.J. Paulson, andJ.F. Gendron 1983 Possible evidence for enrichment of trace ele- ments in the hydrous manganese oxide phases of suspended matter from an urbanized embayment. Estuarine, Coastal and Shelf Science 17:693-708. Feely, R.A., E.T. Baker, J.D. Schumacher, GJ. Massoth, and W.M. Landing 1979 Processes affecting the distribution and trans- port of suspended matter in the northeastern Gulf of Alaska. Deep-Sea Research 26:445-464. Feely, R.A., GJ. Massoth, A.J. Paulson, M.F. Lamb, and E.A. Martin 1981 Distribution and elemental composition of sus- pended matter in Alaskan coastal waters. NOAA Technical Memorandum ERL PMEL-27. 119 pp. Geomorpholocy, Sediment and Sedimentary Processes 137 Fisher, M.A. and R.E. von Huene 1980 Structure of upper Cenozoic strata beneath Kodiak Shelf. American Association of Petroleum Geologists Bulletin 64:1014-1033. Flint, R.F. 1971 Glacial and Quaternary Geology. John Wiley and Sons, New York, NY. 892 pp. Gatto, L.W. 1976 Calculation and sediment distribution in Cook Inlet, Alaska. In: Assessment of the Arctic Marine Environment: Selected Topics. D.W. Hood and D.C. Burrell, editors. Occasional Publication No. 4, Institute of Marine Science, University of Alaska, Fairbanks, AK. pp. 205-227. Geopfert, B.L. 1969 An engineering challenge - Cook Inlet, Alaska. Proceedings of the First Offshore Technology Con- ference, May 18-21, 1969, Houston, Texas, Vol. 1. pp. 1-512 to 1-522. Gershanovich, D.E. 1968 New data on the geomorphology and recent sediments of the Bering Sea and the Gulf of Alaska. Marine Geology 6:281-296. Gibson, R.E. 1958 The progress of consolidation in a clay layer increasing in thickness with time. Geotechnique 8:171-182. Gibson, W.M. 1960 Submarine topography in the Gulf of Alaska. Bulletin of the Geological Society of America 71:1087-1107. Golan-Bac, M. and K.A. Kvenvolden 1983 Methane in sediments of the eastern Gulf of Alaska. In: Geotechnical framework, northeast Gulf of Alaska. HJ. Lee and W.C. Schwab, edi- tors. U.S. Geological Survey Open-File Report 83-499. pp. 108-114. Graham, W.F., M.L. Bender, and G.P. Klinkhammer 1976 Manganese in Narragansett Bay. Limnology and Oceanography 21:665-673. Griffin, J.J. , H. Windom, and E.D. Goldberg 1968 The distribution of clay minerals in the world ocean. Deep-Sea Research 15:433-459. Hampton, M.A. 1981 Grain size and composition of sea floor sedi- ment, Kodiak Shelf, Alaska. U.S. Geological Survey Open-File Report 81-659. 79 pp. Hampton, M.A. 1982a Synthesis report: environmental geology of lower Cook Inlet, Alaska. U.S. Geological Sur- vey Open-File Report 82-197. 55 pp. Hampton, M.A. 1982b Synthesis report: environmental geolog\ of kodiak Shelf, Alaska. U.S. Geological Survey Open-File Report 82-59. 76 pp. Hampton, M.A. 1983a Geology of the Kodiak Shelf, Alaska: environ- mental considerations for resource develop- ment. Continental Shelf Research 1:253-281. Hampton, M.A. 1983b Geotechnical framework study of the Kodiak Shelf, Alaska. U.S. Geological Survey Open- File Report 83-171. 87 pp. Hampton, M.A. 1983c Geotechnical framework study of Shelikof Strait, Alaska. U.S. Geological Survey Open- File Report 83-200. 123 pp. Hampton, M.A. 1985 Quaternary sedimentation in Shelikof Strait, Alaska. Marine Geology 62:213-253. Hampton, L.D. and A.L. Anderson 1974 Acoustics and gas in sediments. In: Natural Gases in Marine Sediments. I.R. Kaplan, editor. Plenum Press, New York, NY. pp. 249-273. Hampton, M.A. and A.H. Bouma 1977. Slope instability near the shelf break, western Gulf of Alaska. Marine Geotechnology 2:309-331. Hampton, M.A. and K.A. Kvenvolden 1981 Geology and geochemistry of gas-charged sed- iment on Kodiak Shelf, Alaska. Geo-Marine Let- ters 1:141-147. Hampton, M.A., A.H. Bouma, T.P. Frost, and LP. Colburn 1979 Volcanic ash in surficial sediments of the Kodiak Shelf — an indicator of sediment dis- persal patterns. Marine Geology 29:347-356. Hampton, M.A., A.H. Bouma, M.E. Torresan, and LP. Colburn 1978 Analysis of microtextures on quartz sand grains from lower Cook Inlet, Alaska. Geology 6:105-110. Hampton, M.A., K.H.Johnson, M.E. Torresan, and W.J. Winters 1981 Description of seafloor sediment and prelimi- nary geo-environmental report, Shelikof Strait, Alaska. U.S. Geological Survev Open- File Report 81-1133. 87 pp. Hampton, M.A., A.H. Bouma, P.R. Carlson, B.F. Molnia, E.C. Clukey, and D.A. Sangrey 1978 Quantitative study of slope instability in the Gulf of Alaska. Proceedings of the Tenth Annual Offshore Technology Conference, May 8-10, 1978, Houston, Texas, Vol. 4. pp. 2308-2318. 138 Physical Environment Hayes, M.O. 1976 A modern depositional system - southeast Alaskan coast. In: Terrigenous clastic deposi tional environments: some modern examples. M.O. Hayes and T.W. Kana, editors. University of South Carolina Technical Report No. 11-CRD, Columbia, SC. pp. 1-112 to 1-120. Hayes, M.O. andj. Michel 1982 Shoreline sedimentation within a forearc embayment, lower Cook Inlet, Alaska.Joimial of Sedimentary Petrology 52:251-263. Hayes, M.O. and C.H. Ruby 1977 Coastal morphology of the northern Gulf of Alaska. Environmental Assessment of the Alaskan Continental Shelf, Quarterly Reports of Principal Investigators April-June 2:329-406. Hayes, M.O., J. Michel, and P J. Brown 1977 Vulnerability of coastal environments of lower Cook Inlet, Alaska to oil spill impact. In: Pro- ceedings of the Fourth International Conference on Port and Ocean Engineering Under Arctic Condi- tions. Memorial University of Newfoundland, St. John's, Newfoundland, pp. 1-12. Heggie, D.T. 1983 Copper in the Resurrection Fjord, Alaska. Estuarine, Coastal and Shelf Science 17:613-635. Hein, J.R., A.H. Bouma, M.A. Hampton, and C.R. Ross 1979 Clay mineralogy, fine-grained sediment dis- persal, and inferred current patterns, lower Cook Inlet and Kodiak Shelf, Alaska. Sedimen- tary Geology 24:291-306. Holmes, M.L. and D.R. Thor 1982 Distribution of gas-charged sediment in Nor- ton Sound and Chirikov Basin, northeastern Bering Sea. Geologie en Mijnbouw 61:79-89. Holtz, R.D. and W.D. Kovacs 1981 An Introduction to Geotechnical Engineering. Pren- tice-Hall, Inc., Englewood Cliffs, NJ. 733 pp. Hoskin, CM. and D.C. Burrell 1972 Sediment transport and accumulation in a fjord basin, Glacier Bay, Alaska./ownra/ of Geol- ogy 80: 539-551. Jordan, G.F. 1962 Redistribution of sediments in Alaskan bays and inlets. Geographical Revieiv 52:548-558. Karlstrom, T.N.V. 1964 Quaternary geology of the Kenai Lowland and glacial history of the Cook Inlet region, Alaska. U.S. Geological Survey Professional Paper 443. 69 pp. Keller, G.H., D.N. Lambert, and R.H. Bennett 1979 Geotechnical properties of continental slope deposits — Cape Hatteras to Hydrographer Canyon. In: Geology of Continental Slopes. L.J. Doyle and O.H. Pilkey,Jr., editors. Special Pub- lication No. 27, Society of Economic Paleon- tologists, Tulsa, OK. pp. 131-152. Kramer, L.S., V.C. Clark, and G.J. Cannelos 1978 Planning for Offshore Development. In: Gulf of Alaska OCS handbook. Alaska Department of Community and Regional Affairs, Juneau, AK. 257 pp. Ladd, C.C. and R. Foott 1974 New design procedure for stability of soft clays. American Society of Civil Engineers, Journal of the Geotechnical Engineering Division 100:763-786. Lagerloef, G. 1983 Topographically controlled flow around a deep trough transecting the shelf off Kodiak Island, Alaska. Journal of Physical Oceanography 13:139-146. Lambe, T.W. and R.V. Whitman 1969 Soil Mechanics. John Wiley and Sons, New York, NY. 553 pp. Landing, W.M. and R.A. Feely 1981 The chemistry and vertical flux of particles in the northeastern Gulf of Alaska. Deep-Sea Research 28A:19-37. Lee, H J. 1979 Offshore soil sampling and geotechnical parameter determination. Proceedings of the Elev- enth Annual Offshore Technology Conference, April 30-May 3, 1979, Houston, Texas, Vol. 3. pp. 1449-1457. Lee, H.J. and W.C Schwab 1983 Geotechnical framework, northeastern Gulf of Alaska. U.S. Geological Survey Open-File Report 83-499. 420 pp. Lee, H.J., B.D. Edwards, and M.E. Field 1981 Geotechnical analysis of a submarine slump, Eureka, California. Proceedings of the Thirteenth Annual Offshore Technology Conference, May 4-7, 1981, Houston, Texas, Vol. 4. pp. 53-66. Lemke, R.W. 1967 Effects of the earthquake of March 27, 1964, at Seward, Alaska. U.S. Geological Survey Profes- sional Paper 542-E. 49 pp. Longathan, P. and R.G. Burau 1973 Sorption of heavy metal ions by a hydrous man- ganese oxide. Geochimica et Cosmochima Acta 37:1277-1293. Geomorpholocy, Sediment and Sedimentary Processes 139 Mackievvicz, N.E., R.D. Powell, P.R. Carlson, and B.F. Molnia 1984 Interlaminated ice-proximal glaci-marine sediments in Mnir Inlet, Alaska. Marine Geology 57:113-147. Mahmood, A., C.J. Ehlers, and B.A. Cilvveck 1981 Sand waves in lower Cook Inlet, Alaska. Ameri- can Society of Civil Engineers, Journal of the Geo- technical Division 10:1293-1307. Malloy, R.J. and G.F. Merrill 1972 Vertical crustal movement on the sea floor. In: The Great Alaska Earthquake of 1964, Vol. 6: Oceanography and Coastal Engineering. National Research Council, National Academy of Sci- ences, Washington, D.C. pp. 252-265. Massoth, G.J., R.A. Feely, P.Y. Appriou, and S.J. Ludwig 1979 Anomalous concentrations of particulate man- ganese in Shelikof Strait, Alaska: an indicator of sediment-seawater exchange processes. Transactions of the American Geophysical Union 60:852. (Abstract only) McClellan, P.H., R.E. Arnal, J.A. Barron, R.E. von Huene, M.A. Fisher, and G.W. Moore 1980 Biostratigraphic results of dart-coring in the western Gulf of Alaska, and their tectonic implications. U.S. Geological Survey Open- File Report 80-63. 24 pp. Meade, R.H., R.T. Sachs, R.T. Manheim, J.C. Hathaway, and D.W. Spencer 1975 Sources of suspended matter in water of the Middle Atlantic Bight. Journal of Sedimentary Petrology 45:171-188. Miller, D.J. 1953 Late Cenozoic marine glacial sediments and marine terraces of Middleton Island, Alaska. Journal of Geology 61:17-40. Miller, D.J. 1960 The Alaska earthquake of July 10, 1958: giant wave in Lituya Bay. Bulletin of the Seismological Society of America 50:253-266. Molnia, B.F. 1977 Rapid shoreline erosion at Icy Bay, Alaska - a staging area for offshore petroleum develop- ment. Proceedings of the Ninth Annual Offshore Technology Conference, May 2-5, 1977, Houston, Texas, Vol. 3. pp. 115-126. Molnia, B.F. 1979a Origin of gas pockmarks and craters. Geological Society of America, Abstracts with Programs 11:481-482. Molnia, B.F. 1979b Sedimentation in coastal embayments, north- eastern Gulf of Alaska. Proceedings of the Eleventh Annual Offshore Technology Conference, April 30- May 3, 1979, Houston, Texas, Vol. 1. pp. 665-670. Molnia, B.F. 1981 Distribution of continental shelf surface sedi- mentary units between Yakutat and Cross Sound, northeastern Gulf of Alaska. Journal of the Alaska Geological Society 1:60-65. Molnia, B.F. 1983 Subarctic glacial-marine sedimentation: a model. In: Glacial- Marine Sedimentation. B.F. Molnia, editor. Plenum Press, New York, NY. pp. 95-144. Molnia, B.F. and P.R. Carlson 1975 Surface sediment distribution map, northern Gulf of Alaska. U.S. Geological Survey Open- File Report 75-505. 1 sheet (1:500,000) and 5 pp. Molnia, B.F. and P.R. Carlson 1978 Surface sedimentary units of northern Gulf of Alaska continental shelf. American Association of Petroleum Geologists Bulletin 62:633-643. Molnia, B.F. and P.R. Carlson 1980 Quaternary sedimentary facies on the conti- nental shelf of the northeastern Gulf of Alaska. In: Quaternary Depositional Environments of the U.S. Pacific Continental Margin. M.E. Field, A.H. Bouma, and I.P. Colburn, editors. Pacific Sec- tion of the Society of Economic Paleontologists and Mineralogists, Bakersfield, CA. pp. 157-168. Molnia, B.F. andJ.R. Hein 1982 Clay mineralogy of a glacially dominated sub- arctic continental shelf: northeastern Gulf of Alaska. Journal of Sedimentary Petrology 52:515-528. Molnia, B.F. and M.L. Rappeport 1980 Seafloor mosaic of the Alsek River pockmark, slump, and sediment-failure area, north- east-Gulf of Alaska. Geological Society of America, Abstracts with Programs 12:486. (Abstract only) Molnia, B.F. and M.L. Rappeport 1984 Mosaic of the Alsek sediment instability area, northeastern Gulf of Alaska. U.S. Geological Survey Open-File Report 84-397. 2 sheets (1:40,000) and 17 pp. Molnia, B.F. and D.A. Sangrey 1979 Glacially derived sediments in the northern Gulf of Alaska - geology and engineering char- acteristics. Proceedings of the Eleventh Annual Off- shore Technology Conference, April 30-May 3, 1979, Houston, Texas, Vol. 1. pp. 647-655. 140 Physical Environment Molnia, B.F. and M.C. Wheeler 1978 Report on the beach dynamics, geology, and oil spill susceptibility of the Gulf of Alaska coast- line in Glacier Bay National Monument — Sea Otter Creek to Icy Point. U.S. Geological Sur- vey Open-File Report 78-284. 1 sheet (1:63,360) and 192 pp. Molnia, B.F., P.R. Carlson, and T.R. Bruns 1977 Large submarine slide in Kayak Trough, Gulf of Alaska. In: Landslides: Reviews in Engineering Geology. Geological Society of America, Denver, CO. pp. 137-148. Molnia, B.F., P.R. Carlson, and K.A. Kvenvolden 1978 Gas-charged sediment areas in the northern Gulf of Alaska. Geological Society of America, Abstracts with Programs 10:548-549. (Abstract only) Molnia, B.F., W.P. Levy, and P.R. Carlson 1980 Map showing Holocene sedimentation rates in the northeastern Gulf of Alaska. U.S. Geo- logical Survey Miscellaneous Field Studies Map MF-1170. 1 sheet (1:500,000). Molnia, B.F., T.J. Atwood, P.R. Carlson, A. Post, and S.C. Vath 1984 Map of marine geology of upper Muir and Wachusett Inlets, Glacier Bay, Alaska: sediment distribution and thickness, bathymetry and interpreted seismic profiles. U.S. Geological Survey Open-File Report 84-632. 3 sheets (1:40,000). Moore, G.W. 1967 Preliminary geologic map of Kodiak Island and vicinity, Alaska. U.S. Geological Survey Open-File Report 67-271. 1 sheet (1:250,000). Muench, R.D. andJ.D. Schumacher 1980 Physical oceanographic and meterological conditions in the northwest Gulf of Alaska. NOAA Technical Memorandum ERL PMEL-22. 147 pp. Muench, R.D., J.D. Schumacher, and C.A. Pearson 1981 Circulation in the lower Cook Inlet, Alaska. NOAA Technical Memorandum ERL PMEL-28. 26 pp. Nayudu, Y.R. 1964 Volcanic ash deposits in the Gulf of Alaska and problems of correlation of deep-sea ash depos- its. Marine Geology 1:194-212. Nelson, C.H., K.A. Kvenvolden, and E.C. Clukey 1978 Thermogenic gases in near-surface sediments in Norton Sound, Alaska. Proceedings of the Tenth Annual Offshore Technology Conference, May 8-11, 1978, Houston, Texas, Vol. 4. pp. 2623-2633. Orlando, R.C. 1984 Morphologic and sediment characteristics of bedforms in lower Cook Inlet, Alaska. M.S. Thesis, San Jose State University, San Jose, CA. 98 pp. Orlando, R.C. and E.A. Martin 1981 Grain size data compilation and parameters of sediment samples: lower Cook Inlet, Alaska, 1976 through 1979. U.S. Geological Survey Open-File Report 81-827. 389 pp. Palmer, H.D. 1981 Recent sedimentation, northeastern Port Val- dez, Alaska. Geo-Marine Letters 1:207-212. Pewe, T.L. 1975 Quaternary geology of Alaska. U.S. Geological Survey Professional Paper 835. 145 pp. Plafker, G. 1967 Geological map of the Gulf of Alaska Tertiary province, Alaska. U.S. Geological Survey Mis- cellaneous Geological Investigations Map 1-484. 1 sheet (1:500,000). Plafker, G. 1972 Tectonics. In: The Great Alaska Earthquake of 1964, Vol. 10: Geology. National Research Coun- cil, National Academy of Sciences, Wash- ington, D.C. pp. 47-122. Plafker, G. 1974 Preliminary geologic map of Kayak and Wing- ham Islands, Alaska. U.S. Geological Survey Open-File Map 74-82. 1 sheet (1:31,680). Plafker, G. and W.O. Addicott 1976 Glaciomarine deposits of Miocene through Holocene age in the Yakataga Formation along the Gulf of Alaska margin, Alaska. In: Recent and Ancient Sedimentary Environments in Alaska: Pro- ceedings of the Alaska Geological Society Symposium Held April 2-4, 1975, at Anchorage, AK. T.P. Mil- ler, editor. Alaska Geological Society, Anchorage, AK. pp. Q1-Q23. Post, A. 1976 Environmental geology of the central Gulf of Alaska coast. In: ERTS-1: a new window to our planet. R.S. Williams, Jr. and W.D. Carter, edi- tors. U.S. Geological Survey Professional Paper 929. pp. 117-119. Powell, R.D. 1980 Holocene glacimarine sediment deposition by tidewater glaciers in Glacier Bay, Alaska. Ph.D. Dissertation, The Ohio State University, Columbus, OH. 420 pp. Ceomorphoiocy, Sediment and Sedimentary Processes 141 Powell, R.D. 1983 Glaciomarine sedimentation in Glacier Bay, Alaska. In: Glacial Marine Sedimentation. B.F. Molnia, editor. Plenum Press, New York, NY. pp. 185-232. Pratt, R.M., K.F. Scheidegger, and L.D. Kulm 1973 Volcanic ash from DSDP site 178, Gulf of Alaska. Initial Reports of the Deep Sea Drilling Proj- ect18:833-834. Price, N.B. and S.E. Calvert 1973 A study of the geochemistry of suspended par- ticulate matter in coastal waters. Marine Chem- istry 1:169-189. Quinterno, P., P.R. Carlson, and B.F. Molnia 1980 Benthic foraminiferans from the eastern Gulf of Alaska. In: Quaternary Depositional Environ- ments of the U.S. Pacific Continental Margin. M.E. Field, A.H. Bouma, and LP. Colburn, editors. Pacific Section of the Society of Economic Pale- ontologists and Mineralogists, Bakersfield, CA. pp. 13-21. Rappeport, M.L. 1981 Studies of tidally-dominated shallow marine bedforms: lower Cook Trough, Cook Inlet, Alaska. Ph.D. Dissertation, Stanford Univer- sity, Stanford, CA. 323 pp. Reimnitz, E. 1966 Late Quaternary history and sedimentation of the Copper River Delta and vicinity, Alaska. Ph.D. Dissertation, University of California, San Diego, CA. 160 pp. Reimnitz, E. 1972 Effects in the Copper River Delta. In: The Great Alaska Earthquake of 1964, Vol. 6: Oceanography and Coastal Engineering. National Research Council, National Academy of Sciences, Wash- ington, D.C. pp. 290-302. Reimnitz, E. and P.R. Carlson 1975 Circulation of nearshore surface water in the Gulf of Alaska. In: Principal sources and dis- persal patterns of suspended particulate mat- ter in nearshore surface waters of the northeast Pacific Ocean. P.R. Carlson, TJ. Conomos, R.J. Janda, and D.H. Peterson, editors. Earth Resources Technology Satellite final report to National Aeronautics and Space Administra- tion. National Technical Information Service, E75-10266, Springfield, VA. 145 pp. Reimnitz, E. and G. Plafker 1976 Marine gold placers along the Gulf of Alaska margin. U.S. Geological Survey Bulletin 1415. 1 sheet (1:1.000,000) and 16 pp. Richards, A.F. 1962 Investigation of deep-sea sediment cores. II. Mass physical properties. U.S. Navy Hydro- graphic Office Technical Report 106. 146 pp. Richards, A.F. and E.L. Hamilton 1967 Investigations of deep-sea sediment cores. III. consolidation. In: Marine Geotechnique: Proceed- ings of the International Research Conference on Geo- technique held at Monticello, Illinois, May 1-4, 1966. A.F. Richards, editor. University of Illinois, Urbana, IL. pp. 93-117. Rosenberg, D.H., D.C. Burrell, D.V. Natarajan, and D.W. Hood 1967 Oceanography of Cook Inlet: with special ref- erence to the effluent from the Collier Carbon and Chemical Plant. Report No. 67-5, Institute of Marine Science, University of Alaska, Col- lege, AK. 80 pp. Royer, T.C.,J.L. Luick, and W.R.Johnson 1984 Temporal variations in the Alaska Coastal Cur- rent. Transactions of the American Geophysical Union 65:968. (Abstract only) Sackett, W.M. and G. Arrhenius 1962 Distribution of aluminum species in the hydro- sphere. I. Aluminum in the ocean. Geochimica et Cosmochimica Acta 26:955-968. Sangrey, D.A., E.C. Clukey, and B.F. Molnia 1979 Geotechnical engineering analysis of under- consolidated sediments from Alaska coastal waters. Proceedings of the Eleventh Annual Offshore Technology Conference, April 30-May 3, 1979, Houston, Texas, Vol. 1. pp. 677-682. Schmertmann,J.H. 1978 Study of feasibility of using Wissa-type piezometer probe to identify liquefaction potential of saturated fine sands. U.S. Army Corps of Engineers Waterways Experiment Station Technical Report S-78-2. 73 pp. SchubelJ.R. 1974 Gas bubbles and the acoustically impenetrable, or turbid, character of some marine sediments. In: Natural Gases in Marine Sediments. I.R. Kaplan, editor. Plenum Press, New York, NY. pp. 275-298. Schumacher, J.D. and R.K. Reed 1980 Coastal flow in the northwest Gulf of Alaska. Journal of Geophysical Research 85:6680-6688. Schwab, W.C. and H.J. Lee 1983 Geotechnical analyses of submarine landslides in glacial marine sediment, northeast Gulf of Alaska. In: Glacial-Marine Sedimentation. B.F. Molnia, editor. Plenum Press, New York, NY. pp. 145-184. 142 Physical Environment Sears, H.S. and S.T. Zimmerman 1977 Alaska Intirlidal Sutvey Atlas. National Marine Fisheries Service, Auke Bay, AK. 407 pp. Seed, H.B., R.J. Woodward, and R. Lundgren 1964 Clay mineralogical aspects of the Atterberg limits. American Society of Civil Engineers, Journal of the Soil Mechanics and Foundations Division 9()(SM4):107-131. Self, G.W. and A. Mahmood 1977 Assessment of relative slope stability of Kodiak Shelf, Alaska, using high-resolution acoustic profiling data. Marine Geotechnology 2:333-347. Sharma, G.D. 1979 The Alaskan Shelf: Hydrographic, Sedimentary, and Geochemical Environment. Springer-Verlag, New York, NY. 498 pp. Sharma, G.D. and D.C. Burrell 1970 Sedimentary environment and sediments of Cook Inlet, Alaska. American Association of Petroleum Geologists Bulletin 54:647-654. Sharma, G.D., F.F. Wright, J.J. Burns, and D.C. Burbank 1974 Sea-surface circulation, sediment transport, and marine mammal distribution, Alaskan continental shelf. NASA Report No. CR-139544, National Technical Information Service, Springfield, VA. 77 pp. Singh, J.P. and D.W. Quigley 1983 Valdez silts: a challenge in design of offshore facilities. In: Proceedings of the Conference on Geo- technical Practice in Offshore Engineering. S.G. Wright, editor. American Society of Civil Engineers, New York, NY. pp. 81-98. Swift, D.J.P., B.M. Molnia, and R.G.Jackson, U 1978 Intermittent structure in the atmospheric boundary layer made visible by entrained sedi- ment— example from the Copper River Delta, Alaska. Journal of Sedimentary Petrology 48:897-900. Tarr, R.S. and L. Martin 1914 Alaskan Glacier Studies. National Geographic Society, Washington, D.C. 498 pp. TefryJ.H. 1977 The transport of heavy metals by the Mis- sissippi River and their fate in the Gulf of Mexico. Ph.D. Dissertation, Texas A&M Uni- versity, College Station, TX. 225 pp. Tefry, J.H. and B.J. Presley 1982 Manganese fluxes from Mississippi Delta sedi- ments. Geochimica et Cosmochimica Acta 46:1715-1726. Terzaghi, K. and R.B. Peck 1967 Soil Mechanics in Engineering Practice. John Wiley and Sons, New York, NY. 727 pp. Thomas, R.H. 1979 The dynamics of marine ice sheets. Journal of Glaciology 24:167-177. Thomas, R.H. and R.R. Bentley 1978 A model for Holocene retreat of the west Ant- arctic ice sheet. Quaternary Research 10:150-170. Thomson, R.E. 1972 On the Alaska Stream. Journal of Physical Oceanography 2:363-371. Thrasher, G.P. 1979 Geologic map of the Kodiak Outer Continen- tal Shelf, western Gulf of Alaska. U.S. Geo- logical Survey Open-File Report 79-1267. 2 sheets (1:250,000). Turner, B.W., G.P. Thrasher, G.B. Shearer, and K.D. Holden 1979 Bathymetric maps of the Kodiak Outer Conti- nental Shelf, western Gulf of Alaska. U.S. Geo- logical Survey Open-File Report 79-263. 13 sheets (1:250,000). Varnes, D.J. 1978 Slope movement types and processes. In: Land- slides: Analysis and Control. R.L. Schuster and R.J. Krizek, editors. National Academy of Sciences, Washington, D.C. pp. 12-33. Visser, J.N.J. 1983 Submarine debris flow deposits from the Upper Carboniferous Dwyka Tillite Formation in the Kalahari Basin, South Africa. Sedimen- tology 30: 511-524. von Huene, R.E. 1966 Glacial-marine geology of Nuka Bay, Alaska, and the adjacent continental shelf. Marine Geol- ogy 4:291-304. von Huene, R.E. 1972 Structure of the continental margin and tec- tonism of the eastern Aleutian Trench. Geo- logical Society of America Bidletin 83:3613-3636. von Huene, R.E., J. Crouch, and E. Larson 1976 Glacial advance in the Gulf of Alaska area implied by ice-rafted material. Geological Society of America Memoir 145:411-422. von Huene, R.E., G.G. Shor, Jr., and R.J. Malloy 1972 Offshore tectonic features in the affected region. In: The Great Alaska Earthquake of 1964, Vol. 6: Oceanography and Coastal Engineering. National Research Council, National Academy of Sciences, Washington, D.C. pp. 266-289. Geomorpholocy, Sediment and Sedimentary Processes 143 von Huene, R.E., G.G. Shor, Jr., and E. Reimnitz 1967 Geological interpretation of seismic profiles in Prince William Sound, Alaska. Geological Society of America Bulletin 78:259-268. von Huene, R.E., G.G. Shor, Jr., andj. Wageman 1979 Continental margins of the eastern Gulf of Alaska and boundaries of tectonic plates. Amer- ican Association of Petroleum Geologists Memoir 29:273-290. von Huene, R.E., MA. Hampton, M.A. Fisher, D.J. Varchol, and G.R. Cochrane 1980 Map showing near-surface geologic structures of Kodiak Shelf, Alaska. U.S. Geological Survey Miscellaneous Field Studies Map MF-1200. 1 sheet (1:500,000). Whitney, J. W., W.G. Noonan, D. Thurston, A.H. Bouma, and M.A. Hampton 1979 Lower Cook Inlet, Alaska: do those large sand waves migrate? Proceedings of the Eleventh Annual Offshore Technology Conference, April 30-May 3, 1979, Houston, Texas, Vol. 2. pp. 1071-1082. Wilcox, R.E. 1959 Some effects of recent volcanic ash falls with special reference to Alaska. U.S. Geological Survey Bulletin No. 1028-N. pp. 409-476. Winkler, G.R. 1973 Geologic map of the Cordova A-7, and A-8, B-6, B-7, and B-8 quadrangles, Hinchinbrook Island, Alaska. U.S. Geological Survey Mis- cellaneous Field Studies Map MF-531. 1 sheet (1:63,360). Wright, F.F. 1972 Marine geology of Yakutat Bay, Alaska. U.S. Geological Survey Professional Paper 800-B. pp. B9-B15. Yeats, P. A., B. Sundby, andJ.M. Brewers 1979 Manganese recycling in coastal waters. Marine Chemistry 8:43-55. Seismicity, Tectonics, and Geohazards of the Gulf of Alaska Regions Klaus H.Jacob Lamont-Doherty Geological Observatory Columbia University Palisades, New York Abstract The Gulf of Alaska is one of the tectonically most active regions in the world. The Pacific Plate moves north-northwest at a rate of 5 to 7 cm/y relative to the North American Plate. This motion controls the tectonics, seismicity, volcanicity, and much of the morphology of the Gulf of Alaska. Subduction is the dominant force along the Aleutian Trench where the Pacific Plate is outlined by dipping seismic zones that range to depths of 250 kilometers. The plate descends beneath the Alaska Peninsula, Cook Inlet, Prince William Sound, and the Chugach-St. Elias Range, while a right-lateral transform motion combines with a small component of convergence to dominate the tectonics of the plate boundary that runs along the Queen Charlotte- Fairweather Fault system in Southeast Alaska. The overriding North American Plate is composed of distinct accreted terranes. The historic active accretion continues into the present by collision of the Yakutat Block with the Chugach terrane in the north eastern Gulf. Seismicity is concentrated on — but not limited to — the plate interface between the Pacific and North American Plates, with great earthquakes (Mw ^ 7.8) recurring at any given plate-boundary seg- ment about once a century. Some of the great Alaskan earthquakes are among the largest recorded on Earth, measuring magnitudes of up to Mw equal to 9.2 (e.g., the Great Alaskan Earthquake of 1964). Some great Alaskan earthquakes are highly tsunamigenic and thus can cause widespread devastation along Pacific coastlines in Alaska and as far away as Hawaii, California, and Japan. In addition, they cause regional damage as a result of shaking, faulting, subsidence, landslides, avalanching, seiches, and soil liquefaction both offshore and onshore. Moderate shallow earth- quakes pose a more frequent risk, but except in localized cases, are generally less damaging to man-made structures. The Aleutian and Wrangell volcano chains pose additional hazards. Tectonic, seismic, and volcanic activity pose unavoidable risks to development in the Gulf of Alaska region. The potential for damage from these hazards has — within certain limits — become spatially and temporally quantifiable. Although such assess- ments provide the public with new options for long-term hazard-mitigation, they also pose the dilemma of striking a balance between mitigation costs and the long-term benefits from those actions taken against rare but catastrophic losses. Introduction _ , , motions, seismicity, crustal deformation, and vol- The Gulf of Alaska is tectonically one of the most canism) dynamic environments on Earth. This chapter includes: • the hazards associated with the seismic and volcanic • an overview of the tectonic activity in the Gulf of activity Alaska • the challenges to human activity from tectonic hazards • the elements of the major tectonic processes (plate along the Pacific rim of Alaska. 145 146 Physical Environment The geographic region considered in this review extends from the Queen Charlotte Islands in the southeast to Unimak Pass in the northwest (Fig. 6-1). The discussion of hazards focuses on the coastal regions, but the plate- tectonic forces that drive the seismic and volcanic activities require a look beyond a narrow coastal strip. Both in terms of method and discipline, this contribution relies more on geophysics than geology. Geologic data are commonly constrained to near-surface observations. The sources of the tectonic processes, and especially of the major seismicity in the subduction zone are, however, deep- seated. Geophysical methods, with their capabilities to monitor deep-seated crustal properties and deformations, are therefore well suited. Yet, geologic and geodetic data and arguments can be crucial in removing ambiguities that are sometimes inher- ent in geophysical problems. For instance, some seis- mologists inferred from their analysis of global seismic data resulting from the giant 1964 Earthquake that a steeply southeast-dipping thrust fault had slipped. Plafker (1969), in a now classic paper, showed on the basis of geologic and geodetic data that a gently northwest-dipping thrust was the correct choice of the two possible solutions and equally com- patible with the seismic nodal-plane information. In this report, the author relies on geologic input where helpful or necessary. Because of the brevity of this survey we must select from the large number of topics covered in the literature. The object is to present a comprehensive rather than an exhaustive treatment of the topic. Omissions, whether inad- vertent or as a result of some bias, are inevitable. Overview of Tectonic Activity The Earth is a thermodynamically convecting 'machine'. It owes its tectonic characteristics (which are rather unique among planetary objects), to a cold outer layer only 100 km thick which acts as a thermal boundary layer. This cold, rigid, yet mobile lithosphere forms plates which overlie a hot ductile asthenosphere. Gravitational forces are the major forces that drive the dozen (or so) primary plates on Earth. The forces originate from mostly thermally controlled lateral density hetero- geneities both in the plates and in the mantle. Cold slabs of lithosphere sink into the hot mantle along the oceanic trenches and try to pull the attached plates along behind them. In return, the hot, partially melted mantle wells up beneath mid-oceanic ridges which are located at the trailing edges of the mobile plates. The melt solidifies into a young oceanic lithosphere. The ocean floor of a hot young oceanic plate stands above the older, cooler, and denser ocean floor, Figure 6-1 . Tectonic map of the Gulf of Alaska and adjacent regions with modifications after King's (1969) Tectonic Map of North America. Note that truncated channels on Zodiac Fan are only schematical to indicate turbidite transport direction. For actual chan- nel configurations, see Stevenson, Scholl, and Vallier (1983). SEISMICITY, I ECTONICS AND CjEOHAZAROS 14/ and thereby exerts a force in the direction of the age gra- dient that runs from young to old. The combination of ridge push and slab pull are the two most important driving forces for plate motions (Forsyth and Uyeda 1975; Chappie and Tullis 1977). Besides the driving forces, the rheologies (stress-strain interactions) between the plate and the mantle are also ther- mally controlled (Kirby 1983). For example, the plates' long- term elastic properties are largely dependent on their thermal structure. In an oceanic plate, the depth to a certain isotherm (e.g., 450C) increases as the square root of the plate's age (Fig. 6-2). The depth of this isotherm determines the elastic thickness of the plate. In materials with higher temperatures (at greater depths), stresses are released by ductile flow. At lower temperatures (shallower depths), stresses either cause elastic (reversible) strains, or else they are released by a sudden seismic failure when the shear strengths of the materials are exceeded. That is why earth- quakes are confined to the low-temperature, elastic-brittle zones of plates. In oceanic plates, the elastic zone thickness varies from about 10 to 40 km, whereas in continental plates, it can meas- ure up to 50, or even 100 km in old cratonic shields. Seis- micity thus delineates only the stressed zones within the lowest-temperature, brittle regions of the Earth. This is par- ticularly visible for instance, at Wadati-Benioff zones where cold slabs subduct into normally aseismic ductile mantle. Age of Oceanic Lithosphere (106 y) 40 80 120 160 200 Average Thermal - Mechanical Thickness Figure 6-2. Thickness of oceanic lithosphere as a function of age (based on various geophysical indicators). Open symbols describe the mechanically coherent thickness of the lithosphere as determined by seismic-velocity studies. Solid symbols define the depth of the elastic portion of the lithosphere. Superimposed on the data are computed iso- therms. The elastic thickness approximately tracks a 450C iso- therm. (Modified from various sources after Kirbv 1983.) In addition to the thermally induced density hetero- geneities in the Earth, there are a number of heterogeneous conditions based on contrasts in compositional density. When an oceanic plate is converging with a continental plate, the more mafic, denser oceanic plate almost always plunges beneath the more silicic, lighter continental plate. Once the oceanic lithosphere has started to subduct, it becomes colder and thus denser than the compositionally similar but hot asthenosphere. The resulting gravitational pull on the slab reinforces further subduction. In contrast, the subduction of the continental crust to any considerable depth is resisted because of the buoyancy caused by its inherent lower density. If an oceanic plate contains low-density bodies (e.g., con- tinental fragments, ocean plateaus, island arcs, or other low-density loads such as thick sediments), then these bodies also tend to resist subduction because of their buoy- ancy. Often they are sheared off from the denser portions of the subducting plate, then transferred and accreted to the overriding continental plate. This action leads to the accre- tion and the growth of continents. If light fragments embed- ded in the oceanic plate are large enough, they may cause collisional tectonics and orogenic mountain-building. All these processes play a prominent role in the present tectonics of the Gulf of Alaska, and have done so during the evolution of the entire formation of continental Alaska. Elements of the Tectonic Process Plate Motions The instantaneous motion of any rigid plate on a sphere (McKenzie and Parker 1967) can be described by a vector of rotation that has a pole position (latitude, longitude) and a rate (degrees/my). The motion of all the major tectonic plates on the Earth (about a dozen) can be described in an absolute frame of reference, or on the basis of the relative motions of pairs of plates. Minster and Jordan (1978) inverted seismic slip directions as well as magnetic and transform lineation data on a global scale for a set of major plates that were assumed to be virtually rigid. Their model (RM2) has been widely accepted as one of several that can approximate plate motions for the last five million years. Another model (RM1) is referred to later in this chapter (Minster, Jordan, Molnar, and Haines 1974). Figure 6-3 out- lines the three principal plates in the northeast Pacific along with the motion for those plates. The three plates discussed here are the North American (NAM), Pacific (PAC), and the Juan de Fuca (JF) Plates. Minor plates or platelets are omit- ted for the sake of simplicity. The three plates join in a triple junction (ridge/trench/transform) off the Vancouver- Queen Charlotte Islands shelf. The relative motion of the PAC-NAM along the Queen Charlotte-Fairweather Fault system (at rates of about 6 cm/y) is dominantly a right-lateral transform movement coupled with a small convergence component. At the Aleutian Trench, convergence domi- nates at rates reaching more than 7 cm/y near the Shum- agins and at Unimak Island. There is a transition region in the northeastern Gulf of Alaska where motion changes from transform motion to convergence. This leads to the com- plex tectonics discussed below. 148 Pin sic -\l Environment 180 500km Figure 6-3. Plate-tectonic map of the Gulf of Alaska showing the Pacific, North American, and Juan de Fuca plates, their absolute plate-motion vectors (solid arrows), and vectors of relative plate motions (open arrows). Large numbers next to arrows indicate motion rates (in cm/y) of model RM2 (see text). Fine lines on the PAC plate are magnetic anomaly patterns, offset by major fracture zones. The time scale (in millions of years) for the numbered magnetic anomalies is shown at upper right. Shaded areas represent the subducted oceanic lithosphere (note the fingering of subducted plates). The basemap is modified from Drummond (1981) with new data added. The Pacific Plate. Age Distribution. The ages of the Pacific Plate can be inferred from the magnetic lineations shown for the Gulf of Alaska in Figure 6-3. Magnetic linea- tions are remnant lines of equal magnetic-field compo- nents that were frozen into the oceanic crust as it formed at mid-oceanic ridges. Once these magnetic-field anomalies or polarity reversals are dated in a few places (e.g., by dating the oldest sediments overlying the oceanic basalts), then the magnetic patterns provide an excellent means to date any piece of ocean floor on the Earth that has this clear magnetic signature. The Pacific Plate presently forms along ridges shared with the Juan de Fuca Plate (Riddihough 1984), resulting in a young ocean floor off the Queen Charlotte Islands. Ages increase towards the northwest, reach ing more than 50 mil- lion years near Unimak Island. Several fracture zones strike east to west off Southeast Alaska and offset the generally N-S magnetic anomalies and isochrons. Note the change to E-W trending isochrons in the western Gulf, a feature known as the 'magnetic bight'. This feature is related to a former ridge/ridge/ridge triple junction (Byrne 1979). This pattern of isochrons reveals that, in general, the ages of the Pacific Plate in the Gulf of Alaska decrease from the open ocean towards the margin with the Alaskan continent. The pattern implies that the ridges that formed the Pacific Plate have long been absorbed into its northern and eastern margins (Atwater 1970; Byrne 1979). The leading edges of subducted Pacific slabs in the Gulf are younger than their up-dip portions. In fact, areas of close-to-zero-age Pacific Plate must have been subducted in the geologic past in a manner similar to that now occurring near the PAC/NAM/JF triple junction off Queen Charlotte and Vancouver Islands. Seamount Chains. Riding on the Pacific Plate are chains of sea mounts (Fig. 6-1) that seem to originate near the triple junction in the southeast and trend north-northwest, the direction in which their age systematically in creases (Turner, Jarrard, and Forbes 1980; Silver, von Huene, and Crouch 1974). Whether these seamount chains record the Seismicity, Tectonics and Geohazards 149 'absolute' motion of the Pacific Plate with regard to a fixed 'hot spot' depends on just how 'fixed' those generating hot spots were through time. Sediments and Zodiac Fan. Much of the Pacific Plate ocean floor in the Gulf of Alaska is blanketed with layers of ter- rigenous sediments (Fig. 6-4). These layers resulted from the erosion of the coastal ranges on the adjacent North American continental margin, and they are transported and deposited as turbidites. At the base of the continental slope of South east Alaska they can be up to 2 km thick (Ludwig and Houtz 1979). The origin of the voluminous sediments of the Zodiac Fan (see Fig. 6-1 for location) has been a persistent enigma. Their origin is difficult to reconstruct (Byrne 1979; Steven- son, Scholl, and Vallier 1983) because reconstructions depend on placing past configurations of the mobile bor- derlands of North America relative to the ocean floor, which has been subducted beneath or accreted to the North Amer- ican continent. Few data, therefore, exist to constrain the earlier configurations (von Huene, Keller, Bruns, and McDougall 1985). Subducted Portions of the Pacific Plate. In the northwestern, central, and northeastern Gulf, subducted portions of the Pacific Plate dip into the upper mantle (see Fig. 6-3). Their configurations to depths of 250 km can be determined by the presence of well-defined Wadati-Benioff zones of seis- micity that will be discussed later. In cases where descending slabs are suspected, but if present, behave aseismically, they can be only vaguely inferred from plate motions and some- times from associated volcanic arcs. The subduction zone in the Gulf of Alaska, beneath Gook Inlet, is characterized by one of the most gently dipping slabs in the world for depths shallower than 50 km (Jacob, Nakamura, and Davies 1977; Davies and House 1979). Below that depth, the dip of the slab increases and is comparable to global averages. The descending Pacific Plate may be torn into fingered segments. For instance, one segment is dip- ping northwest beneath Prince William Sound and Cook Inlet, while another appears to dip northeast beneath the St. Elias and Wrangell Mountains (Stephens, Fogleman, Lahr, and Page 1984). Perez andjacob (1980a) speculate that some subduction of the Pacific Plate may be initiated near the Queen Charlotte Islands, very close to the PAC/NAM/JF triple junction. There, if model RM2 is to hold true, a small component of convergence is required (see Fig. 6-3). If that convergence exists, a very obliquely subducting slab could be continuous at depth from near the triple junction in the vicinity of the Queen Charlotte Islands to beneath the Wrangell volcanoes. However, so far only the northernmost portion of the dipping slab has been observed seismically. The North American Plate. Accreted Terranes. One of the most important results of geologic research on the North American continent in the last decade is the realiza- tion that much of Cordilleran western North America — including most of continental Alaska — is made up of dis- tinct terranes. Each has its own characteristic stratigraphy and tectonic history (Jones and Silberling 1979; Coney, Jones, and Monger 1980; and Churkin and Eberlein 1977). Paleomagnetic data demonstrate that some of these ter- 60 55 165 155 145 135 125 Figure 6-4. Isopach map of sediments in the abyssal portions of the Gulf of Alaska. (Modified from Ludwig and Houl/ 1979.) Triangles indicate sites drilled by the Deep Sea Drilling Program. Barbed lines are on the side of lesser sediment thickness. Numbers indicate thicknesses in kilometers. For sediments on shelves, see compilations by Hampton, Carlson, Lee, and Feely (Ch. 5. this volume). 150 Physical Environment ranes have traveled thousands of kilometers — sometimes from near equatorial latitudes — at velocities compatible with present plate tectonic rates (Stone, Panuska, and Packer 1982; Irving 1979). In fact, the Wrangellia terrane in Alaska was one of the first terranes for which this discovery was made (Hillhouse 1977). Biostratigraphic studies have shown that sediments on now adjacent terranes originated in ocean basins with dis- tinctly different faunas and climatic affinities. Docking times of terranes can be inferred from overlapping strat- igraphic sequences, common igneous piercing or meta- morphic events, and rock magnetism that reveals periods of joint polar wanderpaths that follow times of separate paths. The Alaskan continental crust, despite a flurry of recent research, is far from thoroughly probed. Yet, studies are already revealing a bewildering number of complexly assembled terranes. Figure 6-5 shows some of the larger ter- ranes identified in the Gulf of Alaska borderlands. Most of the terranes are bound by clearly identifiable faults, and some, but not all, are active or reactivated. In fact, seis- mologic data show (see later sections in this chapter) that active accretion currently occurs. The Yakutat Block (Fig. 6-5) is being accreted to the North American continent by collision with the Chugach terrane (Lahr and Plafker 1980; Perez and Jacob 1980a; Bruns 1983, 1985; and von Huene et al. 1985). Recent Volcanism. In almost every segment where the North American Plate overrides the subducting Pacific Plate, the upper plate is pierced by volcanic activity that geo- metrically aligns closely with the 100-km iso-depth line of the Wadati-Benioff zone (where the latter is defined). The basaltic-to-andesitic magmas following tholeiitic to calc- alkaline differentiation trends appear to be fractionated from a parental magma very similar to the mid-ocean ridge basalts (MORB). However, in contrast to MORB, their geo- chemistry suggests that they fractionate from finite, closed- system batches of rising magma rather than from an open system with a replenishing supply of mantle material (Kay, Figure 6-5. Simplified terrane map of portions of southern Alaska (see text for sources). Shaded area labeled Jk is a region that is dominated by extensive Jurassic-Cretaceous flysch. Kay, and Citron 1982). It appears that magma is generated at a depth of about 100 km because at that depth, the advecting asthenospheric mantle comes in contact with volatiles ema- nating from the hydrothermally altered crust of the subduct- ing oceanic plate. Melting temperatures of mantle rocks are lowered by the presence of volatiles such as water. The most prominent subduction-related volcanic chains at the margins of the Gulf of Alaska are the eastern Aleutian arc and the Wrangell Mountains (Kienle and Swanson 1983a; Jacob et al. 1977; and Simkin, Siebert, McClelland, Bridge, Newhall, and Latter 1981). In Figure 6-6, the former can be seen to stretch from Unimak Island at the tip of the Alaska Peninsula into Cook Inlet where it straddles the Inlet's northwest shoreline. St. Augustine volcano actually emerges from within Cook Inlet. More than twenty Quater- nary or historically active volcanoes lie in this continental portion of the Aleutian arc. There are no volcanoes north- east of and beyond either Mount Spurr or Mount Hayes along the Cook Inlet segment, although the Wadati-Benioff zone at depth continues for another 300 km to a point beyond Mount McKinley and the Denali Fault. The Wrangell Mountains in the borderlands of the north- eastern Gulf contain at least five major volcanic edifices (Mounts Drum, Sanford, Wrangell, Blackburn, and Regal) plus the unnamed source of the White River ash near Mount Bona (Lerbekmo and Campbell 1969). These volcanoes seem to be related to the subduction of a separate slab of the Pacific lithosphere (see Fig. 6-3). The tectonic origin of the Mount Edgecumbe volcano — which is seated so closely to the Fairweather-Queen Charlotte transform fault — is uncertain (Perez and Jacob 1980a). It consists of bimodal mafic and felsic volcanic rocks rather than the andesites and basalts that characterize the Aleutian and Wrangell volcanoes. There is considerable volcanic activity in the coastal regions of British Columbia, in the interior of continental Alaska, and on the Bering Sea shelf. Some of the activity in southwest British Columbia is related to both the present and the past subduction of portions of the Juan de Fuca Plate system, but hot-spot and extensional tectonics may be involved for those volcanoes with alkali-basaltic magma affinity (Souther 1977). Extensional tectonics has also been proposed as associated with the widespread volcanic activity in the western interior of Alaska and the Bering Sea shelf (Nakamura, Jacob, and Davies 1977). Internal Deformation arid Diffuse Plate Boundary. In contrast to the rather rigid oceanic Pacific Plate, the North American continental plate bordering the Gulf of Alaska seems to undergo substantial internal deformation. Most aseismic deformation occurs in two places: 1) in the accretionary prism (Fig. 6-7), and 2) in young subduction complexes at the leading edge of the plate up to several tens of kilometers north of the Aleutian Trench (von Huene 1979; House and Jacob 1983). However, some segments of the eastern Aleu- tian Trench do not have extensive accretionary prisms at present (Plafker, Bruns, Winkler, and Tysdale 1982). Internal deformation of the more mature (>20 km- thick ) portions of the accreted fore-arc crust in the hanging wall above the main thrust zone often occurs coseismically, although Pavlis and Bruhn (1983) argue that aseismic ductile Seismicity, Tectonics and Geohazards 151 BO 56 52 ^ 150 — I- 140 130 Sailiord Drum** . WrangeU Blackburn Bon.i (Whin- River) Buldil Anvil, Cerberus, Sugarloaf (Semisopochnoi) 1 Davidof j Kasatoihi Pavlof Sisie: Hague Emmons Frosty Peak ^ Amak Walrus Isanoiski Peaks (Raggedy Jack)! Fisher Pogromni Chagulak Gilbert (Akun) Kisk2» J Adagak Segula'^ J Bobrof\ Little Sitkin \Gareloi \ \ lanaga, I akawangha .** **&££■ Kanaga 7j Ml. Moffet j / Amutka Great Sitkin Pyre Peak Vunaska \ Cleveland Sergief (Seguam) Herbert Koniuji \Carlisle Akutan Kliuchef \ \ Bogoslof. j Korovin \ \Uljaga_ •j^JJiSarichef \, Redo»bt./^f»gJ»j/d Diamna*) j- Kaguyak Augustine /^Kukak *'r'KKs L. Denison Novarupia I ~» .^^Snowy TV ^X (Martin \\ Jff X-Katmai f kejulik My /irident Ikinrck.. % _/ Magejk Jt •BeliliklLlgashik) Chiginagak.^ialagujk-? Aniaktfiak* JYamarni^ 'Black Peak (Purple lake) \ efiiaminof Kupreanof 6 grz Pavlof, Double Crater ^r^.Dutton Roundtop Mountain - Westdahl Shishaldin Table Top xMakushin Okmok, I ulik Recheschnoi Vsevidof Tana, Kagamil 80 56 180 170 160 140 Figure 6-6. Map of Quaternary volcanic centers in the Aleutian arc and southern Alaska. (Modified from Kienle and Swanson 1983a. Figure 6-7. Multi-channel seismic reflection record (time section) across the trench slope northeast of Kodiak Island (see inset for profile location). Note the folds and the faults near the Lower Slope, at the leading edge of the accretionary prism. Numbers near vertical bars indicate layer velocities (km/s) derived from refraction studies. Vertical exaggeration is x 5 at the sea-floor. (Modified from von Huene, Fischer, and Bruns 1979.) 152 Physical Environment flow plays an important role. For instance, Plafker (1969) reports subsidiary faulting on Montague Island during the March 27, 1964 Alaskan earthquake. Internal deformation in submarine basins on the continental shelf of the north- ernmost Gulf of Alaska are documented by Bruns (1979, 1985). The Chugach-St. Elias Range is internally folded, faulted, and uplifted (Plafker 1967) as a result of its collision with the Yakutat Block that rides partly with the Pacific Plate (Lahr and Plafker 1980; Perez and Jacob 1980a; and Bruns 1983). Farther inland (see Fig. 6-1), recent strike-slip and/or some dip-slip motion is observed on the Castle Mountain, Denali, Totschunda, and several lesser faults in the Alaska/ Canada border regions (Plafker 1985, 1986; Plafker, Hud- son, and Richter 1977; Brogan, Cluff, Korringa, and Slem- mons 1975; Sieh 1981; Detterman, Plafker, Hudson, Tysdale, and Pavoni 1974; Richter and Matson 1971; Eisbacher and Hopkins 1977; and Clague 1979). Therefore, the entire rela- tive motion of the PAC/NAM Plates cannot be attributed to a single sharply defined plate boundary. Lahr and Plafker (1980) have taken this fact into account and proposed a model that incorporates a secondary plate boundary that extends as far north as the Denali Fault and the Alaskan Range (Fig. 6-8). In reality, however, strain relief may be even more widely distributed in southern and central Alaska. A Or Denali Fault Wrangell Volcanoes 50- 100 Rupture l-Zone-H I M -Yakutat Block- Transition Wrangell Block - -Main Thrust - Pacific Plate Figure 6-8. Model for present-day crustal deformation along PAC-NAM Plate boundary in southeastern Alaska (after Lahr and Plafker 1980). Top: Map view with estimates of plate- motion rates (circled numbers, in cm/y) of the Pacific Plate, Yakutat Block, and Wrangell Block relative to the North Amer- ican Plate. Numbers next to paired vectors represent plate- motion rates across the indicated zones. Dot patterns are zones of surface outcrops of deformation and faulting. Bottom: Dia- grammatic profile of section A-B across northeastern Gulf of Alaska. Rupture zone is that of the St. Elias earthquake of Feb- ruary 28, 1979. No vertical exaggeration. No one understands from a quantitative standpoint why the overriding North American Plate apparently deforms internally more readily than the underriding oceanic plate. The higher heat flow from ongoing volcanism, inherited weaknesses along the boundaries of accreted terranes, and the differences in yield strength of silicic (continental) ver- sus the more mafic (oceanic) crust may all play an important role. Another, less likely possibility is that internal deforma- tion rates in the continental and oceanic plates are com- parable, but only on land can one readily observe the cumulative slip integrated over long periods of time. On the oceanic plate, it is not observable because evidence is sooner or later either subducted or obliterated by continuous sedi- mentation. Seismicity Major Seismicity and Seismic Gaps. Most of the rela- tive motion between the Pacific and the North American Plates in the Gulf of Alaska is relieved intermittently either by great thrust earthquakes along the Aleutian Trench or by strike-slip faulting along the Fairweather-Queen Charlotte Fault system. The largest recorded Alaska-Aleutian earth- quake occurred in 1964 in the Prince William Sound- Kodiak region and measured Mw equal to 9.2 on the moment-magnitude scale. The horizontal slip component for this thrust measured ~ 20 m (based on geodetic data that resolved only part of the total displacement field). The dip-slip component on one of the steeply dipping subsidi- ary faults (in Henning Bay on Montague Island) measured 7.9 meters. Dislocation-model calculations indicate that the combined horizontal and vertical components of motion on the main thrust zone may have amounted to an average slip of between 20 and 30 meters. Great Alaskan earthquakes generate tsunamis and seiches that in special circumstances produce coastal run-up heights of 30 meters. In one extreme case in 1958, a huge seismically induced landslide displaced a large amount of water in Lituya Bay, creating a vertical run-up that measured in excess of 500 meters! (Miller 1960). The locations where major plate-boundary earthquakes have occurred in Alaska since 1938 are shown in Figure 6-9 (from Sykes, Kisslinger, House, Davies, and Jacob 1981). Dur- ing this period of almost 50 years, major earthquakes have broken all but perhaps five segments along the entire 4,000 km plate boundary in the northern Pacific between South- east Alaska and Kamchatka. The dimensions of the rupture zones for all pre-1972 events were determined by Sykes (1971) by relocating the aftershocks of each main shock (Fig. 6-10). He pointed out that the aftershock zones closely abut each other with little overlap, and also noted that there are a few gaps in recent seismicity for major earthquakes. He sug- gested that these gaps should be likely sites for future large strain-relieving earthquakes. Since Sykes' 1971 study, two moderately large earthquakes have occurred in two of the identified gaps. The 1972 Sitka earthquake (Ms = 7.6) almost completely filled the gap left between the 1958 Fairweather-Lituya Bay earthquake in the north and the northernmost possible extent of the 1949 Queen Charlotte earthquake in the south. (There remains a Seismicity, Tectonics and Geohazards 153 170 180 170 160 150 140 130 Figure 6-9. Rupture zones of large earthquakes and seismic gaps in the Aleutians, southern Alaska, and off British Columbia for the period 1938 to 1984. (Modified from Davies, Sykes, House, and Jacob 1981; Sykes 1971.) Three well-identified seismic gaps and two possible seismic gaps are illustrated for recent occurrence of large earthquakes. Arrows indicate P AC-NAM relative plate motions. 180 170 Bering Sea North American Plate (NAM) Pacific Plate (PAC) 50 Commander Unalaska Shumagin Gap——) f?Gap?) |- -f Gap-) Vakataga ?Gap hGaPl I I M„ = 8.2, M,= 8.6 M =8.4 "7.2 kh7.6 H \i — 7 q \i —81 = M, 1960 1940 1920 1900 1880 Mw = 8.7 °^ ms = »....m, = ..0 ! M.-9J ^*7'5 M =g2 M =7.4 D— - -i •7.6 Mt = 9.3 M, = 8.3.M, = 8.4 8.2 7.9 „ _ - A _ _ h = 100km? ..."-•" 4V1*" -*■- "^ ?»7 7 '•8--3--^1 8.0 7.4 • '•' 1880 M, = = 9.1 1 — : u M„ = 7.7 | hxH MW = 8.1 = M, 8.2/^7.8 1860 1840 - 1858 " ~-M 1849 1854 = 7.5 ±0.7 1847-48 1844 ?]848? 1820 1800 7 Aug 1788— , 22Tull788 J2S2. 170 180 170 160 150 140 130 Figure 6-10. Top: Aftershock zones of earthquakes with M^7.4 for the period from 1925 to 1971 along the Alaska-Aleutian portion of the P AC-NAM plate boundary. (Modified from Sykes 1971.) Bottom: Space/time diagram of known historic and instrumental great earthquakes along the Alaska-Aleutian arc since 1788 (after Davies, Sykes, House, and Jacob 1981). The time intervals between earth- quakes at the same segment are the recurrence times used in Figure 6-11. Ms, Mw, and M, refer to surface wave, moment, and tsunami magnitudes, respectively. 154 Physical Environment possible unbroken northern portion in the 1949 aftershock zone where the main shock may not have fully ruptured the plate boundary. There were only a few isolated moder- ate-sized aftershocks that occurred in the north, but these were south of the after shocks of the later 1972 Sitka earth- quake.) The other major event since 1971 occurred in the Yakataga seismic gap. The gap was only partly filled by the February 28, 1979 St. Elias earthquake of magnitude Ms equal to 7.2 (Mw = 7.5) (Buland and Taggart 1981; Lahr, Stephens, Hasegawa, and Boatwright 1980; McCann, Perez, and Sykes 1980; and Perez and Jacob 1980b). Thus a major seismic gap presently exists in the northeastern Gulf of Alaska, between the 1979 St. Elias rupture in the east and the 1964 rupture zone of the great (Mw = 9.2) Prince William Sound earthquake (see Fig. 6-9) in the west. This Yakataga seismic gap stretches across the 150 km from Icy Bay to Kayak Island. Part of this gap ruptured last in 1899 (Fig. 6-10) and is thought to be capable of supporting a future earth- quake with a likely magnitude (Mw) of about 8.0 to 8.5 if restricted to a single rupture in the gap (McCann, Perez, and Sykes 1980; Perez and Jacob 1980a). The other major seismic gap in the Gulf of Alaska is located near the Shumagin Islands between the 1938 rup- ture (Mw = 8.2) in the northeast and the 1946 earthquake (Ms = 7.4) in the southeast (see Fig. 6-9). The 1946 event was highly tsunamigenic (Mt = 9.1-9.3) and its rupture zone and mechanism are poorly constrained. The history of great earthquakes and tectonic setting of the Shumagin seismic gap and vicinity have been discussed in detail by Davies, Sykes, House, and Jacob (1981). They conclude that this gap has a high potential for a great earthquake within the next few decades. The historic and instrumental data are not fully conclusive, but the Shumagin gap may not have rup- tured in a truly great earth quake since 1788 or 1847. A future great earthquake filling the entire gap is estimated by Davies et al. (1981) to measure about Mw equal to 8.4. An unlikely and extreme scenario would be if the rupture extended into the partly reloaded 1938 rupture zone and/or into the Unalaska segment, in which case these authors estimate that an event with a maximum magnitude of about Mw equal to 9.0 could occur. Great thrust earthquakes in the Aleutians rupture the plate boundary seismically to depths of probably not more than 40 or at most 50 kilometers. Inter-plate slip at larger depths is ductile on a time scale that may range from min- utes to decades. In contrast, the brittle-seismic rupture propagates usually at speeds of about 2.5 to 3 km/s, just below S-wave velocities. Thus, for example, the duration of propagation of the rupture front for a distance of more than 600 km during the 1964 Prince William Sound earthquake was of the order of three to four minutes. Of course, regional shaking lasted longer. Recurrence Periods for Large Earthquakes. Figure 6-10 (bot- tom) shows the space-time diagram of known earthquakes with magnitudes Ms equal to or greater than 7.4 for the instrumental (1897 to present) and historic (since 1788) peri- ods. Before 1900, this record is perhaps complete only for the largest events and for the segment between the Shum- agins and Kodiak that was sufficiently densely settled by Russian traders whose records have survived (Sykes et al. 1981; Davies et al. 1981). Excluding all events east of 140°W, near the transform segment of the plate boundary, Jacob (1984) used a subset of this historic and instrumental seismicity since 1788 to calcu- late a probability density distribution for recurrences of events (on the same plate boundary segment) with magni- tudes Mw equal to 7.8 and larger. He found that for these great events, recurrence times may be log-normally dis- tributed with an average recurrence of ~ 80 and a range ( ± 1 SD) that stretches from about 40 to 140 y (Fig. 6-11). These recurrence periods, especially for giant earthquakes (with moment magnitudes larger than Mw = 8.5), are highly uncertain. For the 1964 rupture zone, Plafker and Rubin (1978) used geologic studies to suggest recurrence periods of between 500 and 1,350 y for great thrust earthquakes large enough to form uplifted marine terraces on Middleton Island. The average slip during the 1964 event may have been on the order of 20 to 30 meters. If the average plate-convergence rate of about 6 cm/y for this plate margin is correct, it should take only about 300 to 500 y to restore the stresses on the 1964 rupture zone to essentially their pre-1964 levels. This forecast ignores any aseismic slip or tbe effects from lesser seismicity. Rupture Zones Gaps 1964 Unalaska Kamchatka 19651 1957 19461938 Yakataga I I Shumagin U 0 [l| I II 10 30 100 300 1000 Recurrence Period (y) Figure 6-11. Cumulative probability (top) for observed recur- rences of great earthquakes (M^7.8) in the Alaska-Aleutian arc between Kamchatka and Yakutat Bay since 1788 (incremen- tal curve) and fit of log-normal probability distribution to the data (smooth curve). Discrete probability density of the recur- rence periods is shown below. The mean recurrence period is 76 y; the range (based on ± 1 SD ) is 43 to 135 years. Note the probabilities that respective segments attained (in 1983) for rerupturing in a new great event; e.g., —60% in the Yakataga Gap, -70% for the Unalaska Gap, -90% for the Shumagin Gap, but only less than 5% for the 1964 and 1965 rupture zones. (Modified from Jacob 1984.) Seismicity, Tectonics and Ceohazards 155 Sykes and Quittmeyer (1981) and Perez and Jacob (1980b) suggest that if terrace formation is linked to nearby imbri- cate faulting in the thrust wedge above the main thrust zone, then not every great event on the main thrust will form a discernible marine terrace. This is because different imbri- cate thrusts may be activated by successive slip events on the main thrust. Despite the contrary evidence summarized by Plafker (1986), these authors maintain that recurrence times that are derived from marine terraces in such subduction environments may be overestimated when compared with actual recurrence periods for great earthquakes. Alter- natively, the historic seismic record for Alaska may be too short to provide accurate estimates for when to expect recurrence periods for the largest earthquakes. Recurrence periods for great earthquakes that have pre- dominantlv right-lateral slip on the Fairweather Fault are estimated to vary between 60 and 100 y (Plafker, Hudson, Bruns, and Rubin 1978). These estimates were based on Holocene geomorphic features and the slip during the 1958 (Ms = 7.7-7.9) Lituya Bay earthquake. ( )ccurrence-frequency relationships for moderate- and small-magnitude earthquakes (i.e., Mw^7.8) in various source regions near the PAC-NAM Plate boundary in Alaska are discussed bv Woodward-Clyde Consultants (1978, 1982) and by Jacob and Hauksson (1983). The data for these smaller events are consistent with the globally observed trend that as the magnitude decreases one unit, the earthquake occurrence-frequency increases by a factor of nearly 10 (corresponding to a so-called 'b-value' of — 1). Teleseismic Patterns. Karthquakes with magnitudes of M() equal to or greater than four are usually recorded at tele- seismic distances and reported by various agencies in cata- logs such as the Preliminary Determination of Epicenters (PDF.) published by the U.S. Geological Survey's National Earthquake Information Service (NEIS). Figure 6-12 shows an epicenter map for teleseismically located earthquakes since 1964. This map was taken from the PDF catalogs and indicates the following patterns: 1) A subdued activity persists in Southeast Alaska along the Queen Charlotte-Fairweather Fault zone. This seismicity is restricted to shallow depths ( < 40 km) con- sistent with little or no subduction. 2) Near the eastern edge of the Yakataga seismic gap (McCann etal. 1980) which is centered on 143°W ±1°, a cluster of seismicity is associated with the St. Elias earthquake (Ms = 7.2) of February 28, 1979 (Stephens, Lahr, Fogleman, and Horner 1980). 3) West of 145°W, both a strong activity level increase and an increase in the width of the seismogenic zone are associated with both the rupture and the after shock zones of the Prince William Sound earthquake of 1964 (Mw = 9.2) (Plafker 1969; Sykes 1971). There, the width of brittle contact between the two plates, as defined by shallow seismicity (<50 km deep), extends for more than 300 km landward of the trench (Jacob el al. 1977). 4) Down-dip of this wide, brittle, plate contact, a dipping Figure 6-12. Teleseismic epicenter patterns for seismicity in the Gulf of Alaska between 1964 and 1984 for earthquakes with M^5 and with epicenters at all depths (data from USGS-PDE files). 156 Phnmcal Environment seismic (Wadati-Benioff) zone extends from depths of 50 km to — 150 km beneath the central Alaska Range (Agnew L980), increasing to about 250 km beneath the Alaska Peninsula (1 lauksson, Armbruster, and Dobbs 1984). 5) West of" the 1964 rupture zone near 155°W, the seis- micitv since 1964 has been low in the 1938 rupture zone (Sykes 1971). The width of the shallow-plate con- tact narrows from 250 to 150 km (Davies and House 1979) and seismicity in the Shumagin seismic gap is restricted to a ring-like feature surrounding the gap (Davies rf al. 1981; Hauksson ^r//. 1984). 6) A similar, but less well-developed pattern of low seis- micity is repeated near Unalaska Island, in a possible seismic gap between the great earthquakes of 1946 and 1957 (House, Sykes, Davies, and Jacob 1981). 7) West of the continent-ocean transition (165° W) in the North American Plate, the brittle plate contact, as defined by shallow seismicity, narrows to a width of less than 100 km, which remains more or less constant for most of the oceanic portion of the Aleutian Island arc (House and Jacob 1983). The deepest earthquakes in the Alaskan arc occur at depths slightly less than 300 km (House and Jacob 1983). 8) A few scattered seismic events occur south and sea- ward of the trench. There events are associated both with flexural strains in the Pacific Plate as it approaches the trench, and with the load of the over- riding plate. 9) Scattered shallow seismicity in south-central Alaska occurs near the Denali, Totschunda, Castle Mountain, and less prominent faults, as well as in the regions sur- rounding the Wrangell Mountains and the Canadian border. The major shallow-depth teleseismic patterns on the pri- mary boundary between the NAM and PAC Plates reflect both the occurrence of aftershocks to recent great earth- quakes, and the quiescences that precede great earthquakes in seismic gaps. Thus, the shallow-seismicity patterns vary temporally with the earthquake cycle (Sykes 1971; McCann, Nishenko, Sykes, and Krause 1979). In contrast, the patterns of seismicity for the intermediate depth range (50 to 300 km) seem to correlate mostly with the presence (or absence) of dipping slabs of Pacific lithosphere (Fig. 6-3). Therefore, they suggest spatially more station ary patterns, although the possibility of temporal variations has been pointed out (House andjacob 1983). The deep seismicity (300 to 750 km) that is present in many other island arcs is absent in both the Gulf of Alaska and the Aleutian arc. This restriction of Alaska/Aleutian seismicity to depths shallower than 300 km is consistent with models that predict the thermal assimila- tion of the lithosphere into the mantle, given the rates of subduction (<7.5 cm/y) and ages (<50 my) of the subducted Pacific Plate in the Gulf of Alaska (Molnar, Freedman, and Shih 1979). Teleseismic hypocenter locations have random errors of about ± 20 km, and in subduction zones, they also often have an additional systematic mislocation bias of 20 to 40 km arc- ward, and tend to down-dip towards the descending slabs (Fujita, Engdahl, and Sleep 1981; House and Boatwright 1980; and Hauksson 1985). Because of these errors, it is advantageous to use data from local seismic net works to resolve detailed tectonic features in the seismicity. The next section discusses the results from several such networks that have been operated in the Gulf of Alaska during the last dec- ade. Seismicity from Locally Operated Seismic Networks. Except for short periods of aftershock observations (Page 1973, 1975), there have been very few local seismic stations operating in Southeast Alaska that could improve the seismic coverage beyond the coverage already available through teleseismic methods. During OCSEAP-sponsored studies, extensive local seismic monitoring was carried out by the USGS (Lahr and Stephens 1983) in the northeastern Gulf of Alaska, by the University of Alaska in the Kodiak-Shelikof Strait- Lower Cook Inlet region (Pulpan and Kienle 1981; Pulpan and Frohlich 1985), and by Lamont-Doherty Geological Observatory in the Shumagin Island-Alaska Peninsula region (Jacob and Hauksson 1983). Other networks, not dis- cussed here, have been operated farther west in the Aleutian arc on Unalaska Island (Jacob and Boyd 1985), and on Adak and Amchitka Islands (Frohlich, Billington, Engdahl, and Malahoff 1982; Engdahl 1977). NEGOA-Wrangell Seismic Zone. Seismicity detected by the USGS-operated network (centered on the Yakataga seismic gap in the northeastern Gulf of Alaska [NEGOA]) has revealed an important tectonic feature that had not been previously discernible from teleseismic data: a seismic Wadati-Benioff zone that dips beneath the Wrangell Moun- tain volcanic chain (Stephens et al. 1984). Figure 6-13 (top) shows a subset of the hypocenters located by this network, and Figure 6-13 (bottom) displays the vertical section along the hinged profile A-A'-A". This section clearly reveals a band of seismicity that starts at the base of the continental shelf at depths between 10 and 30 kilometers. It reaches depths of 25 to 35 km beneath the crest of the Chugach-St. Elias mountain range (beneath A'), steepens its dip north- east of the surface trace of the Border Ranges Fault, then moves down to depths of 85 km beneath the southeast edge of the Wrangell volcano. A down-dip extension of the cen- ter of the inclined seismic zone would reach a depth of about 100 km beneath the crest of the Wrangell volcanoes. These features strongly suggest that a dipping slab of lithosphere descends with a northeast dip beneath the Wrangell mountains. The far-reaching tectonic implica- tions of this important finding are discussed later in this chapter. Another significant feature visible in Figure 6-13 (top) is the shallow- and intermediate-depth seismicity that was located by the regional seismic network both in the upper Cook Inlet and in the Prince William Sound segment of the Aleutian arc-trench system. This seismicity is sharply trun- cated towards the northeast along a line labeled RM1. This line is a segment of a small circle around a pole of rotation for the relative motion of both the PAC and NAM Plates (Minster et al. 1974). It could be visualized as a trajectory of a point fixed to the PAC Plate as it moves north-northwest and down beneath the edge of NAM Plate. The sudden drop-off in seismicity to the northeast of this line opens the Seismicity, Tectonics and Geohazards 157 EPM e \ i i ks 64 155 l3&-,6* Projk in) Hv enters NNE A Wrangell Volcanoes Border Ranges Fault SSW A" 300 Distance (km) Figure 6-13. Seismicity located by the USGS regional seismic network in the Gulf of Alaska for the period 1980 to 1982 for magnitudes equal to or greater than 2. (Modified from Ste- phens et al. 1984.) Top: Map of earthquake epicenters at three depth ranges. See text for information on RM1 line. Bottom: Projected earthquake hypocenters along a section (A- A'-A") through the Wrangell Benioff zone. No vertical exaggeration. possibility of a tear (see Fig. 6-3) or of some other discon- tinuity (e.g., a compositional, thermal, or age contrast) in the descending plate — a discontinuity whose origin is intri- guing but as yet unexplained (Stephens et al. 1984). For later comparison with other seismic cross sections farther west in the Gulf, we note the position and depth of the so-called aseismic front. This aseismic front is the locus at which the dipping seismic zone peels away from the brit- tle seismogenic portion of the overriding plate, leaving a wedge of the mantle aseismic between the two plates. In the NEGO A- Wrangell section of the PAC-NAM plate bound- ary, this aseismic front is at a depth of only 30 km, just north of and beneath the Border Ranges Fault (Fig. 6-13 bottom). The Cook Inlet-Kenai-Kodiak Sections. The University of Alaska operated a regional seismic network on portions of the Alaska Peninsula, on Kodiak Island, in lower Cook Inlet, and on the Kenai Peninsula with some overlap and sharing of stations with the USGS network to the east. Published analyses of these network data (Pulpan and Kienle 1979; Kienle, Swanson, and Pulpan 1983; Kienle and Swanson 1983a; and Pulpan and Frohlich 1985) focus both on seis- motectonics and volcano seismicity. Various hypocenters (Fig. 6-14) and three cross sections (A-A\ B-B', and C-C) (Fig. 6-15) traverse the Kenai Penin- sula as well as Afognak and Kodiak Islands, respectively. These are the major geographical features in the center of each section. The sections are oriented normal to the local strike of the Wadati-Benioff zone. The direction of the pro- file nearly coincides with the PAC-NAM plate-motion vec- tor for the Kodiak section C-C, but trends more westerly (rotated counterclockwise by about 24°) for the Kenai sec- tion A-A'. The salient seismotectonic features can best be seen on the three vertical sections. A seismic Wadati-Benioff zone is well developed in all these sections to depths of about 200 kilometers. The thick- ness of the dipping seismic zone is about 30 to 40 km, with no clear double-planed seismic zone (as discussed later for the Shumagin Islands section). The aseismic wedge is best defined in the Kenai section and shows the depth of the aseismic front at 40 km beneath the northeastern edge of the Kenai section — beneath Cook Inlet. The brittle thrust contact dips at a shallow angle between the two plates from the trench to the aseismic front. This contact is about 300 km wide in the Kenai, 280 km in the Afognak, and 250 km in the Kodiak section. Assuming that the initial depth of the thrust contact at the trench is at 10 km and that its final depth at the aseismic front is 40 km, then the average dip angles of the oceanic plate are only 5.7°, 6.1°, and 6.8° as it descends beneath the tapered accretion- ary prism of the fore-arc region. Even if we raise the initial 158 156 154 152 150 60 R - REDOUBT I - ILIAMNA A - AUGUSTINE D - DOUGLAS F - FOURPEAKED K - KAGUYAK • DEVILS DESK K - KUKAK S - STELLAR D - DENISON G - GRIGGS S - SNOWY N - NOVARUPTA K - KATMAI T - TRIDENT M - MAJEIK M - MARTIN K - KEJULIK U - UKINREK P - PEULIK K - KIALAGVIK — , C - CHIGINAGAK \./ Y - YANTARNI A - ANIAKCHAK 56 Figure 6-14. Seismicity located by the University of Alaska regional seismic network in the Cook Inlet/Kodiak/Kenai region for the period July 1977 to June 1981. Depth coding of earthquakes is A: 0 to 25 km; B: 26 1 o 50 km; C: 51 to 100 km, etc., in 50-km steps. Contours of upper surface to Benioff zone show the northwest dip of the descending Pacific lithosphere. Note the deviation from the 100-km depth contour of vol- canoes (bold face letter symbols) in the Katmai region. (Modi- fied from Kienle et al. 1983; Kienle and Swanson 1983a.) 158 Physical Environment Kenai Peninsula Transect I 100 a 200 A lliamna A' * A * Mainland kenai Coo* hllrl I'ypinsiila \la>ka r;«//o/ w«.*« Aseimic Wedge Afognak Island Transect I 100 x H Q 200 Kourpeakcd A Shehko/ S/rai< Afognak I. B' Gulfof Alaska North American P,ate *#&? mi Aleutian Trench 4400m x»c Kodiak Island Transect c; if Ukinrek Kejulik Shelikof 0 - S 200 J ▲ A Katmai Slrail Kodiak I. Gulfof Alaska ■ <>y ■«■■. '1 ■*•*.«■■■ Aleutian Trench 5200m -100 0 100 200 300 400 Distance (km) Figure 6-15. Cross sections A-A' (Kenai), B-B' (Afognak Island), and C-C ' (Kodiak Island) with hypocenters projected onto sections (refer to Figure 6-14 for section locations). The absence of seismicity on the main thrust zone is partly real and partly due to poor station distribution toward the trench. No vertical exaggeration. depth of the thrust zone at the trench to 5 km (i.e., to the top of sediments, rather than of the oceanic basement), the aver- age dip-angle of the thrust contact (to a depth of 40 km) would still only be 6.1°, 7.1°, and 8.0°, respectively, for sec- tions A-A' through C-C. These values are in remarkable agreement with, albeit slightly lower than, the 9° dip of the thrust fault derived by Savage and Hastie (1966) when they interpreted geodetic measurements of crustal deformation during the 1964 Earthquake. This very shallow dip makes the Gulf of Alaska one of the widest subduction zones in the world. Since the moment of earthquakes is a function of their widths (Sykes and Quitt- meyer 1981), this zone is capable of truly giant thrust earth- quakes as exemplified by the Mw equal to 9.2 earthquake of March 27, 1964, which probably broke up-dip for the full 250- to 300-km-wide thrust zone. A peculiarity of the Kenai section (A-A') is the very high level of seismicity in the Wadati-Benioff zone beneath Iliamna volcano, compared with the segments of Wadati-Benioff zone located to the southwest, beneath Kat- mai. This high activity also stands out on the epicenter map (Fig. 6-14). These activity level differences persist into the higher teleseismic-magnitude range (Fig. 6-12), and last for longer periods of time . The teleseismic activity spans almost two decades, while the network data cover only the four years from July 1977 through June 1981. During periods of volcanic quiescence, few shallow crustal earth quakes are associated with volcanoes. In sec- tion C-C we note some shallow crustal activity, which coin- cides in time and space with the sudden formation of the Ukinrek Maars in 1977 (Kienle, Kyle, Self, Motyka, and Lorenz 1980). Shumagin Islands Section. A seismic network has been oper- ated by the Lamont-Doherty Geological Observatory in both the Shumagin Islands and the outer Alaska Peninsula since 1973. The network is centered on the Shumagin seis- mic gap (Davies et al. 1981). Salient results from the analyses of network data were as follows: 1) A double-planed dipping seismic zone at depths below 70 km was found with an unusual pattern of down-dip tensional focal mechanisms in the upper plane. 2) Strong compression across the arc can be inferred from strike-slip mechanisms in the overriding plate; both these results imply strong compressive coupling between the converging PAC-NAM Plates (Reyners and Coles 1982). 3) The locked main thrust zone, which is expected to rup- ture in an impending great Shumagin earthquake, is at present seismically rather quiescent. 4) Very high stress concentrations are found at a depth of 40 km near the aseismic front. This was indicated by a few high-stress-drop events with magnitudes of about Mb equal to 6 (House and Boatwright 1980). 5) A burst of subcrustal seismicity was associated with a geodetically detected slip event and an unusual paucity of eruptive activity from the nearby Pavlof vol- cano, all consistent with an inferred ~ 80 cm down- ward slip of the descending Pacific Plate at depths of between 25 and 80 kilometers. The unusual event took place over a one- to two-year period during the period 1978 to 1980 (Beavan, Hauksson, McNutt, Bilham, and Jacob 1983; Beavan, Bilham, and Hurst 1984). This deep-seated event is inferred to have brought the locked shallower portion of the main thrust zone closer to failure. The spatial distribution of the Shumagin network seis- micity is shown in map view (Fig. 6-16) and in two cross- sectional views (Fig. 6-17) (from Hauksson et al. 1984). The figures show 1) the concentration of seismicity next to the aseismic front, 2) the down-dip end of the shallow thrust zone, and 3) the relative quiescence of the shallowly dipping portion of the thrust towards the trench. The width of the thrust zone between the trench and aseismic front at 40 km depth is about 140 km; hence the dip of main thrust is 12 to Seismicity, Tectonics and Geohazards 159 Figure 6-16. Seismicity located by the Lamont-Doherty regional seismic network in the Shumagin Islands and vicinity of the eastern Aleutian arc for the period 1973 to 1981. Three- -letter symbols and triangles indicate network stations, sun symbols represent volcanoes. Section A-A' is used for project- ing hypo-centers in Figure 6-17. (Modified from Hauksson, Armbruster, and Dobbs 1984.) 14°, depending on either a 5- or a 10-km starting depth at the trench. These dip values are almost twice those for the Kenai section of the 1964 rupture-zone, and the width of the thrust is almost half of that for the Kenai section of the same zone. More recently, Hauksson (1985) used 3-dimensional seis- mic-ray tracing to correct the systematic hypocenter mis- location of events in the deeper portion (> 100 km deep) of the Wadati-Benioff zone. He found that at depths from 80 to 250-300 km, the Wadati-Benioff zone dips at a constant angle of 45° and the associated cold slab of dipping lithosphere has a 7% higher P-wave velocity than the sur- rounding hotter mantle. Crustal Deformation Focal Mechanisms. An earthquake releases strain by slip across a fault under stress, resulting in a four-lobed radiation pattern for the seismic compressional (P) waves. The polarities of P waves can be separated into four quad- rants by a set of two orthogonal nodal planes. Two quad- rants contain compressional (outward directed) P-wave motions and the other two quadrants contain dilatational (inward directed) motions. A projection of a focal hemi- sphere (lower or upper) is known as a focal mechanism (Fig. 6-18). The quadrants with compressional-wave arrivals contain the T (tensional) axis, while those quadrants with the dilatational arrivals contain the P (pressure) axis. To determine which of the two nodal planes is the fault plane, one must use circumstantial evidence, such as aftershock alignments, or kinematic and geological arguments (see Introduction). The lower-hemisphere projections of focal mechanisms for a set of teleseismic earthquakes in the Gulf of Alaska are shown in Figure 6-1 8 (afterjacob and Perez 1981). The solid quadrants contain compressional arrivals (and the T axis), open quadrants contain the dilatational arrivals (and the P axis). Mechanisms with half-tone shading are for Wadati-Benioff zone events (^50 km deep). All others are for shallower events. There are essentially four types of mechanisms in this set: 1 ) Normal faults associated with flexure in the downgoing shallow portion of the Pacific Plate, both at or near the trench, and beneath Kodiak Island and the Kenai Pen- insula (nos. 1,2,3,14,17,18). Aii Hypocenters 1973-1981 Shumagin Network 300 Better Located Events o 300 Figure 6-17. Depth profile along section A-A' showing hypoc- enters in the Shumagin Islands region. Symbol size is keyed to magnitudes. Top: All hypocenters recorded between 1973 and 1981. Bottom: Only better located events are plotted. Note dou- ble-planed seismic zones at depths between at least 60 and 120 kilometers. Lack of events toward trench is real and appears related to relative seismic quiescence of main thrust zone in the Shumagin Seismic Gap (see Figure 6-16 for location of section and data source). 160 PlI-isK M EnUKONMFNT Fault 170 Inferred fault A Volcanoes # Volcanic vents 160 Figure 6-18. Earthquake focal mechanisms in the Gulf of Alaska and adjacent interior Alaska. Lower hemisphere projections; shaded quadrants contain ray directions with compressional P arrivals, open quadrants contain dilatational P arrivals. Solutions with solid shading are for shallow events (depths ^ 60 km), those with tonal shading are for events with depths equal to or greater than 60 kilometers. Note strike-slip solutions (nos. 11,12,16, and 23); thrust solutions (nos. 4-6, 15, and 19-22); normal faulting (nos. 1-3, 13, 14, 17, and 18) and down-dip tensional solutions in the descending slab (nos. 7- 10). Based on unpublished data byjacob and Perez (1981) and Suarez et al. (1984). 2) Thrust faults in which the subhorizontal nodal plane is assumed to be the plane of faulting. These events occur on the main thrust zone beneath the active mar- gin anywhere between Cross Sound (57°N, 136°W) and the Shumagins. These thrust solutions reflect, with few exceptions (nos. 21,22), the basic PAC-NAM convergence (nos. 4,5,6,19,20). 3) Right-lateral strike slips (in Southeast Alaska along the Queen Charlotte-Fairweather Fault) reflect the PAC- NAM transform motion (no. 23). 4) Down-dip tensional stresses in the descending Pacific lithosphere (nos. 7,8,9,10) found in the Wadati- Benioff zone beneath the upper Cook Inlet and adja- cent volcanic arc. Seismicity, Tectonics and Geomazards K,l In the Alaska interior, we note a south-to-north transi- tion that runs from thrusting (no. 15) near Mount McKinley, to a strike slip near and around Fairbanks (nos. 11,12), to dominant normal faulting (no. 13) associated with apparent extension and alkali basalt volcanism on the Seward Penin- sula, in western Alaska, and on portions of the Bering Sea shelf. The above examples are only a representative subset of a large number of fault-plane solutions obtained during many different studies using teleseismic data (Tobin and Sykes 1968; Chandra 1974; Perez and Jacob 1980a,b; Hasegawa, Lahr, and Stephens 1980; Gedney 1970; Stauder and Bollinger 1966; Stauder 1968; and House and Jacob 1983). Other fault-plane solutions were derived using microseismic earthquake data (Stephens et al. 1980; Reyners and Coles 1982; and Hauksson et al. 1984). The tectonic inferences from these focal mechanisms are discussed next. Seismic Slip Vectors and Tectonic Implications. Earthquakes both delineate active faults and reveal the sense and direction of slip on those faults. Figure 6-19 shows the slip vectors for a set of earthquake mechanisms in the Gulf of Alaska in comparison with slip vectors inferred for P AC-NAM Plate motions. The comparison demonstrates how well seismic slip on the Queen Charlotte-Fairweather Fault system during earthquakes (nos. 1-4) coincides with 156 152 148 140 136 Figure 6-19. Seismic slip vectors (determined from focal mech- anisms illustrated in Figure 6-18; Perez and Jacob 1980a) plot- ted on a tectonic sketchmap showing major tectonic terranes. Seismic slip vectors (solid arrows) show the direction of motion of the crust that is attached to the underriding Pacific Plate (rel- ative to the crust attached to the overriding North American Plate). Xote the general coincidence of the seismic slip direc- tions with computed slip directions (open arrows) inferred for the PAC-XAM plate motion model RM2 of Minster and Jor- dan (1978). Right-lateral strike slip (nos. 1-4) occurs where slip vectors parallel the plate margin, and regular thrusting (nos. 8-10 and 18-24) occurs where vectors are at a high angle to the strike of the plate margin. Oblique thrusting (nos. 5-7 and 11-17) often occurs near the region where the motion of the Yakutat block complicates the slip patterns. Profile A-A' indi- cates the location of the section shown in Fig. 6-20. the slip expected for PAC-NAM right-lateral motion . Simi- larly, the thrust earthquakes along the Alaska-Aleutian sub- duction zone (nos. 8-10 and nos. 18-24) show slip vectors that are close to those vectors for globally computed plate motions. In the northeastern Gulf, the terrane of the Yakutat Block both collides with and accretes to the North American continental margin (Lahr and Plafker 1980). There, some mismatch occurs between the seismically observed slip vectors and those slip vectors calculated for PAC-NAM Plate motions. These misorientations imply (Perez and Jacob 1980a) that the Yakutat Block is no longer attached to the Pacific Plate, but has started to thrust onto the oceanic portion of the Pacific Plate in a southwest direc- tion. The forces responsible for this thrusting may be very recent. The buoyant, semi-continental Yakutat Block may have started resisting further subduction beneath the Chugach-St. Elias ranges of the Alaskan Plate margin only during the last million years. Section A-A' (Fig. 6-20) illustrates the collision tectonics that characterize this continental margin. Subhorizontal detachment faults dip gently for distances of —100 km beneath the deformed margin. Near the seaward edge of the thrust belt, the subhorizontal detachment faults curve upward into more steeply dipping, imbricate, listric thrust faults. Inland, beneath the surface trace of the Border Ranges Fault, the detachment at depths of ~ 30 km curves downward into a steeply dipping master thrust. This curve coincides with what is most likely the crust-mantle bound- ary (Moho) of the subducting slab of Pacific lithosphere. The cross section suggests (based on limited data) that the Pacific Plate is presently underthrusting the Chugach-St. Elias range. The leading edge of the Pacific Plate is apparently plunging beneath the Wrangell volcanoes, whose Quatern- ary activity is related to deep magma generation resulting from a release of volatiles from the dipping slab into the adjacent, advecting mantle. The volatiles lower the melting point of the mantle rocks. It is uncertain whether the slab dipping beneath the Wrangell Mountains is genuine oceanic Pacific Plate that has underridden the Chugach-St. Elias range and/or the Yakutat Block. If it is not a regular oceanic plate, the sub- ducted portion of the Pacific Plate could once have belonged to a transitional continental lithosphere similar in structure to the present combination of Yakutat crustal block and its poorly known subcrustal lithosphere (Bruns 1983, 1985). In the former model, it is implied that both the Chugach-St. Elias range and the Yakutat Block are allochthonous to the Pacific lithosphere (Lahr and Plafker 1980; Perez and Jacob 1980a; and Stephens et al. 1984). The latter model, however, implies that the Yakutat Block (at least until recently) was autochthonous to, and an integral part of, the Pacific Plate (Bruns 1983, 1985). If Bruns' model applies, this Yakutat Block may only now be in the initial process of being detached from the subducting Pacific Plate (mechanisms no. 22 of Fig. 6-18; and nos. 5,6,7, and 13 of Fig. 6-19) because the block is colliding with the continental edge in the Chugach-St. Elias range. Figure 6-18 reflects a bias for the first model, but needs to be verified by future work. 162 Physical Environment A' iNurlh) - u. s b C 3 c 0 A N V (South) c be 'XI — _ W Q. (4* E- u a J3 — OP *-- Yakutat Block -*< 400 200 Distance (km) Figure 6-20. Schematic tectonic profile (section A-A' on Figure 6-19; Perez and Jacob 1980a) across the northeastern Gulf of Alaska from the abyssal Pacific (A) to the Yukon-Tanana terrane in the north (A'). Note that thrust solutions 8, 9, and 10 (same labeling as in Fig . 6-19) occur where the Pacific Plate and a down-dip extension of the Yakutat Block slip on a possibly multi-planed detachment beneath the Chugach/St. Elias mountain range which forms the leading edge and collisional boundary of the North American Plate. This tectonic profile assumes the oceanic Pacific Plate descends beneath the Wrangell volcanoes, a hypothesis which at this time is not proven (see discussion in text). Plate Slip Versus Plate Deformation. If plates were per- fectly rigid, they would slip steadily past each other without any deformation of either plate. If the two slipping plates were each perfectly elastic, they would still slip past each other without any permanent long-term deformation. But between slip events (earthquakes), the plates would take up elastic deformation that would completely rebound during earthquakes. For example, a plate boundary with 5-cm/y long-term motion would experience 10,000 earthquakes (of great magnitudes), each with ~ 5-m slip to move the two plates 50 km past each other in one million years (the dura- tion of the Pleistocene). Still, the two plates would be vir- tually undeformed internally if they behaved perfectly elas- tically throughout the 10,000 great earthquakes. Obviously, this is not the case. The slip between the plates is not neatly confined to a single master fault, because the finite strength of the rock in either plate causes secondary faulting. It is this secondary faulting, associated with folding and ductile shearing, that creates the tectonic styles and much of the land forms. Magmatism, erosion, redeposition, and iso- stasy do the rest. The more that plate slip is diffused away from a single master fault between plates, the more tectonics is imprinted into the plate margin. As more plate slip is con- fined to a single plate-boundary fault, there is an increase in elastic recover)' during the interseismic times between great earthquakes. However, deformation on secondary faults in either plate is not generally recoverable. This distinction is important in understanding the tectonic significance of the crustal deformations that occur during great Alaskan thrust earthquakes. Figures 6-21 and 6-22 illustrate this case for the Prince William Sound earthquake of 1964. Figure 6-21 (from Plafker 1969) shows in map view the regions of mostly recoverable uplift southeast of Kodiak Island and the Kenai Peninsula and the regions of mostly recoverable subsidence northwest of Kodiak Island and the Kenai Peninsula. Profile A-A' (insert) shows that the co-seismic vertical deformations were largely opposite in polarity to that of the preexisting topography/bathymetry. The long-wavelength surface deformation represents largely elastic (recoverable) strain. Figure 6-22 shows models that can satisfactorily explain the elastic long-wavelength deformations at the surface (away from the fault) in terms of slip (with amplitudes between 3 and 18 m) on the main thrust at depth. Superimposed on these major patterns are short- wavelength secondary patterns that reveal steep-angle sub- sidiary thrusting that cuts the surface of the fore-arc prism. The mostly irreversible deformation within the North American Plate during the 1964 event occurred as thrust motion both on the steep-angle Patton Bay Fault on Mon- tague Island and on comparable offshore faults. Most other effects on the NAM Plate are elastic rebound, and therefore do not represent permanent internal deformations within NAM. These are related to the slip on the master fault between the NAM Plate and the PAC Plate. Seismicity, Tectonics and Geohazards 163 142 154 150 146 142 Axis of uplift, dashed where inferred Axis of subsidence — 0 — Zero base contour a Epicenter of major aftershock (M > 6.0) Figure 6-21. Vertical crustal deformation associated with the Great Alaskan Earthquake of 1964 (Prince William Sound). Note hinge line of zero vertical motion straddling the south- east shores of Kodiak Island and the Kenai Peninsula that sepa- rates an area of uplift in the southeast from an area of subsi- dence to the northwest. (Modified from Plafker 1969.) The cumulative effects of irreversible deformation (by internal faulting in the NAM Plate) were exemplified in 1964 by the Patton Bay Fault . These effects can be seen elsewhere, as in the structures described by Bruns (1979, 1985) in the Yakataga shelf of the northeastern Gulf of Alaska (Fig. 6-23). Note the extensive offshore fold-and-thrust-belt with deeply infilled interfold basins (some have up to 5 km of thick young sediments). This offshore fold-and-thrust belt is formed above a main detachment by the internal shorten- ing of the overriding NAM Plate. The folding is driven by the underplating and collision of the Yakutat Block that, in turn, is partly attached to and driven by the Pacific Plate (Figs. 6-18 through 6-20) . Faulting and crustal deformation are not restricted to the leading edge of the NAM Plate, however. Lesser faulting and crustal deformation occur as far north as central Alaska (Figs. 6-1 and 6-8), with motion documented for the Castle Mountain, Denali, Totschunda, and several lesser faults. Present slip rates on these interior faults are believed to be less than 1 cm/y, although they were probably more active at one time. A new compilation of active faults of Alaska is presently being prepared (G. Plafker, U.S. Geological Sur- vey, pers. comm., 1985). When completed, it will constitute an important quantitative update of the older, mostly qualitative studies of crustal deformation in the Alaskan portions of the North American Plate. Indicators of Tectonic Stress. A regional compilation of the directions of maximum horizontal compression (°hmax) Dased mostly on volcanic stress indicators is shown in Figure 6-24 (Nakamura et al. 1977; Nakamura, Plafker, Jacob, and Davies 1980). A few data points are based on sur- face faulting. The figure shows that along the eastern Aleu- tian volcanic arc, the maximum horizontal stress is closely aligned with the azimuth of relative PAC-NAM Plate motion. This result is in close agreement with the previous observation that at least the eastern portion of this arc-trench system is under considerable compression, both from the accretion of terranes and from underthrusting across the unusually wide plate contact at the leading edge of the overriding plate. Along the Fairweather trans- form-fault system, both fault data point No. 1 and Mount Edgecumbe volcano data point No. 186 (Fig. 6-24) indicate a 45° clockwise-rotated trend of chmax with regard to both the northwest-trending plate boundary and the slip vector. This trend is to be expected for this right-lateral strike-slip regime. In central Alaska, a strike-slip regime dominates, with the ohmax direction fanning symmetrically out east and west from the 148° meridian. Nakamura et al. (1977, 1980) point out that in west central Alaska as well as on the Bering Sea shelf, this fanning takes on a more westerly trend for ohmax. There, ohmax coincides with the intermedi- ate stress axis (c2), implying a dominantly (north-south) 10m- Observed and inferred 5- displacement, 1964 earthquake 0 4&r A _X»-0 V c 0 100 200km -5- Patton Bay Fault A Slip:10m-^ y 0- 0- 77 3n\,4m, 7m ,11m < 18m Um 5m Slip: 3 - 18m (as shown) 50- 3m 4m 7m llm . lmi| 1 2.7m 5m Slip: 3 - 18m horizontal 1 — 2.7m vertical (as shown) 200 Cook Inlet 100 Middleton Island 200km Aleutian Trench figure 6-22. Comparison of observed and inferred profiles of surface displacements for the 1964 rupture zone. (Modified from Plafker 1969.) Three models (A, B, and C) are shown that try to explain the surface deformation with slip that is modeled on faults at depth. Model A is from Savage and Hastie (1966), and models B and G are from Stauder and Bollinger (1966). Note steep-angle subsidiary thrust emerging at Patton Bay. 164 Physical Environment Figure 6-23. Structures and basins of the thrust and fold belt in the Yakataga area of the northeastern Gulf of Alaska. (Modified from Bruns 1979.) Contours are based on multichannel seismic data and show configurations of isopachs of presumed Pliocene (?) strata. extensional regime favoring east-west trending normal faults (e.g., on the Seward Peninsula and Bering Sea shelf). The side projections of pressure (P) and tension (T) axes of earthquake focal mechanisms in the Gulf of Alaska are shown in Figure 6-25 along a northwest-southeast profile that crosses Kodiak Island. Note that for earthquakes at depths of 20 km and deeper, located on or near the main thrust zone, the P and T axes are not oriented vertically. Moreover, thrust and normal faulting solutions are very closely interspaced both in depth (Fig. 6-25) and in map view (Fig. 6-18 — solutions 1,2,3,17, and 18 are normal faults; most other nearby events represent thrust faults). Detailed seismic body-wave modeling (Suarez, Jacob, Perez, and Ghosh 1984) suggests that virtually all the normal faulting events are located ~ 5 km beneath the main thrust and inside the subducting oceanic Pacific Plate. The normal-fault events are located where downward bending of the plate creates tensional stresses in the upper portion of the downgoing slab. They are therefore equivalent to the extensional, normal-fault events commonly observed at the flexures of trenches and outer rises. The tectonic and rheologic implications of the close spa- tial coexistence of thrust events and normal-faulting events in the Gulf of Alaska subduction zone are not yet fully resolved. We surmise, however, that the normal-faulting, bending events beneath the thrust zone should not preclude the fact that net horizontal compressive stresses are being transmitted across this plate margin. Seismic and Volcanic Hazards Hazards are generated by both seismic and volcanic events. Seismic hazards originate either from direct seismic effects such as ground shaking, faulting, and subsidence or from indirect earthquake effects such as tsunamis (seis- mic sea waves), soil failure and liquefaction, landslides, avalanching, and seiches in semi-closed or closed bodies of Seismicity, Tectonics and Geohazards 165 Figure 6-24. Orientations of maximum horizontal stress derived from volcanic-stress indicators and recent surface faulting. (Modi- fied from N'akamura et al. 1977.) Note the parallel orientation of maximum horizontal stress with PAC-NAM plate-motion vector (open arrows) for most of the Aleutian arc. Also note fanning pattern in central Alaska (for details , see text). Numbers refer to identification of stress indicators as used by Nakamura et al. (1977). water. Volcanic hazards originate from lava-, pyroclastic-, and mud flows; debris avalanches; air-borne projectiles and ash; toxic rains and gases; explosive shock waves; and vol- canicallv induced earthquakes and sea waves. Seismic Hazards (1): Earthquake Recurrence Periods Great earthquakes are destructive but rare, occurring only about once a century at any given arc segment (Fig. 6-11). Smaller earthquakes pose a more frequent risk, gener- ally with less significant effects. Since a wide range of magni- tudes can contribute to seismic hazards, it is necessary to know the probability of earthquake occurrence as a func- tion of magnitude in any given area. The most common way to describe earthquake occur- rence frequencies is as a function of magnitude (illustrated by an example in Fig. 6-26). The description has the form logN = (A - bMw), where N is the cumulative number of earthquakes for all magnitudes Mw and larger. In order for this type of representation to be meaningful, it is assumed that earthquakes occur randomly, i.e., they are spatially and temporally independent of each other and thus conform to a Poisson distribution. The magnitude data for the Aleutian arc (Mw S; 7) anci for the period 1898 to 1982 are plotted as a function of Mw in Figure 6-26. The data show that -100 events with Mw greater than or equal to 7, but only two events with Mu greater than 9, occurred during 85 years within a 3,600 km arc between Kamchatka and Yakutat Bay. If the slope ('b-value') is preserved, and the A-value is staled down according to both the arc-length and the period of consid- eration, one would expect that in a 360-km-long arc (cen- tered on Cook Inlet or Anchorage) one event with a magni- tude of 7 or larger should occur every 8.5 years. But none has occurred there since 1964. In fact, no earthquake with a magnitude of 7 or larger has occurred within a distance of more than 1,000 km along the arc between Kayak Island and Adak (in the central Aleutians) for the 20-year period from 1966 to 1985. This is a quiescence for Mw events equal to or greater than 7 that falls a factor ~ 30 short of expected activity levels — if complete randomness did apply. An alternative model assumes that although earthquakes are not purely randomly distributed in time, a random component of background seismicity for both small- and moderate-magnitude earthquakes is superimposed on a non-random component for great earthquakes in each plate-boundary subsegment. In this model, the probability for the non-random great earthquakes (and related fore- and after shocks) is a function of time or phase within the seismic cycle. This means that probabilities for the occur- rence of great events are related to the time since the last great earthquake occurred at the plate-boundary segment in question. To define such a model, one needs to know the average periodicity of events, some statistical measure of deviation from this average, and the time since the last event. Such data were previously discussed in Figure 6-11 for various Aleutian arc segments. Taking both these data and the theoretical relationships (Jacob 1984), one can calculate the conditional probabilities for the occurrence of great earthquakes during the next x years in each previously ruptured zone or seismic gap. Fig- ure 6-27 displays the results of such calculations for the Aleutian arc, excluding the southeastern Alaska transform segment of the PAC-NAM Plate boundary. It shows the 166 Physicm Environment A. Geology, Hypocenters and Plate Outlines Aseismic Front Al.isk:i Peninsula Kudiak Island NVV Volcanic Front 100 Thrust earthquakes Normal faulting B. T Axes o 50 100 / - X /^ ^7 C. P Axes D. Slip Vectors o Distance from Aseismic Front (km) Figure 6-25. Seismic stress indicators in a cross section through the Kodiak region of the western Gulf of Alaska. (Modified from Jacob and Perez 1981.) A. Near-surface geology, hypocenters, and inferred plate outlines. The inclined dotted line represents the location of 1964 earthquake thrust fault inferred from geodetic data (Savage and Hastie 1966). B. Projected orientations of T axes. C. Projected orientations of P axes. D. Slip vectors. The insert in the lower right corner shows slip planes with an inferred stress system at the depth of the main thrust zone. Seismicity, Tectonics and Geohazards 167 s D z Period: 85 y Length: 3600 krn logN = A - bMv A = 7.85 ± 0.13 b = 0.85 ± 0.10 • Actual data ■ Inferred leve o Incomplete dat Moment Magnitude (Mw) Figure 6-26. Cumulative number of large earthquakes as a function of magnitude Mw for an 85-y period (from 1897 to 1983) for the Alaska-Aleutian arc between Kamchatka and Yakutat — with inferred relationship log N = A- bMw. Straight lines fit slope b and intercept A, and delimit the maximum error for A. (Modified from Jacob and Hauksson 1983.) range of conditional probabilities for a 10-y and a 20-y period (up to 1993 and 2003, respectively) and for two differ- ent statistical-model distributions of the recurrence times — for a log-normal (Fig. 6-11) and a normal distribu- tion (see Jacob 1984; Jacob and Hauksson 1983). Note that the calculated probabilities apply for great earthquakes (Mw > 7.8) only. These are the primary results from Figure 6-27: 1 ) Seismic gaps in the Shumagin and Yakataga segments of the Gulf of Alaska have high probabilities (30% to 99%) of rupturing in great earthquakes during the next two decades. 2) The 1938, 1946, and 1964 rupture zones have much lower rupture probabilities, decreasing in this order. 3) The relative contrasts in probabilities between differ- ent regions are significant, but the absolute proba- bility levels are poorly constrained and model depend- ent (Jacob 1984), and thus not too meaningful. Two seismic-exposure studies by Woodward-Clyde Consultants (1978, 1982) are the most comprehensive attempts to quantify seismic hazards in offshore Alaska. They used extensive statistical methods, but the data base available for these studies was not complete enough to fully take advantage of the potential of the methods. The 1982 study assumed a 'semi-Markov process' for the temporal and magnitude relationships for great earthquakes (Pat- wardhan, Kulkarni, and Tocher 1980). However, the data base available for the historic earthquakes at that time was not as complete as it is now. Even an improved historic data base (Jacob and Hauksson 1983) may be too limited (going back only 200 v in one section of the eastern Aleutian arc, and even less in most others) to warrant the more sophisti- cated approach. However, from a methodological point, the study by Woodward-Clyde Consultants (1982) is important since it considered separate statistics for the great earthquakes for the first time, and used purely random Poisson statistics loi the smaller-magnitude background activity. The latter wis locally adjusted to reflect the different levels of background seismicity in the tectonically distinct subregions of trench, fore-arc, dipping slab, and volcanic arc. The contributions from these tectonic elements were then combined with those from the great plate-boundary earthquakes, allowing computation of the combined source characterization in each area. A result from this approach will be discussed in a later section (in conjunction with Fig. 6-31). In summary, limited (but quantitative) statistical descrip- tions of seismic-source occurrences have recently become available for the Aleutian-plate boundary west of Yakutat Bay. These occurrences are expressed as a function of time, space, and magnitude. They include the concept of seismic gaps, or time-dependent probability for great earthquakes. 170 180 170 160 150 140 60 Mw °o = 7 8 o 9 o V Gap 60 50 / O i i 50 170 180 Ten Years 1983—1993 100 -i §5 80 t 60 3 40 170 160 150 140 03 i 20 Oh Twenty Years 1983—2003 100 CGap 1946 K Gap 1965 Zone 1957 Zone V S l ..1J< 193H 1964 Zone I 1 j\Gap illllkm 700km XOOkrn ■4 — -1- IIMIkn 350km 800km 200km 200km 150km Figure 6-27. Conditional probability for great earthquakes (Mw^7.8) along the Aleutian arc for a 10- and 20-y period. Map shows the geographical setting with seismicity (Mw^7) since 1897. Solid shading on probability graphs represents log- -normal distribution of recurrence times (see Figure 6-11); gray shading represents normal distribution. Note high proba- bilities in identified seismic gaps (from left to right ) near Kamchatka (K), Unalaska (U), Shumagins (S), and Yakataga (Y). (Modified from Jacob 1984. ) 168 Physical Environment For the Fairweather-Queen Charlotte transform boundary only qualitative assessments are presently available (Sykes 1971; McCann etaL 1979). They are practically non-existent either for the interior of Alaska or for areas outside the ( rulf of Alaska region on which this survey focuses. Even for the best-studied segments along the Alaska- Aleutian trench system, many details remain unresolved. These details include variations along the arc of average recurrence periods and the maximum possible magnitude of the largest earthquakes. It is unclear whether magnitudes are continuous between moderate- and maximum- magnitude earthquakes, or whether there is, in some sub- regions, a distinct lack of large earth quakes with magni- tudes one or two units below the maximum-size earthquake (Davison and Scholz 1985). Recurrence periods for the largest (i.e., giant) earthquakes (Mw>8.5) are also not well known. Periods of a hundred years have been invoked on the basis of plate motions, the ratio of seismic to aseismic slip, and the average stress-drop estimates (Sykes and Quitt- meyer 1981). However, many hundreds or perhaps even a thousand years have been suggested by Plafker and Rubin (1978). These longer recurrence periods are based both on inferences from uplifted marine terraces on Middleton Island and from the duration of interseismic submergence in the Prince William Sound and Copper River delta areas (Plafker 1969). Further geologic-paleoseismic studies are required to resolve these open questions. Seismic Hazards (2): Strong Ground Motion Shaking Although Alaska is by far the most seismogenic state in the United States, no systematic collection of digitally proc- essed strong-motion data from Alaska was available until 1984. Attempting to do a seismic-hazards assessment for a region that does not have a strong-motion data base can introduce high uncertainties. The lack of strong-motion data stems from the fact that no strong-motion recording instruments were installed and operating in Alaska until after the great 1964 Prince William Sound earthquake. About a dozen instruments were installed by the USGS immediately after this great earthquake. The instruments were placed along the Pacific Plate boundary, in Anchorage, and a few other municipalities, and at a few engineering structures. Today, about 75 accelerometer sites have instru- mentation. Several stations were closed due to high mainte- nance costs in the late 1970s and early 1980s. A State of Alaska strong-motion program is only in the planning stage. In the early 1980s, a dozen new strong-motion record- ers were installed in the Yakataga seismic gap (USGS) and in the Shumagin seismic gap (Lamont-Doherty Geological Observatory). The installation roughly coincided with the termination of the seismologic components of the OCSEAP-sponsored studies. A string of stations was origi- nally installed along the Trans-Alaska Pipeline, but the data — if existent — are not in the public domain. For a sum- mary of those strong-motion stations operating in Alaska, see Beavan and Jacob (1984). Because the oil industry must assess offshore and onshore seismic hazards from strong ground motions, it sponsored the systematic compilation and digital process- ing of all significant Alaskan Pacific-coastal strong-motion data available up to 1983. This resulted both in the data report and the digital data sets by Beavan and Jacob (1984). Figure 6-28 shows the distribution both of earthquakes and of stations with processed records that resulted from this compilation. Table 6-1 lists earthquake-source charac- teristics for those earthquakes where strong-motion records were analyzed. Figure 6-29 gives an example of the digitally processed records. Note both the large horizontal ground displacements during the periods of between 2 and 4 s, and the zero-to-peak amplitudes in excess of —30 cm (1 foot) at a distance 170 km from the source. The duration of the record is 80 seconds. Low-frequency ground motions can influence the response of both deep-water structures such as exploration and production platforms and of large bodies of fluids in storage tanks — both of which tend to have their natural periods of vibration in this frequency range. ■ Station • Earthquake I 1 Rupture zone 160 Figure 6-28. Distribution of stations and earthquakes for which digitized and processed seismic strong-motion records are available. Shaded areas show rupture zones of the two largest events with dates indicated. (Modified from Beavan and Jacob 1984.) Table 6-1. Alaska-Aleutian earthquakes for which processed strong-motion data exist. Seismicity, Tectonics and Geohazards 169 Origin Time Latitude °N LONCITUDE °vv Du> in km Magnitude y mo (I h min M„ 1964 1964 1965 1965 1968 1970 1971 1972 1974 1974 1974 1974 1975 1975 1976 1979 1979 1979 1981 1983 1983 06 05 09:50 60.350 06 05 22:06 58.140 09 04 14:32 58.290 12 22 19:41 58.350 12 17 12:02 60.150 03 11 22:38 57.390 05 02 06:08 51.420 07 30 21:45 56.770 04 06 01:53 54.870 04 06 03:55 54.900 08 13 03:46 51.490 11 11 05:17 51.590 01 01 03:55 61.920 07 25 10:40 55.040 02 22 07:21 51.570 01 27 18:57 54.790 02 13 05:34 55.170 02 28 21:27 60.640 12 28 10:28 54.669 02 14 03:20 54.736 145.870 16 5.2 152.180 13 5.0 152.500 32 6.8 153.130 42 6.8 152.820 82 6.3 153.970 38 6.3 177.210 38 6.8 135.910 29 7.5 160.290 37 5.6 160.290 40 5.8 178.110 47 6.1 178.080 69 6.1 149.720 58 6.0 160.410 38 5.6 176.810 61 4.7 160.640 53 6.2 156.940 47 6.5 141.590 13 7.3 160.407 33 3.8 158.882 25 6.3 02 I I 08:10 54.854 158.843 25 6.0 Probably the most important findings from the strong- motion data collected by Beavan and Jacob (1984) for Alaska, and from a similar data set for Japan collected by Wildenstein-Mori and Crouse (1981), are illustrated in Fig- ure 6-30. These critical Findings show that the scatter of peak accelerations (as a function of distance from earth- quakes) is much larger in Alaskan subduction zones than the scatter for Californian earthquakes. Hence, in Alaska, the highest peak accelerations can be signiFicantly larger than the highest accelerations observed in California (Joyner and Boore 1981) for similarly sized earthquakes at the same distances. Ground Acceleration A quantitative analysis of the causes for the difference between Californian (mostly shallow strike-slip) and Alas- kan (mostly subcrustal subduction-zone thrust) earth- quakes and their associated peak accelerations is still pend- ing. Likely candidates for explaining the differences include: 1) higher stress drops for the Alaskan sources (per- haps facilitated by higher conFining pressures at greater depths), 2) lower slab temperatures, and 3) a more com- pressive tectonic stress regime. Lesser absorption during wave propagation in the Alaskan crust may contribute to the difference, but is probably not a major controlling factor. Jacob and Mori (1984) compare the subduction-zone 200 81.33 Figure 6-29. Processed strong-motion record for north-south horizontal component of ground acceleration, velocity, and displace- ment recorded at the Vakutat airport ( ~ 166 km from the epicenter of the St. Flias earthquake. Mw = 7.3) of February 28. 1979. (Modified from Beavan and Jacob 1984.) Note zero-to-peak amplitudes for displacements of 14 cm, velocities of 24 cm/s, and accelerations of 80 cm/s2. 170 Ph^icm Environment 1000 E U / 100 •V- i • A • • A IV. * - • California a Subduction zones (Alaska and Japan) 10 100 HVPOCENTRAL DISTANCE (km) 500 Figure 6-30. Comparison of peak ground acceleration to hvpocentral distance for California earthquakes and Alaska and Japan subduction-zone earthquakes for events with mag- nitudes 6 to less than 7. Note higher peak values for many sub- duction events at any given distance (Jacob and Mori, unpubl. data). attenuation laws (e.g., peak acceleration vs. distance at con- stant Mw, see Fig. 6-30) with the attenuation laws of Wood- ward-Clyde Consultants (1982) for their Alaskan OCS seis- mic exposure study. A quantitative statistical treatment of the new subduction zone attenuation data of Beavan and Jacob (1984) is still pending. The results of these studies have not been incorporated into any systematic seismic- exposure mapping, and strong-motion data for the most important Alaskan subduction-zone earthquakes with mag- nitudes (Mw) equal to or greater than 7.5 are not yet available. Seismic Hazards (3): Seismic-Exposure Mapping Seismic exposure mapping is a computational process that is used to generate maps of ground-motion levels expressed in probabilistic terms. For instance, one may want to map the contours of those peak accelerations that would not be expected to exceed a certain probability within a given period. For example, if the probability were 67% for a time period of 40 y, that would imply a 33% chance that the mapped values of acceleration will be exceeded. Both empirical data and statistical criteria are needed for this type of mapping. For instance, the location, the recur- rence, and the magnitude distribution for earthquakes must be known. The attenuation of ground-motion parameters and their functional dependence on factors such as magni- tude, travel path, distance, and site conditions must be pre- scribed. Finally, the period of interest and the probability level of exceedence (or non-exceedence) for which the map is intended must be specified. Once the input quantities are established, the seismic exposure is obtained by computing (for each grid point on the map) the cumulative distribution function for the chosen ground-motion parameter — based on contribu- tions from all the sources in the region. The shape of this cumulative distribution function — when read at the chosen percentage of non-exceedence — yields the expected ground-motion level at the grid point. Then the results for the system of grid points are contoured on the map for easy visual display. Sometimes, only limited empirical input data are avail- able, but many are needed to properly specify the source, the attenuation, and the statistics of the exposure model. This situation can lead to undesirable subjectivity that can contribute to significant differences in the outcome of the hazards-exposure computation. It is desirable, therefore, to obtain a quantitative understanding of the sensitivity of the output in regard to variations in the input and model parameters. The need for sensitivity studies is illustrated in two exposure maps (Fig. 6-31 and 6-32). Both maps show peak accelerations at a 67% probability of non-exceedence within a 40-y period between 1982 and 2022. (Remember that exposure mapping becomes time-dependent as one goes beyond a random Poisson model for the occurrence of earthquakes!) The first of the two maps (Fig. 6-31, adopted from Woodward-Clyde Consultants 1982, Vol. II: Fig. 10) shows a rather smooth distribution of peak accelerations characterized by a broad ridge of high values (reaching a plateau at 300 cm/s2), but with no values higher than that. The high is best developed on the margin between Kodiak and the Shumagins, but (for reasons not fully clear to this reporter) they drop off toward the Yakataga gap and South- east Alaska transform margin. The second map (Fig. 6-32, adopted with only minor modification from J. Hobgood, formerly with Wood- ward-Clyde Consultants, pers. comm., 1981) is from an early test run with the same exposure routines applied to obtain Figure 6-31. Figure 6-32 does use a slightly different source geometry as well as a different attenuation law for peak accelerations from subduction-zone sources at small depths and distances. (For a discussion of these attenuation laws, see Woodward-Clyde Consultants (1982) Volume II: Figure 7.) Otherwise, the same recurrence relation and statistical criteria as in Figure 6-31 were applied. Nearly twice as high peak-acceleration levels were assumed at short distances in the attenuation laws. Consequently, the exposure map in Figure 6-32 shows higher peak accelerations in the outer shelf of the Shumagin and Yakataga seismic gaps where the main thrust zones have not only high probabilities for large thrust earthquakes but also come very close to the surface. These previously unpublished test results (for sites with competent soils) show maxima of 540 cm/s2 on the outer Shumagin shelf, and 680 cm/s2 near the Pamplona Ridge off the coast in the Yakataga seismic gap. It is interesting from an historical point of view, that at the time of this test computation some investigators felt the high maximum values were unrealistic. The current data base of strong-motion records for subduction zones near the source is still insufficient to resolve this question, but val- ues higher than those shown in Figure 6-30 are quite likely. Even earlier studies, such as Woodward-Clyde Consultants (1978, Vol. Ill: Fig. 3-22), obtained maxima of about 420 cm/s2 in the Shumagin segment, but were located farther inland where the Wadati-Benioff zone is about 60 km deep. Seismicity, Tectonics and Geohazards 171 60 160 ^&r 160 52 150 140 Figure 6-31. Contour map for peak ground accelerations (cm/s2) that have a 67% probability not to be exceeded within a 40-y period from 1981 to 2021. (Modified from Woodward-Clyde 1982.) 60 160 Figure 6-32. Contour map for peak ground accelerations (cm/s2) as described in Figure 6-31, except that an attenuation law which uses higher acceleration levels at short distances from potential sources was applied (for details, see text). Note that contoured values in Yakataga and Shumagin seismic gap regions reach almost twice the levels shown in Figure 6-31 (J. Hobgood, unpubl. data). A set of Alaskan hazard maps for peak horizontal acceler- ations (with a 90% probability not to be exceeded in 10, 50, and 250 y) was prepared by Thenhaus, Ziony, Diment, Hopper, Perkins, Hanson, and Algermissen (1985). The maps are based on: 1) marginally valid Poisson statistics for earthquakes regardless of magnitudes (i.e., the same statistics are applied to small and great events) 2) seismicity data that may have a strong temporal bias since they cover a very limited time period 3) ground-motion attenuation laws based on data for the western continental United States rather than for Alaska. Therefore, the 10- and 50-y exposure maps may be important only for demonstrating the sensitivity of results to method and data, rather than for representing a realistic 172 Physical Environment assessment of Alaskan ground-motion hazards. This is especially true for the next few decades in the seismic gaps. Since, however, for very long exposure times ( > > 100 y) most statistical seismicity models should converge toward a Poisson model, their map for the 250-y exposure time may provide a useful result representing long-term hazards — if it is corrected for attenuation laws applicable to Alaska. Without such corrections, the maps show peak accelerations for the shelf regions between Shumagin Islands and Yakutat that are between 600 and 700 cm/s2. These figures have a 90% probability of not being exceeded (or a 10% proba- bility of being exceeded) within 250 years. Inconsistencies in exposure mapping show that a system- atic sensitivity study for the Gulf of Alaska is needed. This applies especially as long as the empirical attenuation laws are as poorly constrained by actual strong-motion data from the Gulf as they are now. For the Gulf of Alaska, the Woodward-Clyde Consul- tants reports (1978, 1982) also give seismic exposure maps for other ground-motion parameters such as root-mean- square (RMS) acceleration, peak velocity, and others. Unlike for other regions of the United States with high seismic haz- ards potentials, there is not yet an authoritative hazards map available for all of Alaska. Tsunamis and Local Waves In coastal regions of Alaska, tsunamis (seismic sea waves) are often the cause of the most damage associated with great earthquakes. A catalog both of tsunami observations from Alaska and of the pertinent literature for the period prior to 1969 is given by Cox and Pararas-Carayannis (1976). Many refinements and additions of this information are con- tained in Sykes (1971), Davies et al. (1981), and House et al. (1981). A large amount of mostly observational data on the tsunami associated with the Great Alaskan Earthquake of March 27, 1964 is compiled in Volume III (Oceanography and Coastal Engineering) of the National Research Council Report (1972). A more recent review of tsunami-related research has been given by Houston (1979). Steinbrugge (1982) gives a good general compilation of the tsunami effects, damage, losses, and of present tsunami zoning for the United States (including Alaska). In addition, Wiegel (1970) treats many of the engineering and physical aspects of tsunamis including speed, coastal-wave amplification, wave-forces, and run-up effects. Tsunamis and other, localized wave surges are generated during earthquakes or volcanic eruptions by one of several types of displacement at the boundaries of a body of water: 1) The ocean bottom/water interface is directly deformed by faulting or by the primary displacement field of a major earthquake. It causes a tsunami with regional effects on open coastlines, and the tsunami may travel across an entire ocean. 2) An earthquake-induced submarine landslide can change the ocean bottom topography. If such a sub- marine slide occurs in a semi-enclosed bay, the tsunami can be highly localized and its run-up heights may substantially exceed the general run-up heights from the regional tsunami of the same causative earth- quake. 3) The third type of tsunami usually occurs as a localized and often highly directed surge generated not by changing the bottom topography, but by the high- speed impact between water and a subaerial landslide, volcanic debris flow, or an ice avalanche. The three types of tsunamis or surges can be dis- tinguished in many instances, but if two or more types are simultaneously triggered during a regional earthquake, or during a major volcanic eruption with earthquake, their rel- ative importances may not always be readily separable. These complexities make it also difficult to predict local tsunami effects. Examples of maximum run-up heights of tsunamis and local waves at coasts, bays, and inlets in Alaska as a result of the 1964 Earthquake are: • 30 (from 10 to 60) m in Port Valdez Inlet • 20 m at Chenega village in Prince William Sound • 10to20matKodiak • less than 5 m in Shelikof Strait. However, some of those run-up heights are dominated by local waves. Other tsunami effects include: • 30 m at Scotch Cap lighthouse on Unimak Island from the nearby 1946 event of magnitude Ms equal to 7.4 that may have triggered a huge submarine slide • 9 m at Port Graham (Kenai Peninsula) generated by a debris avalanche during the 1883 eruption of St. Augustine volcano in lower Cook Inlet • 10 m in Yakutat Bay during the September 5, 1899 quake, probably from a splash wave. Earthquake-triggered landslides or debris avalanches can set up water surges with astoundingly extreme run-up properties. Most notorious is Lituya Bay along the Fair- weather Fault with reported maximum run-up heights of 120, 24, 60, 150, and 525(!) m in the years 1853-1854, 1874, 1899, 1936 (slide, no quake), and 1958, respectively (Miller 1960). Tsunamis can travel far and still cause considerable damage — especially where bay or inlet morphology locally amplifies the effects by factors of two to four when com- pared to open-coast run-up heights. The maximum run-up heights in Hawaii for the 1946 eastern Aleutian (Unimak) event measured 18 m, and the Great Alaskan Earthquake of 1964 caused run-ups of greater than 9 m in Crescent City, California. A U.S. Army tsunami hazards map (Steinbrugge 1982), which is not widely circulated, puts all of the open coasts of the Gulf of Alaska in Zone 3 (run-up of 5-10 m), except for inlets and fjords, which are categorized in Zone 4 (10-17 m) and possibly Zone 5 (excess of 17 m). These heights are sup- posed to give values not to be exceeded with a 90% proba- bility in 50 years. This probability may be correctly assessed for the regional tsunami effects, but many of the locally induced 1964 run-up heights exceeded these values. A quantitative physical description of the coastal run-up process (especially in near-source regions) as a function of Seismicity, Tectonics and Geohazards 173 (a) static displacements of the ocean floor during the earth- quake and (b) coastal morphology and bathymetry at the receiver site, is still in its early stages and probably will remain so for some time to come. Ward (1982) advanced a method for a computational prediction of tsunami ampli- tudes and their radiation patterns as a function of the seis- mic moment tensor, source geometry, and source depth for distances large compared with the source dimension, i.e., mostly at teleseismic distances. The speed with which a tsunami travels is approximately c = V(gh) > where g is 9.81 m/s-\ and h is water depth in meters. This implies speeds of 800 km/h in the deep ocean, and 150 km/h or 40 m/s and less on the shelf. These speeds give (in many instances) sufficient lead times between the origin time of an earthquake and the arrival of the first tsunami wave at a coastal site so that tsunami warnings can be issued for distances of a few 100 km and more from the source — provided sufficient seismologic and communication facili- ties are regionally available and that they remain operative during a great earthquake. The Alaska Regional Tsunami Warning System in Palmer, Alaska (operated by NOAA) has this important alerting function for Alaska. It is tied into the international Pacific-wide Tsunami Warning System that has its operational center in Honolulu, Hawaii. Localized seiches or tsunamis during a regional event, e.g., those trig- gered bv local landslides during shaking, cannot be detected with sufficient lead time for the localities they affect and, thus, no suitable warning method exists for them. The shallower the earthquake, i.e., the closer the strain source to the ocean floor, the larger is the efficiency with which a tsunami is generated — given a certain moment (or magnitude) of the source. This relation is confirmed both from theoretical considerations (Ward 1982), and from observations (Nishenko and McCann 1979; Fukao 1979; and Abe 1979), which indicate that tsunamis are most efficiently generated by subduction-zone earthquakes during which secondary steep faults cut the ocean floor in the fore-arc region. This was certainly the case near Montague Island for the Great Alaskan Earthquake of 1964 (National Research Council 1972, Vol. 4). A recent SEABEAM (side-scanning sonar) survey of the Shumagin shelf (S. Lewis, Lamont- Doherty Geological Observatory, pers. comm., 1985) suggests that faulting and perhaps extensive slumping is prevalent offshore at Unimak Island, the site of one of the largest tsunamis ever recorded. It was generated by only a moderate-sized earthquake (Ms = 7.4) in 1946. Modest progress has been made during the last decade to improve the quantitative assessment of tsunami hazards for Alaska. Maps have been issued by the State of Alaska's Divi- sion of Emergency Services, in cooperation with federal agencies. They are available for selected, generally more populated coastal segments, and show little more than zones of 'possible flood area' that cover the coastal strips between sea level and elevations to 100 feet (30 m) above sea level. The maps provide the public with fundamental tsunami safety rules and instructions on tsunami warning signals. Since the coast in the Gulf of Alaska is one of the most important economic zones in Alaska, tsunami research, con- sideration of tsunamis in coastal engineering projects, and the implementation of an effective, reliable, and fast tsunami warning system that can reach endangered commu- nities within minutes of a large earthquake must rank high on the priority list for both State and Federal agencies. It is crucial to maintain a modern tsunami-mitigating system. Other Seismic Hazards Seismic hazards come in many fundamentally different forms: there are those related to direct natural effects like- shaking, faulting, subsidence, flooding, tsunami, soil- failure, slides, flows, and avalanching. In addition, there are the secondary effects on man-made structures, and the effects from the failures of man-made structures that cause fires and the loss of water, power, and other essential serv- ices. Both geologic and secondary effects can cause fatalities and substantial economic loss. We discuss here only the geo- logic aspects, and these only to the extent that the reader is guided to the pertinent literature. We refer again to the National Research Council (1972) eight-volume report on the Great Alaska Earthquake of 1964, and to Grantz, Plafker, and Kochadoorian (1964), Wiegel (1970), and Steinbrugge (1982) for the geologic, engineering, and public-economic aspects of seismic hazards, respectively. One of the most consequential phenomena of the 1964 Earthquake was the failure of unconsolidated weak sedi- ments during the minute-long shaking and dynamic load- ing that occurred both onshore and offshore. The failure of sediments in the Bootlegger Cove Formation (Updike, Dear- born, Ulery, and Weir 1984; Updike 1984) caused wide- spread slides in the Anchorage down town area and at nearby sites such as 4th and L Street, Government Hill, and Turnagain Heights. These extensive failure zones and the graben, slide, and pressure-ridge formation areas were ear- lier attributed to dynamic soil-liquefaction, which occurred preferentially in the weak central layer of the Bootlegger Cove Formation. More recently, shear sensitivity and the collapse of the silty clays in that formation have been emphasized as causes (Updike 1984; Updike et al. 1984). When nearshore submarine sediments in Valdez and Seward failed during the 1964 Earthquake, they caused slumps that took the dock facilities with them. Some of the post-1964 submarine slopes at both sites are much steeper when compared with their pre-1964 configurations. Onshore strips of land adjacent to the slides were weakened by extensive fracturing in 1964. Therefore, these areas are likely to fail again in future earthquakes and may not be feas ible sites for reoccupation. Hampton, Carlson, Lee, and Feely (Ch. 5, this volume) review other offshore regions in the Gulf of Alaska that have either observed or potential submarine slope instabilities, as well as review their geo- technical properties . In 1964, many coastal zones of Alaska experienced a co- seismic tectonic subsidence or uplift that measured several meters, along with flooding or shoaling at extreme tides. These shore changes caused considerable economic damage and required the relocation or raisingof facilities in areas where neither the earthquake shaking nor the tsunamis had done much damage. Two examples of severe subsidence effects were the Homer and the Seldovia areas on the Kenai Peninsula. 174 Pn>sii"M Environment The 1964 Earthquake caused fissuring, cracking, sand boils, and ground How (especially into narrow topographic depressions across stream channels where systematic short- ening caused the buckling of railroad trestles that crossed them). Other effects included avalanching, rockslides, and other, lesser geologic and geotechnical events. Similar geo- logic hazards can be assumed for future great earthquakes in the Gulf of Alaska. Careful site-specific assessments of these hazards must be made in the future on a project-by- project basis. Volcanic Hazards Between Unimak Island in the west and Sitka in the east there are about 40 Quaternary and Holocene volcanoes unequally spread over this more than 2,000-km-long sec- tion of the PAC-NAM Plate boundary in the Gulf of Alaska. Most of the volcanoes are located between Unimak Island and Cook Inlet along the Aleutian Trench, although there is a small second group in the Wrangell Mountains, and the lone Edgecumbe volcano and its subsidiary edifices on Kruzof Island near Sitka (see Figure 6-6). The volcanic activity within the Aleutian group east of Aniakchak vol- cano (the Katmai-Cook Inlet trend) has been summarized by Kienle and Swanson (1983a). They show that 10 of the 22 Quaternary-Holocene volcanoes in this group have been active in historic time. Coats (1950) and Simkin et al. (1981) are, respectively, general source references on Aleutian and other Alaskan volcanic activity. For assessment of volcanic risks globally, and the effect of volcano hazards on insur- ance policies and the public, see publications by Munich Reinsurance Company (1984) and Steinbrugge (1982). The largest of all witnessed volcanic eruptions in the Gulf of Alaska was the 1912 Plinian eruption of Novarupta in the Katmai group. A Plinian eruption constitutes explosive activity with large amounts of tephra and is often associated with caldera collapse. Novarupta was by far the world's most voluminous eruption in this century (Hildreth 1983). It pro- duced ~ 20 km3 of ash-fall tephra and less than 15 km3 of ash-flow tuff within —60 hours. By way of comparison, the volume of ejecta associated with the laterally directed, May 18, 1980, Mount St. Helens eruption was at least 10 times smaller, and the volume of new volcanic ash was at least a 1,000 times smaller than that of the Katmai eruption. Locally, ash deposits were up to 17 m thick. Deposits meas- ure ~ 30 cm on Kodiak Island, and the 3-cm cumulative ash- fall contour stretches southeasterly for ~ 400 km from Kat- mai to beyond Kodiak and into the open Pacific Ocean (Fig. 6-33). This eruption created entirely new landforms, includ- ing the Valley of Ten Thousand Smokes and the collapse of the summit of Mount Katmai. Based on radiocarbon dates, twice during the last 2,000 y the source of the White River ash in the Wrangell Mountains produced ejecta volumes on the order of 20 and 25 cubic kilometers. These are spread widely over eastern Alaska and parts of adjacent Canada (Lerbekmo and Campbell 1969). The Wrangell volcanoes have also been the source of the 80,000-year-old 'Old Crow' tephra (with a total volume of 50 km3) that is spread over most of central Alaska (Westgate 1982). Mount Spurr (1953), Mount Redoubt (1966-1968), and Augustine volcano (1976, 1986) erupted and caused ash to fall in populated regions (Fig. 6-34). In the first case, ash damaged equipment in Anchorage. How frequent, how wide-spread, and how severe are vol- canic hazards in the Gulf of Alaska? Although there is no sin- gle comprehensive study or reference on volcanic hazards for the entire Gulf of Alaska, several descriptive and quan- titative assessments of volcanic hazards in portions of Alaska's volcanic regions have been made. For the Aleutian volcano group (74 volcanoes), McNutt (1983) tried to establish the average eruption frequency (per 100 y per volcano) as a function of volume. To do this, he used: 1) ash layers in young Pacific ocean-floor sediments that he probed by piston cores, 2) ash layers dated on land in the Shumagins and on the Alaska Peninsula, and 3) historic and recent records of eruptivity. He concluded that on aver- age one eruption per volcano every 100 y with about 0.1 km3 of ejecta can be expected, but that an eruption with a vol- ume of a few km3 may occur only once every 100,000 y for any one volcano. These are very crude occurrence-fre- quency estimates that take a form somewhat analogous to the logN = A - bMw relationships between earthquake occurrences and their magnitudes. McNutt (1983) also plotted maximum ash thickness ver- sus distance from the source vent, with the log of the ejected material volume as a parameter (analogous to parameteriza- tion of peak ground-motions vs. distance for different Mw). While the data scatter widely, the maximum ash thickness on average falls off inversely proportional to distance for a range of between a few and several hundred kilometers. Thus, 15 m of deposits at 1 km would attenuate to 1.5 m at 10 km, and 15 cm at 100 km — values that are crudely compatible with maximum values for the Katmai event of 1912. Note that these values apply in the direction of the prevailing wind. In other directions, the fall-off is much more rapid. Thus the prevailing wind directions and speeds are most important for probabilistic estimates of ash-fall hazards. McNutt (1983) mapped two regions (between Mount Ven- iaminof and Frosty Peak on the Alaska Peninsula, and between Akutan and Vsevidof on Umnak Island in the east- ern Aleutian Islands), with regard to areas with 100-y ash accumulations of more than 10 cm and 4 cm, respectively. He also mapped zones with likely debris or lava flows, and mapped valleys with geologic ally young volcanic mud flows that extend for distances beyond 50 km from the source vents. Recent geologic mapping on the Alaska Peninsula by Detterman, Miller, Yount, and Wilson (1981a,b) provides locally detailed information on the extent of ash flows, as well as lava and caldera mud flows. The spectacular mobility of ash flows around Aniakchak on the Alaskan Peninsula and around Fisher caldera on Unimak Island have been pointed out by Miller and Smith (1977). Probably the most serious volcanic threat for Alaska exists in the Anchorage/Cook Inlet/Kodiak/Kenai region where about half of Alaska's population is concentrated and exposed to potential volcanic hazards. Augustine, Iliamna, Redoubt, Spurr, and Hayes (Fig. 6-6) are the prominent vol- canoes bordering Cook Inlet, but future, newly forming vol- canic vents could also become sources of volcanic hazards. Sf ismicity, Tectonics and Geohazakds 175 " Stratovolcano f Complex volcano jfe Dissected stratovolcano \j) Caldera with pyroclastic flow apron ^57 Caldera lake CL Crater lake L Historic lava flows LA Lahar F Fumaroles Figure 6-33. Map of major volcanic centers, historic eruptions, and generalized volcanic hazards in and near the Katamai area of the Alaska Peninsula. (Modified from Kienle and Swanson 1983a.) Numbers in plume symbols refer to the Volcanic Explosive Index (VET) described by Simkin et al. (1981). The volcanic hazards to the Cook Inlet region (primarily from Augustine volcano) have been specified in great detail by Kienle and Swanson (1983b, 1985) and by Kienle, Davies, Miller, and Yount (1986). Of particular interest is the poten- tial of Augustine volcano to cause destructive tsunamis in Cook Inlet. Some of the tsunamis would apparently be gen- erated by the rapid impact between massive avalanches composed of dry volcanic debris and the sea. For instance, on October 6, 1883, the western tip of the Kenai Peninsula at Port Graham was in undated by a 10-m-high tsunami that had been generated both by an eruption and the associated debris avalanche of the Augustine volcano. It took approx- imately 25 min for the tsunami to cross Cook Inlet (a dis- tance of about 70 km) before it reached the Kenai Peninsula. Ashfalls are also a major concern for the Cook Inlet region. Ashfalls can, for instance, severely impede power generation in combustion plants, or preclude vital air traf- fic. For example, air traffic in and out of Anchorage was tem- porarily closed in 1953 during an eruption of Mount Spurr. Figures 6-33 and 6-34 (from Kienle and Swanson 1983a) schematically show historic ashfall distributions from vol- canoes extending from Aniakchak (in the southwest) to Mount Spurr (in the northeast). A summary of Holocene tephras in the upper Cook Inlet (Riehle 1985) suggests one major tephra fall every 150 y, and one perceptible ashfall every 12 years. Other known volcanic hazards in Cook Inlet are associ- ated with lahars (volcanic mudflows) originating, for instance, at Redoubt volcano and descending into the Cres- cent and Drift River Valleys (Riehle, Kienle, and Emmel 1981). Coastal flash-flooding occurred, for example, on Jan- uary 26, 1966, and posed a potentially serious risk to the Drift River tanker terminal. A quantitative volcanic-hazards assessment for all vol- canically active regions of Alaska is still pending. Except for those areas within close proximity of volcanic centers (<30 km), volcanic hazards generally pose a lesser degree of risk than the hazards caused by the seismic sources discussed 176 Physical Environment 62 156 154 152 150 60 ▲ Stratovolcano / Complex volcano * Other volcanoes ▲ Stratovolcano with pyroclastic flow apron & Lahar (LA) Flash Hoods r Tsunami F Fumaroles Hayes * Port Alsworth .*» Ash to Skilak Lake 1976 Augustine 1963/64 Augustine 1935 Augustine 1876 Iliamna 1867 Iliamna 1843 Iliamna 1812 Augustine J!~ h/lf Seldovia Griggs^ Douglas -*- )r\ Four peaked Kaguyak^ .^fr^C -^ DevilsDesk ^^^^ £~J Denisony^Kukak NovarupUfci^Kaimai B2 60 Figure 6-34. Map of major volcanic centers, historic eruptions, and generalized volcanic hazards for the Cook Inlet region. (Modified from Kienle and Swanson 1983a.) Numbers in plume symbols refer to the Volcanic Explosive Index (VEI) described by Simkin et al. (1981). Note listing of recent ashfall at Skilak Lake on the Kenai Peninsula. earlier. Unfortunately, the two hazards are additive. Given the population density of the Anchorage metropolitan area and its proximity to Mounts Hayes, Spurr, Redoubt, Iliamna, and Augustine (the latter four of which were active within the last 200 y), the cumulative risk from these vol- canic sources is both real and finite. Clearly it calls for a much better quantitative assessment of the risks involved. Any assessment of past activity should also be combined with continuous seismic monitoring of at least these five vol- canoes closest to Anchorage, in order to provide some advance warning prior to an impending eruption. Over and above those occasions discussed earlier, several smaller communities along the Alaska Peninsula and the Aleutian chain had volcano alerts during the last few decades. These alerts were in connection with the activities of: • Okmok on Umnak Island • Akutan on Akutan Island • Westdahl and Shishaldin on Unimak Island • Pavlof, Kupreanof, Veniaminof, Ukinrek, and Peulik on the Alaskan Peninsula. Although Makushin volcano on Unalaska Island has not been recently active , during any eruption, the towns of Unalaska and Dutch Harbor would be extremely vulnera- ble. The same applies to Sitka, with its close proximity to Mount Edgecumbe. Lava flows, debris avalanches or mud flows, ashfall, and glowing debris avalanches (which some- times surge out onto open water) are all potential hazards in case of an eruption. Add to these hazards the volcanically induced tsunamis, earthquakes, toxic precipitations, and fumes that must be considered potential threats, and the danger is considerable, however rare these occurrences may be. Challenges to Human Activity The seismicity, volcanicity, tectonics, and related geo- hazards of the Gulf of Alaska, combined with increasing population and development, pose severe challenges for the future. Their very existence calls for (1) a solid scientific understanding of the nature of these hazards, and (2) the development of realistic policies based on this knowledge that, when implemented, carefully balance the short-term needs for development with the long-term needs for preser- vation and the avoidance of catastrophic losses. Scientific Challenges The highly dynamic tectonic environment of the Gulf of Alaska poses formidable scientific challenges. One such sci- entific challenge is to unravel both the geologic history and the nature of the terrane accretion that formed most of con- tinental Alaska along with its resources. Another pressing challenge lies in accumulating and using this scientific knowledge to mitigate the adverse effects of geological hazards . One stumbling block lies in the fact that the hazards must be expressed quantitatively before they can be translated into economically viable pub- lic decisions and regulations. To mitigate seismic, volcanic, and tsunami hazards effectively requires solid observational data, which implies that a basic measurement capability must be maintained. The specific scientific and societal chal- lenges that Alaskans face in this respect have been concisely summarized in a brief document prepared by an expert panel (Davies 1983). Outlined here are a few practical and readily achievable points for future research that appear crucial for effective hazards mitigation: 1 ) Paleoseismic Record — Large earthquakes are rare (recur- rence about every 100 y), and the written Alaskan his- toric record is short (about 200 y). Since one needs a long record of great earthquakes in order to establish a statistically meaningful model for their recurrence, geologic studies of paleoseismicity are crucial. 2) Strong-Motion Data — The collection of strong-motion records in the Alaska tectonic environment must be pursued with patience and persistence, regardless of strong-motion recording efforts elsewhere in the United States. This is because strong-motion proper- ties in Alaskan subduction zones are distinctly differ- ent from those of other tectonic environments in the United States. Although the data are most urgently Seismicity, Tectonics and Geohazards 177 needed for the Anchorage metropolitan area and for those offshore regions targeted for development, they probably can be obtained soonest (for great earth- quakes), in the postulated soon-to-break seismic gaps of Yakataga and the Shumagin Islands. The data set must include strong-motions from sites both offshore and onshore, as well as from both soft and competent soils or rocks. 3) Geohazards Atlas — A comprehensive up-to-date atlas with quantitative seismic and other geohazards maps for the Gulf of Alaska region needs to be produced. It should reflect existing hazards data as well as the incompleteness of these data, but most importantly, it must fulfill the very practical and realistic needs of public and private users, planners, and decision makers. 4) Tsunami, Volcano, and Earthquake Warnings — Modern seismic network and mareographic sensing tech- nology is available, and it can make tsunami warnings faster and more effective, bring volcano warnings to reality, and may even make short-term earthquake alerts possible. This will require, however, that mod- ern communication facilities be made available to transmit crucial data from remote monitoring sites to data centers. The centers must be staffed with experts who can exert decisive judgment. Their assessments could not only provide decision makers with options ahead of impending calamities, but could inform them quickly on the extent and severity of a disaster in progress. Public Challenges Sooner or later, there is a price to pay when population centers get a foothold in earthquake and volcano country. The challenges to the Alaskan public lie in the dilemma of whether to pay attention to mitigation and the associated costs ahead of time, or to pay the full price of an unmitigated disaster when ever and wherever it strikes. Alaskans heat their houses — a calculated yet comforting fire hazard — but in doing so, adhere to standard technology and a building code. They use common-sense practices that reduce the risk of fires in homes and in working facilities, and equip themselves with fire extinguishers and hydrants. It has finally become acceptable to maintain standing fire departments, at least in the larger communities. Why, then, only 20 years after the Great Alaskan Earth- quake of 1964, are multi-story buildings in downtown Anchorage rising from those same sites which so recently failed and slid? memory) bustle along, day by day, while the earth beneath them slowly accumulates massive stresses and strains. Overnight — in geologic terms — a colony of log cabins has turned into a metropolis that is oblivious to its potential for disaster — disaster that is guaranteed when tectonic forces like those of 1964 are unleashed again. In advance of the event, only a few seem to take quiet notice. Insurance companies make it their business to heed the numbers and the obvious, documentable odds. They set their rates, and limit, distribute, or exclude coverage, all the time acutely aware of the latent risks. Will they be the only ones who are well prepared when the geologic odds catch up with the rest of Alaska? Acknowledgments This review paper is based on the research of numerous scientists, technicians, students, pilots, administrators, field personnel, and ordinary citizens. Specifically, I thank T. BrunsJ. Davies, E. HaukssonJ. KienleJ. Lahr, G. Plafker, H. Pulpan, C. Stephens, and R. von Huene for contributing either information and comments or materials for some of the figures. The lion's share of the research reported in this paper was supported by the Minerals Management Service, Department of the Interior, through an interagency agree- ment with the National Oceanic and Atmospheric Admin- istration, Department of Commerce, as part of the Alaska Outer Continental Shelf Environmental Assessment Pro- gram (OCSEAP). Funding from the U.S. Geological Survey's Earthquake Prediction and Hazards Mitigation program, and from the Department of Energy, Office of Energy Sci- ences, contributed much to the seismic studies. The prepa- ration of this manuscript was made possible by OCSEAP under P.O. 84-ABA-02196 and 84-ABA-02197. I thank R. Bongiorno and L. Murphy for typing the paper and K. Nagao and M. Luckman for preparing several of the figures. I appreciate the critical reviews by J. Beavan, T. Boyd, J. Kienle, J. Davies, J. Lahr, G. Plafker, C. Stephens, D. Simpson and Y. Vyas that helped to improve both the form and the content of the paper. Finally, I thank the editor, D. Hood, for his patient, yet determined shepherding of the project to completion. This is contribution No. 3905 of the Lamont-Doherty Geological Observatory of Columbia University. Conclusion A century is a small fraction of a rock's geologic memory, while a dozen decades occupy a major segment of Man's mind. Alaskan geology works at an imperceptible pace, while Alaskan urban development continues at an increasingly rapid pace. Alaskans (with their short human 178 Physical Environment References Abe, K. 1979 Size of great earthquakes of 1837-1974 inferred from tsunami data. Journal of Geophysical Research 84B:1561-1568. Agnew,J.D. 1980 Seismicity of the central Alaska Range, Alaska, 1904-1978. M.S. Thesis, University of Alaska, Fairbanks, AK. 88 pp . Atwater, T. 1970 Implications of plate tectonics for the Cenozoic tectonic evolution of western North America. Geological Society of America Bulletin 81:3513- 3535. Beavan, J., R. Bilham, and K. Hurst 1984 Coherent tilt signals observed in the Shumagin seismic gap: detection of time-dependent sub- duction at depth? Journal of Geophysical Research 89B:4478-4492. Beavan, J. and K.H.Jacob 1984 Processed strong-motion data from subduc- tion zones: Alaska. Report No. 1, L-DGO Proc- essed Strong Motion Data. Lamont-Doherty Geological Observatory, Palisades, NY. 252 pp. Beavan, J., E. Hauksson, S.R. McNutt, R. Bilham, and K.H.Jacob 1983 Tilt and seismicity changes in the Shumagin Seismic Gap. Science 222:322-325. Brogan, G.E., L.S. Cluff, M.K. Korringa, and D.B. Slemmons 1975 Active faults of Alaska. Tectonophysics 29:73-85. Bruns, T. 1979 Late Cenozoic structure of the continental margin, northern Gulf of Alaska. In: The Rela- tionship of Plate Tectonics to Alaskan Geology and Resources: Proceedings, Seventh Symposium of the Alaska Geological Society. A. Sisson, editor. Anchorage, AK. pp. 11-30 Bruns, T. 1983 Model for the origin of the Yakutat block, an accreting terrane in the northern Gulf of Alaska. Geology 11:718-721. Bruns, T. 1985 Tectonics of the Yakutat Block, an allochthonous terrane in the northern Gulf of Alaska. U.S. Geological Survey Open File Report 85-13. 107 pp. Buland, R. andj. Taggart 1981 A mantle wave magnitude for the St. Elias, Alaska, earthquake of 28 February 1979. Bul- letin of the Seismological Society of America 71:1143-1159. Byrne, T. 1979 Late Paleocene demise of the Kula-Pacific spreading center. Geology 7:341-344. Chandra, U. 1974 Seismicity, earthquake mechanisms, and tec- tonics along the western coast of North Amer- ica, from 42°N to 61°N. Bulletin of the Seismological Society of America 64:1529-1549. Chappie, W.M. and T.E. Tullis 1977 Evaluation of the forces that drive the plates. Journal of Geophysical Research 82:1967-1984. Churkin, M., Jr. and G.D. Eberlein 1977 Ancient borderland terranes of the North American Cordillera: correlation and micro- plate tectonics. Geological Society of America Bul- letin 88:769- 786. ClagueJ.J. 1979 The Denali Fault system in southwest Yukon Territory — a geologic hazard? Geological Sur- vey of Canada, Paper 79-1A. pp. 169-178. Coats, R.R. 1950 Volcanic activity in the Aleutian Arc. U.S. Geo- logical Survey Bulletin 974-B. pp. 35-49. Coney, P.J., D.L.Jones, and J. W.H. Monger 1980 Cordilleran suspect terranes. Nature (London) 288:329-333. Cox, D.C. and G.P. Pararas-Carayannis 1976 Catalog of tsunamis in Alaska, Report SE-1. World Data Center A, NOAA, Environmental Data Service, Boulder, CO. 43 pp. Davies,J.N. 1983 Seismic, volcanic, and tsunami mitigation in Alaska: an unmet need. Report of Investiga- tions 83-11, Division of Geological and Geo- physical Surveys, State of Alaska Department of Natural Resources. 13 pp. Davies, J.N. and L. House 1979 Aleutian subduction zone seismicity, volcano- trench separation, and their relation to great thrust-type earthquakes. Journal of Geophysical Research 84B:4583-4591. Davies, J., L. Sykes, L. House, and K.Jacob 1981 Shumagin Seismic Gap, Alaska Peninsula: his- tory of great earthquakes, tectonic setting, and evidence for high seismic potential. Journal of Geophysical Research 86B:3821-3855. Davison, F.C. and C.H. Scholz 1985 Frequency-moment distribution of earth- quakes in the Aleutian Arc: a test of the charac- teristic earthquake model. Bulletin of the Seismological Society of America 75:1349-1361. Seismicity, Tectonics and Geohazards 179 Detterman, R.L., T.P. Miller, M.E. Yount, and F.H. Wilson 1981a ( Geologic map of the ( Ihignik and Sutwik Island quadrangles, Alaska. L'.S. Geological Survey Map 1- 1229. Scale 1:250,000. Detterman, R.L., T.P. Miller, M.E. Yount, and F.H. Wilson 1981b Quaternary geologic map of the Chignik and Sutwik Island quadrangles, Alaska. U.S. Geo- logical Survey Map 1-1292. Scale 1:250,000. Detterman, R.L., G. Plafker, T. Hudson, R.G. Tysdale, and N. Pavoni 1974 Surface geology and Holocene breaks along the Susitna segment of the Castle Mountain fault, Alaska. U.S. Geological Survey Mis- cellaneous Field Studies Map MF-618. Drummond, K.J. 1981 Plate-tectonic map of the circum-Pacific region, 1:10, 000, 000, NE-quadrant. American Association of Petroleum Geologists, Tulsa, OK. Eisbacher, G.H. and S.L. Hopkins 1977 Mid-Cenozoic paleomorphology and tectonic setting of the St. Elias Mountains, Yukon Ter- ritory. Report of Activities, Part B, Geological Survey of Canada, Paper 77-113. pp. 319-335. Engdahl, E.R. 1977 Seismicity and plate subduction in the central Aleutians. In: Island Arcs, Deep Sea Trenches and Back-Arc Basins. M. Tahvani and W. Pitman, III, editors. Maurice Ewing Series 1. American Geo- physical Union, Washington, D.C. pp. 259-271. Forsyth, D. and S. Uyeda 1975 On the relative importance of the driving forces of plate motions. Geophysical Journal of the Royal Astronomical Society 43:163-200. Frohlich, C, S. Billington, E.R. Engdahl, and A. Malahoff 1982 Detection and location of earthquakes in the central Aleutian Subduction Zone using island and ocean bottom seismograph stations. Jour- nal of Geophysical Research 87B:6853-6864. Fujita, K., E.R. Engdahl, and N. Sleep 1981 Subduction zone calibration and teleseismic relocation of thrust zone events in the central Aleutian Islands. Bulletin of the Seismological Soci- ety of America 71:1805-1828. Fukao, Y. 1979 Tsunami earthquakes and subduction proc- esses near deep-sea trenches.jourruil of Geophys- ical Research 84B:2303-2314. Gedney, L. 1970 Tectonic stresses in southern Alaska in rela- tionship to regional seismicity and the new global tectonics. Bulletin of the Seismological Soci- ety of America 60:1789-1802. Grantz, A., G. Plafker, and R. Kachadoorian 1964 Alaska's Good Friday Earthquake, March 27, 1964: a preliminary geologic evaluation. U.S. Geological Survey Circular 491. 35 pp. Hauksson, E. 1983 Structure of the Benioff Zone beneath the Shumagin Islands, Alaska: relocation of local earthquakes using three-dimensional ray trac- ing. Journal of Geophysical Research 90B:635-649. Hauksson, E., J. Armbruster, and S. Dobbs 1984 Seismicity patterns (1963-1983) as stress indica- tors in the Shumagin Seismic Gap, Alaska. Bul- letin of the Seismological Society of America 74:2541-2558. Hasegawa, H.S., J.C. Lahr, and CD. Stephens 1980 Fault parameters of the St. Elias, Alaska, earth- quake of February 28, 1979. Bulletin of the Seis- mological Society of America 70:1651-1660. Hillhouse,J. W. 1977 Paleomagnetism of the Triassic Nikolai Green- stone, McCarthey Quadrangle, Central Alaska. Canadian Journal of Earth Science 14:2578-2592. Hildreth, W. 1983 The compositionally zoned eruption of 1912 in the Valley of Ten Thousand Smokes, Katmai National Park, A\aska. Journal of Volcanology and Geothermal Research 18:1-56. House, L. andj. Boatwright 1980 Investigation of two high stress drop earth- quakes in the Shumagin seismic gap, Alaska. Journal of Geophysical Research 85B:7151-7165. House, L. and K.H.Jacob 1983 Earthquakes, plate subduction, and stress reversals in the eastern Aleutian Arc. Journal of Geophysical Research 88B:9347-9373. House, L.S., L.R. Sykes, J.N. Davies, and K.H.Jacob 1981 Evidence for a possible seismic gap near Unalaska Island in the eastern Aleutians, Alaska. In: Earthquake Prediction: An International Review. D.W. Simpson and P.G. Richards, edi- tors. Maurice Ewing Series 4. American Geo- physical Union, Washington, D.C. pp. 81-92. Houston, J. R. 1979 State-of-the-art for assessing earthquake haz- ards in the U.S.: tsunamis, seiches, and land- slide-induced water waves. Miscellaneous Paper S-73-1, Hydraulics Laboratory, U.S. Army Engineer Waterways Experimental Sta- tion, Vicksburg, MS. 90 pp. Irving, E. 1979 Paleopoles and paleolatitudes of North Amer- ica and speculations about displaced terraines. Canadian Journal of Earth Scietues 16:669-694. 180 Phisical Environment Jacob, K.H. 1984 Estimates of long-term probabilities for future great eartbquakes in the Aleutians. Geophysical Research Letters 11:295-298. Jacob, K.H. and T.M. Boyd 1985 Analysis of data from a temporary seismic net- work on Unalaska Island. Report to the Divi- sion of Geological and Geophysical Surveys. State of Alaska Public Data File, PDF 85-59. 48 pp. Jacob, K.H. and E. Hauksson 1983 A seismotectonic analysis of the seismic and volcanic hazards in the Pribilof Islands-eastern Aleutian Islands region of the Bering Sea. Research Unit 16. Final report to NOAA, Outer Continental Shelf Environmental Assessment Program. Contract NOAA 03-5-022-70. Lamont-Doherty Geological Observatory, Pal- isades, NY. 224 pp. Jacob, K.H. and J. Mori 1984 Strong motions in Alaska-type subduction zone environments. In: Proceedings of the Eighth World Conference on Earthquake Engineering, Vol. II. Prentice Hall, Englewood, NJ. pp. 311-318. Jacob, K.H. and O.J. Perez 1981 Crustal deformation and stress patterns result- ing from the shallowly dipping subduction zone in the Gulf of Alaska. EOS: Transactions, American Geophysical Union 62:398. (Abstract only) Jacob, K.H., K. Nakamura, and J.N. Davies 1977 Trench-volcano gap along the Alaskan- Aleutian Arc: facts, and speculations on the role of terrigenous sediments for subduction. In: Island Arcs, Deep Sea Trenches and Back-Arc Basins. M. Talwani and W.C. Pitman III, editors. Maurice Ewing Series 1. American Geophysical Union, Washington, D.C. pp. 243- 258. Jones, D.L. and H.J. Silberling 1979 Mesozoic stratigraphy — the key to tectonic analysis of southern and central Alaska. U.S. Geological Survey Open File Report 79-1200. 37 pp. Joyner, W.B. and D.M. Boore 1981 Peak horizontal acceleration and velocity from strong motion records including records from the 1979 Imperial Valley, California earth- quake. Bulletin of the Seismological Society of Amer- ica 71:2011- 2038. Kay, S.M., R.W. Kay, and C.P. Citron 1982 Tectonic controls on tholeiitic and calc- alkaline magmatism in the Aleutian Arc. Jour- nal of Geophysical Research 87B:4051-4072. Kienle, J. and S.E. Swanson 1983a Volcanism in the eastern Aleutian Arc: late Quaternary and Holocene centers, tectonic set- ting and petrology. Journal of Volcanology and Geothermal Research 17:393-432. Kienle, J. and S.E. Swanson 1983b The hazards of Augustine. The Northern Engineer 15(3):10-14, 30-37. Kienle, J. and S.E. Swanson 1985 Volcanic hazards from future eruptions of Augustine Volcano, Alaska. Report UAG R-275, Geophysical Institute, University of Alaska, Fairbanks, AK. 122 pp. Kienle, J., S.E. Swanson, and H. Pulpan 1983 Magmatism and subduction in the eastern Aleutian Arc. In: Arc Volcanism: Physics and Tec- tonics. D. Shimozuru and I. Yokoyama, editors. Terra Scientific Publishing Co., Tokyo, pp. 191-224. Kienle, J., J.N. Davies, T.P. Miller, and M.E. Yount 1986 1986-eruption of Augustine Volcano: public safety response by Alaskan volcanologists. EOS, Transactions, American Geophysical Union 67:580- 582 Kienle, J., P.R. Kyle, S. Self, R.J. Motyka, and V. Lorenz 1980 Ukinrek Maars, Alaska, I: April 1977 eruption sequence, petrology and tectonic setting. Jour- nal of Volcanology and Geothermal Research 7:11-37. King, R.B. 1969 Tectonic map of North America, 1:5,000,000. U.S. Geological Survey, Washington, D.C. Kirby, S.H. 1983 Rheology of the lithosphere. Review of Geop- hysics and Space Physics 21:1458-1487. Lahr, J.C. and G. Plafker 1980 Holocene Pacific - North American plate interaction in southern Alaska: implica- tions for the Yakataga seismic gap. Geology 8:483-486. Lahr, J.C. and CD. Stephens 1983 Eastern Gulf of Alaska seismicity. Final report to NOAA, Outer Continental Shelf Environ- mental Assessment Program. Research Unit 210. U.S. Geological Survey, Menlo Park, CA. 52 pp. Lahr, J.C, CD. Stephens, H.S. Hasegawa, and J. Boatwright 1980 Alaskan seismic gap only partially filled by 28 February 1979 earthquake. Science 207:1351- 1353. Seismicity, Tectonics and Geohazakds 181 Lerbekmo.J.F. and F.A. Campbell 1969 Distribution, composition, and source of tbe White River ash, Yukon Territory. Canadian Journal of Earth Sciences 6:109-116. Ludwig, VV.J. and R.F. Houtz 1979 Isopach map of sediments in the Pacific Ocean basin and marginal sea basins. American Asso- ciation of Petroleum Geologists, Tulsa, OK. 2 sheets, 1:13,999,369. McCann, W.R., S.P. Nishenko, L.R. Sykes, andj. Krause 1979 Seismic gaps and plate tectonics: seismic poten- tial for major boundaries. Pure and Applied Geo- physics 117:1082-1147. McCann, W.R., OJ. Perez, and L.R. Sykes 1980 Yakataga Gap, Alaska: seismic history and earthquake potential. Science 207:1309-1314. McKenzie, D.P. and R.L. Parker 1967 The North Pacific: an example of tectonics on a sphere. Nature (London) 216:1276-1280. McNutt, S.R. 1983 Volcanic hazards. A seismotectonic analysis of seismic and volcanic hazards in the Pribilof Islands-Eastern Aleutian Islands region of the Bering Sea. Research Unit 16. K. Jacob and E. House, compilers. Final report submitted to NOAA, Outer Continental Shelf Environmen- tal Assessment Program. Contract NOAA-03-5-022-70. Lamont-Doherty Geo- logical Observatory, Palisades, NY. 224 pp. Miller, DJ. 1960 The Alaska earthquake of July 10, 1958: giant wave in Lituya Bay. Bulletin of the Seismological Society of America 50:253-266. Miller, T.P. and R.L. Smith 1977 Spectacular mobility of ash flows around Aniakchak and Fisher calderas, Alaska. Geology 5:173- 176. Minster, J. B. and T.H.Jordan 1978 Present-dav plate motions. Journal of Geophysi- cal Research 83B:5331-5354. Minster, J.B., T.H.Jordan, P. Molnar, and E. Haines 1974 Numerical modelling of instantaneous plate tectonics. Geophysical Journal of the Royal Astro- nomical Society 36:541-576. Molnar, P., D. Freedman, andJ.S.F. Shih 1979 Lengths of intermediate and deep seismic zones and temperatures in downgoing slabs of lithosphere. Geophysical Journal of the Royal Astro- nomical Society 56:41-54. Munich Reinsurance Company 1984 Volcanic eruption — causes and risks. Munich Reinsurance Company, Munich. 49 pp. Nakamura, K., K.H.Jacob, and J.N. Davies 1977 Volcanoes as possible indicators of tectonic stress orientation — Aleutians and Alaska. Pure and Applied Geophysics (PAGEOPH) 115:86-112. Nakamura, K., G. Plakfer, K.H.Jacob, and J.N. Davies 1980 A tectonic stress trajectory map of Alaska using information from volcanoes and faults. Bulletin Earthquake Research Institute 55:89-100. National Research Council 1972 The Great Alaska Earthquake of 1964. National Academy of Sciences Publication No. 1604, Washington, D.C. 8 volumes. Nishenko, S. and W. McCann 1979 Large thrust earthquakes and tsunamis: implications for the development of fore arc basins. Journal of Geophysical Research 84B:573-584. Page, R. 1973 Page, R. 1975 The Sitka, Alaska, earthquake of 1972: an unex- pected visitor. Earthquake Information Bulletin 5(5):5-9. Evaluation of seismicity and earthquake shak- ing at offshore sites. Offshore Technology Con- ference 1975, Paper OTC 2354. 13 pp. Patwardhan, A.S., R.B. Kulkarni, and D. Tocher 1980 A semi-Markov model for characterizing recurrence of great earthquakes. Bulletin of the Seismological Society of America 70:323-347. Pavlis, T.L. and R.L. Bruhn 1983 Deep-seated flow as a mechanism for the uplift of broad forearc ridges and its role in the exposure of high P/T metamorphic terranes. Tectonics 2:473-497. Perez, O.J. and K.H.Jacob 1980a Tectonic model and seismic potential of the eastern Gulf of Alaska and Yakataga Seismic Gap. Journal of Geophysical Research 85B:7132-7150. Perez, O.J. and K.H.Jacob 1980b St. Elias, Alaska, earthquake of February 28, 1979: tectonic setting and precursory seismic pattern. Bulletin of the Seismological Society of Amer- ica 70:1595-1606. Plafker, G. 1967 Geologic map of the Gulf of Alaska Tertiary province, Alaska. U.S. Geological Survey Mis- cellaneous Geological Investigations Map 1-484. Scale 1:500,000. 182 Physical Environment Plafker, G. 1969 Tectonics of the March 27, 1964, Alaska earth- quake. U.S. Geological Survey Professional Paper 543-1. 74 pp. Plafker, G. 1985 Geologic studies related to earthquake poten- tial and recurrence in the Yakataka Seismic Gap. U.S. Geological Survey NEPEC Meeting, September 8-9, 1985, Anchorage, AK. (Abstract only, with figures) Plafker, G. and K. Rubin 1978 Uplift history and earthquake recurrence as deduced from marine terraces on Middleton Island, Alaska. U.S. Geological Survey Open File Report 78-943. pp. 687-721. Plafker, G., T. Hudson, and D.H. Richter 1977 Preliminary observations on late Cenozoic dis- placements along the Totschunda and Denali Fault System. U.S. Geological Survey Circular 733. pp. 67-69. Plafker, G, T.R. Bruns, G.R. Winkler, and R.G. Tysdale 1982 Cross section of the eastern Aleutian Arc from Mount Spurr to the Aleutian Trench near Mid- dleton Island, Alaska. Geological Society of America Map and Chart Series MC-28-P. Scale 1:250,000. Plafker, G., T. Hudson, T. Bruns, and M. Rubin 1978 Late Quaternary offsets along the Fairweather Fault and crustal plate interactions in southern Alaska. Canadian Journal of Earth Science 15:805-816. Pulpan, H. and C. Frohlich 1985 Geometry of the subducted plate near Kodiak Island and lower Cook Inlet, Alaska, deter- mined from relocated earthquake hypocen- ters. Bulletin of the Seismologkal Society of America 75:791-810. Pulpan, H. and J. Kienle 1979 Western Gulf of Alaska seismic risk. In: Proceed- ings of the Eleventh Annual Offshore Technology Con- ference, April 30-May 3, 1979, Houston, Texas, pp. 2209-2218. Pulpan, H. and J. Kienle 1981 Seismic and volcanic risk studies in the western Gulf of Alaska. Research Unit 251. Environmen- tal Assessment of the Alaskan Continental Shelf, Annual Reports of Principal Investigators 7:197-290. Reyners, M. and K.S. Coles 1982 Fine structure of the dipping seismic zone and subduction mechanics in the Shumagin Islands, Alaska. Journal of Geophysical Research 87B:336-366. Richter, D.H. and N.A. Matson , Jr. 1971 Quaternary faulting in the east Alaska Range. Geological Society of America Bulletin 82:1529- 1539. Riddihough, R. 1984 Recent movements of the Juan de Fuca Plate System. Journal of Geophysical Research 89B:6980-6994. Riehle,J.R. 1985 A reconnaissance of the major Holocene tephra deposits in the upper Cook Inlet region, Alaska. Journal of Volcanology and Geothermal Research 62:37-74. Riehle, J.R., J. Kienle, and K.S. Emmel 1981 Lahars in Crescent River valley, lower Cook Inlet, Alaska. Geological Report 53, State of Alaska Division of Geophysical Surveys. 10 pp. Savage, J.C. and L.M. Hastie 1966 Surface deformation associated with dip-slip faulting. Journal of Geophysical Research 71:4897-4904. Sieh, K. 1981 A review of geological evidence for recurrence times of large earthquakes. In: Earthquake Pre- diction, An International Review. D.W. Simpson and P.G. Richards, editors. Maurice Ewing Series 4. American Geophysical Union, Wash- ington, D.C. pp. 181-207. Silver, E.A., R. von Huene, and J.K. Crouch 1974 Tectonic significance of the Kodiak-Bowie seamount chain, NE Pacific. Geology 2:147-150. Simkin, T., L. Siebert, L. McClelland, D. Bridge, C. Newhall, andJ.H. Latter 1981 Volcanoes of the World. Hutchinson Ross Publish- ing Company, Stroudsburg, PA. 232 pp. Souther,J.G. 1977 Volcanism and tectonic environments in the Canadian Cordillera — a second look. In: Vol- canic regimes in Canada. W.R.A. Baragar, L.C. Coleman, andJ.M. Hall, editors. Geological Association of Canada Special Paper No. 16. pp. 3-24. Stauder, W.S. 1968 Tensional character of earthquake foci beneath the Aleutian Trench with relation to seafloor spreading. Journal of Geophysical Research 73:7693-7701. Stauder, W.S. and G.A. Bollinger 1966 The focal mechanism of the Alaska earthquake of March 28, 1964, and of its aftershock sequence. Journal of Geophysical Research 71:5283-5296. Seismicity, Tectonics and Geohazards 183 Steinbrugge, K.V. 1982 Earthquakes, Volcanoes, and Tsunamis: An Anthology of Hazards. Skandia America Group, New York, NY. 392 pp. Stephens, CD., K.A. Fogleman, J.C. Lahr, and R.A. Page 1984 Wrangell Benioff Zone, southern Alaska. Geol- ogy 12:373-376. Stephens, CD., J.C. Lahr, K.A. Fogleman, and R.B. Horner 1980 The St. Elias, Alaska, earthquake of February 28, 1979: regional recording of aftershocks and short-term pre-earthquake seismicity. Bulletin of the Seismological Society of America 70:1607-1633. Stevenson, A.J., D.W. Scholl, and T.L. Vallier 1983 Tectonic and geologic implications of the Zodiac Fan, Aleutian Abyssal Plain, northeast Pacific. Geological Society of America Bulletin 94:259- 273. Stone, D.B., B.C. Panuska, and D.R. Packer 1982 Paleolatitudes versus time for southern Alaska. Journal of Geophysical Research 87B:3697-3707. Suarez, C, K.H.Jacob, O.J. Perez, and R. Ghosh 1984 Focal depth and tectonic significance of nor- mal faulting earthquakes in the Gulf of Alaska. Earthquake Notes 55:15. (Abstract only) Sykes, L.R. 1971 Aftershock zones of great earthquakes, seis- micity gaps, and earthquake prediction for Alaska and the Aleutians. Journal of Geophysical Research 76:8021-8041. Sykes, L.R. and R.C Quittmeyer 1981 Repeat times of great earthquakes along simple plate boundaries. In: Earthquake Prediction: An International Review. D.W. Simpson and P.G. Richards, editors. Maurice Ewing Series 4. American Geophvsical Union, Washington, D.C pp. 217-247. Sykes, L.R., K. Kisslinger, L. House, J. Davies, and K.Jacob 1981 Rupture zones and repeat times of great earth- quakes along the Alaska-Aleutian Arc, 1784-1980. In: Earthquake Prediction: An Interna- tional Review. D.W. Simpson and P.G. Richards, editors. Maurice Ewing Series 4. American Geophysical Union, Washington, D.C. pp. 73-80. Thenhaus, P.C., J.I. Ziony, W.H. Diment, M.G. Hopper, D.M. Perkins, S.L. Hanson, and S.T. Algermissen 1985 Probabilistic estimates of maximum seismic horizontal ground acceleration on rock in Alaska and the adjacent continental shelf. Earthquake Spectra 1:285-306. Tobin, D.G. and L.R. Sykes 1968 Seismicity and tectonics of the northeast Pacific Ocean. Journal of Geophysical Research 73:3821-3845. Turner, D.L., R.D. Jarrard, and R.B. Forbes 1980 Geochronology and origin of the Pratt- Welker Seamount chain, Gulf of Alaska: A new pole of rotation for the Pacific Pfale.Journtd of Geophysi- cal Research 85:6547-6556. Updike, R.G. 1984 Geologic evaluations of earthquake hazards in the Anchorage area. The Northern Engineer 16(4):18-25. Updike, R.G., L.L. Dearborn, CA. Ulery, andJ.L. Weir 1984 Guide to the Engineering Geology of the Anchorage Area. Alaska Geological Society, Anchorage, AK. 75 pp. von Huene, R. 1979 Structure of the outer convergent margin off Kodiak Island, Alaska, from multichannel seis- mic records. In: Geological and Geophysical Investi- gations of Continental Margins. American Associa- tion of Petroleum Geologists Memoir 29. pp. 261-272. von Huene, R., M.A. Fisher, and T.F. Bruns 1979 Continental margins of the Gulf of Alaska and Late Cenozoic tectonic plate boundaries. In: The Relationship of Plate Tectonics to Alaskan Geol- ogy and Resources: Proceedings of the Sixth Sym- posium. Alaska Geological Society, Anchorage, AK. von Huene, R., G. Keller, T. Bruns, and K. McDougall 1985 Cenozoic migration of Alaskan terranes indi- cated by paleontologic study. In: Tectono- stratigraphic Terranes. D.G. Howell, editor. Earth Science Series No. 1. Circum-Pacific Council for Energy and Mineral Resources, pp. 121-136. Ward, S.N. 1982 Earthquake mechanisms and tsunami genera- tion: the Kurile Islands events of 13 October 1963. Bulletin of the Seismological Society of America 72:759-777. Westgate,J.A. 1982 Discovery of a large-magnitude, late Pleistocene volcanic eruption in Alaska. Science 218:789- 790. Wiegel, R.L., editor 1970 Earthquake Engineering. Prentice Hall, Englewood Cliffs, NJ. 518 pp. 184 Physical Environment Wildenstein-Mori, A. and C.B. Crouse 1981 Strong-motion data from Japanese earth- quakes. Report SE-29, World Data Center A for Solid-Earth Geophysics, NOAA-EDIS, Boulder, CO. (unpaginated) Woodward-Clyde Consultants 1978 Offshore Alaska seismic exposure study (OASES). Prepared for Alaska Subarctic Off- shore Committee (ASOC). Woodward-Clyde Consultants, San Francisco, CA. 6 volumes. Woodward-Clyde Consultants 1982 Development and initial application of soft- ware for seismic exposure evaluation. Final report submitted to NOAA, Outer Continental Shelf Environmental Assessment Program. Contract NA-80- RAC-000-91. Woodward- Clyde Consultants, San Francisco, CA. Vol- umes I and II. Interaction Between Silled Fjords and Coastal Regions David C. Burrell Institute of Marine Science University of Alaska Fairbanks, Alaska Abstract This chapter reviews the oceanography of the silled fjords bordering the Gulf of Alaska — with emphasis on both the physical and the biogeochemical interactions between the estuaries and the contiguous coastal regions. Of necessity, specific exam- ples are drawn predominandy from relatively few localities that have been the sites of multi-year, interdisciplinary studies. However, comparisons are made with more comprehensively studied fjord provinces elsewhere in the world. As in all high lati- tude fjord environments, freshwater and sediment input, primary production, and other biogeochemical processes are subject to intense seasonal fluctuations. In most of the Alaskan fjords studied to date it appears that an entrainment-driven circulation is not well developed, even at the time of maximum freshwater discharge. Circulation in the near-surface region, at intermediate depths, and within the basins (on various time scales) is dominated by events occurring in the coastal zone and within the Gulf. This physical regime in turn generates distinctive annual cycles in the sub-euphotic chemistry. Nutrients regenerated both within the basin column and within soft-bottom sedi- ments are predominantly exported out of the fjords. The Gulf of Alaska fjord province is geologically young, and the mean sediment discharge rate is corres- pondingly large. Sedimentation rates within the fjords may be very high, especially in those glacial fjords where the stratified estuarine circulation is relatively weak. Introduction Although a number of investigators (see review by Dar- nell and Soniat 1979) have emphasized the interdependence of estuaries and their contiguous coastal regions, it has been common practice to treat these marine environments as oceanographically independent entities. Such has largely been the case along the Gulf of Alaska coast. This region has not been studied extensively when compared with neigh- boring, lower latitude environments. For example, few of the more detailed studies of fjord-estuaries along the Gulf coast have included synoptic biogeochemical data from adjacent shelf regions. Inevitably, detailed knowledge of the mutual oceanographic influence of the fjords and the shelf region in the Gulf is very sparse, and the situation is proba- bly little better in fjord provinces elsewhere in the world (Syvitski, Burrell, and Skei, in press). Nevertheless, there is increasing appreciation of the fact that such interactions (Fig. 7-1) are of major importance (Svendsen 1977). The pri- mary purpose of this chapter is to review some of the infor- mation presently available, and hopefully stimulate further interdisciplinary work specifically directed to fjord-ocean interaction problems. The chapter discusses certain inlets in Atmosphere Freshwater Terrigenous Input Shelf Coastal Zonk Import - Water Particulates Dissolved Species Biota Fjord — Fsi t ari ■Export Figure 7-1. Schematic of fjord-coastal water interactions. detail; these inlets are predominantly located along the Alas- kan fjord coast from Ketchikan to the Kenai Peninsula — between 55° and 60°N (see Fig. 7-4; see also Hood, Figs. 1-1 187 188 Pmsic-u Environment through 1-4, Gh. 1, this volume). Conditions in fjords in the adjoining regions of British Columbia are also cited. For various practical reasons, the sampling scales of oceanographic field programs can seldom be optimized for a range of multidisciplinary parameters and processes. Fol- lowing the definition of Mann (1975) and others, it is clear that estuaries — including the near-surface zone of fjords — generally function as autonomous systems only with respect to processes that operate at frequencies of days or less. Thus, Winter, Banse, and Anderson (1975) used an approximately daily sampling scheme to document irregular bursts of phy- toplankton production in Puget Sound, and linked those bursts to short-term mixing events. Most field programs operated in Alaskan fjords sampled at intervals of the order of months. At these frequencies, not only is there the danger of aliasing the data, but the danger that most in-fjord proc- esses are likely to be affected by events occurring outside the fjord. The time and space scales of oceanographic processes are intimately linked, and it is apparent that investigations specifically dedicated to unraveling shelf-estuary interac- tions would require observations that continued over a period of many years. Multi-year trends are evident from the comprehensive oceanographic data obtained for the northern Gulf shelf region (Xiong and Royer 1984). These trends can also be seen over four to five year periods in a southeast Alaska fjord system as is discussed later in this chapter. However, continuing investigations over many more years would be required before low-frequency (order of years) signals can be delineated with any degree of confidence. Physical Interactions Background A two-way water exchange couples the Gulf of Alaska and the fjord-estuaries along the Alaska and British Colum- bia coast. Freshwater that is discharged via fjords and other estuaries is a major influence on shelf transport, and Gulf waters may episodically penetrate into the coastal inlets, replacing both intermediate and deep resident water. The major driving force for geostrophic flow within the sub-surface Gulf mixed layer below 50 m (Royer 1979; Xiong and Royer 1984) is the Aleutian low-pressure system (Fig. 7-2) (Dodimead, Favorite, and Hirano 1963; Royer 1975). This system is dominant throughout the oceanographic winter season. Prevailing cyclonic winter winds (easterlies in the northern Gulf, becoming more southerly with decreasing latitude) generate on-shore Ekman transport along the coasts of Alaska and British Columbia. Computed upwelling-downwelling indices show that the maximum coastal convergence occurs in the north- ern Gulf during January and February (Bakun 1973), and begins progressively earlier (October through December) in the southern Gulf region (the data in Fig. 7-3 from Dodimead 1980 are for a 50°N locality). For greater detail on the meteorological conditions in this region, refer to Chap- ter 2 of this volume by Wilson and Overland. Figure 7-2. Mean seasonal sea-level atmospheric pressure pat- terns (millibars) for the north Pacific. (Modified from Dodimead et al. 1963; Royer 1975.) The Gulf region is predominantly under the influence of weak high pressure centers throughout the summer (approximately May-September) (Fig. 7-2). A relaxation of the intense winter down-welling condition at the coast then permits the run-up of denser water onto the shelf and into the coastal waterways. Wind measurements obtained in the northern Gulf at this time of year (Livingstone and Royer 1980; Royer 1983) do not confirm off-shore, near-surface transport in this region as predicted by computed upwelling 1966 1967 1968 1969 1970 1971 1972 1973 Figure 7-3. Mean monthly on-shore Ekman transport at 50°N, 130°W for the period 1964 to 1973 (data from Dodimead 1980). Silled Fiords and Coastal Regions 189 Win ilr (Dm ) 140 120 \ Norllnvesl v lc'inui\ Of run l()"kg/kms Summer (|i i ■» ) 140 130 120 I ' \ I \ I \ Notthwei u J*. M . i C 1- Yuk 'crri on tor) y l < r r ilcti v \ M.ivk.i ' — I 60 I ^^1^ X s\ ~ I 1 \ \f British I I I I I | I X \Jr Coluinbia I I \ \ 50 Pacific Ocean '^ Canada U.S c Washington . — — "" " KK'kg/k m-s i o ■egon 50 140 Figure 7-4. Mean monthly Ekman transport vectors, northeast Pacific coast, for December andjuly, for the period 1950 to 1959. (Modi- fied from Crean 1967.) indices (Bakun 1973, 1975; see below), although it is apparent from the data of Figure 7-4 (Crean 1967) that coastal diver- gence should increase in importance southwards in the summer. Estuarine Circulation Within the Gulf Coast Fjords The rate of both rainfall and freshwater discharge into the Gulf of Alaska is very high and becomes an important control on circulation (Tully and Barber 1960; Royer 1979). High mountain ranges run continuously along the eastern and northern Gulf coast, and the mean annual precipitation along the margins of both Alaska and northern British Columbia generally exceeds 240 cm (Crean 1967; Royer 1979). Much of this precipitation falls as snow which is stored for later discharge. Local freshwater discharge patterns reflect the relative importance of both stored and direct precipitation and sub- sequent runoff. Because of the rugged terrain within the catchment areas, residence time for rainfall is typically very short. Consequently, peak freshwater influx from these fjords to the Gulf of Alaska occurs in the fall at the time of maximum direct precipitation. The precipitation stored as snow then generates a secondary discharge peak in the spring at lower latitudes (Fig. 7-5A), merging into the late summer-fall maximum in the northern Gulf region (Fig. 7-5B). The maximum freshwater influx from snow melt occurs where large river systems that drain extensive hin- terlands enter the Gulf. This influx normally occurs in spring through summer. This pattern appears to predomi- nate along the coast of northern British Columbia (Pickard and Stanton 1980; Macdonald 1983). In the northern Gulf there is a preponderance of glacial and snow-field run-off, and a paucity of large rivers. Glacial meltwater discharge reaches its peak in late summer to fall. While the single major river in this area — the Copper River — reaches maximum discharge levels in June andjuly (Roden 1967), the mean annual flow is only around 10% of the total regional discharge. This estimate was made by Royer (1979, 1982) from precipitation/run-off box models. Royer' s line-source hydrology models predict maximum freshwater influx into the northern Gulf region in October, coincident with maximum sea-level. Although the mean precipitation rate along the Gulf of Alaska coast is very high, discharge into the head of any par- ticular fjord may be relatively low. This is a consequence of the characteristic watershed topography that surrounds each fjord. For example, the total catchment area for Boca de Quadra fjord (Southeast Alaska) is approximately ten times the marine surface area. Mean annual freshwater dis- charge via the Keta River at the head is 25 m:5/s, increasing to ~ 40 m3/s through the period of maximum discharge in Sep- tember and October (Fig. 7-5A). However, this is only about 15% of the total freshwater influx into this fjord. Discharge 190 Physical Environment A. Ki i \ Ri\ ir (Boca i>e Quadra) 243 272 385 [87 A t "t t A A A 120 - 100 - 80 - T Tt T 60 - I T i 40 - T T ' r . ■ "i" ,i T 20 - ' || 1 T " ii ,i ,i 1 ' ' . -* i i n , _ in*il 111l]nli 1-1 JIl 1978 1979 1980 B. Resurrection River (Resurrection Bay) 1981 400 ■ 300 - T 200 - T 100 - 0 - 1- 1 ll] ,,J ■|«"l« i 1 ,''' 11 I1 1,, 1965 1966 1967 1968 Figure 7-5. Patterns of seasonal freshwater discharge into the heads of two Gulf of Alaska fjords: monthly maxima, minima and means (U.S. Geological Survey Water Resources Data for Alaska, 1965-1981). (A) the Keta River into Boca de Quadra, for the period October 1977 through September 1981; (B) the Res- urrection River into Resurrection Bay, for the period October 1964 to June 1968. around the periphery of the fjord increases the stability of the upper water column, but does little to enhance classic, fjord-type estuarine circulation. Royer (1982) computes a mean coastal freshwater input value for Southeast Alaska of 0.41 km3/y for each kilometer of coastline. This figure is of the same order as Pickard and Stanton's (1980) estimate of 0.44 km3/y. This is nearly 100% greater than the annual mean discharge from the Boca de Quadra watershed. The discrepancy suggests a significant net supply of brackish water outside the mouth of this par- ticular fjord, and Nebert (1982) has shown that a reverse estuarine circulation — inflow at the surface and outflow at depth — may be identified from hydrographic data in the lower reaches of the inlet throughout much of the year. Port Valdez provides another well-documented example of a fjord where the expected two-layer circulation pattern is poorly developed. The mean salinity of the upper 100 m from the head to the mouth remains relatively constant year-round and may even decrease down-fjord in mid- summer (Muench and Nebert 1973). A poorly developed estuarine circulation, substantially confined to the surface 15 to 20 m zone, has been observed in October in this fjord. In addition to the relatively low freshwater discharge at the heads of many Alaskan silled fjords, the large regional tidal ranges must favor a mixed over a layered near-surface circulation. An indication of the relative importance of either pattern is shown by the ratio of freshwater input to the tidal prism. The annual mean of this ratio for Boca de Quadra is 0.012, and corresponding values for some other well-studied Alaskan fjords are all less than 0.05 (Endicott Arm: Nebert 1972; Port Valdez: Muench and Heggie 1978; Resurrection Bay: Heggie and Burrell 1977). Bowden (1980) has noted that estuaries having ratio values less than 0.1 are likely to fall into the partially to well-mixed categories. Stud- ies at Silver Bay, southeast Alaska (McAlister, Rattray, and Barnes 1959; Rattray 1977), have been cited by Dyer (1973) as illustrating entrainment-driven fjord circulation. While this mode of transport may occur in the summer when the ratio of freshwater discharge to tidal prism is around 0.08 (Fig. 7-6B), it rarely occurs through the winter when river inflow is low (Fig. 7-6A). Based on present evidence, it appears that near-surface circulation in Silver Bay is not typical of the circulation that develops in Alaskan fjords in general (see also discussion by Nebert 1985). Fjord Intermediate Water Exchange Shelf processes may cause a sporadic exchange of fjord intermediate water — that zone beneath the near-surface estuarine circulation, and above the sill. In relatively deep- silled fjords, estuarine circulation may be only weakly cou- pled to the intermediate water exchange (Stigebrandt 1981; Farmer and Freeland 1983). The best documented examples have been recorded from the west coast of Norway. Helle (1978) described the monsoonal reversal of the annual wind patterns along this fjord coastline from prevailing south- erlies through the winter to periodic winds from the north in late spring and early summer. On-shore convergence in autumn and winter results in a sea surface set-up at the coast, as well as the barotrophic and induced baroclinic flow of water up-inlet. This has been described for Josenfjord and adjacent inlets along the southwest Norwegian coast by Svendsen (1977, 1980) and modeled by Klinck, O'Brien, and Svendsen (1981). Summer-time wind reversals result in shal- low upwelling of shelf waters at the coast (Svendsen 1981). Subsequent penetration into the fringing fjords is largely dependent on the depths of the barrier sills as described, for example, by Bakke and Sands (1977). Computed transport ranges that are normal to the coast (as illustrated in Fig. 7-3) imply that off-shore Ekman trans- port should result in upwelling along the Gulf coast in the summer (Dodimead 1980), especially in the southern Gulf region (Fig. 7-4). However, Livingstone and Royer (1980) and Royer (1983) do not believe that summer winds reverse the northward-flowing coastal current in the northern Gulf. Silled Fiords and Coastal Rfc;ions 191 A. MaR( H 1 EMPERA I IRl (C) Mean Veloci i v (cm/s) -10 0 10 20 ~i r 30 31 32 33 34 35 Salinity (°/oo) B. JUU Temperature (C) 0 5 10 15 0 Mean Vei «>< m (cm/s) -10 0 10 20 30 20 80 100 1/ / I I I I 1 I 15 20 25 30 35 40 45 Salinity (°/oo) Figure 7-6. Vertical temperature, salinity, and velocity profiles (positive seaward), Silver Bay, Alaska, in March and July 1957. (Modi- fied from Rattray 1977.) Based on Norwegian experience, shallow coastal upwelling would be a significant and readily identifiable phenomenon in the summer because each water mass imported into the fjords has a distinct chemical signature and biota (see fur- ther discussion below). At present, there is no evidence that this occurs anywhere along the Gulf of Alaska coast. Relaxa- tion of the intense winter downwelling condition in the summer does, however, result in an impingement along the coast of relatively deep and dense shelf water as described in the following section. December through February is the period of maximum on-shore convergence in the northern and northeastern Gulf, and near-surface shelf waters are believed (Muench and Schmidt 1975) to be transported into Prince William Sound at this time of year (see also following discussion on zooplankton dynamics). However, to date, a large-scale exchange of intermediate zone water within Alaskan fjords has not been observed in late winter or spring. Figure 7-7 illustrates a temperature-characterized 'event' at around 50 m immediately outside the entrance of Boca de Quadra fjord in April (1983). This water was not present within the immediately adjacent fjord basin, and was no longer evident outside the fjord some six days later. Colonell (1980) has identified similar transient surges of external water into Port Valdez (Prince William Sound), and suggests they result from the passage of local weather systems. Royer (1979) has observed that maximum set-up along the northern Gulf coast occurs in November. This set-up is out of phase with the winter peak in the computed down- welling index, but occurs immediately following the period of maximum annual freshwater influx into the near-shore zone. He believes that freshwater input is the dominant influence on the circulation of the upper mixed layer of the coastal Gulf in this region, and hence, that barotrophic effects on the sea level are small. This pattern may similarly apply in Southeast Alaska and northern British Columbia. Dodimead (1980) shows that maximum sea levels at Prince Rupert (54° N) occur around December (Fig. 7-8), possibly slightly preceding the onset of on-shore Ekman transport which, over the previous five years, has peaked abruptly in January and February. However, maxima recorded over a 20-y period occurred in a range that extends from November to January, and, as noted above, in this region, peak discharge from the major rivers occurs around June and July. Thus, Waldichuk (1964), in an earlier study of the sea level record at Prince Rupert, concluded that the baro- clinic contribution to the pressure field in this region of the Gulf shelf was insignificant. Temperature (C) 75 150 Inside Basin (Station 11) Outside Basin (Station 15) Figure 7-7. Vertical temperature profiles outside and inside the entrance sill of Boca de Quadra fjord, April 1983. (See Fig. 7-27 for longitudinal profile.) 192 Physical Environment 140 13 5 125 11.5 1965 1966 1967 1968 1969 1970 1971 1972 1973 Figure 7-8. Mean monthly sea level values at Prince Rupert, British Columbia, 1964 to 1973 (data from Dodimead 1980). Regardless of driving forces, it would be expected that shallow sub-surface shelf waters would be carried into the coastal waterways and fjords along the northern and eastern Gulf margin primarily in the fall — the period of maximum coastal set-up. It appears that, to date, the shelf-fjord inter- mediate-water exchange in this region has been specifically studied only within Boca de Quadra (a fjord located at 55°N, close to the Alaska-British Columbia border). Brackish surface water from the northern British Columbia rivers is transported northward along the coast (Crean 1967; Dodimead 1980), impacting the coastal waterways and penet- rating into the outer reaches of Boca de Quadra (Nebert 1982, 1984). Figure 7-9A shows that through the winter (October through April 1983), the mean salinity of water between 30 and 50 m is lower outside the fjord than at the head. However, the transport of exterior water found at intermediate depths into the innermost basin at the head of Boca de Quadra has been identified only in the fall and early winter. Figure 7-10 illustrates a water mass that was characterized by higher temperatures, and centered at approximately 50 m both outside the mouth and toward the head of Boca de Quadra fjord in December 1980. Some chemical properties of this intrusion are noted below. Nebert (1984) has also described in detail the advection of warmer and less-saline shelf water at intermediate depths up to the head of this fjord system in October and November 1982. (Penetration over the latter period is marked by the net decrease in salt in the above-100-m region as shown later in Fig. 7-15.) Surface cooling through the winter isolates a warm core near the 50-m depth mark at the head of the fjord, and this core persists until the follow- ing spring. In the southern Gulf region, maximum on-shore con- vergence occurs earlier (around December) (Figs. 7-3 and 7-4) than it does at higher latitudes. Winter on-shore con- vergence has been shown to generate energetic up-fjord movement of water at depths above 180 m within Alberni Inlet on the Pacific coast of Vancouver Island (Stucchi 1983). Cannon and Holbrook (1981) and Holbrook, Cannon, and Kachel (1983) have described in detail major inflows of coastal surface water into the fjord-like Strait of Juan de A. Salinity 32.0 31.5 31.0 305 30.0 Innermost Basin (Station 3A) Outside Mouth (Station 15) Nitrate 30 C V 20 - 15 - Innermost Basin (Station 3A) Outside Mouth (Station 15) Nov dec Jan Feb Mar Apr may jun Jul Aug Sep Oct Nov 1980 1981 Figure 7-9. Mean values of salinity and nitrate concentrations within the 30- to 50-m intermediate water zone outside the fjord, and within the innermost basin, Boca de Quadra, November 1980 to October 1981. (See Fig. 7-27 for longitudinal profile.) S ' I l« )KI >s \NI ) ( I IAS1 M Kl( ,K IN! 19 I Tempera i uw (C) 7 8 50 100 200 Central sill Central Basin (Station 7) Outside Mouth (Station 15) Figure 7-10. Vertical temperature profiles outside the mouth and within the central basin of Boca de Quadra fjord, December 1980. (See Fig. 7-27 for longitudinal profile.) Fuca. Such intrusions also occur predominantly in the winter when more frequent and persistent southerly winds both promote coastal convergence and carry Columbia River water northward to provide an external source of less dense water. Flow into the west coast inlets of Vancouver Island and through the Strait of Juan de Fuca appears to be mainly baroclinic. This sequence thus appears to duplicate, on a larger scale, the intermediate-water exchange observed in Boca de Quadra fjord. Intense down-fjord winds are a common occurrence along the Gulf of Alaska coast in winter, especially in glaci- ated regions. Such katabatic (Squamish or Taku) winds drive the surface layer seaward, promoting localized import and upwelling of intermediate water within the fjords. An exam- ple has been described from the Kitimat system of northern British Columbia by Macdonald, Cretney, Wong, and Erickson (1983). Episodic up-inlet winds may occur along this coast in the spring and summer. Farmer (1972) has described the reversal of the surface currents during such an event within Alberni Inlet. Deep-Water Exchange Sub-sill fjord basin water is replaced from seaward sources when higher density water is available for transpor- tation in over the sill. Since at any time, this process is a func- lion of the relative densities both at the sill height and within the basin, exchange depends both on the supply of denser external waters and on the mixing processes between the basin and the over-lying intermediate water, which pro- gressively reduces the density of the resident basin water. The tidal range along the Gulf coast is larger (mean range of — 3.5-5.0 m, south to north) than along the fjord coast of Norway. Higher velocity tidal currents in the region of sill constrictions generate turbulent mixing, which in turn accelerates the rate at which the density decreases in the sub-sill water. This results in a more extensive deep- water exchange, and lessens the chance that anoxic water will be produced. Farmer and Smith (1980) have shown that super-critical tidal How at the sill can lead to plunging waves that may descend to considerable depths within the basin. Figure 7-11 illustrates the temporal relationship between density at sill height (80 m), and at the bottom ( ~ 365 m) of the central basin of Boca de Quadra fjord. Complete water replacement may occur when these values coincide. In a stratified basin, the water will be replaced to some inter- mediate depth if the source-water density is less than the density of water at the bottom. The deep-water renewal processes in a wide variety of fjords have been reviewed in detail by Gade and Edwards (1980) and by Farmer and Free- land (1983). As described above, water circulation in the Gulf of Alaska exhibits a regular seasonal pattern. The denser water runs up onto the shelf during the summer with the relaxa- tion of the shoreward convergence that dominates in the winter. The shelf surface water, however, has a minimum density in the summer because of increased freshwater dilu- tion and insolation, and a zone of minimum seasonal den- sity variation centered at around 150 m on the northeastern Gulf shelf (Royer 1975) (Fig. 7-12). The density of source waters available to the fjord basins is therefore primarily a function of the sill depth (Muench and Heggie 1978). Near-surface winter shelf water is the densest source water available to shallow-silled fjords. Basin water con- tained by a sill shallower than 150 m (in the northeast Gulf) has a lower density at comparable depths than water found in deep-silled fjords. Depending on the density differential across the sill (determined primarily by year-to-year varia- tions in the source water density) replacement of sub-sill water should occur in the oceanographic winter (January to May). This is the time when the maximum shoreward Ekman transport occurs along much of the Gulf coast; how- ever, mechanisms for transporting source water into shal- low-silled fjord basins in this region have not been studied in detail. Nebert (1972) has shown that the tides may pump denser water that is present outside a shallow sill (Endicott Arm, Southeast Alaska) into the basin. Axially directed winds may also be an important local factor. Yakutat Bay (60°N, 140°W) and its interior fjords are located between the northern Gulf region and southeast Alaska. The Bay consists of a number of basins enclosed by sills found at various depths. The seaward sill — which con- trols the entry of shelf source water — is the shallowest sill (around 25 m). Although the deepest penetration into inte- rior basins occurs in the winter, as predicted, there appears 194 Physical Environment 26.5 -| -.260 c" - 25.5- \r. V 111 C 25.0 245 Central Basin (Station 9) Central Sill (Station 11) 1.2 -, N 1979 M J 1980 J 1981 M J 1982 M J 1983 M 1984 Figure 7-11. Time series distribution of density within Boca de Quadra fjord, October 1979 to March 1984. (Top) Densities at 100-m depth outside the central sill and near the bottom (350 m) of the deep central basin. The shaded zones mark periods of complete flushing of the central basin. (Bottom) Density difference between the source water and resident water at the bottom of the central basin. (See Fig. 7-27 profile for locations.) to be considerable year-to-year variability. Reeburgh, Muench, and Cooney (1976) have shown that in April 1973 a deep but incomplete over-turn occurred in the fjord far- thest removed from the coastal zone. Conditions in the Bay in 1977 are illustrated in Figure 7-13. In this year, replace- ment water had penetrated the outermost basin prior to sampling in early April, but by late July, the innermost basin had not been flushed and the density of the bottom water there was lower (<24.8) than it had been the previous Sep- tember (> 25.0). Fjords separated from the Gulf by sills deeper than ~ 150 m are flushed through the summer season which is the period of minimum coastal downwelling. Figure 7-14 illus- trates this flushing for Resurrection Bay (approximately 60°N, 150° W), a fjord that opens directly onto the Gulf shelf and is guarded by a single sill at a depth of 185 m (Heggie and Burrell 1977, 1981). As the density of the external water at sill height increases in spring and early summer (cf. Fig. 7-11) and then starts to exceed the density of the resident basin water, the basin water is displaced to progressively x h =- w Q 240 - 1971 1972 1973 1974 1975 Figure 7-12. Time series vertical density distributions at a shelf station outside Resurrection Bay, December 1970 to February 1975. (Modified from Royer 1975.) 250 Silled Fiokds and Coastal Regions 195 Si a i io\s YAK9 YAK7 YAK5 YAKS J J L__ -/24.8 10km I I 0 i i i 15.0 _'ii ii — 50 "■"At / 1 24.H- 7 n --._ 100 Depth (m o t • ; 25.0Wc/ -'25.0 1 ' 200 Density (a,) J»iy 1 1 \ 1 250 Figure 7-13. Yakutat Bay showing profile line through basins (100-m contour shown) and station locations (left), and longitudinal density profiles within Yakutat Bay basins, April and July 1977 (right). deeper levels. This happens prior to the multiple flushing of the entire basin that occurs later in the season. The tem- porally changing chemical character of the source water, derived from progressively deeper horizons in the Gulf, is discussed later in this chapter. The flushing behavior of Res- urrection Bay may be contrasted with that of the immedi- ately adjacent shallow-silled ( — 15 m) Aialik Inlet where water replacement occurs in winter (D.L. Nebert, University of Alaska, pers. comm., 1984). Maximum sigma-t (density) values recorded at 200 m in the Aialik basin are less than 25.5, but are greater than 26.5 at the same depth within Res- urrection Bav. Deep-water replacement in fjords on the Pacific coast of Vancouver Island also occurs in the summer (Stucchi and Farmer 1976; Stucchi 1983). The basic winter-summer (shallow-deep silled) flushing patterns exhibited bv the Gulf coast fjords are modified for basins separated from the open shelf bv additional barriers (as is shown in Yakutat Bay: Fig. 7-13). The seaward terminus of the central basin of Boca de Quadra fjord in southeast Alaska is a sill located at ~ 85 meters. Water that lies at inter- mediate depths below the sill is renewed beginning in late spring, and in most years the basin appears to be completely flushed through the summer. Intervals for 1980 to 1982 when the basin was flushed to the bottom are shown in Figure 7-11, and Figure 7-15 (data from Nebert 1984) illustrates the 1982 seasonal progression in terms of the mean net flux of salt into and out of the basin. This particular fjord basin is isolated from direct contact with external source water by an outermost basin (see longitudinal profile of Fig. 7-28 below) where sill-depth water entering the fjord is well mixed with over-lying water. Because of this feature, higher density water is required to flush the central basin than would be predicted based solely on the sill height and the density of the deep central basin water. In other words, the central basin exhibits an annual renewal sequence typical of the deep-sill fjord category defined bv Muench and Heggie (1978). Long-period events in the Gulf may have important impacts on water circulation within the fringing fjords. Dur- ing 1982-1983, a major El Nino event affected water proper- ties in the Gulf (Xiong and Rover 1984), and may have been a contributing cause of non-renewal within the deep central basin of Boca de Quadra in the summer of 1983 (Figs. 7-11 and 7-15). However, Nebert (1985) has shown no correlation between the long-term (38-year) upwelling-index record for the adjacent shelf region and known El Nino events. 196 PinsR \| Ewironment t'pwelliiif. 5 -, I Downwelli ng 0.5 2 a z •1.0 o z 5 -1.5 ;j -2.0 fl N JMMJ S N J MMJ S NJMM 1972 1973 1974 1975 Figure 7-14. Computed seasonal advective transport into the Resurrection Bay basin, and mean monthly upwelling index values (Bakun 1973, 1975) at an adjacent Gulf shelf locality (approximately 60°N, 149° W), November 1972 to May 1975. (Modified from Heg- gie and Burrell 1981.) The annual meteorological patterns in the Gulf are the primary influence on the renewal of sub-sill water within the fringing fjords, because the effect of mixing during storms provides source water of the required density. The annual renewal cycle typical of Alaskan fjords is believed to be expedited by relatively intense vertical mixing of the resi- dent basin water between renewal periods. Tidal energy is the most likely source of subsurface vertical turbulence along this coast. High freshwater run-off has not been observed to block the supply of denser water to the basins — a process that may occur in shallow-silled, poll-type fjords elsewhere (Edwards and Edelsten 1977). Although the renewal of shallow-silled basin waters (such as in Aialik Inlet) is inhibited in the summer when near-surface shelf water salinity is lowest, even the shallowest-silled Alaskan fjords appear to be flushed at least once each year. Nebert (1972) has shown that basin water in Endicott Arm (max- imum sill depth —30 m) is renewed almost continuously throughout the year. Tidal mixing and freshwater input generates a density gradient across the sill in the summer, 835 247 635 — 70 1234 2310 2086 149 0 267 427 414 256 509 395 424 100 - 92 187 28 81 153 504 116 190 183 50 107 25 248 86 77 106 18 187 24 3 46 4 174 125 99 158 30 68 25 51 16 3 12 200 50 112 17 ^ 35 37 81 32 8 49 5 20 17 16 19 5 5 29 49 14 12 41 63 14 8 18 5 11 4 4 13 11 7 11 II 7 pi 6 17 29 5 0 0 5 6 0 2 8 5 7 300 5 4 3 X 6 8 17 0 0 0 5 3 0 2 3 3 3 |w 1" Al <■ 1982 JAN May 1983 JUN OCT Figure 7-15. Seasonal net salt flux (kg/s) up-fjord from the ~ 85 m central sill within Boca de Quadra fjord, April 1982 to October 1983 (see Fig. 7-27 for longitudinal profile). Mean temporal changes for the depth segments and time intervals shown; positive values (net imports) shaded (data from Nebert 1984). Silled Fiords and Coastai Rick ins 197 and during the winter, when freshwater discharge is low, the gradient is maintained because of a relative increase in the density of the source water (Nebert and Burrell 1981). To date, very few individual fjords in Alaska and north- ern British Columbia have been examined in detail. A great deal remains to be learned about circulation patterns in these inlets. For example, since the mean tidal range tends to increase northward along the Gulf of Alaska coast, super- critical flow should be generated at the entrance to shallow- silled fjords. This flow should provide a sub-sill source of turbulent energy that will decrease the mean density of the resident basin water and promote more rapid turn-over. This phenomenon has been recorded in a number of fjords in British Columbia (Stucchi 1980; Farmer 1983), but has not yet been observed in Alaska. Biological Interactions Background The biological coupling between estuaries and con- tiguous shelf areas has received increased attention in recent years. Considerably less is known about higher lati- tude fjord-shelf interactions when compared with the more commonly studied temperate zone environments. Pearson (1985) however, has noted that the impacts of migrating fish as well as of marine mammals and birds are likely to increase with increases in latitude. Fjords along the Gulf of Alaska coast are known to serve as nursery areas for a number of pelagic fish species such as pink salmon fry and herring. Estuarine nekton are characteristically bottom- dwelling species, but there must be free exchange between fjords and the adjacent coastal waters. Unfortunately, there have been no detailed studies of nektonic food webs in estu- aries bordering the Gulf of Alaska that can compare with the work on salmon in the Strait of Georgia done by LeBrasseur, Barraclough, Kennedy, and Parsons (1969). In this section, therefore, only the interchange of planktonic components will be considered. It has been noted previously that the interdependence of physical and biological processes both inside and outside fjords is a function of the relevant time scales. The near- surface, estuarine region of fjords is likely to be an autono- mous ecological system (Mann 1975) only on time scales of less than days. A working relationship linking the residence time of estuarine zone water and phytoplankton turnover rates was initially developed by Ketchum (1954). Lewis and Piatt (1982) have shown that the interaction of physical and biological scales may be quantified in terms of a scale length that is a function of both the longitudinal dispersion and the biological reaction rate. In upper Boca de Quadra fjord, for example, where the computed turnover rate of phytoplank- ton carbon is of the order of days (Burrell 1983b), the corres- ponding scale length appears to be between 1 and 10 kilo- meters. This is somewhat greater than, but comparable to, the scale for a Nova Scotia embavment that was determined bv Therriault and Piatt (1978). Phytoplankton Advection of phytoplankton over long distances within fjords (Braarud, F0yn, and Hasle 1958) and other estuaries (Tyler and Seliger 1978) has been reported. From detailed transport measurements taken at the sill region of Bedford Basin (Nova Scotia) over a 25-hour period, Piatt and Con- over (1971) determined that nearly 60% of one day's phy- toplankton production was flushed into the adjacent coastal zone. Such direct determinations, even over such a short and possibly unrepresentative time period, are logistically very difficult. No equivalent work on potential export (or import) of phytogenous material has been attempted in any west coast fjord. However, knowledge of the periods and sites of enhanced primary production along the Gulf of Alaska coast both provides useful clues, and points to desir- able future work. In high latitude estuaries, a spring-summer diatom bloom keyed to an irradiation threshold (Stockner, Cliff, and Shortreed 1979; Hegseth 1982; and Erga and Heimdal 1984) is the most distinctive feature of phytoplankton growth. In southeastern Alaska, this event spans a few weeks (or less) between late March and early May (Fig. 7-16), and generally occurs progressively later in the year northward along the Alaskan fjord coastline. The peak bloom in Port Valdez in 1972 was in late April (Goering, Shiels, and Patton 1973) (Fig. 7-17) and in Resurrection Bay in 1974 in June (Heggie and Burrell 1977). For the localities illustrated in Figure 7-16, Burrell (1983b) computed that some 40% of the annual depth-integrated primary production (135 gC/m2 in 1980) occurred over a 28-day period in March and April. 35 3 0 - 7 25 s o b0 Z 2.0 h U D a i2 1.5 10 Inner Basin (Station 3A) Central Basin (Station 9) Jan fkb mar Apr May Jin |i i Aug sir o< i Nov dec Figure 7-16. Depth-integrated 14C uptake rates through the euphotic zone within Boca de Quadra fjord in 1982 (data from Burrell 1983b and VTN 1983). 198 Physical Environment Inside (Port Valdez) Jan Feb Mar Apr may Figure 7-17. Annual depth-integrated 14C uptake rates through the euphotic zone within Port Valdez fjord. Com- posite of data obtained in 1971-1972. (Modified from Goering, Shiels, and Patton 1973.) In the absence of intense grazing and high turbidity, blooms may develop in those nutrient-rich waters that become stabilized to the point that turbulence does not per- sistently transport the cells below a critical depth. Because of increased freshwater discharge in the spring, this condition usually occurs earlier inside northern estuaries than it does in contiguous shelf regions. Blooms within fjords on the west coasts of Scotland and Norway commence several weeks earlier than they do on the adjacent shelves (Braarud 1974; Tett and Wallis 1978). Goering, Shiels, and Patton (1973) monitored seasonal carbon uptake both within Port Valdez and outside the sill in Valdez Arm, and found con- temporaneous bloom periods (Fig. 7-17). However, in this case, a major portion of the freshwater influx occurs in the vicinity of the sill, and Muench and Nebert (1973) demon- strated that near-surface stratification at the time of the spring bloom did not differ significantly at these two localities. To date, there have been no synoptic 14C uptake measurements taken both within and outside any other Alaskan fjord. Within glacial fjords in particular, it has been observed (e.g., in Port Valdez: V. Alexander, University of Alaska, pers. comm., 1985) that a turbid fresh water influx occurring in spring may suppress or limit the intensity of the diatom blooms. In both shelf and coastal waters, contem- poraneous grazing may prevent a bloom from developing even though increasing insolation tends to stabilize the sur- face zone. From late spring into summer, freshwater influx into the fjords increases and the characteristic entrainment-driven circulation should generally assume greater importance. Increased or maintained phytoplankton population levels then require a suitable balance between turn-over rates and the residence time of the near-surface water within the fjord (Ketchum 1954). Computed phytoplankton carbon turn-over rates in upper Boca de Quadra and Smeaton Bay are around 1.0/d both at the time of the spring bloom and in early summer. Phytoplankton residence times are therefore probably much shorter than the mean residence time of the near-surface waters at the heads of these inlets. The flushing time of water within Port Valdez has been variously esti- mated at between 20 and 40 days (Muench and Nebert 1973; Colonell 1980). These values are predicated on complete mixing of the water column, and the residence time of the near-surface water is probably considerably smaller. If vari- able turbidity levels and other localized factors are ignored, conditions in Port Valdez should theoretically permit devel- opment of an autochthonous bloom which could extend throughout the inlet. Simultaneous sampling both inside Port Valdez and within the narrows region external to the sill (Goering, Shiels, and Patton 1973) showed that, although the bloom is near contemporaneous, the diatom species composition and dominance is different. This suggests that communion is not maintained both inside and outside the fjord proper, and may be due to increased turbulence in the vicinity of the sill. In both Port Valdez (Horner, Dick, and Shiels 1973) and Boca de Quadra fjord (VTN 1983), it has been shown that, following the termination of the spring diatom bloom, there is a major change in the phytoplankton community struc- ture. Smaller flagellate species assume dominance along with algae which generally have higher carbon uptake effi- ciencies, lower nutrient half-saturation constants, and a greater tolerance to reduced salinities. Phytoplankton pro- duction is characteristically nutrient limited in the post-bloom, summer-fall period in high-latitude, stratified estuaries. This certainly appears to be the case in Port Val- dez and Boca de Quadra (the only Alaskan fjords that have been studied in detail to date) where, for example, 15N- uptake experiments show that regenerated ammonia con- stitutes the primary source of nitrogen through the summer (Goering, Patton, and Shiels 1973; S. Whalen, University of Alaska, unpubl. data, 1984). Under these conditions, the enhancement of phytoplankton production (and potential export) requires the local injection of additional nutrients into the euphotic zone. The two primary potential sources of 'new' nutrients (sensu Dugdale and Goering 1967) are the rivers, and the sub-euphotic marine waters. In most parts of the world, high nutrient concentrations are carried seaward by mature river systems that drain large watersheds — especially in areas that are subject to agricultural drainage and urban dis- charges. Parsons, Albright, and Parslow (1980) and Harrison, Fulton, Taylor, and Parsons (1983) estimate that up to 30% of the nitrogen utilized in the Strait of Georgia may be sup- plied by the Fraser River (with sewage contributing less than 10%). There are examples in this region (Parsons, Stephens, and LeBrasseur 1969), and in fjord provinces elsewhere Silled Fjords and Coastal Regions 199 (Therriauk, de Ladurantaye, and Ingram 1984), where pro- ductivity in coastal waters that are affected hy the plumes of major rivers exceeds the productivity in adjacent fjords. Phytoplankton productivity in such cases is enhanced both because of the influx of riverine nutrients, and because of vertical entrainment of nutrient-rich marine waters from below. This may lead to imports of particulate organic mate- rial into the bordering fjords. As discussed previously, a number of large rivers inject water into the northward- flowing Alaska Coastal Current System, and conditions sim- ilar to those described in southern British Columbia may occur locally. In the southern-most part of Alaska it appears that, although brackish water from the large rivers of northern British Columbia is transported into the coastal waterways in the spring, there may be only slight penetration into the fjords (only two have been studied in detail). However, over a four-year period, the dominant diatom species of the spring blooms changed from year to year, but was the same in any one year in two adjacent fjords. This may argue for external seeding. In south central Alaska, where fjords open directly onto the Gulf shelf, there is a slight indication that an up-fjord drift of near-surface water occurs in the summer. It has been suggested (Heggie 1983), for example, that Copper River water impacts the mixed zone of Resurrection Bay at this time of year. Nutrients supplied by bay-head rivers are frequently cited as the primary cause of elevated phyto- plankton production, or of secondary blooms, during the summer in Norwegian fjords (Sakshaug and Myklestad 1973). This is especially true in polls (Wassmann and Aad- nesen 1984). However, this appears not to be the case for the majority of fjords along the Gulf of Alaska coast. Naiman and Sibert (1978) have noted that heavy precipitation along the west coast of Canada has resulted in highly leached soils and a low nutrient content in the rivers. It is generally believed that the nutrient levels of the freshwater that is dis- charged into Alaskan fjords are significantly lower than lev- els in the non-depleted marine water. This is certainly the case both for precipitation that is initially stored as snow and for non-glacial rivers where the residence time of rain- fall in the relatively small catchment areas is very short (Sugai and Burrell 1984). The chemistry of glacial meltwater in Alaska has not been systematically studied, but Goering, Patton, and Shiels (1973) stated that freshwater discharge into Port Valdez is rich in both silicic acid and nitrate. Other examples may also be cited where riverine influx of nutrients is locally important. For example, Brickell and Goering (1970) and Sugai and Burrell (1984) have demon- strated enhanced production in southeast Alaskan fjords at the time when decaying salmon resulted in higher ammonia concentrations in the rivers. However, because the fresh- water influx into fjords in summer is relatively insignificant when compared with the tidal exchange, it is believed that, in general, riverine nutrients are a very minor contribution to phytoplankton growth in this fjord province. Sub-surface marine water is the primary reservoir of the 'new' nutrients necessary to enhance phytoplankton pro- duction. River-plume entrainment is one method of inject- ing this water into the euphotic zone. Other mechanisms that may be operating within fjords include wind mixing, estuarine circulation, and periodic destabilization of die- surface waters by higher-than-average tides (Webb and D'Elia 1980). Short-term (order of days) fluctuations in pro- ductivity levels recorded in several fjords (Winter el al. 1975; Takahashi, Seibert, and Thomas 1977) may be attributable to such sporadic mixing of the near-surface zone. Under such conditions, a net export of autochthonous biogenic mate- rial from the fjord into the coastal zone might be expected. Primary production may be enhanced in coastal frontal zones (Pingree, Holligan, and Mardell 1978; Parsons, Stronach, Borstad, Louttit, and Perry 1981). These zones are typically shallow regions of increased flow where vertical turbulence promotes upward transport of nutrients into the depleted surface zone. Parsons, Perry, Nutbrown, Hsieh, and Lalli (1983) and Parsons, Dovey, Cochlan, Perry, and Crean (1984) have demonstrated that sustained increases in phytoplankton production may occur in shoal areas adja- cent to the mouths of certain fjords in southern British Columbia. Because of the high tidal range, similar enhance- ments in the northern Gulf region would be expected at the mouths of shallow-silled fjords. There is some preliminary evidence for this inside the 15-m sill of Aialik Inlet (D.C. Burrell, University of Alaska, unpubl. data, 1984), but there have been no direct studies of this phenomenon in any Alas- kan fjord. Parsons (Ch. 18, this volume) suggests that for various rea- sons (including the summer-time upwelling activity described above) mean primary production along the Gulf of Alaska shelf break is higher than it is within the fjords. However, no unequivocal shallow coastal up welling events — such as are responsible for episodically advecting coastal waters into the fjords of Nova Scotia (Therriault, Lawrence, and Piatt 1978) and western Norway — have been recorded within the fjords along the Alaskan coastline in the summer. In western Norway, Braarud (1975), Kattner, Ham- mer, Eberlein, Brockmann, Jahnke, and Krause (1983), Erga and Heimdal (1984), and others have demonstrated that influxes of coastal water may terminate existing fjord blooms, transport in remnant shelf communities, or re-seed with species better adapted to the new physical environ- ment. For example, Kattner et al. (1983) note that Thalassiosira nordenskioeldii is better adapted to cold water conditions. No comparable abrupt changes in phytoplank- ton species composition have been recorded to date in coastal fjords along the Gulf. In late summer and fall, differences in mean levels of pri- mary production both inside and outside the fjord may be further accentuated as river-generated turbidity pro- gressively limits the euphotic zone up-fjord. This prevents or suppresses secondary blooms which commonly occur at this time of year. The phenomenon has been extensively documented for a mainland British Columbian fjord (Stock- ner, Cliff, and Buchanan 1977), and is a general charac- teristic of Alaskan glacial fjords. Thus, the absence of the sec- ondary October bloom within Port Valdez, which is evident outside the sill entrance in Valdez Arm (Fig. 7-17), has been attributed to high glacial silt loading towards the head of the fjord (Goering, Shiels, and Patton 1973). In Boca de Quadra (a non-glacial fjord), Sugai and Burrell (1984) have shown 200 Physical Environment that the peak river discharge of riverine-soluble humic material may also locally attenuate the euphotic zone at this time of year. In shallow water estuaries, unit-area primary production by the fringing macrophytic algae and vascular plant com- munities may be at least an order of magnitude greater than phytoplankton production (Mann 1982; Seki 1982). Since a large proportion of detritus from these sources is relatively refractory, seaward transport may be a significant source of energy to the shelf benthos. However, because of their rug- ged topography, fjords characteristically have very reduced littoral zones. Pickard and Stanton (1980) catalogued a wide range of Pacific coast fjords and determined the intertidal to subtidal area ratios to be in the range 1:13 to 1:40. The inter- tidal regions of Smeaton Bay fjord amount to only 2.1% of the marine surface area inside the entrance sill (Burrell 1983b). It is estimated that littoral primary production within the adjacent Boca de Quadra fjord cannot exceed, and is probably far less than, 15% of the marine phy- toplankton production. Although floating wracks — especially of Fucus — are commonly observed within the lat- ter fjord, export into the contiguous waterways is believed to be insignificant. Zooplankton Both the seasonal distribution and the community struc- ture of herbivores are major factors controlling fjord ecol- ogy. At a relatively basic level, fjords can be considered in terms of the two generalized trophic pathways discussed by Greve and Parsons (1977) and by Landry (1977). These path- ways lead from small phytoplankton and zooplankton to jellyfish and similar predators, and from net phytoplankton, primarily diatoms, to the larger copepods and finfish. The frequently cited review by Matthews and Heimdal (1980) related these two patterns to poll- and fjord-estuaries, respectively — polls being both shallower and shallower- silled types of fjords. Wassmann (1983) noted that the basin depth within Lindaspollene in western Norway — perhaps the archetypical and most commonly referenced poll sys- tem— is too shallow to permit over-wintering of larger copepods. However, the most important feature of polls — stressed by Matthews and Heimdal (1980) — is that the shal- low sill intercepts the pycnocline. Along the western Nor- wegian coast in particular, where tides are moderate and freshwater inflow is frequently high, this physical configura- tion acts as an effective barrier to recruitment of the larger calanoid copepod species from outside. Such characteristic differences in zooplankton ecology within two adjacent Norwegian fjords have been summarized by Fosshagen (1980). Factors other than the residence time of the water are usually important. In more open, turbulent fjords, primary production sustained by renewal of nutrients into the euphotic zone (and in some cases, advection of external phy- toplankton stocks) are factors required to support popula- tions of the large copepods. However, import of zoo- plankton into fjords from adjacent coastal regions appears to be a common — if not a characteristic — feature of regular fjords (Matthews, Hestad, and Bakke 1978; Falk-Petersen and Hopkins 1981). No comparable spatially and temporally detailed studies of zooplankton community structure have been carried out in Alaskan fjords, although there have been a number of survey investigations. The epipelagic zooplankton ecology of Boca de Quadra and Smeaton Bay (Southeast Alaska) over a three-year period has been summarized by VTN (1983), who have shown that summer holoplankton in the surface 25-m zone consists predominantly of small copepod species. For exam- ple, in Boca de Quadra in 1980, calanoid copepods such as Pseudocalanus and Acartia made up over 70% of the popula- tion, and in Smeaton Bay in 1981 P. minutus, A. longiremis, and Paracalanus parvus made up approximately 65% of the total. This mixture represents a classic poll-type community structure. Densities are relatively low in the spring and gen- erally appear to increase through July and August. There is no firm evidence that the spring phytoplankton bloom in these fjords, which appears, based on phaeopigment dis- tributions, to peak in late summer, is terminated by grazing. However, Burrell (1983b) has shown that the preliminary seasonal carbon-flux balance in the upper column only allows for a 10 to 15% sedimentation rate for phytogenous material falling out of the euphotic zone at the time of the spring bloom. This suggests that much more intensive graz- ing is possibly occurring below the euphotic zone. Figure 7-18 shows chlorophyll a and phaeopigment concentrations within Boca de Quadra in April 1983. At the time it was sampled (believed to be during the termination stage of the bloom) the phytoplankton biomass was essentially confined to the central and innermost basin regions, but phaeopig- ment to chlorophyll ratios were elevated in the near-surface water of the outermost basin. Such distributions suggest either that there is intensive grazing by the copepods that are advected into the outer reaches of the fjord where the intervening ( ~ 85 m) sill acts as a barrier to external recruit- ment, or that there is transportation of detritus into the fjord from the outside. The latter event has been docu- mented for several fjords on the west coast of Scotland by Solorzano and Grantham (1975). Damkaer (1976) recorded over-wintering populations of Neocalanus spp. within Prince William Sound, and it might be expected that larger copepod species would remain within the fjord systems — like Boca de Quadra — that incor- porate deep basins. However, it is apparent that, since spring blooms are an annual feature of all Gulf coast fjords examined to date, phytoplankton production and grazing are uncoupled early in the season, and such fjords cannot be regarded as simple mesocosms of the adjacent shelf environ- ment. A number of investigators (Parsons 1965; Frost, Landry, and Hassett 1983; see also recent review by Miller, Frost, Batchelder, Clemons, and Conway 1984) have shown that the plant-herbivore system within the Gulf of Alaska is in balance in the spring, and that the biomass increase at this time results from an increase of grazers, not of phytoplankton. Populations of large oceanic copepods would be expected in the near-surface zone of many Alaskan fjords in spring (R.T. Cooney, University of Alaska, pers. comm., 1985) as a consequence of the prevailing patterns of on-shore transport of shelf waters as described in a pre- vious section. The pattern may be envisaged with reference Silled Fjords and Coastal Regions 201 A. •BQ15 i30°4cr B. B(M o 5 20 I HOI IB Si \ i ki\s BQ9 BQ5 BQ3A 50 \ \ I ^t!l^// tL-5.0— > ; Cj£Z >1.0 L0 0 y^ . v> ^y " >1.0 / / / Chlorophyll 5.0mg/m3 c. £ 20 I = 30 40 • \\ ' — /* ^ 1 j S ^^ O^ --^ < 25 "**" i -•' r>( >50 ft 1 100 V \ \0 >50 /X / / u <*> / Phaeopigment/Chlorophyll it x 100 ■jP | | values >100 Lower Boca dc Quadra ^ Upper Boca de Quadra 60 50 40 30 20 10 Distance from Heap of Fjord (km) Figure 7-18. Longitudinal sections for surface to 50-m depth zone within Boca de Quadra fjord and suhsidiary Marten Arm, April 1983. (A) Location map showing station positions. The primary sill is located at Kite Island (see Fig. 7-27 for longitudinal profile). (B) Isopleths of chlorophyll a. (C) Ratio of phaeopigment to chlorophyll a x 100. to Neocalanus plumchrus, a large, ubiquitous copepod found along the fjord coast of Alaska and British Columbia. The life-cycle seasonal migrations of this organism (Fulton 1973) are shown in Figure 7-19. Adults over-winter in deep water (and hence resident populations should exist in a number of the deep fjord basins along the Gulf coast), but later migrate and feed as late copepodite stages near the surface around the time of maximum plant production. This ontogenic sequence and the coupling with the vernal diatom bloom has been best documented for the Strait of Georgia (Par- sons, LeBrasseur, Fulton, and Kennedy 1969; Parsons, LeBrasseur, and Barraclough 1970; and Harrison et al. 1983). The migration of A', plumchrus and allied oceanic species into the upper regions of the shelf column occurs at the time of coastal convergence. This migration provides a means of recruitment into contiguous fjord environments. Krause and Lewis (1979) described in detail the seasonal advection of Eucalanus bungii into Knight Inlet, British Columbia. Cooney (University of Alaska, unpubl. data, 1984) has shown that large copepods are advected from the Gulf shelf into Prince William Sound, and N. plumchrus is present in Port Valdez in the spring (Cooney, Redburn, and Shiels 1973). However, detailed work on the potential coupling between the Gulf and specific Alaskan fjords has not yet been attempted. It might be expected that the greatest potential impact would be in those shallow-silled fjords where basin water exchange occurs predominantly in late winter and spring. However, as noted previously, from the limited observations available, it appears that the penetration of near-surface water into southeast Alaska fjords is much weaker in late winter than in early winter. Waters outside these fjords at this time of year are derived primarily from Inside Passage regions farther to the south in British Colum- £200 1 400 /c I-IV \ \ /Nauplii I-V'I / ' \ Copepodite V ^ Eggs V. Copepodite V J Adult VI Oct Nov UK Jan Flu Mar Acr Mav Jin )i 1 AUG Sep Figure 7-19. Schematic of life cycle of Neocalanus plumchrus in the Strait of Georgia: depth zones of nauplii, copepodites, and adults through the year. (Modified from Fulton 1973.) 202 Physical Environment bia, rather than being derived directly from the Gulf. Such observations may partially explain why large oceanic zoo- plankters such as N. plumchrus have not been observed in the euphotic zone up-fjord within either Boca de Quadra or Smeaton Bay at the time of the spring bloom. Meroplankton Time-series abundances of macro-infauna at two deep ( — 160 and 385 m) fjord basin stations in southeast Alaska are illustrated in Figure 7-20. There is an annual cycle of spring/summer recruitment followed by winter die-back, as well as a multi-year density fluctuation. Although pelagic larval development generally decreases in importance at high latitudes, this is the primary means of reproduction employed by invertebrates along the Gulf coast (H.M. Feder, University of Alaska, pers. comm, 1984). Pearson (1980) has noted that factors controlling the recruitment to fjord benthic communities are not well understood, but he believes that curtailment of free exchange between silled fjords and the adjacent coastal waters must be important. Both Pearson (1971) and Gage (1972a) suggest that the observed blurring of classic benthic community boundaries in fjords may be the result of larval confinement within the basins. However, Gage (1972b) has also concluded that there is a reduced benthic infaunal diversity in the shallow-silled Loch Etive when compared with neighboring fjords because of the physical barrier to larval import. Carpenter (1983) sug- gests that pandalid shrimp — either as larvae or adults — are transported into Aialik Inlet (northern Gulf) on flood tides and are then trapped behind the shallow ( — 15 m) sill. Migrations of invertebrate larvae depend both on water circulation patterns and on the the distribution of the adults 10,000 -i 5000 500 100 - Inner Basin (Station 3A) Centra! Basin (Station 7) 1979 1980 1981 1982 1983 Figure 7-20. Seasonal densities of macro-infauna (>1 mm) at two basin localities (270 m depth in central basin, and 140 m in inner basin) within Boca de Quadra fjord, 1979 to 1983 (data from VTN 1983). (Fig. 7-27 shows longitudinal profile.) (Harding, Vass, and Drinkwater 1982). Unfortunately, the dispersion dynamics for most larval groups are less well known in west coast fjord environments (Levings, Foreman, and Tunnicliffe 1983) compared with many better-studied temperate estuaries (Kennedy 1982). It has been generally supposed that there is a wide broadcasting of larvae in the coastal zone, and Scheltema (1975) stated that most larvae produced within well-flushed estuaries are unlikely to be retained to maturity. In recent years however, in-estuarine larval retention has been increasingly emphasized (Sulkin and Van Henkelen 1982). Strathmann (1982) noted that dis- persion is especially unlikely to be a favorable survival strat- egy in those estuaries that have strong physical and chemical gradients. However, in general, these strictures should be less applicable to fjords than to most other types of estuaries. Chemical Interactions Background Attempts have been made to determine the oxygen and nutrient budgets (incorporating import-export terms) for a number of temperate estuaries. These estuaries have been both mixed and partially mixed, and determinations were made by applying relatively simple one- and two-layer box models (e.g., Bowman 1977; Taft, Elliot, and Taylor 1978). This approach may not be easily applied to silled fjords in toto because the circulations above and below the sill barrier are generally poorly coupled. However, for using these pro- cedures, the above-sill region of the fjords should be a very suitable environment for quantifying the reactions and the transport of chemical constituents — especially in summer when stratification is at its greatest (Hamilton, Gunn, and Cannon 1985). Based on mean oxygen distributions, Gilmar- tin (1964) estimated that about 25% of the phytoplankton production was lost from a British Columbian fjord. As emphasized previously, the stratified estuarine flow that has been studied in the Alaskan fjords was found to be poorly developed, and for those fjords, tidal mixing and exchange is correspondingly more important than in many other fjord provinces. Therefore, determining the import-export exchange at the sill boundaries is a difficult exercise, and no attempt has been made to model the above-sill distribution of a non-conservative constituent within any Gulf coast fjord. Seasonal oxygen and nutrient budgets within the basins are a more tractable problem, and this is the primary topic considered here. (It should be noted, therefore, that both the oxygen and the nutrient distribution patterns described in this section do not directly relate to the auto- chthonous primary production discussed previously.) Nutrients Surface and Intermediate Waters Nutrients are renewed in the surface zone each winter when water column stability is at a minimum. During the summer, uptake by the phytoplankton results in nutrient minima in the well-stratified near-surface zone. Increased Silled Fiords and Coastal Regions 203 primary production at this time necessitates the import of exogenous nutrient supplies. In some fjord regions, the rivers may he a primary source (Wassmann and Aadnesen 1984), leading to an export into the coastal /.one. However, since it appears that the influx of freshwater nutrients into many (most?) fjords along the Gulf of Alaska coast is rela- tively insignificant, 'new' nutrients must be supplied from marine sources. Upward infusion from the sub-euphotic region may occur via the mechanisms outlined in the pre- vious section. The flux rates for nutrients moving between the Alaskan fjords and the external coastal regions are unknown since no detailed synoptic observations have been attempted. As noted above, in two fjords located near the Alaska-British Columbia border, water found between the estuarine circulation zone and the sill (Fig. 7-9 illustrates mean conditions between 30 and 50 m in Boca de Quadra) may be more brackish outside than inside the estuary. The coastal transport of freshwater in this area results in charac- teristic seasonal nutrient patterns within this transitional depth zone. For example, Figure 7-9B shows that nitrate is at higher concentrations year-round within the inner region of Boca de Quadra than it is outside the mouth. In fjord provinces elsewhere in the world, on-shore con- vergence during the summer may result in periodic whole- sale changes in the integrated nutrient contents of the near- surface waters (with concomitant changes in the plankton community structure, as discussed above). This phe- nomenon has been well described for inlets along the Nova Scotia coast by Piatt, Prakash, and Irwin (1972). Wassmann (1984) has demonstrated how an influx of shelf water into Fanafjord (west coast of Norway) at relatively shallow depths may effectively eliminate the reservoir of sub-euphotic nutrients at the time when euphotic zone concentrations are at their lowest. Similar abrupt changes have not been observed in Alaskan fjords during the major phytoplankton production season. However, an influx of low-salinity water into the intermediate zone of a southeast Alaskan fjord at the onset of coastal downwelling has been described (Fig. 7-10). This water, which has a long residence time at the head of the fjord, has lower nutrient concentrations than the resident, penetrated water. Figure 7-21 illustrates con- temporaneous silicic acid profiles both outside and inside the estuary in November. It has been frequently observed that primary production is stimulated in the vicinity of large river plumes (see phy- toplankton section), and Skreslet (1981) suggests that entrained nutrients associated with freshwater discharge along the west coast of Norway are a major factor influenc- ing biological productivity in the adjacent coastal waters. The integrated flux of fresh water that feeds the Alaska coastal current is very large, but any effect on the indigenous biota is presently unknown. Deep Waters Nutrient species are regenerated within the basin water column, and especially within the soft-bottom sediments. It is believed that the major supply of labile organic material to depth occurs during the summer and hence that the max- imum rate of remineralization occurs in summer as well. In ;>u Silk am- (uM H,Si<), 30 40 Si) 200 Outside Mouth (Station 15) Central Basin (Station 9) Figure 7-21. Vertical profiles of silicic acid concentrations within the upper water column outside the mouth and within the central basin of Boca de Quadra fjord, December 1980. those Alaskan fjords where the sill is deeper than the zone of minimum annual density variation on the adjacent shelf, this is the season of deep-water renewal within the basins. No evidence of the benthic flux is retained within the basin column. However, during the oceanographic winter season when the relatively deep-silled basins along the Gulf coast tend to be advectively isolated, nutrient species effluxed from the sediments may accumulate if the regeneration sup- ply exceeds the rate of upward loss out of the basin. Figure 7-22 illustrates elevated concentrations of nitrate and silicic acid in the bottom waters of the central basin of Boca de Quadra in April, prior to deep-water renewal. From early spring through autumn (in deep-silled basins), a complex intermittent exchange sequence occurs. Shelf water of increasing density penetrates to deeper levels within the basin and flushes out the nutrient pool which has accumulated during the winter (Fig. 7-23). This expulsion of nutrient-rich water represents a subsidy to the exterior coastal regions at a time when phytoplankton production may be at a seasonal maximum. However, F0yn and Rev (1981) found a negligible impact on the primary production in coastal waters as nutrients were flushed from the fjords along the west coast of Norway. Water that initially penetrates and flushes the basins has a relatively low nutrient content (Fig. 7-23). The resident basin water is displaced upwards into the intermediate zone at this time, and patches of displaced, high-nutrient water may persist up-fjord for extended periods. Macdonald (1983) has identified such uplifted remnants within the Kitimat fjord system of northern British Columbia, and an example from the head of Boca de Quadra is shown in Fig- ure 7-24. Basin water that is injected into the long-resi- dence-time, intermediate (above-sill) zone at the head of 204 Physical Environment Stations 9 7 6 I I I Maximum concentration >6() (uM H4Si04-Si) 60 50 40 30 20 10 0 Distance from Head of Fjord (km) Figure 7-22. Longitudinal profiles of soluble nitrate and silicic acid concen nations within Boca de Quadra fjord, April 1980. Samples taken at localities and depths shown; shaded areas show regions of maximum concentrations. the fjord, while brackish water dominates outside the fjord mouth, may be a primary explanation for the longitudinal nitrate gradient demonstrated in Figure 7-9B. Progressively throughout the summer, denser water masses with their higher nutrient concentrations are emplaced in the basins. By September and October (immediately prior to the winter isolation period), Boca de Quadra reaches its highest annual mean nutrient content within the basin. A similar pattern occurs in Resurrection Bay in the central Gulf (Fig. 7-25), and is likely to be a characteristic feature of deep-silled fjords all along this coast. In Resurrection Bay, Boca de Quadra, and other deep- silled Alaskan fjords, nutrients regenerated at and within the sediments accumulate within the basins throughout the winter and are then flushed from the fjord during the sum- mer. However, elevated concentrations may be restored during the latter part of the deep water renewal sequence in late summer and fall. Although there are no detailed mass- balance computations, it is estimated that in Boca de Quadra in 1981, the autochthonous production of silicic acid, and its import into the basin from outside, were nearly balanced. Both the annual benthic flux (which is peri- odically flushed either directly out of the basins or up into the intermediate zone), and the net advective import between mid-September and mid-October (at the end of the summer renewal period) are estimated to be in the range of2()-to25 x 106 moles. Within this same fjord, it is interesting to compare the preliminary transport-rate estimates for remineralized nutrients across the soft-bottom basin interface with the phytoplankton requirements in the overlying near-surface zone (Burrell 1983b). The rate of carbon degradation within the deep central basin region appears to be around 10% of the mean annual primary uptake value (Burrell 1983a). From a knowledge of the diatom fraction present through the primary summer production period, phytoplankton sil- icon requirements are estimated to be ~ 1.5 M/m2y, and, via a number of independent procedures (Burrell 1983b; Hong and Burrell, University of Alaska, unpubl. data, 1985), the benthic flux is estimated to be in the range of 9 to 36% of the euphotic uptake. Both computations are sensitive to the ratio between the fjord surface area and the soft-bottom substrate surface area — a ratio that can only be approximated. These data suggest that any phytoplankton production that is over and above the production that is stimulated by nutrients regenerated in situ is not primarily or directly I Maximum concentration >60 (uMH^SiO,) Minimum concentration <5 33 Minimum concentration < 1,0 50 40 30 20 10 Distance from Head of Fjord (km) Figure 7-23. Longitudinal profiles of silicic acid concentra- tions in Boca de Quadra fjord, May and July 1980. Shaded areas show regions of maximum and minimum concentrations. Silled Fiokds and Coastal Regions 205 Aucusn 60 50 40 30 20 10 Distance from Head op Fjord (km) Figure 7-24. Longitudinal profiles of silicic acid concentra- tions, in Boca de Quadra fjord, August and October 1981. Shaded areas show regions of maximum concentrations. fueled by the nutrients that are derived from the immedi- ately underlying basin sediments. Throughout the summer growth season, the near-surface zone is well stratified. This means that nutrient resupply will most likely be from exter- nal sources both via estuarine circulation and via various localized shallow mixing processes. One potential method for estimating the nutrient subsidy required from outside the fjord is to measure the net downward sedimentation of phytogenous detritus out of the euphotic zone. This method is currently being attempted in Boca de Quadra using sedi- ment-trap measurements. Dissolved Oxygen The oxic-anoxic character of basin waters is controlled to a large extent by the transport patterns of dissolved oxy- gen progressing from shelf regions into the fjords. The fjord basins examined to date along the northern and central Gulf coast (except in the case of the deep basin of Boca de Quadra in 1983) have been flushed at least annually, and sub-sill waters within Alaskan fjords have not been observed to go anoxic at any time. It would appear, there- fore, that in these higher latitude estuaries, the labile organic detritus supply and degradation rates rarely out- strip the oxygen resupply rate during the period. Saanich Inlet, on the southeast coast of Vancouver Island, is a com- monly cited seasonally anoxic fjord (Anderson and Devol 1973) which is also flushed annually. However, dissolved oxygen within the fjord basin is naturally depleted within a few months. There is also some input of anthropogenic car- bon into this fjord. Burrell (1983b) has estimated a mean winter time oxygen use rate of 68 nM/hy within the deep central basin of Boca de Quadra. This estimate is based on net rates of decrease and computed resupply rates from the above-sill 'reservoir' over the same time intervals. Benthic oxygen-consumption rates were determined from incubated core samples that were retrieved from the deepest region of the same basin. The rates were some three times greater in the summer than in the winter (433 and 156 |j.M7m2h, respectively) (G. Hong, University of Alaska, unpubl. data, 1984). This indicates that the mean annual basin consumption rate is about double the winter value. Even so, this is a much smaller utilization rate than the values given by Barnes and Gollias (1958) and by Christensen and Packard (1976) for areas within the tem- perate zone system of Puget Sound (195 and 238 |iM7hy, respectively). It should be noted that the latter authors believed that less than 10% of their observed oxygen increase was attributable to vertical diffusional resupply, whereas in Boca de Quadra it appears that about half of the oxygen consumed in the basin and sediments is contempo- raneously transported in across the free basin boundary. Heggie and Burrell (1981), using an advection-diffusion model structured for fjord basin conditions, have computed year-round (i.e., for both the winter advectively isolated and summer flushing periods) oxygen utilization rates of 170 \i MlVy within the basin of Resurrection Bay on the north cen- tral Gulf coast. Seasonal dissolved oxygen concentration patterns in the fjord basins are, predictably, approximately the reverse of the nutrient distributions discussed above. During the 200 1977 1978 1979 Figure 7-25. Time-series vertical distribution of nitrate (|iM NO,"-N) within Resurrection Bay, November 1977 to March 1979. The shaded zone marks period of complete flush- ing of the basin. 206 Physical Environment winter in deep-silled basins, dissolved oxygen levels decrease as consumption exceeds replacement. (Consump- tion rates are believed to be generally at a minimum at this time of year, however.) The initial spring-summer flushing event emplaces water having a relatively high dissolved oxy- gen content and having relatively low nutrient concentra- tions. However, denser replacement waters that enter at the end of the summer flushing period typically have reduced oxvgen concentrations and an elevated nutrient content. This pattern generally reflects the depth at which the source water originated as the density of the intrusions increases. This is well illustrated by the summer time sequence observed in Boca de Quadra in 1980 (Fig. 7-26). Helle (1978) has noted that upwelled water along the Norwegian fjord coast has a relatively low dissolved oxygen content because the source water is originally shelf water which has been advected into the coastal trough. However, replacement water entering Alaskan deep-silled fjords in late summer and fall is believed to be relatively deep water from the Gulf. Freeland (1983) recorded upwelling of low oxygen-con- centration water along the west coast of Vancouver Island. In a fashion that is analogous to that described for soluble nutrient species, intrusions of denser water sinking to depth within the basins displace resident low-oxygen water towards the surface. This transport occurs on a time scale of days to weeks and may severely impact the sessile benthic fauna, as has been demonstrated in Saanich Inlet by Tun- nicliffe (1981). Figure 7-27 illustrates both the uplift and the isolation of remnants of winter water at the head of Boca de Quadra fjord in July. Water within the basins is replaced by progressively denser water throughout the summer. However, both the oxygen and the nutrient content of the source water varies non-linearly throughout the summer, and hence these parameters may serve as useful, quasi-conservative tracers of successive infusions. The computed conservative 'NO' index has been used to map advective intrusions into Rus- sell Fjord (Yakutat) (Reeburgh et at. 1976; Reeburgh and Kip- 300 1979 1980 1981 Figure 7-26. Time-series vertical distribution of dissolved oxy- gen (ml/1) within the central basin (Station 9) of Boca de Quadra fjord, September 1979 to October 1981 (see Fig. 7- 27 for location). 50 40 30 20 10 0 Distance from Head of Fiord (km) Figure 7-27. Longitudinal profile of dissolved oxygen con- centrations (ml/1) within Boca de Quadra fjord, July 1980. Shaded area shows region of maximum concentrations (>8 ml/1, 357 uM/1). phut, Ch. 4, this volume). However, since deep water replacement is generally independent of the mixed-layer circulation, in the few other Gulf coast fjords studied in any detail, individual nutrient and oxygen tracers appear to function equally well. Time-series dissolved oxygen concentrations at the bot- tom ( — 365 m) of the central Boca de Quadra basin are shown in Figure 7-28. It is apparent that over this three- year observation period there has been a progressive decline in the mean oxygen content of the bottom water in each successive winter. Assuming a nearly constant mean annual flux of labile carbon, this pattern probably reflects changes in the shelf source waters that enter the fjord in the summer. This parallels the multi-year decrease in density referred to previously. 1979 1980 1981 1982 Figure 7-28. Time-series dissolved oxygen concentrations near the bottom (350 m) of the central basin of Boca de Quadra fjord, September 1979 to December 1982. The shaded zones mark periods of complete flushing of the basin. Su i fd Fjords and Coastal Regions 207 Dissolved Organic Carbon and Heavy Metals Sugai and Burrell (1984) give a mean figure of 10.6 g C/m2y (carbon per unit area of watershed) as the amount of dissolved organic carbon (DOC) that is exported into Smeaton Bay, a fjord adjacent to the British Columbia boundary in Southeast Alaska. While this value is high when compared with values from temperate zone rivers (Schlesinger and Melack 1981), it is comparable to values recorded for the Nanaimo River of southeast Vancouver Island (Naiman and Sibert 1978). Comparatively high dis- charge rates of terrestial DOC may therefore be charac- teristic of Gulf coast fjords. The mean annual concentration of DOC found in major rivers that feed into Smeaton Bay is about twenty times greater than the particulate organic car- bon (POC) concentration. The DOC concentration reaches a peak both in late spring to early summer and in the fall. Since these are periods of maximum freshwater discharge, the major DOC input flux (80% of the annual total of ~4.5 x 108 moles) also occurs at these times. The highlv polymerized humic compounds of dissolved organic material (DOM) that are found in the rivers floccu- late upon mixing with seawater (Sholkovitz 1978; Morris, Mantoura, Bate, and Howland 1978), so this fraction is gen- erally believed to constitute a relatively small proportion of the total freshwater humate pool (Hunter 1983). Mantoura and Woodward (1983) have shown that the bulk of the DOM discharged by the rivers consists of the more soluble fulvic acids which are not immediately sedimented under estuarine conditions. This means that during the summer, terrigenous DOC mav be exported into coastal regions of the Gulf. Significant quantities of certain soluble heavy metal spe- cies may also be exported seaward out of the fjords. The sta- bilitv of humic-metal compounds generally appears to par- allel the Irving-Williams series (Schnitzer and Khan 1972). Copper and iron, in particular, are believed to form high- stability soluble complexes in natural waters. Abundant evi- dence shows that both these elements may be substantially complexed by humic material in anoxic sediment pore waters (Krom and Sholkovitz 1978; Mantoura, Dickson, and Riley 1978), and Lieberman (1979) believes that 20 to 50% of the soluble copper in Lake Nitinat, a permanently anoxic fjord on the Pacific coast of Vancouver Island, is organically complexed. Wrhile much less is known about organo- metallic bonding in aerobic marine environments, this may be the primary explanation for the conservative behavior of the copper that was observed (Holliday and Liss 1976; Hunter 1983) in estuaries that received high influxes of humic material. A conservative distribution of copper through the fresh-marine mixing zone of Boca de Quadra is illustrated in Figure 7-29 (data from Erikson and Stukas 1983). Similarly, Sugai and Burrell (1984) showed that acid- soluble iron decreases only slightly with increasing salinitv in the adjacent Smeaton Bay fjord, in contrast to the sub- stantial removal of acid-soluble iron that was recorded both in more temperate estuaries (Bovle, Edmond, and Sholkovitz 1977; Sholkovitz, Boyle, and Price 1978), and in laboratory mixing experiments (Bale and Morris 1981). In Smeaton Bay (and presumably also in other Gulf of Alaska fjords) there appears to be a mechanism that allows soluble 400 350 he 300 -a: "So B 250 200 150 Innermost Basin (Station 3A) ( entral Basin (Station 9) 15 20 Salinity (°/oo) 25 30 35 Figure 7-29. Soluble (<0.4 uM) copper concentrations versus salinity in the central and innermost basins of Boca de Quadra fjord, in September 1983 (data from Erickson and Stukas 1983). iron to be maintained and transported in marine water, and hence possibly out into contiguous shelf areas. From mass balance computations applied to Resurrec- tion Bay, Heggie (1983) suggests that copper may be trans- ported in from exterior coastal regions. Because of the large volume of freshwater that is discharged into the Alaska Coastal Current System, it has been noted that the near- surface transport of brackish water into the fringing fjords may be a common occurrence at certain times of the year. The imported copper found in Resurrection Bay could, therefore, originate from suitable freshwater sources such as the Copper River further south along the Gulf coast. Geological Interactions Input of terrigenous sediment into the Gulf coast fjords occurs primarily throughout the summer. Since a river's ability to transport particulate material is an exponential function of its flow rate, the sediment-mass flux is the high- est during enhanced-volume discharge. This occurs during the spring-summer thaw, and especially in late summer- fall, which is the period of maximum direct precipitation. Over 90% of the sediment deposited by the Keta River into upper Boca de Quadra fjord is carried in during a few weeks in September-October. This happens primarily during major storms, since the residence time of rainfall in the catchment area is very short. VTN (1984) showed that both suspended load and precipitation maxima, some 3 to 4 km upstream from the mouth of the river, coincide without notable hysteresis. 208 Physical Environment Fjords are generally well stratified throughout the sum- mer. Particulate sediment that is added at the surface of well-stratified estuaries tends to be transported shelfward along with the brackish surface layer. It may be generalized that less sediment is deposited within this kind of estuary than in more thoroughly mixed estuaries. Turbid sediment plumes that extend long distances seaward are charac- teristic features of many glacial fjords (Burrell 1972). How much of this material is carried beyond the confines of the fjord to the open shelf regions depends largely upon the supply rate, upon local hydrographic conditions, and upon the physiography of the inlet. In this respect it is instructive to compare conditions within Alaskan fjords with more thoroughly documented examples from along the mainland coast of British Columbia. For example, mean freshwater discharge from the Homathko River into the head of Bute Inlet is around 250 m;5/s, and the mean annual influx of par- ticulate sediment may approach 10" mt (Syvitski and Farrow 1983). In this fjord, Syvitski, Asprey, Clattenburg, and Hodge (1985) have described the behavior of the largely inorganic particulate sediment within defined upper and lower pro- delta environments. In this case, the upper prodelta environment is the river-dominated near-field. Seaward from this region, particulate sediment concentrations were found to be related to the distance from the riverine source by a constant empirical power function. (Sedimentation rates are a function of the square of the mean particle radius.) Finer particles are carried progressively further sea- ward and, in Bute Inlet, particulate sediment-load con- centrations may exceed 1 mg/1 some 50 km down-fjord from the head. In contrast, the mean freshwater influx into the head of Boca de Quadra fjord (25 m3/s: Fig. 7-5A) is around an order of magnitude less than the influx into Bute Inlet. Particulate loads in the surface zone do not generally exceed 1 mg/1 except within a few kilometers of river outfalls in late summer (and locally at the time of the spring bloom). As discussed previously, because of both the relatively low freshwater discharge into the heads of many Alaskan fjords and the strong tidal signal along the Gulf coast, strat- ified estuarine circulation flow patterns may not be well developed. In these cases, particulate sediment tends to be deposited closer to the source. Sills physically retain sedi- ment within the fjord basins, which invariably are sites of net sediment accumulation. All fjord-estuaries are geo- logically recent features and, as a generalization, mean rates of sediment discharge are a function of their relative age. Sedimentation rates of the order of 0.01 cm/y have been recorded for mature European fjords (Aarseth, Bjerkli, Bjorklund, Boe, Holm, Lorentzen-Styr, Myhre, Ugland, and Thiede 1975; Calvert and Price 1970). However, the Gulf coast province is very young, and in glacial inlets, annual depositions as high as 1 to 10 m have been measured (Hoskin and Burrell 1972; Mackiewicz, Powell, Carlson, and Molnia 1984). Sedimentation regimes within fjords along the British Columbia-Alaska coast — contrasted with fjord domains elsewhere in the world — have been discussed in detail by Syvitski et al. (in press) and will not be reiterated here. It is possible that sediment — especially biogenic mate- rial— that originates from seaward of the fjord may be trans- ported in and trapped within the basins of some fjords (Syvitski et al., in press). This could occur, for example, if more productive surface water was advected in over the sill, as has been described for the Saguenay Fjord, Quebec — a fjord that borders the relatively productive estuary of the St. Lawrence River (Therriault, de Ladurantaye, and Ingram 1980, 1984). Comparable examples have not been described for the Gulf of Alaska region, however. Most shelf sediment has probably been transported by the relatively few major rivers which drain into the Gulf. This has been best documented to date for the northeast Gulf region as discussed by Hampton, Carson, Lee, and Feely (Ch. 5, this volume). Gatto (1976) has estimated that the mean sediment discharge from rivers entering Cook Inlet approaches 3 x 107 mt/y, and most of this material is carried through the Inlet and deposited in the Shelikof Strait to the west of Kodiak Island (Feely and Massoth 1982). This region also receives large quantities of sediment from the Copper River. Hein, Bouma, Hampton, and Ross (1979) have shown that material derived from these two major river systems may be distinguished on the basis of characteristic suites of clay minerals. Acknowledgments Funding support for the preparation of this chapter was furnished by the Minerals Management Service, Depart- ment of the Interior, through a Memorandum of Under- standing between the National Oceanic and Atmospheric Administration, Department of Commerce, and the Univer- sity of Alaska, and with support from the State of Alaska. Much of the data discussed in the chapter originated from grants and contracts with the author from the Department of Energy, the National Science Foundation, and from the United States Borax and Chemical Corporation. Major con- tributions from past and present graduate students, and especially from Drs. D.T. Heggie and S.F. Sugai are grate- fully acknowledged. I thank D.L. Nebert for many stimulat- ing discussions, and V. Alexander, R.T. Cooney, D.L. Nebert, A.J. Paul of the University of Alaska, and the exter- nal reviewers for critical and helpful comment. This review is contribution No. 600 from the Institute of Marine Science, University of Alaska. Silled Fjords and Coastal Rfgions 209 References Aarseth, L, K. Bjerkli, K.R. Bjorklund, D. Boe, J.P. Holm, T.J. Lorentzen-Styr, L.A. Myhre, E.S. Ugland, and J. Thiede 1975 Late quaternary sediments from Korsfjorden, western Norway. Sarsia 58:43-66. Anderson, J.J. and A.H. Devol 1973 Deep water renewal in Saanich Inlet, an inter- mittently anoxic basin. Estuarine and Coastal Marine Science 1:1-10. Bakke, J.L.W. and N.J. Sands 1977 Hydrographical studies of Korsfjorden, west- ern Norway, in the period 1972-1977. Sarsia 63:7- 16. Bakun, A. 1973 Coastal upwelling indices, west coast of North America, 1946-71. NOAA Technical Report NMFS SSRF- 671. 103 pp. Bakun, A. 1975 Daily and weekly upwelling indices, west coast of North America, 1967-73. NOAA Technical Report NMFS SSRF-693. 114 pp. Bale, A.J. and A.W. Morris 1981 Laboratory simulation of chemical processes induced by estuarine mixing: the behaviour of iron and phosphate in estuaries. Estuarine, Coastal, and Shelf Science 13:1- 10. Barnes, C.A. and E.E. Collias 1958 Some considerations of oxygen utilization rates in Puget Sound. Journal of Marine Research 17:68- 80 Bowden, K.F. 1980 Physical factors: salinity, temperature, circula- tion, and mixing processes. In: Chemistry and Biogeochemistry of Estuaries. E. Olausson and I. Cato, editors. John Wiley & Sons, New York, NY. pp. 37-70. Bowman, M.J. 1977 Nutrient distributions and transport in Long Island Sound. Estuarine and Coastal Marine Science 5:531-548. Boyle, E.A., J.M. Edmond, and E.R. Sholkovitz 1977 The mechanism of iron removal in estuaries. Geochimica et Cosmochimica Acta 41:1313-1324. Braarud, T. 1974 The natural history of the Hardangerfjord. 11. The fjord effect upon the phytoplankton in late autumn to early spring, 1955-56. Sarsia 55:99-114. Braarud, T. 1975 The natural history of the Hardangerfjord. 12. The late summer water exchange in 1956, its effect upon phytoplankton and phosphate dis- tribution, and the introduction of an offshore population into the fjord in June, 1956. Sarsia 58:9-30. Braarud, T., B. F0yn, and G. Hasle 1958 The marine and freshwater phytoplankton of the Dramsfjord and the adjacent part of the Oslofjord, March-December 1951. Hvalradets Skrifter 43:1-103. Brickell, D.C. andJ.J. Goering 1970 Ghemical effects of salmon decomposition on aquatic ecosystems. In: Water Pollution Control in Cold Climates. R.S. Murphy and D. Nyquist, edi- tors. U.S. Government Printing Office, Wash- ington, D.C. pp. 125-138. Burrell, D.C. 1972 Suspended sediment distribution patterns within an active turbid-outwash fjord. In: Pro- ceedings of the International Conference on Port and Ocean Engineering. S.S. Wetteland and P. Bruun, editors. University of Trondheim, Norway, pp. 227- 245. Burrell, D.C. 1983a Patterns of carbon supply and distribution and oxygen renewal in two Alaskan fjords. Sedimen- tary Geology 36:93-115. Burrell, D.C. 1983b The biogeochemistry of Boca de Quadra and Smeaton Bay, Southeast Alaska: summary report on investigations 1980-1983. Unpub- lished report, Institute of Marine Science, Uni- versity of Alaska, Fairbanks , AK. Calvert, S.E. and N.B. Price 1970 Composition of manganese nodules and man- ganese carbonates from Loch Fyne, Scotland. Contributions to Mineralogy and Petrology 29:215-233. Cannon, G.A. andJ.R. Holbrook 1981 Wind-induced seasonal interactions between coastal and fjord circulation. In: The Norwegian Coastal Current: Proceedings from the Norwegian Coastal Current Symposium. R. Saetre and M. Mork, editors. University of Bergen, Bergen, Norway, pp. 131-151. Carpenter, T.A. 1983 Pandalid shrimps in a tidewater-glacier fjord, Aialik Bay, Alaska. M.S. Thesis, University of Alaska, Fairbanks, AK. 122 pp. 210 Physical Environment Christensen, J.P. and T.T. Packard 1976 Oxygen utilization and plankton metabolism in a Washington fjord. Estuarine, Coastal and Marine Science 4:339-347. Colonell, J.M., editor 1980 Port Valdez, Alaska: Environmental Studies 1976-1979. Occasional Publication No. 5, Institute of Marine Science, University of Alaska, Fairbanks, AK. 373 pp. Cooney, R.T., D.R. Redburn, and W.E. Shiels 1973 Zooplankton studies. In: Environmental Studies of Port Valdez. D.W. Hood, W.E. Shiels, and E.J. Kelley, editors. Occasional Publication No. 3, Institute of Marine Science, University of Alaska, Fairbanks, AK. pp. 297-302. Crean, P.B. 1967 Physical oceanography of Dixon Entrance, British Columbia. Fisheries Research Board of Canada Bulletin No. 156. 66 pp. Damkaer, D.M. 1976 Initial zooplankton investigations. Environmen- tal Assessment of the Alaskan Continental Shelf Annual Reports 7:31-56. Darnell, R.M. and T.M. Soniat 1979 The estuary/continental shelf as an interactive system. In: Ecological Processes in Coastal and Marine Systems. RJ. Livingston, editor. Plenum Press, New York, NY. pp. 487-525. Dodimead, A J. 1980 A general review of the oceanography of the Queen Charlotte Sound - Hecate Strait - Dixon Entrance region. Canadian Manuscript Report, Fisheries and Aquatic Science No. 1574, Department of Fisheries and Oceans, Nanaimo, B.C. 248 pp. Dodimead, A.J., F. Favorite, and T. Hirano 1963 Salmon of the North Pacific Ocean. Part II. Review of the oceanography of the subarctic Pacific Ocean. International North Pacific Fisheries Commission Bulletin No. 13. 195 pp. Dugdale, R.C. andJJ. Goering 1967 Uptake of new and regenerated forms of nitro- gen in primary productivity. Limnology and Oceanography 12:196-206. Dyer, K.R. 1973 Estuaries: A Physical Introduction. John Wiley & Sons, London. 140 pp. Edwards, A. and D.J. Edelsten 1977 Deep water renewal of Loch Etive: a three basin Scottish fjord. Estuarine and Coastal Marine Sci- ence 5:575-585. Erga, S.R. and B.R. Heimdal 1984 Ecological studies on the phytoplankton of Korsfjorden, western Norway. The dynamics of a spring bloom seen in relation to hydro- graphical conditions and light regime. Journal of Plankton Research 6:67-90. Erickson, P. and V. Stukas 1983 Trace metals in Boca de Quadra using the vac- uum intercept pumping system. Unpublished report to U.S. Borax and Chemical Corpora- tion, Los Angeles, CA. Seakem Oceanography Ltd., Victoria, B.C. 20 pp. Falk-Peterson, S. and C.C.E. Hopkins 1981 Ecological investigations on the zooplankton community of Balsfjorden, northern Norway: population dynamics of the euphausiids Thy- sanoessa inermis (Kroyer), Thysanoessa raschii (M. Sars) and Meganyctiphanes norvegica (M. Sars) in 1976 and 1977 '. Journal of Plankton Research 3:177-192. Farmer, D.M. 1972 The influence of wind on the surface waters of Alberni Inlet. Ph.D. Thesis, University of Brit- ish Columbia, Vancouver, B.C. 240 pp. Farmer, D.M. 1983 Stratified flow over sills. In: Coastal Oceanogra- phy. H.G. Cade, A. Edwards and H. Svendsen, editors, Plenum Press, New York, NY. pp. 337-362. Farmer, D.M. and H.J. Freeland 1983 The physical oceanography of fjords. Progress in Oceanography 12:147-220. Farmer, D.M. andJ.D. Smith 1980 Tidal interaction of stratified flow with a sill in Knight Inlet. Deep-Sea Research 27A:239- 254. Feely, R.A. and G.J. Massoth 1982 Sources, composition, and transport of sus- pended particulate matter in lower Cook Inlet and northwestern Shelikof Strait, Alaska. NOAA Technical Report ERL 415-PMEL 34. 28 pp. Fosshagen, A. 1980 How the zooplankton community may vary within a single fjord system. In: Fjord Oceanogra- phy. H.J. Freeland, D.M. Farmer, and CD. Lev- ings, editors. Plenum Press, New York, NY. pp. 399-405. F0yn, L. and F. Rey 1981 Nutrient distributions along the Norwegian Coastal Current. In: The Norwegian Coastal Cur- rent: Proceedings from the Norwegian Coastal Cur- rent Symposium. R. Saetre and M. Mork, editors. University of Bergen, Bergen, Norway, pp. 626-639. Silled Fiords and Coastal Regions 2T1 Freeland, H.J. 1983 A seasonal upwelling event observed off the west coast of British Columbia, Canada. In: Coastal Oceanography. H.G. Gade, A. Edwards and H. Svendsen, editors. Plenum Press, New York, NY. pp. 217-223. Frost, B.W., MR. Landry, and R.P. Hassett 1983 Feeding behavior of large calanoid copepods Neocalanus cristatus and A', plumchrus from the subarctic Pacific Ocean. Deep-Sea Research 30:1-13. Fulton, J. 1973 Some aspects of the life history of Calanus plumchrus in the Strait of Georgia. Jouriuil of the Fisheries Research Board of Canada 30:811-815. Gade, H.G. and A. Edwards 1980 Deep water renewal in fjords. In: Fjord Oceanography. H.J. Freeland, D.M. Farmer, and G.D. Levings, editors. Plenum Press, New York, NY. pp. 453-489. Gage, J. 1972a Community structure of the benthos in Scot- tish sea-lochs. I. Introduction and species diversity. Marine Biology (Berlin) 14:281-297. Gage, J. 1972b A preliminary survey of the benthic macro- fauna and sediments in Lochs Etive and Creran, sea lochs along the west coast of Scotland. Journal of the Marine Biological Associa- tion of the United Kingdom 52:237-276. Gatto, L.W. 1976 Circulation and sediment distribution in Cook Inlet, Alaska. In: Assessment of the Arctic Marine Environment. D.W. Hood and D.C. Burrell, edi- tors. Occasional Publication No. 5, Institute of Marine Science, University of Alaska, Fair- banks, AK. pp. 205-277. Gilmartin, M. 1964 The primary production of a British Columbia F)ord. Journal of the Fisheries Research Board of Can- ada 21:505-538. Goering, J.J., E.J. Patton, and W.E. Shiels 1973 Nutrient cycles. In: Environmental Studies of Port Valdez. D.W. Hood, W.E. Shiels, and E.J. Kelley, editors. Occasional Publication No. 3, Institute of Marine Science, University of Alaska, Fair- banks, AK. pp. 225-248. Goering, J.J. , W.E. Shiels, and C.J. Patton 1973 Primary production. In: Environmental Studies of Port Valdez. D.W. Hood, W.E. Shiels, and E.J. Kelley, editors. Occasional Publication No. 3, Institute of Marine Science, University of Alaska, Fairbanks, AK. pp. 251-278. Greve, W. and T.R. Parsons 1977 Photosynthesis and fish production: hypo- thetical effects of climactic change and pollu- tion. Helgolander wissenschaftliche Meeresunter- suchungen 30:666-672. Hamilton, P., J. I ". Gunn, and G.A. Cannon 1985 A box model of Puget Sound. Estuarine, Coastal, and Shelf Science 20:673-692. Harding, G.C., W.P. Vass, and K.F. Drinkwater 1982 Aspects of larval American lobster (Homarus americanus) ecology in St. Georges Bay, Nova Scotia. Canadian Journal of Fisheries and Aquatic Sciences 39:1117-1129. Harrison, P.J., J.D. Fulton, F.J.R. Taylor, and T.R. Parsons 1983 Review of the biological oceanography of the Strait of Georgia: pelagic environment. Cana- dian Journal of Fisheries and Aquatic Sciences 40:1064-1094. Heggie, D.T. 1983 Copper in the Resurrection fjord, Alaska. Estuarine, Coastal, and Shelf Science 17:613-635. Heggie, D.T. and D.C. Burrell 1977 Hydrography, nutrient chemistry and primary productivity of Resurrection Bay, Alaska, 1972-75. Report R77-2, Institute of Marine Science, University of Alaska, Fairbanks, AK. Ill pp. Heggie, D.T. and D.C. Burrell 1981 Deep water renewals and oxygen consumption in an Alaskan fjord. Estuarine, Coastal, and Shelf Science 13:83-99. Hegseth, E.N. 1982 Chemical and species composition of the phy- toplankton during the first spring bloom in Trondheimsfjorden, 1975. Sarsia 67:131-141. Hein, J.R., A.H. Bouma, M.A. Hampton, and C.R. Ross 1979 Clay mineralogy, fine-grained sediment dis- persal, and inferred current patterns, lower Cook Inlet and Kodiak Shelf, Alaska. Sedimen- tary Geology 24:291-306. Helle, H.B. 1978 Summer replacement of deep water in Byfjord, western Norway: mass exchange across the sill induced by coastal upwelling. In: Hydrodynamics of Estuaries and Fjords. J-C.J. Nihoul, editor. Elsevier Scientific Publishing Co., Amsterdam, pp. 441-464. Holbrook, J.R., G.A. Cannon, and D.G. Kachel 1983 Two-year observations of coastal-fjord inter- actions in the Strait of Juan de Fuca. In: Coastal Oceanography. H.G. Gade. A. Edwards, and H. Svendsen, editors. Plenum Press, New York, NY. pp. 411-426. 212 Physical Environment Holliday, L.M. and P.S. Liss 1976 The behaviour of dissolved iron, manganese and zinc in the Beaulieu Estuary, S. England. Estuarine and Coastal Marine Science 4:349-353. Horner, R.A., L.S. Dick, and W.E. Shiels 1973 Phytoplankton studies. In: Environmental Studies of Port Yaldez. D.W. Hood, W.E. Shiels, and EJ. Kelley, editors. Occasional Publication No. 3, Institute of Marine Science, University of Alaska, Fairbanks, AK. pp. 283-294. Hoskin, CM., and D.C. Burrell 1972 Sediment transport and accumulation in a fjord basin, Glacier Bay, Alaska. Journal of Geol- ogy 80:539-551. Hunter, K.A. 1983 On the estuarine mixing of dissolved sub- stances in relation to colloid stability and sur- face properties. Geochimica et Cosmochimica Acta 47:467-473. Kattner, G., K.D. Hammer, K. Eberlein, W.H. Brockmann, J. Jahnke, and M. Krause 1983 Nutrient and plankton development in Rosfi jorden and enclosed ecosystems captured from changing water bodies during POSER. Marine Ecology — Progress Series 14:29-43. Kennedy, V.S., editor 1982 Estuarine Comparisons: Proceedings of the Sixth Biennial International Estuarine Research Con- ference. Academic Press, New York, NY. 709 pp. Ketchum, B.H. 1954 Relation between circulation and planktonic populations in estuaries. Ecology 35:191-200. Klinck, J.M., J.J. O'Brien, and H. Svendsen 1981 A simple model of fjord and coastal circulation interaction. Journal of Physical Oceanography 11:1612-1626. Krause, E.P. and A.G. Lewis 1979 Ontogenetic migration and the distribution of Eucalanus bungii (Copepoda; Calanoida) in Brit- ish Columbia inlets. Canadian Journal of Zoology 57:2211-2222. Krom, M.D. and E.R. Sholkovitz 1978 On the association of iron and manganese with organic matter in anoxic marine pore waters. Geochimica et Cosmochimica Acta 42:607-611. Landry, M.R. 1977 A review of important concepts in the trophic organization of pelagic ecosystems. Helgoldnder wissenschaftliche Meeresuntersuchungen 30:8-17. LeBrasseur, R.J., W.E. Barraclough, O.D. Kennedy, and T.R. Parsons 1969 Production studies in the Strait of Georgia. Part III. Observations on the food of larval and juvenile fish in the Fraser River plume, Febru- ary to May, 1967. Journal of Experimental Marine Biology and Ecology 3:51-61. Levings, CD., R.E. Foreman, and V.J. Tunnicliffe 1983 Review of the benthos of the Strait of Georgia and contiguous fjords. Canadian Journal of Fish- eries and Aquatic Sciences 40:1120-1141. Lewis, M.R. and T. Piatt 1982 Scales of variability in estuarine ecosystems. In: Estuarine Comparisons: Proceedings of the Sixth Biennial International Research Conference. V.S. Kennedy, editor. Academic Press, New York, NY. pp. 3-20. Lieberman, S.H. 1979 Stability of copper complexes with seawater humic substances. Ph.D. Dissertation, Univer- sity of Washington, Seattle, WA. 228 pp. Livingstone, D. and T.C Royer 1980 Observed surface winds at Middleton Island, Gulf of Alaska and their influence on ocean cir- culation. Journal of Physical Oceanography 10:753-764. Macdonald, R.W., editor 1983 Proceedings of a workshop on the Kitimat marine environment. Canadian Technical Report of Hydrography and Ocean Sciences No. 18. Institute of Ocean Science, Sidney, B.C. 218 pp. Macdonald, R.W., W.J. Cretney, CS. Wong, and P. Erickson 1983 Chemical characteristics of water in the Kitimat fjord system. In: Proceedings of a Work- shop on the Kitimat Marine Environment. R.W. Macdonald, editor. Canadian Technical Report of Hydrography and Ocean Sciences No. 18, Institute of Ocean Science, Sidney, B.C. pp. 67-87. Mackiewicz, N.E., R.D. Powell, P.R. Carlson, and R.F. Molnia 1984 Interlaminated ice-proximal glacimarine sedi- ments in Muir Inlet, Alaska. Marine Geology 57:113-147. Mann, K.H. 1975 Relationship between morphometry and bio- logical functioning in three coastal inlets of Nova Scotia. In: Estuarine Research, Vol. 1. L.E. Cronin, editor. Academic Press, New York, NY. pp. 634-644. Silud Fjords and Coastal Regions 213 Mann, K.H. 1982 Ecology oj Coastal Wains: A Systems Approach. University of California Press, Berkeley, CA. 322 pp. Mantoura, R.F.C. and E.M.S. Woodward 1983 Conservative behaviour of riverine dissolved organic carbon in the Severn Estuary: chemical and geochemical implications. Geochimica el Cosmochimica Ada 47:1293- 1309. Mantoura, R.F.C, A. Dickson, and J. P. Riley 1978 The complexation of metals with humic mate- rials in natural waters. Estnarine and Coastal Marine Science 6:387-408. Matthews, J.B.L. and B.R. Heimdal 1980 Pelagic productivity and food chains in fjord systems. In: Fjord Oceanography. H.J. Freeland, D.M. Farmer and CD. Levings, editors. Plenum Press, New York, N. Y. pp. 377-398. Matthews, J.B.L., L. Hestad, andJ.L.W. Bakke 1978 Ecological studies in Korsfjorden, western Nor- way. The generations and stocks of Calanus hyperboreus and C. finmarchicus in 1971-1974. Oceanologica Acta 1:277-284. McAlister, W.B., M. Rattray, Jr., and CA. Barnes 1959 The dynamics of a fjord estuary, Silver Bay, Alaska. Technical Report 62, Department of Oceanography, University of Washington, Seattle, WA. 70 pp. Miller, C.B., D.W. Frost, H.P. Batchelder, M.J. Clemons, and R.E. Conway 1984 Life histories of large, grazing copepods in a subarctic ocean gyre: Neocalanus plumchrus, Neo- calanus cristatus and Eucalanus bungii in the northeast Pacific. Progress in Oceanography 13:201-243. Morris, A.W., R.F.C. Mantoura, A.J. Bale, and R.J.M. Howland 1978 Very low salinity regions of estuaries: impor- tant sites for chemical and biological reactions. Nature (London) 274:678-680. Muench, R.D. and D.T. Heggie 1978 Deep water exchange in Alaskan subarctic fjords. In: Estnarine Transport Processes. B. Kjerfve, editor. University of South Carolina Press. Columbia, SC pp. 239-267. Muench, R.D. and D.L. Nebert 1973 Physical oceanography. In: Environmental Stud- ies of Port Valdez. D.W. Hood, W.E. Shiels, and EJ. Kelley, editors. Occasional Publication No. 3, Institute of Marine Science, University of Alaska, Fairbanks, AK. pp. 103-149. Muench, R.D. and CM. Schmidt 1975 Variations in the hydrographic structure of Prince William Sound. Report R75-1, Institute of Marine Science, University of Alaska Sea Crant Report 75-1, University of Alaska, Fair- banks, AK. 135 pp. Naiman, R.J. and J.R. Sibert 1978 Transport of nutrients and carbon from the Nanaimo River to its estuary. Limnology and Oceanography 23:1183-1193. Nebert, D.L. 1972 A proposed circulation model for Endicott Arm, an Alaskan fjord. M.S. Thesis, University of Alaska, Fairbanks, AK. 90 pp. Nebert, D.L. 1982 The circulation of the Smeaton Bay and Boca de Quadra fjord systems. In: Marine Tailings Dis- posal. D.V. Ellis, editor. Ann Arbor Science Pub- lications, Ann Arbor, MI. pp. 291-310. Nebert, D.L. 1984 The physical oceanography of Boca de Quadra. Unpublished report, Institute of Marine Science, University of Alaska, Fair- banks, AK. 43 pp. Nebert, D.L. 1985 The physical oceanography of Smeaton Bay and Wilson Arm. Unpublished report, Institute of Marine Science, University of Alaska, Fairbanks, AK. 62 pp. Nebert, D.L. and D.C Burrell 1981 Marine environmental studies in Boca de Quadra and Smeaton Bay: physical oceanogra- phy 1980. Report R81-5, Institute of Marine Science, University of Alaska, Fairbanks, AK. 57 pp. Parsons, T.R. 1965 A general description of some factors gov- erning primary production in the Strait of Georgia, Hecate Strait and Queen Charlotte Sound, and the N.E. Pacific Ocean. Fisheries Research Board of Canada Manuscript Report Series (Oceanographic and Limnological) No. 193. 34 pp. Parsons, T.R., L.J. Albright, and J. Parslow 1980 Is the Strait of Georgia becoming more eutrophic? Canadian Journal of Fisheries and Aquatic Science 37:1043-1047. Parsons, T.R., R.J. LeBrasseur, and W.E. Barraclough 1970 Levels of production in the pelagic environ- ment of the Strait of Georgia, British Colum- bia: a review. Journal of the Fisheries Research Board of Canada 27:1251-1264. 214 Physicai Environment Parsons, T.R., K. Stephens, and R.J. LeBrasseur 1969 Production studies in the Strait of Georgia. Part I. Primary production under the Fraser River plume, February to May, 1967. Journal of Experimental Marine Biology and Ecology 3:27-38. Parsons, T.R., R.J. LeBrasseur, J.D. Fulton, and O.D. Kennedy 1969 Production studies in the Strait of Georgia. Part II. Secondary production under the Fraser River plume, February to May, 1967. Journal of Experimental Marine Biology and Ecology 3:39-50. Parsons, T.R., J. Stronach, G.A. Borstad, G. Louttit, and R.I. Perry 1981 Biological fronts in the Strait of Georgia, Brit- ish Columbia, and their relation to recent measurements of primary productivity. Marine Ecology — Progress Series 6:237-242. Parsons, T.R., H.M. Dovey, W.P. Cochlan, R.I. Perry, and P.B. Crean 1984 Frontal zone analysis at the mouth of a fjord — Jervis Inlet, British Columbia. Sarsia 69:133- 137. Parsons, T.R., R.I. Perry, E.D. Nutbrown, W. Hsieh, and CM. Lalli 1983 Frontal zone analysis at the mouth of Saanich Inlet, British Columbia, Canada. Marine Biology (Berlin) 73:1-5. Pearson, T.H. 1971 Studies on the ecology of the macrobenthic fauna of Lochs Linnhe and Eil, west coast of Scotland. II. Analysis of the macrobenthic fauna by comparison of feeding groups. Vie et Milieu Supplement No. 20. pp. 53-91. Pearson, T.H. 1980 Macrobenthos of fjords. In: Fjord Oceanography. H.J. Freeland, D.M. Farmer and CD. Levings, editors. Plenum Press, New York, NY. pp. 569-602. Pearson, T. H. In Fjord ecosystems. In: Proceedings of the Comite Press Antique Symposium, University of Alaska, Fair- banks, AK. Pickard, G.L. and B.R. Stanton 1980 Pacific fjords — a review of their water charac- teristics. In: Fjord Oceanography. H.J. Freeland, D.M. Farmer, and CD. Levings, editors. Plenum Press, New York, NY. pp. 1-51. Pingree, R.D., P.M. Holligan, and G.T. Mardell 1978 The effects of vertical stability on phytoplank- ton distributions in the summer on the North- west European Shelf. Deep-Sea Research 25: 1011-1028. Piatt, T. and R.J. Conover 1971 Variability and its effect on the 24h chlorophyll budget of a small marine basin. Marine Biology (Berlin) 10:52-65. Piatt, T., A. Prakash, and B. Irwin 1972 Phytoplankton nutrients and flushing of inlets on the coast of Nova Scotia. Naturaliste Canadien 99:253-261. Rattray, M. , Jr. 1977 Fjord and salt-wedge circulation. In: Estuaries, Geophysics and the Environment. National Acad- emy of Sciences, Washington, D.C pp. 36-45. Reeburgh, W.S., R.D. Muench, and R.T. Cooney 1976 Oceanographic conditions during 1973 in Rus- sell Fjord, Alaska. Estuarine and Coastal Marine Science 4:129-145. Roden, G.I. 1967 On river discharge into the northeastern Pacific Ocean and the Bering Sea. Journal of Geo- physical Research 72:5613-5629. Royer, T.C 1975 Seasonal variations of waters in the northern Gulf of Alaska. Deep-Sea Research 22:403-416. Royer, T.C. 1979 On the effect of precipitation and runoff on coastal circulation in the Gulf of Alaska./owraa/ of Physical Oceanography 9:555-563. Royer, T.C. 1982 Coastal fresh water discharge in the northeast Pacific. Journal of Geophysical Research 87C: 2017-2021. Royer, T.C 1983 Observations of the Alaska Coastal Current. In: Coastal Oceanography. H.G. Gade, A. Edwards and H. Svendsen, editors. Plenum Press, New York, NY. pp. 9-30. Sakshaug, E. and S. Myklestad 1973 Studies on the phytoplankton ecology of the Trondheimsfjord. III. Dynamics of phy- toplankton blooms in relation to environmen- tal factors, bioassay experiments and param- eters for the physiological state of the populations./owrwz/ of Experimental Marine Biol- ogy and Ecology 11:157-188. Scheltema, R.S. 1975 Relationship of larval dispersal, gene-flow and natural selection to geographic variation of benthic invertebrates in estuaries and along coastal regions. In: Estuarine Research, Vol. 1. L.E. Cronin, editor. Academic Press, New York, NY. pp. 372-391. Su lfd Fiords and Coastal Regions 215 Schlesinger, VV.H. andJ.M. Melack 1981 Transport of organic carbon in the world's rivers. Tellus 33:172-187. Schnitzer, M., and S.U. Khan 1972 Humic Substances in the Environment. Marcel Dek- ker, New York, NY. 143 pp. Seki, F. 1982 Organic Materials in Aquatic Ecosystems. CRC Press, Boca Raton, FL. 201 pp. Sholkovitz, E.R. 1978 The flocculation of dissolved Fe, Mn, Al, Cu, Ni, Co and Cd during estuarine mixing. Earth and Planetary Science Letters 41:77-86. Skolkovitz, E.R., E.A. Boyle, and N.B. Price 1978 The removal of dissolved humic acids and iron during estuarine mixing. Earth and Planetary Sci- ence Letters 40:130-136. Skreslet, S. 1981 Information and opinions on how freshwater outflow to the Norwegian Coastal Current influences biological production and recruit- ment to fish stocks in adjacent seas. In: The Nor- wegian Coastal Current: Proceedings of the Nor- wegian Coastal Current Symposium. R. Saetre and M. Mork, editors. University of Bergen, Bergen, Norway, pp. 712-748. Soldrzano, L. and B. Grantham 1975 Surface nutrients, chlorophyll a and phaeopig- ments in some Scottish sea lochs. Journal of Experimental Marine Biology and Ecology 20:63-76. Stigebrandt, A. 1981 A mechanism governing the estuarine cir- culation in deep, strongly stratified fjords. Estuarine, Coastal, and Shelf Scieru:e 13:197-211. Stockner, J.G., D.D. Cliff, and D.B. Buchanan 1977 Phytoplankton production and distribution in Howe Sound, British Columbia: a coastal marine embayment fjord under stress. Journal of the Fisheries Research Board of Canada 34:907-917. Stockner, J.G., D.D. Cliff, and K.R.S. Shortreed 1979 Phvtoplankton ecology of the Strait of Georgia, British Columbia.. Journal of the Fisheries Research Board of Canada 36:657-666. Strathmann, R.R. 1982 Selection for retention or export of larvae in estuaries. In: Estuarine Comparisons: Proceedings of the Sixth Biennial International Estuarine Research Conference. V.S. Kennedv, editor. Academic Press, New York, NY. pp. 521-536. Stucchi, D.J. 1980 The tidal jet in Rupert-Holbert inlet. In: Fjord Oceanography. H.J. Freeland, D.M. Farmer and CD. Levings, editors. Plenum Press, New York, NY. pp. 491-497. Stucchi, D. J. 1983 Shelf-fjord exchange on the west coast of Van- couver Island. In: Coastal Oceanography. H.G. Gade, A. Edwards, and H. Svendsen, editors. Plenum Press, New York, NY. pp. 439-450. Stucchi, D. and D.M. Farmer 1976 Deep-water exchange in Rupert-Holberg Inlet. Pacific Marine Science Report No. 76-10, Institute of Ocean Science, Sidney, B.C. 31 pp. Sugai, S.F. and D.C. Burrell 1984 Transport of dissolved organic carbon, nutrients, and trace metals from the Wilson and Blossom Rivers to Smeaton Bay, Southeast Alaska. Canadian Journal of Fisheries and Aquatic Sciences 41:180-190. Sulkin, S.D. and W. Van Henkelen 1982 Larval recruitment in the crab Callinectes sapidus Rathburn: an amendment to the con- cept of larval retention in estuaries. In: Estuarine Comparisons. V.S. Kennedy, editor. Academic Press, New York, NY. pp. 459-475. Svendsen, H. 1977 A study of the circulation in a sill fjord on the west coast of Norway. Marine Science Communica- tions 3:151-209. Svendsen, H. 1980 Exchange processes above sill level between fjords and coastal water. In: Fjord Oceanography. H.J. Freeland, D.M. Farmer, and CD. Levings, editors. Plenum Press, New York, NY. pp. 355-361. Svendsen, H. 1981 A study of circulation and exchange processes in the Fyfylkefjord. Report No. 55, Geophysical Institute, University of Bergen, Bergen, Nor- way. 70 pp. Syvitski, J. P.M. and G.E. Farrow 1983 Structures and processes in bayhead deltas: Knight and Bute Inlet, British Columbia. Sedi- mentary Geology 36:217-244. Syvitski, J.P.M., D.C. Burrell, andJ.M. Skei In press Fjords: Processes and Products. Springer-Verlag, New York, NY. Syvitski, J. P.M., K.W. Asprey, D.A. Clattenburg, and CD. Hodge 1985 The prodelta environment of a fjord: sus- pended particle dynamics. Sedimentology 32:83-107. 216 Physical Environment Taft, J.L., A.J. Elliot, and W.R. Taylor 1978 Box model analysis of Chesapeake Bay am- monium and nitrate fluxes. In: Estuarine Interac- tions: Proceedings of the Fourth International Estuarine Research Conference. M.L. Wiley, editor. Academic Press, New York, NY. pp. 115-130. Takahashi, M., D.L. Seibert, and W.H. Thomas 1977 Occasional blooms of phytoplankton during summer in Saanich Inlet, B.C., Canada. Deep- Sea Research 24:775-780. Tett, P. and A. Wallis 1978 The general annual cycle of chlorophyll stand- ing crop in Loch Creran. Journal of Ecology 66:227-239. Therriault,J.-C. andT. Piatt 1978 Spatial heterogeneity of phytoplankton bio- mass and related factors in the near-surface waters of an exposed coastal embayment. Lim- nology and Oceanography 23:888-899. Therriault, J.-C, R. de Ladurantaye, and R.G. Ingram 1980 Particulate matter exchange processes between the St. Lawrence estuary and the Saguenay Fjord. In: Fjord Oceanography. H.J. Freeland, D.M. Farmer, and CD. Levings, editors. Plenum Press, New York, NY. pp. 363-373. Therriault, J.-C, R. de Ladurantaye, and R.G. Ingram 1984 Particulate matter exchange across a fjord sill. Estuarine, Coastal, and Shelf Science 18:51-64. Therriault, J.-C, D.J. Lawrence, and T. Piatt 1978 Spatial variability of phytoplankton turnover in relation to physical processes in a coastal environment. Limnology and Oceanography 23:900-911. Tully, J.P. and F.G. Barber 1960 An estuarine analogy in the sub-arctic Pacific Ocean. Journal of the Fisheries Research Board of Canada 17:91-112. Tunnicliffe, V. 1981 High species diversity and abundance of the epibenthic community in an oxygen-deficient basin. Nature (London) 294:354-356. Tyler, M.A. and H.H. Seliger 1978 Annual subsurface transport of a red tide dino- flagellate to its bloom area: water circulation patterns and organism distributions in the Chesapeake Bay. Limnology and Oceanography 23:227-246. VTN Environmental Sciences, Inc. 1983 Integrative data analysis: coastal and marine biology program Quartz Hill molybdenum project, Southeast Alaska. Unpublished report prepared for U.S. Borax and Chemical Corp., Los Angeles, CA. 162 pp. VTN Environmental Sciences, Inc. 1984 Suspended sediment study of the Keta and Blossom Rivers — Quartz Hill molybdenum project, Southeast Alaska. Unpublished report prepared for U.S. Borax and Chemical Corpo- ration, Los Angeles, CA. 27 pp. Waldichuk, M. 1964 Daily and seasonal sea-level oscillations on the Pacific Coast of Canada. In: Studies in Oceanogra- phy. Geophysical Institute, University of Tokyo, Tokyo, pp. 181-201. Wassmann, P. 1983 Sedimentation of organic and inorganic partic- ulate material in Lindaspollene, a stratified, land-locked fjord in western Norway. Marine Ecology — Progress Series. 13:237-248. Wassmann, P. 1984 Sedimentation and benthic mineralization of organic detritus in a Norwegian fjord. Marine Biology (Berlin) 83:83-94. Wassmann, P. and A. Aadnesen 1984 Hydrography, nutrients, suspended organic matter, and primary production in a shallow fjord system on the west coast of Norway. Sarsia 69:139-153. Webb, K.L. and CF. D'Elia 1980 Nutrient and oxygen redistribution during a spring neap tidal cycle in a temperate estuary. Science 207:983-985. Winter, D.F., K. Banse, and G.C Anderson 1975 The dynamics of phytoplankton blooms in Puget Sound, a fjord in the northwestern United States. Marine Biology (Berlin) 29:139-176. Xiong, Q. and T.C Royer 1984 Coastal temperature and salinity in the north- ern Gulf of Alaska, 1970-1983 Jourra/ of Geophys- ical Research 89G8061-8068. Section 3 Biological Resources Microbiology 8 Ronald M. Atlas Department of Biology University of Louisville Louisville, Kentucky Robert P. Griffiths Department of Microbiology Oregon State University Corvallis, Oregon Abstract Microbial population levels in the Gulf of Alaska appear comparable to those in other regions of the Pacific Ocean. However, these levels are lower in surface waters in the Gulf of Alaska than they are in the Bering and Beaufort Seas. There are regional differences in species distribution within the Gulf as well as differences in the dominant species as compared with other marine ecosystems; pseudomonads do not dominate. Bacterial communities in the Gulf are taxonomically and physiologically diverse. Bacteria capable of growth at low nutrient concentrations are particularly versatile with respect to their tolerance of variations in environmental parameters and their use of diverse substrates as sources of nutrition. Pathogens have not been extensively studied; some microbial diseases of fish and shellfish have been reported, and some human pathogens are associated with crabs collected near areas of human habitation. The distribution of hydrocarbon utilizers correlates positively with areas of hydrocarbon accumulation. Exposure to hydrocar- bons affects microbial activities, with potential long-term impacts on ecological productivity. Detrital microorganisms are very important in food webs and contribute to overall productivity. Microbial populations, particularly important in carbon and nitrogen cycling in marine ecosystems, are similar to those reported for more temperate cli- mates. The highest rates of microbial productivity in the Gulf occur in areas directly influenced by river inputs and the transport of fine-grained sediments. Bacterial activities are closely tied to phytoplankton production. Distribution of Microbial Populations Traditionally, the distribution of bacteria in marine eco- systems has been determined by enumeration using viable plate count procedures with high nutrient media (ZoBell 1946). Such enumeration procedures were thought to give the highest counts and, therefore, to be representative of the microbial biomass in a given sample. However, marine microbiological studies in the last few decades have shown that the viable plate count is selective (Jannasch and Jones 1959) and only accounts for a fraction of the total microbial biomass that is revealed by the acridine orange direct count procedure or by a variety of biochemical methods (Atlas 1983). Thus, microbial ecologists now question the value of viable plate counts and rely more upon nonselective enu- meration procedures such as the biochemical quantifica- tion of microbial constituents and direct microscopic observations. These modern enumeration procedures, however, often leave unresolved questions, such as: 1) are the micro- organisms enumerated by such procedures living or dead, 2) are the microorganisms active or dormant, and 3) are they representative of a particular species? Different investiga- tors have used a variety of both traditional and modern enu- 221 222 Biological Resources meration methods in marine studies. This practice has severely limited the ability to make accurate comparisons between different regions of the oceans. Nevertheless, we can make some generalizations about the distribution of microorganisms in marine ecosystems. For example, microbial numbers are relatively high in near- shore, upwelling, and estuarine waters, but fall off to between 1 and l()0/ml in pelagic waters (ZoBell 1946; Wood 1965, 1967; and Atlas and Bartha 1981). Kriss (1963) estimated that seawater overlying continental shelf regions contains between 103 and 104 bacteria per milliliter. Relatively high numbers of microorganisms occur in the top few cen- timeters of most marine sediments (107 to 10H/g), but the numbers taper off in deeper sediment layers (Wood 1965, 1967; Atlas and Bartha 1981). In nearshore regions of the marine ecosphere there is a mixture of autochthonous (indigenous) and allochthonous (non-indigenous) microorganisms. Most bacteria in marine ecosystems are Gram-negative and motile; often greater than 95% of the bacteria isolated from seawater samples are Gram-negative motile rods (Wood 1965, 1967). There is a relatively high proportion of proteolytic bacteria in marine habitats compared with water or soil habitats (Atlas and Bartha 1981). While Pseudomonas or Vibrio species are often found to be the dominant genera in marine environments (ZoBell 1946; Colwell and Liston 1961; and Wood 1965, 1967), Flavobacterium species are also found in relatively high numbers (ZoBell 1946; Colwell and Morita 1972). For example, in Chesapeake Bay, Lovelace, Tubiash, and Colwell (1967) found 56% Vibrio species, 18% Pseudomonas species, and 6% Flavobacterium species, along with Spirillum, Achromobacter, Hyphymicrobium, Cytophaga, Microcylus, and actinomycetes. Some Gram-positive bacteria such as Bacillus are normally found in marine sediments (ZoBell 1946; Wood 1967). Enumeration of Microorganisms in the Gulf of Alaska Bacterial populations in the Gulf of Alaska have been enumerated through a variety of procedures (Atlas 1982), including: • using the direct count procedure with acridine orange staining (Daley and Hobbie 1975) for total counts • using several media and incubation conditions for enumeration of viable bacteria (such as marine agar 2216 at 5C for viable counts of heterotrophic bacteria) (ZoBell 1946) • using hydrocarbon-mineral salts media for determin- ing numbers of hydrocarbon-degrading micro- organisms (Atlas 1979). Population levels in the Gulf of Alaska (Atlas 1977, 1982; Kaneko, Hauxhurst, Krichevsky, and Atlas 1978) appear to be comparable to other regions of the Pacific Ocean (ZoBell 1946; Wood 1967). Numbers of viable heterotrophic bacteria are lower in the Gulf of Alaska surface waters than in th Bering and Beaufort Seas; total direct bacteria counts, how- ever, are not significantly different between these regions (Table 8-1) (Kaneko et al. 1978; Atlas 1982). This observation presents a paradox because the waters of more northern seas are subject to more severe environmental conditions and thus it might be expected that they would have lower bacterial numbers. The suggestion has been made that the presence of sea ice in circumpolar seas enables certain bac- teria to reach higher numbers or to survive longer than they would in more temperate waters (Atlas and Griffiths 1984). No such differences would be expected for sediments because they are subjected to relatively uniform environ- mental conditions. Indeed, both viable and total bacteria counts in Arctic and subarctic sediments are not signifi- cantly different (Table 8-1). No significant seasonal differences in either viable or direct bacteria counts have been found in water and sedi- ment samples from the Gulf of Alaska despite seasonal dif- ferences in surface water temperatures or microbial meta- bolic activity (Table 8-1) (Griffiths, Caldwell, and Morita 1982; Kaneko et al. 1978; Atlas 1982). Counts of hydrocar- bon-degrading microorganisms show that these bacteria constitute only a small proportion of the total bacterial com- munities that occur in the water and sediment of the Gulf of Alaska (Roubal and Atlas 1978). Total numbers of microorganisms are about an order of magnitude lower in the northern and central portions of lower Cook Inlet than elsewhere in the lower Cook Inlet region (Atlas, Venkatesan, Kaplan, Feely, Griffiths, and Mor- ita 1983). In both lower Cook Inlet and Shelikof Strait, the range of total numbers of microorganisms is similar, gener- ally with only one order of magnitude variation. Atlas et al. (1983) reported an association between the microbial popu- lation distribution and the sedimentation patterns for fine-grained particles in Cook Inlet and adjacent waters. Taxonomy of Microbial Populations in the Gulf of Alaska Investigators have performed taxonomic studies on Gulf of Alaska isolates that were randomly selected both from marine agar enumeration plates (copiotrophs) and from low-nutrient isolation media (oligotrophs) (Hauxhurst, Krichevsky, and Atlas 1980; Horowitz, Krichevsky, and Atlas 1983). The isolates have been extensively characterized using a large number of morphological, physiological, and nutritional tests; —300 phenotypic characteristics were determined for each strain (Kaneko, Krichevsky, and Atlas 1979; Hauxhurst et al. 1980). The data have been analyzed using numerical taxonomic procedures that included clus- ter analyses (Sneath and Sokal 1973). Clusters of strains with similarities greater than 75% were designated as taxonomic groupings (Liston, Wiebe, and Colwell 1963). Hauxhurst et al. (1980) described the Gulf of Alaska's major taxonomic groups for both water and sediment samples (Table 8-2). The distribution of bacterial species appears to be quite different between the northeast and the northwest Gulf of Alaska. Distribution differences also occur between these Gulf of Alaska regions and elsewhere in the Pacific Ocean, and in other Alaskan continental shelf regions (Hauxhurst et al. 1980). Many new 'species' or genera probably exist both within the Gulf of Alaska and within other northern marine ecosystems. There appears to be a spatial discontinuity in the dis- tribution of Microcyclus species in Alaskan coastal waters. Mk kobioiocy 223 Table 8-1. Comparison of numbers of microorganisms found in Arctic and subarctic marine waters (numbers/ml) and sediments (numbers/g). Location TlME Dirk i Count Viable ( ,< )i \ i Hydro* akbon L.' I II.IZI.KS Beaufort Sea Beaufort Sea Beaufort Sea Beaufort Sea Summer 1975 Winter 1976 Summer 1976 Summer 1978 Sediment 6.2± 1.1x10" 3.7±1.0*108 2.1±0.9xlO'J 1.6±0.8xl0» 2.0±l.lxl06 2.5±1.9xl05 8.3±6.7xl06 5.3±3.2xlOu 2.5 ± 2.2 x 04 Norton Sound North Bering Sea Mid-Bering Sea South Bering Sea South Bering Sea Summer 1979 Spring 1979 Spring 1980 Summer 1980 Winter 1981 2.1±1.9xl0K 1.7±1.4xl09 2.3±1.4xl09 1.9±2.5xl09 3.0±2.3xl09 9.2 ± 9.6 x '3 2.6±3.3xi^ 3.0±1.8> TO2 3.0± 1.0x10s 2.5±1.7xlOs NW Gulf of Alaska NE Gulf of Alaska Cook Inlet Cook Inlet Cook Inlet Cook Inlet Cook Inlet Fall 1975 Spring 1976 Fall 1976 Spring 1977 Fall 1977 Spring 1978 Spring 1979 3.0± 1.6x10° 1.5±1.9*109 7.7±3.8xl08 5.9 ± 2.2xl08 4.9±1.5xl08 2.6±1.6xl09 6.3±6.2xlOr> 1.0±2.3xl06 2.2±2.1xl0h 4.2±5.7xl06 4.4±5.6xl06 24±2.7xl06 3.3±2.3xl06 8.9±3.1xl02 3.6±3.5xl02 2.9±7.1xl03 6.7±9.1xl0:* 8.4 ± 8.3 x 10s 5.6±4.9xlOs 6.3 ±5.8x10' Water Beaufort Sea Beaufort Sea Beaufort Sea Beaufort Sea Summer 1975 Winter 1976 Summer 1976 Summer 1978 8.2±7.2xl05 1.8± 1.3xl05 5.2±3.9xl05 6.7±4.9xl05 9.6±4.8xl03 6.1±7.0xl02 5.0±3.2xl04 3.5±2.9xl04 2.6±1.3xl0' Norton Sound North Bering Sea Mid-Bering Sea South Bering Sea South Bering Sea Summer 1979 Spring 1979 Spring 1980 Summer 1980 Winter 1981 2.8±1.5xl05 1.4±0.9xl05 2.0±1.7xl05 2.6±1.5xl05 9.3±7.2xl05 l.l±1.2xl0' l.l±5.7xl0° 1.5±1.0xl0° 2.2±6.2xl0° NW Gulf of Alaska NE Gulf of Alaska Cook Inlet Cook Inlet Cook Inlet Cook Inlet Cook Inlet Fall 1975 Spring 1976 Fall 1976 Spring 1977 Fall 1977 Spring 1978 Spring 1979 3.0±1.0xl05 1.4±0.9xl05 3.2±2.9xl05 2.5±0.9xl04 5.8±2.4xl04 8.1±3.1xl04 4.2±2.2xl05 1.0±0.7xl02 l.l±0.8xl02 1.6±1.5xl02 3.9±4.9xl02 1.7±1.8xl02 1.0±1.6xl02 3.7±3.0xl02 1.8±4.7xl0° 1.3± 1.7x10° 6.4±1.5xl01 3.7±1.5xl0' 3.7±4.5xl0' 4.8±5.4xl0' 2.6±3.4xl0' Although common to the contiguous regions of the north- west Gulf of Alaska, Bering Sea, and Arctic Ocean, this genus is not common to the northeast Gulf of Alaska. Micro- cyclus species were identified near the Aleutian Islands (Hauxhurst et al. 1980) and have also been found in the Beau- fort Sea (Kaneko et al. 1979) and the Bering Sea (Atlas 1982). In the northeast Gulf of Alaska, Moraxella and Acinetobacter were the most frequently detected bacterial genera. However, the dominant Moraxella and Acinetobacter populations found in the northeast Gulf of Alaska were not found in samples from the northwest Gulf of Alaska (Haux- hurst et al. 1980). Although Acinetobacter and Moraxella strains are readily isolated from marine habitats, thev had not been found as dominant marine bacterial populations (Wood 1967). Vibrio and Beneckea are commonly found in marine eco- systems (Kaneko and Colwell 1973, 1974), and these genera were found in the Gulf as well as in the Beaufort Sea (Kan- eko et al. 1979). The repeated failure to find dominant popu- lations of Pseudomonas in the Gulf (Hauxhurst et al. 1980) is not likely to be an artifact of isolation procedures because, using the same basic medium marine agar 2216, ZoBell and colleagues (ZoBell and Upham 1944; ZoBell 1946) isolated numerous Pseudomonas species in the Pacific between Hawaii and California. Simidu, Kaneko, and Taga (1977) also isolated Pseudomonas species from the Pacific Ocean. Characteristics of Gulf of Alaska Bacterial Populations Gram-negative rods were predominant in all the water samples collected in the Gulf of Alaska (Hauxhurst et al. 1980; Hauxhurst, Kaneko, and Atlas 1981; and Horowitz et al. 1983). Approximately one-half of the bacterial populations were pigmented (predominantly with yellow, orange, and brown pigments) although the incidence of pigmented bac- teria in the northwest Gulf of Alaska was somewhat lower than in the northeast Gulf (Hauxhurst et al. 1980; 1981). The high incidence of pigmented bacteria is similar to that 224 Biological Resources Table 8-2. Descriptions of taxonomic groups of bacteria isolated from the Gulf of Alaska. Nor 1 1 ii \m (In 1 ok Alaska Isolates 1 . Gram-negative, non-motile rods-coccobacilli often occurring as pairs. 1 lie morphological and metabolic features of the organisms closelv resembled those of the Acinetobacler-Moraxella group. '_'. Gram-negative, motile, oxidase-positive, fermentative, curved or straight tods. Members of these clusters resembled strains classified in the genera Aeromonas. Beneckea, and Vibrio. '.\. Gram-negative, non-motile rods producing yellow, orange, or brown pigments. Bacteria with these characteristics are included in the genus Flavohacterium. 4. Gram-negative, non-motile, non-fermentative, oxidase-positive, catalase-negative rods which are not actively proteolytic in gelatin media. These strains resembled non-motile strains of Alcaligenes. 5. Gram-positive, motile rods producing pink colonies and spherical bodies in older cultures. The morphogenesis of these strains is representative of coryneform bacteria (e.g., Arthrobacter). 6. Gram-positive-Gram- variable, motile, large rods forming endospores and growing aerobicallv. The strains in this cluster t learly belong in the genus Bacillus. 1 . In addition to the organisms that formed defined major clusters, several minor clusters showed characteristics of the genera Flavohacterium (Gram-negative, motile rods producing yellow pigments, Pseudomonas (Gram-negative, motile rods growing only oxidatively), and Vibrio (Gram-negative rods generally with a curved axis). Northwest Gulf of Alaska Isolates 1. Gram-negative, oxidase-positive, non-pigmented, fermentative, motile rods. These organisms were similar to Beneckea species. 2. Gram-negative, oxidase-positive, non-pigmented, variably fermentative, motile, curved or straight rods. The characteristics of these organisms closely resembled those of Vibrio or Beneckea species. 3. Gram-negative, facultatively anaerobic, straight rods producing non- diffusible yellow pigments, presumably classified in the genus Flavohacterium. 4. Gram-negative, yellow-pigmented, non-motile rods forming partial rings. These organisms were morphologically similar to members of the genus Microcyclus. 5. Gram-negative, oxidase-positive rods producing violet pigments characteristic of the genus Chromobacterium. 6. Gram-negative, straight or curved rods that are catalase-negative. These strains have not been identified. 7. Gram-negative, non-pigmented, pleomorphic rods exhibiting bipolar inclusions. These bacteria have not been identified. 8. In addition to the organisms that were recovered in defined clusters, several individual organisms showed characteristics of coryneform bacteria (large rods forming spherical bodies in older cultures) and several others were Gram-positive cocci which exhibited characteristics of the genus Micrococcus (Gram-positive cocci producing pigments and occurring singly or in pairs). found in other Alaskan continental shelf regions (Kaneko et al. 1979), but is even higher than that reported for some temperate marine waters (Lovelace et al. 1967). Slightly less than half of the Gulf of Alaska bacterial iso- lates were motile; higher percentages of motile bacteria were found in water samples (49%) than in sediment sam- ples (38%). The majority of the bacterial populations grew at temperatures of 5 to 20C, but true psychrophiles, incapa- ble of growth at 20C, were found in only two-thirds of the samples. The majority of isolates at most stations required NaCl for growth. A higher incidence of pleomorphism was found among isolates from low-nutrient media (33%) than for strains iso- lated from high-nutrient media (8%) (Horowitz et al. 1983). Pleomorphism has been associated with oligotrophic bac- teria; the increased surface area appears to be important because it permits bacteria to use nutrients at very low con- centrations (Moaledi 1978; Poindexter 1979, 1981a, 1981b). Physiogical Tolerances Investigators have developed physiological tolerance indices so they could describe how isolates from microbial communities grow under environmental conditions that differ from the conditions that existed at the time of isola- tion. These indices indicate the abilities of bacterial popula- tions to tolerate both natural ecological variability and eco- logic disturbances (Hauxhurst etal. 1981). Different physiological tolerance indices are used to describe the abil- ities to grow over ranges of temperature (PT), pH (PH), and salinity (Ps) (Table 8-3) (Hauxhurst et al. 1981). There was a significant difference in Ps values for communities in sur- Table 8-3. Summary of physiological tolerance indices, nutrient utilization indices, and taxonomic diversities showing mean values. Intertidal Offshore West East Gulf Gulf of Cook of Beaufort of of KODIAK Inlet KODIAK Sea Alaska Alaska Island Island Water PT 0.82 0.78 0.72 0.78 0.80 0.60 Ph 0.58 0.55 0.35 0.57 0.62 0.62 Ps 0.58 0.41 0.11 0.57 0.61 0.26 Nr 0.85 0.76 0.63 0.76 0.82 0.55 Na 0.41 0.32 0.49 0.28 0.27 0.29 Nr, 0.61 0.51 0.45 0.46 0.59 0.37 N„ 0.61 0.62 0.70 0.69 0.50 0.32 Nh 0.06 0.04 0.14 0.00 0.05 0.00 NT 0.58 0.51 0.53 0.50 0.52 0.31 H' 3.0 3.0 2.9 2.9 3.0 2.6 J' 0.64 0.70 0.75 0.67 0.71 0.68 Sediment PT 0.79 0.69 0.59 0.71 0.72 0.55 Ph 0.50 0.55 0.52 0.51 0.59 0.72 PS 0.55 0.28 0. 1 7 0.18 0.41 0.35 Nr 0.97 0.87 0.79 0.86 0.90 0.67 N, 0.54 0.46 0.43 0.35 0.55 0.56 Nrn 0.64 0.57 0.55 0.44 0.68 0.69 N,n 0.70 0.74 0.67 0.78 0.74 0.40 Nh 0.00 0. 1 3 0.10 0.12 0.14 0.00 NT 0.65 0.61 0.57 0.55 0.67 0.46 H' 3.4 3.8 3.6 3.6 4.0 4.0 J' 0.74 0.84 0.84 0.84 0.85 0.86 PT = physiological tolerance index for temperature. PH = physiological tolerance index for pH. Ps = physiological tolerance index for salinity. Nc = nutritional utilization index for carbohydrates. Na = nutritional utilization index for alcohols. Nca = nutritional utilization index for carboxylic acids. Naa = nutritional utilization index for amino acids. N'h = nutritional utilization index for hydrocarbons. NT = nutritional utilization for all substrates. H' = Shannon diversity index. J' ™ equitabilitv index. Microbiology 225 face waters east and west of Kodiak Island; the mean Ps for western stations was 0.11, whereas the mean Ps for eastern stations was 0.61. In most cases, the temperature tolerance index (P, ) was greater than the indices for either the pH range or the NaCl concentration. This indicates that the majority of communities sampled are more tolerant to changes in temperature than they are to changes in either pH or salinity, at least for the ranges that were tested. The high physiological tolerance indices for Gulf of Alaska bacterial communities are somewhat surprising con- sidering that relatively low annual variations in tem- perature, salinity, and pH occur in these subarctic marine ecosystems. Most populations were quite tolerant of fluctua- tions in temperature, salinity, and pH, even for values that went beyond the limits to which they are ever naturally exposed. There are lower salinity tolerance indices for the western Gulf of Alaska than for Cook Inlet and the eastern Gulf. These lower indices correlate with areas where fresh- water input is expected; little runoff should occur from the Aleutian Islands, while east of Kodiak Island there are major river sources of freshwater. The salinity tolerance indices also indicate that intertidal communities are more tolerant of variations in salinity than offshore communities. This higher tolerance is adaptive, since the nearshore communities experience greater sali- nitv fluctuations than the offshore communities. Extensive mixing in the water column, suggested by temperature and salinity (density) measurements taken at the time of sam- pling, may account for a lack of statistically significant dif- ferences between the water and the sediment communities as far as physiological tolerance indices are concerned. The physiological tolerance indices showed significant differences for temperature, pH, and salinity between bac- teria isolated on high- and on low-nutrient media (Table 8-4) (Horowitz et al. 1983). Although one might postulate that bacteria isolated on low-nutrient media would be able to giow only under greatly restricted conditions, the bac- teria isolated on low-nutrient media were actually more tol- erant to variations in salinity and pH. They were also less fastidious from a nutrition standpoint than bacterial popu- lations isolated on rich media. The high physiological toler- ance indices for the Gulf isolates contrast markedly with those indices calculated for salinity and temperature using the data of Mallory, Austin, and Colwell (1977) (P , = 0.44 and Ps = 0.20 for Chesapeake Bay isolates). In the Gulf, it is obviously advantageous for indigenous bacteria to be ver- satile rather than specialized. Nutritional Versatility A nutritional versatility index (NT) was developed by Hauxhurst et al. (1981) to describe the nutritional capabilities of the indigenous microbial populations. This index, which is essentially synonymous with the average carbonaceous compound index (UAI) developed independently by Mar- tin and Bianchi (1980), is based upon first determining the numbers of different substrates that can be used as growth substrates by members of the microbial community, and then calculating the percentage of the substrates that can be used bv one or more representative isolates. Average UAI Table 8-4. Comparison of physiological tolerance indices, nutrient utilization indices, and taxonomic diversities for bacterial populations isolated on high- and low-nutrient media. Water Low Mr i rum Hk.ii Nt'i kii-m Sedimen I Low Nutrient Hk.h Ni irun i 1', 0.81 11.81) 0.80 0.69 PH 0.80 0.60 0.80 0.61 Ps 0.81 II i,ii 0.86 0.20 N, 0.38 0.37 0.24 0.19 Na 0.59 0.33 0.43 0.20 Nca 0.71 0.36 0.68 0.22 Naa 0.72 0.46 0.59 0.32 Nh 0.50 0.17 0.35 II. 0H H' I I P, = physiological tolerance index for temperature. PH " physiological tolerance index forpH. 1\ = physiological tolerance index for salinity. N( = nutritional utilization index for carbohydrates. Na = nutritional utilization index for alcohols. Nca = nutritional utilization index for carboxylic acids. Naa = nutritional utilization index for amino acids. Nh = nutritional utilization index for hydrocarbons. H' = Shannon diversity index. values for oligotrophic Mediterranean waters were found to be approximately 40% (NT = 0.40) with increases in UAI values up to 52 to 57% during peak phytoplankton bloom. This indicates that higher UAI values occurred during peri- ods of organic enrichment than under oligotrophic condi- tions. The mean Nr value of 0.53 for offshore Gulf of Alaska waters is somewhat higher than the UAI of 0.40 reported for oligotrophic Mediterranean waters. Direct comparison, however, is not possible in an absolute sense because differ- ent substrates were used for the calculations. Carbohydrates and amino acids generally had the high- est utilization indices (Table 8-3) (Hauxhurst et al. 1981). In the Gulf, saccharolytic bacterial populations appear to occur as frequently as proteolytic populations. There are two other noteworthy similarities that occur in the Gulf as well: 1) similar utilization indices for amino acids and carbo- hydrates, and 2) similar proportions of bacterial popula- tions that exhibit extracellular proteolytic and saccharolytic activities. In other regions of the Pacific Ocean, proteolvtic capacities have been found to far exceed saccharolytic activities for bacterial populations (ZoBell 1946). The nutri- tional utilization indices presumably reflect patterns of sub- strate use within the natural habitats of these communities. This reflection suggests that the bacterial communities may be deriving their energy from phytoplankton-produced nutrients that are rich in carbohvdrates. Although high-nutrient media have been used exten- sively in marine microbiology — ZoBell and others have found that a nutrient-rich medium supports the growth of higher numbers of marine microorganisms than media of other composition (ZoBell 1946; Carlucci 1974) — the recog- nition that most true marine bacteria grow in a nutrient-deprived environment has raised questions as to whether the use of low-nutrient media would be more appropriate (Jannasch 1967; Carlucci 1974; Carlucci and 226 Biological Resources Shimp 1974). High nutrient concentrations inhibit the growth of some marine bacteria; such bacteria grow best at low nutrient concentrations (Torella and Morita 1981). The characteristics of bacteria that were isolated on either low- or high-nutrient media differ significantly, sug- gesting that the bacteria isolated on the different media rep- resent bacterial populations occupying different ecological niches within their environment. In addition, isolates from low-nutrient media were nutritionally far more versatile than those isolated on high-nutrient media (Horowitz et al. 1983) (Table 8-4). Isolates from low-nutrient media could utilize two to three times more alcohol, carboxylic acid, amino acid, and hydrocarbon substrates than the isolates obtained from high-nutrient media. It is possible that in natural marine ecosystems some bacteria are associated with nutrient-rich particles such as detritus — including dead organisms and excretions — while other bacteria grow under conditions of near starvation on minimal concentra- tions of dissolved organic carbon (Morita 1982). Comparing these results to those obtained by Mallory et al. (1977), it appears that for comparable tests, a higher pro- portion of the Alaskan isolates were euryheterotrophic, whereas the Chesapeake Bay isolates were more restricted in the substrates they used. For example, the nutritional uti- lization indices for the Chesapeake Bay isolates — calculated based on the data of Mallory et al. (1977)— are Nc = 0.40, Na = 0.20, Naa = 0.10, and Nca = 0.10, which, with the exception of carbohydrates, are significantly lower than the compara- ble indices for the Alaskan Cook Inlet isolates that were obtained on low-nutrient media (Horowitz et al. 1983). Diversity of Gulf of Alaska Bacterial Communities A diversity index reflects both the number of different species and their relative abundances (distribution) within a given community, and hence the 'status' of the community. However, a diversity index does not define the specific fac- tors responsible for establishing levels of informational het- erogeneity (Atlas 1984a). Various diversity indices have been used to assess environmental stress caused by pollution (Patrick, Hohn, and Wallace 1954; Patrick 1963; Pielou 1975; and Cairns 1979). The Shannon index (H') accounts for both the numbers of different species and their relative abun- dances within a community. The index is calculated as H' = - ZPilogPi, where Pi = ni/N = importance probability for each species, ni = importance value for each species, and N = total of importance values. The equitability index (J') describes the evenness of species distribution within the community and is calculated as J' = H'/Hmax, where Hmax is the theoretical maximum Shannon index for a community that contains a specified number of species. The Shannon diversity indices for Gulf of Alaska bac- terial communities show a high state of diversity (Hauxhurst et al. 1981). These findings are comparable to those reported by Martin and Bianchi (1980) for oligotrophic marine waters of the French Mediterranean region. The taxonomic diver- sity indices for the Gulf of Alaska bacterial communities were somewhat higher for the water column and were sim- ilar for sediments when compared with those indices pre- viously calculated for Arctic marine bacterial communities (Kaneko, Atlas, and Krichevsky 1977; Hauxhurst et al. 1981; and Atlas, in press). Although seasonal differences in tax- onomic diversity were found in Arctic waters, no significant seasonal differences in taxonomic diversity indices were found for bacterial communities in those subarctic Gulf of Alaska waters sampled in March and October. Unlike the Beaufort Sea, where an inverse relationship between popu- lation size and taxonomic diversity was found (Kaneko et al. 1977), no significant correlation was found between popula- tion size and diversity for Gulf of Alaska bacterial commu- nities (Hauxhurst^ al. 1981). The bacterial populations isolated on nutrient-rich media had higher diversities than bacteria isolated on low-nutrient media (Table 8-4) (Horowitz et al. 1983). The average Shannon diversity index for all isolates from high- nutrient media was 5.6, compared with an index of 3.1 for isolates from low-nutrient media. The Shannon diversity indices for isolates from sediment obtained on high- nutrient media were higher than indices for comparable isolates taken from water. There was no significant dif- ference in diversity indices between sediment and water iso- lates obtained on low-nutrient media. Pathogenic Microorganisms in the Gulf of Alaska Fish Diseases Most of the data on fish diseases in the Gulf of Alaska relate to the freshwater environments where salmonids are reared and released (see review by Dieterich 1981). For fish diseases in marine systems, Grischkowsky and Amend (1976) reported infectious hematopoietic necrosis virus in Alaskan sockeye salmon; the virus was isolated from moribund juve- niles at Kitoi Bay and from adult spawning stock throughout Bristol Bay, Kodiak Island, Cook Inlet, and the southeast Gulf of Alaska areas. McCain, Gronlund, Myers, and Wellings (1979) and McCain, Hodgins, Sparks, and Gronlund (1981) found that Gulf of Alaska flatfish show no lymphocystis disease, and although lymphocystis was not observed in the yellowfin sole {Limanda aspera) of the Gulf of Alaska, it was found in sole collected in the Bering Sea. In contrast to the absence of lymphocystis, Levings (1967) reported that 10% of the rock sole (Lepidopsetta bilineata) collected in the Western Gulf of Alaska had epidermal papillomas, which in some cases cov- ered up to 50% of the body. Since such tumors were rarely detected in specimens from British Columbia, Levings pro- posed that differences in growth rates between fish in these regions might reflect differences in the frequency with which certain diseases occur in the two populations. Stich, Acton, Oishi, Yamazaki, Harada, and Moser (1977) conclude that lymphocystis and papillomatosis are mutually exclusive; even in the Bering Sea, where both diseases occur, individual flatfish are never afflicted with both of these dis- eases. Based upon the distributions of lymphocystis and papillomatosis, Stich, Acton, Dunn, Oishi, Yamazaki, Harada, Peters, and Peters (1977) hypothesized that the lym- Microbiology 227 phocystis virus and the 'papilloma virus' are related. They further hypothesized that lvmphocystis disease results when a complete infectious-replication cycle occurs, whereas papillomatosis occurs when a complete infection is aborted. Crab Diseases The commercially important Tanner crab (Chionoecetes bairdi) is susceptible to fungal infection by Trichomaris invad- ens which results in a disease called black mat syndrome (BMS). Sparks and Hibbits (1979) have shown that T. invadens can be found in most organs and tissues of infected Tanner crabs. Sparks (1982) has suggested that this disease could prove fatal to the infected crab, but before death occurs, it undoubtedly affects breeding and reproduction. A survey of natural Gulf of Alaska Tanner crab populations indicated that as many as 94.7% of the barren females had BMS (Hicks 1982), suggesting that T. invadens infections have a signifi- cant detrimental impact on reproductive success. Females showed the highest incidence of BMS with as much as 50% of the population infected in some areas. Black mat syn- drome was more prevalent in offshore populations than in nearshore populations. The incidence of BMS shows large seasonal variations; Tanner crabs southwest of Kodiak Island had a 29% incidence of BMS one year and 2% inci- dence the next year (Hicks 1982). Although it is clear that BMS is an important factor controlling Tanner crab popula- tions, we do not know enough about the conditions that enhance the rate of infection to offer solutions for reducing the incidence of this disease (Sparks 1982). Potential Human Pathogens Associated with Edible Crabs Pennington and Cronholm (1977) detected bacteria that are known human pathogens in crabs collected in the vicinity of Kodiak Island. They suggested that inadequately treated sewage was the source of this contamination. Faghri, Pennington, Cronholm, and Atlas (1984) examined the interaction between pathogenic bacteria and crabs from the Gulf of Alaska in greater detail. Their evidence indicates that certain bacteria from foreign contamination sources such as sewage can associate with crab tissue and survive in the marine environment for prolonged periods. Crabs obtained from near Kodiak Island contained bacteria that were identified as potential human pathogens. The isolates contained many taxa such as Klebsiella and Citrobacter that are normally associated with domestic sewage. These iso- lates were most frequently found in association with gill tissue, but in some cases bacteria were isolated from muscle tissue as well. Yersinia enterocolytica, a human pathogen transmitted via the gastrointestinal tract and associated with several recent outbreaks of food poisoning, was among the isolates obtained from crabs collected near Kodiak Island; tests with laboratory mice confirmed the pathogenicity of the Y. entero- colytica and also of the Klebsiella pneumoniae isolates (Faghri et al. 1984). Crabs from the southern Bering Sea and those collected in the Gulf of Alaska away from Kodiak Island did not contain bacterial populations indicative of sewage contamination. A standard indicator organism, Escherichia coli, was absent from crabs collected near Kodiak Island, but other bacteria associated with sewage were present. Previous studies have shown that standard coliform counts are inadequate as indi- cators either of fecal contamination of marine ecosystems, or of the safety of shellfish collected from areas impacted by sewage effluents. This is because E. coli is rapidly eliminated from seawater, whereas other bacteria in sewage effluents, including human pathogens, survive longer (Carlucci and Pramer 1959; Dutka 1973; and Rhodes, Anderson, and Kator 1983). Microcosm studies by Faghri et al. (1984) confirmed the rapid disappearance of E. coli from seawater at low tem- peratures and indicated that E. coli survival is not enhanced by association with crabs. Other bacteria such as Klebsiella, however, showed prolonged survival when in association with crab tissues. In addition to examining the potential for the association of sewage bacteria with crabs, Faghri et al. (1984) examined the possibility that indigenous marine bacteria that may be human pathogens could accumulate in crab tissue. Several investigators have found Vibrio species associated with tissue in blue crabs collected in temperate waters (Colwell, Wicks, and Tubiash 1975; Sizemore, Colwell, Tubiash, and Lovelace 1975; Tubiash, Sizemore, and Colwell 1975; and Davis and Sizemore 1982). Recent studies have shown that V. cholerae occurs naturally in temperate estuaries (Kaper, Lockman, Colwell, and Joseph 1979) and that cases of cholera in the Gulf Coast region of the United States have resulted from eating contaminated shellfish, including inadequately cooked crab meat (Blake, Weaver, and Hollis 1980). While it has been suggested that V. cholerae is a ubiquitous inhabitant of estuarine ecosystems (Kaper et al. 1979), this organism was not found in association with the Alaskan crabs (Faghri et al. 1984). Vibrio vulnificus, reported in association with eels and shellfish by Oliver, Warner, and Cleland (1982) and by Tison, Nishibuchi, Greenwood, and Seidler (1982), was found in the gill tissue of crabs collected off the Oregon/ Washington coast. It was not found, however, in the tissues of crabs collected in Alaskan continental shelf regions (Faghri et al. 1984). Similarly V. parahaemolyticus was isolated from Dungeness crabs collected off the mouth of the Colum- bia River, but not from Alaskan crabs (Faghri et al. 1984). Vibrio parahaemolyticus, a human pathogen, has been found in association with crabs and other shellfish (Fishbein, Mehlman, and Pitcher 1970; Bartley and Slanetz 1981). In temperate estuaries, V. parahaemolyticus undergoes an annual cycle during which it becomes associated with the chitin exoskeletons of invertebrates (Kaneko and Colwell 1973, 1975a). It is apparently restricted to temperate waters that reach high enough temperatures for it to complete its annual cycle (Kaneko and Colwell 1975b, 1978). Previous sur- veys have failed to detect V. parahaemolyticus north of Petersburg in southeastern Alaska, but the closely related species, V. alginolyticus, has been isolated throughout the Gulf of Alaska (Baross and Liston 1970; Vasconcelos, Stang, and Laidlaw 1975). Thus, although Vibrio species are among the major bacterial species occurring in Alaskan waters, those of concern with respect to human health appear to be absent in cold marine waters. 228 Biological Resources Staphylococcus and Micrococcus species were frequently iso- lated from Alaskan crab tissues (Faghri el al. 1984); these Gram-positive cocci are much more abundant in crab tissue than the\ are in the surrounding water and sediment (Haux- hurst et al. 1980). Recent reports, however, have indicated that Gram-positive cocci are normally found in marine hab- itats (Gunn, Singleton, Peele, and Colwell 1982; Gunn and Colwell 1983). All the Staphylococcus isolates from crabs exam- ined bv Faghri et al. (1984) were coagulase-negative S. epider- midis and S. hominis; these species have also been isolated from other marine ecosystems (Gunn and Colwell 1983). Some coagulase-negative Staphylococcus species are human pathogens (Kloos 1982), and the in vivo pathogenicity tests showed that the crab isolates were pathogenic for mice (Faghri et al. 1984). Besides examining field samples for contamination with human pathogen bacteria, Faghri et al. (1984) conducted microcosm studies to determine which, if any, bacteria could survive in seawater and become associated with crab tissues. An important question is whether the bacteria asso- ciated with crabs contaminate the edible muscle tissues. Scanning electron microscope observations and viable enu- meration procedures indicate that most bacteria are associ- ated with surface tissue of the gills and on the shell of crabs collected in the Gulf of Alaska. For example, Dungeness crabs had a diverse array of bacteria associated with gill tissue, and Alaskan king crabs collected near Kodiak Island showed higher numbers of viable bacteria on their gill tissue than crabs collected away from this populated area. As the study by Faghri et al. (1984) showed, hemolymph and muscle tissues of Alaskan crabs normally have low bac- terial populations. However, after death, high numbers of bacteria were found in hemolymph and muscle tissues; the muscle tissues of crabs that are either stressed by oxygen depletion or are injured and die within holding tanks can rapidly become contaminated with bacteria that include human pathogens. As long as the crab is healthy, the bac- teria appear to be restricted to the shell and gill tissues. How- ever, if the crab is injured, becomes weakened, or dies, bac- terial contaminants on the surface rapidly penetrate the hemolymph, and human pathogens can enter the muscle tissues. Microbial Processes Carbon Cycling In the classical scheme of large-scale marine biological processes, the major role of bacteria was thought to be that of mineralizer. Even though the role of the bacteria in the detrital food chain was known, it was thought to be of little importance to the total biological productivity of marine systems. By the early 1970s, however, enough radiotracer studies had been conducted to challenge many of the earlier concepts (Fenchel 1970; Mann 1972; and Fenchel and J0rgensen 1977). About the same time, Wetzel, Rich, Miller, and Allen (1972) redefined the working definition of the term detritus as "nonpredatory losses of organic carbon from any trophic level (includes egestion, excretion, and secretion) or input from sources external to the ecosystem that enter and cycle in the system (allochthonous organic carbon)." This relatively liberal interpretation of what con- stitutes detritus includes such components as dissolved organic compounds that were normally not categorized in this way (Fenchel and J0rgensen 1977). In light of both the above definition and observations that were being made using increasingly sensitive and sophisticated techniques, it was rapidly becoming evident that the relative importance of marine bacteria in the detrital food chain needed reevaluation. Pomeroy (1974) pointed out that bacteria had several roles to play in the detrital food chain: (1) converting dissolved organic carbon into bacterial biomass that could be used directly by higher trophic levels; (2) degrading relatively recalcitrant organic polymers that would not normally become available as a food source; and (3) colonizing both organic and inorganic particles, thus increasing the food value of these particles. Considering all these functions and using Wetzel's defini- tion of detritus, Sibert and Naiman (1980) concluded that ecosystems derive their total productivity from two sources: photosynthesis and microbial processing of non-grazed plant material. Although it is now generally acknowledged that the detrital food chain plays an important, if not major, role in overall productivity (Naiman and Sibert 1979) and that bac- terial biomass is an important component of that system, the actual percentage of total organic carbon that is cycled through bacterial biomass is still difficult to estimate. Excluding all other sources of carbon, it has been estimated that between 10 and 15% of macrophytic carbon (Stuart, Newell, and Lucas 1982) and between 3 and 30% (Jensen 1983) or up to 33% (Laake, Dahle, and Hentzschel 1983) of phytoplankton carbon is converted to bacterial biomass. In another study, the investigators estimated that between 20 and 60% of the phytoplankton carbon that was fixed by pri- mary productivity was consumed by microheterotrophs (Linley, Newell, and Lucas 1983). Azam, Fenchel, Field, Gray, Meyer-Reil, and Thingstad (1983) concluded that between 10 and 50% of all the carbon that is fixed by photosynthesis in the water column is used by bacteria, and most of this carbon is subsequently cycled to the rest of the food chain via nanoplanktonic hetero- trophic flagellates. Although their study concerned only free bacteria in the water column, they concluded that sim- ilar principles would apply to detrital particles as well. In another study of carbon cycling in Kiel Bight, Rheinheimer (1981) concluded that between 15 and 30% of the yearly pri- mary production was transformed to bacterial biomass. The above studies were conducted in various geograph- ical areas using different techniques, and the conclusions were often based on different assumptions. However, it does seem clear that in general terms, approximately 10 to 50% of all primary production in the marine environment is cycled through bacteria. The relative importance of bacterial biomass production will depend to a large extent on the population being con- sidered. When considering the diets of marine herbivores, bacterial biomass is probably relatively unimportant. On the other hand, the high correlation found between Microbiology 229 nematode biomass and microbial biomass by Hanson, Ten- ore, Bishop, Chamberlain, Fainatmat, andTietjen (1981) and the close predator-prey relationship observed by Azam et al. (1983) between nanoplanktonic heterotrophic flagellates and bacteria suggest that both nematodes and nanoplanktonic heterotrophic flagellates are very much dependent on bacterial biomass. This principle is also well illustrated in the case of the food chain dynamics of chum salmon fry. During their first few weeks in saltwater, chum salmon feed heavily on harpacticoid copepods. Sibert, Brown, Healey, Kask, and Naiman (1977) found that harpac- ticoid copepods are primarily dependent on bacteria as a food source. Their findings strongly suggested that the high microbial productivity that they observed in an estuary in British Columbia was critical to the high salmonid produc- tivity of the region. Areas of high microbial activity may also be important in relation to salmonid production in the Gulf of Alaska. Carbon Cycling in the Water Column The pelagic microbial community is generally classified as either free-living or particulate-associated. While there is still considerable controversy concerning the relative roles of these two populations in the marine environment, it is generally accepted that their relative importance varies with the environment (Azam and Hodson 1977; Hanson and Wiebe 1977; Bell and Albright 1981; Bent and Goulder 1981; and Wright and Coffin 1983). Although these two popula- tions were not differentiated in studies of the Gulf of Alaska, a very high positive correlation was observed in Cook Inlet pelagic waters between water turbidity and relative hetero- trophic activity using both glucose and glutamate (Griffiths, McNamara, Steven, and Morita 1981). The relatively high microbial activity associated with suspended particulates in Cook Inlet suggests that these particles could be an impor- tant food source for any organisms that can trap them and then digest the associated microheterotrophs. Since most of the major rivers emptying into the Gulf of Alaska contain a high sediment load, bacterial biomass pro- duction associated with sediment particles may be an important feature of nearshore biological activity. Even without these particles, bacterial biomass production is gen- erally greater nearshore than offshore and is greatest in areas directly influenced by major river plumes. Not only is the rate of organic carbon uptake elevated, but there is also an elevation in microbial biomass production in the plumes when compared with the surrounding seawater (Griffiths, McNamara, Steven, and Morita 1981; Griffiths, Caldwell, and Morita 1984). This phenomenon was observed in essentially every major river input that was studied in Alaskan near- shore waters. In the Gulf of Alaska, it was observed on a very large scale in Cook Inlet and on a smaller scale within Kachemak Bay (Griffiths et al. 1984). The stimulation of microbial activity in areas where freshwater from terrestrial runoff and marine waters inter- mix has also been reported by others (Stevenson and Erkenbrecher 1976; Valdes and Albright 1981; and Albright 1983). The exact mechanism for this stimulation is not known, but it has been hypothesized by Albright (1983) that organic nutrients from both sources complement each other to provide a more complete nutrient for the micro- heterotrophs. The stimulation of microbial biomass pro- duction under these conditions may help explain the sources of the bacterial biomass that is required to feed young chum salmon as suggested by Naiman and Sibert (1979). It is probable that similar food chain dynamics take place in most major estuarine systems within the Gulf of Alaska. The relative microbial activities found in the Gulf of Alaska have been found to be similar to those observed in more temperate climates (Griffiths, Hayasaka, McNamara, and Morita 1978), as well as being similar to those observed in Arctic waters (Atlas and Griffiths 1984). Measurements of the uptake of "C-labeled organics by bacteria do not take into account the tracer dilution due to ambient concentra- tion of the substrate — dilution which can seriously affect measured uptake values. However, the data support the con- clusion that the microbial biomass in the food chain of the Gulf of Alaska is comparable to the microbial biomass in the food chains of other regions of the world's oceans. During studies of relative microbial activities in the waters of Kachemak Bay, Griffiths, Caldwell, and Morita (1982) observed seasonal trends that indicate that the pelagic microorganisms change both qualitatively and quan- titatively. From the results of this study and from patterns of relative microbial heterotrophic activity observed during several cruises in Cook Inlet (Griffiths and Morita 1981), it was concluded that the major seasonal variation observed in pelagic microbial communities is directly related to phy- toplankton bloom activity. These seasonal variations strongly suggest a link between the release of dissolved organic compounds by phytoplankton during a bloom cycle and the incorporation of this material into microbial bio- mass (Griffiths, Caldwell, and Morita 1982). The same rela- tionship was suggested by the nutritional data reported by Hauxhurst et al. (1981). During these studies, Griffiths, Caldwell, and Morita (1982) detected a shift in the qualitative characteristics of the microbial population as the population responded to the phytoplankton bloom. During periods when phy- toplankton activity was relatively low, the ratio of the glucose uptake rate to the glutamate uptake rate was approximately 0.1, indicating that the potential rate at which glutamate could be utilized was approximately 10 times greater than that for glucose. During an active phy- toplankton bloom the ratio was approximately 1.0. Quan- titative shifts in bacterial populations during phv- toplankton blooms have also been reported by Lelong, Bianchi, and Martin (1980) and Rieper (1976). The link between both qualitative and quantitative changes in pelagic microbial communities and phy- toplankton bloom cycles is well established (Saunders and Storch 1971). Typically these changes occur either in response to the extracellular carbon produced by the phy- toplankton (Smith, Barber, and Huntsman 1977; Hollibaugh 1979; and Larsson and Hagstrom 1979, 1982) or in response to injured or decomposing phytoplankton (Fuhrman, Ammerman, and Azam 1980; Fukami, Simidu, and Taga 1981). Both qualitative and quantitative changes may also 230 Biological Resources occur in response to sedimentation of the starch particles produced bv phvtoplankton (Bursa 1968). The fact that sim- ilar phytoplankton-microbial interactions have been found in other marine systems again suggests that the bloom responses that were observed in the Gulf of Alaska are not unique to this region. Carbon Cycling in the Sediments In shallow nearshore environments, cycling of organic carbon through the benthic community is undoubtedly an important feature of this area's biological productivity. Unfortunately, there are no standardized methods for meas- uring relative microbial heterotrophic activity in marine sediments. Therefore, it is difficult to make direct com- parisons between those rates observed in the Gulf of Alaska and rates observed in other marine systems. However, com- parisons can be made with rates observed in more northern Alaskan waters (Table 8-5). Although differences were observed in the mean values of samples from different regions that were collected at different times, none of these differences was statistically significant. Of greater interest and significance were the seasonal changes that were observed in the sediments from Kachemak Bay (Fig. 8-1; Table 8-6), which were analyzed using methods described by Griffiths, Caldwell, Broich, and Morita (1983). In contrast to the seasonal variation in the water column, where there is a variation factor of 10, the relative microbial activities observed in the sediments collected near Kasitsna Bay were relatively constant with a seasonal variation factor of about three. The increased microbial activity observed in July 1979 could have been caused by either a seasonal increase in temperature or by the input of detrital carbon into the system. Temperature has been discounted as a sig- nificant factor in this increase, since the correlation between temperature and glutamate uptake was not sig- nificant and the correlation with glucose uptake was very low. Additionally, the maximum mean sediment tem- perature was found in November when the mean rate of substrate uptake was again reduced to a more normal level (Table 8-6). It is much more likely that this elevated activity was related to an elevated input of detrital carbon. This detrital input could have been from terrestrial sources but it was more likely in response to the early and intense phy- toplankton bloom that had occurred in the spring of that Table 8-5. Comparison of microbial uptake rates (ng/g-h) found in Arctic and subarctic marine sediments. 151u30' Glucose Uptake Glutamate Uptake Location Time Mean Range Mean Range Beaufort Sea Summer 1976 4 1-15 80 20-180 Beaufort Sea Summer 1978 9 1-24 96 7-262 Norton Sound Summer 1979 28 0.1-154 127 3-1063 Bristol Bay Spring 1981 - - 215 149-345 Cook Inlet Fall 1976 12 1-56 220 70-1190 Cook Inlet Spring 1977 8 1-18 217 80-370 Cook Inlet Fall 1977 4 0.4-22 63 20-252 Cook Inlet Spring 1978 4 0.1-38 89 5-595 151°30' Figure 8-1. Microbiological sampling locations within Kachemak Bay. Table 8-6. Glucose and glutamate uptake rates (ng/g-h) in sediments collected in and near Kasitsna Bay. Glucose Uptake Gl.UTAM Mean ate Uptake Time Mean Range Range Winter 1979 25 3-110 340 32-1860 Spring 1979 27 5-73 320 35-940 Summer 1979 140 20-360 1070 180-3600 Fall 1979 57 4-180 320 41-1260 Winter 1980 46 11-120 380 110-1110 Spring 1980 53 10-140 380 130-780 Summer 1980 50 9-150 470 120-960 year (Griffiths, Caldwell, and Morita 1982). During the sec- ond season of the study, the spring phytoplankton bloom occurred two months later and there was no stimulation in samples collected in the first week of July. An apparent rela- tionship between a phytoplankton bloom and increased microbial activity in marine sediments has also been found in the Baltic Sea (Graf, Bengtsson, Diesner, Schulz, and Theede 1982). A number of studies have shown that organic nutrients are introduced into marine sediments either during or after a major phytoplankton bloom. This carbon source forms a major portion of the carbon required to maintain the benthic community (Iturriaga 1979; Hargrave 1980; and Wassmann 1983). Chester and Larrance (1981) concluded that the extremely high productivity of both benthic and pelagic animals in Kachemak Bay (located within Cook Inlet) was the direct result of a high flux of organic matter consisting mostly of phytoplankton and phytoplankton- derived material that was incorporated into the sediments of the Bay. A lag that occurs between the time of the phy- toplankton bloom and the elevated microbial activity may be related to the time it takes the bioturbation process to incorporate this carbon into the sediments (Yingst and Rhoads 1980). Microbiology 231 Table 8-7. Enzyme activities found in sediments collected at locations illustrated in Figure H-2. Mean values are given on first line; ranges oi variation are given in parentheses. Amylase and cellulase activities are ug gluco.se/g-h; phosphatase and arylsulfatase activities are LtM p-nitrophenol/g-h; nitrogenase activities are ng N._,/g-h. Tl.Ml Amylase On fi.-x.st Phospha 1 ASI Aryi.m i i \i \m Nil K< H.I N AM Winter 1979 32 16 0.27 0.50 0.7 (11-62) (4-31) (0.03-0.81) (0.01 1.41) (0-2.3) Spring 1979 28 14 0.22 0.37 0.9 (11-83) (7-35) (0.13-0.41) (0.08-0.62) (0-2.1) Summer 1979 26 18 0.31 0.60 0.9 (10-45) (8-38) (0.14-0.48) (0.30-1.12) (0-4.2) Fall 1979 32 12 0.27 0.48 1.7 (11-100) (2-49) (0.15-0.62) (0.09-1.04) (0-7.5) Winter 1980 19 10 0.28 0.63 0.9 (6-51) (4-20) (0.14-0.50) (0.21-1.13) (0.3-1.8) Spring 1980 30 14 0.23 0.41 0.9 (14-75) (8-33) (0.12-0.44) (0.14-0.85) (0-1.7) Summer 1980 28 21 0.34 0.56 1.3 (10-73) (8-43) (0.19-0.70) (0.16-1.19) (0.2-3.1) Chester and Larrance (1981) also measured microbial activity by assaying potential activities for five enzymes: phosphatase, amylase, hydrolase, arylsulfatase, and cellulase (Table 8-7). Phosphatase and arylsulfatase activities were measured as indicators of general microbial activity. Amylase and cellulase activities were measured as indicators of potential hydrolase activities for the degradation of starch and cellulose, respectively. For those sediments that were tested, no significant seasonal changes took place in any of these enzymes. This relative seasonal consistency in microbial activities may be attributed to a relatively constant source of usable organic carbon throughout the year. Dur- ing the winter months, the major contributor of detrital car- bon is probably Laminaria and related macrophytes (Lees 1978). This Laminaria growth is likely based both upon algal organic carbon produced during the summer and upon inorganic nutrients released from sediments by bacterial activity during fall and winter periods. It has been estimated that the biomass produced annually by the macrophytes in Kachemak Bay equals the biomass produced by phy- toplankton in the same region (Lees 1978). To supplement this source of carbon, there is some freshwater runoff dur- ing most of the winter. Presumably, this provides terrestrial carbon input throughout the year. This pattern of seasonal consistency is in stark contrast to the seasonal differences observed in Arctic marine sedi- ments and in the mouth of Kachemak Bay. For example, Griffiths et al. (1978) observed a 10-fold seasonal variation in the relative heterotrophic activities between summer and winter in Beaufort Sea sediments and in the mouth of Kachemak Bay (Table 8-8). This seasonal difference was attributed to seasonal changes in the input of detrital car- bon into the two systems. During the winter months, the Beaufort Sea has little or no light for photosynthesis, no ter- restrial runoff, and very few areas where significant mac- rophytic carbon can come into the system. This reduction in activity also accounts for the 10-fold reduction in adenylate concentrations in Elson Lagoon sediments (Beaufort Sea) (Atlas and Griffiths 1984). In Kasitsna Bay sediments no sea- sonal changes were observed in total adenylates. The Elson Lagoon data suggest that during the winter, there is a reduc- tion both in microbial biomass and in total benthic biomass for all organisms smaller than 2 mm residing in Arctic sedi- ments. This does not seem to occur in the more temperate subarctic marine sediments of Kasitsna Bay. It has been known for some time that there is an inverse correlation between microbial activity and the distance from shore. There are also two other generalizations that can be made about microbial activities in marine sediments. As Griffiths et al. (1983) observed in Bristol Bay, there is ele- vated microbial activity in areas where fine particles settle out of the water column and are incorporated into the sedi- ments. In the Gulf of Alaska there are various geological fea- tures such as Prince William Sound and areas near Kayak Island which should allow extensive settling of fine-grained Table 8-8. Rates of various microbial activities observed along the Kachemak Bay transect. All values are the means of three observations. Station locations are shown in Figure 8-1. Glucose and glutamate uptakes and alginase activities are in Ltg glucose/g-h; phosphatase and arylsulfatase activities are shown as a ratio of these two activities; and nitrogenase activities are ng N2/g-h. Glucose Glutamate Nitrogen Arvlsulfatase/ Station Uptake Uptake Fixation Phosphatase Alginase Winter 1979 A 10 104 0.03 0.52 B 46 384 0.10 0.49 C 25 200 0.61 D 12 138 0.46 1.16 E 1.51 F 5 104 0.76 3.95 Summer 1979 B 16 146 0.00 0.69 5.3 C 30 208 0.70 0.75 7.0 D 47 402 1.38 1.04 9.8 E 69 535 1.56 1.26 9.9 F 82 662 2.57 2.37 11.7 232 Biological Resources particles. From the known geographical distributions of rel- ative microbial heterotrophic activity, it is possible to pre- dict that areas like Prince William Sound are areas of high microbial biomass productivity and are therefore impor- tant features of secondary productivity in the Gulf of Alaska. Gulf of Alaska studies have also shown that microbial activity is elevated in the soft sediments that lie within the normal plume pattern of major rivers (Atlas et al. 1983). How- ever, the areas of highest activity may not be those areas clos- est to the mouth of the river. A good example of this is where the Yukon River empties into Norton Sound. Most of the sediments near the major outlets of the Yukon are sandy and do not have elevated microbial activities (Atlas et al. 1983). In areas to the east and northeast (where prevailing currents presumably carried fine-grained terrestrial detritus), microbial activities were greatly elevated. Elevated microbial activities have also been found in sediments near the major rivers in the Beaufort Sea (Atlas and Griffiths 1984). Kachemak Bay may serve as a model for many embay- ments within the Gulf of Alaska because of the seasonal and geographic variations in the sources of detrital carbon that occur within it. As indicated above, the major detrital inputs are from phytoplanktonic, macrophytic, and terrestrial car- bon. Although all of these carbon sources can be found throughout the Bay, one of these sources probably domi- nates in each area. The major source of terrestrial carbon in the region should be the Fox, Bradley, and Martin Rivers which flow into the head of Kachemak Bay. The bulk of the macrophytic community is found along the entire south- eastern shoreline and must represent the major input of organic carbon into the soft sediments along this shoreline (Lees 1978). Although phytoplankton undoubtedly flourish throughout the Bay, their productivity is particularly high at the mouth of the Bay seaward of the Homer Spit (Chester and Larrance 1981). The waters in the inner Bay are often very turbid and thus primary productivity is reduced. Terrestrial carbon should also be a relatively constant source of detrital carbon to the benthic community. Although river flow rates and detrital carbon input rates can vary seasonally, there is at least some flow during most of the year in this area. Since most of the particulate terrestrial car- bon requires some processing by marine invertebrates and bacteria before it can become useful as food for higher trophic levels, the seasonal pulses of new carbon should be buffered in their effects on microbial activities. The carbon input from phytoplankton blooms should have entirely different characteristics. Because phyto- plankton represent a readily degradable source of high- quality food, they should provide a relatively transient source of high-quality, carbon-containing compounds (e.g., simple carbohydrates). This results in a pulse of elevated microbial activity after a major bloom. During studies on Kachemak Bay, sediment samples were collected and ana- lyzed along two transects; one was sampled in July after a large early phytoplankton bloom in the area (Griffiths, Cald- well, and Morita 1982) and the other was sampled in January. If the above assumptions are correct, one would expect to find maximum microbial activity in the sediments collected near the major rivers, and much lower activity in sediments collected outside of Homer Spit during January. This, indeed, is what was found when relative microbial activity was measured using either glucose or glutamate (Table 8-8). In the summer, on the other hand, one would expect to find a gradient of increasing microbial activity from the area near the river input to the outside of the spit where phy- toplankton biomass should have recently sedimented out of the water column. Again, this is the pattern that was found in July (Table 8-8). Additionally, if these assumptions are correct, one would also expect to find greater seasonal vari- ability in microbial activity in the offshore stations where phytoplankton carbon should dominate than in stations where terrestrial carbon should dominate. Again, the obser- vations support these assumptions. Arylsulfatase, phosphatase, and alginase activities were also measured during these studies. Measurements were made to determine if the microbial function in the Bay was influenced by differing sources of detrital carbon. In these studies, phosphatase activity was assumed to act as a general indicator of microbial activity (Kobori and Taga 1974; Kan- eko et al. 1978) even though other organisms are known to produce this enzyme (Rivkin and Swift 1979; Griffiths et al. 1983). The arylsulfatase activity, on the other hand, should reflect a more specific microbial population, such as bac- teria that have adapted to using particulate carbon from a marine source (Oshrain and Wiebe 1979). If these assump- tions are correct, and if there is a gradient of terrestrial car- bon from the head to the mouth of Kachemak Bay, an increase in the ratio of arylsulfatase to phosphatase should have been observed in sediments collected along this gra- dient. This was found (Table 8-8). These same trends were found on a smaller scale in two side bays where there was a source of terrestrial carbon at the heads of both bays (Fig. 8-2). Alginase activity was also measured. If the assumptions about the terrestrial carbon gradient along Kachemak Bay are correct, there should be a positive correlation between the marine algal alginin input into sediment detritus and the distance from the head of the Bay. If this is true, and 151°30' 151°30' Figure 8-2. Ratios of arylsulfatase to phosphatase activities in sediments near Kasitsna Bay. Microbiology 233 microbial enzymatic activities adjust to the presence of this compound, an increase in alginase activity along the Kachemak Bay head-to-mouth transect would be expected. This was found (Table 8-8). These studies in Kachemak Bay showed that the charac- teristics of carbon cycling in Bay sediments depend heavily upon the source of the detrital carbon. The patterns that were found at the mouth of Kachemak Bay are probably typ- ical of many shallow nearshore environments where phy- toplankton carbon provides most of the carbon for the detrital food chain. In such a system, organic carbon should be cvcled very rapidly and there are undoubtedly long per- iods when secondary productivity is low in the benthic com- munities. The sediments near the head of Kachemak Bay are typical of the soft sediments found adjacent to the mouths of large rivers. Here most of the carbon is in a rela- tively recalcitrant form that provides a constant source of organic carbon for the detrital food chain throughout the year. The areas which have the highest and most consistent input of carbon for the detrital food chain should be found in small bays such as Sadie Cove and Tutka Bay (see Fig. 8-2). These areas do not have a large water column particu- late load due to either terrestrial runoff or to sediment resuspension from wave or tidal action. In bays such as these, there is carbon input under essentially ideal condi- tions from all major sources. The water is clear enough to allow spring phvtoplankton blooms to occur, there is some terrestrial input from the surrounding watershed, and there is ample rocky substrate to allow extensive macrophytic growth (Lees 1978). The end result is that a high constant level of good-qualitv detrital carbon flows through the sys- tem, allowing it to support a highly productive marine assemblage (Lees 1978). These bays are probably good sys- tems to use as models for most of the southeastern Alaskan coastline. Nitrogen Cycling Insufficient quantities of either fixed nitrogen or phos- phorus can be a limiting factor in the growth of marine phv- toplankton. Therefore, these compounds are an important feature of overall biological productivity. Both the miner- alization of these compounds from organic matter and the equilibria between atmospheric and combined nitrogen are greatly affected by microbial processes. Nitrogen recycling by microorganisms both in nearshore sediments and in marine waters plays a vital role in providing nutrients to the phvtoplankton. A study of 'whole phvtoplankton debris' degradation by marine microorganisms has shown that as much as 30.8% of the carbon is mineralized and returned to the environment within three days (Newell, Lucas, and Linlev 1981). Even the more recalcitrant carbon (64.4%) was mineralized by bac- teria within 11 days. In studies of nitrogen mineralization in Saanich Inlet, British Columbia, Harrison (1978) found usable nitrogen turnover rates of between 3 and 16 days and observed that 'microplankton' were the primary nitrogen mineralizers. While conducting studies of ammonium regeneration rates in Nova Scotia, LaRoche (1983) found that rapid mineralization in the water column could account for 36% of the ammonia needed for phytoplankion growth. Bacterial mineralization is also an important factor in kelp bed productivity (Newell, Field, and Criffiths 1982). Although microbial mineralization of organic matter may be an important mechanism for sustaining phy- toplankton productivity in the water column, it is becoming increasingly clear that mineralization by benthic micro organisms is not only important for benthic productivity, but is also a potentially important source of inorganic nutrients for the water column as well (Hattori 1982). Studies of nearshore environments indicate that most phy- toplankton inorganic-nutrient requirements could be met by the nitrogen and phosphorus released from the sedi- ments. While studying phosphorus mineralization in Nar- ragansett Bay, Rhode Island, Nixon, Kelly, Furnas, Oviatt, and Hale (1980) found that the Bay released enough phos- phorus to provide 50% of the phosphorus requirement for phytoplankton productivity. Fisher, Carlson, and Barber (1982) reported that between 28 and 35% of both the nitro- gen and the phosphorus requirements for the primary pro- ductivity in three North Carolina estuaries came from min- eralization in nearshore sediments. From their analysis of mid-American coastal waters, Sharp and Church (1981) con- cluded that one-third to two-thirds of all nitrogen required for primary productivity was mineralized from the sedi- ments. Similar conclusions have also been reached by Davies (1975) in studies of a Scottish sea loch, and by investi- gators in earlier works summarized in a review by Zeitzschel (1980). The most vigorous mineralization rates probably occur at the sediment-water interface (Kemp, Wetzel, Boyn- ton, D'Elia, and Stevenson 1982; Garber 1984). When one considers nitrogen cycling as it relates to the mineralization process, one must also account for both the conversion of atmospheric nitrogen to combined nitrogen (nitrogen fixation) and the loss of combined nitrogen to atmospheric nitrogen (denitrification). Although these processes may be relatively insignificant relative to the total nitrogen flux in nearshore environments (Marsho, Bur- chard, and Fleming 1975), these processes can be locally important. While studying nitrogen fixation in a salt marsh, Teal, Valiela, and Berlo (1979) observed that nitrogen fixa- tion could account for somewhat less than a third of the total nitrogen requirement for the local marsh grass. Capone, Penhale, Oremland, and Taylor (1979) and Zuberer and Sil- ver (1978) reached the same conclusion in studies of two other marine systems. At least two factors can greatly influence nitrogen fixa- tion rates in marine sediments: 1) the presence of inorganic combined nitrogen tends to suppress the rates, and 2) the availability of readily degradable sugars tends to stimulate the rates. Two studies have reported the effect that com- bined nitrogen has on nitrogen fixation in salt marsh sedi- ments. Hanson (1977) found that nitrate inhibited nitrogen fixation more than ammonium did, and that ammonium inhibited nitrogen fixation more than organic nitrogen. Dicker and Smith (1980) made similar observations, but they also found a seasonal component to the degree in which ammonium inhibited nitrogen fixation. It is generally agreed, however, that the primary limiting factor for nitro- 234 Biological Resources gen fixation in marine sediments is a readily oxidizable car- bon source (Herbert 1975; Marsho et al. 1975; Hartwig and Stanley 1978; and Jones 1982). Of perhaps greater ecological significance than nitrogen fixation is the process of denitrification. Whenever nitrate is present in microaerophilic marine environments, either in the water column or in sediments, it can be converted to N.,0 or N., by microbial denitrification. Denitrification may be one of the major mechanisms for releasing inorganic nitrogen from sediments. Nishio, Koike, and Hattori (1982) reported that denitrification accounted for between 27 and 57% of nitrate consumption in three bays along the Japa- nese coast. In a study of denitrification in Narragansett Bay, Seitzinger, Nixon, and Pilson (1984) concluded that 35% of all mineralized nitrogen was removed from the sediments by this process. At the present time, relatively little is known about the dynamics of nitrogen cycling in the Gulf of Alaska. Most of what is known comes from relatively few sources: a study of amino acid uptake and regeneration by phytoplankton communities in Southeast Alaska (Schell 1974), a study of nitrogen fixation and denitrification in Cook Inlet and Shelikof Strait (Haines, Atlas, Griffiths, and Morita 1981), and studies of glutamate metabolism, nitrogen fixation, and denitrification in Kachemak Bay (reported in this chapter). If one assumes that relative microbial activity measure- ments using an amino acid as the test substrate reflect rela- tive levels of nutrient mineralization, then one can make certain statements concerning relative mineralization rates in both the waters and the sediments of the Gulf of Alaska. As this and other reports show (Griffiths et al. 1978; Griffiths, McNamara, Steven, and Morita 1981; Griffiths, McNamara, Caldwell, and Morita 1981; Griffiths, Caldwell, and Morita 1982; Griffiths, Caldwell, Broich, and Morita 1982a; Griffiths et al. 1983; and Atlas and Griffiths 1984), glutamate miner- alization rates both in Arctic and subarctic sediments and in Arctic and subarctic waters are comparable to those in other parts of the world. This is because the presence of a suitable substrate is more ecologically important than temperature. In other words, if a suitable substrate is present (i.e., amino acids for mineralization, simple sugars for nitrogen fixa- tion, and/or nitrate for denitrification), bacteria adjust to the colder conditions so that glutamate-mineralization dynam- ics end up being very similar to those found in warmer waters. Using the report by Schell (1974) and observations by Griffiths, Caldwell, and Morita (1982), we can conclude that mineralization rates in the water column are closely tied to the phytoplankton bloom. In the waters of southeastern Alaska, Scbell (1974) found that inorganic nitrogen sources were much more important to phytoplankton growth than dissolved organic nitrogen (DON). Therefore, we assume that mineralization by microheterotrophs is important to maintaining productivity during spring phytoplankton blooms. Any link between primary productivity and nutrient mineralization should result in cycles of increased dissolved inorganic nitrogen (DIN) and in surges of primary productivity following the initial intense spring bloom. This is essentially what Schell (1974) found in his study. There is now a large body of data (reviewed by Hattori 1982), which indicates that the mineralization process carried out by microheterotrophs can be extremely important in main- taining primary productivity in the marine environment once the initial bloom has consumed most of the available inorganic nutrients. In addition to the elevated mineralization rates associ- ated with the phytoplankton bloom, Griffiths, McNamara, Steven, and Morita (1981) and Atlas et al. (1983) found ele- vated mineralization rates in major river plumes. Miner- alization of terrestrial organic material by marine hetero- trophs may contribute significantly to the high biological productivity associated with these plumes (Griffiths, Cald- well, and Morita 1984). Based on observations made in Cook Inlet, it is reasonable to assume that heterotrophic miner- alization is an important feature of all major river plumes in the Gulf of Alaska. In Gulf of Alaska sediments, important inorganic nutrients are recycled via mineralization at rates that depend on both the quality and quantity of the carbon com- ing into the system. As was the case for marine waters that were affected by major river plumes, elevated mineraliza- tion rates have been found in sediments that are affected by the same plumes (Atlas et al. 1983; Atlas and Griffiths 1984). The impact that carbon has on mineralization rates has been graphically illustrated in sediment samples from both the Beaufort Sea and Kachemak Bay. Large seasonal dif- ferences in mineralization rates were found in the Beaufort Sea study (Griffiths et al. 1978). It was hypothesized that the differences resulted from extreme seasonal differences in the amount of organic carbon being introduced from all sources. Similar seasonal changes in mineralization rates were found in the mouth of Kachemak Bay (Table 8-8) where most of the new organic carbon probably comes from spring and summer phytoplankton blooms (Chester and Larrance 1981). In sediments where organic carbon supplies should be more constant, such as in Kasitsna Bay and at the head of Kachemak Bay, mineralization rates showed much greater seasonal consistency (Tables 8-6 and 8-8). The nitrogen fixation and denitrification rates for sedi- ments from Cook Inlet and Shelikof Strait and the rates for sediments from other Alaskan marine waters (Table 8-9) agree with those rates reported by other investigators work- ing in other regions (Haines et al. 1981). In addition to these studies, both nitrogen fixation and denitrification have Table 8-9. Comparison of mean rates of nitrogen fixation and denitrification in sediments from different regions of the Alaskan continental shelf. N 2 Fixation Denitrification Region (mg- at N2-N/m2h) (mg- -at N2-0-N/m2h) Upper Cook Inlet 0.3 0.1 Kamishak Bay 1.0 25.6 Shelikof Strait 2.4 2.1 Norton Sound 0.8 4.3 Elson Lagoon Winter 0.4 0.3 Spring 4.6 <0.1 Summer 2.1 <0.1 Microbiology 235 been measured for sediment from Kachemak Bay to deter- mine seasonal and geographical patterns for this area. Measurements of denitrification rates were conducted on Kachemak Bay sediments collected at various locations and at different times of the year. Using a standard acetylene block technique, NzO production was rarely detected from nonamended sediments, even though the minimum sen- sitivity for this method is 0.002 ng NL,/g«h. We are unclear as to why significant natural denitrification rates were not detected in these particular sediments, even though rela- tively high denitrification rates were found in sediments from across Cook Inlet in Kamishak Bay (Haines et al. 1981). It may be related to the availability of nitrate in these sedi- ments. Very high denitrification rates were found when nitrate was added to the assayed sediments (Griffiths and Morita 1981). This indicates that Kachemak Bay sediments had the potential to denitrify, but that there was very little available nitrate present. Since the denitrification rates observed by Haines et al. (1981) were of the same magnitude as those reported by others, one must assume that the denitrification process works in Gulf of Alaska sediments in the same manner that it does in other marine system sediments. As discussed earlier, there are reports indicating that nitrogen fixation provides significant combined nitrogen for salt marsh plants that grow in more temperate waters (Zuberer and Silver 1978; Capone et al. 1979; and Teal et al. 1979). McRoy, Goering, and Chaney (1973), however, found no nitrogen fixation associated with seagrasses taken from both Izembek Lagoon (Alaska Peninsula) and Prince William Sound and concluded that nitrogen fixation was an unimportant source of nitrogen for these glasses. Nitrogen fixation levels in the sediments of Cook Inlet and Shelikof Strait suggest that rates for these sediments are comparable to those reported elsewhere. In addition, nitro- gen fixation rates found in Kachemak Bay suggest that char- acteristics of the detrital carbon that comes into the system influence nitrogen fixation. No significantly consistent sea- sonal changes in nitrogen fixation rates were found for sedi- ment collected near Kasitsna Bay (Table 8-7). This appears to be another indication that these sediments receive a rela- tively consistent input of detrital carbon throughout the year. The lack of seasonal variability in the nitrogen fixation rates for Kasitsna Bay sediments contrasts sharply with the wide variation we found in the rates for sediments collected near the mouth of Kachemak Bay (Table 8-8). In the same study, we also found that nitrogen fixation rates increased as the distance from the head of Kachemak Bay increased (Table 8-8). It is possible that both the elevated seasonal variability and the gradients can be explained in terms of phytoplankton as a carbon source for the system. Phy- toplankton represent a relatively high quality food source in the marine environment. This food source includes not only cytoplasm but starch granules that settle out of the water column (Bursa 1968). Carbon input from phyto- plankton is seasonal in nature, which may explain the seasonal changes in the nitrogen fixation rates found in sed- iments taken from the mouth of the Bay. How distance from the head of the Bay affects nitrogen fixation could be explained in terms of the relative food value of phy- toplankton versus the food value of leaves and woody debi is that are presumably the major components of the detrital carbon found in the sediments near the head of the Bay. Microbial Activities and Pollutants in the Gulf of Alaska Biodegradation of Petroleum Hydrocarbons Oil and gas development within the Gulf of Alaska, cou- pled with petroleum transportation from Valdez, acts to raise the chances that petroleum pollutants will be acciden- tally introduced into the Gulf. After petroleum pollutants are introduced into marine environments, they are subject to microbial biodegradation. The rate of that biodegrada- tion is influenced by a number of factors, including the abundance of hydrocarbon-degrading microorganisms, the composition of the oil, and the environment (tem- perature, dissolved oxygen levels, and nutrient concentra- tions) (Karrick 1977; Atlas 1981, 1984c). Although there have been no major oil spills in the Gulf of Alaska, the wreck of the ship Irish Stardust in 1973 spilled — 180 mt of heavy fuel oil into a British Columbia embay- ment. Cretney, Wong, Green, and Bawden (1978) reported that biodegradation accounted for almost complete removal of n-alkanes in this oil during the first year after the spill, and although pristane and phytane were biodegraded more slowly, they were almost completely gone after 4 years. The non-ft-alkane components of the C28 to C30 range appeared to be the most resistant to degradation of all the components of the fuel oil. Roubal and Atlas (1978) reported that hydrocarbon uti- lizers were ubiquitously distributed, with no significant con- centration differences between Arctic and subarctic sam- pling regions nor between surface water and sediment samples. Counts of hydrocarbon degraders for various regions of Alaska are listed in Table 8-1 (Atlas 1982). Robertson, Arhelger, Law, and Button (1973) and Robertson, Arhelger, Kinney, and Button (1973) reported 1/ml concentrations of hydrocarbon degraders in Cook Inlet and Port Valdez. The distribution of hydrocarbon utilizers within Cook Inlet was positively correlated with the occur- rence of hydrocarbons in the environment (Roubal and Atlas 1978). Areas of hydrocarbon accumulation within Cook Inlet and surrounding waters had elevated abun- dances of hydrocarbon-degrading microorganisms (Atlas et al. 1983). These findings are in agreement with studies indicating that the distribution of hvdrocarbon-utilizing microorganisms reflects the environment's historical exposure to hydrocarbons (Atlas 1981; Floodgate 1984; and Vestal, Cooney, Crow, and Berger 1984). Roubal and Atlas (1979) reported that water samples from Cook Inlet showed low potential for natural biodegradation in both spring and fall. Cook Inlet sediment showed some- what higher natural biodegradation potentials in sum- mer-through-fall samples than in winter-through-spring samples. Biodegradation potentials followed the order: naphthalene > hexadecane > pristane ^ benzanthracene. 236 Biological Resources and natural biodegradation potentials for pristane and ben- zanthracene were often zero. Kinney, Button, and Schell (1969) reported that hydrocarbons within Cook Inlet bio- degrade rapidly and that concentrations of nitrogen and phosphorus nutrients do not limit the rate of microbial hydrocarbon degradation in this region. Arhelger, Robertson, and Button (1977) compared Arctic and subarctic hydrocarbon biodegradation and found that dodecane oxidation rates were: Port Valdez, 0.7 g/d; Chukchi Sea, 0.5 g/d; and Arctic Ocean, 0.001 g/d. This study indicates that hydrocarbon degradation rates show a defi- nite climatic shift and are higher in the Gulf of Alaska region than in the Arctic Ocean. Button, Robertson, and Craig (1981) found that toluene oxidation rates in the Port Valdez estuary were in the range of 1 to 30 pg/1. Near the bal- last-water injection site of the trans-Alaska pipeline's load- ing facility, the bacterial biomass was elevated by a factor of 10; the origin of bacteria in this layer was traced to growth in oil-tanker ballast water during shipments. Effects of Hydrocarbons on Microbial Activities Currently available information indicates that the long- term impact that petroleum hydrocarbons have on micro- bial activity in marine sediments is greater than the impact in marine waters. The extent of that impact may also vary with the latitude at which the impact occurs. An early study (Hodson, Azam, and Lee 1977) reported on the effects that petroleum hydrocarbons have on the uptake of organic substrates by microplankton. As a part of the Controlled Ecosystem Pollution Experiments (CEPEX) program, these investigators examined the effects that Kuwait and Louisiana crude oil, No. 2 fuel oil, and Bunker C oil had on the assimilation and mineralization of glucose by microbial populations from Saanich Inlet, British Colum- bia, Canada. They demonstrated that all types of oil inhib- ited glucose use, although refined petroleum products inhibited glucose use significantly more than either of the crude oils. Glucose uptake and mineralization both appeared to be inhibited to a similar extent by No. 2 fuel oil. Griffiths, McNamara, Caldwell, and Morita (1981) col- lected over 200 water samples from both Arctic and sub- arctic regions. Most of the subarctic samples were collected in Cook Inlet. In samples that were exposed to crude oil, glucose uptake rates were reduced 37 to 50% when com- pared with a control group of samples that were not exposed to oil. When glutamate was used as the test sub- strate, the mean reduction was 33 percent. For these studies, incubation times were less than 12 hours and, therefore, there was little time for hydrocarbon utilizer populations to multiply. In the same paper, Griffiths, McNamara, Caldwell, and Morita (1981) followed the response of natural microbial populations to crude oil over extended exposure (up to 10 days). These studies demonstrated that after an initial period when the substrate uptake was inhibited, uptake rates increased in the treated samples until their rates greatly exceeded the rates observed in the non-oiled con- trols. This adjustment to the presence of petroleum hydro- carbons was also observed indirectly during the same study; samples that came from areas near natural oil seeps or in shipping lanes were less affected by crude oil than samples collected in areas that were not previously exposed to petroleum hydrocarbons. It was therefore concluded that the adverse effects that crude oil has on microbial hetero- trophic activity (substrate uptake rates) are short lived and those effects would have relatively little impact in overall biological activity under most circumstances. Although the initial impact of crude oil on benthic micro- bial activity was found to be somewhat less than its impact on water samples (between 14 and 36% reduction in diluted sediment samples versus reductions between 37 and 85% in water samples), the long-term effects were of much greater importance (Griffiths, McNamara, Caldwell, and Morita 1981; Griffiths, Caldwell, Broich, and Morita 1981, 1982a, 1982b). This conclusion is based on an extensive study of crude-oil effects on microbial activities and of other vari- ables in Kachemak Bay sediments. During the study, investi- gators mixed either fresh or weathered crude oil into natu- ral sediments collected at the study sites. The sediments were loaded into plastic trays which were then placed on the bottom by SCUBA divers. Subsamples from these trays were collected for up to 18 months to assess the impact of the petroleum hydrocarbons. A large number of microbial functions were affected by both the fresh and the weathered crude oils for periods of up to 18 months. The oils were at concentrations which have been reported in marine sedi- ments collected at spill sites (from 0.1-50°/oo). The micro- biologically mediated transformations found to be affected are summarized in Figure 8-3. As the figure shows, crude oil interfered with portions of all major geochemical processes. The changes have several possible explanations. They may have been caused directly by toxicity of oil components or degradation products or indirectly by secondary factors such as reduced oxygen availability. When investigators interpreted the microbiological data in terms of what they Algal Biomass Inorganic Phosphate Organic Phosphate Atmospheric Nitrogen t Nitrogen Fixation Polysaccharides Simple Sugars Figure 8-3. Diagram of nutrient cycling in the marine environ- ment. Transformations marked with black arrows are adversely affected by crude oil. Transformations labeled with numbers are primarily mediated by bacteria. Microbiology 237 learned about the hydrocarbon chemistry of these sedi- ments, they concluded that the benthic microbial commu- nities had the capacity to use the crude oil and return the sediment to its approximate original condition //the crude oil component was less than l"/<><> (Griffiths and Morita 1981). Hydrocarbon chemistry in both the treated samples and the non-treated controls looked essentially the same after 18 months — even in the sediments that had been treated with O.l'Voo crude oil — vet the redox potential was still 89% lower in the treated sediments than in the control. All other vari- ables appeared normal, however. It was abundantly clear from data by Griffiths and Morita (1981) that the self-cleansing capacity was severely impaired in sediments which were treated with 50"/o<> crude oil. After 18 months, hvdrocarbon chemical analyses strongly indi- cated that little biodegradation had taken place in the sedi- ments. The temporal trends in the microbiological studies suggested that it would take between 6 and 8 years to re-establish normal function. There is little information presently available for com- paring the effects that Griffiths and his associates observed in Kachemak Bay with effects of crude oil on marine sedi- ments taken from temperate waters. A study of hydrocarbon effects in a wide variety of locations led Pfaender and Buck- lev (1984) to conclude that petroleum hydrocarbons have a greater impact on Arctic and subarctic environments than they have on tropical and temperate environments. Griffiths, Caldwell, Broich, and Morita (1981) compared the effects of crude oil on Kachemak Bay sediments with the effects on sediment collected near Point Barrow, Alaska (well above the Arctic Circle). The comparison showed dis- tinct differences in the time required for microbial changes to take place after exposure to crude oil. In the Kachemak Bay sediments, large reductions in glucose and glutamate uptake rates were found within the first 6 weeks of exposure. In the Arctic sediment samples, no reduction was found for over a year after sediments had been exposed. Even after exposure for 2 1/2 years, glucose and glutamate uptake rates were still greatly reduced. This study showed that the effects of crude oil on the benthic microflora were similar in both Arctic and subarctic sediments, but the time it took for the changes to become manifest was much different. If most of the adverse effects of crude oil contamination result from biological activity (i.e., the production of toxic metabolic bvproducts and oxygen depletion), it is possible that both the timing and the duration of the effect may be related to hydrocarbon biodegradation rates. There may also be a direct correlation between the mean environmental tem- perature and hydrocarbon degradation rates as suggested by Pfaender and Buckley (1984). ture as well as both the physiological and nutritional proper- ties of microbial populations, investigators have discovered the versatility of the indigenous microorganisms, along with the adaptive properties that have evolved within commu- nities in response to environmental factors in various parts of the Gulf. These studies have also revealed the close link between microorganisms and other biota in the Gulf. Rate measurements of microbial metabolic activities indicate that microbially based detrital food webs are essen- tial for supporting the productivity of higher organisms. This productivity is closely tied to a number of factors, including: • relationships between bacterial and phytoplankton populations • microbial nutrient-cycling activities • microbial biomass production. New marine study methods should lead to a better under- standing of the factors controlling productivity in the Gulf. These methods should also produce a more precise com- prehension of the overall functioning of the ecosystems in the Gulf including the microbially mediated pathways and the rates of transfer involved in interpopulation dynamics. Developing such a fundamental understanding will let us do a better job of predicting the impact of human activity on Gulf productivity as well as on the general functioning of the Gulf ecosystem. Acknowledgments We wish to thank our collaborators in these studies and, in particular, B.A. Caldwell for providing the enzyme kinetic data. We also thank the officers and crews of the NOAA ships Discoverer, Miller Freeman, and Surveyor, as well as the charter vessel Ranger, for their help. Some data reported in this chapter were generated with the funding support of the Minerals Management Service, Department of the Inte- rior, through an interagency agreement with the National Oceanic and Atmospheric Administration, Department of Commerce, as part of the Outer Continental Shelf Environ- mental Assessment Program (OCSEAP). The writing of this chapter was also supported by OCSEAP. Conclusions Investigators are using modern methods to formulate the beginnings of a quantitative understanding of the role microorganisms play in marine systems. Microbiological studies of the Gulf of Alaska show that microorganisms are critical in establishing and regulating ecosvstem dynamics. By studying factors such as the microbial community struc- 238 Biological Resources References Albright, L.J. 1983 Influence of river-ocean plumes upon bac- terioplankton production of the Strait of Geor- gia, British Columbia. Marine Ecology — Progress Series 12:107-113. Arhelger, S.D., B.R. Robertson, and D.K. Button 1977 Arctic hydrocarbon biodegradation. In: Fate and Effects of Petroleum Hydrocarbons in Marine Ecosystems and Organisms. D. Wolfe, editor. Per- gamon Press, New York, NY. pp. 270-275. Atlas, R.M. 1977 Microbiological studies as part of Alaska's Outer Continental Shelf Environmental Assessment Program for offshore petroleum development. Proceedings of the Twenty-seventh Alaska Science Conference, Vol. 2. Alaska Division, American Association for the Advancement of Science, Fairbanks, AK. pp. 112-120. Atlas, R.M. 1979 Measurement of hydrocarbon biodegradation potentials and enumeration of hydrocarbon utilizing microorganisms using ^-radio- labelled spiked crude oil. In: Native Aquatic Bac- teria: Enumeration, Activity, and Ecology. J.W. Cos- terton and R.R. Colwell, editors. ASTM-STP 695. American Society for Testing and Mate- rials, Philadelphia, PA. pp. 196-204. Atlas, R.M. 1981 Microbial degradation of petroleum hydrocar- bons: an environmental perspective. Micro- biology Reviews 45:180-209. Atlas, R.M. 1982 Assessment of potential interactions of micro- organisms and pollutants resulting from petroleum development on the outer conti- nental shelf of Alaska. Final report RU 29. National Oceanic and Atmospheric Admin- istration, Office of Marine Pollution Assess- ment project office, Juneau, AK and NOAA Office of Marine Pollution Assessment, Rock- ville, MD. 320 pp. Atlas, R.M. 1983 Enumeration and estimation of biomass of microbial components in the biosphere. In: Methods in Microbial Ecology. R.G. Burns andJ.H. Slater, editors. Blackwell Scientific Publishers, Oxford, pp. 84-104. Atlas, R.M. 1984a Diversity of microbial communities. Advances in Microbial Ecology 7:1-47 . Atlas, R.M. 1984b Diversity and dynamics of marine bacterial communities. In: Proceedings, Colloque Interna- tional CNRS Bacteriologie Marine, 17-19 May, 1982, Centre National pour VExploitation des Oceans, Mar- seille. Atlas, R.M., editor 1984c Petroleum Microbioloby. Macmillan Publishing Co., New York, NY. 692 pp. Atlas, R.M. and R. Bartha 1981 Microbial Ecology: Fundamentals and Applications. Addison-Wesley, Reading, MA. 560 pp. Atlas, R.M. and R.P. Griffiths 1984 Bacterial populations of the Beaufort Sea. In: The Alaska Beaufort Sea: Ecosystems and Environ- ments. D. Schell, P. Barnes, and E. Reimnitz, editors. Academic Press, Orlando, FL. pp. 327-380. Atlas, R.M., M.I. Venkatesan, I.R. Kaplan, R.A. Feely, R.P. Griffiths, and R.Y. Morita 1983 Distribution of hydrocarbons and microbial populations related to sedimentation proc- esses in lower Cook Inlet and Norton Sound, Alaska. Arctic 36:251-261. Azam, F. and R.E. Hodson 1977 Size distribution and activity of marine micro- heterotrophs. Limnology and Oceanography 22:492-501. Azam, F., T. Fenchel, J.G. Field, J.S. Gray, L.A. Meyer-Reil, and F. Thingstad 1983 The ecological role of water-column microbes in the sea. Marine Ecology — Progress Series 10:257-263. Baross, J. and J. Liston 1970 Occurrence of Vibrio parahaemolyticus and related hemolytic vibrios in marine environ- ments of Washington State. Applied Microbiology 20:179-186. Bartley, C.H. and L.W. Slanetz 1981 Occurrence of Vibrio parahaemolyticus in estuarine waters and oysters of New Hamp- shire. Applied Microbiology 21:965-966. Bell, C.R. and L.J. Albright 1981 Attached and free-floating bacteria in the Fraser River estuary, British Columbia, Can- ada. Marine Ecology — Progress Series 6:317-327. Bent, E.J. and R. Goulder 1981 Planktonic bacteria in the Humber Estuary; seasonal variation in population density and heterotrophic activity. Marine Biology (Berlin) 62:35-45. Microbiology 239 Blake, P.A., R.E. Weaver, and D.G. Hollis 1980 Diseases of humans (other than cholera) caused by vibrios. Annual Review of Microbiology 34:341-367. Bursa, A.S. 1968 Starch in the oceans. Journal of the Fisheries Research Board of Canada 25:1269-1284. Button, D.K., B.R. Robertson, and K.S. Craig 1981 Dissolved hydrocarbons and related micro- flora in a fjordal seaport: sources, sinks, con- centrations, and kinetics. Applied and Environmental Microbiology 42:708-719. Cairns, J.C., Jr. 1979 Factors affecting the number of species in freshwater protozoan communities. In: The Structure and Function of Freshwater Microbial Com- munities. J.C. Cairns, Jr., editor. Virginia Poly- technic Institute and State University, Blacks- burg, VA. pp. 219-247. Capone, D.G., P.A. Penhale, R.S. Oremland, and B.F. Taylor 1979 Relationship between productivity and NQ (C,H,) fixation in a Thalassia testudinum com- munity. Limnology and Oceanography 24:117-125. Carlucci, A.F. 1974 Nutrients and microbial response to nutrients in seawater. In: Effect of the Ocean Environment on Microbial Activities: Proceedings of the Second United States-Japan Conference on Marine Microbiology. R.R. Colwell and R.Y. Morita, editors. Univer- sity Park Press, Baltimore, MD. pp. 245-248. Carlucci, A.F. and D. Pramer 1959 Factors affecting the survival of bacteria in sea water. Applied Microbiology 7:388-392. Carlucci, A.F. and S.L. Shimp 1974 Isolation and growth of a marine bacterium in low concentrations of substrate. In: Effect of the Ocean Environment on Microbial Activities: Proceed- ings of the Second United States-Japan Conference on Marine Microbiology. R.R. Colwell and R.Y. Mor- ita, editors. University Park Press, Baltimore, MD. pp. 363-367. Chester, A.J. andJ.D. Larrance 1981 Composition and vertical flux of organic mat- ter in a large Alaskan estuary. Estuaries 4:42- 52. Colwell, R.R. and J. Liston 1961 Taxonomic relationships among the pseudomonads.yoHnw/ of Bacteriology 82:1-14. Colwell, R.R. and R.Y. Morita, editors 1972 Effect of the Ocean Environment on Microbial Activities. University Park Press, Baltimore, MD. 587 pp. Colwell, R.R., T.C. Wicks, and H.S. Tubiash 1975 A comparative study of the bacterial flora of the hemolymph of Callinectes sapidus. Marine Fisheries Rnnew 37(5-6):29-33. Cretney, W J., C.S. Wong, D.R. Green, and C.A. Bawden 1978 Long-term fate of a heavy fuel oil in a spill- contaminated coastal bay. Journal of the Fisheries Research Board of Camilla 35:521-527. Daley, R.J. andJ.E. Hobbie 1975 Direct counts of aquatic bacteria by a modified epifluorescence technique. Limnology and Oceanography 20:875-882. Davies,J.M. 1975 Energy flow through the benthos in a Scottish sea loch. Marine Biology (Berlin) 31:353-362. Davis, J. W. and R.K. Sizemore 1982 Incidence of Vibrio species associated with blue crabs {Callinectes sapidus) collected from Gal- veston Bay, Texas. Applied and Environmental Microbiology 43:1092-1097. Dicker, H J. and D.W. Smith 1980 Physiological ecology of acetylene reduction (nitrogen fixation) in a Delaware salt marsh. Microbial Ecology 6:161-171. Dieterich, R.A. 1981 Alaskan wildlife diseases. Institute of Arctic Biology, University of Alaska, Fairbanks, AK. Dutka, B.J. 1973 Coliforms are an inadequate index of water quality. Environmental Health 36:39-46. Faghri, M.A., C.L. Pennington, L.S. Cronholm, and R.M. Atlas 1984 Bacteria associated with crabs from cold waters with emphasis on the occurrence of potential human pathogens. Applied and Environmental Microbiology 47:1054-1061. Fenchel, T. 1970 Studies on the decomposition of organic detrius derived from the turtle grass Thalassia testudinum. Limnology and Oceanography 15:14-20. Fenchel, T.M. and B.B. J0rgensen 1977 Detritus food chains of aquatic ecosystems: the role of bacteria. Advances in Microbial Ecology 1:1-58. Fishbein, M., IJ. Mehlman, andj. Pitcher 1970 Isolation of Vibrio parahaemolyticus from the processed meat of Chesapeake Bay blue crabs. Applied Microbiology 20:176-178. Fisher, T.R., P.R. Carlson, and R.T. Barber 1982 Sediment nutrient regeneration in three North Carolina estuaries. Estuarine, Coastal, and Shelf Science 14:101-116. 240 Biological Resources Floodgate, G. 1984 The fate of petroleum in marine ecosystems. In: Petroleum Microbiology. R.M. Atlas, editor. Macmillan Publishing Co., New York, NY. pp. 355-398. Fuhrman, J.A., J.W. Ammerman, and F. Azam 1980 Bacterioplankton in the coastal euphotic zone: distribution, activity and possible relationships with phytoplankton. Marine Biology (Berlin) 60:201-207. Fukami, K., U. Simidu, and N. Taga 1981 Fluctuation of the communities of hetero- trophic bacteria during the decomposition process of phytoplankton. Journal of Experimen- tal Marine Biology and Ecology 55:171-184. Garber,J.H. 1984 15N tracer study of the short-term fate of par- ticulate organic nitrogen at the surface of coastal marine sediments. Marine Ecology — Progress Series 16:89-104. Graf, G., W. Bengtsson, U. Diesner, R. Schulz, and H. Theede 1982 Benthic response to sedimentation of a spring phytoplankton bloom: process and budget. Marine Biology (Berlin) 67:201-208. Griffiths, R.P. 1983 The importance of measuring microbial enzymatic functions while assessing and pre- dicting long-term anthropogenic perturba- tions. Marine Pollution Bulletin 14:162-165. Griffiths, R.P. and R.Y. Morita 1981 Study of microbial activity and crude oil- microbial interactions in the waters and sedi- ments of Cook Inlet and the Beaufort Sea. Research Unit 190. Environmental Assessment of the Alaskan Continental Shelf Final Reports of Prin- cipal Investigators 10:417-784. Griffiths, R.P., B.A. Caldwell, and R.Y. Morita 1982 Seasonal changes in microbial heterotrophic activity in subarctic marine waters as related to phytoplankton primary productivity. Marine Biology (Berlin) 71:121-128. Griffiths, R.P., B.A. Caldwell, and R.Y. Morita 1984 Observations on microbial percent respiration values in Arctic and subarctic marine waters and sediments. Microbial Ecology 10:151-164. Griffiths, R.P., B.A. Caldwell, W.A. Broich, and R.Y. Morita 1981 Long-term effects of crude oil on uptake and respiration of glucose and glutamate in Arctic and subarctic marine sediments. Applied and Environmental Microbiology 42:792-801. Griffiths, R.P., B.A. Caldwell, W.A. Broich, and R.Y. Morita 1982a Long-term effects of crude oil on microbial processes in subarctic marine sediments amended with organic nutrients. Marine Pollu- tion Bulletin 13:273-278. Griffiths, R.P., B.A. Caldwell, W.A. Broich, and R.Y. Morita 1982b The long-term effects of crude oil on micro- bial processes in subarctic marine sediments: studies on sediments amended with organic nutrients. Estuarine, Coastal, and Shelf Science 15:183- 198. Griffiths, R.P., B.A. Caldwell, W.A. Broich, and R.Y. Morita 1983 Microbial processes relating to carbon cycling in southeastern Bering Sea sediments. Marine Ecology — Progress Series 10:265-275. Griffiths, R.P., S.S. Hayasaka, T.M. McNamara, and R.Y. Morita 1978 Relative microbial activity and bacterial con- centrations in water and sediment samples taken in the Beaufort Sea. Canadian Journal of Microbiology 24:1217-1226. Griffiths, R.P., T.M. McNamara, B.A. Caldwell, and R.Y. Morita 1981 Field observations on the acute effect of crude oil on glucose and glutamate uptake in samples collected from Arctic and subarctic waters. Applied and Environmental Microbiology 41:1400-1406. Griffiths, R.P., T.M. McNamara, S.E. Steven, and R.Y. Morita 1981 Relative microbial activity and mineralization association with water masses in the lower Cook Inlet, Alaska, USA. Journal of the Oceano- graphical Society of Japan 37:227-233. Grischkowsky, R.S. and D.F. Amend 1976 Infectious hematopoietic necrosis virus: preva- lence in certain Alaskan sockeye salmon, Oncorhynchus nerka. Journal of the Fisheries Research Board of Canada 33:186-188. Gunn, B.A. and R.R. Colwell 1983 Numerical taxonomy of staphylococci isolated from the marine environment. International Journal of Systematic Bacteriology 33:751-759. Gunn, B.A., F.L. Singleton, E.R. Peele, and R.R. Colwell 1982 A note on the isolation and enumeration of Gram positive cocci from marine and estuarine waters. Journal of Applied Bacteriology 53:127-129. Microbiology 241 Haines, J.R., R.M. Atlas, R.P. Griffiths, and R.Y. Morita 1981 Denitrification and nitrogen fixation in Alas- kan continental shelf sediments. Applied and Environmental Microbiology 41:412-421. Hanson, R.B. 1977 ( lomparison of nitrogen fixation activity in tall and short Spartina altemiflora salt marsh soils. Applied and Environmental Microbiology 33:596-602. Hanson, R.B. and W.J. Wiebe 1977 Heterotrophic activity associated with particu- late size fractions in a Sparina altemiflora salt- marsh estuary, Sapelo Island, Geogia, USA, and the continental shelf waters. Marine Biology (Berlin) 42:321-330. Hanson, R.B., K.R. Tenore, S. Bishop, C. Chamberlain, M.M. Pamatmat, andj. Tietjen 1981 Benthic enrichment in the Georgia Bight related to Gulf Stream intrusions and estuarine outwelling. Journal of Marine Research 39:417-441. Hargrave, B.T. 1980 Factors affecting the flux of organic matter to sediments in a marine bay. In: Marine Benthic Dynamics. K.R. Tenore and B.C. Coull, editors. University of South Carolina Press, Columbia, SC. pp. 243-263. Harrison, W.G. 1978 Experimental measurements of nitrogen re- mineralization in coastal waters. Limnology and Oceanography 23:684-694. Hartwig, E.O. and S.O. Stanley 1978 Nitrogen fixation in Atlantic deep-sea and coastal sediments. Deep-Sea Research 25:411- 417. Hattori, A. 1982 The nitrogen cycle in the sea with special refer- ence to biogeochemical processes. Journal of the Oceanographical Society of Japan 38:245-265. Hauxhurst, J.D., T. Kaneko, and R.M. Atlas 1981 Characteristics of bacterial communities in the Gulf of Alaska. Microbial Ecology 7:167-182. Hauxhurst, J. D., M.I. Krichevsky, and R.M. Atlas 1980 Numerical taxonomy of bacteria from the Gulf of Alaska. Journal of General Microbiology 120:131-148. Herbert, R.A. 1975 Heterotrophic nitrogen fixation in shallow estuarine sediments. Journal of Experimental Marine Biology and Ecology 18:215-225. Hicks, D.M. 1982 Abundance and distribution of black mat syn- drome on stocks of Tanner crabs, C.luonoecetes bairdi, in the northwestern Gulf of Alaska. In: Proceedings of the International Symposium on the Genus Chionoecetes. Alaska Sea Grant Report No. 82-10, University of Alaska, Fairbanks, AK. pp. 563-579. Hodson, R.E., F. Azam, and R.F. Lee 1977 Effects of four oils on marine bacterial popula- tions: controlled ecosystem pollution experi- ment. Bulletin of Marine Science 27:119-126. Hollibaugh,J.T. 1979 Metabolic adaptation in natural bacterial pop- ulations supplemented with selected amino acids. Estuarine and Coastal Marine Science 9:215- 230. Horowitz, A., M.I. Krichevsky, and R.M. Atlas 1983 Characteristics and diversity of subarctic marine oligotrophic, stenoheterotrophic, and euryheterotrophic bacterial populations. Cana- dian Journal of Microbiology 29:527-535. Iturriaga, R. 1979 Bacterial activity related to sedimenting partic- ulate matter. Marine Biology (Berlin) 5:157-169. Jannasch, H.W. 1967 Growth of marine bacteria at limiting con- centrations of organic carbon in seawater. Lim- nology and Oceanography 12:264-271. Jannasch, H.W. and G.E.Jones 1959 Bacterial populations in sea water as deter- mined by different methods of enumeration. Limnology and Oceanography 4:128-139. Jensen, L.M. 1983 Phytoplankton release of extracellular organic carbon, molecular weight composition, and bacterial assimilation. Marine Ecology — Progress Series 11:39-48. Jones, K. 1982 Nitrogen fixation in the temperate estuarine intertidal sediments of the River Lune. Lim- nology and Oceanography 27:455-460. Kaneko T. and R.R. Colwell 1973 Ecology of Vibrio parahaemolyticus in Chesa- peake Bay. Journal of Bacteriology 113:24-32. Kaneko T. and R.R. Colwell 1974 Distribution of Vibrio parahaemolyticus and related organisms in the Atlantic Ocean off South Carolina and Georgia. Applied Micro- biology 28:1009-1017. 242 Biological Resources Kaneko, T. and R.R. Colwell 1975a Adsorption of \'ibrio parahaemolyticus onto chitin and copepods. Applied Microbiology 29:269-274. Kaneko, T. and R.R. Colwell 1975b Incidence of Vibrio parahaemolyticus in Chesapeake Bay. Applied Microbiology 30:251- 257. Kaneko, T. and R.R. Colwell 1978 The annual cycle of Vibrio parahaemolyticus in Chesapeake Bay. Microbial Ecology 4:135-155. Kaneko, T., R.M. Atlas, and M. Krichevsky 1977 Diversity of bacterial populations in the Beau- fort Sea. Nature (London) 270:596-599. Kaneko, T., M.I. Krichevsky, and R.M. Atlas 1979 Numerical taxonomy of bacteria from the Beaufort Sea. Journal of General Microbiology 110:111-125. Kaneko, T., J. Hauxhurst, M. Krichevsky, and R.M. Atlas 1978 Numerical taxonomic studies of bacteria iso- lated from Arctic and subarctic marine envi- ronments. In: Microbial Ecology. M.W. Loutit and J.A.R. Miles, editors. Springer-Verlag, New York, NY. pp. 26-30. Kaper, J.B., H. Lockman, R.R. Colwell, and S.W.Joseph 1979 Ecology, serology, and enterotoxin production of Vibrio cholerae in Chesapeake Bay. Applied and Environmental Microbiology 37:91-103. Karrick, N. 1977 Alterations in petroleum resulting from phys- io-chemical and microbiological factors. In: Effects of Petroleum on Arctic and Subarctic Marine Environments and Organisms, D.C. Malins, editor. Academic Press, New York, NY. pp. 225-299. Kemp, W.M., R.L. Wetzel, W.R. Boynton, C.F. D'Elia, andJ.C. Stevenson 1982 Nitrogen cycling and estuarine interfaces: some current concepts and research direc- tions. In: Estuarine Comparisons. Academic Press, New York, NY. pp. 209-230. Kinney, P.J., D.K. Button, and D.M. Schell 1969 Kinetics of dissipation and biodegradation of crude oil in Alaska's Cook Inlet. In: Proceedings, Joint Conference on Prevention and Control of Oil Spills. American Petroleum Institute, New York, NY. pp. 333-340. Kloos, W.E. 1982 Coagulase-negative staphylococci. Clinical Microbiology Newsletter 4:75-79. Kobori, H. and N. Taga 1974 Phosphatase activity and its role in the miner- alization of organic phosphorous in coastal sea water. Journal of Experimental Marine Biology and Ecology 36:23-39. Kriss, A.E. 1963 Marine microbiology [deep sea]. Translation byJ.M. Shewan and Z. Kabata. Oliver & Boyd, Edin- burgh, England. 536 pp. Laake, M., A.B. Dahle, and G. Hentzschel 1983 Productivity and population diversity of marine organotrophic bacteria in enclosed planktonic ecosystems. Marine Ecology — Progress Series 14:59-69. LaRoche,J. 1983 Ammonium regeneration: its contribution to phytoplankton nitrogen requirements in a eutrophic environment. Marine Biology (Berlin) 75:231-240. Larsson, U. and A. Hagstrom 1979 Phytoplankton exudate release as an energy source for the growth of pelagic bacteria. Marine Biology (Berlin) 52:199-206. Larsson, U. and A. Hagstrom 1982 Fractionated phytoplankton primary produc- tion, exudate release and bacterial production in a Baltic eutrophication gradient. Marine Biol- ogy (Berlin) 67:57-70. Lees, D.C. 1978 Reconnaissance of the intertidal and shallow subtidal biota, lower Cook Inlet. Environmental Assessment of the Alaskan Continental Shelf, Final Reports of Principal Investigators 3:179-506. Lelong, P.P., M.A. Bianchi, et Y.P. Martin 1980 Dynamique des populations planctoniques et bacteriennes au cours d'une production experimentale de phytoplancton marin naturel. II. Structure et physiologie des popula- tions et leurs interactions. Canadian Journal of Microbiology 26:297-307. Levings, CD. 1967 A comparison of the growth rates of the rock sole, Lepidopsetta bilineata Aryes, in Northeast Pacific waters. Fisheries Research Board of Canada, Technical Report No. 36. pp. 1-43. Linley, E.A.S., R.C. Newell, and M.I. Lucas 1983 Quantitative relationships between phy- toplankton, bacteria and heterotrophic micro- flagellates in shelf waters. Marine Ecology — Progress Series 12:77-89. Liston, J., W. Weibe, and R.R. Colwell 1963 Quantitative approach to the study of bacterial species. Journal of Bacteriology 85:1061-1070. Microbiology 243 Lovelace, T.E., H. Tubiash, and R.R. Cohvell 1967 Quantitative and qualitative commercial bac- terial flora of Crassostrea virginica in Chesa- peake Bay. Proceedings of the National Fisheries Association 58:82-87. McCain, B.B., WJD. Gronlund, M.S. Myers, and S.R. Wellings 1979 Tumors and microbial diseases of marine fishes in Alaskan waters. Journal of Fish Diseases 2:111-130. McCain, B.B., H.O. Hodgins, A.K. Sparks, and W.D. Gronlund 1981 Determine the frequency and pathology of marine fish diseases in the Bering Sea, Gulf of Alaska, Norton Sound, and Chukchi Sea. Environmental Assessment of the Alaskan Continen- tal Shelf, Final Reports of Principal Investigators 13:1-63. McRoy, C.P., J.J. Goering, and B. Chaney 1973 Nitrogen fixation associated with seagrasses. Limnology and Oceanography 18:998-1002. Mallory, L.M., B. Austin, and R.R. Colwell 1977 Numerical taxonomy and ecology of oligotrophic bacteria isolated from the estuarine environment. Canadian Journal of Microbiology 23:733-750. Mann, K.H. 1972 Macrophyte production and detritus food chains in coastal waters. In: Proceedings of the IBP-i'XESCO Symposium on Detritus and its Eco- logical Role in Aquatic Ecosystems, Pallanza, Italy. U. Melchiorri-Santolini andJ.W. Hopton, edi- tors. Memorie Dell'Instituto Italiano Di Idro- biologia. Vol. 29 Supplement, pp. 353-383. Marsho, T.V., R.P. Burchard, and R. Fleming 1975 Nitrogen fixation in the Rhode River estuary of Chesapeake Bav. Canadian Journal of Micro- biology 21:1348-1356. Martin, Y.P. and M.A. Bianchi 1980 Structure, diversity, and catabolic poten- tialities of aerobic heterotrophic bacterial pop- ulations associated with continuous cultures of natural marine phvtoplankton. Microbial Ecol- ogy 5:265-279. Moaledi, K. von 1978 Qualitative analysis of an oligocarbophilic aquatic microflora in the Plussee. Archiv fur Hydrobiology 82:98-113. Morita, R.Y. 1982 Starvation-survival of heterotrophs in the marine environment. Advances in Microbial Ecol- ogy 6:171-198. Naiman, R.J. andJ.R. Sibert 1979 Detritus and juvenile salmon production in the Nanaimo estuary: III. Importance of detrital carbon to the estuarine ecosystem. Journal of the Fisheries Research Board of Canada 36:504-520. Newell, R.C., J.G. Field, and C.L. Griffiths 1982 Energy balance and significance of micro- organisms in a kelp bed community. Marine Ecology — Progress Series 8:103-113. Newell, R.C., M.I. Lucas, and A.E.S. Linley 1981 Rate of degradation and efficiency of con- version of phytoplankton debris by marine micro-organisms. Marine Ecology — Progress Series 6:123-136. Nishio, T., I. Koike, and A. Hattori 1982 Denitrification, nitrate reduction, and oxygen consumption in coastal and estuarine sedi- ments. Applied and Environmental Microbiology 43:648-653. Nixon, S.W., J.R. Kelly, B.N. Furnas, C.A. Oviatt, and S.S.Hale 1980 Phosphorous regeneration and the metabo- lism of coastal marine bottom communities. In: Marine Benthic Dynamics. K.R. Tenore and B.C. Coull, editors. University of South Carolina Press, Columbia, SC. pp. 219-242. Oliver, J.D., R.A. Warner, and D.R. Cleland 1982 Distribution and ecology of Vibrio vulnificus and other lactose-fermenting marine vibrios in coastal waters of the southeastern United States. Applied Environmental Microbiology 44:1404-1414. Oshrain, R.L. and W.J. Wiebe 1979 Arylsulfatase activity in salt marsh soils. Applied and Environmental Microbiology 38:337-340. Patrick, R. 1963 The structure of diatom communities under varying ecological conditions. Annals of the New York Academy of Sciences 108:359-365. Patrick, R., M.H. Hohn, andJ.H. Wallace 1954 A new method for determining the pattern of the diatom flora. Notulae Xaturae 259:1-12. Pennington, C.L. and L.S. Cronholm 1977 The effects of urbanization on the microbial content of edible shellfish from the Gulf of Alaska. Annual Meeting of the American Soci- ety for Microbiology. American Society for Microbiology, Washington, D.C. (Abstract only.) 244 Biological Resources Pfaender, F.K. and E.N. Buckley, III 1984 Effects of hydrocarbons on microbial commu- nities. In: Petroleum Microbiology. R.M. Atlas, edi- tor. Macmillan Publishing Co., New York, NY. pp. 507-536. Pielou, E.G. 1975 Ecological Diversity. John Wiley and Sons, New York, NY. 165 pp! * Poindexter,J.S. 1979 Morphological adaptation to low nutrient con- centrations. In: Strategies of Microbial Life in Extreme Environments. M. Shilo, editor. Dahlem Konferenzen Life Sciences Research Report 13. VerlagChemie, Weinheim, West Germany, pp. 341-356. Poindexter,J.S. 1981a The caulobacters: ubiquitous unusual bacteria. Microbiology Review 45:123-179. Poindexter,J.S. 1981b Oligotrophy: fast and famine existence. Advances in Microbial Ecology 5:63-89. Pomeroy, L.R. 1974 The ocean's food web, a changing paradigm. BioScience 24:499-504. Rheinheimer, G. 1981 Investigations on the role of bacteria in the food web of the western Baltic. Kieler Meer- esforschungen, Sonderheft 5:284-290. Rhodes, M.W., I.C. Anderson, and H.I. Kator 1983 In situ development of sublethal stress in Escherichia coli: effects on enumeration. Applied and Environmental Microbiology 45:1870-1876. Rieper, M. 1976 Investigations on the relationships between algal blooms and bacterial populations in the Schlei Fjord (western Baltic Sea). Helgoldnder wissenschaftliche Meeresuntersuchungen 28:1-18. Rivkin, R.B. and E. Swift 1979 Diel and vertical patterns of alkaline phos- phatase activity in the oceanic dinoflagellate Pyrocystis noctiluca. Limnology and Oceanography 24:107-116. Robertson, B.R., S.D. Arhelger, R.A.T. Law, and D.K. Button 1973 Hydrocarbon biodegradation. In: Environmen- tal Studies of Port Valdez. D.W. Hood, W.E. Shiels, and E.J. Kelley, editors. Occasional Publication No. 3, Institute of Marine Science, University of Alaska, Fairbanks, AK. pp. 449-479. Robertson, B., S. Arhelger, P.J. Kinney, and D.K. Button 1973 Hydrocarbon biodegradation in Alaskan waters. In: The Microbial Degradation of Oil Pollu- tants. D.G. Ahearn and S.P. Meyers, editors. Publication No. LSU-SG-73-01, Center for Wetland Resources, Louisiana State Univer- sity, Baton Rouge, LA. pp. 171-184. Roubal, G. and R.M. Atlas 1978 Distribution of hydrocarbon-utilizing micro- organisms and hydrocarbon biodegradation potentials in Alaskan continental shelf areas. Applied and Environmental Microbiology 35:897- 905. Roubal, G. and R.M. Atlas 1979 Hydrocarbon biodegradation in Cook Inlet, Alaska. In: Developments in Industrial Microbiology, Vol. 20. Society for Industrial Microbiology, Arlington, VA. pp. 497-502. Saunders, G. W. and T.A. Storch 1971 Coupled oscillatory control mechanism in a planktonic system. Nature (London) 230:58-60. Schell, D.M. 1974 Uptake and regeneration of free amino acids in marine waters of southeast Alaska. Limnology and Oceanography 19:260-270. Seitzinger, S.P., S.W. Nixon, and M.E.Q. Pilson 1984 Denitrification and nitrous oxide production in a coastal marine ecosystem. Limnology and Oceanography 29:73-83. Sharp, J.H. and T.M. Church 1981 Biochemical modeling in coastal waters of the middle Atlantic states. Limnology and Oceanogra- phy 26:843-854. Sibert, J.R. and R.J. Naiman 1980 The role of detritus and the nature of estuarine ecosystems. In: Marine Benthic Dynamics. KJ. Tenore and B.C. Coull, editors. University of South Carolina Press, Columbia, SO pp. 311-323. Sibert, J., TJ. Brown, M.C. Healey, B.A. Kask, and R.J. Naiman 1977 Detritus-based food webs: exploitation byjuve- nile chum salmon (Oncorhynchus keta). Science 196:649-650. Simidu, U., E. Kaneko, and N. Taga 1977 Microbiological studies of Tokyo Bay. Microbial Ecology 3:173-191. Sizemore, R.K., R.R. Colwell, H.S. Tubiash, and T.E. Lovelace 1975 Bacterial flora of the hemolymph of the blue crab, Callinectes sapidus: numerical taxonomy. Applied Microbiology 29:393-399. Microbiology 245 Smith, W.O., Jr., R.T. Barber, and S.A. Huntsman 1977 Primary production off the coast of northwest Africa: excretion of dissolved organic matter and its heterotrophic uptake. Deep-Sea Research 24:35-47. Sneath, P.H.A. and R.R. Sokal 1973 Numerical taxonomy: The Principles and Practice of Numerical Classification. W.H. Freeman and Co., San Francisco , CA. 573 pp. Sparks, A.K. 1982 The histopathology and possible role in the population dynamics of Tanner crab, Chionoecetes bairdi, of the fungus disease (black mat syndrome) caused by Trichomaris invadens. In: Proceedings of the International Symposium on the Genus Chionoecetes. Alaska Sea Grant Report No. 82-10, University of Alaska, Fair- banks, AK. pp. 539-545. Sparks, A.K. andj. Hibbits 1979 Black mat syndrome, an invasive mycotic dis- ease of the Tanner crab, Chionoecetes bairdi. Jour- nal of Invertebrate Pathology 34:184-191. Stevenson, L.H. and C.W. Erkenbrecher 1976 Activity of bacteria in the estuarine environ- ment. In: Estuarine Processes, Vol. 1. M. Wiley, editor. Academic Press, New York, NY. pp. 381-394. Stich, H.F., A.B. Acton, K. Oishi, F. Yamazaki, T. Harada, and H.G. Moser 1977 Systematic collaborative studies on neoplasms in marine animals as related to the environ- ment. Annals of the New York Academy of Sciences 298:374-388. Stich, H.F., A.B. Acton, B.P. Dunn, K. Oishi, F. Yamazaki, T. Harada, G. Peters, and N. Peters 1977 Geographic variations in tumor prevalence among marine fish populations. International Journal of Cancer 20:780-791. Stuart, V., R.C. Newell, and M.I. Lucas 1982 Conversion of kelp debris and faecal material from the mussel Aulacomya ater by marine microorganisms. Marine Ecology — Progress Series 7:47-57. Teal, J.M., I. Valiela, and D. Berlo 1979 Nitrogen fixation by rhizosphere and free- living bacteria in salt marsh sediments. Lim- nology and Oceanography 24:126-132. Tison, D.L., M. Nishibuchi, J.D. Greenwood, and RJ. Seidler 1982 Vibrio vulnificus biogroup 2: new biogroup pathogenic for eels. Applied and Environmental Microbiology 44:640-646. Torella, F. and R.Y. Morita 1981 Microcultural study of bacterial size changes, and microcolony and ultramicrocolony forma- tion by heterotrophic bacteria in seawater. Applied and Environmental Microbiology 41:518-527. Tubiash, H.S., R.K. Sizemore, and R.R. Colwell 1975 Bacterial flora of the hemolymph of the blue crab, Callinectes sapidus: most probable number. Applied Microbiology 29:388-392. Valde's, M. and L.J. Albright 1981 Survival and heterotrophic activities of Fraser River and Strait of Georgia bacterioplankton within the Fraser River plume. Marine Biology (Berlin) 64:231-241. Vasconcelos, G.J., W.J. Stang, and R.H. Laidlaw 1975 Isolation of Vibrio parahaemolyticus and Vibrio alginolyticus from estuarine areas of south- eastern Alaska. Applied Microbiology 29:557-559. Vestal, J.R., J.J. Cooney, S. Crow, and J. Berger 1984 Effects of hydrocarbons on microorganisms. In: Petroleum Microbiology. R.M. Atlas, editor. Macmillan Publishing Co., New York, NY. pp. 475-506. Wassmann, P. 1983 Sedimentation of organic and inorganic partic- ulate material in Lindaspollene, a stratified, land-locked fjord in western Norway. Marine Ecology— Progress Series 13:237-248. Wetzel, R.G., P.H. Rich, M.C. Miller, and H.L. Allen 1972 Metabolism of dissolved and particulate detrital carbon in a temperate hard-water lake. In: Proceedings of the IBP-UNESCO Symposium on Detritus and its Ecological Role in Aquatic Eco- systems, Pallanza, Italy. U. Melchiorri-Santolini and J.W. Hopton, editors. Memorie Dell'Instituto Italiano Di Idrobiologia. Vol. 29 Supplement, pp. 185-243. Wood, EJ.F. 1965 Marine Microbial Ecology. Rheinhold Publishing Corp., New York, NY. 243 pp. Wood, EJ.F. 1967 Microbiology of Oceans and Estuaries. Elsevier Pub- lishing Co., Amsterdam. 319 pp. Wright, R.T. and R.B. Coffin 1983 Planktonic bacteria in estuaries and coastal waters of northern Massachusetts: spatial and temporal distribution. Marine Ecology — Progress Series 11:205-216. 246 Biological Resources Yingst, J.Y. and D.C. Rhoads 1980 The role of bioturbation in the enhancement of bacterial growth rates in marine sediments. In: Marine Benthic Dynamics. K..R. Tenore and B.C. Coull, editors. University of South Car- olina Press, Columbia, SC. pp. 407-421. Zeitzschel, B. 1980 Sediment-water interactions in nutrient dynamics. In: Marine Benthic Dynamics. K.R. Ten- ore and B.C. Coull, editors. University of South Carolina Press, Columbia, SC. pp. 195-218. ZoBell, C.E. 1946 Marine Microbiology: A Monograph on Hydrobac- tenology. Chronica Botanica Co., Waltham, MA. 240 pp. ZoBell, C.E. and H.C. Upham 1944 A list of marine bacteria including description of sixty new species. Bulletin of the Scripps Institu- tion of Oceanography (Technical Series) 5:239-292. Zuberer, D.A. and W.S. Silver 1978 Biological dinitrogen fixation (acetylene reduction) associated with Florida mangroves. Applied and Environmental Microbiology 35:567- 575. Phytoplankton and Primary Production Raymond N. Sambrotto Ocean Sciences Division National Science Foundation Washington, D.C. Carl J. Lorenzen School of Oceanography University of Washington Seattle, Washington Abstract Changes in both the amount of daily light and in the depth of mixing initiate a predictable, positive response in phytoplankton productivity throughout the sub- arctic Gulf of Alaska during the spring. In the oceanic regions, however, this produc- tivity increase is not accompanied by a commensurate increase in the phytoplankton standing crop. Chlorophyll a levels in this region usually do not exceed 1 mg/m3, diatom cells are not especially numerous, and the phytoplankton community is numerically dominated by microflagellates. The discrepancy between increased pro- ductivity and the size of the standing crop is generally attributed to the rapid rate with which phytoplankton cells are removed from the surface water by endemic North Pacific macrozooplankton. Recent measurements suggest that in addition to the macrozooplankton's influ- ence, grazing by microzooplankton coupled with the number of phytoplankton cells that sink are also important loss factors. Seasonal 14C productivity measurements at Ocean Station 'P' (50°N, 145°W) vary from winter values that are generally less than 50 mg C/m2d to summer values that range between 200 and 400 mg C/m2d and sug- gest annual productivity of —50 g C/m2. However, a mass balance of phytoplankton nutrient consumption indicates that the yearly production may actually exceed 100 g C/m2 for the Central Subarctic Domain. The Gulf of Alaska shelf is extremely productive and in the areas near Adak Island, lower Cook Inlet, and the Kenai shelf, annual production is ~ 300 g C/m2. Production in these areas may be associated with upwelling that is induced by both coastal and near-shelf water movements. Such productivity suggests that previous estimates of the Gulfs productivity may need to be adjusted upward. Coastal areas are environmentally heterogeneous, and measurements suggest that the annual production in the various embayments ranges from 140 to over 200 g C/m2. Large standing crops of phytoplankton build up near the shore. Dense chlorophyll a concentrations usually appear briefly in surface waters, although subsurface chlo- rophyll a layers may persist throughout the summer. Introduction ^ne earnest comprehensive coastal studies began both in Cook Inlet (Hood, Natarajan, Rosenberg, and Wallen 1968) For the purpose of our discussion, we have separated the and in Prince William Sound (Goering, Shiels, and Patton oceanic regions from both the coastal and the shelf waters in 1973). However, the Alexander Archipelago of the southeast the Gulf at the shelf break (roughly the 200-m isobath in Fig. Gulf, Yakutat Bay, Kodiak Island, and the large estuary 9-1). The coastal area stretches from the Queen Charlotte formed by the Copper River are also an important part of Islands in the east to 176°W in the Aleutian Islands. the extremely long and physiographically diverse coast. 249 250 Biological Resources 165 160 155 150 145 140 135 :}*/■ I 1 r?7 y* m~&yJ i >$L J0rW0%7?0^ XvX\\\\\"XvX-XvX\\" Gulf YLof^ Alaska ^*L*-.*~>>'\>>-^Af / rSx: Oct.- 1 \ ^-~>y> \jr oA ^yyy 60 \ A Alaskan Stream Domain Fx-l Alaskan Gvir k^d Central Subarctic Domain Gulf of Alaska study area 55 Bering Sea ,0yy200mm |0»/ ~y y^y*"*^ 50 60 165 160 155 Figure 9-1. Overview of the Gulf of Alaska that indicates the 200-m isobath and selected coastal features. Superimposed on the figure are surface-water domains delineated by Dodimead^a/. (1963) on the basis of measurements of temperature, salinity, and oxygen. This means that phytoplankton studies done in the coastal areas of the Gulf have generally been more scattered than those conducted in the oceanic area. The width of the Gulfs continental shelf varies greatly — from less than 15 km off Southeast Alaska to over 100 km south of Cook Inlet and on the Kodiak and Aleutian shelves (Fig. 9-1). Historically, phytoplankton and primary produc- tion on the Gulfs continental shelf have received little atten- tion. However, information on the phytoplankton of the central Gulf shelf was significantly expanded during the United States Department of the Interior's Outer Continen- tal Shelf Environmental Assessment Program (OCSEAP) (Larrance, Tennant, Chester, and Ruffio 1977). Limited measurements for phytoplankton occurrence and growth in the oceanic region of the Gulf began in the late 1950s (McAllister, Parsons, and Strickland 1960; Holmes 1958). North American workers collected more extensive data in this area during the subsequent two decades (Ander- son, Parsons, and Stevens 1969; Parsons and LeBrasseur 1967; Parsons and Anderson 1970; and Larrance 1971 a, b). The work by the North Americans has been supple- mented not only by a substantial body of information col- lected during Japanese cruises (Faculty of Fisheries, Hok- kaido University 1960-1983; Takahashi, Satake, and Nakamoto 1972) but also from ships that traversed the area during Pacific crossings (Anderson and Munson 1972). In addition to information from these sources, we have also included data from the Canadian Ocean Weather Station P (50°N, 145°W) in our discussion. Although it is south of the current Gulf of Alaska definitional boundary (52°N), Sta- tion P has been the site of many process-oriented produc- tion studies relevant to the oceanic Gulf area. Therefore, these results are included in our discussion. Generally, phytoplankton studies in the Gulf of Alaska focus on the analyses of two major processes: 1) the produc- tivity of commercially important food chains (OCSEAP Staff, Ch. 14, this volume) and, increasingly, 2) the associa- tion of phytoplankton growth with the vertical flux of mate- rial from the ocean's surface layers (Eppley and Peterson 1979). Each of these two processes ultimately depends on both the physical and the biological influences that govern phytoplankton growth in a particular area. Generally, these influences include several semi-independent factors such as the interaction of light and mixing processes (Sverdrup 1953), nutrient limitation (Dugdale 1967), and herbivore grazing (Steele and Frost 1977). In the Gulf of Alaska, situations have been found in which each one of these influences dominates the local phy- toplankton growth. In our review of the literature concern- ing phytoplankton and phytoplankton growth, we have pre- sented the material in the context of these environmental influences whenever possible. Methods Phytoplankton identification and cell counts for the Gulf have usually been made using samples of preserved sea- water. A set volume (typically 50 or 100 ml) of seawater was often collected and then preserved with Lugol's solution (Rodhe, Vollenweider, and Nauwerick 1958). While this preservation technique works well for diatoms, the acetic acid component of the preservative may destroy calcareous Phytopiankton and Primary Production 251 material such as coccolithophorids (Hobro and Wilier) 1977). Conversely, preservation using a formalin solution damages naked flagellates (Hasle 1959). The most reliable analysis of delicate small phytopiankton forms (<20-um cells) in the Gulf employed glutai aldehyde as a preservative and avoided the mechanical damage caused by direct filtra- tion (Booth, Lewin, and Norris 1982). However, even with these refined techniques, some loss of the naked cell forms takes place. This means that both the preservation and the sample-handling techniques that are used to identify and enumerate phytopiankton have a direct effect on the results. In most studies, the cell counts were usually done using the inverted microscope method developed by Utermohl (1931). Diatom identification in most studies was based on Cupp (1943). The use of scanning electron microscopes (SEM) on phytopiankton samples allowed researchers to identify species based on previously ignored features (Booth ei al. 1982). Humm and Wicks (1980) has been used as a guide to the bluegreen algae. Cell measurements and geo- metric formulae were used to estimate plasma volumes (Lar- rance 1964) from which cell carbon could be estimated for individual species (Strathmann 1967). Most primary production measurements have involved modification of the ' *C-uptake tracer method developed by Steemann Nielsen (1952). Typically, water from several depths throughout the euphotic zone (the depth at which 99% of the available sunlight is absorbed) was first collected and then incubated with 14C-labeled sodium bicarbonate (e.g., Parsons and Anderson 1970). Although some incuba- tions took place under artificial light (Faculty of Fisheries, Hokkaido University 1960), most carbon productivity esti- mates were based upon on-deck simulations of in situ light conditions. In addition to the interpretive problems posed bv the llC technique itself (Peterson 1980), incubation peri- ods varied according to who conducted the tests. Therefore, estimates for daily primary production were often extrapo- lated from shorter incubation periods and were based on the relative amount of davlight received. Two studies conducted in the Gulf have used 15N as a tracer for phytopiankton nitrogen uptake (Goering, Shiels, and Patton 1973; Hattori and Wada 1972). The 15N tracer technique is an alternative to the carbon method for meas- uring marine production. In addition, it has the added capability of distinguishing between 'new' production (fueled by nitrate uptake) and regenerated production (fueled largely by ammonium uptake) (Dugdale and Goer- ing 1967). Phytopiankton production in the Gulf can also be estimated from a mass balance of the dissolved inorganic nutrients. This method can be used as an alternative to tracer methods or can be used to cross-check results. As phytopiankton grow, they consume carbon, nitrogen, and phosphorus in predictable proportions (Redfield, Ket- chum, and Richards 1963). In theory, therefore, carbon pro- duction can be estimated from the measured consumption of carbon, nitrogen, or phosphorus. Seawater nitrate is a phytopiankton nitrogen source that has been extensively measured in the ocean (Reeburgh and Kipphut, Ch. 4, this volume), and which can be used as a basis for estimating carbon production. The methodology involved is strictly chemical in nature. (Details on the spe- cific methods used are found in Parsons, Maita, and Lalli [1984].) Both the amount of total carbon dioxide and the par- tial pressure of surface-water carbon dioxide are sensitive indicators of phytopiankton photosynthesis (Kelley, Long- erich, and Hood 1971; I lood and Codispoti 1984). The most widely used index of phytopiankton biomass in the Gulf — as in other marine areas — has been the measure- ment of the photosynthetic pigment chlorophyll a. Typ- ically, this involves the extraction of the pigment into an organic solvent and its detection either by spectrophotome- try (e.g., Anderson 1969) or by fluorometry (Yentsch and Menzel 1963). A similar technique has been used to measure chlorophyll degradation products found in seawater. These products are formed mainly as a result of the activities of herbivorous grazers (Shuman and Lorenzen 1975). The par- ticulate material from this activity falls through the water column and can be captured in sediment traps suspended at depth. These sediment traps have been used to measure par- ticulate flux in the Gulf of Alaska (Larrance, Chester, and Milburn 1979). The amount of phytopiankton removed from surface waters has been estimated by a combination of these various methods. Using a pigment budget, phytopiankton losses can be partitioned among three causes: 1) microzooplankton grazing (suspended degradation products), 2) mac- rozooplankton grazing (degradation products from sedi- ment traps), and 3) phytopiankton sinking (chlorophyll a losses). The methodology is introduced here because we will present some preliminary results from Station P that are based on this technique. A more complete description of the methodologies and rationales used in this approach can be found in Welschmeyer and Lorenzen (1985). Other measurements that are important to phyto- piankton studies in the Gulf are surface-water mixing and light measurements. Most often, the amount of sur- face-water mixing has been determined by the depth of the mixed layer (the depth to the top of the major thermocline) (Giovondo and Robinson 1965). Incident solar radiation was often measured with a shipboard pyranometer, while an underwater quanta sensor was used in some cases to meas- ure the extinction coefficient of light in the surface water. In most cases, however, a Secchi disk was used to estimate light extinction coefficients. An approximate conversion between the Secchi disk depth (Zm) and the extinction coefficient (kc) can be obtained from the following rela- tionship (Walker 1980): k. = 1.45/Zr (1) Oceanic Gulf of Alaska We will first consider studies that have been done in oceanic areas. Table 9-1 lists the background data as reviewed by Anderson, Lam, Booth, and Glass (1977), together with more recent cruise listings for the oceanic Gulf. Broad geographic divisions of the subarctic Pacific domain were defined by Dodimead, Favorite, and Hirano (1963) (Fig. 9-1). The three areas indicated in Figure 9-1 are not water masses per se, but reflect the prevailing circulation 252 Biological Resources Table 9-1. Background biologic and oceanographic data collected in the oceanic Gulf of Alaska. The list is taken largely from Anderson et al. (1977) and has been modified and updated. Ol'ERA HON Period ZONES3 Data Type6 Source Weather Station P Cruises 593 to 614 Cruises 615 to 634 Cruises 635 to 655 Cruises 661 to 674 Cruises 681 to 706 Ships of Opportunity Cruises 02 to 43 1958 H.M. Smith 46 Vityaz 29 1959 Oshoro Maru 44 Brown Bear 235 1960 Oshoro Maru 46 1961 Oshawa 1961 Pioneer 66 1964 G.B. Reed \64 Agassiz Ursa Major 1966 Argo Zetes I Kelez 166 Paragon 266 Kelez 366 1967 Kelez 167 T.G. Thompson 12 Kelez 367 Kelez 667 Kelez 767 1968 Kelez 268 Oshoro Maru 28 1969 Endeavour (trans-Pacific) Vityaz 45 Hakuho Maru 694 1970 Hakuho Maru 702 Oshoro Maru 37 1959 to 1961 1961 to 1963 1964 to 1966 1966 to 1967 1968 to 1970 1968 to 1972 August-September October-December June July-August June-August June September-October January-February August-September January March June September January-February February-March April July August May June-July March-April May-June August May June-July 33 33 33 33 33 15,19, 22-32,34, 36 24,25,29, 30,31 19-21,24, 27,29,30, 35 22,25,29 15,19,23, 24,27,28, 34,36 18,19,22- 24,29-31, 35 19,33,36 22,23,26, 29,30 19,21,24, 27,28,31- 36 16,24,27,31 16,24,27,31 22,25,29 22,25,29 20,22,29-31 23,26,30 17-19,24, 27,28,34-36 19,36 22 22,25,29 23,26,30 17,18,22 20,29-31 17,18,23,35 31 1,3,6,9 McAllister 1962 1,3,6,9 Stephens 1964 1,3,6,7,9 Stephens 1966 1,3,6,7,9 Stephens 1968 1,3,6,7,9 Stephens 1970 1,3,5,7,8,9 G.C. Anderson, 1,3,6 3,7,9 6 1,6 5,6 1,6,7 1,3 1,5,6 1,2,5,6,7 1,3,8,9 1,3,8,9 1,3,7,8,9 1,3,7,8,9 1,3,6,7 1,8 1,3,7,8,9 1,3,7,8,9 1,8 6 1,3,7,8,9 1,3 1,5 Washington, unpubl. data McGary and Graham 1960 Koblentz-Mishke 1969 Faculty of Fisheries, Hokkaido University 1960 Stephens 1964 Faculty of Fisheries, Hokkaido University 1961; Motoda and Kawamura 1963 Antia et al. 1962 Doty 1964 Stephens 1964 University of California 1967; Venrick 1971 University of California 1970; Venrick 1969 Larrance 1971b Larrance 1971b Larrance 1971b Larrance 1971b G.C. Anderson, University of Washington, unpubl. data Larrance 1971b Larrance 1971b Larrance 1971b Larrance 1971b Faculty of Fisheries, Hokkaido University 1969 Anon. 1970 Anon. 1973 Takahashi el al. 1972; T. Asaoka, University of Tokyo, unpubl. data 19,34 6,7 Horibe 1971 16,17,18, 1,6 Faculty of Fisheries, 22-24,27, Hokkaido University 1972 31,33,34 Pi iytoplankton and Primary Production 253 Opera noN Period /.ONI S' Data TvPEb Si II kl I 1971 T.G. Thompson 59 May-June 1972 T.G. Thompson 72 September 1973 T.G. Thompson 82 August 1974 Hakuho Maru 742 May T.G. Thompson 9 1 July 1975 Discoverer (OCSEAP- October RP4-DI-75CLegI) 1976 Discoverer (OCSEAP- April RP4-DI-76ALegIII) Discoverer (OCSEAP- May RP4-DI-76ALegV&VH) Acona (OCSEAP- July RP4-AC-76LegII). Surveyor (OCSEAP- August RP4-SU-76BLegII) 1978 July-August 1980 Oshoro Maru 80 July 1981 Oshoro Maru 85 July 1982 Oshoro Main 90 W'ecoma July July-August 22,23,25, 1,6,7 G.C. Anderson, Universitv.ol 26,27 Washington, unpubl. data 24,27,31 1,2,3,6,7,9 G.C. Anderson, University of Washington, unpubl. data 33 1,2,3,6,7,9 G.C. Anderson, University of Washington, unpubl. data 29 1,6,7 Kuroki 1975 36 1,2 G.C. Anderson, University of Washington, unpubl. data 17 1,2,3,5,7,9 Larrance el al. 1977 16,17 1,2,3,5,7,9 Larrance et al. 1977 16,17 1,2,3,5,7,9 Larrance et al. 1977 16,17 1,2,3,5,7,9 Larrance et al. 1 977 16,17 1,2,3,5,7,9 Larrance et al. 1977 18,28,35 5 Boothia/. 1982 33,34,35 6,7 Faculty of Fisheries, 33,34,35 27,28,35 33 Hokkaido University 1981 4,6,7 Faculty of Fisheries, Hokkaido University 1982; J.J. Goering, University of Alaska, unpubl. data 1,2,4,6,7,9 Faculty of Fisheries, Hokkaido University 1983; R.A. Sambrotto and J.J. Goering University of Alaska, unpubl. data 1,2,3,8,9 Lorenzen 1984a, b, unpubl. data a The zones correspond to the geographic areas labeled in Figure 9-9. b Data type codes indicate the following parameters were measured: 1 = chlorophyll a, 2 = phaeopigments, 3 = primary productivity (carbon). 4 = primary productivity (nitrogen). 5 = phvtoplankton species, 6 = oxygen, 7 = nitrate, 8 = mixed-layer depth, 9 = total incident radiation. and weather patterns in the Gulf. For example, the Central Subarctic Domain is largely the path of the Subarctic Cur- rent as it turns north to form the Alaska Current. Although the Alaska Current is not properly called the Alaskan Stream until west of Kodiak Island (Reed and Schumacher, Ch. 3, this volume), the entire near-shelf circulation in Fig- ure 9-1 is labeled Alaskan Stream Domain. Precipitation exceeds evaporation in the Gulf of Alaska, and this maintains the surface salinity at less than 34 parts per thousand. This relatively fresh water results in a perma- nent halocline at ~ 100 to 120 m that limits winter convective circulation to relatively shallow depths, compared with the winter mixing depths in the North Atlantic. Relevance of Ocean Station P Data Available oceanographic data from the Gulf of Alaska are not evenly distributed, and by far the greatest number of measurements have been taken at Station P (Anderson et al. 1977). These measurements form the most reliable time series to use when addressing the seasonal variation and associated environmental influences on oceanic phv- toplankton near the Gulf. Like the rest of the Gulf, Station P is north of the subarctic boundary and, consistent with the domains specified by Dodimead et al. (1963) (Fig. 9-1), is also under the influence of the North Pacific Current. This means that at Station P properties are probably represen- tative of those found farther north as this flow continues in 254 Biological Resources the form of the Central Subarctic Domain. Therefore, the results of phytoplankton studies at Station P are generally relevant to large areas of the eastern oceanic Gulf of Alaska. Another factor that suggests a relative homogeneity for phytoplankton growth in the Gulf is the siliceous ooze that dominates the sediments of the entire area (Lisitzin 1971). The diatom composition in the surface sediments coincides closely with the composition in the overlying water masses, and the sediments reflect the boundary between subarctic and transitional water (Kanaya and Koizumi 1966). Local diatom growth is ultimately responsible for the sediment patterns, although the biological factors that are involved are poorly known. For example, it is not clear how dif- ferences in the composition of local phytoplankton commu- nities, differences in growth rates, and the various vertical-transport mechanisms such as the grazing and sink- ing bring about such sediment patterns. Although a quan- titative answer to this question for the Gulf is not possible, the question serves as a useful framework for our discussion of oceanic phytoplankton. Seasonal Pattern of Phytoplankton Growth at Ocean Station P Anderson et al. (1977) compiled measurements from Sta- tion P that summarized the average seasonal changes in chlorophyll a (Fig. 9-2) and nitrate (Fig. 9-3) based on data collected from 1959 through 1970. The average chlorophyll a data (Fig. 9-2) indicate that the phytoplankton standing crop at Station P typically increases from winter values of — 0.2 M.g/1 to maximum summer values of less than 0.5 pg/1. From March to September, nitrate concentrations in sur- face waters decrease steadily from over 15 pM/l to less than 7 |lM/l, reflecting the seasonally changing supply and con- sumption of this important phytoplankton nutrient. Nitrate is brought to the surface as a result of the vertical mixing of the deeper, nutrient-rich water throughout the a 60 Figure 9-2. Average changes in chlorophyll a concentration (mg/m3) according to both time and depth at Station P (50°N, 145° W). This is a composite from several sources. (Modified from Anderson et al. 1977.) Figure 9-3. Average changes in nitrate concentration (|iM/l) according to both time and depth at Station P. This is a composite from several sources. (Modified from Anderson et al. 1977.) year. The mixing rate is greater during winter when vertical mixing is at its most vigorous. Conversely, the consumption of nitrate during phytoplankton growth is greatest in the summer months. These two processes result in the observed winter nitrate maximum and summer minimum in surface waters at Station P. Although nitrate levels are reduced in the summer, the average concentrations are still larger than the minimum levels that are required for phytoplankton growth ( > 1 p.M/1) (Dugdale 1967; Hattori and Wada 1972). Other plant nutrients such as phosphorus (in the form of phosphate) are also plentiful during the summer, and therefore a lack of nutrients does not appear to be the factor that prevents greater amounts of plant biomass from accumulating in sur- face waters. The seasonally consistent level of the phytoplankton standing crop at Station P is very similar to the uniformly low levels found in the high latitude southern ocean (El Sayed 1978). However, the relatively small vernal phy- toplankton increase in the Gulf is very different from the sit- uation found at comparable latitudes in the North Atlantic, where a much more dramatic increase in phytoplankton occurs during spring. Also, no pronounced subsurface chlo- rophyll a layers are found in the North Atlantic. Such layers appear to be a common feature in lower latitude waters of the North Pacific (Anderson 1969). The consistency in the Station P phytoplankton biomass is striking, but not absolute. A weak seasonal signal in chlo- rophyll a can be observed at Station P (Fig. 9-2). Also, Anderson et al. (1977) presented the averaged chlorophyll a data for individual seasons (Fig. 9-4) and showed that in cer- tain periods {e.g., the summers of 1964 and 1965) greater than mean chlorophyll a levels were present. Also, the standard deviations of the means appear to increase with the sample size. This suggests that the actual chlorophyll a levels are not normally distributed around a constant value and that the mean values actually mask episodic departures from typical conditions. Pi iytoplankton and Primary Production 255 Win iiks 10 08 06 04 02 I'll Sl'RINC.S 10 08 06 04 02 I I I I I -i 1 1 1 1 1 1 r Si MMERS 1 u 08 ■ i 06 04 0 2 0 I 1 1 ♦ 1 \ 1 Mi Autumns 10 08 0.6 0.4 02 0 195H 1964 1968 1970 1972 Figure 9-4. Mean seasonal concentrations of chlorophyll a found at Station P (±1 SD) from 1959 to 1973. This is a composite from several sources. (Modified from Anderson etal. 1977.) Unlike chlorophyll a levels, the rates of primary produc- tion at Station P increase significantly in spring and summer (Fig. 9-5). The seasonal increase in the amount of daily light certainly contributes to this increase. However, Parsons, Giovondo, and LeBrasseur (1966) have shown that the trig- gering mechanism for increased spring productivity is actu- ally made up of more than this one variable. These authors applied a production model based on the critical depth (Zcr) as defined by Sverdrup (1953): I k/I. (2) The critical depth formula expresses a depth in meters that can be compared directly to the mixed layer depth (MLZ). Importantly, in addition to incident light (Ic), the critical depth model considers the light intensity needed for net photosynthesis (the compensation light intensity, It) and the light extinction coefficient of the surface water (kt). The changes in Zcr relative to the mixed layer depth indicated 400 E rt 300 u bo E C 200 a c Cu 183 Days 305 365 Figure 9-5. Seasonal changes in vertically integrated (0-50 m) primary production measured by the 14C method at Station P. These are several years' worth of combined data. (Modified from Anderson et al. 1977.) that suitable conditions for phytoplankton growth (low MLZ:Zcr ratios) first occurred at Station P in May (Fig. 9-6). t During May, the mixed layer rises abruptly from its winter depth at the permanent halocline. These physical changes in upper water column properties coincide with increases in the local production rate (Fig. 9-5). The exact timing of when the spring mixed layer rises and phy- toplankton productivity begins to increase varies from year to year, and this variation may then influence zooplankton growth (Parsons and LeBrasseur 1969). Phytoplankton growth conditions remain favorable throughout the summer because the mixed layer usually remains within the euphotic zone at — 50 m during this sea- son. Carbon productivity rates on the order of 200 to 400 mg C/m2d are typical during the summer months. These rates are maintained until fall when vertical stability becomes T T 25 50 I , T 1 1 1 X X T 1 X .] 1 75 T 1 X T £.100 T T 1 1 T ' t I J. I 125- H - U Q 150- L i 175 200 225 250 1 1 Jan Feb Mar Apr May Ji-n |i i VUG SEP o< i Nov Dm Figure 9-6. Comparison of the seasonal changes in both the critical depth and the mixing depth at Station P. Solid lines indicate the ranges of the critical depth (Equation 2, see text). Broken lines indicate the mean mixed-layer depth (±1 SD). (Modified from Parsons et al. 1966.) 256 Biological Resources weakened due to surface cooling and the increased fre- quency of storms. Eventually, the seasonal thermocline is destroyed and the surface waters are again well mixed down to depths of 100 to 150 meters. Winter productivity levels are typically less than 50 mgC/m2d. Loss Processes Affecting Oceanic Phytoplankton The difference between seasonally variable algal produc- tivity and seasonally consistent biomass presents somewhat of an enigma in the Gulf of Alaska. This discrepancy has been attributed to the intense grazing of algal cells by zoo- plankton (McAllister, Parsons, and Strickland 1960). This manner of phytoplankton population control is different from the situation in many other ocean areas and was first suggested by Heinrich (1975). The grazers that are thought to be the most influential in this control are two large, her- bivorous calanoid copepods endemic to the subarctic Pacific: Neocalanus plumchrus and N. cristatus. The last larval stage of these two species overwinters at depth, during which time the adults both develop and reproduce without any additional food supplies. The young arrive at the surface in the spring where they can feed on the phytoplankton at approximately the same time that the plant community begins its accelerated growth. In this sce- nario, any increase in the biomass due to growth is grazed by the resident zooplankton population. As a result, a constant phytoplankton population is maintained. Recently, the hypothesis that the large herbivores con- trolled the phytoplankton population at Station P was quan- titatively tested. This test entailed using a plant pigment budget to calculate both algal growth rates and herbivore grazing rates (Welschmeyer and Lorenzen 1985). Sediment traps were used to catch particles that sank from the surface water. These samples were then used for pigment analyses. Herbivore grazing rates can be partitioned, in a functional sense, into 1) grazing that is attributable to macrozoo- plankton and that produces consolidated fecal pellets or 2) grazing by microzooplankton that produces non-consol- idated material. Microzooplankton grazing residue does not sink and therefore is sampled with water bottles. In May and August 1983, a series of seven successful experiments designed to partition grazing losses between macro- and micrograzers was carried out (Lorenzen 1984a, b, unpubl. data). The results indicated that the average chlo- rophyll a specific growth rate for the phytoplankton com- munity was 0.13/d. The phytoplankton standing crop did not change during the observation period, and therefore the growth rate could be partitioned among those loss processes that affected the phytoplankton. The three major algal loss rates were: 1) 0.076/d from microzooplankton grazing (56% ), 2) 0.046/d from macrozooplankton grazing (35%), and 3) 0.010/d from cells that sank (7%). Clearly, the mac- rozooplankton were not the dominant grazers during this period. Over half the estimated phytoplankton loss was attributed to grazing by microzooplankton. Even though the partitioning experiments established the role of the macro- and microzooplankton in phyto- plankton loss, no previous analysis of phytoplankton graz- ing losses has addressed the role of megazooplankton such as salps, which are known to be episodically abundant in the Gulf (Iseki 1981). These tunicates can remove phytoplankton smaller than 4 [im from surface waters (Harbison and McAlister 1979). The size distribution of Gulf phyto- plankton may be strongly influenced by grazing conditions (Parsons 1972). Also, the results of some recent sediment- trap studies at Station P suggest that phytoplankton cell sinking is a much more important loss process than pre- viously thought. For example, large amounts of opal (silica) were collected in deep traps throughout the year in the form of ungrazed phytoplankton diatom frustules (K. Takahashi, Woods Hole Oceanographic Institution, pers. comm.). Only a two-week delay separated the peaks in diatom biomass collected from traps at 1,000- and 3,800-m depths. This delay equals a sinking rate of 180 m/d. Solitary diatom cells sink much more slowly than this (Bienfang 1984), and these rapid rates suggest that diatoms might sink as aggregated particles. Ungrazed phytoplankton cells that sink from the surface therefore may account for a significant portion of the phytoplankton loss in the oceanic Gulf of Alaska. Large-Scale Features of Phytoplankton Growth A number of measurements that pertain to oceanic phy- toplankton have been collected from American Mail Line (AML) ships that traverse the southern Gulf (Anderson and Munson 1972). These cruise tracks provided zonal coverage of both the central subarctic and the Alaskan Gyre waters from late winter through summer of the years 1968 to 1972 (between 50 and 55°N). The zonal distribution of several rel- evant parameters that were measured by the AML ships is shown in Figure 9-7. The sections that were examined extend beyond the Gulf (west of 176°W and east of 135° W). Both the Kuroshio water (in the west) and the water closer to the North American continent (in the east) exhibit consis- tently warmer temperatures than the water in the Gulf (Fig. 9-7a). Within the Gulf itself, the Alaskan Gyre (west of 145°W) has a colder surface-water signature than the Cen- tral Subarctic Domain in the east — a condition that lasts well into the summer. This cooler water often signals higher sur- face concentrations of inorganic nutrients such as phos- phate, nitrate, and silicate (Figs. 9-7d through f). Such cool, high-nutrient water is often a sign of deeper water upwell- ing, as would be expected from the cyclonic nature of the Alaskan Gyre. Meridional sections across the Gulf of Alaska also revealed increased isohaline 'doming' along 156°W as the Alaskan Gyre is encountered near 52°N (Favorite, Dodimead, and Nasu 1976). Chlorophyll a levels in the central Alaskan Gyre are usu- ally lower than those in the central subarctic water (Fig. 9-7c). In spite of the steady increase in insolation across the Gulf from March through May (Fig. 9-7b), chlorophyll a lev- els did not display an analogous increase (Fig. 9-7c). How- ever, spring productivity did increase (Fig. 9-7g) in propor- tion to increases in the amount of daily light. The disparity between the increase in biomass and the increase in produc- tivity indicates that the more detailed measurements made at Station P have widespread applicability across the Gulf. In both the Central Subarctic Domain and the western Gulf, productivity values greater than 50 mg C/m2d were measured by late March, although in the central Alaskan Phytoplankton and Primary Production 257 A. Tkmpkraii ki (( i \lu JIM JULY Marc h n 1 1 1 r Chlorophyll a (mg/m:!) JUNE July E. NlTRAIt (|i\I/l) JUNE Jl-LY G. Primary Productivity (mg C/m^O.Sd) March JUNE jit y 135E B. [nsolation (cal/cm2d) I ~i 1 F. Silicate (nMSi(OH4)/l) Figure 9-7. Time/space contours of seven parameters meas- ured during the American Mail Line ship crossings of the Gulf of Alaska between 50 and 55°North. (Modified from Anderson and Munson 1972.) 175 165 Longitude (degrees) 145 125W 258 Biological Resources Gyre this value was not exceeded until May. Also, the west- ern Gulf of Alaska was by far the most productive area and the only location in which chlorophyll a levels greater than 2 mg/m3 were recorded (Larrance 1971a, b). This same chlo- rophyll a pattern was recorded during the 1968 sections from the AML ships. These sections indicate that the spring increase in daily light is important for stimulating production in the oceanic areas of the Gulf. However, a stable upper-water layer is also an important criterion for enhanced phytoplankton growth. Parsons et al. (1966) considered data from through- out the eastern subarctic Pacific, then used the critical depth approach to predict seasonal increases in phytoplankton growth. Their analysis indicated that growth would begin during March south of Kodiak Island and during April in much of the Central Subarctic Domain. This is even earlier than the point at which seasonal growth increases are observed at Station P. Detailed productivity data are not available to determine if enhanced productivity actually does occur in these areas at the predicted times. However, the times that were pre- dicted for spring phytoplankton growth did coincide with measured increases in copepod abundance in Gulf waters (Parsons, Ch. 18, this volume). This indicates that changes in the depth to which vertical mixing of surface-waters occur may cause a significant impact on phytoplankton growth in the Gulf and probably correspond to those growth trends exhibited at Station P. Nitrogen uptake data for August were collected at a sta- tion located at 50°N, 155°W (Hattori and Wada 1972). New (nitrate) production was 0.56 (J.M/m2d. The ratio of new uptake to total (nitrate and ammonium) uptake was ~ 0.36. Assuming that carbon and nitrogen are assimilated in the Redfield ratio (Redfield et al. 1963), then the total nitrogen productivity is equivalent to a carbon productivity of —130 mg C/m2d. This carbon productivity is greater than the 14C values measured in this area in July (Fig. 9-7g). The results of recent United States/Japan cooperative- sampling efforts include vertical chlorophyll a data that were collected across the Gulf at 55°N during July 1982 (Fig. 9-8). The chlorophyll a values in the samples are generally low (<1 Hg/1), similar to other measurements taken in this area. An abrupt increase in chlorophyll a levels at the mid- dle station in the section coincided with the boundary between the Alaskan Gyre in the west and the Central Sub- arctic Domain in the east. However, there may be no causal significance to this relationship because high chlorophyll a values found at the eastern end of this section did not corres- pond to any similar water mass boundary. The data presented in Figure 9-8 show the chlorophyll a levels that were extracted from all the particulate material that was retained on glass-fiber filters. In contrast to this pattern of 'whole community' chlorophyll a, the distribu- tion of chlorophyll a in selected particle-size ranges (or frac- tions) exhibited east-to-west differences across the sam- pling section. Specifically, in the western four stations in the Alaskan Gyre, there was less chlorophyll a associated with particles greater than 28 |xm (8.1%) than there was for the four eastern stations in the Central Subarctic Domain (19.5%). The cause of the zonal differences in the phyto- plankton-size distribution across the section is not clear. 154°52'W 139°02'W Figure 9-8. Extracted chlorophyll a values along 55°N in the Gulf of Alaska between the indicated longitudes (Faculty of Fisheries, Hokkaido University 1983; R.N. Sambrotto and J.J. Goering, University of Alaska, unpubl. data). In the eastern portion of the section, the mixed layer of the Central Subarctic Domain was warmer (10-12C) than the mixed layers in the west (8-9C). More importantly, the net tows across this section collected many more zooplankton of the copepod genus Calanvs (largely C. pacifkus) in the eastern waters. Therefore, the observed differences in phy- toplankton size distribution may reflect this east/west dif- ference in grazing pressure. This interpretation is compati- ble with the observation that C. pacifkus cannot efficiently remove large-size particles from seawater (Parsons, LeBrasseur, and Fulton 1967). Parsons (1972) did not find any clear zonal differences in particle-size spectra in the measurements he made during the spring bloom period. During an east-to-west crossing of the southern Gulf, he found that nanoplankton (2-20 |am) accounted for most of the chlorophyll a. Parsons and LeBrasseur (1969) suggested that because small phyto- plankton dominated the Gulf, the food chain leading to har- vestable particles was longer. This also meant it was less effi- cient than a system that supported larger phytoplankton. In addition, Parsons (1972) found that the particulate carbon- to-chlorophyll ratio of ~ 236 was much larger than the previous ratios (15-60) reported by McAllister (1969) from Station P. When Anderson et al. (1977) presented twenty years of phytoplankton data from the Gulf, they divided the eastern subarctic Pacific into geographic zones based largely on the physiographic domains introduced by Dodimead et al. (1963) (Fig. 9-9). They organized the data by zone and by data type in their presentation of broad-scale patterns. Sea- sonal chlorophyll a data that were integrated through the euphotic zone and organized in the above manner are pre- sented in Figure 9-10. As Figure 9-10 shows, the oceanic areas in the Gulf gener- ally exhibited both low and relatively uniform chlorophyll a levels throughout the year. In contrast, the coastal zones exhibited a pronounced seasonal trend in phytoplankton biomass and attained much higher maximum values. Excep- tions to the above trends were the relatively large oceanic chlorophyll a concentrations south of the Aleutian Islands Phytoplankton and Primary Production 259 180 Figure 9-9. Geographic zones used by Anderson et al. (1977) to analyze both phytoplankton and productivity data in the northern North Pacific. Figure 9-10. Distribution of depth-integrated chlorophyll a (seasonal means for the euphotic zone are in mg/m'-') for the Gulf of Alaska during the years 1958 through 1974. (Modified from Anderson et al. 1977.) W = December to February; Sp = March to May; S = June to August; A = September to November. The number of measurements on which the mean is based is given below each season. 260 Biological Resources in Zone 25 and beyond the Kodiak shelf in Zone 24. How- ever, the values in this latter zone are based on few data points and may not represent typical conditions. Both the seasonal and geographic productivity data that are integrated through the euphotic zone confirm the pat- terns discussed previously for Station P (Fig. 9-11). For exam- ple, in those zones for which sufficient data are available, the oceanic areas exhibit productivity peaks during the sum- mer, whereas the coastal areas show productivity increases that begin earlier in the year. Seasonal productivity changes in many parts of the Gulf cannot be resolved with existing data; however, extensive data for the central Gulf of Alaska coastal region are available and will be reviewed below. Anderson et al. (1977) also reviewed nutrient data. In the oceanic zones, nitrate levels went from late winter/early spring maxima to lower (but still non-limiting) concentra- tions in the summer — conditions similar to those at Station P. Nitrate concentrations decreased more than phosphate concentrations. Silicate was completely stripped from the surface water during the spring in Zone 17, and was stripped from the surface during summer in Zones 23 and 36. Silicate concentrations in Zone 17 are low throughout the year, sug- gesting that vigorous diatom growth takes place in this area in all seasons. Oceanic Phytoplankton Species Composition A list of those phytoplankton species recorded for the eastern subarctic Pacific is presented in Table 9-2. Note that this list also includes collections from transition waters south of 50°North. Therefore, the list includes warm-water species not often found in the Gulf such as Ethmodiscus rex, Eucampia zodiacus, Hemiaulus sinensis, Planktoniella sol, Rhi- zosolenia styliformis, and Pseudoeunotia doliolus. However, these can be carried along the outer edge of the Alaskan Gyre from lower latitudes, and P. sol has been found as far north as Zone 22. In reviewing phytoplankton taxonomic composition data collected from 120 ships of opportunity, Anderson et al. (1977) were not able to delineate any clear geographic pat- tern. This contrasts with the findings of Venrick (1971), who was able to identify groups of diatoms that were associated with certain areas. For example, both Venrick (1971) and Anderson et al. (1977) found that Rhizosolenia hebatata f . hiemalis, and Thalassionema nitzschioides were restricted to waters north of the transition zone. However, unlike Ven- rick (1971), Anderson et al. (1977) found Thalassiothrix long- issima and Tropidoneis antarctica distributed well north into the Gulf area. These differences may reflect seasonal and yearly variations in species distributions. Later work has sug- gested that the diatom Denticulopsis seminae is ubiquitous in the oceanic Gulf of Alaska (Booth 1981; Taylor and Waters 1982). Both the photosynthesis/light response and the composi- tion of phytoplankton communities in the western Gulf of Alaska were examined by Motoda and Kawamura (1963). The response of community photosynthesis to light was found to vary with community composition. For example, a community dominated by the diatom Thalassiothrix long- issima did not exhibit photosynthesis light saturation. In contrast, communities with significant numbers of Chaetoceros debilis exhibited maximum photosynthesis Figure 9-11. Distribution of depth-integrated carbon productivity (seasonal means for the euphotic zone are in mg C/m2d) for the Gulf of Alaska during the years 1958 through 1974. (Modified from Anderson etal. 1977.) W = December to February; Sp = March to May; S =June to August; A = September to November. The number of measurements on which the mean is based is given below each season. Phytoplankton and Primary Production 261 Table 9-2. Phytoplankton species list for the eastern subarctic Pacific north of 42°N and east of 180° West. (Modified from data compiled by Anderson etal. 1977.) Diatoms Achnantlws longipes Ag. ()•' A. sp. N Actinocycltis curvatuhis fanisch () A. sp. 0 Actinoptychus undulalui (Bail.) Ralfs 0 Amphiprora sp. N Asterionella japonica CI. 0 Asterolampra marylandica Ehr. o A. flabellatus (Breb.) Grev. o A. heptactus (Breb.) Rails 0 A. robustus Castr. 0 Baeteriastrum delicatulum CI. o Bacterosira fragUis Gran. N Biddulphia aurita (Lyng.) Breb. and God. N B. longicruris Grev. o #. sp. 0 Cerataulina sp. o C. bergonii H. Per. o Chaetoceros atlanticus CI. o C. convolutus Castr. o C. concavicornis Mang. 0 C. peruvianus Brightw. o C. debt I is CI. N C. decipiens CI. N C didymus Ehr. N C laciniosus Schutt N C. radicans Schutt N C. affinis Laud. N C. brevis Schutt N C mitra (Bail.) CI. N C. pelagicits CI. N C. socialis Laud. N C. subsecundus (Grun.) Hust. N C. teres CI. N C.occonris sp. O Corethron hystrix Hen. O Coscinodiscus lineatus Ehr. o C. curvatulus Grun. o C centralis Ehr. o C radiatus Ehr. o C. stellaris Rop. o C. oculis iridis Ehr. o C. tabularis Grun. o C. marginalia Ehr. o C. wailesii Gran and Angst o C. granii Gough N C. per for at us Ehr. o Cyclotella stelligera o CI . and Grun. Cylindrotheca closterium (Ehrb.) Reimanna and Leu in o Cymbella sp. o Dactyliosolen mediterraneus H.Per. o Denticulopsis seminae (Semina) Simon, and Kanava 0 Ditylum brightwellii (West) Grun. () Ethmodiscus rex (Wall.) I lendey ( ) Eucampia zodiacus Ehr. O Gyrosigma sp. N Grammatophora manna (Lyng.) Kill/. () Hemiaulus sinensis Grev. O H. membranaceous CI. O Hemidiscus cuneiformis Wall. O Lauder ia borealis Gran. O Leptocylindrus danicus C\. O Licmophora abbreviata Ag. N Melosira moniliformis (Mull.) Ag. N M. sulcata (Ehr.) Kiitz. N Navicula sp. O Nitzch ia serin to CI. O N. sicula (Castr.) Hustedt O N. bilobata Wm. Smith O N. bicapitata CI. O N. heirnii Manguin O N. turgiduloides Hasle O N. longissima (Breb.) Ralfs O N. pungens Hasle N A', paradoxa (Gmel.) Grun. N N. pseudonana Hasle1' O N. sp. O Planktoniella sol (Wall.) Schutt O Pleurosigma directum Grun. O Podosira sp. O Pseudoeunotia doliolus (Wall.) Grun. O Rhabdonema arcuatum Kiitz. O Rhizosolenia alata Brightw. O R. alata f. curvirostris Gran O R. alata f. inermis (Castr.) Hust. O R. hebetata f. hiemalis Gran O R. hebetata f. semispina (Hen.) Gran O R. stolterfothii H. Per. O R. styliformis Brightw. O R. styliformis f. longispina O Hust. O R. fragilissima Berg. O R. imbrkata shrubsolei (CI.) Schrod. O R. obtusa Hensen O Roperia tesselata (Roper) Grun. O Skeletonema costatum (Grev.) CI. O Stephanopyxis nipponica Gran and Yendo O S. turris (Grev. and Arn.) Ralfs N Striatella unipunctata (Lyng.) Ag. N Surirella sp. N Synedra vaucheriae Kutz. var. capitellala Grun. O Thalassionema nitzschioides Grun. O Thalassiosira decipiens (Grun.) J0rg. O '/'. angstii (Gran.) Makarova 7. nordenskioeldii CI. 7". rotula Meun. T. pacifica Gran and Angst T. subtilis (Osten.) Gran T. condensata CI. T. lineata Jouse T. antiqua (Grun) A. CI. var. septula Prosh. I.avr. T. oestrupii (Ostf.) Hasle T. eccentrica (Ehr.) Cleve T. polychorda (Gran) ]0rg. Thalassiothrix longissima CI. and (.i.iii Triceratium arcticum Brightw. Tropidoneis antarctica Grun. var. polyplasta Gran and Angst Dinoflagellates Ceratium fusus (Ehr.) Dujardin C. longipes (Bailey) Gran C. tripos O. F. Muller C. macroceros (Ehr.) Vanhoffen C. pentagonum Gourret C. lineatum (Ehr.) CI. C. intermedium (J0rg.) ]0rg. Dinophysis acuta Ehr. Exuviella baltica Lohmann Gymnodinium sp. Gyrodinium sp. Minuscula bipes Lebour Peridinium depressum Bailey P. cerasus Paulsen P. conicum (Gran) Ost. and Schmidt P. pallidum Ost. Coccolithophorids Calyptrosphaera sp. Coccolilhus huxleyi (Lohm.) Kpt.' C. pelagicm (Wallick) Schiller Cyclococcolithus leptoporus (Murr. el. Blackm.) Schiller C.fragilis (Lohm.) Gaarder Michaelsarsia sp. Rhabdosphaera tignifer Sch. Syracosphaera sp. Other gToups Pterosperma sp. Halosphaera viridis Schmitz Htn flagellates Pliaeocystis pouchetit (Hariot) Lagerhcim Ebria tripartita (Si hum.) Lemmerman Dictyocha fibula Ehr. Distephanus speculum (Ehr. I Haeckel I), octangulatiu Wailes O () () o () o O () o o o o N () o o O O o N O o O o O O O o N N O o o O o o o o () o o o o o o a O = oceanic. N = neritic ''This taxon probably includes a small number of cells of Nitzschia pseudonana Hasle. but is mostly cells and described as .V. cylmdroformis by Hasle and Booth 1984). The taxonomic complexities of this gr Washington, pers. comm., 1986). 'CocceUtkui huxleyi (Lohm.) Kpt. is now Emiliania huxleyi (Lohm.) Hav and Mohler. of N. cylindrnformis oup are discussed Hasle (called X. aliwlrii* Hasle in Booth el at. 1982 in Hasle and Booth 1984 (B. Booth. University of 262 Biological Resources around 500 lux. These results suggest that the spatial dif- ferences found in species distribution may influence phy- toplankton growth in the Gulf as well. One useful index of seasonal species changes at Station P — at least among the diatoms — is available from the sedi- ment-trap data of K. Takahashi (Woods Hole Oceano- graphic Institution, pers. comm.). For example, Rhizosolenia alata and Coscinodiscus marginatus were numerically abun- dant during winter conditions, while Chaetoceros concavicornis was the peak species during spring. Rhizosolenia styliformis exhibited a numerical maximum in the summer, while Cor- ethron hystrix appeared episodically throughout the growing season. Denticulopsis seminae was the only pennate diatom that accounted for a significant percentage of the biomass. The trap data suggest that certain silicoflagellates are useful indicators for productive periods. However, trap data probably will not be a useful sampling device for the micro- flagellates that usually constitute a large portion of the phytoplankton standing crop in the Gulf. A more complete species compilation than that available from the trap data is presented in Table 9-2. Anderson et al. (1977) ranked species from this list according to the max- imum number of cells per liter and the maximum amount of carbon per liter (Table 9-3). The maximum number of cells per liter for the top 15 species ranged from a high of 7 x 105 to a low of 2.4 x 103. Carbon per liter was estimated from cell volume (as described in the Methods section) and ranged from highs of 7.7 x 104 mgC/1 to a minimum of 1.62 x 103 mg C/l. Note that the coccolithophorid Cyclococcolithus sp. moved up dramatically in the carbon-per-liter rank- ing— mainly due to the extensive calcium carbonate test of these cells. Also, the diatom Corethron hystrix may contribute significantly to the total pool of particulate organic carbon due to its large size. Table 9-3. Phytoplankton species from 121 eastern subarctic stations (neritic stations omitted) ranked according to A) maximum number of cells per liter and B) maximum nanograms of carbon per liter. (Modified from Anderson et al. 1977.) A) Species Rank (# cells/1) B) Species rank (ngC/1) 1 . Nitzschia pseudonana 2. Denticulopsis seminae 3. Rhizosolenia alata f. inermis 4. Nitzschia sp. (Pseudonitzschia group) 5. Corethron hystrix 6. Cylindrotheca closterium 7 '. Cyclococcolithus sp. 8. Coccolithus huxleyi (= Em Mania huxleyi) 9. Thalassiosira nordenskioeldii 10. Thalassiosira lineata 1 1 . Coccolithus pelagicus 12. Asieromphalus spp. 1 3. Thalassiosira rotula 1 4. Chaetoceros atlanticus 1 5. Chaetoceros convolutus Nitzschia pseudonana Cyclococcolithus sp. Denticulopsis seminae Rhizosolenia alata f. inermis Corethron hystrix Nitzschia sp. (Pseudonitzschia group) Cylindrotheca closterium Coccolithus huxleyi (= Emiliama huxleyi) Coccolithus pelagicus Chaetoceros convolutus Thalassiosira nordenskioeldii Nitzschia sp. (Fragilariopsis group) Thalassiosira rotula Asieromphalus spp. Thalassiosira lineata However, as Anderson et al. (1977) point out, the listings in Tables 9-2 and 9-3 are not quantitative for phyto- plankton that do not preserve well and are therefore not adequately sampled by most investigators. In a section across Zones 18, 35, and 28 (Fig. 9-9), Booth et al. (1982) col- lected detailed information on the smaller phytoplankton (<20 (xm cell size). This study characterized these smaller cells ( < 20 p:m) in much greater detail than previous studies. The Booth et al. (1982) data differed in several respects from those of Anderson et al. (1977), largely reflecting improved methodology and updated taxonomy. For example, the prymnesiophyte Phaeocystis pouchetii was not restricted to neritic locations as suggested by Table 9-2, and attained cell numbers of over 106/1 in those oceanic areas that were sampled. In addition, four species of choanoflagellates were identified and two different kinds of cryptomonads were found. Coastal Gulf of Alaska The geographic productivity pattern suggested by Koblentz-Mishke, Volkovinsky, and Kabanova (1970) indi- cated that yearly productivity in the Gulf increased from oceanic values of less than 100 g C/m2 to values of 100 to 150 g C/m2 in the shelf and nearshore regions. These regions are here referred to as the coastal Gulf of Alaska. The original productivity contours of Koblentz-Mishke et al. (1970) were largely speculative, but later measurements confirmed a general increase in productivity for the coastal areas (Lar- rance 1971a, b; Goering, Shiels, and Patton 1973). The data sources on which the present discussion of coastal phyto- plankton is based are listed in Table 9-4 — analogous to the listing of oceanic data sources in Table 9-1. Before review- ing these data, some comments on the marked differences between phytoplankton growth conditions in coastal and oceanic water are in order. Major Influences on Coastal Phytoplankton Growth There is appreciable advection along the coastal area from British Columbia to the Aleutian Islands. Two distinct currents dominate local flow characteristics along this area (Reed and Schumacher, Ch. 3, this volume). The first is the Alaska Current, which flows counterclockwise along the shelf break at velocities up to 1.5 m/s (Niebauer, Roberts, and Royer 1981). Both wind and baroclinic forcing allow some of this water to enter Shelikof Strait through its northern end (Schumacher and Reed 1980). The second current is the Alaska Coastal Current, which is a prominent feature of the entire Gulf within ~ 35 km of the coast. This current reaches a velocity of 0.5 m/s and transports in excess of 1 x 106 m3/s (Royer 1981). Part of this coastal current flows along the Alaska Peninsula and exits the south Aleutian shelf through Unimak Pass (Schumacher, Pearson, and Overland 1982). These currents foster a much more energetic environ- ment in the surface water of the shelf and near-shelf areas than is found in the oceanic region. Also, unlike oceanic areas where excess plant nutrients are found year-round, nutrient-depleted surface layers develop during summer in the shallow, nearshore areas. Therefore, spring bloom con- Phytoplankton and Primary Production 263 Table 9-4. Biological and oceanographic data collected in the coastal area of the Gulf of Alaska. The data type codes used are the same as in Table 9-1. Specialized measurements of interest are also noted. Year/Month Data Type Soi K( I Eastern Aleutian Passes 1970 - June. September 1978 -Julv Shelikof Strait/Kodiak Island Shelf 1967 -June Cook Inlet 1968 - February, March. May-October 1974 -January-December 1976 -April, May, July, August 1978 - March, May-August Resurrection Bay 1972-1975 1983 - summer Prince William Sound 1971 - Mav-December 1972 -March-April 1976- April, May, Julv, August Northeast Gulf of Alaska Shelf 1976 - April, May, July, August Tenekee Inlet 1975 -July-August Auke Bay 1966 - 1968 various months 1968- April-June 1969 -June-August Smeaton Bay 1980 - October-December 1981 - February-October Boca de Quadra 1979 - December 1980 -April-July, September, December 1981 -January, April-June, August-October 1982- April, December 1983 -March-April Hecate Strait 1979 -June, Julv 1980 -June, August Multi-Site Studies 1978-1979 7, pCOa 1.7 6,7,8 5-8 5 1,2,3,5,7,9 1-3,5,7 (sediment traps) 3,7,8 1,3,5 1-7 1-3,5-7 1,2,3,5,7,9 1,2,3,5,7,9 KeWey etal. 1971 Koike etal. 1982 Wright 1970 Hood etal. 1968 Kinney et al. 1970 Schandelmeier 1975 Larrance et al. 1977 Larrance and Chester 1979 Chester and Larrance 1981 Heggie etal. 1977 Bienfangl984 Goering, Shiels, and Patton 1973; Goering, Patton, and Shiels 1973; Hood and Patton 1973 Homers al. 1973 Larrance et al. 1977 Larrance et al. 1977 Zimmerman and McMahon 1976 1,5,7,9 Bruce 1969 1,4,7 Schell 1974 1,7,9 Iverson, Curl, O'Connors, Kirk, and Zakar 1974 1-3,5,7,8 VTN Sciences 1982 1,2,3,6-8 Burrell 1984 1-3,5,7,8 VTN Sciences 1982 1,2,3,6-8 Burrell 1984 1-3,5,7-9 VTN Sciences 1982 1,2,3,6-9 Burrell 1984; VTN Sciences 1982 1,2,3,6-8 Burrell 1984 1,2,3,6-8 Burrell 1984 Sediment traps Burrell 1984 1,5,7 Perry et al. 1983 5* Hall 1982b a Most identifications from sediment isolates. *> Sampled 23 sites in several areas (see Fig. 9-23). ditions in many of the coastal areas are short-lived. A recent review of phytoplankton production on several shelves indi- cated that differences in yearly production levels were directly related to both the strength and the consistency of those physical mechanisms that supplied nutrients during the growing season (Sambrotto, Goering, and McRoy 1984). There are several mechanisms in the coastal Gulf waters that can supply nutrients to the euphotic zone throughout the summer. For example, a vigorous current such as the Alaska Coastal Current prevents nutrient depletion during summer by enhancing the vertical diffusion of nutrients (Winant and Olson 1976). Also, while coastal upwelling is not a dominant feature along the Gulf shelf, it does occur in the summer (Rover 1985). In addition, the intrusion of the Alaska Coastal Current into lower Cook Inlet brings sum- mer-long upwelling in that area (Muench, Mofjeld, and 264 Biological Resources Charnell 1978). Additional upwelling areas have been iden- tified along the Gulf coast and will be identified in the next section, which surveys the entire coastal environment. The spatial variability or patchiness in the distribution of chlorophyll a often coincides with specific physical hydro- graphic features found in the coastal environment (e.g., Seliger, McKinley, Biggley, Rivkin, and Aspden 1981). The association between phytoplankton abundance and along- shelf frontal features is well established for high-latitude shelves with low to moderate current regimes such as the eastern Bering Sea (Iverson, Coachman, Cooney, English, Goering, Hunt, Macaulay, McRoy, Reeburgh, and Whitledge 1979). Tidally mixed frontal systems, in particu- lar, enhance the nutrient supply to the surface waters and are areas where there is active phytoplankton growth throughout the summer (Pingree, Pugh, Holligan, and For- rester 1975). Fronts such as these influence phytoplankton growth in coastal British Columbia (Perry, Dilke, and Par- sons 1983). One important environmental factor that strongly influ- ences phytoplankton growth along the Gulf coast is the tur- bidity that comes from suspended terrestrial material. The geographic pattern of late-fall carbon productivity for the central northern Gulf reflects this influence (Larrance, Ten- nant, Chester, and Ruffio 1977). These data are presented by Parsons (Ch. 18, this volume: Fig. 18-3). The lowest prod- uctivities measured by Larrance et al. (1977) were located south and west of the mouth of the Copper River — in the path of a substantial amount of suspended material deliv- ered to the area by this river. The light available for photo- synthesis was so attenuated by this material that it resulted in a 50% decrease in the depth of the euphotic zone. This, in turn, greatly decreased the vertically integrated productivity. The only sampling area west of the Copper River that was highly productive was the relatively clear Orca Bay in Prince William Sound. There, an apparently isolated bloom ofSkel- etonema costatum was encountered. Cases where nearshore productivity is inhibited by turbid water may be common in the Gulf, judging from the extent to which coastal areas are influenced by silt-laden water (Hampton, Carlson, Lee, and Feely, Ch. 5, this volume). Grazing pressure in coastal areas may differ significantly from that found in oceanic areas. In the southeast Bering Sea, phytoplankton losses due to macrozooplankton graz- ing are significantly fewer in the coastal areas than they are farther offshore (Cooney and Coyle 1982). This is probably the case in nearshore regions in the Gulf, although this pat- tern is certainly not applicable to all coastal Gulf regions. For example, coastal advection carries oceanic zooplankton into Prince William Sound, which is deep enough for these populations to overwinter (Cooney, Ch. 10, this volume). Therefore, grazing pressure in such areas may approach that found in oceanic regions of the Gulf. Survey of Coastal Phytoplankton-Related Measurements Both chlorophyll a and productivity levels in Adak Bay and in the adjacent coastal/inner-Alaskan Stream water were consistently greater than those levels for oceanic waters of the Gulf (Larrance 1971a, b). Summer daily produc- tivity in the coastal waters here typically exceeded 0.4 gC/m2d, with integrated euphotic zone chlorophyll a values of over 20 mg/m2. Values for both parameters were greater still inside Adak Bay. In the oceanic region south of Adak Island, productivity rarely exceeded 0.3 g C/m2d, and the integrated chlorophyll a levels were never greater than 20 mg/m2. Larrance (1971a, b) also noted that there were elevated nutrient levels in the coastal surface water compared with the nutrient levels for the surface layer of deeper waters. These nutrients may be an indication of coastal upwelling in this region. Water movement through the Aleutian passes appears to produce local upwelling. This may be the case in Unimak Pass, where nutrient-rich water produces localized high productivity (Kelley et al. 1971). On the shelf between Kodiak Island and Unimak Pass, wind stress usually promotes upwelling during the summer (Ingraham, Bakun, and Favorite 1976). During August, the relatively cold surface water found both in and around Unimak Pass and in the Shumagin Islands suggests that substantial upwelling occurs throughout this entire area (Fig. 9-12). Kelley et al. (1971) found a strong correlation between surface-water pC02 and nitrate, suggesting that these two upwelled nutrients are consumed at least in part during plant growth. In this area, a supply of cold, deep water elevates the nitrate levels, the pC02, and the diatom growth well into July (Koike, Furuya, Otobe, Nakai, Nemoto, and Hattori 1982). During those summer conditions when upwelling does not occur near the coast, surface nutrient levels may decrease to a point where they begin to limit phytoplankton growth. In such cases, the vertical mixing caused by the Alaska Coastal Current could still provide enough nutrients to sustain growth. However, no clear examples of this inter- Figure 9-12. Satellite image of the western Gulf during the sum- mer. Shades of gray correspond to surface-water temperatures that range from cold (light gray) to warm (dark gray). The upwelling of cold subsurface water is apparent from the light- er-shaded surface water in and around Unimak Pass and the Shumagin Islands. Phytoplankton and Primary Production 265 action are available from the limited data available Tor the Gulf. On the northern shelf of the Alaska Peninsula, there is a coastal current that is associated with an intense subsurface chlorophyll a layer (Fig. 9-13). The rise in the depth of the nitrate isopleths in Figure 9-13a was probably caused by an intensified vertical shear at this depth. The water stratum just above the isopleths is commonly associated with a rela- tive maximum in zooplankton abundance (Herman 1983). Also, these layers may serve as important feeding environ- ments for larval pollock (Nishiyama, Hirano, and Haryu 1982). This sequence of relationships provides a mechanism by which the biological processes of the coastal area could respond to variations in both the transport and the speed of the coastal current (Sambrotto 1985). In late fall 1975, Larrance et al. (1977) made an extensive collection of productivity and related data in the central Gulfs coastal and nearshore areas (see Fig. 18-3, this vol- A. Nitrate (mM/m3) 72 73 0 Stations 74 75 Figure 9-13. Nitrate and chlorophyll a sections normal to the North Aleutian Shelf (56°47'N, 164°19'W to 57°9'N, 162°17.9'W). (Compiled from data in Niebauer, McRov, and Goering 1980.) ume). This figure illustrates the inhibiting effect that turbidity has on productivity in nearshore waters. It also indicates that productivity rates greater than 0.4 g C/m2d were present throughout both the outer-shelf and the oceanic areas that were sampled at that time. In July of 1976, the extreme southwestern station in this survey supported an integrated carbon productivity value of 2.4 g C/m2d. This indicates that both the central Gulf shelf and slope regions are much more productive than the oceanic and nearshore areas. Detailed seasonal data in Cook Inlet were presented by Larrance and Chester (1979) and by Chester and Larrance (1981). A section that extended across the lower portion of the Inlet was repeatedly sampled from April through August (Fig. 9-14). The results illustrate the dependence of coastal phytoplankton productivity on hydrographic condi- tions. Figure 9-15 depicts typical end-of-winter conditions along the section from Kamishak Bay (Station 1) to Kachemak Bay (Station 7). Judging from the lack of struc- ture in the density field, the upper mixed layer was relatively deep (Fig. 9-15a). The standing crop of phytoplankton at this time was low (Fig. 9-15b). Also, the depth uniformity of the nitrate concentration indicates that no substantial phytoplankton growth had occurred (Fig. 9-15c). Conditions in the sampling area changed a great deal during spring, however; and by lOJune, surface-water strati- fication was evident in both Kamishak and Kachemak Bays (Fig. 9-16a). The stratification was associated with surface accumulations of chlorophyll a (Fig. 9-16b), indicating that a typical, physically mediated, high-latitude spring bloom sequence takes place in these waters. By June, phyto- plankton nitrate consumption had significantly reduced the nitrate levels across the sampling section and had exhausted 60 - A Hydrocast stations • Sediment trap moorings 50km Figure 9-14. Lower Cook Inlet station locations sampled dur- ing April through August by Larrance and Chester (1979). 266 Biological Resources C. Nitrate (mM/m3) o B. Chlorophyll a (mg/m:l) o-, — — i — — l ■ ■ i i C. Nitrate (mM/m3) 0-r— —I— —I Figure 9-15. Late March 1978 sections across lower Cook Inlet from Kamishak Bay (Station 1) to Kachemak Bay (Station 7). (Modified from Larrance and Chester 1979.) Figure 9-16. June 1978 sections across lower Cook Inlet from Kamishak Bay (Station 1) to Kachemak Bay (Station 7). (Modi- fied from Larrance and Chester 1979.) Phytoplankton and Primary Production 267 the nitrate content of the surface waters in Kacheinak Bay. In contrast, nitrate concentrations remained relatively high in outer Kacheinak Bay (Fig. 9-16c). Chlorophyll a con- centrations across this section were at their maximum in early July, coincident with minimum nitrate levels. Bacterial activity in Kacheinak Bay closely followed this production cycle, although heterotrophic activity may lag phy- toplankton production slightly (Griffiths, Caldwell, and Morita 1982). Even in early July, nitrate was not exhausted from the upper water in the middle of lower Cook Inlet. Deeper water that upwelled may be responsible for maintaining these nitrate levels and the extremely productive area in outer Kachemak Bay. Productivity in this area was high throughout the summer (Fig. 9-17). Production values exceeding 7 g C/m'-d were measured here, and time- integrated productivity values suggest that yearly produc- tion may exceed 300 g C/m-. These data indicate that lower Cook Inlet is among the most productive high-latitude shelf areas in the world. Sediment trap data collected in outer Cook Inlet demon- strate the important role that copepod fecal pellets play in the sinking flux of surface organic particles (Table 9-5) (Lar- rance and Chester 1979). Fecal pellets accounted for 83% of the loss of surface chlorophyll a. Large numbers of oceanic grazers may be brought to this area by the Alaska Coastal Current (T. Cooney, University of Alaska, pers. comm.). This Table 9-5. Daily particulate flux (numbers/m'-') settling near the bottom in lower (look Inlet, 1978 (from I.arraiue and Chester 1979). See Figure 9-14 for locations of sediment traps. b£ 3 Eakli Ear] y La 1 1 Eari n Late April Man Mu JU« \l (.1 SI 1 1 1 \i Pellets I)l A KIMS Tin i innids <*I0") DlNOH AC. 11 1 MIS Moi is Kachemak May 0.360 13.41 0.114 0.023 0.027 Fun 0.932 1 5.82 0.408 0.024 0.010 Jul Aug 3.110 9.40 2.355 0.240 0.046 Central May 0.247 154.07 0.148 0.018 0.001 Jim 2.010 14.23 0.489 0.073 0.006 Jul 0.079 7.27 0.04 1 0.010 0.001 Aug 0.119 196.22 0.118 0.012 0.004 Kamisha k May 0.092 20.05 0.199 0.133 0.000 Jun - - - - - Jul 0.750 9.29 0.367 0.208 0.016 Aug 1.830 6.75 1.158 0.025 0.034 Figure 9-17. Average seasonal primary productivity in outer Kachemak Bay (Station 7, Fig. 9-14) during 1976. (Modified from Larrance el al. 1977.) means that — unlike some nearshore areas — phytoplankton grazing losses in lower Cook Inlet are significant. Ungrazed diatoms that sink also account for significant losses of surface-produced carbon in this area. In Cook Inlet, detrital phytoplankton are associated with fine- sized sediment material that exhibits a high percentage of organic carbon content (Atlas, Venkatesan, Kaplan, Feeley, Griffiths, and Morita 1983). Analysis of this material indi- cated that petroleum hydrocarbons from local oil-extrac- tion activities were not contaminating nearby food webs. Production studies began in the early 1970s in Resurrec- tion Bay on the Kenai Peninsula (Heggie, Boisseau, and Bur- rell 1977). Even though these measurements are scattered, they indicate that yearly production here may exceed 200 g C/m2. A facility was established in Seward, Alaska for pump- ing deep, nutrient-rich water from the fjord into ponds in order to study artificial upwelling (Neve, Clasby, Goering, and Hood 1976). This facility was used to study both the growth and the sinking dynamics of coastal phytoplankton (Bienfang 1984). In Resurrection Bay, most of the phyto- plankton biomass, as well as the photosynthesis that took place during the summer, was associated with cell sizes of less than 5 |im. Conversely, in the upwelling test ponds, more than 50% of the phytoplankton were larger than 20 urn. No significant difference was found between the sinking rates of the two groups (sinking rates varied from 0.07 to 0.63 m/d). Almost the entire downward flux of organic carbon and nitrogen was associated with the larger particles, however. Detailed seasonal data on phytoplankton growth also exist for selected areas of Prince William Sound. In Port Val- dez and Valdez Arm, both chlorophyll a concentrations and carbon productivity were measured bimonthlv from May 1971 to April 1972 by Goering, Shiels, and Patton (1973). They found a typical spring-bloom sequence in which both the areal photosynthesis and the standing crop increased dramatically in April, depleting the upper water of nitrate. 268 Biological Resources Productivity then decreased during the remainder of the summer in the dozen areas for which time series are avail- able. They did, however, find fall increases in areal photosynthesis for several areas (Fig. 9-18). The average vearlv production for all the areas covered in the study was ~185gC/m2. Goering, Shiels, and Patton (1973) also made 15N meas- urements of both nitrate and ammonium uptake (Table 9- 6). During April — before the surface-water nutrients were depleted — nitrate was the dominant form of nitrogen used for growth, and the percentage of nitrate uptake-to-total nitrogen uptake (nitrate and ammonium) was over 65% on an areal basis. Their July measurements were made well after the nutrients were depleted, and carbon productivity had decreased more than an order of magnitude compared with the April sampling. In July, the nitrogenous-nutrition pattern was completely reversed from that in April, and nitrate supplied only 1% of the phytoplankton nitrogen demands. These data illustrate the tendency for nitrate to play a more important role as a phytoplankton nitrogen source in eutrophic (more productive) situations. During the summer, it is common to find such nutrient- depleted conditions in the surface mixed layer of the coastal areas. For example, the strong physical stratification that develops in Auke Bay also results in nitrogen limitation and a sharp decrease in the phytoplankton standing crop com- pared with the spring values (Bruce 1969). Storms with accompanying winds that are strong enough to both deepen the surface mixed layer and to resupply the upper euphotic zone with nutrients during the summer were associated with renewed phytoplankton growth (Iverson, Curl, O'Connors, Kirk, and Zakar 1974). Iverson, Curl, and Sanger (1974) incorporated this wind mixing into their numerical model of Auke Bay phyto- plankton dynamics — a model that predicted phytoplankton responses to a deeper mixed layer. In Auke Bay, the Men- denhall Glacier runoff apparently does not significantly enrich the nutrient levels — as occurs in some other glacially fed coastal areas (Apollonio 1973). Also, a study of how organic nitrogen was used by the Auke Bay phytoplankton indicated that although the dissolved free amino acids become relatively abundant during phytoplankton growth, an uptake of 15N-labeled amino acids accounted for only a small fraction of the phytoplankton nitrogen requirements (Schell 1974). Several groups have conducted detailed studies of sea- sonal phytoplankton production in Alaskan fjords, specifi- cally in Boca de Quadra fjord and in Smeaton Bay-Wilson Arm near the Alaskan/Canadian border (Burrell 1984; VTN Sciences 1982). Seasonal sampling in Boca de Quadra fjord in 1980 indicated that the annual production there was — 145 g C/m2, and that much of this production took place during spring and fall bloom periods (Burrell 1984). The sur- face waters of both these fjords were nutrient depleted throughout the summer, causing peaks in both productivity and biomass to occur in subsurface layers (Fig. 9-19). Often in such physically stratified waters, the productiv- ity maximum occurs in shallower areas than the biomass (chlorophyll a) maxima. April carbon and nitrogen com- positional data for the particulate material in Boca de Quadra fjord is presented in Table 9-7. Station BQ-15 is outside the mouth of the fjord and BQ-3A is the farthest sta- tion inside the fjord. At the outer station (BQ-15), the lowest C-to-N ratios in the particulate material were found at the Station GB-1 225gC 3- 2- 1- he z 0- Station 106 Station 113 Station JB-1 Station 120 Station 128 Station 152 Station 153 Station 139 i i i i i i i i Station 171 i i i i i i i i i i i Station 142 Station 150 n r J M M J i ii — r J M M J Figure 9-18. Daily and annual rates of primary production in 12 locations around Port Valdez, Valdez Arm, and contiguous bays. (Modified from Goering, Shiels, and Patton 1973.) Pmvtoplankton and Primary Production 269 Table 9-6. Nitrogen- 15 and carbon-14 uptake rates by phytoplankton during spring and summer at Jackson Point, Port Valdez. (Modified from (ioering. Shiels, and Patton 1973.) NO., L'lM AM NH.,+ Uptake Pkrcf.ni NO., C ARBON Ul'I \K1 C:N Uptaki I)HM 11 (111) (|iMN(V -N/l-h) (uM Nil/ -N/l-h) Uptake* (uMHCO., -( :/l-h) Raiid 31 July 1971 0 0.0003 0.0091 2.8 0.0508 5.4 :">.() 0.0006 0.0397 1.5 0.0350 0.9 10.0 0.0002 0.0230 0.9 0.0250 1.1 15.0 0.0001 0.0108 0.9 0.0100 0.9 20.0 0.0001 0.0025 2.0 0.0058 2.3 25 April 1972 0 0.0184 0.0019 90.6 0.8525 42.0 2.0 0.0038 0.0023 62.8 1 .5775 258.6 3.5 0.0102 0.0022 81.9 1.6917 136.5 5.0 0.0103 0.0026 79.6 1 .3858 107.4 10.5 0.0009 0.0057 13.3 0.1467 22.4 NO," uptake •' '< .NO, uptake - NOs~ uptake + NH., uptake surface, unlike the more inshore stations at which minima in the C-to-N ratio occurred in subsurface strata. These subsurface minima in the C-to-N ratios coincided with sub- surface chlorophyll a maxima, and may indicate that the phytoplankton there were growing in a nitrogen-replete environment. East of the Queen Charlotte Islands in Hecate Strait, the summer phytoplankton biomass was greatest along a coastal front (Perry et al. 1983). This physical feature marks the tran- sition between the vertically mixed nearshore water and the deeper, stratified water. The characteristics of these tidally mixed fronts apparently prevent the depletion of local nutrients. These fronts are often associated with a summer increase in phytoplankton populations in several other tem- perate shelf areas as well. Most likely, these fronts are present along much of the Gulf coast and, as in Hecate Chi orophyll a (mg/m1) 20 30 50 100 14C Uptake (mgC/m3d) 200 300 400 Salinity 500 30 J 15 20 25 Salimtv (°/oo) 30 35 Figure 9-19. Vertical profiles through the euphotic zone for 14C uptake, chlorophyll a, and salinity at the head of Wilson Arm off Smeaton Bav near Ketchikan, Alaska during April 1982. (Modified from Burrell 1984.) Strait, they locally enhance phytoplankton growth during the summer. Just south of Hecate Strait, Denman, Mackas, Freeland, Austin, and Hill (1981) identified zones of both high produc- tivity and high biomass along the west coast of Vancouver Island. These zones were attributed to the combined effects of the along-shore current and to complex bathymetry that produced upwelling conditions. The Alaskan Stream may have the same effects in other areas of the Gulf. For example, the interaction of the Alaskan Stream and the shelf break may bring nutrient-rich slope water into the euphotic zone. Coastal Phytoplankton Species Composition In the fall of 1975, Larrance et al. (1977) conducted a tax- onomic analysis of the phytoplankton communities found in the coastal and near-oceanic areas of the central Gulf. These data indicated that the geographic distribution of the silicoflagellate Dictyocha fibula was mutually exclusive of the distribution of the diatom Fragilariopsis sp. (The genus Frag- ilariopsis has since been combined with Nitzschia.) The sil- icoflagellate was found only in areas west of the Copper River delta, and the diatom was restricted to areas east of the Table 9-7. Carbon-to-nitrogen ratios found in particulate matter through the euphotic zone in Boca de Quadra fjord in April 1983 (from Burrell 1984). Light Station Level (%) BQ-15 BQ-11B BQ-9 MA-2 BQ-5 BQ-3A 100 5.6 5.9 7.7 7.0 7.6 6.5 50 5.9 5.0 6.7 5.6 5.2 6.3 25 6.0 5.8 5.7 7.1 5.6 9.3 11 6.3 7.9 5.2 7.7 4.5 5.7 6 5.3 6.0 4.6 5.8 6.2 - 1 9.1 11.7 4.9 5.9 4.0 - 270 Biological Resources delta at that time. However, microflagellates were ubiq- uitous throughout the sampling area (Fig. 9-20). There is some indication that microflagellate densities on the shelf were about an order of magnitude larger than their densi- ties at the more oceanic stations. In addition, Larrance et al. (1977) observed differences between the phytoplankton communities found at the oceanic stations and those found in Prince William Sound. The offshore areas were dominated by microflagellates, while the Sound assemblage was dominated by diatoms. Diatoms also dominated the phytoplankton composition throughout the year off Nikiski (Schandelmeier 1975). A list of those phytoplankton species that were found in signifi- cant numbers in lower Cook Inlet during the spring and summer of 1976 is presented in Table 9-8 (Larrance et al. 1977). This list differs from the oceanic-species list (Table 9-2) in several respects. In particular, neritic species such as Melosira sulcata, which are totally absent from oceanic areas, were found in coastal waters. Based on temporal data in Table 9-8, the seasonal changes in phytoplankton commu- nity composition are presented graphically in Figure 9-21. A build-up of Thalassiosira spp. in April preceded the appearance of Chaetoceros spp., and both of these genera coexisted during the very productive period during May. Microflagellates dominated the outer Inlet in late August as they did throughout the oceanic waters during this time. The neritic Melosira sulcata usually dominated the upper parts of Cook Inlet. The seasonal succession of phytoplankton species is closely associated with the changing hydrography of the coastal areas (Levasseur, Therriault, and Legendre 1984). This tendency is evident in the species changes recorded by Larrance et al. (1977) in lower Cook Inlet (Fig. 9-21). For example, the appearance of the Thalassiosira-Chaetoceros community in May coincided with the establishment of a sta- ble upper-water column at this time. These observations are similar to those of Iverson, Curl, O'Connors, Kirk, and Zakar (1974) made in Auke Bay. The diatom bloom which formed upon the initial stratification of the water column in Auke Bay was composed mainly of Thalassiosira aestivalis, a Table 9-8. Phytoplankton species present in abundances greater than 1,000 cells/1 in lower Cook Inlet from April through August 1976. (Modified from Larrance et al. 1977.) April May May July August 7-12 6-9 25-28 10-15 25-31 Chrysophytes Dictyocha fibula X Ebria tripartita X Diatoms Actinoptychus undulatus X Bacteriastrum delicatulum X Cerataulina bergonii X X Chaetoceros affinis X X Chaetoceros compressus X X Chaetoceros concavicornis X X X X Chaetoceros constrictus X X Chaetoceros convolutus X Chaetoceros debilis X X X X Chaetoceros decipiens X X X Chaetoceros didymus X Chaetoceros radicans X X Chaetoceros subsecundus X Chaetoceros socialis X X X Chaetoceros spp. X X X Corethron hystrix X X Cylindrotheca closterium X X Denticulopsis semina X X Fragilariopsis spp. X X X X Leptocylindrus danicus X Melosira sidcata X X X X X Navicula distans X Navicula spp. X X Nitzschia delkatissima X X X X X Nitzschia longissima X X X X X Nitzschia spp. X X Rhizosolenia delicatula X Rhizosolenia fragilissima X Rhizosolenia stolterfothii X Schroederella delicatula X X Skeletonema costatum X Stephanopyxis nipponica X Thalassionema nitzschioides X X X X X Thalassiosira aestivalis X X X X X Thalassiosira decipiens X X X Thalassiosira gravida X X Thalassiosira nordenskioeldii X X X Thalassiosira pacifica X X X Thalassiosira polychorda X X Thalassiosira rotula X X X Thalassiosira spp. X X X X Tropidoneis antarctica X Dinoflagellates Exuviella spp. X X X Gymnodinium lohmanni X Oxyloxum spp. X X Peridinium minusculum X Peridinium spp. X X X Miscellaneous green algae X X X X microflagellates X X X X X Figure 9-20. Distribution of microflagellates at the 10-m depth in the central Gulf of Alaska from October through November 1975. (Modified from Larrance et al. 1977.) common early bloom species. However, the later productiv- ity peaks associated with wind mixing were often composed of Skeletonema costatum. Goering, Shiels, and Patton (1973) found that the flagel- late Phaeocystis pouchetii was numerically dominant during April in Valdez Arm. However, during the less productive July conditions, the phytoplankton community was domi- Phytoplankton and Primary Production 271 April 6-13 Dominant species ' Melosira sulcata : Chae toreros spp. Thalassiosira spp. Microflagellates 0 100km Figure 9-21. Distribution of dominant phytoplankton groups in lower Cook Inlet and adjacent waters from April through August 1976. (Modified from Larrance el ai 1977.) nated by the dinoflagellate Ceratium longipes. During this time, the nitrate and carbon productivities changed dramat- ically as well (Table 9-5). Therefore, the composition of the phytoplankton community may play an important role in determining local production rates. Generalizations regarding the exact sequence of species during the growing season are difficult to make because of the heterogeneous nature of the phytoplankton growth con- ditions that are encountered in the coastal Gulf. For exam- ple, the high volume of siltation found in the area west of the Copper River mouth is similar to the suspended-paniculate loading found in Cook Inlet (Kinney, Groves, and Button 1970). The shading caused by this suspended material is probably responsible for the slower-than-expected utiliza- tion of surface nitrate in the upper Inlet during spring. This shading effect may also slow the successional sequence of the phytoplankton species found here. An additional com- plication in successional studies is that species composition can vary with depth as well as time. For example, cell counts from Galena Bay indicated that Phaeocystis ponchetii could be found in numbers of over 1,000 cells/ml at depths where the light level was 1%, and at the same time they were almost absent from the surface waters above (Table 9-9). Size fractionation studies of the phytoplankton biomass have been done in Smeaton Bay near Ketchikan (Southeast Alaska) (VTN Sciences 1982). These studies indicated that 272 Biological Resources Table 9-9. Phytoplankton counts (cells/ml) of samples collected from the 100% and 1% light depths in Galena Bay during late April (from Horner elal. 1973). Species Cell Counts 100% light depth Diatoms Small flagellates Phaeocys t is pouchetii 1% light depth Diatoms Small flagellates Phaeocystis pouchetii 205 9 2 1006 30 1148 the ultraplankton (<5 |J,m) usually dominated the standing crop of chlorophyll a. Only during the spring diatom bloom did the larger (>5 |xm) phytoplankton dominate the com- munity. However, during the bloom, the larger phyto- plankton constituted up to 95% of the total chlorophyll a. Successional changes in the phytoplankton were well documented by tracking the species changes at four stations in the Smeaton Bay area (Fig. 9-22). During each time series, the large, chain-forming diatom Thalassiosira nordenskioeldii reached its peak abundance and numerically dominated the phytoplankton community during the April spring bloom. Since this was also the maximum productivity period of this species, it alone may be responsible for more than 25% of the total yearly production here. The most seaward station (SB7) exhibited a reduced diatom bloom in spring. How- ever, during the summer, diatoms contributed a larger pro- portion of the total phytoplankton numbers at this station than at the more protected stations. Dinoflagellate Growth in Coastal Gulf Waters Certain dinoflagellates produce toxins that can be trans- mitted to people if they eat contaminated filter-feeding organisms such as clams. Periods of intense summer dino- flagellate growth (often called 'red tides' because of the color that dense populations impart to nearshore waters) can pro- duce local anoxic conditions that damage fish populations (Malone 1978). Alaska has the potential for a substantial bivalve mollusk fishery (Orth, Smelcher, Feder, and Williams 1975). Therefore, red tides near such fisheries are significant both in terms of human health and in terms of economics (Fortune 1975). Dinoflagellates have been found among the phyto- plankton in both southeast Gulf coast waters (Chang 1971) and in northern Gulf coast waters (Schantz and Magnussen Station SB0 Station WA2 Q 3 Station SB7 3/26 □ Figure 9-22. kan, Alaska. Canal at the respectively. 4(24 7/18 Station BA1 Skeletonema costatum Dinoflagellates Leptocylindrus spp. 9/27 3/26 Sampling Period HM1 Chaetoceros spp. 9 Cryptophyta ] Other diatoms 6/24 7/18 9/27 m Bacteriastrum delicalulum [\\\N Thalassiosira nordenskioldii HI Microflagellates Seasonal changes in composition of the phytoplankton community at four stations in the Smeaton Bay area near Ketchi- (Modified from VTN Sciences 1982.) Station SBO is at the juncture of Wilson and Bakewell Arms, Station SB7 is in Behm mouth of Smeaton Bay, and Stations WA2 and BA1 are approximately at the midpoints of Wilson and Bakewell Arms, Phytoplankton and Primary Production 273 1964). The Wilson Arm/Smeaton Bay taxonomic data (Kig. 9-22) indicated that dinoflagellates appear in the coastal phytoplankton community at the end of the spring diatom bloom and persist throughout much of the summer. This is typical of the way they occur in the seasonal species sequence of coastal waters in other areas as well (Karentz and Smayda 1984). Dinoflagellate resting cysts have been isolated from sedi- ments throughout Alaskan coastal waters (Fig. 9-23). Hall (1982) identified the dinoflagellates as members of the genus Protogonyaulax and demonstrated their capacity for toxicity. Although Figure 9-23 is not a quantitative record of dino- flagellate distribution for Alaskan waters, it suggests that dinoflagellates are a common component of the phyto- plankton assemblage in the coastal Gulf. Dinoflagellates have also been found in surface waters during episodes of paralytic shellfish poisoning that occurred both in False Pass (Meyers and Hilliard 1955) and in Tenakee Inlet (Zim- merman and McMahon 1976). However, only in areas near Ketchikan was there an actual correlation made between shellfish toxicity and an abundance of dinoflagellates (Neal 1967). A definitive link between an abundance of dinoflagel- lates and filter-feeder toxicity may be missing for several reasons: 1) invertebrates may remain toxic for some time after the short-lived dinoflagellates have disappeared, 2) not all dinoflagellate species are toxic, and 3) invertebrates may become toxic after ingesting dinoflagellate cysts from the sediments. Summary of Regional Productivity Estimates and Conclusions Estimates for annual phytoplankton production and ranges for seasonal chlorophyll a levels for several areas of the Gulf are shown in Table 9-10. Seasonal production measurements in the nearshore areas of the Gulf are scat- tered. The values presented for the protected embayments near Port Valdez, Auke Bay, and for Boca de Quadra fjord are fairly similar. Typically, most of the production comes from relatively brief blooms in the spring, followed by a sec- ondary production peak in the fall. In Auke Bay, these blooms are augmented by wind-mixing-induced produc- tivity pulses throughout the summer. Less detailed data from Resurrection Bay suggest that yearly production in this fjord could exceed 200 g C/m2. Coastal areas are unusual with respect to most other regions in the Gulf in that the surface waters remain in a nutrient-depleted condition throughout most of the sum- mer. The maximum surface-water chlorophyll a values may be exceeded several-fold in subsurface layers that exist dur- ing much of the summer. Studies of primary production in selected Gulf shelf areas indicate that these regions are very productive. In lower Cook Inlet, upwelling that is associated with the Alaska Coastal Current appears to play an important role in maintaining the large daily production ( > 1 g C/m2) through- out the summer. Water movement through the Aleutian passes also produces local upwelling, and the relatively high productivity values recorded near Adak may reflect this process. 50 165 160 155 150 145 Figure 9-23. Locations where dinoflagellate resting cysts (Protogonyaulax sp.) have been isolated in Gulf coastal waters, and where they have been shown to produce paralytic shellfish toxins. (Modified from Hall 1982.) 274 Biological Resources Table 9-10. Summary of estimated annual phytoplankton production and chlorophyll ranges from various locations in the Gulf of Alaska. Location Annual Production (g C/m2) Based on: Surface Water '«C Mass Balance of: Nitrate Phosphate Chlorophyll a (mg/nv1) Nearshore Port Yaldez and 185 - 1 to 8* Valdez Arm" Auke Bayh 200 - 1 to 10* Boca de Quadrac Shelf 145 - 1 to 7* Adak Bay/Shelf 330 - 0.1 to 6* Lower Cook 300 - 0.1 to 10* Inler Kenai Shelf 30C)f - 0.1 to 3« Oceanic Ocean Station P 48h >100! 0.2 to 0.5 Western Gulf of 72-85 100 (rarely 2)8 0.2 to 2 Alaskad (along 1 76° W) a Goering, Shiels. and Patton 1973. b Iverson, Curl. O'Connors, Kirk, and Zakar 1974. < Burrell 1984. <■ Larrance 1971a. c Larrance and Chester 1979. 1 Larrance et al. 1977. g Andersons al. 1977. h McAllister 1969. ' See text. * Larger values measured in subsurface layers. The reasons for the intense production on the Kenai shelf in the central Gulf are less clear. Environmental features such as the Alaskan Stream coupled with intense grazing pressure on resident phytoplankton may play an important role in the productivity for this area. In any case, our review indicates that previous estimates of phyto- plankton production in shelf areas of the Gulf of Alaska must be revised upwards to ~ 300 g C/m2y. For the oceanic areas, there is a striking discrepancy between the results of using 14C incubation techniques and the results of using nutrient mass-balance methods for estimating yearly production. The nitrate mass-balance at Station P was based on the average seasonal nitrate data shown in Figure 9-3. From early March until September, the nitrate content of the upper 100 m decreased ~ 480 mM/m2. If this nitrate (or new) production is multiplied by the aver- age carbon-to-nitrogen composition of phytoplankton (6.6 by atoms) (Redfield et al. 1963), it yields an estimated annual carbon production of 38 g C/m2. However, nitrate produc- tion is only a portion of the total production, and the meas- urements of Hattori and Wada (1972) indicate that nitrate supplies less than 40% of the phytoplankton nitrogen requirements. Based on the findings of Hattori and Wada, the 38 g C/m2 estimate of annual carbon production was increased to 95 g C/m2. Even a production estimate of 95 g C/m2y is conservative because it is based only on the observed local nitrate change without taking into account the summer-long vertical nitrate supply from deeper waters. Based on Acara's (1964) estimate of upwelling at Station P ( — 17 m/y), 150 mM NO:5 /m2 would be supplied vertically over the course of the growing season. Phytoplankton consumption of this extra nitrate would result in ~ 30 g of additional carbon produc- tion. A similar approach to estimating carbon production (based on phosphate) was taken by Larrance (1971a) in the western Gulf. He also suggested that the 14C incubation esti- mates for phytoplankton production in the Central Sub- arctic Domain are low. The explanation for these significant (over 100% at Sta- tion P) discrepancies is not clear. The poor temporal resolu- tion of changes in productivity that are characteristic of the discrete-incubation methods may be a factor, but the sam- pling at Station P at least, should be fairly reliable. Piatt (1984) suggested that microzooplankton grazing that occurs during 14C incubations could cause underestimates of car- bon production. The importance of microzooplankton grazing in the control of phytoplankton standing crop in the Gulf suggests that the conditions necessary to cause such an underestimate are present. Because there are few detailed data for the Alaskan Gyre, a detailed comparison between productivity in this oceanic area and the productivity in the Central Subarctic Domain is not possible. However, although the phytoplankton growth in both of these areas is never nutrient limited, the more intense upwelling found in the Alaskan Gyre should influence phytoplankton growth there. Specifically, the delay in the onset of elevated productivity in the Alaskan Gyre (suggested by the data of Anderson and Munson 1972) may reflect this greater degree of upwelling. In terms of overall productivity, the shortened growing season makes the Alaskan Gyre less productive than the Central Subarctic Domain on a yearly basis. However, over- all nutrient-consumption calculations indicate that produc- tion levels in both the Central Subarctic Domain and the western Alaskan Gyre are greater than previous estimates {e.g., Sanger 1972). The Gulf of Alaska supports vast fisheries resources (OCSEAP Staff, Ch. 14, this volume; Rogers, Ch. 15, this vol- ume). Predictive fisheries models have been developed that address those interactions that affect phytoplankton growth in the Gulf (Laevastu 1978). However, we still lack the biolog- ical information necessary in order to do the same detailed trophodynamic modeling that has been done for other important fishing areas (e.g., Sherman, Smith, Morse, Ber- man, Green, and Ejsymont 1984). Any advances we can make in quantifying those loss processes that affect phyto- plankton in the oceanic Gulf will be helpful in this regard. Major environmental fluctuations have been recorded for the subarctic Pacific (Fulton and LeBrasseur 1985). These fluctuations appear to be associated with large-scale atmospheric changes (Hamilton and Emery 1985). Such fluc- tuations most likely influence not only the character, but the quantity of biological production in the Gulf — as they have been shown to do in other North Pacific areas (e.g., Peterson and Miller 1975). Better information (perhaps through remote sensing) on the annual variability in phytoplankton growth is needed in order to address the biological impact of these environmental fluctuations. Phytoplankton and Primary Production 275 Acknowledgments We thank both Dr. Bruce Wing of the National Marine Fisheries Service in Auke Bay and Dr. Richard Iverson of Florida State University at Tallahassee for their helpful dis- cussions. In addition, we acknowledge the useful informa- tion and suggestions we received from the other authors of this volume (especially Drs. Parsons and Cooney), as well as the helpful suggestions from the two anonymous peer reviewers for the chapter. Support for the preparation of this document was furnished by the Minerals Management Service, Department of the Interior, through an interagency agreement with the National Oceanic and Atmospheric Administration, Department of Commerce, as part of the Outer Continental Shelf Environmental Assessment Program. References Acara, A. 1964 On the vertical transport velocity on line "P" in the eastern subarctic Pacific Ocean. Journal of the Fisheries Research Board of Canada 21:397-407. Anderson, G.C. 1969 Subsurface chlorophyll maximum in the northeast Pacific Ocean. Limnology and Oceanography 14:386-391. Anderson, G.C. and R.E. Munson 1972 Primary production studies using merchant vessels in the North Pacific Ocean. In: Biological Oceanography of the Northern North Pacific Ocean. A.Y. Takenouti, editor. Idemitsu Shoten, Tokyo, pp. 245-251. Anderson, G.C, T.R. Parsons, and K. Stephens 1969 Nitrate distribution in the subarctic northeast Pacific Ocean. Deep-Sea Research 16:329-334. Anderson, G.C, R.K. Lam, B.C. Booth, and J.M. Glass 1977 A description and numerical analysis of the fac- tors affecting the processes of production in the Gulf of Alaska: final report. Research Unit 58. Environmental Assessment of the Alaskan Conti- nental Shelf, Annual Reports of Principal Investiga- tors for the Year Ending March 1977 7(Recep- tors— fish, littoral, benthos):477-798. Anonymous 1970 Data record. First Canadian trans-Pacific oceanographic cruise, March-May 1969. Bio- logical, chemical, and physical data. Fisheries Research Board of Canada Manuscript Report Series No. 1080. 92 pp. Anonymous 1973 Complex investigations of the continental slope in the Gulf of Alaska region. Akadcmiia Nauka. USSR Institute Okeanologii Vol. 91. 259 pp. Antia, N.J., K. Stephens, R.B. Tripp, T.R. Parsons, and J.D.H. Strickland 1962 A data record of productivity measurements made during 1961 and 1962. Fisheries Research Board of Canada Manuscript Report Series (Oceanographic and Limnological) No. 135. 41pp. Apollonio, S. 1973 Glaciers and nutrients in Arctic seas. Science 180:491-493. Atlas, R.M., M.I. Venkatesan, I.R. Kaplan, R.A. Feeley, R.P. Griffiths, and R.Y. Morita 1983 Distribution of hydrocarbons and microbial populations related to sedimentation pro- cesses in lower Cook Inlet and Norton Sound, Alaska. Arctic 36:251-261. Bienfang, P.K. 1984 Size structure and sedimentation of biogenic microparticulates in a subarctic ecosystem. Journal of Plankton Research 6:985-995. Booth, B.C. 1981 Vernal phytoplankton community in the east- ern subarctic Pacific: predominant species. In: Proceedings of the Sixth International Diatom Sym- posium, Budapest, 1980. R. Ross, editor.J. Cramer, Koenigstein, Federal Republic of Germany, pp. 339-358. Booth, B.C, J. Lewin, and R.E. Norris 1982 Nanoplankton species predominant in the sub- arctic Pacific in May and June 1978. Deep-Sea Research 29:185-200. Bruce, H.E. 1969 The role of dissolved amino acids as a nitrogen source for marine phytoplankton in an estuarine environment in southeastern Alaska. Ph.D. Dissertation, Oregon State University, Corvallis, OR. 124 pp. Burrell, D.C 1984 The biogeochemistry of Boca de Quadra and Smeaton Bay, Southeast Alaska: summary report 1980-1983. Prepared for U.S. Borax and Chemical Corporation and Pacific Coast Molybdenum Company by the Institute of Marine Science, University of Alaska, Fair- banks, AK. 280 pp. 276 Biological Resources Chang.J.C. 1971 An ecological study of butter-clam (Saxidomus giganteus) toxicity in Southeast Alaska. M.S. Thesis, University of Alaska, Fairbanks, AK. 94 pp. Chester, A.J. andJ.D. Larrance 1981 Composition and vertical flux of organic mat- ter in a large Alaskan estuary. Estuaries 4:42-52. Cooney, R.T. and K.O. Coyle 1982 Trophic implications of cross-shelf copepod distributions in the southeastern Bering Sea. Marine Biology (Berlin) 70:187-196. Cupp, E.E. 1943 Marine plankton diatoms of the west coast of North America. Bulletin of the Scripps Institute of Oceanography 5(l):l-237. Denman, K.L., D.L. Mackas, H.J. Freeland, M J. Austin, and S.H. Hill 1981 Persistent upwelling and mesoscale zones of high productivity off the west coast of Van- couver Island, Canada. In: Coastal Upwelling. F.A. Richards, editor. American Geophysical Union, Washington, D.C. pp. 514-521. Dodimead, A.J., F. Favorite, and T. Hirano 1963 Salmon of the North Pacific Ocean, part II: review of the oceanography of the subarctic Pacific region. North Pacific Fisheries Commis- sion Bulletin No. 13. 195 pp. Doty, M.S. 1964 Algal productivity of the tropical Pacific as determined by isotope tracer techniques: final report. Report 1, Appendices I— III, Hawaii Marine Laboratory, University of Hawaii, Hon- olulu, HI. 27 pp. Dugdale, R.C. 1967 Nutrient limitation in the sea: dynamics, identi- fication and significance. Limnology and Oceanography 12:685-695. Dugdale, R.C. and J.J. Goering 1967 Uptake of new and regenerated forms of nitro- gen in primary productivity. Limnology and Oceanography 12:196-206. Eppley, R.W. and B.J. Peterson 1979 Particulate organic matter flux and planktonic new production in the deep ocean. Nature (London) 282:677-680. El-Sayed, S.Z. 1978 Primary productivity and estimates of poten- tial yields of the southern ocean. In: Polar Research: To the Present and Future. M.A. McWhinnie, editor. American Association for the Advancement of Science, Washington, D.C. pp. 141-160. Faculty of Fisheries, Hokkaido University 1960 The Oshoru Maru cruise 44 to the Bering Sea in June-July 1959. Data Record of Oceanographic Observations and Exploratory Fishing 4:1-122 . Faculty of Fisheries, Hokkaido University 1961 The Oshoru Maru cruise 46 to the Bering Sea and North Pacific in June-August 1960. Data Record of Oceanographic Observations and Explora- tory Fishing 5:52-261. Faculty of Fisheries, Hokkaido University 1962 The Oshoru Maru cruise 48 to the Bering Sea and northwestern North Pacific in June-July 1961. Data Record of Oceanographic Observations and Exploratory Fishing 6:22-149. Faculty of Fisheries, Hokkaido University 1966 The Oshoru Maru cruise 14 to the northern North Pacific and Bering Sea in May-August 1965. Data Record of Oceanographic Observations and Exploratory Fishing 10:249-354. Faculty of Fisheries, Hokkaido University 1969 The Oshoru Maru cruise 28 to the northern North Pacific, Bering Sea, and the Gulf of Alaska in June-August 1968. Data Record of Oceanographic Observations and Exploratory Fishing 13:1-137. Faculty of Fisheries, Hokkaido University 1972 The Oshoru Maru cruise 37 to the northern North Pacific, Bering Sea, and Bristol Bay in June- August 1970. Data Record of Oceanographic Observations and Exploratory Fishing 15:1-97. Faculty of Fisheries, Hokkaido University 1981 The Oshoru Maru cruise 80 to the Bering Sea and North Pacific Ocean in June-August 1980. Data Record of Oceanographic Observations and Exploratory Fishing 24:1-108. Faculty of Fisheries, Hokkaido University 1982 The Oshoru Maru cruise 85 to the Bering Sea and the North Pacific Ocean in June-August 1981. Data Record of Oceanographic Observations and Exploratory Fishing 25:1-116. Faculty of Fisheries, Hokkaido University 1983 The Oshoru Maru cruise 90 to the Bering Sea and North Pacific Ocean in June-August 1982. Data Record of Oceanographic Observations and Exploratory Fishing 26:47-158. Favorite, F., A J. Dodimead, and K. Nasu 1976 Oceanography of the subarctic Pacific region, 1960-1971. International North Pacific Fish- eries Commission Bulletin No. 33. 187 pp. Fortune, R. 1975 Paralytic shellfish poisoning in the North Pacific: two historical accounts and implica- tions for today. Alaska Medicine 17:71-76. Phytoplankton and Primary Production 277 Fulton, J.D. and R.J. LeBrasseur 1985 Interannual shifting of the subarctic boundary and some biotic effects on juvenile salmon ids. In: El Nino North: Nino Effects in the Eastern Sub- arctic Pacific Ocean. W.S. Wooster and D.S. Fluharty, editors. Washington Sea Grant No. WSG-WO 85-3, University of Washington, Seattle, WA. pp. 237-252. Giovondo, L.F. and M.K. Robinson 1965 Characteristics of the surface layer in the north- east Pacific Ocean. Fisheries Research Board of Canada Manuscript Report Series (Oceano- graphic and Limnological) No. 205. 15 pp. plus 28 figures. Goering, J.J., C.J. Patton, and W.E. Shiels 1973 Nutrient cycles. In: Environmental Studies of Port Valdez. D.W. Hood, W.E. Shiels, and E.J. Kelley, editors. Occasional Publication No. 3, Institute of Marine Science, University of Alaska, Fair- banks, AK. pp. 225-248. Goering, J.J., W.E. Shiels, and C.J. Patton 1973 Primary production. In: Environmental Studies of Port Valdez. D.W. Hood, W.E. Shiels, and E.J. Kelley, editors. Occasional Publication No. 3, Institute of Marine Science, University of Alaska, Fairbanks, AK. pp. 251-279. Griffiths, R.P., B.D. Caldwell, and R.Y. Morita 1982 Seasonal changes in microbial heterotrophic activity in subarctic marine waters as related to phytoplankton primary production. Marine Biology (Berlin) 71:121-127. Hall, S. 1982 Toxins and toxicity of Protogonyaulax from the northeast Pacific. Ph.D. Dissertation, Univer- sity of Alaska, Fairbanks, AK. 196 pp. Hamilton, K. and W.J. Emery 1985 Regional atmospheric forcing of interannual surface temperature and sea level variability in the northeast Pacific. In: El Nino North: Nino Effects in the Eastern Subarctic Pacific Ocean. W.S. Wooster and D.L. Fluharty, editors. Wash- ington Sea Grant Publication No. WSG-WO 85-3, University of Washington, Seattle, WA. pp. 22-30. Harbison, G.R. and V.L. McAlister 1979 The filter-feeding rates and particle retention efficiencies of three species of Cyclosalpa (Tunicata, Thaliacea). Limnology and Oceanogra- phy 24:875-892. Hasle, G.R. 1959 A quantitative study of phytoplankton from the equatorial Pacific. Deep-Sea Research 6:38-59. Hasle, G.R. and B.C. Booth 1984 Nitzschia cylindroformis sp. nov., a common and abundant nano-plankton diatom of the east- ern subarctic Pacific. Journal ofPlanhUm Research 6:493-503. Hattori, A. and E. Wada 1972 Assimilation of inorganic nitrogen in the euphotic layer of the North Pacific Ocean. In: Biological Oceanography of the Northern North Pacific Ocean. A.Y. Takenouti, editor. Idemitsu Shoten, Tokyo, pp. 279-287. Heggie, D.T., D.W. Boisseau, and D.C. Burrell 1977 Hydrography, nutrient chemistry, and primary productivity of Resurrection Bay, Alaska, 1972-75. Institute of Marine Science Report No. R77-2, University of Alaska, Fairbanks, AK. Ill pp. Heinrich, A.K. 1975 The breeding and development of the domi- nant copepods in the Bering Sea. Trudy Bsesioznoe Gidrobiology Obshchertuo 8:143-162. (in Russian) Herman, A.W. 1983 Vertical distribution patterns of copepods, chlorophyll, and production in northeastern Baffin Bay. Limnology and Oceanography 28:709-719. Hobro, R. and E. Willen 1977 Phytoplankton countings. Intercalibration results and recommendations for routine work. Internationale Revue der Gesamten Hydro- biologie 62:805-811. Holmes, R.W. 1958 Surface chlorophyll a, surface primary produc- tion, and zooplankton volumes in the eastern Pacific Ocean. Rapports et Proces-Verbaux des Reunions, Conseil Permanent International pour lExploration de la Mer 144:109-116 . Hood, D.W. and L.A. Codispoti 1984 The effect of primary production on the car- bon dioxide components of the Bering Sea shelf. In: The Potential Effects of Carbon Dioxide- Induced Climatic Changes in Alaska. H. McBeath, editor. Miscellaneous Publication No. 83-1, School of Agriculture and Land Resources, University of Alaska, Fairbanks, AK. pp. 33-39 . Hood, D.W. and C.J. Patton 1973 Chemical oceanography. In: Environmental Studies of Port Valdez. D.W. Hood, W.E. Shiels, and EJ. Kelley, editors. Occasional Publication No. 3, Institute of Marine Science, University of Alaska, Fairbanks, AK. pp. 199-222. 278 Biological Resources Hood, D.W., K.V. Natarajan, D.H. Rosenberg, and D.D. Wallen 1968 Summary report on Collier Carbon and Chem- ical Corporation studies in Cook Inlet, Alaska. Institute of Marine Science Report No. R68-9, University of Alaska, Fairbanks, AK. 69 pp. Horibe, Y., editor 1971 Preliminary report of the Hakuho Maru cruise KH-70-2 (Great Bear Expedition) April 14- June 18, 1970, North Pacific. Ocean Research Institute, University of Tokyo , Tokyo. 90 pp. Horner, R.A., L.S. Dick, and W.E. Shiels 1973 Phytoplankton studies. In: Environmental Studies of Port Valdez. D.W. Hood, W.E. Shiels, and E.J. Kelley, editors. Occasional Publication No. 3, Institute of Marine Science, University of Alaska, Fairbanks, AK. pp. 283-294. Humm, HJ. and S.R. Wicks 1980 Introduction and Guide to the Marine Bluegreen Algae. John Wiley and Sons, New York, NY. 194 pp. Ingraham, W., J. A. Bakun, and F. Favorite 1976 Physical oceanography of the Gulf of Alaska, final report. Research Unit 357. Environmental Assessment of the Alaskan Continental Shelf Quar- terly Reports of Principal Investigators July- September 3:845-978. Iseki, K. 1981 Particulate organic matter transport to the deep sea by salp fecal pellets. Marine Ecology — Progress Series 5:55-60. Iverson, R.L., H.C. Curl, Jr., andJ.L. Saugen 1974 Simulation model for wind-driven summer phytoplankton dynamics in Auke Bay, Alaska. Marine Biology (Berlin) 28:169-177. Iverson, R.L., H.C. Curl, Jr., H.B. O'Connors, Jr., D. Kirk, and K. Zakar 1974 Summer phytoplankton blooms in Auke Bay, Alaska, driven by wind mixing of the water col- umn. Limnology and Oceanography 19:271-278. Iverson, R.L., L.K. Coachman, R.T. Cooney, T.S. English, J.J. Goering, G.L. Hunt, Jr., M.C. Macauley, C.P. McRoy, W.S. Reeburgh, and T.E. Whitledge 1979 Ecological significance of fronts in the south- eastern Bering Sea. In: Ecological Processes in Coastal and Marine Systems. R.J. Livingston, edi- tor. Plenum Press, New York, NY. pp. 125-157. Kanaya, T. and I. Koizumi 1966 Interpretation of diatom thanatocoenoses from the North Pacific applied to a study of core V20-130 (Studies of a deep-sea core V20-130. Part IV.). The Science Reports of the Tohoku University, Sendai, Japan, Second Series (Geology) 37:89-130. Karentz, D. and T.J. Smayda 1984 Temperature and seasonal occurrence pat- terns of 30 dominant phytoplankton species in Narragansett Bay over a 22-year period. Marine Ecology — Progress Series 18:277-293. Kelley, J.J., L.I. Longerich, and D.W. Hood 1971 Effect of upwelling, mixing, and high primary productivity on C02 concentration in surface waters of the Bering Sea. Journal of Geophysical Research 76:8687-8693. Kinney, P.J., J. Groves, and D.K. Button 1970 Cook Inlet environmental data: R/V Acona Cruise 065— May 21-28, 1968. Institute of Marine Science Report No. R-70-2, University of Alaska, Fairbanks, AK. 120 pp. Koblentz-Mishke, O.J. 1969 Specific composition of the phytoplankton and primary production in the northeastern Pacific Ocean. In: Proceedings of the Conference on Primary Productivity Measurement, Marine and Freshwater. M.S. Doty, editor. University of Hawaii, Honolulu, HI. pp. 10-19. Koblentz-Mishke, O.J., V.V. Volkovinsky, and J.G. Kabanova 1970 Plankton primary production of the world ocean. In: Scientific Exploration of the South Pacific. W.S. Wooster, editor. U.S. National Academy of Science, Washington, D.C. pp. 183-193. Koike, I., K. Furuya, H. Otobe, T. Nakai, T. Nemoto, and A. Hattori 1982 Horizontal distributions of surface chlorophyll a and nitrogenous nutrients near Bering Strait and Unimak Pass. Deep-Sea Research 29A:149-155. Kuroki, T. 1975 Preliminary report of the Hakuho Maru cruise KH-74-2 (N.N. Pacific Cruise) April 30-June 26, 1974: northern North Pacific Ocean. Ocean Research Institute, University of Tokyo, Tokyo. 72 pp. Laevastu, T. 1978 Dynamic numerical marine ecosystem model (DYNUMES III) for evaluation of fisheries resources. Research Unit 77. Environmental Assessment of the Alaskan Continental Shelf, Quar- terly Reports of Principal Investigators July- September 1978 1:319-431. Larrance,J.D. 1964 A method for determining volume of phyto- plankton in a study of detrital chlorophyll a. M.S. Thesis, University of Washington, Seattle, WA. 107 pp. Phytoplankton and Primary Production 279 Larrance, J.l). 1971a Primary production in the mid-subarctic Pacific region, 1966-1968. Fishery Bulletin (U.S.) 69:595-613. Larrance, J. D. 1971b Primary productivity and related oceano- graphic data, subarctic Pacific region, 1966-68. National Marine Fisheries Service Data Report No. 50. 113 pp. Larrance, J.D. and A.J. Chester 1979 Source, composition and flux of organic detritus in lower Cook Inlet. Outer Continental Shelf Environmental Assessment Program, Final Reports of Principal Investigators 46:1-71. Larrance, J.D., AJ. Chester, and H.B. Milburn 1979 A new sediment trap and particulate flux meas- urements in lower Cook Inlet, Alaska. Marine Science Communications 5:269-282. Larrance, J.D., D.A. Tennant, A.J. Chester, and P.A. Ruffio 1977 Phytoplankton and primary productivity in the northeast Gulf of Alaska and lower Cook Inlet: final report. Research Unit 425. Environ- mental Assessment of the Alaskan Continental Shelf Annual Reports of Principal Investigators for the Year Ending March 1977 10:1-136. Levasseur, M., J.-C. Therriault, and L. Legendre 1984 Hierarchical control of phytoplankton succes- sion bv phvsical factors. Marine Ecology — Pro- gress Series 19:211-222. Lisitzin, A.P. 1971 Distributions of siliceous microfossils in sus- pension and bottom sediments. In: The Micro- paleontology of the Oceans. B.M. Funnel and W.R. Reidel, editors. Cambridge University Press, Cambridge, England, pp. 127-195. Lorenzen, C.J. 1984a SUPER Program/data report 1. Incident radia- tion during cruises: SUPER 1, 18 April-24 Mav 1984; SUPER 2, 30 July-26 August 1984. College of Oceanography Reference 84-13, Oregon State University, Corvallis, OR. 109 pp. Lorenzen, C.J. 1984b SUPER Program/data report 2. Chlorophyll- phaeopigment profiles from SUPER 1 cruise, 28 April-24 May 1984, and SUPER 2 cruise, 30 July-26 August 1984. College of Oceanography reference 84-14, Oregon State University, Cor- vallis, OR. 133 pp. Malone, T.C. 1978 The 1976 Ceratium tripos bloom in the New York Bight: causes and consequences. NOAA Tech- nical Report NMFS Circular No. 410. 14 pp. McAllister, CD. 1962 Data record. Photosynthesis and chlorophyll a measurements at Ocean Weather Station "P", July 1959 to November 1961. Fisheries Research Board of Canada Manuscript Report Series (Oceanographic and Limnological) No. 126. 14 pp. McAllister, CD. 1969 Aspects of estimating zooplankton production from phytoplankton production. Journal of tlie Fisheries Research Board of Canada 26:199-220. McAllister, CD., T.R. Parsons, andJ.D.H. Strickland 1960 Primary productivity at Ocean Station P in the northeast Pacific Ocean. Journal du Conseil, Con- seil Permanent International pour I Exploration de la Mer 25:240-259. McGary,J.W. andJJ. Graham 1960 Biological and oceanographic observations in the central North Pacific, July-September 1958. U.S. Fish and Wildlife Service SSRF-358. 107 pp. Meyers, H.F. and D.K. Hilliard 1955 Shellfish poisoning episode in False Pass, Alaska. Public Health Reports 70:419-420. Motoda, S. and T. Kawamura 1963 Light assimilation curves of surface phyto- plankton in the North Pacific 42°N— 61°N. In: Symposium on Marine Microbiology. C.H. Oppenheimer, editor. Charles C Thomas, Springfield, IL. pp. 251-259. Muench, R.D., H.O. Mofjeld, and R.L. Chamell 1978 Oceanographic conditions in lower Cook Inlet: spring and summer 1973. Journal of Geo- physical Research 83O5090-5098. Neal, R.A. 1967 Fluctuations in the levels of paralytic shellfish toxin in four species of lamellibranch molluscs near Ketchikan, Alaska, 1963-1965. Ph.D. Dis- sertation, University of Washington, Seattle, WA. 164 pp. Neve, R.A., R.G. Clasby, J.J. Goering, and D.W. Hood 1976 Enhancement of primary productivity by artificial upwelling. Marine Science Communica- tions 2:109-124. Niebauer, H.J., J. Roberts, and T.C. Royer 1981 Shelf break circulation in the northern Gulf of Alaska. Journal of Geophysical Research 86C4231-4242. Nishiyama, T., K. Hirano, and T. Haryu 1982 Nursery layer of walleye pollock {Tfieragra chal- cograma) larvae. EOS 63:943. (Abstract only) 280 Biological Resources Orth, F.L., C. Smelcher, H.M. Feder, andj. Williams 1975 The Alaskan clam fishery: survey and analysis of economic potential. Institute of Marine Sci- ence Report No. R75-3, University of Alaska, Fairbanks, AK. 148 pp. Parsons, T.R. 1972 Size fractionation of primary producers in the subarctic Pacific area. In: Biological Oceanography of the Northern North Pacific Ocean. A.Y. Take- nouti, editor. Idemitsu Shoten, Tokyo, pp. 275-278. Parsons, T.R. and G.C. Anderson 1970 Large scale studies of primary production in the North Pacific Ocean. Deep-Sea Research 17:765-776. Parsons, T.R. and R.J. LeBrasseur 1967 North Pacific biological studies. Fisheries Research Board of Canada. Annual Report. Pacific Oceanographic Group. 75 pp. Parsons, T.R. and R.J. LeBrasseur 1969 A discussion of some critical indices of primary and secondary production for large scale ocean surveys. California Marine Research Commission CALCOFI Report No. 12. pp. 54-63. Parsons, T.R., L.F. Giovondo, and RJ. LeBrasseur 1966 The advent of the spring bloom in the eastern subarctic Pacific Ocean. Journal of the Fisheries Research Board of Canada 23:539-546. Parsons, T.R., R.J. LeBrasseur, andJ.D. Fulton 1967 Some observations on the dependence of zoo- plankton grazing on the cell size and con- centration of phytoplankton blooms./ourra^ of the Oceanographical Society of Japan 23(1):10-17. Parsons, T.R., Y. Maita, and CM. Lalli 1984 A Manual of Chemical and Biological Methods for Seawater Analysis. Pergamon Press, New York, NY. 173 pp. Perry, R.I., B.R. Dilke, and T.R. Parsons 1983 Tidal mixing and summer plankton distribu- tions in Hecate Strait, British Columbia. Cana- dian Journal of Fisheries and Aquatic Sciences 40:871-887. Peterson, B.J. 1980 Aquatic primary productivity and the 14C-C02 method: a history of the productivity problem. Annual Review of Ecology and Systematics 11:359-385. Peterson, W.T. and C.B. Miller 1975 Year-to-year variations in the planktology of the Oregon upwelling zone. Fishery Bulletin (U.S.) 73:642-653. Pingree, R.D., P.R. Pugh, P.M. Holligan, and G.R. Forster 1975 Summer phytoplankton blooms and red tides along tidal fronts in the approaches to the Eng- lish Channel. Nature (London) 258:672-677. Piatt, T. 1984 Primary productivity in the central North Pacific: comparison of oxygen and carbon fluxes. Deep-Sea Research 31:1311-1319. Redfield, A.C., B.H. Ketchum, and F.A. Richards 1963 The influence of organisms on the composi- tion of sea-water. In: The Sea, Vol. 2. M.N. Hill, editor. Wiley Interscience, New York, NY. pp. 26-77. Rhode, W., R.A. Vollenweider, and A. Nauwerick 1958 The primary production and standing stock of phytoplankton. In: Perspectives in Marine Biology. A.A. Buzzati-Traverso, editor. University of California Press, Berkeley and Los Angeles, CA. pp. 299-322. Royer, T.C. 1981 Royer, T.C. 1985 Baroclinic transport in the Gulf of Alaska, part II: a fresh water driven coastal current. Journal of Marine Research 39:251-266. Coastal temperature and salinity anomalies in the northern Gulf of Alaska, 1970-1984. In: El Nino North: Nino Effects in the Eastern Subarctic Pacific Ocean. W.S. Wooster and D.L. Fluharty, editors. Washington Sea Grant No. WSG-WO 85-3, University of Washington, Seattle, WA. pp. 107-115. Sambrotto, R.N. 1985 The dependence of phytoplankton nutrient utilization on physical processes in the eastern Bering Sea area: mechanisms for yearly varia- tion. In: El Nino North: Nino Effects in the Eastern Subarctic Pacific Ocean. W.S. Wooster and D.L. Fluharty, editors. Washington Sea Grant No. WSG-WO 85-3, University of Washington, Seattle, WA. pp. 268-281. Sambrotto, R.N. , J.J. Goering, and C.P. McRoy 1984 Large yearly production of phytoplankton in the western Bering Strait. Science 225:1147-1150. Sanger, G.A. 1972 Fishery potentials and estimated biological productivity of the subarctic Pacific region. In: Biological Oceanography of the Northern North Pacific Ocean. A.Y. Takenouti, editor. Idemitsu Shoten, Tokyo, pp. 566-574. Phytopiankton and Primary Production 281 Schandelmeier, L. 1975 Phytopiankton, January 1974-December 1974. In: Oceanographic data: Collier Carbon and Chemical Corporation Pier, Cook Inlet, Alaska, August, 1975. D. Rosenburg, editor. Institute of Marine Science, University of Alaska, Fairbanks, AK. 28 pp. Schantz, E.J. and H.W. Magnusson 1964 Observations of the origin of the paralytic poi- son in Alaska butter clams. Journal of Pro- tozoology 11:239-242. Schell, D.M. 1974 Uptake and regeneration of free amino acids in marine waters of Southeast Alaska. Limnology and Oceanography 19:260-270. Schumacher, J.D. and R.K.. Reed 1980 Coastal flow in the northwest Gulf of Alaska: the Kenai Current. Journal of Geophysical Research 85:6680-6688. Schumacher, J.D., C.A. Pearson, andJ.E. Overland 1982 On exchange of water between the Gulf of Alaska and the Bering Sea through Unimak Pass. Journal of Geophysical Research 87C:5785-5795. Seliger, H.H., K.R. McKinley, W.H. Biggley, R.B. Rivkin, and K.R.H. Aspden 1981 Phytopiankton patchiness and frontal regions. Marine Biology (Berlin) 61:119-131. Sherman, K., W. Smith, W. Morse, M. Berman, J. Green, and L. Ejsymont 1984 Spawning strategies of fishes in relation to cir- culation, phytopiankton production, and pulses in zooplankton off the northeastern United States. Marine Ecology — Progress Series 18:1-19. Shuman, F.R. and C.J. Lorenzen 1975 Quantitative degradation of chlorophyll by a marine herbivore. Limnology and Oceanography 20:580-586 . Steele, J.H. and B.W. Frost 1977 The structure of plankton communities. Philo- sophical Transactions of the Royal Society of London 280:485-534. Steemann Nielsen, E. 1952 The use of radioactive carbon C14 for measur- ing organic production in the sea. Journal du Conseil, Conseil Permanent International pour I'Exploration de la Mer 18:117-140. Stephens, K. 1964 Data record. Productivity measurements in the northeast Pacific with associated chemical and physical data, 1958-1964. Fisheries Research Board of Canada Manuscript Report Series (Oceanographic and Limnological) No. 179. 168 pp. plus 15 figures. Stephens, K. 1966 Data record. Primary production data from the N.E. Pacific Ocean, January 1964 to December 1965. Fisheries Research Board of Canada Manuscript Report Series (Oceanographic and Limnological) No. 209. 14 pp. Stephens, K. 1968 Data record. Primary production data from the northeast Pacific Ocean, January 1966 to December 1967. Fisheries Research Board of Canada Manuscript Report Series No. 957. 58 pp. Stephens, K. 1970 Data record. Primary production data from the northeast Pacific Ocean, January 1967 to December 1969. Fisheries Research Board of Canada Manuscript Report Series No. 1123. 16 pp. Strathmann, R.R. 1967 Estimating the organic carbon content of phytopiankton from cell volume or plasma vol- ume. Limnology and Oceanography 12:411-418. Sverdrup, H.U. 1953 On conditions for the vernal blooming of phytoplankton./ownm/ du Conseil, Conseil Perma- nent International pour I'Exploration de la Mer 18:187-195. Takahashi, M., K. Satake, and N. Nakamoto 1972 Chlorophyll distribution and photosynthetic activity in the North and equatorial Pacific Ocean along 155° W. Journal of the Oceanographic Society of Japan 28:27-36. Taylor, F.J.R. and R.E. Waters 1982 Spring phytopiankton in the subarctic North Pacific Ocean. Marine Biology (Berlin) 67:323-335. University of California 1967 Physical, chemical, and biological data: Ursa Major expedition, 4 August-4 October 1965. Reference 67-5, Scripps Institute of Oceano- graphy, Lajolla, CA. 43 pp. University of California 1970 Physical, chemical, and biological data: Zetes expedition, Leg I, 11-24 January 1966. Refer- ence 70-5, Scripps Institute of Oceanography, Lajolla, CA. 70 pp. 282 Biological Resources Utermohl, H. 1931 Neue Wege in der qualitative!! Erfassung des Planktens. Internationale Vereinigung Fuer The- oretische und Angewandte Limnologie Ver- handlungen 5:151-155. Venrick, E.L. 1969 The distribution and ecology of oceanic diatoms in the North Pacific. Ph.D. Disserta- tion, University of California, San Diego, CA. 655 pp. Venrick, E.L. 1971 Recurrent groups of diatom species in the North Pacific. Ecology 52:614-625. VTN Sciences 1982 1981 Wilson Arm/Smeaton Bay baseline report. Consultants report: Coastal and Marine Biol- ogy Program, Quartz Hill Molybdenum Proj- ect. Prepared for U.S. Borax and Chemical Cor- poration, Los Angeles, CA, on behalf of Pacific Coast Molybdenum Company. VTN Sciences Inc., Anchorage, AK. 300 pp. Walker, T.A. 1980 A correction to the Poole and Atkins Secchi disc/light-attenuation formula. Journal of the Marine Biological Association of the United Kingdom 60:769-771. Welschmeyer, N.A. and C.J. Lorenzen 1985 Chlorophyll budgets: zooplankton grazing and phytoplankton growth in a temperate fjord and the central Pacific gyres. Limnology and Oceanography 30:1-21. Winant, CD. andJ.R. Olson 1976 The vertical structure of coastal currents. Deep- Sea Research 23:925-936. Wright, F.F. 1970 An oceanographic reconnaissance of the waters around Kodiak Island, Alaska. Report No. R70-19, Institute of Marine Science, Uni- versity of Alaska, Fairbanks, AK. 23 pp. Yentsch, C.S. and D.W. Menzel 1963 A method for the determination of phy- toplankton chlorophyll and phaeophytin by fluorescence. Deep-Sea Research 10:221-231. Zimmerman, S.T. and R.S. McMahon 1976 Paralytic shellfish poisoning in Tenakee Inlet, Southeastern Alaska: a possible cause. Fishery Bulletin (U.S.) 74:679-680. Zooplankton 10 R. Ted Cooney Institute of Marine Science University of Alaska Fairbanks, Alaska Abstract This chapter reviews the distribution, seasonal abundance, species composition, and production of zooplankton in the Gulf of Alaska. Emphasis is placed on research conducted since 1970. Approximately 30 species account for the majority of the biomass and numerical abundance, with copepods being the most common taxa collected when using plankton nets and trawls with mesh sizes ranging between 0.200 and 0.500 millimeters. Zooplankton standing stock (wet weight) varies seasonally. Summer and fall highs range from 1,600 g/m2 for the deep inside waters (Prince William Sound; 700 m) to 30 g/m2 in the upper 150 m at Ocean Station P. Winter values decline to 1.5 g/m2 in the open ocean, with higher biomass occurring over the shelf and in the inside waters; 40 g/m2 in the Strait of Georgia, British Columbia, and 1,320 g/m2 in Prince William Sound. Oceanic zooplankton populations may produce up to 30 g C/m2y (upper 150 m) assuming that all the phytoplankton production is grazed, and that 30% of what is ingested appears as growth. The annual growth of populations over the shelf and in the inside waters is probably higher, with production estimates ranging from 27 to 50 g C/m2y. Since the annual primary production over the shelf (where measured) does not exceed 300 g C/m2y, the zooplankton growth is not likely to be greater than 20% of this value, 60 g C/m2y. The Alaska Coastal Current (ACC) and the Alaska Current/Alaskan Stream pro- vide physical mechanisms that mix oceanic and shelf populations, and then distribute this assemblage around the periphery of the Gulf. The result is a homogeneous sub- arctic community occurring over 2,200 km of coastline from northern British Colum- bia to the tip of the Alaska Peninsula. The abundance of several oceanic zooplankters in shelf and coastal collections demonstrates the influence that the bordering ocean has on shallower-water processes such as synthesis and transfer of organic matter. However, this influence has yet to be fully evaluated. Introduction Oceanographic studies in the North Pacific Ocean date from observations made during the Challenger Expedition (1872-1876), from three cruises of the American vessel, Albatross (1888-1905), and from a portion of the Carnegie Expedition (1929). As early as 1889, the Harriman Alaska Expedition crossed the northern Gulf of Alaska and exam- ined some of the physical and geological features of the coastal zone between Yakutat Bav and Kodiak Island, including much of interior Prince William Sound. This lat- ter effort was furthered by studies conducted during the Canadian Arctic Expedition (1913-1924). These early ven- tures were, in part, responsible for collecting and describing the common flora and fauna of the open ocean and coastal regions of Alaska. The International Pacific Halibut Commission (formerly the International Fisheries Commission) collected plankton samples in the northern Gulf of Alaska from 1926 to 1934 in order to support studies of the distribution and abundance of fish eggs and larvae (Thompson and Van Cleve 1936). Samples from the Northern Holiday expedition and the Inter- national Fisheries Commission also form a basis for descrip- tions of euphausiid distributions in the North Pacific (Brin- ton 1962). In 1955, Japan, Canada, and the United States began an international study of the North Pacific Ocean 285 286 Bioiocic ai Resources titled NORPAC. Nineteen research vessels and 14 institu- tions studied the physics, biology, and fisheries of this region. The most ambitious zooplankton research for multi-year time series at Ocean Station 'P' (OSP) and from broader reaches of the northeastern Pacific was reported by LeBrasseur (1965a, 1965b) and Fulton and LeBrasseur (1985). Seasonal and annual variability for copepods, euphausiids, amphipods, decapods, chaetognaths, pteropods, and small cephalopods was described from a collection of ~ 5,000 ver- tical tows (taken with a NORPAC net with 0.3-mm mesh size). Only a small percentage of the 5,000 samples was obtained from shelf and coastal regions. In addition, several Soviet investigators described the ecological importance of the large upper-layer oceanic copepods in seasonal studies of the North Pacific Ocean (Vinogradov 1968; Heinrich 1968: Vinogradov and Arashkevich 1969). The purpose of this chapter is to review both the pub- lished manuscripts and the unpublished reports that describe the distribution, abundance, and species composi- tion of zooplankton communities occurring in the oceanic and shelf/coastal regions of the Gulf of Alaska. Particular attention is given to investigations sponsored by BLM/ NOAA under the Alaska Outer Continental Shelf (OCS) studies (1974-1979). The intent is to summarize and discuss the present knowledge of zooplankton in this northern tem- perate ocean and to identify areas where future research needs to be done. Although the study area has been defined as that portion of the northeastern Pacific Ocean north of 52°N and extending west to 176°W, it is necessary to draw on information (mostly Canadian) published for a few more southerly locations to supplement the available information. The Database This review is limited to information that describes the distribution, abundance, and standing stock of zooplankters that were collected using nets and trawls with mesh sizes ranging between 0.200 and 0.500 millimeters. Conse- quently, crustacean microzooplankton and marine pro- tozoans are excluded from this chapter. In a number of the OCS-sponsored studies, the standing stock of net-caught zooplankton is reported as settled vol- ume. In the interest of consistency within this chapter, set- tled volumes in ml/m3 or ml/m2 were converted to g/m3 or g/m2 after Weibe, Boyd, and Cox (1975). This conversion assumes that 70% of the settled volume in milliliters is equivalent to the wet weight in grams. Since at least two dif- ferent mesh sizes (0.333 or 0.211 mm) and several nets (1-m, 0.5-m, neuston, 60-cm bongo, and 2-m Tucker trawl) were used, strict comparisons between standing stocks reported by various investigators are probably not appropriate in view of errors associated with active avoidance or losses through the mesh. Also, it is likely that nets fished with 0.211-mm mesh contained higher amounts of phytoplank- ton than did 0.333-mm nets. However, there is neither a way to tell if this is true, nor a method to remove this bias from settled volume measurements. In those few cases where formalin dry-weight values were reported, wet weights were estimated by first using a 15% conversion factor (Ikeda and Motoda 1978) and then doub- ling the resultant values to account for preservation losses (Paffenhofer 1980). Zooplankton carbon was considered to be 45% of the reported or estimated dry weight since the samples were dominated primarily by copepods (eupha- usiids were probably not well sampled in most studies). These problems with the database are acknowledged so the reader may be aware of the limitations inherent in the underlying observations and their subsequent interpreta- tion. Community Composition In all, 284 species and six generic composites have been reported for zooplankton and micronekton collected from the oceanic, shelf, and coastal waters of the northern Gulf of Alaska (Fig. 10-1; Appendix I, II). Four taxa constitute the most diverse groups: Cnidaria, Copepoda, Amphipoda, and Osteichthys (Table 10-1). In general, the Gulf of Alaska com- munity reflects a similarity with the zooplankton and micro- nekton communities reported previously for the Bering Sea (Cooney 1981) and (though not shown) for British Columbia (Arai and Brinckmann-Voss 1980; Gardner and Szabo 1982). The Copepoda and Amphipoda are apparently much less diverse in the northern Gulf than in the Bering Sea (Cooney 1981). Since the collection techniques have generally been similar in these two regions (vertical tows, mostly upper 150-200 m), and the database roughly the same size, it seems possible that the Bering Sea may host a mixture of both sub- arctic and arctic species. This mixture may account for the difference in Copepoda and Amphipoda diversity. (Motoda and Minoda 1974). Table 10-1. Numbers of species and generic composites reported for the Gulf of Alaska and southern Bering Sea. Taxon Gulf of Alaska3 Bering SEAb Cnidaria 42 41 Ctenophora Polychaeta Mollusca 3 9 9 1 17 8 Cladocera 5 2 Ostracoda 4 7 Copepoda Cumacea 76 3 111 8 Mysidacea 10 20 Isopoda Amphipoda Euphausiacea Decapoda Chaetognatha Larvacea 3 29 8 14 5 4 67 7 13 6 2 Thaliacea 2 0 Osteichthys Total 64 290 27 337 ^Appendix I bCoone> 1981 53 140 ZOOPIANKTON 287 60 120 Bering Sm .. jPSTy — i r-| [— /',/,», William I Sound I (iulftifAUulu ^^^\<\^\ \ \ukr Bay 1'nfl ii' mil) \ (■III/ Cull Of Alaska studv area » Ocean Station 1 150 Figure 10-1 Locations of data sets used to describe the distribution, abundance, and production of zooplankton covered in this chap- ter. Large study areas are depicted by dark, shading. Zooplankton communities in the Gulf of Alaska are numerically dominated by relatively few species; approx- imately 30 species constitute the numerically common taxa, with copepods being the most numerous (Table 10-2). Cooney (1975) reports 14 species and 2 generic composites as common in the northern Gulf of Alaska (NEGOA). All but one of these categories appear on the list of common species from OSP and the western Gulf of Alaska (WEGOA). Four- teen of 25 taxa from OSP are common to both the other locations, while 18 taxa are common to at least one of the other locations. There are no taxa (common or otherwise) listed for OSP that do not occur at the other locations. Damkaer (1977) reports 19 species and four generic com- posites from lower Cook Inlet (LCI) (including Kachemak Bay). Nine taxonomic categories listed for this inshore area are also commonly found at OSP. These listings demonstrate a continuity in the subarctic oceanic zooplankton community that spans roughly a thou- sand nautical miles — from OSP to Kodiak Island. Unlike the southeastern Bering Sea (Cooney 1981), a mixed assemblage of oceanic and neritic species inhabits the entire shelf and coastal zone including sounds, fjords, and protected inside waters. Life History Considerations Scientists have long recognized that the oceanic produc- tion cycle in the subarctic Pacific differs from the cycle in most other temperate latitude oceans. In spite of sufficient year-round nutrients and illumination in the surface waters, subarctic Pacific waters lack a well-defined spring phytoplankton bloom. This lack is attributed to the evolu- tion of a specialized grazing community. Heinrich (1957, 1962) and Beklemishev (1957) suggested that seasonally non-varying stocks of oceanic phytoplankton in the north- ern North Pacific Ocean result from intense grazing by her- bivorous copepods. Unlike Calanus finmarchicus in the North Atlantic, the large calanoid copepods in the Pacific subarctic, Neocalanus cristatus and N. plumchriis, reproduce at depth in late winter when primary production is still light-limited. This places their annual broods in the photic zone ahead of the seasonal phytoplankton growth period. The energy for their egg pro- duction comes from lipid reserves stored at the sea surface during the previous year's phytoplankton production cycle. This ability to anticipate and reproduce before seasonal phytoplankton growth, rather than in response to it, assures an extremely close coupling between plant and animal stocks. This coupling eliminates the classic lag period observed in other high-latitude oceans. Because of the intensity of the grazing afforded by this reproductive strat- egy, the seasonal biomass increase at OSP occurs at the sec- ondary (zooplankton) rather than primary (phytoplankton) level (Parsons 1965; Fulton 1983). A third large calanoid, Eucalanus bungii, augments oceanic grazing by producing surface broods later in the spring and summer when much of the Neocalanus biomass is descending to its overwintering and reproductive depths far below the surface. Together, these three copepods con- tribute as much as 75% to the net zooplankton biomass (>0.333-mm mesh) in the upper 2,000 m of the open ocean (Miller, Frost, Batchelder, Clemons, and Conway 1984). The medium-sized copepod, Metridia pacifica, is also an impor- tant contributor to the oceanic biomass, particularly in the surface waters after the interzonal species have migrated to depth. Cooney (1975) reports a species of similar size, Cal- anus pacificns, as the most abundant near-surface oceanic 288 Biological Resources Table 10-2. Numerically common zooplankton and micronekton from oceanic and shelf regions of the Gulf of Alaska. Location Taxon OSP" NEGOAb WEGOA- LCId Cnidaria Hydrozoa Aglantha digitate X X Chaetognatha Sagitta elegans X X X X Eukrohnia hamata X X X Arthropoda Copepoda Aetideus sp. X Acartia clausi X X A. longiremis X X X X A. tumida X X Calanns marshallae X X C. pacificus X X X X C. glacialis X Neocalanus cristatus X X X X N. plumchrus X X X Eucalanus bungii X X X Centropages arcuicornis X Clausocalanus abdominalis X X Epilabidocera longipedata X Mesocalanus tenuicornis X Microcalanus spp. X X Metridia pacifica (= M. lucens) X X X X Eurytemora spp. X Oithona similis X X X X O. spinirostris X Pseudocalanus spp. X X X X Scolecithricella minor X Tortanns discaudatus X X Cyclopina sp. X Oncaea borealis X Tegastes sp. X Tisbe gracilis X Amphipoda Parathemisto libellula X P. pacifica X X X Cyphocaris challengeri X Hyperoche medusarum X Hyperia sp. X Euprimno sp. X Ostracoda Conchoecia spp. X X Cladocera Podon spp. X X Evadne spp. X Euphausiacea Euphaiisia pacifica X X X Thysanoessa inermis X T. longipes X X X X T. spinifera X X T. raschii X Annelida Polychaeta Tomoptern spp. X Mollusca Pteropoda Limacina helicina X X Clione limacina X Cephalopoda Gonatus spp. X Chorda ta Larvacea Oikopleura spp. X X X X Fritillana borealis X Total 25 16 33 23 Ocean Weather Station F (LeBrasseur 1965b). ''Northeastern Gulf of Alaska (Cooney 1975). 'Western Gulf of Alaska (Kendall, Dunn, Wolotira. Bowerman, Day, Matarese, and Munk 1980: Vogel and McMurray 1986). dLowerC.ook Inlet (Darnkaer 1977). calanoid during late summer and early fall in the northern Gulf of Alaska. The life histories of the shelf and coastal neritic species exhibit a more classic response to the annual primary pro- duction cycle. The abundant small copepods, Pseudocalanus spp., Acartia spp., and Centropages abdominalis, build their late spring and summer populations following the spring phy- toplankton bloom. All produce from one to several genera- tions, depending upon food availability and temperature. Calanus marshallae, a medium-sized neritic copepod, is also most numerous during the summer months after overwin- tering adults have fed and reproduced. To date, there is no evidence that this latter species produces more than one generation each year in either the Gulf of Alaska or the southern Bering Sea (Smith and Vidal 1984; Vogel and McMurray 1982). Ctenophores and small cnidarians make up a relatively unimportant portion of the seasonally varying zooplankton stocks in the northern and western Gulf of Alaska, unlike their numbers in the more southerly waters bordering the British Columbia coastline and in the protected straits and sounds (Cooney 1975; Vogel and McMurray 1982). However, midsummer blooms of larvaceans are not uncommon, as is also the case in waters further south (Harrison, Fulton, Tay- lor, and Parsons 1983). Seasonality in Abundance and Biomass The Oceanic/Slope Community Kendall, Dunn, Wolotira, Bowerman, Dey, Matarese, and Munk (1980) report seasonal variations in total zooplankton biomass as mean settled volumes for nearshore, shelf, and slope locations in the western Gulf of Alaska near Kodiak Island (Fig. 10-2). The seasonal variations for a 150-m water column in the slope regime range from a low of 9.5 g/m2 in the winter to a high of 65.1 g/m2 in the summer. Cooney (unpubl. NEGOA data) measured a seasonal high of 19.9 g/m2 in May, falling to 3.3 g/m2 in late winter for the north- ern portion of the Gulf of Alaska (Table 10-3). Further to the west, Larrance (1971) reported a summer high volume of 29.4 g/m2, and a winter low of 7.4 g/m2. This seasonality com- pares with a high of 30.2 g/m2 and low of 1.5 g/m2 based on observations at OSP (McAllister 1969; LeBrasseur 1965b). Thus, over broad areas of the open Gulf of Alaska, seasonal variations in standing stock of near-surface zooplankton are roughly comparable, with the largest seasonal variability occurring at OSP, and the smallest variability occurring at locations to the north and west. A considerable portion of the seasonal biomass variation that occurs in the slope and oceanic regions probably reflects the life histories of three interzonal copepods: Neo- calanus cristatus, N. plumchrus, and Eucalanus bungii. These large species are present at some stage of development in the upper 150 m for at least 10 months of each year (Miller^ al. 1984). Unlike populations that occur in the deeper inside waters of British Columbia (Fulton 1973) and Alaska (Cooney, Urquhart, and Barnard 1981), the oceanic species demonstrate far less synchrony in their reproduction. Therefore, a variety of copepodid stages occur together, both at depth and in the surface waters. Zooplankton 289 E 06 I 5 05 a 04 - 01 Shell ()< ean/Slope Nr. ti -shore Winter (Feb— Mar) Spring (Mar— Apr) Summer (Jun-jul) Fall (Oci— Nov) Figure 10-2 Seasonal variability in zooplankton biomass near Kodiak Island, Alaska, based on samples collected with 60-cm bongo nets with 0.333-mm mesh. (Modified from Kendall et al. 1980.) Although the oceanic biomass of net zooplankton is dom- inated by the large interzonal copepods, several other taxa contribute to the seasonality. The smaller copepods, Calanus pacificas and Metridia pacifica, occur abundantly and at differ- ent times of the year. C. pacificus exhibits a strong seasonal signal with its highest amplitude occurring in the fall. M. pacifica populations are less variable with time, but have been reported as being the most numerous in late winter and spring (LeBrasseur 1965b). The even-smaller species, Pseiidocalanus spp., Scolecithricella ovata, Pseudocalanus parvus, the larger species are less abundant in the near-surface waters. The chaetognath, Sagilla elegans, is most common in the summer and fall months, as are the pteropods, lAmacina heliana and Clione limacina. Kendall et al. (1980) report chaetognaths occurring in densities of about 6 organisms/m:< in the summer, fall, and winter months in slope waters near Kodiak Island. Likewise, the ostracods, Concfwecia spp., are present in concentrations of 1 to 2 organisms/ms with the highest values occurring in the summer. The most common amphipod, Parathemisto pacifica, is most numerous in the summer and fall months. Adult euphausiids, Euphausia pacifica and Thysanoessa lang- ipes, reach peak densities in the winter. Oikopleura spp. occur most abundantly in the open ocean in the summer. In oceanic surface waters bordering the shelf, the zooplankton community composition reflects a distinct neritic cast in the summer and early fall as the shallower water assemblage grows and spreads seaward (Table 10-4). The Shelf Community Cooney (unpubl. data) measured 30.6 g/m2 injuly and 6.2 g/m2 in February (150-m water column) for the northeastern portion of the Gulf. This compares with summer values of 78.8 g/m2 and winter values of 6.3 g/m2 measured by Kendall et al. (1980) further to the west over the shelf near Kodiak Island. Since these studies were conducted in different years and with different nets, there is no way to determine whether the summer differences represent interannual, location, or merely sampling variability. Table 10-4. Seasonal variations in abundance by rank order for WEGOA offshore locations (Vogel and McMurray 1986). Rank Order Month ana uu/iona spp ., are an mos t apparent during times wnen March 1978 June 1978 Table 10-3. 1 Neocalanus plumchrus Pseudocalanus spp. Zooplankton stand ing stocks (in mg/m3) for the Gulf of Alaska. 2 3 4 5 6 Pseudocalanus spp. Me I rid i a spp. Neocalanus crislatus Limacina helicina Scolecilhricella minor Metridia spp. Neocalanus plumchrus Location Winter Spring Summer Fall Acarlia longiremis Eucalanus bungii Acarlia tumida OSP" NEGOA" 1. Shelf 2. Oceanic 10.0 41.2 22.8 88.0 140.8 132.8 190.0 168.1 33.3 80.0 70.2 25.6 7 8 9 10 Oikopleura spp. Sagitta spp. Oithona spp. Cnidarians (unidentified) Centropages abdominalis Calanus marshallae Oikopleura spp. Parathemislo pacifica WEGOAc 42.0 112.0 525.0 77.0 1. Shelf 2. Oceanic 63.0 70.0 434.0 70.0 October 1978 Fluri \kn 1979 LCId - 5,010.0 1,440.0 - Prince William 1 Acarlia longiremis Pseudocalanus spp. Sound'1 - 1,890.0 2,060.0 2,290.0 2 Metridia spp. Metridia spp. Russell Ejord*" - 110.0 470.0 250.0 3 Pseudocalanus spp. Si nlei illicit ellu minor Strait of Georgia1 - 100.0 - 800.0 4 5 6 7 8 9 10 Oithona spp. Calanus marshallae Parathemisto pacifica Limacina helicina Sagitta spp. Oikopleura spp. Parathemisto pacifica Neocalanus plumchrus Conchoecia spp. Ocean Weather Station PaPa (Fulton 1983). ''Northeastern Gulf cif Alaska (R.T. Cooney, University of Alaska, unpubl 'Western Gulf of Alaska (Kendall el al. 1980) (settled volumes converted). data). Calanus marshallae Limacina helicina Sagitta spp. Oithona spp. ( nid. ii i.nis i unidentified) dLowerCook Inlet (I) cReeburgh, Muench, anikaer 1977) (sett tnd Coonev 1976. ed volumes co nvcrted). 'Harrison et al. 1983. 290 BlOKX.k Al RlSOUKC IS Zooplankton and micronekton communities on the shelf are composed of a mixture of oceanic and neritic species (Table 10-5). Expressed in the rank order of their abun- dance, the copepods Pseudocalanus spp., Metridia spp., Acartia longiremis, A. tumida, Calanus marsliallae, Neocalanus plumchrus, N. cristatus, Eucalanus bungii, Scolecithrkella minor, Oithona spp., and Centropages abdominalis all occur in the top ten rankings at least once each season. Unidentified cnidarians, medusae, and euphausiids, the cladocerans Podon spp. and Evadne spp., the chaetognaths Sagitta spp., the pteropod Lim- acina helkina, and larvaceans Oikopleura spp. complete the list of dominant zooplankton and micronekton found on the shelf. Seasonally, the zooplankton community shifts from its oceanic domination in late winter through early spring, to a greater neritic influence in mid- to late-summer and fall. Neocalanus spp. drop out of the ten most abundant taxa in July and August, being replaced by the cladocerans, Podon spp. and Evadne spp. Centropages abdominalis and Acartia long- iremis become more prominent as the season progresses from winter through summer. Sagitta spp. are most numer- ous in the fall, winter, and early spring, as are adult Thy- sanoessa inermis (Kendall et al. 1980). Protected Inside Waters, Fjords, and Sounds Few studies have focused on zooplankton and micronek- ton populations in protected inside waters bordering the Gulf of Alaska (Damkaer 1977; Wing and Reid 1972; VTN 1983). A description of the pelagic ecosystem in the Strait of Georgia (Harrison et al. 1983) is considered first because of its thoroughness and seasonal coverage. Three distinct com- munities were described in this deep ( < 400 m) basin: an epi- pelagic community, a mid-water community, and a deep- water community (Table 10-6). The epipelagic community extends from the surface to the base of the mixed layer, and is generally composed of small copepods. These organisms are supplemented in the Table 10-5. Seasonal variations in abundance by rank order for WEGOA inshore locations (Vogel and McMurray 1986). Rank Order Month 1 2 3 4 5 6 7 8 9 10 March 1978 Calanus'1 copepodites I —II I Pseudocalanus spp. Metridia spp. Acartia longiremis Acartia tumida Oikopleura spp. Neocalanus plumchrus Neocalanus cristatus Cnidarians (unidentified) Scolecithrkella minor April 1978 Pseudocalanus spp. Calanus copepodites I— III Neocalanus plumchrus Acartia tumida Metridia spp. Neocalanus cristatus Oikopleura spp. Scolecithrkella minor Acartia longiremis Limacina helkina May 1978 Pseudocalanus spp. Acartia longiremis Calanus marshallae Acartia tumida Metridia spp. Centropages abdominalis Calanus copepodites I — III Oithona spp. Limacina helkina Medusae (unidentified) 1 2 3 4 5 6 7 8 9 10 June 1978 Pseudocalanus spp. Acartia tumida Acartia longiremis Calanus marshallae Metridia spp. Neocalanus plumchrus Cnidarians (unidentified) Centropages abdominalis Eucalanus bungii Scolecithrkella minor July 1978 Pseudocalanus spp. Acartia longiremis Calanus marshallae Centropages abdominalis Metridia spp. Podon spp. Oikopleura spp. Parathemisto pacifica Eucalanus bungii Oithona spp. August 1978 Acartia longiremis Pseudocalanus spp. Podon spp. Centropages abdominalis Oikopleura spp. Calanus marshallae Oithona spp. Metridia spp. Limacina helkina Parathemisto pacifica 1 2 3 4 5 6 7 8 9 10 November 1978 Acartia longiremis Metridia spp. Pseudocalanus spp. Oithona spp. Calanus marshallae Sagitta spp. Parathemisto pacifica Limacina helkina Calanus pacificus Eucalanus bungii Ini Indes Neocalanus spp. copcpocliies ZOOPIANKTON 291 Tabic 10-6. Zooplankton communities in the Strait of Georgia, B.C. (Harrison el al. 1983). I)l 1M1I /<>\l Win i i k Si aso\ SPRING Si \i\ii k 1- \i i Epipelagic (0-100 m) Midwater (100-250 m) Deepwater (>250 m) Pseudocalanus spp. Paracalanus parvus Oithona helgolandica Corycaeus sp. Euphausia pacifica3 Pasiphae pacifica' Cyphocaris challengeri3 Tomopteris septentrionalU Neocalanits plumchrus Calanus marshallae C. pacificus Metridiapacifica Sagitta elegans Aglantha digitate-' Aegina citrea Pleurobrurhin spp. Phialidium sp. Oikopleura sp. Neocalanus plumchrus Calanus marshallae C. pacificus Pseudocalanus spp. •nDiel migration into the epipelagic zone at night. spring by large numbers of the early stage copepodids of Neocalanus plumchrus that are recruited to the surface waters along with adult Calanus marshallae and C. pacificus. Both small and large species respond to the spring phytoplank- ton bloom by rapidly increasing their population biomass. By mid spring, N. plumchrus reaches its biomass high at 30 g/m2 (upper 20 m), during which time Pseudocalanus spp. show a high of 4 g/m2. Calanus marshallae follows with highs of 10 g/m2 in the late spring. Euphausia pacifica reaches its seasonal peak of 14 g/m2 as a diel migrator into the sur- face waters in late fall and winter. Spring is also the time when the cnidarian Phialidium sp. and the cteno- phore Pleurobrachia sp. begin a rapid increase in number and biomass. The jelly-like zooplankton, including Oikopleura sp., reach seasonal highs in the summer and fall months, along with Sagitta sp. and amphipods. Later in the fall, small blooms of C. marshallae, C. pacificus, Metridia pacifica, and Pseudocalanus spp. occur in response to renewed phy- toplankton growth. During the late fall and winter, the epi- pelagic community is composed mainly of the small copepods Pseudocalanus spp., Paracalanus parvus, Oithona helgolandica, and Corycaeus sp., supplemented by Euphausia pacifica during the hours of darkness. At this time, the over- wintering populations of A', plumchrus have migrated below 250 m in the Strait. The midwater community between 100 and 250 m is dom- inated primarily by the euphausiid Euphausia pacifica (dur- ing the day), the glass shrimp Pasiphaea pacifica, the amphipod Cyphocaris challengeri, the polychaete Tomopteris septentrionalis, and hydromedusae that include Aglantlui digi- tate and Aegina citrea. Most of these species also migrate into the epipelagic zone during darkness. The deep-water or mesopelagic community below 250 m is dominated by the overwintering herbivorous copepods, Neocalanus plumchrus, Calanus marshallae, C. pacificus, and Pseudocalanus spp. N. plumchrus enters a diapause in late fall in the copepodid stage V (CV), and later molts to become an adult. Spawning occurs at depth from January through April. The other species migrate to the surface either as CV or adult stages. Once at the surface, they first feed and then reproduce. Zooplankton tows made from 400 m to the sur- face yielded 0.8 g/m3, or 320 g/m2 in October and November. Most of this biomass is made up of the deep overwintering copepods. Seasonal lows from zooplankton tows (also 400 m to the surface) occur in April and May when the biomass is reduced to 40 g/m2. These lows occur mostly in the surface waters. Considerably less is known about the zooplankton and micronekton communities of Alaska's inside waters. Wing and Reid (1972) reported zooplankton data for samples col- lected between 1962 and 1964 in surface waters of Auke Bay and vicinity. Unfortunately, this report provides no syn- thesis of seasonal patterns or any interpretation of results. Damkaer (1977) reports settled volumes for Prince William Sound and for a series of locations in lower Cook Inlet. Sam- ples taken in the fall in Prince William Sound had settled volumes of — 770 g/m2 for a water column 730 m deep. Much of this biomass was associated with Neocalanus plum- chrus that was overwintering at depths below 300 meters. A diel migration of copepods, amphipods, euphausiids, and pteropods contributed to an increase in the night biomass in the upper 100 meters. Cooney, Urquhart, Neve, Hilsinger, Clasby, and Barnard (1978) and Cooney et al. (1981) describe the zooplankton com- munity in the upper 25 m during the spring and early sum- mer months in Prince William Sound. The mixture of neritic and oceanic species that was numerically dominated by copepods suggests that this large enclosed basin is influ- enced by circulation processes originating outside the Sound. Pseudocalanus spp., Acartia longiremis, and Oithona sim- His were consistently the most numerous zooplankters. The 292 Biological Rlsources only seasonal observations in Prince William Sound demon- strate a succession in numerical dominance for large zoo- plankton beginning with N. plumchrus, Calamus marshallae, and Sagitta elegans in late spring, slutting to C. marshallae, Metridia okhotensis and M. pacifica, and Thysanoessa raschii in mid-summer, followed by Sagitta elegans and M. pacifica in the fall and winter (Cooney, Redburn, and Shiels 1973). In lower Cook Inlet, including Kachemak Bay, zoo- plankton populations vary seasonally, with the biomass in the upper 25 m reaching lows of 1.8 to 10.5 g/m2 in the early spring and highs of 267.8 to 542.2 g/m2 in the late spring and summer months (Damkaer 1977). These spring and summer stock estimates seem somewhat high for a shallow environ- ment, and may be influenced by measurable amounts of phytoplankton (mesh size, 0.211 mm). Similarly, an upper 150-m summer measurement of 242.2 g/m2 (reported for a location in the oceanic Gulf of Alaska upstream from Kodiak Island), is roughly four times the oceanic seasonal high measured in a nearby area by Kendall et al. (1980). Reducing the spring and summer standing stock estimates in lower Cook Inlet bv this difference provides what appears to be more reasonable estimates of between 67 and 135.6 g/m2 for seasonal highs. Conversely, the higher values reported by Damkaer (1977) may include large quantities of small zooplankton and meroplankton missed by the larger- mesh nets. The zooplankton community in Kachemak Bay and lower Cook Inlet is also composed of a mixture of oceanic and neritic species. During the months of April through August, barnacle nauplii and crab zoea contribute large numbers to the meroplankton. During the spring and sum- mer months, the small copepods, Pseudocalanus spp., Acartia longiremis, and Oithona similis, numerically dominate the community (Damkaer 1977). Annual Production Few attempts have been made to measure secondary pro- ductivity in any of the major hydrographic regions of the Gulf of Alaska. McAllister (1969) estimated the annual sec- ondary production at 13 g C/m2y for OSP based on the rate at whicb phytoplankton was grazed by oceanic herbivores and assuming tbat sinking losses were negligible. If it can be assumed that, as a first approximation, zooplankters (including microzooplankton) ingest all of the annual pro- duction (as hypothesized by Heinrich 1957, 1962; Beklemishev 1957), and further that 30% of this material is used for growth (Copping and Lorenzen 1980), then some additional estimates of secondary production can be calcu- lated from other measures of oceanic annual primary pro- duction. Koblents-Mishke (1965), in a summary of data from the Pacific Ocean, estimated the annual primary produc- tion for the mid-subarctic region to be between 55 and 91 g C/m2y, with between 35 and 55 g C/m2y occurring in the transition zone. Although these estimates were admittedly subject to error because of the methodology, they nonethe- less generally agree with those estimates reported by other investigators (Larrance 1971; Anderson 1964; and McAllister 1969). Under the assumption that the annual contribution is Table 10-7. Zooplankton annual production estimates for the oceanic Gulf of Alaska and Strait of Georgia. Annual Al'THOR Method Production g C/m.2 McAllister 1969 Phytoplankton grazing losses 13.0 Parsons et al. 1969 Neocalanus plumchrus growth; 81 mgC/m2/d 9.72B This paper; using 30% phytoplankton 10.5-27.3" Koblents-Mishke 1965 production Larrance 1971 30% phytoplankton production 24-30" Calculated for a 120-d growth period "Assumes all the primary production is grazed and 30% of what is ingested appears as growth entirely grazed by zooplankton, estimates of secondary pro- duction range from a low of 10.5 g C/m2y to a high of 30 g C/m2y (Table 10-7). Measures of zooplankton production for shelf and inside-water environments are practically non-existent. Parsons, LeBrasseur, Fulton, and Kennedy (1969) report production of 81 mg C/m2d for Neocalanus plumchrus in the Fraser River plume. If this rate were sustained for the four months that N. plumchrus is in the surface waters, then pro- duction on the order of 9.72 g C/m2 would be realized. How- ever, since the measured annual increase in zooplankton standing stock was 18.9 g C/m2y (not including losses to mor- tality) for the deeper portion of the Strait of Georgia, the N. plumchrus contribution represents a substantial, but unknown fraction of the total annual secondary production. Cooney and Coyle (1982) report zooplankton grazing rates of 76 mg C/g dry weight of grazers per day in the mid- dle-shelf domain of the southeastern Bering Sea (compara- ble community, and similar temperatures in April and May). If this value is applied to spring, summer, and fall zoo- plankton stocks occurring over the shelf near Kodiak Island, and if 30% of the material ingested can be assumed to go to growth, then the annual zooplankton production would be — 32 g C/m2y (Table 10-8). This value is somewhat less than Table 10-8. Seasonal zooplankton production rates for shelf populations in the WEGOA area (Kendall et al. 1980). Standing Stock3 Ingestion1" Production0 Season mg/m2 mg C/m2d mg C/m290d Spring Mar-May 2,520 192 5,171 Summer Jun-Aug 11,813 898 24,239 Fall Sep-Nov 1,733 132 3,555 Total 33.0 g C/m2y ;lDry wt calculated as 15% wet wt (150 m water column). "Using Cooney and Coyle (1982); 76 mg C/g dry wt 'grazer'/d. 'Using 30% gross growth efficiency and a period of 90 days. ZOOPIANKTON 293 Table 10-9. Seasonal zooplankton production rates lor Russell Fjord, Alaska (Reeburgh efai. 1970). Standing Stock" Ingest noNb Production' Si \m>\ mg/m- mg C/m-d mgC/m290d Spring Mar-May 3.380 257 6,939 Summer Jun-Aug 14,040 1,067 28,809 Fall Sep-Nov 7,460 467 Total 15,309 51.1 g C/m*y aMeasured dry \\t; /noplankters >()..">71 mm, ''Using Cooney and Coyle (1982); 76 mg C/g dry wl gia/er'/d. the 51.1 gC/m2y that was obtained by using the same method on standing stock data reported by Reeburgh, Muench, and Cooney (1976) for Russell Fjord, Alaska (Table 10-9). Finally, since most of the estimates of primary produc- tion for the fjords and inside waters range between 100 and 300 g C/m2y, it seems unlikely that the annual secondary production will exceed 10 to 20% of these values. Thus, the zooplankton production, though largely unknown, is proba- bly greater than 10 g C/m'-'y and less than 60 g C/m2y in these protected coastal environments. Oceanographic/Ecological Significance Practically nothing is known about broad-scale abun- dance distributions of zooplankton in the open Gulf of Alaska. Parsons, Giovando, and LeBrasseur (1966) report generally higher copepod stocks around the northern, east- ern, and southern periphery of the oceanic gyre. They made this determination using averages for areas composed of 2° latitude and 10° longitude, and based on collections made during 1962 and 1963. This places the highest surface con- centrations of copepods in portions of the subarctic and Alaska Current systems. Wickett (1967) concluded that, given this general pattern of distribution, concentrations of zooplankton along the California coast and in the eastern Bering Sea could be cor- related with interannual variations in Ekman transport computed at seven locations in the northeast Pacific and Gulf of Alaska. In years following an above-average south- erly component of surface flow, zooplankton volumes were higher than average off California. Conversely, under these same conditions, Bering Sea zooplankton populations were diminished. Wickett suggested that during those years when the southerly component of Ekman transport was strongly developed, more oceanic zooplankters were deflected southward into the California Current and fewer were deflected into the Alaska Current/Alaskan Stream. Since the transit time to these adjacent areas is roughly one year, the effects of transport variations in the Gulf lagged by this amount of time. Frost (1983) found that there was considerable interan- nual variation in the standing stock at OSP. These dif- ferences showed a weak positive correlation with surface salinities measured at the same location, as had previously been noted by Wickett (1907). However, since plant growth is apparently not limited by nutrients, it seems unlikely that zooplankton production is enhanced either by increased upwelling or by wind mixing as suggested by the rela- tionship with salinity. While the large-scale distributions of oceanic zoo- plankters are only vaguely known, both seasonal and ver- tical variations in abundance and biomass of oceanic spe- cies have been described in detail for OSP and other locations in the subarctic Pacific (Fulton 1978, 1983; Heinrich 1968; LeBrasseur 1965b; Marlowe and Miller 1974; Miller et al. 1984; Sekiguchi 1975; and Vinogradov and Ara- shkevich 1969). The most obvious feature is the approx- imately twenty-fold increase in surface layer biomass (upper 150 m) associated with the annual growth of the net plankton community. This community is dominated by the interzonal copepods, Neocalanus cristatus, N. plumchrus, and Eucalanus bungii. The rise in biomass to a spring peak in June tapers off during the fall and closely tracks the seasonal vari- ation in light. This phenomenon, coupled with the fact that the oceanic phytoplankton standing stock remains rela- tively constant throughout the year (most values <0.4 mg Chi fl/m3), suggests that zooplankton grazing must play a sig- nificant role in balancing the primary productivity. That hypothesis has recently been critically examined at OSP (Frost, Landry, and Hassett 1983; Miller et al. 1984). It is now known that the reproductive strategies of the major grazers are much more complex than originally thought, and that N. plumchrus and N. cristatus exhibit behavioral and morphological adaptations that allow them to very effi- ciently exploit the phytoplankton stocks. Most recently, Mil- ler (C. Miller, Oregon State University, pers. comm., 1985) has demonstrated that two distinct forms of N. plumchrus are present at OSP. These forms differ in color, size, and breed- ing cycle — one is reddish, smaller than 4 mm as adults, and reproduces in mid-summer, while the other (the typical Neo- calanus plumchrus) is orange, larger than 4 mm, and reproduces in the fall. It is unknown how this discovery will affect the present understanding of how the zooplankton community functions in the open northeast Pacific Ocean. In addition to Miller's discovery, it is now also known that the large herbivorous copepods are partitioned vertically in the water column during their upper-layer development. Both forms of Neocalanus plumchrus occur above the seasonal thermocline (upper 30 m), whereas N. cristatus and Eucalanus bungii are generally restricted to depths below the thermocline. Cooney (1986) demonstrates the seasonal presence of the oceanic inter-zonal copepods over the shelf of the northern Gulf of Alaska. This presence is associated both with the time these species reside in the wind-influenced surface layer of the bordering ocean and with the duration of the shelf convergence season that lasts from October to April each year (Royer 1981). These and other oceanic zoo- plankters are dominant members of the shelf and coastal communities, a fact that adds support to the notion that the bordering ocean may be the source for substantial amounts of organic matter that is adverted shoreward in the season- ally persistent onshore Ekman flow (Cooney 1984). The Gulf 294 Bioux.k ai RisoLiRcis of Alaska shelf is unlike the middle shelf domain of the southeastern Bering Sea, which is isolated from oceanic influence by a strong mid-shelf frontal system. The consid- erably narrower shelf of the Gulf of Alaska has a much more advective environment due to influences by both the Alaska Current over and along the shelf break, and by the Alaska Coastal Current (ACC) that occupies the first 40 km from the beach seaward. The ACC originates in northern British Columbia, and continues north and west around the periph- ery of coastal Alaska as far as Unimak Pass on the Alaska Peninsula (Rover 1983). Interaction between these two cur- rents (where the shelf is <50 km wide) presumably provides a mechanism to mix and transport the coastal and oceanic faunas over and along the shelf. This mechanism, combined with the wind-induced onshore Ekman flow, assures that near-surface (upper 200 m) zooplankters of oceanic origin become a seasonal part of the shelf/coastal zooplankton communities. The degree to which the shelf is enriched by oceanic bio- mass can be estimated by measuring both the standing stocks and the rate of onshore surface flow. Cooney (1984) proposes that over an eight-month period from March to November of each year, ~ 10 x 106 mt of zooplankton bio- mass are advected shoreward from the upper 50 m of the bordering ocean. This biomass then moves into the outer edge of the ACC along 1,000 km of coastline in the northern Gulf of Alaska. This advected zooplankton biomass com- pares to the ~ 2 x 106 mt estimated as the production yielded by zooplankters resident in the ACC. If this calcu- lated contribution is at all accurate, the bordering ocean supplies an immense and significant amount of biomass to both shelf and coastal food webs each year. Mesoscale processes such as fronts and eddies concen- trate forage species for higher trophic levels, and may also be extremely important in the process of organic matter transfer. Cooney (1984) suggests one such mechanism that may be associated with vertical circulation patterns in the outer margin of the ACC. Interactions between either upwelling or downwelling in the front separating the ACC from the shelf waters, coupled with the distributions of oceanically derived zooplankters, point to periods when for- age biomass is concentrated in the frontal region of the ACC. This theoretical concentration may partially explain the apparent obligate use of the ACC by millions of out- migrating juvenile salmon each year ( Rogers, Ch. 15, this volume). The continuous counterclockwise flow of both the ACC and the Alaska Current/Alaskan Stream around the Gulf of Alaska implies a constant relationship between the upstream source regions and the downstream distributions for both oceanic and shelf/coastal zooplankton populations. Using a conservative estimate of 20 km/d for flow in the ACC (Royer 1981), and given the standing stock information for NEGOA shelf zooplankton (Table 10-3), it is possible to esti- mate the biomass of the zooplankton that is transported downstream each year. Under these conditions, approx- imately 1.5 x 106 mt of zooplankton are moved past fixed locations annually in a current 20 km wide and 100 m deep. In this context it is not surprising that the community com- position of populations in the northern and western por- tions of the Gulf of Alaska is similar to the fauna occurring at OSP. The system is at least partially closed as a gyre, and the cross-shelf Ekman flow and meander in the Alaska Cur- rent/Alaskan Stream both provide further means for mixing the oceanic and coastal communities. Even the zooplankton assemblages in Alaska's protected inside waters reflect an oceanic influence. The non-reversing nature of the flow further suggests that while population fluctuations that orig- inate in British Columbian and southeastern Alaska waters may retain their continuity until they are observed off Kodiak, the converse of that is not likely — except for popu- lations that retain their continuity while being circulated completely around the gyre. Zooplankton in the Gulf of Alaska serve as forage for higher trophic levels including fishes, marine birds, and mammals (Vogel and McMurray 1986; Appendix III). In addition to these consumers, larval fishes may depend on the early life-history stages of zooplankton, particularly the Copepoda, for their first feeding (Dagg, Clarke, Nishiyama, and Smith 1984). It has long been assumed, but rarely observed in nature, that most fish larvae enter a critical phase at the time when their yolk sac is nearly absorbed and they must begin external feeding (May 1974). At this time, the presence of sufficient quantities of appropriate kinds of food is thought to be extremely important. Copepod nau- plii have been described as one of these critical food items (Kamba 1977; Clarke 1978; Nishiyama and Hirano 1983; Lau- rence 1974; and Paul 1983). In this regard, Pseudocalanus is probably one of the most ecologically important genera affecting fish production in the Gulf of Alaska, particularly in the shelf and coastal zones. Pseudocalanus spp. continu- ously produce nauplii while food is available and conditions are favorable (McLaren 1978), thus providing food for first- feeding larvae from April through November of each year. The tiny cyclopoids, Oithona spp., may also be important in the diets of first-feeding larvae, both because of their small size (even as late stage copepodids) and their great abun- dance (Miller et al. 1984). Kendall et al. (1980) found that the greatest abundance of fish larvae occurred in both offshore and inshore regions near Kodiak during the summer when zooplankton stocks were also at their seasonal highs. Calanoid copepods, har- pacticoid copepods, euphausiids, decapod larvae, fish lar- vae, mysids, and pelagic amphipods are all known as food sources for a variety of species, ranging from both juvenile and adult pelagic and demersal fishes to sea birds and sev- eral whale species. Vogel and McMurray (1986) discuss relationships between fish, bird, and mammal consumer populations and the forage stocks in the WEGOA region. In the Kodiak area, the distribution of juvenile and adult walleye pollock was related to the distribution of both copepods and the eupha- usiids, Euphausia pacifiea and Thysanoessa spinifera. These two species are also forage for juvenile pollock (Rogers, Rabin, Rogers, Garrison, and Wangerin 1979). A similar rela- tionship was found for the larval Atka mackerel along the slope regime in this same area. In contrast, the distribution of herring in the inshore waters, including bays and chan- nels, was most strongly related to the abundance of copepods and cladocerans. The most abundant pelagic fish ZOOPLANKTON 295 collected over the shelf near Kodiak, the capelin (Harris and Hartt 1977; Kendall et al. 1980), was distributed spatially according to /ooplankton abundance, but was seasonally out of phase with the /ooplankton biomass. Distributions of Pacific sand lance were weakly related to both copepod dis- tribution and seasonal abundance. The occurrence and distributions of some marine birds were positively related to the distribution of their food. Shearwaters frequented areas of high euphausiid, copepod, and capelin densities. Since the capelin feed on copepods and euphausiids, and the birds on euphausiids and capelin, the concomitance is expected. Distribution of tufted puffins and black-legged kittiwakes was strongly correlated to areas with larval capelin, but their distribution was weakly corre- lated to distributions of euphausiids and copepods (Rogers et al. 1979). Five species of filter-feeding whales are found in the Kodiak area: minke, humpback, sei, fin, and blue whales (Science Applications, Inc. 1980; Calkins, Ch. 17, this vol- ume). Humpbacks occur most abundantly over the shelf in the vicinity of the major bathymetric trenches where oceanic copepod and euphausiid populations are high. Both humpback and sei whales forage on copepods, eupha- usiids, and planktivorous fishes such as capelin and herring (Nemoto 1957, 1970; Nishiwaki 1972). Conclusions 1. The composition of zooplankton communities in the Gulf of Alaska displays a homogeneity of species across oceanic, shelf, and coastal and inside waters. This composi- tion reflects both the influence of the open ocean on the shallower, protected environments and the highly advective nature of the overall system. The Gulf of Alaska appears closed, and coastal and shelf-break currents distribute pop- ulations over ~ 2,200 km of coastline from northern British Columbia to Unimak Pass, Alaska. 2. Copepods are the dominant taxa reported in samples taken from all marine environments in the Gulf of Alaska. In the oceanic domain, more than 70% of the biomass (nets of 0.333 mm mesh and larger) is associated with three spe- cies, Neocalanus cristatus, N. plumchrus, and Eucalanus bungii. A complex life history pattern, including ontogenetic migra- tions and reproduction at depth, places a mixture of these large copepods in the upper 150 m for at least 10 months of each year. 3. Recent studies tend to confirm the hypothesis that grazing by oceanic herbivores controls both the stock and the production of phytoplankton in the open ocean. Oceanic zooplankton standing stocks vary seasonally by as much as a factor of 20 (between 1.5 and 30.0 g/m2; upper 150 m), with somewhat higher winter values occurring along the northern and western continental margin. It is unlikely that the annual production of oceanic zooplankton exceeds the 30.0 g C/m2y figure. 4. Shelf and coastal zooplankton stocks vary in abun- dance and species composition according to the season. Winter and early spring populations are augmented by oceanic species that are moved into the shallower waters bv the seasonally persistent onshore Ekman transport. The numerical importance of the open ocean community is diminished during the summer and fall months when the shelf and coastal communities are dominated by a more neritic assemblage. At this time, the copepods Pseiulocakmus spp., Acartia longiremis, A. tumida, Calanus marshallae, Metridia spp., and Cenlropages abdomitialis are common. The marine cladocerans, Podon and Evadne, and the larvaceans, Oikopleura spp., are also evident during the summer. 5. Shelf and coastal zooplankton stocks exhibit growth cycles that respond to phytoplankton production. Winter and early spring stocks are lowest (3-10 g/m2), followed by substantial increases (30-78 g/m-') in the summer and fall. In the deeper inshore waters of the Strait of Georgia, seasonal variations in a 400-m water column range from a low of 40 g/m2 in the spring to a high of 320 g/m2 in the fall. Annual zooplankton production probably does not exceed 30 to 60 g C/m2y in shelf and coastal areas. 6. Zooplankton serve as forage for fishes, shellfishes, marine birds, and mammals. Copepod nauplii are critical in the diets of most larval fishes. In this respect, the prolific small copepods, Pseudocalanus spp. and Oithona spp., are probably extremely important in the life cycles of most pel- agic and demersal fishes. The larger copepods and eupha- usiids represent critical food items, particularly for marine birds, whales, and juvenile and adult pelagic fishes. 7. Our present understanding of both the zooplankton community structure and its function is flawed by our inade- quate understanding of the production of key species in both shelf and inside water environments. General seasonal cycles have been described for biomass, but very few attempts have been made to determine those factors that enhance or constrain population growth rates and how those factors might vary interannually. Sizable annual varia- tions in the returns of pink salmon (a species that feeds almost entirely on zooplankton and micronekton as juve- niles) suggest that the coastal, shelf, and oceanic environ- ments are all 'noisier' than our data sets portray. In addition, although the availability of food may not be the only factor affecting survival, it is probably extremely important. In this regard, information on mesoscale patchiness (1-10 km) is also lacking, although there is little doubt about its primary importance. Future Studies The zooplankton community plays a unique role in con- trolling the production cycle in the open portion of the Gulf of Alaska. Further, zooplankton are of significant trophic importance. Considering these facts, it seems appropriate to expand the more site-specific studies of zooplankton dis- tribution and abundance into broader, hydrographically defined domains such as currents, convergences, and diver- gences. Studies at this level of complexity will certainly bene- fit from a close working tie with physical oceanographers who use a variety of techniques, including mass balance, sat- ellite-tracked surface buoys, and multiple current meter deployments, to describe the Gulfs responses to seasonal wind and freshwater forcing patterns. 296 Biological Resources Recent advances in high-frequency quantitative acoustic sampling let investigators make hundreds of thousands of biomass measurements as routinely as they now take tem- perature and salinity readings both along cruise tracks that cross the currents and in upwelling regions which define the gyre in the northeast Pacific Ocean. While it is true that sur- veys of this kind still rely on net tows for identification of the zooplankton, the actual amount of direct sampling can be reduced to manageable limits. Euphausiids, which are likely to be as important in trophic exchange processes as copepods, are poorly sampled by conventional means. These organisms are particularly suited for acoustic census- ing, and knowledge of their mesoscale distribution and abundance will benefit from the use of quantitative sonic methods. Vast manpower and monetary resources have been expended on studies to determine how the oceanography of the northeast Pacific Ocean affects the production of com- mercially important fish and shellfish. These studies have generally lacked interdisciplinary coordination, and because of this, have been unfocused in terms of ecosystem function. Completion of the OCSEAP-sponsored research and its synthesis in this book will provide one of the first attempts — in a single volume — to assemble what is under- stood about the Gulf of Alaska. It is essential that this com- pilation not represent an end in itself, but rather become a point of departure for more focused oceanographic studies of the interrelationships between the living and non-living components of this system. In the spirit of the new initiatives to describe ocean productivity that are stated by the Divi- sion of Ocean Sciences, NSF, this is surely one area ripe for both continued and expanded research. Acknowledgments The author was assisted in the preparation of this man- uscript by formal reviews from C.B. Miller, J.D. Fulton, and S. Zimmerman. Their helpful suggestions and criticisms greatly strengthened the chapter. I am also indebted to R. Horner and W. Shiels for their skill in technically editing the manuscript. Helen Stockholm and the publications staff of the Institute of Marine Science, University of Alaska-Fair- banks are thanked for the many hours they spent preparing the chapter for review. Lastly, I thank the editor, Donald Hood, for inviting me to participate in this project. Funding support for the preparation of this chapter was furnished by the Minerals Management Service, Depart- ment of the Interior, through an interagency agreement with the National Oceanic and Atmospheric Administra- tion, Department of Commerce, as part of the Outer Conti- nental Shelf Environmental Assessment Program. It is my desire to dedicate this review of zooplankton in the Gulf of Alaska to my dear friend and mentor, the late Dr. T. Saunders English, Professor of Oceanography, University of Washington, Seattle, Washington. His dedication to oceanography, his inspiration as a colleague, and his bound- less enthusiasm for life infected all who were privileged to know him. It seems fitting that many of his friends and asso- ciates were in some way involved in the preparation of this monograph on the Gulf of Alaska. Tom would have liked that. Appendix I. Zooplankton and ichthyoplankton, reported in samples taken from the northern Gulf of Alaska (LeBrasseur 1965b; Cooney et al. 1973; Cooney 1975; Damkaer 1977; Kendall et al. 1980; Cooney et al. 1981; Vogel and McMurray 1986; VTN 1983; Wing and Reid 1972). Cnidaria Rathkea octopunctata Bougainvilla supercilliaris ( = B. multitentaculata) Euphysa japonica Hybocodon prolifer Calycopsis sp. Sarsia tubulosa S. princeps S. rosaria Leuckartiara octona L. nobilis L. breviconis ( = Neoturris breviconis) Perigonimus vesicarius Halimedusa typus Stomotoca atra Polyorchis penicillatus Obelia borealis Phialidium gregarium Aequorea aequorea ( = A. victoria) Melicertum octocostatum Halistaura cellularia Tiaropsidium sp. Staurophora mertensi Eutonina indicans Gonioncmus vertens Proboscidactyla Jlavicirrata Aglantha digitate Pantachogon haeckeli Aegina citrea Cunina globosa Lensia conoidea Muggiacea atlantica Dimophyes arctica Vogtia serrata Agalma elegans Chuniphyes multidentata Nanomia sp. Periphylla periphylla Nectopyramis diomedeae Amelia aurita Cyanea capillata Praya reticulata Crysaora melanaster Ctenophora Bolinopsidae infundibulum Beroe sp. Pleurobrachia pileus Polychaeta Pelagobia longicirrata Tomopteris septentrionalis T. pacifica ZOOPIANKTON 297 T. planktonis T. renata Plotohelmii tenius Autolytus sp. Typhloscolex mailer i Poeobius meseres Mollusca Limacma helicma ( = Spiratella pacified) Euclio pyramidata Clione limacma Gasteropteron pacificu m Rossia pact fun ElecUme sp. Chiroteuthis veranyi Galiteuthis armata Octopus sp. Cladocera Daphnia schodleri Evadne nordmatini E. tergestina Podan leuckarti P. polyphemoides Ostracoda Philomedes sp. P. trituberculatus Conchoecia alata minor C. elegans Copepoda Neocalanus cristatus ( = Calanus cristatus) N. plumchrus ( = C. plumchrus) Calanus marshallae C.pacificus Mesocalanus tenuicornis ( = Calanus tenuicornis) Eucalanus bungii Clausocalanus arcuicornis Microcala n us s p p . Pseudocalanus spp. Spinocalan us brevicaudatus Aetideus divergens A. pacificus Chiridius gracilis C poppei Bradyidius saanichi Gaetanus intermedins Gaidius tenuispinus G. simplex G. variabilis Pseudochirella sp. Pareuchaeta elongata P. sarsi Lophoth rix frontalis Amallothrix inornata Racovitzanus antarcticus Scaphocala n us magn us S. brevicornis Scolecithruella minor S. ovata I 'ndinella sp. Metridia curticauda M. okhotensis M. pacificu ( = M. lucens) M. princeps Pleuromamma scutulluta P. robusta Centropages abdominalis Paracalanus parvus Limnocalanus macrurus Diaptomus sp. Eurytemora americana E. pacifka ( = E. herdmanii) Lucicutia flavkornis L. ovalis Disseta scopularis Heterorhabdus tanneri H. compactus H. robustoides Heterostylites major Haloptilus pseudooxycephalus Candacia columbiae Pachyptilis pacificus Epilabidocera longipedata Acartia clausi A. longiremis A. tumida Tortanus discaudatus Microsetella rosea Harpactkus sp. Tegastes sp. Tisbe sp. Lubbockia wilsonae Pseudolubbockia dilatata Oncea conifera 0. borealis 0. parila 0. notopus 0. prolata Corycaeus anglicus Oithona helgolandica ( = 0. similis) 0. spinirostris Monstrilla helgolaruiwa M. longiremis M. wandlii M. canadiensis Cymbasoma rigidum Isopoda Grwrimosphaeroma oregonensis Idothea wosnesenskii Neosphaeroma oregonensis Cumacea Cumella sp. Diastylis dawsoni Vaunthompsonia sp. Mysidacea Acanthomysis ncphrophthalma A. pseudomacropsis Holnwsiella anomala Neomysis rayii N. kadiakensis N. nakazawai Pseiuiomma trumatum Meterythrops robusta Gnatlwpiwmia gigas Mysis oculata Amphipoda Andaniexis subabyssi Calliopius laeviusucla C. behringi Cypfwcam crmllengeri C. anonyx Eusiriella multkakeola Koroga megalops Hyperia medusarum hystrix Hyperocfie medusarum Monoculodes zernovi Orchomene sp. Parathemisto gracilipes P. pacifka P. libellula Phronima sedentaria Primno macropa Proscina birsteini Scina stebbingi S. borealis S. rattrayi Streetsia sp. Tryphaena malmii Lanceola pacifka Westwoodilla rectangulata Vibila australis Paraphronima crassipes Caprella sp. Paracallisoma alberti Rhachotropis natator Euphausiacea Eupliauski pacifica Thysanoessa inermis T. inspinata T. longipes T. raschii T. spin if era Tessarabrach ion oculata Stylocfieiron sp. Decapoda Pasiphaea pacifica Hymenadora frontalis Pandalus borealis P. danae P.jordani P. platyceros P. montagui tridens P. stenolepis Pandelopsis dispar Eualus pusiola 298 Bioioc.iC/U Resources C.rongoti alaskensis Sergestes si mi I is Chionoecetes spp. Paralithodes sp. Chaetognatha Eukrohnia hamata E. fowleri E. bathypelagica Sagitta elegans S. scrippsae Larvacea Oikopleura dioica 0. labradoriensis 0. vanhoeffeni Fritillaria borealis Thaliacea Salpa fusiformis S. maxima Osteichthyes Clupea harengas pallasii Mallotus vilbsus Tlialekhthys pacificus Bathylagus milleri B. pacificus Lampanyctus regalis Leuroglossus schmidti Stenobraxhius sp. 5. leucopsarus S. nannochir Protomyctophum crockeri P. thompsoni Gadus macrocephalus Theragra chakogramma Sebastes sp. Hexagrammos sp. H. decagrammus H. lagocephalus H. octogrammus H. stelleri Ophiodon elongatus Pleurogrammus monopterygius Anoplopoma fimbria Artedius spp. Clinocottus sp. Dasycottus setiger Gymnocanthus sp. Hemilepidotus spp. H. hemilepidotus Icelinus borealis Malacocottus zonurus Myoxocephalus spp. Radulinus asperellus Triglops sp. Liparis florae Lifucensis spp. Trkhodon trichodon Aptocyclus ventricosus Bathymaster sp. Anoplarchus insignis Ronquilus jordani Chirolophis polyactoceplialus Lumpenella longirostris Lumpenus sagitta L. maculatus Sticfiaeus puyictatus Lyconectes aleutensis Pholis sp. P. laeta Zaprora silenus Ammodytes hexapterus Atheresthes stomias Glyptocephalus zachirus Hippoglossoides elassodon Isopsetta isolepis Lepidopsetta bilineata Microstomus pacificus Platkhthys stellatus Psettichthys melanostictus Hippoglossus stenolepis Cyclothone sp. Chauliodus macouni Lycodapus mandibularis Gasterosteus aculeatus Appendix II. Zooplankton collected in Boca de Quadra fjord during 1982 (VTN 1984). Cnidaria Hydrozoans Anthomedusae Leuckartiara sp. Rathkea octopunctata Sarsia rosaria Bougainvilla sp. Leptomedusae Obelia sp. Phialidium gregarium Aequorea aequorea Limnomedusae Proboscidactyla flavicirrata Trachymedusae Aglantfia digitate Siphonophora Nanomia bijuga Lensia conoidea Muggiacea atlantica Dimophyes arctka Scyphozoans Amelia aurita Cyanea capillata Ctenophora Pleurobrachia pileus Annelida Polychaete larvae Tomopteris septentrionalis Rhynchonerella angelini Mollusca Gastropod larvae Limacina helkina Clione sp. Bivalve larvae Cephalopod larvae Cladocera Evadne nordmanni Podon leuckarti Ostracoda Conchoecia spp. Copepoda Calanoida Calanus marshallae C. pacificus C. plumchrus C. cristatus Eucalanus bungii Paracalanus parvus Mkrocalanus piisillus Pseudocalanus minutus Aetideus armatus Gaetanus simplex Pareuchaeta elongata Metridia okhotensis Metridia pacifka Centropages abdominalis Eurytemora sp. E. pacifka E. amerkana Candacia columbine Epilabidocera longipedata Acartia clausi A. longiremis Tortanus discaudatus Harpacticoida Microsetella rosea Harpactkus sp. Cyclopoida Oncaea borealis Corycaeus anglkus Oithona helgolandka 0. spinirostris Cirripeda Balanus sp. larvae Zoopiankton 299 Mysidacea Unidentified mvsid Isopoda Gnorimosphaeroma oregonensis Amphipoda ( '.yphocaris challenger i Orchomene sp. Parathemisto pacifica Prim no macropa Scina borealis Euphausiacea Euphausiid larvae Euphausia pacifica Thysanoessa raschii T. longipes T. inermis T. spinifera Chaetognatha Sagitta elegans Tunicata Oikopleura spp. Fritillaria borealis Ascidian larvae Appendix III. Planktivorous organisms off Kodiak Island classified by known food sources (Vogel and McMurray 1986). Calanoid Copepods juvenile salmonids capelin herring Pacific sand lance juvenile whitespotted greenling juvenile pollock juvenile rock sole juvenile yellowfin sole gray whale sei whale fin whale right whale Fish Larvae juvenile salmonids Pacific sand lance juvenile whitespotted greenling Harpacticoid Copepods juvenile salmonids capelin Pacific sand lance juvenile whitespotted greenling juvenile masked greenling juvenile pollock Pacific cod Mysids sand sole pollock Pelagic Amphipods juvenile chum salmon herring Euphausiids pollock Pacific Ocean perch yellow Irish lord yellowfin sole rex sole flathead sole juvenile arrowtooth flounder short-tailed shearwater tufted puffin black-legged kittiwake minke whale fin whale blue whale humpback whale Decapod Larvae Pacific Ocean perch herring smelt juvenile pink salmon pandalid shrimp 300 Biological Resources References Anderson, G.C. 1964 The seasonal and geographic distribution of primary productivity off the Washington and Oregon coasts. Limnology and Oceanography 9:284-302. Arai, M. and A. Brinckmann-Voss 1980 Hydromedusae of British Columbia and Puget Sound. Canadian Bulletin of Fisheries and Aquatic Science No. 204. 192 pp. Beklemishev, K.V. 1957 The spatial relationships of marine zoo- and phytoplankton. Trudy Instituta Okeanologii Akademiya nauk SSSR 20:253-278. (Translation: Marine Biology. B.N. Nikitin, editor. 1959. Ameri- can Institute of Biological Sciences, Wash- ington, D.C. pp. 206-226. ) Brinton, E. 1962 The distribution of Pacific euphausiids. Bul- letin of Scripps Institution of Oceanography 8:51-269. Clarke, M.E. 1978 Some aspects of the feeding biology of larval walleye pollock, Theragra chalcogramma (Pallas), in the south-eastern Bering Sea. M.S. Thesis, University of Alaska, Fairbanks, AK. 44 pp. Copping A.E. and CJ. Lorenzen 1980 Carbon budget of a marine phytoplankton- herbivore system with carbon-14 as a tracer. Limnology and Oceanography 25:873-882. Cooney, R.T. 1975 Environmental assessment of the northeastern Gulf of Alaska: zooplankton and micronekton. Final report to NOAA. Institute of Marine Sci- ence, University of Alaska, Fairbanks, AK. 159 pp. (4 microfiche). Cooney, R.T. 1981 Bering Sea zooplankton and micronekton communities with emphasis on annual produc- tion. In: The Eastern Bering Sea Shelf: Oceanogra- phy and Resources, Vol. 2. D.W. Hood and J.A. Calder, editors. Office of Marine Pollution Assessment, NOAA. Distributed by the Univer- sity of Washington Press, Seattle, WA. pp. 947-974. Cooney, R.T. 1984 Some thoughts on the Alaska coastal current as a feeding habitat for juvenile salmon. In: The Influence of Ocean Conditions on the Production of Salmonids in the North Pacific. W.C. Pearcy, edi- tor. Sea Grant Program, ORESU-W-83-001, Oregon State University, Corvallis, OR. pp. 256-268. Cooney, R.T. 1986 The seasonal occurrence of Neocalanus cristatus, Neocalanus plumchrus, and Eucalanus bungii over the shelf of the northern Gulf of Alaska. Conti- nental Shelf Research 5:541-553. Cooney, R.T. and K.O. Coyle 1982 Trophic implications of cross-shelf copepod distributions in the southeastern Bering Sea. Marine Biology (Berlin) 70:187-196. Cooney, R.T., D.R. Redburn, and W.E. Shiels 1973 Zooplankton studies. In: Environmental Studies of Port Valdez. D.W. Hood, W.E. Shiels, and EJ. Kelley, editors. Occasional Publication No. 3, Institute of Marine Science, University of Alaska, Fairbanks, AK. pp. 297-302. Cooney, R.T., D. Urquhart, and D. Barnard 1981 The behavior, feeding biology, and growth of hatchery released pink and chum salmon fry in Prince William Sound, Alaska. Alaska Sea Grant Report 81-5, Institute of Marine Science Report R81-4, University of Alaska, Fairbanks, AK. 114 pp. Cooney, R.T., D. Urquhart, R. Neve, J. Hilsinger, R. Clasby, and D. Barnard 1978 Some aspects of the carrying capacity of Prince William Sound, Alaska, for hatchery released pink and chum salmon fry. Alaska Sea Grant Report 78-4, Institute of Marine Science Report R81-4, University of Alaska, Fairbanks, AK. 98 pp. Dagg, M.J., M.E. Clarke, T. Nishiyama, and S.L. Smith 1984 Production and standing stock of copepod nauplii, food items for larvae of the walleye pol- lock Theragra chalcogramma in the southeastern Bering Sea. Marine Ecology — Progress Series 19:7-16. Damkaer, D.M. 1977 Initial zooplankton investigations in Prince William Sound, Gulf of Alaska, and lower Cook Inlet. Environmental Assessment of the Alaska Conti- nental Shelf Annual Reports of Principal Investiga- tors for the year ending 1977. 10(Receptors — fish, littoral, benthos):137-274. Frost, B.W. 1983 Interannual variation of zooplankton standing stock in the open Gulf of Alaska. In: From Year to Year: Interannual variability of the environment and fisheries of the Gulf of Alaska and the Eastern Bering Sea. W.S. Wooster, editor. Washington Sea Grant Publication 83-3, University of Wash- ington, Seattle, WA. pp. 146-157. ZOOPLANKTON 301 Frost, B.W., M.R. Landry, and R.P. Hassett 1983 Feeding behavior of large calanoid eopepods Neocalanits cristatus and N. plumchrus from the subarctic Pacific Ocean. Depp-Sea Research 301:1-13. Fulton, JJ). 1973 Some aspects of the life history of Calanus plumchrus in the Strait of Georgia. Journal of the Fisheries Research Board oj Canada 30:811-815. Fulton,J.D. 1978 Seasonal and annual variations of net zoo- plankton at Ocean Station P, 1965-1976. Fish- eries and Marine Service Canada Data Report No. 49. 89 pp. Fulton, J.D. 1983 Seasonal and annual variations of net zoo- plankton at Ocean Station P, 1956-1980. Cana- dian Fisheries and Aquatic Science Data Report No. 374. 65 pp. Fulton, J.D. and R.J. LeBrasseur 1985 Interannual shifting of the subarctic boundary and some of the biotic effects on juvenile salm- onids. In: El Nino North: Effects in the Eastern Sub- arctic Pacific Ocean. W.S. Wooster and D.L. Fluharty, editors. Washington Sea Grant Pub- lication 85-3. University of Washington, Seattle, WA. pp. 237-252. Gardner, G.A. and I. Szabo 1982 British Columbia marine Copepoda: an identi- fication manual and annotated bibliography. Canadian Special Publications, Fisheries and Aquatic Sciences No. 62. 536 pp. Harris, C.K. and A.C. Hartt 1977 Assessment of pelagic and nearshore fish in three Bays on the east and south coasts of Kodiak Island, Alaska. Research Unit 485. Environmental Assessment of the Alaskan Continen- tal Shelf, (hiarterly Reports of Principal Investigators April-June 1:483-688. Harrison, P.J. , J.D. Fulton, F.J.R. Taylor, and T.R. Parsons 1983 Review of the biological oceanography of the Strait of Georgia: pelagic environment. Cana- dian fournal of Fisheries and Aquatic Science 40:1064-1094. Heinrich, A.K. 1957 The breeding and development of the domi- nant eopepods in the Bering Sea. Trudy Ves- esoiuznoe Cibrobiologie Obshchestuo 8:143-162. Heinrich, A.K. 1962 The life history of plankton animals and sea- sonal cycles of plankton communities in the oceans. Journal du Conseil, Conseil International pour VExploration de la Mer 27:15-24. Heinrich, A.K. 1968 Seasonal phenomena in the plankton of the northeast Pacific Ocean. Ocearwlogy 8:231-239. Ikeda, T., and S. Motoda 1978 Zooplankton production in the Bering Sea cal- culated from 1956-1970 Oshoro Maru data. Marine Science Communications 4:329-346. Kamba, M. 1977 Feeding habits and vertical distribution of wall- eye pollock, Theragra chalcogramrna (Pallas), in early life history stage in Uchiura Bay, Hok- kaido. Report of the Institute of North Pacific Fisheries, Hokkaido University, Special Vol- ume, pp. 123-273. Kendall, A.W., Jr., J.R. Dunn, R.J. Wolotira,Jr.,J.H. Bowerman, Jr., D.B. Dey, A.C. Matarese, andJ.E. Munk 1980 Zooplankton, including ichthyoplankton and decapod larvae, of the Kodiak shelf. Processed Report 80-8, Northwest and Alaska Fisheries Center, Seattle, WA. 393 pp. Koblents-Mishke, O.I. 1965 Velichina pervichnoi produktsii Tikhogo Okeana (Primary production in the Pacific Ocean). Okeanologiya 5:325-337. Larrance,J.D. 1971 Primary production in the mid-subarctic Pacific region, 1966-68. Fishery Bulletin (U.S.) 69:595-613. Laurence, G.C. 1974 Growth and survival of haddock (Melanogram- mus aeglefinus), larvae in relation to planktonic prey concentration. Journal of the Fisheries Research Board of Canada 31:1415-1419. LeBrasseur, R.J. 1965a Biomass atlas of net zooplankton in the north- eastern Pacific Ocean, 1956-1964. Fisheries Research Board of Canada Manuscript Report Series (Oceanographic and Limnological) No. 201. 14 pp. plus figures. LeBrasseur, R.J. 1965b Seasonal and annual variations of net zoo- plankton at Ocean Station P, 1956-1964. Fish- eries Research Board of Canada Manuscript Report Series (Oceanographic and Lim- nological) No. 202. 163 pp. Marlowe, C.J. and C.B. Miller 1974 The vertical distribution of zooplankton at Ocean Station "P" in June-Julv, 1971. Reference No. 74-13, School of Oceanogi aphv, Oregon State University, Corvallis, OR. 100 pp. 302 Biological Resources May, R.C. 1974 Larval mortality in marine fishes and the criti- cal period concept. In: The Early Life History of Fish: Proceedings of an International Symposium held at the Dunstaffnage Marine Research Laboratory of the Scottish Marine Biological Association at Oban, Scotland, from May 17-23, 1973. J.H.S. Blaxter, editor. Springer-Verlag, Heidelberg, pp. 3-19. McAllister, CD. 1969 Aspects of estimating zooplankton production from phytoplankton production. Journal of the Fisheries Research Board of Canada 26:199-220. McLaren, LA. 1978 Generation lengths of some temperate marine copepods: estimation, prediction, and implica- Uons.Journal oftlie Fisheries Research Board of Can- ada 35:1330-1342. Miller, C.B., B.W. Frost, H.P. Batchelder, MJ. Clemons, and R.E. Conway 1984 Life histories of large grazing copepods in a subarctic ocean gyre: Neocalanus plumchrus, Neo- calanus cristatus and Eucalanus bungii in the northeast Pacific. Progress in Oceanography 13:201-243. Motoda, S. and T. Minoda 1974 Plankton of the Bering Sea. In: Oceanography of the Bering Sea. D.W. Hood and E.J. Kelley, edi- tors. Occasional Publication No. 2, Institute of Marine Science, University of Alaska, Fair- banks, AK. pp. 207-241. Nemoto, T. 1957 Food of baleen whales in the northern Pacific. Science Report of the Whales Research Institute 12:33-90. Nemoto, T. 1970 Feeding patterns of baleen whales in the ocean. In: Marine Food Chains. J.H. Steele, editor. Uni- versity of California Press, Berkeley, CA. pp. 241- 252. Nishiyama, T. and K. Hirano 1983 Estimation of zooplankton weight in the gut of larval walleye pollock (Theragra chalcogramma). Bulletin of the Plankton Society of Japan 30:159-170. Nishiwaki, M. 1972 General biology. In: Mammals of the Sea: Biology and Medicine. S.H. Ridgway, editor. Charles C. Thomas, Springfield, IL. pp. 3-204. Paffenhofer, G. A. 1980 Zooplankton distribution as related to summer hydrographic conditions in Onslow Bay, North Carolina. Bulletin of Marine Science 30:819-832. Parsons, T.R. 1965 A general description of some factors govern- ing primary production in the Strait of Geor- gia, Hecate Strait and Queen Charlotte Sound, and the N.E. Pacific Ocean. Fisheries Research Board of Canada Manuscript Report Series (Oceanographic and Limnological) No. 193. 86 pp. Parsons, T.R., L.F. Giovando, and R.J. LeBrasseur 1966 The advent of the spring bloom in the eastern subarctic Pacific Ocean. Journal of the Fisheries Research Board of Canada 23:539-546. Parsons, T.R., RJ. LeBrasseur, J.D. Fulton, and O.D. Kennedy 1969 Production studies in the Strait of Georgia. Part II. Secondary production under the Fraser River plume, February to May, 1967. Journal of Experimental Marine Biology and Ecology 3:39-50. Paul, A J. 1983 Light, temperature, nauplii concentrations, and prey capture by first feeding pollock larvae Theragra chalcogramma. Marine Ecology — Progress Series 13:175-179. Reeburgh, W.S., R.D. Muench, and R.T. Cooney 1976 Oceanographic conditions during 1973 in Rus- sell Fjord, Alaska. Estuarine and Coastal Marine Science 4:129-145. Rogers, D.E., D.J. Rabin, B J. Rogers, KJ. Garrison, and M.E. Wangerin 1979 Seasonal composition and food web rela- tionships of marine organisms in the near- shore zone of Kodiak Island — including ichthyoplankton, meroplankton (shell fish), zooplankton and fish. Research Unit 553. Environmental Assessment of the Alaskan Continen- tal Shelf, Annual Reports of Principal Investigators 4:529-662. Royer, T.C. 1981 Baroclinic transport in the Gulf of Alaska. Part II. A fresh water driven Coastal Current.Journal of Marine Research 39:251-266. Royer, T.C. 1983 Observations of the Alaska Coastal Current. In: Coastal Oceanography. H. Gade, A. Edwards, and H. Svendsen, editors. Plenum Press, New York, NY. pp 9-30. Science Applications, Inc. (SAI) 1980 Environmental Assessment of the Alaskan Continen- tal Shelf: Kodiak Interim Synthesis Report. Boulder, CO. 326 pp. ZOOPIANKTON 303 Sekiguchi, H. 1975 Seasonal and ontogenetic vertical migrations of some common copepods in the northern region of the North Pacific. Bulletin of the Faculty of Fisheries, Met University 2:29-38. Smith, S.L., andj. Vidal 1984 Spatial and temporal effects of salinity, tem- perature, and chlorophyll on the communities ofzooplankton in the southeastern Bering Sea. Journal of Marine Research 42:221-257. Thompson, VV.F. and R. Van Cleve 1936 Life history of the Pacific halibut. International North Pacific Fisheries Commission Report No. 9. 184 pp. Vinogradov, M.Ye. 1968 Vertical distribution of the oceanic zoo- plankton. Academiya NAUK SSSR. Institut Okeanologii. (Translated from Russian by Israel Program for Scientific Translations, 1970.) 339 pp. Vinogradov, M.Ye., and Ye.G. Arashkevich 1969 Vertical distribution of interzonal copepod fil- ter feeders and their role in communities at dif- ferent depths in the north-western Pacific. Ocearwlogy 9:399-409. Vogel, A.H. and G. McMurray 1986 Seasonal population density distribution of copepods, euphausiids, amphipods and other holoplankton on the Kodiak Shelf. Outer Conti- nental Shelf Environmental Assessment Program, Final reports o/PriTicipal Investigators 46:423- 659. VTN Environmental Sciences, Inc. 1983 Integrative data analysis: coastal and marine biology program — Quartz Hill Molybdenum Project, Southeast Alaska. Unpublished report prepared for U.S. Borax and Chemical Corpo- ration, Los Angeles, CA. 162 pp. Wickett, W.P. 1967 Ekman transport and zooplankton concentra- tion in the North Pacific Ocean. Journal of the Fisheries Research Board of Canada 24:581-594. Wiebe, P.H., S. Boyd, andJ.L. Cox 1975 Relationships between zooplankton displace- ment volume, wet weight, dry weight, and car- bon. Fishery Bulletin (U.S.) 73:777-786. Wing, B.L. and G.N. Reid 1972 Surface zooplankton from Auke Bay and vicinity, southeastern Alaska, August 1962- June 1964. Data Report 72, National Marine Fisheries Service, Auke Bay, AK. 765 pp. (12 microfiche). Biogeography and Ecology of Intertidal 11 and Shallow Subtidal Communities Charles E. O'Clair Northwest and Alaska Fisheries Center Auke Bay Laboratory National Marine Fisheries Service National Oceanic and Atmospheric Administration Auke Bay, Alaska Steven T. Zimmerman Alaska Regional Office National Marine Fisheries Service National Oceanic and Atmospheric Administration Juneau, Alaska Abstract Recent studies of the natural shore communities of the Gulf of Alaska provide a descriptive foundation for future work on the primary factors that determine both geographical and local distribution and abundance patterns for algal and inverte- brate populations. However, there is still a lack of experimental evaluation to deter- mine the role that physical disturbances, gradients in physical regimes, and biological interactions play in determining these patterns. Our analysis of both the biotic composition and the zoogeographic affinities of those invertebrates of the major phyla revealed no major biogeographical discon- tinuities between Yakutat and the eastern Aleutian Islands. However, we found that the intertidal flora and fauna of the western Aleutians (Amchitka and Shemya Islands) differed markedly from the flora and fauna of the eastern Gulf. The distribu- tion of species among trophic levels was similar between these two regions, but the western Aleutians had more Asiatic and fewer North American species, and had a greater proportion of endemic species of Mollusca, Crustacea, and Echinodermata than were found in the eastern Gulf. Physical disturbance was only of overriding importance in controlling community structure at three of the 29 study sites. Gradients in the regimes for salinity, turbidity, and exposure altered both the community composition and the relative abundances of intertidal species, such as Semibalanus balanoides and Balanus glandula, which have a tolerance for a broad range of values for these factors. Pisaster ochraceus and Evasterias troschelli do not appear to play key roles in the organization of intertidal communities in Alaska because Mytilus californianus is rare there and M. edulis is vulnerable to the activities of other predators and perhaps to physical disturbance as well. When most intertidal species are lifted even slightly above their upper vertical limits by land-level changes, they either die or emigrate. This supports the contention that the upper limits of most intertidal organisms are physiologically determined. The exceptions are Balanus glandula, Semibalanus cariosids, and Chthamalus dalli which can survive uplift of nearly 1 m above their upper limits. It normally takes at least three years for communities to redevelop to their former condition after an uplift. 305 306 Biological Resources Introduction The Gulf of Alaska is bordered by an extensive and intri- cate coastline that provides a variety of habitats for inter- tidal organisms. For this chapter, we include the western Aleutian Islands in our discussion of intertidal communities in the Gulf so we can include research on the effects that sea otters (Enhydra lutris) have on intertidal and shallow subtidal communities, as well as research on the response of inter- tidal communities to land-level changes. We have included an historical review of those studies done on the biogeography and the ecology of intertidal biota, with emphasis on recent work. We describe in detail the biogeographical relationships between intertidal algae and invertebrates found along the coast from Yakutat to the western Aleutian Islands. We also discuss the ecology of intertidal communities found both on the outer coast and in protected inner waters, and review research on the effect of natural and man-induced land-level change on intertidal communities. Because many of the more recent intertidal studies also include subtidal observations, and research on the effects of sea otter predation on nearshore communities encom- passes both intertidal and subtidal habitats, we also consider some research results from the subtidal region. In the final section of the chapter we discuss some aspects of subtidal kelp beds. Studies of both rocky and unconsolidated inter- tidal habitats are listed in this chapter, but our discussion emphasizes rocky intertidal research because these commu- nities have historically received broader and more detailed attention than the infaunal intertidal communities. Historical Research Review The earliest observations and collections of intertidal organisms in the Gulf of Alaska were made at the beginning of the nineteenth century by the naturalists who accom- panied expeditions of discovery into the region (Sauer 1802; Chamisso 1821). The beginnings of an extensive taxonomic literature on the algae and invertebrates of the region (Eschscholtz 1829-1833; Middendorff 1847, 1849; Brandt 1851; Grube 1855; and Dall 1884) followed soon after the observations of these naturalists were published. Lebednik and Palmisano (1977) and O'Clair (1977a) reviewed this early literature (with emphasis on the Aleutian Islands). Feder and Mueller (1972) reviewed the intertidal literature begin- ning with the Harriman Alaska Expedition (1899) and con- tinuing through the 1960s (see also Zimmerman and Merrell 1976). Nybakken's (1969) study of the intertidal ecology of Three Saints Bay on Kodiak Island was the first quantitative study of intertidal communities in Alaska. During the late 1960s and early 1970s, four major events occurred which precipitated a series of ecologically ori- ented studies of the Alaskan littoral zone. The first was the Great Alaskan Earthquake of 1964 (Baxter 1971; Haven 1971; Hubbard 1971;Johansen 1971; Nybakken 1971; and Paul, Paul, and Feder 1976). The second event was the initiation of the Amchitka Bioenvironmental Program in 1966 (O'Clair and Chew 1971; O'Clair 1977a, b; Lebednik, Weinmann, and Nor- ris 1971; Lebednik and Palmisano 1977; Palmisano and Estes 1977; Simenstad, Estes, and Kenyon 1978; and Estes, Smith, and Palmisano 1978). The third was the Trans-Alaska Pipeline Project which followed the discovery of oil at Prud- hoe Bay in 1969 (McRoy and Stoker 1969; Feder, Cheek, Flanagan, Jewett, Johnston, Naidu, Norwell, Paul, Scar- borough, and Shaw 1976; Myren and Pella 1977; Dames and Moore 1979a; Feder and Paul 1980; and Feder and Reiser 1980). The fourth event was the establishment of the Outer Continental Shelf Environmental Assessment Program (OCSEAP) in 1974 (see review of Gulf of Alaska studies in Jarvela 1982). As a result of these and other more academic research efforts (Smith 1972; Duggins 1980a), a vast body of literature describing the species composition, community structure, and the ecology of intertidal biota has been accu- mulated during the last fifteen years. It is one objective of this chapter to indicate where these sources of informa- tion— most of which are still unpublished — may be found. Aerial and Coastwide Surveys The overall distribution of intertidal habitat types in the Gulf of Alaska was first described in a series of maps by Sears and Zimmerman (1977). Their data, extending from Yakutat (59°33'N, 139°50'W) to the Islands of the Four Mountains (52°45'N, 170°10'W), are based on aerial reconnaissance and describe 1) the general beach types (bedrock, boulder, gravel, sand, mud), 2) beach slopes, and 3) the percentage of the beach covered by intertidal biota. Zimmerman, Gnagy, Calvin, MacKinnon, Barr, Fujioka, and Merrell (1977) pro- vide a breakdown of Sears and Zimmerman's (1977) data into the number of miles and the percentages of each beach type for several of the areas they surveyed. Concurrent with this work, several sections of the Gulf coastline were also mapped to provide information on coastal morphology and coastal vulnerability to oil spills. The first of these studies consisted primarily of maps indicating beach profiles, sub- strate types, grain sizes, and presumed vulnerabilities to oil retention; later work included detailed information on asso- ciated biota. By area, the early studies included: • Glacier Bay National Monument (Molnia and Wheeler 1978) • the northern Gulf of Alaska (Nummedal and Stephen 1976; Ruby 1977; Ruby and Hayes 1978; and Hayes and Ruby 1979a) • the area from Montague Island to the Kenai Peninsula (Hayes 1980) • the lower Cook Inlet region (Hayes, Brown, and Michel 1976; Michel, Hayes, and Brown 1978) • the Kodiak Island region (Hayes and Ruby 1979b). Surveys that also incorporated biological indices as part of the maps included Kodiak Island (Hayes 1982) and Shelikof Strait (Domeracki, Tjebeau, Getter, Sadd, and Ruby 1980). Additional data on intertidal habitats and associated biota, as indicated by aerial surveys or other large-scale reconnais- sance methods, are found in: • Arneson (1980) for the entire Gulf • Rosenthal, Lees, and Maiero (1982) for Prince William Sound Inllrtidal and Shallow Subtidal Communities 307 • Lees (1978) for lower Cook Inlet • Dames and Moore (1977a) for the outer coast of the Kenai Peninsula. Many of these reports were reworked graphically and are found in Science Applications Inc. (1979, 1980a, b). Intertidal and Shallow Subtidal Study Sites Intertidal communities in the Gulf of Alaska have been described at approximately one hundred sites extending from Boca de Quadra in Southeast Alaska to Attu Island in the western Aleutians (Tables 11-la to 11-le). Research at almost all of these sites has resulted in detailed species lists and, in some measure, abundance and distributions data relative to tidal heights for the dominant species. Southeast Alaska. From the perspective of littoral biol- ogy, Southeast Alaska is one of the least-described regions in the Gulf. No general aerial or coastwide surveys have ever been completed there; only six general areas have been stud- ied in any detail on the ground (Table 11-la). Of these six, those that extended over the longest period of time and con- tain the most detailed observations include: 1) the intertidal work at Torch Bay by Quinn and Duggins (1977) and Paine (1980) and 2) the subtidal work at Torch Bay, Deer Harbor, and Surge Bay by Duggins (1980a, b; 1981a, b; and 1983). In addition to describing the seasonal distributions and the densities of dominant organisms, the Torch Bay work also describes the results of experiments that were designed to determine the role that three kinds of predators — sea urchins, the sea star Pycnopodia, and sea otters — play in the subtidal community. Work at Starrigavin Bay (Hartman and Zahary 1983) describes species groups sampled throughout the intertidal region. The descriptions were part of a study aimed at differ- entiating the biogeographic regions along the west coast of the United States. Research by VTN (1982a, b, and 1983)— part of a comprehensive environmental baseline done prior Table 11-la. Intertidal and shallow subtidal sites sampled in Southeast Alaska (northern Queen Charlotte Islands to Vakutat). Site Substrate Author Boca de Quadra, Smeaton Rock, gravel. Bay, Wilson Arm sand, silt (55°10'N, 131o0()"W')a Starrigavin Bay Rock (57°06'N, 135°23'\V) Hawk Inlet, Young Bay Rock, gravel, (58°10'N, 134038'\\'> sand, silt Auke Bav Rock (58°22'N, 134°40'\V) Berner's Bay Rock, gravel. (58°42'N, 135°00"VV) sand, silt Torch Bav Rock (58°20'N. 136°50"VV) VTN 1982a. 1982b. 1983 Hartman and Zahary 1983 International Environ- mental Consultants 1980; Holland el al. 1981 O'Clair and Fritts 1980 Smith 1972: Calvin 1977 Quinn and Duggins 1977; Paine 1980; Duggins 1980a, 1980b, 1981a, 1981b. 1983 In cases where geographic coordinates were not listed by the authors, those given bv Orth (1967) have been used. to the development of the Quartz Hill Molybdenum Proj- ect— provides data on year-to-year variations in both the abundances of selected species and dendrograms of species groups. A draft Environmental Impact Statement, which describes both the proposed development of this large molybdenum deposit and the environmental studies that accompanied the proposed action, is available from the Ketchikan Office of the USDA Forest Service (Admin- istrative Document 133, undated). Research was done by International Environmental Con- sultants (1980), Martin Marietta Corporation (Holland, Hiegel, and Richkus 1981), and Hancock (undated) as part of the Noranda/Greens Creek mining study. These studies pro- vide data on the number of organisms per square meter in soft bottom samples as well as graphical depictions of biotic zonation at several sampling sites. A Final Environmental Impact Statement (dated January 1983), which describes both the proposed development of this large lead/zinc/silver ore body on Admiralty Island and the environmental research which accompanied it, is available from thejuneau Office of the USDA Forest Service. Smith (1972)— later pub- lished as Calvin (1977) — gives qualitative observations on the species that occur at eight sites in the Berner's Bay area. O'Clair and Fritts' (1980) experimental data from studies in Auke Bay are discussed in more detail later in this chapter. Data on substrate types, benthic profiles, and associated biota recorded during subtidal investigations of approx- imately 75 additional sites may be found in the Special Investigations Files of the National Marine Fisheries Sendee in Juneau, Alaska. These studies, usually limited to a single set of observations occurring over a one- or two-day period, were undertaken as part of a regional survey of pro- posed log transfer and rafting sites in Southeast Alaska. Results from 32 of these sites are summarized in Schultz and Berg (1976). A final Environmental Impact Statement (dated October 1984) describes subtidal work done in conjunction with a proposed log transfer facility at Cube Cove on Admi- ralty Island. This is available from the U.S. Army Corps of Engineers office in Anchorage. Northeastern and Central Gulf. As evidenced from aerial surveys, exposed sand and gravel beaches predomi- nate in this region. They account for almost 60% of the intertidal substrata (Zimmerman et al. 1977), but this esti- mate does not include Prince William Sound. Data from many of the individual sites within this area are found in Zimmerman and Men-ell (1976) and O'Clair, Hanson, Mac- Kinnon, Ghanett, Calvin, and Menell (1978); both of these reports resulted from a single geographically extensive study of the intertidal biota of the Gulf — a study funded by the Outer Continental Shelf Environmental Assessment Program (OCSEAP). Transect lines or random point sam- pling methods were used to collect quantitative quadrat samples at each site. Zimmerman and Merrell (1976) and O'Clair^ al. (1978) contain figures and tables describing the densities and the distributions of organisms relative to tidal heights. Additional work completed as part of this project includes a study of the accumulation of drift biota at three sites over several seasons (Palmisano 1976); Rosenthal, Lees, and Rosenthal's (Dames and Moore 1976a, 1977b) charac- 308 Biological Resources terization of subtidal biota at three sites adjacent to Zimmer- man and Merrell's (1976) intertidal sites; and a feasibility study using aerial multispectral scanning techniques to map the distribution of biota in intertidal zones (Roller and Pol- c\n 1978). Other geographically extensive studies have also been completed in this region (Table 11— lb). Rosenthal, Lees, and Maiero (1982) provide qualitative descriptions and general observations at 22 sites along the shoreline of Prince William Sound. Lees and Rosenthal (Dames and Moore 1977a) describe the intertidal and subtidal zones at three sites along the outer coast of the Kenai Peninsula. These data include quantitative determinations of the densities, distributions, and percent cover of several numerically abundant species — as well as general 'nature walk' descrip- tions. Lees and Rosenthal also paid special attention to the biology of the eelgrass beds and the mussel beds which they encountered. Nickerson (1975) reports on razor clam populations and associated organisms at eleven sites across the northern Gulf and also provides descriptions of substrate types. Research results following the Great Alaskan Earthquake of 1964 describe the effects that tectonic changes in land levels have on populations of 1) benthic algae (Johansen 1971), 2) clams (Baxter 1971), and 3) other intertidal invertebrates (Haven 1971). This earthquake-related work was based on a coordi- nated, vessel-based survey of thirty-three sites from upper Orca Inlet to the southwestern islands of the Sound. Several additional studies report on the distribution of intertidal communities at a single site or in a geographically restricted area. These include: • earthquake-related work at Olsen Bay (Hubbard 1971; Paul, Paul, and Feder 1976) • a time-series study of the effect of oil development in the Valdez area on Macoma balthica populations (Myren and Pella 1977 ) • a three-year field study of the effects of crude oil on intertidal populations of bacteria, meiofauna, and Macoma. balthica at Port Valdez (Feder et al. 1976) • a pre-oil baseline survey in the Valdez area (McRoy and Stoker 1969) • a study of several intertidal and shallow subtidal sites north of the oil terminal in the Valdez area (Dames and Moore 1979a; Lees, Erikson, Driskell, and Boet- tcher 1979) • a nineteen-month time series study of species densi- ties, settlement, and recruitment at three permanent sites in Port Valdez (Feder and Reiser 1980) • a study of seasonal trends in meiofaunal abundance on two beaches in Port Valdez (Feder and Paul 1980) • a zonation study at Resurrection Bay (Hartman and Zahary 1983). Cook Inlet Region. Aerial surveys (Lees 1978) indicate that protected habitats — most often composed of uncon- solidated cobble, gravel, sand, or silt — dominate this coast- line. Most littoral research has occurred in the southern sec- tor of the Inlet; with the exception of salt marsh studies in Table 11-lb. Intertidal and shallow subtidal sites sampled in the northeastern and central Gulf of Alaska ( Yakutat to Cook Inlet). Site Substrate Author Yakutat Rock Zimmerman and Merrell (59°32.3'N, 139°52.5'W) 1976; O'Clair e< a/. 1978 Yakutat Sand Palmisano 1976 (59°32'N, 139°53'W) Yakataga Rock Zimmerman and Merrell (62°03.8'N, 142°25.9'W) 1976; O'Clair 9°i:vn, iji0or\\') Chugach Bav (59°ir\. i3i°:i4'\V) Kovuktolik Bav (59°14.3'N, 151°56.3'W) O'Clail -rial. 1978 Subtidal rock Dames and Moore 197(ia: 1977b Zimmerman and Merrell 1976; O'Clair etflJ. 1978 Zimmerman and Merrell 1976; O'Clair et al. 1978 Hartman and Zaharv 1983 Rock Rock Rock Rock O'Clair et at 1978 Rock, cobble. Dames and Moore 1977a sand Rock, cobble, Dames and Moore 1977a sand Rock, cobble. Dames and Moore 1977a sand the upper part of the Inlet (Macdonald, Wolfe, and Savage 1979; Vince and Snow 1984; and Snow and Vince 1984), all other littoral work in this region has occurred south of Kalgin Island (Table 11-lc). Intertidal and shallow subtidal research in this region began with a description of marine plant (Dames and Moore 1976b) and shallow subtidal (Dris- kell and Lees 1977) communities in Kachemak Bay. This work was expanded geographically to include a reconnais- sance of representative sites on both sides of the Inlet (Lees 1978; Lees and Driskell 1980) and was completed with a detailed investigation of the ecology of rock, sand, and silt habitats on both sides of the Inlet (Dames and Moore 1979b, 1980a). Throughout all of this work, stratified random sam- pling along transect lines was generally used to obtain data on species distributions, abundances, and standing stocks. Seasonal patterns of primary productivity, growth, and standing crops of macrophytes were also examined. Addi- tional studies of limited geographical areas include a multi- seasonal study of sixteen transect lines along both sides of the Homer Spit (Lees, Erikson, Driskell, and Treesh 1981), and a reconnaissance of inshore areas at the Phillips Petroleum lease blocks at Spring Point in Chinitna Bay (Lees 1976). A study of beach drift composition similar to Palmisano's work in the eastern Gulf was also completed in lower Cook Inlet (Cunning 1977). Kodiak Area. Beaches in the Kodiak area are com- posed primarily of bedrock, boulder, and gravel. Bedrock comprises almost 50 percent of all beach types found on Kodiak and associated islands; sand and silt substrates account for less than ten percent (Zimmerman et al. 1977), but this estimate does not include the Alaska Peninsula. Eco- logical research on intertidal communities was initiated on Kodiak Island with Nybakken's thesis work at Three Saints Bay (Xybakken 1969). Two studies since then have greatly expanded the data from this area. These were: 1) a qualitative and quantitative study of the intertidal biota and subtidal kelp communities occurring around Kodiak Island (Zimmerman, Hanson, Fujioka, Calvin, Gharrett, and Mac- Kinnon 1979; O'Clair, Hanson, Myren, Gharrett, Merrell, MacKinnon, and Calvin 1981), and 2) a detailed study of Si i h Si BSTRATE Ar i iiok Seldovia Point (59°28'N, 151°42'W) Jakalof Bay (59°28'N, 151°32'W) Sadie Cove (59°30.5'N. 151°28'W) Gull Island (59°35.1'N, 151°19.7'W) Homer Spit (59°37'N, 151°27'W) Archimandrite)!' Shoals (59°36'N, 151°27'W) Seafair Beach, Bishop's Beach, Bluff Point (59°40'N, 151°41'W) Whiskey Gulch (59°50'N, 151°49'W) Deep Creek (60°02'N, 151°42'W) Clam Gulch (60°14.5'N, 151°24'W) Kasilof (60°23.3'N, 151°17.8'W) Potter Marsh (61°03'N, 149°48'W) Susitna Flats (61°15'N, 151°30'W) Polly Creek (60°17'N, 152°27'W) Spring Point (59°52'N, 152°48'W) Chinitna Bay (59°51'N, 152°54'W) Scott Island (59°38'N, 153°26'W) Iniskin Bay (59°39'N, 153°27'W) Knoll Head Lagoon (59°38.5'N, 153°30'W) White Gull Island (59°37'N, 153°34'W) Bruin Bay (59°22.5'N, 153°57'W) Amakdedori Beach (59°16.6'N, 154°07.5'W) Douglas River (59°04.5'N, 153°48.5'W) Ro< k, ( obble Dames and Moore 1970b. 1979b, 1980; Lees and Driskell 1980 Rock, cobble Dames and Moore 1976b; Lees and Driskell 1980a Rock Dames and Much c 1 97dh Rock Dames and Moore 1970b 1979b, 19811 Sand Dames and Moore 1979b 1980a; Lees et al. 1981 Rock, sand Dames and Moore 1976b, 1979b, 1980a Boulder, cob- Lees 1978 ble, gravel, sand Cobble, sand Lees 1978 Sand Dames and Moore 1977a, 1979b, 1980a Sand Lees 1978 Sand, silt Lees 1978 Salt marsh Macdonald et al. 1979 Salt marsh Vince and Snow 1984; Snow and Vince 1984 Sand Lees 1978 Cobble, sand Lees 1976 Sand, silt Dames and Moore 1977a, Rock Rock, sand, silt Rock, cobble Rock Rock, gravel, sand, silt Rock, sand Rock, sand, sill 1979b, 1980a: Lees and Driskell 1980 Dames and Moore 1979b, 1980a; Lees and Driskell 1980 Lees 1978 Dames and Moore 1979b, 1980a; Lees and Driskell 1980 Dames and Moore 1979b, 1980a; Lees and Driskell 1980 Lees 1978 Lees 1978 Lees 1978 razor clam distributions and populations in the Kodiak/ Shelikof Strait region (Kaiser and Konigsberg 1977). Both of these studies covered wide geographic areas (Table 11— Id). The reports of Zimmerman et al. (1979) and O'Clair et al. (1981) primarily describe the abundances and tidally related distributions of rocky intertidal communities; Kaiser and Konigsberg's (1977) report provides data on sandy beaches and associated biota. All three publications contain exten- sive species lists. Additional reports, which review the avail- able literature or provide lists of shallow subtidal organisms 310 Biological Resources Table ll-ld. lnlcrtidal and shallow subtidal sites sampled in the Kodiak Island vicinity (North of56°N from 152° to 155°W). Si 1 1 Substrate Author Slid Island (58°54.3'N, 152°12.4'W) North Shuyak Island (58°36'N, 152°31'W) Sea Otter Island (58°31'N, 152°13'W) Tonki Bay (58°16'N. 152°()9'W) Pillar Cape (58°()9'N, 152°05'W) Spruce Island (57°54'N, 152°21'W) Whale Island (57°56'N, 152°45'W) St. Paul Harbor (57°46'N, 152°28'W) St. Paul Harbor (57°46'N, 152°28'W) Chiniak Bay (57°41'N, 152°25'W) Narrow Cape (57°25'N, 152°20'W) Lagoon Point (57°11.3'N, 153°3.4'W) South Sitkalidak Lagoon (57°08'N, 153°02'W) Ocean Bay (57°06.7'N, 153°10'W) Three Saints Bay (57°()8'N. 152°29'W) Three Saints Bay (57°07.8'N, 152°28.7'W) Cape Kaguyak (56°52.4'N, 153°40.9'W) Geese Islands (56°43'N, 153°53'W) Cape Sitkinak (56°33.7'N, 153°52.1'W) Whirlpool Point (57°37'N, 154°08'W) Sundstrom Island (58°54.3'N, 152°12.4'W) Dolina Point (56°36.9'N, 154°13.2'W) Tugidak Island (56°30.7'N, 152°28.7'W) Tanner Head (56°52.8'N, 154°13.3'W) Low Cape (57°59.5'N, 154°31.1'W) Bumble Bay (57°21.6'N, 154°13.3'W) Cape Nukshak (58°23'N, 153°59'W) Swikshak (58°36.6'N, 153°43.2'W) Big River (58°35.7'N, 153°52.2'W) Village Beach (58°34.2'N, 153°51.5'W) Hallo Bay (58°20.2'N, 154°04.3'W) Kukak Bay (58°21.3'N, 154°40.5'W) Dakavak Bay 58°03.7'N, 154°41.2'W) Rock Zimmerman et al. 1979 Rock Zimmerman et al. 1979 Rock Zimmerman et al. 1979 Rock Zimmerman et al. 1979 Rock Zimmerman et al. 1979 Rock Zimmerman et al. 1979 Rock Zimmerman c/ «/. 1979 Rock, Marine Advisors 1971 sand, silt Rock Zimmerman et al. 1979 Rock Zimmerman c/ «/. 1979 Rock Zimmerman et al. 1979 Rock Zimmerman et al. 1979 Silt Zimmerman et al. 1979 Sand Kaiser and Konigsberg 1977 Rock Nybakken 1969; Nybakken 1971 Rock Zimmerman et al. 1979 Rock Zimmerman el al. 1979 Rock Zimmerman et al. 1979 Rock Zimmerman et al. 1979 Gravel Zimmerman et al. 1979 Rock Zimmerman et al. 1979 Rock Zimmerman el al. 1979 Sand Kaiser and Konigsberg 1977 Sand Kaiser and Konigsberg 1977 Boulder, Zimmerman et al. 1979 Cobble Sand Kaiser and Konigsberg 1977 Rock O'Clair etal. 1981 Sand Kaiser and Konigsberg 1977 Sand Kaiser and Konigsberg 1977 Sand Kaiser and Konigsberg 1977 Sand Kaiser and Konigsberg 1977 Sand Kaiser and Konigsberg 1977 Sand Kaiser and Konigsberg 1977 Si i E SUBS1 K.\ 1 1 Author Katmai Bay Sand Kaiser and Konigsberg 1977 (58°01.2'N, 154°55'W) Kashvik Bay Sand Kaiser and Konigsberg 1977 (57°56.7'N, 155°05.7'W) Alinchak Bay Sand Kaiser and Konigsberg 1977 (57°49.9'N, 155°20.2'W) collected during studies on the effects of sewer outfalls or canneries, include Arctic Environmental Information and Data Center (AEIDC) (1974), Marine Advisors (1971), and Fisheries Research Institute (1971). Western Gulf of Alaska. Beaches in the western Gulf of Alaska are composed primarily of bedrock and boulders. From Unimak Pass to the Islands of the Four Mountains, these two substrates account for over 86% of beaches sur- veyed (Zimmerman et al. 1977). Most of the intertidal research in this area has been a direct result of either the OCSEAP Program or the Amchitka Bioenvironmental Program. The research funded through the OCSEAP Program (Zimmerman et al. 1979; O'Clair et al. 1981) was primarily reconnaissance in nature and extended only as far as Makushin Bay on Unalaska Island (Table 11-le). The research done on Amchitka Island was more intensive, extending over several seasons to determine the effect of the Milrow and Cannikin experiments (O'Clair 1977a, b; Estes and Palmisano 1974; Lebednik and Palmisano 1977; and Palmisano and Estes 1977). Reports resulting from both the OCSEAP and Amchitka research, as well as a study of inter- tidal and subtidal habitats near the Unalaska Airport (Dames and Moore 1980b), contain detailed species lists, along with tables and figures describing abundances and tidally related distributions of dominant biota. Additional studies related to the distribution and productivity of eelgrass beds in Alaska (most of which have been studied north of Unimak Pass) are found in McRoy (1970). Biogeography A great deal of attention has been paid to the delineation of the marine biogeographical boundaries along the eastern North Pacific coast. Valentine (1966) reviews the provincial classification systems for Mollusca proposed by various authors. Hartman and Zahary (1983) provide a more recent review including classification schemes suggested by work- ers studying other invertebrate phyla and algae. Although most workers recognize an Aleutian Province (which includes the Gulf of Alaska) within the Eastern Pacific Boreal region (Briggs 1974; Hartman and Zahary 1983), their provincial boundaries are based on latitude. In the Gulf of Alaska, most latitudes intersect two coastal segments. The longitudinal boundaries of the Aleutian Province are much broader than those of other provinces along the Pacific coast of North America. While longitudinal boundaries of the other provinces never include more than 10 degrees of longitude, those of the Aleutian Province include 60 degrees. Further, the Aleutian Archipelago appears to be an Intertidal and Shallow Suhiiimi Communities m Table Q-le. Intertidal and shallow suhtidal sitt-s sampled in I lit- western Gulf o Alaska (156° W to 179°E). Si i i Chirikof Island (55°49.6'N, 156° I l.l'W ) Spectacle Island (55°07.2'N, 159°44.6'W) Sennet Point (54°29.1'W, 164°54.4'W) Akun Island (54°08.5'N, 165°38.7'W) Unalaska Airport (53°54'N, 166°33'W) Eider Point (5S°57.5'N, 166°35.1'W) Makushin Bay (53°44'N, 166°45.8'W) Adak Island (51°45'N, 176°45'W) Amchitka Island (51.5°N, 179°E) Amchitka Island (51.1°N, I79°E) Shemya Island (52°43TSF, 174°07'E) Attu Island (52°55'N, 172°55'E) Si US 1 K \ 1 1 Ai i HOR Rock Zimmerman etal 1979 Roik O'Claii etal. 1981 Rock O'Clair etal. 1981 Rock O'Claii etal. 1981 Rock, cobble, Dames and Moore 19801) gravel, sand Rock O'ClairrfaZ. 1981 Rock Rock Rock Rock Rock Rock O'Clair etal. 1981 Palmisano and Estes 1977 l.ebednik and Palmisano 1977 O'Clair 1977a, 1977b Palmisano and Estes 1977 Palmisano and Estes 1977 area of transition between the Asiatic and North American biotas. Because of these facts, east-west trends in bio- geographical distributions of invertebrates and algae within the Aleutian Province seem to warrant further resolution. Biotic Similarity. We compared assemblages of algae and invertebrates in the rocky intertidal region at 28 localities (27 for the algae) bordering the Gulf of Alaska (Fig. 11-1). Data on presence or absence of species at each of these sites were taken from Lebednik and Palmisano (1977), Zim- merman et al. (1979), O'Clair (1977a), O'Clair et al. (1978), and O'Clair et al. (1981). Sites at each of the localities were sampled with transects laid perpendicular to the shoreline or by means of intertidal arrays. Quadrats, usually 1/16 or 1/64 m2 in area, were placed systematically either along transects or randomly in arrays. All macrobiota were removed from within the quadrant, fixed with 10% for malin, and returned to the laboratory for sorting and identi fication. For further details on the sampling methods Lebednik and Palmisano (1977), see Zimmerman et al (1979) O'Clair (1977a), O'Clair et al. (1978), and O'Clair et al. (1981) The 28 sampling localities included in the present work are shown in Figure 11-1 and listed in Tables 11-lb, d, and e. Only organisms identified to species are included — except in those few cases when organisms obviously unique within the composite collection considered here could be identified only to generic or higher taxonomic level. Mem- bers of the following taxa were not identified to species level at most sites: Porifera Anthozoa Platyhelminthes Nemertea Sipuncula Nematoda Oligochaeta Pseudoscorpionida Harpacticoida Acarina Insecta (except Emplectonema) Brachiopoda Urochordata Similarity in biotic composition between localities was quantified withjaccard's (1902) coefficient of similarity, cal- culated as follows: CJ = c/(a + b-c) where a and b are the number of species present at each locality, and c is the number of species common to both localities. CJ varies between 0 (dissimilar) and 1 (similar) and was multiplied by 100 to remove the decimal. Patterns of similarity in biotic composition in the rocky intertidal region from Yakutat to the western Aleutian Islands were evaluated from cluster analysis by the unweighted pair-group average analysis of the CJ's (Dixon, Brown, Engelman, Frane, Hill, Jennrich, and Toporek 1983). Separate similarity matrices and dendrograms were con- structed for algae and invertebrates (Figs. 11-2 through 11-4, and 11-6). 170 180 170 160 150 170 60 55 1 — Ocean Cape 2 — Cape Yakataga 3 — Katalla Bay 4 — Cape St. Elias 5 — Port Etches 6 — Zaikof Bay 7 — Macleod Harbor 8 — Latouche Point 9 — Squirrel Bay \-\ Gulfo 28 10— Anchor Cove 19- 11— Gore Point 20- 12— Sud Island 21- 13— Cape Nukshak 22- 14 — Lagoon Point 23- 15 — Three Saints Bay 24- 16 — Cape Kaguyak 25- 17 — CapeSitkinak 26- 18 — Sundstrom Island 27- f Alaska study area 28— 4/« 27 A ""W„ Bering 'slands ■Low Cape -Dolina Point Chirikof Island -Spectacle Island -Sennet Point -Akun Island -Eider Point -Portage Bav -Amchitka Island Shemya Island 24 25 26 Ca^ J?' 180 170 160 Figure 11-1. Map showing locations used in the biogeographical analyses. 150 312 Biological Resources i ( II \i 1 1 V 1 2 ! i -. li 7 S 'l 111 II 12 i:i 1 1 IS Hi 17 IS 19 20 21 22 2:1 24 25 26 27 1- »s 8 >1 - " ' " '■ ! 1 : 21 20 ■ • • ■ M B a 29 " V /' •' .'i 17 1! 21 10 l» ' 21 2 ■ ii ■ ■ 10 >5 " 1 « " '■' 37 15 20 IK 27 16 1! " " l' K '" 15 18 ; y( ' 1 IB IS 15 21 l: ; ;e B II ' 12 12 22 1/ 2 15 », " « a - a ik T* 111 21 J9 '1 1' 21 r.< 21 15 > 9 H ' ' ' ." i< - 10 11 2! » 11 51 [3 : 11 38 go » 21 ■ • 17 It 12 10 ' 35 31 1. IV (A 36 ■ 25 30 16 31 10 23 37 10 :o 28 22' ' It V CO - 2' 5l 17 11 11 ii 19 17 35 15 15 20 2' 21 fee- T5 18 20 20 n 11 26 36 :* 31 76 29 15 31 ;i 23 20 !! - 21 13 26 13 13 10 g .'l 17 31 15 21 30 22 21 3f 21 31 13 3 28 : ! - 18 11 2] 20 21 21 1. 5 ^ 21 21 j: 19 15 e 16 18 2C 2 Z S II 13 21 39 36 17 31 15 19 I''' — T - 10 11 7 16 11 11 5 lO J. 21 16 17 21 r: is *■ ■ 36 18 SG 25 19 21 ■ 11 37 15 27 11 20 25 19 7 23 33 15 22 9 o 10 - □ □ 20 Figure 11-2. Similarity matrix (Jaccard's index) for algae at 27 sites in the Gulf of Alaska. Locality numbers correspond to the localities shown in Figure 11-1. Locality S o u V feo V m "C in ! ■_> 3 1 5 h 7 s "I HI, II 12 13 It ]") II) 17 IS 19 '.'II 21 Tl 23 24 25 26 'J 7 28 ■ - ■ ' " - -. ti 28 : 19 21 i. 13 13 ■ - ■ 1 il ". K . .' : : - .2 . 31 . 2! 5( 3 in 32 !l '. ' \ 31 13 i 9 .. } - 20 21 21 21 H n 2" ; 29 ' 25 11 38 " ;: ' -' 2; 12 ■ ■ I! 22 '. ., 50 15 :. 33 - ' " 2'. 11 " i: II . 11 : 11 ,c 26 21 -. 16 . 1' 10 57 '■ 26 '' 31 ■' 13 22 7 ~ 22 ■ 7 23 ' 15 2! . 21 15 7 ' 32 " 9 - - 7 6 . 1 6 23 J 19 - ' 11 8 ■ •■ 5C li 51 n ■ II . 8 15 ' 17 t 21 2f 18 11 - S3 21 " 8 17 ' 17 ' 6 5 ' 19 25 15 23 12 11 ' " 11 ' - - 25 ' 6 21 31 ' 28 ' 28 18 9 '- -r :> 11 . 21 11 10 23 13 - '' 50 15 17 IS ' 18 it 16 11 ,1 ' 11 52 31 32 29 .:. 23 18 II 32 28 51 21 22 37 ' 29 51 •• " I1 .' '• SI 25 18 32 31 19 ■ 18 13 17 18 9 11 15 ■.: 20 If 111 39 27 31 27 J6 17 1. » li ■ 12 16 2< 12 I' lu if 10 r'j 12 1] IE 11 ■ 16 13 11 12 : 10 ■ 17 12 v1 38 19 35 30 18 17 -- 2C 17 :> 15 B !« 15 21 17 19 15 11 6 1' 38 M 31 ► 7 12 |2 ) ■'■ 3'. 3" 38 16 17 25 2. 25 9 11 "■ il 15 11 \ 30 15 i i \ 13 h t \ ..' ■ l\ D D 230 - 39 Figure 11-3. Similarity matrix (Jaccard's index) for inverte- brates at 28 sites in the Gulf of Alaska. Locality numbers corres- pond to localities shown in Figure 11-1. U 30 20 10 6 27 19 20 17 16 14 25 23 26 24 15 4 18 21 12 22 II 9 J T 5 LJ u y j Y Algae Southern Kodiak Western Aleutians Northern Gulf of Alaska (NGOA) Figure 11-4. Dendrogram depicting the similarity of intertidal sites in the Gulf of Alaska with respect to algal species composi- tion. Numbers correspond to localities shown in Figure 11-1. 180 60 T^ 170 Algae groups NGOA I Southern Kodiak I Western Aleutians Bering Sea .■■/> "^ .?«£>• 180 160 140 Figure 11-5. Map showing the distribution of major bio- geographic groups of algae between Yakutat (Ocean Cape) and the western Aleutian Islands. 50 z U 40 2^ 30 > H 3 < = 20 21 12 28 27 20 17 19 16 14 23 15 18 u u CJr LV 25 26 24 13 22 11 4 9 5 10 8 6 7 3 2 1 Wl V Invertebrates Southern Kodiak Western Aleutians Northern Gulf of Alaska (NGOA) Figure 11-6. Dendrogram of similarity coefficients for inverte- brates. Numbers correspond to localities shown in Figure 11-1. Intertidal and Shallow Subtidai Communities 313 65 60 180 170 55 50 Invertebrate groups ■ NGOA I Southern Kodiak I Western Aleutians Hrnng Sea 180 170 160 Figure 11-7. Map showing distribution of major biogeographic groups of invertebrates between Vakutat (Ocean Cape) and the western Aleutian Islands. Analysis of the algal data revealed two distinct groups of sites with low between-group similarity and low similarity with Amchitka Island in the western Aleutians (Figs. 11-2 and 11-4). The first group comprised most of the sites stud- ied in the northern Gulf of Alaska (NGOA). The second group was composed of five localities at the southern end of Kodiak Island: Lagoon Point (14), Cape Kaguyak (16), Low Cape (19), Cape Sitkinak (17), and Dolina Point (20) (Figs. 11-4 and 11-5). (Numbers in parentheses refer to locality numbers in Figure 11-1.) The similarity matrix and dendrogram for invertebrates showed similar groupings to those for the algae. Cluster analysis distinguished a NGOA group, a southern Kodiak group, and a western Aleutian group consisting of Amchitka and Shemva Islands (Figs. 11-3, 11-6, and 11-7). With the exception of the localities in the southern Kodiak group, most of the localities from Yakutat to the east- ern Aleutian Islands fell within the same cluster with respect to both algal- and invertebrate-species composition. The Kodiak sites were characterized by either complete or par- tial exposure to open ocean waves and, at four of the five sites, they were characterized by exposure to unstable sub- strates of boulders or boulders and bedrock. Algae and invertebrates at these sites were characterized by low species richness (Zimmerman el al. 1979). The species richness for algae at the sites averaged less than half of the species richness for the NGOA group (Table 11-2). The low algal species richness at four of the Kodiak sites was probably due to disturbances that resulted when boulders on the pre- dominantly boulder-strewn beaches were moved during storms. Invertebrate species richness within the southern Kodiak group was also low — especially in the case of Polychaeta and Crustacea. Crustacean species richness was low because few gammarids were present in collections from (he area. Analy- sis of invertebrate geographical distribution lot two major taxa on the Kodiak sites showed a similar pattern of species distribution among zoogeographic categories to the pattern for species from sites in the NGOA group. Ibis indicated that the intertidal communities at sites within these two groups were probably quite similar. Low species richness within the Kodiak group — caused at least in part by distur- bance, rather than by pronounced qualitative differences in community composition — was probably responsible for the dissimilarity between the Kodiak and the NGOA groups. Biogeographic Affinities of Biota. Species of four major taxa — Polychaeta, Mollusca, Crustacea, and Echi- nodermata — that were found in the rocky intertidal region at our Gulf of Alaska sites were categorized according to their geographic distribution. Each species was assigned to one of seven zoogeographical categories: 1) widely distributed species — including those species whose distributions extend into the tropics and South- ern Hemisphere as well as those which are cosmopoli- tan or bipolar 2) arctic-boreal species — including circumpolar forms which range into the Arctic 3) amphiboreal species — including those in the boreal fauna of the Atlantic and Pacific Oceans, but whose ranges do not extend into the Arctic 4) North Pacific species — whose ranges extend into the Bering Sea as far north as Bering Strait and to both Asiatic and North American shores 5) Asiatic species — whose ranges extend beyond the Aleutian Province only to shores of the western Pacific 6) North American species — whose ranges extend beyond the Aleutian Province only to shores of the eastern Pacific 7) endemic species — which are restricted to the Aleutian Province as originally defined by Bartsch (1912) and subsequently supported by Valentine (1966; see also Briggsl974). Table 11-2. Number of species in major taxonomic groups within clusters of sites in the Gulf of Alaska. Pi \\ IS POLYC N umber of Spec IES KS C.RISI \< 1 \\s Other Cluster3 HAETES MOLLUS X SD X SD X SD X SD X SD NGOA'- 57 24 36 16 34 12 32 13 23 8 Southern Koci ak 25 8 2 1 23 9 12 2 13 5 Amchitka 89 — • 46 — 51 — 63 — 56 — Shemya — — 1 — 39 — 1 1 — 17 — x = mean; SD = standard deviation. ' Number of sites: NGOA, 21: southern Kodiak, 5. bNGOA = Northern Gull ol Uaska. ' Dashes indicate missing dala oi no value I oi Si) because cluster includes onl\ one location. 314 Biological Resources Our definition of "endemic" was less restrictive than that of O'Clair (1977a); consequently, the species distribution among zoogeographic categories at Amchitka will differ from his. The western boundary of the Aleutian Province has not been precisely established, but may be at or just east of the Commander Islands (O'Clair 1977a). For comparison, we also present data from O'Clair (1977a), who categorized species of littoral polychaetes that had been listed for Bering Island by Annenkova (1934) and species of intertidal mol- lusks that were listed by Dall (1884), Barabash-Nikiforov (1947), Scarlato (1960), and Colikov and Kussakin (1962) for the Commander Islands according to their geographical dis- tributions (Table 11-3). Data in Table 11-3 for Amchitka and the Commander Islands are similar to those presented by O'Clair (1977a: Table 5), except for 1) recent additions to the species list of Amchitka and 2) the inclusion of all species found intertidally at each site — including those whose ranges have been reported to extend below 60 m in depth. Intertidal species composition in the western Aleutian and Commander Islands differed markedly from that in NGOA as reflected in the distribution of species among zoo- geographical categories (Table 11-3). The percentage of North American species in major taxa was significantly less in the western Aleutian and Commander Islands — except in the Polychaeta found at Amchitka Island. Conversely, the percentage of Asiatic species was significantly greater among the Mollusca and Echinodermata in the western Aleutians than at the NGOA sites (Table 11-3). Percentages of Asiatic polychaetes and crustaceans at Amchitka Island and Asiatic polychaetes and mollusks in the Commander Islands could not be statistically compared with the same taxonomic groups at the NGOA sites because the large number of zeros in the NGOA data precluded the use of parametric statistics. We know of no nonparametric test for comparing a sample with a single observation. Nevertheless, the percentages of Asiatic Polychaeta and Crustacea at Amchitka and Asiatic Mollusca in the Commander Islands exceeded the Asiatic percentages of these taxa at every NGOA site; the percentage of Asiatic polychaetes at Bering Island exceeded the percentage of Asiatic polychaetes at all but two NGOA sites. Although the percentage of endemic polychaetes remained relatively constant over all sites, endemism among the mollusks and echinoderms was significantly higher in the western Aleutian Islands than in NGOA (Table 11-3). Endemism among mollusks in the western Aleutians averaged 12% — about the same percentage as for Crustacea at Amchitka and half of that reported by Valentine (1966) for Table 11-3. Percent of species of four major taxonomic groups of intertidal invertebrates in the Gulf of Alaska (NGOA) and western Aleutian Islands categorized according to geographical distribution. North North Arctic- Amphi- Widely Total Taxon En % DEMIC SD Asiatic % SD American % SD Pacific % SD boreal % SD boreal % SD Distributed % SD Species X Polychaeta NGOA Amchitka 5.4 4.5 0.2 0.8 23.6 5.7 9.2 4.8 21 7.2 7.2 5.4 33.5 9.7 28 Island 3 —a 9 — 15 — 9 — 27 — 3 — 33 33 Bering Island Test Statistic 6 ts = 0.14n.s.b 2 21c — 4 — ts = 1.57 n.s. 10 — ts = 0.09 n.s. 38 ts = 0.82 n.s. 4 — ts = -0.46 n.s. 36 — ts = -0.002 n.s 50 Mollusca ts = 0.38 n.s. 19 ts = -4.47*** ts = 0.26 n.s. ts = 2.01 n.s. ts = -0.26 n.s. ts = 0.274 n.s. NGOA 2.3 3.2 1.3 1.8 39.8 10 27.2 8.3 23 5.3 1.6 2.0 4.7 2.0 26 Western Aleutians 12.5 2.1 8.5 0.7 23.5 0.7 26.5 0.7 23.5 0.7 0 0 5 0 40 Commander Islands 8 — 14 — 8 — 27 — 38 — 3 — 3 — 37 Test Statistic Crustacea z = 2.29*d 19 z = 2.29* 21 ts = -2.25* ts = -3.59** ts = 0.05 n.s. ts = 0.02 n.s. ts = ts = -0.17 n.s. 2.38* z = 1.06 n.s. 13 ts = -0.33 n.s. ts = -0.60 n.s. NGOA Amchitka 0.1 13 0.6 1.5 13 3.2 53.3 8.3 33 — 32.4 5.6 36 — 2.4 0 3.7 4.2 4.3 5 — 5.8 4.0 0 0 20 39 Test Statistic Echinodermata 21 21 ts = -2.409* ts = 0.63 n.s. 0 ts = 0.47 n.s. ts = 1.60 n.s. NGOA 0.6 3.1 1.4 6.3 78.7 21.0 1.6 7.2 17.6 16.4 0 0 0 0 3 Western Aleutians Test Statistic 27.5 7.8 z = 2.291* 19.5 3.5 z = 2.073* 19.5 3.5 ts = 3.023** 0 0 z = 0.56 n.s. 33 z = • 0 -1.27 n.s. 0 0 z = 0 n.s. 0 0 z = 0 n.s. 8 x = mean; SD = standard deviation; ts = student t statistic; z = Mann-Whitney U-Test statistic; n.s. = not significant; * =p<0.05;** = p<0.01;*** = p<0.001. rl Dash indicates no value for SD because only one locality is included. h All tests are two-tailed. The upper statistic of each pair compares NGOA with Amchitka (or Western Aleutians); the lower compares NGOA with Bering Island (or Commander Islands). SeeSokal and Rholf (1981) for t-test comparing a sample mean with a single observation. Percentages were transformed (arcsin Vp)to render their distribution more nearly normal. 1 Where test statistics are not identified, statistical comparisons could not be made. Values shown indicate the number of comparisons (total 21) in which the percentage for Amchitka Island or Bering Island (or Commander Islands) exceeded those for the NGOA sites. '' The Mann-Whitney L'-test was used when a large number of zeros in the NGOA data precluded the use of parametric statistics. ImIKJIDAL AND SHAUOW SuBTIOAL COMMUNITIES 315 moUusks in the Aleutian Province. Kndemism was highest (28%) in the echinoderms of the western Aleutians, hut the total number of species was small. Although endemic mol- lusks in the Commander Islands and endemic crustaceans at Amchitka could not be compared statistically with those at the NGOA sites for the same reason stated above, the endemic percentages at Amchitka and the Commander Islands were greater than those at no less than 90% of the sites in NGOA (Table 11-3). In the Commander Islands, Arctic-boreal polychaetes and mollusks showed virtually identical percentages, but only the molluscan percentages were significantly greater than those for sites to the east (Table 11-3). This difference probably reflected the influence of the Kamchatka Current, a southward-flowing stream of arctic water that passes to the east of the Kamchatka Peninsula and probably brings the propagules of more northerly species south to the Com- mander Islands (O'Clair 1977a). Trophic Distribution. We compared the distribution of species among trophic levels in NGOA with those at Amchitka. The southern Kodiak sites and Shemya were excluded from this analysis because Polychaeta and Gam- maridea were clearly under-represented at these sites. Trophic groups included benthic autotrophs, herbivores (grazers and browsers), suspension feeders, carnivores, deposit feeders, omnivores, and scavengers (including mac- rophagus detritivores). The trophic distribution of the rocky intertidal biota of Amchitka was quite similar to that of the NGOA sites (Table 11-4). Our results are similar to those reported by Hartman and Zahary (1983) for trophic levels in the Aleutian Province with the exception of the relative percentage of grazers. (Most of the herbivores in our study were grazers.) Grazers appear to have outnumbered both suspension feeders and carnivores in Hartman and Zahary's study, although one cannot determine from their data whether the differences were significant because they present no estimate of vari- abilis within trophic levels. The present analysis revealed about an equal number of species of herbivores, suspension feeders, and carnivores in NGOA and at Amchitka (Table 11-4). Table 11-4. Trophic distribution of rocky intertidal benthic biota in the Gulf of Alaska as expressed as percent of species3. NGOA b Amchitka Trophic: Level X SD Autotrophs 31 7 33 Herbivores 15 3 16 Suspension feeders 16 3 14 Carnivores 18 3 16 Deposit feeders 11 4 12 Omnivores 4 1 3 Scavengers 5 2 5 x =mean;SD = standard deviation. » Parasites and commensals are excluded from table, therefore percentages do not sum to 100. h NGOA = Northern Gulf of Alaska; number of sites = 21. Ecology of Rocky Shores In recent years, the interest of marine ecologists has cen- tered on how natural populations of marine organisms interact within the spatial and the temporal constraints oi the physical environment so that local patterns of commu- nity structure may be determined. There have been few attempts to examine the processes controlling benthic coin munity structure in the Gulf of Alaska, with the exception of 1) Estes and Palmisano's (1974) description of the results of a natural experiment (see effects of sea otter prcdation below) in the western Aleutians, 2) Dayton's (1975b) experimental evaluation of competitive interactions among sublittoral kelps at Amchitka Island, and 3) Duggins' (1980a, b and 1983) systematic and comprehensive study of the role of herbivory and predation in structuring subtidal communities in Torch Bay. However, evidence from the short-term descrip- tive studies that have been conducted in the Gulf of Alaska suggests factors that are likely to be important in certain communities. Physical Factors Both physical disturbance and biological interactions combine in varying degrees to influence community struc- ture on the outer coasts of the Gulf. However, the descrip- tive nature of intertidal studies conducted thus far has only allowed an examination of those situations where one or the other category was of overriding importance. Physical dis- turbance was clearly of overriding importance at only three (Cape Yakataga, Low Cape, and Whale Island) of the 29 sites described in Zimmerman et al. (1979) and O'Clair et al. (1978). Unstable substrates in exposed outer-coast environments were the chief source of the physical disturbances that affected the rocky intertidal communities at these three sites. At Cape Yakataga, two factors were reflected in the com- position of the species assemblages on our intertidal trans- ects: 1) the periodic scouring of the rock by sand and/or ice (from Icy Bay) and 2) probable burial of intertidal biota by sand deposited on the rock platform in some seasons or dur- ing storms. We sampled Cape Yakataga using intertidal arrays and transects during three periods: late spring, late summer, and fall. The data indicated that populations of many of the species there were transitory and spatially patchy. Mytilus edulis was common but was represented by small individuals. Filamentous brown and green algae and diatoms were the most numerous algae on the three transects (O'Clair et al. 1978). Intertidal recolonization studies by Lebednik and Pal- misano (1977) showed that these algal species were the ear- liest colonizers of disturbed rocky substrates on Amchitka Island. The abundance of these algal species on the inter- tidal platform at Cape Yakataga during the three sample periods indicates a high frequency of disturbance for Cape Yakataga. At Low Cape and southeast Whale Island, the cobble and small-boulder beaches are subject to heavy wave action which results in the heavy scouring and battering of the rock surfaces there. The cobble and boulders at both sites were sparsely covered with algae, and few invertebrates were found. The Mytilus edulis collected during quantitative sam- 316 Biological Resources pling at Low Cape were small (Zimmerman et al. 1979). At Whale Island, recently settled barnacles and diatoms were found on small rocks. Large boulders had a sparse cover of filamentous and foliose green algae. Crevices in the large boulders harbored barnacles and mussels. The lower sur- faces of large boulders were bare up to a height of 45 cm above the substrate — presumably as a result of cobble scour- ing. In contrast, the same substrate on the protected south- west shore of Whale Island had a heavy cover of intertidal species (Zimmerman et al. 1979). It seems unlikely to us that the community patterns described above for Cape Yakataga, Low Cape, and the southwest shore of Whale Island were the result of biolog- ical rather than physical disturbance. Herbivory by sea urchins of the genus Strongylocentrotus can produce extensive barren areas lacking in both benthic algae and sessile inver- tebrates, similar to the barren areas observed at Low Cape and Whale Island; however, Strongylocentrotus spp. were not evident at either of these two sites (Zimmerman et al. 1979). The portion of the intertidal region sampled at Cape Yakataga was probably above the upper tidal limit of urchin grazing. Predatory gastropods such as Nucella spp. and large star- fish could conceivably reduce both the barnacle and the adult mussel populations to the low levels seen at all three sites, but no large invertebrate predators were found to be abundant at any of the sites. At Cape Yakataga Nucella lamellosa and N. lima were present, but not in great abun- dance (O'Clair et al. 1978). Aggregations of N. lamellosa were observed feeding on small- to medium-sized Semibalanus cariosus on large boulders, but Nucella was not evident over most of the cobble- and boulder-covered shore (Zimmer- man et al. 1979). No large starfish were observed at either Cape Yakataga or at Low Cape. Neither Nucella spp. nor large starfish were found on the southwest shore of Whale Island. In locations such as Cook Inlet, Prince William Sound, southerly along the coast between Prince William Sound and Cape Yakataga, Glacier Bay, and southern Southeast Alaska, there may be significant disturbance of the rocky intertidal communities either by floating glacial ice which has calved off the face of tidewater glaciers or by ice floes and slush ice that form on the surface of the water in pro- tected bays in winter. Waveborn ice may create bare patches of rock substrate by scraping or bashing intertidal orga- nisms from the rock surface in a fashion similar to the way logs create patches of bare rock on the outer coast of Wash- ington (Dayton 1971). Feder and Reiser (1980) listed large ice floes and slush ice as notable winter stresses for intertidal organisms at Port Valdez. At Koyuktolik Lagoon on the outer Kenai Peninsula, ice-scouring created broad furrows through beds of Mytilus edulis. The furrows were quickly colonized by Porphyra sp. and subsequently became sites of dense recruitment by juvenile mussels (Dames and Moore 1977a). Where ice-scour is extensive, intertidal commu- nities become impoverished and are dominated by pioneer species such as were found at Cape Yakataga (O'Clair et al. 1978) and on the lower west side of Cook Inlet (Dames and Moore 1980). In inner waters such as those in Prince William Sound and in southeastern Alaska, greatly fluctuating salinities result both from glacial runoff (in the late spring and sum- mer) and from heavy rainfall (in the fall). Widely fluctuating salinities restrict the number of intertidal species to those that are relatively euryhaline, and may alter the rela- tionships of species that are found in both inner waters and on the outer coast. Localized, heavy freshwater run-off in spring may affect intertidal and shallow subtidal commu- nities near the heads of some bays on the outer coast (e.g., Port Dick; Dames and Moore 1977a), and may further stress intertidal organisms in estuaries (Feder and Reiser 1980). Biological Interactions In the two sections that follow we discuss in some detail examples in which competition and/or predation may be controlling the abundance of species in intertidal commu- nities at specific localities in the Gulf of Alaska. We empha- size these examples because they involve species that are widely distributed on rocky shores in the Gulf of Alaska, and are likely to play important roles in the rocky intertidal com- munities there. The examples involve intertidal systems that are amenable to a mechanistic approach which we believe is more useful in sorting out the key factors involved than is the descriptive approach that has been emphasized in past studies in the Gulf of Alaska. Relative Abundance of Semibalanus balanoides and Balanus glandula. Semibalanus balanoides and Balanus glandula occur together only on the Pacific coast of North America from Unalaska to the northern end of the Strait of Georgia, Brit- ish Columbia (Pilsbry 1916; Haven 1973). The two species are ecologically similar; B. glandula has been referred to as the ecological counterpart of S. balanoides in the eastern Pacific. Semibalanus balanoides also occurs in the North Atlantic (New- man and Abbott 1980). It is likely that these species are potential competitors. Barnes (1958) proposed that the southern limit of distribution for S. balanoides on the Pacific coast of North America was set by B. glandula and (in the lower intertidal zone) by Semibalanus cariosus, but he did not suggest a mechanism. Sessile filter-feeding invertebrates usually compete for space rather than for food (Branch 1984). Competition for space between S. balanoides and Chthamalus stellatus has been shown in Scotland (Connell 1961). For these and related spe- cies, competitive ability was related to growth rate, resulting in hierarchies of adult size and competitive ability that were identical (Connell 1961; Dayton 1971). Comparative growth rates of 5. balanoides and B. glandula in the Gulf of Alaska are not known, but the adult sizes of the two species are about equal — suggesting that where space is limited, the outcome of competition between them may be more sensitive to local factors that influence both the relative growth rate and per- haps recruitment as well. Semibalanus balanoides and B. glandula overlap extensively in vertical distribution in the mid-littoral zone on shores of both the outer coast and inner waters of the Gulf. However, the relative abundances of the two species differ between outer coast and inner waters (at least in Prince William Sound). The relative abundance of S. balanoides and B. glan- dula was estimated at nine sites in Prince William Sound (Fig. 11-8, Appendix 11-1). Intertidal and Shallow Subtidal Communities 317 Outside Bav (7) 100 80 V 60 111 40 X 20 £ 0 u Semibalanus balanoides Balanus glandula Coverage of primary space 60 Figure 11-8. Relative abundance (percent of total barnacles) of Semibalanus balanoides and Balanus glandula at nine sites and coverage of primary space at six sites in Prince William Sound. Error bars are 95% confidence intervals. Asterisks indicate significance of statis- tical tests (***= p< 0.001; **-p<0.01; ns = not significant). At North Shore, Jackson Point, and West Bay sites, t-tests for paired comparisons were used to test the differences in the abundances of S. balanoides and B. glandula. Data from Point Barber and Zaikof Bay sites did not meet the assumptions of the t-test; therefore Wilcoxon's signed-ranks test was used to test barnacle abundances. At locations where either species was absent from all quadrats, statistical tests were not performed. B. glandula was observed at Outside Bay, but was absent from the quadrats. Numbers in parentheses represent number of quadrats sampled. 318 Biological Resources Semibalanus balanoides dominated in coverage in upper Prince William Sound, whereas B. glandula dominated in coverage or abundance in the outer Sound (Fig. 11-8). (Onlv data from quadrats in which one or both species was recorded were included when preparing Fig. 11-8.) Cover- age of S. balanoides in quadrats significantly exceeded that of B. glandula on the north shore of Port Valdez (but not at Jack- son Point) and at Bligh Island (Fig. 11-8). Semibalanus bal- anoides also outnumbered B. glandula at all tide levels where thev occurred together at Island Flats in spring 1977 (Feder and Reiser 1980: Table 8.14). At Siwash Bay and Naked Island, B. glandula was virtually absent from the quadrats, but was observed within the sampling area at Naked Island. Although the sample size was generally small, the results showed that S. balanoides usually had significantly greater percent cover than B. glandula at the sites in the upper Sound. Conversely, at study sites on Hinchinbrook, Mon- tague, and Latouche Islands in outer Prince William Sound, B. glandula either had consistently greater coverage or out- numbered S. balanoides. Elsewhere on shores bordering the Gulf of Alaska, a sim- ilar situation prevailed. At Auke Bay — a protected inner bay in southeastern Alaska where the amplitude of salinity fluc- tuations is about half that at Port Valdez (Figs. 11-9A, 11-10) — the relative percent cover of 5. balanoides was double that of B. glandula (paired t-test, t = 2.30, p = 0.02). Along the outer coast of the Gulf, 5. balanoides was recorded at only 9 of the 28 rockv intertidal sites described in Zimmerman et at (1979), O'Clair et al. (1978), and O'Clair et al. (1981). B. glandula was present at 24 of these locations. The above authors do not include enough data on the rel- ative abundances of S. balanoides and B. glandula at most sites to determine which species was dominant. However, Zim- merman et al. (1979) observed that S. balanoides was dominant in the upper intertidal zone at Whale Island and on one of three transects at Lagoon Point; 5. balanoides also had greater biomass than B. glandula on the upper part of the quan- titative transect at Low Cape. Two of the three sampling areas at WThale Island were subject to heavy freshwater runoff (Zimmerman et al. 1979). B. glandula, but not S. bal- anoides, was present at the eight rocky intertidal sites studied by Dames and Moore (1977a, 1980) both on the outer coast of the Kenai Peninsula and in lower Cook Inlet. The differences in relative abundance for 5. balanoides and B. glandula in outer-coast habitats (as compared with abundances on inner shores) may simply reflect differences in the tolerances that these species have for changes in the regimes of salinity, temperature, wave shock, or siltation. Parts of upper Prince William Sound are influenced by glacial runoff in summer. Salinities in Port Valdez fluctuate greatly, dropping to near O'Voo at the surface in summer (Fig. 11-9A; see also Muench and Nebert 1973 and Feder and Rei- ser 1980). However, with the exception of Siwash Bay, the surface salinities at the other sites in upper Prince William Sound do not appear to fluctuate any more than salinities in the lower Sound (Table 11-5). Both Semibalanus balanoides and Balanus glandula are euryhaline, with similar tolerance limits to low salinities. S. balanoides can acclimate to salinities in the range of 12 to 50°/oo (Foster 1970). The lower end of this range is identical A. Pori Valdez, North Shore 40 Salinity Temperature 1978 1979 1 1 1980 1981 40 20 B. Prince William Sound 15 ^ 10- 0- Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Figure 11-9. A. Surface salinities and water temperatures at the north shore of Port Valdez from June 1978 to September 1981. B. Average monthly air temperatures at three stations in Prince William Sound. Data for 1978 obtained from Climatological Data, Annual Summary, U.S. Department of Commerce, National Climatic Center. Auke Cape, Auke Bay 40-, 30 < 20 t/3 Salinity Temperature I 1978 1979 20 1980 1981 1982 1983 Figure 11-10. Surface salinities and water temperatures Cape, Auke Bay from April 1978 to February 1984. at Auke Intertidal and Shallow Subtidal Communities 319 Table 11-5. Surface salinities ("/<><>) al four locations in Prince William Sound. Means and ranges are shown when available. !.()( A I ION 1977 1978 1979 \! u JlJlA ()( IOBIR Man May SiwashBay 16.5 13.9 22.1 28.:? r>.:$-22.5 West Bay 23.1 24.8 27.6 25.0 28.5 27.6-27.7 Outside Bay 31.6 27.6 26.6 29.2 30.0 Point Barber 31.0 25.1 — 28.4 24.7-25.5 27.7-29.1 to the lowest salinity at which (under normal temperatures) the first stage nauplii of S. balanoides remain mobile (Bhatnagar and Crisp 1965). Twelve parts per thousand also falls within the range of salinities (10-15°/oo) recorded either at or near the inner limit of penetration of S. balanoides into both the Baltic Sea (Barnes and Barnes 1962) and Conway Estuary (Foster 1970). Adult B. glandula can tolerate 0 to 300% seawater for 72 h but apparently do not feed below 50% (about 16°/oo) seawater (Bergen 1968), which is 2°/oo higher than the salinity at which acclimated S. balanoides cease activity (Foster 1970). Bergen (1968) gives salinities in percent of normal water only. Embryos of B. glandula can tol- erate salinities in the range of 50 to 200% seawater (Bergen 1968). S. balanoides may therefore be favored in habitats where salinities periodically drop below 16°/oo, but this would seem to include habitats only at Port Valdez and pos- sibly Siwash Bay. Dominance of 5. balanoides over B. glandula at Outside and West Bays cannot be explained by reduced salinities that act directly on the barnacle populations at these sites. Surface water temperatures fluctuate throughout most of Prince William Sound and ranged from 1 to 11. 8C in the lower Sound to 2.1 to 12.6C in the upper Sound in 1972 to 1973 (data extracted from Figs. 4 to 28 in Muench and Schmidt 1975). Surface-water temperature ranges for Port Valdez (Fig. 11-9; see also Muench and Nebert 1973 and Feder and Keiser 1980) do not differ substantially from those recorded by Muench and Schmidt (1975) in the lower Sound. However, air temperatures at Port Valdez are lower than those in lower Prince William Sound in winter and early spring (Fig. 11-9B). During this period, both the final embryonic maturation and the release of nauplii take place in S. balanoides and B. glandula in Port Valdez (Feder and Kei- ser 1980). Barnes (1959) argues that nauplii release for S. balanoides is not temperature dependent, but rather is under endoge- nous control and synchronized with the vernal diatom bloom. The period of embryonic development may be con- trolled more by availability of food for the adult and the ven- tilation frequency of the adult's mantle cavity during feed- ing than by temperature. Barnes (1959) further suggests that larval release in other northern species may also be con- trolled endogenously, but does not consider B. glandula. One should be cautious about extending Barnes' argument for endogenous control of larval release in S. balanoides to popu- lations of B. glandula at Port Valdez. S. balanoides ranges as far north as Bering Strait (Shclford 1930), and its northern limit is thought to be set by 1) the amount of time that is available for release of the nauplii, 2) the development of the planktonic phase, and 3) settlement of the cyprids during the ice-free period in the Arctic (Barnes 1957). B. glandula, on the other hand, has not been observed north of Port Val- dez (Pilsbry 1916). Nothing is known about the factors that set the northern limit of B. glandula, and one cannot dis- count the possibility that lower winter air temperatures in Port Valdez (as compared with lower Prince William Sound) limit B. glandula development in Port Valdez. The roles that sediment deposition and wave shock play in controlling S. balanoides and B. glarulula distributions in Prince William Sound are even more difficult to evaluate. Appreciable amounts of glacial silt enter Port Valdez in the form of suspended sediment in the freshwater outflow from the Lowe River, Valdez Clacier Stream, and Mineral Creek (Sharma and Burbank 1973). This silt is deposited on the shores of Port Valdez from June through August (Feder and Keiser 1980). The layer of fine silt that covers the shore dur- ing this period may cause considerable stress — especially to recently settled barnacles — but we know of no information on the relative sensitivities of the spat of 5. balanoides and B. glandula to sediment deposition. Noticeable accumulations of sediment were not observed on the shore at West and Outside Bays. The intertidal habitats at our sites in upper Prince William Sound were protected from heavy wave action, and although habitats in the lower Sound were more exposed, none of our sites could be considered in the category of exposed outer coast. Both S. balanoides and B. glandula are found in exposed as well as protected habitats (Stubbings 1975; Barnes and Barnes 1956). In laboratory tests, S. bal- anoides can withstand a relatively high impact force com- pared with other North Atlantic barnacles (Barnes, Read, and Topinka 1970); B. glandula 's resistance to impact has not been tested. Although B. glandula was not observed at our site at Siwash Bay, both the results shown in Figure 11-8 and the observations and relative abundance estimates made by O'Clair in a number of estuaries in southeastern Alaska indicate that B. glandula is rarely completely absent from protected inner shores — even when those shores are exposed to widely fluctuating salinity regimes. S. balanoides apparently cannot exclude B. glandula from inner shores — either because it is not competitively superior to B. glandula, or because it is prevented from excluding B. glandula by a third agent such as predation or disturbance. The relatively high percentage of primary space (bare rock) available at all of the sites in Prince William Sound for which we have data (Fig. 11-8) indicates that space was not a limiting factor at those sites and that barnacle populations were held in check either by predation or disturbance. Ice floes and slush ice on the shore in winter at Port Val- dez (Feder and Keiser 1980) may bash or scrape barnacles from the rocks there. Physical disturbance by ice is probably not an important factor in central and lower Prince William Sound, although predation may be. The number of species 320 Biological Resources that prey on barnacles increases from upper to lower Prince William Sound (Table 11-6). If one assumes that the effec- tiveness of any individual species of barnacle predator is not drastically reduced (except perhaps in extreme exposure), the intensity of predation is probably greater in lower Prince William Sound. One cannot rule out competition as being important to the distribution of S. balanoides. The complete absence of 5. balanoides in our samples from McLeod Harbor and Latouche Point, and from 19 of the other 28 outer-coast intertidal sites discussed in Zimmerman et al. (1979), O'Clair et al. (1978), and O'Clair et al. (1981), indicates that B. glandula may exclude S. balanoides in certain exposed situations. This is consistent with the results of Menge (1976) and Peterson (1979), who found that exposure to wave action renders predators less effective in controlling sessile filter-feeders, resulting in intense competition among the filter-feeders. In the absence of experimental evidence, one cannot decide conclusively among the possible mechanisms con- trolling the geographical trends in the relative abundances of S. balanoides and B. glandula in Prince William Sound and on the outer coast of the Gulf of Alaska. However, the evi- dence at hand suggests that while competition may play a dominant role in exposed outer coast situations, in shel- tered habitats, predation and/or disturbance prevent com- petitive exclusion of one species of barnacle by the other. Fluctuating salinity is probably the most important physical factor influencing barnacle abundances in inner waters. However, except where salinities drop well below 16°/oo, they may not directly alter the competitive hierarchy between 5. balanoides and B. glandula, but may control the distributions of the predators that prey on these species, thereby favoring S. balanoides over B. glandula. The Role of Predators in Community Organization. Evidence has accumulated in recent years suggesting that predation frequently surpasses competition in the organiza- tion of natural communities. In some systems predation Table 11-6. Species of barnacle predators at nine intertidal sites in Prince William Sound. Species of Location Predator" Total Port Valdez, North Shore NA.ET 2 Jackson Point Siwash Bay West Bay Outside Bay Point Barber NA.ET NA.OB PO, ET NL, PO, ET, LH EG,NL,NE?,SD, PO, ET, LH 2 2 2 4 7 Zaikof Bay EG,NL,NC,SD, PO, ET. LH 7 MacLeod Harbor EG, NA, NL, NC, SD, PO 6 Latouche Point EG.NA, NL, SD.LH 5 1 Vbbreviations are: EG = Empledonrma graule; NA = Nucella lima; NL = Nucella lamellnw.W- = Nucella emarginata; NC = Nxuella canalieulata.SD = Searlesia dira; OB = Onrhidoris bilamrllata:PO = Pisaster ochraceus; Y.'l = Evasterias troschelii; LH - Leplaslerias hexaetus. exerts its overriding influence by reducing the impact of competitive dominants. Perhaps because of the lower struc- tural heterogeneity typical of marine intertidal habitats, pre- dation appears to exert a stronger influence in these hab- itats than in any other (Sih, Crowley, McPeek, Petranka, and Strohmeier 1985). In the Gulf of Alaska studies of the impact of predation on intertidal and shallow subtidal commu- nities have focused on the role of large seastars and sea otters. In the following two sections we review the results of these studies. Predatory Seastars. Large predatory seastars frequently play important roles in shaping community structure in the rocky intertidal region at temperate and subpolar latitudes (see review by Menge 1982; Paine, Castillo, and Cancino 1985). On the outer coast of Washington the seastar Pisaster ochraceus clearly exerts strong control over the structure of the rocky intertidal community by preying preferentially on the mussel Mytilus californianus, the dominant competitor for space (Paine 1966, 1974; Dayton 1971, 1975a). However, Pisaster does not appear to exert the same organizational control at Torch Bay in southeastern Alaska because it and M. californianus are less abundant there (D.O. Duggins, Fri- day Harbor Laboratories, pers. comm., 1985; Paine 1980). Although Mytilus edulis constituted the greatest proportion of the diet of Pisaster at Torch Bay, the mussel population may be controlled by the predatory gastropod Nucella ( = Thais) canaliculata (Paine 1980), but this remains to be demonstrated. As at Torch Bay, Pisaster 's influence on the structure of intertidal communities in lower Prince William Sound may be reduced compared to its influence on the outer coast of Washington. Mytilus californianus was absent from Point Bar- ber (Hinchinbrook Island) and Zaikof Bay (Montague Island) when we visited these sites during 1977 through 1980 (O'Clair et al. 1978 contains initial results from this study). In May and July, adult M. edulis were found in small scattered patches at Point Barber, although an extensive area of the intertidal region was covered by very small M. edulis where adult mussels had dominated four years earlier (N.I. Calvin and J. Landingham, Auke Bay Laboratory, pers. comm., 1977). Adult M. edulis were low in abundance at the Zaikof Bay site as well. As at Torch Bay, the diet of Pisaster at both sites was low in species richness, but unlike Torch Bay, bar- nacles dominated, rather than M. edulis (Table 11-7). In the inner waters of Prince William Sound and south- eastern Alaska, Evasterias troschelii usually replaces P. ochraceus as the most common large intertidal seastar. (Eva- sterias is also common in more oceanic locations on the east side of Cook Inlet and in bays on the outer coast of the Kenai Peninsula (Dames and Moore 1977a, 1980).) Casual observa- tion of the shore at low tide in these areas reveals a sharp demarcation for the lower limit of distribution for M. edu- lis— below which free space (bare rock devoid of mac- roscopic organisms) can reach 80% of the lower intertidal zone (C.E. O'Clair, Auke Bay Laboratory, unpubl. data). Dames and Moore (1977a) found that Evasterias fed mainly on Mytilus edulis and Littorina sitkana at Dick's Head on the outer Kenai Peninsula, and they speculated that Evasterias was probably a major mortality factor for Mytilus both there and at Koyuktolik Lagoon. At Koyuktolik Lagoon, Evasterias Intertidal and Shallow Subtidal Communities 321 Tabic 11-7. Diets of Pisaster ochraceus at three locations in the Gulf of Alaska. Unless otherwise noted, numbers in body of table are numbers of individuals consumed. Sl'K 1ES Tor< 11 Bay" POIN I Barber Zaikoe Bay Barnacles Balanns glandula 71 Bala n us cariosus 13 4 Balanus spp. 182 15b 29 Mussels Mytilus edulis 733 9 Chitons Katharina tunicata 1 Mopalia ciliata 1 4 Mopalia sp. 9 Herbivorous Gastropods Collisella pelt a 4 1 Littorina sp. 1 Carnivorous Gastropods 6 1 Xtuella lumellosu 1 1 Nucella lima 1 Nucella spp. 8 16 Decapod Crustacea Pagurus beringanus 1 Paguridae sp. 1 Annelids Sabellidae sp. 2 Serpula vermicularis 1 Total No. observations 922 136 58 No. not feeding 479 462 No. species 4 13 9 a After Paine (1980) >' Value is number of observations. Several observations included many small Bal- anus that were not counted. probably set the lower limit of Mytilus in some locations (Dames and Moore 1977a). Beginning in spring 1978, O'Clair and Fritts (1980) con- ducted experiments at two sites in Auke Bay, Alaska (Fig. 11-11) to determine 1) the role that E. trosclielii plays in setting the lower limit of M. edulis and 2) whether release from pre- dation by Evasterias allows Mytilus to invade and eventually monopolize the lower intertidal region. These experiments were extended to Port Valdez in late spring 1978 (Appendix 11-2). At both localities, Evasterias preferred to eat M. edulis. Mytilus constituted 84% (n. observations, 120) and 81% (n., 395) of the diet of Evasterias at Auke Bay and Valdez, respectively. At Auke Bay, the species which colonized the cages, plots, and roofs were species common to the mid- to upper-inter- tidal zones. Barnacles, particularly Semibalanus balanoides, and later M edulis, colonized the cages (Figs. 11-12 and 11-13). By September 1978, the percentage of barnacles (mostly S. balanoides and a few B. glandula) found in the cages signifi- cantly exceeded the percentage found in roofs and plots at both the Evasterias removal and control sites (Figs. 11-12 and 11-13; Table 11-8). Barnacles in the cages at the Evasterias removal site suffered heavy mortality during September and October in both 1978 and 1979 when the predaceous nudibranch Onchidoris bilamellata invaded the cages and ate numerous barnacles (Fig. 11-14). Onchidoris was in low abun- r\J]y SlUcK' AVVd \ i |uncau KclthilumW I Figure 11-11. Map of Auke Bay and vicinity showing study sites. (Modified from Bruce, McLain, and Wing 1977.) dance at the control site — barnacle coverage remained high in the cages then gradually decreased as Mytilus colonized them (Fig. 11-15; Table 11-8). Barnacles failed to increase both in the plots and under roofs at both sites in 1978 and 1979 — probably because of predation by the sea urchin Strongyfocentrotus droebachiensis, which may consume cyprids and juvenile barnacles while grazing. (Nucella was rare at both the Evasterias removal and control sites. Only a few N. lima were seen there during the entire study.) Urchins were abundant at both sites in 1978 and 1979. In the summer of 1980, urchins unexplainably decreased at the Evasterias removal site. No urchins were found there in June 1980, whereas —1,000 were counted at the control site. Barnacles, particularly Semibalanus bal- anoides, increased significantly at the Evasterias removal site between June 1979 and June 1980 (Table 11-8). In July, Onchidoris returned in great numbers and by September 1980, barnacle populations were significantly reduced in plots and under roofs (Fig. 11-14; Table 11-8). The suppression of barnacle populations by Strongylo- centrotus droebachiensis and O. bilamellata may indirectly inhibit Mytilus recruitment by reducing the preferred set- tling substrate for Mytilus. At Auke Bay, larval M. edulis settle in large numbers on barnacle shells, perhaps because fila- mentous algae are uncommon there (C.E. O'Clair, pers. obs.); D. Duggins has observed M. edulis to settle abundantly on Balanus at Torch Bay, Alaska, as well (D.O. Duggins, Fri- day Harbor Laboratories, pers. comm., 1985). S. droebachiensis may also directly limit Mytilus recruitment by preying on plantigrades and juvenile mussels. Mytilus began settling within the cages in 1979; settlement in plots and roofs was generally later (Figs. 11-12 and 11-13). At the Evasterias removal site, Mytilus coverage increased in all treatments to the end of the study. However, increases in Mytilus coverage in the plots and under roofs was less than expected in the absence of Evasterias. By August 1981, Mytilus coverage in the cages significantly exceeded the coverage both in plots and under roofs at the Evasterias removal site. Mytilus coverage in plots and roofs at the Evasterias removal 322 Biological Resources Cages Evasterias Removal Site Roofs —■ 100 r 80 u 0 60 u H 40- Z u « 20- ,H',A'n'1Jr1 — p*n — i-T^^f-t-f-i-r- i«-i— | — i — r— ^r— | — r-r-^--r-f Plots 100 80 H 60 40 20 0 - /v— — • Bare rock *- All barnacles • Mytilus edulis 1978 1979 1980 1981 Figure 11-12. Percent cover of Mytilus edulis, all barnacles, and bare rock in cages, roofs, and plots at the Evasterias removal site at Auke Cape in Auke Bay from April 1978 to September 1981. Cages Evasterias Control Site # 100- 80- 60- 40- 20 0 - itoofs > "^^"v * " >■ /—A - u X 111 4 wr'^ >v I 100 80 60 40 20 0 Plots ■ Bare rock *■ All barnacles • Mytilus edulis A 1 ^-r«~>- 1978 1979 1980 1981 Figure 11-13. Percent cover of Mytilus edulis, all barnacles, and bare rock in cages, roofs, and plots at the Evasterias control site at Auke Cape in Auke Bay from April 1978 to September 1981. Intertidal and Shallow Subtidal Communities 323 Table 11-8. Statistical tests for Evasterias troschelii removal experiment at Auke Bay, June 1978-Scptember 1981. Sim ( its Si i e Comparison Type of Analysis" Sk.niik \\( I Level Kll R \( I IONS Barnacles1' Evasterias Cages vs. roofs &.- plots removal September 1978 Control Cages vs. roofs & plots September 1978 Evasterias Cages vs. roofs &.- plots removal July 1979 Control Cages vs. roofs 8c plots July 1979 Evasterias June 1979 vs. June 1980 removal plots and roofs Control June 1979 vs. June 1980 plots and roofs Evasterias June 1980 vs. Sept. 1980 removal plots and roofs Control June 1980 vs. Sept. 1980 plots and roofs 2-way anova t-test ]X 0.001 p< 0.001 2-way anova t-test p< 0.001 p<0.001 3-way anova t-test ]X(). 01 U.S. 3-way anova t-test p<0.01 p<0.05 2-way anova Scheffes-test p<0.01 p<0.05 2-way anova Scheffes-test p<0.01 p<0.05 3-way anova Scheffes-test p< 0.001 p<0.05 3-way anova Scheffes-test p< 0.001 n.s. 2-way anova t-test p<0.05 p<0.01 2-way anova t-test p<0.05 n.s. 2-way anova t-test p<0.05 n.s. Mytilus Evasterias removal Control Evasterias removal and control Cages vs. roofs & plots August 1981 Cages vs. roofs &.- plots August 1981 ER vs. control plots & roofs. August 1981 LR = Evasterias removal site; n.s. = not significant. •' Data were transformed (arcsin y/poTyJWOp, p = proportion of coverage) to stabilize variances before analysis. Bartlett's test was used to verify homogeneity of variances. Individual comparisons of simple main effects were made with a t-test (a priori; Winer 1971) or Scheffes test (a posteriori) and were one-tailed. h Mostly Semibaianus balanoides with some Balanus glandula. site did not exceed those at the control (Table 11-8). Nev- ertheless, near the center of the Evasterias removal site on a 6-m long stretch of shore, Mytilus had extended its former lower limit 2 m into the lower intertidal zone — apparently because Evasterias was removed. The results of O'Clair and Fritts's (1980) experiments in Auke Bay are summarized in Figure 11-16. Strongylocentrotus droebachiensis directly limits Mytilus recruitment by preying on plantigrades and juvenile Mytilus, or indirectly limits recruitment by consuming barnacles that are Mytilus' pre- ferred settling substrate. When Onchidoris bilamellata is pre- sent, it consumes the barnacles that have escaped urchin predation. This prevents Balanus from maintaining popula- tions in the lower intertidal zone and probably delays Mytilus recruitment. Evasterias may ultimately preclude Mytilus from dominating the lower intertidal zone, but the activities of Strongylocentrotus and Onchidoris usually prevent Mytilus from even becoming accessible to Evasterias predation. The intertidal community at Port Valdez was less com- plex. S. droebachiensis and O. bilamellata were absent from both the Evasterias removal and the control sites and Nucella was rare. The results of the Port Valdez experiments sup- ported the hypothesis that Evasterias controlled the lower limit of distribution for Mytilus on the north shore of Port Valdez. By the end of the experiment (September 1981), cov- erage of M. edidis had increased significantly compared to coverage at the beginning of the experiment (June 1978). This was true for all treatments at the Evasterias removal site and for the cages at the control site (Table 11-9). Coverage of Mytilus averaged between 70 and 80% in these treatments by September 1981. Mytilus coverage in the plots and under the roofs at the control site did not increase significantly between June 1978 and September 1981 (Table 11-9). How- ever, Mytilus coverage was quite variable in the plots and roofs at the control site in September 1981. We could not stabilize coverage-estimate variances, so we used the less powerful Mann-Whitney U-test to make comparisons. The results were significant, but not as strik- ing as one would expect if Evasterias exerted complete con- trol over the lower limit of Mytilus. Why M. edidis increased in some plots and roofs at the control site is open to specula- tion. Evasterias on the north shore of Port Valdez averaged 104 g fresh (drip-dried) weight and were significantlv smaller (p< 0.001, oneway anova) than Evasterias, which had an average fresh weight of 275 g at Auke Bay. The small size of Evasterias may have allowed Mytilus to successfully colo- nize some of the plots and roofs at the control site in Port Valdez. Sea Otters. In the western Aleutian Islands, large sea otter populations (Enhydra lutris) inhabit certain islands and con- sume a variety of invertebrates — especially sea urchins 324 Biological Resources Cages Evasterias Removal Site ^ z u a S c X u z 0 1978 1979 1980 Figure 11-14. Percent cover of barnacles and density of Onchidoris bilamellata in cage sets at the Evasterias removal site at Auke Cape in Auke Bay from April 1978 to September 1980. Error bars are one standard deviation from either side of the mean. Cages Evasterias Control Site !£ < - 100 -i 80 - 60 40- 20 Balanus spp. Onchidoris bilamellata 1978 1979 1980 Figure 11-15. Percent cover of barnacles and density of Onchidoris bilamellata in cage sets at the Evasterias control site at Auke Cape in Auke Bay from April 1978 to September 1980. Error bars are one standard deviation from either side of the mean. Urchins absent (cages) Urchins present (control) Barnacles settle and grow Onchidoris absent Onchidoris present Af, Barnacle populations increase § Barnacle populations decimated I Mytilm sets on barnacles Mytilus outcompetes barnacles Evasterias consumes mytilus \ \ J Barnacle populations low ? Mytilus Mytilus absent settlement delayed 50-90% free space Figure 11-16. Summary of the results of an experiment at Auke Cape in Auke Bay in which Evaslerias troschelii was removed. Successful colonization of the low intertidal zone by Mytilus depended on reduction in abundance of urchins (Strongylo- centrotus droebachiensis) and Onchidoris bilamellata. Barnacles include Balanus glandula and Semibalanm balanoides. Intertidal and Shallow Subtidal Communities 325 (Strongylocentrotus polyacanthus) and bottom fish (Kenyon 1969; Burgner and Nakatani 1972; and Estes, Jameson, and Rhode 1982). The sea urchins that are preyed upon by the otters are important grazers on marine algae. Other species of Strongylocmtrotus have been shown to cause large-scale kelp bed destruction which may persist for many years (Leighton 1971; Breen and Mann 1976; and Mann 1977). Estes and Palmisano (1974) compared the sublittoral and lower intertidal communities on Amchitka Island (with its popula- tions of sea otters) to the same nearshore communities on Shemya Island (without sea otters). They found striking dif- ferences in the nearshore communities between the two islands. Amchitka Island had fewer and smaller sea urchins, especially in the shallow sublittoral region above the 15- to 18-m range — the apparent lower limit of effective sea otter foraging (Fig. 11-17; Estes el ai 1978). The reduced sea urchin biomass on Amchitka was accompanied by extensive inter- tidal and subtidal kelp beds (Laminaria spp., Alaria fislulosa, Agarum cribrosum, and Tkalassiophyllum clathrus) as well as reduced populations of mussels, barnacles, limpets, and chitons in the intertidal region (Estes and Palmisano 1974; Palmisano and Estes 1977; and O'Clair 1977a). There was also an abundant, diverse nearshore ichthyofauna (Sim- enstad, Isakson, and Nakatani 1977). At Shemya, offshore kelp beds were sparse, and the lower intertidal algae were heavily grazed by the large, abundant sea urchins (Estes and Palmisano 1974) (Fig. 11-17). Dense populations of mussels (Mytilus edulis) and barnacles (Semibalanus cariosus and Bal- anus glandula) occupied the shore at Shemya Island (Pal- misano and Estes 1977). Simenstad et ai (1978) examined faunal remains in the strata of a prehistoric Aleut midden at Amchitka Island and found a temporal pattern of faunal composition which was consistent with the spatial pattern observed by Estes and Pal- misano (1974) at Amchitka versus Shemya Islands. Sim- enstad et al. (1978) found an inverse relationship between the number of sea otters, fish, and harbor seals that were har- vested by the Aleuts and the number of sea urchins and limpets harvested by the Aleuts for the same time period. Table 11-9. Statistics for coverage of Mytilus edulis in Evasterias removal experiment at Port Valdez,June 1978 to September 1981. EVASTERIAS Treatment Mytilus Mean Cover (%) June Sept. 1978 1981 Type of Analysis Significance Level [nter vctions Removal Cages Plots Roofs 12 21 27 78 71 2-way anova t-test 2-way anova t-test 2-way anova t-test p< 0.001 p< 0.001 p<0.001 p< 0.001 p< 0.001 p< 0.025 Control Cages Plots Roofs 20 29 32 71 58 65 1-wav anova Mann-Whitney U-test Mann-Whitney U-test p<0.05 n.s. n.s. = not significant ■' Data were transformed (arcsin Vp. p = proportion of coverage) lo stabilize variances for parametric tcMv Homogeneity ol variance was verified »iili Bartlelt's test Individual comparisons of simple main effects were made with t-tesis (Winer 1971) when variances wen- homogeneous, otherwise with the Mann- Whitne) I -test Ml tests are one-tailed. 326 Biological Resources Shemya Island — No Otters 500 400 200 Algal Cover 100 80 60 "tf u > C O 40 20 12 18 Depth (m) 40 60 Test Diameter (mm) Amchitka Island — Otters Abundant 500 C 300 200 100- 100 40 £8 > 0 u -J < o 12 Depth (m) 1 2 0.4 A 20 40 60 Test Diameter (mm) 80 Figure 11-17. Comparative relationships of sea urchin population densities to algal cover and sizes of individual sea urchins to urchin biomass between Aleutian islands with sea otters (Amchitka) and without sea otters (Shemya). (Modified from Estes and Palmisano 1974.) Simenstad et al. (1978) attributed the stratigraphic replace- ment of the former species assemblage by the latter species assemblage to overexploitation of sea otters — an exploita- tion that caused a shift in the nearshore community from one dominated by sea otters to one with few sea otters and abundant sea urchins and limpets. Without the grazing pressure normally exerted by sea urchins at Amchitka, competition for light and space assumed a more important role in organizing the benthic macrophyte populations. Dayton (1975b) manipulated algal canopies in the sublittoral region at Amchitka and found that in the shallow areas, removing the stipes and fronds of Laminaria longipes resulted in complete recolonization by that species. The rhizoidal growth pattern of L. longipes pre- sumably gives that species an advantage over Laminaria spp., Alaria, and Agarum cribosum following disturbance if the holdfasts of L. longipes remain intact (Dayton 1975b). Dayton's (1975b) experiments in the deeper subtidal area indicated that Laminaria spp. suppressed the growth of Agarum cribrosum, and that either Laminaria or Agarum could suppress the recruitment and growth of Alaria j is tulosa. Despite its larger size and dominance in the floating canopy, Alaria fistulosa behaved as a fugitive species in Dayton's (1975b) experiments. Duggins (1980a, b) simulated sea otter dominance, then examined competitive interactions among kelps (Laminaria groenlandica, Nereocystis luetkeana, Alaria fistulosa, Cymathere triplicata, and Costaria costata) in a shallow subtidal commu- nity at Torch Bay, Alaska. Duggins mimicked the influence of sea otters by removing sea urchins (Strongylocentrotus fran- ciscanus, S. purpuratus, and S. droebachiensis) from plots with an area of ~ 50 square meters. Plots where sea urchins were removed were initially colonized by both annual (especially Nereocystis) and perennial kelps. By the second year of the Intertidal and Shallow Subtidal Communities 327 experiment, L. groenlandica dominated the experimental plots, resulting in a reduction in both the biomass and diver- sity of kelps when compared with the first year after the urchins were removed. Without sea otters, the shallow subtidal community at Torch Bay became a mosaic of kelp patches. The patches were created when the kelps were temporarily released from grazing pressure because the sea star Pycnopodia helianthoides began preying on Strongylocentrotus droebachiensis and S. purpuratus, forcing them into a three-species aggrega- tion with S. franciscamis in order to escape predation (Dug gins 1981a, 1983). The faster growing annual species (e.g., Nereocystis and Alaria) in this community occasionally escaped urchin herbivory long enough to reach a large size (thereby avoiding further grazing by urchins) when the urchins temporarily switched from grazing the benthic mac- roalgae to eating ephemerally abundant food sources such as drift algae, diatoms, or (unusually) salps (Duggins 1981b, 1983). Community Response to Sudden Land-Level Changes Both the continental coasts and the islands that rim the Pacific Ocean have an active seismic history. Sudden uplift of the shore is often the greatest source of earthquake- related mortality among marine organisms (see review by Brongersma-Sanders 1957). Mass mortalities of marine organisms resulting from land-level changes caused by major earthquakes have been recorded at a variety of places, including Chile (Graham 1824; Fitz-roy 1839; and Davison 1936), Mexico (Bodin and Klinger 1986), Alaska (Tarr and Martin 1912; Haven 1971; andjohansen 1971), and Japan (Kaburaki 1928). In the Gulf of Alaska, sudden changes in the land level that followed both the Great Alaskan Earth- quake of 1964 and the underground nuclear testing on Amchitka Island have permitted studies of the changes in intertidal and shallow subtidal communities that take place following either an uplift or a downthrust of the shore. The Great Alaskan Earthquake lifted some littoral shores in Prince William Sound as much as 10 m, displacing the entire intertidal region to a position above the range of the tides. Several researchers, includingjohansen (1971), Haven (1971), Hubbard (1971), and Baxter (1971), recorded popula- tion changes for algae and invertebrates in the intertidal and shallow subtidal regions of Prince William Sound fol- lowing the Alaska Earthquake. Fifteen months after the earthquake — when Johansen and Haven first visited the dis- turbed sites — virtually all the intertidal organisms and those sublittoral species that were lifted into the intertidal region on the maximally uplifted shores had died (Johansen 1971; Haven 1971). A conspicuous white zone composed of the cal- careous remains of coralline algae, serpulid worm tubes, bryozoans, and mollusk shells extended from the pre-earth- quake lower mid-littoral zone down to —9.0 m below the pre-earthquake zero tide level (Haven 1971). On moderatelv uplifted shores, the amount of effect the uplift had depended on several factors, including its magni- tude, the type of habitat, the species, and (for algae) the age of the individual (Johansen 1971; Haven 1971). With the exception of barnacles (Balanus glandula, Semibalanus \ = Balanus] cariosus, and CJithamalus dalli) which Haven (1971) found alive nearly 1 m above their normal upper limits, organisms that were lifted above their pre-earthquake upper limits were killed. On intertidal shores which had sub- sided into the sublittoral region, mussels, barnacles, and Fucus were alive in the post-earthquake Laminaria zone and appeared to be inhibiting the development of Laminaria and associated fauna (Haven 1971). Species composition and the vertical ranges and relative abundances of species in the post-earthquake mid-littoral zone 15 months after uplift were generally similar to the inferred pre-earthquake conditions. However, Haven (1971) found evidence that some post-earthquake communities were at a relatively early stage of development. Film- forming algae rather than Verrucaria occupied the post- earthquake Verrucaria zone. On those uplifted shores that rose the highest, Porphyra rather than Fucus dominated the mid-littoral zone. In contrast to the relative abundances inferred for pre-earthquake barnacles, after the earth- quake, Semibalanus balanoides rather than Balanus glandula appeared to dominate the upper mid-littoral zone (Appen- dix 11-3). MytUus edulis were frequently attached to algae rather than rock — the substrate usually occupied by mussels beyond the plantigrade stage. The overall rate of develop- ment of the post-earthquake community appeared highest in the Laminaria zone and decreased from there upward (Haven 1971). Grazing, both by limpets (Collisella [= Acmaea) pelta, C. strigatella [ = A. paradigitalis], C. digitalis, Notoacmea [ = Acmaea] scutum, N. persona, and Sipkonaria thersites) and by littorines (Littorina sitkana and L. scutulata), may have influenced the development of algal populations in the post-earthquake mid-littoral zone. This was evidenced by 1) inverse correla- tions between limpet populations and both the mem- branous and the filamentous algae in the upper mid-littoral zone, 2) a grazing line found at the lower limit of the vertical distribution of encrusting microalgae which occupied the post-earthquake Verrucaria zone — below which Collisella strigatella and littorines were actively feeding, and 3) Por- phyra becoming dominant in the post-earthquake Fucus zone on stretches of shore where grazers were rare (Haven 1971). Haven returned to Prince William Sound four and one-half years after the earthquake and generally found that post-earthquake communities were essentially the same as pre-earthquake communities that were inferred for the same tidal level. Balanus glandula had replaced Semi- balanus balanoides to various degrees as the dominant barna- cle, and Fucus had replaced Porphyra as the dominant alga in the post-earthquake upper mid-littoral zone. Mytilus was attached to both rocks and barnacles beneath the canopy algae, and its lower limit appeared to be set by seastar preda- tion. However, a distinct Verrucaria zone had not formed. When viewed as an intertidal experiment in land-level change, the underground nuclear testing on Amchitka Island allowed for experimental designs that could detect and quantify those changes in the intertidal communities that were caused by uplift more sensitively than the designs 328 Biological Resources that could have been employed following the Great Alaska Earthquake. In contrast to the earthquake, the timing of each detonation was controlled, and the pre-blast distribu- tion and abundance for intertidal organisms were accu- rately estimated. While geologists could not predict the exact location, nature, or magnitude of the land-level change, knowing the epicenter let scientists choose experi- mental and control (reference) sites with reasonable confidence. The underground nuclear test designated Milrow (Fig. 11-18) was fired on October 2, 1969, and lifted ~ 4 ha of inter- tidal bench on the Pacific side of Amchitka 12 cm as a result of a shift along a pre-existing fault line (Lebednik 1973). The uplift, which was 13% of the mean tide range at Amchitka, was equivalent to a 40-cm (13% of the mean tide range at Cordova, Alaska) displacement in Prince William Sound. 179°10' 179°20' ^\I\ 9 ^ClA 3 C^^ ^-w — Banjo Point ^^^^vTV^ Bering Sea • \BIG ^^^m. Cannikin test ^N"\_^--^0 51° surface zero ( 30' \\ v^-i k C \ \ \ 1 Pacific Ocean ^^li\ C^~t> 179° ■t ** k. ^\ 51° "% ^^~\ I s-**) 25' k •Milrow test ^~""\/ J e& tt - /> l USSR (Order Dysodonta). Opredeliteli po Faune SSSR. hdavaemye Zoologicheskim Muzeem Institut Akademi Nauk, SSSR 71:1-150. (in Rus- sian) Schultz, R.D. and R.J. Berg 197(5 Some effects of log dumping on estuaries. Proc- essed report, Environmental Assessment Divi- sion, National Marine Fisheries Service, Juneau, AK. 64 pp. Science Applications, Inc. 1979 Environmental Assessment of the Alaskan Outer Continental Shelf: Lower Cook Inlet Interim Synthesis Report. Boulder, CO. 241 pp. Science Applications, Inc. 1980a Environmental Assessment of the Alaskan Continental Shelf: Northeast Gulf of Alaska Interim Synthesis Report. Boulder, CO. 313 pp. Science Applications, Inc. 1980b Environmental Assessment of the Alaskan Continental Shelf: Kodiak Interim Synthesis Report. Boulder, CO. 326 pp. Sears, H.S. and S.T. Zimmerman 1977 Alaska Intertidal Survey Atlas. National Marine Fisheries Service Auke Bay Laboratory, Auke Bay, AK. 402 pp. Sharma, G.D. and D.C. Burbank 1973 Geological oceanography. In: Environmental Studies of Port Valdez. D.W. Hood, W.E. Shiels, and E.J. Kelley, editors. Occasional Publication No. 3, Institute of Marine Science, University of Alaska, Fairbanks, AK. pp. 15-100. Shelford, V.E. 1930 Geographic extent and succession in Pacific North American intertidal (Balanus) commu- nities. Publications of the Puget Sound Marine Bio- logical Station 7:217-224. Sih, A., P. Crowley, M. McPeek, J. Petranka, and K. Strohmeier 1985 Predation, competition, and prey commu- nities: a review of field experiments. Annual Review of Ecology and Systematics 16:269-311. Simenstad, C.A., J. A. Estes, and K.W. Kenyon 1978 Aleuts, sea otters and alternate stable-state communities. Science 200:403-411. Simenstad, C.A., J.S. Isakson, and R.E. Nakatani 1977 Marine Fish communities. In: The Environment of Amchitka Island, Alaska. M.L. Merritt and R.G. Fuller, editors. National Technical Informa- tion Service, Energy Research and Develop- ment Administration, Springfield, VA. pp. 451-492. 344 Biological Resources Smith, N.I. 1972 Intertidal communities of Berner's Bay, Alaska. M.S. Thesis, Western Washington State Univer- sity, Bellingham, WA. 77 pp . Snow, A.A. and SAV. Vince 1984 Plant zonation in an Alaskan salt marsh. II. An experimental study of the role of edaphic con- ditions.Journal of Ecology 72:669-684. Stubbings, H.G. 1975 Balanus balanoides. L.B.M.C. Memoirs on Typ- ical British Marine Plants and Animals No. 37, Liverpool University Press, Liverpool. 175 pp. Tarr R.S. and L. Martin 1912 The earthquake at Yakutat Bay, Alaska, in Sep- tember 1899. U.S. Geological Survey Profes- sional Paper 69. 135 pp. Valentine,J.W. 1966 Numerical analysis of marine molluscan ranges on the extratropical northeastern Pacific shelf. Limnology and Oceanography 11:198-211. Vince, S.W. and A.A. Snow 1984 Plant zonation in an Alaskan salt marsh. I. Dis- tribution, abundance and environmental fac- tors. Journal of Ecology 72:651-667. VTN Environmental Sciences, Inc. 1982a 1981 Boca de Quadra monitoring study: coastal and marine biology program — Quartz Hill Molybdenum Project, Southeast Alaska. Pre- pared for U.S. Borax and Chemical Corpora- tion, Los Angeles, CA. 79 pp. plus appendices . VTN Environmental Sciences, Inc. 1982b 1982 Boca de Quadra and Wilson Arm-Smeaton Bay monitoring study, Annual Environmental Report, Quartz Hill Molyb- denum Project, Southeast Alaska. Prepared for U.S. Borax and Chemical Corporation, Los Angeles, CA. 161 pp. plus appendices . VTN Environmental Sciences, Inc. 1983 Interrogative data analysis: coastal and marine biology program — Quartz Hill Molybdenum Project, Southeast Alaska. Prepared for U.S. Borax and Chemical Corporation, Los Angeles, CA. 162 pp. Winer, BJ. 1971 Statistical Principles in Experimental Design, 2nd edition. McGraw-Hill Book Company, New York, NY. 907 pp. Zimmerman, S.T. and T.R. Merrell, Jr. 1976 Baseline characterization, littoral biota, Gulf of Alaska and Bering Sea. Environmental Assess- ment of the Alaskan Outer Continental Shelf Annual Reports of Principal Investigators for the Year ending 1976 6(Receptors — fish, littoral, benthos):75-584. Zimmerman, S.T., J.L. Hanson, J.T. Fujioka, N.I. Calvin, J.A. Gharrett, andJ.S. MacKinnon 1979 Intertidal biota and subtidal kelp communities of the Kodiak Island area. Environmental Assess- ment of the Alaskan Continental Shelf Final Reports of Principal Investigators 4(Biological Stud- ies):316-508. Zimmerman, S.T., J.H. Gnagy, N.I. Calvin, J.S. MacKinnon, L. Barr,J. Fujioka, and T.R. Merrell, Jr. 1977 Baseline/reconnaissance characterization, lit- toral biota, Gulf of Alaska and Bering Sea. Environmental Assessment of the Alaskan Continen- tal Shelf Annual Reports of Principal Investigators for the year ending March 1977 8(Receptors — fish, littoral, benthos):l-228. The Subtidal Benthos 12 Howard M. Feder Stephen C. Jewett Institute of Marine Science University of Alaska Fairbanks, Alaska Abstract This chapter considers the subtidal benthos of the Gulf of Alaska shelf, the Gulfs embayments, and its fjords. It presents a brief historical review of both fisheries and non-fisheries work, examines benthic data in order to assess both infaunal and epi- faunal species-distribution patterns and biomass, discusses those environmental vari- ables that are responsible for community composition, and briefly considers trophic groups and the feeding interactions between invertebrates and fishes. Benthic pro- duction estimates for the shelf of the northeast Gulf and for lower Cook Inlet are also calculated. The mean macrofaunal production for the northeast Gulf of Alaska (NEGOA) is estimated at 4.5 g C/m2y, with total benthic (microflora, meiofauna, and macrofauna) production estimated at 13.7 g C/m2y. Infaunal production estimates for lower Cook Inlet vary between 2.5 and 10 g C/m2y. The chapter also covers the rela- tionships between the physiographic and the oceanographic features of the Gulf as well as those carbon-concentrating mechanisms that lead to benthic enrichment. Introduction The shelf, embayments, and fjords of the Gulf of Alaska are characterized by many epifaunal invertebrate and demersal fish species of actual or potential commercial importance. These species include shrimps, crabs, snails, scallops, flatfishes, and cod. Since many of these species feed — in whole or in part — on infaunal and epifaunal resi- dents of the bottom (Feder and Jewett 1981a; Feder and Paul 1980; Feder, Jewett, McGee, and Matheke 1981; Feder, Paul, Hoberg, and Jewett 1981), changes in either the distribution or the abundance of these prey organisms will affect the commercially important species that feed on them (Zenkevitch 1963; Feder, Paul, Hoberg, and Jewett 1981; and Feder and Jewett 1981a, b). There are a number of industrial activities taking place on the shelf that have been shown to affect other shelf sys- tems. These activities include: • offshore mining and petroleum activities • intensified bottom fishing • coastal development, including dredging activities for port improvement and increased sewage input into coastal waters (Zijlstra 1972; Mclntyre 1977; and Pearson and Rosenberg 1978). Preliminary assessment of the benthos on the Gulf shelf suggests that the fauna is influenced by the Alaska Coastal Current in conjunction with heavy sediment loads that originate from glacial meltwater (H.M. Feder, Univer- sity of Alaska, unpubl. OCSEAP data; Rover, Hansen, and Pashinski 1979; Feder and Matheke 1980a'; and Rover 1981, 1982, 1983). Thus, potential alteration of the benthic environment of the Gulf must be considered in the context of both human activity and naturally occurring stresses. Infaunal benthic organisms are frequently chosen to monitor the long-term effects of pollution, and often reflect the biological health of marine areas (Pearson 1971, 1972, 1975; Rosenberg 1973). Benthic organisms in the Gulf (pri- marily infauna, but also epifauna) were emphasized in the biological studies of the 1970s which were sponsored by the Outer Continental Shelf Environmental Assessment Pro- gram (OCSEAP)(Feder and Matheke 1980a). OCSEAP- sponsored programs broadened the historical data, devel- oped an inventory of benthic species, examined community structure, and initiated investigations of the food habits of dominant species. 347 348 Biological Resources In this chapter, the continental shelf, along with its embayments and fjords, is discussed in terms of both the qualitative and the quantitative data that exist on infaunal and epifaunal species composition and distribution. The environmental variables responsible for community struc- ture of the benthos are also discussed. Two additional sub- ject areas considered in this chapter are the feeding interac- tions among infaunal, epifaunal, and nektobenthic predators, and benthic production estimates for two regions of the shelf — northeast Gulf of Alaska (NEGOA) and lower Cook Inlet. Finally, the relationships between phvsiographic and oceanographic features of the Gulf are briefly examined, as well as those carbon-concentrating mechanisms that may lead to benthic enrichment. In benthic studies, those invertebrates sampled by either grab or trawl methods are termed infauna and epifauna, respectively. Occasionally, organisms may be taken by both sampling methods and in these cases they are usually cate- gorized as either infauna or epifauna, depending on the method used to capture it. This classification rationale is fol- lowed in the Soviet, National Marine Fisheries Service (NMFS), and OCSEAP investigations discussed in this chap- ter. For example, small surface-dwelling organisms such as seastars, ophiuroids, heart urchins, and sand dollars are typically characterized as infauna, but when abundant they are also captured in trawls. Including these organisms in trawl-capture data sets can provide useful information for categorizing a benthic area. In most benthic studies, some of the species that are col- lected by grab methods — and that are used in subsequent analyses — are slow-moving surface dwellers. These organ- isms are often categorized as infauna in order to permit the assessment of abundance, biomass, and production of the small species that can be captured by this equipment. The latter approach — used in the investigations of Shevtsov (1964a, b), Semenov (1965), Feder and Matheke (1980a), and Bakus and Chamberlain (1975) — is also used in this chapter. Historical Review General The Gulf of Alaska has historically been the site of a number of important fisheries, including: • Dungeness crab (Cancer magister) • Tanner crab (Chionoecetes bairdi) • red king crab (Paralithodes camtsdiatica) • shrimps (Family Pandalidae) • scallop (Pecten caurinus) • Pacific cod and walleye pollock (Family Gadidae) • flatfishes (Family Pleuronectidae) • rockfishes (Family Scorpaenidae) (Alaska Department of Fish and Game 1985a, b, c, d; Ronholt, Shippen, and Brown 1978; and Smith, Hadley, French, Nelson, and Wall 1981). Most of these species use benthic organisms as a major component of their diet (Alton 1974; Feder and Paul 1980; Feder, Haflinger, Hoberg, and McDonald 1980; Feder and Jewett 1981a, b; Feder, Paul, Hoberg, andjewett 1981; and McDonald, Feder, and Hoberg 1981). However, despite the obvious trophic importance of the benthos to the Gulf ecosystem, little biological data were available for these organisms until the OCSEAP-sponsored studies were initiated in 1974. The biological literature and unpublished data on the Gulf benthos collected through 1976 are summarized in Feder (1977) as well as in the review of the renewable resources of the northern Gulf found in Rosenberg (1972). Shevtsov (1964a, b) and Semenov (1965) describe infaunal as well as dominant epifaunal Gulf species assemblages, and discuss the relationships between the water depth, the sub- strate type, and the prevalent feeding modes (see summary in Cooney 1972). They divide the continental shelf and upper slope between Unimak Pass and Graham Island (in Southeast Alaska) into western, northern (NEGOA), and eastern regions. They define the boundary between the western and northern areas as a line running to the south- east from the southern tip of the Kenai Peninsula. Their boundary of the eastern area coincides with the geo- morphological boundary of the eastern areas of the shelf and the continental slope (approximately off Cape Spencer). Although few data were available for the eastern area, the low organic carbon content of the sediment and the strong tidal currents there led them to separate this region from the northern area. The relative importance of the various trophic groups and associated bottom type by region, on the shelf and slope, is also considered by Semenov (1965) (Tables 12-1 through 12-3). NEGOA Shelf A summer survey by Bakus and Chamberlain (1975) examined the infauna and epifauna in a small area on the NEGOA shelf south of the Bering Glacier. The results of this study are similar to those of Shevtsov (1964a, b), Semenov (1965), Feder, Mueller, Matheke, andjewett (1976), Feder and Matheke (1980a), and Feder andjewett (University of Alaska, unpubl. OCSEAP data on file at the National Oceanographic Data Center [NODC], Washington, D.C. 20235) for the entire NEGOA shelf. Hickman and Nesbitt (1980) describe the infaunal mollusk associations in the Yakataga-Yakutat regions of the northern Gulf. Trawl surveys for resource assessment span nearly 30 years and provide detailed spatial, qualitative, and quan- titative coverage of the epifauna of NEGOA. Ronholt et al. (1978) present a comprehensive historical review of com- mercially important shellfishes and finfishes for the years 1948 to 1976. This review, which covers the broad region from Cape Spencer to Unimak Pass, includes mostly unpublished surveys done by the NMFS (formerly Bureau of Commercial Fisheries) and by the International Pacific Halibut Commission (IPHC). Included in this review is a 1961 to 1962 survey from Kodiak Island to Cape Spencer (Hitz and Rathjen 1965) and a 1975 survey from Yakutat Bay to Cape Cleare (Ronholt, Shippen, and Brown 1976). Two additional surveys examined the non-commercial epifauna in detail, as well as examining the commercial spe- The Subtidal Benthos 349 Table 12-1. Relationship between the distribution of trophic groups and the type of bottom sediment (Semenov 1965). Bottom Sediment Organic Filter Feeders Dl • IRII I 's Feede ks Carnivores Total Type Non-mobile Mobile Browsers Non-selective Biomass Carbon g/ms % g/m2 % g/m2 % g/m2 % g/m2 % g'm2 Mud 0.80 0.66 1.0 1.27 2.0 11.16 11.7 41.90 66.4 8.15 12.9 63.14 Sandy mud 0.50 0.19 0.3 2.65 4.57 11.51 19.9 39.54 68.3 4.03 6.96 57.92 Muddv sand 0.51 12.88 32.5 1.08 2.72 15.55 39.6 5.75 14.4 4.54 11.4 39.80 Sand 0.39 0.64 1.3 19.13 40.1 20.26 42.5 0.51 1.12 7.17 15.0 47.71 Mud with admixture of pebbles and gravel - 7.09 17.0 7.09 17.0 1 5.05 36.2 5.71 13.7 6.66 16.0 41.60 Sandy mud, gravel, pebbles 32.46 46.0 4.62 6.55 1 7.99 25.6 13.53 19.3 1.88 2.67 70.38 Muddv sand, gravel, pebbles - 62.69 52.2 18.76 15.6 22.27 18.5 4.16 3.46 12.35 10.2 120.23 Pebbles, gravel, sand, stones, shells - 15.82 31.7 9.55 19.0 12.22 24.5 1.35 2.70 11.00 22.1 49.94 Rocks - 470.30 91.0 4.78 0.923 11.90 2.3 0.04 0.007 30.27 5.85 517.29 cies. In the summer of 1975, the first survey was conducted on the shelf between Yakutat Bay and Cape Cleare (H.M.Feder and S.C.Jewett, University of Alaska, unpubl. OCSEAP data on file at NODC; Ronholt et al. 1976), and in November 1979 the second survey covered the waters near Icy Bay extending southeasterly to near Lituva Bay (Feder, Jewett, McGee, and Matheke 1981). Portions of the region between Icy Bay and Yakutat Bay were sampled during both surveys. Only limited information is available on the feeding habits of the epifauna and the demersal fishes of NEGOA (Smith, Paulson, and Rose 1978; Feder, Jewett, McGee, and Matheke 1981). However, feeding data from contiguous areas such as Cook Inlet, the Kodiak Archipelago, and the Kodiak shelf can be used to extrapolate data for NEGOA (Feder, Paul, Hoberg, and Jewett 1981; Rogers, Wangerin, and Rogers 1980; and Feder and Jewett 1981b). Gulf Embaymenls and Fjords The biological systems of these regions are influenced by the oceanographic features of the shelf waters, and particu- larlv bv the Alaska Coastal Current (Royer 1981, 1982, 1983; Rover et al. 1979). Although few biological investigations of these bodies of water are available, various reports, theses, and papers help to develop a preliminary understanding of these benthic environments. Infaunal and epifauna! data available for Yakutat Bay are included in: • Feder and Jewett (University of Alaska, unpubl. data on file at NODC) • Feder, Jewett, McGee, and Matheke (1981). Information on the bays and fjords of Prince William Sound, including Port Etches, Zaikof Bay, and Rocky Bay is presented by: • Feder and Hoberg (1981) • Hoberg (1986). Paul and Feder (1975), Hoskin (1977), and Feder and Paul (1977) contain information on: • Nelson Bay Port Wells Blackstone Bay Blue Fjord Derickson Bay McClure Bay Port Etches • Simpson Bay • Sheep Bay • Port Gravina • PortValdez • Columbia Bay • Unaquik Inlet Information on Port Valdez is included in: • Hood, Shiels, and Kelley (1973) • Colonell (1980) Table 12-2. The biomass distribution of trophic groups found on the shelf of the Gulf of Alaska (Semenov 1965). Trophic Group Western Region Northern- Region (NEGOA) Entire Eastern Shelf Region Zone Non-mobile filter feeders g/m2 111.87 13.13 3.2 50.84 % 62.15 20.4 13.8 48.37 Mobile filter feeders g/m2 26.06 4.11 2.5 12.57 % 14.48 6.4 10.8 11.96 Browsing detritus eaters g/m2 15.06 24.05 9.9 18.89 % 8.37 37.4 42.7 17.97 Non-selective detritus consumers g/m2 15.97 18.92 2.1 15.83 % 8.87 29.4 9.1 15.06 Remainder (predators, scavengers) g/m2 11.04 4.09 5.3 6.97 % 6.13 6.4 22.8 6.63 Total biomass g/m2 180.0 64.3 23.2 105.1 No. of stations 24 30 7 61 350 Biological Resources • Feder and Matheke (1980b) • Feder, Gosink, Naidu, and Shaw (1983) • Feder and Shaw (1986) • Feder and Jewett (in press). Information on Resurrection Bay is included in: • Heggie, Boisseau, and Burrell (1977) • Feder, Paul, and McDonald (1979). Aialik Bay is covered in material by Feder et al. (1979) and Carpenter (1983). Fjords are also reviewed by Pearson (1980) and Burrell (Ch. 7, this volume). There is an extensive data base on the epifaunal inverte- brates of lower Cook Inlet. Exploratory fishing was first undertaken there in 1958 when the Bureau of Commercial Fisheries conducted a demersal trawl survey that targeted shrimp and crab (USDI 1977; Ronholt et al. 1978). The status of the commercial shellfish fishery in the Inlet is updated annually by the Alaska Department of Fish and Game (ADF&G 1985b). The exploration and development of potentially rich sources of petroleum in the Inlet in the early 1970s required further assessment of its abiotic and biotic components. Ini- tial resource surveys made by ADF&G and the U.S. Depart- ment of Commerce (ADF&G 1976) were followed by investi- gations of the larval and/or the adult stages of commercially important shellfish (Hennick 1973; Feder 1977; Haynes 1977; Sundberg and Clausen 1977; Paul, Paul, Shoemaker, and Feder 1979; Paul and Paul 1980; and Feder, McCumby, and Paul 1980). Summaries of the food habits of adult crabs (Tan- ner, king, and Dungeness) and the food habits of pandalid shrimps in Cook Inlet are included in Crow (1977), Paul, Feder, and Jewett (1979), Feder and Paul (1980), Rice, McCumby, and Feder (1980), and Feder, Paul, Hoberg, and Table 12-3. The biomass distribution of trophic groups found on the upper continental slope of the Gulf of Alaska (Semenov 1965). Entire Western Northern Eastern Shelf Trophic Group Region Region Region Zone Non-mobile filter feeders g'm2 % 1.20 6.28 1.35 2.8 0.03 0.2 1.04 3.22 Mobile filter feeders g'm2 % 3.00 15.71 0.44 0.9 0.22 1.5 1.22 3.78 Browsing detritus eaters g/m2 % 9.51 49.79 13.66 28.2 4.18 28.9 10.43 32.29 Non-selective detritus consumers g/m2 % 2.33 12.20 20.97 43.2 2.31 16.0 11.27 34.89 Remainder (predators, scavengers) g/m2 % 3.06 16.02 12.08 24.9 7.73 53.2 8.34 25.82 Total biomass g/m2 No. of stations 19.1 8 48.5 22 14.5 5 32.3 25 Jewett (1981). Data on non-commercial, benthic inverte- brates were initially not as extensive as those available for commercial species in the Inlet, although some data are included in Rosenberg, Natarajan, and Hood (1969), USDI (1977), and Bakus, Orys, and Hendrick (1979). However, the shallow subtidal region received a great deal of attention ini- tially when it was identified as the region most likely to be impacted by petroleum-related activities (Lees 1976; Rose- nthal and Lees 1976; Driskell and Lees 1977; Lees 1978; Lees and Driskell 1981; and Dames and Moore 1981, 1984). An investigation of the biology of crangonid shrimps in deeper water was conducted by Rice (1980), and surveys of infauna and epifauna from various depths throughout lower Cook Inlet are reported in Dames and Moore (1978), Feder and Paul (1981), and Feder, Paul, Hoberg, and Jewett (1981). Western Shelf The infauna of the western Gulf is best known from Shev- tsov (1964a, b) and Semenov (1965). Additional data in Feder and Jewett (1981b; University of Alaska, unpubl. data) sup- port the findings of the earlier investigations. Most of the biological information on epibenthic invertebrates (mainly non-commercial species) is from trawl surveys conducted on the Kodiak shelf and some of its embayments (Feder and Jewett 1977; 1981b). Shevtsov (1964a, b) and Semenov (1965) present some data on sessile epifauna of rocky-gravel substrates. The stock status for various commercially important shellfish is presented annually in reports prepared by ADF&G (ADF&G 1985a). The estimated total biomass of the commercial invertebrates from this region for the years 1973 through 1976 was nearly 7.0 x 104 mt — higher than for any other region of the Gulf shelf (Ronholt et al. 1978). Data compilations for the renewable resources of the Kodiak shelf are included in Arctic Environmental Informa- tion Data Center (1974) and Science Applications, Inc. (1980) reports. Ronholt et al. (1978) present a review of the commer- cially important invertebrates and fishes of the Kodiak shelf. Both inshore and limited offshore surveys of the Kodiak region examined the distribution of the invertebrate benthos as well as collected data on the food of selected epi- faunal invertebrates. The species included were: • Tanner crab (Chionoecetes bairdi) • red king crab (Paralithodes camtschatica) • pink shrimp {Pandalns borealis) • sea star (Pycnopodia helianthoides). These surveys also covered fishes, including: • Pacific cod (Gadus macrocephalns) • walleye pollock (Theragra chalcogramma) • sculpins (Myoxocephalus spp. and Hemilepidotus jordani) • flathead sole (Hippoglossoides elassodon) • rock sole (Lepidopsetta bilineata) • arrowtooth flounder {Atheresthes stomias) • yellowfin sole {Limanda aspera) • butter sole (Isopsetta isolepis) • Atka mackerel (Pleurogrammus monopterygius) • sablefish (Anoplopoma fimbria) The Subtidal Benthos 351 (Feder and Jewett 1977, 1981b; Jewett and Powell 1979; Jewett and Feder 1982, 1983; and Rogers el ai 1980). Faunal Review by Region Northeast Gulf of Alaska Shelf General. Investigations of the shelf (<2()0 m) and its upper slope, troughs, and canyons (201-400 m) have been conducted primarily between Cape Cleare (148°W) and Cape Fairweather (138°W). This portion of the Gulf has a relatively wide shelf (up to 100 km) with several banks or grounds bisected by submarine canyons or troughs (Fig. 12-1). The boundaries of these physiographic features are loosely defined and are based upon bathymetry (Hitz and Rathjen 1965; Science Applications, Inc. 1980). All banks and grounds, with the exception of Tarr Bank, have depths greater than 100 m and less than 200 meters. All troughs and canyons, with the exception of Egg Island Trough, are deeper than 200 meters. The dominant shelf sediment is clayey silt that comes pri- marily from either the Copper River or from the Bering and the Malaspina Glaciers (Molnia and Carlson 1980; Hampton, Carlson, Lee, and Feely, Ch. 5, this volume). Once sediments enter the Gulf, they are generally transported to the west. High sedimentation rates throughout most of the shelf result in poorly consolidated sediments. Few sedi- ments accumulate on the relatively shallow Tarr Bank because of scouring by strong bottom currents and frequent winter storm waves. Sand predominates nearshore, especially near the Copper River and the Malaspina Glacier (Carlson, Molnia, Kittelson, and Hampson 1977). Infauna . Feder and Matheke (1980a) described over 400 invertebrate taxa from the shelf, representing eleven phyla. Fifteen taxa (primarily annelids and mollusks) occurred at 50% or more of the stations while 28 taxa (from eight phyla) represented 10% or more of the wet weight at one or more stations (Tables 12-4 and 12-5). Infaunal abun- dance on the shelf for the period 1974 to 197(5 (Feder and Matheke 1980a) ranged from 67 to 1,654 individuals/m2; the biomass ranged from 7 to 776 g/m2. The mean abundance/biomass values for the major Shelf groups (Fig. 12-2) determined by Feder and Matheke (1980a) are given in Table 12-6. The mean diversity and species richness among station groups were highest in the region of Tarr Bank and the shelf break (Table 12-6). Among the major station groups (Feder and Matheke 1980a), the per- centage of sessile organisms was relatively low inshore (32%), increased at the shelf break (44%), and was highest at Tarr Bank (53%). Hickman and Nesbitt (1980) describe three recurring mollusk associations in the northern Gulf: 1) a shallow- water Yoldia-Siliqua-Lyorisia sand association, 2) a shallow- to-intermediate depth Cyclocardia-borea.\ turrid mud association (with a typical phase developing in offshore muds and a Clinocardium-Nitidella nearshore mud phase associated with Yakutat and Icy Bays), and 3) a deep-water Cadulus thin-shelled protobranch mud association. They report an abrupt faunal break at 180 m, separating the typ- ical Cyclocardia-boreaX turrid mud association from the Cadulus thin-shelled protobranch mud association. Although the two mud associations have species in com- mon, many species drop out as the 180 m isobath is approached, and other species appear at or not far below it. 146 144 142 Figure 12-1. Shelf of the northeast Gulf of Alaska showing major physiographic features. 352 Biological Resources Shevtsov (1964a, b) found that the trophic zonation of infauna was well expressed in the Gulf, and noted that east of Kodiak Island the biomass of the shelf benthos decreased abruptly. This decrease was at the expense of suspension (fil- ter) feeders which reached their highest biomass values (77% of the total) in the western Gulf. The biomass con- sisted mainly of deposit (detritus) feeders in the northeast Table 12-4. Taxa occurring at 50% or more of the stations sampled with a van Veen grab in the northeast Gulf of Alaska (NEGOA), Port Valdez, lower Cook Inlet, and Aialik Bay (Feder, Mueller, Matheke, andjewett 1976; Feder 1979; Feder, Paul, Hoberg, andjewett 1981; and Carpenter 1983). Port Cook Aialik Taxa NEGOA Valdez Inlet Bay Annelida Eleone longa Gyptis brevipalpa Nephtys punctata Nephtys ciliata Nephtys cornuta Nephtys longasetosa Onuphis irridescens Goniada annulata Glycera capitata Glycinde picta Lumbrineris spp. Aricidea lopezi Ninoe gemma Haploscoloplos elongatus Prionospio malmgreni Magelona sp. Polydora sp. Tharyx sp. Slernaspis scutata Heteromastus filiformis Praxillella gracilis Maldane glebifex Scalibregma inflatum Myriochele heeri Myriochele acculata Amphicteis gunneri Lysippe labiata Artacama conifera Terebellides stroemi Disoma multisetosum Melinna crislata Ampharetidae Mollusca Chaetoderma robusta Nucula tenuis Nuculana fossa Yoldia sp. Axinopsida spp. Macoma calcarea Turridae Solar iella sp. Thyasira flexuosa Odontogena borealis Psephidia lordi Cylichna alba Dentalium dalli Arthropoda Eudurella emarginata Ampelisca macrocephala Byblis gaimardi Echinodermata Ctenodiscus crispatus Ophiura sarsi Table 12-5. Taxa representing 10% of the wet weight at one or more stations sampled with a van Veen grab in the northeast Gulf of Alaska (NEGOA), Port Valdez, lower Cook Inlet, and Aialik Bay (Feder, Mueller, Matheke, andjewett 1976; Feder 1979; Feder, Paul, Hoberg, andjewett 1981; and Carpenter 1983). Taxa Port Cook Aialik NEGOA Vai.de/ Inlet Bay Porifera Cnidaria Anemones Ptilosarcus gurneyi Alcyonacea Annelida Ancistrosyllis sp. Nephtys spp. Nephtys punctata Nepthys ciliata Nephtys longasetosa Goniada annulata Travisia brevis Lumbrineris spp. Flabelligera masligophora Sternaspis scutata Heteromastus filiformis Praxillella gracilis Maldane glebifex Myriochele heeri Myriochele occulata Terebellides stroemi Melinna cristatus A mph icteis gunneri Mollusca Nuculana fossa Nuculana sp. Yoldia thraciaeformis Yoldia scissurata Yoldia secunda Yoldia montereyensis Axinopsida serricata Clinocardium ciliatum Clinocardium sp. Astarte alaskensis Astarte polaris Astarte esquimalti Glycymeris subobsoleta Macoma brota Macoma calcarea Macoma moesta alaskana Tellina nuculoides Natica clausa Polinices pallida Arthropoda Scalpellum sp. Balanus nubilis Balanus balanoides Balanus crenalus Sipuncula Golfi ngia m a rgart tacea Brachiopoda Laqueus californianus Terebratalia transversa Echinodermata Ech i na rack u i us pa rma Slrongylocentrotus sp. Brisaster touinsendi Ctenodiscus crispatus Unioplus macraspis Ophiocantha sp. Oph iopholis aculeata Ophiura sarsi A lolpadia in termedia The Subtidal Benthos 353 iiu hinbi ook Inn ,in< c gi on]) I I an H.uik group I I I nshiii (' g] oup IS] Shelf break group VZA Group I • ( .r.ih M.il inn 60 59 Figure 12-2. Major station groups formed by cluster analysis of 1974 to 1976 /^-transformed infaunal data from the shelf of the north- east Gulf of Alaska. (Modified from Feder and Matheke 1980a.) At stations where samples were not always classified in the same station groups, two station groups overlap. Gulf (67% of the total biomass) while suspension (filter) feeders represented only 27% of the total (Semenov 1965) (Table 12-2). Deposit feeders dominated the abundance and biomass in all regions on the northeastern shelf (except Tarr Bank) that were investigated by Feder and Matheke (1980a) (Tables 12-7 and 12-8). Non-selective deposit feeders were most common in the canyons (such as Yakutat and Alsek), and on the continental slope. East of Yakutat Bay to the Queen Charlotte Islands, browsing detritus feeders (browsers and selective deposit feeders) were common. Suspension feeders were not common over most of the NEGOA shelf. However, the numbers and the biomass of species such as the sea pen (Ptibsarcus gurneyi) increased on both Tarr and Yakutat Banks, as well as off the Copper River (Station Group 6) (Figs. 12-1 and 12-2). Table 12-6. Mean abundance, biomass, and diversity of the fauna of station groups shown in Figure 12-2 and Station gToups 5, 6, 42 (Tables 12-7, 12-8) of NEGOA delineated in a cluster analysis of combined grab data (July 1974-March 1976). Biomass values are in formalin wet weight (based on Feder and Matheke 1980a). Station Abundance Biomass Shannon Species Group (No./m2) (g/m2) Diversity Richness Inshore Group 424 152 3.1 6.8 Shelf Break Group 625 46 3.6 11.1 Tarr Bank Group 1,040 302 3.8 15.0 Hinchinbrook Entrance Group 947 417 2.9 8.0 Station Group 4 709 68 3.2 9.0 Station Group 6 280 83 2.7 6.0 Station Group 5 258 39 3.0 6.5 Station Group 42 605 77 3.2 9.3 Infaunal carbon production estimates (H.M. Feder, Uni- versity of Alaska, unpubl. data) were calculated by using the carbon-conversion values from Stoker (1978) and the P/B values from Stoker (1978), Robertson (1979), and Warwick (1980). Estimates for NEGOA station groups (Feder and Matheke 1980a) are: • Hinchinbrook Entrance Group: 4.6 g C/m2y • Inshore Group: 2.2 g C/m2y • Tarr Bank Group: 9.3 g C/m2y • Shelf Break Group: 1.9 g C/m2y. The mean infaunal production for the NEGOA shelf is esti- mated as 4.5 g C/m2y (Table 12-9). Assuming that the micro- floral/meiofaunal production rate is twice that of the macro- fauna (Parsons, Ch. 18, this volume), and further assuming that epifaunal production on the shelf is 0.12 gC/m2y (H.M. Feder, University of Alaska, unpubl. data), then the total benthic production for the NEGOA shelf is estimated at 13.7 g C/m2y. No discrete infaunal communities, such as those described by Petersen andjensen (1911) and Thorson (1957), were identified in NEGOA by Feder and Matheke (1980a). In fact, the data suggest that species distribute themselves inde- pendentlv along environmental gradients (Whittaker 1970). It took a minimum of 28 species groups in order to describe the spatial distribution patterns found during a single month period, and it took 53 species groups to describe both the spatial and the temporal distribution patterns over a 21-month period. Moreover, there was variation in the species abundance patterns of species within these groups. As the amount of sand and gravel in the sediment increased, faunal abundance changed, and there was an increase in both diversity and species richness. This indi- cates that sediment size is a major factor in controlling spe- 354 Biolocical Resources Table 12-7. Dominant taxa (number/m'-') in the major shelf groups of NEGOA determined by cluster analysis (Feder and Matheke 1980a). All samples collected by van Veen grab (see Fig. 12-2). Feeding Abundance Feeding Abundance Taxa Class3 (No./m2) Taxa Class (No./m2) Inshore Group Group 42 Xucula tenuis DF 37 Xucula tenuis DF 73 Myriochele heeri DF 22 Psephidia lordi SF 56 Psephidia lordi SF 20 Myriochele heeri DF 30 Sternaspis scutata DF 20 Spiophanes cirrata DF 22 Axinopsida serricata SF 17 Spio filicornis DF 18 Lumbrineris similabris DF/P 17 Lumbrineris zonata B 19 Xuculana fossa DF 15 Maldanae sarsi DF 18 Ophiura sarsi DF/B/P 13 Ophiura sarsi DF/B/P 12 Hinchinbrook Entrance Group Tarr Bank Group Ophiura sarsi DF/B 198 Ectoprocta SF 192 Sternaspis scutata DF 125 Peisidice aspera S 56 Eudorellopsis Integra DF 52 Crenella decussata SF 42 Eudorella emarginata DF 41 Terebratulina unguicula SF 31 Spiophanes cirrata DF 38 Golfingia margaritacea DF 20 Myriochele heeri DF 33 Laqueus californianus SF 20 Group 4 Shelf Break Group Ophiura sarsi DF/B/P 114 Golfingia margaritacea DF 55 Psephidia lordi SF 112 Ectoprocta SF 37 Crenella decussata SF 55 Ophiura sarsi DF/B/P 25 Cyclocardia ventrkosa SF 29 Amphipoda S 17 Xucula tenuis DF 25 Axinopsida serricata SF 17 Cyclocardia crebricostata SF 25 Odontogena borealis SF/DF 16 ' DF = deposit feeder; SF = suspension feeder; B = browser; P = predator; S = scavenger. Table 12-8. Dominant taxa (wet weight in g/m2) in the shelf groups of NEGOA determined by cluster analysis (Feder and Matheke 1980a). All samples collected by van Veen grab (see Fig. 12-2). Feeding Feeding Taxa Class3 BlOMASS Taxa Class BlOMASS Inner Shelf Group Group 42 Molpadia intermedia DF 53 Ophiura sarsi DF/B/P 21 Ctenodiscus crispatus DF 15 Ophiopholis aculeata SF/DF 10 Brisaster townsendi DF 11 Ctenodiscus crispatus DF 5 Ophiura sarsi DF/B/P 5 Myriochele heeri DF 2 Hinchinbrook Entrance Group Tarr Bank Group Molpadia intermedia DF 270 Anthozoa P 9 Ophiura sarsi DF/B/P 31 Unidentified brachiopod SF 5 Macoma brota DF 7 Virgulariidae P 4 Sternaspis scutata DF 4 Ophiura sarsi DF/B/S 4 Group 4 Porifera SF 4 Ophiura sarsi DF/B/P 18 Molpadia intermedia DF 3 Golfingia margaritacea DF 3 Shelf Break Group Porifera SF 3 Golfingia margaritacea DF 5 Anthozoa P 21 Brisaster townsendi DF 5 Station Group 6 Ophiura sarsi DF/B/S 4 Ptilosarcus gurneyi SF/P 73 Group 5 Mitrella gouldi U 1 Brisaster townsendi DF 16 Pinnixa schmitti U 1 Unioplus macraspis DF 3 Xuculana fossa DF 1 Sternaspis scutata DF 1 d DF = deposit feeder; SF = suspension feeder; B = browser; P = = predator; S = ' scavenger; U = unknown. The Subtidal Benthos 355 Table 12-9. Mean biomass and production estimates of benthos from selected stations in the four major station groups of NEGOA, based on a cluster analysis of combined data (1974-1976) (Feder and Matheke 1980a). Differences in mean biomass values from Table 12-6 reflect the bias of specific stations within each station group selected for production estimations. Station GROUP Dominant Feeding Type3 Biomass Carbon1* PRODUCTIONb (g/m*) (gC/m-') (gC/m2y) 164 3.6 2.2 48 1.1 1.9 245 7.4 9.3 343 7.1 4.6 200 4.8 4.5 Carbon Required/Yeah (10% < ()\\ F KSI()\ efficiency) 1. Macrofauna1 Inshore Group Shelf Break Group Tarr Bank Hinchinbrook Entrance x of selected stations 2. Microflora and meiofauna (assuming production twice that of macrofauna; Schwinghammer 1981) 3. Mobile Epifauna'1 Mean value for shelf (Feder and Jewett, unpubl. data). A P/B value of 2.0 was applied DF Mixed SF/DF SF Mixed SF/DF 2.1 0.12 9.0 0.24 22 19 93 46 45 90 2.4 Total (macrofauna + epifauna + meiofauna) 13.7 92 • DF = deposit feeder; SF = suspension feeder. h Calculations based on biomass data of Feder and Matheke (1980a) and literature values for carbon and P/B values (Stoker 1978; Robertson 1979; and Warwick 1980). 1 All organisms collected by van Veen grab. d All organisms collected by trawl cies distribution. However, variations in the distribution patterns for individual species (especially within the species groups that characterize silt-clay environments) indicate that environmental conditions other than grain size and deposition rate affect their distribution. This is also sug- gested for the distribution of species within the recurrent mollusk associations identified by Hickman and Nesbitt (1980). Thus, it appears that by delineating station groups in NEGOA, we identified the largest discontinuities in an oth- erwise near continuum of species distributions (Stephenson 1973; Feder and Matheke 1980a). Epifauna. Surveys in the northeastern Gulf during 1975 and 1979 yielded ~ 180 epifaunal species representing ten phyla (H.M. Feder and S.C. Jewett, University of Alaska, unpubl. OCSEAP data on file at NODC; Feder, Jewett, McGee, and Matheke 1981). Mollusks, arthropods, and echi- noderms dominated both the species representation and the biomass. For this region, a general trend of decreasing epifaunal biomass was apparent from west to east at all depths (Table 12-10). Based upon the 1975 survey, epifaunal biomass from stations between 148° and 144°30'W and 144°30' and 140°W were 2.4 g/m2 and 1.2 g/m2, respectively (Table 12-10). Biomass values from the 1979 sampling were 2.6 g/m2 between 144°30' and 140°W and 1.1 g/m2 between 140° and 137°30'West. The high value of 2.6 g/m2 between 144°30' and 140°W in 1979 was attributed to an unusually large catch of Dungeness crab {Cancer magister) outside of Icy Bay. The highest biomass values occurred west of Kavak Island, specifically in the vicinities of Hinchinbrook Entrance off Prince William Sound and immediately west of Kavak Island. The substratum at these locations reflected a depositional environment consisting mainly of silt and clay (Carlson el al. 1977). These regions were dominated at all depths by the predator/scavenger Tanner crab, Chionoecetes ba/rdi (Tables 12-10 through 12-12). Five stations outside Hinchinbrook Entrance yielded —1.4 mt of mainly sub- adult and adult crabs in five hours of trawling. Crab biomass at these five stations collectively was 4.0 g/m2, representing 86% of the total epifaunal biomass. West of Kayak Island, in the vicinity of Kayak Trough and Middle Bank, Tanner crab accounted for 86% of the epi- faunal biomass at eight selected stations (H.M. Feder and S.C. Jewett, University of Alaska, unpubl. data on file at NODC). Tanner crab biomass for these eight stations collec- tively was 4.1 g/m2, with the highest value (6.0 g/m2) within the trough. The crab composition in this vicinity varied from station to station with no apparent pattern of size, sex, or maturity emerging for a particular depth or area. Other benthic organisms that exhibited high standing stocks near the west side of Kayak Island were the pink shrimp, Pandalus borealis, and the mud star, Ctenodiscus crispatus (Tables 12-10 and 12-11). Long-term trends in the relative magnitude of Tanner crab within NEGOA can be shown by comparing the crab catch per unit of effort (CPUE in kg/h) for the 1961-1962 sur- veys by the IPHC and the 1973 to 1976 surveys by the NMFS (Ronholt el al. 1978). Although the population in some regions decreased while in others it increased, there was no marked change in the CPUE for Tanner crab within the Gulf of Alaska as a whole during the period from 1961 though 1976. The shelf region south of Prince William Sound (148°- 144°30'W) was the only region that showed a marked increase in the CPUE for Tanner crab during this period. In 356 Biological Resources Table 12-10. Dominant fauna taken by trawl in NEGOA in 1975 and 1979. Total Area3 Total Depth Stations Sampled Invertebrate (in) Sampled (km*) Biomass (g/m2) Dominant Taxa Percent of Area Biomass S100 101-200 16 51 1.032 3.529 148°-144°30'W 1975b 3.6 1.9 Chionoecetes bairdi Pandalus borealis Halocynthia helgendorfi igaboja Chionoecetes bairdi Ctenodiscus crispatus Pandalus borealis 48.3 13.1 6.8 74.5 6.9 4.6 201-400 All depths 72 0.366 4.927 4.0 2.4 Chionoecetes bairdi Ctenodiscus crispatus Chionoecetes bairdi Pandalus borealis Ctenodiscus crispatus 82.5 9.4 67.4 6.7 5.3 ^100 101-200 201-400 0.102 0.244 0.183 144°30'-140°W1979C 6.9 2.1 0.9 Cancer magister Pecten caurinus Pycnopodia helianthoides Cucumaridae Strongylocentrotus droebathiensis Porifera Alloc entr otus fragilis Cucumaridae Porifera Rossia pacifica Berryteuthis magister 50.0 37.2 7.4 3.8 44.3 26.4 8.9 4.8 79.1 5.5 4.8 All depths 16 0.529 2.6 Cancer magister Porifera Pecten caurinus Strongylocentrotus droebathiensis Cucumaridae Alloc entr otus fragilis 25.3 19.3 18.8 16.6 3.8 3.4 a Trawl opening width = 12.2 m. b 1975 trawl survey (H.M. Feder and S.C. Jewett, University of Alaska, unpubl. OCSEAP data on file with NODC). c 1979 trawl survey (Feder, Jewett, McGee, and Matheke 1981). this region, increases were seen at all depth zones — on the inner shelf (0-100 m), on the outer shelf (101-200 m), and on the upper slope (201-400 m). Nearly 40% of the total esti- mated biomass of Tanner crab from the Gulf of Alaska shelf came from this region south of Prince William Sound. In 1976, two new fishing districts were established by ADF&G for Tanner crab outside Prince William Sound. These districts were between Cape Fairfield (western entrance of the Sound) and Cape Suckling (west of Kayak Island). A north-south line from Hinchinbrook Entrance separated the two districts. The combined Tanner crab harvests from both districts increased from 351 mt in 1976-1977 to 2,509 mt in 1979-1980, when it peaked. Since that peak year, the harvest from both districts continued to fall to 439.5 mt in 1982-1983 (ADF&G 1985c). The 1983-1984 season brought a closure to the western district, as well as to the Sound. Although the eastern district remained open in 1984, fishermen accepted the gloomy forecast and did not fish. Management biologists are unable to determine which specific factors are responsible for the population decline in this once-productive Tanner crab region although they suspect unfavorable environmental conditions (ADF&G 1985c). In addition to the Tanner crab, the mud star was one of the most ubiquitous species on the shelf and was a dominant contributor to the biomass. It occurred mostly at depths greater than 100 m — in canyons and troughs as well as on banks and grounds. This non-selective deposit-feeding asteroid feeds on the organic material associated with the mud it ingests. It either dominated, or was second in total biomass in four canyons/troughs: Kayak, Icy, Yakutat, and Alsek. It was also very abundant at shallower depths in loca- Tuf Subtidai Benthos 357 Total AREAa Total Depth Stations Sampled Invertebrate (m) Sampled (km-) Biomass (g/m2) Dominant Taxa 1*1 1<( I \ I OF Area ^ 100 101-200 201-400 All depths 17 29 12 58 2.017 0.826 3.961 144°30'-140°W 1975'' 1.2 0.7 2.5 1.2 Chionoecetes bairdi Pycnopodia h el Kit it h 0 ides Pecteri caurinus Ctenodiscus crispatus Chionoecetes bairdi Cucumaridae Lopholithodes foraminatus Pyawpodia helianthoides Brisaster townsendi Ctenodiscus crispatus Allocentrotus fragilis Brisaster townsendi Chionoecetes bairdi Pycnopodia helianthoides Pecten caurinus Ctenodiscus crispatus 39.1 24.0 19.4 14.7 8.4 8.0 8.0 6.0 71.9 2.8 1.9 29.8 13.8 8.6 5.9 5.8 ^ 100 101-200 201-400 All depths 10 12 26 0.361 0 451 0.122 0.905 140°-137°30'W 1979c 1.6 1.1 0.3 1.1 Metridium senile Pecten caurinus Pycnopodia helianthoides Chionoecetes bairdi Strongylocentrotus droebachiensis Allocentrotus fragilis Fusitriton oregonensis Brisaster townsendi Fusitriton oregonensis Ctenodiscus crispatus Allocentrotus fragilis Metridium senile Pecten caurinus Chionoecetes bairdi Strongylocentrotus droebachiensis Allocentrotus fragilis Fusitriton oregonensis 47.7 31.3 7.9 34.5 32.8 5.8 3.1 39.4 30.4 8.1 4.4 25.4 17.6 15.3 14.0 2.7 2.5 tions such as Cape Cleare Ground, Egg Island Trough, Mid- dle Bank, and Icy Bank (Tables 12-10 and 12-12). Quantities of this small (<5 cm diameter) sea star are presumed to be underestimated when sampled by trawls. Although most of Tarr Bank was untrawlable, seven sta- tions were sampled. Two stations along the northwest por- tion of the Bank exhibited extremely diverse macrofauna with 58 epifaunal taxa being identified in the 65- to 70-m depth range. Nearly two-thirds of the species were scav- engers/predators; the remaining one-third were suspension feeders. The dominant taxa were Tanner crab, the ascidian Halocynthia hilgendorfi igaboja, and the green sea urchin, Strongylocentrotm droebachiensis. Halocynthia was attached to a substrate of small ( ~ 4 cm diameter), rounded rocks. Nearly 245 kg (4.5 g/m2) of this suspension-feeding organism were taken in one hour. In shallow subtidai regions Strongylo- centrotus is characterized as a grazer; however, at greater depths it presumably feeds by browsing and scavenging. The Pacific halibut, Hippoglossus stenolepis, was the only abun- dant fish at the stations. Halibut averaged 18.5 kg per indi- vidual at these two stations — with 1,399 kg taken per hour. Stations on the eastern and southern portions of Tarr Bank were dominated by Tanner crab, pink shrimp, and the mud star. The basket star Gorgonocephulus carp, was one of the spe- cies which dominated the epifaunal biomass at three banks/ grounds. This species accounted for 1.5, 2.0, and 5.6% of the respective biomasses at Cape Cleare Ground, Middle Bank, and Icy Bank (Table 12-11). It resides in areas of rapid cur- rents and relatively solid substrates, and feeds using a com- bination of predation, suspension feeding, and browsing (Patent 1970) (Table 12-12). 358 Biological Resources Table 12-11. Dominant fauna taken by trawl from the major physiographic regions of NEGOA in 1975a and 19791'. Area Total. Area' Area iepth Stations Sampled Biomass (111) Sampled (km2) (g/m2) Dominant Taxa Percent OF Area Biomass Cape Cleare Ground (1975) Egg Island Trough (1975) Tarr Bank (1975) Middle Bank (1975) Kavak Trough (1975) Kayak Bank (1975) Bering Canyon (1975) lev Bank (1975) Icy Canyon (1975) Yakutat Canyon (1975) Outer Yakutat Canyon (1979) Yakutat Bank (1975) Yakutat Bank (1979) Alsek Canyon (1979) 101-197 101-132 65-96 102-188 202-222 119-191 298-306 113-182 10 17 20 222-226 209-312 284-351 130-150 110-156 209-263 15 1.490 0.705 0.400 1.127 0.142 0.506 0.167 .360 0.072 0.623 0.163 0.606 0.542 0.122 1.4 2.8 4.7 2.3 5.8 0.6 0.4 0.6 0.2 2.8 0.2 1.7 1.4 0.3 Chionoecetes bairdi Ctenodiscus crispatus Gorgonocephalus caryi Pandalus borealis Fusitriton oregonensis Chionoecetes bairdi Ctenodiscus crispatus Pandalus borealis Chionoecetes bairdi Halocynthia helgendorfi igaboja Strongylocentrotus droebachiensis Pandalus borealis Ctenodiscus crispatus Chionoecetes bairdi Ctenodiscus crispatus Pandalus borealis Gorgonocephalus caryi Ophiura sarsi Chionoecetes bairdi Ctenodiscus crispatus Neptunea lyrata Chionoecetes bairdi Pecten caurinus Lopholithodes foraminatus Pandalus borealis Ctenodiscus crispatus Ophiura sarsi Allocentrotus fragilis Brisaster townsendi Lithodes aequispina Actiniidae Dipsacaster borealis Ctenodiscus crispatus Pycnopodia helianthodes Chionoecetes bairdi Gorgonocephalus caryi Ophiura sarsi Fusitriton oregonensis Lopholithodes foraminatus Ctenodiscus crispatus Mediasler aequilis Pandalopsis dispar Brisaster townsendi Ctenodiscus crispatus Allocentrotus fragilis Rossia pacifica Berryteuthis magister Dipsacaster borealis Allocentrotus fragilis Cucumaridae Lopholithodes foraminatus Allocentrotus fragilis Chionoecetes bairdi Strongylocentrotus droebachiensis Fusitriton oregonensis Ctenodiscus crispatus Strongylocentrotus droebach iensis Chionoecetes bairdi Lopholithodes foraminatus Allocentrotus fragilis Fusitriton oregonensis Brisaster townsendi Fusitriton oregonensis Ctenodiscus crispatus Pandalopsis dispar Allocentrotus fragilis 68.5 8.7 1.5 1.3 1.0 87.8 4.1 3.9 41.6 13.6 10.5 7.5 1.1 75.7 7.7 7.3 2.0 0.7 86.2 9.2 1.5 21.9 21.4 10.5 10.1 6.9 3.7 31.2 15.6 12.5 8.6 1.3 26.3 11.1 9.5 5.6 4.2 2.0 1.7 56.3 11.2 8.4 83.9 2.8 1.2 32.2 28.3 9.3 4.3 19.8 12.7 4.0 3.2 1.7 1.6 1.0 49.6 22.1 7.4 7.4 2.9 39.5 8.8 8.1 3.4 2.9 The Subtidal Benthos 359 Aki \ Total Area1 Area Depth Stai ions Sampled BlOMASS mi) Sampled (km2) (g/m-) 1)<>\II\ \N I 1 \\ V I'l K< I \ I 01 Aki \ BlOM ISS Fair weather Ground (1979) 113-166 0.095 0.3 Allocnitrntu.s/rrigilis Lopholithodes foramina/us Fusitriton oregonensis Rossia pat ifit a 45.0 16.2 7.3 2.5 1 1975 trawl survey (H.M. Federand S.C. [ewett, University of Alaska, unpubl. OCSEAP data on file at NOIM > b 1979 trawl survey (Feder.Jewett, McGee, and Matheke 1981). ■ trawl opening width = 12.2 m. The brittle star Ophiura sarsi is an organism not ade- quately sampled with large trawls. However, when con- centrations are high, it is quite conspicuous, and trawl sam- pling allows a glimpse of their distribution and relative abundance. The area where they made up the greatest biomass was on Middle Bank, —15 km west of the southern end of Kayak Island. This area yielded 11.3 kg per hour or 0.2 g/m2 of this brittle star. This equates to a catch rate of ~ 2,000 individuals per hour. Ophiura is a deposit feeder/ scavenger/predator (Kyte 1969), but may occasionally engulf sediment and detritus. It is preyed upon by a number of bottom-feeding species, among which the sunflower sea star, Pycnopodia helianthoides, and the flathead sole, Hippo- glossoidfs elassodon, are predominant. The broad region between Kayak Island and Lituya Bay generally displayed a low epifaunal biomass (Table 12-11). During 1975 and 1979, 58 and 42 stations, respectively, were sampled east of 144°30'West. Of these stations, only 14 yielded values exceeding 3 g/m2. Three of these stations were in shallow waters (28-73 m) between Cape Yakataga and Yakutat Bay, six were within (and at the mouth of) Yakutat Canyon, three were on Yakutat Bank, and two were at shallow depths (62-64 m) nearshore between Dry and Lituya Bays. Weathervane scallops, Pecteri caurinus, Tanner and Dun- geness crabs, and sunflower sea stars were the dominant spe- cies at stations between Cape Yakataga and Yakutat Bay. A dense bed of scallops was found seaward of Icy Bay and landward of Icy Canyon. The scallop concentration here was 11.6 g/m2 for a catch rate of nearly 1,100 individuals in a 30-minute tow. Other, less impressive scallop concentra- tions were noted off Cape Yakataga at 68 m, 10 km southeast of Dry Bay at 64 m, and 15 km south of Kayak Island at 130 meters. Many large scallops in the Cape Yakataga/Yakutat Bay region were infected by the spionid polychaetes Pygospio ele- gans and Polydora ciliata. These polychaetes had burrowed into the upper valves, weakening them to the point where the valves were easily broken by trawling. Scallops in the Yakutat Bay vicinity were once the target of a major fish- ery; however, recent landings have been low. During 1984, only 33.6 mt were harvested in the Yakutat region (ADF&G I985d). Dungeness crab dominated in terms of both density and biomass at the mouth of Icy Bay in November 1979. At this location (28 m) 833 crabs were obtained during a 30-minute tow. These crabs were mostly males weighing —0.4 kg each. Waters on either side of Icy Bay have been the most impor- tant fishing areas for Dungeness crab in the Yakutat Bay area fishery. The value of this species to the fishermen in the Yakutat Bay fishery in 1984-1985 was about $1 million for 346 mt (ADF&G 1985d). As a predator/scavenger, Dungeness crab takes an array of benthic prey, as has been demon- strated in Cook Inlet (Feder and Paul 1980). The sunflower sea star is one of the largest sea stars in the Gulf of Alaska, often attaining weights to 0.5 kilograms. This species occurred mostly at shallower depths (< 100 m), between Kayak Island and Dry Bay, although the depths between 113 and 182 m in Icy Bank were also important hab- itats (Tables 12-10 and 12-11). As a predator/scavenger, this sea star takes a variety of benthic prey (Paul and Feder 1975), but prefers clams, snails, brittle stars, and mud stars. Nearly 75% of the stations where Pycnopodia was found also con- tained Ophiura sarsi and/or the mud star. Other foods of lesser importance consumed by the sunflower sea star are the gastropods Coins halli, Mitrella gouldi, Solariella obscura, Oenopota sp., and Natica clausa, and the bivalves Serripes groenlandkus and Clinocardium ciliatum. Stations examined on Yakutat Bank in 1979 were domi- nated by Tanner crab and the green sea urchin. The pooled concentration of sea urchins at two of the three high- biomass Yakutat Bank stations was 1,428 individuals/km, or 5.6 g/m2. Stations between Dry Bay and Lituya Bay were domi- nated by the anemone Metridium senile, as well as by scallops. Organic materials suspended in the water column in this turbulent shallow region are presumably the primary source of food for the suspension-feeding Metridium. With the exception of Kayak Trough and Yakutat Can- yon, epifaunal biomass at depths exceeding 200 m was con- siderably less than on adjacent banks and grounds (Table 12-11). In most cases, deposit feeders dominated these deep regions. However, stations in the Bering Canyon were domi- nated by the sea urchin Allocentrotus jragilis, which presum- ably feeds by a combination of browsing and scavenging. The greatest density of this species was only 37 individuals/ km or 200 for each hour of trawling. Trawl samples in Yakutat and Alsek Canyons, and to a lesser extent in Bering Canyon, were dominated by the heart urchin Brisaster toumsendi. This species selects organic 360 Biological Resources Table 12-12. Feeding methods of the biomass-dominant epifauna from NEGOA (1) and the Kodiak Shelf (2) (Barnes 1980; Feder andjewett 1981a, b; Hyman 1955; Kozloff 1973; Kyte 1969; Morris, Abbott, and Haderlie 1980; Patent 1970; and Pearce and Thorson 1967). Taxa Common Name Feeding Class Area of Dominance Hydrozoa Porifera Actiniidae Metridium senile Ptilosamts gurneyi Stylatula gracile Modiolus modiolus Pododesmus macroschima Pec ten caurinus Septunea lyrata Fusitriton oregonensis Octopodidae Rossia pacifica Berryteuthis magister Pandalus borealis Pandalopsis dispar Cancer magister Chionoecetes bairdi Lithodes aequispina Lopholitlwdes foraminatus Ophiura sarsi Gorgonocephalus caryi Ctenodiscus crispatas Pycnopodia heiianthoides Medi aster aequilis Dipsacaster borealis Echinarachnius parma Strongylocentrotus droebachiensis Allocentrotus fragilis Brisaster townsendi Cucumaridae Halocynthia helgendorfi igaboja hydroid sessile SF sponge sessile SF anemone P/SF anemone P/SF sea pen P/SF sea pen SF mussel SF jingle SF weathervane scallop mobile SF snail S/P snail - Oregon Triton P/S octopus P/S squid P/S squid P/S pink shrimp P/S sidestripe shrimp P/S Dungeness crab P/S Tanner (snow) crab P/S Golden (brown) King crab P/S box crab P/S brittle star P/B/DF basket star P/SF/B mud star non-selective DF sunflower seastar P/S vermillion star P sea star P? sand dollar DF/SF green sea urchin B/S sea urchin B/S? heart urchin selective DF sea cucumber SF tunicate SF 2 1 1,2 1.2 2 2 2 2 1,2 1,2 1,2 2 1 1 1,2 1 1 1,2 1 1 1 1,2 1 1 1 1,2 2 1 1 1 1,2 1,2 a SF = suspension feeder; DF = deposit feeder; P = predator; S = scavenger; B = browser material deposited either on or within the sediment in which it burrows. Because of its burrowing habit, sampling via trawl presumably underestimates their relative abun- dance. Nevertheless, they still accounted for 84, 40, and 16% of the biomass at stations in Yakutat, Alsek, and Bering Can- yons, respectively (Table 12-8). Values as high as 7.5 g/m2 or 12,340 individuals/h were obtained in Yakutat Canyon. Extensive bottom trawling in NEGOA during 1961 and 1962 revealed that Brisaster accounted for 50% of the total inver- tebrate catch by weight and mainly occurred in Yakutat, Alsek, and Bering Canyons (Hitz and Rathjen 1965). Trawls taken from the outer Yakutat Canyon region con- tained the squids Rossia pacifica and Berryteuthis magister, two cephalopod species that are closely associated with the benthic substrate. Embayments of the Northeast Gulf of Alaska Yakutat Bay. The fine glacial sediments of Yakutat Bay (Fig. 12-1) were dominated by deposit-feeding polychaetes and bivalve mollusks, infaunal organisms characteristic of similar substrata elsewhere in the Gulf (Feder, Jewett, McGee, and Matheke 1981). Suspension-feeding species, such as cockles, scallops, and brachiopods were found in low numbers on the gravel-rock admixture in the mid- and outer Bay. The fact that suspension feeders were found here suggests the presence of strong bottom currents in the outer Bay. The area at the inner end of Yakutat Bay (mouth of Dis- enchantment Bay) was notable for the low abundance (32 individuals/m2) and biomass (1 g/m-) of its infauna. For sta- tions in mid-Yakutat Bay, there was both an increased abun- dance (x = 390 individuals/m-) and an increased biomass (x = 62 g/m2). The highest infaunal values were recorded at the mouth of Yakutat Bay with a mean abundance of 520 individuals/m2 and a biomass of 234 g/m2. Arthropods, echinoderms, and mollusks dominated the epifaunal species in terms of both abundance and biomass (H.M. Feder and S.C. Jewett, University of Alaska, unpubl. OCSEAP data on file at NODC). Arthropods contributed 13 species and made up 68.6% of the total biomass, echi- noderms contributed seven species and constituted 16% of the biomass, while mollusks accounted for two species and 14.8% of the biomass. The biomass for all epifaunal species was 1.2 g/m2. The dominant arthropod was the Dungeness crab, which contributed 88.1% of the arthropod biomass and 60.4% of the invertebrate biomass. The sunflower sea star and the weathervane scallop were the dominant echi- noderm and mollusk species, respectively. I he buBTiDAi Benthos 361 Prince William Sound. Port Valdez and Valdez Arm. Feder, Mueller, Dick, and Hawkins (1973) and Feder and Matheke (1980b) described over 200 invertebrate taxa representing thirteen phyla from grab samples they took in Port Valdez (a turbid outwash fjord; the location of the marine terminal for the Trans- Alaska oil pipeline) and Valdez arm (Fig. 12-3). Poly- chaetous annelids were both dominant and widely dis- tributed throughout the Port; mollusks were next in impor- tance. Echinoderms (primarily ophiuroids) were the third most common group of organisms present. All other groups combined represented a minor component of the fauna. The abundance of infauna in Port Valdez ranged between 13 and 1,860 individuals/m-, and the biomass (formalin wet weight) ranged from between 1 and 490 g/m2. Multivariate analysis of grab data in the Port separated sampling stations in the deep basin into two large groups — eastern and western — with a dividing line running between Gold Creek and a point to the east of Sawmill Creek (Feder and Matheke 1980b; Feder et al. 1983) (Fig. 12-4). Discrete communities such as those described by Petersen and Jensen (1911) and Thorson (1957) for the Baltic Sea were not observed in Port Valdez (Feder and Matheke 1980b). Trawl surveys of the deep basin of Port Valdez made between 1972 and 1982 collected representatives of eight invertebrate phyla (Feder et al. 1983). In general, crusta- ceans— primarily the shrimps Pandalus borealis, I'andalopsis dispar, and Crangon communis — dominated the bottom of both the eastern and the western stations. Juvenile Tannei crab, Chionoecetes bairdi, were sporadically abundant in Port Valdez, but adult crab were never common. The mud star, Ctenodiscus CrispatUS, was usually abundant in the catch at most trawl stations. Both the pink shrimp (P. borealis) and the sidestripe sin imp (P. dispar) were uncommon in Port Valdez during 1972. They were more common in 1973, fairly abundant from 1977 to 1978, and were again reduced in numbers from 1980 to 1982. The common, small polychaetous annelids and crustaceans in the Port are important prey for P. borealis in other Alaskan waters (Rice et al. 1980; Carpenter 1983) and presumably represent common components of the diet of these crustaceans in Port Valdez. The increased numbers ol pink shrimp in the Port from 1977 to 1978 may be related to the increased abundance of polychaetes present there dur- ing this period (Feder et al. 1983; Feder and Shaw 1986). The food of P. dispar is not known. Other Fjords and Bays of Prince William Sound. Although no quantitative investigations of benthic fauna in Prince William Sound (other than for Port Valdez) are available, three qualitative surveys present useful information of Sheep Bay Simpson Ba\ 148 147 146 Figure 12-3. Map of Prince William Sound. Alaska, showing sampling sites for benthic biological studies. 362 Biological Resources f|ords and embayments there (Hoskin 1977; Feder and Paul 1977; and Feder and Hoberg 1981). Port Etches, an embayment of Hinchinbrook Island on the eastern side of Hinchinbrook Entrance (Fig. 12-3), was characterized by Hoberg (1986) as a deposit-feeding, mud- bottom infaunal assemblage. Many of the dominant infaunal mollusks present there (the protobranchs Nucula tenuis, Nuculana fossa, and Yoldia spp. and the gastropod Mitrella gouldi) were heavily preyed upon by the sunflower sea star (Pycnopodia helianthoides) (Paul and Feder 1975), Tan- ner crab, and bottomfishes (Feder and Hoberg 1981). The deposit-feeding polychaete Sternaspis scutata and the small suspension-feeding bivalve Axinopsida serricata — both char- acteristic of depositing environments of Prince William Sound — were also common here. The sandy bottom north of the entrance to the Port was dominated by suspension- feeding organisms (e.g., the sea pen, Ptilosarcus gurneyi, and the bivalve, Glycymeris subobsoleta). The epifauna of Port Etches was dominated by Arthro- poda (Crustacea — 22 species), Mollusca (8 species), and Echinodermata (4 species) (Feder and Hoberg 1981). The sunflower sea star accounted for 62% of the total biomass, and pink shrimp and Tanner crab made up 28 and 4% of the biomass, respectively. Mollusks only accounted for 0.2 % of the total biomass. The total epifaunal biomass was 0.8 g/ m-\ The benthic environment of outer Rocky Bay, an embay- ment on the northwestern side of Hinchinbrook Entrance (Fig. 12-3), was dominated primarily by suspension/small- zooplankton feeders (Feder and Hoberg 1981; Hoberg 1986). The infauna included: • sea pens (Ptilosarcus gurneyi) • bivalves (Astarte sp., Clinocardium spp., and Serripes groenlandicus ) • amphipods (Ampelisca hessleri). The epifauna included: • alcyonarians (Eunephthya rubiformis) • bryozoans • brachiopods • basket stars (Gorgonocephalus caryi) • sea cucumbers (Psolus chitinoides and Bathyplotes sp.) • crinoids (Heliometra glacialis maxima). Infaunal deposit feeders such as the polychaete Myriochele heeri and the bivalves N. tenuis and N. fossa were most impor- tant within the inner Bay. Eighteen echinoderm species accounted for 87% of the total epifaunal biomass of Rocky Bay. Three species — Bathyplotes sp., Ophiura sarsi, and Gorgonocephalus caryi — made up 34, 26, and 16% of this bio- mass, respectively. Although there were 35 crustacean spe- cies and 24 mollusk species, they only accounted for 5.9 and 3.2%, respectively, of the total biomass. Ophiuroids (pri- marily the browsing/predator O. sarsi) were dominant prey for Tanner crab in Rocky Bay. The benthos of outer Zaikof Bay (Fig. 12-3), on the south- western side of Hinchinbrook Entrance, was characterized by some of the same infaunal suspension-feeding and scav- enging species as Rocky Bay. Twelve species of echinoderms accounted for 50% of the total epifaunal biomass of Zaikof 146°30' Eastern group Western group 146°30' Figure 12-4. Two major station groups in Port Valdez, Alaska formed by cluster analysis of /^-transformed infaunal abun- dance data. (Modified from Feder and Matheke 1980b.) Bay. Two species, P. helianthoides and G. caryi, made up 31 and 15% of this biomass, respectively. Crustaceans accounted for 45% of the total biomass, lead by the sidestripe shrimp (24%), the pink shrimp (6%), and the Tanner crab (9%). The inner part of the Bay was dominated by deposit-fee- ding organisms. Deposit-feeding bivalves were more com- mon as food for Tanner crab here than in Rocky Bay. The bottom of outer Simpson Bay (southeastern Prince William Sound) (Fig. 12-3) is a gravely sand environment with fauna that is characteristic of areas with strong bottom currents. Organisms common here were sea pens, (P. gur- neyi), cockles (Clinocardium ciliatum and S. groenlandicus), brachiopods (Laqueus sp.), and basket stars (G. caryi) (Feder and Paul 1977). The epifauna of the inner Bay was domi- nated by bottom-foraging crustaceans, suggesting the pres- ence of a relatively rich infauna of polychaete worms, bivalve mollusks, and small crustaceans (see Paul, Feder, and Jewett 1979; Feder and Paul 1980; Rice 1980; Rice et al. 1980; and Feder and Hoberg 1981, for a listing of the food con- sumed by Alaskan crustaceans). Pink shrimp were abun- dant, sidestripe shrimp ranged from being common to abundant, and crangonid shrimps, Tanner crab, and Dun- geness crab (Cancer magister) were all common. The mud star C. crispatus was common on the soft bottom of inner Sheep Bay (adjacent to Simpson Bay; Fig. 12-3). The pink shrimp was abundant, and Crangon spp. and Pagurus spp. were also common epifauna in this Bay. The mud star was also common on the bottom adjacent to Gravina Point and outer Port Gravina (an embayment northwest of Simpson Bay). The pink shrimp was the domi- nant epifaunal species here. The benthos of the northern rocky entrance to Port Fidalgo, an embayment north of Port Gravina (Fig. 12-3), was dominated by suspension/zooplankton-feeding preda- tors such as the crinoid, H. glacialis maxima, and the basket star (Schaefers, Smith, and Greenwood 1955; Feder and Paul 1977). The fauna of the muddy bottom of inner Port Fidalgo consisted of deposit-feeding organisms typical of the inner portions of embayments of eastern Prince William Sound (H.M. Feder, University of Alaska, unpubl. data). The presence of suspension/zooplankton-feeding spe- cies (e.g., the infaunal bivalve C. ciliatum and the feather star Heliometra sp.) in trawl samples from inner Galena Bay The Subtidal Benthos 363 (north of Port Fidalgo; Fig. 12-3) suggests the presence of strong bottom currents and associated particulate organic carbon. The pandalid shrimps P. borealis, P. goniurus, and P. bypsinotus were common in Galena Bay. Columbia Bay, a tidewater-glacier fjord in the northern Sound (Fig. 12-3), contained walleye pollock (Theragra chal- cogramma) that fed heavily upon both pelagic hyperiid amphipods (Parathemisto libellula) and pink shrimp. The presence of these amphipods in the Bay and the common occurrence of the suspension/zooplankton-feeding sea pen, Ptilosarcus sp., suggest that an influx of zooplankton from the Sound into the fjord is common. The presence of the mud star in 50% of the trawls also suggests that there is a flux of carbon to the bottom sufficient to support a deposit- feeding infaunal assemblage in Columbia Bay (Feder and Paul 1977). Another tidewater-glacier fjord (Unaquik Inlet; Fig. 12-3) contained few infaunal organisms within the mud-gravel substrate inside the shallow (4 m) sill (H.M. Feder, University of Alaska, unpubl. data). However, large numbers of bottom-feeding pandalid shrimps were present outside the sill, suggesting the presence of a productive bot- tom there. Populations of deposit-feeding bivalve mollusks (Nuculana sp. and Yoldia sp.) and associated predatory snails (Natica spp.), along with large numbers of C. crispatus in the outer Inlet, all point to sufficient accumulations of carbon on the bottom to sustain deposit-feeding assemblages. Port Wells, a deep (400 m) tidewater-glacier fjord in the western Sound (Fig. 12-3), supported abundant populations of mud stars* protobranch bivalves, Yoldia spp., the heart urchin (Brisaster townsendi), and sea cucumbers (Synaptidae) on the bottom outside the sill (H.M. Feder, University of Alaska, unpubl. data). The mud bottom of the deep (350 m) Blackstone Bay (southwest of Port Wells; Fig. 12-3) supported a deposit- feeding assemblage of species similar to that found in Port Valdez in the northern Sound (H.M. Feder, University of Alaska, unpubl. data). The stomachs and intestines of Tan- ner crab from Blackstone Bay were often full of mud, an occurrence noted in other areas of Prince William Sound (e.g., Port Valdez) whenever appropriate crab food items were uncommon (Paul, Feder, and Jewett 1979). In the Port Nellie Juan area of western Prince William Sound, the macrobenthos of three contiguous fjords (Blue Fjord, Derickson Bay, and McClure Bay; Fig. 12-3) consisted primarily of deposit-feeding polychaetous annelids and bivalve mollusks (Hoskin 1977). Suspension feeders were more common in glacier-free McClure Bay (x = 15%) than in the more turbid Derickson Bay, a tidewater-glacier fjord (x = 6%) or Blue Fjord, a turbid outwash fjord (x = 9.5%). Biomass was highest in Derickson Bay (x = 19.9 g/m2) with values decreasing somewhat from the head to the mouth of the fjord. The biomass was intermediate in Blue Fjord (x = 12.9 g/m2), although a high value of 52 g/m2 occurred behind the sill (the mean of the other stations within Blue Fjord was 3.1 g/m2). The mean biomass in McClure Bav was 5.9 g/m2. Resurrection Bay. A description of the phvsical/chem- ical environment of Resurrection Bav (Fig. 12-5), a turbid outwash fjord with a deep (185 in) sill, is presented in Heggie et al. (1977). The benthic biology of this fjord is poorly known, but a qualitative survey of the benthos is available in Feder et al. (1979). Crustaceans — in particular, shrimps (Pandalus borealis, Pandalopsis dispar, and Crangon communis), hermit crabs, and Tanner crabs (Chioiwecetes bairdi) — dominated the epifauna throughout the Bay, but were more common inside the sill (Fig. 12-5). These species were particularly abundant directly behind the sill. The dominant infaunal taxa were deposit-feeding polychaetes and bivalve mollusks. The deep basin both within and outside the sill was charac- terized by the presence of the polychaete Sternaspis scutata, bivalve mollusks (Thyasiridae, Nuculana fossa), and the aplacophoran mollusk Chaetoderma robusta. The scaphopod mollusk Dentalium sp. and cumaceans occurred in low num- bers in this region. Stations sampled by Feder et al. (1979) within the deep basin contained up to 20 taxa. 149°20' Figure 12-5. Resurrection Bay, Alaska. The dark gray area rep- resents the region with the highest abundance values of pink shrimp {Pandalus borealis) and Tanner crab {Chionoecetes bairdi) as determined by Feder, Paul, and McDonald (1979). 364 Biological Resources Large numbers of two deposit-feeding taxa — the mud star and the heart urchin — occurred on the muddy bottom adjacent to Tonsina Creek on the western shore of the Bay. However, on the western side, inside the sill, the benthos was dominated by a variety of taxa (number of taxa at stations there ranged from 14 up to 21) typical of muddy substrates in Alaskan waters. These included: • polychaetes {Nephtys punctata, Sternaspis scutata, Terebellides stroemi, Spiophanes kroyeri, and Lumbrineris sp.) • bivalve mollusks (Axinopsida serricata, Thyasiridae, Nuculana fossa, and Odontogena borealis). Similar taxa were found south of Caines Head (outside the sill), although up to 38 taxa were described here. In contrast, south of Callisto Head, only 10 taxa (primarily deposit feeders) occurred. Along the eastern shore of Resurrection Bay, north of Fourth of July Creek, the bottom was dominated by deposit- feeding organisms (primarily the polychaete S. scutata and the bivalve Macoma brota). Laminaria spp. and other kelps were common here, and presumably supply detrital mate- rials for these organisms. The small bivalve A. serricata, typ- ical of muddy sediments in the Gulf, was also common in this region. The fine mud of Thumb Cove — a small embayment on the eastern shore at mid-fjord — contained a rich infauna (36 taxa) dominated by the sipunculid Golfmgia vulgaris and the polychaete Myriochele heeri. Also common were other deposit-feeding polychaetes, the sipunculid Phascolion strombi, and thyasirid bivalves. A relatively rich epifauna occurred on boulders protruding from the mud of outer Thumb Cove, suggesting that local eddy turbulence around these boulders makes particulate organic carbon available for the suspension feeders. Species present on the boulders within the Cove were solitary corals, serpulid polychaetes, ectoprocts, the brachiopod Laqueus sp., and the crinoid Heliometra glacialis maxima (H.M. Feder, University of Alaska, unpubl. data). Aialik Bay. Carpenter (1983) examined infauna in Aialik Bay, a shallow-silled (6-10 m) tidewater-glacier fjord west of Resurrection Bay (Fig. 12-6). She described —70 infaunal taxa, primarily annelids, mollusks, and arthropods. Twenty-one taxa occurred at 50% or more of the stations (Table 12-4). Nine taxa that occurred at all stations are: • Tharyx sp. • Nephtys punctata • Heteromastus filiformis • Melinna cristata • Nuculana sp. • Lumbrineris sp. • Myriochele occulata • Terebellides stroemi • Chaetoderma robusta. The first five of the above taxa occurred in high densities (732 individuals/m2) at one or more stations; the remaining taxa were present in low numbers. Six taxa constituted at least 10% of the wet weight at one or more stations (Table 12-5). 149°40' Figure 12-6. Aialik Bay, Alaska. The dark gray area represents the region investigated by Carpenter (1983). Twenty-three taxa occurred at stations closest to the glacier. The number of taxa increased to 28 at stations inside the sill while 38 taxa occurred at a station outside the sill. The abundance of individuals increased from near the glacier to a maximum just inside the sill. The lowest abun- dance values occurred outside the sill. Biomass values varied from 19 to 48 g/m2 at stations within the sill, and showed no pattern. The highest biomass value of 133 g/m2 occurred out- side the sill, mainly attributed to the presence of the heart urchin Brisaster townsendi, a species only found outside the sill. Dominance (Simpson Index) was highest near the glacier, where abundance values for N. punctata and M. cristata were also high. Diversity (Shannon Index) increased away from the glacier. Lower Cook Inlet. General. Lower Cook Inlet (south of Kalgin Island) (Fig. 12-7) is a tidally dominated estuary of the central Gulf of Alaska. It supports commercially harvested populations of Tanner, red king, and Dungeness crabs as well as shrimps The Subtidal Benthos 365 Figure 12-7. The two major infaunal station groups in lower Cook Inlet (Feder, Paul, Hoberg, andjewett 1981), but modified to incor- porate qualitative data derived from dredge samples (Feder 1978). Patterns of water movement within lower Cook Inlet are from Burbank (1977) and Muench et al. (1978). 366 Biological Resources (Pandalidae) (Ronholt et al. 1978). Primary production is high throughout the lower Inlet, and may exceed 7.8 g C/m2d in Kachemak and Kamishak Bays (Larrance, Ten- nant, Chester, and Ruffio 1977). During spring and summer, the eastern Inlet is characterized by clear, saline water enter- ing from the Gulf via Kennedy Entrance. A gyre system acts to increase the residence time of water in outer Kachemak Bay and contributes to the early development of the large spring and summer plankton population found there (Bur- bank 1977; Larrance et al. 1977). The western Inlet is greatly influenced by freshwater runoff and high concentrations of river-derived suspended matter carried there from the upper Inlet (Burbank 1977; Muench, Mofjeld, and Charnell 1978; Larrance et al. 1977; and Chester and Larrance 1981). These highly turbid waters restrict primary productivity in the western and northern portions of the Inlet, especially in early spring (Larrance etal. 1977). The deeper waters of lower Cook Inlet are characterized by a relatively smooth bottom and strong tidal currents. The sediment is relatively coarse, gravel-to-boulder-bearing sand in the north grading to clean sand and then to muddy sand to the south (Bouma and Hampton 1976). The sedi- ment of upper Kamishak Bay is a muddy sand grading to mud in the southern portion of the Bay. The sediments of inner Kachemak Bay are silts grading to muddy sand and rippled sand in the outer Bay (Driskell and Lees 1977). The bottom of the inshore waters of outer Kachemak Bay is char- acterized by shell debris, while the shallow subtidal area is a boulder/large-cobble facies (Driskell and Lees 1977). Infauna. Subtidal invertebrates are rare in the turbid waters of upper Cook Inlet (north of Kalgin Island) (Rosen- berg et al. 1969; Bakus et al. 1979; and H.M. Feder, University of Alaska, unpubl. data). However, in the relatively clear waters of lower Cook Inlet over 370 invertebrate taxa repre- senting 11 phyla were described from grab samples taken at depths between 24 and 181 m (Feder, Paul, Hoberg, andjew- ett 1981). Eighteen species occurred at 50% or more of the stations (Table 12-4), and 17 species constituted at least 10% of the wet weight at one or more stations (Table 12-5). Abun- dance values at sampling stations ranged between 150 and 3,988 individuals/m2 and the biomass ranged from 21 to 731 g/m2. Cluster analysis of infaunal data (Feder, Paul, Hoberg, andjewett 1981) identified two major station groups (Fig. 12-7). Group 1 consisted primarily of stations from south- western Cook Inlet. Group 2 consisted of stations in the east- ern part of the Inlet adjacent to Kachemak Bay. The two groups were distinguished by a number of differences, including (Tables 12-13 and 12-14): • dominant taxa • biomass • abundance • Shannon diversity • species richness • trophic group composition. High biomass values within Station Group 2 were generally the result of large numbers of both the sand dollar, Echi- narachnius parma, and two bivalve mollusks (Tellina nuculoides and Glycymeris subobsoleta). Dredge sampling (Feder 1978) complemented and expanded data derived from grab samples (Feder, Paul, Hoberg, andjewett 1981). Dredging made it possible to Table 12-13. Dominant taxa (no./m2 and g/m2) and feeding classes in the groups from lower Cook Inlet determined by cluster analysis (Feder, Paul, Hoberg, and Jewett 1981). All samples collected by van Veen grab (see Fig. 12-7). Feeding Abundanci Feeding Biomass Taxa Phylum2 Class6 (No./m2) Taxa Phylum11 Class6 (g/m2) Group 1 Axinopsida serricata M SF 352 Echinarachn his parma E SF 9.5 Lumbrineris sp. A DF/P 157 Ptilosarcus gurneyi C SF/P 8.9 Nucula tenuis M DF 86 Macoma calcarea M DF 7.8 Magelona sp. A DF 83 Nuculana fossa M DF 6.4 Nuculana fossa M DF 74 Alcyonacea C SF/P 5.8 Macoma calcarea M DF 67 Macoma moesta M DF 3.2 Haploscoloplos elongatus A DF 48 Travisia brevis A DF 2.7 Lumbrineris zonata A DF/P 40 Nephtys ciliata A DF/P 1.6 Byblis gaimardi Ar S 39 Axinopsida serricata M SF 1.4 Eudorella emarginata Ar DF 28 Group 2 Tellina nuculoides M SF/DF 263 Echinarachnius parma E SF 186 Glycymeris subobsoleta M SF 95 Tellina nuculoides M SF/DF 46 Spiophanes bombyx A DF/SF? 25 Ectoprocta - SF 16 Echinarachnius parma E SF 20 Glycymeris subobsoleta M SF 10 Magelona sp. A DF 16 Astarte rollandi M SF 3 Ophelia limacina A DF 13 Allocentrotus fragilis E S 3 Glycera capitata A P 11 Ophelia limacina A P? 1 Paraphoxus sp. Ar S 10 Glycera capitata A P 1 aA = Annelida; M = Mollusca; Ar = Arthropoda; E = Echinodermata; C = Cnidaria. b DF = deposit feeder; SF = suspension feeder; P = predator; S = scavenger. The Subtidai Benthos 367 Table 12-14. Distinguishing features of the two major infaunal groups determined by multivariate analysis for lower Cook Inlet (Feder, Paul, Hoberg, and Jewett 1981). (Refer to Fig. 12-7 for location of stations and groups.) Group 1 Group 2 Biomass (g/m-) 74 283 Abundance (individuals/m2) 1,743 616 Shannon Diversity 3.1 2.3 Species Richness 10.5 5.5 Deposit Feeders (%)a 58 38 Suspension Feeders (%)a 19 27 " Percent of all individuals counted in samples. examine regions not readily sampled with a grab. One such region is the rock/sand bottom immediately north of the Barren Islands and adjacent to Kennedy Entrance where fauna consisted primarily of suspension-feeding bivalve mollusks, brachiopods, bryozoans, and sand dollars. The fauna of the rock/cobble channel east of Kalgin Island and the rocky area adjacent to Tuxedni Bay and Chisik Island also consisted of bryozoans and brachiopods. The bottom immediately north of Augustine Island was identified as a deposit-feeding assemblage as a result of grab sampling, but dredge sampling revealed large numbers of the barnacle Balanus rostratus on pumice fragments. Studies of Kachemak Bay by Driskell and Lees (1977) pro- vide a descriptive overview of the bottom characteristics and associated infaunal species there. Several areas investigated by Driskell and Lees (1977) in the outer Bay overlap those considered by Feder, Paul, Hoberg, and Jewett 1981; results of both studies complement each other. Driskell and Lees (1977) identified five major subtidai geological facies within Kachemak Bay, consisting of four substrate types (rock, sand, silt, shell debris) (Fig. 12-8), and described their char- acteristic infaunal assemblages. The northern shell debris assemblage was the richest — accounting for over 80% of the total species collected in Kachemak Bay. Mollusks and bryozoans dominated this assemblage. The southern shell-debris assemblage was dominated by mollusks with juvenile bivalves (mainly G. subobsoleta) most common; polychaetes and bryozoans were of lesser importance. The rippled sand assemblage was also dominated by mollusks with the pinkneck clam Spisula poly- nyma most common; low numbers of other species of clams (e.g., Tellina spp.) were also present. In addition, adult sand dollars (E. parma) occurred throughout the area. The mud- dy-sand assemblage of the Bay was dominated by bivalve mollusks — Axinopsida serricata, Nuculana fossa, Pandora gran- dis, Nucula tenuis, Psephidia lordi, S. polynyma, and Yoldia semi- nuda. The sea pen Ptilosarcus gurneyi was also common. Juve- nile sand dollars were concentrated in the northern portion of this assemblage. The silt assemblage of the Bay was impoverished — with polychaetes most abundant, followed closely by mollusks. The boulder/large-cobble facies is dis- cussed in the epifaunal section of this chapter. Bivalves are important trophic links in the benthic food webs that lead to Tanner. Dungeness, red king, and hermit crabs, as well as to flatfishes and other organisms in lower Cook Inlet (Feder 1978; Paul, Feder, and Jewett 1979; Feder and Paul 1980; Rice 1980; and Feder, Paul', Hoberg, and Jew- ett 1981). Further, based on the benthic sampling of Driskell and Lees (1977), Feder (1978), and Feder and Paul (1980), it is clear that bivalve mollusks are common (76 species) and widely distributed throughout the Inlet. Deposit-feeding species dominated the fine sediments on the western side of the Inlet. Suspension-feeding species were more abundant in sandier areas of outer Kachemak Bay. Distribution, size, age, and mortality data for the six dominant bivalves in lower Cook Inlet are available in Feder, Paul, Hoberg, and Jewett (1981). These species include: • Nucula tenuis • Nuculana fossa • Macoma calcarea • Glycymeris subobsoleta • Spisula polynyma • Tellina nuculoides. Growth rates for each of these species were similar through- out the Inlet (Feder, Paul, Hoberg, and Jewett 1981). The estimated mean infaunal production values for the two lower Cook Inlet station groups (Fig. 12-7) are: Group 1— 6.6 gC/m2y, and Group 2—3.4 g C/m2y (H.M. Feder, Uni- versity of Alaska, unpubl. data). The estimated value of benthic production for a station in outer Kachemak Bay is 2.5 g C/m2y; for two stations located beneath the gyre out- side of Kachemak Bay, the estimated value is 6.3 g C/m-'y (Knull and Williamson 1969; Burbank 1977); for a station immediately south of Augustine Island in Kamishak Bay, the estimated value is 9.9 g C/m2y; and for a station located within the Tanner crab nursery area in Stevenson Entrance, the estimated value is 10.1 g C/m2y (Feder, Paul, Hoberg, and Jewett 1981; Feder and Paul 1981). Epifauna. Most of the shallow ( < 20 m) subtidai epifaunal investigations of Cook Inlet were conducted on rocky hab- itats in the lower portion of the Inlet — although some soft- bottom habitats have been examined there. The shallow subtidai assemblages of rocky substrates examined fall into Figure 12-8. Geological facies in outer Kachemak Bay, lower Cook Inlet. (Modified from Driskell and Lees 1977.) 368 Biological Resources three geographically distinct groups: 1) southern Kachemak Bay, 2) northern Kachemak Bay, and 3) western Cook Inlet. The three assemblage groups are distinguished on the basis of the composition and structure of both macrophyte and epifaunal components. The dominant species from these areas are listed in Table 12-15, and a characterization of these three assemblages is summarized below (after Lees and Driskell 1981) (Fig. 12-9): 1) The southern Kachemak Bay assemblage has a lush, fairly dense kelp bed consisting of both a canopy and an understory. The epifaunal community exhibits low diversity and is poorly developed, although the preda- tor/scavenger component is diverse with low density. 2) The northern Kachemak Bay assemblage is charac- terized by a moderate kelp bed development that con- sists of a very spotty, thin canopy and a moderate understory, but with well-developed components of both sedentary and predator/scavenger invertebrates. 3) The western Cook Inlet assemblage exhibits little or no development of a kelp bed community. Sedentary invertebrates are well developed, and predator/scav- enger epifauna are moderately developed. Differences in the shallow subtidal rocky epifauna are most apparent between the east and west sides of the Inlet. Although many of the species found on the west side are also found on the east side, the absence of numerous eastern spe- cies in the west is most apparent. Further, there is an abun- dance of numerous species in the west that are more charac- Table 12-15. Dominant species in major rock bottom, shallow ( < 20 m) subtidal assemblages in lower Cook Inlet (Lees and Driskell 1981). Southern Kachemak Bay Northern Shelf of Ka< :hemak Bay West Side of Co< Knoll White >k Inlet Seldovia Barbara Jakalof Archimanritof Bluff Troublesome Head Gull Black Point Point Bay Shoals Point Creek Lagoon Island Reef Kelps Surface canopy Nereocystis leutkeana Aa(12)b A A C(19) Alaria fistulosa A(12) A C(12) C Understory Agarum cribrosum A(21) A A CO 3) C(16) C(14) C(5) C(3) S(4) Alaria spp. (not fistulosa) Intertidal Intertidal Intertidal A(2) C(2) S(2) Laminaria groenlandica A(20) A A C(10) C(12) C(14) C(4) C(3) S(2) Maximum depth of kelps (m) 21 >14 12 13 16 15 5 3 4 Sedentary Invertebrates Flustrella gigantea A C P C A C P Microporina borealis C C s Mycale spp. C c P c C C C Saxidomus giganteus C P A C-A s A Modiolus modiolus A A c C A s S Potamilla neglecta A A C c Halichondria panicea S s A P c c Balanus rostratus C c S-C c c Dendrodoa pulchella A A Costazia? surcularis C A A Metridium senile s C s s s S Cucumaria miniata s s c A c C.fallax s c A Bidenkapia spitsbergensis F c c Dendrobeania murrayana c s c Motile Invertebrates Evasterias trosrhelii s A c S Dermasterias imbricata A s Pycnopodia helianthoides c s A s Orthasterias koehleri c p C s Henricia leviuscula c c s s P Leptasterias polaris aceruata c s c C p P Solaster stimpsoni s c s s s p Crossaster papposus c p c c c s C p P Henricia sanguinolenta s p A c c C c P Fusitriton oregonensis c A c c c C s P Neptunea spp. c c c s s P Buccinum glaciate s s s s s P Beringius hennicotti s s s s P Tonicella spp. c p C c c c c s P Strongylocen trot us droebath iens is c c A A c A s s P aA = Abundant; C = Common; S = Sparse; P = Present. b Parenthetic numbers represent maximum depth (m) of occurrence in this area. The Subtidal Benthos 369 154 153 152 151 60 ^9 Troublesome Creek ^ Bluff Point Ni"!i,;'"^f Archimandritof Shoals y*ja Black Reef Barabara Point _^ -j Seldovia Point £?'$ Cape Douglas 153 152 151 Figure 12-9. Areas in lower Cook Inlet in which shallow sub- tidal studies were made by Lees and Driskell (1981). teristic of the Bering and Beaufort Seas. This fact is especially apparent when comparing bryozoan assemblages (Lees and Driskell 1981). Benthic trawling conducted during various periods from 1976 to 1978 in deeper portions of the Inlet (25-181 m) yielded at least 287 invertebrate species from 46 stations (Table 12-16). Three or four species generally dominated at each station (Feder and Paul 1981). Twelve species accounted for nearly 84% of the total epifaunal biomass (Table 12-17). The dominant phyla — in numbers per m2 — for combined data were Arthropoda (Crustacea) (91%), Mollusca (3.5%), and Echinodermata (3%). In terms of live weight, the dominant groups were Arthropoda (Crustacea) (74%), Echinodermata (17%,), and Mollusca (6%) (Table 12-18). The important species were: 1) Tanner crab — accounting for 38.6% of the live weight and 1.1 g/m2, 2) humpy shrimp (Pandalus goniurus) — accounting for 20.7% of the weight and 0.6 g/m2, 3) red king crab — accounting for 7.2% of the weight and 0.2 g/m2, and 4) sea cucumber {Cunimaria fallax) — accounting for 4.8% of the weight and 0.1 g/m2 (Table 12-17). Within lower Cook Inlet the dominant organisms pre- sent reflected both the nature of the substratum and the bot- tom-current dynamics. In the inner portion of Kachemak Bay, where fine-grained sediments mainly prevail, omnivorous pandalid shrimps (pink, humpy, and coonstripe — P. hypsinotus), dominated both in terms of abundance (number/m2) and biomass (g/m2) (Table 12-19). Toward the more dynamic outer Kachemak Bay, both the epifaunal density and the biomass were dominated by: 1 ) the grazing green sea urchin Strongylocentrotus droebachien- sis, 2) the suspension-feeding sea cucumber C. fallax, and 3) the sand dollar Echinarachnius parma. In Kamishak Bay, where the suspended sediment load tends to be greater than in Kachemak Bay, the omnivorous crangonid shrimps (mainly Crangon dulli) (Rice 1980) were the most numerous, while the scavenger/predator king and Tanner crabs dominated the biomass (Table 12-19). Table 12-16. Number and percent of epifaunal species by phylum at depths >25 m in lower Cook Inlet (Feder and Paul 1981). NlAIHI-K Pi K( EN I Porifera Cnidaria Rhynchocoela Annelida Mollusca Arthropoda Ectoprocta Brachiopoda Echinodermata Urochordata Totals 1 0.3 9 3.1 1 0.3 19 6.6 94 32.8 99 34.5 8 2.8 6 2.1 47 16.4 3 1.0 287 100.0 In the central part of lower Cook Inlet where the bottom is sandy, the sand dollar and Tanner crab dominated both in terms of numbers and weight. In the outer portion of the Inlet where sediments are finer grained, Tanner crabs were most numerous and made the greatest contribution to the biomass. King crabs were also dominant in the biomass from this region (Table 12-19). Stations in the vicinity of outer Kachemak Bay displayed the greatest epifaunal biomass, ranging from 6.2 to 14.5 g/m2. These relatively large biomass values can presumably be attributed to the high rate of primary productivity and the flux of much of this production to the bottom (Larrance and Chester 1979). The dominant epibenthic invertebrates in this region are capable of either using this organic carbon directly (e.g., C. fallax and E. parma) or indirectly — as in the case of large predators, such as the red king crab and the Tanner crab — by feeding on organisms that are suspension or detrital feeders. Shellfish landed from lower Cook Inlet during the 1984-1985 season included Tanner and Dungeness crabs, five species of pandalid shrimps, scallops (Pecten caurinus), and octopus. The shellfish harvest for that season was valued at $6.3 million (ADF&G 1985b). Table 12-17. Biomass of the 12 dominant epifaunal species at depths > 25 m in lower Cook Inlet (Feder and Paul 1981). Biomass Percent of (g/m-') Total Bk>\i \ss Fusitriton oregonensis 0.02 0.68 Neptunea lyrata 0.11 3.83 Pandalus borealis 0.02 0.84 Pandalus goniurus 0.60 20.72 Pa ra lith odes cam tsch alica 0.21 7.20 Hyas lyratus 0.05 1.61 Ckionoecetes bairdi 1.12 38.60 Cancer magister 0.03 1.21 Evasterias Iroschelii 0.01 1.40 Echinarachnius parma 0.02 0.70 Strongylocentrotus droebacliiensis 0.07 2.29 Cucumaria fallax 0.14 4.83 Totals 2.43 83.91 370 Biological Resources Table 12-18. Biomass of epifaunal phyla at depths >25 m in lower Cook Inlet (Feder and Paul 1981). Biomass (g/m*) Percent of Total Biomass Porifera Cnidaria Rhynchocoela Annelida Mollusca Arthropoda Ectoprocta Brachiopoda Echinodermata Urochordata Totals 0.026 0.91 0.047 1.67 <0.001 <0.01 <0.001 0.02 0.071 5.87 2.155 74.09 0.002 0.05 <0.001 0.02 0.504 17.33 <0.001 0.03 2.909 100.00 Tanner crab were present throughout all regions of lower Cook Inlet (Feder and Paul 1981). Although adults were ubiquitous, juveniles were concentrated in the western and southwestern portions of the Inlet. In particular, the region between Cape Douglas and the Barren Islands, at depths of 150 to 170 m, is apparently a Tanner crab nursery area. Throughout various sampling periods, large con- centrations of tiny crab (carapace widths ranging from 3-25 mm) were found there. These crab often occurred among a substrate of silty sand with scattered mats of sponge, hydro- ids, and polychaete tubes (mainly Spiochaetopterus sp.). As many as 414 of these small crab per kilometer were captured in a small (6.1 m) trawl in this region during October 1976. These juveniles were the dominant prey for three common demersal fishes — Pacific halibut (Hippoglossus stenolepsis), Pacific cod (Gadus macrocephalus), and great sculpin (Myox- ocephalus polyacanthocephalus) — that were also common within the same nursery area. Nearly 63% of the 43 Pacific cod examined contained Tanner crab with as many as 12 crab found within a single cod stomach. As a scavenger/predator, the Tanner crab feeds on a vari- ety of prey organisms (Feder andjewett 1981a; Jewett and Feder 1983). A food analysis of 428 Tanner crab, taken mainly from the western and southwestern portions of the Inlet, revealed that crab of different size, sex, and state of maturity consumed diverse but similar prey species (Paul, Feder, andjewett 1979). The four major food items were: 1) small clams — 44%, 2) hermit crabs — 34% frequency of occurrence, 3) barnacles — 18 % , and 4) crangonid shrimps — 9%. Occasionally, the crab preyed upon polychaetes, gas- tropods, amphipods, and ophiuroids. Stomach contents typically reflected prey species common to a given area. Fur- thermore, most of the prey species tended to use detrital or suspended material either directly or indirectly. The Tanner crab is currently the target species found within the ADF&G Cook Inlet Shellfish Management Area. Historically, the Kamishak Bay and Barren Islands districts have produced most of the commercial Tanner crab; the Southern District, which includes both mid- and outer Kachemak Bay, has been of secondary importance. There has been a gradual decline in landings since the high of 3.5 x 103 mt during the 1973-1974 season. The 1983-1984 har- vest was only 1.3 x 10:1 mt as of March 1985 (ADF&G 1985b). The crabbing fleet within the Southern District in the 1984-1985 season had doubled from recent years to ~ 80 vessels. Regardless of the increased effort during this season, the harvest trend is expected to continue in a downward direction for at least the next few years (S. Kyle, ADF&G, pers. coram., 1984). Although the Dungeness crab was among the top twelve biomass-dominating epifauna captured in Cook Inlet trawl studies between 1976 and 1978, it only accounted for 1.2% of the epifaunal weight (Table 12-17). Furthermore, its dis- tribution was generally confined to the Kachemak Bay area. As a predator/scavenger, the Dungeness crab feeds on a number of benthic prey species. In 1977-1978, those crab over 50 mm in carapace width from Kachemak Bay pri- marily preyed on: 1) small bivalves — 67% frequency of occurrence, 2) barnacles — 11%, and 3) amphipods — 6% (Feder and Paul 1980). For smaller crab (carapace widths 22 to 44 mm), the most frequent prey were: 1) Foraminifera — 36% frequency of occurrence, 2) polychaetes— 28%, 3) bar- nacles—28%, and 4) small bivalves — 25%. Dungeness crab have been harvested commercially in lower Cook Inlet since 1961. Annual catches have fluctuated markedly — from the smallest catch of 3.2 mt in 1967 to the largest catch of 968.6 mt in 1979. The average annual harvest from 1961 through 1984 was 283 mt, with most of the catch taken from near Kachemak Bay (ADF&G 1985b). The 1984 catch was nearly 364 mt, 75% of which came from the inner embayments of Kachemak Bay rather than from the Bluff Table 12-19. Dominant epifaunal invertebrates from deep ( >25 m) regions in lower Cook Inlet (Feder and Paul 1981). The species are ranked in decreasing order of abundance and biomass. Region Abundance Biomass Inner Pandalus borealis Pandalus hypsinotus Kachemak Bay Pandalus goniurus Pandalus hypsinotus Pandalus borealis Pandalus goniurus Mid- Pandalus borealis Chionoecetes bairdi Kachemak Bay Crangon dalli Pandalus borealis Cucumaria fallax Cancer magister Outer Kachemak Bay Strongylocentrotus droebachiensis Cucumariafallax Ech inarachnius parma Cucumariafallax Strongylocen trotus droebachiensis Echinarachnius parma Central Echinarachnius parma Chionoecetes bairdi Cook Inlet Chionoecetes bairdi Echinarachnius parma Crangonidae Ptilosarcus gurneyi Outer Chionoecetes bairdi Chionoecetes bairdi Cook Inlet Crangonidae Paralithodes camtschatica Pandalus borealis Neplunea lyrata Upper Kamishak Bay Crangon dalli Pandalus goniurus Chionoecetes bairdi Chionoecetes bairdi Neptunea lyrata Paralithodes camtschatica Lower Crangonidae Chionoecetes bairdi Kamishak Bay Chionoecetes bairdi Paralithodes camtschatica The Subtidal Benthos 371 Point area which has traditionally yielded large quantities. The majority of the harvest is normally taken from May through October. The ex-vessel value of the 1984 harvest was approximately $1.08 million (ADF&G 1985b). Although king crab only accounted for — 7% of the epi- faunal biomass sampled during the Cook Inlet OCSEAP investigations (Table 12-17), the following account of the dis- tribution, biomass, and relative abundance of this crab is appropriate because of its historic importance to Cook Inlet and adjacent Gulf of Alaska waters (ADF&G 1985 a,b,c,d). King crab occurred in Kachemak and Kamishak Bays during all eight sampling months (March through August, October, and November). However, during October 1976 they also occurred within the Tanner crab nursery grounds of the outer Inlet. Over 95% of the king crab captured dur- ing all sampling periods were sexuallv mature individuals. King crab within Kachemak and Kamishak Bays are apparently resident populations since adult crabs were found there in all periods. Crab of various sizes were often found in Kachemak Bay associated with remnants of macro- algae, hydroids, sponges, and bryozoans on the bottom. One station in outer Kachemak Bay yielded 28 juveniles with a biomass of 10.7 g/m2 in March 1978. These crab were associ- ated with the macroalgae, hydroids, and other taxa men- tioned above. Evidence of a major king crab nursery along the shallow (< 27 m), rocky perimeter of outer Kachemak Bay from Dia- mond Gulch to Mutnaia Gulch is presented by Sundberg and Clausen (1977). Furthermore, Haynes (1977) reported that the concentration of glaucothoe larvae in the same gen- eral area, between Anchor Point and Bluff Point, implies that this area is especially important for the settling of king crab larvae. King crab populations within Kamishak Bay were domi- nated by adults. The few juveniles taken were generally larger than those encountered in Kachemak Bay. Since a suitable habitat for king crab larval settlement was not observed and a resident adult population apparently exists there, suitable juvenile habitat presumably occurs nearby at shallower depths within the Bay. Many Kodiak Island regions that are shallow, rocky, and rich in epiphytic growth are ideal environments for king crab mating, spawning, egg-hatching, and juvenile-rearing activities (Jewett and Powell 1981). The red king crab, like Tanner and Dungeness crabs, is a scavenger/predator capable of taking a variety of prey (Feder and Jewett 1981a; Jewett and Feder 1982). The food found in crabs from the Kachemak Bay region was domi- nated by the pinkneck clam Spisula polynyma (found in 38% of the crab stomachs). Barnacles were found in 14% of the crab stomachs, and the snail Neptunea lyrata was found in 11 percent. An additional 25 food categories were observed (Feder and Paul 1980; Feder, Paul, Hoberg, and Jewett 1981). The food of post-larval individuals (3-5 mm carapace length) from northwest Kachemak Bay consisted of: 1) un- identified crustaceans — 45% frequency of occurrence, 2) polychaete worms — 31%, 3) foraminiferans — 27%, and the bryozoan Flustrella sp. — 10%. Sediment was found in 93% of the tiny crab (Feder, McCumby, and Paul 1980). Among the 20 food categories identified from the stom- achs of Kamishak Bay king crab, the three most frequently observed prey were barnacles (81% frequency of occur- rence), bivalves of the family Mytilidae (13%), and hermit crabs (12%) (Feder and Paul 1980). Benthic samples from stations adjacent to Augustine Island often revealed the presence of volcanic bombs or pumice which resulted from the eruption of Augustine vol- cano in February 1976. Prior to the eruption, the bottom around the Island had little rocky substrate, and therefore, settling organisms such as barnacles were restricted pri- marily to biological substrates such as shells and crab car- apaces. During the April and October 1976 surveys, pumice samples were examined for settling organisms, and no set- tlement was apparent. However, similar samples taken in November 1977 revealed that large numbers of barnacles (Balanus sp.), had settled on most of the volcanic bombs we examined (Feder 1978). Feder and Paul (1980) examined the stomach contents of potential barnacle predators taken in trawls during November 1977. Thirty-six king crab collected at a single station had full stomachs. All the crab had barna- cles in their stomachs and 60% of these crab were feeding exclusively on barnacles. Judging from both the weights of the barnacle hard parts from within crab stomachs and from live specimens on the bombs, the average number of barna- cles in each crab stomach was estimated as 11.2 (SD = 7.4). Other organisms taken in the trawls from this region were the hermit crab Pagurus ochotensis and the Tanner crab, both of which were feeding on barnacles. Apparently, the substrate provided by the volcanic eruption on Augustine Island had an important effect on both the population den- sities of the barnacles and the food habits of the crabs. The king crab fishery is the oldest commercial shellfish fishery in Cook Inlet. The earliest recorded commercial landings occurred in 1937 when crabs were canned at a Halibut Cove packing facility (ADF&G 1985b). From the late 1960s through 1976 the seasonal total catch ranged from 1.1- to 2.2 * 103 mt. Since that time, catches have generally been decreasing. Since the 1982-1983 season, the Southern Dis- trict (mid- and outer Kachemak Bay) has been closed. The 1983-1984 Cook Inlet king crab harvest of 87.7 mt was a record low and was 93% below the 16-year average of 1.3 x 103 mt (ADF&G 1985b). The entire Cook Inlet manage- ment area was closed during 1984-1985, and the outlook for opening the fishery within the next several years is grim. Reasons that have been suggested for the declining popula- tion are the prevalence of 1) viruses, 2) microsporidians, 3) rhizocephalans, 4) egg predation by the nemertean worm Carcinonemertes errans, and 5) predation of larvae and juve- niles by various fishes (Melteff 1985). All of these factors have been observed in Cook Inlet or adjacent waters. Three numerically important species of pandalid shrimps (P. borealis, P.goniurus, and P. hypsinotus) are also har- vested commercially in lower Cook Inlet. The major trawl fishery has historically taken place in the Southern District which includes Kachemak Bay. Population-abundance- index surveys have been completed each year in Kachemak Bay since 1971 by ADF&G (1985b). Since the May 1979 index survey, the abundance index has been decreasing. After 372 Biological Resources completion of the May 1983 abundance-index survey in Kachemak Bay, the stock decreased to the point where a commercial fishery was not warranted. The fishery was reopened in January 1984. Information gathered from that winter fishery and the subsequent spring index survey indi- cated that continued harvest was warranted in the 1984-1985 season and ~ 682 mt were harvested with 79% of the harvest taken inside the Homer Spit. Species composition samples collected throughout that season were approximately: 75% P. borealis, 12% Pandalopsis dispar, 10% P. goniurus, and 3% P. hypsinotus (ADF&G 1985b). Food samples taken from P. borealis, P. hypsinotus, and P. goniurus in lower Cook Inlet revealed that they are active predators of infaunal invertebrates as well as foragers that ingest detritus and sediment (Rice et al. 1980). Approx- imately 20 food categories were recorded for each of these shrimp species, with diatoms, polychaetes, bivalves, and crustaceans as the most frequently consumed food groups. Sediment was observed in at least 60% of each species. Crangonid shrimps are not harvested commercially in lower Cook Inlet (or elsewhere in Alaska), but were abun- dant in trawl samples taken there. Crangon dalli was the dom- inant species taken (Feder and Paul 1981) (Table 12-19). These shrimps are food generalists, and Rice (1980) describes 60 categories of food for them in Cook Inlet. The most important food items were polychaetes, crustaceans, and bivalve mollusks. Most organisms used as food were deposit feeders, as evidenced by sediment and detrital mate- rial that was found in stomachs of all the feeding shrimp. The high occurrence of sediment in shrimp stomachs (typ- ically more than 60% on a dry weight basis) and the types of food utilized by them suggest that these crustaceans rely heavily on the sediment/detrital system for food (Rice 1980). Sediment ingestion is described as relatively important in Crangon septemspinosa, with sand representing 4 % of the total volume of stomach contents (Wilcox and Jeffries 1974). In crangonids from Cook Inlet, inorganic sediment con- stituted over 56% of the stomach contents on a dry weight basis. A high percentage of sediment in stomach contents of pandalid shrimps and hermit crabs in lower Cook Inlet was also noted by Rice et al. (1980) and Feder, Paul, Hoberg, and Jewett (1981). Moriarity (1976) reported that the prawn Meta- penaeus sp. ingests sediment and uses bacteria for food as part of its natural diet elsewhere. Preliminary experiments by Rice (1980) imply that Crangon dalli may also be able to assimilate the bacterial carbon that is associated with sedi- ments. He suggests that, during low food levels, shrimp use the carbon that is associated with sediment (inclusive of microbial carbon) as a nutrient supplement. In Cook Inlet, crangonids are an important food source for Tanner crab (Paul, Feder, and Jewett 1979) and bottom- feeding fishes (Feder, Paul, Hoberg, andjewett 1981), includ- ing: • starry flounder (Platichthys stellatus) • halibut (Hippoglossus stenolepis) • Pacific cod (Cadus macrocephalus) • rock sole (Lepidopselta bilineata) • flathead sole (Hippoglossoides elassodon) • walleye pollock (Tlieragra chakogramma). The Western Gulf of Alaska and Kodiak Island Regions General Western Gulf Region — Infauna and Epifauna. The shelf of most of the western Gulf (ie., west of Cape Igvak) consists of slopes characterized by marked dissection and steepness — with many banks and reefs, numerous coarse, clastic, or rocky bottoms, and patchy bottom sediments. In contrast, the shelf adjacent to the Kodiak Archipelago con- sists of flat, relatively shallow banks cut by transverse troughs (Fig. 12-10). Unconsolidated sediments of the entire western shelf are distributed in relation to: 1) the physiogra- phy of the bottom and 2) local currents and related turbulence. The banks are exposed to both wave and current action (particularly during winter storms) that continually resus- pend bottom sediments and winnow out the finer sands, silts, and clays. Bottom materials such as sand, gravel, boul- ders, and broken shells are most characteristic of the banks. Other, less common features are fine sediments which accu- mulate in local depressions, and ridges that expose silt- stones and silty sandstones. The deeper troughs commonly contain fine sands and muds made up in large part by vol- canic ash (Bouma and Hampton 1976; Hampton et al., Ch. 5, this volume). The investigations of Semenov (1965) demonstrated that large areas of the bottom of the western Gulf were domi- nated by sessile suspension (filter) feeding infauna and epi- fauna (e.g., sponges, sabellid and serpulid polychaetes, nest- ling clams (Saxicavidae), barnacles, and the brachiopod Terebratulina unguicula), with the biomass exceeding 3,000 g/m2 in some regions. The biomass of this trophic group in the western Gulf was 112 g/m2 (62% of the total biomass) (Table 12-2). Although sessile suspension feeders were com- mon in the shallow sublittoral, they were most abundant at the shelf edge where valleys separate the broad plateaus from the coastal areas. Many of these plateaus form banks with complex relief and rock outcrops that are covered with coarse sediments — a substratum that is ideal for sessile sus- pension feeders. Separate patches of non-mobile filter feeders were encountered in the coastal regions such as Unimak Pass, southwest of the Shumagin and Trinity Islands, and east of Afognak Island. Mobile suspension (filter) feeders (e.g., the bivalve mol- lusks Pectinidae, Carditidae, Glycymeridae, Astartidae, Ser- ripes sp., and Cardium sp., the amphipods Ampelisca spp., and the sand dollar Echinarachnius parma) also dominated in the western Gulf. They occurred mainly in two areas: 1) on the plateau-like surfaces of the shelf in areas with smooth relief and a predominance of sandy sediments and 2) on the sides of troughs and canyons where sand has accumulated. The organic level was low in these sediments. The biomass of this trophic group in the western Gulf was 26 g/m2. This trophic group was also commonly found adjacent to the islands where coarse sands and broken shell occur. Browsers and selective deposit-feeders — browsing detritus-feeders according to Semenov (1965) (e.g., terebellid polychaetes and the bivalve mollusks Nucula ten- uis, Nuculana fossa, Yoldia spp., and Macoma spp.) — were most common on bottoms which had a smooth relief and which were covered with fine-grained sand or muddy sediments at depths of from 52 to 158 meters. The organic carbon content The Subtidal Benthos 373 -57 56 156 154 152 Figure 12-10. Kodiak Shelf showing the major physiographic features. of these sediments was relatively low (0.39-0.50%). These trophic groups represented a relatively insignificant por- tion of the total benthic biomass of the western Gulf (8.4%), with a biomass of 15.1 g/m2. However, large concentrations (100-250 g/m2) of browsers and selective deposit feeders were found on the shelf of Kodiak, Trinity, and Chirikof Islands, and in the trough between the Shumagin Islands and Sanak Island. In the basin west of Kodiak Island at the entrance to Shelikof Strait, the slopes were occupied by these two trophic groups. The characteristic bottom sedi- ment, where a third trophic group — non-selective deposit feeders (termed non-selective consumers by Semenov 1965) — was found, consisted of fine-grained sand, sandy mud, and mud with an organic content between 0.5 and 0.6% (Semenov 1965; Atlas, Venkatesan, Kaplan, Feely, Griffiths, and Morita 1983). Non-selective deposit feeders {e.g., the polychaetes Scoloplos armiger, Axiothella catenata, Ster- naspis scutata, and the mud star, Ctenodiscus crispatus) that occurred at depths between 100 and 244 m and, in the west- ern region, had a biomass of nearly 16 g/m2 (8.9% of the total benthic biomass). This trophic group was most abundant 1) west of Kodiak Island in the trough at the entrance to and within Shelikof Strait, 2) between the Semidi and Shumagin Islands, and 3) in the trough between Sanak Island and the Shumagins. Kodiak Island Region — Infauna and Epifauna. Since most of the information on benthic invertebrate fauna in the western Gulf of Alaska has come from the waters adja- cent to Kodiak Island (i.e., ADF&G 1985a; Feder andjewett 1977, 1981b; Ronholt et al. 1978; Shevtsov 1964a, b; and Semenov 1965), the fauna of this region is presented with a focus on the embayments, banks, and troughs. Furthermore, knowledge of the epifauna is more extensive for the inner shelf of the Island than for adjacent outer-shelf waters, although inner-shelf information is mainly limited to four embayments. Trawl surveys were conducted throughout Alitak and Ugak Bays (Fig. 12-10) from June to August 1976, and in March 1977 (Feder andjewett 1977). A 12.2-m otter trawl was used for these surveys. In Izhut and Kiliuda Bays (Fig. 12-10), the otter trawl and a 6.1-m try net were used dur- ing surveys from April to August and during November 1978, as well as during March 1979 (Feder andjewett 1981b). Infaunal sampling was not conducted in these four bays. However, indirect information about the infauna was obtained from the stomach contents of some benthic preda- tors (Feder andjewett 1981b; Jewett and Feder 1982, 1983). Alitak Bay. Alitak Bay, located at the southern end of Kodiak Island (Fig. 12-10), is the largest of the four bays that was sampled. The distance from the mouth to the head of the Bay is nearly 55 km, and the bathymetry gradually deep- 374 Biological Resources ens from 30 m at the entrance to 175 m in the innermost region. Approximately 1.9 km2 of the bottom was trawled, with near-equal allocation at depths of less than 50 m, 50 to 100 m, and greater than 100 meters. A variety of substrate types yielded diverse assemblages of epifauna. Most of the species encountered were predator/scavengers, although low numbers of suspension feeders such as Ptilosarcus gur- neyi, Balanus spp., and Cucumaria sp. occurred throughout the Bay. Taxonomic analysis delineated 10 epifaunal phyla with 60 genera and 79 species. Two groups — Arthropoda (Crust- acea) and Mollusca — dominated species representation, accounting for 34 and 22 species, respectively. The epi- faunal biomass for all periods was 6.2 g/m2 (Table 12-20), with the lowest biomass occurring in August (3.2 g/m2) and the highest biomass occurring in March (10.6 g/m2). Five shrimp and two crab species accounted for 94.3% of the biomass (Table 12-20). Pink shrimp dominated the shrimps, yielding nearly 13% of the total biomass and aver- aging 9.9 kg/km. Abundant pink shrimp catches were obtained duringjune, July, and August from the middle and outer portions of the Bay. Although pink shrimp were not carrying eggs duringjune andjuly, in August aqua-colored eggs were either visible through the cephalothorax or were attached to the abdominal appendages. By the following March, eyes were visible in the developing embryos. Crangonid shrimps and other pandalid shrimps displayed similar timing for egg maturation. King and Tanner crabs together accounted for nearly 75% of the biomass from Alitak Bay, with similar total weights for each species (Table 12-20). The king crab catch was 2.2 g/m2, or 27.3 kg/km. Throughout the sampling period, king crab occurred mainly in the outer portion of the Bay and consisted primarily of egg-bearing females and juveniles of both sexes. Ovigerous king crab were collected in the four sampling periods, and concentrations were so great in the outer Bay in March 1977 that sampling had to be discontinued at seven stations to avoid damaging the crab. The female-to-male ratio of mature king crab in the outer Bay was 7.4 to 1 for all periods. Adult red king crab typically migrate into shallow waters to spawn from April through June. After they breed, they gradually migrate back to deeper water (Wallace, Pertuit, and Hvatum 1949; Powell 1964). The inshore waters of the Kodiak Island Archipelago provide a suitable environment for their molting, breeding, and feeding activities (Jewett and Powell 1981; Jewett and Feder 1982), although king crab are also known to breed on offshore banks (McMullen 1967a, b). Adult king crab were nearly absent from trawl catches on the Kodiak shelf in March 1978, and their absence presumably reflects their migration to shallow water for molting and mating. Alitak Bay has traditionally been a major king crab mat- ing area (Gray and Powell 1966; Kingsbury and James 1971), and until recently, the outer Bay and adjacent waters have produced substantial commercial quantities (ADF&G 1980). Red king crab has been commercially harvested from the Kodiak Island area since 1960, and has dominated the com- mercial fisheries there for many of those years. The average catch for the years 1960 through 1983 was 1.1 x 104 mt, or 2.9 x 106 crab (ADF&G 1985a). The 1981-1982 harvest of 1.1 x 104 mt fell to 4.0 x \

100 m) extending —11 km into the Bay. The substrate of the trough is mainly composed of fine mud, with a sublayer of anoxic mud in the deeper regions of the outer bay. Mixed substrates prevail at shallower depths. The trawl surveys of 1978-1979 covered 0.8 km2 of the bottom of Izhut Bay. Because a small (6.1 m) try net was used most of the time, the shallower depths were sampled most intensively (i.e., 67% at < 50 m, 25% at 50-100 m, and 7% at >100 m). The southeast portion of the Bay, near the entrance, was given the greatest attention. The overall epi- faunal biomass was 3.8 g/m2 (Table 12-22). Notable findings here were the presence of relatively few king crab and the abundance of sunflower sea stars. Important species, in decreasing order of biomass, were (Table 12-22): • Tanner crab (Chionoecetes bairdi) • pink shrimp (Pandalus borealis) • sunflower sea star (Pycnopodia helianthoides) • Dungeness crab (Cancer magister) • red king crab (Paralithodes camtschatica). Dominant infaunal prey taken by king crab at 180 m in outer Izhut Bay duringjune andjuly 1978 were the bivalves Nuculana fossa (deposit feeder), Clinocardium ciliatum, and Axinopsida serrkata (suspension feeders), and brittle stars (browser/predator/deposit feeders) (Table 12-21). The mixed feeding habits of these prey organisms suggest that the bottom of Izhut Bay is not a strictly depositional environ- ment— even though the depth and the substrate suggest that it should be. The dominant prey taken by king crab from Izhut Bay in June andjuly 1978 were fishes — a prey of opportunity. This presumably resulted from intense surface feeding by sooty shearwaters, black-legged kittiwakes, and Steller sea lions, all of which were feeding on schooling fishes such as capelin (Mallotus villosus) and sand lance (Ammodytes hexapterus). These fishes may have fallen to the bottom after they were either injured or regurgitated by predators, and could then have been eaten by the crab. Izhut Bay typically yields only small landings of commer- cially important shellfishes. Recent Tanner and Dungeness crab harvests were each less than 0.5% of the overall Kodiak district harvest (ADF&G 1985a). The Subtidal Benthos 377 The infaunal species consumed bv Tanner crab in outer I/but Bay consisted primarily of polvcbaetes and bivalves, including Nucula tenuis, Axinopsida spp., and Macoma spp. Other important prev were pandalid shrimps, juvenile Tan- ner crab, and fishes. No feeding data are available for Dungeness crab for I/but Bay. However, feeding habits are presumably similar to those observed for this crab in lower (look Inlet (Feder and Paul 1980). The sunflower sea star's food reflected the dynamic environment of the shallower depths. Dominant items included predator)' snails (Oenopota sp., Solariella sp., Mitrella gouldi, and Natica clausa), bivalves (Nuculana fossa, Psephidia lordi, Spisula polynyma, Clinocardium ciliatum, and Mya spp.), and barnacles (Balanus spp.). Port lock Bank. Although little is known of the epifauna of Portlock Bank, the dynamic character of the physical environment there indicates that suspension feeders and predator/scavengers should be dominant. An exploratory king crab trawl survey on Portlock Bank in the spring of 1966 revealed a king crab spawning ground on a substrate composed predominantly of rock and shell material (McMullen 1967b). In 1967, the ADF&G conducted an exploratory scallop survey covering most of Portlock Bank (P. Jackson, ADF&G, pers. comm.). Observations revealed that the southwestern portion of the Bank contained the greatest total biomass as well as the greatest epifauna species diversity. Common representatives were sea pens, king crab, scallops, sea cucumbers, and brittle stars. Kelp fragments (Nereocystis) were also common. Since the late 1960s, both scallops and king crab have been commercially harvested from the western portion of Portlock Bank (Ronholt et al. 1978; Science Applications, Inc. 1980). In 1978, a trawl survey (Feder andjewett 1981b) of a sandy station in the western edge of Portlock Bank revealed that the fauna was dominated by the sand dollar Echinarachnius parma, the sea pen Ptilosarcus gnrneyi, and to a lesser extent by king crab (Table 12-23). The most abundant infaunal orga- nisms collected by dredge from the same location were a mixture of deposit- and suspension-feeding organisms that included tube-dwelling amphipods, E. parma, a brittle star, and several clam species (Table 12-24). Grab sampling (Semenov 1965) demonstrated that both sessile and mobile suspension feeders such as sponges, bivalves (Glycymeridae, Astartidae, and Veneridae), barnacles, brachiopods, and E. parma were more common than deposit feeders on Portlock Bank. Furthermore, the biomass of sessile suspension feeders (mean of 600 g/m2) was about 12 times greater than the biomass of browsers and selective deposit feeders (mean of 48 g/m-) (Semenov 1965). The fact that both deposit and suspension feeders were present at the same dredge stations underscores the patchy distribution of faunal types. Echinarachnius parma is occasionally taken as food bv king crab (Jewett and Feder 1982). Crab that have recently preyed intensively on sand dollars often displayed external evi- dence of this feeding in the form of an obvious green stain along the crushing margin of the chelipeds. Subsequent examination of crab stomachs and gut contents have linked the green chelae to sand dollars with green tests. The suspension-feeding sea pen, P.gurneyi, typically resi- ded in sandy areas at depths between 10 and 100 m, where light-to-moderate currents prevail. North Albatross Bank. North Albatross Bank is somewhat similar to Portlock Bank in terms of both substrate and fauna. However, the bottom depressions of Albatross Bank are covered by muddy sediments with an admixture of shell and pebbles. These sediments were occupied by large num- bers of browsers and selective deposit feeders such as terebellid polychaetes, bivalves (Macoma spp.), and ophiuroids (Semenov 1965). Representatives of these two trophic groups had a combined mean biomass of 74 g/m-. The most abundant infaunal organisms collected by dredge were of mixed feeding types with the brittle star [Ophiopholis aculeata) the dominant species (Table 12-24). A brittle star, presumably O. acideata, dominated the food of the king crab that were collected here. The coarse substrata on all of Albatross Bank yielded an array of suspension-feeding mac- roinvertebrates that were dominated by sessile suspension feeders (mean of 766 g/m2) (Semenov 1965). Those epifaunal species commonly encountered on this Bank during exploratory dredging for scallops in the 1960s were hydroids, scallops, sea stars, sea cucumbers, and brittle stars (P.Jackson, ADF&G, pers. comm.). The western por- tion of the bank is another offshore spawning ground for king crab (McMullen 1967a, b). Past fisheries for king crab and scallops have periodically been intense on this Bank (ADF&G 1980). Two stations where trawl surveys were con- ducted in 1978-1979 were found to be dominated by the mussel Modiolus modiolus and by a sea cucumber. These two species accounted for 67 and 22% of the biomass taken in the trawls, respectively. Middle Albatross Bank. Little information is available con- cerning the epifauna of Middle Albatross Bank. Trawl sur- veys on this bank were only conducted at two sand-shell dominated stations (1978) off the eastern shore of Kodiak Island. The pooled epifaunal biomass of these two stations was 1.8 g/m2 (Table 12-23). The sea anemone Metridium sp., king crab, and Tanner crab accounted for 45.4, 27.7, and 19.4% of the biomass, respectively. The western portion of Middle Albatross Bank has historically yielded commercial quantities of both of these crab species, although in recent years no king crab have been harvested. During the 1983-1984 fishing season, nearly 73 mt or 1.1% of all Tanner crab from the Kodiak district came from the waters of Mid- dle Albatross Bank, outside of Ugak and Kiliuda Bays, and north Sitkalidak Strait (ADF&G 1985a). The suspension-fee- ding bivalve Psephidia lordi was the most numerous infaunal species taken by dredge in this region (Table 12-24). South Albatross Bank. No benthic sampling was conducted on south Albatross Bank. Commercial Tanner crab produc- tion on south Albatross Bank was slightly less than on Mid- dle Albatross Bank (ADF&G 1985a). South Kodiak Island. The waters at the south end of Kodiak Island, west of Sitkinak Island, at depths shallower than 100 m have historically yielded high catches of king, Tanner, and Dungeness crabs. During the 1983-1984 season, nearly 42% (903 mt) of the Kodiak Dungeness crab catch came from waters surrounding the Trinity Islands (ADF&G 1984). 378 Biological Resources Table 12-23. Dominant epifauna collected by trawl from some subtidal regions of the Kodiak Shelf (H.M. Feder andS.C.Jewett, University of Alaska, unpubl. OCSEAP data on file at NODC; Feder andjewett 1981b). Area Depth (m) Total Area Stations Sampled Sampled (km2) Area BlOMASS (g/m2) Dominant Taxa Percent of Area Biomass W. Portlock Bank 64-73 N. Albatross Bank 69-93 Middle Albatross Bank 46-59 Inner Stevenson 1 44- 1 99 Trough Chiniak Trough 123-159 N.E. Kiliuda 117-143 Trough W. Kiliuda Trough 101-157 Albatross Gully 200-322 Outer Izhut Bay 163-177 Outer Marmot Bay 104-115 0.020 0.045 0.062 0.198 0.122 0.104 0.245 0.319 0.084 0.034 8.1 6.8 1.8 0.5 1.2 4.9 2.0 0.5 5.1 0.5 Echinarachnius parma 46.1 Ptilosarcus gurneyi Paralithodes camtschatica 44.2 7.3 Modiolus modiolus 67.0 Holothuroidea 21.9 Halocynthia helgendorfi igaboja Pododesmus macroschisma 4.5 3.9 Hydrozoa Metridium sp. 1.5 45.4 Paralithodes camtschatica 27.7 Chionoecetes bairdi 19.4 Ptilosarcus gurneyi Chionoecetes bairdi 1.6 92.6 Paralithodes camtschatica 4.2 Neptunea spp. Chionoecetes bairdi 1.9 58.4 Gorgonocephalus caryi Stylatula gracile Chionoecetes bairdi 34.9 6.4 84.4 Paralithodes camtschatica 12.8 Neptunea spp. Paralithodes camtschatica 0.6 54.6 Chionoecetes bairdi 34.3 Actiniidae 9.4 Gorgonocephalus caryi Dipsacaster borealis 0.6 31.4 Fusitriton oregonensis Chionoecetes bairdi 18.4 17.9 Strongylocentrotus sp. Neptunea sp. Chionoecetes bairdi 13.0 8.4 65.6 Pandalus borealis 19.0 Paralithodes camtschatica 11.0 Octopodidae Paralithodes camtschatica 47.0 39.8 Pec ten caurinus 10.1 However, only 19% (464 mt) were taken there during the 1984-1985 season (ADF&G 1985a). High biomasses of mobile suspension-feeders — such as bivalve mollusks (Pec- tinidae, Carditidae, Astartidae, Serripes sp., and Cardium sp.) and amphipods (Ampelisca spp.) — occurred between Kodiak and Chirikof Islands (Semenov 1965). Most of the latter spe- cies serve as prey for crabs elsewhere on the shelf (Feder and Paul 1980; Jewett and Feder 1982, 1983). Stevenson Trough. Five stations were trawled within inner Stevenson Trough during 1978 and 1979 (Feder andjewett 1981b). The pooled biomass was low (0.5 g/m2) when com- pared with values obtained in troughs elsewhere near Kodiak (Table 12-23) and in the NEGOA region (Table 12-11). Tanner crab dominated, accounting for nearly 93% of the biomass (Table 12-23). The most recent catch statistics show that 161 mt (2.4%) of Tanner crab were taken from this trough during the 1983-1984 season (ADF&G 1985a). Unlike shallow banks which typically are characterized as a dynamic environment, troughs typically are depositional. The gray mud substrate and the associated infauna that are found in Stevenson Trough substantiate that it is mainly a depositional environment, although the presence of sus- pension feeders suggests that particulate organic carbon must also be resuspended there (Table 12-24). Chiniak Trough. Based on the substratum and the domi- nant faunal types, bottom-water movement in Chiniak Trough appears to be more dynamic than in other troughs. Stations sampled here had substrates of fine sand and cob- ble. The presence of the biomass-dominating suspension feeders Stylatula gracile (sea pen) and Gorgonocephalus caryi (basket star) further indicates that this is a dynamic region (Table 12-23). Both suspension- and deposit-feeding infauna were numerous here (Table 12-24). The Tanner crab was another important component of the epifaunal biomass of the Chiniak Trough. The 1983-1984 Tanner crab harvest from Chiniak Trough accounted for 2.8% (183 mt) of the Kodiak Island region harvest (ADF&G 1985a). Kiliuda Trough. The benthos of the horseshoe-shaped Kiliuda Trough was examined extensively (Feder andjewett 1981b) (Tables 12-23 and 12-24). This trough has historically yielded high commercial catches of king and Tanner crabs. The northeast and western portions of Kiliuda Trough were The Subtidal Benthos 379 Table 12-24. Dominant infauna collected by pipe dredge from various subtidal regions of the Kodiak Shelf (H.M. Feder and S.C. Jewett, University of Alaska, unpubl. OCSEAP data on file at NODC; Feder and Jewett 1981b). Area Depth (m) Nl'MBER OF Samples Substrate Taxon Feeding Method" Abundance W. Portlock Bank W. Albatross Bank Middle Albatross Bank Inner Stevenson Trough Chiniak Trough N.E. Kiliuda Trough 64-73 69-84 46-57 162-199 123-159 105-132 N.W. Kiliuda Trough (Entrance of S. Sitkalidak Strait) W. Kiliuda Trough (Horse's Head) 128-145 126-157 Outer Izhut Bay 163-177 Outer Alitak Bav 54-69 sand Ampelisca spp. SF 10 Echinurachnius parma DF/SF 5 Macoma sp. DF 4 Ophiura sarsi P/B/DF 4 Astarte spp. SF 3 Cyclocardia spp. SF 3 sand-cobble Ophiopholis aculeata SF 12 Macoma obliqua DF 7 Oregonia gracilis P/S 7 Cancer oregonensis P/S 7 Golfingia vulgaris DF 3 sand-shell Psephidia lordi SF 1,800 Olivella baetica P 85 Suavodrillia kennicotti P 75 Glycinde picta DF/P 30 Gammaridae SF 18 gray mud Psephidia lordi SF 26 Nuculana fossa DF 26 Axinopsida serricata DF/SF 23 Myriochele heeri DF 20 Yoldia spp. DF 16 Macoma sp. DF 8 fine sand-cobble Axinopsida serricata DF/SF 200 Macoma sp. DF 142 Psephidia lordi SF 1 00 Nuculana fossa DF 40 Cucumaria calcigera SF 38 Nucula tenuis DF 25 gray mud with Echiurus echiurus DF 807 anoxic sublayer Axinopsida serricata DF/SF 297 Nucula tenuis DF 58 Yoldia spp. DF 45 Eudorella emarginata DF/B 27 Heteromastis filiformis DF 23 Nuculana fossa DF 20 Nephtys punctata DF/P 19 gray mud with Axinopsida serricata DF/SF 615 anoxic sublayer Pinnixa occidentalis P/S 250 Echiurus echiurus DF 35 Macoma spp. DF 25 Haploscoloplos elongatus DF 19 Yoldia spp. DF 14 gray mud Axinopsida serricata DF/SF 807 Nucula tenuis DF 238 Macoma spp. DF 176 Eudorella emarginata DF/B 139 Nuculana fossa DF 125 Myriochele heeri DF 120 Pinnixa occidentalis P/S 79 Haploscoloplos elongatus DF 55 Yoldia spp. DF 44 Echiurus echiurus DF 31 gray mud with Axinopsida serricata DF/SF 42 anoxic sublayer Nephtys punctata DF/P 13 Heteromastis filiformis DF 10 Macoma spp. DF 6 Yoldia spp. DF 4 Pinnixa occidentalis P/S 4 Psephidia lordi SF 3 gray mud Axinopsida serricata DF/SF 870 Nuculana tenuis DF 420 Yoldia spp. DF 82 Macoma spp. DF 81 Nuculana spp. DF 61 Tysanoessa inermis 40 Heteromastis filiformis DF 29 Rhvnchocoela P 22 1 DF = deposit feeder; SF = suspension feeder; B = browser; P = predator, S = scavenger. 380 Biological Resources dominated by both Tanner and king crab in 1978-1979. Sta- tistics for the 1983-1984 season show that 445 mt (21.9%) of Tanner crab were harvested in the Trough. Stocks of king crab were so low for the 1983-1984 season that the fishery was not opened (ADF&G 1985a). Prior to the collapse of the king crab fishery in 1983, the Horse's Head region of the western portion of the Trough was a big producer of king crab (ADF&G 1980). Water movement at depth within Kili- uda Trough is apparently minimal, giving way to a predomi- nance of deposit feeders such as polychaete and echiurid worms, along with bivalves (Table 12-24). The food of king crab taken from the Horse's Head region was extremely diverse. As many as 73 taxa were found in crab from here; 25 taxa were found in a single crab stomach. Deposit-feeding clams were the most important prey, although Tanner crab and fish were also important. A sediment sublayer of black anoxic mud was characteristic at the northeast portion of the trough, as well as in the vicinity of the west end of Sitkalidak Island (Fig. 12-10). King crab from the northwest Kiliuda Trough area mainly consumed the pea crab (Pinnixa occidentalis) and fishes. The pea crab was also abundant in dredge samples from the same loca- tion (Table 12-24). Albatross Gully. Albatross Gully also received com- paratively extensive trawl-survey coverage. In March 1978, eight stations were sampled in this deep region (200-322 m), yielding a combined biomass of 0.5 g/m2. Dominant epi- fauna were the sea star Dipsacaster borealis (31.4% of the bio- mass), the snail Fusitriton oregonensis (18.4%), Tanner crab (17.9%), and a maroon sea urchin Strongylocentrotus sp. (13%) (Table 12-3). A small portion of the 1983-1984 Tanner crab catch (20 mt; 0.3%) came from this deep region (ADF&G 1985a). Shelikof Strait. Exploratory trawling throughout Shelikof Strait during the summer of 1961 revealed consistently high catches (> 100 kg/h) of benthic invertebrates (Ronholt et al. 1978). Tanner crab catches typically exceeded 100 kg/h from at least 40 m to the bottom ( > 200 m). King crab catches were mainly between 0.6 and 25 kg/h at all depths. During the 1983-1984 Tanner crab season 1,524 mt (23.1% of the Kodiak district catch) of crab were harvested from the Shelikof Strait region (ADF&G 1985a). All areas of the Strait were big producers, except the area along the Alaska Penin- sula at the south end of the Strait. Shrimp-catch statistics indicate that the southern, and particularly the northeast portions of the Strait have tradi- tionally been important areas for pink shrimp (Ronholt et al. 1978; ADF&G 1985a). The 1984-1985 shrimp harvest of 212 mt from waters adjacent to the mainland was considerably lower than in previous years. The shallow waters on both sides of the Strait are also productive Dungeness crab grounds. The 1984-1985 fishing season yielded 590 mt (24.5% of the Kodiak district catch) of Dungeness crab from the Shelikof Strait district (ADF&G 1985a). In the basin west of Kodiak Island at the entrance to Shelikof Strait, the slopes were occupied by browsing and selective deposit-feeding infauna. Non-selective deposit feeders such as maldanid polychaetes were abundant west of Kodiak Island in the trough at the entrance to, and within, Shelikof Strait (Semenov 1965). Many of the infaunal taxa found on the slope and in the trough were organisms that were used as food by crabs and shrimps elsewhere in the Kodiak region (Feder andjewett 1981b; Jewett and Feder 1982, 1983). Aleutian Islands Region — Infauna and Epifauna. The bottom adjacent to the Aleutian Islands — from the Near Islands to Unimak Pass — was examined by Shevtsov (1964b); most of the data were from Near Strait and adjacent to Buldir Island, Amchitka, and Amukta Passes. The substrata in these regions are mostly bedrock outcrops and coarsely fragmented sediments infrequently interspersed with sand bottoms. The bottom fauna was dominated by sessile sus- pension feeders. The biomass of this trophic group (pri- marily sponges, barnacles — Balanus rostratus, and bryozoans) in Near Strait was 400 g/m2, representing 96% of the total biomass of the area. In Buldir Pass, the sessile suspension feeders were pri- marily sponges, sea anemones, sabellid polychaetes, bivalves (Saxicavidae, Pododesmus macroschisma), and bryozoans. Their biomass was over 1.0 kg/m2 — representing 98% of the total biomass of the area. In Amukta Pass, the biomass con- sisted mainly of sponges, hydroids, bryozoans, and ascidians and was 400 g/m2, or 96% of the total biomass of the area. Selective deposit feeders were dominant at the entrance to all of the straits, although they occurred more frequently at depths of 1,000 m where the rocky, pebbly, or gravely bot- toms were replaced by sand and muddy sand. On the Pacific side of Buldir Island, ophiuroids and eunicid and onuphid polychaetes composed up to 78% of the total biomass of 450 g/m2. On the Pacific side of Amukta Pass, the biomass of the ophiuroids Amphiura psilopora and Ophiura spp. made up 3 g/m2, or 50% of the total biomass of the area; on the Bering Sea side, the polychaete Lysippe labiata and ophiuroids made up 6 g/m2, or 47% of the total biomass. Motile suspension feeders in the straits of the Aleu- tians accounted for 27% of the total biomass of the region. Non-selective consumers were uncommon in the area, and their biomass never exceeded 1.0 g/m2. Factors Affecting Distribution and Composition of the Fauna Shelf of the Northeast Gulf of Alaska There are a number of major discontinuities in the faunal distribution within the northeast Gulf of Alaska (NEGOA). These discontinuities are related, in part, to dif- ferences in the sediment-size distribution that are con- trolled by factors such as water movement and the deposi- tion of glacially derived fine sediments (Carlson et al. 1977; Feely and Cline 1977; Hickman and Nesbitt 1980; and Molnia and Carlson 1980). The sediments that enter the NEGOA are transported westward except near Kayak Island where they are deflected to the southwest and trapped in a counterclockwise gyre west of the Island (Burbank 1977; Sharma, Wright, Burns, and Burbank 1974; Gait 1976; and Royer 1983). This results in high sedimentation rates and a high suspended-sediment load throughout much of the The Subtidal Benthos 381 shelf area west of Cape Spencer (Feely and Cline 1977; Molnia and Carlson 1980). However, on both topographic highs and shallow inshore waters on the shelf (62-130 m), scouring by strong bottom currents and frequent winter storm waves prevent sediment accumulation (Carlson et al. 1977; Molnia and Carlson 1980). This turbulence also creates ideal feeding conditions for suspension feeders such as bryozoans, brachiopods, and scallops. The westward trans- port of particulates by the Alaska Coastal Current and the Alaskan Stream also inhibits the accumulation of sediment within some regions of the shelf, including the shelf break. Sediment deposition within Hinchinbrook Entrance (especially at the mouths of Rocky and Zaikof Bays to the west of the entrance) is limited by currents of up to 50 cm/s that move in and out of Prince William Sound (T. Royer, University of Alaska, pers. comm.). The infauna of the Inshore Group (IG) (Feder and Math- eke 1980a) (Fig. 12-2), where the sediments are fine (at least 30% silt and clay) and the sedimentation rates are high, con- sisted primarily of motile deposit-feeding organisms which were widely distributed throughout the region. The fauna of the Hinchinbrook Entrance Group (HEG), where sediments were —28% sand mixed with silt and clay, was also domi- nated by deposit-feeding organisms. However, abundance, biomass, species richness, and diversity of the fauna was greater in the Hinchinbrook Entrance Group than the Inside Group (Table 12-6). This resulted from the presence and increase in abundance of many species in the HEG which were absent or rare in the IG. High epifaunal biomass values — resulting primarily from the Tanner crab — occurred in the vicinity of Hinchinbrook Entrance and to the west of Kayak Island. A frontal system formed by water moving into Prince William Sound along the eastern side of Hinchinbrook Entrance probably concentrates nutrients along the front, thereby stimulating production both in the water column and on the bottom (T. Royer, University of Alaska, pers. comm.). The high infauna] biomass of 417 g/m2 in the HEG (Feder and Matheke 1980a) represented a food resource capable of sup- porting the large numbers of Tanner crab found there. The clockwise gyre west of Kayak Island (Gait 1976; Royer 1983), extends vertically from the surface to the bottom. When the gyre is coupled with nutrients supplied by the Copper River, the productivity of the area is presumably enhanced. Greater numbers of sessile and suspension-feeding infauna] organisms occurred as the sediment changed from the silt and clay found in the IG to the sand and gravel mixed with silt and clay found in the Shelf Break Group (SBG) and the Tarr Bank Group (TBG) (Feder and Matheke 1980a). The diversity and species richness of the fauna in the SBG and the TBG were the highest found in the Northeast Gulf (Table 12-6). Although there are several possible explana- tions for the increase in diversity in the SBG and the TBG areas, the most obvious one is the increase in environmental heterogeneity provided by the presence of sand and gravel. Among the common organisms found in the TBG and the SBG were brachiopods, bryozoans, and other organisms that require a solid substrate. The smaller numbers of suspension-feeding organisms found in muddy sediments (noted elsewhere by Davis 1925; Jones 1950; Sanders 1956, 1958; Thorson 1957; and McNulty, Work, and Moore 1962) may be partly responsible for the reduced diversity of the infauna of the Inshore Group. The activities of deposit-feeding organisms often make an area unsuitable for suspension feeders by creating an easily resuspended, unstable sediment-water interface which clogs the suspension feeders' gills and either buries or inhib- its the settling of their larvae (Rhoads and Young 1970). Fur- ther, unstable sediment may also exclude suspension feeders by requiring them to expend excessive energy in order to maintain contact with overlying waters (Myers 1977). Throughout much of the NEGOA shelf, the poorly consolidated fine deposits are easily resuspended (Feely and Cline 1977), and this condition tends to exclude suspen- sion-feeding organisms (Rhoads and Young 1970; Rhoads 1974). Jumars and Fauchald (1977) postulated that sessile species may also be excluded from regions with disturbed sedi- ments or high sedimentation rates. They suggest that both burial and the rapid alteration of the local sediment charac- teristics give an advantage to motile individuals. They fur- ther suggest that the relative abundance of sessile organisms would decrease as the flux of organic material to the sub- strate decreased. They also state that in areas with a limited food supply, "the foraging radius required for adequate nutrition exceeds the reach of most sessile individuals." Since much of the sediment deposited in the NEGOA is of glacial origin, it might be expected that the sediments would be low in organic carbon. For example, the relatively low carbon values in the outwash deltaic complex formed by glacier streams in Port Valdez indicate that glacially derived sediments contain low concentrations of organic carbon (Sharma and Burbank 1973). Thus, there is a reduced abun- dance of sessile organisms in those NEGOA areas that have a high rate of deposition of glacially derived sediments (e.g., the Inshore Group of Feder and Matheke 1980a). This may be due, in part, to the relatively low organic carbon values in the sediment. Port Valdez The only identifiable difference in the environmental conditions between the deep basin in eastern and western Port Valdez appears to be an increased sediment flux to the bottom in the eastern region (Feder and Matheke 1980b; Feder et al. 1983). The geographical boundary between the eastern and western station groups (Fig. 12-4) closely coin- cides with significant differences in sediment flux to the bot- tom on either side of that boundary (Feder and Matheke 1980b). Throughout most of Port Valdez, sedimentation rates are relatively high, resulting in poorly consolidated, easily resuspended fine sediments (Sharma and Burbank 1973). As suggested previously for NEGOA, these conditions tend to exclude suspension-feeding organisms. Areas adjacent to stream or river outflows and within the Valdez Narrows were the onlv ones in which more than 20% of the fauna was composed of suspension feeders. Axinopsida serricata, a small suspension-feeding bivalve adapted to muddy environments, accounted for most of the suspen- sion-feeding organisms in the former regions. The Narrows 382 Biological Resources are subject to relatively high current speeds, conditions con- ducive to suspension feeding. The sporadic presence of large numbers of juvenile Tan- ner crab coupled with a relative scarcity of adults indicates that food resources are insufficient to support older indi- viduals. Studies of both the infauna and the food habits of Tanner crab within Port Valdez suggest that prey — such as large polychaetes, clams, hermit crabs, and barnacles nor- mally available to adult crab elsewhere in Alaskan waters (Paul, Feder, and Jewett 1979;Jewett and Feder 1983) — are not readily available to them here. Thus, although juvenile crab have sufficient small prey available to them (e.g., small polychaetes), they must either migrate out of the Port as they become larger, or fail to survive. Other Fjords and Bays of Prince William Sound The benthos of Port Etches (Fig. 12-3) exists in a deposi- tional environment. This is a result of the heavy sediment load from the Copper River that is carried into Hinchinbrook Entrance by the Alaska Coastal Current, and subsequently deflected into the Port. The depositional nature of the Port is reflected by the presence of a mud bot- tom dominated by deposit-feeding infaunal species (Hoberg 1986). The relatively high abundance and biomass values recorded for suspension-feeding species at the entrances to Rocky and Zaikof Bays (Feder and Hoberg 1981) (Fig. 12-3) suggest a dynamic environment in which detrital material and zooplankters remain in suspension within the water col- umn. A current that flows southward on the western side of Hinchinbrook Entrance across the entrances to the two Bays (T. Royer, University of Alaska, pers. comm.) presumably brings particulate organic carbon (POC) from Prince William Sound into Hinchinbrook Entrance. This current also provides the turbulence required to keep POC sus- pended in the water column where it would be available for suspension feeders. The current also deflects the sedi- ment-laden water away from the bay entrances. The heads of bays on the eastern side of Prince William Sound (Fig. 12-3) are characterized by mud bottoms enriched by terrestrial and marine detrital materials. All the inner bays examined were characterized by deposit-feeding infauna (Feder and Paul 1977). However, the mouths of these bays are more dynamic, and the benthos was always dominated by suspension-feeding species. Fjords on the western side of the Sound uniformly demonstrated low infaunal abundance and biomass values within the sill, but showed an increase in these values for the benthic fauna in the more dynamic environment outside the sill. In the Port Nellie Juan area of western Prince William Sound (Fig. 12-3), three contiguous fjords appear to be in separate phases of glacial retreat (Hoskin 1977). Derickson Bay is dominated by icebergs that are calved from the tide- water Nellie Juan Glacier. Blue Fjord is influenced both by meltwater and by the sediment that is derived from the ter- restrial Ultramarine Glacier. In contrast, McClure Bay is no longer influenced by glacial processes and has clear water. The bottom fauna varied in these three fjords, reflecting dif- fering sedimentation rates in each area. Biomass was highest in the glacier-influenced Derickson Bay, but suspension feeders were uncommon. Biomass was lowest in glacier-free McClure Bay, but suspension feeders were more common. Resurrection Bay The fine sediments inside the sill of Resurrection Bay are similar to those described for Port Valdez in Prince William Sound. (Both of these bodies of water are turbid outwash fjords; Sharma and Burbank 1973; Heggie et al. 1977.) Depos- it-feeding species dominate the infauna in both fjords, and suspension feeders are uncommon (Feder et al. 1979; Feder and Matheke 1980b). The movement of zooplankton into the fjord may be enhanced by the Bay's proximity to the open Gulf and the presence of its deep sill (R.T. Cooney, University of Alaska, pers. comm.). The continued flux to the bottom of organic carbon, derived from entrained zoo- plankters and detritus from the shore and local streams, pre- sumably enriches the bottom. The presence of both an abundant epibenthic fauna on rocks and boulders within Thumb Cove and relatively large numbers of large deposit- feeders throughout Resurrection Bay suggest that this fjord is more productive than Port Valdez. However, the reduced number of benthic taxa behind Callisto Head, an area directly affected by the turbid waters derived from Bear Glacier, is similar to observations made within the turbid waters at the heads of Port Valdez and Aialik Bay (Carpenter 1983). Aialik Bay The characteristics of the sediment and the composition of benthic organisms near Aialik Glacier (a tide- water-glacier fjord; Fig. 12-6) demonstrate the effects of the high sediment load that comes from glacial meltwater (Car- penter 1983). Both the high sedimentation rate (Post 1980) and the low primary productivity (Goering, Shiels, and Pat- ton 1973) associated with glacial sediment plumes are pre- sumably responsible for the low nitrogen and organic car- bon content of the sediment in fjords. The low organic content of the sediment near Aialik Glacier (Carpenter 1983) appeared to be one of the limiting factors for infaunal organisms. However, a few taxa were common close to the glacier. These taxa included: 1) the polychaetes Melinna cristata and Nephtys punctata and 2) the bivalve mollusks Axinopsida viridis and Nuculana sp. Although the number of taxa and the abundance of infaunal organisms tend to be reduced in turbid outwash fjords as compared with tidewater-glacier fjords, many of the same taxa occur in both, as in Blue Fjord and Derickson Bay (Hoskin 1977), Resurrection Bay (Feder et al. 1979), and Port Valdez (Feder et al. 1983). The biomass of the infaunal benthic organisms in Aialik Bay was higher than the bio- mass in turbid-outwash fjords (Hoskin 1977; Feder et al. 1983), but it was only one tenth of the benthic biomass observed either on the NEGOA shelf (Feder and Matheke 1980a) or in Cook Inlet (Feder, Paul, Hoberg, and Jewett 1981). The abundance and the diversity of benthic organisms were higher immediately behind the sill than outside. This The Subtidal Benthos 383 suggests that conditions were more favorable and stable inside and close to the sill than in other regions of the inner fjord. Since most of the suspended sediment load is depos- ited near the glacier (Post 1980), the stress on benthic orga- nisms resulting from high sedimentation rates is reduced near the sill. Further, the bottom directly behind the sill is a relatively stable environment that undergoes deepwater renewal at least once a year (Muench and Heggie 1978), and probably receives both organic debris and zooplanktonic organisms with the incoming water at flood tide. Terrestrial debris probably also accumulates in the deep basin behind the sill. Pearson (1975) suggests that even a moderate increase in the flux of organic carbon to the bottom will result in greater numbers of benthic organisms. Both the increased abundance and the diversity of the benthic orga- nisms in the deep, stable basin adjacent to the sill within Aialik Bay presumably result from an accumulation of organic material there. Lower Cook Inlet The distribution of the infauna and epifauna within lower Cook Inlet (Fig. 12-7) generally reflects the current patterns as well as the type of bottom sediment present. The dynamics of the Inlet's benthic system is far more complex than that observed for the outer Gulf shelf, but the limited infauna] sampling within the Inlet makes it difficult to assess benthic relationships there. There is a a large clockwise gyre in the western half of outer Kachemak Bay and a smaller counterclockwise gyre in the eastern half of the Bay (Knull and Williamson 1969; Bur- bank 1977). Knull and Williamson (1969) estimated a flush- ing time for Kachemak Bay of 27 days. The relatively long residence time of water in Kachemak Bay may be a control- ling factor in the development of the extended phy- toplankton blooms (7.8 g C/m2 for May-August) in the Bay. The prolonged period of primary productivity here is unlike most North Pacific areas where phytoplankton pro- duction is characterized by a short spring bloom followed by nutrient-limited summer production. The total amount of carbon contributed to the bottom over the period of May to August was 60 g C/m2 in Kachemak Bay and 17 g C/m2 in the central Inlet (Larrance and Chester 1979). Although phytoplankton production was reduced in Kamishak Bay, a flux of 40 g C/m2 of organic material to the bottom of this Bay was reported for the same period (Larrance and Chester 1979). Allochthonous carbon derived from both algal and terrestrial detrital materials also contributes to the total carbon input to the bottom of both bays and the entrance to the Inlet. The contribution of benthic marine algae to detrital reserves is highest in Kachemak Bay. A greater proportion of detrital material that accumulates on the bottom in Kamishak Bay is proba- bly terrigenous in origin (Lees and Driskell 1981). The infauna of Station Group 1 (Feder, Paul, Hoberg, and Jewett 1981) (Fig. 12-7) typically occurred in sandy silt, in gravelly mud, or in gravelly-muddy sand (Bouma and Hampton 1976; Hampton et al., Ch. 5, this volume). Kamishak and Kachemak Bays, and the Stevenson Entrance region, are described as areas of sediment accumulation. The highest levels of total organic carbon, lipid concentra- tions, and microbial activity in the sediment of the Inlet are reported here (Chester and Larrance 1981; Atlas et al. 1983; and Atlas and Griffiths, Ch. 8, this volume). Most of the bot- tom occupied by Station Group 1 is within the area identi- fied by these investigators as an enriched depositional environment. The fauna of this group consisted primarily of deposit feeders (58.4%), presumably responding to high levels of organic carbon within the sediment. Suspension feeders represented only 19.3% of the organisms present. The bottom within the area of Station Group 2 (Feder, Paul, Hoberg, andjewett 1981) (Fig. 12-7) is subject to strong currents, and the sediment consists of sand, silty sand, and sandy gravel. The infauna of this station group consisted of a higher percentage of suspension feeders and a lower per- centage of deposit feeders (38.3%). Water passing through Kachemak Bay contains high levels of POC derived from a variety of sources, including the high phytoplankton pro- duction, streams, estuaries, tidal flats, and algae on rocky shores (Lees and Driskell 1981; Chester and Larrance 1981). These organically rich waters move rapidly across the north- ern part of Kachemak Bay where they are entrained by the large gyre at the mouth — making POC available to benthic suspension feeders. Both the high abundance and biomass of suspension-feeding clams (Tellina nuculoides and Glycymeris subobsoleta), and sand dollar (Echinarachnhis parrna) within the Group 2 area reflects the abundance of a rich food source in the waters over the bottom (Table 12-13). The rich, rocky epifaunal assemblages on the bottom of the east- ern region of the Inlet north of Kachemak Bay (Feder, Paul, Hoberg, andjewett 1981; Feder and Paul 1981) apparently reflect the northward movement of this water mass along the coast (Muench et al. 1978). Western Gulf of Alaska and the Aleutians The shelf of the western-region of the Gulf (including the Kodiak region) and the area near the Aleutian passes are characterized by a benthos that is dominated by filter-feed- ing organisms (Semenov 1965). This dominance results from favorable bottom relief and from storm-induced vertical mixing that prevent sediment accumulation. Particulate organic carbon remains suspended in the water column in this turbulent region, making it available for the abundant suspension-feeding fauna. The gravelly and rocky habitats that serve as attachment sites for these animals are charac- teristic of the area. Although there is relatively little sedi- mentation in the western Gulf, fine sediment, with associ- ated carbon, accumulates in troughs and canyons along the shelf margin. Non-selective deposit feeders occur in higher numbers at these sites. The presence of commercially important shellfishes and bottomfishes in some troughs reflects the relative abundance of food benthos in these areas. Discussion The shelf of the Gulf of Alaska is a complex and dynamic geologic environment where each major region is influ- enced by a unique set of variables (see Hampton et al., Ch. 5, 384 Biological Resources this volume). Nevertheless, the shelf can be divided into three broad areas (eastern, north-central, and western) based on: 1) bottom topography, 2) sediment characteristics, 3) the amount of available organic carbon, and 4) trophic composition of the bottom fauna (Semenov 1965). A sum- mary of these and other characterizing features of the shelf regions is included in Table 12-25. The eastern area, extending south of Cape Spencer, is characterized by strong tidal currents and a low organic con- tent in the sediment (Semenov 1965). The outer shelf of this area is dominated by deposit-feeding infauna. The mean biomass is 23 g/m2 (Table 12-2), apparently reflecting a reduced carbon flux to the bottom. The northcentral area (NEGOA) receives large quantities of fine sediment from both glaciers and rivers. These sediments cover the bottom and obliterate most of the differences between the sediment of the troughs and banks. Sediments are also muddy on both the seaward edge of the shelf and the upper portion of the slope of the NEGOA. This area has two particular charac- teristics: 1) low-water mobility with reduced particulate organic carbon (POC) in the water column, and 2) a rela- tively high organic carbon content within the sediment (Semenov 1965). Deposit feeders dominate the infauna here. An increase in both the abundance and the biomass of sus- pension-feeding macrofauna occurs on Tarr and Yakutat Banks. The mean biomass of the northcentral area was reported as 64 g/m2 by Semenov (1965) and as 118 g/m2 by Feder and Matheke (1980a). The western area is characterized by a series of banks cut by transverse troughs with a bottom dominated by sand, gravel, and rocky outcrops. Sediment accumulates in the depressions and the troughs. However, sediment influx into Table 12-25. Summary of the general features of regions of the Gulf of Alaska considered in this chapter. Eastern shelf Northern shelf Western Gulf Aleutian Passes Water mobility High Suspended sediment load Low Particulate organic Low carbon (POC) Terrestrial carbon input - Bottom topography Variable Substrate type Organic content of sediment Infaunal biomass (g/m2) (van Veen grab) Mobile epifaunal biomass (g/m2) (trawl) Total benthic production (microflora, meiofauna, macrofauna) (g C/m2y) Macrofaunal production (infauna and epifauna) available to apex predators Dominant infaunal trophic groups Mixed Deposit feeders Low High Low Low Relatively wide shelf with several banks or grounds bisected by submarine canyons or troughs Mainly muddy except on banks I3.7d 4.7d Deposit feeders; suspension feeders on banks High Low High Low Relatively narrow shelf with slopes of marked dissection and steepness; many banks and reefs Sand, gravel, rocky outcrops; fine sediment in troughs and depressions Lowa Variable: Low to relatively Low high^ 23a x = 64a, 118b x = 180 Low Variable: low to high Variable: low to high depending on shelf depending on shelf location; 0.2-5.8c location; high in some troughs; 0.5-8. le High Low High Low Rocky bottom prevalent Sand, gravel, rock Probably low Probably low Suspension feeders; deposit feeders in troughs Suspension feeders Dominant mobile epifauna Tanner crab; occasionally Dungeness crab Commercial crabs; pandalid shrimps J Semenov (1965). b Feder and Matheke (1980a). 'This chapter, Table 12-11. *' Estimated, this chapter. « This chapter, Table 12-23. 1 This chapter, lower Cook Inlet section. k Feder and Paul (1981). h H.M. Feder (University of Alaska, unpubl. data), infaunal data only. 1 Carpenter (1983), tidewater-glacier fjord. J This chapter. Port Valdez. turbid outwash fjord. k Feder andjewett (in press). 'Hoberg(1986). The Subtidal Benthos 385 this area is low because no large rivers drain onto the shell. In the Aleutian passes, the bottom is mainly rocky. The water column over much of the relatively shallow western shelf and the Aleutian passes is generally characterized by storm-induced vertical mixing that suspends HOC; conse- quently, filter-feeding bottom fauna dominate the bottom here. Semenov (1965) reported a macrofaunal biomass of 180 g/m- for the area. In the NEGOA, relatively low macrofaunal production (2.2 g/m-y) has been estimated for the soft-bottom areas that make up a major portion of the shelf (see the Inshore Group: Fig. 12-2, Table 12-9). As suggested by Cooney (1986), the seasonal presence of large oceanic copepods (Neo- calanus cristatus, N, plumchrus, and Eucalanus bungii) on both the eastern and central shelf should channel most of the pri- mary production into a pelagic rather than a benthic food web, so that low benthic production values should be expected. Similarly, in the southeastern Bering Sea, the sea- sonal movement of oceanic copepods onto the outer shelf domain supports a pelagic food web used by squid and wall- eye pollock. (Theragra chalcogramma) (Iverson, Coachman, Cooney, English, Goering, Hunt, Macaulay, McRoy, Reeburgh, and Whitledge 1979; Cooney and Coyle 1982). Infaunal production for the latter region was calculated as only 2.8 g C/m2y, as opposed to the middle-shelf domain where reduced numbers of grazers in early spring result in a high flux of POC to the bottom and an infaunal production estimate of 28 g C/m2y (H.M. Feder, unpubl. data in Walsh and McRoy 1986). The dominant fishes of the NEGOA shelf are also pelagic species — mainly the arrowtooth flounder (Atheresthes stomias) and the walleye pollock. These two spe- cies make up over half of the total standing stock of commer- Lower Cook Inlet Fjords Bays Water mobility Suspended sediment load Particulate organic carbon (POC) Terrestrial carbon input Bottom topography Substrate type High Generally high High Low to high Relatively smooth bottom Coarse in the north grading to muddy sand to the south; bays mainly muddy Low High Relatively low Generally low Relatively smooth bottom; steep sides Muddy; gravelly adjacent to rivers Tidally flushed Intermediate Relatively low Relatively high Relatively smooth with some rock projections and gravel adjacent to streams Mud Organic content of sediment Infaunal biomass (g/m-) (van Veen grab) Mobile epifaunal biomass (g/m-)(trawl) Variable depending on location x = 74: Station Group lf; x = 283: Station Group 2 Variable: low to high depending on location; 0.1-14.58 Generally low 14-48'; 1-490) Variable; depending on fjord Probably relatively high1 May be relatively high1 6-617 Total benthic production (microflora, meiofauna, macrofauna)(g C/m2y) Macrofaunal production (infauna and epifauna) available to apex predators Dominant infaunal trophic groups Dominant mobile epifauna 2.5-10.0h Deposit feeders: Station Group 1; Increased percentage suspension feeders: Station Group 2 0.3-1.7* Deposit feeders Variable; low to high densities of crabs and shrimps Deposit feeders Tanner crab; pandalid shrimps 386 Biological Resources ciallv important invertebrates and fishes there (Ronholt et al. 1976, 1978). Although the bottom-feeding Tanner crab (Chionoecetes bairdi) constitutes 12.5% of the total standing stock of orga- nisms available to the commercial fishery for the NEGOA, the onlv areas identified as commercially productive are in shallow waters off either the Kenai Peninsula or Yakutat Bay (Ronholt et al. 1978). Tanner crab forage widely over the shelf, feeding on common small polychaetes, mollusks, and crustaceans. They were relatively abundant in the vicinity of Kayak Trough and Middle Bank where organic material and the associated deposit-feeding infauna probably accumu- late in the sediment beneath the gyre off the west end of Kayak Island (Gait 1976; Royer 1983). A relatively high macrofaunal production value (9.3 g C/m2y) is estimated for the relatively shallow Tarr Bank where the hard bottom and increased vertical mixing results in a diverse assemblage of both suspension and deposit feeders. The areas within and adjacent to the Bank were dominated by Tanner crab that were presumably taking advantage of the rich benthic fauna there. This crab was also common on Yakutat Bank. Macrofaunal production is also relatively high (4.6 g C/m2y) within Hinchinbrook Entrance (Feder and Matheke 1980a). This region is characterized by suspension-feeding species that feed on the POC sus- pended in the water column by strong tidal currents. A total production of 13.7 g C/m2y can be estimated for the benthos of the NEGOA shelf (H.M. Feder, University of Alaska, unpubl. data) (Table 12-9). This value is based on the assumption that the microfloral and meiofaunal produc- tion of 9.0 g C/m2y is double the production of the macro- fauna (Schwinghammer 1981; Parsons, Ch. 18, this volume) and that the epifaunal production is 0.24 g C/m2y (H.M. Feder and S.C. Jewett, University of Alaska, unpubl. data). Others have assumed that the macrofauna consumes most of the microorganisms in the sediment (Mills 1980; Reise 1979; and Parsons, Ch. 18, this volume), and the micro- organisms are then shunted through the macrofauna as an additional carbon source. Thus, only 4.5 g C/m2y of benthic production {i.e., macrofauna + mobile epifauna) (Table 12-9) is available to apex predators (e.g., sea stars, crabs, and bottomfishes). By using a transfer efficiency of 10% (Par- sons, Ch. 18, this volume), it is estimated that the macro- benthos requires 45 g C/m2y and the microflora/meio- benthos requires 90 g C/m2y. If it is assumed that primary production on the shelf is ~ 300 g C/m2y (Parsons, Ch. 18, this volume), then at least 160 g C/m2y could be available to the grazing community in the water column. Cooney (Ch. 10, this volume) estimates the zooplankton production on the NEGOA shelf to be up to 32 gC/m2y. If a conversion efficiency of 20% (Cooney, Ch. 10, this volume) is applied, zooplankton on the shelf would require 160 g C/ m2y of the available primary production. Thus, the benthic production values estimated for the shelf seem to be reason- able— given the calculated carbon requirement for the zoo- plankton on the NEGOA shelf. The composition of the benthic fauna in the bays and fjords of Prince William Sound reflects, in general, the sea- sonal sediment loads in the water column and the type of bottom. Thus, the fjords of the western Sound — which are impacted by glacial silts — are characterized by a depauper- ate fauna in contrast to the higher abundance and biomass found in the bays of the eastern Sound. The mobile epi- faunal components of the bays and fjords are variable, and appear to reflect both the type and the abundance of infaunal food organisms. For example, Port Etches (within Hinchinbrook Entrance) has a relatively high infaunal bio- mass and contains large numbers of the protobranch clam Nuculana fossa. This clam is a food resource for Tanner crab and the sunflower star Pycrwpodia helianthoides, as well as for several species of bottomfishes in the Port (Paul and Feder 1975; Feder and Hoberg 1981; and Paul, Feder, and Jewett 1979). In contrast, Port Valdez with its low infaunal biomass (Feder and Matheke 1980b) is unable to support large popu- lations of benthic predators such as pandalid shrimps, crabs, and demersal fishes (Feder et al. 1983). In general, the low infaunal standing stocks characteristic of most of the bays and fjords in the Sound suggest that benthic produc- tion values should also be low. However, a low but constant supply of carbon from terrestrial and marine sources gener- ally maintains small populations of deposit-feeding orga- nisms, but occasionally sustains high densities of pandalid shrimps, Tanner crab, and blue king crab (Paralithodes platypus) (Feder and Paul 1977; also see the general discus- sion on Norwegian fjords in Sargent, Hopkins, Seiring, and Youngson 1983). The high annual primary productivity of 185 g C/m2y that is estimated for the Sound and its embay- ments and fjords (Goering et al. 1973) suggests that grazing communities may dominate the water column, and that most of the energy flow occurs in pelagic food chains — as it does in Norway's Balsfjord (Sargent et al. 1983). The large populations of bottom-feeding crabs and pan- dalid shrimps in lower Cook Inlet require substantial amounts of food (Paul, Feder, and Jewett 1979; Feder, McCumby, and Paul 1980; and Rice et al. 1980). Although Kachemak Bay (on the eastern side of the Inlet) has a high rate of primary productivity, has abundant shrimp and crab larvae (English 1979), and has a high flux of POC to the bot- tom, the infaunal biomass and production estimates are rel- atively modest — 52 g/m2 and 2.5 g C/m2y (Feder, Paul, Hoberg, and Jewett 1981; H.M. Feder, University of Alaska, unpubl. data). Most of the POC flux to the bottom appears to be flushed out of the Bay by strong tidal currents and then entrained by the gyre at the entrance to the Bay (Fig. 12-7). It is beneath this gyre that the highest infaunal biomass and production values are found (400 g/m2; 6.3 g C/m2y). Crabs are common here, and they feed on the abundant juvenile clams that inhabit the sediment (Feder, Paul, Hoberg, and Jewett 1981). The highest epifaunal biomass (8.1 g/m2) within lower Cook Inlet is also reported for this area. For Kamishak Bay (in the western side of the Inlet), a four-month (spring/summer) POC flux of 40 g C/m2 has been reported for an area south of Augustine Island (Lar- rance and Chester 1979). Water moving through the Bay forms an eddy behind the Island (Burbank 1977), and the increased residence time of the primarily terrigenous POC within this eddy contributes to the high infaunal production (9.9 g C/m2y) which occurs there. Tanner and king crabs, and yellowfin sole (Limanda aspera) are common in Kamishak Bay, and feed on this highly productive infauna. The Subtidal Benthos 387 A high benthic production value (10gC/m2y) was also cal- culated for the Stevenson Entrance area. This is a region where sediment is deposited, carbon accumulates, and there is an abundant food benthos (infaunal biomass of 163 g/m2) that supports bottom-feeding organisms. This area serves as a nursery for juvenile Tanner crab (Feder and Paul 1981; Paul 1982) and supports a significant fishery for adult Tan- ner crab. Accumulations of carbon and associated food benthos in Shelikof Strait support commercially important stocks of Tanner crab as well. The calculations of benthic production in lower Cook Inlet discussed above were based on conservative productiv- ity-to-biomass (P/B) values for bivalves (0.5-0.7), a domi- nant component of the infauna. However, clam populations in lower Cook Inlet consisted mainly of young individuals as a result of the intense predation pressure on the larger, older clams (Feder, Paul, Hoberg, andjewett 1981). Conse- quently, a higher P/B value (e.g., 2.0: Robertson 1979) might be more appropriate for production calculations in the Inlet (see Robertson 1979 for discussion). Thus, by applying a P/B value of 2.0 (rather than 0.5-0.7) for all the bivalves, infaunal production values in the Inlet become 4.2 to 12.5 g C/m2y (compared with the 2.5-10 g C/m2y noted above). The highest production estimate (i.e., 12.5 g C/m2y) approaches the value obtained for the benthos of the highly productive middle shelf of the southeastern Bering Sea. In that area, there is a substantial carbon flux to the bottom due to ungrazed phytoplankton (Iverson et al. 1979; Cooney and Coyle 1982; and H.M. Feder, University of Alaska, unpubl. data). Also, by using the higher P/B value for Cook Inlet bivalves, a high value of 13.4 g C/m2y is calculated for Steven- son Entrance — the region identified as a Tanner crab nurs- ery area. The relatively high biomass (180 g/m2) reported for the western area of the Gulf is attributed to an increase in non- mobile filter feeders (62% of the total biomass; 112 g/m2) associated with the predominantly hard bottom of the region (Semenov 1965) (Table 12-2). However, the fine sedi- ments that setded in depressions on the banks and in the troughs contained deposit-feeding species, composing 15% of the total biomass (30 g/m2) of the shelf. These areas gener- ally supported large populations of Tanner, red king, and Dungeness crabs. Carbon production values for the sedi- mented regions on banks and troughs of the western area are unavailable, but are probably as high or higher than those calculated for the physically similar Hinchinbrook Entrance/Tarr Bank region of the central Gulf shelf — between 4 and 9 g C/m2y. The POC of the sediment bottom of the western Gulf has multiple origins: 1) westward transportation onto the Kodiak Shelf of zooplankton and juvenile fishes both by the Alaska Coastal Current (also known as the Kenai Current) and by the Alaskan Stream (Royer 1981, 1983; Royer et al. 1979; Cooney 1986), 2) detrital input from lower Cook Inlet that is transported primarily into Shelikof Strait, and 3) ter- rigenous and marine detritus from the coastal regions of the Alaska Peninsula and the Kodiak Archipelago. POC from these sources accumulates in the troughs on the shelf, in Shelikof Strait, and is further concentrated by eddies in the Alaska Coastal Current south of Kodiak Island. The accumulation of organic carbon on the bottom and the associated increase in deposit-feeding infauna are especially important in Kiliuda Trough (Fig. 12-10) which has historically yielded large commercial catches of red king and Tanner crabs. An enhanced sediment input and the associated carbon flux to the bottom within Shelikof Strait also result in an increase in food benthos. These factors con- tribute to the high standing stocks of commercially impor- tant crustaceans which are found there. The bays of the Alaska Peninsula and the Kodiak Archi- pelago are presumably also enriched by the POC trans- ported by the adjacent Alaska Coastal Current (Royer 1981; Cooney 1986) as well as from local marine and terrigenous sources. These bays are traditionally used by shrimps and crabs for reproduction and feeding, and the seasonally enhanced populations of these crustaceans have made many of the bays important fishing grounds (Feder andjew- ett 1981b). The relatively low infaunal standing stocks in Aialik Bay and other steep-sided tidewater-glacier fjords of the Gulf suggest that there is a reduced flux of organic carbon to the bottom to support the benthos. However, resident popula- tions of marine birds and mammals feed heavily on euphau- siids, pandalid shrimps, and mid-water fishes in most of these fjords, implying that there is high productivity in the water column. Nevertheless, the heavy sediment loads com- bined with low salinity of the near-surface waters of glaci- ated fjords in late spring and summer act to limit the vertical zone that can support primary productivity to the upper one meter (Goering et al. 1973). Cooney (Ch. 10, this volume; pers. comm.) suggests that oceanically derived zooplankton, advected from the Gulf shelf into the fjords, may represent a major carbon source that can sustain water-column con- sumer populations there. Diel vertical migration of pan- dalid shrimps (Barr 1970; Pearcy 1970; and Beardsley 1973) places them in a position to be carried over the sill by tidal currents and into the inner fjord where they accumulate (Carpenter 1983). An increased abundance and diversity of infauna behind the sill in some fjords (Hoskin 1977; Car- penter 1983) probably represents an accumulation of this advected organic material into the relatively stable basin (Muench and Heggie 1978). As discussed above, each broad area of the shelf and its contiguous embayments and fjords is characterized by a rel- atively distinctive fauna related to the local physical features and organic input. However, localized 'hot spots' — regions with enhanced benthic standing stocks — can be identified within these areas. Examples of some of these enriched benthic regions that have been discussed in this chapter include: • the Kayak Island gyre • Tarr Bank • Hinchinbrook Entrance and adjacent bays • the gyre west of Kachemak Bay • Kamishak Bay • PortlockBank • Shelikof Strait • the embayments of the Kodiak Archipelago • Kiliuda Trough. 388 Bioiocical Resources Carbon input to these enriched regions has variable origins depending on the location of the 'hot spot', but the high benthic standing stocks can usually be related to the auto- chthonous and allochthonous detrital material charac- teristic of the region. Perhaps one unifying feature of these benthically enriched areas is their proximity to the Alaska Coastal Cur- rent with its entrained POC (Royer 1981; Cooney 1986). It can be assumed that there is a continuous fallout of POC as the Alaska Coastal Current moves westward along the Gulf shelf and that any diversion of this current — whether by coastal features such as points, capes, islands, or entrances to embayments or by bottom such as banks or reefs — will cause local eddying, turbulence, or vertical mixing. This should increase the water's residence time over local areas and result in a higher POC flux to the bottom. We suggest that the Alaska Coastal Current and the physiographic and oceanographic features of the Gulf combine to concentrate POC, and offer a possible mechanism to explain why some local regions can assume importance for their large popula- tions of commercially important benthic species. Acknowledgments The cooperation of the officers and crew of the NOAA vessels Miller Freeman, Oceanographer, Discoverer, and Surveyor in the collection of much of the data discussed in this chap- ter is appreciated. The assistance of numerous Institute of Marine Science personnel on shipboard and in the labora- tory is also acknowledged. We thank the many biologists of the Alaska Department of Fish and Game and the National Marine Fisheries Service for their support and assistance on shipboard during many of the survey cruises over the past ten years. Funding support for the preparation of this chap- ter was provided both by the Minerals Management Service, Department of the Interior, through an interagency agree- ment with the National Oceanic and Atmospheric Admin- istration, Department of Commerce, as part of the Outer Continental Shelf Environmental Assessment Program, and by the Institute of Marine Science, University of Alaska, Fair- banks, Alaska. References Alaska Department of Fish and Game (ADF&G) 1976 A fish and wildlife resource inventory of the Cook Inlet-Kodiak areas. Under contract to Alaska Coastal Management Program, Divi- sion of Policy Development and Planning, Anchorage, AK. Two volumes. Alaska Department of Fish and Game (ADF&G) 1980 Westward region shellfish report to the Alaska Board of Fisheries. Division of Commercial Fisheries, Westward Regional Office, Kodiak, AK. 290 pp. Alaska Department of Fish and Game (ADF&G) 1984 Westward region shellfish report to the Alaska Board of Fisheries. Division of Commercial Fisheries, Westward Regional Office, Kodiak, AK.300pp. Alaska Department of Fish and Game (ADF&G) 1985a Westward region shellfish report to the Alaska Board of Fisheries. Division of Commercial Fisheries, Westward Regional Office, Kodiak, AK. 346 pp. Alaska Department of Fish and Game (ADF&G) 1985b Shellfish report to the Alaska Board of Fish- eries. Lower Cook Inlet management area. Report 85-4. Division of Commercial Fish- eries, Homer, AK. 56 pp. Alaska Department of Fish and Game (ADF&G) 1985c Shellfish report to the Alaska Board of Fish- eries. Prince William Sound management area. Data Report 85-2. Division of Commercial Fisheries, Homer, AK. 54 pp. Alaska Department of Fish and Game (ADF&G) 1985d Shellfish report to the Alaska Board of Fish- eries. Southeast Alaska-Yakutat management areas. Divison of Commercial Fisheries, Petersburg, AK. 102 pp. Arctic Environmental Information and Data Center (AEIDC) 1974 The Western Gulf of Alaska: A Summary of Available Knowledge. University of Alaska, Anchorage, AK. 399 pp. Alton, M.S. 1974 Bering Sea benthos as a food resource for demersal fish populations. In: Ocearwgraphy of the Bering Sea. D.W. Hood and E.J. Kelley, edi- tors. Occasional Publication No. 2, Institute of Marine Science, University of Alaska, Fair- banks, AK. pp. 257-277. The Subtidal Benthos 389 Atlas, R.M., M.I. Venkatcsan, I.R. Kaplan, R.A. Feely, R.P. Griffiths, and R.Y. Morita 1983 Distribution of hydrocarbons and microbial populations related to sediment processes in lower (look Inlet and Norton Sound, Alaska. Arctic 36:251-261. Bakus, G.J. and D.VV. Chamberlain 1975 An oceanographic and marine biological study in the Gulf of Alaska. Report submitted to Atlantic Richfield Co. 57 pp. Bakus, G.J., M. Orys, and J.D. Hendrick 1979 The marine biology and oceanography of the Anchorage region, upper Cook Inlet, Alaska. Astarte 12:13-20. Barnes, R.D. 1980 Invertebrate Zoology. Saunders College/Holt, Rinehart and Winston, Philadelphia, PA. 1089 pp. Barr, L. 1970 Diel vertical migration of Pandalus borealis in Kachemak Bay, Alaska. Journal of the Fisheries Research Board of Canada 27:669-676. Beardsley, A.J. 1973 Design and evaluation of a sampler for measur- ing the near-bottom vertical distribution of pink shrimp, Pandalus jordani. Fishery Bulletin (U.S.) 71:243-253. Bouma, A.H. and M.A. Hampton 1976 Preliminary report on the surface and shallow subsurface geology of lower Cook Inlet and Kodiak Shelf, Alaska. Open-File Report 76-695, U.S. Geological Survey, Menlo Park, CA. 36 pp. Burbank, D.C. 1977 Circulation studies in Kachemak Bay and lower Cook Inlet, Alaska. Alaska Department of Fish and Game, Anchorage, AK. 207 pp. Carlson, P.R., B.F. Molnia, S.C. Kittelson, and J.C. Hampson,Jr. 1977 Distribution of bottom sediment on the conti- nental shelf, northern Gulf of Alaska. U.S. Geo- logical Survev Miscellaneous Field Studies Map MF-876. 13 pp., 2 maps. Carpenter, T.A. 1983 Pandalid shrimps in a tidewater-glacier fjord, Aialik Bay, Alaska. M.S. Thesis. University of Alaska, Fairbanks, AK. 122 pp. Chester, A.J. and J.D. Larrance 1981 Composition and vertical flux of organic mat- ter in a large Alaskan estuary. Estuaries 4:42-52. Colonell, J.M., editor 1980 Port Valdez, Alaska: Environmental Studies 1976-1979. Occasional Publication No. :>. Institute of Marine Science, University of Alaska, Fairbanks, AK. 373 pp. Cooney, R.T. 1972 A review of the biological oceanography of the northeast Pacific Ocean. In: A review of the oceanography and renewable resources of the northern Gulf of Alaska. D.H. Rosenberg, edi- tor. Sea Grant Report 73-3, IMS Report R72-23, Institute of Marine Science, University of Alaska, Fairbanks, AK. pp. 57-74. Cooney, R.T. 1986 The seasonal occurrence of Neocalanus rristalus, Neocalanus plurnchrns, and Eucalanus hungii over the shelf of the northern Gulf of Alaska. Conti- nental Shelf Research 5:541-553. Cooney, R.T. and K.O. Coyle 1982 Trophic implications of cross-shelf copepod distributions in the southeastern Bering Sea. Marine Biology (Berlin) 70:187-96. Crow,J.H. 1977 Food habits of shrimp in Kachemak Bay, Alaska. In: Environmental Studies of Kachemak Bay and Lower Cook Inlet, Vol. 6. L.L. Trasky, L.B. Flagg, and D.C. Burbank, editors. Alaska Department of Fish and Game, Anchorage, AK. pp. 1-32. Dames and Moore 1978 Lower Cook Inlet biological studies, Lease Block Clearing Area 1. Final report to Mar- athon Oil Company. 31 pp. Dames and Moore 1981 Homer Spit coastal development program: bio- logical investigations of Homer Spit coastal area. Report to Kenai Peninsula Borough, City ofHomer,AK.123pp. Dames and Moore 1984 Environmenal monitoring study, Homer small boat harbor expansion, winter 1984. Report to the City of Homer, AK. 53 pp. Davis, F.M. 1925 Quantitative studies on the fauna of the sea bottom No. 2 — Results of the Investigations in the southern North Sea, 1921-24. Great Britain Ministry of Agriculture and Fisheries. Fishery Investigations Series II, Vol. 8, No. 4. 50 pp. 390 Biological Resources Driskell, W.B. and D. Lees 1977 Benthic reconnaissance of Kachemak Bay, Alaska. In: Environmental Studies of Kachemak Bay and Lower Cook Inlet, Vol. 7. L.L. Trasky, L.B. Flagg, and D.C. Burbank, editors. Alaska Department of Fish and Game, Anchorage, AK. pp. 1-102. English, T.S. 1979 Lower Cook Inlet meroplankton. Research Unit 424. Unpublished Outer Continental Shelf Environmental Assessment Program annual report. University of Washington, Seattle, WA. 22 pp. Feder, H.M. 1977 Summarization of existing literature and unpublished data on the distribution, abun- dance, and productivity of benthic organisms of the Gulf of Alaska and Bering and Chukchi Seas. Bibliography of northern marine waters with emphasis on benthic organisms (indexed by author and title keywords). Research Unit 282. Outer Continental Shelf Environmental Assessment Program Alaska Office, Anchorage, AK. Microfiche only. Feder, H.M. 1978 Distribution, abundance, community struc- ture, and trophic relationships of the near- shore benthos of the Kodiak Shelf, Cook Inlet, Northeast Gulf of Alaska and the Bering Sea. Environmental Assessment of the Alaskan Continen- tal Shelf Annual Reports of Priwipal Investigators 4:416-730. Feder, H.M. 1979 Subtidal benthos. In: Continuing environmen- tal studies of Port Valdez, Alaska: 1976-1979. Final report on TAPS/41 contract. J. M. Colo- nell, editor. Institute of Marine Science, Uni- versity of Alaska, Fairbanks, AK. pp. 1-222 Feder, H.M. and M.K. Hoberg 1981 The epifauna of three bays (Port Etches, Zaikof Bay, and Rocky Bay) in Prince William Sound, Alaska, with notes on feeding biology. Report R81-2, Institute of Marine Science, University of Alaska, Fairbanks, AK. 39 pp. Feder, H.M. and S.C. Jewett 1977 The distribution, abundance, biomass and diversity of the epifauna of two bays (Alitak and Ugak) of Kodiak Island, Alaska. Report R77-3, Institute of Marine Science, University of Alaska, Fairbanks, AK. 74 pp. Feder, H.M. and S.C. Jewett 1981a Feeding interactions in the eastern Bering Sea with emphasis on the benthos. In: The Eastern Bering Sea Shelf Oceanography and Resources, Vol. 2. D.W. Hood andJA. Calder, editors. Office of Marine Pollution Assessment, NOAA. Dis- tributed by the University of Washington Press, Seattle, WA. pp. 1229-1261. Feder, H.M. and S.C. Jewett 1981b Distribution, abundance, community structure and trophic relationships of the nearshore epi- benthos of the Kodiak Shelf. Report 81-1, Institute of Marine Science, University of Alaska, Fairbanks, AK. 216 pp. Feder, H.M. and S.C. Jewett In press The subtidal benthos. In: Environmental Manage- ment of Port Valdez, Alaska: Scientific Basis and Practical Results. D.G. Shaw and MJ. Hameedi, editors. Springer- Verlag, New York, NY. Feder, H.M. and G.E.M. Matheke 1980a Distribution, abundance, community struc- ture, and trophic relationships of the benthic infauna of the Northeast Gulf of Alaska. Report R78-8, Institute of Marine Science, University of Alaska, Fairbanks, AK. 209 pp. Feder, H.M.and G.E.M. Matheke 1980b Subtidal benthos. In: Port Valdez, Alaska: Environmental Studies 1976-1979. J.W. Colonell, editor. Occasional Publication No. 5, Institute of Marine Science, University of Alaska, Fair- banks, AK. pp. 235-324. Feder, H.M. and A.J. Paul 1977 Biological cruises of the R/V Acona in Prince William Sound, Alaska, from 1970 to 1973. IMS Report R77-4, Alaska Sea Grant Report No. 77-14, University of Alaska, Fairbanks, AK. 76 pp. Feder, H.M. and A.J. Paul 1980 Food of the king crab, Paralithodes camtschatica and the Dungeness crab, Cancer magister in Cook Inlet, Alaska. Proceedings of the Shellfisheries Association 70:240-246. Feder, H.M. and A.J. Paul 1981 Distribution and abundance of some epi- benthic invertebrates of Cook Inlet, Alaska. Report R80-3, Institute of Marine Science, University of Alaska, Fairbanks, AK. 154 pp. Feder, H.M. and D.G. Shaw 1986 Environmental studies in Port Valdez, Alaska in 1985. Final report to Alyeska Pipeline Serv- ice Co. Institute of Marine Science, University of Alaska, Fairbanks, AK. 415 pp. The Subtidai Benthos 391 Feder, H.M., K. McCumby, and AJ. Paul 1980 The food of post-larval king crab, Paralithodes camtschatica, in Kachemak Bay, Alaska (Decapoda, Lithodidae). Crustaceana 39:315-318. Feder, H.M., A.J. Paul, andj. McDonald 1979 A preliminary survey of the benthos of Resur- rection Bay anil Aialik Bay, Alaska. Sea Chant Report No. 79-9, IMS Report R78-7, Institute of Marine Science, University of Alaska, Fair- banks, AK. 53 pp. Feder, H.M., T.A. Gosink, A.S. Naidu, and D.G. Shaw 1983 Environmental studies in Port Valdez, Alaska, 1980-82. Final report to Alyeska Pipeline Serv- ice Co. Institute of Marine Science, University of Alaska, Fairbanks, AK. 585 pp. Feder, H.M., K. Haflinger, M. Hoberg, and J. McDonald 1980 The infaunal invertebrates of the southeastern Bering Sea. Environmental Assessment of tfie Alas- kan Continental Shelf, Final Reports of Principal Investigators 9(Biological Studies):256-670. Feder, H.M., S.C. Jewett, S.G. McGee, and G.E.M. Matheke 1981 Distribution, abundance, community struc- ture, and trophic relationships of the benthos of the northeastern Gulf of Alaska from Yakutat Bay to Cross Sound. Research Unit 5. Final report to Outer Continental Shelf Environmental Assessment Program. Institute of Marine Science, University of Alaska, Fair- banks, AK. 197 pp. Feder, H.M., G.J. Mueller, M.H. Dick, and D.B. Hawkins 1973 Preliminary benthos survey. In: Environmental Studies of Port Valdez. D.W. Hood, W.E. Shiels, and EJ. Kelley, editors. Occasional Publication No. 3, Institute of Marine Science, University of Alaska, Fairbanks, AK. pp. 305-391. Feder, H.M., G. Mueller, G. Matheke, and S. Jewett 1976 The distribution, abundance, diversity, and productivity of benthic organisms in the Gulf of Alaska. Environmental Assessment of the Alaskan Continental Shelf Principal Investigators Reports for the Year Ending March 1976 7(fish, plankton, benthos, littoral):263-454. Feder, H.M., A.J. Paul, M.K. Hoberg, and S.C. Jewett 1981 Distribution, abundance, community structure and trophic relationships of the nearshore henthos of Cook Inlet. Environmental Assessment of the Alaskan Continental Shelf Final Reports of Principal Investigators 14(Biological Stud- ies):45-676. Feely, R. andj. Cline 1977 The distribution, composition, and transport of suspended particulate matter in the north- eastern Gulf of Alaska, southeastern Bering Shelf, and lower Cook Inlet. Research Unit 152. Environmental Assessment of the Alaskan Continen- tal Shelf Annual Reports of Principal Investigators 13:89-179. Galt,J.A. 1976 Circulation studies on the Alaska continental shelf off the Copper River. NOAA Technical Report. U.S. Government Printing Office, Washington, D.C. 36 pp. Goering, J.J., W.E. Shiels, and C.J. Patton 1973 Primary production. In: Environmental Studies of Port Valdez. D.W. Hood, W.E. Shiels, and E.J. Kelley, editors. Occasional Publication No. 3, Institute of Marine Science, University of Alaska, Fairbanks, AK. pp. 253-279. Gray, G.W., Jr. and G.C. Powell 1966 Sex ratios and distribution of spawning king crabs in Alitak Bay, Kodiak Island, Alaska (Decapoda, Anomura, Lithodidae). Crustaceana 10:303-309. Haynes, E. 1977 Summary status on the distribution of king crab and pandalid shrimp larvae in Kachemak Bay-lower Cook Inlet, Alaska, 1976. In: Environ- mental Studies of Kachemak Bay and Lower Cook Inlet, Vol. 4. L.L. Trasky, L.B. Flagg, and D.C. Burbank, editors. Alaska Department of Fish and Game, Anchorage, AK. 52 pp. Heggie, D.T., D.W. Boisseau, and D.C. Burrell 1977 Hydrography, nutrient chemistry, and primary productivity of Resurrection Bay, Alaska 1972-75. Sea Grant Report 77-9, Institute of Marine Science Report R77-2, University of Alaska, Fairbanks, AK. Ill pp. Hennick, D. 1973 Cook Inlet shellfish investigations, commercial fisheries research development act. Project No. 5-29-R, Alaska Department of Fish and Game, Juneau, AK. 21 pp. Hickman, C. and E.A. Nesbitt 1980 Holocene mollusk distribution patterns in the northern Gulf of Alaska. Quaternary deposi- tional environments of the Pacific coast. In: Pacific Coast Paleography Symposium 4. M.E. Field, editor. Society of Economic Paleontologists and Mineralogists, Los Angeles, CA. pp. 305-312. 392 Biological Resources Hitz, C.R. and W.F. Rathjen 1965 Bottom trawling surveys of the northeastern Gulf of Alaska. Commercial Fisheries Review 27(9):1-15. Hoberg, M.K. 1986 A numerical analysis of the benthic infauna of three bays in Prince William Sound, Alaska. M.A. Thesis, Humboldt State University, Areata, CA. 153 pp. Hood, D.W., W.E. Shiels, and E.J. Kelley, editors 1973 Environmental Studies of Port Valdez. Occasional Publication No. 3, Institute of Marine Science, University of Alaska, Fairbanks, AK. 495 pp. Hoskin, CM. 1977 Macrobenthos from three fjords in western Prince William Sound, Alaska. Report R77-1, Institute of Marine Science, Fairbanks, AK. 28 pp. Hyman, L.H. 1955 The Invertebrates: Echinodermata, the Coelomate Bilateria, Vol. 4. McGraw-Hill Book Co., Inc. New York, NY. 763 pp. Iverson, R.L., L.K. Coachman, R.T. Cooney, T.S. English, J.J. Goering, G.L. Hunt, Jr., M.C. Macauley, C.P. McRoy, W.S. Reeburgh, and T.E. Whitledge 1979 Ecological significance of fronts in the south- eastern Bering Sea. In: Ecological Processes in Coastal and Marine Systems. R.J. Livingston, edi- tor. Plenum Press, N.Y. pp. 437-466. Jewett, S.C. and H.M. Feder 1982 Food and feeding habits of the king crab Para- lithodes camtschatica near Kodiak Island, Alaska. Marine Biology (Berlin) 66:243-250. Jewett, S.C. and H.M. Feder 1983 Food of the Tanner crab Chionoecetes bairdi near Kodiak Island, Alaska.yowma/ of Crustacean Biol- ogy 3:196-207. Jewett, S.C. and G.C. Powell 1979 Summer food of the sculpins, Myoxocephalus spp. and Hemilepidotus jordani, near Kodiak Island, Alaska. Marine Science Communications 5:315-331. Jewett, S.C. and G.C. Powell 1981 Nearshore movement of king crab. Alaska Seas and Coasts 9(3):6-8. Jones, N.S. 1950 Marine bottom communities. Biological Review 25:283-313. Jumars, P.A. and K. Fauchald 1977 Between-community contrasts in successful polychaete feeding strategies. In: Ecology of Marine Benthos. B.C. Coull, editor. University of South Carolina Press, Columbia, S.C. pp. 1-20. Kingsbury, A.P. and K.E.James 1971 Abundance and composition of king crabs in the Alitak and Kaguyak Bay areas during April amdjune 1970. Informational Leaflet 152, Alaska Department of Fish and Game, Juneau, AK. 42 pp. Knull, J. and R. Williamson 1969 Oceanographic Survey of Kachemak Bay, Alaska. MR-F Nos. 60, 70, and 76, Bureau of Commercial Fisheries Biology Laboratory, Auke Bay, AK. Kozloff, E.N. 1973 Seashore Life of Puget Sound, the Strait of Georgia, and the San Juan Archipelago. University of Wash- ington Press, Seattle, WA. 282 pp. Kyte, M.A. 1969 A synopsis and key to the recent Ophiuroidea of Washington State and southern British Columbia.yourwz/ of the Fisheries Research Board of Canada 26:1727-1741. Larrance, J.D. and A.J. Chester 1979 Source, compositon, and flux of organic detritus in lower Cook Inlet. Outer Continental Shelf Environmental Assessment Program, Final Reports of Principal Investigators 46:1-71. Larrance, J.D., D.A. Tennant, A.J. Chester, and P.A. Ruffio 1977 Phytoplankton and primary productivity in the northeast Gulf of Alaska and lower Cook Inlet. Environmental Assessment of the Alaskan Con- tinental Shelf, Annual Reports of Principal Investiga- tors for the Year Ending March 1977 ^(Recep- tors— fish, littoral, benthos): 1-136. Lees, D. 1976 Lees, D. 1978 The epifaunal assemblage in the Phillips Petroleum lease site off Spring Point, Chinitna Bay, Alaska. Dames and Moore final report to Phillips Petroleum Company. 42 pp. Reconnaissance of the intertidal and shallow subtidal biota, lower Cook Inlet. Research Unit 417. Environmental Assessment of the Alaskan Conti- nental Shelf Final Reports of Principal Investigators 3(Biological Studies):l79-506. Lees, D.C. and W.B. Driskell 1981 Appendix IV. Investigations on shallow sub- tidal habitats and assemblages in lower Cook Inlet. In: Distribution, abundance, community structure and trophic relationships of the near- shore benthos of Cook Inlet. H.M. Feder, A.J. Paul, M.K. Hoberg, and S.C. Jewett, authors. Environmental Assessment of the Alaska Continental Shelf, Final Reports of Principal Investigators 14(Biological Studies):419-610. The Subtidal Benthos 393 McDonald, J., H.M. Feder, and M. Hobcrg 1981 Bivalve mollusks of the southeastern Bering Sea. In: The Eastern Bering Sea Shelf: Oceanography and Resources, Vol. 2. D.W. Hood and J.A. Cal- der, editors. Office of Marine Pollution Assess- ment, NOAA. Distributed by the University of Washington Press, Seattle, WA. pp. 1155-1204. Mclntyre, A.D. 1977 Effects of pollution on inshore benthos. In: Ecology of Marine Benthos. B.C. Coull, editor. The Belle W. Baruch Library in Marine Science, No. 6, University of South Carolina Press, Colum- bia, SC. pp. 301-318. McMullen,J.C. 1967a Breeding king crabs Paralithodes camtschatica located in the ocean environment. Jourrud of the Fisheries Research Board of Canada 24:2627-2628. McMullen,J.C. 1967b King crab Paralithodes camtschatica (Tilesius) off- shore breeding study on Marmot Flats, Kodiak Island, spring of 1967. Informational Leaflet 112, Alaska Department of Fish and Game, Juneau, AK. 12 pp. McNulty, J.K., R.C. Work, and H.B. Moore 1962 Some relationships between the infauna of the level bottom and the sediment in south Florida. Bulletin of Marine Science 12:322-332. Melteff, B.R., editor 1985 Proceedings of the International King Crab Sym- posium. Lowell Wakefield Symposium Series. Alaska Sea Grant Report No. 85-12, University of Alaska, Anchorage, AK. 507 pp. Mills, E.L. 1980 The structure and dynamics of shelf and slope ecosystems off the northeast coast of North America. In: Marine Benthic Dynamics. K.R. Ten- ore and B.C. Coull, editors. University of South Carolina Press, Columbia, SC. pp. 25-47. Molnia, B.F. and P.R. Carlson 1980 Quaternary sedimentary facies on the conti- nental shelf of the northeastern Gulf of Alaska. In: Quaternary Depositional Environments of the U.S. Pacific Continental Margin. M.E. Field, A.H. Bouma, and LP. Colbern, editors. Society of Economic Paleontologists and Mineralogists, Pacific Section, Bakersfield, CA. pp. 157-168. Moriarity, D.J.W. 1976 Quantitative studies on bacteria and algae in the food of the mullet Mugil cephalus L. and the prawn Metapenaeus bennettae (Racek and Dall). Journal of Experimental Marine Biology and Ecology 22:131-143. Morris, R.H., D.P. Abbott, and E.C. Haderlie 1980 Intertidal Invertebrates of California. Stanford Uni- versity Press, Stanford, CA. 665 pp. Muench, R.D. and D.T. Heggie 1978 Deep water exchange in Alaskan subarctic fjords. In: Estuarine Transport Processes. B. Kjerfve, editor. University of South Carolina Press, Columbia, SC. pp. 239-267. Muench, R.D., H.O. Mofjeld, and R.L. Charnell 1978 Oceanographic conditions in lower Cook Inlet: spring and summer 1973. Journal of Geo- physical Research 83C:5090-5098. Myers, A.C. 1977 Sediment processing in a marine subtidal sandy bottom community. II. Biological conse- quences. Journal of Marine Research 35:633-647. Patent, D.H. 1970 Life history of the basket star, Gorgonocephalus eucnemis (Mueller and Troschel) (Echinoder- mata: Ophiuroidea). Ophelia 8:145-160. Paul,J.M. 1982 Distribution of juvenile Chionoecetes bairdi in Cook Inlet. In: Proceedings of the International Symposium on the Genus Chionoecetes. Lowell Wakefield Fisheries Symposia Series. Alaska Sea Grant Report No. 82-10, University of Alaska, Fairbanks, AK. pp. 173-189. Paul, AJ. and H.M. Feder 1975 The food of the sea star Pycnopodia helianthoides (Brandt) in Prince William Sound, Alaska. Ophelia 14:15-22. Paul, AJ. andJ.M. Paul 1980 The effect of early starvation on later feeding successs of king crab zoeae. Journal of Experimen- tal Marine Biology and Ecology 44:247-251. Paul, A.J., H.M. Feder, and S.C. Jewett 1979 Food of the snow crab, Chionoecetes bairdi Rathbun 1924, from Cook Inlet, Alaska (Decapoda, Majidae). Crustaceana Supplement 5:62-68 Paul, A.J., J.M. Paul, P.A. Shoemaker, and H.M. Feder 1979 Prey concentrations and feeding response in laboratory-reared stage-one zoeae of king crab, snow crab, and pink shrimp. Transactions of the American Fisheries Society 108:440-443. Pearce, J.B. and G. Thorson 1967 The feeding and reproductive biology of the red whelk, Neptunea antiqua (L.) (Gastropoda, Prosobranchia). Ophelia 4:227-314. Pearcy, W.G. 1970 Vertical migration of the ocean shrimp. Pan- dalus jordani: a feeding and dispersal mecha- nism. Ccdifornia Fish and Game 56:125-129. 394 Biological Resources Pearson, T.H. 1971 The benthic ecology of Loch Linnhe and Loch Eil, a sea-loch system on the west coast of Scotland. III. The effect on the benthic fauna of the introduction of pulp mill effluent. Journal of Experimental Marine Biology and Ecology 6:211-233. Pearson, T.H. 1972 The effect of industrial effluent from pulp and paper mills on the marine benthic environ- ment. Proceedings of the Royal Society of London, Series B 130:469-485. Pearson, T.H. 1975 The benthic ecology of Loch Linnhe and Loch Eil, a sea-loch system on the west coast of Scotland. IV. Changes in the benthic fauna attributable to organic enrichment. Journal of Experimental Marine Biology and Ecology 20:1-41. Pearson, T.H. and R. Rosenberg 1978 Macrobenthic succession in relation to organic enrichment and pollution of the marine environment. Oceanography and Marine Biology Annual Review 16:229-311. Pearson, T.H. 1980 Macrobenthos of fjords. In: Fjord Oceanography. H J. Freeland, D.M. Farmer, and CD. Levings, editors. Plenum Press, New York, NY. pp. 569-602. Petersen, C.GJ. and P.B.Jensen 1911 Valuation of the sea. I. Animal life of the sea- bottom, its food and quantity (Quantitative studies). Report of the Danish Biological Station 20:1-81. Post, A. 1980 Preliminary bathymetry of Aialik Bay and neo- glacial changes of Aialik and Pederson glaciers, Alaska. Open-File Report 80-423, U.S. Geo- logical Survey, Tacoma, WA. Powell, G.C. 1964 Fishing mortality and movements of king crabs. Transactions of the American Fisheries Society 93:295-300. Reise, K. 1979 Moderate predation on meiofauna by the mac- robenthos of the Wadden Sea. Helgolander wissenschaftliche Meersuntersuchungen 32: 453-465. Rhoads, D.C. 1974 Organism-sediment relations on the muddy sea floor. Oceanography and Marine Biology Annual Review 12:263-300 . Rhoads, D.C. and D.K. Young 1970 The influence of deposit-feeding organisms on sediment stability and community trophic structure.yoMnW of Marine Research 28:150-178. Rice, R.L. 1980 Feeding habits of crangonid shrimps and some aspects of sediment-detrital food systems in lower Cook Inlet, Alaska. M.S. Thesis, Univer- sity of Alaska, Fairbanks, AK. 59 pp. Rice, R.L., K.I. McCumby, and H.M. Feder 1980 Food of Pandalus borealis, Pandalus hypsinotus, and Pandalus goniurus (Pandalidae, Decapoda) from lower Cook Inlet, Alaska. Proceedings of the National Shellfisheries Association 70:47-54. Robertson, A.I. 1979 The relationship between annual produc- tiombiomass ratios and lifespans for marine macrobenthos. Oecologia 38:193-202. Rogers, B.J., M.E. Wangerin, and D.E. Rogers 1980 Seasonal composition and food web rela- tionships of marine organisms in the near- shore zone of Kodiak Island - including ichthyoplankton, zooplankton, and fish. A report on the fish component of the study. FRI-UW-8017, Fisheries Research Institute, University of Washington, Seattle, WA. 109 pp. Ronholt, L.L., H.H. Shippen, and E.S. Brown 1976 An assessment of the demersal fish and inverte- brate resources of the northeastern Gulf of Alaska, Yakutat Bay to Cape Cleare, May- August 1975. U.S. Department of Commerce, National Oceanic and Atmospheric Admin- istration, National Marine Fisheries Service. Seattle, WA. 184 pp. Ronholt, L.L., H.H. Shippen, and E.S. Brown 1978 Demersal fish and shellfish resources of the Gulf of Alaska from Cape Spencer to Unimak Pass, 1948-1976: a historical review. Environmen- tal Assessment of the Alaskan Continental Shelf Final Reports of Principal Investigators 2(Biological Studies):l-955. Rosenberg, D.H., editor 1972 A review of the oceanography and renewable resources of the northern Gulf of Alaska. Alaska Sea Grant Report 73-3, Institute of Marine Science Report No. R72-23, University of Alaska, Fairbanks, AK. 690 pp. Rosenberg, R. 1973 Succession in benthic macrofauna in a Swedish fjord subsequent to the closure of a sulphite pulp mill. Oihos 24:244-258. The Subtidal Benthos 395 Rosenberg, D.H., D.V. Natarajan, and D.W. Hood 1969 Summary report. Collier Carbon and Chem- ical Corporation Studies in Cook Inlet, Alaska. Report No. 69-13, Parts I and II, November 1968-September 1969, Institute of Marine Sci- ence, University of Alaska, College, AK. 150 pp. Rosenthal, R. and D. Lees 1976 Marine plant community studies, Kachemak Bay, Alaska. Final report to Alaska Department of Fish and Game, Anchorage, AK. 288 pp. Royer, T.C. 1981 Baroclinic transport in the Gulf of Alaska. Part II. A fresh water driven coastal current. Journal of Marine Research 39:251-266. Royer, T.C. 1982 Coastal fresh water discharge in the northeast Pacific. Journal of Geophysical Research 87C:2017-2021. Royer, T.C. 1983 Observations of the Alaska Coastal Current. In: Coastal Oceanography. H. Gade, A. Edwards, and H. Svendsen, editors. NATO Conference Series IV: Marine Sciences. Plenum Press, New York, NY. pp. 9-30. Royer, T.C, D.V. Hansen, and D.J. Pashinski 1979 Coastal flow in the northern Gulf of Alaska as observed by dynamic topography and satel- lite-tracked drogued drift buoys. Journal of Phys- ical Oceanography 9:785-801. Sanders, H.L. 1956 Oceanography of Long Island Sound, 1952-1954. X. Biology of marine bottom com- munities. Bulletin of the Bingham Oceanographic Collection 15:345-414. Sanders, H.L. 1958 Benthic studies in Buzzards Bay. I. Animal-sed- iment relationships. Limnology and Oceanography 3:245-258. Sargent, J.R., C.C.E. Hopkins, J.V. Seiring, and A. Youngson 1983 Partial characterization of organic material in surface sediments from Balsfjorden, northern Norway, in relation to its origin and nutritional value for sediment-ingesting animals. Marine Biology (Berlin) 76:87-94. Schaefers, E.A., K.S. Smith, and M.R. Greenwood 1955 Bottom Fish and shellFish explorations in the Prince William Sound area, Alaska, 1954. Com- mercial Fisheries Review 17(4):6-28. Schwinghammer, P. 1981 Characteristic size distributions of integral benthic communities. Canadian Journal of Fish- eries and Aquatic Science 38:1255-1263. Science Applications, Inc. 1980 Environmental Assessment of the Alaskan Outer Continental Shelf: Kodiak Interim Syn- thesis Report - 1980. Boulder, CO. 326 pp. Semenov, U.N. 1965 Quantitative distribution of benthic fauna of the shelf and upper part of the slope in the Gulf of Alaska. In: Soviet Fisheries Investigations in the Northeast Pacific, Part IV. PA. Moiseev, editor. Israel Program for Scientific Translations. 1968. pp. 37-69. Sharma, G.D. and D.C. Burbank 1973 Geological oceanography. In: Environmental Studies of Port Valdez. D.W. Hood, W.E. Shiels, and EJ. Kelley, editors. Occasional Publication No. 3, Institute of Marine Science, University of Alaska, Fairbanks, AK. pp. 15-100. Sharma, G.D., F.F. Wright, J.J. Burns, and D.C. Burbank 1974 Sea surface circulation, sediment transport, and marine mammal distribution, Alaska con- tinental shelf. Report prepared for the National Aeronautics and Space Administra- tion, Goddard Space Flight Center, Greenbelt, MD. Shevtsov, V.V. 1964a Quantitative distribution and trophic groups of benthos in the Gulf of Alaska. In: Soviet Fish- eries Investigations in the Northeast Pacific, Part II. P.A. Moiseev, editor. Israel Program for Scien- tific Translations. 1968. pp. 109-114. Shevtsov, V.V. 1964b Quantitative distribution and trophic groups of benthos in the Gulf of Alaska. In: Soviet Fish- eries Investigations in the Northeast Pacific, Part III. P.A. Moiseev, editor. Israel Program for Scien- tific Translations. 1968. pp. 150-166. Smith, R.A., A. Paulson, andj. Rose 1978 Food and feeding relationships in the benthic and demersal Fishes of the Gulf of Alaska and Bering Sea. Research Unit 284. Environmental Assessment of the Alaskan Continental Shelf, Final Reports of Principal Investigators l(Biological Studies):33-107. Smith, G.B., R.S. Hadley, R. French, R. Nelson, Jr., and J. Wall 1981 A summary of productive foreign Fishing loca- tions in the Alaska region during 1977-80: trawl Fisheries. Alaska Sea Grant Report 81-4, University of Alaska, Fairbanks, AK. 4l() pp. Stoker, S.W. 1978 Benthic invertebrate macrofauna of the east- ern continental shelf of the Bering and Chukchi seas. Ph.D. Dissertation, Universin of Alaska, Fairbanks, AK. 259 pp. 396 Biological Resources Stephenson, W. 1973 The validity of the community concept in marine biology. Proceedings of the Royal Society of Queensland 84:73-86. Sundberg, K.A. and D. Clausen 1977 Post-larval king crab {Paralithodes camtschatica) distribution and abundance in Kachemak Bay, lower Cook Inlet, Alaska. In: Environmental Stud- ies of Kachemak Bay, Vol. 5. L.L. Trasky, L.B. Flagg, and D.C. Burbank, editors. Alaska Department of Fish and Game, Anchorage, AK. pp. 1-36. Thorson, G. 1957 Bottom communities (sublittoral or shallow shelf). In: Treatise on Marine Ecology and Paleo- ecology, Vol. 1: Ecology. J.W. Hedgpeth, editor. Memoir 67, Geological Society of America, New York, NY. pp. 461-534 U.S. Department of the Interior (USDI) 1977 Lower Cook Inlet final environmental impact statement, Vol. 1. Alaska Outer Continental Shelf Office, Anchorage, AK. pp. 1-561. Wallace, M.M., C.J. Pertuit, and A.R. Hvatum 1949 Contribution to the biology of the king crab, Paralithodes camtschatica (Tilesius). U.S. Fish and Wildlife Service, Fishery Leaflet 340. 50 pp. Walsh, J.W. and C.P. McRoy 1986 Ecosystem analysis in the southeastern Bering Sea. Continental Shelf Research 5:259-288. Warwick, R.M. 1980 Population dynamics and secondary produc- tion of benthos. In: Marine Benthic Dynamics. K. Tenore and B. Coull, editors. University of South Carolina Press, Columbia, SC. pp. 1-24. Whittaker, R.H. 1970 Communities and Ecosystems. MacMillan, New York, NY. 162 pp. Wilcox, J.R. and H.P.Jeffries 1974 Feeding habits of the sand shrimp Crangon sep- temspinosa. Biological Bulletin 146:424-434. Zenkevitch, L.A. 1963 Biology of the Seas of the USSR. Interscience Pub- lishers, New York, NY. 955 pp. Zijlstra,JJ. 1972 On the importance of the Waddenzee as a nurs- ery area in relation to the conservation of the southern North Sea fishery resources. Zoological Society of London, Symposia 29:233-258. The Nearshore Fishes 13 Donald E. Rogers BrendaJ. Rogers Fisheries Research Institute University of Washington Seattle, Washington Rick J. Rosenthal Card iff— by— the— Sea, California Abstract The nearshore fishes in the Gulf of Alaska have been studied mainly in the areas near Kodiak, lower Cook Inlet, and Prince William Sound. These studies have been in response to potential oil development and, in southeastern Alaska, in response to a developing rockfish fishery. Several types of sampling gear were employed to deter- mine the species compositions and the relative abundances offish in various habitats, such as rocky/kelp, epipelagic, intertidal beaches, subtidal shelves, and the deeper bot- toms of bays. However, each type of gear was — to some extent — selective, and some species were undoubtedly under-represented in the catches. Greenlings, cottids, and flatfishes (yellowfin sole [Limanda aspera] and rock sole [Lepidopsetta bilineata]) were the prominent large fish that were found near shore in the bays, whereas greenlings, cottids, and rockfishes were more prominent along the exposed coast. Pacific sand lance (Ammodytes hexapterus), capelin (Mallotus villosus), and juveniles of many species were the prominent forage fishes. The nearshore zone serves as an important spawning and/or rearing area for several commercially impor- tant species such as the Pacific salmon (Oncorhynchus spp.), Pacific herring (Clupea harengus pallasii), walleye pollock {Theragra chalcogramma), and flatfishes. The densities of several of the larval fishes were much higher in the bays than they were in the off- shore waters of the shelf. The typical forage fishes and juveniles of all species fed predominantly on zoo- plankton and small epibenthic crustaceans, whereas larger fish consumed mainly polychaetes, crab, shrimp, and small fishes. Most of the organisms eaten were not commercially important. However, two species, yellowfin sole and yellow Irish lord (Hemilepidotus jordani), consumed significant quantities of Tanner crab (Chionoecetes bairdi) and Pacific cod (Gadus macrocephalus); three species — walleye pollock, flathead sole {Hippoglossoides elassodori), and yellow Irish lord — consumed large quantities of pandalid shrimp. Research on nearshore fish is needed in other areas of the Gulf, and there is a spe- cial need to determine the magnitude of interannual variations at specific locations if we are to accurately evaluate environmental or fishery impacts in the future. Introduction Because marine research is relatively expensive, our knowledge of the fish communities in the Gulf of Alaska has been largely dictated by the need to understand potential environmental or fishery crises. Prior to the 1970s, studies were largely confined to either single commercially impor- tant species such as salmon, halibut, or herring, or to off- shore bottom fishes (Ronholt, Shippen, and Brown 1979). Research on nearshore fish communities consisted largely of taxonomic studies and the compilation of both checklists and geographic distributions (Wilimovsky 1954; Hubbard and Reeder 1965; and Quast and Hall 1972). However, with the initiation of the Outer Continental Shelf Environmental Assessment Program (OCSEAP) in 1974, and the State of Alaska's interest in the inshore groundfish resources soon thereafter, research funding was provided in order to inves- tigate the ichthyofauna of this previously undescribed zone. 399 400 Biological Resources The nearshore zone, in contrast to the open offshore waters in the Gulf of Alaska, is especially vulnerable to environmental impacts from human activities. The near- shore zone for this chapter is defined as the intertidal and subtidal waters to a depth of about 30 m and the deeper waters of bays or estuaries within less than 5 km of the shoreline. Exploration for and potential development of petroleum resources in lower Cook Inlet, off the eastern coast of Kodiak Island, and in the northeastern Gulf of Alaska, prompted the United States government to fund research projects on the nearshore fish communities in these areas. Surveys of inshore fishes in the southeastern Gulf of Alaska were initiated in anticipation of a new domes- tic commercial fishery. The results of these widely separated studies form the primary basis for our discussion of the nearshore fishes of the Gulf of Alaska. Nearshore fish research in the southeastern Gulf has been concentrated either on single species such as walleye pollock (Clausen 1983) and Pacific herring (Blankenbeckler 1980; Carlson 1980), or on limited assemblages (e.g., bottom- fish and rockfish) (Haldorson and Rosenthal 1983). The nearshore fish communities in the northeastern Gulf have likewise received relatively little study (Rogers, Wangerin, Garrison, and Rogers 1983). Although Rosenthal (1983) reported the results of a survey in Prince William Sound (which we will review), nearshore research in the central and western Gulf of Alaska has been sparse and has been directed toward single species such as salmon (Tyler 1972). The only exception is in lower Cook Inlet and along the east- ern coast of Kodiak Island. Intensive fish sampling was conducted in lower Cook Inlet in 1978 by both the Alaska Department of Fish and Game (ADF&G) and by Dames and Moore (Blackburn, Anderson, Hamilton, and Starr 1983; Dames and Moore 1983). The ADF&G and the Fisheries Research Institute (FRI) conducted a similar study in 1976 within three bays (Alitak, Kaiugnak, and Ugak) on Kodiak Island (Fig. 13-1) (Blackburn 1979; Harris and Hartt 1977). However, the most extensive nearshore fish survey was conducted in 1978-1979 in four Kodiak Archipelago bays (Kaiugnak, Kiliuda, Kalsin, and Izhut). This survey by ADF&G, FRI, and the National Marine Fisheries Service (NMFS) employed six types of gear and was conducted during seven months of the year. Over 1,000 sets or hauls were made and 14,000 fish stomachs were examined to determine seasonal compositions and food habits of the nearshore fish communities (Blackburn and Jackson 1980; Rogers, Rabin, Rogers, Garrison, and Wangerin 1979). In addition, larval fish were sampled con- currently using four different types of gear in the bays and offshore waters (Dunn, Kendall, Wolotira, Bowerman, Dey, Matarese, and Munk 1981; Kendall, Dunn, Matarese, Rogers, and Garrison 1981). The shallow-water fish assemblages of the northeastern Gulf of Alaska and Prince William Sound (Fig. 13-2) were examined during 1977 through 1979 (Rosenthal 1983). Addi- tional baseline observations were made in the summer of 1980 (Rosenthal, Lees, and Maiero 1982). These studies were designed to provide detailed descriptions and ecological analyses of nearshore fish assemblages. Important food- web links and dietary trends among the conspicuous species 153 152 i^JshuyaU. Kalsin Bay O Ugak Bay Kiliuda Bay Alitak Bay U/^ Kaiugnak Bay Deadman Bay /■ Ctp 153 152 Figure 13-1. Bays of the Kodiak Archipelago in which near- shore fish surveys were conducted. of fish were also described as part of these investigations. Morrison (Alaska Department of Fish and Game, unpubl. data) surveyed rockfish and lingcod (Ophiodon elongatus) stocks along the outer Kenai Peninsula during 1982-1983. The ADF&G field studies were in response to a developing small-boat fishery for rockfish in this area. Resource assessment studies of both inshore and shallow offshore bottomfish in southeastern Alaska were conducted during 1980 to 1983 in anticipation of an expanding domes- tic fishery for rockfish and lingcod. The need for baseline information on these multispecies assemblages was recog- nized and research was directed by ADF&G (Rosenthal, Field, and Myer 1981; Rosenthal, Haldorson, Field, O'Con- nell, LaRiviere, Underwood, and Murphy 1982; and Haldor- son and Rosenthal 1983). Most of the shallow exposed waters of the Gulf of Alaska remain in a relatively pristine state; therefore, a unique sit- uation was presented to the various investigative teams in that they were able to survey fish populations before human influence and heavy commercial exploitation disrupted nat- ural population dynamics. Sampling Methods In order to obtain a broad description of the nearshore fish communities, several types of gear were used because each has unique properties regarding both where and how it samples the fishes. Passive gear — such as a set gill-net, The Nearshore Fishes 401 146 \ aldez GulJ of Ala.\ka 60 148 147 Figure 13-2. Shallow-water study sites in Prince William Sound. trammel net, or hook and line — depends on the fishes' activity as well as their size and shape, and it is relatively inef- fective in capturing small or sedentary fish. Active gear — such as trawls and tow nets — is not so dependent on the activity of the fish, but its effectiveness is dependent on mesh size and the size of the net opening. Seines are proba- bly the least selective gear since they catch fish by surround- ing them; however, they can only be used either in shallow or surface waters and in areas where there are few obstructions. The main gear types employed in the Kodiak bays are illustrated in Figure 13-3. Not shown are a mid-water trawl used only in the summer of 1976 and a surface gill net used only in the late spring and summer of 1978. Catches were sorted by species and weighed. Lengths were measured and stomachs collected from selected species (usually the more 146 abundant species). Stomach contents were identified, enu- merated, and weighed in the laboratory. Catch statistics and stomach contents were grouped by fish length for the pur- pose of analysis; the lengths were broken into categories of 30-150 mm, 151-300 mm, and over 300 mm. Fish less than 150 mm were predominantly juveniles (i.e., young-of- the-year or yearlings). Larval fish (typically < 20 mm in length) were sampled by four gear types (Fig. 13-4). A neuston net sampled the sur- face layer, an epibenthic sled sampled fish near the bottom, and a Tucker trawl sampled discrete mid-water depths. The bongo net, which sampled from near bottom to the surface, was the most effective gear because it caught by far the great- est number of larval fish and eggs. Blackburn et al. (1983) sampled the nearshore fishes in lower Cook Inlet using a beach seine, a try net, a tow net, a 402 Biological Resources Figure 13-3. Sampling gear employed in the nearshore zone of Kodiak Island bays. gill net, and a trammel net. Dames and Moore (1983) also made SCUBA observations near shore in Kamishak and Kachemak Bays. Rosenthal (1983) studied fish communities from 2 to 39 m below MLLW at four primary sites in outer Prince William Sound. Gill nets, hook and line, and SCUBA were the main sampling techniques. Divers covered nearly 1.3 x 104 m2, gathering fish density and distribution information along random or haphazardly placed transects. They also covered nearly 6 * 103 m2 along fixed transects. The primary gear used in Southeast Alaska by Rosenthal, Field, and Myer (1981) was automatic jigging machines rig- ged with monofilament line, weights, and between 5- and 10-hook strings attached to synthetic rubber lures. The jig gear was fished vertically from the bottom to near the sur- face. Diver/biologists were also used to conduct counts, observe behavior, and to collect fish that were located in depths up to ~ 30 meters. In the period from 1980 to 1982, 201 diver transects — each measuring 30m x 2 m — were studied, for a total coverage of 12,060 square meters. Fish collected from Prince William Sound and south- eastern Alaska were sorted according to species, and indi- vidual fish were measured and weighed to the nearest gram. Two general methods were used to describe the food habits: 1) divers made direct observations offish feeding, or 2) stom- achs which had been removed from selected species were examined either while they were fresh or after they were preserved. Results Occurrence of Species Based on a summary of the early fish collections that were made in Alaska, Quast and Hall (1972) suggested that the range of numerous species would be extended by future research. Peden and Wilson (1976) subsequently surveyed the inshore waters of northern British Columbia and cap- tured 120 species of fish. Their results extended the geo- graphic ranges of 20% of these species. The nearshore sampling conducted in the Gulf of Alaska during 1976 through 1982 resulted in the collection of 153 species offish from 33 families (Table 13-1). Included in the samples were four species and three families represented only by larval fish. Cottids (sculpins) were most numerous and constituted 25% of the 149 species (excluding larvae), while the rockfishes (largely from Prince William Sound and southeastern Alaska) constituted 12% of the species. About 21% of the fishes collected in the inshore Gulf waters were either previously unreported there or their occurrence extended their known range in the Gulf (Rosenthal and Haldorson, in press). Notably, the Bering wolffish {Anarichas Thf Nearshore Fishes 403 < > B 0 z a a. < a < < Ncuston Net r 10m 30m 50m Epibenthic Sled Figure 13-4. Ichthyoplankton sampling gear employed in Kodiak Island bays. orientalis) and leatherfin lumpsucker (Eumicrotremus derjugini) were caught in Cook Inlet (Blackburn et al. 1983), and the Bering poacher (Ocella dodecaedron) was caught at Kodiak (Harris and Hartt 1977). These species had pre- viously been reported as occurring along the North Ameri- can coast only from the Bering Sea or from the Arctic Ocean. Several of the species caught inshore were uncommon in the catches and were atypical of nearshore fishes. In the fol- lowing section, we emphasize the relative abundance of the more common species in each of the four nearshore regions of the Gulf. Kodiak Archipelago. Adult and Juvenile Abundance. Blackburn (1979) made 240 otter trawls in both Ugak and Alitak Bays during the period from June to September 1976 and during March 1977. The preponderant species he recorded were yellowfin sole, great sculpin, flathead sole, yellow Irish lord, Pacific halibut (Hip- poglossus stenolepis), Pacific cod, walleye pollock, starry flounder (Platichthys stellatus), and Gymnocanthus spp. The catch composition was similar throughout the area with the exception of Deadman Bay, which had more eelpouts, snailfish, stout eelblenny {Lumpenus medius), and longsnout prickleback (Lumpenella longirostris) than any other site. Deadman Bay also had fewer of all other species except flathead sole, great sculpin, and capelin. There were two trends that emerged: 1) there were fewer species toward the heads of the bays, and 2) the fish were larger at greater depths. In the winter, most species moved to deeper water and no species moved into shallower water, although some species apparently moved into the bays. Comparisons of the otter trawl catches in Ugak and Alitak Bays with catches from the continental shelf and slope near Kodiak (Ronholt, Shippen, and Brown 1979) indi- cated the uniqueness of the bays. Rockfish were more com- mon on the shelf and the slope than they were in bays. Yel- lowfin sole constituted 58% of all the flounder in the Days but was only incidental on the shelf. Arrowtooth flounder (Atherestes stomias) ranked sixth among flounders in the bays, but was the most abundant flatfish on the shelf. However, in shelf areas of less than 100 m, rock sole was the most com- mon flounder — but it only ranked fifth among flounders in Ugak and Alitak Bays. Starry flounder was the fourth most abundant species in the bays — due primarily to high winter catches — but it was incidental offshore. However, winter studies were not conducted offshore, so the two are difficult to compare. Most species were more abundant on the shelf than they were in the bays, with abundance generally decreasing toward the heads of bays. Fish size increased with increasing depth, indicating that the shallow areas — which are the most vulnerable to environmental impacts — are important as nursery sites. The nearshore and pelagic fish of Ugak, Kaiugnak, and Alitak Bays on both the east and the south coasts of Kodiak Island were sampled during four cruises that took place from late May to mid-September 1976 (Harris and Hartt 404 Biological Resources Table 13-1. List of fishes collected in the nearshore waters of the Gulf of Alaska from Kodiak (K), Cook Inlet (C), Prince William Sound (P), and Southeast Alaska (S) between 1976 and 1982. Petromyzontidae Scorpaenidae Lampetra japonica Arctic lamprey C Sebastes alutus Pacific ocean perch K Lamnidae Lamiui ditropis S. auriculatus Brown rockfish P Salmon shark PS S. brevispinis Silvergray rockfish PS S. caurinus Copper rockfish CPS Squalidae S. ciliatus Dusky rockfish KCPS Squalus acanthias Spiny dogfish KC S. crameri Darkblotched rockfish K Rajidae Raja binoculata S. emphaeus Puget Sound rockfish PS Big skate KCS S. entomelas Widow rockfish S R. kincaidii Black skate C S. Jlavidus Yellowtail rockfish PS R. rhiiui Longnose skate KCS S. maliger Quillback rockfish PS S. melanops Black rockfish KCPS Clupeidae S. miniatus Vermilion rockfish s Clupea harengus pallasii Pacific herring KCPS S. mystinus Blue rockfish s Salmonidae S. nebulosus China rockfish PS Coregonus laurettae Bering cisco C S. nigrocinctus Tiger rockfish KPS Oncorhynchus gorbuscha Pink salmon KCPS S. pinniger Canary rockfish s 0. keta Chum salmon KC S. proriger Redstripe rockfish s 0. kisulch Coho salmon KCPS S. ruberrimus Yelloweye rockfish PS 0. nerka Sockeye salmon KCPS Anoplopomatidae O. tshawytscha Chinook salmon CS Anoplopoma fimbria Sablefish KS Salmo gairdnerii Steelhead s Salvelinus malma Dolly Varden KCS Hexagrammidae Hexagrammos decagrammus Kelp greenling KCPS Osmeridae H. lagocephalus Rock greenling KCPS Hypomesus pretiosus Surf smelt KC H. octogrammus Masked greenling KCPS Mallotus villosus Capelin KC H. stelleri Whitespotted greenling KCPS Spirinchus thaleichthys Longfin smelt C H. superciliosus Terpug K Tkaleichthys pacificus Eulachon KC Pleurogrammus monopterygius Atka mackerel K Bathylagidae Ophiodon elongatus Lingcod KCPS Leuroglossm Schmidt i Northern smoothtongue * Cottidae Myctophidae Artedius fenestrate Padded sculpin KCPS Stenobrachius leucopsarus Northern lampfish * A. harringtoni Scalyhead sculpin CPS A. lateralis Smoothhead sculpin CP Gadidae A. notospilotus Bonyhead sculpin CP Elegimis gracilis Saffron cod C Blepsias bilobus B. cirrhosus Crested sculpin KP Gadus macrocephalus Pacific cod KCPS Silverspotted sculpin KCP Microgadus proximus Pacific tomcod KCPS Clinocottus acuticeps Sharpnose sculpin KCP Theragra chalcogramma Walleye pollock KCPS Dasycottus setiger Spinyhead sculpin KC Zoarcidae Enophrys bison Buffalo sculpin KPS Bolhrocara pusillum Alaska eelpout K E. diceraus Antlered sculpin KC Lycodes brevipes Shortfin eelpout KC Gilbertidia sigalutes Soft sculpin KC L. palearis Wattled eelpout KC Gymnocanthus galeatus Armorhead sculpin KC Gasterosteidae Gaslerosteus aculeatus G. pistilliger Threaded sculpin KC Threespine stickleback CP Hemilepidolus hemilepidotus H. jordani Red Irish lord Yellow Irish lord KCPS KCP Syngnathidae H. spinosus Brown Irish lord CP Syngnathus griseolineatus Bay pipefish S Hemitripterus bolini Bigmouth sculpin KCP Aulorhynchidae A ulorhynchus jlavidus Tubesnout KCPS lcelinus borealis Icelus spiniger Jordania zonope Northern sculpin Thorny sculpin Longfin sculpin KC KC PS Embiotocidae Leptocottus armatus Pacific staghorn sculpin KCPS Cymatogaster aggregata Shiner perch S Malacocottus kincaidi Blackfin sculpin C Trichodontidae Myoxocephalus jack Plain sculpin KC Trichodon trichodon Pacific sandfish KC M. niger Warthead sculpin K M. polyacanthocephalus Great sculpin KCP Bathymasteridae M. scorpius Shorthorn sculpin KP Bathymaster caeruleofasciatus Alaskan ronquil KCPS Nautichthys oculofasciatus Sailfin sculpin KPS B. leurolepis Smallmouth ronquil CP N. pribilovius Eyeshade sculpin KC B. signatus Searcher KCPS Oligocottus maculosus Tidepool sculpin KCP Ronquilus jordani Northern ronquil KCPS Psychrolules paradoxus Tadpole sculpin KC Radulinus asprellus Slim sculpin K Rhamphocottus richardsonii Grunt sculpin CPS Scorpaenichthys marmoratus Cabezon s Synchirus gilli Manacled sculpin K Triglops forfica ta Scissortail sculpin KC T. macellus Roughspine sculpin K T. pingelii Ribbed sculpin KCP The Nearshore Fishes 405 Stichaeidac Anoplarchus purpurescens Chvrolophii nugator C. decora tits Lumpenella longirostris Lumpenus maculatus L. medius L. sagitta Poroclinus rothrocki Stichaeus punctatus Xiphister mucosus Pholididae Apodich th ys flavidus Pholis clemensi P. laeta Anarhichadidae Anarichas oriental is A narrhichthys ocellatus Ptilichthyidae Ptilichthys goodei Cryptacanthodidae Delolepis gigantea Lyconectes aleutensis Zaproridae Zaprora silenus Ammodytidae Ammodytes hexapterus Gobiidae Coryphopterus n icholsii High cockscomb Mosshead warbonnet Decorated warbonnet Longsnout prickleback Daubed shanny Stout eelblenny Snake prickleback Whitebarred prickleback Arctic shanny Rock prickleback Penpoint gunnel Longfin gunnel Crescent gunnel Bering wolffish WolT-eel Quillfish Giant wrymouth Dwarf wrymouth Prowfish Pacific sand lance Blackeye goby Agonidae KCP Agonopsis emmelane Northern spearnose poacher C PS Agonus acipenserinus Sturgeon poacher KCP S Anoplagonus inermis Smooth alligatorfish KCP K Aspidophoroides bartoni Aleutian alligatorfish C KC Asterolheca alascana Grey starsnoul c K Hypsagonus quadricornis Fourhorn poacher c KCPS Occella dodecaedron Bering poacher KC K Pallasina barbata Tubenose poacher KC KCP Sarritor frenatus Sawback poacher C S Cyclopteridae Aptocyclus ventricosiis Smooth lumpsucker KP KPS Eumicrotrernus derjugini Leatherfin lumpsucker C K E. orbis Pacific spiny lumpsucker CP KCPS Liparis callyodon Spotted snailfish KC L. cyclopui Ribbon snailfish KC KC KCPS L. dennyi Marbled snailfish KCP L. florae Tidepool snailfish C L.fucensis Slipskin snailfish KC L. mucosus Slimy snailfish K * L. pulchellus Showy snailfish C L. rutteri Ringtail snailfish C C Pleuronectidae * Atheresthes stomias Arrowtooth flounder KCP Glyptocephalus zachirus Rex sole KC KCPS Hippoglossoides elassodon Flathead sole KCP Hippoglossus stenolepis Pacific halibut KCPS hopsetta isolepis Butter sole KC KCPS Lepidopsetta bilineata Rock sole KCPS Limanda aspera Yellowfin sole KCP s Microstomus pacificus Dover sole KCP Parophrys vetulus English sole KCP Pleuronectes quadrituberculatus Alaska plaice KC Platichthys stellatus Starry flounder KCPS Psettichthys melanostictus Sand sole KC * Collected only as larval fish from Kodiak. 1977). The survey objectives were to determine the species composition, distribution, and relative abundance for the common species, along with determining the age-class com- position and the food habits for the key species. The estuarine bays proved to be nursery areas. Juvenile fish were found both near shore and in the pelagic habitats of the bays. During the study, 70 species were caught, with more species found in the subtidal zone than in either the intertidal or the pelagic zones. Large numbers of capelin and young-of-the-year Pacific sandfish {Trichodon trichodon) were encountered in the pelagic zone, with both species exhibiting a diel migration. Few adults were found in the study area. Other abundant pelagic species were young-of-the-year sand lance and juvenile salmon (mainly pink salmon [Oncorhynchus gorbuscha}). Both pink and chum salmon {Oncorhynchus keta) moved from nearshore to pelagic hab- itats in early summer and left the bays by mid-September. Greenlings were prominent in the rocky/kelp habitats and flatfishes were prominent in the subtidal smooth-bottomed habitats. Of the four bays surveyed in 1978 and 1979 (Blackburn andjackson 1980), one (Kaiugnak) had also been sampled in 1976. Although the station locations were not identical for both surveys, this dual sampling provided some comparison of the interannual variation in relative abundance. How- ever, between 1976 and 1978, there was a marked change in seasonal water temperatures in the nearshore region of Kodiak Island (Table 13-2). Water temperatures during 1976 were comparable to the average for 1950 through 1976, whereas water temperatures in 1978 were significantly warmer during winter and spring months, although they were comparable to averages for the recent warmer years Table 13-2. A comparison of monthly mean sea surface temperatures (C) in 1976 and in 1978 and 1979 with recent and earlier historical means and ranges for Womens Bay (Kodiak). June 1950- Nov. 1976- Oct. 1976 1976 Dec . 1985 1978 1979 Month Mean Range Mean Mean Range Mean Mean Jan 0.8 -1.7,3.0 2.4 4.1 2.3,5.1 4.0 5.0 Feb 1.0 -0.8,3.1 2.4 3.6 1.8,5.4 4.2 3.1 Mar 1.6 -0.5,4.3 2.8 4.2 2.3,6.0 4.7 4.5* Apr 3.6 2.1,5.0 3.9 5.5 3.1,6.9 5.9* 6.9 May 6.3 4.2,7.8 6.0* 7.6 5.9,8.8 7.2* 8.8 Jun 8.5 6.4,10.3 8.7* 10.3 8.6.11.7 10.3* 10.6 J"' 1 1 .0 8.7,13.7 11.1* 12.1 10.1.13.7 11.8* 13.2 Aug 11.9 9.8,13.4 11.8* 12.9 11.4,14.4 13.2* 14.4 Sep 9.9 8.1,11.4 11.0* 11.1 9.6.12.1 11.5 12.1 Oct 6.9 5.2,8.4 8.2 8.0 6.7,9.1 8.8 9.1 Nov 4.0 0.4,5.8 6.1 5.8 4.1,7.3 6.2* 7.3 Dec 1.7 -0.6,3.8 5.7 4.2 2.9,5.7 5.4 4.2 * Months in which sampling was conducted in Kodiak bays. . Data source: U.S. Department of Commerce. NOAA/NOS, Rockville. MD 20852. 406 Biological Resources (1976-1985). This is important because temperature proba- bly affects the distribution and availability offish. The snake prickleback (Lumpenus sagitta) was the most abundant fish that was caught using try nets in Kaiugnak Bay in 1976, yet it was absent in try net hauls in 1978. Instead, yellowfin sole was the most abundant species that year. Capelin were most abundant in tow net catches in 1976, whereas they were not caught at all in Kaiugnak Bay during 1978 — and the Pacific sand lance was the most abundant species. Pacific sandfish was the third most abundant spe- cies in the 1976 beach seine catches that were made in Kaiug- nak Bay, but they were also not captured there during 1978. Only the species' compositions in trammel-net catches were similar in 1976 and 1978. These catches were dominated by both masked and rock greenling (Hexagrammos lagocephalus) that were generally larger and older than the highly variable, small, and mosdy pelagic forage fishes. The geometric means of the catches made during 1978 and 1979 for the four bays — Izhut, Kalsin (within the larger Chiniak Bay), Kiliuda, and Kaiugnak — depict the seasonal changes in relative abundance of the five most common spe- cies (Table 13-3). Catches were combined for April (1978) and March (1979) to represent the cold temperatures of winter; they were combined for May and June (rising spring temperatures), and for July and August (summer tem- peratures), with catches for November representing fall with its declining temperatures. The nearshore fishes were relatively scarce in late winter and were apparently the most abundant in the summer. The seasonal changes in the deeper waters (sampled by otter trawls) were not so pronounced. The gill net catches are not given because they were obtained mainly during the sum- mer and the sampling effort was relatively low. Pacific her- ring was most abundant in the gill net catches, whereas it was either scarce or absent from catches taken by the other gear. More adult salmon were caught by gill nets than by any other gear. The abundance of salmon in the Kodiak region was well established from historical fishery records, and areas of salmon concentrations (e.g., stream mouths) were purposely avoided. Twenty-two families and 101 species of fish were identi- fied in the catches taken from the Kodiak Archipelago bays. Many species were apparently not very abundant. However, if other gear such as SCUBA or hook-and-line had been employed, or if the sampling had been conducted outside the bays on exposed headlands, a somewhat different view as to the most abundant nearshore fishes at Kodiak might have emerged. The trend apparent from otter trawl catches, showing that body size decreased from offshore to inshore, appeared Table 13-3. Seasonal abundances of the five most abundant fish species by gear type in four bays along the southeastern coastline of the Kodiak Archipelago, 1978-1979. Gear Type (unit of effort) Species Number Per Unit Effort Winter Spring Summer Fall Biomass Per Unit Effort Winter Spring Summer Fall Beach seine (haul) Pink salmon Dolly Varden Pacific sand lance Masked greenling Gieat sculpin Trammel net (2 h set) Rock greenling Masked greenling Whitespotted greenling Great sculpin Rock sole Tow net (10 min haul) Pink salmon Chum salmon Capelin Pacific sand lance Threespine stickleback Try net (10 min haul) Great sculpin Gymnocanthus sp. Rock sole Yellowfin sole Flathead sole Otter trawl (20 min haul) Walleye pollock Great sculpin Rock sole Yellowfin sole Flathead sole (grams) 3 69 6 0 1 37 2,202 0 + + 1 + 3 78 118 40 + 9 154 2 + 33 299 13 1 1 4 1 9 46 78 26 1 3 5 3 7 124 52 152 2 13 28 5 474 (grams) 6,716 9,952 2,139 1 8 48 3 20 895 6,498 818 + 2 5 2 2 335 1,291 82 + 1 1 1 126 255 249 860 1 3 2 1 117 674 61 78 + 3 2 0 + (grams 1 ) 7 0 + 4 + 0 + 5 + 0 + 1 + 1 1 2 + + + + 52 + 1 + 81 + + + + 0 1 1 + 0 + 1 2 1 12 (grams) 102 849 177 2 4 7 4 48 236 323 61 6 18 34 29 241 1,061 1,834 1,370 1 19 39 12 13 1,187 3,576 626 1 4 9 2 3 47 227 15 210 75 190 517 0.4 (kilograms) 3.2 26.2 22.7 15 64 39 30 17.4 70.7 40.4 41.6 309 397 154 115 43.5 102.6 39.0 30.9 236 349 300 756 36.7 77.2 77.8 150.4 98 405 557 479 3.9 41.7 94.8 23.5 < I The Nearshore Fishes 407 to continue into the nearshore zone. However, the trend was partially obscured by gear selectivity. The average body weights (by season) and the composition (by length inter- vals) were averaged over the seasons and then examined for two particular species that were caught in four types of gear (Table 13-4). The trammel net was obviously ineffective in capturing juvenile fish, and the smaller Myoxocephalus juve- niles were more difficult to identify; otherwise, great sculp- ins — some Myoxocephalus spp., but predominantly M. polya- canthocephalus — were smaller, and a higher proportion of juveniles was present in the intertidal and subtidal waters than in deeper waters. Rock sole were smaller in the winter and generally smaller nearshore than they were in deeper water. However, there was a higher proportion of juveniles in the subtidal (try net) than in the shallower beach areas. The nearshore zone does appear to be especially important as a rearing area for juvenile fish. Ichthyoplankton. Nearshore surveys of both fish larvae and eggs within the Gulf were mainly conducted in the east- coast bays of the Kodiak Archipelago. More extensive sur- veys were conducted offshore over the continental shelf and slope at about 90 stations from 40 to 2,000 m deep (Dunn et al. 1981). We compared the results of the inshore (bays) sur- veys and the offshore surveys with regard to the most abun- dant taxa and their densities (number per 100 m2) in order to determine the uniqueness, if any, of the nearshore ich- Table 13-4. Comparisons of the body sizes of fish caught by different gear types in four Kodiak Archipelago bays, 1978-1979. Composition of Catch by Body Weight Gear Type Mean Body Weight (g) Species Winter Spring Summer Autumn Great sculpin Beach seine 9 48 11 53 Trammel net 419 425 311 955 Try net 62 146 404 161 Otter trawl 1,163 1,104 1,032 1,400 Rock sol e Beach seine 19 74 88 59 Trammel net 130 250 34 87 Try net 44 57 54 47 Otter trawl 141 259 253 268 Composition of Catch (%) by Body Length Gear Tyte Length Interval (mm) Species S150 151-300 >300 Great sculpin Beach seine 81 12 7 Trammel net 0 23 77 Try net 27 22 51 Otter trawl 4 6 90 Rock sol le Beach seine 36 50 14 Trammel net 3 56 40 Try net 73 21 6 Otter trawl 5 64 31 thyofauna. Offshore, five cruises were conducted that spanned the four seasons; inshore, ten cruises were con- ducted during four seasons. To choose the most abundant taxa for discussion, catches during four inshore cruises were examined — these cruises taking place during: 6 to 16 March, 29 March to 8 April, 21 to 29July, and 3 to 13 November. Inshore, 110 taxa were captured compared with the ~60 taxa that were captured offshore. The numbers and the diversity of the ichthyoplankton were greater in the spring and summer than they were in the fall and winter, and inshore catches were generally larger than offshore catches. Thirty taxa were abundant enough to allow their distribu- tions to be described. Seven of the most abundant are dis- cussed here: larvae of four species (Pacific sand lance, sand sole [Psettichthys melanostktus], stout eelblenny, and walleye pollock); two larval groups (smelt and great sculpins); and flatfish eggs. The smelt larvae were identified only to the familial level in the bays because of their small size; however, most were probably capelin. Capelin were identified in the offshore samples. Smelt larvae were found year-round and con- stituted about 90% of all larval fish in the bays. They were caught more frequently in bongo nets than neuston nets at both offshore and inshore sampling sites. The average den- sity of smelt larvae reached 13,480/100 m2 in the bays during late August. They were somewhat more abundant in Izhut Bay than in the other bays. Their offshore density averaged only 11/100 m2 during the period of 19 June to 9 July, with densities tending to be higher closer to shore. More smelt larvae were captured in neuston tows during the night than during the day. Smelt larvae were at their most abundant densities at 10, 30, and 50 m during both day and night. However, high densities also occurred at the remaining sample depths of 70 and 90 meters. Smelt larvae were also the most abundant taxon in epibenthic sled sam- ples that were taken close to the sea floor. Walleye pollock larvae were collected mostly in the spring. Inshore, the highest abundances occurred during the period from 21 April to 1 May (76/100 m2). Offshore, the highest abundance of larvae occurred during the spring cruise from 28 March to 20 April (7/100 m2 larvae). The high- est abundances occurred in Chiniak Bay and the lowest occurred in Kaiugnak Bay. At least four species of great sculpins occur in the north- east Pacific: Myoxocephalus jaok, the plain sculpin, M. scorpius, the shorthorn sculpin, M. niger, the warthead sculpin, and M. polyacanthocephalus, the great sculpin. Two types were recog- nized in the ichthyoplankton, one of which (Type A) resembled a larval great sculpin which was very abundant in Kodiak bays. The other (Type B) could not be identified. Both types occurred primarily during the spring when den- sities of both A and B reached 102/100 m2 during the period from 21 April to 1 May. Their densities were highest at 10 m during the day, but highest at 30, 50, and 70 m during the night. Pacific sand lance larvae were captured primarily by bongo nets, with the larvae occurring from early March (186/100 m2) to mid-June (2/100 m2). Pacific sand lance densi- ties were highest during 29 March through 8 April (343/100 m2). There were no differences in abundance among the 408 Biologicai Resources bays; however, mean catches were larger inshore than offshore. In Izhut Bay, highest densities of Pacific sand lance larvae occurred at 10 and 30 m during the day, whereas at night, the major abundances were at 30, 50, 70, and 90 meters. Densi- ties were also highest in Kiliuda Bay during the day, but at night, the major concentrations were at 10, 30, 50, and 70 meters. Stout eelblenny larvae were taken inshore during the winter, the spring, and the summer. The largest numbers occurred during late March to early April (31/100 m2) and the largest catches came from Kiliuda Bay. The smallest catches were in Izhut Bay and no larval stout eelblenny were collected in surface samples. They were apparently dis- tributed over 10- to 90-m depths during both day and night. Offshore catches were negligible. Unidentified flatfish eggs most likely came from five spe- cies: starry flounder, sand sole, English sole (Parophrys vet- ulus), yellowfin sole, or butter sole (Isopsetta isolepis). Inshore, the largest catches occurred in both mid-July (1,752/100 m2) and early August (1,816/100 m2). The highest mean catch of eggs was in Kiliuda Bay. Sand sole larvae were caught both in the bays and off- shore. Catches in bays occurred from late May to late August. The largest catches were in late July (44/100 m2). Abundances did not differ significantly among the bays. Offshore, sand sole larvae were caught only during the sum- mer, and then only at 41% of the stations. Catch densities averaged 187100 m2. Larval sand sole in both Izhut and Kili- uda Bays were concentrated at 10- and 30-m depths during the day. At night, high concentrations occurred at both 30 and 50 m — although larvae were also caught at 70 and 90 meters. The high abundance of sand sole larvae was somewhat surprising because adults and juveniles were relatively scarce inshore. However, rock sole, which were the most abundant flatfish in the bays, were represented by large numbers of larvae in the spring (21 April to 1 May — 338/100 m2). The high catches of larval capelin and Pacific sand lance were expected because of the high abundance of the older fish inshore. Lower Cook Inlet. Twenty-five families (105 species) were collected from lower Cook Inlet. The most important species by numbers in the beach seine catches were Pacific sand lance, juvenile chum salmon, Dolly Varden (Salvelinus malma), juvenile pink salmon, Pacific herring, longfin smelt (Spirinchus thaleichthys), whitespotted greenling {Hexagram- mos stelleri), Pacific staghorn sculpin (Leptocottus armatus), and Myoxocephalus spp. (mainly the great sculpin). The most important species by weight in the try net catches were yellowfin sole, butter sole, flathead sole, Pacific halibut, rock sole, arrowtooth flounder, Myoxocephalus spp., and walleye pollock juveniles. Numerically predominant species in the tow net were the Pacific sand lance, Pacific herring, whitespotted greenling, capelin, as well as juvenile pink, sockeye, chum, and chinook salmon. Numerically important species caught in the gill net were adult herring, chum salmon, Dolly Varden, and Bering cisco {Coregonus lau- rettae). Numerically predominant species taken by trammel net included adult Pacific herring, whitespotted greenling, sturgeon poacher (Agonus acipenserinus), yellowfin sole, masked greenling (Hexagrammos octogrammus), and the Pacific staghorn sculpin. The composition of the ichthyofauna was different at each location. SCUBA surveys in Kamishak and Kachemak Bays revealed that non-schooling species were prominent at each rocky site. Sculpin, greenling, and ronquil were rep- resentatives of the major families that were observed. Only the greenling were common over rock habitats in Kamishak Bay. Alaskan ronquil (Bathymaster caeruleofasciatus) and kelp greenling were the most important demersal fishes in Kachemak Bay, but black rockfish (Sebastes melanops) and dusky rockfish (S. ciliatus) were the most numerous school- ing fishes found over the rocky substrate. Whitespotted greenling and masked greenling were the main demersal fishes found in Kamishak Bay. Over soft substrates, flatfish predominated in both bays. In the summer, the important species found on a sand beach were Pacific sand lance, Pacific staghorn sculpin, English sole, rock sole, sturgeon poacher, and Dolly Varden. During the winter, only Pacific sand lance, Pacific staghorn sculpin, and surf smelt (Hypo- mesus pretiosus) were present. Prince William Sound. Overall, 72 species from 18 fish families were identified in Prince William Sound. Of these, 14 species were found in areas that extended their known range. Species richness was generally the highest in exposed and semi-exposed habitats that were dominated by rocks and profuse algal growth. Within these habitats, rockfish and greenling usually dominated — both in terms of num- bers and weight. The kelp greenling was the most important species in terms of its frequency of occurrence and its rela- tive abundance. Black rockfish, dusky rockfish, Alaskan ron- quil, and whitespotted greenling were also important. In the eelgrass meadows, whitespotted greenling and Pacific tomcod (Mkrogadus proximus) were the preponderant species. Other important species in these habitats were starry flounder, tubesnout (Aulorhynchus flavidus), and juve- nile yellowtail rockfish (Sebastes flavidus). There was a positive correlation between the fish biomass and the bot- tom relief, suggesting that biomass was lower in these low relief areas than it was in the rocky, high-relief sites. There were marked seasonal changes in the species richness, the densities, and the spatial distribution of the fish communities. Summer density peaks were followed by strong winter declines at both the protected and the exposed sites. These were marked by bathymetric shifts as the fish moved farther offshore or into deeper waters. For example, at Zaikof Point in the southern entrance to Prince William Sound, there was a total of 15 species of reef fish sighted during the summer (August) 1978 survey (Rosenthal 1983). Fish density averaged 2,200 fish/ha in fixed (300 m2) transects, and 1,812 fish/ha in randomly (800 m2) placed transects. However, when the same area and depth strata were revisited in early April 1979, fish density had sharply declined to only 400 fish/ha in the fixed transects and 197 fish/ha in random transects. In addition, only seven species offish were sighted in the entire subtidal study area. Most of the population was recorded well below the 10-m isobath. Thf Nfakshokf Fishes 409 Species richness and abundance remained low through May, but steadily increased over summer until August (1979), when a total of 16 species was recorded. Density esti- mates in both the fixed and random transect bands during August were 1,833 and 1,667 fish/ha, respectively. The dif- ferences in the species composition, species richness, and the abundance between summer and winter were signifi- cant (P = 0.05). Southeastern Alaska. Fifty-one fish species were regu- larly observed in the rocky environment of die outer coast of southeastern Alaska between 1980 and 1982 (Rosenthal, Haldorson, Field, O'Connell, LaRiviere, Underwood, and Murphy 1982). There were 12,060 m2 of sea floor that were examined by SCUBA divers in four different depth strata. The rockfish family (Scorpaenidae) was represented by 12 species — six species that were regularly sighted in the shal- low water zone and six others that were present but less frequently encountered (Table 13-5). Overall, the most important species in terms of frequency of occurrence was the black rockfish. Another prominent species in this nearshore assemblage was the Puget Sound rockfish (Sebastes emphaeus), which ranked first in relative abundance. Dusky and yellowtail rockfishes were also relatively abundant. Many more species inhabit this shallow water zone; however, the field team was concerned only with species that frequent the exposed, high-energy rocky reef environment of the southeastern Gulf. The bathymetric patterns that relate to distribution and growth were studied for relatively unexploited populations of rockfish that inhabit the southeastern Gulf (Rosenthal, Haldorson, Field, O'Connell, La Riviere, Underwood, and Murphy 1982; Field 1984). Shallow-water bottomfish were categorized along various depth gradients starting at the shore and extending to the 50-fm ( ~ 91-m) depth contour. Table 13-5. Frequency of occurrence on transects and relative abundance (average number per transect) of most commonly observed bottomfish on diver transects sampled during 1980, 1981, and 1982 in southeastern Alaska. Frequency of Relative Abundance Occurrence (%) (% OF TOTAL FISH) Species 1980 1981 1982 1980 1981 1982 Puget Sound rockfish 31.6 31.8 77.8 31.8 33.5 45.2 Black rockfish 68.4 75.6 94.4 28.2 31.2 18.0 Dusky rockfish 57.1 43.3 72.2 23.1 11.2 7.9 Yellowtail rockfish 31.1 44.3 83.3 4.9 8.8 18.7 China rockfish 40.7 59.2 77.8 4.0 6.1 4.2 Quillback rockfish 33.9 27.9 33.3 5.4 5.4 2.7 Copper rockfish 14.1 20.9 16.7 1.2 1.4 0.7 Yelloweye rockfish 1.1 8.5 22.2 0.1 0.3 0.4 Canary rockfish 0 3.0 0 0 0.3 0 Tiger rockfish 1.1 6.5 22.2 0.1 0.3 0.6 Silvergray rockfish 7.3 3.0 16.7 0.4 0.2 0.7 Widow rockfish 0 1.0 0 0 0.1 0 Lingcod 11.3 28.4 44.4 0.7 1.2 0.8 Total transects 177 201 18 Total fish 3,340 6,238 962 Populations were structured by depth, distance from shore, and type of underlying habitat. Small, immature fish were usually found near shore. However, as depth increased, the size of the fish increased in a statistically significant fashion. Three species — black, yel- lowtail, and dusky rockfishes — exhibited a clear pattern of increasing size and age with increasing depth, and there was an absence of small or young fish in the deeper water (Table 13-6). Larger, mature fish were found either farther offshore or at greater depths than the immature members of the same species or population. Also, most of the fish collected in the deeper portions of the southeastern Gulf were much older than their counterparts in the nearshore zone (Fig. 13-5). Ecologically, three distinct zones became apparent dur- ing summer studies of rocky substrates (Fig. 13-6). The first zone was shallow, level, or rocky and extended from the low intertidal down to ~ 6 m (20 ft). This zone was dominated by low-statured kelps. Rock greenling, sculpins (Artedius spp.), and juvenile kelp greenling were common in this zone. The second zone was made up of kelp forests with can- opies that floated on the sea surface. Juvenile black, dusky, and yellowtail rockfishes inhabit these three-dimensional kelp forests. Other schooling fishes such as the tubesnout, herring, and Pacific tomcod were repeatedly observed in these stands of vegetation. Adult kelp greenling dominated the underlying sea floor that was overlain with fleshy algae and encrusting macroinvertebrates such as sponges and tunicates. These kelp forests occurred to depths of ~ 18 m on the exposed rocky outer coast. The third zone consisted of boulder fields inhabited pri- marily by both sea urchins (Strongylocentrotus spp.) and crust- ose coralline algae. Sedentary reef-dwelling fishes such as the Alaskan ronquil, red Irish lord, and the longfin sculpin were closely associated with the rocky substrate. Various rockfish species frequently schooled above the rock pave- ment and boulder patches or hid within the interstices of the reef. Lingcod were also common in the deeper zones. Boulder fields and rocky reefs occasionally extend to depths of 100 m in the southeastern Gulf of Alaska. Many of the bottomfish that were collected or observed in the shal- low-depth strata were either juveniles or subadults, as larger, sexually mature fish were typically found at depths beyond 30 m — the lower limit for safe diver observations in these northern waters. Food Habits About 950 stomachs from 18 fish species were examined by Harris and Hartt (1977) from samples collected in three Kodiak bays during 1976. Pelagic fish such as juvenile pink salmon, greenlings, and capelin consumed pelagic foods such as calanoid copepods, nauplii, euphausiids, and fish eggs. Juvenile pink and chum salmon caught in the inter- tidal zone had epibenthic diets, including harpacticoid copepods and gammarid amphipods. Pacific sand lance captured in intertidal areas had consumed mostly pelagic foods such as calanoid copepods, crab zoea, larvaceans, and nauplii. Rock sole and adult masked greenling had gener- alized diets — that is, no single food item was greatly pre- 410 Biological Resources Table 13-6. Average lengths (x), standard deviation (SD), and sample sizes (n) by depth zone for survey-caught fish in samples taken in 1981 and 1982 in southeastern Alaska. Average Length (cm) 10- -25 fm 26- -40 fm 41- 70 fm Year (18.3 -45.7 m) (47.6 -73.2 m) (74.9 -128 m) Species X SD n X SD n X SD n Black rockfish 1981 42.7 5.55 864 45.3 5.46 141 48.4 4.48 201 1982 41.6 5.50 731 46.2 5.32 18 46.5 4.67 95 Vellowtail rockfish 1981 34.9 5.31 255 37.8 5.77 204 43.7 3.79 384 1982 35.4 4.78 347 41.5 4.82 85 44.7 4.68 149 Dusky rockfish 1981 35.8 4.14 69 39.8 3.50 99 42.0 3.33 123 1982 32.2 3.26 61 40.2 3.55 64 43.5 2.84 71 Yelloweye rockfish 1981 53.1 12.44 30 57.7 12.06 29 58.8 7.96 81 1982 57.2 10.66 16 60.9 5.26 18 53.6 9.37 26 Quillback rockfish 1981 37.7 3.98 60 36.6 3.95 34 37.6 2.82 31 1982 35.5 4.42 30 39.8 2.84 20 39.4 4.22 9 Widow rockfish 1981 45.0 6.70 31 43.8 8.29 14 48.8 5.60 80 1982 36.1 2.75 17 40.9 4.61 20 Redstripe rockfish 1981 29.8 2.97 10 29.5 4.14 32 30.8 3.27 80 1982 27.1 2.59 34 29.2 4.95 31 29.9 3.53 39 Silvergray rockfish 1981 35.9 5.33 32 39.2 6.89 14 44.4 1.00 44 1982 37.5 6.93 29 43.4 11.25 15 41.9 7.62 59 Canary rockfish 1981 41.2 3.92 6 48.5 3.92 12 46.9 4.50 59 1982 44.3 3.51 3 44.3 3.51 3 48.1 4.76 26 Lingcod 1981 84.2 21.75 43 85.9 21.47 24 83.2 17.69 17 1982 73.1 14.74 29 82.9 14.91 16 74.6 5.46 5 dominant. Dolly Varden diets were also diverse, although fish was the most important item in their diet. The contents of 14,000 fish stomachs that were collected from the Kodiak bays in 1978-1979 were analyzed according to season, gear/habitat, bay, and predator length. Tradi- tional food webs that indicated the percentage of each food in a particular species' diet were created for those fish spe- Shallow (18-47m) 30- 25 H 20 -| 15 N = 71 Mean = 7.61 Scd. Dev. = 3.(1 Lul Middle (47-74m) - 30-i y u 25 5 20- | 15 N = 113 Mean = 9.98 Sid. Dev. = 4.2 y I rm-i =■_ Deep (74-lllm) 3U- 25- N = 165 ?n- Mean = 13.37 15 - Std. Dev. = 3.35 10- r -. 5 - o - .ir Tlnm-r^- ill 20 25 30 Age (y) Figure 13-5. Age frequency distributions of yellowtail rockfish (sexes combined) from three depth zones in Southeast Alaska. cies that composed 5% or more of the catch by weight (Rogers, Wangerin, and Rogers 1983). 'Dot/box' diagrams were also constructed to indicate the relative impact that predators had on their food sources. Seasonal food webs and diagrams for the rock/kelp hab- itat (trammel net) are shown in Figures 13-7 and 13-8. Fish were least abundant in the winter in all habitats and the amount of food in their stomachs was likewise the smallest during the winter. The more abundant species in the inter- tidal and shallow subtidal zones (rock, masked, and white- spotted greenling; and rock, yellowfin, and flathead sole) had generalized diets. Most of the crabs they consumed (e.g., Telmessus cheiragcmus, Pugettia gracilis, and Cancer oregonensis) were not commercially important species. Most of the fishes they consumed included Pacific sand lance, capelin, small cottids, gunnels (Pholididae), and pricklebacks. However, both rock and yellowfin sole also took juvenile Pacific cod, walleye pollock, and Pacific herring. Polychaetes were especially important in the diets of both the rock and the yellowfin sole; the rock sole took mainly motile forms (errantiates), whereas the yellowfin sole consumed more non-motile forms (sedentariates). Clam siphons were important to the diet of both the rock sole and the rock greenling during the spring. Gammarid amphipods were an important food for juveniles of nearly all of the benthic and intertidal fishes. The large cod, walleye pollock, great sculpins, yellow Irish lord, and the flathead sole consumed large numbers of both fish and shrimp. The great sculpin ate about 50% (by weight) of all the fish and crab that were consumed by the fishes that were sampled, while the Pacific cod consumed nearly 50% of the shrimp. These larger predators tended to stay in the deeper waters of the bays (otter trawl catches), The Nearshore Fishes 411 Figure 13-6. Habitat relationships of nearshore fish during summer. and their diets contained commercially important species of both shrimp (Pandalus borealis) and crab (Tanner, Chionoecetes spp.). However, king crabs — which constituted a greater proportion of the crab biomass (based on try net and otter trawl catches) — were relatively uncommon in the diets of the fish. They were perhaps too large to be eaten. The fishes that were preyed upon by those fish caught in the deep waters of the bays were similar to those consumed by the shallow nearshore fish (e.g., Pacific sand lance, cottids, capelin, and juvenile walleye pollock and flatfishes). Instances of cannibalism (adults eating juveniles) were com- mon but never constituted a major portion of their diets. Blackburn et al. (1983) examined —900 stomachs taken from 17 fish species that were collected in lower Cook Inlet. An additional 258 stomachs were examined by Dames and Moore (1983). The most common foods of non-schooling fishes were amphipods, brachyuran crabs, caridean shrimp, brittle stars, gastropods, and hermit crabs. Prey most com- monly taken by fish from rocky intertidal habitats were both epifaunal and were associated with macrophytes. Fish found over soft substrates consumed planktonic and benthic foods. Schooling species, such as juvenile salmon, herring, and Pacific sand lance usually ate planktonic orga- nisms, whereas non-schooling species either ate benthos or fish. Rosenthal (1983) examined 486 stomachs from 26 fish species caught in Prince William Sound and observed that bottom dwellers preyed heavily on benthic invertebrates such as gammarid amphipods, polychaetes, snails, shrimp, and crab. Pelagic fish ate more of the zooplankton and for- age fish associated with the water column than other types of food. There was considerable overlap in the diets, especially among the bottom feeders. The summer diets often common species of rockfish that were collected in the inshore waters of southeastern Alaska's outer coast during 1980 to 1982 were determined based on a collection of 1,030 specimens. Stomachs from about 62% of the specimens contained some food. Each of the species ate a variety of food items and usually capitalized on the most accessible prey. The bottom-dwelling species were highly dependent on detrital-based food sources, whereas more pelagic rockfish consumed substantial quantities of zoo- plankton and small schooling fishes. A number of food items such as crabs, shrimps, brittle stars, and fish were shared in common by the demersal rockfish, and dietary overlaps were strong. Pacific sand lance was the dominant food of the more pelagic black, yellowtail, and widow rock- fishes (Sebastes entomelas). Two other pelagic schoolers, the Puget Sound and dusky rockfishes, ate significant amounts of Crustacea and gelatinous zooplankton. Discussion The main concern for nearshore fishes in the Gulf of Alaska has been twofold: 1) their potential susceptibility to 412 Biological Resources Winter Spring Masked Greenling Hexagra m moi octogra tit m it* (lam siphon Figure 13-7. Food webs, by season, for fish caught by trammel net. environmental impacts (mainly petroleum-related), and 2) their economic importance. Therefore, the extensive, multi-gear studies have concentrated primarily on lower Cook Inlet and the Kodiak Archipelago, and our knowledge of the nearshore fishes throughout most of the Gulf remains relatively limited. The exception is for those commercially important species such as salmon, herring, and rockfish. Some large coastal areas such as the south side of the Alaska Peninsula and the coast between Southeast Alaska and Prince William Sound have not been investigated by multi- gear sampling. The nearshore fish assemblages of the Gulf of Alaska are composed of numerous species, many with widespread dis- tributions along the coast of North America. The fish fauna has been characterized as a mix of temperate and subarctic species (Quast and Hall 1972; Hart 1973). The greenlings, cottids, rockfishes, and flatfishes were the prominent large predatory fishes near shore, whereas Pacific sand lance, capelin, and juveniles of many species — including the Pacific salmon — were the prominent forage fishes. The rela- tive abundance of these species varied considerably among locations and the abundance of the forage fishes probably varies considerably from year to year. Interannual variation in abundance, however, is poorly documented and repre- sents the area of greatest need for future research in order to evaluate environmental impacts as well as to understand the dynamics of the nearshore communities. The Alaska Current and the Alaska Coastal Current con- stitute the major transport mechanisms in the Gulf of Alaska (Reed and Schumacher, Ch. 3, this volume). Both currents flow in a northerly direction off southeastern Alaska and then turn southwestward along the Alaska coast. Beyond Kodiak Island, the Alaska Current intensifies and becomes the Alaskan Stream as it flows along the Alaska Peninsula and the Aleutian Islands. The eggs, larvae, and juvenile stages of many inshore fishes may be transported by these currents (OCSEAP Staff, Ch. 14, this volume). Peden and Wilson (1976) found no distinct boundary for fish off north- ern British Columbia, and if such a barrier exists in the Gulf of Alaska, it is unknown. It would seem that the fish fauna of both the Pacific Northwest and the southern Alaska region are highly cosmopolitan. Visual investigation revealed that the fish fauna of the exposed rocky inshore zone of the Gulf of Alaska was domi- nated by greenlings, sculpins, ronquils, and rockfish. Pro- nounced differences in species composition and abun- dance were seen when the more protected areas such as bays, fjords, and lagoons were compared with areas exposed to wave action and strong currents. Large segments of the coastal area from Dixon Entrance to Kodiak Island are com- posed of rock substrates (O'Clair and Zimmerman, Ch. 11, this volume). The substrates of the more protected bays and estuaries of the Gulf — which are composed of sandy-silt, mud, and shell debris — contained fish assemblages that were numerically dominated by flatfishes, sculpins, and cod. During the summer months, more transitory schooling fishes such as Pacific salmon, herring, capelin, and sand lance enter these systems. Commercial fishing for stocks of shallow-water bottom- fish has been relatively light in the Gulf of Alaska, especially when compared with the more traditional fisheries for halibut, crab, and salmon. However, a new domestic fishery The Nearshorf Fishes 413 Rock Greenling Winter n Polychaetes • Nemerteans (Ham siphons • Snails • Shrimp • Crab • Fish • Other • Rock Sole Great Sc nl pin 3 Summer Gammarids Crab Fish Eggs Other Rock Greenling Masked Greenling VVhitespotted Greenling t i 9 • Spring Polychaetes Glam siphons Gammarids Crab Fish Other ock Greenling Masked Greenling Rock Sole Biomass of predator (kg) 2.5 prey (g) ^^ i-l 0 5 1-6.0 > 10 0 Rock Green ing Autumn Polychaetes • Snails • Gammarids • Crab • Fish • Other • Great Sculpin Masked Greenling Figure 13-8. Quantitative food diagrams, by season, for fish caught by trammel net. for rockfish and lingcod has developed off the coast of southeastern Alaska. In 1984, 3,520 mt (1.6 million pounds) of rockfish were caught in the directed nearshore fishery alone. Fish were caught using longline or hook-and-line gear, and self-imposed three-day trip limits were instituted to insure a high-quality product. The potential for expan- sion of the nearshore fishery has increased the need for more detailed scientific information in order to determine sustainable yields. While the bays and coastal waters of the Gulf of Alaska offer some potential for recreational and commercial fish- eries on nearshore fishes, their economic significance lies more in their importance as spawning habitats and rearing areas forjuveniles of other commercially important fish spe- cies. It is this aspect that makes the nearshore zone unique relative to the open waters of the Gulf of Alaska. Kodiak, Dr. Jon Houghton (Dames and Moore) in Coo Inlet, and especially Mr. Jim Blackburn (ADF&G) at botl places, for providing supervision of field work and analy; ing the data. Funding for the preparation of this manuscript was pre vided both by the Outer Continental Shelf Environments Assessment Program of the National Oceanic and Atmo; pheric Administration, Department of Commerce, throug] an interagency agreement with the Minerals Managemen Service, Department of Interior, and by the Pacific Seafoo< Processors Association. Mr. Marcus Duke helped with mar uscript preparation. Acknowledgments Our knowledge of the nearshore fishes in the Gulf of Alaska has benefited from the work of many biologists, stu- dents and fishermen; however, we would like to single out, and to acknowledge separately, Mr. Colin Harris (FRI) at 414 Biological Resources References Blackburn, J.E. 1979 Demersal fish and shellfish assessment in selected estuary systems of Kodiak Island. Research Unit 486. Environmental Assessment of the Alaskan Continental Shelf, Annual Reports of Principal Investigators 6(Biological Stud- ies):727-852. Blackburn, J.E. and P.B.Jackson 1980 Seasonal composition, abundance and food web relationships of principal juvenile and adult marine finfish species inhabiting the nearshore zone of Kodiak Island's eastside. Research Unit 552. Unpublished final report, Outer Continental Shelf Environmental Assessment program. Alaska Department of Fish and Game, Kodiak, Alaska. 101 pp. Blackburn, J.E., K. Anderson, C.I. Hamilton, and S.J. Starr 1983 Pelagic and demersal fish assessment in the lower Cook Inlet estuary system. Research Unit 512. Environmental Assessment of the Alaskan Conti- nental Shelf Final Reports of Principal Investigators 17(Biological Studies):107-450. Blankenbeckler, D. 1980 Gulf of Alaska herring management. In: Pro- ceedings of the Alaska Herring Symposium. February 19-21, 1980, Anchorage, AK. B.R. Melteff and V.G. Wespested, editors. Alaska Sea Grant Report 80-4, University of Alaska, Fairbanks, AK. pp. 55-62. Carlson, H.R. 1980 Seasonal distribution and environment of Pacific herring near Auke Bay, Lynn Canal, southeastern Alaska. Transactions of the American Fisheries Society 109:71-78. Clausen, D.M. 1983 Food of walleye pollock, Theragra chalcogramma, in an embayment of southeastern Alaska. Fish- ery Bulletin (U.S.) 81:637-642. Dames and Moore 1983 A preliminary assessment of composition and food webs for demersal fish assemblages in sev- eral shallow subtidal habitats in lower Cook Inlet, Alaska. Environmental Assessment of the Alas- kan Continental Shelf Final Reports of Principal Investigators l7(Biological Studies):383-450. DunnJ.R., A.W. Kendall, Jr., R.J. Wolotira, Jr., J.H. Bowerman, Jr., D.B. Dey, A.C. Matarese, and J.E. Munk 1981 Seasonal composition and food web rela- tionships of marine organisms in the near- shore zone - including components of the ichthyoplankton, meroplankton, and holo- plankton. Research Unit 551. Environmental Assessment of the Alaskan Continental Shelf, Final Reports of Principal Investigators 13(Biological Studies):357-776. Field, LJ. 1984 Bathymetric patterns of distribution and growth in three species of nearshore rockfish from the southeastern Gulf of Alaska. M.S. The- sis, University of Washington, Seattle, WA. 88 pp. Haldorson, L. and R.J. Rosenthal 1983 Development of a monitoring program for inshore bottomfish assemblages off south- eastern Alaska. Prepared for Alaska Council on Science and Technology. 85 pp. Harris, C.K. and A.C. Hartt 1977 Assessment of pelagic and nearshore fish in three bays on the east and south coasts of Kodiak Island, Alaska. Environmental Assessment of the Outer Continental Shelf, Quarterly Reports of Principal Investigators April-June 1:483-688. HartJ.L. 1973 Pacific fishes of Canada. Bulletin of the Fish- eries Research Board of Canada No. 180. 740 pp. Hubbard, J.D. and W.G. Reeder 1965 New locality records for Alaska fishes. Copeia 1965:506-508. Kendall, A.W., J.R. Dunn, A.C. Matarese, D.E. Rogers, and K.J. Garrison 1981 Taxonomic composition, seasonal distribu- tion, and abundance of ichthyoplankton in the nearshore zone of the Kodiak Archipelago, Alaska. Research Unit 551. Environmental Assess- ment of the Alaskan Continental Shelf Final Reports of Principal Investigators 13(Biological Stud- ies):777-842. Peden, A.E. and D.E. Wilson 1976 Distribution of intertidal and subtidal fishes of northern British Columbia and southeastern Alaska. Syesis 9:222-248. Quast, J.C. and E.L. Hall 1972 List of fishes of Alaska and adjacent waters with a guide to some of their literature. U.S. Depart- ment of Commerce, NOAA Technical Report NMFS SSRF-658. 47 pp. The Nearshore Fishes 415 Rogers, B.J., M.E. Wangerin, and D.E. Rogers 1983 Seasonal composition and food web rela- tionships of marine organisms in the near- shore zone of Kodiak Island — including ichthyoplankton, zooplankton, and fish. A report on the fish component of the study. Research Unit 553. Environmental Assessment of the Alaskan Continental Shelf, Final Reports of Prin- cipal Investigators 17(Bio logical Stud- ies):541-658. Rogers, B.J., M.E. Wangerin, K.J. Garrison, and D.E. Rogers 1983 Epipelagic meroplankton, juvenile fish and forage fish: distribution and relative abun- dance in coastal waters near Yakutat. Research Unit 603. Environmental Assessment of the Alaskan Continental Shelf Final Reports of Principal Investi- gators 17(Biological Studies):l-106. Rogers, D.E., D.J. Rabin, B.J. Rogers, K. Garrison, and M. Wangerin 1979 Seasonal composition and food web rela- tionships of marine organisms in the near- shore zone of Kodiak Island — including ichthyoplankton, meroplankton (shellfish), zooplankton, and fish. Research Unit 553. Environmental Assessment of the Alaskan Continen- tal Shelf Annual Reports of Principal Investigators for the year ending March 1979 4:529-662. Ronholt, L.L., H.H. Shippen, and E.S. Brown 1979 Demersal fish and shellfish resources of the Gulf of Alaska from Cape Spencer to Unimak Pass 1948-1976: a historical review. Research Unit 174. Environmental Assessment of the Alaskan Continental Shelf Final Reports of Principal Investi- gators 4(Biological Studies):580-669. Rosenthal, R.J. 1983 Shallow water fish assemblages in the north- eastern Gulf of Alaska: habitat evaluation, spe- cies composition, abundance, spatial distribution and trophic interaction. Research Unit 542. Environmental Assessment of the Alaskan Continental Shelf Final Reports of Principal Investi- gators l7(Biological Studies):451-540. Rosenthal, R.J. and L. Haldorson In press Northern range extensions of reef-dwelling fishes in the Gulf of Alaska. California Fish and Game. Rosenthal, R.J., L.J. Field, and D. Myer 1981 Survey of nearshore bottomfish in the outside waters of southeastern Alaska. Alaska Depart- ment of Fish and Game, Juneau, AK. 85 pp. Rosenthal, R.J., D.C. Lees, and D. Maiero 1982 Description of Prince William Sound shoreline habitats associated with biological commu- nities. Prepared for Department of Commerce, NOAA Office of Marine Pollution Assessment. 58 pp. Rosenthal, R.J., L. Haldorson, L.J. Field, T. O'Connell, M. LaRiviere, J. Underwood, and M.C. Murphy 1982 Inshore and shallow offshore bottomfish resources in the southeastern Gulf of Alaska (1981-1982). Alaska Department of Fish and Game, Juneau, AK. 166 pp. Tyler, R.W. 1972 Study of fingerling pink salmon at Kodiak Island with an evaluation of the method of forecasting based on townetting. In: Proceedings of the 1972 North East Pacific Pink Salmon Work- shop.].^. Bailey, editor. Information Leaflet No. 161, Alaska Department of Fish and Game, Juneau, AK. pp. 40-49. Wilimovsky, N.J. 1954 List of the fishes of Alaska. Stanford Ichthyological Bulletin 4:279-294. Marine Fisheries: Resources and Environments 14 OCSEAP Staff* Abstract Approximately 287 species of fish belonging to 55 families occur in the Gulf of Alaska. This chapter summarizes information relating to the abundance, distribu- tion, and life history aspects of the most important commercial species. Among those species considered here are Pacific cod, Pacific halibut, rockfish (with emphasis on Pacific ocean perch), sablefish, walleye pollock, Atka mackerel, lingcod, and herring. Commercial species of shrimp, crab, and squid are also discussed. Because commer- cial exploitation of these species has had major influence on fish stocks in the Gulf of Alaska, the development of fisheries for each of the stocks is described. Wherever pos- sible, descriptions of life history events are integrated with recently available oceanographic data. In many cases this has led to new hypotheses concerning the dis- persal and recruitment patterns that had been noted in past research. Introduction Beginning with the Outer Continental Shelf Environ- mental Assessment Program (OCSEAP) studies, marine investigations in the Gulf of Alaska came of age. For the first time, resources such as aircraft, large oceanographic and fishery research vessels, moored buoys and satellite-tracked drifting buoys, drift cards and bottom drifters, and a number of other resources and instruments were used to conduct by far the most extensive research on the northern Gulf of Alaska. OCSEAP was also the first broad-scale, long-duration, environmental study ever conducted in the area that did not use the commercial fisheries as a rationale. Historically, research resulting from such cruises as that of the U.S. Fish Commission's steamer Albatross at the turn of the century, studies by the International Fisheries Commis- sion (IFC) from 1927 to 1934, and studies by the Interna- tional North Pacific Fisheries Commission (INPFC) from the period between 1955 and 1965 (see Hood, Ch. 1, this vol- ume) were all dictated by interest in groundfish, Pacific halibut, or Pacific salmon. Little was accomplished in the decades between such investigations. In the early 1970s, the National Marine Fisheries Service (NMFS) established a comprehensive Marine Resources Monitoring, Assessment and Prediction (MARMAP) program in the northeast Pacific that contained strong environmental and fisheries oceanography components, but a lack of financial support prevented a long-term commitment to that program. Because the priorities of OCSEAP were dictated largely by specific oil-lease considerations, and its emphasis was on finding out which organisms were present within the lease areas at any given time, no broad-range fisheries oceanography studies were funded or carried out by that program. In spite of this, the interdisciplinary aspects of OCSEAP research led to an immense computerized data- base containing fish and environmental data. Using these data, it is possible at this time to present new information, new ideas, and even a few speculations concerning profit- able lines of both current and future analyses. We can also identify potentially rewarding avenues for future research. The complex interaction that exists between the ocean and its biota frequently obscures the effects that changes in the physical environment can have on both the distribution and the productivity of marine organisms. Although the cor- relation can sometimes be seen, more often the influence of environmental factors is ameliorated in terms of time, area, and intensity. This is true because the effects are manifested by way of complex biological processes which are collec- *This chapter was extracted by the editors from a larger document pre- pared under contract by Favorite Associates. Seattle. WA for the Outer Continental Shelf Environmental Assessment Program. As such, its emphases and content differ from those presented by the original docu- ment's authors. 417 418 Biological Resources lively described as ecosystem effects. Most events in fisheries oceanography, therefore, are not easily explained by simple cause-and-effect associations because the multifaceted rela- tionships mean that the effect either lags behind the cause or shows itself in an irregular manner. Nonetheless, both seasonal and interannual cyclic changes in oceanographic conditions can alter fish abundance by directly influencing factors such as behavior, growth, survival, and reproduc- tion, or the survival of eggs, larvae, and juveniles. Changing oceanographic conditions also indirectly influence abun- dance by affecting food or other habitat requirements. Phenomena such as El Nino demonstrate the economi- cally catastrophic consequences of dramatic reductions in the abundance or availability of commercially valuable resources. Declines in abundance result from undesirable changes in near-coastal conditions. These changes are thought to be related to variations in complex trans-Pacific Ocean currents which in turn are thought to be associated with changes in transoceanic surface-winds. Similar phenomena — albeit with less dramatic conse- quences— probably occur with regularity in the Gulf of Alaska and in other important North Pacific fishing areas. However, little emphasis has been placed on developing and testing hypotheses concerning the effects that the changing oceanographic environment has on resource dis- tribution, availability, and productivity. It is easy to pose questions that involve environmental considerations which go beyond the simplistic effects that air or water temperatures have on fish. For the Gulf, such questions include: • Why is there such a diversity of flatfish, but no domi- nant species (compared to the Bering Sea)? • Why are there juvenile halibut and sablefish in the Bering Sea but little or no evidence of eggs or larvae? Does the Gulf of Alaska sustain the Bering Sea stocks and, if so, where do the eggs originate and how are they transported? • What roles do sea-floor topography and near-bottom currents play in the distribution of groundfish, shrimp, and king and Tanner crab? What roles do the surface currents play in exchanges of eggs and larvae among stocks in Prince William Sound, in Cook Inlet, and in the Kodiak and Shumagin areas? • To what extent do the juvenile salmon that come from areas south of Yakutat transit the coastal areas in the northern Gulf of Alaska? How do environmental con- ditions affect seaward-migrating juveniles and shoreward-migrating adults? • How do currents affect invertebrate populations? Although OCSEAP-sponsored investigations were extensive, they were essentially discipline oriented and any fishery assessments were conducted independently from other oceanographic studies. As a result, no fish/environ- ment relationships were evaluated. However, it is obvious from the summaries of these investigations — many of which are chapters in this book — that new information has been obtained that bears both directly and indirectly on such fish/ environment relationships. The Gulf of Alaska (hereafter referred to as the Gulf) (see Hood, Ch. 1, this volume) is the eastern sector of the sub- arctic Pacific region and is part of the near-surface trans- Pacific subarctic gyre. This gyre extends from the northern Bering Sea to the oceanic subarctic/subtropic boundary near 40°N. Environmental conditions and processes in any given area in the Gulf are affected by pronounced seasonal cycles of insolation, wind stress, and coastal runoff. In addi- tion, exchanges of surface and deep water along the south- ern boundary and limited exchanges in Bering Strait also affect the environment (Dodimead, Favorite, and Hirano 1963; Favorite, Dodimead, and Nasu 1976). The Alaskan Gyre is the dominant oceanographic fea- ture in the Gulf of Alaska. However, this is not a simple rotary system such as those established by long-term cyclonic or anti-cyclonic winds, because major cyclonic sys- tems constantly pass through the area. Nor is it similar to gyres that are driven by constant zonal winds from opposite directions at different latitudes. These winds often drive flows that are constrained at east-west boundaries by land masses as in the case of major ocean gyres. Flow in the Gulf results when oceanic flows with north- ward components extending to depths below 1,000 m con- verge in the northeastern Gulf. Then, after interacting with flow on the continental shelf (above 200 m) and after being influenced by local wind stresses and extensive runoffs, these flows are discharged southwestward along the western boundary. While earlier investigations contain much perti- nent information on the oceanic area of the Gulf, it is in their direct observations of flow (although they were limited to the area over and adjacent to the shelf in the northern Gulf), that OCSEAP-sponsored studies have notably advanced our knowledge of Gulf oceanographic conditions. In the Gulf, there are ~ 287 fish species that belong to 55 families (Table 14-1). Sculpins (Cottidae) and snailfish (Cyclopteridae) represent l9 and 13%, respectively, of the total species numbers. Ten dominant families constitute about 68% of the total species reported by Quast and Hall (1972) (Table 14-2). Bottom sampling has captured 138 spe- cies representing 26 families (Ronholt, Shippen, and Brown 1978) — 39% of which were included in the ten largest fami- lies. Rockfish (Scorpaenidae) were the largest group, accounting for 10% (Table 14-2). Other family groups included the sculpins (8%) and flounders (Pleuronectidae) (6%). Several species found in the Gulf are of commercial importance. Of these, the Pacific cod (Gadus macrocephalus), Pacific halibut {Hippoglossus stenolepis), Pacific ocean perch (Sebastes alutus), sablefish (Anoplopoma fimbria), and walleye pollock (Theragra chalcogramma) are the five most important. In 1984, ~ 3.65 x 105 mt of demersal fish were landed. Bait and sac roe herring (Clupea harengus pallasii) also constituted very valuable landings. At least 3.07 x 104 mt of sac roe her- ring and 3.4 x 103 mt of bait herring were landed in 1982, having a value of $13.7 million and $958,000, respectively. The Gulf is the feeding ground for millions of fish. Among the salmonids, tagging has provided evidence that it is the principal feeding area for: 1) chinook salmon (Oncorhynchus tshawytscha) from the Columbia River, 2) all Marine Fisheries 419 Table 14-1. Fish families and ihe approximate number of genera and species reported from the Gulf of Alaska (from Ronholt, Shippen, and Brown 1978). Table 14-2. Proportion of the total species composition of Gulf of Alaska fish fauna that is contributed by the ten dominant fish families. Quasi and Haei MlSCEEEANEOl S Sl'RVE YN1' Famili Nimber Number oe Genera OF Spe< IES Nl'MBER >e Genera Petromyzontidac 2 Hexanchidae 1 I.amnidae 2 Carcharhinidae 1 Squalidae 2 Rajidae Acipenseridae Clupeidae Salmonidae 1 1 2 6 Osmeridae 5 Bathylagidae Opisthoproctidae Gonostomatidae 1 1 2 Melanostomiidae 1 Chauliodontidae 1 Alepocephalidae Anotopteridae Scopelarchidae Myctophidae Oneirodidae 1 1 1 7 1 Moridae 1 Gadidae 5 Ophidiidae Zoarcidae 2 6 Macrouridae 1 Scomberesocidae 1 Melamphaidae 3 Zeidae 1 l.ampridae Trachipteridae 1 1 Gasterosteidae 2 Scorpaenidae Hexagrammidae Anoplopomatidae Cottidae 9 3 2 30 Psychrolutidae 1 Agonidae Cyclopteridae Bramidae 8 12 1 Pentacerotidae 1 Sphyraenidae Trichodontidae 1 2 Bathvmasteridae 2 Anarhichadidae 1 Stichaeidae 10 Ptilichthvidae 1 Pholididae 2 Scvtalinidae 1 Zaproridae Ammodvtidae 1 1 Scombridae 2 Centrolophidae Bothidae 1 1 Pleuronectidae 15 Cryptacanthodidae' 2 Totals 167 3 1 2 1 2 7 2 2 12 6 4 1 4 1 1 1 1 1 1(1 3 1 5 2 11 3 1 3 1 1 1 2 22 6 2 54 1 12 38 1 1 1 2 4 1 15 1 4 1 1 1 9 1/ 2 287 1 15 8 5 15 2 84 Nl'MBER oe Species 30 5 1 24 9 7 16 2 138 ■ After Quast and Hall (1972). b Gulf of Alaska exploratory, BCF. IPHC. and NMFS trawl survey data. c Quast and Hall (1972) include these genera and species in the family Stichaeidae while Hart (1973) recognizes a separate family. Family' Pi rum m.i OF TOTAL msii spec n s 1- Will \ ' 1*1 KC I \ I U.I Ol TOTAL EISII SIM ( n s Cottidae Cyclopteridae Scorpaenidae Pleuronectidae Stichaeidae Salmonidae Agonidae Zoaricidae Myctophidae Rajidae Total 19 13 8 ti 5 4 4 4 3 2 68 Scorpaenidae Cottidae Pleuronectidae Agonidae Zoarcidae Cyclopteridae Stichaeidae Osmcridae Gadidae Hexagrammidae 10 8 6 3 2 2 2 2 2 2 39 •' From Quast and Hall (1972). b From Gulf of Alaska exploratory cruises and resource assessment surveys. species of salmon from British Columbia streams, and 3) all species of salmon from thousands of streams found not only in the western Gulf region, but in southeastern, north- eastern, and central Alaska as well. There is also evidence that sockeye salmon (O. nerka) from western Alaska, chinook salmon from the Arctic-Yukon-Kuskokwim area, pink (O. gorbuscha) and chum (O. keta) salmon from Kamchatka, and chum salmon from Hokkaido seasonally inhabit the western Gulf (French, Bilton, Osako, and Hartt 1976; Neave, Yonemori, and Bakkala 1976; Takagi, Aro, Hartt, and Dell 1981; Godfrey, Henry, and Machidori 1975; and Major, Ito, Ito, and Godfrey 1978). Greater detail on Gulf salmonids is given by Rogers (Ch. 15, this volume). Although numerous invertebrate species inhabit the Gulf, there is a paucity of knowledge regarding most of this fauna (Feder and Hoberg 1983; Feder, Paul, Hoberg, Jewett, Matheke, McCumby, McDonald, Rice, and Shoemaker 1981; and Feder and Jewett, Ch. 12, this volume). However, infor- mation is available concerning commercially important species (crabs, shrimps, and clams) and concerning the con- spicuous macrobenthic species (seastars and snails). Com- mercially important invertebrates represent ~ 13 species in five families (Table 14-3), including four crab species, eight species of pandalid shrimp, and one scallop species {Pecten caurinus). Shellfish landings from the Gulf in 1982 accounted for -4.93 x 104mt, with a value of $118.5 million. About 30 bird species can be found on a yearly basis in the Gulf (Gusey 1978; DeGange and Sanger, Ch. 16, this vol- ume). Approximately 340 colonies of seabirds have been identified and catalogued. Of these, 226 occur in the west- ern Gulf from the Kenai Peninsula to Unimak Pass. The seabird population in the western Gulf is estimated at five million individuals (Lensink and Bartonek 1976). Seabirds are a very important component of the Gulf ecosystem because they depend on land only for reproduction and subsist entirely upon food obtained from the sea. Therefore, they are predators as well as competitors for the commer- cially important fish. 420 Biological Resources Table 14-3. List of the commercially important invertebrate families and species collected in the Gulf of Alaska during exploratory cruises and resource-assessment surveys (from Ronholt, Shippen, and Brown 1978). A. Si lbNiinc Name Common Name Cancridae Cancer magister Inachidae Ckionoecetes bairdi Lithodidae Lithodes aequispina Paralithodes camtschatica Pandalidae Pandalus borealis Pandalus danae Pandalus goniurus Pandalus hypsinotus Pa ndalus jo rda n i Pandalus platyceros Pandalus montagui tridens Pandalopsis dispar Pectinidae Pecten caurinus Dungeness crab Tanner crab Golden king crab Red king crab Pink shrimp Dock shrimp Humpy shrimp Coonstripe shrimp Ocean pink shrimp Spot shrimp Sidestripe shrimp Weathervane scallop Twenty-six species of marine mammals have been identi- fied in the Gulf (Calkins, Ch. 17, this volume). Of these, sea otters (Enhydra lutris), Steller sea lions {Eumetopias jubata), harbor seals {Phoca vitulina), northern fur seals (Callorhinus ursinus) and belukha whales (Delphinapterus Imcas) appear at predictable times and places. Certain other whales, harbor porpoises (Phocoena Phocoena), and Dall porpoises (Pho- coenoides dalli) are present but are less predictable. Walrus (Odobenus rosmarus), right whales {Balaena glacialis), pilot whales (Globicephala macrorhynchus), white-sided dolphins (Lagenorhynchus obliquidens), and three species of beaked whales (Ziphiidae) are rare (Scheffer 1972). The total number of marine mammals entering or living in the Gulf has been estimated to be 90- to 100,000 (Gusey 1978). These mammals are estimated to consume 7.77 x 106 mt of bio- mass per year (Calkins, Ch. 17, this volume). Vertebrate Fisheries Demersal and Semi-Demersal Fishes Demersal fish spend most of their lives on or near the bot- tom and are caught by using bottom trawls or longlines. Their food in the adult stage consists primarily of benthos, as well as other demersal or semi-demersal fish. All flatfish (Family Pleuronectidae) belong to this group. Most of the larger gadoids such as the Pacific cod (Gadus macrocephalus) and the sablefish {Anoplopoma fimbria) are also semi-demer- sal fish. However, their larvae can be pelagic in the first year, although they settle to the bottom after metamorphosis (Fig. 14-1). In addition to feeding on or near the bottom, some demersal fish may also make daily feeding migrations throughout the water column. The pelagic larvae of demersal fish are subjected to large and sometimes rapid environmental changes resulting from temperature fluctuations and surface currents. For exam- Dispersal of larvae and early juveniles Pelagic shoaling of semi-demersal juveniles \ /Transport and y dispersal of eggs SettHng of juveniles " (Flatfishes) Spawning Life cycle migrations Spawning overwintering Growth (and food) affected by temperature Seasonal (feeding) migrations Shoaling M Dispersal of larvae (currents, turbulence) Active migration phase Maturation affected by temperature V Hatching (timing temperature dependent) Y Passive drift phase Drift of eggs Spawning Figure 14-1. Schematic diagrams of dynamic processes in the life cycle of demersal fishes that might be affected by the environment (A and B), and the effects of the environment (mainly current and temperature) on active and passive phases of their life histories (C). pie, the larvae and juveniles of some semi-demersal fish such as the Pacific hake can spend several years in the pel- agic realm where they feed on zooplankton, fish and shell- fish larvae, and juvenile fish. While there, they are at the Marine Fisheries 421 mercy of surface currents and may undergo long-distance passive migrations while being subjected to a variety of short-term, seasonal, and annual anomalies of the near- surface environment. In the adult stage, these fish return to the continental shelf and slope to feed and spawn where thev are caught by fishermen using otter trawls and longlines. Demersal fish are important to the Gulf ecosystem and include several groups or species (Table 14-4) that are of value to the United States' North Pacific fisheries. The Ber- ing Sea cod fishery and the United States/Canadian halibut longline fishery have been active since the latter half of the 19th century. The large oceanic fisheries in the eastern Ber- ing Sea and Gulf of Alaska, however, commenced on a mod- est scale in the mid-1950s. These fisheries were charac- terized by distant-water fleets of factory ships with accompanying trawlers, as well as by independent trawlers and longliners from Japan, the Soviet Union, and the Republic of Korea. These multinational fisheries expanded very rapidly after 1961 with their main target being the Pacific ocean perch (Major 1986) (Fig. 14-2 and Table 14-3). Total catch peaked at 3.71 x 105 mt, of which 3.49 x 105 mt was Pacific 400 — 300 200 Total catch Walleye pollock Pacific ocean perch Figure 14-2. Commercial catch data for Pacific ocean perch (Sebastes alutus) and walleye pollock (Theragra chalcogramma) from the Gulf of Alaska between 1958 and 1983. Table 14-4. Total foreign, domestic, and joint-venture catches (mt) of demersal fish from the Gulf of Alaska for the period 1958 to 1984. a Pacific Pacific Atka ocean Pacific Year Pollock Sablefish cod MACKEREL Flatfish PERCHb HALIBUTC Total 1958 14,570 14,570 1959 962 16,564 17,526 1960 1,348 15,512 16,860 1961 606 16,000 16,532 33,138 1962 684 62,000 17.610 80,294 1963 2,298 136,000 16,752 155,050 1964 1,126 2,214 243,400 17,185 263,925 1965 2,749 3,155 348,600 17,050 371,554 1966 8,932 4,565 200,800 17,038 231,335 1967 6,276 5,164 120,000 15,018 146,458 1968 6,194 13,998 100,200 14,007 133,399 1969 17.553 19,889 70,724 125,766 125,766 1970 9,343 21.766 40,386 91,395 91,395 1971 9,458 25,921 656 7,513,161 126,696 126,696 1972 34,081 36,505 3,573 7,611,734 163,493 163.493 1973 36,836 30,296 6,059 548,403 137,994 137,994 1974 61.880 26,550 5,251 17,531 51,000 4,593 166,805 1975 59,512 25,698 5,958 27,776 50,400 6,015 175,359 1976 86,527 27,514 6,524 20,032 45,500 6,334 192.431 1977 118,064 17,136 2,258 19,455 16,723 23,451 5,610 202.697 1978 97,470 8,866 12,163 19,588 15,171 8,179 5,584 167,021 1979 105,784 10,350 14,872 10,949 13,930 9,923 5.317 171.125 1980 115,037 8,543 35,322 13,166 15,846 12.471 5,553 205.938 1981 147,744 9,916 36,087 18,727 14,864 12,184 6,659 246,181 1982 168,746 8,556 29,379 6,760 9,278 7,993 8.314 239,026 1983 215,649 9,001 36,401 1 2,260 12,661 7,406 9.917 303.295 1984 306,693 10,230 23.219 1,153 6,879 4,452 12.008 364,634 •' Source: for the period 1958 to 1976 from Ito and Balsiger (1983); for the period 1977 to 1984 from Major (1986). b Source: Ito (1982). Excludes unknown catch by I'.S.S.R. c Source: International Pacific Halibut Commission Technical Report No. 14 for annual statistics for the period 1929 to 1975. Landings for the period 1975 to 1984 obtained from Annual Reports of IPHC. Catches indicated are from 1PHC Regulator)- Areas 3A and 3B (Cape Spencer to Cape Lutke). 422 Biolocicai Resources ocean perch. Landings declined to a minimum of 9.1 x 1()4 mt in 1970. The increasing trend in total landings after 1970 resulted from increased exploitation of walleye pollock, Pacific cod (beginning in 1971), and Atka mackerel (begin- ning in 1978). Although demersal fish in the Gulf are not as abundant as the\ are in the Bering Sea, where maximum annual catches have exceeded 2.2 x 106 mt ( ~ 2.0 x 106 mt of which were walleye pollock), demersal fish of the Gulf are closer to domestic markets and have considerable potential commer- cial value to a growing United States fishery. Further details regarding the history of the fisheries, the distribution of spe- cies, and the condition of the Gulf stocks can be found in Ito and Balsiger (1983). Pacific Cod (Gadus macrocephalus). Fifty years ago, the Pacific cod (Gadus macrocephalus) was considered a sub- species of the Atlantic cod {Gadus morhua), although it is now considered a separate species. The essential difference is that the eggs and larvae of the Pacific cod are demersal, whereas the eggs and larvae of the Atlantic cod are pelagic. The Pacific cod, which is known also as true cod, gray cod or just 'cod', was the target species of one of the oldest non- aboriginal fisheries of the west coast of North America. Although market demand has fluctuated considerably over the years, the demand appears to be increasing, and cod is a species of principal interest to the newly developing North Pacific trawl fisheries of the United States. Pacific Cod Distribution. Since 1981, commercial fishing and joint Japan/United States longline surveys (Bakkala, West- rheim, Okada, Zhang, and Brown 1981; Sasaki, Rodman, Onoda, and Rosapepe 1982) have provided considerable information regarding the distribution and relative abun- dance of Pacific cod. Although some cod were taken as deep as 500 to 600 m, they are most abundant at depths of less than 300 m, particularly at 100 to 200 m (Fig. 14-3). More details relating to the distribution and abundance of cod 170 60 can be found in Ito and Balsiger (1983), and in Bakkala and Low (1985). The bottom layer at the depths where cod are most often found (100-300 m) is not motionless, but circulates in approximately the same pattern as the surface layer, although friction may slow the speed of the bottom currents. It should be noted that 1) the currents (including the near- bottom currents) are stronger along the continental slope (where the cod spawn), and 2) they follow the contours of the slope. Therefore, we postulate that cod larvae are carried westward by bottom currents along the northern Gulf slope and are then dispersed over both the continental shelf and deeper waters when the larvae become more pelagic. According to this hypothesis, larvae from the Kodiak spawn- ing area will provide recruitment to the cod stock(s) in the Aleutian Islands, and to some extent, to those stocks in the southern Bering Sea. We hypothesize similar drift patterns for halibut larvae (see section on Pacific halibut) and for Pacific ocean perch, although the larvae of both these species are pelagic. The Kodiak stock must receive recruitment from spawning stocks along the coast further to the east and south. Some recirculation of the larvae caught in the gyre may be possible. Circulation time for the Gulf gyre might be of the order of 6 to 9 months (Reed 1980; Reed and Schumacher, Ch. 3, this volume). This much time may allow juvenile cod to attain a length of 11 cm and longer — the size at which they have been found in shallow-water exploratory surveys (Fredin 1985). Juveniles 6 to 10 cm long have been taken in shallow bays (< 20-m depths) both in the Gulf of Alaska and in Puget Sound. The results from trawl surveys that were conducted in the eastern Bering Sea suggest that juvenile cod gradually disperse offshore as they attain progressively larger size (Gunderson 1983). Pacific Cod Catch Statistics. The history of the United States cod fishery has most recently been summarized by Rigby 60 120 55 45 | Fishing area Spawning area Bering 170 45 160 150 Figure 14-3. Spawning and fishing areas for Pacific cod (Gadus macrocephalus). (1984). It began as a distant-water, sailing-vessel operation where United States fishermen exploited cod in the Okhotsk Sea during the years 1863 through 1909. Cod fish- ing in the Bering Sea began in 1864, and the pre-World War II cod fishery peaked in 1920 at 5.8 x 10;i metric tons. How- ever, poor market conditions reduced the catch to —1.0 x 10:1 mt by 1942, and then to less than 500 mt through 1950. No catches were made from 1951 through 1954. Marine Fisheries 423 The post-World War II Pacific cod fishery resumed in 1964 off the Aleutian Islands and in the Bering Sea. In 1971, it was extended into the Gulf by the distant-water, engine-powered vessels ofjapan. In the latter area, total for- eign catches increased from —6.50 x 102 mt in 1971 to —3.6 x 10' mt in 1981 (Table 14-5). The relative abundance of cod is indicated by the commercial landings: the Gulf catch of 3.6 x 104 mt in 1981 (Ito and Balsiger 1983) was 3.4 times as Table 14-5. The annual Gulf of Alaska Pacific cod catch (mt). Catch is shown by International North Pacific Fisheries Commission (INPFC) area for the period 1971 to 1981 as reported for Japan, U.S.S.R., Republic of Korea (R.O.K.), Poland, Mexico, the United Statesa, and U.S. -foreign joint venture1' (from Ito and Balsiger 1983.) 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 Japan Shumagin 119 167 329 689 1,451 1,542 377 4,073 3,067 6,624 9,032 Chirikof 57 83 957 614 746 492 296 3,537 5,598 1 7,403 1 1,807 Kodiak 262 453 972 1,185 694 760 457 971 1,414 4,551 2,334 Yakutat 23 70 332 440 362 479 285 199 294 1,961 1,517 Southeastern 0 43 15 44 27 35 13 66 55 43 78 Total 461 816 2,605 2,972 3,280 3,308 1,428 8,846 10,428 30,582 27,768 U.S.S.R. Shumagin 739 40 309 267 196 86 6 361 Chirikof 829 d 0 514 50 995 165 906 Kodiak1 176 2,696 1,732 2,096 2.226 1,520 279 60 663 675 Yakutat 95 d 16 694 0 0 1 Total 176 2,696 3,395 2,136 2,551 2,995 525 1,141 835 1,942 R.O.K. Shumagin Chirikof Kodiak Yakutat Total 1,361 8 1,369 788 56- 844 1,627 39 1,666 2,241 4,069 25 731 7,066 Poland Shumagin Chirikof Kodiak Total 14 14 9 118 127 9 46 55 41 94 135 Mexico Shumagin Chirikof Kodiak Total 100 376 463 939 U.S. Shumagin 36 2 1 13 53 64 70 238 Chirikof 1 42 52 16 167 267 49 38 Kodiak 12 10 28 71 40 96 140 443 606 415 679 Yakutat 2 10 8 6 2 27 4 2 Southeastern 7 15 31 67 34 52 55 107 85 190 30 Total 19 61 59 143 127 221 270 783 985 728 987 U.S. -Foreign Joint Ventures Shumagin 7 11 13 1 Chirikof 17 223 58 Kodiak 683r 230 Total 7 711 466 58 Grand total 656 3,573 6,059 5,251 5,958 6,524 2,223 12,160 14,869 35,439 36,014 Percent of total ground- -fish catch 0.5 1.8 3.4 2.6 3.3 2.2 1.2 7.4 9.1 17.0 15.1 1 Data supplied by Alaska Department of Fish and Game. •' Data source NMFS Foreign Observer Program (French, Wall, Berger, and Gibbs 1981). ' Reported as western Gulf in 1971 and 1972; includes Shumagin, Chirikof, and Kodiak INPFC areas. d Catch, if any, reported in Other Species category. <" Includes 7 mt from the Southeastern area. 1 Includes 0.6 mt from the Yakutat area. T = Trace amounts 424 Biological Resources large as the catch in the Aleutian Islands (1.05 x 104 nit) (Bakkala and Low 1985), but only 69% of the 5.2 x 104 mt catch from the eastern Bering Sea. Pacific Cod Reproductive Biology and Life History. Descriptions of both the life history and the biology of Pacific cod have been summarized by Gunderson (1983). Fredin (1985) has presented a comprehensive synopsis of the species. Pacific cod spawn off Vancouver Island in February and March as well as in Hecate Strait in March. They spawn at depths of from 100 to 150 m and at temperatures of 6 to 8C (Ketchen 1961; Westrheim 1977). Canadian research shows that both the size and the age at maturity increase in a north- ward cline. Off southern Vancouver Island, 50% of the pop- ulation matures at 50 to 53 cm (2-3 y) as compared to 53 to 56 cm (3-4 y) in Hecate Strait. Both the growth rate and the maturation of adult cod can be assumed to be a function of temperature. Canadian tagging studies indicate that the Pacific cod found off Washington and British Columbia migrate short distances and that the differences in both the growth rate and the size/age at maturation vary with latitude and tem- perature. These findings indicate that the Pacific cod is con- siderably less migratory than its Atlantic relative. Spawning cod have been taken from January through May off Siberia (Musienko 1970) and from January through March in the northern Bering Sea (Svetovidov 1948), whereas cod in spawning condition have been taken by thejapanese fishery southwest of the Pribilof Islands from late January through March and by United States fishermen from December through April in bays along the north side of Unimak Island as far as False Pass (Fredin 1985). Hirschberger and Smith (1983) reported finding cod in spawning condition along the outer edge of the continental shelf from Yakutat Bay to Chirikof Island (during February through July) in bottom-water temperatures of 4.5 to 5.9C. Although cod in spawning condition are rather ubiq- uitous in the region, very little is known regarding 1) their reproductive biology, 2) their fecundity or the ecology of their eggs, or 3) the ecology of the larvae and young juveniles (Gunderson 1983). The capture of significant numbers of cod larvae in the relatively enclosed waters of Puget Sound has been reported by Gunderson (1983). However, even though there have been numerous ichthyoplankton surveys conducted in the Gulf, no eggs or larvae have been found. In addition, only five larvae have been captured in the eastern Bering Sea (Waldron 1981), and these were found south of Nunivak Island near the 40-m contour. Pacific cod eggs are slightly heavier than seawater and are adhesive until they hatch. The timing of the various Gulf ich- thyoplankton surveys has included the period when cod eggs and larvae should have been present. The fact that they have not been found is attributable to the ineffectiveness of sampling for them in the upper water column using plankton and nekton nets. This suggests that the eggs and even the larvae develop very near the bottom at depths below those that were sampled. The selective advantage offered by adhesive eggs with negative buoyancy is not clear, but it may become more apparent as we learn more about the reproductive biology of cod and the ecology of their embryological development. Since we know from aquarium research in both Korea and Japan that cod eggs lose their adhesiveness shortly before they hatch (Fredin 1985), the fact that larvae are not captured in the water-column plankton tows is indirect evi- dence that both the eggs and the larvae remain in the bot- tom water layers. Staying near the bottom through the larval stage may have two selective advantages. First, the optimum tem- perature for cod egg development is 3 to 6C (the limits are 1 to 8C) (Fredin 1985) and lower winter temperatures occur in the shelf and slope areas where the cod spawn. The higher winter temperatures of this near-bottom environment might provide better growth conditions. Second, as cod lar- vae emerge at a very small size in early spring, they must have a ready supply of food. Food such as copepod eggs and early-stage nauplii can be found in the deeper layers during early spring, coincidental with emergence of the larvae. Pacific Halibut (Hippoglossus stenolepis). Pacific Halibut Distribution. The northern Gulf is not only an important nursery area for Pacific halibut eggs, larvae, and juveniles, it also provides habitat for local adults as well as for those transient adults that migrate into the area from as far west as Cape Navarin and from as far south as Santa Barbara (Skud 1977) — a range of several thousand kilo- meters (Fig. 14-4). The shelf-break environment throughout the range fre- quented by adults features conditions which are relatively constant all year around at any given depth. For example, at the 400-m contour, temperatures of 5 ± 1C are found with salinities of 34.1 ± 0.1°/oo and dissolved oxygen levels of 0.71 ± 0.35 mM/1. Even over the slope across the northern Bering Sea such values are not altered enough to preclude the sur- vival of larvae during a trans-Bering Sea migration. Halibut rise in spring from winter depths of 300 to 1,000 m, moving over the shelf edge to forage and even to enter the warm, dilute, coastal bays. Best (1981) has shown that in the southeastern Bering Sea, the on-shelf migration is retarded by bottom temperatures of near 0C that are caused by a winter turnover of the water column under the ice. However, in the Gulf, any extensive ice formation is lim- ited to the dilute, inshore areas such as Cook Inlet or to areas along the northern and western coasts where ice does not extend far seaward and is therefore not a major impediment to migration. Pacific Halibut Catch Statistics. The commercial fishery for Pacific halibut started in 1888 off Cape Flattery, expanded into the northeastern Gulf by 1913, and stretched into the western Gulf by 1921. Since 1924, the fishery has been man- aged by both the International Pacific Halibut Commission (IPHC) and its predecessor, the International Fisheries Commission (IFC). The total commercial catch in 1982 was 1.32 x 104 mt, compared to an average catch during the period from 1919 to 1928 of 2.27 x 104 metric tons. The 1982 catch had a dockside value of $32 million. The northern and the western Gulf management areas (designated 3A and 3B) constitute 49% of the halibut habitat in United States and Canadian waters. Kodiak and Seward were the primary and secondary unloading ports, respectively. Marine Fisheries 425 60 120 Figure 14-4. Distribution of tag recoveries from Pacific halibut (Hippoglossus stenolepsis) tagged off Yakutat. Number of fish tagged is shown in the boxes. (Modified from Skud 1977.) Halibut are long-lived, with those under eight years of age considered juveniles. Adults may live as long as half a century and weigh several hundred pounds. The IPHC adult surveys conducted in 1982 from the Canadian coast northward around the Gulf to the Shumagin Islands indi- cated a stock that averaged nearly 11 years of age and 13.2 kg in weight (females averaged about twice the weight of males). Most adults taken in the survey were caught at bot- tom temperatures that ran between 4.6 and 6.6 Celsius. Pacific Halibut Reproductive Biology and Life History. During the fall, halibut retreat back over the shelf edge as the onset of winter cooling and winter storm systems create increased turbidity over the sea floor and stir up unconsolidated sedi- ments over the shallow banks. This offshore retreat is also a prelude to spawning that occurs in winter at depths typically between 300 to 600 meters. The females release between 0.5- and 2.0 x 106 eggs, which are denser than the surround- ing water and hatch within several weeks. Environmental conditions play a major role in the survival of both the eggs and the larvae. Much of our present knowledge of the early life history of halibut in the Gulf stems from IFC studies (Thompson, McEwen, and Van Cleve 1936). However, laboratory studies indicate that halibut eggs will not survive to hatching at tem- peratures of 4C (Forrester and Alderdice 1973). This can be interpreted to mean that even in situ eggs and larvae are at risk at such temperatures — in which case, the western Gulf may be a hostile environment. Even though spawning 426 Biological Resources occurs in this general area (Best 1981) and eggs released in the Gulf may be advected here in great numbers, survival may be minimal. New information on the currents in this area indicates that the dispersal of both eggs and larvae in the Gulf may be more complicated than we previously assumed. Oceanographic Considerations. The first extensive oceanographic studies of the northern Gulf were conducted by the IFC during the winters of 1927, 1928, and 1929, in order to determine the drift of both halibut eggs and larvae (McEwen, Thompson, and Van Cleve 1930). An intense west- ward Gulf flow had been reported for over half a century in this area; the IFC studies (McEwen et ai, 1930, Thompson et al. 1936) showed that the maximum flow was indeed gener- ally westward around the Gulf (off Ocean Cape, Cape Cleare, and Cape Chiniak). The maximum speeds occur in a narrow band 50 km wide just seaward of the shelf edge that is usually bounded by weak easterly currents. The one exception — and an important one in terms of egg and larval drift — is the area off Cape Cleare where in 1929, larval drift was eastward and not westward, although the maximum flow still occurred at the shelf edge. In view of recent studies that reflect a general complex westward flow in this area, a closer inspection suggests that these station data are in error, although the irregular bathymetry in this area could be a factor. Perhaps the most ambiguous result in view of recent data is the fact that without exception, the IFC flow calculations show that low current speeds ( ~ 5 cm/s) are restricted to the upper 300 m and the calculations invariably show either no or very weak westerly flow ( < 2 cm/s) and even easterly flow adjacent to the slope between depths of 300 and 1,000 meters. These flow calculations imply little egg or larval drift unless the eggs or larvae were to rise above the 200-m contours. Particularly significant in this respect are the more recent direct current measurements that were taken at the shelf edge south of Cape Cleare between April 1976 and March 1977 (Niebauer 1981). These measurements (averaged velocity time-series data), indicated that there is a 19 cm/s (max. 58 cm/s) along-slope flow out of the northern Gulf in the spring at a depth of 273 meters. Summer and fall data indicate flows at depths of 278 m of 13.8 cm/s (max. 48.4 cm/s), and a partial winter record taken at 307 m indi- cates a flow of 33.5 cm/s (max. 65.3 cm/s). Near-surface speeds averaged —50 cm/s (on a bearing true of 198-207°) during the three measurement periods, with a maximum average speed of 133.5 cm/s occurring in spring. In addition, whereas IFC studies off Cape Chiniak indicated no flow within 50 to 100 m of the bottom in an area extending from the coast out over the shelf and down the slope to 800 m, a current meter moored at a depth of 100 m near the shelf edge (183 m) during the fall of 1975 recorded a mean speed over an 18-d period of 30.2 cm/s. Our new data come from direct current measurements rather than from geostrophic computations, which are invalid 1) in the presence of physical constraints such as bot- tom topography and 2) because they require a level of 'no flow'. (In the case of IFC data, no-flow is assumed to be at or near the bottom.) In light of the new data, it appears that flow over the slope in the northern Gulf is considerably higher than the IFC data indicated and, except for along-shelf perturbations, it is continually westward below 200 to 300 meters. One can safely assume a flow of 10 cm/s at 300 to 600 m — the depth range that both halibut eggs and larvae occupy from December to March. Eggs that are released in December in the northeastern Gulf drift westward along the slope, attaining larval stages and reaching a position seaward of Cape Chiniak by March. By this time, they would also have risen into the upper 100 m of the water column where they would encounter speeds of 50 to 100 cm/s in the Alaskan Stream (Favorite and Ingraham 1976). In the summer of 1978, satellite-tracked drogued buoys moved southwestward in this area at average speeds of 29, 15, and 27 cm/s (Reed 1980). If we accept a mean flow of 25 cm/s, by May when larvae are normally expected to have arrived in shallow water and metamorphosed to demersal fish, these larvae would either have been transported past Unimak Pass and out along the Aleutian Islands, or would have been recirculated into the Gulf. In the former case, three results can be anticipated (Fig. 14-5): 1) The larvae could settle on the bottom near any of the Aleutian Islands. 2) The larvae could move through deep passes at 170° W and eastward to the Bering Sea shelf by June (Favorite and Fisk 1971). 3) The larvae could move through Amchitka Pass (180° W) and then eastward to the southwestern Ber- ing Sea shelf, perhaps arriving near the Pribilof Islands by August (Favorite, Laevastu, and Straty 1977). In making such transits, the larvae will encounter tem- peratures of 3 Celsius. In the latter case, the southward displacement of larvae, which can occur at various locations, will result in recircula- tion into the Gulf. Recirculation in summer from south of Kodiak Island and from south of Unimak Pass to the north- ern Gulf — as demonstrated by satellite-tracked drogued buoys — requires four and six months, respectively, and an additional month to reach Kodiak Island (Reed 1980). Recirculation from south of the central Aleutian Islands to the coast of North America would require about 12 months — although such trajectories are largely hypothetical because Skud (1977) infers that an extended pelagic life for halibut larvae is unlikely. Thus it appears that any successful contranatant displacement of larvae must stem from eggs released over the mid-Gulf slope in winter and whose larvae have risen in the water column sufficiently to be advected across the ridge domain ( ~ 200 m) in a recirculation flow in February. Those larvae that endure the pelagic regime until June could survive, and during that time, they may be advected to the northeast Gulf shelf. Flow over the shelf is important to the larvae that have risen into the surface layer and require transportation into the coastal regime if they are to survive. Geostrophic calcula- tions of flow over the shelf (from IFC data taken off Ocean Cape, Cape Cleare, and Cape Chiniak in the winters of 1928 and 1929) reflected 1) low flows (2 to 10 cm/s), 2) a general flow trend toward the west, and 3) marked irregularities. Marine Fisheries 427 170 60 130 60 120 55 50 45 How along slo|><- Neai sui fa< <■ flow I'l.inkion travel time ia**^ 170 45 Figure 14-5. Locations of spawning areas and fishing grounds for Pacific halibut (Hippoglossus stenolepsis) (modified from St-Pierre 1984), and the estimated time (in days) required for plankton in the surface layer to travel between indicated points (based on data from OCSEAP satellite-tracked drogued buoys). Near-surface flow is based on geostrophic considerations. Opposing flows alternated seaward from the coast off Ocean Cape and Cape Cleare. The flows started westward inshore, then moved eastward, changed to westward, and subsequently headed eastward again near the shelf edge that liesjust inshore from the intense westward flows that are sea- ward of the shelf. The wide spacing between the lines of measuring stations made it impossible to determine any continuity between these flows or to find any possible eddy structures. However, the extensive IFC drift-bottle program from the period between 1930 and 1934 (Thompson et al. 1 936) clearly demonstrated that cross-shelf flow was a major feature in the northeast Pacific because onshore recoveries were made all along the coast from Cape Flattery to Unimak Pass after offshore releases. Vessel transits between northern ports consistently reflected an organized westward flow inside the shelf edge at the head of the Gulf. IFC drift-bottle data also provide addi- tional insight into the continuity of flow in this area. A drift bottle (#2219) that was released in March 1932 off the coast of the Queen Charlotte Islands had moved northward as far as Prince William Sound by June — traveling a distance of 1,220 km in 91 days for an average speed of 18 cm/s. Another drift bottle (#3806) released in January 1934 near the coast south of Ocean Cape (Yakutat) moved across the Gulf through Shelikof Strait to the west side of Kodiak Island — traveling a distance of 1,111 km in 78 days for an average speed of 19 cm/s. It is possible that the actual transit times could be much less and the speeds proportionately higher since it is possible the bottles are trapped in inshore oscillatory tidal flows. Larvae are not necessarily at the sea surface, however, and reduced speeds and even shifts in direction are possible at increased depths. Considerable advances have been made by using satel- lite-tracked drogue drift buoys for this research (Royer, Hansen, and Pashinski 1979). Three buoys were released — 100 km south of Yakutat in the summer of 1976. All three moved westward at speeds as high as 40 cm/s before moving into an eddy west of Kayak Island and then into Prince William Sound. Once they were in the Sound, one buoy cir- cuited the Sound clockwise in 20 days, suggesting that many of the drift bottles that were released offshore east of the Sound and recovered west of it may have completed the same circuit. The transit time required by the drift bottles to go from off Yakutat Bay to the exit of Prince William Sound was just under two months, whereas the satellite-tracked buoys (Reed 1980) moved from a nearly identical position off Yakutat Bay westward to a point south of Prince William Sound and then via the southwestward Kenai Current (Schumacher and Reed 1980) to Shelikof Strait in less than 30 days (December 17, 1978 to January 13, 1979). This means that it is possible for halibut larvae that are spawned at depths of ~ 500 m and at a distance of 800 km south of Yakutat off the Queen Charlotte Islands to move north at 10 cm/s to arrive in the northeastern Gulf in the upper 100 m of the water column by March. The larvae can then be trans- ported over the shelf edge into the coastal regime rather than being transported westward along the slope as planktonic organisms at depths below 200 m would be. Once in the coastal regime, they are dispersed throughout the northern and western Gulf before their metamorphosis occurs and they descend to the sea floor. Some drifting buoys have moved into Prince William Sound during the summer. In winter, one buoy moved west- ward south of Prince William Sound to a point west of Kodiak Island. Muench and Schumacher (1980) have shown that there is a wide dispersal both east and west of Kodiak Island based on drift cards they released northeast and southwest of the Island. Dispersal currents had velocities of between 10 and 30 cm/s in Shelikof Strait. Based on these 428 Biological Resources data, the dispersal of those halibut larvae that are ready to descend to the bottom throughout the shelf area as far south as Unimak Pass and the southeastern Bering Sea would require less than an additional month. Ingraham (1979) has shown that during late summer, the runoff from the Copper River could be traced for over 300 km to the southwest of Kayak Island. Runoff moved as far as the shelf break off Kodiak Island where it may have started to recirculate back to the northeastern Gulf. This pattern would agree with early IFC interpretation of drift-bottle data in the 1930s. However, such a flow is not clearly docu- mented at this time. Complex circulation in this area can be assumed because the flow over the slope turns southward as part of the Alas- kan Stream. In any event, it can also be assumed that any near-surface drogues or planktonic organisms, or even sur- face fish, may be carried southwestward across the shelf in such a system. But since dilute coastal flow and runoff from the Copper River is a summer or fall condition, it is unlikely that halibut larvae are present in surface flow at this time. In spite of the complexity and annual variability of cur- rents in the Gulf, recent direct current measurements have indicated 1) that there is a basic order to the flow in the northern Gulf, and 2) that there are subsurface flows over the shelf and slope that have much higher speeds than ear- lier data indicated. This gives rise to the general hypothesis that young-of-the-year halibut throughout both the north- ern and the western Gulf may originate from eggs that are released in the Queen Charlotte area, or just north of that area. Spawning in the northeastern Gulf near Yakutat would result in young-of-the-year being deposited along the Aleutian Islands as well as in the southeastern Bering Sea, but losses could be high. Spawning in the western Gulf could result in a contranatant transport of larvae east of Kodiak to the northeast Gulf, but larvae are probably advected along the slope to the extreme western Aleutian Islands where the cold temperatures (3C or less) could limit their survival. Rockfish (Scorpaenidae) The genus Sebastes of the family Scorpaenidae, is remark- ably diverse, and it includes —100 species worldwide (Chen 1971). Although a few species occur in the South Pacific Ocean, most inhabit the temperate North Pacific and North Atlantic Oceans. Sixty-five species have been recognized in the temperate North Pacific Ocean, whereas in contrast, only three or four species have been recognized in the North Atlantic Ocean (Taning 1949; Templeman 1959). Spe- cies diversity in the eastern North Pacific Ocean appears to be greatest between 34 and 38°N, with as many as 50 species found between these latitudes. Between 38 and 40°N, there is an abrupt decrease in diversity, with 12 fewer species found there, and north of 40°N, an average of one less species is found for every degree of latitude (Chen 1971). Alverson, Pruter, and Ronholt (1964) reported a decrease in species diversity from south to north and an increase in diversity with depth, with the maximum number of species encountered in trawl sur- veys at depths of between 183 and 256 meters. Thirty species have been captured in trawl surveys in the Gulf of Alaska (Ronholt et al. 1978). Quast and Hall (1972) reported eight species in the Bering Sea, although trawl surveys of the east- ern Bering Sea in 1980 captured only five of these species (Umeda and Bakkala 1983). Fifteen species have been identi- fied in the rockfish catches of the foreign fisheries in the Aleutian Islands/eastern Bering Sea slope, while an addi- tional 14 species were tentatively identified, but their iden- tity was not verified (Ito 1984). Considering the similarities in the apparent require- ments of the genus, it is curious that species diversity should be so much greater in the North Pacific Ocean. Chen (1971) considered geographic speciation as a partial explanation for the abundance of species of Sebastes in the North Pacific, also taking sympatric speciation into account. The fact that new species evolve through the shifting of their bathymetric preference or their association with different bottom types has been suggested by Barsukov (1964). Many authors have shown that each species of Sebastes has a characteristic depth range (Templeman 1959; Alverson et al. 1964; Chen 1971; Gunderson 1977; and Anderson 1984). Although rockfish can be found in a range of water tem- peratures at given depths (Gunderson 1977), they have been found at specific depths even when desirable temperatures prevailed in shallower waters (Templeman 1959). There is, however, overlap in the distribution of sympatric species which Chen (1971) attributes in part to younger fish in shal- lower waters mingling with adults of shallower-water spe- cies. The discreteness of the distribution of species by depth is further confused by the fact that the same species in differ- ent geographic locations may occupy different depth zones. However, it should be noted that rockfish also undergo diur- nal movement, albeit at relatively great depths. There is no apparent reason why these same mechanisms of geographic and sympatric speciation should not also apply to Sebastes of the North Atlantic. There are only four species of Sebastes in the North Atlantic and, although this genus is distributed from the northwestern areas to the Barents Sea, obviously, both geographic and sympatric spe- ciation occur to a lesser degree than in the North Pacific Ocean. The oceanographic structure of the North Atlantic may contribute to the difference because there is a greater seasonal turnover of the water column as evidenced by the near absence of a winter thermocline or its existence at great depth. There is also less salinity stratification and swifter currents (Dietrich 1965). Further investigation into the com- parative environments of Sebastes is required. Greater rockfish species diversity in the North Pacific Ocean than in the North Atlantic may also indicate that the species originated in the Pacific Ocean and has a consider- ably longer history there than in the Atlantic. If species diversity is considered a criterion for the antiquity of a genus, it might further be inferred that Sebastes first evolved in the eastern North Pacific Ocean in the area between 34 and 38° North. Barsukov's (1964) hypothesis concerning sympatric spe- ciation appears very reasonable inasmuch as the feeding habits of rockfish range from benthic to pelagic. Adult rock- fish characteristically inhabit the continental shelf edge and slope. There — within relatively short distances — large Marine Fisheries 429 changes occur in the light, the pressure, the temperature, and the salinity. In addition, as indicated by Anderson (1984), the currents are stronger along the continental slope, and may transport more pelagic food past a stationary, feed- ing, rockfish shoal. All rockfish appear to have an affinity for certain substrates, although as pelagic feeders, it is not readily apparent why the type of bottom would be a neces- sary condition for survival. The mechanisms for sympatric speciation in pelagic-feeding rockfish are not obvious, but they must be associated with either dines or discontinuities in pressure, light, temperature, and salinity. The species diversity within Sebasles, their bathymetric distribution, and the dominance of certain sympatric spe- cies (S. alutus, in particular) are of considerable biological interest. Further insights into these subjects will require a better understanding of their environment, including the nature of their niches and the niche diversity in their mid-water environment. The spatial and the bathymetric distribution of zooplankton and nekton and the diversity of herbivores must be determined, then linked to the specific specialization in rockfish foraging. Rockfish are an important component of the total demer- sal fish complex in all areas south of the Alaska Peninsula. Thev dominated the pre-fishery demersal fish community, particularly at depths between 183 and 274 meters. Their rel- ative importance generally declines 1) north of Cape Spencer, 2) on the inner shelf (< 183 m), and 3) at depths greater than 549 m (Alverson et al. 1964). Pacific ocean perch (Sebastes alutus) are the most abundant of these rockfish (Alverson et al. 1964; Pereyra, Reeves, and Bakkala 1976; and Ronholt et al. 1978). This species constituted 90% of the rock- fish catch in Canadian surveys in the Gulf from 1963 to 1966 (Westrheim 1970). The Pacific ocean perch has historically been an important target of both domestic and foreign trawl fisheries (Ito 1982, 1983). We emphasize Pacific ocean perch in this section because of their dominance among continen- tal slope rockfish, their commercial importance, and because of the knowledge we have of their distribution, abundance, and biology. Pacific Ocean Perch (Sebastes alutus). Pacific Ocean Perch Distribution. The Pacific ocean perch is broadlv distributed over the outer continental shelf and the slope of the Asian and North American continents (Figure 14-6). Adults are usually found in gravel, rocky, or boul- der-strewn substrates in and along the gullies, submarine canvons, and depressions of the upper continental slope (Alverson and Westrheim 1961). Both their larvae and their juveniles are pelagic and they join the adults in the demersal habitat after 2 or 3 years (Alverson and Westrheim 1961; Lyubimova 1964). Little is known of their distribution or movements before thev join the adult population. Pacific Ocean Perch Catch Statistics. The history of the exploitation of Pacific ocean perch is summarized in Figure 14-7. The fisherv commenced in about 1960 with the annual catch peaking in 1965 at —4.74 x 105 metric tons. There- after, catches declined sharply to recent levels of ~ 1.55 * 10 * metric tons. In 1977, catch limits were imposed under authority of the Magnuson Fisherv Conservation and Man- 150 180 150 120 I S.S.R. /^Nai.ir.n / Uuki I 60 i /i \ -V J J llrnnn V„ Fnl>ilol Is. / ommamlcr Is. *»'V \laska (Ml b< 45 Pat if,. Ocean ttv.V OH 30 l l i Lajm,'.. B0 45 180 150 Figure 14-6. Distribution of Pacific ocean perch (Sebastes alutus) in the North Pacific. (Modified from Ito 1982.) agement Act of 1976. The decline in the catch after 1976 is a consequence of this management action and may not reflect ocean perch abundance. There is no doubt, however, that in less than 25 years of exploitation, the once abundant Pacific ocean perch stocks of the eastern North Pacific Ocean have declined considerably. For a number of reasons, the pros- pects of any rapid return to former levels of abundance appear to be quite remote. The continued low productivity of Pacific ocean perch stocks in the Gulf (and elsewhere) is probably not attributa- ble to a single factor. Pacific ocean perch once dominated the biomass of the Gulf, indicating their high efficiency in competing for food. There is no obvious reason why this efficiency should be reduced simply because they are now less abundant. However, although there is little supporting evidence, predation by the increasing pollock population may contribute to the suppression of rockfish stocks. In addition to pollock predation, there is also evidence that chinook salmon may prey on both larval and juvenile perch. E 2 300 X 200 • • All regions — a — Gulf of Alaska —A— Aleutians ---«■■• Eastern Slope Ml / ' \\ 1 \\ 1 \\ 1 M 1 \ \ 1 \ \ //A A ?' ^ \ s. r P / V /•/ / hji 'o-fi"°~-o....o-~o- A. .a.. ^ ,,/cA '•<*. -<>•• 0- t .0. °— a— a- .A ■O....Q- ■» Tr--hi-.:W 1960 1962 1964 1966 1968 1970 1972 1974 1976 1978 Figure 14-7. Catch trends for Pacific ocean perch (Seba\tr\ ! in^ migration Autumn migration Nrnng Sea Figure 14-8. A. Seasonal distribution and migration of Pacific ocean perch (Sebastes alutus). (Modified from Lyubimova 1964.) B. Multi- ple aggregation and seasonal bath\ metric migration hypothesis of Fadeev (1968). overlap contribute to geographic phenotypic clines and to the frequency of the alleles observed by L.W. Seeb and D.R. Gunderson (University of Washington, unpubl. data)? It is also important to know how local rockfish aggrega- tions maintain their geographic position and how they avoid being transported westward along the axis of the Alaska Current. Contact with favorable substrate may help them with their orientation, but favorable substrate is more or less continuous throughout the Gulf. The continuity in Pacific ocean perch aggregations seems to bear out this contention. If local rockfish aggregations can be shown to be rela- tively stable in terms of their composition and their loca- tion, then perhaps the complex eddy system along the irregular coastline provides isolating barriers or oceanographic discontinuities which aid rockfish orienta- tion. This could be verified if a method were developed to capture and tag viable rockfish. In this regard, there is an indication that Atlantic redfish {Sebastes marinus) off the New England coast migrate from their 200-m daytime depth up to 80-m depths during the night (Templeman 1959). Assum- ing that the swim bladders of other marine teleosts can adjust in a manner comparable to perch when adapting to pressure changes, diurnal migrations involving more than a 50% pressure change are unlikely. At least one fisherman in British Columbia routinely cap- tures rockfish at great depths on handlines, transfers them to tanks, and then delivers them alive to market (M. Yesaki, 432 Biological Resources United Nations FAO, Sri Lanka, pers. comm.), Although the quantity of the catch may not be large, Yesaki's experience is clear evidence that rockfish can adapt to surface pressures if properly handled, and that the method should be investi- gated for its application to tagging experiments. Rockfish have adapted to a deep and stable environ- ment— an adaptation that has narrowed the limits of their tolerance to environmental changes. They are confined to certain mid-water depths, although they migrate vertically when they feed — a movement that is synchronous with the diurnal migration of euphausiids and copepods. Their lar- vae, however, are pelagic for several months and juveniles do not rejoin the demersal population until after two to three years (Alverson and Westrheim 1961; Lyubimova 1964). In surface waters, larvae are subject not only to currents which might sweep them out of the area but also to high tem- peratures that are imposed by seasonal increases in insola- tion. Evidently, both the location and the timing of larval release has been such that those larvae which are either retained or circulated in a favorable environment have been able to maintain a comparatively abundant resource. Chikuni (1975) suggested that the Aleutian Islands stock receives larvae from the Gulf of Alaska, and the Bering Sea stock receives larvae from both the Aleutian and the Gulf of Alaska spawners. These conjectures, although reasonable, are unverified. There are no quantitative estimates of how many larvae are retained within the territory of the parent aggregation and how many are transported out of the area. If the genetic component of a population outweighs the environmental component, then the retention of aggrega- tional traits such as maximum age, size at age, and age at maturity is evidence that most of the larvae ultimately settle in the habitat of the parent population. Conversely, any sub- stantial transportation of larvae to downstream populations would ultimately alter the genotypic structure of those down stream stocks. Sebastes have adapted to a narrow range of cool tem- peratures. Reported optimum temperatures for redfish in both the Atlantic (Taning 1949; Templeman 1959; and Anderson 1984) and in the Barents Sea (Veshchezerov 1944) were from 3 to 8C. For Pacific ocean perch, optimum tem- peratures ranged from 1 to 9C. However, like the redfish of the Atlantic, optimum temperatures for Pacific ocean perch appear to be in the 3 to 8C range, with the higher tem- peratures pertaining to the Vancouver/Oregon stocks (Lyubimova 1965; Snytko 1971; and Pautov 1972). Larvae are released in late spring and summer and have a pelagic existence when sea surface temperatures undergo rapid heating due to both increased insolation and air tem- perature. For redfish, S. marinus, of Flemish Cap (east of Newfoundland's Grand Banks), Anderson (1984) found that high temperatures reduced growth rates, and that slow growth rates during the warm years were accompanied by an increase in larval mortalities. Anderson (1984) also noted that bottom temperatures of less than 2C adversely affect redfish when they become benthic. Whether this is true for Gulf rockfish is unknown. However, the Pacific ocean perch releases its larvae in the Alaska Current during April and May. These larvae would be transported westward where water temperatures decrease even as seasonal warming of the atmosphere occurs. Although egg fertilization and embryological develop- ment occur externally for many marine fish, rockfish are ovoviviparous and release yolksac larvae. There is very little known regarding the time and place of mating for most spe- cies. The stock structure at mating is also not understood. Neither is it known whether the species is polygamous or polyandrous. Knowledge concerning the latter may be per- tinent to the management of species such as Pacific ocean perch where sexes may be segregated except during mating and where exploitation might be highly selective for one sex over the other. Because Pacific ocean perch are ovoviviparous, both their eggs and their embryos are protected from the exter- nal environment and from predation. Larval mortality, however, is apparently quite substantial because fecundity is high. Fecundity estimates range from 1.0 x 104 to 3.0 x 105 eggs per gravid female (Ito 1982). These estimates are, however, much less than for species such as yellowfin sole, Limanda aspera (1.3- to 3.3 x 106 eggs), Pacific cod, Gadus macrocephalus (2- to 6 x 106 eggs), sablefish, Anoplopoma fimbria (8.2 x 104 to 1.3 x 106 eggs), or Pacific halibut, Hippo- glossus stenolepis (1.01 x 105 to 2.8 x 106 eggs), which all extrude eggs into the sea for fertilization. Not all rockfish eggs develop into larvae; some are used as an energy store. Anderson (1984) estimated larval survival for Flemish Cap redfish at less than 1% between April and July. Such high larval mortality is typical for marine fishes. Comparable larval mortalities have been calculated for cod, plaice, and herring (Cushing 1974), and for North Sea plaice (Bannister, Harding, and Lockwood 1974). On the basis of this limited evidence, starting life as a yolksac larva appears to have no obvious survival advantages. The fecundity of Gulf Pacific ocean perch is lower than fecundity for either the eastern Pacific or the Aleutian Islands/Bering Sea stocks (Fig. 14-9, top). This suggests that the natural mortality rate is lower for the Gulf stocks. Para- doxically, the growth rate for the Gulf stocks is also lower (Fig. 14-9, bottom) suggesting a higher natural mortality rate — if we assume that the growth rate is directly related to survival. In spite of the evidence that points to a lower fecun- dity and a slower growth rate, the Gulf stocks were over- whelmingly dominant during the early fishery (1963-1968) and remain dominant, although at much lower levels. The dominance of the Gulf stocks, in spite of their lower fecun- dity and growth rates, raises three basic questions: 1) Does the total area encompassed by the continental slope and edge in the Gulf exceed the area of other regions enough to explain this overwhelming domi- nance? 2) Is there less predation? 3) Do catch statistics reflect both the availability and the trawlability of the Gulf rather than reflecting the abun- dance of Pacific ocean perch in the area? The comparatively slower growth rate for Gulf Sebastes alutus appears to be manifest after the onset of maturity. The growth rate prior to maturity, when natural mortalities can Marine Fisheries 433 c a (a 3 O u bu 0 x 300 250 200 150 100 20 5 10 15 Age (vr) Eastern Pacific (Dixon Entrance to California (Alverson and Westrheim 1961) Bering Sea (Paraketsov 1963) Gulf of Alaska (Lisovenko 1965) 25 i<;uu ..-• _1000 be jjj 800 / -J 600 S 400 200- yy .^ I I I I 10 15 20 Age (yr) 25 Eastern Pacific (Westrheim 1973) ■ Bering Sea (Chikuni 1975) Gulf of Alaska (Chikuni 1971a) Figure 14-9. Comparisons of age versus fecundity (top) and age versus length and age versus weight relationships (bottom) for Pacific ocean perch (Sebasles alutus) from three regions of the North Pacific. (Adapted from Chikuni 1975.) be expected to be the highest, is both rapid and similar for all stocks. It may be, therefore, that the comparatively lower, postpubescent growth rate for Gulf stocks does not signifi- cantly impact their relative productivity. Sablefish (Anoplopoma fimbria). Sablefish Distribution. Adult sablefish are found along both the shelf edge and the continental slope from Mexico around the Pacific rim to Japan (except for the Sea of Okhotsk). They inhabit depths between 150 and 1,200 m, (predominantly between 400 and 500 m), and have been caught by trawl, longline, and pot. About 75% of the sablefish biomass is found between Vancouver Island and the Aleutian Islands. Tagging studies have indicated that they make long migrations that cross the Gulf in both east- erlv and westerly directions (Fig. 14-10). Environmental conditions such as temperature, salinity, and oxygen level over the slope are quite uniform at corresponding depths throughout their distribution range and do not pose any barriers to the adult migrations. Sablefish Catch Statistics. The sablefish or blackcod fishery began over a century ago off the Washington-British Columbia coast, primarily incidental to halibut catches. It expanded to include California and Alaska during the first 25 years. Exploitation was limited to Canada and the United Slates, and annual catches remained at about 1.5 x 10'' ml until the 1960s. After that, foreign fishing resulted in a marked rise in the catch. Recent summaries of sablefish research have been presented by Low, I anonaka, and Ship- pen (1976), Balsiger (1983), and Sasaki, Rodman, Onoda, and Rosapepe (1984). After Japan entered the Gulf sablefish fishery in 1963, the catch increased from 2.3 x 103 mt to a maximum of 3.65 x 101 mt in 1972, when over 95% of the catch was taken by Japanese vessels (see Table 14-4). As other nations such as Russia and Korea joined the fishery, regulations were applied and catches for the period from 1978 to 1982 aver- aged about 9 x 103 metric tons. By 1982, a quota of 8.23 x 103 mt was in force. In the early 1970s, the average United States catch of about 1.5 x 103 mt was used as follows: • industrial 3% • food 97% (smoked 77%, fillet 16%, salted 6%, and pickled 1%). The domestic catch had a value of $3.8 million (Low et al. 1976). This suggests the peak catch in the Gulf area in 1972 had a potential value of nearly $1.0 billion. Sablefish Reproductive Biology and Life History. Little is known about sablefish spawning migrations or about the time associated with their egg and larval development. We do know that spawning occurs during the winter at depths of between 250 and 750 m, and occurs rather ubiquitously throughout the distribution area (except in northern Bering Sea). The demersal larvae must adjust to vastly different pel- agic and inshore environmental conditions in the surface layers where they occupy depths down to 150 meters. The juveniles range in age from one to four years. Although little is known about their movements during this period, they tiering Sea • Release area — *■ West-to-east migration •* — East-to west migration Figure 14-10. Release and recovery locations of tagged sablefish {Anoplopoma fimbria) for long migrations across the Bering Sea and the northeastern Pacific Ocean. (Modified from Low, T anonaka, and Shippen 1976.) 434 Biological Resources are present around the periphery of the Gulf. The fishery concentrates on fish between three and eight years of age, even though adults may live longer than 20 years. Both the spawning activities and the widespread adult migrations bear a certain likeness to those of halibut. How- ever, the sablefish larvae do not require a substrate for sur- vival for the first year, but instead, are pelagic. Therefore, one would expect that those larvae that develop from eggs that have been released seaward of the shelf in the Gulf would be transported by the Alaskan Stream. According to Kodolov (1968), sablefish larvae are found over the slope from California to the southeastern Bering Sea shelf, as well as westward from there in a trans-Pacific latitudinal band (from 3 to 5° wide) between the Alaska Peninsula and the southeastern end of the Kamchatka Peninsula, including portions of the Aleutian Islands. Much of the latter areas encompass a pelagic regime that is under the influence of the Alaskan Stream. The apparent absence of larvae in the Bering Sea north of ~55°N (particularly on the eastern side) suggests two things: (1) there is a low threshold temperature ( ~ 2C) for sablefish eggs and larvae, and (2) the presence of sablefish along the Asian shores is dependent on, or at least enhanced by, spawning activity in the Gulf of Alaska. Although a large proportion of the eggs released in the Alaskan Stream in winter will recirculate in the Gulf as larvae (as indicated by the halibut larvae), some will also be transported westward along the Aleutian Island chain into the vicinity of the Com- mander Islands by spring and summer. These larvae will metamorphose into juveniles prior to winter cooling and will have access to the currents associated with the western subarctic gyre (Favorite et at. 1976). Any subsequent move- ment must be understood before an effective management plan can be devised or before the effect that the Gulf environment has on sablefish can be properly assessed. Walleye Pollock (Theragra clialcogramma). Walleye Pollock Distribution. The walleye or Pacific pollock is a cod-like species which is broadly distributed through- out the subarctic North Pacific Ocean and adjacent seas (Fig. 14-11). It can be found in depths ranging from near the ocean surface to the ocean bottom in waters over the conti- 70 60 40 nental shelf and slope. It also inhabits both surface and intermediate waters over the very deep Aleutian Basin in the Bering Sea (Okada and Yamaguchi 1983) and the Aleu- tian Trench (Larkins 1964) and it appears to prefer lower temperatures. In waters off the Korean Peninsula, pollock is generally found at temperatures between 2 and 5C, but is never found in the Yellow Sea where other subarctic species such as the Pacific cod and the Pacific herring occur year round (Gong and Zhang 1983). Walleye Pollock Catch Statistics. Throughout most of its range, the pollock is the dominant fish species. It has, in recent years, surpassed the Peruvian anchoveta and the Atlantic cod in terms of total world catch. The world catch of walleye pollock was 6 x 106 mt in 1973, but has since declined to less than 5 x 106 mt (Bakkala, Maeda, and McFarlane 1984) (Table 14-6). In spite of this decline, it has remained at the top (4.5 x 106 mt), exceeding catches of the Japanese pilchard, the second most productive fishery, by almost 0.5 x 106 mt in 1982 (Fishing News International, August 1984). The commercial use of pollock dates back to the 17th cen- tury in Korea (Gong and Zhang 1983); substantial fisheries for other pollock stocks did not develop until considerably later. Asian landings constituted —60% of the total for the years 1970 to 1972 (Table 14-6), and made up more than 70% (max. = 78% in 1978) after 1972. East of 175°W, landings from the Bering Sea have dominated the fisheries (99% in 1970 to 81% in 1982) (Bakkala et al. 1984). Pollock exploitation in the Gulf began in 1962 when it was taken incidentally by foreign fisheries which were then catching Pacific ocean perch. Prior to 1972, pollock were taken in intermittent directed fisheries by the Japanese or were taken as by-catch in both the Japanese and the Soviet rockfish fisheries (Alton and Deriso 1983). In 1972, the pol- lock catch increased abruptly to 3.4 x 104 mt and has been about 1.0 x 105 mt since 1976 (Table 14-7). Most of the catch in recent years has been taken west of 147° W in the central and western Gulf, with the largest landings coming from the Kodiak area (Fig. 14-12). Until very recently, almost all of the pollock taken in the eastern North Pacific Ocean and Bering Sea was taken by foreign vessels. This situation has changed dramatically and Table 14-6. Catch ( x 103mt) of walleye pollock (Theragra chalcogramma) from both the western and eastern Pacific for the period 1970 to 1980 (from Bakkala, Maeda, and McFarlane, 1984). Year Western Pacific: Eastern Pacific Totai. Figure 14-11. Distribution of walleye pollock (Theragra chal- cogramma) in the North Pacific. (Adapted from Bakkala, Maeda, and McFarlane 1984.) 1970 1,984.3 1971 2,685.1 1972 2,862.5 1973 4,227.3 1974 4,204.8 1975 4,356.1 1976 4,458.9 1977 4,116.9 1978 3,752.6 1979 3,693.4 1980 3,193.3 1,266.2 3,250.5 1,756.5 4,441.6 1,910.3 4,772.8 1,806.3 6,033.6 1,673.1 5,877.9 1,430.2 5,786.3 1,270.0 5,728.9 1,107.5 5,224.4 1,085.8 4,838.4 1,032.4 4,725.8 1,135.7 •4,329.0 Marine Fisheries 435 Table 14-7. Total trawl catch (ml) and pollock landed (ml) in both the eastern Bering Sea (EBS) and Gulf of Alaska (GA) since 1964. Eastern Bering Sea Gulf of Alaska6 GA/EBS Yeas Toi u POLl ()( K % Poll ()( K Toi A] Pollock % Pot IOC K 1 i)l VI Pol 1 ()( K 1964 393,891 171.792 0.44 263,925 1,126 0.00 0.67 0.01 1965 344,369 230.551 0.66 371,554 2,749 0.01 1.08 0.01 1966 452.081 261,678 0.57 231,335 8,932 0.04 0.51 0.03 1967 836.308 551,562 0.66 146,458 6,276 0.04 0.17 0.01 1968 977,083 702,181 ().7I 134,399 6,164 0.05 0.14 0.01 1969 1 . 1 92,020 862,789 0.72 125,766 17,553 0.14 0.11 0.02 1970 1,593,649 1,265,565 0.79 91.395 9,343 0.10 0.06 0.01 1971 2,157.320 1,743.763 0.81 126,696 9,458 0.08 0.06 0.00 1972 2,249,092 1.874.534 0.83 163,493 34,081 0.21 0.07 0.02 1973 2,064,444 1,758,919 0.85 137,994 36,836 0.27 0.07 0.02 1974 1,900.092 1,588,390 0.84 166,805 61,880 0.37 0.09 0.04 1975 1,645,232 1,356,736 0.82 175,359 59,512 0.34 0.11 0.04 1976 1,428,575 1,177,822 0.82 192,431 86,527 0.45 0.13 0.07 1977 1.173,457 978,370 0.83 202,011 118,064 0.58 0.17 0.12 1978 1.312,030 979,431 0.75 169,749 97,470 0.57 0.13 0.10 1979 1,167,404 913,881 0.78 172,022 105,784 0.61 0.15 0.12 1980 1,221.914 958,279 0.78 211,242 115,037 0.54 0.17 0.12 1981 1,260.297 973,505 0.77 253,829 147,744 0.58 0.18 0.15 1982 1,212,045 955,964 0.79 236,095 168,746 0.71 0.19 0.18 1983 1.276,061 982,363 0.77 299,446 215,649 0.72 0.23 0.22 1984 1.457.601 1,098,783 0.75 356,311 306,693< 0.86 0.24 0.28 J Bakkala and Low (1984). bIto and Balsiger (1983). c Major (1986). 170 60 60 120 55 Bering Sea jf*& 50 Figure 14-12. Principal regulatory fishing areas and total foreign catch for walleye pollock (Theragra chalcogramma) during the period 1977 to 1981. (Adapted from Alton and Deriso 1983.) it is expected that eventually the United States trawl fishery will catch most, if not all, of the harvestable surplus of wall- eye pollock in the eastern North Pacific Ocean and Bering Sea (Hughes and Draves 1984). In addition to their immedi- ate importance to the developing United States fishery, pollock are so abundant and broadlv distributed that thev constitute a very significant component in the dynamics of the subarctic region's ecosystem in their roles as prey, com- petitors, and predators. Their recent proliferation in the Gulf and the corresponding interest in their exploitation have raised a number of questions relating to the biology and management of this resource. Many of these questions can only be answered through a better understanding of the interaction between pollock and the oceanography of the area. Both the catch statistics and survey information for pol- lock indicate that their abundance in the Gulf has increased since the mid- and late 1960s (Ronholt et al. 1978). Surveys 436 Biological Resources conducted in the mid-1970s indicated abundance increases of several orders of magnitude (Alton 1981). This increase is reflected in landings that increased from less than 1.0 x 10 ' mt for 1970-1971 to more than 1.3 x 105 mt for 1981. Consid- ering both the overlap in the depth distribution and the prev spectra for pollock and Pacific ocean perch, Alton (1981) associated the increase in pollock to the overexploita- tion of the perch. There is, however, no direct evidence that pollock displaced the diminished Pacific ocean perch stocks or that the proliferating pollock population has contributed to the suppression of the Pacific ocean perch resource. Alton's (1981) hypothesis infers that the sudden increase in the pollock population resulted because they used both the space and the prey which became available when a sub- stantial biomass (2- to 3 x 105 mt) of Pacific ocean perch was removed. Removing that many perch has undoubtedly severely depleted and depressed the perch population and should make food available to pollock which would have been consumed by the perch. This cannot, however, explain the proliferation of pollock in the Gulf unless it can be estab- lished that competition with perch for food had limited the pollock productivity before large numbers of Pacific ocean perch were removed. Pacific ocean perch and pollock may compete for prey because euphausiids and copepods are important in the diets of both species. However, Pacific ocean perch are far more specialized feeders and depend upon these zoo- plankton through adulthood. Copepods and euphausiids (particularly the latter) are also consumed by pollock. How- ever, as pollock grow, their diet shifts to fish (mostly other pollock), as well as to shrimp and crab (Takahashi and Yamaguchi 1972). Furthermore, copepods and euphausiids (and their eggs and larvae) are consumed not only by Pacific ocean perch and pollock, but also by many other marine fishes and organisms. There is no direct evidence that the abundance of zooplankton has limited the productivity of any fish stocks in the North Pacific Ocean. Estimates indi- cate that the annual zooplankton production far exceeds its consumption by predators (Laevastu and Larkins 1981). It is not known whether pollock in the Gulf constitute one or several stocks. On the basis of differences in the rela- tive abundance of two principal year-classes, Hughes and Hirschhorn (1979) hypothesized that stocks were separate for areas east and west of Kodiak. Somewhat in support of the two-stock hypothesis, Grant and Utter (1980) found pol- lock of the western Gulf to have a closer biochemical affinity to Bering Sea pollock than to those from areas south and east of Kodiak Island. However, other evidence indicates that pollock in the Gulf are essentially a single stock (Strick- land and Sibley 1985). Data from acoustic surveys conducted during 1981 in the Shelikof Strait area indicated that the spawning aggrega- tions totaled 2- to 4 x 106 individuals (Alton and Deriso 1983) — a number that is equivalent to the estimated stand- ing stock of pollock from Kodiak to the Shumagin area. The fisheries, the trawl surveys, and the ichthyoplankton surveys that all took place at roughly the same time indicated, how- ever, that spawning pollock also occurred outside the Kodiak area. Shortcomings in both survey and analytical methodology make present stock abundance and condition estimates pro- visional. The evidence indicates, however, that pollock in the Gulf of Alaska have continued to increase through the 1984 season. The trends indicate an increase in the exploita- ble biomass as well as surplus production. The average bio- mass of the exploitable stocks ranges from 5.9 x 105 to 1.5 x 106 mt and the surplus production ranges from 1.8- to 5.1 x 105 metric tons. Equilibrium yield (for the period from 1976 to 1980) has fallen within the range of surplus produc- tion (Alton and Deriso 1983). As is the case with most marine fish species, the natural mortality rate for Gulf pollock has not been reliably ascer- tained. However, mortality estimates range from 0.20 to 0.43. The stock has been conservatively exploited, with annual fishing mortality ranging from 0.16 in 1976-1977 to 0.07 in 1981, for an average mortality of 0.13 for the 6-year period (Alton and Deriso 1983). Data from one United States/Japan joint-venture pollock fishery in the Shelikof area in 1984 indicate that the fishery was primarily supported by 3-, 5-, and 6-year-old fish from the 1981, 1979, and 1978 year-classes. The 1980 year-class of 4-year-olds was very poorly represented in the landings, although the 1981 year-class appeared to be reasonably abundant (Hughes and Draves 1984). Walleye Pollock Reproductive Biology and Life History. Pollock are found in spawning condition throughout the Gulf and their eggs and larvae may be encountered at almost any time of the year. Zooplankton studies by Kendall, Dunn, and Wolotira (1980) indicated that pollock eggs were concen- trated toward the southern end of Kodiak Island and near Shelikof Strait during the fall, spring, and summer. Large aggregations of spawning pollock occur in specific places during the spring months (Fig. 14-13), with the Shelikof Strait aggregation by far the largest. It is not known whether each spawning population is genetically isolated or where pollock of the Shelikof spawning population spend the rest of the year (Alton and Deriso 1983). Bering Sea Figure 14-13. General regions where walleye pollock (Theragra chalcogramma) spawn as deduced from ichthyoplankton surveys conducted during 1980. (Modified from Alton and Deriso 1983.) Marine Fisheries 437 Strickland and Sibley (1985) hypothesized that the Shelikof Strait spawning population migrates eastward (upstream) during the autumn and winter to spawn, and then migrates downstream again in spring and summer. Spawning occurs from February through August; 60% of the spawning occurred in March and April and 82% occurred at depths between 150 and 300 m (Hirschberger and Smith 1983). During spring, the mid-water schools are segregated by sex and are 80 m off the bottom along the deepest troughs (~300 m) of Shelikof Strait (Nunnallee, Williamson, and Nelson 1982). Pollock spawn upstream in the Alaska Current, and their eggs and larvae drift downstream. This phenomenon also occurs with Pacific ocean perch in the western Gulf of Alaska and has been observed for marine fishes in the North Atlantic Ocean (Walford 1938; Carruthers, Lawford, and Veley 1951). It is not known what environmental stimuli trigger the behavioral events (spawning migration and aggregation by sex) or the physiological events (such as sex- ual maturation) that lead to spawning. These events must be highly synchronized in shoaling species such as pollock. Nei- ther is it known whether spawning selection and timing are keyed to the needs of the adults or whether they anticipate the conditions necessary for maximum egg and larval survival. Pollock eggs are fertilized externally. Experimental evi- dence indicates that the time required for eggs to hatch depends upon the incubation temperature (10 d at 8C: see Table 14-8). Newly hatched larvae are — 3.5 to 4.0 mm in length (Gorbunova 1954) and the yolk sac is completely absorbed by the time they reach 7.0 to 7.5 millimeters. Lar- vae are at the surface at all times. Postlarvae and juveniles move to the surface at night and then sink to mid-water lev- els during the daylight hours (Gong and Oh 1977). Gong and Zhang (1983) report that in Korean waters where the cur- rents are not so swift, pollock remain in coastal waters until they reach 7 cm in size (4-5 mo). Strickland and Sibley (1985) have presented evidence sug- gesting that pollock eggs and larvae in Shelikof Strait are also found in association with reduced currents and strong upwelling conditions. Shallow, coastal areas may provide a favorable environment for the growth and survival of postlarval pollock. Both the fertilization success and the survival rate for fer- tilized eggs and for larvae in Gulf pollock are unknown. However, the natural mortality during the early life of marine fish species is typically very high. If comparable to larval mortality estimates for other marine species such as Table 14-8. Incubation period for pollock eggs in relation to water temperature. A i iiior Temperature Days TO Hatch Yusa(1954) 6-7C 12 Gorbunova (1954) x-3.4 (0.11-1 L.5C) 20.5 x =8.2(2.0-12.2C) 10 Uchida(1964) 8C in 1-2C 20 Atlantic cod, plaice, and herring, walleye pollock larval sur- vival is probably less than 1% (Gushing 1974). Pollock attain a size of ~ 15 cm by age 1 and grow very rapidly (5-10 cm/y) during the first four or five years of life (Niggol 1982). Both males and females mature at about three years of age or at ~ 30 cm in length. Pollock longevity in the Gulf of Alaska is not known but may be about 13 years (Nig gol 1982). The oldest pollock captured in the trawl surveys conducted by the NMFS in the eastern Bering Sea was a 17-year-old female (Pereyra et al. 1976). Pollock may first be recruited into the fishery in substan- tial numbers at two years of age, but they are not fully recruited into the Gulf trawl fishery until age 4 (or until they reach about 35 cm in length). Although 10 or more year-classes may be represented in commercial landings, the fishery in the Gulf is primarily supported by only four year-classes (ages 3-6). A failure in one year-class, there- fore, may have a significantly negative impact upon the fish- ery and the failure of two of the four principal year-classes may be economically catastrophic. On the other hand, the economic potential that results from an unusually strong year-class can be realized within a few years, and may sus- tain high productivity in the fishery for four successive years. Adult pollock in the Gulf are found at depths ranging from 30 to 2,000 m, although the fishery generally captures pollock at 100 to 200 m in winter and 50 to 150 m in the sum- mer (Niggol 1982). They appear to feed very actively except during spawning, when they do not feed at all. Information on pollock feeding habits in the Gulf is pretty much limited to information from certain bays and inlets. The principal food items in Cook Inlet were Tanner crab megalops, gam- marid amphipods, and shrimp (Blackburn, Anderson, Hamilton, and Starr 1983). In certain Kodiak Island bays, seasonal changes in diet were observed. Chaetognaths and calanoid copepods were the predominant food in May, and euphausiids and shrimp were eaten in July (Rogers, Robin, Rogers, Garrison, and Wangerin 1979). There is no direct evidence that food supplies limit the productivity of Gulf pollock populations. However, Strickland and Sibley (1985) argue that the food available to pollock in the Gulf of Alaska may be limited because both their size and their growth rates are smaller in strong year-classes. Examinations of the stomach contents of eastern Bering Sea pollock indicate that their diet changes markedly as they grow. Until they reach ~ 500 mm in length, their stomachs typically contain euphausiids, copepods, and amphipods, although the importance of these zooplankters decreases with increasing length. At 250 mm, fish, shrimp, and crab begin to appear in the diet. Pollock larger than 350 mm are cannibalistic, and other pollock constitute an increasingly larger percentage of their diet (40-70% in pollock >500 mm) as they increase in size. Pollock ( > 35 cm) prey very heavily on other pollock and, in addition, both the juvenile and the adult pollock in the Gulf are eaten by at least 11 species of marine mammals, 13 species of pelagic birds, and 10 other species offish. Marine mammals alone have been estimated to consume 3.4 x 10"' mt of pollock in the Gulf each year (Livingston 1977). 438 Biological Resources Although there is little documentation of predation on pollock eggs and larvae, several species of fish (including pollock), and invertebrates such as squid, may consume pol- lock eggs and larvae. The eggs are fragile and probably very rapidly digested beyond recognition. It is therefore difficult to detect them in the stomach contents of either fish or squid predators. Accumulating evidence indicates that predation is the largest component of natural mortality and may be a very substantial limiting factor in the productivity offish stocks. To improve our understanding of natural mortality we must have much better information on both the prey and con- sumption rate for predators on the pollock during all their life-history stages. We also need information on the pol- lock's food habits, not only when they are near the bottom and available to bottom trawls, but also when they are feed- ing off the bottom and nearer to the surface. Greenlings (Hexagrammidae). Nine species of green- lings from the genera Hexagrammos, Pleurogrammus, and Ophiodon are found in the Gulf of Alaska; only three have any commercial importance. Most greenlings of the family Hexagrammidae inhabit shallow water and are non-shoaling species. Of these, only the kelp greenling {Hexagrammos decagrammus) is an appreci- ated sports fish species. It can grow up to 42 cm long and weigh ~ 1.4 kilograms. The adults are semi-demersal in kelp beds, whereas juveniles are found in the high seas in the Gulf of Alaska and along the Aleutian Islands. The fish bio- mass in shallow water along the Gulf coast averages ~ 850 kg/ha during summer, consisting largely of kelp greenling (30-80%) (Rosenthal 1980). During the winter most kelp greenlings move into deeper water. Atka Mackerel. The Atka mackerel, Pleurogrammus monop- terygiiis, is quantitatively the dominant greenling; it is also the most important commercially. Atka mackerel occurs near and to the west of Kodiak Island. The importance of Atka mackerel in the Gulfs fish ecosystem can be ascertained only when considerably more empirical research (e.g., stomach content analysis) is done on the feeding habits of the pelagic feeders, including mam- mals, which prey on it. Furthermore, the locations of Atka mackerel pre-fishery juveniles must be determined before any conjecture can be made concerning the effect which environmental anomalies might have on the mackerel's population. Its greatest abundance is in the Aleutian area. While it is a pelagic fish, found over the continental shelf as well as over deep water, it is a demersal spawner that attaches its eggs to the bottom substrate. Atka Mackerel Catch Statistics. Neither the Gulf catches of — 2.0 x 104 mt in the late 1970s nor the catch per unit effort (CPUE) reflects the abundance of the species for several rea- sons, including: 1) variable demand, 2) targeting, and 3) the nations involved in the fishery. Despite the meager amount of reliable data, the exploitable biomass of Atka mackerel in the Gulf has been estimated to be ~8.0 x 104 mt (Ronholt 1983). Atka Mackerel Reproductive Biology and Life History. Another example of upcurrent spawners, Atka mackerel aggregate in the Kodiak area from July to October (Albatross and Port- lock Banks) in order to spawn. The species is caught mainly during spawning aggregations in the Kodiak, Chirikof, and Shumagin areas in 50- to 350-m depths. The mean age of the spawning population is estimated at three to four years, with mean lengths of ~ 30 cm, and weights of up to ~ 400 grams. Since eggs of Atka mackerel are attached to the bottom, spawning areas have been estimated either from knowledge of spawning concentrations or from the results of limited larval surveys. Age determinations are controversial, because the ages that were determined by Soviet scientists who were using scales, and ages determined by United States scientists using otoliths do not agree and show consid- erable variability (Ronholt 1983). Lingcod. The lingcod (Ophiodon elongatus) is caught com- mercially. It occurs from Baja California to Kodiak Island, and some specimens have also been found along the Alaska Peninsula (Hart 1973). It frequents offshore reefs and may occur at depths exceeding 500 meters. Lingcod Catch Statistics. As lingcod does not shoal much, it is only incidentally caught in trawls. Some lingcod are taken by sports fishing (jigging), but the main fishery is longline. Off the Canadian coast, between 2.5- and 3.5 x 103 mt have been taken annually. The average length of commercially caught lingcod is between 80 and 90 cm, with weights rang- ing from 10 to 20 kilograms. Fish this size are 6 to 8 years old. In Alaska, most lingcod are taken off the Southeast coast incidental to halibut, sablefish, and cod long-lining opera- tions (Rigby 1984). Lingcod Reproductive Biology and Life History. Little is known about fluctuations in the abundance of lingcod stocks in the Gulf or about lingcod ecology in relation to environmental anomalies. Female lingcod deposit sticky eggs on rocky sub- strate in February and March, and males guard the depos- ited egg masses (Rosenthal, Haldorson, Field, O'Connell, LaRiviere, Underwood, and Murphy 1982). Because lingcod is not only demersal, but is also non- shoaling and deposits eggs on rocks, it may be assumed that environmental influences might have little effect on lingcod stocks. This would mean that fluctuations in recruitment would be caused by predation on juveniles. The adult ling- cod is highly piscivorous and also cannibalistic. The adults also feed on benthic macro-invertebrates, including gam- marid amphipods. Pelagic Fishes The many pelagic species of fishes in the Gulf of Alaska include: • five species of salmon (Oncorhynchus spp.) • steelhead trout (Salmo gairdneri) • sea-run cutthroat trout {Salmo clarki) • Dolly Varden {Salvelinus malma). A detailed discussion of the salmonid species is given elsewhere (Rogers, Rogers, and Rosenthal, Ch. 13, this vol- ume; Rogers, Ch. 15, this volume). Other than Pacific salmon, the single most commercially important.pelagic species in the Gulf is Pacific herring. Marine Fisheries 439 Pacific Herring (Clupea harengus pullasii). Pacific Herring Distribution. The Pacific herring is a sub- species of the Atlantic herring and is believed to have entered the Pacific Ocean in the post-glacial era. It exists today from southern California to Korea. Macy, Wall, Lampsakis, and Mason (1978) present an excellent summary of the herring research conducted in the northeast Pacific, and the results of a recent herring symposium can be found in Melteff and Wespestad (1980). Pacific Herring Catch Statistics. Herring are perhaps the most abundant fish in the ocean. In the past, the annual world catch has been in excess of 2 x 109 metric tons. They are particularly important to the marine ecosystem because they effectively convert plankton into fish biomass that is readily consumed by larger demersal, pelagic, and anad- romous fish. The commercial fishery in areas of the Gulf of Alaska began: • during 1882 in southeastern Alaska • during 1906 south of the Alaska Peninsula • during 1913 in Prince William Sound • during 1914 in Cook Inlet. Prior to 1911, Alaska catches never exceeded 1.0 x 104 mt, but within a decade they had doubled, and by 1925 catches had reached 8.0 x 104 metric tons. The maximum catch — 1.2 x 1()"' nit — was attained in 1937. Over the years, herring have been processed in a number of ways: • reduced to oil, fertilizer, and fish meal — a practice that started in 1882, peaked in 1937 at nearly 1.14 x 106 mt, and essentially terminated by 1966 • salted and pickled — a use that started at the turn of the century, peaked in 1922, and ceased in 1954 • used as bait — a use that was firmly established by 1913, peaked in 1927, and continues today although at a modest level • used for roe and egg harvesting — a use that started in the 1960s, and continues to be a profitable venture today. Gulf of Alaska herring concentrations fall into three groups: 1) southeastern — Chatham Strait, Stephens Passage, and west coast of Baranof Island, 2) central — Yakutat Bay, Prince William Sound, Kachemak Bay, northern and east- ern Kodiak Island, and 3) western — Chignik and the Shum- agin Islands. Herring fishing permits (Alaska Department of Fish and Game 1983) for various gear indicate that the 1982 fishing effort was divided as follows: Prince William Sound— 500, Cook Inlet— 408, Kodiak— 322, South- eastern— 234, Alaskan Peninsula — 224, and Chignik — 128 (versus a total of 3,374 for the Bering Sea). Because Bristol Bay catches are combined with those of both Prince William Sound and Cook Inlet in the statistical summaries, it is diffi- cult to isolate the Gulf catch. However, the total value of the Alaska herring fishery in 1982 was $51.5 million, over 77% of which was for sac roe. In 1960, just before the Soviet Union started herring fish- ing in the eastern Bering Sea, 809c of the Pacific herring catch of 2.27 x 105 mt was Canadian. By 1964, the catch nearly quadrupled to 8.42 x l()'> nit, of which 40% went to the Soviet Union and 30% went to the Canadians. In 1968, the catch was reduced to 5.1 x If)5 mt, but the Soviet Union share was 90% and the Canadian share was only 5% (Buck 1973). The cause for the demise of the Canadian herring fishery is not clear, but it is apparent that useful large-scale studies of the herring-environment relationships cannot be made until both the oceanic distributions and the move- ments of herring stocks are known. Pacific Herring Reproductive Biology and Life History. Herring spawning is a spectacular event that occurs during a period that lasts for several days to a week. Herring milt turns the water opaque, giving it a white cast that is visible even from the air. Many thousands of birds as well as large numbers of demersal, pelagic, and anadromous fish and various marine mammal groups prey in a feeding frenzy on both the eggs and the spawners. Because herring attract so many predators, species survival is related to fecundity (only one egg in 10,000 will produce a spawner). However, adapt- ability to varying environmental conditions also plays a major role in their survival. Although spring and summer spawning occurs along the northeast coast of the United States, spawning in the Gulf occurs only in the spring. Sometimes beginning in March and sometimes as late as earlyjune, eggs are deposited both intertidally and subtidally on vegetation along rocky shores or sandy beaches. Deposit densities can vary from 1.0 x 106 to 1.0 x 108 eggs/m2 (as many as 3.0 x 103 eggs can cling to a single strand of eel grass). Although water temperatures of 5 to 9C and salinities of 8 to 28°/oo are considered favorable for egg survival (Alderdice and Velsen 1971), values of -1 to 15C and 0 to 70°/oo are apparently acceptable. Surviving eggs usu- ally hatch within three weeks (but may require as many as seven weeks), and the larvae are planktonic for about three months. After this period, they actively swim in schools and migrate offshore during the fall, where they remain until they mature at age 3. There is still controversy as to whether or not juveniles join adult schools in winter and as to whether or not they participate in spawning migrations. Food organisms consisting of microscopic eggs, dia- toms, and the nauplii of small copepods at densities of 2.2 x 104/m3 (20 to 50 mg/m3) are required for larval herring survival during early stages (Nikitinskaya 1958). By age 1, their diet consists largely of copepods, and at age 2 eupha- usiids have become the dominant food. Conversely, over 40 groups of invertebrates, fishes, birds, and mammals prey on herring. Maturation occurs at age 3, and age 4 herring domi- nate the fishery (38%); very few survive to age 10. Although there are well-known, basic patterns to the her- ring's life-cycle, these patterns are by no means rigid and must be more completely understood before predictions about the herring and its response to environmental pertur- bations can be made. Traditional spawning locations have been identified, but there are many instances where both the spawning times and the locations vary. There is evidence of discrete local stocks which show limited onshore- offshore movement, while other stocks appear to arrive from unknown oceanic areas. Further, it is unclear whether or not juveniles accompany adults on spawning migrations, so it is impossible to know whether the migrations are a 440 Biological Resources learned response rather than an instinctive one. We also do not understand what triggers spawning activity and whether it can be delayed or advanced, protracted or accelerated, by environmental conditions. Since we have so little oppor- tunity to observe such behavior in other species, better information on herring would be valuable to our under- standing of pelagic fisheries in general. Favorite and McLain (1973) have indicated that the October-to-March mean sea-surface temperatures over a broad area off southeastern Alaska were directly related to the large CPUE of herring that occurred there both in 1953 and in 1958. Subsequent year-classes were evident in the fishery for six years (for the period 1955 to 1960 and for the period 1960 to 1965). Such correlations certainly deserve closer scrutiny. One obvious question that arises is why the CPUE in 1953 was roughly ten times the CPUE in 1952 or 1954. We also know little about either the distribution or the movements of juvenile herring. Rounsefell (1929) reported that second-year herring were numerous in inlets, whereas Tester (1946) noted that little was known about second-year herring and assumed that most remained on oceanic feed- ing grounds. Recently, Hourston (1980) reported that juve- niles appear to remain on offshore feeding grounds until the end of their third growth season, at which time they join the adults' spawning migration. There is no information on what triggers spawning activity. One suggestion is that spawning is synchronized with the full moon. It is important that the roe-herring fish- ery be timed so that it starts immediately before spawning, when the roe is in prime condition. More investigation is required as to whether herring can control the final stage of spawning (ovulation) so that optimum success is achieved. We also need to know the length of time that this process can be blocked in anticipation of more favorable conditions for egg and larval survival. We assume that for spawning, coastal salinity is only sec- ondarily important compared with temperature, because extreme salinity dilution occurs more frequently in the sum- mer than it does in the spring. Where fresh water is bound up in ice, melting may occur, but temperature conditions above the freezing point are also delayed in such a circum- stance, so that any temperature signal (if one exists) would still be a controlling factor. Other questions also remain unanswered: • At what point do the herring decide that the tem- perature is acceptable? • Are herring able to make a subsequent decision as to whether delaying egg release will result in a more favorable temperature? • To what extent are herring able to control year-class success when short-term anomalous environmental conditions occur? In an attempt to clarify herring distributions on the northeast Atlantic coast, Parrish and Saville (1965) separated herring into three population types: 1) oceanic, 2) shelf, and 3) coastal. Perhaps some consideration should be given to the possibility that similar divisions exist in the Gulf, as well as to the possibility that herring spawn in deep water, which also occurs in the Atlantic Ocean. Although these three divi- sions are supplemented by the additional presence of sum- mer/autumn spawners that are not normally present in the Gulf, Atlantic shelf populations migrate from Georges Bank as far south as Chesapeake Bay for the winter, a distance of over 1,500 kilometers. Commensurate migrations in the Gulf of Alaska would permit herring to spawn in south- eastern Alaska even if they originated in the Aleutian Islands or Bering Sea area. Offshore herring surveys took place in the Gulf during the 1920s and again in 1957 (Carlson 1980), but they were considered unsuccessful. Herring have been found in the stomachs of fur seals taken from areas that were 100 to 200 km south of the Alaska Peninsula, and unusually large her- ring were caught in salmon gillnets 100 to 200 km south of the Bering Sea shelf during the INPFC studies. There is evidence that herring larvae remain near spawn- ing sites for a period of time that correlates with their spawn- ing success. The identification by OCSEAP investigators of both inshore and coastal eddies in the northern Gulf that would make this feasible should benefit future herring research. Nevertheless, until we know what proportion of the herring actually move offshore to their unknown oceanic wintering sites, and until we know the distribution and movement of these stocks, it will remain impossible to assess any damage to the herring fishery that results from perturbations in the Gulf environment. Invertebrate Fisheries The invertebrate fisheries of the Gulf of Alaska include both arthropods (crabs, shrimps) and mollusks (scallops, snails, and squids). An historical review of many of these fisheries is provided elsewhere (Feder andjewett, Ch. 12, this volume). Here we highlight three taxa from among these: • pink shrimp • red king crab • oegopsid squids. The fisheries for both the pink shrimp and red king crab are in decline, while those for squids have so far only developed as incidental catches. Shrimp (Pandalidae) Larval Distribution. Cruises in the Kodiak Island area during 1977 and 1978 provide the first detailed description of the occurrence, the distribution, and the abundance of shrimp larvae (Kendall et al. 1980). During bongo-net sam- pling, larvae belonging to the following taxa (by frequency of occurrence) were collected: • hippolytid shrimps • crangonid shrimps • Pandalus borealis P. stenolepis P. goniurus Pandalopsis dispar unidentified pandalid shrimps Marine Fisheries 441 • Pandalus montagui tridens • P. hypsinotus • pasiphaeid shrimps. Although not identified in this list of larva] shrimps, adult Pandalus Jordan i and P. platyceras occur in commercial catches from the Kodiak area. Mean densities (numbers/1,000 ms) of the first three taxa (Table 14-9) reflect the surprising predominance of hippo- lytid shrimp as well as large, but greatly reduced, numbers of crangonid shrimp. Even though over 50 species of these two types of shrimp inhabit the Gulf, none is considered to be of anv commercial importance. Hippolvtid and crangonid shrimp larvae were found throughout most of the year, with highest densities occur- ring in summer. In most portions of the study area, abun- dance was roughly an order of magnitude greater inshore than offshore. Although Pandalus borealis larvae were the third most abundant species reported, they represent 85% of the com- mercial catch in the Gulf — although in some locations, Pan- dalus goniurus and Pandalopsis dispar may dominate. Subse- quent discussion will be limited to pandalid shrimps (specifically P. borealis), commonly known as pink shrimp. Pink Shrimp (Pandalus borealis). Pink Shrimp Distribution. Pink shrimp are rather ubiq- uitous in northern waters, occurring in the Bering Sea, Gulf of Alaska, Gulf of Maine, off Greenland, off Ireland, in the North Sea, and in the Norwegian Sea. They are found at depths ranging from 20 to 1,450 m, and prefer temperatures ranging from -1.6 to 11C and salinities that are greater than 32 parts per thousand. Pink Shrimp Catch Statistics. The shrimp fishery is another example where an unmanaged resource exploitation ended with very strict regulations and pleas for research. Although shrimp were being harvested in southeastern Alaska as early as 1915, the major fishery started after World War II pri- marily in the Kodiak area. Initial catches exceeded 5.0 x 102 mt, increased three-fold by 1955, and increased ten-fold by 1961. The fishery expanded westward along the peninsula in 1967, reaching the Unalaska Island area in 1972. By 1973, 5.23 x 104 mt were being taken annually from the northern Gulf. By the mid-1970s, over 50% of the catch was made in Table 14-9. Mean densities (numbers/10:t m:t) of the three dominant taxa of shrimp larvae in the Kodiak area (from Kendall, Dunn, and Wolotira 1980). Area HlPPOLYTID Crangonid P. BOREALIS Inshore Izhut Bay 4.034 408 120 Chiniak Bav 4.324 312 182 Kiliuda Bay 4,391 1.326 49 Kaiugnak Bay 1,698 1 35 131 Offshore subareas Portlock 355 52 16 Marmot 270 121 23 Albatross 465 178 6 Sitkinak 211 15 - the western areas and this increased to 65% by 1979. In 1982, the western areas were closed. A decline in the Kodiak stocks was readilv apparent in 1977 when catches were about 50% lower than during the peak years between 1970 and 1973 (1.44 x 10 ' mt vs. averages of 3.09 x 1() i mt), and there were 16 locations that had sepa- rate management regulations. From 1973 to 1977, the aver- age annual catch in the Kodiak area (and west) was 4.81 x 10s mt — which at today's ex-vessel prices ($.30/lb) represents an annual value of $31.8 million. Pink Shrimp Reproductive Biology arid Life History. Spawning occurs in late summer or early fall. Females carry the fertil- ized eggs until they hatch into planktonic larvae — usually by early spring. Pandalus borealis larvae are released only during this brief spring period and the number of larvae in inshore areas not only diminishes in late spring, but by late summer, none are present. Further, in offshore areas greatly reduced concentrations of P. borealis are found in the spring and sum- mer, and none are found in fall or winter. Within three months the juveniles start their semi- benthic existence after which (in one or two years) most mature first as males (maturing in the second year), and thereafter spawn as females. Pink Shrimp Oceanographic Considerations. Although phys- ical/chemical oceanographic data from OCSEAP cruises show that currents east of Kodiak Island are weak and vari- able compared with the 50 to 100 cm/s southwestward flow at the shelf edge in the Alaskan Stream, both surface and bot- tom drifters reflect southwest flow along both sides of the island. This suggests a contranatant movement of the adults that is similar to the one discussed in relation to halibut. However, even though shrimp have mobility in the water column, it is assumed that most movement occurs along the bottom. It is unlikely that any bottom movement would be ade- quate to maintain the long-term stock distributions in the Kodiak area. Rather, it appears that those larvae that are released in (and not flushed out of) the extensive bays are adequate to maintain discrete local stocks. Those larvae that are carried out of the bays contribute to stocks along the Alaska Peninsula. Shrimp behavior may be related to both air and sea tem- peratures (Niebauer 1981; Weingartner 1981). For example. Ingraham (1981) was able to show that environmental condi- tions off Kodiak Island during a good shrimp catch in the spring of 1972 were cold compared to those during a poor shrimp catch in the spring of 1978. However, the former data were part of a MARMAP study which was subsequently discontinued and the latter were part of an OCSEAP study which commenced in 1977. No comparable data were obtained in the intervening period. Studying the relationship between shrimp and the warm-temperature stratum at the shelf edge (discussed as favorable to halibut larvae) reveals a temperature regime that is reasonably constant. Since P. borealis tolerates a wide temperature range, it seems that temperature studies would not be as informative as salinity studies. If, as Ivanov (1963) reports, adult P. borealis avoid salinities below 32.34"/oo, this would explain not only why there are limited distributions in both hyposaline Prince William 442 Biological Resources Sound and Cook Inlet, but also why distributions are abun- dant on the east side of the Kodiak, Afognak, and Shumagin Islands where there are deep troughs (i.e., Stevenson, Chiniak, Kiliuda, and others) with salinities that are greater than 32.5 parts per thousand. Although some pandalid shrimp are believed to move offshore in fall and winter (Lukas 1981), it is never clear how far they move and to what depths they descend. Ivanov (1963, 1964) has shown that in December 1962, commercial quantities existed east of the Shumagin Islands at depths of between 100 and 150 meters. This was adjacent to a trough whose depth exceeded 200 meters. Similar quantities were also found in the Bering Sea during the period of December to February 1962-1963, at equivalent depths. Thus it would appear that the shelf provides an adequate year-round environment for shrimp. Crabs Several species of crab are commercially caught in Gulf of Alaska waters. These include: • Dungeness crab (Cancer magister) • Tanner crab (Chionoecetes bairdi) • Red king crab (Paralithodes camtschatica) Both the Dungeness and Tanner crabs are discussed in detail elsewhere (Feder andjewett, Ch.12, this volume). Here we instead focus on the most abundant of the king crabs, the red king crab. Red King Crab (Paralithodes camtschatica). King Crab Distribution. The red king crab is the most abun- dant of the five species of the genus, and is broadly dis- tributed on the continental shelf and upper slope off Asia and North America. It is also found in subarctic waters of the North Pacific Ocean and its adjacent seas. In North America, the red king crab occurs in both the Bering Sea and the Gulf of Alaska. King Crab Catch Statistics. The major king crab fisheries in the Bering Sea are in Bristol Bay, in Norton Sound, and along the Aleutian Islands. In the Gulf, there are fisheries in Prince William Sound, Cook Inlet, around Kodiak Island, and along the south side of the Alaska Peninsula. The red king crab catch in the Gulf has been dominated by landings from the western Gulf — from the Kodiak Island and Chignik/South Peninsula fisheries. Catch data from 1950 through 1984 (Table 14-10), indicate a disastrous 1983-1984 season. Red king crab were first taken in Kodiak in 1936, even though the catch was not officially recorded until 1950 (Alaska Department of Fish and Game 1983). The Kodiak fishery had a maximum production in 1965-1966; in the period from 1970 to 1980, catches declined. The Chignik/ South Peninsula fisheries declined in a similar manner. Catches in both the Kodiak and Chignik-South Peninsula areas declined very sharply after the 1981-1982 season. Popu- lation estimates indicated that the stocks in both areas were seriously depressed and, consequently, no red king crab fishery was permitted in those areas from 1983 to 1985. Declines in the red king crab stocks occurred in virtually all major stocks in Alaskan waters. In the Bering Sea, red king crab abundance was so low that no fishery was permitted in the 1983-1984 season, but a modest catch of ~ 1.8 x 103 mt was permitted in 1984-1985. The outlook is dim for any substantial abundance increase in the western Gulf. In addition to the fact that there are very few legal-size male crabs, the abundance of pre-recruits and females is at record lows, while the inci- dence of non-ovigerous females is high. There is no readily apparent reason for the decline in pre-recruit and female crabs (which are not targeted by the fishery) nor for the decline in legal-size males. There are several theories as to the cause of the decline in the non-exploitable (females and pre-recruits) compo- nents of red king crab stocks. These theories include: Table 14-10. Historical king crab catch ( x 103 mt) in both the Kodiak and the Chignik/South Peninsula registration areas from 1950 to 1984 (from Alaska Department of Fish and Game 1983). Year Kodiak 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 Subtotal Average 1960-1961 1961-1962 1962-1963 1963-1964 1964-1965 1965-1966 1966-1967 1967-1968 1968-1969 1969-1970 Subtotal Average 1970-1971 1971-1972 1972-1973 1973-1974 1974-1975 1975-1976 1976-1977 1977-1978 1978-1979 1979-1980 Subtotal Average 1980-1981 1981-1982 1982-1983 1983-1984 Subtotal Average Chignik/ South Peninsula 60.0 2,124.0 200.0 599.0 400.0 298.0 900.0 380.0 4,000.0 317.0 2,000.0 1,641.0 4,800.0 4,221.0 5,000.0 6,687.0 5,200.0 7,246.0 10,200.0 6,167.0 32,760.0 29,680.0 3,276.0 2,968.0 21,064.8 6,700.0 28,962.9 3,900.0 37,626.7 2,273.0 37,716.2 6,539.0 41,596.5 14,354.0 94,431.0 14,713.0 73,817.8 22,577.0 43,448.5 17,252.0 18,211.4 10,944.0 12,200.5 4,137.0 409,076.3 103,389.0 40,907.6 10,338.9 11,719.9 3,425.7 10,884.1 4,123.1 15,479.9 4,069.3 14,397.3 4,260.6 23,582.7 4,572.3 24,061.6 2,605.3 17,966.8 958.8 13,503.6 726.3 12,021.8 3,093.8 14,608.9 4,453.5 158,226.6 32,288.5 15,822.6 3,228.9 20,448.6 5,080.6 24,237.6 3,147.5 8,729.7 1,627.7 111.4" CLOSED 53,415.9 9,855.8 17,805.3 3,285.2 a Brown crab. Source: Alaska Department of Fish and Game (1983). Marine Fisheries 443 • high handling mortalities for crabs discarded from the trawl or the crab fisheries • increased predation by Pacific halibut and Pacific cod • parasitism or disease. Griffin, Eaton, and Otto (1983) observed the catch com- position in the red king crab fishery of 1982 (September- October) and in the fanner crab fishery of 1983 (March-April) for the eastern Bering Sea. In the red king crab fishery, 1 female and 7.3 sublegal males were caught for every legal male crab that was landed. In the Tanner crab fishery, 1.6 king crab were discarded for every legal Tanner crab caught. Red king crab discarded by both trawl and long-line fisheries in the eastern Bering Sea in 1981 and 1982 was estimated at 1.2 x 106 crabs (790 mt) and 3.3 x 105 crabs (245 mt), respectively (French, Nelson, Wall, Berger, and Gibbs 1981; Nelson, Wall, and Berger 1983). No reliable survival-rate estimates are available for dis- carded red king crab. Otto, Macintosh, Stahl-Johnson, and Wilson (1983) did not consider the incidental catch and sub- sequent discards by the directed and non-directed fisheries to be sufficient to account for the decline in the abundance of the eastern Bering Sea red king crab stock. King Crab Reproductive Biology and Life History. Predation on king crab by both the Pacific cod and the Pacific halibut has been thought to be a contributing cause in the decline of both female and pre-recruit red king crabs. Both the abun- dance of these two predatory fish and the numbers of them caught incidental to retrieval of crab pots (Alaska Depart- ment of Fish and Game 1983) have increased in recent years. They are both known to consume some red king crab. In the Kodiak area, only 10 of 5,500 Pacific cod stomachs that were examined during the non-molting period contained king crab parts (Alaska Department of Fish and Game 1983). No information is available from the Gulf regarding predation by cod on soft-shelled king crab. However, evidence from studies in the Bering Sea indicate that red king crab preda- tion by Pacific cod may be more serious during the molting season. June and Shimada (Northwest and Alaska Fisheries Cen- ter, NMFS/NOAA, unpubl. data, 1986) found either red king crab parts or whole red king crabs in 10% of the cod stom- achs collected in the eastern Bering Sea trawl surveys con- ducted between May 5 and July 20, 1981. All the crab and crab parts in the stomach had new shells, indicating recent molting. From estimates of the cod biomass in areas where crab are distributed, and assuming certain minimum and maximum consumption rates, potential mortality to king crab females in the eastern Bering Sea was calculated as between 3.3 x 106 and 3.49 x 10" crabs during the single month that the female crabs are in their soft-shelled condition. Both disease and parasitism are also suspected causes of or contributors to the decline in the productivity of red king crab stocks. Lethal viruses and microsporidians have been estimated to infect about 4% of the red king crab through- out Alaska. In one out of even' five cases, the Kodiak crabs that were examined were infected bv a virus. The signifi- cance of diseases as a source of mortality to Alaskan red king crab is not yet known. However, there is speculation that epidemic diseases could have been a major factor in the recent decline of red king crab throughout Alaska (Alaska Department of Fish and Game 1983). The coincidental decline in the abundance of virtually all red king crab stocks in Alaska is surprising since the stocks are apparently independent. There is no direct evidence, such as from tagging, to indicate that adult red king crab from the major stocks in the Bering Sea and the Gulf inter- mingle (Hayes and Montgomery 1963; Powell and Reynolds 1965; and Simpson and Shippen 1968). Evidence from tag- ging operations conducted off southwest Kodiak and south of the Alaska Peninsula suggests that there is a regularity to red king crab movement and that the crab population in an area such as Kodiak is composed of many local stocks. Red king crab form offshore aggregations during the summer and the early fall. Beginning in November, crabs off Kodiak migrate shoreward and by February, large num- bers are in depths of 30 fin or less (Powell 1964). Crabs in the offshore feeding areas represent mixed stocks. Crabs dropped at single offshore release sites in both the Kodiak and Shumagin Islands areas migrated to more than one bay. In both studies, very few crabs released in one bay migrated to another. In a given spawning season, the crabs in the vari- ous bay systems are apparently isolated, indicating the exis- tence of separate stocks. Powell (1964) suggests that bay systems include offshore banks which may be occupied by discrete stocks. This evi- dence indicates that the spawners of the respective bays are isolated during a given mating season. It is not clear, how- ever, if crabs return to the same bay systems in successive years, and therefore retain genetically isolated stocks. It is also possible that if crabs spawn in different bays in suc- cessive years, some broader genetic interchange results. If such an interchange does occur, it is probably geograph- ically limited. Evidence from tagging indicates that crabs from single offshore locations usually migrate to adjacent banks and bays. Those factors that determine the stock formation and which control the crabs' shoreward and seaward migration are not well understood. Powell (1964) suggests that the trenches of the continental shelf, which project into the numerous bays, form a path which is followed by the crabs in their shoreward migration. It is not known if the trenches guide the crabs shoreward or if other environmental gra- dients come into play. Neither is it known what triggers the beginning of these inshore migrations. Hayes (1983) sug- gests that there are environmental mechanisms that main- tain the apparent separation of stocks and considers stock structure to be the result of certain current patterns that keep the crab larvae within these areas on the Kodiak shelf. Marukawa (1933) first suggested that crab larvae must be most numerous in vortices and gyres, since the perpetua- tion of the population depends upon the ultimate settling of the first instar in an environment that is suitable for survival. Powell (1964) also suggested that inshore spawning of king crab assures that their planktonic larvae are not carried out to sea by currents. The same hypothesis has also been pro- posed with regard to fish eggs and larvae (e.g., see sections on Pacific halibut, Pacific ocean perch, and walleye pollock). There are, however, few, if any, direct measurements of the 444 Biological Resources flow patterns in the heavily indented coastline south of the Alaska Peninsula and its several archipelagos. Hydro- dvnamical numerical (HN) models, however, have indicated the presence of gyres and countercurrents in waters off Kodiak Island, and local wind stresses (obtained from mete- orological data) indicate periods of both onshore and off- shore flow at the surface as well as at depth (Fig. 14-14). It is often assumed that year-class strength is directly related to larval survival. Larvae are at the mercy of the environment and are particularly vulnerable to mortality due to temperature, flow, predation, and the availability of food. A better understanding of larval distribution and mor- tality will require much more detailed knowledge of the estuarine, coastal, and oceanic environment of the Gulf. As noted by Hayes (1983), however, abundant year-classes of A. Onshore Transport Positive Curl B. Onshore Transport Negative Curl C. Offshore Transport Positive Curl D. Offshore Transport Negative Curl Location Vectors C Wind stress CJ~\ Ekman transport 'QA ^ L'pwelling-down welling Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 54N, 164.W BAACCCCCCCCC 55N.160W BAACACCCCCCA 57N, 156VV BAACCCCCCAAA 59N, 151W AAAABDDCAAAA 60N, 140VV AAAABDDDAAAA 59N, 141W AAAABDDBAAAA 57N, 137W AAABBBBBBAAA 54N, 134W AAAABBAAAAAA Figure 14-14. Classification of transport events according to the combination of both coastal and offshore convergence or divergence and monthly mean transport types in the northern Gulf. (Modified from Ingraham, Bakun, and Favorite 1976.) juvenile crabs have undergone considerable mortality dur- ing either their pre-recruitment size or age. Better under- standing of the dynamics of red king crab production, there- fore, will require knowledge of both the sources and the magnitude of mortality of all of the red king crab's life his- tory components. As indicated by the Alaska Department of Fish and Game (1983), the significance of epizootics, parasitism, and preda- tion must also be evaluated. In addition, the interre- lationships between the short-term effects of both hydro- dynamics and temperature on the distribution and behavior of crab and the effect of longer-term variations in ocean conditions on the productivity of Gulf crab stocks should be studied. Squids Oegopsid Squids. Squids are pelagic species of cephalopod mollusks having soft bodies and 10 arms. Related to them are octopus and cuttlefish. Representatives of the oegopsid squids include: • Onychoteuthis boreali japonkus • Gonatus fabricii • Gonatopsis borealis • Moroteuthis robusta • Berryteuthis magister • Loligo opalescens. Squid Distribution. Most squids live in relatively deep water (200 to 2,000 m) in the the Gulf and Aleutian Islands areas. Various cephalopods have been caught in these areas at night-light stations associated with INPFC high-seas salmon research. They are found at a wide range of depths and require high-salinity water ( > 30°/<><>). Therefore, they do not occur in coastal waters of low salinity. Some species that live near the surface undertake long seasonal migrations as part of large schools — they move toward the north in the spring and then back to the south in autumn. The south- ernmost species, Onychoteuthis boreali japonkus, occurs in the southern part of the Gulf only during summer. It has a life span of only one year and undertakes extensive seasonal migrations in the western Pacific. Gonatus fabricii and Gonatopsis borealis are both pelagic squids that are common in the subarctic region. Gonatus fabricii made up roughly 50% of the stomach contents in sperm whale stomachs in the Commander/Aleutian Islands area during 1961 and 1962 (Kodolov 1970). Moroteuthis robusta is the largest member of the species considered here and is primarily demersal during its adult stages. It also forms an important part of the diet of sperm whales in the northeastern Pacific and is occasionally caught by trawlers but has little market value. Berryteuthis magister, also an important item in the sperm whale diet, is a subarctic littoral species. It changes to a benthic life before matura- tion and spawns at from 200 to 500 m between June to October along the Aleutian and Bering Sea slopes (Naito, Murakami, and Kobayashi 1977). Squid Catch Statistics. Direct measurement of squid resources is very difficult, if not impossible. An idea of the Marine Fisheries 445 great size of the squid standing stock can be obtained by computing the food consumption of sperm whales in the North Pacific. This is done with conservative input values in Table 14-11. For Comparison, Clarke's (1977) conservative estimate of the amount of squid consumed by sperm whales on a worldwide basis is 3.2 * 108 metric tons. Although there is an intense squid fishery in the western Pacific (Okutani 1977), the fishery in the Gulf is incidental to other target species, with less than 1.0 x 104 mt harvested annually in the Gulf by foreign (leets. Recently, an experi- mental fishery for squid off the Canadian coast has been car- ried out in a cooperative effort by Japan and Canada. Although in recent years some research on cephalopods has been conducted in Canadian waters in association with cither bait or export fisheries, little has been conducted in the Gulf. Squid research by United States fishery agencies has been limited and, consequently, the relationship between squids and their environment is unknown. The absence of research on either the abundance or the seasonal behavior of squid in the northeast Pacific precludes any serious quantitative consideration of the effects that squids have on the marine fish ecosystem. Squid Reproductive Biology and Life History. Squids play an important role in the oceanic ecosystem as prey and preda- tors. They are a major food item for some of the toothed whales {e.g., sperm whales), pinnipeds {e.g., fur seals), por- poises {e.g., Dall's porpoise), and the larger pelagic fish such as salmon. Larger offshore pelagic fish such as tuna, salmon, and pomfret feed to a considerable extent on smaller (juve- nile) squid, as do some species of marine birds {e.g., sooty shearwaters). Because pelagic squids form schools that can Table 14-11. An estimation of squid consumption by sperm whales in the North Pacific Ocean to derive squid standing stock estimate. Harvestable sperm whales in the North Pacific: 1 75,000-' individuals Mean weight of a sperm whale: 30 mt Total biomass of harvestable sperm whales: 5.25 * l()''mt Sperm whale food requirement as a) % of body weight daily (BWD): 5b b) (times body weight annuallv): 18.25 Total annual food consumption by harvestable sperm whales in the North Pacific: 95.81 * 10'' mt Composition of sperm whale's diet as a) squids: 85%c b) fishes: 15% Annual food consumption bv sperm whales in the North Pacific as a) squids: 81.4 x 10" mt b) fishes: 14.4 * 10" mt Assuming Fmax = 20%'', the minimum biomass of squids in the North Pacific is: 400 x 106 mt •' This is an absolute minimum' estimate (International Whaling Commission Spe- cial Issue 2 1980). The total number of sperm whales in the North Pacific was estimated for 1977 as: females 411.000 to 525.000; males 376,000 to 474,000. b The food consumption of whales is estimated in the literature to be 4 to 6% BWD. The minimum estimate is 2.59c BWD. c Some estimates give up to 959c squid (Berzin 1970). d This 'fishing coefficient' of squids bv sperm whales is probablv too high; it corres- ponds roughlv to F for pelagic fish. move faster than many fish, and because they can sustain high speeds, they are seldom caught in mid-water trawls. Most of the quantitative knowledge on oceanic squid in the Gulf of Alaska originates from food studies conducted on the marine mammals and fish. Many squid species migrate seasonally in large schools in a north-south direction (Okutani 1977). It has been postu- lated that these seasonally migrating squid schools are fol- lowed by fish, marine mammals, and birds, but no prool of this is available. On the other hand, squid themselves are predators and might affect the marine fish ecosystem to a considerable extent. Juvenile squids (and other juvenile cephalopods) feed on planktonic crustaceans, including euphausiids. As squid grow, the percentage of fish in their diet increases. All squid longer than 20 cm feed exclusively on pelagic fish (myctophids andjuveniles of other fish, such as rockfishes) and on other smaller cephalopods. Can- nibalism among squids is common (Naito et al. 1977). Adult squid are among the most aggressive inhabitants of the seas, frequently attacking prey that is larger than them- selves. Large squids (Architeuthidae) can overpower even large fish such as tuna, and squid attack marks are often found on small tuna and salmon. It has been speculated that the inter-annual variation in squid abundance might cause some fluctuation in the abundance of pelagic fish. Only a few squid species, such as Berryteuthis magister (along the Aleutian Islands) and Loligo opalescens (off Califor- nia), return to shallower water to spawn. Most species under- take diurnal vertical migrations toward the surface in the evening and then back into deep water in the morning. A considerable amount of research on squid and their rela- tionship to the ocean environment has been carried out by Japanese scientists in the western subarctic Pacific (Okutani and Nemoto 1964; Okutani 1977; and Naito et al. 1977). Physical Oceanographic Considerations Perhaps the most interesting and most applicable of the OCSEAP physical oceanography studies are the satel- lite-tracked drifting buoys. One of the first of the OCSEAP buoy releases clearly established that there is an extensive eddy west of Kayak Island (Fig. 14-15), which trapped the buoy for a number of weeks (Royer et al. 1979). Such trap- ping could have an effect on fish eggs, larvae, and juveniles, as well as on fish homing and the movements of predator) fish. However, no biological sampling was conducted. In addition, the northerly onshore drift of the buoy after it was released resolved a number of theoretical questions about the effects of bottom topography on alongshore flow in the area. Further, subsequent movement of the buoy directly across the mouth of the Copper River and into Prince William Sound was surprising, and suggested that distribu- tion for the tongue of dilute water from the Copper River (extending seaward for 300 km in summer during 1978) may be quite variable. Equally perplexing are the trajectories of the satel- lite-tracked buoys that were released south of the Kenai Peninsula in the spring of 1978 (Muench and Schumacher 1980). The buoy released at the southernmost point (No. 446 Biological Resources 148 E^7^7 — ^ — Track of buoy (142) Days from starting point Figure 14-15. Trajectory of a satellite-tracked drifting buoy released in the Gulf of Alaska in summer 1976 showing the extensive along-coast flow near Cape Suckling, the large, non-tidal eddies west of Kayak Island, and movement into Prince William Sound. 1421) moved the farthest northward and went into Cook Inlet (Fig. 14-16), although it only penetrated the Inlet a few tens of kilometers. Other buoys released in the same general area (Reed 1980) have not even penetrated that far into the inlet, indicating an extremely limited surface flow of north- ern Gulf water into Cook Inlet. The trajectories of two buoys released in spring 1978 (Nos. 1473 and 1775) nearly crossed each other southeast of the Kenai Peninsula, then moved southeastward on differ- ent sides of Kodiak Island. Similar evidence of equally con- fusing drifts were obtained from drift cards released in the same area during the same time (Fig. 14-17). Evidence from both of these experiments reflects the complexity of flow in the northwest Gulf. Also interesting is the trajectory of a buoy (No. 1220) that was released at the shelf edge off Kodiak Island in late July 1978. This buoy was tracked through August southwestward along the shelf edge as far as 54.5°N, 159°West. It did not exhibit the eastward movement into the central Gulf that Reed (1980) was able to show by releasing three buoys in this area both at and seaward of the shelf edge. Further, the sea- bed drifters that were released on the shelf near Kodiak Island by Kendall et al. (1980) indicate a complex onshore and offshore cross-shelf bottom flow. The onshore flow extended into the coastal bays in spite of a general south- westerly flow. Such studies mark a tremendous advance in the knowledge of the coastal flow in this area, even though the apparent variability makes it difficult to sort out all com- plexities. Additional Field work and considerable analysis must be done before such environmental data can be inte- grated with information on biological phenomena. An extensive database of Gulf physical and chemical oceanographic data (gathered from nearly 4,000 CTD sta- tions during the period from February 1975 to February 1979) has been compiled as a result of OCSEAP investiga- tions. Although individual disciplines may use these data for specific purposes, an overall synthesis and analysis of condi- tions and processes should be a high priority. Some of the limitations of such analyses are the aperiodic nature of the Jun9 May 23 Figure 14-16. Trajectories of drogued satellite-tracked buoys deployed in 1978. Locations are plotted at one-day intervals. (Modified from Muench and Schumacher 1980.) Marine Fisheries 447 Figure 14-17. Summary of the recovery and release points for OCSEAP drift cards released in May 1978. (Modified from Muench and Schumacher 1980.) data and the fact that in many instances, tidal currents not only dominate geostrophic flows (based on distribution of mass) but also compromise property distributions where a number of tidal cycles happened during the time it took to gather station data. Fisheries Interactions and Surveys The goals of those competing for ocean resources are not necessarily compatible. For example, the goal of preserving marine mammals (which are formidable competitors with fishermen and a serious nuisance to fishing) is accom- plished at the expense of the efficiency and the yield of com- mercial fisheries. In addition, there are concerns over the impact that oil exploration and extraction will have on both the ocean environment and the fish stocks even though there is no evidence of either long-term damage to the oceanic environment or of damage to the marine fisheries. In order to both adjudicate conflicts and evaluate trade- offs rationally, it is necessary to critically assess the value of the conflicting activities. An important aspect of such an evaluation is an accurate assessment of the abundance and condition of the fisheries. Knowledge concerning the fish- eries resources, therefore, is now of interest to parties other than those directly associated with fisheries. There are diver- gent perspectives and interpretations of resource assess- ment information even within the fisheries community. Fish stocks were studied even before the beginning of the present century (Petersen 1894) and are among the best-studied groups of animals. The historical, substantive development of fisheries science has been recently dis- cussed by Cushing (1983). The biological basis for fisheries was first examined by Baranov (1918). Russell (1931) provided a lucid discussion which became the basis for his theory of fishing. Even though later developments have provided extensions, refinements, and elaborations on Russell's work, his basic considerations still hold. The simple model which he used to describe overfishing will suffice to illustrate some important points regarding the status of our knowledge about Gulf fish stocks. The dynamics offish populations are extremely com- plex. For the sake of simplicity, Russell described the dynamics of a single fish stock (single species) by the equation: S2 = Sj + (A + G) - (C+ M), where; S2 = stock weight in year 2. Sj = stock weight in year 1. A = the increase in the exploitable biomass that comes from adding fish that are glowing to a size where they are retained by fishing gear (recruit- ment). G = the increment (in weight) from growth of an individual fish within the exploitable stock. (A + G) = the total annual population increment. C = the annual catch, which must include not only the tonnage offish that were landed but also the weight of the fish that were discarded. M = the total natural mortality as a result of preda- tion, disease, senescence, and starvation. (C + M) = the total decrement in the exploitable popula- tion. When (A + G) is equal to (C+M), then S2 equals S, and the population is in equilibrium. When S2 is greater than S,, then (A + G) is greater than (C + M) and, conversely, when S2 is less than S,, then (A + G) is less than (C + M). The catch (Q and the size at first recruitment are control- lable. The quantity C is dependent upon both the quality (the mesh sizes and the efficiency of the fishing gear, the horsepower of the fishing vessels, and other factors) and the quantity (the number and the duration of the trawl tows) of the fishing effort. Assuming that the catch (C) is controllable, the most important components in the dynamics of a stock are recruitment (.4) and natural mortality (M). The biological effect of the quantity of C on M (or of M on Q is difficult to ascertain. In a cannibalistic species, increasing C would decrease M. Since C and M constitute total mortality in terms of weight, there is an inverse, arith- metic relationship between C and M. If C increases, it will diminish M, since some of the individuals that are caught would have died natural deaths. Conversely, if M is increased, C must diminish, since some individuals will die which otherwise would have been caught. If food is considered to be a limiting factor, then competi- tion for similar prey exists. Any reduction in biomass that results from an increase in C may also result in an increase in G. With a superabundance of food, variations in C would have no effect on G. The catch, C, would seem to have no effect on incoming recruitment, (A), unless the species is cannibalistic. In that case, an increase in C would result in an increase in A Obviously, fish-stock productivity is greatlv influenced by interactions other than those included in Russell's model. Russell's model reflects only the productivity of a single stock of a single species for two successive years. For exam- 448 Biological Resources pie, the recruitment strength may be associated with the number of spawners in the year of their birth. As a result, the catch that year may affect subsequent recruitment. Another important consideration is that the habitat and the prey of various species overlap to some extent. Inter- specific competition and predation are factors which may affect both G and M. The foregoing discussion of Russell's simple model illus- trates that some complex interrelationships and some very demanding estimates are required even in an elementary stock assessment. It serves, however, as a basis for under- standing the Gulf resources and fisheries. Population biomass estimates for year 1 (S,) and year 2 (52) pertain to a common spawning stock. In the Gulf, it is not known whether each demersal species is made up of one stock or several stocks. Pacific halibut are presumed to be a single stock (Bell 1981), and there is some evidence to indi- cate that Gulf pollock are also from a single stock (Strickland and Sibley 1985). Other evidence, however, suggests that two or more pol- lock stocks occur in the Gulf (Hughes and Hirschhorn 1979; Grant and Utter 1980; and Alton and Deriso 1983). For Pacific ocean perch, the prevailing view is that discrete stocks occur along the entire rim of the Gulf of Alaska, but stock boundaries have not been clearly delineated. For man- agement purposes, there has been some arbitrary stock delineation using statistical districts which may not corres- pond to actual stock boundaries. Although stocks are not clearly identified or delineated, estimates of Sj and S2 are nonetheless obtained in surveys using bottom trawls (Ronholt et al. 1978; Ito and Balsiger 1983). Trawl survey information is at times supplemented with acoustical survey data. There are at least two major ways in which errors can be introduced when biomass estimates are made from bottom trawl catches. The first relates to whether or not fish are available to the bottom trawls, and the second relates to the catchability of fish and shellfish even when they are available. Any trawl survey must assume that the total distribution area for a given stock is known and that the catch in the stan- dardized tows is representative of the species composition, as well as representative of the size, the sex composition, and the abundance of each species. The exploitable portions of the demersal fish are distributed from near the surface — as in the case of pollock — to near the bottom — as in the case of flatfish and shellfish. It is clear that bottom trawls may ineffi- ciently sample semi-demersal and pelagic species such as pollock, which are only partially available near the bottom. Alton and Deriso (1983) suggest that bottom trawl surveys per se may be adequate for detecting several orders of magni- tude of change in the abundance of pollock. However, meaningful comparisons cannot be made between esti- mates which differ by less than one order of magnitude. Supplementing trawl surveys with acoustical surveys will improve the estimates of semi-demersal populations. How- ever, the accuracy of even those biomass estimates remains unverified. Adult flatfish and shellfish such as king crab are available to bottom trawls. There is, however, some question regard- ing the efficiency of capturing them. For example, the increase in abundance evident for some species of flatfish during eastern Bering Sea trawl surveys between 1981 and 1982 was so large (~50% overall) that it could not be explained biologically. Bakkala and Wespestad (1985) attributed these increases to rerigging the trawl and improv- ing the bottom-tending characteristics of the trawl used in 1982. If this is true, trawl surveys conducted prior to 1982 have underestimated both the abundance and the biomass of flatfish. It is not clear, however, to what extent the catchability coefficient was improved in 1982, considering that relative abundance (CPUE) increased again by 23% in the 1983 survey. Estimates of both recruitment and growth in Gulf demer- sal fish are directly obtainable by systematically sampling at the processing facilities for the sex, the size, and the age of fish that are brought there. Careful appraisal of the fishing methodology of the fleet is also necessary, because size — and, therefore, quantity — at recruitment will vary with the gear type and the mesh size. For Pacific ocean perch and some other species, the age at recruitment cannot be relia- bly estimated because there are substantial disagreements regarding age determinations. It has at times been assumed that recruitment is related to the number of spawners. There is, however, little or no information regarding spawner-recruit relationships for demersal fish species in the Gulf. Growth of the exploitable stock usually is among the more easily estimated components in Russell's simple stock-dynamics model. Growth rate is not, however, con- stant but varies with such factors as water temperature and, possibly, with the availability of food. It is therefore neces- sary periodically to update age-length relationships for all exploited species. Reliable age-length relationships cannot be developed for some demersal fish in the Gulf until dis- agreements over age determination are reconciled. Catch would seem to be the simplest mortality compo- nent to estimate with accuracy. However, there are several error sources in the collection and compilation of catch sta- tistics which have not been evaluated. In the 1984 fishery, observers were aboard foreign fishing vessels during 85% of their operating days and for 85 to 90 % of the operating days of the joint-venture fisheries. Although observers make sev- eral kinds of observations, their main task is to estimate the catch in these fisheries. In these commercial fisheries, the catch is not actually weighed but is volumetrically estimated either from the dimensions of the fish-storage bins (some of which have irregular configurations) or from the estimated capacity of the cod ends of trawls. The accuracy of these pro- cedures in estimating the weight of the catch has not been evaluated. Another source of error is the inaccurate reporting of catch statistics. Both under-logging and under-reporting of catch or by-catch data are common among foreign fisheries in Alaskan waters. Catch statistics obtained prior to the placement of substantial numbers of observers were essen- Marine Fisheries 449 tiallv unverified and may have been substantially under- reported. With increased observer coverage during the past two or three years, opportunities for inaccurate reporting have been reduced. However, in spite of the best efforts, the accuracy of catch reports cannot be verified. Although the fishery targets certain species, sexes, and sizes, the catch often includes other fish. The by-catch should be included as part of the catch; however, it may be discarded cither by the fishing vessel or sorted and dis- carded on the processing vessel. The by-catch very fre- quentlv is not estimated (e.g., overflow catch released from trawls prior to deliveries) or may be approximated (with some unknown error) as it is on foreign processing vessels. The bv-catch may be composed of commercially valu- able species which must — bv regulation — be discarded because thev are either prohibited, or of the wrong sex, or are undersized. It is ironic that regulations intended for the welfare of the stock may actually aggravate the problems associated with discards. Discards may also be undesirable species, undersized fish of the target species, or catch which is in excess of the handling and processing capabilities of the factory facility. There are no fish stocks in the Gulf for which natural mortalitv (At) has been reliablv estimated. The rate of natu- ral mortality is not the same for all ages within the stock. Mortality rates for marine fish tend to be highest in early life (through earlv juvenile stages), then decrease with growth and increase again in older fish which suffer spawning stress and senescence. Natural mortality is the result of a number of causes — some of which impose greater impact than others — and the significance of the various mortality sources may vary throughout the life history of a species. However, accumulating evidence indicates that the heaviest mortality after the post-larval stage comes from predation (Cohen, Laurence, and Smith 1984). Predators are frequently other species. An understanding of this important component of M therefore, must consider interactions between species, which cannot be done using single-species production models. From the foregoing discussion, it is clear that practically all of the essential components in the simple stock-assess- ment model are estimated with a degree of uncertainty. The reliability of the estimated stock sizes and evaluation of the condition of resources are, therefore, correspondingly uncertain. Many of the uncertainties are attributable to the difficulties of assessing the dynamics of a number of species which have very complex environmental interactions. The animals cannot be directly observed in situ and they live in an environment which is neither readily accessible nor read- ily understood. Certain population fluctuations influence the condition of a stock more significantly than others. In most species — and in particular, in relatively short-lived species such as pollock and cod — recruitment is probably the most impor- tant population increment. An uncontrolled catch — partic- ularly for long-lived species — can be the major population decrement. Natural mortality is, however, the component which must be estimated with accuracv so that C can be adjusted both to it and to the population increments in order to achieve the desired biomass in year 2 (S7). Estimates of such components as the recruitment (A), the growth of the exploitable stock (G), and the catch of Gulf resources are amenable to improvement through better sampling techniques and analytical treatment. However, even these refinements will do little to improve estimates of these population parameters for some species unless ages can be estimated reliably. Also, since the estimates of A and G relate to the biomass of a single stock, it is necessarv to identify and estimate the biomass of all stocks of commer- cial species in the Gulf. Information on both subjects is diffi- cult to obtain. In the Gulf, there are several commercially important demersal fish species. Adults of these species typically inhabit different depth strata, although some have broad overlapping distributions or may migrate vertically through the water column. Throughout most of the year, they migrate various distances over the extensive (~2 x 10"' km'-) area of the Gulf shelf and slope. It is very difficult to obtain reliable biomass estimates for an ill-defined or unknown number of stocks for several different species, or to obtain estimates for all of the stocks for even a few species, when all of them are moving as well as growing and dving through- out most of the year over this large, three-dimensional space. In the North Sea — an area of about 5.0 x 10"' km- — much more effort is expended (Food and Agriculture Organization 1958), but even estimates of North Sea resources are not without some uncertainty. However, they are undoubtedly far more reliable than population esti- mates for the Gulf. Given the present costs of operating research vessels and realistic funding limitations, it is not clear whether continu- ing the surveys in the present mode will contribute to improved biomass estimates or simply add to a data set which has already reached its limits of accuracy and reliability. Some aspects of recruitment were discussed earlier in this section. Further understanding both of recruitment and of the causes for its variability require early life-history stud- ies— particularly on juveniles in the pre-recruitment size and age categories. With most fish and shellfish, there seems to be less known about this stage than about any other. Since larvae and young juveniles are especially at the mercy of their environment, understanding their mortality processes means understanding both ocean temperatures and cur- rents. We also need better knowledge regarding their prey and their predators. Little is known about the early juvenile stages of most marine fish and shellfish. Both sampling gear and sampling procedures have been developed to capture fish and shell- fish eggs and larvae. Modified commercial trawling gear is used to sample older juveniles and adults. With few excep- tions, neither sampling gear nor sampling strategies have been developed that can capture young juveniles (< 10 cm) or that can quantitatively sample pre-recruit juveniles. Abnormal development and extreme temperatures ma) cause high egg mortalitv rates. In all other life-history stages, however, predation is the most frequent cause of nat- 450 Biological Resources ural mortality. For a given stock, cannibalism may constitute a large part of predation. However, from egg stage right up through adulthood, all Gulf species are consumed by a vari- ety of predators. An understanding of Gulf predation will require accurate knowledge of both the qualitative and the quantitative food habits of the entire community of species. Abundant community members such as squid — which are known to be voracious predators — must be included in such studies. Salmon must not be overlooked as a substantial pelagic component of the Gulf even though we have not dealt with them in this chapter. Post-smoltjuvenile salmon are heavily preyed upon. However, by the time they reach both the immature and the maturing stages, they may be dominant predators in pelagic waters and may prey upon pelagic lar- vae and juveniles of other species such as rockfish and Pacific ocean perch. Acknowledgments Funding support for the preparation of this chapter was furnished by the Minerals Management Service, Depart- ment of the Interior, through an interagency agreement with the National Oceanic and Atmospheric Administra- tion, Department of Commerce, as part of the Outer Conti- nental Shelf Environmental Assessment Program. References Alaska Department of Fish and Game 1983 Westward region shellfish report to the Alaska Board of Fisheries. March 1983. Alaska Depart- ment of Fish and Game, Division of Commer- cial Fisheries, Westward Regional Office, Kodiak, AK. 330 pp. Alderdice, D.F. and F.P.J. Velsen 1971 Some effects of salinity and temperature on early development of Pacific herring (Clupea pallasi). Journal of the Fisheries Research Board of Canada 28:1545-1562. Alton, M.S. 1981 Gulf of Alaska bottomfish and shellfish resources. NOAA Technical Memorandum NMFS F/NWC 10. 51 pp. Alton, M.S. and R. Deriso 1983 Walleye pollock. In: Condition of groundfish resources of the Gulf of Alaska in 1982. J. Bal- siger, editor. NOAA Technical Memorandum NMFS F/NWC-52. 204 pp. Alverson, D.L. and S.J. Westrheim 1961 A review of the taxonomy and biology of the Pacific ocean perch and its fishery. Conseil Per- manent International pour I'Exploration del la Mer, Rapports et Proces-Verbaux des Reunions 150:12-27. Alverson, D.L., A.T. Pruter, and L.L. Ronholt 1964 A Study of Demersal Fishes and Fisheries of the North- eastern Pacific Ocean. H.R. MacMillan Lectures in Fisheries. Institute of Fisheries, University of British Columbia, Vancouver, B.C. 190 pp. Anderson, J.T. 1984 Early life history of redfish (Sebastes spp.) on Flemish Cap. Canadian Journal of Fisheries and Aquatic Sciences 41:1106-1116. Bakkala, R.G. and L.L. Low, editors 1985 Condition of groundfish resources of the east- ern Bering Sea and Aleutian region in 1984. NOAA Technical Memorandum NMFS F/ NWC-83. 202 pp. Bakkala, R. and V. Wespestad 1985 Walleye pollock. In: Condition of groundfish resources of the eastern Bering Sea and Aleu- tian region in 1984. R.G. Bakkala and L.L. Low, editors. NOAA Technical Memorandum NMFS F/NWC-83. 202 pp. Bakkala, R., T. Maeda, and G. McFarlane 1984 Distribution and stock structure of pollock (Theragra chalcogramma) in the North Pacific Ocean. International North Pacific Fisheries Commission Bulletin No. 45. pp. 3-20. Bakkala, R., S. Westrheim, K. Okada, C. Zhang, and E. Brown 1981 Overall distribution of Pacific cod in the North Pacific Ocean. International North Pacific Fisheries Commission Bulletin No. 42. pp. 111-116. Balsiger,J.W. 1983 Sablefish. In: Conditon of groundfish resources of the Gulf of Alaska. D.H. Ito and J.W. Balsiger, editors. NOAA Technical Memo- randum NMFS F/NWC-83. pp. 63-86. Bannister, R.C.A., D. Harding, and S.J. Lockwood 1974 Larval mortality and subsequent year-class strength in the plaice (Pleuronectes platessa L.). In: The Early Life History of Fish. J.H.S. Blaxter, editor. Springer- Verlag, Berlin, pp. 21-37. Baranov, F.T. 1918 On the question of the biological basis of fish- eries. Nauchnyi Issledovatelskii Ikhtiologischeskii Institut Isvestia 1:81-128. Marine Fisheries 451 Barsukov, V.V. 1964 Interspecies variability of the Pacific ocean perch (Sebastodes alutus Gilbert). Trudy Vsesoiuznyi Nauchno-isslcdovatel'skii Institut Mor- skogo Rybnogo Khoziaistva i Okeanografii 49 (Izvestiia Tikhookeanskogo Nauchno-issle- dovatel'skogo Instituta Morskogo Rybnogo Khozi- aistva i Okeanografii 51):231-252. (Translation, 1968, In: Soviet Fisheries Investigations in the North- east Pacific, Part II. P.A. Moiseev, editor. Israel Program for Scientific Translations, pp. 241-261.) Beamish, R.J. 1979 New information on the longevity of Pacific ocean perch (Sebastes alutus). Journal of the Fish- eries Research Board of Canada 36:1395-1400. Bell, F.H. 1981 The Pacific Halibut: The Resource and the Fishery. Alaska Northwest Publishing Co., Anchorage, AK. 267 pp. Berzin, A.A. 1970 Kashalot [The Sperm Whale]. Tikhookeanskii Nauchno-issledovatel'skii Institute Rhybnogo Khozyaistva Okeanographii, Moscow, USSR. 367 pp. (in Russian) (Translated by Israel Pro- gram for Scientific Translations. 1972. 394 pp.) Best, E.A. 1981 Halibut ecology. In: The Bering Sea Shelf- Oceanography and Resources, Vol. I. D.W. Hood andJ.A. Calder, editors. Office of Marine Pollu- tion Assessment, NOAA. Distributed by the University of Washington Press, Seattle, WA. pp. 495-509. Blackburn, J.E., K. Anderson, C.I. Hamilton, and S.J. Starr 1983 Pelagic and demersal fish assessment in the lower Cook Inlet Estuary System. Outer Conti- nental Shelf Environmental Assessment Program, Final Reports of Principal Investigators 17(Biolog- ical Studies):107-450. Buck, E.H. 1973 National patterns and trends of fishery devel- opment in the North Pacific. Alaska Sea Grant Program Report No. 73-4, Arctic Environmen- tal Information and Data Center, University of Alaska, Anchorage, AK. 65 pp. Carlson, H.R. 1980 Herring research in the Gulf of Alaska - a his- toric overview. Proceedings of the Alaska Herring Symposium, February 19-21, 1980, Anchorage, AK. B.R. Melteff and V.G. Wespestad, editors. Alaska Sea Grant Report 84-4, University of Alaska, Fairbanks, AK. pp. 63-68. Carruthers, J.N., A.L. Lawford, and V.F.C. Veley 1951 Fishery hydrography: brood-strength fluctua- tions in various North Sea fish, with suggested methods of prediction. Kieler Meeresforschungen 8:5-15. Chen, L.-C. 1971 Systematics, variation, distribution, and biol- ogy of rockfishes of the subgenus Sebastomus (Pisces, Scorpaenidae, Sebastes). Scripps Institu- tion of Oceanography Bulletin 18. 115 pp. Chikuni, S. 1975 Biological study on the population of the Pacific ocean perch in the North Pacific. Far Seas Fisheries Research Laboratory Bulletin No. 12. 119 pp. Chilton, D.E. and R.J. Beamish 1982 Age determination methods for fishes studied by the groundfish program at the Pacific Bio- logical Station. Canadian Special Publications of Fisheries and Aquatic Sciences 60. 102 pp. Clarke, M.R. 1977 Beaks, nets and numbers. In: The Biology of Cephalopods. M. Nixon andJ.B. Messenger, edi- tors. Academic Press, New York, NY. pp. 89-126 Cohen, E.B., G.C. Laurence, and W.G. Smith 1984 The role of starvation and predation in regulat- ing year class strength in several fish stocks on Georges Bank. Conseil International pour FExploration de la Mer, 1984 meeting, Copenhagen, Denmark. Demersal Fish Com- mittee Paper G:32. 19 pp. Cushing, D.H. 1974 The possible density-dependence of larval mortality and adult mortality in fishes. In: Tlic Early Life History of Fish. J.H.S. Blaxter, editor. Springer-Verlag, Berlin, pp. 103-111. Cushing, D.H., editor. 1983 Key Papers on Fish Populations. IRL Press, Oxford. 405 pp. Dietrich, G. 1965 New hydrographical aspects of the northwest Atlantic. International Commission for the North- west Atlantic Fisheries Special Publication 6:29-51. Dodimead, A.J., F. Favorite, and T. Hirano 1963 Salmon of the North Pacific Ocean, part II. Review of oceanography of the subarctic Pacific region. International North Pacific Fisheries Commission Bulletin No. 13. 195 pp. 452 Biological Resources Fadeev, N.S. 1968 Migrations of Pacific ocean perch. Izvestiia Tikhookeanskogo Nauchno-issledovatel'skogo Instituta Morskogo Rybnogo Khoziaistva i Okeanografii 64:170-177. (Fisheries Research Board of Canada Translation Series No. 1447) FAO 1958 Directory of Fisheries Institutions (Europe). Food and Agricultural Organization of the United Nations (Fisheries Division), Rome. Sections paginated separately. Favorite, F. and D.M. Fisk 1971 Drift bottle experiments in the North Pacific Ocean and Bering Sea— 1957-60, 1962, 1966, and 1970. U.S. Department of Commerce, NOAA, National Marine Fisheries Service, Data Report 67. 20 pp. Favorite, F. and W.J. Ingraham, Jr. 1976 On flow in the northwestern Gulf of Alaska, May 1972. Journal of the Oceanographical Society of Japan 33(2):66-81. Favorite, F. and D.R. McLain 1973 Coherence in transpacific movements of positive and negative anomalies of sea suface temperature, 1953-60. Nature (London) 244:139-143. Favorite, F., A.J. Dodimead, and K. Nasu 1976 Oceanography of the subarctic Pacific region, 1960-71. International North Pacific Fisheries Commission Bulletin No. 33. 187 pp. Favorite, F., T. Laevastu, and R.R. Straty 1977 Oceanography of the northeastern Pacific Ocean and eastern Bering Sea and relations to various living marine resources. Processed report, Northwest and Alaska Fisheries Center, National Marine Fisheries Service, NOAA, Seattle, WA. 280 pp. Feder, H.M. and M.K. Hoberg 1983 The distribution, abundance and diversity of the epifaunal benthic organisms in two bays (Alitak and Ugak) of Kodiak Island, Alaska. Environmental Assessment of the Alaskan Continen- tal Shelf Final Reports of Principal Investigators 14(Biological Studies):l-43. Feder, H.M., A.J. Paul, M. Hoberg, S. Jewett, G. Matheke, K. McCumby, J. McDonald, R. Rice, and P. Shoemaker 1981 Distribution abundance, community structure and trophic relationships of the nearshore benthos of Cook Inlet. Environmental Assessment of the Alaskan Continental Shelf Final Reports of Principal Investigators 14(Biological Stud- ies):45-676. Forrester, C.R. and D.F. Alderdice 1973 Laboratory observations on early development of the Pacific halibut. International Pacific Halibut Commission Technical Report 9. 13 pp. Fredin, R.A. 1985 The Pacific cod (Gadus macrocephalus) in the Bering Sea. Processed Report 84-8505, North- west and Alaska Fisheries Center, National Marine Fisheries Service, NOAA, Seattle, WA. 58 pp. Frederikhsen, A.V. 1977 Identification of species of the genus Sebastes from bones found in the stomach of the sperm- whale (Physeter catadon). Journal of Ichthyology 17:483-487. French, R„ H. Bilton, M. Osako, and A. Hartt 1976 Distribution and origin of sockeye salmon (Oncorhynchus nerka) in offshore waters of the North Pacific Ocean. International North Pacific Fisheries Commission Bulletin No. 34. 113 pp. French, R., R. Nelson, Jr., J. Wall, J. Berger, and B. Gibbs 1981 Summaries of provisional foreign and joint- venture groundfish catches (metric tons) in the northeast Pacific Ocean and Bering Sea, 1981. Unpublished manuscript, Northwest and Alaska Fisheries Center report, National Marine Fisheries Service, NOAA, Seattle, WA. 183 pp. Godfrey, H., K.A. Henry, and S. Machidori 1975 Distribution and abundance of coho salmon in offshore waters of the North Pacific Ocean. International North Pacific Fisheries Commis- sion Bulletin No. 31. 80 pp. Gong, Y. and M.Y. Oh 1977 Oceanographic environments and fisheries resources off the east coast of Korea. Korean National Federation of Fisheries Cooperatives. 633 pp. (in Korean) Gong, Y. and C.I. Zhang 1983 The walleye pollock (Theragra chalcogramma) stock in Korean waters. International North Pacific Fisheries Commission International Groundfish Symposium, Anchorage, AK, October 26-28, 1983. 37 pp. Gorbunova, N.N. 1954 The reproduction and development of walleye pollock (Theragra chalcogramma) (Pallas). Akademiia Nauk SSSR Trudy Instituta Okeanologii 11:132-195. (In Russian. English translation, Northwest and Alaska Fisheries Center, National Marine Fisheries Service, NOAA, Seattle, WA.) Marine Fisheries 453 Grant, W.S. and F.M. Utter 1980 Biochemical genetic variation in walleye pol- lock, Theragra chalcogram ma: population struc- ture in the southeastern Bering Sea and the Gulf of Alaska. Canadian journal of Fisheries and Aquatic Sciences 37:1093-1100. Griffin, K.L., M.F. Eaton, and R. Otto 1983 An observer program to gather in-season and post-season on-the-grounds red king crab catch data in the southeastern Bering Sea. Final report, Contract No. 82-2, North Pacific Fish- ery Management Council, December 1983. 39 pp. Gunderson, D.R. 1977 Population biology of Pacific ocean perch, Sebastes alutus, stocks in the Washington- Queen Charlotte Sound Region, and their response to fishing. Fishery Bulletin (U.S.) 75:369-403. Gunderson, D.R. 1983 Interannual variability of the environment and gadoid fisheries of the Gulf of Alaska and east- ern Bering Sea. In: From Year to Year: Interannual Variability of the Environment and Fisheries of the Gulf of Alaska and the Eastern Bering Sea. W.S. Wooster, editor. Washington Sea Grant Pub- lication 83-3, University of Washington, Seattle, WA. pp. 61-69. Gusey, W.F. 1978 The fish and wildlife resources of the Gulf of Alaska. Environmental Affairs, Shell Oil Co., Houston, TX. 580 pp. Hart,J.L. 1973 Pacific fishes of Canada. Fisheries Research Board of Canada Bulletin 180. 740 pp. Hayes, M.L. 1983 Variation in the abundance of crab and shrimp with some hypotheses on its relationship to environmental causes. In: From Year to Year: Interannual Variability of the Environment and Fish- eries of the Gulf of Alaska and the Eastern Bering Sea. W.S. Wooster, editor. Washington Sea Grant Publication 83-3, University of Washington, Seatde, WA. pp. 86-101. Hayes, M.L. and D.T. Montgomery 1963 Movements of king crabs tagged and released in Shumagin Islands area, 1957-62. U.S. Fish, and Wildlife Service SSRF-458. 7 pp. Hirschberger, W.A. and G.B. Smith 1983 Spawning of twelve groundfish species in the Alaska and Pacific coast regions, 1975-81. XOAA Technical Memorandum NMFS F/ NWC-44. 50 pp. Hourston, A.S. 1980 The biological aspects of management of Can- ada's west coast herring resource. Proceedings of the Alaska Herring Symposium. B.R. Melteff and V.G. Wespestad, editors. Alaska Sea Grant Report 80-4, University of Alaska, Fairbanks, AK. pp. 69-90. Hughes, S.E. and R.F. Draves 1984 U.S./Nippon Suisan joint venture winter pol- lock fishery in Shelikof Strait and the Bering Sea, January 27-April 15, 1984. Natural Resource Consultants, Seattle, WA. 50 pp. Hughes, S.E. and G. Hirschhorn 1979 Biology of walleye pollock, Theragra chal- cogramma, in the western Gulf of Alaska, 1973-75. Fishery Bulletin (U.S.) 77:263-274. Ingraham, W.J. , Jr. 1979 The anomalous surface salinity minima area across the northern Gulf of Alaska and its rela- tion to fisheries. Marine Fisheries Review 41(5-6):8-19. Ingraham, W.J., Jr. 1981 Environment of pink shrimp in the western Gulf of Alaska. Proceedings of the Pandalid Shrimp Symposium. T. Frady, editor. Sea Grant Report 81-3, University of Alaska, Fairbanks, AK. pp. 361-375. Ingraham, W.J. , Jr., A. Bakun, and F. Favorite 1976 Physical oceanography of the Gulf of Alaska. Outer Continental Shelf Environmental Assessment Program, Final Reports of Principal Investigators 34:97-124. Ito, D. H. 1982 A cohort analysis of Pacific ocean perch stocks from the Gulf of Alaska and Bering Sea regions. Processed Report 82-15, Northwest and Alaska Fisheries Center, National Marine Fisheries Service, NOAA, Seattle, WA. 157 pp. Ito, D. H. 1983 Condition of groundfish resources of the east- ern Bering Sea and Aleutian Islands region in 1982. R.G. Bakkala and L.L. Low, editors. NOAA Technical Memorandum NMFS F/ NWC-42. pp. 127-162. Ito, D. H. 1984 Pacific ocean perch. In: Condition of groundfish resources of the eastern Bering Sea and Aleutian Islands region in 1983. R.G. Bak- kala and L.L. Low, editors. NOAA Technical Memorandum NMFS F/NWC-53. pp. 109-142. 454 Biological Resources Ito, D.H. andJ.W. Balsiger, editors 1983 Condition of groundfish resources of the Gulf of Alaska in 1982. NOAA Technical Memoran- dum NMFS F/NWC-52. 204 pp. Ivanov, B.G. 1963 Some data on the biology of shrimp in the west- ern part of the Gulf of Alaska. In: Soviet Fisheries Investigations in the Northeast Pacific, Part I. P.A. Moiseev, editor. Israel Program for Scientific Translations. 1968. pp. 218-230. Ivanov, B.G. 1964 Biology and distribution of shrimps during winter in the Gulf of Alaska and the Bering Sea. In: Soviet Fisheries Investigations in the Northeast Pacific, Part III. P.A. Moiseev, editor. Israel Pro- gram for Scientific Translations. 1968. pp. 176-190. Kendall, A.W.,Jr., J.R. Dunn, and R.J. Wolotira 1980 Zooplankton, including ichthyoplankton and decopod larvae of the Kodiak shelf. Processed Report 80-8, Northwest and Alaska Fisheries Center, National Marine Fisheries Service, NOAA, Seattle, WA. 393 pp. Ketchen, K.S. 1961 Observations on the ecology of the Pacific cod (Gadiis macrocephalns) in Canadian waters. Jour- nal of the Fisheries Research Board of Canada 18:513-558. Kodolov, L.S. 1968 Reproduction of the sablefish [(Anoplopoma fimbria (Pall.)]. Voprosy Ikhtiologii 8:662-668. (in Russian) (Translation in Problems of Ichthyology 8:531-535.) Kodolov, L.S. 1970 Squids of the Bering Sea. In: Soviet Fisheries Investigations in the Nortlieast Pacific, Part V. P.A. Moiseev, editor. Israel Program for Scientific Translations. 1972. pp. 157-160. Laevastu, T. and H.A. Larkins 1981 Marine Fisheries Ecosystem. Fishery News Books, Ltd. Farnham, England. 162 pp. Larkins, H.A. 1964 Some epipelagic fishes of the North Pacific Ocean, Bering Sea, and Gulf of Alaska. Transac- tions of the American Fisheries Society 93:286-290. Lensink, C.J. andJ.C. Bartonek 1976 Preliminary catalogue of seabird colonies and photographic mapping of seabird colonies. U.S. Fish and Wildlife Service, Anchorage, AK. 138 pp. Lisovenko, L.A. 1965 Fecundity ofSebastodes alutus Gilbert in the Gulf of Alaska. In: Soviet Fisheries Investigations in the Northeastern Pacific, Part IV. P.A. Moiseev, edi- tor. Israel Program for Scientific Translations. 1968. pp. 162-169. Livingston, P.A. 1977 Numerical evaluation of marine biomasses in the Gulf of Alaska: an evolution of minimum sustainable biomasses of fisheries resources in the Gulf of Alaska using the Laevastu-Favorite bulk biomass model. Northwest and Alaska Fisheries Center report, National Marine Fish- eries Service, NOAA, Seattle, WA. 61 pp. Livingston, P.A. 1983 Food habits of Pacific whiting, Merluccius prod- uctus, off the west coast of North America, 1967 and 1980. Fishery Bulletin (U.S.) 81:629-636. Livingston, P.A. and B.J. Goiney, Jr. 1983 Food habits literature of North Pacific marine fishes: a review and selected bibliography. NOAA Technical Memorandum NMFS F/ NWC-54. 81 pp. Low, L.L., G.K. Tanonaka, and H.H. Shippen 1976 Sablefish of the northeastern Pacific Ocean and Bering Sea. Processed report, Northwest and Alaska Fisheries Center, National Marine Fisheries Service, NOAA, Seattle, WA. 115 pp. Lukas,J. 1981 Review of the Oregon pink shrimp fishery, management strategy and research activities. In: Proceedings of the International Pandalid Shrimp Symposium. T. Frady, editor. University of Alaska Sea Grant Report 81-3, University of Alaska, Fairbanks, AK. pp. 63-72. Lyubimova, T.G. 1964 Biological characteristics of the school of Pacific rockfish (Sebastodes alutus G.) in the Gulf of Alaska. In: Soviet Fisheries Investigations in the Northeast Pacific, Part III. P.A. Moiseev, editor. Israel Program for Scientific Translations. 1968. pp. 208-216. Lyubimova, T.G. 1965 Main stages in the life cycle of the rockfish Sebastodes alutus Gilbert in the Gulf of Alaska. In: Soviet Fisheries Investigations in the Northeast Pacific, Part IV. P.A. Moiseev, editor. Israel Pro- gram for Scientic Translations. 1968. pp. 85-111. Macy, P.T., J.M. Wall, N.D. Lampsakis, andJ.E. Mason 1978 Resources of non-salmonid pelagic fishes of the Gulf of Alaska and eastern Bering Sea. Part 1. Manuscript report, Northwest and Alaska Fisheries Center, National Marine Fisheries Service, NOAA, Seattle, WA. 355 pp. Marine Fisheries 455 Major, R.L. 1986 Condition of groundfish resources of the Gulf of Alaska Region as assessed in 1986. Document submitted to the Annual Meeting of the Inter- national North Pacific Fisheries Commission, October 1986, Anchorage, AK. 309 pp. Major, R.L., J. Ito, S. Ito, and H. Godfrey 1978 Distribution and origin of Chinook salmon in offshore waters of the North Pacific Ocean. International North Pacific Fisheries Commis- sion Bulletin No. 38. 54 pp. Marukavva, H. 1933 Biological and fishery research on Japanese king crab Paralithodes camtschatica (Tilesius). Journal of the Imperial Fisheries Experiment Station, Tokyo, Paper 37, No. 4. 152 pp. McEvven, G.F., T.G. Thompson, and R. Van Cleve 1930 Hvdrographic sections and calculated currents in the Gulf of Alaska, 1927 to 1928. Report of the International Fisheries Commission No. 4. 36 pp. Melteff, B.R. and V.G. Wespestad, editors 1980 Proceedings of the Alaska Herring Symposium. Alaska Sea Grant Report 80-4, University of Alaska, Fairbanks, AK. 274 pp. Muench, R.D. andJ.D. Schumacher 1980 Physical oceanographic and meteorological conditions in the northwest Gulf of Alaska. NOAA Technical Memorandom ERL/ PMEL-22. 147 pp. Musienko, L.N. 1970 Reproduction and development of Bering Sea fisheries. In: Soviet Fisheries Investigations in the Northeastern Pacific, Part V. P.A. Moiseev, editor. Israel Program for Scientific Translations. 1972. pp. 161-224. Naito, M., K. Murakami, and T. Kobayashi 1977 Growth and food habits of oceanic squids (Onnastrephes bartrami, Onychoteuthis boreali- japonicus, Berrytouthis magister and Gonatopsis borealis) in the western subarctic Pacific region. Fisheries Biology Prod. Subarctic Pacific Region Faculty of Fisheries, Hokkaido Univer- sity, Hakodate Japan, pp. 321-337. Neave, F.T., T. Yonemori, and R. Bakkala 1976 Distribution and origin of chum salmon in off- shore waters of the North Pacific Ocean. Inter- national North Pacific Fisheries Commission Bulletin No. 35. 79 pp. Nelson, R.,Jr., J. Wall, and J. Berger 1983 Summary of U.S. observer sampling on foreign and joint-venture fisheries in the northeast Pacific Ocean and the eastern Bering Sea, 1982. Document submitted to the annual meeting of the International North Pacific Fisheries Com- mission, Anchorage, AK, October 1983. 223 pp. Niebauer, H.J. 1981 Observations on sea surface temperature changes around Kodiak. In: Proceedings of the International Pandalid Shrimp Symposium. T. Frady, editor. Sea Grant Report 81-3, Univer- sity of Alaska, Fairbanks, AK. pp. 377-379 Niggol, K. 1982 Data on fish species from Bering Sea and Gulf of Alaska. NOAA Technical Memorandum NMFS F/NWC-29. 125 pp. Nikitinskaya, I.V. 1958 On the onset of active feeding of the larvae of Clupea harengus pallasi Val. Zoologicheski Zhurnal 37:1571-1574. (in Russian, Translation [1959] available from the National Marine Fisheries Service Language Service Division, Depart- ment of Commerce, Washington D.C. ) Nunnallee, E.P., N.J. Williamson, and M.O. Nelson 1982 Acoustic trawl survey of spawning walleye pol- lock (Theragra chalcogramma) in the Shelikof Strait-Chirikof region of the Gulf of Alaska in 1980 and 1981. Northwest and Alaska Fisheries Center report, National Marine Fisheries Sen- ice, NOAA, Seattle, WA. 31 pp. Okada, K. and H. Yamaguchi 1983 Results of the Japanese hydroacoustic survey of pollock in the Aleutian Basin. In: Results of cooperative groundfish investigations in the Bering Sea during May-August 1979. R.G. Bak- kala and K. Wakabayashi, editors. Northwest and Alaska Fisheries Center report, National Marine Fisheries Service, NOAA, Seattle, WA. pp. 329-339. Okutani, T. 1977 Stock assessment of cephalopod resources fished by Japan. Food and Agriculture Organi- zation of the United Nations, Fisheries Tech- nical Paper 173. 62 pp. Okutani, T. and T. Nemoto 1964 Squids as the food of sperm whales in the Ber- ing Sea and Alaskan Gulf. The Scientific Reports of the W^hales Research Institute 18:111-122. 456 Biological Resources Otto, R.S., R.A. Macintosh, K.L. Stahl-Johnson, and S.J. Wilson 1983 United States crab research in the eastern Ber- ing Sea during 1983. Document submitted to the Annual Meeting of the International North Pacific Fisheries Commission, Anchorage, AK, from Northwest and Alaska Fisheries Center, National Marine Fisheries Service, NOAA, Seattle, WA. 55pp. Paraketsov, I.A. 1963 On the biology of Sebastodes alutus in the Bering Sea. In: Soviet Fisheries Investigations in the North- eastern Pacific, Part I. P.A. Moiseev, editor. Israel Program for Scientific Translations. 1968. pp. 319-327. Parrish, B.B. and A. Saville 1965 The biology of the north-east Atlantic herring populations. Oceanography and Marine Biology 3:323-373. Pautov, G.B. 1972 Some characteristic features of the biology of Pacific ocean perch (Sebastodes alutus Gilbert) in the Bering Sea. Izvestiia Tikhookeanskogo Nau- cho-issledovatel 'skogo Instituta Rybnogo Khozyaistva i Okeanograffii (TINRO) [Proceedings of Pacific Scientific Research Institute of Marine Fish- eries and Oceanography] 81:91-117. Fisheries Research Board of Canada Translation Series No. 2828. Pereyra, W.T., J.E. Reeves, and R.G. Bakkala 1976 Demersal fish and shellfish resources of the eastern Bering Sea in the baseline year 1975. Northwest and Alaska Fisheries Center proc- essed report, National Marine Fisheries Serv- ice, NOAA, Seattle, WA. 619 pp. Petersen, C.G.J. 1894 On the biology of our flatfishes and on the decrease of our flatfishes. Report of the Danish Biological Station 4:1-146. Phillips, J.B. 1957 A review of the rockfishes of California (family Scorpaenidae). California Department of Fish and Game, Fish Bulletin 104. 158 pp. Plakhotnik, A.F. 1964 Hydrologic description of the Gulf of Alaska. In: Soviet Fisheries Investigations in the Northeast Pacific, Part II. P.A. Moiseev, editor. Israel Pro- gram for Scientific Translations. 1968. pp. 13-47. Powell, G.C. 1964 Fishing mortality and movements of adult male king crabs, Paralithodes camtschatica (Tilesius), released seaward from Kodiak Island, Alaska. Transactions of the American Fish- eries Society 93:295-300. Powell, G.C. and R.E. Reynolds 1965 Movements of tagged king crabs, Paralithodes camtschatica (Tilesius), in the Kodiak Island-lower Cook Inlet region of Alaska, 1954-1963. Alaska Department of Fish and Game Information Leaflet No. 55. 108 pp. Quast, J.C. and E.L. Hall 1972 List of fishes of Alaska and adjacent waters with a guide to some of their literature. NOAA Technical Report NMFS SSRF-658. 48 pp. Reed, R.K. 1980 Direct measurement of recirculation in the Alaskan Stream. Journal of Physical Oceanography 10:976-978. Rigby, P.W. 1984 Alaska domestic groundfish fishery for the years 1970 through 1980 with a review of two historic fisheries — Pacific cod (Gadus mac- rocephalus) and sablefish (Anoplopoma fimbria). Alaska Department Fish and Game Technical Data Report No. 108. 446 pp. Rogers, D.E., D.J. Robin, BJ. Rogers, K.J. Garrison, and M.E. Wangerin 1979 Seasonal composition and food web rela- tionships on marine organisms in the near- shore zone of Kodiak Island - including ichthyoplankton, macroplankton (shellfish), zooplankton, and fish. Annual Reports FRI-UW-7906 and FRI-UW-7925 to Outer Continental Shelf Environmental Assessment Program. Fisheries Research Institute, Univer- sity of Washington, Seattle, WA. 123 and 291 pp., respectively. Ronholt, L.L. 1983 Atka mackerel. In: Condition of groundfish resources of the Gulf of Alaska region as assessed in 1983. Processed Report 84-02, Northwest and Alaska Fisheries Center, National Marine Fisheries Service, NOAA, Seattle, WA. pp. 5-1 to 5-24. Ronholt, L.L., H.H. Shippen, and E.S. Brown 1978 Demersal fish and shellfish resources of the Gulf of Alaska from Cape Spencer to Unimak Pass 1948-1976: a historical review, Vol. 1. Environmental Assessment of the Alaskan Conti- nental Shelf, Final Reports of Principal Investigators 2(Biological Studies):l-304. Rosenthal, R.J. 1980 Shallow water fish assemblages in the northeast Gulf of Alaska: habitat evaluation, species com- position, abundance, spatial distribution and trophic interaction. Environmental Assessment of the Alaskan Continental Shelf, Final Reports of Principal Investigators 17(Biological Stud- ies):451-540. Marine Fisheries 457 Rosenthal, R.J., L. Haldorson, L.J. Field, T. O'Connell, M.G. LaRiviere, J. Underwood, and M.C. Murphy 1982 Inshore and shallow offshore bottomfish resources in the southeastern Gulf of Alaska (1981-1982). Alaska Department of Fish and Game. Juneau, AK. 166 pp. Rounsefell, G.A. 1929 Contribution to the biology of the Pacific her- ring, Clupea pallasii, and the condition of the fishery in Alaska. U.S. Bureau of Fisheries Bulletin 45:227-320. Rover, T.C., D.V. Hansen, and D.J. Pashinski 1979 Coastal flow in the northern Gulf of Alaska as observed by dynamic topography and satel- lite-tracked drogued drift buoys.Journal of Phys- ical Oceanography 9:785-801. Russell, E.S. 1931 Some theoretical considerations on the "over- fishing" problem. Journal du Conseil, Conseil Per- manent International pour VExploration de la Mer 6:3-20. Sasaki, T., D. Rodman, M. Onoda, and J. Rosapepe 1982 Preliminary report on Japan-U.S. joint long- line survey for sablefish and Pacific cod by Anyo Maru No. 22 in the Aleutian region and the Gulf of Alaska in summer of 1981. Far Seas Fish- eries Research Laboratory, Japan Fisheries Agency. Shimizu, Japan. 88 pp. Sasaki, T., D. Rodman, M. Onoda, and J. Rosapepe 1984 Sablefish fishery in the North Pacific Ocean. Bulletin of the Far Seas Fisheries Research Lab- oratory No. 21. pp. 83-114. Scheffer, V.B. 1972 Marine mammals in the Gulf of Alaska. In: A review of the oceanography and renewable resources of the northern Gulf of Alaska. D.H. Rosenberg, editor. Alaska Sea Grant Report 73-3, Institute of Marine Science, University of Alaska, Fairbanks, AK. pp. 175-207. Schumacher, J. D. and R.K. Reed 1980 Coastal flow in the northwest Gulf of Alaska: the Kenai Current. Journal of Geophysical Research 85C:6680-6688 . Simpson, R.R. and H.H. Shippen 1968 Movement and recovery of tagged king crabs in the eastern Bering Sea, 1955-63. International North Pacific Fisheries Commission Bulletin No. 24. pp. 111-123. Skud, B.E. 1977 Drift, migration and intermingling of Pacific halibut stocks. International Pacific Halibut Commission Scientific Report No. 63, Seattle, WA. 42 pp. Snytko, V.A. 1971 Biology and peculiarities of distribution of Pacific ocean perch (Sebastodes alutus) in Van- couver-Oregon area. Izvestiia Tikhookeanskogo Nauchno-issledovatel'skogo instituta Rybnogo Khoziaistva i Okearwgraffii (TINRO) [Proceedings of the Pacific Scientific Research Institute of Marine Fishes and Oceanography] 79:3-41. Fisheries Research Board of Canada Transla- tion Series No. 2805. St-Pierre, G. 1984 Spawning locations and seasons for Pacific halibut. Scientific Report 70, International Pacific Halibut Commission, Seattle, WA. 46 pp. Strickland, R.M. and T. Sibley 1985 Potential effects of water transport on the wall- eye pollock (Theragra chalcogramma Pallas) fish- ery in the Gulf of Alaska. Paper submitted to the Workshop on Comparative Biology, Assess- ment, and Management of Gadoids from the North Pacific and Atlantic Oceans, Seattle, WA, 24-28 June 1985.Jointly hosted by the Uni- versity of Washington, Seattle, WA; and the University of Oslo, Oslo, Norway. 35 pp. Svetovidov, A.N. 1948 Gadiformes. In: Fauna of the U.S.S.R.: Fishes. Israel Program for Scientific Translations. 1962. Vol. 9 (4):77-304. Takagi, K., K.V. Aro, A.C. Hartt, and M.B. Dell 1981 Distribution and origin of pink salmon (Oncorhynchus gorbuscha) in offshore waters of the North Pacific Ocean. International North Pacific Fisheries Commission Bulletin No. 40. 195 pp. Takahashi, Y. and H. Yamaguchi 1972 Stock of the Alaskan pollock in the eastern Ber- ing Sea. Bulletin of the Japanese Society of Scientific Fisheries 38:418-419. Taning, A.V. 1949 On the breeding places and abundance of the red fish (Sebastes) in the North Atlantic. Journal du Conseil, Conseil Permanent International pour VExploration de la Mer 16:85-95. Templeman, W. 1959 Redfish distribution in the North Atlantic. Fisheries Research Board of Canada Bulletin No. 120. 173 pp. Tester, A.L. 1946 Comparison of the Atlantic and Pacific herring and herring fisheries. Fisheries Research Board of Canada, Progress Reports of the Pacific Coast Sta- tions 66:4-8. 458 Biolocical Resources Thompson, T.G., G.F. McEwen, and R. Van Cleve 1936 Hydrographic sections and calculated currents in the Gulf of Alaska, 1929. Report of the Inter- national Fisheries Commission No. 10. 32 pp. Uchida, K. 1964 Searching for the Juveniles. Iwanami Shinso series 535. 207 pp. Umeda, Y. and R. Bakkala 1983 Data Report: 1980 demersal trawl survey of the eastern Bering Sea continental shelf. NOAA Technical Memorandum NMFS F/NWC-49. 175 pp. Veshchezerov, V.V. 1944 Some materials on the biology and fisheries of Norway haddock (Sebastes marinus) of the Barents Sea. Trudy Poliarnogo Nauchno- issledovatel'skogo Instituta Morskogo Rybnogo Khoziaistva i Okeanografii 8:236-270. Waldron, K.D. 1981 Ichthyoplankton. In: The Eastern Bering Sea Shelf: Oceanography and Resources, Vol. 1. D.W. Hood andJ.A. Calder, editors. Office of Marine Pollu- tion Assessment, NOAA. Distributed by the University of Washington Press, Seattle, WA. pp. 471-493. Walford, L.A. 1938 Effects of currents on distribution and survival of the eggs and larvae of the haddock (Melanogrammus aeglefinus) on Georges Bank. U.S. Bureau of Fisheries Bulletin 49(29). 73 pp. Weingartner, T. 1981 Observations on temperature changes on the shelf of the Gulf of Alaska. Proceedings of the International Pandalid Shrimp Symposium. T. Frady, editor. Sea Grant Report 81-3, Univer- sity of Alaska, Fairbanks, AK. pp. 381-385. Westrheim, S.J. 1958 On the biology of the Pacific ocean perch, Sebastes alutus (Gilbert). M.S. Thesis, University of Washington, Seattle, WA. 106 pp. Westrheim, S.J. 1970 Survey of rockfishes, especially Pacific ocean perch, in the northeast Pacific Ocean, 1963-66. Journal of the Fisheries Research Board of Canada 27:1781-1809. Westrheim, S.J. 1977 Length-weight and length-girth relationships, maturity, spawning season and diet of Pacific cod (Gadus macrocephalus) collected in British Columbia waters during April 1975-February 1976. Fisheries Research Board of Canada Manuscript Report Series No. 1420. 68 pp. Yusa, T. 1954 On the normal development of the fish (Theragra chalcogramma) (Pallas) Alaska pollock. Bulletin of the Hokkaido Regional Fisheries Laboratory No. 10. 15 pp. Pacific Salmon 15 Donald E. Rogers Fisheries Research Institute University of Washington Seattle, Washington Abstract The Gulf of Alaska is the main oceanic nursery for most North American salmon. The annual abundance figures for the North American runs (catch plus escapement) are estimated from the catch and escapement statistics for the period 1950 through 1984. Both the numbers and the biomass for mature salmon that annually returned from the Gulf of Alaska were estimated by using a combination of North American run statistics and information on the oceanic distribution of the major stocks that resulted from INPFC-related research during the 1960s. The Gulf of Alaska produced — 2.5 x 105 mt of mature salmon annually during the period 1950 to 1977. In 1978, the annual runs increased, and during the period of 1981 through 1984, ~ 4 x 105 mt were produced annually. The abundance of the runs dur- ing the most recent years was probably comparable to the historical peak abundances of the 1930s. The average biomass of adult salmon was —30 times greater than the average biomass of juveniles that entered the offshore waters. Both the distribution and the growth of salmon at sea are affected by interannual temperature variations. Salmon tended to migrate earlier and grow more when tem- peratures were warmer and migrate later and grow less when temperatures were colder. Introduction Commercial fisheries on anadromous North American salmon {Oncorhynthus spp.) developed in the late 1800s, and by the 1920s nearly all of the more abundant North Ameri- can and Asian stocks were being exploited. The annual salmon catches reached a peak in the late 1930s on both the North American and Asian coasts with an average annual catch of 3.54 x 108 individual fish or -8.0 x 105 mt (Fredin 1980; International North Pacific Fisheries Commission [INPFC] 1979). Catches declined significantly in the mid-1940s to early 1950s. Then Japan mounted a highseas fishery which, by the late 1950s, had become the largest salmon fisher)' in the North Pacific — accounting for nearly 40% of the annual catch in numbers of salmon. However, the total catch remained relatively low until 1978, when high- seas fishing had been greatly reduced and there was a signifi- cant increase in abundance of most salmon stocks in west- ern and central Alaska (Rogers 1984). The North American catches of salmon during the period 1978 to 1983 were com- parable to the catches made during the historical peak pro- duction of the late 1930s (Table 15-1). The annual abundances of salmon runs (the return of mature fish to their spawning grounds for reproduction) are characterized both by considerable year-to-year varia- tion as well as by long-term changes in average abundance. For example, in the coastal areas of the upper Gulf of Alaska alone (north of 55°N), there were 1.6 x 107 salmon caught in 1974 and 9.0 x 107 caught in 1982. The 1982 catch of 1.92 x 105 mt translated into $217 million for commercial fish- ermen (Alaska Department of Fish and Game (ADF&G) 1984a). Some of the annual variability is explained by the abun- dance of parent spawners. Small numbers of spawners usu- ally produce small numbers of adults; however, average to large numbers of spawners can produce anywhere from small to large numbers of adults. For example, for stocks of Bristol Bay sockeye salmon (O. nerka), less than one and up to as many as 20 adults have returned per spawner from the 1956 to 1978 brood years. The causes of this variability in rel- ative production have been the subject of salmon research since the early 1900s; however, this research was largely directed toward the freshwater and nearshore marine phases of salmon life history until the late 1950s. 461 462 Biological Resources Table 15-1. Comparison of the average annual salmon catch both in Asia and in North America during the historical peak-production period (1934-1939) and the recent period (1978-1983). SOCKEYE Chum Pink Coho Chinook Total Number (x 106 fish) 1934-1939 Asia 15 49 154 3 0.2 221 N.Am. 34 14 73 8 3.7 133 Total 49 63 227 11 3.9 354 % N.Am. 69 22 32 73 95 38 1978-1983 Asia 4 38 84 3 0.3 129 N.Am. 42 12 68 10 4.3 136 Total 46 50 152 13 4.6 266 % N.Am. 91 24 45 77 93 51 Weici -IT(x 10= 1 nit) 1934-1939 Asia 43 176 216 10 2 447 N.Am. 93 62 134 30 28 347 Total 136 238 350 40 80 794 % N.Am. 68 26 38 75 93 44 1978-1983 Asia 9 126 116 8 2 261 N.Am. 113 48 118 30 29 338 Total 122 174 234 38 31 599 % N.Am. 93 28 50 79 94 56 Little was known about the oceanic life of the valuable North American stocks of Pacific salmon until a large research program was undertaken by scientists from Japan, Canada, and the United States in response to an extensive Japanese high-seas salmon fishery in the 1950s. Although this research was focused on the central Pacific (in the area of the fishery), a considerable amount of information was gained on salmon in the Gulf of Alaska. This information has been reported in the bulletins of the International North Pacific Fisheries Commission (INPFC 1974). Because salmon abundance has changed considerably since the Gulf of Alaska salmon research was done, the contemporary status of the stocks will be examined in this chapter. The Gulf of Alaska is the main oceanic nursery for most North American salmon, as well as for some Asian stocks for at least a significant part of their ocean life. Salmon proba- bly constitute over 95% of the large (> 20 cm) fish in the epipelagic offshore waters of the Gulf of Alaska and are the most economically important species in North American fisheries. The distribution of the larger regional stocks (e.g., Bristol Bay, upper Gulf of Alaska, British Columbia) are fairly well known — at least for the summer months (Royce, Smith, and Hartt 1968; French, Bilton, Osaka, and Hartt 1976; Neave, Yonemuri, and Bakkala 1976; Takagi, Aro, Hartt, and Dell 1981; Godfrey, Henry, and Machidori 1975; Major, Ito, Ito, and Godfrey 1978; and Hartt 1980). However, both their distributions and their migrations from fall to spring must be largely inferred from the early and late sum- mer distributions. The main objective of this chapter is to estimate both the annual number and the biomass of North American salmon that returned from the Gulf of Alaska since 1950. Informa- tion on the oceanic distribution of North American stocks is used first to estimate the annual abundance and then esti- mate the numbers of North American salmon that returned from the Gulf (east of 165°W and north of 50°N). Also dis- cussed in this chapter are some factors that likely affect the annual numbers and the weights of those salmon that return to coastal fisheries and spawning grounds. Life History Salmon spawn in the fall, usually in freshwater and nor- mally in the place where they originated. They die soon after spawning. The eggs, which are buried in the gravel, develop during the winter and the fry emerge in the spring. The remainder of the salmon life cycle varies both among spe- cies and among populations within species; however, they spend most of their life at sea and it is there that they attain most of their growth and reproductive potential. All of their ability to successfully complete their life must be inherited, because there is no contact with their parents. It is most likely that each generation of each population inherits the abilities to survive, grow, and reproduce that were most advantageous for the environment of their parents. Thus, changes in the environment will probably cause changes in the stocks. "In almost all cases where both genetic and environmental influences affecting natural stock dif- ferences among Pacific salmon and steelhead have been searched for adequately, both have been found; though sometimes one, sometimes the other, is relatively weak, or infrequently expressed" (Ricker 1972). The following is a brief description of the 'typical' life his- tories (i.e., the usual age and size both at seaward migration and at maturity) of the five species of Pacific salmon in North America. The largest spawning population of each species is generally distributed according to the habitat that particularly suits the species' reproductive and early life- history needs. These large spawning populations are the ones most often encountered in the Gulf. Individual Species Sockeye Salmon. Sockeye salmon (Oncorhynchus nerka) are associated with lakes, where they spawn near beaches or in tributary streams and rivers. The juveniles emerge from the gravel in the spring, then rear for one to two years before their seaward migration. They typically weigh between 5 and 10 g when they enter the sea, and after two to three years they return weighing about 2 to 3 kilograms. They are between three and five years old at maturity, but return from the sea between four and six years after their parents have returned. They are more dependent on freshwater rearing than the other species of Pacific salmon and have been the most difficult species to propagate artificially in hatcheries. Large sockeye concentrations are found both in Pacific Salmon 463 the large lake systems that drain into Bristol Bay and in the lakes of the Fraser River system. Their bright red flesh has made the sockeye the highest valued and most desirable salmon for canning. Pink Salmon. Pink salmon (Oncorhynchus gorbuscha) are associated with small- to intermediate-sized coastal rivers, with large concentrations occurring in southeastern Alaska, British Columbia, Prince William Sound, Kodiak, and a few large rivers such as the Nushagak and the Fraser. They migrate to sea soon after thev emerge in the spring, weigh- ing ~ 1 gram. They return the next year (summer-fall) at an average weight of between 1.5 and 2.0 kilograms. Since pink salmon have an invariable age structure, there are even- and odd-year runs, which do not interbreed. While there are strong even- and odd-year runs throughout the coastal regions of the Gulf, at present, only strong odd-year runs occur along the southern boundary of the large populations (Fraser River) and onlv strong even-year runs occur along the northern boundary of the large populations (Nushagak River). Historically, pink salmon have been more abundant in Asia than in North America. Chum Salmon. Chum salmon {Oncorhynchus keta) are also more abundant in Asia than in North America. Large chum salmon populations occur in all large northern rivers as well as in many of the same small- to intermediate-sized rivers used by pink salmon. Since the mid-1970s, the largest concentration of chum salmon has probably been from hatcheries in northern Japan. Natural populations of chum salmon migrate to sea in the same spring or early summer in which they emerge from the gravel and weigh ~1 gram. They return to spawn after two to four years at sea and weigh between 3 and 6 kilograms. Chum, pink, and sockeye salmon constitute about 90% of the number and weight of salmon in the North Pacific; however, the other salmon spe- cies in North America — coho {O. kisutch) and chinook (O. tshawytscha) — are most abundant in southern regions (Cal- ifornia to Washington). Coho Salmon. Coho salmon {Oncorhynchus kisutch) typ- ically spawn in tributary streams in river systems. The juve- niles spend one to two years in the stream (predominantly one year in the south and two years in the north) and they are the largest of the Pacific salmon when they migrate to sea, averaging between 10 and 20 grams. Hatcheries pres- ently produce a significant proportion of coho migrants, which may average two to three times heavier than natural migrants. Coho salmon spend one year at sea but return later in their second year (fall) than the other species, by which time they average 3 to 4 kilograms. There are few large coho concentrations other than those in Puget Sound and the Columbia River (now primarily from hatcheries). Rather, their abundance seems to be spread over a large area from Oregon to the central Gulf of Alaska. Their abun- dance in northern coastal areas is difficult to determine because the late-returning coho were not fished intensively. From 1956 to 1977, the high-seas fishery took 64% of the annual coho catch from northern waters. Chinook Salmon. Chinook salmon {Oncorhynchus tshawytscha) are the largest, the oldest at maturity, but the least-abundant species. They also have the most diverse life history and one that has been altered most by human activities {e.g., selective fisheries, dams, and hatcheries). They migrate to sea during their first or second year weighing ~ 8 to 10 g and commonly return after between two and four years at sea, weighing between 4 and 15 kilograms. Generalized Life History The life history of all five species is characterized by juve- nile salmon that usually migrate to sea in the spring when water temperature and photoperiod are increasing (Groot 1982). Migrations typically begin abruptly, reach a peak, and then have a long tail-off of stragglers. Since spring comes earlier in the southern portion of their range than it does in the northern portion, the southern stocks migrate to sea about two months earlier than northern stocks. Most north- ern stocks migrate to sea from mid-May to mid-July. In gen- eral, stocks located closer to the coast enter the sea first and those farthest from the coast enter last. This is not only because of the distance they must travel, but also because spring arrives later in the interior of the northern regions where winter ice must melt. Adult salmon usually return from the sea somewhat ear- lier than necessary for their fall spawning period. Their arrival in coastal waters usually begins abruptly with large numbers of fish arriving within a few days of the first fish. This is followed by a long tail-off with some fish arriving after spawning is underway. Although the first fish to return may spawn earlier or migrate farther, there are many exam- ples where stocks returned several weeks prior to spawning. In other cases, stocks that returned to the same area at differ- ent times spawned at about the same time. The spawning time for each population must be corre- lated with the temperature regime of the spawning grounds to ensure that eggs will develop and hatch, and that the fry will emerge at the right time in the spring for feeding and growth. Salmon may spawn later than normal — with their fry emerging in summer — but if they spawn too early and their offspring emerge in winter, the fry will likely not sur- vive (at least not in northern regions). Each stock, therefore, has a characteristic return and spawning time that is rather precise from year to year. Since fall arrives earlier to the north, northern stocks tend to return earlier than southern stocks. Chinook salmon usually return earliest (June) and coho salmon usually return latest (August-September). The timing of the returns for other species varies among stocks, and can range from mid-June to August. However, sockeye tend to return earlier than pink salmon and the chum salmon returns tend to overlap the return of other species. For example, in Bristol Bay, chum returns overlap with sockeye (in early July) and in Prince William Sound, chum returns overlap with returns for pink salmon (mid-July to mid-August). In southern regions, there is greater variability in timing among stocks — with significant numbers of salmon returning to coastal waters from June through November. 464 Biological Resources Annual Abundance Estimates To estimate the number of salmon returning to North America each year (the run), the number offish caught by a combination of commercial, sport, and subsistence fisheries is added to the number of fish that were not caught (the escapement). Commercial catch statistics are relatively pre- cise, and both sport and subsistence catches have negligible impact on the numbers for the majority of sockeye, chum, and pink salmon stocks. However, reasonably precise escapement estimates are available only for the larger stocks of sockeye salmon (data from weir and tower counts). Less precise estimates are available for pink and chum salmon escapements (data from aerial survey estimates). If the pro- portion of the run that was caught (rate of exploitation) is known or can be estimated, then the run (catch plus escape- ment) can be estimated by dividing the catch by the rate of exploitation. Annual runs (1950-1984) were estimated for the follow- ing regions: • western Alaska — the coastal waters of the Bering Sea from the Yukon River to Unimak Island • central Alaska — from Unimak Island to the Bering River • southeastern Alaska/northern British Columbia — from Yakutat to about 51°N • southern British Columbia to California. Catch statistics were obtained from Fredin (1980) and INPFC (1979) for the period 1950 to 1977. Regional catch data for recent years were obtained from statistical year- books of INPFC (1978-1981), preliminary reports of fishery management agencies such as ADF&G, and Fisheries and Oceans of British Columbia (1982-1984). Annual escapement estimates for stocks or groups of stocks within the regions were obtained from several sum- mary reports, including INPFC (1974), Beacham (1984), Starr and Petrie (1984), Henderson, Charles, and Starr (1984), Donnelly (1983), and McBride and Wilcock (1983). Other escapement estimates come from annual agency reports (Yuen 1984; McCurdy 1984; Cross, Bernard, and Mar- shall 1983; Roos 1984; and ADF&G 1984b). The regional sockeye runs were estimated by adding the runs of major stocks (for which escapements were known) to the catches of minor stocks, divided by the rate of exploita- tion on the major stocks. For the interception fishery in the Shumagin-Unimak Islands, the catches in June were added to the western Alaska run, and later catches were added to the central Alaska run. High-seas catches (west of 175°W) were not included in the estimated North American runs because it was unlikely that those salmon were in the Gulf of Alaska in the year of return. Relationships between rate of exploitation and standard- ized catch (annual catch minus average catch divided by standard deviation) were estimated for the major pink salmon stocks and some chum salmon stocks (Kodiak, Prince William Sound, British Columbia). Regressions were then used to estimate the rate of exploitation and hence the run for minor stocks and major stocks in years when escape- ments were unknown (typically prior to 1960). Exploitation rates for Alaskan pink salmon stocks were generally high (0.7-0.8) when catches were average to above average, but declined to about 0.4 when catches were about one standard deviation below the mean and declined further to 0.2 when they were more than one standard deviation below the mean. Exploitation rates on those chum salmon runs that went to Prince William Sound and Kodiak were between 90 and 94% of the rates on the pink salmon runs. Escapement figures for coho salmon runs in western and central Alaska were unknown. The annual coho runs to western Alaska were estimated from the catches by assum- ing an exploitation rate of 0.3 for 1950 to 1972 and an increasing rate of 0.4 to 0.6 from 1973 to 1982. The runs to central Alaska were estimated assuming rates of 0.4 to 0.6 for the period 1950 to 1982. Although escapement estimates were available for some southern stocks (e.g., Columbia River), coho salmon from southern stocks were caught in mixed-stock ocean fisheries from southeastern Alaska to California and it was not feasible to estimate the exploita- tion rate for individual groups within this region. Annual runs were estimated by assuming a gradually increasing exploitation rate that went from 0.60 (1950) to 0.75 (1982). Chinook salmon runs to western Alaska since 1965 were estimated by Rogers, Myers, Harris, Knudsen, Walker, and Davis (1984), and the runs in earlier years were estimated using catch data and the average exploitation rates during 1966 to 1975. Runs to central Alaska were estimated from the relatively small catches and an assumed exploitation rate of 0.5. Chinook salmon are fished intensively in mixed-stock fisheries from southeastern Alaska to California, and as with coho salmon, the annual runs were estimated for the com- bined region. Escapement estimates for the region were available for the period of 1975 to 1982, and the relationship between the catch and exploitation rate for those years was used to estimate the runs in other years. I estimated the biomass of the annual runs for each spe- cies by using the number of fish in the run and the mean weight in the commercial catch — except for Bristol Bay sockeye, where mean weights in the escapement were avail- able. Commercial fisheries, particularly gillnet fisheries, are typically size selective due to the fact that they under- exploit both the smaller individuals (e.g., jacks) and the largest individuals (Ricker 1982). Therefore, the mean weights in the catches may be somewhat biased because mean weight estimates are affected in some areas where a high proportion of the catch is made by giilnets (e.g., western Alaska). In addition to estimating the annual number and weight of adult salmon that returned from the Gulf of Alaska, I also estimated the approximate number of juvenile salmon (smolts) that annually migrated into the Gulf of Alaska. I divided the estimated number of returning adults (by year of seaward migration) by the marine survival averages reported in the literature (Mathews 1984; Bill 1984; McDonald and Hume 1984; and Peterman 1980). The ocean-age compositions of sockeye salmon runs were avail- able for most major stocks, and when they were not avail- able, ocean-age was estimated from regressions of age com- position (e.g., percentage age .3) on mean weight in the catch. A salmon's age is designated according to the number of Pacific Salmon 465 winters the fish spent in freshwater and in saltwater. For example, an age of 1.3 indicates that the fish spent one winter in freshwater (excluding winter as an egg or alevin) and three winters at sea; an age of .3 indicates that a fish spent three winters at sea regardless of the number of win- ters spent in freshwater. Sockeye that ranged from southern British Columbia to Washington were assumed to mature at age .2 and chum and chinook salmon were assumed to mature at age .3 (the average ocean-age at maturity). Adult Salmon Runs The annual North American salmon runs from 1950 to 1984 ranged from 9.0 x 107 fish in 1959 to 2.21 x 108 fish in 1980 and from 2.58 x 105 mt in 1959 to 5.48 x 105 mt in 1981. The lowest period of abundance was during 1972 through 1975 when the annual runs averaged 9.9 x 107 fish (2.9 x 105 mt). Then, just three years later, the runs increased and aver- aged 2.0 x 10« fish (5.03 x 105 mt) from 1978 to 1984. Most of the variation in North American salmon abundance since 1970 was caused by variation in pink and sockeye salmon abundance in central and western Alaska (Tables 15-2 to 15-6). Central Alaska pink salmon (mostly Kodiak and Prince William Sound stocks) constituted 34% of the North Ameri- can pink salmon runs during the period from 1950 to 1977, but constituted 46% of the pink salmon runs since 1978. The central Alaskan runs were consistently high in recent years, whereas the runs to the other regions varied considerably from year to year (Table 15-2). The central Alaskan sockeye stocks also increased in the late 1970s; however, the runs were not nearly as large as those from western Alaska (Table 15-3). The western Alaskan sockeye salmon (mostly Bristol Bay stocks) constituted 51% of the North American sockeye runs from 1950 to 1977 (annual range, 13 to 79%), but 65% of Table 15-2. Estimates of annual pink salmon (Oncorhynchus gorbiischa) runs in millions offish and thousands of metric tons. Numbers in parentheses are approximate. Southeastern Southern Western Central Alaska/Northern British Coluiy ibia/ North Alaska Alaska British Coll IMBIA Washington America Year No. Wt. No. Wt. No. Wt. No. Wt. No. Wt. 1950 + + 14 24 24 39 3 4 41 67 51 10 18 40 76 13 33 63 127 52 + + 16 26 28 51 4 7 48 84 53 14 26 14 27 18 47 47 100 54 + 1 21 35 23 42 1 2 45 80 55 21 37 22 44 15 40 57 121 56 + 1 20 33 30 52 2 3 52 89 57 9 16 20 39 13 31 42 86 58 5 7 20 33 25 47 2 4 52 91 59 7 12 17 33 10 22 34 67 1960 1 1 18 26 12 21 1 1 31 49 61 13 28 27 66 5 14 45 108 62 2 2 39 53 45 81 1 3 87 139 63 19 33 36 56 16 36 70 125 64 3 3 34 52 38 65 1 2 75 122 65 13 20 22 40 4 9 38 69 66 4 6 22 38 45 90 5 8 76 142 67 6 12 9 20 15 37 31 69 68 5 7 22 34 52 74 5 7 84 122 69 24 46 11 22 4 11 40 79 1970 1 1 24 40 31 55 4 7 60 103 71 19 31 21 36 11 24 50 91 72 + + 5 10 37 49 1 2 43 61 73 5 10 15 25 9 20 30 55 74 2 4 7 14 17 29 3 4 29 51 75 12 21 13 23 7 16 32 60 76 2 3 23 44 20 37 5 18 51 92 77 19 36 31 69 10 24 59 129 78 18 23 36 59 40 58 2 3 95 143 79 46 77 25 46 14 31 85 154 1980 7 9 51 76 33 58 2 3 93 146 81 46 85 37 72 19 41 102 198 82 3 5 45 72 35 52 1 1 84 130 83 29 52 (61) (115) (16) (33) 105 200 84 7 9 59 93 (42) (64) (2) (3) 1(19 169 + Indicates less than 1. 466 Biological Resources Table 15-3. Estimates of annual sockeye salmon (Oncorhynchus nerka) runs in millions offish and thousands of metric tons. Numbers in parentheses are approximate. Southeastern Southern Wes IERN Central Alaska/Northern British Columbia/ North Alaska A L.ASKA British Columbia Washington Amerk :a Year No. Wt. No. Wt. No. Wt. No. Wt. No. Wt. 1950 13 33 10 29 3 8 6 18 32 88 51 11 26 8 21 5 15 4 12 28 74 52 21 42 7 18 6 18 4 10 37 88 53 11 32 6 16 7 19 6 17 30 84 54 9 24 6 16 5 14 13 41 32 95 55 9 21 5 14 4 12 3 8 21 55 56 27 54 6 17 5 15 3 8 40 94 57 12 34 4 11 4 9 5 11 24 65 58 7 18 3 8 6 16 19 52 34 94 59 14 33 4 10 3 8 5 13 26 64 1960 38 76 5 12 3 8 4 9 50 105 61 19 54 5 14 5 14 4 12 34 94 62 11 29 6 16 5 13 3 8 25 66 63 7 20 4 12 3 9 3 8 18 49 64 12 28 5 13 6 17 2 5 25 63 65 54 112 6 16 5 11 3 8 68 147 66 19 52 7 19 5 14 5 14 35 99 67 11 29 5 15 7 17 7 19 30 80 68 9 23 6 16 9 27 4 9 27 75 69 20 48 5 14 4 11 6 14 35 87 1970 42 90 6 17 3 8 6 18 57 133 71 17 46 6 17 4 11 8 23 35 97 72 6 16 5 16 4 12 4 11 20 55 73 3 10 5 16 8 22 7 19 23 67 74 12 28 5 16 5 13 9 27 30 84 75 25 58 4 12 3 7 4 11 36 88 76 13 35 8 25 4 11 6 14 30 85 77 11 32 10 35 6 18 7 20 34 105 78 22 58 9 30 4 11 10 29 44 128 79 44 114 7 21 5 14 7 18 63 167 1980 68 164 8 22 3 9 4 10 83 205 81 40 113 10 30 6 17 9 22 64 182 82 27 79 13 40 6 19 14 41 60 179 83 51 126 14 43 (6) (16) (4) (10) 75 195 84 46 117 13 40 (4) (10) (4) (10) 67 177 the runs since 1978 (annual range, 45 to 82%). The cyclical variation in the large runs to Lake Iliamna (Kvichak stocks) caused most of the year-to-year variation in the western Alaskan runs — with very large runs following very large spawning escapements four or five years earlier. However, since 1978, the other stocks in Bristol Bay increased to a greater extent than the Kvichak stocks and the other stocks are not so cyclical. The large runs to southern British Columbia and Washington State were caused by large Fraser River runs that also followed relatively large escape- ments four years earlier. The abundance of North American chum salmon has apparently varied to a lesser extent than abundance of pink and sockeye salmon; however, the abundance estimates for chum salmon are more imprecise. The southeastern Alaska/ northern British Columbia region had 38% (range, 20 to 48%) of the North American chum salmon runs during the period of 1950 to 1977, but only 23% of the runs since 1978 (range, 13 to 27% ). In recent years, most of the chum salmon runs have been to western and central Alaska where abun- dances have increased (Table 15-4). The annual runs of coho and chinook salmon to North America did not vary much between 1950 and 1984; how- ever, in recent years the runs increased in northern areas and decreased slightly in the southern region (Table 15-5). Abundances of coho, chinook, and chum salmon in the southern region were relatively high during the early to mid-1970s when abundances of northern salmon stocks were at a low point. This might indicate either a competitive interaction between southern and northern stocks or an inverse relationship between oceanic conditions favorable for survival — e.g., temperature, food abundance, and preda- tor abundance. To determine plausible interactions among regional stocks of salmon in the Gulf of Alaska, we need to know both the oceanic distributions and the abundances of the stocks. Pacific Salmon 467 Table 15-4. Estimates of annual chum salmon (Oncorhynchtu keta) runs in millions offish and thousands of metric tons. Numbers in parentheses are approximate. SOUTHE, \S1ERN Southern Western Central Alaska/N OKI HERN Bur i ish Columbia/ Norm H Ai I.ASKA Alaska British C OLUMBIA Washington Amerk :a Year No. Wt. No. Wt No. Wt. No. Wt. No. Wt. 1950 3 9 3 1 1 13 59 10 52 29 131 51 3 9 3 12 11 51 7 36 24 108 52 3 10 5 17 10 47 5 29 23 1 03 53 4 11 4 14 12 55 5 29 25 1 09 54 4 13 5 18 12 55 7 40 28 126 55 3 10 2 8 6 26 2 13 11 57 56 4 12 6 20 7 30 3 13 19 75 57 3 10 7 26 10 45 3 14 23 95 58 3 1 1 5 18 8 35 5 25 20 89 59 4 12 4 13 3 15 4 20 15 60 1960 6 17 5 17 4 18 3 13 17 65 61 4 12 3 11 5 24 2 9 14 56 62 4 1 1 6 19 8 38 2 9 19 77 63 3 g 3 11 4 19 2 9 13 48 64 4 12 6 23 7 30 2 11 18 76 65 3 9 2 8 4 17 1 4 10 38 66 3 9 4 12 8 36 2 10 17 67 67 3 10 2 7 6 26 2 9 13 52 68 3 9 4 13 8 39 4 22 18 83 69 3 9 2 7 2 10 3 12 10 38 1970 3 10 4 13 8 32 3 17 19 72 71 3 10 5 16 6 22 2 7 16 55 72 3 10 4 13 9 39 8 39 24 101 73 4 15 4 14 8 38 7 38 23 105 74 5 15 2 6 7 32 3 17 17 70 75 5 14 2 6 3 13 2 10 12 43 76 5 16 3 10 5 26 4 23 17 75 77 7 22 5 20 3 15 2 11 17 68 78 6 19 4 13 3 17 6 30 18 79 79 5 16 4 13 3 15 1 5 13 49 1980 9 27 5 16 6 28 5 26 25 97 81 9 29 9 32 3 15 3 14 23 90 82 5 18 9 34 3 16 6 29 23 97 83 6 20 7 24 (3) (16) (2) (12) 18 72 84 8 25 5 19 (7) (33) (6) (30) 26 107 Salmon Distribution in the Gulf of Alaska Most of the research sampling conducted in the Gulf of Alaska was done during the period of 1961 to 1967. Gillnets and longlines were used to catch salmon in the offshore waters and purse seines were employed in the coastal waters. Sampling was done primarily in the spring and sum- mer, with no sampling taking place in the early winter. Rela- tively little sampling was done in late winter, and the sam- pling that did take place was done entirely by gillnets and longlines. The sampling was insufficient to determine inter- annual variations in either abundance or distribution; how- ever, a general picture of the seasonal distributions and migrations was obtained by combining observations from all years. The regional origins of maturing salmon were largely determined from tags that were returned, aug- mented by studies of scale patterns and parasites. Nearly all of the salmon that originate in the area from central Alaska to southern British Columbia spend their oceanic life within the Gulf of Alaska. However, probably less than half of the coho and chinook salmon originating in the area from Washington to California migrate into the Gulf {i.e., north of 50°N). Stocks from southeastern Alaska and northern British Columbia tend to occupy the eastern and central Gulf and those from central Alaska occupy the central and western Gulf (except chinook salmon, which migrate into the central Pacific). Salmon from southern British Columbia tend to occupy the more southerly region of the Gulf with sockeye stocks distributed farther to the west and pink salmon stocks con- centrated in the eastern region. Chum salmon from western Alaska are centered in the western Gulf but extend from the eastern Gulf to the central Aleutians (180° longitude). West- ern Alaskan pink salmon are distributed from the western Gulf to the central Aleutians, whereas western Alaskan chinook salmon are found largely in the central Pacific and in the Bering Sea. 468 Biological Resources Table 15-5. Estimates of annual coho (Oncorhynchus kisutch) and Chinook (0. tshawytscha) salmon runs in millions offish and thousands of metric tons. Numbers in parentheses are approximate. Coho Chinook Southeastern Southeastern Western Central Alaska 1 Western Central Ai .aska/ Alaska A laska California Alaska Alaska California Year No. Wt. No. Wt. No. Wt. No. Wt. No. Wt. No. Wt. 1950 0.3 1.7 6 10.5 41 0.5 5 0.4 5 5.0 34 51 0.3 1.6 6 15.5 58 0.5 5 0.4 5 5.1 35 52 0.3 1.2 4 12.2 48 0.5 5 0.2 3 5.3 40 53 0.2 0.9 3 10.0 38 0.5 5 0.2 3 5.2 38 54 0.3 1.8 6 9.3 36 0.5 5 0.2 2 5.2 38 55 0.2 1.2 4 10.0 37 0.6 6 0.2 2 5.8 39 56 0.2 1.3 5 10.3 38 0.5 5 0.2 2 5.9 36 57 0.4 0.8 3 10.8 36 0.6 6 0.1 2 5.0 31 58 0.9 3 1.2 4 9.0 34 0.6 6 0.1 4.6 28 59 0.4 0.8 3 8.9 28 0.6 6 0.1 4.2 28 1960 0.3 1.4 5 5.6 19 0.6 6 0.1 3.7 24 61 0.2 1.0 3 9.4 33 0.6 6 0.1 3.9 24 62 0.4 1.6 6 10.5 37 0.5 4 0.1 3.7 24 63 0.4 1.4 5 10.3 35 0.5 5 0.1 4.3 27 64 0.4 1.9 7 12.3 44 0.7 5 + 4.5 29 65 0.2 0.9 3 13.7 51 0.5 5 0.1 4.3 29 66 0.2 1.3 5 15.3 53 0.6 5 + 4.5 28 67 0.4 1.0 4 11.7 42 0.6 6 0.1 4.2 28 68 0.8 2 2.0 7 14.6 44 0.6 6 + + 4.4 28 69 0.5 1 0.6 2 8.2 27 0.6 6 0.1 4.6 27 1970 0.2 + 1.3 5 12.9 49 0.6 6 0.1 4.9 30 71 0.1 + 1.0 4 15.8 49 0.6 6 0.1 5.2 32 72 0.2 0.5 2 11.5 38 0.5 5 0.1 5.2 31 73 0.4 0.7 3 11.7 39 0.5 5 0.1 5.9 35 74 0.4 0.6 2 14.5 45 0.5 4 0.1 5.3 30 75 0.4 0.8 3 10.5 36 0.3 3 0.1 5.6 33 76 0.3 0.9 3 15.5 41 0.5 5 0.1 5.6 32 77 0.9 3 0.9 4 10.5 33 0.6 6 0.1 5.8 33 78 0.8 2 1.4 5 10.5 30 0.8 9 0.2 2 5.4 33 79 1.5 5 2.3 8 11.5 35 0.9 8 0.2 2 5.3 31 1980 1.5 5 2.2 7 10.7 32 0.9 9 0.1 1 4.9 29 81 1.4 4 2.4 9 8.5 25 1.2 11 0.2 2 4.6 27 82 2.9 9 3.8 14 10.0 30 1.0 9 0.2 2 4.9 33 83 0.9 3 2.3 8 (8) (21) 1.0 9 0.3 3 (4) (24) 84 3.1 10 2.9 10 (9) (28) 0.8 7 0.2 2 (5) (27) + Indicates less than 100,000 fish or 1,000 mt Bristol Bay sockeye often make up the most abundant regional stock at sea because, in addition to the annual run of mature fish, there are two age groups of immature fish in offshore waters. Only one age group of pink salmon is pre- sent in offshore waters at any given time. Maturing Bristol Bay sockeye salmon extend from the eastern Gulf of Alaska to the western Aleutians and Bering Sea (Fig. 15-1). To esti- mate the average proportion of Bristol Bay maturing sockeye in the Gulf (i.e., east of 165°W), the average regional composition of the tag returns was calculated for each 2° x 5° area from data given in Figures 53 to 59 of French et al. (1976). During the period from 1961 to 1967, the average annual catch of sockeye salmon in Bristol Bay (9.3 x 106 fish) was equal to the average sockeye catch in the remainder of North America, so the chance of recovering tags should have been about equal. The unweighted mean of the per- centages of Bristol Bay tags from Gulf of Alaska tagging was 26%, and since the average annual run to North America excluding Bristol Bay was 14.6 x 106, the average number of Bristol Bay sockeye in the Gulf for the period of 1961 to 1967 was ~5.0 x 106 fish. This was 26% of the average Bristol Bay inshore run of 1.9 x 107 and 23% of the combined western Alaska sockeye run during those years (Table 15-6). How- ever, the vast majority of the Bristol Bay sockeye in the Gulf were in the western half where they were mixed mainly with central Alaskan stocks, western Alaskan chum salmon, and some unknown proportion of the abundant Asian chum salmon stocks. I hypothesized that Bristol Bay stocks that migrate to sea late would more likely be in the Gulf of Alaska than those that migrate to sea early. I based the hypothesis on the the- Pacific Salmon 469 120 Winter-spring migration June-July migrations Gulf of Alaska study area 42 180 170 160 150 Figure 15-1. Principal migratory routes to Bristol Bay followed by maturing salmon. 42 140 38 ory that salmon return as adults from about the same area where they resided at the end of their first winter at sea. Konovalov (1971) suggested that individual salmon popula- tions have rather precise wintering and feeding grounds at sea; however, the complex of populations from a large river or lake system may occupy a broad area. Bristol Bay sockeye salmon smolts from the various lake systems migrate to sea each year in about the same order. They migrate seaward in a rather narrow band along the north side of the Alaska Peninsula (Straty 1974). Their migration beyond Unimak Island is undocumented (Fig. 15-2). Although the stocks throughout Bristol Bay contain both early (mid-May to early June) and late (mid-June to late July) migrations, the stocks from the Kvichak River to the Alaska Peninsula generally have earlier migrations and larger and older smolts than stocks from the northwest side of Bristol Bay (Nushagak and Togiak districts). The majority of chum and pink salmon in Bristol Bay are also produced from both the Nushagak and the Togiak systems, and they tend to reside in the western Gulf. I compared the tag returns to the Kvichak and to north Peninsula fisheries with the returns to the Nushagak/Togiak fisheries. The returns came from maturing sockeye that had been tagged from April to early July in both the Gulf of Alaska and the central Pacific (data on file at the Fisheries Research Institute, University of Washington, Seattle, WA). The expected tag returns were calculated from the commer- cial catches. For sockeye tagged in the Gulf, there were sig- nificantly more tags recovered in the Nushagak/Togiak districts than expected from the number offish taken in the commercial catches (Table 15-7). An exceptional number of tags (relative to the catches) were recovered in the intercep- tion fisheries of the south Peninsula (Unimak/Shumagin Islands). This fishery is particularly effective because sock- eye returning from the Gulf are concentrated as they migrate along the Peninsula and around Unimak Island before heading into Bristol Bay. Sockeye salmon tagged in the central Pacific tended to return to a lesser extent to the Nushagak/Togiak districts than to the other Bristol Bay systems. The one exception to this pattern occurred in 1962. Most of the sockeye returning to the Nushagak that year had migrated to sea in 1960 and the migration from the Wood River lakes (the major sockeye producer in the district) had an unusually early peak (first week ofjune) and then a more typical late peak in mid-July. Interannual variation in the timing of smolt migrations from Bristol Bay probably affects the subsequent distribu- tion of the stocks at sea, and thus affects both their abun- dance in the Gulf and their availability to interception fisheries such as those of the south Peninsula and the high seas. A comparison was also made between the age composi- tions from catch estimates of maturing Bristol Bay sockeye in the high-seas fishery (mostly between 175°W and 175°E) given by Fredin and Worlund (1974) and the age composi- tions in the Bristol Bay runs. The sockeye caught in the high-seas fishery were consistently older in both freshwater and ocean age than the sockeye caught in the Bristol Bay runs. The difference in ocean-age compositions was proba- bly affected by the selectivity of the gillnets, but the fresh- water age was probably unaffected. In addition, the fresh- water ages of those immature Bristol Bay sockeye that were sampled by the Fisheries Research Institute south of Adak Island were usually older than the ages found in subsequent Bristol Bay returns of mature sockeye. Each year the age composition of immature fish usually shifted from older ages — in latejune to earlyjuly — to younger ages in late July as the immature salmon moved from east to west on their feeding migration. 470 Biological Resources Table 15-6. Estimated annual catches of maturing sockeye salmon (Oncorhynchus nerka) of western Alaska origin by both the Japanese high-seas and the Unimak-Shumagin Islands fisheries, and estimated inshore western Alaska sockeye salmon runs for the period 1950 to 1984. Catch and run numbers are expressed in millions offish. Japanese Fishery Unimak- Shumagin Western Alaska Western Total Western At.ASKAa Alaska Catch Immatures Matures Fishery Inshore Run Combined RuNb 1950 0 0 0 1.6 11.2 12.8 51 0 0 0 0.2 10.7 10.9 52 0.7 0 0 0.8 19.9 20.7 53 1.6 0 0 0.9 10.3 11.2 54 3.8 0 0 0.6 8.1 8.7 55 12.5 0 0 0.5 8.6 9.1 56 10.3 0.9 2.4 0.6 26.2 29.2 57 20.1 + 6.4 0.3 11.6 19.2 58 12.9 + 0.4 0.2 6.6 7.2 59 9.9 0.1 0.6 0.2 13.9 14.7 1960 14.5 0.3 3.6 0.2 37.6 41.5 61 14.2 0.1 5.8 0.4 18.8 25.3 62 10.8 0.1 0.8 0.4 10.8 12.1 63 8.9 0.1 0.9 0.2 7.3 8.5 64 7.2 0.8 0.3 0.3 11.3 12.0 65 12.2 0.4 6.1 0.8 53.5 61.2 66 8.0 0.1 1.5 0.6 18.0 20.5 67 10.7 + 0.9 0.3 10.7 12.0 68 9.2 0.8 0.9 0.6 8.4 9.9 69 8.4 0.5 1.2 0.9 19.6 22.5 1970 10.0 1.2 3.5 1.8 39.8 45.6 71 6.6 0.6 0.8 0.7 16.4 19.1 72 6.9 0.2 0.7 0.5 5.7 7.5 73 5.9 0.3 0.6 0.3 2.7 3.8 74 5.4 0.7 0.3 0.1 11.4 12.1 75 5.2 0.2 0.6 0.2 24.6 26.1 76 5.8 0.2 0.8 0.4 12.6 14.0 77 2.8 0.3 0.5 0.3 10.4 11.4 78 3.2 0.2 0.1 0.5 21.4 22.3 79 3.0 0.4 0.1 0.9 43.1 44.3 1980 3.2 0.7 0.2 3.3 64.8 68.7 81 3.1 0.3 0.1 2.0 37.5 40.3 82 2.5 0.2 0.1 2.0 24.6 27.0 83 2.5 0.2 0.1 2.2 49.2 51.7 84 1.9 0.2 0.1 2.1 43.9 46.3 aFredin and Worlund (1974) and M. L. Dahlburg (NMFS, pers. comm.) estimated the western Alaska catches by the high seas fleet. bCombined run includes Unimak-Shumagin catch, Japanese catch of mature sockeye, and the catch of immature sockeye in the preceding year. + Indicates less than 100,000 fish. The Kvichak system usually has the most abundant smolt migration and adult run. Since 1971, the Alaska Department of Fish and Game has made daily estimates of the number of smolts that migrate from Lake Iliamna, although the esti- mates obtained in 1975 were poor. I calculated the daily adult runs in the fishery by lagging daily escapements back to the catch and comparing the annual timing of the smolt and adult migrations (Fig. 15-3). The timing of the smolt migrations was related to the average April/May air tem- perature in Bristol Bay, whereas the timing of the adult run related to the average April/May temperature in Womens Bay (Kodiak). The timings of the smolt and adult migrations were usu- ally correlated, as were the spring air temperatures; how- ever, in 1977 when temperatures were cool in Bristol Bay but warm in the Gulf, the smolt migration was somewhat late and the adult run was very early. Thus, the interannual varia- tion in both the composition of the stocks migrating from Bristol Bay and in the spring temperature probably affects the abundance of Bristol Bay salmon that can be found in the Gulf of Alaska. A high proportion of late-migrating stocks coupled with a cold spring would probably mean that a high proportion of western Alaskan salmon could be found in the Gulf. On the other hand, a high proportion of early migrating stocks coupled with a warm spring would probably lead to a small proportion of western Alaskan salmon in the Gulf. In addition, cold winters may displace salmon farther to the south, whereas in warm winters they may be more dispersed farther north (Rogers 1984). El Nino events (the unusual extension of southern warm water into Pacific Salmon 471 160 170 62 62 140 130 58 120 160 50 46 42 lirrt rig .SVfl '/, ' /-:■ . -*— X' / > S\ Vnima V v xvvv Spring-summer migrations Fall-to-winter migrations Gulf of Alaska study area 130 42 180 170 150 42 38 Figure 15-2. Principal spring/summer migratory routes followed by Bristol Bay and Gulf of Alaska salmon stocks (large gray arrows). Hypothetical fall-to-winter migrations of Bristol Bay salmon are shown by small black arrows. Table 15-7. Tag returns (both observed and expected) from maturing sockeye salmon tagged in the Gulf of Alaska and central Pacific, 1957 through 1967. Catch (xlO6) Tagged in Gulf of Alaska (E of 165° W) and Returned from: Tagged in Central Pacific3 and Returned from: Kvichak- South North Nushagak- South Kvichak — North Peninsula Peninsula Togiak Peninsula Peninsula Nushagak — Togiak Kvichak — North Peninsula Nushagak — Togiak Year Observed Observed Expected Observed Expected %d» Observed Expected Observed Expected 1957 0.34 6.08 0.53 0 4 0 36 33 0 3 58 0.19 2.33 1.13 — — — 35 29 8 14 59 0.22 3.41 1.83 0 1 0 18 16 0 2 60 0.38 12.74 1.66 — — — 551 508 23 66 61 0.46 11.60 0.70 6 207 210 16 13 + 23 525 513 19 31 62 0.41 3.43 1.55 22 27 50 45 22 + 105 25 36 27 16 63 0.20 2.06 1 .03 5 11 13 8 6 + 33 13 13 7 7 64 0.37 4.16 1.67 5 18 24 15 9 + 67 8 7 2 3 65 0.88 23.45 1.01 5 114 123 14 5 + 180 143 141 4 6 66 0.61 8.19 1.37 13 129 146 31 24 + 29 15 15 2 2 67 0.30 3.79 0.76 7 11 14 6 3 + 100 17 15 1 3 JOne tag was recovered in the south peninsula fishery in 1961. Most of the fish were tagged between 165°W and 180°W. ''[(Obs. - Exp.) * Exp] x 100. (Percentage difference between observed and expected). 472 Biological Resources 50-, 40 30- 20 10 o 50-i 40 - 30 20 10- 0 50 40 30 20- 10- 0 50 40 30 20 10 0 50 40- 30 20 10 0 50 40 - 30- 20 92 Smolts Adults 1971 -1.6< -I.7C 68 194 43 16? 103 1972 -1.7C -1.6C 1973 0.4C - 0.8C 1974 I.OC -0.4C 1975 - I.OC 1976 -0.7C -0.4C 20 25 May I 30 10 15 20 June r 30 0.3 15 5 10 July 215 Smolts Adults 1977 -0.4< I.7C 270 53 173 184 204 1978 I.1C 0.9C 1979 I.6C 1.9C 1980 0.7C: I.6C 1981 1.6C l.H( 1982 -1.3C -0.8C AW 10 15 20 June 25 35 Figure 15-3. Timing of the smolt and adult migrations for Kvichak sockeye salmon (Oncorhynchus nerka) during the period 1971 to 1982 in terms of the daily percentage of the annual migration. The number of smolts (millions) is given in the upper left corners and the number of adults (millions) is given in the upper right corners. The deviations from the mean April/May air temperature in Bristol Bay are shown at left center and the deviations from the mean April/May sea surface temperature at Kodiak are shown at right center. Pacific Salmon 473 the Gulf) may also cause salmon to locate farther north in the Gulf. Such events occurred in 1958, 1972, and 1983 (McLain 1984). In 1972, the Kvichak run was earlier than expected based on the sea surface temperature (SST) at Kodiak (Fig. 15-3), so perhaps warmer water from the south moved the fish far- ther north and thus closer to Bristol Bay. Their migration may even have begun earlier. In warm years, the Fraser River sockeye tend to return around the north end of Van- couver Island (Johnston Strait) rather than taking their usual route through the Strait of Juan de Fuca (McLain 1984). If Fraser River sockeye were concentrated in the upper Gulf, they might be expected to return via Johnston Strait, whereas if they were concentrated in the southern Gulf (as appeared to be the case during the 1961 to 1967 returns), they would probably return via the Strait ofjuan de Fuca. Temperature also affects the growth of sockeye salmon while they are at sea. The growth of Bristol Bay sockeye dur- ing their last year at sea (and probably during their last spring) was strongly density-dependent until 1978 (Rogers 1984). After that, they were larger than expected, given the abundance of the runs. I used stepwise multiple regressions to compare the annual variation in the mean lengths for the four main age groups of sockeye salmon in Bristol Bay with 1) the SST in April-May at Kodiak, 2) the western Alaskan run size, and 3) the year (Table 15-8). Ages 1.2 and 1.3 were consistently abundant in the Nushagak runs, whereas ages 2.2 and 2.3 were usually scarce (although they were abun- dant in the other Bristol Bay systems). The variation in the mean lengths of age 1.2 sockeye was most affected by varia- tion in spring temperature, while the length variation of older sockeye was most affected by the abundance of the run. Very little of the variation in the lengths of age 2.3 fish was explained by the temperature in the Gulf. For the age 2.2 and 2.3 sockeye, lengths were longer in recent years than might be expected, given both the temperatures and abun- dances of the runs. It was particularly interesting that the Table 15-8. Multiple linear regressions of annual mean lengths of Bristol Bay sockeye salmon based on sea surface temperature, western Alaska run size, and year (1959-1983). Percent Variation Regressions-' Explained by R2 Lb 1.2 = 0.594 (T> - 0.486 (R)'1 L1.3 = 0.658 (T) - 0.757 (R) L 2.2 = 0.453 (T) - 0.728 (R) + 0.530 (Y) L 2.3 = 0.274 (T) - 0.826 (R) + 0.386 (Y) 31 53 61 67 •'All variables are standardized, v = ■ number of standard deviations from the SU mean for the 25 years, and all coefficients are significant at P < 0.05 except 0.274 in the L 23 regression. bL 1.2 = mean length (mideve-tailfork) of Nushagak sockeye, age 1.2; mean = 507 mm. SD = 8.1.: L 1.3 = same for Nushagak age 1.8; mean = 571 mm. SD = 7.8: L 2.2 = mean length of Bristol Bay sockeye. age 2.2; mean = 521 mm. SD = 9.9: L 2.3 = same for Bristol Bav age 2.3; mean = 579 mm. SD = 7.2. CT = April-May SST at Womens Bav. Kodiak (C); mean = 5.5. SD = 1.3. C,R = Western Alaskan sockeye run in millions; mean = 23.8. SD = 17.3. eY " vear; mean = 71, SD = 7.4. younger freshwater ages (1.2 and 1.3) were more affected by temperatures in the Gulf than were the older freshwater ages, since this seems to agree with the hypothesis that younger .smolts are more likely to begin their ocean life in the western Gulf than are the older smolts. Returns From The Gulf The abundance, distribution, and size of salmon in the Gulf of Alaska are both seasonally and interannually dynamic. Salmon move from north to south in the fall and from south to north in the spring. The stock compositions vary as both species' abundances and regional stocks change, and fish growth varies as density, temperature, food abundance, and inherent growth rates all vary. Although we lack measurements for these phenomena, we can be reason- ably sure that they are occurring. The maximum biomass of salmon in the Gulf of Alaska probably occurs in late May to early June just before the mature fish begin returning to their freshwater spawning streams. If the mortalities from either predation or fisheries (fish that are killed but not caught) equal the growth that occurs between June and October when most fish have returned, then the biomass of runs from the Gulf is nearly equal to the seasonal peak bio- mass of maturing salmon in the Gulf. I believe this assump- tion is not unreasonable, although most biologists probably believe that growth exceeds mortality. Runs from the Gulf of Alaska were estimated by assuming that 1) 26% of the sockeye, coho, and chinook salmon returning to western Alaska were from the Gulf, 2) 75% of chum and pink salmon returning to western Alaska were from the Gulf, and 3) 50% of the southern runs of coho and chinook salmon were also from the Gulf. Annual salmon run estimates for runs from the Gulf and to all of North America are shown in Figure 15-4. The Gulf had an annual peak biomass between 2 * 105 and 3 x 105 mt of maturing salmon from 1950 to 1977, and ~4 x 105 mt from 1981 to 1984. 1 did not attempt to estimate the biomass of immature sockeye, chum salmon, or maturing Asian chum salmon, i V A / \ North America \ \ r \ ' Gulf of Alaska Figure 15-4. Annual salmon runs from the Gulf of Alaska and to North America for the period 1950 to 1984. 474 Biological Rfsources although this can probably be done (Peterman and Wong 1984). The recent salmon returns (1981-1984) valued in terms of prices paid to fishermen would be worth nearly $500 million/y, based on catch plus escapement. This makes the Gulf of Alaska a valuable resource for North America. The approximate number of juveniles entering the Gulf of Alaska from the coastal estuaries was estimated based on the number of adult returns and an assumed 10% survival rate. This appeared to be average for 10-cm smolts ( — 8.5 g) — the size of most salmon when they leave the inshore waters. For the smolt migrations from 1956 to 1976, the annual estimates ranged from 6.30 x 108 to 1.35 x 109 fish, or 5.4 x 103 to 1.15 x 104 metric tons. The adult returns from those migrations averaged 2.53 x 105 mt — nearly 30 times the average biomass of juveniles that entered the offshore waters of the Gulf during the period of 1956 to 1976. The adult returns from the 1977 to 1981 seaward smolt migrations were 66% higher than the returns from the period 1956 to 1976 migrations. However, most of this increase was probably caused by an increase in marine survival rather than an increase in the number of seaward migrants (Rogers 1984). The Future Although in recent years the salmon runs to western and central Alaska were probably as large as they have been since commercial fishing began, the recent abundance of North American salmon was still below the historical peak abundance — mainly because southeastern Alaska and Brit- ish Columbia stocks were still at a relatively low level. How- ever, based on preliminary catch statistics, the 1985 run may be comparable to the historical peak for this region. It seems likely that North American salmon stocks could produce annual sustained catches of ~ 3.5 x 105 mt if it were not for some rather disturbing trends in southern stocks. These trends include a decline in the average size of British Colum- bia salmon (and probably a decline in their reproductive potential) (Ricker 1982), and a decline in the marine survival rate for some Oregon hatchery stocks (Mathews 1984). Fishery practices (e.g., selectivity, overexploitation of nat- ural stocks) as well as hatchery practices (e.g., elimination of natural reproduction and the altering of both behavior and natural selection) will probably continue to affect salmon abundance in the southern Gulf of Alaska. However, as long as the freshwater spawning and rearing grounds in British Columbia and Alaska remain as they are, we can look for- ward to continued bountiful salmon returns from the Gulf of Alaska. We have yet to determine the causes of natural salmon mortality in offshore waters. It is generally assumed that marine mortality rates are greatest for seaward migrants in coastal estuaries, then decline as the salmon grow to matu- rity. However, little is known about either the natural mor- tality for immature salmon at sea or about mortality for maturing salmon on their homeward migration. The ability to predict interannual variation in marine mortality would greatly improve our ability to forecast annual salmon runs. Acknowledgments Drs. E.S. Salo and S.B. Mathews provided valuable insight regarding both the biology and the interpretations of statis- tics on salmon stocks from the southern regions of the Gulf. Mr. C.K. Harris provided valuable assistance in interpreting salmon statistics for the high seas. Funding support for the preparation of this chapter was furnished both by the Minerals Management Service, Department of the Interior, through an interagency agree- ment with the National Oceanic and Atmospheric Admin- istration, Department of Commerce, as part of the Outer Continental Shelf Environmental Assessment Program and by the Pacific Seafood Processors Association. References Alaska Department of Fish and Game (ADF&rG) 1984a Alaska 1982 catch and production. Statistics Leaflet 35. 65 pp. Alaska Department of Fish and Game (ADF&G) 1984b Preliminary forecasts and projections for 1984 Alaska salmon fisheries. Information Leaflet 229. 45 pp. Beacham, T.D. 1984 The status of the chum salmon fishery and stocks of British Columbia. Document submit- ted to Scientific Sub-Committee on Salmon, Annual Meeting of The International North Pacific Fisheries Commission, Vancouver, Can- ada, October 1984. 28 pp. Bill, D. 1984 1982 Kvichak River sockeye salmon smolt stud- ies. In: 1982 Bristol Bay Sockeye Salmon Smolt Stud- ies. D.M. Eggers and H.J. Yuen, editors. Alaska Department of Fish and Game Technical Data Report No. 103. pp. 1-12. Cross, B.A., D.R. Bernard, and S.L. Marshall 1983 Return-per-spawner ratios for sockeye salmon in upper Cook Inlet, Alaska. Alaska Department of Fish and Game Information Leaflet 221. 82 pp. Donnelly, R.F. 1983 Factors affecting the abundance of Kodiak Archipelago pink salmon (Oncorhynchus gor- buscha, Walbaum). Ph.D. Dissertation, Univer- sity of Washington, Seattle, WA. 157 pp. Fredin, R.A. 1980 Trends in North Pacific salmon fisheries. In: Salmonid Ecosystems of the North Pacific. W.J. McNeil and D.C. Himsworth, editors. Oregon State University Press, Corvallis, OR. pp. 59-114. Pacific Salmon 475 Fredin, R.A. and D.D. Worlund 1974 Catches of sockeye salmon of Bristol Bay origin by the Japanese mothership salmon fishery, 1956-70. International North Pacific Fisheries Commission Bulletin No. 30. pp. 1-80. French, R., H. Bilton, M. Osako, and A. Hartt 1976 Distribution and origin of sockeye salmon (Oncorhynchus nerka) in offshore waters of the North Pacific Ocean. International North Pacific Fisheries Commission Bulletin No. 34. 113 pp. Godfrey, H., K.A. Henry, and S. Machidori 1975 Distribution and abundance of coho salmon in offshore waters of the North Pacific Ocean. International North Pacific Fisheries Commis- sion Bulletin No. 31. 80 pp. Groot, C. 1982 Modifications on a theme — a perspective on migratory behavior of Pacific salmon. In: Pro- ceedings of the First International Symposium on Salmon and Trout Migratory Behavior. E.L. Bran- non and E.O. Salo, editors. University of Wash- ington, Seattle, WA. pp. 1-21. Hartt, A.C. 1980 Juvenile salmonids in the oceanic ecosystem — the critical first summer. In: Salmonid Ecosystems of the North Pacific. W.J. McNeil and D.C. Himsworth, editors. Oregon State University Press, Corvallis, OR. pp. 25-57. Henderson, M.H., A.T. Charles, and P.J. Starr 1984 A review of British Columbia sockeye salmon (Oncorhynchus nerka) stocks and their coastal fisheries: 1970 to 1984. Document submitted to Scientific Sub-Committee on Salmon, Annual Meeting of the International North Pacific Fisheries Commission, Vancouver, Canada, October, 1984. 21 pp. International North Pacific Fisheries Commission (INPFC) 1974 Additional information on the exploitation, scientific investigation, and management of salmon stocks on the Pacific coasts of Canada and the United States in relation to the absten- tion provisions of the North Pacific Fisheries Convention. International North Pacific Fish- eries Commission Bulletin No. 29. 178 pp. International North Pacific Fisheries Commission (Secretariat) (INPFC) 1979 Historical catch statistics for salmon of the North Pacific Ocean. International North Pacific Fisheries Commission Bulletin No. 39. 166 pp. Konovalov, S.M. 1971 Differentiation of local populations of sockeye salmon. Translation, 1975, L.V. Sagen, College of Fisheries, University of Washington. Univer- sity of Washington Publications in Fisheries — New Series 6:1-289. Major, R.L., J. Ito, S. Ito, and H. Godfrey 1978 Distribution and origin of Chinook salmon (Oncorhynchus tshawytscha) in offshore waters of the North Pacific Ocean. International North Pacific Fisheries Commission Bulletin No. 38. 54 pp. Mathews, S.B. 1984 Variability of marine survival of Pacific salm- onids: a review. In: The Influence of Ocean Condi- tions on the Production of Salmonids in the North Pacific. W.G. Pearcy, editor. Oregon State Uni- versity Sea Grant No. ORESU-W-83-001. Oregon State University Press, Corvallis, OR. pp. 161-182. McBride, D.N. andJ.A. Wilcock 1983 Alaska chinook salmon (Oncorhynchus tshawytscha, Walbaum) catch and escapement, 1961- 1980, with age, size, and sex composition estimates. Alaska Department of Fish and Game Information Leaflet 212. 181 pp. McCurdy, M.L. 1984 Prince William Sound general district pink (Oncorhynchus gorbuscha) and chum (O. keta) salmon aerial and ground escapement surveys and pre-emergent alevin index surveys, brood years 1980 through 1983. Alaska Department of Fish and Game Technical Data Report No. 116. 116 pp. McDonald, J. andJ.M. Hume 1984 Babine Lake sockeye salmon (Oncorhynchus nerka) enhancement program: testing some major assumptions. Canadian Journal of Fisheries and Aquatic Sciences 41:70-92. McLain, D.R. 1984 Coastal ocean warming in the northeastern Pacific, 1976-83. In: The Influence of Ocean Condi- tions on the Production of Salmonids in the North Pacific. W.G. Pearcy, editor. Oregon State Uni- versity Sea Grant No. ORESU-W-83-001, Oregon State University Press, Corvallis, OR. pp. 61-99. Neave, F., T. Yonemori, and R.G. Bakkala 1976 Distribution and origin of chum salmon in off- shore waters of the North Pacific Ocean. Inter- national North Pacific Fisheries Commission Bulletin No. 35. 79 pp. 476 Biological Resources Peterman, R.M. 1980 Testing for density-dependent marine survival in Pacific salmonids. In: Salmonid Ecosystems of the North Pacific, W.J. McNeil and D.C. Himsworth, editors. Oregon State University Press, Corvallis, OR. pp. 1-24. Peterman, R.M. and F.Y.C. Wong 1984 Cross correlations between reconstructed ocean abundances of Bristol Bay and British Columbia sockeye salmon (Oncorhynchus tierka). Canadian Journal of Fisheries and Aquatic Sciences 41:1814-1824. Ricker, W.E. 1972 Hereditary and environmental factors affect- ing certain salmonid populations. In: The Stock Concept in Pacific Salmon. R.C. Simon and P.A. Larkin, editors. University of British Columbia Press, Vancouver, B.C. pp. 27-160. Ricker, W.E. 1982 Size and age of British Columbia sockeye salmon (Oncorhynchus nerka) in relation to environmental factors and the fishery. Cana- dian Technical Report, Fisheries and Aquatic Sciences No. 1115. 117 pp. Rogers, D.E. 1984 Trends in abundance of northeastern Pacific stocks of salmon. In: The Influence of Ocean Condi- tions on the Production of Salmonids in the North Pacific. W.G. Pearcy, editor. Oregon State Uni- versity Sea Grant No. ORESU-W-83-001, Oregon State University Press, Corvallis, OR. pp. 100-127. Rogers, D.E., K.W. Myers, C.K. Harris, CM. Knudsen, R.V. Walker, and N.D. Davis 1984 Origins of chinook salmon in the area of the Japanese mothership salmon fishery. Final report to Alaska Department of Fish and Game. School of Fisheries, University of Wash- ington, Fisheries Research Institute, FRI-UW-8408, Seattle, WA. 215 pp. Roos,J.F. 1984 Predictions of the 1985 sockeye and pink salmon runs to the Fraser River. International Pacific Salmon Fisheries Commission man- uscript presented at Bellingham, WA, 7 December 1984. 9 pp. Royce, W.F., L.S. Smith, and A.C. Hartt 1968 Models of oceanic migrations of Pacific salmon and comments on guidance mechanisms. Fish- ery Bulletin (U.S.) 66:441-462. Starr, P.J. and K.R. Petrie 1984 A review of British Columbia chinook salmon stocks and their coastal fisheries: 1970 to 1984. Document submitted to Scientific Sub-Com- mittee on Salmon, Annual Meeting of the International North Pacific Fisheries Commis- sion, Vancouver, Canada, October 1984. 21 pp. Straty, R.R. 1974 Ecology and behavior of juvenile sockeye salmon (Oncorhynchus nerka) in Bristol Bay and the eastern Bering Sea. In: Oceanography of the Bering Sea. D.W. Hood and E.J. Kelley, editors. International Symposium, Bering Sea Study, Japan, 3January-4 February 1972. pp. 285-320. Takagi, K., K.V. Aro, A.C. Hartt, and M.B. Dell 1981 Distribution and origin of pink salmon (O. gor- buscha) in offshore waters of the North Pacific Ocean. International North Pacific Fisheries Commission Bulletin No. 40. 195 pp. Yuen, H.J. 1984 Bristol Bay salmon (Oncorhynchus sp.) — 1981: a compilation of catch, escapement, and biolog- ical data. Alaksa Department of Fish and Game Technical Data Report No. 129. 116 pp. Marine Birds 16 Anthony R. DeGange Gerald A. Sanger U.S. Fish and Wildlife Service Alaska Fish and Wildlife Research Center Anchorage, Alaska Abstract In this chapter we review existing knowledge of marine birds in the Gulf of Alaska. Three estuarine systems in the Gulf provide critical habitat for migratory shorebirds and waterfowl: 1) the Stikine River Delta, 2) Cook Inlet, and 3) the Copper River Delta. Over 20 million waterbirds are estimated to use the latter system during spring migra- tion. Western sandpipers, dunlin, and northern pintails numerically dominate this migration. Breeding populations of shorebirds and waterfowl in the Gulf are small compared with those elsewhere in Alaska. Of those Gulf regions suitable for nesting waterfowl and shorebirds, the Copper River Delta is the most important. Species diversity and the number of shorebirds wintering in the Gulf are low; however, water- fowl wintering in the Gulf number at least in the low millions. These birds concen- trated in sheltered, near-shore regions where their epibenthic and infaunal prey are accessible. Over nine million seabirds (twenty-six species) nest in the Gulf of Alaska at more than 800 sites. Seabird productivity varies markedly. Food availability seems to have a large influence on reproductive success, especially for surface-feeding species such as the black-legged kittiwake. Seabird densities are highest over shelf and shelf-break habitats during spring migration and in summer. Sooty and short-tailed shearwaters dominate the pelagic avifauna both numerically and in terms of biomass. Seabird densities are generally lower in winter than in summer as a result of both a southward migration of some species and offshore dispersal of others. A variety of prey species are used by seabirds in the Gulf; of these, capelin, sand lance, and euphausiids are of greatest importance. Trophically, seabirds in the Gulf range from near primary con- sumers to third-order carnivores, ingesting an estimated 1,120,000 mt during the 120-day summer period. Introduction Over 147 species of birds use marine or estuarine habitats in the Gulf of Alaska, and overall populations, although not precisely known, number in the millions. Marine bird resources in the Gulf of Alaska are unquestionably some of the largest in the Northern Hemisphere. Our intent in this chapter is to summarize much of the published and unpublished literature on distribution, abundance, migra- tion, breeding biology, and feeding ecology of the water- fowl, shorebirds, and seabirds that spend all or a portion of their lives in coastal or offshore habitats in the Gulf. We con- centrate on features that are particularly relevant to each species group. For waterfowl and shorebirds — many of which breed outside the Gulf of Alaska — migration and win- tering are emphasized. For seabirds, many of which spend their entire lives in Alaskan waters, our coverage is more detailed. Any attempt to understand patterns of bird distribution, variations in migration patterns, nesting phenology, or breeding success depends on an understanding of topogra- phy and climate, prey abundance and variability, and fac- tors that affect prey populations. Where possible, uc attempt to identify the critical biotic and abiotic factors that affect the lives of marine birds in the Gulf. However, a com- prehensive synthesis that relates marine birds to their environment awaits more detailed interdisciplinary studies. 479 480 Biohx.icm Resources Review Area Boundaries The Gulf of Alaska, as defined in this volume, includes all marine and coastal waters north of 52°N. Although marine birds are usually confined to geographic regions that have both the appropriate oceanographic conditions and food resources, they may wander widely over that region's marine waters. Indeed, some species found in the Gulf of Alaska are trans-equatorial migrants. The southern bound- arv of the Gulf of Alaska (i.e., 52°N) is artificial in ornithological terms. Nevertheless, we adhere to 52°N as a southern boundary for estimating at-sea populations of marine birds, ignoring portions of those populations that pass south of that line. For the rest of the chapter, we limit coverage to Alaskan waters between the southern tip of southeastern Alaska and Unimak Pass (Fig. 16-1), where the majority of recent work funded through the Outer Conti- nental Shelf Environmental Assessment Program (OCSEAP) has occurred. Sources of Information The biology of marine birds in the Gulf of Alaska was lit- tle understood prior to studies initiated in the mid-to-late 1970s. Prior to this time, information on marine birds in the Gulf was limited either to accounts of distribution and abun- dance or to general information on life histories and feed- ing (Bent 1919; Gabrielson and Lincoln 1959; Sanger 1972; and Shuntov 1972). Six primary sources provided informa- tion on distribution, abundance, and migration of marine birds: 1) Gabrielson and Lincoln (1959) 2) Isleib and Kessel (1973) 3) Kessel and Gibson (1978) 4) Sowls, Hatch, and Lensink (1978) 5) Gould, Forsell, and Lensink (1982) 6) the frequently updated seabird-colony database of the U.S. Fish and Wildlife Service . Information on specific sites and species was gleaned from numerous sources. Data on shorebird and waterfowl migration are primarily from: • Isleib and Kessel (1973) • Senner(1979) • Murphy (1981) • Senner, West, and Norton (1981) • Hawkings(1982). Similar information from southeastern Alaska is from Petersen, Greilich, and Harrison (1981) and Heglund and Rosenberg (1985). For seabirds, we have summarized data primarily col- lected by personnel of the U.S. Fish and Wildlife Service or subcontractors to the Fish and Wildlife Service. Most of these data are from colony studies that took place in the fol- lowing locations: Forrester Island in southeastern Alaska; Middleton Island; Wooded Islands and the Barren Islands in the northern Gulf; Chisik Island in Cook Inlet; Sitkalidak Island and Chiniak Bay at Kodiak Island; and Semidi Islands, Ugaiushak Island, and the Shumagin Islands west of Kodiak Island (Fig. 16-1). Much of the data on seabird breed- ing biology is summarized in Baird and Gould (1983), and we draw heavily from that report. The broad scope of this chapter, and particularly the limited amount of data from some sites, does not permit a detailed analysis of the between-year and the between-colony differences in reproductive success and nesting phenology. These dif- ferences were sometimes profound. Instead, we summarize these data and present averages for several reproductive parameters. Information on the pelagic distribution and abundance of seabirds is primarily from Gould el al. (1982). Most infor- mation is for nearshore and continental shelf waters in spring, summer, and fall. Data on feeding ecology of seabirds come primarily from studies by the U.S. Fish and Wildlife Service. Nestling diets were studied at several colony sites in the Gulf, and pelagic 60170 170 55 I'ntmak Pi ^>ation and nes tling perio ds, and Fork-tailed 50 (37-68) 60(51-65) Boersma and reproductive success are summarized in Tables 16- 7, 16-8, storm-petrel Wheelwright 1979; 16-9, and 16-10, respectively. Summaries of seabird breed- Quinlan 1979 ing distributions in the Gulf of Alaska, their nesting phe- Leach's storm-petrel 42 — 66 (63-70) Palmer 1962; Quinlan 1979 Double-crested 28 (25-29) 50 (40-50) van Tets 1959; Palmer Table 16-8. cormorant 1962 Summary of timing of egg-laving for 21 seabird species breed ing in Pelagic 31 (28-32) 49 (42-58) Drent, van Tets, the Gulf of Alaska.3 cormorant Red-faced 33 — 50 — Tom pa, and Vermeer 1964 Period OF Baird and Gould 1985 Date of First Egg Egg-Lay INGb cormorant Mew gull 26 (?) 35 (?) Month Barth 1955 Na -Day SD(d) Na Days SD Glaucous- winged 27 (26-29) 40 (40-45) Drent et al. 1964 gull Northern fulmar Fork-tailed 7 5-30 2.9 7 25 5.1 Black-legged kittiwake 27(25-31) 42 (36-53) Coulson and White 1958; Maunder and storm-petrel 8 5-4 11.4 8 34 8.0 Threlfall 1972 Leach's storm-petrel Double-crested 5 5-27 20.3 Arctic tern 21 — 28(25-31) Baird and Gould 1985 cormorant 4 6-9 18.9 2 19 3.5 Aleutian tern 22 28(25-31) Baird and Gould 1985 Pelagic cormorant 9 5-29 4.5 8 26 8.3 Common 33 (32-34) 23(16-30) Tuck 1960 Red-faced cormorant 8 5-27 10.8 5 22 4.3 murre Mew gull 3 5-17 7.6 3 23 2.1 Thick-billed 33 (32-34) 23(16-30) Tuck 1960 Glaucous-winged gull 99 5-29 6.0 14 28 8.2 murre Black-legged kittiwake Arctic tern 22 7 6-6 5-22 11.5 5.9 19 3 25 30 9.7 5.3 Pigeon guillemot 30 (28-32) 35 (29-39) Drent etal. 1964 Aleutian tern 4 5-28 3.7 4 29 6.1 Common murre 16 6-17 12.6 12 32 8.8 Ancient 35(33-47) 2 (2-4) Sealv 1976 Thick-billed murre 3 6-6 5.6 5 27 5.2 murrelet Pigeon guillemot 2 5-25 5.0 2 33 7.8 Cassin's auklet 38 (37-42) 41 (35-46) Manuwal 1974c Ancient murrelet 2 5-3 35.4 9 31 21.2 Parakeet auklet 35 (35-36) 35 (34-37) Sealy and Bedard 1 973 Cassin's auklet 3 4-24 1 3. 1 3 53 15.7 Crested auklet 37 ( ? ) 34 (?) Sealv 1968 Parakeet auklet 3 5-17 9.5 3 31 12.1 Crested auklet 1 6-6 1 20 Rhinoceros 46 (42-49) 52 (42-62) Leschner 1976 Rhinoceros auklet 5 5-10 12.9 5 34 6.0 auklet Tufted puffin 17 5-25 5.1 13 28 6.8 Tufted puffin 40 (38-43) 40 (37-46) Wehle 1980 Horned puffin 14 6-12 4.1 13 22 5.9 Horned puffin 46(43-53) 46 (43-48) Sealy 1973; Baird and Gould 1985 a Sample size (N) is the number of 1 iiliiin \ears on whic h estimate is based. ''Mean range (in days) of a colon v-\ car 1 Values expressed as means (ranges). 492 Biological Resources Table 16-10. Productivity of seabirds in the Gulf of Alaska.^ FLEDGLINGS/ Fledglings/ Nest with Eggs/ Clutch Hatching Fledgling Sl'K lis Nest Attempt Nest with Eggs Nest Attempt Size Success Success Northern X 0.45 0.49 0.85 1 0.63 0.81 fulmar Range 0.12-0.63 0.15-0.72 0.80-0.87 0.23-0.79 0.66-0.91 Nh 5 7 5 5 5 nl> 2,086 1,761 1,913 1,778 1,196 Fork-tailed X 0.30 0.42 0.69 1 0.62 0.67 storm- Range 0.21-0.40 0.24-0.68 0.68-0.69 0.35-0.84 0.52-0.94 petrel N 2 6 2 6 6 n 255 519 367 519 319 Double-crested X 0.77 1.31 0.81 3.17 0.49 0.93 cormorant Range 0.95-1.67 2.67-3.67 N 1 2 1 2 1 1 n 26 36 26 55 27 Pelagic X 0.83 1.14 0.94 3.08 0.54 0.75 cormorant Range 0.00-1.96 0.14-2.05 0.75-0.96 2.17-3.64 0.29-0.68 0.47-0.93 N 17 9 7 11 6 6 n 1,052 274 191 795 421 Red-faced X 0.86 1.24 0.97 2.60 0.36 0.86 cormorant Range 0.00-2.33 0.32-2.33 0.90-1.00 2.12-3.08 0.24-0.48 0.81-0.90 N 11 5 4 2 2 2 n 690 304 272 219 89 Glaucous- X 1.08 2.46 0.69 0.61 winged gull Range 0.16-1.58 1.98-2.93 0.35-0.86 0.18-0.89 N 11 22 13 11 n 761 1,628 2,283 1,331 Mew gull x" 0.83 2.69 0.82 0.38 Range 0.70-0.97 2.51-2.88 0.72-0.87 0.33-0.42 N 3 3 3 3 n 104 104 276 228 Black-legged X 0.33 0.41 0.71 1.63 0.49 0.50 kittiwake Range 0.00-1.23 0.00-1.45 0.02-0.91 1.26-1.98 0.00-0.85 0.06-0.90 N 39 26 20 29 18 16 n 15,305 2,859 3,458 2,840 1,568 Arctic tern X Range 2.06 1.79-2.29 0.68 0.32-0.91 0.77 N 8 7 1 n 417 861 17 Aleutian tern X Range N n 1.66 1.35-1.89 4 215 0.53 0.16-0.65 4 373 Common X 0.32 0.50 0.78 1 0.50 0.73 murre Range 0.07-0.47 0.29-0.64 0.71-0.87 0.15-0.70 0.54-0.86 N 5 4 4 7 4 n 386 273 356 894 187 Thick-billed X 0.38 0.50 0.74 1 0.61 0.77 murre Range 0.24-0.52 0.43-0.63 0.56-0.82 0.54-0.97 0.68-0.85 N 4 4 4 4 4 n 425 330 425 351 221 Tufted puffin X 0.78' 0.64 1 0.86 0.75 Range 0.76-0.80 0.44-0.90 0.85-0.88 0.46-0.91 N 2 9 3 11 n 71 801 99 340 Horned puffin X 0.60 1 0.79 0.74 Range 0.29-0.77 0.64-0.93 0.36-0.91 N 8 10 9 n 361 375 243 'Sources: Snarslu (1971); Baird and Gould (1985); Hatch (1985); Gould el al. (1983); Nysewander and Irons (U.S. Fish and Wildlife Service, pers. comm., 1985); G. Mulberg (U.S. Fish and Wildlife Service, pers. comm., 1984). ' Sample sizes are number of colony years (N) and total nests, eggs, or chicks (n) on which estimate is based. Hatching success (0.86) x fledging success (0.75) = 0.65. probably a better estimate of breeding success for tufted puffins. Makine Birds 493 kittiwak.es because fulmars prefer the higher, more veg- etated portions of the cliffs (Hatch and Hatch 1983; Squibb and Hunt 1983). Approximately two million northern fulmars breed in Alaska, of which 96% occur at four sites: the Pribilof Islands, the St. Matthew Island complex, Chagulak Island in the Aleutian Islands, and the Semidi Islands in the Gulf of Alaska. An estimated 440, 000 fulmars nest in the Gulf of Alaska at 11 sites, but with the exception of the Semidi Islands, the colonies are of little significance (Fig. Hi— 5). Nesting by fulmars in Alaska has been studied on the Semidi Islands (Hatch 1979, 1983, and 1985) and the Pribilof Laying Ha m him Islands (Hunt, Kppley, and Drury 1981). The nesting season is long. Northern fulmars at the Semidi Islands usually arrive at their colonies in March or early April and most chicks depart sometime in September or early October (Fig. 10-4). On average, about 85% of the pairs that attend nest- ing sites lay eggs and about 50% of the pairs that lay eggs successfully produce a fledged chick (Table 16-10). With the exception of 1976, reproductive success — defined as the number of chicks fledged per nest with eggs — was generally high for fulmars on the Semidi Islands. Hatch (1985) sug- gests that food availability is the primary factor affecting reproductive success. FLEDGING Cassin's Auklet Ancient Murrelet Fork-Tailed Storm-Pelrel Rhinoceros Auklet Parakeet Auklet Mew Gull Arctic Tern Pigeon Guillemot Tufted Puffin Red-Faced Cormorant Aleutian Tern Leach's Storm-Petrel Glaucous-Winged Gull Pelagic Cormorant Northern Fulmar Thick-Billed Murre Crested Auklet Black-Legged Kittiwake Double-Crested Cormorant Horned Puffin Common Murre 10 20 Apr 10 20 May — r~ 30 10 20 JUN ~r- 30 10 20 T' — r~ 30 10 20 Aug 30 10 20 Sep 10 20 ()( I 30 10 20 Nov Figure 16-4. Nesting phenologies of seabirds in the Gulf of Alaska. Thin horizontal lines indicate the extreme dates on which each event occurred and bars indicate the mean first and last dates of occurrence. Sample sizes (colony-years) are as in Table 16-8. Fre- quently, only one or two of the three distributions were observed per species. In those instances, the timing of the other events was calculated using the mean incubation and fledging periods given in Table 16-9. 494 Biological Resources 160 150 Figure 16-5. Northern fulmar breeding densities for the Gulf of Alaska. 160 60 130 Figure 16-6. 160 150 Fork-tailed storm-petrel breeding densities for the Gulf of Alaska. Fork-Tailed Storm-Petrel 55 130 Figure 16-7. 160 150 Leach's storm-petrel breeding densities for the Gulf of Alaska. Marine Biros 495 Storm-petrels are small, abundant oceanic birds. Fork- tailed storm-petrels are restricted to the North Pacific, and Leach's storm-petrels are found on both sides of the North Atlantic and North Pacific Oceans. In Alaska, the breeding distributions of both species extend from Petrel Island at the tip of southeastern Alaska to the westernmost Aleutian Islands (Figs. 16-6, 16-7). The breeding populations of fork- tailed storm-petrels and Leach's storm-petrels are esti- mated at one million and 1.2 million birds, respectively. The nocturnal habits of storm-petrels and their preferences for nesting in isolated areas have discouraged censusing efforts, so population data are often either crude or lacking. Both fork-tailed and Leach's storm-petrels commonly nest in burrows dug in the soil on both forested and treeless islands. Fork-tailed storm-petrels also frequently nest in crevices in rocky habitats. The breeding season for storm- petrels is the longest of all Alaskan seabirds (Fig. 16-4). Fork-tailed storm-petrels commence egg laying as early as late April in the Gulf of Alaska. Leach's storm-petrels, on average, breed about 20 days later than fork-tailed storm-petrels, and the nestling period may extend into November at some colonies. Incubation periods and nes- tling periods are long for both species (Table 16-9), and interrupted incubation is common at least for fork-tailed storm-petrels (Boersma, Wheelwright, Nerini, and Wheel- wright 1980). Boersma and Wheelwright (1979) found that hatched eggs on the Barren Islands were neglected an average of 11 days each in 1977. Interrupted incubation probably occurs in many Procellariiformes (Boersma 1982). At colonies in the Gulf of Alaska, -69% of the active fork-tailed storm- petrel burrows contained eggs. Hatching success averaged 62%, and about 42% of the pairs producing eggs fledged a chick (Table 16-10). Similar data on the reproductive per- formance of Leach's storm-petrels are unavailable. Cormorants. Four species of cormorants occur in Alaska, of which three species, the double-crested {Phalacrocorax auritus), pelagic (P. pelagicus), and red-faced cormorants {P. wile), are common in the Gulf of Alaska. The fourth species, Brandt's cormorant (P. penicillatus), is uncom- mon but is possibly increasing its range in southeastern Alaska (U.S. Fish and Wildlife Service, unpubl. data). Dou- ble-crested cormorants are widespread throughout much of North America, but the other three species are restricted to the North Pacific basin. The red-faced cormorant is endemic to the subarctic North Pacific and Bering Sea (American Ornithologists' Union 1983). In the Gulf of Alaska, double-crested and pelagic cor- morants are widespread (Figs. 16-8, 16-9), but red-faced cor- morants nest exclusively west of Cape St. Elias (Fig. 16-10). A small population of Brandt's cormorants nested in Prince William Sound in 1972 (Isleib and Kessel 1973), but they are now known to occur only at two sites in southeastern Alaska. The size of various breeding populations is only crudely known. Most cormorants were not identified to species dur- ing censuses, hence population estimates must be consid- ered minimal and their distributions, as depicted here, incomplete. Double-crested cormorants place their nests on flat islets, on wide cliff ledges, on gradual slopes of islands, and in trees. In contrast, the pelagic and red-faced cormorants nest almost exclusively on narrow cliff ledges (Sowls et al. 1978). On average, the nesting season of cormorants in the Gulf of Alaska extends from the end of May to mid- to late-September (Fig. 16-4). Cormorants lay multi-egg clutches, with double-crested and pelagic cormorants aver- aging slightly greater than three eggs per nest, compared with ~ 2.6 eggs per nest for red-faced cormorants (Table 16-10). Reproductive success was highly variable for all species, averaging slightly more than one chick per nest (Table 16-10). Hatching success was uniformly low for all these spe- cies, indicating that most mortality occurred during incuba- tion. Egg predation by glaucous-winged gulls (Larus glaucescens), bald eagles {Haliaeetus leucocephalns), common ravens {Corvus corax) or northwestern crows (Corvus caurinus) was important at most study sites. 160 140 60 130 60 55 Double-Crested Cormorant 5'' \. 55 130 160 150 Figure 16-8. Double-crested cormorant breeding densities for the Gulf of Alaska. 140 496 Biological Resources 60 130 160 150 Figure 16-9. Pelagic cormorant breeding densities for the Gulf of Alaska. 60 130 160 150 Figure 16-10. Red-faced cormorant breeding densities for the Gulf of Alaska. Gulls. Gulls are probably the most familiar of seabirds to people along the Gulf coast of Alaska. Four species breed in the Gulf of Alaska: 1) mew gull (Larus canus) 2) herring gull (L. argentatus) 3) glaucous-winged gull (L. glaucescens) 4) black-legged kittiwake (Rissa tridactyla). All four species are widely distributed. The mew gull is found across Eurasia and northwestern North America. The herring gull is circumpolar. The glaucous-winged gull occurs from Washington State to Nunivak Island, and west to the Commander Islands (Sowls el al. 1978), and the black- legged kittiwake is found in both the North Atlantic and North Pacific Oceans. Mew gulls are much less abundant than glaucous-winged gulls in the Gulf of Alaska, but are nevertheless widespread (Fig. 16-11) — occurring at 69 nesting sites (Table 16-7). They nest in a variety of habitats, including moist maritime mead- ows, crowberry tundra, sandy beaches, the grassy tops of islands, and in trees (Baird and Gould 1985). In Anchorage, mew gulls have been found nesting on Fill sites, on truck trailers, and on industrial debris (C.I. Adamson, Anchorage, AK, pers. comm., 1984). Mew gulls usually lay two to three eggs per nest. Hatching success was relatively high, but fledg- ing success was low (Table 16-10). Overall reproductive suc- cess averaged 0.83 fledglings per nest with eggs. Baird and Gould (1985) list starvation, exposure, predation, and egging as the principal factors affecting reproductive success. Breeding herring gulls are uncommon in the Gulf of Alaska. They frequently hybridize with glaucous-winged gulls in the northern Gulf (Patten 1980). Colonies of glaucous-winged gulls vary in size from two birds to 11,000 birds. More than 460 colonies have been located in the Gulf of Alaska, and the breeding population probably exceeds 200,000 individuals. The majority of the Makine Birds 497 60 130 160 150 Figure 16-11. Mew gull breeding densities for die Gulf of Alaska. 60 130 160 150 Figure 16-12. Glaucous-winged gull breeding densities for the Gulf of Alaska. colonies are located west of Cape St. Elias (Fig. 16-12). Nests are almost always situated on offshore rocks or islands, and nests are placed on sandbars, along beaches, on the flat tops and gentle slopes of islands, and occasionally on cliffs. Over- all reproductive success for gulls is difficult to determine because the cryptically colored chicks leave the nest shortly after hatching and are difficult to find. Our best estimates indicate that about one chick is fledged per nest with eggs, which is similar to the productiv- ity of the species in British Columbia (Vermeer 1963). The availability of food during the incubation period, predation by other birds and river otters, and egging by humans were important factors affecting reproductive success of glaucous-winged gulls in the Gulf of Alaska (Baird and Gould 1985). Black-legged kittiwake colonies occur at 177 sites in the Gulf of Alaska, mostly west of Cape St. Elias (Fig. 16-13). The estimated population of breeding birds exceeds 700,000 individuals (Table 16-7). Although long-term population data are not available for most sites in the Gulf of Alaska, at Middleton Island, breeding populations have increased from ~ 14,000 birds in 1956 to ~ 144,000 birds in 1974 (Baird and Gould 1985). Increases have also occurred at Chiniak Bay on Kodiak Island. Black-legged kittiwakes most commonly nest on the narrow ledges of steep cliffs. On Middleton Island, black- legged kittiwakes colonized steep, soil-covered slopes after the entire island was uplifted during the Great Alaskan Earthquake of 1964. Kittiwakes also nested on an old ship- wreck and on boulders protruding from a meadow on Mid- dleton Island. Kittiwakes first arrive at their colonies in March and the peak of egg laying occurs from earlyjune to earlyjuly (Baird and Gould 1985). Very early nesting on Middleton Island in 1978 was responsible for a wider range of egg dates than for any other seabird (Fig. 16-4). About 71% of the kittiwake pairs that built nests laid eggs. The average clutch size for 3,328 nests was 1.63 eggs per clutch, but hatching success was 498 Biological Resources 60 130 160 150 Figure 16-13. Black-legged kittiwake breeding densities for the Gulf of Alaska. Figure 16-14. 160 150 Arctic tern breeding densities for the Gulf of Alaska 60 130 Figure 16-15. 160 150 Aleutian tern breeding densities for the Gulf of Alaska. Makinl Bikds 499 low compared with other gulls (Table 16-10). Approximately 0.41 chicks fledged per nest with eggs. An important feature of kittiwake biology in the Gulf is the great variation in reproductive success among years and colonies. This variation was manifest during all phases of the nesting cycle including: I) the proportion of nest-build- ing pairs that laid eggs, 2) the clutch sizes, 3) the hatching success, and 4) the fledging success. Black-legged kittiwakes at some colonies such as Middleton Island and Chisik Island had consistently low reproductive success (Band and Gould 1985), while those at most other sites raised chicks in some years and failed completely in others. Reproductive success of kittiwakes elsewhere in Alaska is similarly variable (Hunt, Eppley, and Drury 1981; Springer, Roseneau, Murphy, and Springer 1984), which is in marked contrast to high kittiwake productivity in the North Atlantic (Coulson 1972; Maunder and Threlfall 1972; and Wooller and Coulson 1977). Terns. Arctic terns (Sterna paradisaea) are circum- polar-breeding seabirds and are abundant in both the Arctic and the subarctic regions of the North Pacific. Aleu- tian terns (S. aleutica), on the other hand, are found only in the North Pacific. Breeding Arctic terns occur at 106 colo- nies in the Gulf (Fig. 16-14); Prince William Sound and the Kodiak Archipelago contain the largest number of colonies. Aleutian terns are much less abundant and more local than Arctic terns, occurring at 22 sites in the Gulf (Table 16-7, Fig. 16-15). Terns nest primarily in open areas such as on low grassy islands, in flat areas with low vegetation, and on gravel or sandy beaches (Baird and Gould 1985). The breeding season of both species extends from mid-May to mid-August (Fig. 16-4). Most individuals of both species have departed the breeding grounds by late August (Baird and Gould 1985). Both Arctic and Aleutian terns lay from one to three eggs per nest and hatching success varies considerably from year to year for both species. Field investigators both at Sit- kalidak Strait and at Chiniak Bay on Kodiak Island were unable to determine estimates of overall productivity. Human disturbance, predation of both eggs and chicks, and exposure of both eggs and chicks to poor weather were the most important factors affecting productivity. Egging by humans near Sitkalidak Strait greatly reduced the value of studies undertaken there. Murres. Both common (Uria aalge) and thick-billed murres (U. lomvia) are widely distributed in the North Pacific and the North Atlantic Oceans (Tuck 1960). Approximately five million birds of each species nest in Alaska (Sowls et al. 1978). Both species are widespread in the Gulf of Alaska (Figs. 16-16, 16-17), although common murres are consider- ably more abundant than thick-billed murres. The latter species appears to be expanding its range into southeastern Alaska (J.W. Nelson, U.S. Fish and Wildlife Service, pers. comm., 1984) and British Columbia (Vallee and Cannings 1983). Because murres are difficult to distinguish on their crowded nesting ledges, they frequently were not identified to species, so there are no precise population estimates for each species and their known breeding distributions are imprecise. Murres typically nest on the steep cliffs of offshore islands and mainland promontories where they typically lay one egg on bare rock or soil. Some segregation between the two species occurs, with common murres preferring to nest in dense aggregations on wide cliff ledges or on the tops of sea stacks, and thick-billed murres preferring to nest in sin- gle lines on long, narrow ledges (Squibb and Hunt 1983; Baird and Gould 1985). Less frequently, common murres can be found nesting in crevices, in the entrances to puffin burrows, in dense grass and umbels, and on vegetated and unvegetated talus slopes (Baird and Gould 1985). The pre- dilection of murres for steep, inaccessible cliffs greatly limits their vulnerability to terrestrial predators (Petersen 1982). On average, the breeding schedule of thick-billed murres precedes that of common murres by about two weeks (Fig. 16-4). Murre chicks jump from their nesting ledges before they are fully grown — usually about 23 days after hatching. Most chicks have departed the colony by mid-September. Approximately 50% of the pairs that pro- duced eggs fledged a chick (Table 16-10). During the mid- to late 1970s, productivity of murres on the Pribilof Islands and in Norton Sound was generally higher than in the Gulf of Alaska (Hunt, Eppley, and Drury 1981). Pigeon Guillemot. Pigeon guillemots are among the few alcids to lay two eggs. Colonies, which are frequently nothing more than loosely scattered pairs, are found throughout the Gulf, but are concentrated west of Cape St. Elias (Fig. 16-18). Rock crevices, boulder beaches, and talus slopes are favorite natural nesting places, but this species has also adapted well to man-made structures such as boat piers, rock jetties, and even the tires used for bumpers on boat piers (Sowls, DeGange, Nelson, and Lester 1980). The nesting season extends from late May to late August. There are few estimates of the reproductive success for pigeon guillemots in Alaska. The most intensive study occurred at Naked Island in Prince William Sound where the number of chicks fledged per nest ranged from 0.68 to 1.16 (x = 0.86) (Kuletz 1983). Small Alcids. Seven species of small alcids nest in the Gulf of Alaska: 1) marbled murrelet (Brachyramphus marmoratus) 2) Kittlitz's murrelet (B. brevirostris) 3) ancient murrelet (Synthliboramphus antiquus) 4) Cassin's auklet (Ptychoramphus aleuticus) 5) parakeet auklet {Cyclorrhynchus psittacula) 6) least auklet (Aethia pusilla) 7) crested auklet [Aethia cristatella). Little is known of the first two species (marbled murrelet and Kittlitz's murrelet). Both are widespread in the Gulf of Alaska in coastal waters, but their solitarv and largelv undiscovered nesting habits have all but precluded their study. Marbled murrelets nest on branches of trees in old growth coastal forests (Binford, Elliott, and Singer 1975), on the ground on treeless islands (Simon 1980; Hirsch, Woodby, and Astheimer 1981), or on the mainland (Day, Oakley, and Barnard 1983). Kittlitz's murrelets nest on rocky substrates in the alpine zone of coastal mountain ranges 500 Biological Rfsources 160 150 Figure 16-16. Common murre breeding densities for the Gulf of Alaska. 160 150 Figure 16-17. Thick-billed murre breeding densities for the Gulf of Alaska. 160 150 Figure 16-18. Pigeon guillemot breeding densities for the Gulf of Alaska. Marinf Birds 501 (Bailey 1973; Day et al. 1983). What little is known of their biology is summarized in these papers and in Sealy (1974, 1975a) and Kiff (1981). Ancient murrelets nest from British Columbia through the Aleutian Islands and south to Korea (Sovvls et al. 1978). Their nocturnal nesting habits may limit the northern extent of their range. Colonies of ancient murrelets are diffi- cult to find, not only because of their nocturnal, bur- row-nesting habit, but also because of the limited time they spend on land each breeding season. Nests are found in bur- rows, under tree roots, in rock crevices, and under shoreline debris. In southeastern Alaska, ancient murrelets may nest in forests, but they also are at home on treeless islands. Pres- ently, 27 widespread colonies of ancient murrelets have been identified in the Gulf (Fig. 16-19). The largest of these colonies — on Forrester Island in southeastern Alaska — has a population of 60,000 birds. The breeding biology of this species is summarized by Sealy (1976). Among the small alcids nesting in the Gulf of Alaska, ancient murrelets have a unique breeding strategy. After an incubation period of about 35 days, the precoi ial chicks hatch and, at between two and four days of age, go to sea with their parents. This arrangement relieves the par- ents of costly long-distance flights with food to colonies, and probably enables the parents to occasionally raise two chicks — provided the chicks survive their extraordinary journey to sea. Ancient murrelets are one of the ear- liest-nesting species in southeastern Alaska (Fig. 16-4), and most adults and chicks have usually departed the colonies by late June. Cassin's auklet is another small burrow-nesting seabird of the North Pacific. Colonies extend from Baja California north through the Aleutian Islands (American Ornithologists' Union 1983). Nearly two dozen Cassin's auklet colonies have been found in the Gulf of Alaska, most of which are concentrated south of the Alaska Peninsula (Fig. 16-20). Population estimates are available for only a few of these colonies. 160 150 Figure 16-19. Ancient murrelet breeding densities for the Gulf of Alaska. 60 130 160 150 Figure 16-20. Cassin's auklet breeding densities for the Gulf of Alaska. 502 Biological Resources Cassin's auklets are one of the earliest breeding seabirds in Alaska (Fig. 16-4). There have been no detailed studies of this species in Alaska, but they have been studied both in California (Thoresen 1964; Manuwal 1974a, b, c; Manuwal 1979; and Speich and Manuwal 1974) and in British Colum- bia (Vermeer, Vermeer, Summers, and Billings 1979; Ver- meer 1981, 1984). Parakeet auklets are common breeding seabirds in the western Gulf of Alaska, in the Aleutian Islands, and in the Bering Sea (Sowls et al. 1978). They are widespread west of Kodiak Island, but are absent east of Cape St. Elias (Fig. 16-21). They prefer nesting habitats that include talus slopes, boulder beaches, and crevices in cliffs. Parakeet auklets are not as gregarious as other auklets, usually nesting as solitary pairs or in small colonies. Little work has been done on the biology of this auklet in the Gulf of Alaska, but it has been studied on St. Lawrence Island in the Bering Sea (Bedard 1969a, b; Sealy and Bedard 1973). Both least- and crested auklets are birds of the Bering Sea and the Aleutian Islands (Sowls et al. 1978). Small num- bers of least auklets are found at two sites in the Gulf of Alaska: the Shumagin Islands and the Semidi Islands. Twenty birds were counted at these sites, although we feel that 100 birds is a more reliable estimate. Breeding crested auklets are comparatively abundant in the Gulf of Alaska, numbering over 40,000 birds. All seven breeding sites are located in the Shumagin Islands. Elsewhere in Alaska, least and crested auklets nest together in huge colonies. They prefer nest sites that include talus slopes, boulder beaches, and cracks in cliff faces. Com- petition between the two species for nest sites is minimized by their size difference (Bedard 1969a; Knudtson and Byrd 1982). Few data from the Gulf of Alaska are available on these species, but considerable information on their reproductive biology is available from colonies both in the Bering Sea (Bedard 1969a, b; Sealy 1968, 1972,) and on the Aleutian Islands (Knudtson and Byrd 1982; Byrd, Day, and Knudtson 1983). Puffins. Three puffin species occur in the Gulf of Alaska: 1) rhinoceros auklet (Cerorhinca monocerata) 2) tufted puffin (Fratercula cirrhata) 3) horned puffin (F. corniculata). Rhinoceros auklets are the largest of the burrow-nesting nocturnal alcids. They are widely distributed in the North Pacific, with colonies found from California to the Aleutian Islands and Japan (American Ornithologists' Union 1983). Forrester Island in southeastern Alaska — with an estimated population of more than 100,000 birds — is the only large colony in Alaska. The remaining 12 colonies in the Gulf are small and widely dispersed (Fig. 16-22). Detailed studies of this species have occurred at Middleton Island (Hatch 1984), in British Columbia (Vermeer 1978; Vermeer and Cullen 1979; Vermeer, Cullen and Porter 1979; and Vermeer and Westrheim 1984), and in Washington State (Richardson 1961; Leschner 1976; and Wilson 1977). Tufted puffins are among the most abundant and wide- spread of Alaskan seabirds. Some 382 colonies are located in the Gulf of Alaska and the breeding population may exceed 1.5 million individuals (Table 16-7, Fig. 16-23). The center of this species' abundance is in the western Gulf of Alaska and the eastern Aleutian Islands (Sowls et al. 1978). Tufted puffins primarily nest in earthen burrows, but will occasionally nest in rocky habitats. The most typical colony sites are either on steep grassy slopes or on the grassy shoul- ders of cliffs. Tufted puffins return to their colonies in the central Gulf of Alaska in early May, and the breeding season extends to early September (Baird and Gould 1985). Like most alcids, tufted puffins lay one egg per season, but there is evidence that suggests that some birds may re-lay follow- ing loss of their first egg (Wehle 1980). Aspects of the breeding biology of tufted puffins are sum- marized in Baird and Gould (1985), Burrell (1980), and Wehle (1976, 1980, 1982a, b, 1983). In studies conducted by the U.S. Fish and Wildlife Service, approximately 64% of 160 150 Figure 16-21. Parakeet auklet breeding densities for the Gulf of Alaska. Marinf Biros 503 150 160 150 Figure 16-22. Rhinoceros auklet breeding densities for the Gulf of Alaska. 60 130 160 150 Figure 16-23. Tufted puffin breeding densities for the Gulf of Alaska. 160 150 Figure 16-24. Horned puffin breeding densities for the Gulf of Alaska. 504 BlOIOCK M RlMH'KUs the burrows that showed some activity by tufted puffins con- tained eggs. Because tufted puffins frequently desert their nests if disturbed during the incubation period, their reproductive success varied markedly between disturbed and undisturbed areas within the colonies. Between 1976 and 1978, reproductive success of tufted puffins that were frequently disturbed during the incubation and nestling periods averaged 0.34 chicks fledged per nest with eggs, compared with 0.74 chicks fledged per undisturbed nest with eggs. Overall reproductive success for tufted puffins for all vears of study was about 65% for those colonies where there was a minimum of disturbance (Table 16-10). Horned puffins are common in the Gulf of Alaska, although their abundance does not equal that of the tufted puffins. Approximately 304 colonies of horned puffins are located in the Gulf, ranging from southeastern Alaska to Unimak Pass (Fig. 16-24). The breeding population may exceed one million individuals. The western Gulf of Alaska is unquestionably the center of this species' breeding dis- tribution. Horned puffins prefer to nest in boulder rubble, in talus slopes, and in rock crevices, although the population nest- ing on Sutlik Island in the Semidi Islands uses burrows almost exclusively (Hatch and Hatch 1983). Horned puffins arrive at their colonies in the central Gulf of Alaska in early May, and the nesting season extends through early October (Fig. 16-4). Overall reproductive success, in terms of fledg- lings per nest with eggs, was 60% (Table 16-10). The natural history of horned puffins is summarized in both Sealy (1973) and Wehle (1980). Pelagic Distribution Physical properties of Gulf waters, such as surface water temperature and salinity, affect the distribution and abun- dance of seabirds by directly affecting the species composi- tion, quantity, and availability of food organisms. The three topographic features that most obviously influence the dis- tribution and abundance of seabirds in the Gulf of Alaska include 1) a deep ocean basin studded with seamounts, 2) a wide continental shelf with a wealth of small and large islands, and 3) extremely rocky coastal areas with many deep fjords and bays. In general, seabirds are found wherever physical conditions are appropriate, and within such areas, seabirds become distributed in response to food availability and breeding sites. Water circulation in the Gulf is dominated by the North Pacific Current, which flows eastward from Japan before it bifurcates into two currents off North America. The first branch curves northward to form the Alaska Current (Favorite 1967), which flows westward along the shelf break, occasionally sending branches southward to complete the Alaskan Gyre (see Reed and Schumacher, Ch. 3, this vol- ume). The second branch curves southward to form the Cal- ifornia Current. In the northern Gulf and along the Alaska Peninsula, there is also a distinctly narrow, dilute current called the Alaska Coastal Current, which also flows west- ward (Royer 1981). The Transition Domain and Subarctic Boundary, which occur across the North Pacific between 35°N and 45°N, mark the boundary between subtropical and subarctic water masses (Favorite, Dodimead, and Nasu 1976). These water masses are characterized by distinctly different avifaunas (Gould 1983, R. H. Day, University of Alaska, pers. comm., 1985). In the eastern Pacific, the separation of distinct faunas becomes less structured where the North Pacific Cur- rent bifurcates to form part of the Alaskan Gyre and Califor- nia Current systems. Pelagic surveys of seabirds indicate that large seasonal differences in seabird abundance occur across all habitats in the Gulf of Alaska (Gould et al. 1982). Seabird populations in the Gulf are both least numerous and least diverse in winter. During spring, however, profound changes occur in seabird numbers and diversity as returning breeders and summer visitors appear and birds begin concentrating over the deeper waters of the continental shelf and in oceanic regions. As summer approaches, increasing numbers of birds move onto the continental shelf and into nearshore waters. Overall bird densities in shelf, shelf-break, and oceanic habitats in spring are higher than at any other time of the year (Table 16-11). Overall bird densities in spring are highest over the continental shelf and shelf break, reflecting the preference for this habitat by the millions of short- tailed and sooty shearwaters that spend the austral winter in the North Pacific and Bering Sea (Table 16-11). During mid-summer, seabird populations in the Gulf of Alaska may exceed 40 million individuals (Gould et al. 1982). Densities of seabirds in bays and fjords are higher at this time of year, reflecting the large number of nesting seabirds. Some species such as cormorants, guillemots, and Brachyramphus murrelets remain near shore. Others, includ- ing kittiwakes, puffins, fulmars, and storm-petrels, are capa- ble of foraging far from colonies. The continental shelf contains, by far, the largest densi- ties of seabirds in summer (Table 16-11). Shearwaters — par- ticularly short-tailed shearwaters — make up the majority of birds on the shelf. Alcid densities over the shelf decrease markedly from their densities in nearshore habitats. Shelf-break waters contain similar densities of seabirds as do nearshore habitats, and shearwaters again are the domi- nant group in this region. Tubenose populations such as albatrosses, fulmars, and storm-petrels are more dense over shelf-break waters than they are over the continental shelf. Table 16-11. Total densities of seabirds (birds/km2) in the Gulf of Alaska by season and habitat (from Gould et al. 1982). H, \BITAT Season Bay Shelf Shelf-break Oceanic Spring 29.0 158.2 57.2 43.8 (Mar-May) Summer 56.7 134.1 55.8 14.7 (Jun-Aug) Fall 35.6 59.9 22.4 6.7 (Sep-Nov) Winter 18.2 13.7 22.0 3.2 (Dec-Feb) Makini Birds 505 The lowest seabird densities in the Gulf in summer occur in oceanic waters where sooty shearwaters and other tubenoses predominate (Gould et al. 1982; Sanger and Ainlev, in press). Immature tufted and horned puffins were found to be an important component of the avifauna in oceanic waters south of the western Aleutian islands (A.R. DeGange and D.J. Forsell, U.S. Fish and Wildlife Service, unpubl. data), and it is likely that many of the puffins sum- mering over deep oceanic water in the Gulf of Alaska are also immature. In the fall, seabird densities in the Gulf decrease over all habitats (Table 16-11). This is particularly true on the conti- nental shelf as the shearwaters depart for their breeding grounds in the Southern Hemisphere. Alcids also disperse from coastal waters, resulting in lower densities of these birds in nearshore areas. Seabird densities decrease even further in winter (Table 16-11), especially in nearshore, shelf, and oceanic habitats. Seabird densities over shelf-break habitats are similar to densities in the fall, reflecting the importance of this area to wintering fulmars, fork-tailed storm-petrels, kittiwakes, and murres. More precise information on temporal and spatial dis- tribution is available for some Gulf species. Both black- footed and Lavsan albatrosses are non-breeding visitors to the Gulf of Alaska, reaching their peak abundance in late summer and early fall (Gould et al. 1982). The striking con- centration of albatrosses along the shelf-break front (Gould et al. 1982) suggests that there is ample food there. Of the two species, black-footed albatrosses were the more numer- ous— particularly in the northeastern Gulf — indicating a more easterly distribution of this species in the North Pacific during the non-breeding season than the distribu- tion of Lavsan albatrosses (see also Shuntov 1972; Fisher and Fisher 1972; and Sanger 1974). Northern fulmars were simi- larlv concentrated along the Gulf shelf break during both summer and winter (Fig. 16-25). It is estimated that more than 26 million short-tailed and sooty shearwaters occur in the Gulf of Alaska in summer, 68% of which are sooty shearwaters (Gould et al. 1982). There is some geographical separation between the two shearwater species. In the northern Gulf, sooty shearwaters appear to outnumber short-tails by a ratio of nearly nine to one; west of Kodiak Island, the two species are found in approximately equal abundance (Gould et al. 1982). Gould et al. (1982) also suggested that some habitat separa- tion occurs between the two species. Short-tailed shear- waters were more abundant than sooty shearwaters over the continental shelf, but were uncommon over shelf-break and oceanic habitats (Fig. 16-25). Sooty shearwaters, in con- trast, were about equally abundant over shelf and shelf-break habitats and were more abundant than were short-tailed shearwaters over oceanic waters (Fig. 16-25) (see also Sanger and Ainlev, in press). Most shearwaters depart for the Southern Hemisphere in fall, but small num- bers of over-wintering birds have been observed both west of the Queen Charlotte Islands in British Columbia and south of Kodiak Island (Gould et al. 1982). Both Leach's storm-petrels and fork-tailed storm-petrels were common in the Gulf of Alaska in summer, and were most frequently associated with shelf-break and oceanic habitats (Fig. 16-25). Fork-tailed storm-petrels were fre- quently observed on the continental shelf, particularly near breeding colonies. Leach's storm-petrels, however, are more pelagic than fork-tailed storm-petrels, and were only occasionally observed on the shelf. In winter fork-tailed storm-petrels were uncommon and were found principally outside the shelf break. Leach's storm-petrels disperse southward to tropical waters (Palmer 1962). Several species attained their highest summer densities in nearshore waters, coinciding with the concentration of breeding birds near colonies. These species included cor- morants, glaucous-winged gulls, black-legged kittiwakes, pigeon guillemots, marbled murrelets, and tufted puffins. Apparently, the life histories of cormorants, pigeon guillemots, and marbled murrelets are closely tied to the nearshore zone. These species were rarely seen far offshore, and at least in the case of cormorants and marbled mur- relets, densities in winter were also higher in nearshore hab- itats when compared to offshore areas (Fig. 16-25). In contrast, densities of glaucous-winged gulls, black- legged kittiwakes, and tufted puffins decreased in nearshore habitats following the breeding season. In winter, densities of glaucous-winged gulls were highest over the shelf and the shelf break (Fig. 16-25). An unknown percentage of the glaucous-winged gull population migrates southward far offshore and along the coast as far south as California (Sanger 1973; Harrington 1975), and some also concentrate around coastal communities in Alaska at this time. Densities of black-legged kittiwakes in winter were highest over the shelf-break (Fig. 16-25). They are uncommon along the coast of Alaska in winter. Tufted puffins dispersed widely to sea following the breeding season (Shuntov 1972) and were rarely encoun- tered during surveys over the shelf of the Gulf of Alaska dur- ing winter (Gould et al. 1982). Tufted puffins are one of the main components of the winter seabird community across the entire oceanic subarctic Pacific (Shuntov 1972; Sanger and Ainley, in press), although they are widely dispersed. Common murres were most abundant near shore, especially in winter when they attained their highest densi- ties (Fig. 16-25). Common murres were an especially impor- tant component of the wintering avifauna around Kodiak Island (Forsell and Gould 1981). Thick-billed murres — although less abundant in the Gulf of Alaska than common murres — were relatively more abundant over oceanic water than in nearshore or continental shelf habitats (Gould et al. 1982). We were unable to make comparisons of summer versus winter densities for additional species. During winter, few- surveys were undertaken, and several of the species were not observed with any frequency. There is some evidence that shelf and shelf-break habitats are important for Arctic terns, ancient murrelets, Cassin's auklets, and horned puffins during summer (Fig. 16-25). Feeding Ecology Seabirds differ not only in terms of the geographic areas where they forage, but in terms of the way they use different depth strata in the water column, the maximum depths to 506 Biological Resources 12-i 8 Northern Fulmar 20 Sooty Shearwater Short-Tailed Shearwater Fork-Tailed Storm-Petrel Leach's Storm-Petrel Cormorants Glaucous-Winged Gull Arctic Tern Common Murre Ancient Murrelet Tufted Puffin Shelf oceanic BREAK Shelf Shelf Oceanic BREAK Shelf Shelf oceanic break ■ Summer (June — August) *~ Winter (December — February) Figure 16-25. Winter and summer seabird densities in four pelagic habitats in the Gulf of Alaska. (Modified from Gould et al. 1982.) which they descend to feed, and (in shallower waters) their tendencies to forage on or near the bottom. Besides those instances where birds are caught in fishing gear at known depths (Piatt and Nettleship 1985), foraging depths can often be deduced by a careful evaluation of the habits of prey species and a knowledge of water depth where birds were collected (Croxall and Prince 1980; Ainley, Anderson, and Kelley 1981; and Sanger and Jones 1982). For purposes of comparing foraging behavior and diets, seabirds in the Gulf may be divided into four groups — based on information in Table 16-12: 1) surface-feeders that are restricted to feeding in 0.5 m depths in either coastal or oceanic habitats 2) shallow divers that regularly forage down to ~ 20 m in either coastal or oceanic habitats 3) coastal foragers that regularly forage down to at least 40 m either in mid-water or on the bottom 4) pelagic foragers that descend from at least 40 m to well over 100 m depending on species, and which may include benthic foraging in shallower depths. Since diving depths for some species are much better known than others, there may well be more overlap in forag- ing strata than suggested in Table 16-12. In general, how- ever, those species feeding on the surface (to 0.5m) include albatrosses, northern fulmar, storm petrels, gulls, kittiwakes, terns, and phalaropes. The shallow divers include the shear- waters. Cormorants and the smaller alcids appear to forage regularly to at least 40 m, either in mid-water or to the bot- tom, while murres and puffins are deep-diving pelagic for- agers. Common murres have been caught in crab pots at 1 25 m at Kodiak Island (Forsell and Gould 1981), and in tram- mel nets at 180 m in the Atlantic (Piatt and Nettleship 1 985). The latter study shows that the larger alcids routinely dive to far greater depths than has been generally believed. Marine Birds 507 Table 16-12. Known and estimated foraging depths of seabirds in the Gulf of Alaska. I'm <>>• Dep i n Strata in W ater Column" M [aximum MlD-WA 1 IK Demersal hi'iui \ l iik I)i VI l)l I'l II Rl II Kl \( 1 s Species 0-0.5 m 0.5-10 in 10 m (111) Black-footed albatross 1 3 0 (i 0 1 Laysan albatross 1 3 0 (i 0 1 Northern fulmar 1 3 i) (i 0 1 Mottled petrel 1 3? () 0 0 0.5? Sooty shearwater 3 1 3? (i 0 5 Brown, Bourne, and Wahl 1978 Short-tailed shearwater 3 1 2? 0 0 20 Morgan 1982 Fork-tailed storm-petrel 1 0 0 0 0 em's Leach's storm-petrel 1 (i i) 0 0 em's Double-crested cormorant (i 3? 3? 1 2? 20? Pelagic cormorant it 3? 2? 1 1 36 Schefferl942 Red-faced cormorant 0 3? 3? 1 1 20 -30? Red-necked phalarope 1 (i 0 0 0 em's Red phalarope 1 (i 0 I) 0 em's Glaucous-winged gull 1 3 0 0 0 1 Mew gull 1 3? 0 0 0 1? Black-legged kittiwake 1 3 0 (1 0 1-2 Bunt 1974 Arctic tern 1 0 (i 0 0 0.5? Aleutian tern 1 0 0 0 0 0.5? Common murre 0 2? 1 2? 3 180 Piatt and Nettleship 1985 Thick-billed murre 0 2? 1 2? 3 72 Tuck and Squires 1955 Pigeon guillemot 0 0? 2 1 1 23 -40 Sanger and Jones 1982; Kuletz 1983 Marbled murrelet 0 2? 1 3 3 40? t/ Bedard 1969b kittlitz's murrelet (1 2? 1 3 3 40? cf. Bedard 1 969b Ancient murrelet 0 2? 1 0 40? cf. Bedard 1969b Cassin's auklet 3b 2? 1 0 0 40? cf. Bedard 1969b Parakeet auklet 0 3? 2? 2 2 40 Bedard 1969b Crested auklet 0 3? 1 2 2 40 Bedard 1969b Rhinoceros auklet 0 1 2 3? 0 60 cf. Piatt and Nettleship 1985 Tufted puffin 0 2 2 3? 0 cf. Piatt and Nettleship 1985 Horned puffin 0 I 2 3? 0 cf. Piatt and Nettleship 1985 al = major. 2 = moderate. 3 = minor. 0 = none. b Sanger, personal observation. The diets of seabirds found in the Gulf of Alaska (Sanger 1983, in press) were examined in terms of the percent vol- ume (%V), the percent numbers (%N), and the percent fre- quency of occurrence (%FO) of the prey found in bird- stomach samples. These three values are combined into an Index of Relative Importance (IRI) (Pinkas, Oliphant, and Iverson 1971), and the percent of total IRI for all prey eaten by a bird species was used to further evaluate and compare the importance of various prey species. Bv combining these three parameters (i.e., IRI = [%V + %N]/%FO), the IRI attempts to overcome the shortcomings of using any of them alone to represent a predator's diet. Briefly, these are the shortcomings: • The differential in digestion rates for hard- or soft- bodied prey may distort their original relative vol- umes. • Percent numbers can make abundant small prey in the diet seem more important than sparse larger prey. • Percent frequency-of-occurrence ignores volume and numbers. We emphasize that the IRI is an index and not a measure of prey importance. Until a method for measuring prey ingestion rates (biomass eaten/time) is devised, however, the IRI is useful for estimating the relative importance of vari- ous prey and for comparing diets among predators. Details on %V, %N, and %FO of prey in the diets of the various seabird species can be found in Sanger (1983). Surface Feeders. Diet data are available for seven spe- cies of surface feeders (Table 16-13): 1) northern fulmar 2) fork-tailed storm-petrel 3) glaucous-winged gull 4) mew gull 5) black-legged kittiwake 6) arctic tern 7) Aleutian tern. Of these species, both the fulmar and the fork-tailed storm- petrel forage almost exclusively in oceanic and shelf-break 508 Biological Resources Table 16-13. Diets (% of total Index of Relative Importance for prey taxa) of surface-feeding seabirds in the Gulf of Alaska. (Adapted from Sanger 1983.) \RTE ALTE Bird Species-1 NOFU FTSP MEGU GWGU BLKI Adults Immatures Adults Immatures Main Habitats1' 0 o,s C C,S C,S C C Sample Size, n 46 14 68 13 328 36 32 14 48 Prey Taxon Cephalopods 96.3 60.7 0.1 Miscellaneous crustaceans' 0.7 6.7 0.2 0.6 0.1 2.2 Gammarid amphipods 84.8 Thysanoessa inermis 0.2 0.3 8.2 94.8 76.4 Euphausiidsd 22.3 0.1 2.2 0.8 2.2 0.1 Decapods4, 3.0 7.4 0.3 0.2 0.1 Mallolus villosus 0.1 2.6 61.3 1.4 64.7 3.2 44.3 Theragra chalcogramma 0.6 1.7 1.2 Hexagrammids 0.2 0.6 Ammodytes hexapterus 1.7 1.6 8.6 1.3 25.9 12.0 6.5 Miscellaneous Fishes' 2.1 4.2 3.5 92.0 10.0 0.2 2.1 4.6 37.7 Birdse 0.1 0.6 Other* 0.2 1.3 2.6 1.6 2.2 0.1 1.5 0.1 Index of Stomach Fullness, Max. (n)' 3.5(40) 1.2(11) 25.1(119) 3.9(13) 12.3(325) 14.9(31) 11.4(12) 8.5(15) 8.4(5) 1 NOFU = northern fulmar, FTSP = fork-tailed storm-petrel, GWGU = glaucous-winged gull, MEGU = mew gull, BLKI = black-legged kittiwake, ARTE = Arctic tern. ALTE = Aleutian Tern; bC = coastal, S = shelf, O = oceanic. ' Includes barnacles, copepods, isopods, hyperiid amphipods, and Paracallisoma alberti. d Includes unidentified euphausiids, Thysanoessa raschii, and T. spmifera. l' Includes unidentified decapods, pandalid shrimp, and unidentified shrimp. f Includes Clupea harengus, Hypomesus pretwsus, Gadus macrocephalus, Trichodim tnchodon, Blepsius cirrhosus, Zaprora silenius, unidentified osmerids, unidentified gadids, and unidentified cottids. « Fork-tailed storm-petrel in northern fulmar; ancient murrelet chicks in glaucous-winged gull. h Includes nereid polychaetes, gastropods, chitons, bivalves, sea urchins, and insects. 1 Weight of stomach contents/ (field body weight — weight of stomach contents) X 100; n represents sample size. habitats, while mew gulls and both species of terns are pri- marily coastal foragers. Glaucous-winged gulls and kit- tiwakes forage almost equally in coastal and shelf areas. Cephalopods dominated the diet of both the oceanic fulmars and the storm petrels, while capelin {Mallotus villosus) and Pacific sand lance were the mainstay prey of most of the coastal-foraging surface-feeders. Other studies have shown thatjellyfishes and their symbiotic hyperiid amphipods may be locally common in the diet of fulmars (Harrison 1983) and that larval capelin and the gammarid amphipod Paracallisoma alberti are common prey brought by parent fork-tailed storm-petrels to their nestlings at the Barren Islands (P.D. Boersma, University of Washington, pers. comm., 1984). The euphausiid Thysanoessa inermis was especially impor- tant to adults of both Arctic and Aleutian terns. In contrast, chicks of both species fed exclusively on fish brought by their parents (Table 16-13). The diets of nestling black- legged kittiwakes (Sanger 1983) were made up of quantities of fish and euphausiids, while T. inermis was important to adult birds in early summer (Table 16-13) (see also Krasnow and Sanger 1982). Glaucous-winged gulls had one of the most varied diets of all seabirds in the Gulf, although fish still constituted over 90% of the total IRI (Table 16-13). Maximum values for the Indices of Stomach Fullness (ISF) (the percent of body weight accounted for by the weight of the stomach contents), are shown at the bottom of Table 16-13. These values are assumed to represent the amount of food in the most recent meal. Values for each spe- cies ranged as high as 12% for kittiwakes, 15% for Arctic terns, and 25% for glaucous-winged gulls. The meaning of these data is speculative, but a value as high as 25% may indicate gorging instead of frequent consumption of smaller meals. Shallow Divers. The diets of two species of shallow div- ers— the sooty and the short-tailed shearwaters — are shown in Table 16-14. The shearwaters forage mainly over the shelf where Mallotus villosus (capelin) stood out as important prey for both species. Cephalopods were eaten by both of these species, although they were of moderate importance in the diet of only sooty shearwaters — the more oceanic species of the two (Table 16-14). The low volume of cephalopods found in sooty shearwaters (2%) was mainly accounted for by beaks. Euphausiids were particularly important in the diet of short-tailed shearwaters. As in the case of the surface feeders, maximum ISF values for the shearwaters tended to be high (Table 16-14), indicat- ing gorging instead of smaller meals eaten more often. Coastal Divers. This group includes (Table 16-15): • the pelagic cormorant • the pigeon guillemot • marbled and Kittlitz's murrelets • parakeet and crested auklets. Marine Birds 509 Table 16-14. Diets (r( of total Index of Relative Importance for prey taxa) of shallow-diving seabirds in the Gulf of Alaska. (Adapted from Sanger 1983.) Short- T \ii i d Bird Species Soon Sill \R\\ AIER Shearwater Main Habitats Shelf, 0< eank Shelf Sample Size, n 187 228 Prey Taxon Cephalopods11 26.6 2.0 Miscellaneous crustaceans1' 0.2 0.1 F.uphausiidsc 1.5 72.4 Mallotus villosus 68.5 21.8 I h eragra ch a Icogra mm a 0.1 A m m odytes h exapterus 1.3 0.2 Miscellaneous fishes'1 1.9 1.0 Other 0.1 1.8 Index of Stomach Fullness, Max.(n)' 16.6(181) 20.0(215) • Includes gonatid squids. Onychoteuthis borealijaponit us. h Includes ralanoid copepods, Paracallisoma alberti, gammarid amphipods, hyper- iid amphipods. and Trlmrsu.i rhieragnnus. ■ Mostlv Th\sanoessa sp.. but includes T. inermis, T. raschii, and T. spinifera. ■' Includes Stenobrruiiius nuitnochir, Microgadus proximus, and Trichodon trichodon. ' Includes nereid polvchaetes and gastropods. 1 Weight of stomach contents / (field body weight - weight of stomach contents) x 1 00; n represents sample size. The presence of demersal and benthic prey such as gas- tropods, mollusks, gammarid amphipods, mysids, and a variety of decapods (depending on bird species) attests to varying degrees of benthic foraging by all species in tins group. However, it seems likely that murrelets and auklets forage primarily within the water column (fable 16-12; see below). The pigeon guillemot had the most generalized diet ol the group (or of any of the seabird species considered in ibis chapter), eating mostly benthic prey. Prey included at least 12 invertebrate species and seven fish species (Table 16-15). Kuletz (1983) showed that breeding guillemots in Prince William Sound ate mostly fish, with some birds specializing on sand lance {Ammodytes hexapterus), while others spe- cialized on benthic species even when sand lance were abun- dant closer to nest sites. Among the four smaller alcids in this group, marbled and Kittlitz's murrelets both ate a variety of invertebrates and fishes, although capelin and sand lance were the main prey (Table 16-15). Both species included mysids and euphausiids in their diets, with the latter eaten more by Kittlitz's than by marbled murrelets. In general, Kittlitz's murrelets appear to eat more crustaceans and forage closer to shore, while mar- bled murrelets forage across a broader range of habitats and eat mostly fish (Sanger, in press). Both the parakeet and the crested auklets ate pelagic and demersal prey. The parakeet auklet's diet was almost equally divided between crustaceans and fish, while crested auklets ate crustaceans exclusively, particularly Acanthomysis mysids Table 16-15. Diets (% of total Index of Relative Importance for prey taxa) of coastal diving seabirds in the Gulf of Alaska. (Adapted from Sanger 1983.) Bird Speciesa Sample Size (n) PECO PIGU MAMU KIMU PAAU CRAL 16 64 158 16 13 25 Prey Taxon Miscellaneous crustaceans1' Hvperiid amphipods Acanthomysis spp. Thxsanoessa inermis L nidentified euphausiids" Hippolvtid shrimps Pandalid shrimps Decapods Mallotus villosus Theragra chalcogramma Trichodon trichodon Cottidae Stichacidae Ammodytes hexapterus Miscellaneous fishes'1 Other* Index of Stomach Fullness, Max.(n)1 0.2 1.3 1.4 2.1 3.0 0.4 32.7 1.8 13.0 0.6 4.8 0.9 0.4 1.5 85.8 10.1 39.9 0.2 1.3 9.4 3.8 15.2 1.5 9.1 4.7(12) 5.1(68) 0.1 47.9 0.1 0.3 21.3 14.0 0.2 8.6(156) 1.8 1.7 3.6 67.7 1.8(14) 46.5 12.1 41.4 1.1(14) 24.1 5.0 42.6 28.2 3.2(22) 1 PKCO = pelagic cormorant. PIGU = pigeon guillemot, MAMU = marbled murrelet, KIMU = Kittlitz's murrelet. PAAf = parakeet auklet. CRAU = crested auklet. '' Includes unidentified gammarids. unidentified mysids, Neomysis rayii, Spirontocaris spp.. Lebbeus spp.. and eualid shrimps. 1 MostI) Thysanorssa sp., 7". raschu. and / spinifera, (l Includes Clupea harengus, unidentified osmerids. unidentified gadids. Phulis sp.. and unidentified pleuronectids. ' Includes polvchaetes. echinoids, gastropods, bivalves, and cephalopods. 1 Weight ol stomach con tents / 1 field bodv weight — weight ol stomal h contents) x 100 ; n represents sample- si/e. 510 Biological Resources and the euphausiid Thysanoessa inermis. Mysids may occur within the water column at night, but they are generally demersal in daylight (Mauchline 1980) when the auklets were collected. This observation — and the similar presence of demersal crustaceans in the diets of these auklets in the northern Bering Sea (Bedard 1969b) — suggests that both species regularly forage near the bottom when water depth is shallow enough. However, it is unknown how important this mode of feeding is when compared with foraging within the water column. Maximum ISF values were generally low for all coastal foragers. Values ranged from 1% for parakeet auklets to 9% for marbled murrelets indicating the frequent consumption of small meals as opposed to sporadic gorging. Pelagic Midwater- and Deep-divers. Seven species of alcids mav be placed in this category: 1 ) common murre 2) thick-billed murre 3) ancient murrelet 4) Cassin's auklet 5) rhinoceros auklet 6) horned puffin 7) tufted puffin. Common murres are abundant in coastal areas in winter (Forsell and Gould 1981), but in summer this species forages mainly over the shelf, whereas thick-billed murres forage over both the shelf and in oceanic waters (Table 16-16). The ability of murres to descend to depths of 180 m (and proba- bly deeper), and to forage extensively on the bottom (Piatt and Nettleship 1985), allows them to capture prey from a wide variety of mid-water and benthic habitats (Table 16-12). Although 70% of the 12,243 common murres stud- ied by Piatt and Nettleship (1985) were observed in gill nets within 30 m of the surface, 4% (450) were found at 70- and 80-m depths, suggesting a greater amount of deep foraging by these species than was previously suspected. Ancient murrelets and Cassin's auklets forage both in shelf and in coastal habitats, but are apparently restricted to shallower foraging depths. There are no definite diving-depth records for these species, although it seems likely that they should be able to forage to at least 40 m as do other small alcids (Bedard 1969b). Sealy (1975b) observed that ancient murrelets in British Columbia foraged in water depths of at least 50 m, although their deepest foraging depths are unknown. In the present study, mysids made up a small portion of the ancient murrelet's diet (Table 16-16), suggesting occasional benthic foraging (Mauchline 1980; see above). Table 16-16. Diets (% of total Index of Relative Importance for prey taxa) of pelagic midwater- and deep-diving seabirds in the Gulf of Alaska. (Adapted from Sanger 1983.) Bird Species3 Main Habitats'3 Sample Size (n) COMU S, C 251 TBMU s,o 64 ANMU S, C 18 CAAU S 8 RHAU, ad C,S 21 RHAU, C,S 25 IMM HOPU C 54 TUPU.AD C,S 440 TUPU.IMM C,S 80 Prey Taxon Cephalopodsc Miscellaneous crustaceans 0.1 73.8 0.2 1.1 1.2 0.4 1.2 0.2 7.8 0.1 Calanoid copepods Neomysis rayii Hyperiid amphipods Thysanoessa inermis 1.6 6.4 8.7 0.2 75.1 76.7 Unidentified euphausiidsd 1.6 0.2 2.3 3.5 0.5 11.2 Decapodse Clupea harengus Mallotus villosus 1.0 35.9 1.1 3.1 0.4 14.0 27.9 32.8 0.4 61.5 74.3 64.9 Theragra chalcogramma Cololabis saira 11.7 2.3 1.2 1.5 0.1 1.1 0.1 0.6 1.5 Sebastes spp. 4.0 1.7 Hexagrammus spp. Ammodytes hexapterus Miscellaneous fishesf 23.9 14.6 1.4 9.5 20.1 4.6 9.8 56.8 1.0 61.6 1.2 16.2 19.8 5.4 0.7 33.2 0.4 Others 0.2 0.1 0.1 0.5 0.1 0.2 Index of Stomach Fullness, Max.(n)h 8.1(254) 8.9(42) 4.8(16) - 14.5(21) 10.7(65) 16.1(423) 8.5(35) 3 COMU = common murre, TBMU = thick-billed murre, ANMU = ancient murrelet, CAAU = Cassin's auklet. RHAU = rhinoceros auklet, HOPU = horned puffin, TUPU = tufted puffin, AD = adult, IMM = immature. bC = coastal, S = shelf, O = oceanic. ' Includes gonatid squid and unidentified. d Mostly Thysanoessa spp., plus T. inermis, T raschii, and T. spinifera. c Mostly pandalid shrimp and crangonid shrimp. 1 Includes Clupea harengus, unidentified osmerids, unidentified gadids, Microgadus proximus, Trichodon trkhodon, and Lumpenus sp. R Includes nereid polychaetes, gammarid amphipods, or insects. h Weight of stomach contents / (field body weight - weight of stomach contents) * 100; n represents sample size. Marine Birds 511 The foraging depths of the three puffins are largely a matter of speculation, although puffins appear to feed mainly within the water column (Table 10-12). Presumably, they can descend to at least the 60-m depths common to the Atlantic puffin (Fratercula arctica) (Piatt and Nettleship 1985). The nearly exclusive presence of epipelagic fish in the diet of rhinoceros auklets (Vermeer and Westrheim 1984; Sanger 1983) suggests that they may forage largely in the upper layers. In contrast, the occasional presence of epibenthic prey such as gammarid amphipods, mysids, and pandalid shrimp found in the stomachs of horned and tufted puffins that were collected in daylight (Table 16-16), indicates that they occasionally forage near the bottom. The breadth of the foraging habitats that are available to the murres is reflected in the variety of both invertebrates and fish in their diet (Table 16-16). Common murres ate at least 15 species of prey, including eight invertebrates and seven fish, and the thick-billed murre ate nine species of prey (fable 16-16). Capelin and sand lance were predomi- nant in the diet of common murres, although pandalid shrimps and mysids were their main food during one win- ter in Kachemak Bay (G.A. Sanger, U.S. Fish and Wildlife Sen ice, unpubl. data). Cephalopods were the main prey of thick-billed murres. Both of the small alcids in this group rely heavily on crus- taceans (Table 16-14). In general, ancient murrelets and Cas- sin's auklets appear to specialize on planktonic crustaceans, with ancient murrelets eating mainly euphausiids (77% of total IRI) and Cassin's auklets eating mainly copepods (77% of total IRI) (see also Sanger, in press; Vermeer 1981). Max- imum ISF values for these divers (Tables 16-13 through 16-16) were generally intermediate compared with the other species, ranging from 5% for the ancient murrelet to 16% for the tufted puffin. Both rhinoceros auklets and horned puffins forage mainly in coastal waters, while tufted puffins forage almost equally over the shelf and in neritic waters. The diet of nes- tling rhinoceros auklets (Table 16-16) observed at Forrester Island in southeastern Alaska (Fig. 16-1) included mainly Pacific herring (Clupea harengus) and Pacific sand lance, although at least six other fish species were also in the diet. Sand lance were also an important food of nestling rhi- noceros auklets on Middleton Island in the northern Gulf (Hatch 1984). In a recent study in British Columbia, rhi- noceros auklets were shown to eat a wide variety offish (Ver- meer and Westrheim 1984). In general, surface feeders and shallow divers tended to have relatively high ISFs (average of —14%, with maxima of 16-25%), while ISF's in the demersal/benthic feeders were much lower (average —4%, with maximum of 9%). These values may indicate a relatively patchy occurrence of prey for near-surface foragers, and their need to gorge when prey is available. The low values for benthic feeders may imply a steadier food supply and suggest that these birds eat smaller, more frequent meals than the surface feeders. Trophic Levels for Seabirds and Their Prey Trophic levels (TL's) for prey found in the diets of 19 Gulf of Alaska seabird species were estimated and then used to graph the TL spectra of their diets (Sanger, in press). The average TL's of the pooled diet of each species was calcu- lated by weighting the TL of each prey with a relative impor- tance in the diet (percent of total IRI for all prey). This method is nearly identical to one used by Mearns, Young, Olson, and Schafer (1981) to examine trophic levels of prey in a fish community off California. Details of this concept as applied to seabirds in the Gulf of Alaska are given elsewhere (Sanger, in press). Although this approach relies heavily on untested assumptions, it allows insights into how different bird spe- cies relate trophically and into how the bird community could relate to lower trophic levels in the ecosystem. The average prey trophic levels ranged from 2.2 in the case of Cassin's auklets — making them nearly primary carnivores, to 4.0 in the case of northern fulmars — making them third- order carnivores (Table 16-17). Other small alcids not included in the discussion (least, whiskered, and crested auklets) have diets consisting largely of calanoid copepods, making them the closest to primary carnivores of all sea- birds in the Gulf. The albatrosses, with their diets mostly of large squid, probably have the highest trophic levels. Biomass of Seabirds and Their Prey First-order approximations of average summer biomass for seabirds in the Gulf are —33,000 mt over the shelf, in bays, and in fjords; and —12,000 mt in oceanic regions. Table 16-17. Summary of trophic levels for 19 species of seabirds in the Gulf of Alaska, ranked from highest to lowest. Means are calcualted from the estimated trophic levels of each prey taxon in the diet, weighted by % volume of the taxon in the diet (from Sanger 1986b). Trophic Levels Species For Birds' Prey Mean for Sample Weighted Bird Size (n) Mean Min. Max. Species Northern fulmar 43 4.0 2.0 4.0 5.0 Thick-billed murre 38 3.8 2.5 4.0 4.8 Sooty shearwater 178 3.3 2.5 4.0 4.3 Rhinoceros auklet 16 3.1 3.0 4.0 4.1 Tufted puffin 364 3.1 2.5 4.0 4.1 Common murre 166 3.1 2.5 3.2 4.1 Pigeon guillemot 58 3.1 2.0 3.5 4.1 Black-legged kittiwake 373 3.0 2.0 3.5' 4.0 Glaucous-winged gull 66 3.0 2.0 3.1 4.0 Horned puffin 40 3.0 2.5 4.0 4.0 Pelagic cormorant 16 2.9 2.0 3.5 3.9 Marbled murrelet 129 2.8 2.5 3.1 3.8 Fork-tailed storm-petrel 8 2.8 2.0 3.0 3.8 Kittlitz's murrelet 15 2.8 2.5 3.0 3.8 Ancient murrelet 15 2.7 2.5 3.5 3.7 Short-tailed shearwater 201 2.6 2.5 4.0 3.6 Aleutian tern 13 2.6 2.0 3.5 3.6 Arctic tern 34 2.5 2.5 3.1 3.5 Cassin's auklet 8 2.2 2.0 3.0 3.2 II. 4.0, prev in diet in trace amount. 512 Biological Resources These figures are based on population estimates given in Table 16-18. Since the metabolic rate of a bird is inversely propor- tional to its body weight, smaller species such as storm- petrels and auklets eat proportionally more than larger spe- cies such as shearwaters. We know that short-tailed shear- waters, (which average —634 g in the Gulf) can eat at least 20% of their body weight per day (Table 16-14). To estimate the biomass of prey consumed by Gulf sea- birds we followed the same procedure as for waterfowl; that is, we assumed that birds of less than 200 g eat the equivalent of 40% of their body weight per day; birds weighing between 200 and 600 geat 30% of their weight per day; and birds weighing over 600 g eat 20% of their weight per day. Our results (Table 16-19) indicate that the Gulfs pelagic bird community eats an average of ~ 7,000 mtid over the conti- nental shelf, and 2,500 mt/d in oceanic waters. These values convert to —18 kg/km2/d over the shelf and 2.4 kg/km2/d in oceanic waters. Shearwaters account for 61% of the prey consumed over the shelf while murres and tufted puffins account for another 25 percent. In oceanic waters, shear- waters eat an estimated 65% of the prey biomass, and murres and puffins eat another 19 percent. Seabird/Fisheries Interactions Although Hunt, Burgeson, and Sanger (1981) docu- mented the heavy use of walleye pollock (Theragra chal- cogramma) by seabirds in the Bering Sea, our feeding studies suggest that birds are far less dependent on currently har- vested species of fish and shellfish in the Gulf of Alaska. Although those commercial species eaten by the birds we studied included Pacific herring, pollock, Pacific cod (Gadus macrocephalus), salmon {Oncorhynchus spp.), sablefish {Anoplopoma fimbria), razor clams, and pandalid shrimps, their cumulative IRI's were generally low (Sanger 1983). However, we made no attempt to sample birds at those times and in those areas where there were concentrations of com- mercial species of the sizes eaten by birds. The scarcity of both juvenile herring and salmon in the birds' diets is per- plexing. The relatively new, but rapidly expanding pollock fishery in the Gulf may possibly affect bird populations. However, a greater immediate consequence to seabirds in the Gulf would be the development of fisheries for Pacific sand lance and capelin. A capelin fishery may already be imminent. The Icelandic Ministry of Fisheries has expressed an interest in cooperative research with the United States on capelin stocks in Alaskan waters and small experimental fisheries have recently occurred in Bristol Bay (J.M. Nelson, U.S. Fish and Wildlife Service, pers. comm., 1985). Discussion Primary production by phytoplankton forms the basis of most marine food chains (Steele 1974). While seabirds are two or more trophic levels removed from primary pro- Table 16-18. Estimated populations of seabirds in the Gulf of Alaska in summer (June to August). (Adapted from Gould et al. 1982.) Shelf, Shelf Break, and Bays Oceanic Total (382 x 103km2) (1,025 x 103ki Birds 11-) Correction Birds Birds Species Factor" (x 103) % (x 103) % (x 103) % Black-footed albatross 1.0 11 0.1 184 1.0 195 0.3 Northern fulmar 1.3 1.239 2.6 2,276 12.0 3,515 5.2 Mottled petrel 1.0 17 0.1 543 2.8 560 0.8 Sooty shearwater 1.0 12,696 26.5 7,920 41.7 20,616 30.8 Short-tailed shearwater 1.0 13,775 28.8 102 0.5 13,877 20.8 Storm-petrels 1.5 1,519 3.2 4,134 21.8 5,653 8.4 Cormorants 2.0 122 0.2 0 0 122 0.2 Phalaropes 1.0 464 1.0 41 0.2 505 0.8 Jaegers 2.0 182 0.4 369 1.9 551 0.8 Glaucous-winged gull 2.0 992 1.9 61 0.3 983 1.5 Black-legged kittiwake 2.0 2,768 5.8 758 4.0 3,526 5.3 Terns 2.0 385 0.8 328 1.7 713 1.1 Murres 2.5 3,815 8.0 1,050 5.5 4,865 7.3 Pigeon guillemot 1.5 140 0.3 0 0 140 0.2 Brach\ramphus murrelets 1.5 486 1.0 0 0 486 0.7 Ancient murrelet 1.5 252 0.5 15 0.1 267 0.4 Cassin's auklet 1.5 1,397 2.9 184 1.0 1,581 2.4 Rhinoceros aukletb - 139 0.3 61 0.3 200 0.3 Tufted puffin 1.5 5,651 11.8 953 5.0 6,604 9.9 Horned puffin 1.5 1.876 3.9 15 0.1 1,891 2.8 Total 47,857 18,994 66,851 Multiplied by the population estimate to account for birds on colonies. 1 Population estimate adapted from Sov\ Is el al. (1978) for coastal birds and from Gould el al. (1982) for oceanic birds. Makini Bikds 513 Table 16-19. Estimates of biomass of seabirds and prey ingestion by seabirds in the Gulf of Alaska in summer (June to August). Shelf, Slope, and Bays < )( i \\K Birds Pre* Biomass Eaten Birds Prf.y Biomass Eaten Species Mean Estimated Ingestion Estimated Weighi Biomass Rates'" % Biomass (mt) ml/cl kg/km2d % (g) (mt) nu/d kg/km'-'d BFALb 3.090 34 20 7 <0.1 0.1 569 114 0.1 4.6 NOFU 610 756 20 151 0.4 2.2 1.388 278 0.3 11.3 MOPE 350 6 30 2 <0.1 <0.1 190 57 0.1 2.3 SOSH 842 10,690 20 2,138 5.6 30.8 6,669 1,334 1.3 54.3 STSH 634 8,773 20 1,747 4.6 25.2 65 13 0.1 0.5 STPE 50 76 40 30 0.1 0.4 207 83 0.1 3.4 CORM 1 ,850 226 20 45 0.1 0.6 0 0 0 0 PHAL 45 21 40 8 0.1 0.1 2 1 <0.1 <0.1 JAEG 500 91 30 27 0.1 0.4 184 55 /'<»>0 — ^ <=>? S^130 160 150 140 Figure 17-1. Summer sightings of fin and humpback whales in the Gulf of Alaska. (Modified from Consiglieri and Braham 1982.) (1966) that fin whales are divided into eastern and western stocks. Both stocks migrate north and south, although the Gulf of Alaska stock stays closer to the North American coast- line (Mitchell 1978). The historical population of North Pacific fin whales was estimated at between 42,000 and 45,000 animals (Tillman 1975). The North Pacific stock is presently estimated at 17,000 whales (Ohsumi and Wada 1974). Consiglieri and Braham (1982) estimated that the population of fin whales from the Gulf of Alaska to the Bering Sea probably does not exceed 10,000 whales. Rice and Wolman (1981) estimated that 159 fin whales were present in an area of 76,117 mi2 in the north central Gulf of Alaska. Although the International Whaling Commission granted protected-stock status to North Pacific fin whales in 1976, Allen (1974) suggested that it may take as long as 25 years for the population to recover to 90% of its original size. Calves are born about 6.5 m in length, and lactation lasts until they double in size — which usually takes about 6 months (Ohsumi, Nishiwaki, and Hibiya 1958). Females are generally larger than males and take longer to reach sexual maturity. Sexual maturity occurs at about 18.6 m in females and at 17.5 m in males (Rice 1963). Physical maturity is reached at about 20 m for females and 19 m for males (Rice 1963; Ohsumi et al. 1958). The largest female recorded in the North Pacific was 24.4 m, and the largest male was 23.8 m (Tomilin 1957). Fin whales have a breeding cycle that varies from bien- nial to triennial (Mitchell 1978). Gestation lasts between 11 and 12 months (Ohsumi et al. 1958). The breeding season extends from September through June, peaking in mid- winter (from November through January). Births occur over a similarly protracted period. Both the abundance and the location of prey for the fin whales are related to seasonal planktonic blooms in the Gulf. Kawamura (1982) reported that fin whales may switch prey species from euphausiids (abundant in late spring and early summer) to copepods (most abundant in summer and fall). Other less-used prey include fish and cephalopods, which are consumed more during the summer than during the spring (Kawamura 1982). Calanoid copepods and several species of euphausiids are among the most important prey for the fin whales (Kawamura 1980; Nemoto 1957; Nemoto 1959; and Nemoto and Kasuya 1965). Important species include Calanus cristatus, C. plumchrus, C. finmarchicus, and Metridia lucens. These species dwell in warmer surface waters, as does the euphausiid Thysanoessa spinifera, which is also heavily used by fin whales (Kawamura 1980). T. spinifera is a dominant neritic species of euphausiid found in the Gulf (Kawamura 1980). It is restricted to depths of 100 m or less in the shallower, nearshore waters. Other euphausiids preyed upon by fin whales include Euphausia pacifica, Thysanoessa longipes, and 71 inermis, which migrate ver- tically in the water column, generally rising at night (Barnes 1974; Nemoto and Kasuya 1965). Lockyer (1976a) estimated that fin whales feed twice daily for an average daily consumption rate of 1,000 to 1,500 kilo- grams. Nemoto (1959) reported that one 17.5-m male fin whale had 759 kg offish in its stomach. Sei Whale Sei whales (Balaenoptera borealis) are large balaenopterids which grow to 16 m in length (rarely longer) in the North Pacific (Leatherwood et al. 1982). Lengths of physically mature females captured off California averaged 15.6 m; males averaged 13.7 meters. At birth, sei whales are between 4.3 and 5.3 m long (Leatherwood et al. 1982; Tomilin 1957; and Masaki 1976). Sei whales are dark gray or bluish gray on the back and sides and on the posterior portion of the ven- tral surface. On the abdomen, there is a region of grayish white that is almost always confined to the area of the ventral grooves. The right lower lip and mouth cavity are uniformly 532 Biological Resources gray, unlike on the fin whale. The body often has a 'gal- vanized' appearance due to scars inflicted either by lampreys {Lampetra sp.) or by parasitic copepods (Leather- wood et al. 1982). Sei whales are seasonal residents of the Gulf. They are generally most abundant in the spring (Consiglieri and Braham 1982), although they apparently form local con- centrations in summer in certain areas. Masaki (1976) stated that in spring sei whales migrate from the southern breed- ing and calving areas (20° to 30°N) to the northern feeding grounds. From May through August, the areas of greatest sei whale densities are in the northwestern and the north- eastern parts of the Gulf (Masaki 1976). Sei whales are found throughout the Gulf, although there may be local seasonal concentrations which can change from year to year as the abundance of copepods and eupha- usiids fluctuates (Nemoto 1959). Sei whales apparently leave the Gulf in late summer and by September, most have departed for southern waters (Masaki 1976). Apparently few sei whales remain in the Gulf during winter, although Consiglieri and Braham (1982) reported one sighting of five animals near the Fairweather grounds during winter months. Rice (1974) conjectured that sei whales winter off- shore. Masaki (1976) indicated that sei whales are distributed between 20° and 30°\ duringjanuary and February. Heavy commercial exploitation of sei whales did not take place in the North Pacific until 1963, when other, more desirable species became depleted. Tillman (1977) estimated that prior to 1963, the number of sei whales in the North Pacific was on the order of 42,000 animals. By 1966, the sei whale population in the North Pacific had been designated a protected stock by the International Whaling Commis- sion. Tillman (1977) estimated the North Pacific population at 8,600 sei whales. Breeding and calving occur between October and March when sei whales are in warmer, southern waters. Calving peaks in November and breeding peaks in December (Masaki 1976). Both sexes are thought to attain sexual matu- rity by seven years; gestation lasts about 10.5 months, with calves born every other year (Masaki 1976). The diet of sei whales in the North Pacific has been stud- ied by examination of stomach contents of whales taken in the commercial fishery. Kawamura (1980) summarized the examination results for 12,000 whales and found that the most important food was copepods (primarily Calanus plumchrus), which accounted for 83% of the diet. Eupha- usiids made up 13% of the diet, fishes made up 3%, and squids accounted for 1 percent. Tomlin (1957) and Klumov (1963) found that fishes eaten by sei whales include: • smelt (Osmeridae) • sand lance (Ammodytes hexapterus) • arctic cod {Boreogadus saida) • rockfishes (Sebastes sp.) • greenlings (Hexagrammos sp.) • pollock (Theragra chakogramma) • capelin (Mallotus villosus) • sardines (Sardinops sajax). Little information is available on the food requirements of sei whales. Lockyer (1976a) estimated the average stomach-content weight for sei whales at 180 to 230 kg for those whales 13 to 17 m in length. Sei whales consume 1.5 x 10;5 kg of food per day, according to Lockyer (1976a). Humpback Whale The humpback whale (Megaptera novaengliae) is the only living representative of the genus Megaptera and a member of the family Balaenopteridae (rorqual). Newborn calves are between 4.5 and 5.0 m long and females (which are larger than males) reach lengths of 16 m as adults; sexual maturity is reached by both at about 11 to 12 m (Leatherwood et al. 1982). Body color is generally gray or black with some white on the ventral surface. The flippers are unusually long (one-fourth to one-third the total body length) and are usually white underneath. Humpbacks have between 14 and 22 throat or ventral grooves which extend to the navel. The baleen is short (seldom more than 80 cm) and numbers between 270 and 400 plates (Leatherwood et al. 1982). Humpbacks are generally found in coastal areas or near oceanic islands (Berzin and Rovnin 1966; Leatherwood et al. 1982). They appear to have a strong affinity for nearshore waters, particularly for highly productive fjord-like areas such as southeastern Alaska and Prince William Sound. Those few sightings from the central Gulf of Alaska were probably of animals in transit (Consiglieri and Braham 1982). Humpbacks move seasonally from the warm, south- ern waters where they winter to the rich, productive waters of the north where they summer. Humpbacks from the North Pacific winter in three loca- tions: 1) off the Hawaiian Islands, 2) off the Mexican coast, and 3) near the Ryuko, Bonin, and Marianas Islands and Taiwan in the Western Pacific (Berzin and Rovnin 1966; Wolman 1978). Their northward migration begins in March and April, and they arrive in southeastern Alaska in April and May. They remain in the Gulf through the summer and fall and begin their southward migration in November. Some humpbacks apparently spend the winter in south- eastern Alaska. There have been a few sightings in the Gulf in February (Consiglieri and Braham 1982), but most whales move further south. In summer, humpbacks can generally be found in three nearshore areas of the Gulf: 1) near Kodiak Island, 2) in Prince William Sound, and 3) in southeastern Alaska (see Fig. 17-1). Offshore, humpbacks are typically sighted off Kodiak Island, Cape St. Elias, Yakutat, and the Fairweather grounds (Consiglieri and Braham 1982). In 1966, the International Whaling Commission pro- tected humpbacks from commercial whaling, after more than 50 years of overexploitation of this species. Prior to 1905, the North Pacific population of hump backs was esti- mated at 15,000 (Wolman 1978). Over 28,000 humpbacks were killed between 1904 and 1965. A recent estimate places the North Pacific population at 1,200 whales (Johnson and Wolman 1984). According to Consiglieri and Braham (1982), this gives the humpback whale the unenviable status of being the second-most depleted whale in the North Pacific, after the North Pacific right whale. Makini Mammals 533 Hall and Johnson (1978) estimated that there were 50 humpbacks ill Prince William Sound, while Rice and VVolman (1981) extrapolated their counts in the Gulf to pro- vide an estimate of 306 whales. Von Ziegesar and Matkin (1985) obtained photographs of 96 whales in Prince William Sound. Baker, Herman, Perry, Lawton, Straley, and Straley (1985) estimated that there are between 270 and 373 humpbacks in southeastern Alaska. Breeding for the humpback takes place in their wintering areas during the period from October to April, with peak activity occurring in December. Gestation lasts 11 to 11.5 months, and lactation continues for an additional 11 months (Tomilin 1957; Rice 1963), resulting in a two-year reproduc- tive cycle. Chittleborough (1960) estimated that a female humpback whale may live for 47 years and give birth to as many as 15 calves. Wolman (1978) assumed that humpbacks, like other ror- quals, feed heavily during summer while they are in high lat- itudes and then live off the energy stored in their body fat during the winter. However, this assumption has not been tested (Morris et al. 1983; Wolman 1978). Nemoto (1959) found that humpback foods consisted primarily offish and euphausiids. Important fishes were herring (Clupea harengus pallasii), capelin, saury (Cololabis saira), pollock, and Pacific mackerel (Scomber japonicus). Their principal prey varied with location. Kreiger and Wing (1985) suggested that in Glacier Bay, humpbacks switched from their primary diet of euphausiids in the mid-1970s to a diet in the early 1980s that consisted primarily offish. However, they also found that most of the whales they sighted in Stephens Passage, Frederick Sound, and Chatham Strait were feeding on euphausiids in 1984. Humpbacks have been observed using several feeding methods. In southeastern Alaska, they use a technique called "lunge feeding. During lunge feeding, they plough through prey concentrations with their mouths open. During 'flick feeding', they move their flukes forward at the surface and then dive through the concentrated food. In a third feeding method, they produce a 'bubble net' by swimming in a circle below agitated prey (such as a school of herring) while releasing air bubbles from their blowhole. The bubbles rise to the surface, forming a curtain; this presumably frightens the prey and concentrates them in the center of the rising ring of bubbles. The humpback then rises swiftly through the prey with its mouth open, engulfing the food (Ingebrightsen 1929; Jurasz andjurasz 1979). The only information available on the food amounts con- sumed by humpbacks is from Tomilin (1957) who reported on the prey he found in two stomachs that contained large volumes of food. He found 500 kg of Thysanoessa longipes in the stomach of a 14.3 m female and 600 kg of saffron cod in the stomach of a male of unspecified length. Gray Whales Gray whales (Eschrirhtius robust us) are morphologically distinct from other baleen whales (Barnes and McLeod 1984). Apparently, the incomplete fossil record does not provide any basis for understanding the evolutionary his- tory of gray whales. Their baleen is considered to be primi- tive because there are fewer plates and the plates are thicker than those of other balaenopterids (Barnes and Mcleod 1984). Gray whales grow to a maximum length of —14 m and typically weigh ~33 t (Leatherwood et al. 1982). They are strongly tapered at both ends, have a narrow, triangular head, have a slightly arched mouthline, and exhibit a low hump on their back. The skin is mottled gray due to both natural pigmentation and extensive scarring from barnacles (Leatherwood et al. 1982). The short, coarse baleen plates number between 138 and 180 per side and are colored yel- lowish-white to white. Gray whales migrate through the Gulf of Alaska on their way both to and from summer feeding grounds in the Bering and Chukchi Seas (Fig. 17-2). Generally, gray whales are found within 4 km of shore except when crossing the entrance to Prince William Sound or when going from Kodiak Island to the south side of the Alaska Peninsula (Rugh 1984). Rice and Wolman (1971) report that gray whales are seldom found in waters deeper than 180 meters. Pike (1962) suggested that gray whales use topographical clues for orientation. Their migratory routes may be most influenced by the availability and the composition of food (Braham 1984). Gray whales winter along the west coast of Baja Califor- nia, Mexico, and migrate the 9,000 to 14,000 km to the Bering and Chukchi Seas each spring. The migration route through the Gulf of Alaska is entirely coastal (Braham 1984). Animals segregate by sex and age during the migration, with single adults arriving first followed by pregnant females, subadults, postbreeding males, and finally by the cows with their calves (Rice and Wolman 1971). In 1977 and 1978, the migration past Cape St. Elias peaked during the third week of April (Cunningham and Stanford 1979). Generally, the migration through the Gulf of Alaska and into the Bering Sea is complete by the end of June or by early July (Braham 1984). Some whales remain south of the Bering Sea in summer (Pike 1962; Pike and MacAskie 1969; Rice and Wolman 1971; and Darling 1984). Summer distribution of gray whales in the Gulf of Alaska is not well documented. Consiglieri and Braham (1982) recorded sightings of gray whales at a variety of sites: 1) the south side of Kodiak Island, 2) in the Hinchinbrook Entrance to Prince William Sound, and 3) between Cape St. Elias and southeastern Alaska. All their sightings were in waters very near shore. These sightings may have been local feeding groups or may have been cows with their slower calves. The peak of the southbound migration in the Gulf lasted from late November to early December (Rugh 1984; Consigleiri and Braham 1982; and Rugh and Braham 1979). Most gray whales have left the Gulf by early January. The route of the southward migration is not as well understood as the route of northward migration; however, sightings have been made both nearshore and offshore in the fall and early winter. Braham (1984) suggested that the few sightings which have been made indicate that the whales follow a coastal route, although possibly farther offshore. 534 Biolocical Resources 130 60 General grav whale migratory route (approximate width 4km) Secondary route used bv low number of whales ^130 150 140 Figure 17-2. Generalized spring migratory route of gray whales through the Gulf of Alaska. Nineteenth-century commercial exploitation of gray whales was devastating to the population because it took place in die wintering lagoons where cows and calves were easily taken (Henderson 1984). Reilly (1981) estimated the original gray whale population at between 15,000 and 24,000; Henderson (1984), however, suggested that the pop- ulation did not exceed 15,000 when whaling began in the southern calving areas during 1845-1846. Approximately 4,000 whales still survived in 1874 — when nineteenth- century gray whaling in the calving lagoons effectively ended (Henderson 1984). Whaling on gray whales continued into the twentieth century. However, the emphasis was shifted to pelagic whal- ing. In 1966, commercial whaling on gray whales was termi- nated when they were designated a Protected Stock. In 1979, gray whales were redesignated a 'Sustained Management Stock', and currently a subsistence take is allocated to (or on the behalf of) the coastal Natives of the Soviet Union and the United States. The eastern North Pacific gray whale population appears to have recovered to near pre-nineteenth century exploita- tion levels and probably is now nearing the carrying capac- ity of its range (Reilly 1981). The most recent population esti- mate is between 13,000 and 17,000 whales (Reilly 1981, 1984). The population apparently grew at a rate of 2.5% annually between 1968 and 1980 (Reilly 1981). This stock has been con- sidered endangered by the United States; however, the National Marine Fisheries Service has initiated action to have the stock reclassified as threatened (S. Zimmerman, National Marine Fisheries Service, Juneau, AK., pers. comm., 1985). Female gray whales become sexually mature at lengths of between 11.7 m and 12 m, while males reach sexual maturity between 11.0 m and 11.1 m (Blokhin 1984; Rice and Wolman 1971). Calving occurs off Baja California duringjanuary and February, although some calves may be born in the Gulf (Consiglieri and Braham 1982). Estrus and conception occur in late November or in December (Rice and Wolman 1971) although sexual activity has been observed at other times of the year (Cunningham and Stanford 1979). Lactation con- tinues until August (Rice and Wolman 1971). Gray whales take two years to complete a reproductive cycle; a female may reproduce for nearly 40 years and produce as many as 12 calves (Consiglieri and Braham 1982; Rice and Wolman 1971). Generally, gray whales move to northern latitudes annually to take advantage of rich food resources. Some whales apparently linger along the coast to feed, rather than to complete the migration into the Bering Sea, while some feed at select locations along the route (Nerini 1984). Gray whales feed on several species of benthic amphipods in the Bering Sea and may also eat polychaetes, mysids, planktonic decapods, gastropods, and some bivalves. The extent to which these resources are used in the Gulf of Alaska has not been documented (Nerini 1984). Schooling fishes such as herring or capelin may be important during migration, since they are abundant near Kodiak Island and off south- eastern Alaska (Consiglieri and Braham 1982; Morris et al. 1983). Zimushko and Lenskaya (1970) estimated that a gray whale consumes ~ 300 kg of food per feeding. Lowry, Frost, Calkins, Swartzmann, and Hills (1982) assumed four feeding bouts per day, based both on their own observations of other baleen whales as well as on the field observations of Zimushko and Lenskaya (1970). They estimated a daily food consumption of 1,200 kg in the Bering and Chukchi Seas. We can only infer consumption amounts for the Gulf of Alaska because we have no feeding-rate estimates. The Gulf of Alaska is important to gray whales primarily as a migratory corridor, although some feeding and reproductive activity probably occur there. The Gulf is used by nearly the entire eastern gray whale stock as it moves along its route between the breeding and calving lagoons of Baja California and the rich feeding areas of the north. Marinf Mammals 535 Sperm Whale The sperm whale (Physeter macrocephalus) is the largest rep- resentative of the odontocetes or toothed whales and is clas- sified as endangered by the United States under the Endangered Species Act of 1973. According to Leatherwood et al. (1982), sperm whales are among the easiest of the large whales to identify because of the disproportionately large head. Much of the bulk of the head consists of the sper- maceti organ. The development of a spermaceti organ — which consists of an oil-filled structure that appears to have a role in controlling buoyancy — is a specialization peculiar to the physeterids (Gaskin 1982). The sperm whale's huge head accounts for one-fourth to one-third its total length; the blowhole, an S-shaped struc- ture, is located on the forward half of the head (Rice 1978c). The dorsal hump or fin is usually rounded at the peak, but is sometimes triangular shaped. It is located about two-thirds of the way back from the front of the head (Leatherwood et al. 1982). Sperm whales usually are dark brownish-gray with white areas on the belly, on the front of the head, and around the mouth. The sperm whale's mandible has about 25 teeth per side and can be as much as 1.5 m shorter than the snout (Rice 1978c; Leatherwood et al. 1982). Maxillary teeth are usually rudimentary, seldom erupting through the gums. Adult males can reach lengths of 17 m and average 15 meters. Adult females are generally smaller, rarely exceeding 12 m (Leatherwood et al. 1982). At birth, calves are about 3.5 to 5 m long and weigh about 1.0 * 10s kilograms. In the Gulf, sperm whales are found near the continental slope and in the deeper waters beyond (Smith 1980; Ohsumi 1980). According to Berzin (1970), sperm whales feed from mid-water depths to the ocean bottom. Sperm whales spend the winter months in more temper- ate waters of the North Pacific from the equator to approx- imately 40°N (Berzin 1970). Pike and MacAskie (1969) reported the appearance of sperm whales off the coast of British Columbia in spring, and the young (subadult) males remain there throughout the summer. The northern limit of the females' range appears to be the 15C isotherm (or 50°N) — well south of the Gulf of Alaska. Consequently, adult females and immatures (maternity schools) would be rare visitors to the Gulf. Apparently, the distribution of sperm whales shifts fur- ther offshore in summer, because Rice and Wolman (1981) sighted 36 individuals over deep water beyond the continen- tal shelf. Very few sperm whale sightings have been made in the Gulf of Alaska in autumn. However, Consiglieri and Braham (1982) and Pike and MacAskie (1969) thought that the sightings were consistent with other records that indi- cated a southward movement. Consiglieri and Braham (1982) reported one winter sighting in the Gulf when a single sperm whale was observed on the Fairweather grounds in 1979. Although sperm whales were continuously harvested for over three centuries, substantial numbers of animals were not taken prior to 1947 (Berzin 1970; Tillman 1976). Appar- ently, few sperm whales were taken from the Gulf of Alaska over the last several decades. Rice (1978c) estimated the sperm whale population in the North Pacific at 7.4 x 105 individuals. The eastern North Pacific population is cur- rently (1982) estimated at 1.74 x 105 whales (Gosho, Rice, and Brewick 1984). No estimate is available for the numbers of sperm whales that occur in the Gulf of Alaska. Sperm whales mate in waters south of the Gulf of Alaska in spring or early summer (Rice 1978c). Females reach maturity at about nine years (Ohsumi 1965; Lockyer 1976b). According to Gosho et al. (1984), puberty is prolonged in the males, beginning at about nine years of age and reaching completion when the testes are fully spermatogenic at about 20 years. Calves are born between June and October with peak calving activity occurring in August. The total gestation period is ~14 to 17 months (Best 1968; Ohsumi 1966), and lactation lasts from 12 to 24 months. With a reproductive cycle of between 3 and 6 years, sperm whales may have the lowest reproductive potential of any marine mammal (Gosho et al. 1984). Throughout the North Pacific, sperm whales eat mainly cephalopod mollusks — particularly squid of the family Gonatidae — and bottom-dwelling fish (Gosho et al. 1984; Kawakami 1980; Okutani and Nemoto 1964; and Rice 1963). They are noted for their ability to make prolonged, deep dives (Rice 1978c). Sperm whales have been reported to feed on bottom-dwelling sharks in water depths over 3,049 m off South Africa (Rice 1978c). In the Gulf of Alaska, Okutani and Nemoto (1964) found fish to be the predominant prey, but gave no species identification. The most commonly eaten fish include rockfishes, cod (Gadidae), skates (Rajidae), lan- cet fish (Alepisaurusferox), lumpfish (Cyclopteridae), and rat- tails (Coryphaenoides sp.) (Berzin 1959, 1970; Okutani and Nemoto 1964; and Kawakami 1980). Daily food consumption rates for sperm whales ranges from 2 to 4% of the total body weight (Lockyer 1976b; Kawakami 1980). In the North Pacific, two stocks of sperm whales are cur- rently recognized: the eastern and the western stocks (Best 1975; Harwood and Garrod 1980; Bannister and Mitchell 1980; and Gosho et al. 1984). The boundary between the two stocks runs through Amchitka Pass in the western Aleutians at 50°N, 180°W, then southeast to the Hawaiian Islands (20°N, 160 °W). Minke Whale The minke whale (Balaenoptera acutorostrata) is the small- est baleen whale in the Gulf. Its nicknames — 'little piked whale' or 'sharp-headed finner' — refer to its narrow head and pointed rostrum. The rostrum is divided sagitally by a distinctive ridge running forward from the blowhole (Leath- erwood et al. 1982). Minke whales are usually black or dark gray, with white on the belly and undersides of the flippers. The most conspicuous marking is a white band across the top of the flippers (Leatherwood et al. 1982). The dorsal fin is tall and falcate and there are between 50 and 70 thin ventral grooves, the longest ending slightly forward of the navel. The size of minke whales at birth varies from 2.1 to 2.8 m and they double in size by six months (Omura and Sakiura 1956). Females, which are larger than males, reach physical matu- 536 Biological Resources rity at about 8 m, although they sometimes reach lengths of 10 m (Leatherwood et al. 1982). With spring, sightings of minke whales become common over the continental shelf and in the nearshore waters of the Gulf. Over 95% of the sightings are shoreward of the 200-m contour (Consiglieri and Braham 1982). North Pacific minkes are distributed from the equator north to the Chukchi Sea (Leatherwood et al. 1982), and are most abun- dant in Alaska waters during the summer. They are less com- mon in British Columbia and southeastern Alaska than they are in the waters of the Gulf of Alaska and the eastern Aleu- tian Islands (Scattergood 1949). In a 1980 survey of the Gulf, Rice and Wolman (1981) found minkes in nearshore waters from southeastern Alaska to Kodiak Island; only three individuals were seen in oceanic waters of the Gulf. They are frequently observed in some bays of Kodiak Island in summer (T. Emerson, Alaska Department of Fish and Game, pers. comm. cited in Consiglieri and Braham 1982), as well as in Prince William Sound and Yakutat Bay. Their summer movements may be local and related to territoriality. In an area of 660 km2 of Puget Sound, 16 whales used at least three adjoining, exclusive ranges (Dorsey 1983). At least part of this range was probably seasonal. Minkes move into the Gulf in April and summer there. By October, most have left coastal Gulf waters, and have moved south. Of the five recorded minke whale sightings in winter in the Gulf of Alaska, two were south of Icy Bay and three were near Sitka (Consiglieri and Braham 1982). Minkes are found near shore for the most part. In Japan, no minke whales were taken beyond the 185-m contour (Omura and Sakiura 1956). Sexual segregation was reported for minke whales off the coast of Japan, where the immature males remained in southern waters, while the mature ani- mals— mostly adult females as well as some immature females — migrated to northern feeding grounds (Omura and Sakiura 1956). There is no current population estimate for North Pacific minke whales, but they are considered abundant. There is no current minke whale harvest in the area nor has there been an historically heavy take (Consiglieri and Braham 1982; International Whaling Commission 1981). The worldwide population was estimated at 3.25 x 105 indi- viduals (Scheffer 1976). Based on samples taken from Antarctic minke whales, the mean age at sexual maturity has dropped from 14 years to 6 years for males and from 14 years to 7 years for females (Masaki 1979). Masaki (1979) suggested this might be a result of the intense exploitation of baleen whales, including the increased harvest of minke whales. There is no data avail- able on age of sexual maturity of minke whales in the Gulf. Sexual maturity in minke whales off Japan was reached at 7.4 m for females and at 6.8 m for males (Omura and Sakiura 1956). Gestation takes from 10 to 11 months. Lactation, which lasts approximately 6 months, has been observed during ovulation in Antarctic minke whales, indicating an annual reproductive cycle (Lockyer 1981). The reported minimum pregnancy rate is 0.86 (International Whaling Commission 1981). Very little information is available on the food of minke whales in the Gulf. In general, euphausiids and schooling fishes are their main foods (Ohmura and Sakiura 1956; Tomilin 1957; Nemoto 1959; and Klumov 1963). Fishes eaten include pollock, salmon (Oncorhynchus sp.), cod, sand lance, and herring. One whale found stranded on Unalaska Island had small pollock in its stomach (Frost and Lowry 1981). The main euphausiids taken are probably Thysanoessa spinifera and Euphausia pacijica (Nemoto and Kasuya 1965). Lockyer (1981) estimated daily food consumption by minkes at 4% of the total body weight in summer. Killer Whale Killer whales (Orcinus orca) are among the most widely dis- tributed of all marine mammals. They occur in all oceans, major seas, and all ocean zones of the world (Dalheim, Leatherwood, and Perrin 1982). There are certain areas where they concentrate, such as within a few hundred kilo- meters of the coast and in the higher latitudes (Perrin 1982). Killer whales have a conspicuous, prominent mid-dorsal fin which in adult males can be 1.8 m tall. Females and juveniles have a smaller, somewhat falcate dorsal fin, usually less than 1 m tall (Leatherwood et al. 1982). The large flippers, which are shaped like broad, rounded paddles, are also distinctive (Leatherwood et al. 1982). Coloration in killer whales is sharply contrasting white and black. There is a large oval white patch above and behind each eye, the chin and throat are white, and the ventral surface is white. The white on the ventral surface narrows between the flippers, then con- tinues up on each side of the flanks. Most animals have a light gray saddle behind the dorsal fin. Male killer whales reach lengths of 9.5 m (average ~ 8 m) and weigh approx- imatly 8 mt, while females reach lengths of 8.2 m (average ~ 7 m) and weigh approximatly 4 mt (Dalheim 1981). New- borns are 2.1 m to 2.4 m in length and weigh about 180 kilo- grams. Killer whales are ubiquitous and abundant in the Gulf of Alaska. According to Consiglieri and Braham (1982) and Leatherwood, Balcomb, Matkin, and Ellis (1984) they are especially common near Kodiak Island, in Prince William Sound, and in the coastal waters of southeastern Alaska. Some killer whales are probably year-round Gulf residents (Braham and Dalheim 1982). In spring, killer whales can be found throughout the Gulf, primarily in the shelf waters shallower than 200 meters. The summer concentration areas are south and east of Kodiak, over Portlock Bank, in Prince William Sound, and in the inland waters of south- eastern Alaska (Consiglieri and Braham 1982). No specific, well-defined seasonal migrations have been documented for killer whales in the Gulf, although sightings of whales in waters as far as 100 nautical miles offshore have been interpreted by Consiglieri and Braham (1982) to be migrating animals. A group estimated to contain 500 killer whales sighted near Middleton Island in April 1973 (Jim Branson, National Marine Fisheries Service, pers. comm. cited in Calkins, Pitcher, and Schneider 1975) could repre- sent a northward spring migration. According to Dalheim (1981), both the movements and the distribution of killer Makini Mammals 537 whales are related to fish movements in summer and autumn. They are known to prey on shoreward-migrating schooling fish such as salmon and herring both in south- eastern Alaska and in Prince William Sound (Nishiwaki and Handa 1958; Fiscus 1980). No reliable estimate of killer whale abundance is avail- able. Leatherwood et al. (1984) counted a minimum of 286 killer whales in three study areas (173 in Prince William Sound, 96 in southeastern Alaska, and 17 in the Shelikof Strait area). These direct counts only represent a fraction of the total number of whales present in those areas and an even smaller fraction of the total number of killer whales in the Gulf of Alaska. Age at sexual maturity is not known, but is inferred both from the size of collected specimens and from the known growth rates of captive animals. Based on commercial catches of killer whales by Norway (Jonsgard and Lyshoel 1970), few pregnancies occur in females that are less than 4.9 m (16 ft) long. There is a marked increase in pregnancies in females over 4.9 m (16 ft). Gestation ranges from 12 to 16 months (Nishiwaki and Handa 1958; Perrin 1982). No direct evidence is available on the length of lactation in killer whales, but the calf remains closely associated with the cow for a period of between one and two years (Perrin 1982; Dalheim 1981). Killer whales prey on a variety of fish and marine mam- mals, but appear to prefer fish when they are abundant. Lowry et al. (1982), after extensively reviewing the literature, conclude that they have one of the most diverse diets of all marine mammals. The relative importance of individual food species in the diet has not been determined, but they are known to eat fur seals, walruses, sea lions, elephant seals, harbor porpoises, Dall's porpoises, minke whales, cods, flat- fishes (Pleuronectidae), and salmon (Tomilin 1957; Nishiwaki and Handa 1958; Bychkov 1967; Rice 1968; Fiscus 1980; and Dahlheim 1981). The daily food intake for four captive killer whales was estimated by Sergeant (1969) to be between 3.6 and 4.4% of their total body weight. Belukha Whale The belukha (beluga, or white whale) (Delphinapterus leucas) is the only medium-sized odontocete, common in the Gulf, that lacks a dorsal fin. Adult male belukhas reach lengths of between 3.2 and 4.4 m and weigh 520 to 1,200 kilo- grams. Females can be between 3.1 and 3.6 m in length and weigh 480 to 700 kilograms. Most newborn calves are about 1.6 m long (Kleinenberger, Yablokov, Bel'kovich, and Terasovich 1964; Leatherwood et al. 1982). Most adults are completely white, while newborns and immature animals are gray-shaded with blue or brown. Males become white as they reach nine years of age or older, while the females may become white as early as age six — but may retain some gray coloration for as long as 21 years (Burns and Seaman 1985). Belukhas are closely related to narwhals (Monodon mono- cents), and in the eastern Canadian Arctic, these two whales are sympatric. Belukhas are generally found in the open waters of those arctic and subarctic regions that are seasonally covered with ice. The Cook Inlet stock in the northern Gulf of Alaska is thought to be an isolated population. The nearest belukhas to the Cook Inlet stock are found in Bristol Bay on the north side of the Alaska Peninsula. No interchange between these stocks has been documented (Calkins 1984). Fay (University of Alaska, pers. comm., 1979) suggested the possibility of morphological differentiation between these stocks. He examined a limited series of skulls from Cook Inlet and compared them to skulls from other areas. The Cook Inlet sample was too small to conclude that the skull morphology differed from whales of the Bering Sea population (Calkins 1984). Belukhas are sighted mostly in coastal or continental shelf waters. They frequent shallow waters, bays, and estu- aries, and often enter rivers. Belukhas commonly concen- trate in the mouths of rivers during calving, possibly because of a thermal advantage to newborns and other age classes (Sergeant 1973; Sergeant and Brodie 1975; and Fraker, Sergeant, and Hoek 1978). In Cook Inlet, belukha concentrations have been observed near the mouths of the Susitna, Lewis, and Beluga rivers in late May andjune. They may be attracted to these areas by large numbers of ana- dromous fish, particularly eulachon (Thaleicthys pacificus), which are abundant there during the spring (Calkins 1984). Belukhas move seasonally in relation to the ice that forms over much of their range. Virtually all of the belukhas from the Bering, Chukchi, and Beaufort Seas spend the winter along the Bering Sea ice fringes (Kleinenberger et al. 1964; Fay 1974; Seamen and Burns 1981). In the Gulf of Alaska, belukhas follow a seasonal pattern: they move into upper Cook Inlet in the spring, they concentrate near the mouths of rivers in the early summer (May andjune), they can be found throughout Cook Inlet through late summer, and then probably move to the lower Inlet in winter (Fig. 17-3). Some belukhas have been seen in Yakutat Bay (Calkins and Pitcher 1977) on an irregular basis. Consiglieri and Braham (1982) reported annual observations in Yakutat Bay by local fishermen. However, those reports are anecdotal and lack sufficient documentation to conclude that there is a small, resident population in Yakutat Bay. The belukhas that are seen in Yakutat Bay are probably members of the Cook Inlet stock and move across the north Gulf of Alaska. Other sightings reported outside Cook Inlet were at the Barren Islands, Marmot Bay north of Kodiak Island, Mon- tague Island, and Shelikof Strait (Consiglieri and Braham 1982). In July 1983, approximately 200 belukhas were sighted in Prince William Sound just south of Bligh Island. These are assumed to have been part of the Cook Inlet stock. No systematic, thorough surveys have been made of the Cook Inlet belukhas. Klinkhart (1966) estimated this stock at between 300 and 500 animals. Recent census work has not appreciably changed that estimate (Murray and Fay 1979; Calkins 1984). Estimates of between 300 and 500 individuals were based on direct counts and do not account for those animals that were underwater (and not seen) or for animals which were beyond the survey area. It is possible that there may be as many as 2 to 4 times more belukhas in the area than the current estimate. Female belukhas are capable of breeding late in their third or fourth year. Males are sexually mature by the eighth year (Brodie 1971; Sergeant 1973; and Seaman and Burns 538 Biolocical Resources 130 60 6C 55 > OS General range of belukha whales Late Mav-earlvjune concentration 160 150 Figure 17-3. Distribution of belukha whales in the Gulf of Alaska. 1981). Breeding occurs in May and calving takes place in July or August after a gestation period of about 14 months (Lensink 1961; Fraker 1977; and Seaman and Burns 1981). Calving is followed by a two-year nursing period (Brodie 1971; Sergeant 1973) that completes a triennial breeding cycle. Belukhas feed both on fish and on some invertebrates. Although they are capable of diving deeper, they feed pri- marilv in the upper 10 m of water (Kleinenberger et al. 1964). Little information is available on the feeding habits of belukhas in Cook Inlet. However, Calkins (1984) observed whales (assumed to be feeding), in association with con- centrations of anadromous fishes such as salmon or eulachon. In other parts of their range, belukhas eat over 100 species (Kleinenburger et al. 1964). Common in their diet are smelt, capelin, eulachon, herring, and saffron cod (Eleginus gracilis). In offshore waters, Arctic cod and pollock mav be impor- tant prey, along with shrimps, octopus, and sculpins (Lowrv, Frost, and Seaman 1985). Sergeant (1969) presented data on the feeding rates of captive belukhas. He estimated that their consumption rate was between 4 and 7% of their body weight per day, with the highest percentage representing the feeding rate of a calf. Pacific White-sided Dolphin Pacific white-sided dolphins (Lagenorhyncus ololiquidens) are also commonly called lags, a term that is an abbreviation of the genus Lagenorhynchus. They are strong swimmers and leapers, sometimes turning complete aerial somersaults (Leatherwood et al. 1982). Lags reach a length of at least 2.3 m and may weigh as much as 150 kilograms. They have a mod- erately tall, strongly recurved dorsal fin that is situated in the mid-back. Their coloration is usually distinctive: a black back, light gray sides, and a white belly. A white or light-grav stripe starts at the forehead and face, then curves upward 140 over the top of the head, continues along the back to the area of the dorsal fin, and finally widens and curves toward the anus, forming a prominent, light gray patch on the flank. The dorsal fin is dark on the forward one-third and light gray on the rear two-thirds (Leatherwood et al. 1982). Pacific white-sided dolphins frequent the continental shelf slope and the coastal heads of deep-sea canyons (Leatherwood and Reeves 1978). They range throughout the Gulf of Alaska. There is not enough information to charac- terize their seasonal movements as migrations, although thev are seasonallv abundant in some areas (Consiglieri and Braham 1982). Pacific white-sided dolphins become increasingly abun- dant in the spring, particularly in the eastern Gulf. The period of highest abundance is during the summer, when thev concentrate over the Fairweather Ground and Portlock Bank (Consiglieri and Braham 1982). Autumn sightings have been reported from both the northeast and the north- west Gulf. Winter sightings have been rare (Consiglieri and Braham 1982). Lags are extremely gregarious and groups of over 1,000 individuals have been sighted in the Gulf. Groups consisting of over 100 lags are common (Morris et al. 1983). While no reliable estimate of the total number of Pacific white-sided dolphins in the Gulf was found, it is estimated that there are between 2,000 and 3,000 individuals. Reproductive biology of Pacific white-sided dolphins is not well understood. Males are sexually mature at between 1.7 and 1.8 m and females mature at between 1.8 and 1.9 meters. Most calving apparently takes place in the summer (Leatherwood et al. 1982). Almost no information is available about the feeding habits of Pacific white-sided dolphins in the Gulf. Near shore in California and Puget Sound, the usual prey consists of anchovies (Engraulis mordax), hake (Merluccins productus), and squids (Leatherwood and Reeves 1978). Lags are oppor- tunistic feeders that consume a variety of small schooling Marine Mammals 539 fishes and cephalopods similar to those taken by Dall's por- poise (Stroud, Fiscus, and Kajinnira 1981). No information on their food requirements was found. It can be assumed, however, that similar to Dall's porpoise, they require approximately 10% of their body weight per day. Dall's Porpoise Dall's porpoises (Phocoenoides dalli) are the most common small cetacean of the northern North Pacific (Leatherwood et al. 1982). They are ubiquitous year-round residents throughout much of the Gulf of Alaska (Consiglieri and Braham 1982). They grow to a length of 2.2 m and weigh — 300 kg (Leatherwood et al. 1982). Dall's porpoises are stocky, with males exhibiting much thicker bodies than the females. Their striking black-and-white color pattern makes identification relatively easy. The body is shiny black, with large, oval, white patches on each side at about mid -body. The patches meet ventrally at the midriff and end below the dorsal fin. The upper half of the dorsal fin and the upper rear margin of the flukes are also white (Leatherwood et al. 1982). Dall's porpoises can be found in the waters of the conti- nental shelf and slope. They tend to prefer wide straits and areas of merging currents, or the channels between islands (Scheffer 1949; Cowan 1944). Hall (1979) rarely saw Dall's porpoises in less than 20 m of water in Prince William Sound. The only continental shelf or slope areas of the Gulf that are not frequented by Dall's porpoises are those shal- low, turbid waters such as upper Cook Inlet and Icy Bay (Consiglieri and Braham 1982). Dall's porpoises show evidence of seasonal movements, but no directed, consistent migrations have been docu- mented. Kasuya (1976) described north/south, summer/ winter movements in Japan, while Leatherwood and Field- ing (1974) described seasonal on-shore and offshore move- ments in California. Hall (1979) documented clear seasonal population declines from summer to fall in Prince William Sound. According to Bouchet (1981), the North Pacific popula- tion of Dall's porpoises is estimated at between 8.37 x 105 and 1.3 * 106, excluding those animals found in the coastal waters of California, Oregon, and Washington. The Gulf of Alaska population estimates range from between 1.37- and 2.54 x 105 individuals. Density estimates in the Gulf range from 0.277 to 0.514 porpoises/nmi2. Parturition occurred between June and August for those Dall's porpoises that were taken in gillnets incidental to the North Pacific Japanese salmon fishery (Newby 1982). More- john (1979) reported that calving occurred year-round in northeastern Pacific waters from Alaska to California, while Kasuya (1976) found that parturition occurred from August to September in the western Pacific. Newby (1982) found that males became sexually mature at 183 cm or at 5.7 years, while females mature sexually at 171 cm or 3.3 years. At birth, calves are about 95 cm long and weigh 16.5 kilograms. Wean- ing occurs after one to two months. Stomach content data from 457 Dall's porpoise taken during the high seas salmon gillnet fishery in 1978 and 1979 show that they eat squids (primarily of the family Gonatidae), as well as 29 fish species (Jones, Newby, Crawford, and Treacy 1980). Of the fishes eaten, a major pro- portion were from the family Myctophidae. Other impor- tant fishes were bathylagids and sand lance (Scheffer 1953). Based on a review of the available literature, Lowry et al. (1982) concluded that a daily food intake of about 10% of the body weight is necessary in order to sustain a Dall's porpoise in the Bering Sea. Harbor Porpoise The harbor porpoise (Phocoena phocoena) is the smallest cetacean that inhabits the Gulf of Alaska. It grows to a max- imum length of about 1.8 m and a maximum weight of about 90 kg (Leatherwood et al. 1982). The harbor porpoise is dark brown or gray above and gray or white below, with the white coloration extending onto the chin. The upper jaw and lower lip are both dark, and a dark stripe extends from the corners of the mouth to the flippers. Harbor porpoises appear to prefer coastal areas — partic- ularly harbors, bays, and the mouths of rivers (Tomilin 1957). They dive to at least 80 m in search of food (Scheffer and Slipp 1948). No specific migrations have been docu- mented for harbor porpoises, although several investigators (Consiglieri and Braham 1982; Hall 1979; and Leatherwood and Reeves 1978) have noted changes in seasonal abun- dance. Hall (1979) estimated the winter population in Prince William Sound to be about half the summer population. The Prince William Sound concentration of harbor por- poises may be the largest in the eastern North Pacific (Leath- erwood and Reeves 1978). No population estimate is currently available for the Gulf of Alaska. Hall (1979) estimated 590 harbor porpoises in Prince William Sound in the winter and 946 in the summer. There is extensive suitable habitat in the Gulf of Alaska and sightings are numerous. This led Morris et al. (1983) to sug- gest that harbor porpoises are abundant, and to estimate that there may be between 2,000 and 3,000 in the Gulf. Little is known about the reproductive biology of harbor porpoises in the eastern North Pacific. Tomilin (1957) thought that breeding periods were similar for the North Atlantic, North Pacific, and the Black Sea stocks. In the Black Sea, harbor porpoises mate from June to October, with peak activity occurring in August. Calving occurs in May and June after a gestation period of between 10 and 11 months (Tomilin 1957). In the Atlantic stock, sexual matu- rity is reportedly attained by males at age 4 to 5 years and by females at age 6 years (Prescott and Fiorelli 1980; Fisher and Harrison 1970). Harbor porpoises in the North Atlantic feed on cod (Gadus morhua), herring, and Atlantic mackerel (Scomber scombrus) (Smith and Gaskin 1974). Frost and Lowry (1981) found the remains of small fish (primarily saffron cod) and crustaceans in the stomachs of three harbor porpoises from Norton Sound. The predominant food species in the North Atlantic were pelagic, schooling fishes that were often of some economic importance (Smith and Gaskin 1974). In the Gulf of Alaska, harbor porpoise probably feed on fishes such as herring, capelin, pollock, and eulachon — although no data are available to verify that. Hall (1979) 540 Biolocical Resources reported harbor porpoises at the mouth of the Copper River and assumed they were foraging on those fish species that concentrate in the area where the Copper River water mixes with water from the Gulf. Little information on food requirements exists for harbor porpoises. Sergeant (1969) and Prescott and Fiorelli (1980) all suggested a daily feeding rate for harbor porpoises of between 8.3 and 10% of their body weight. Harbor Seal The harbor seal (Phoca vitulina richardsi) is found in all coastal areas of the Gulf of Alaska, where Pitcher (1985) con- sidered it to be the most widely distributed of the Pinnipedia. Harbor seals are relatively small 'earless' seals, with stiff, bristle-like hair and short limbs. There is a consid- erable variety in their coloration and markings — ranging from spots of white-gray to dark brown or black along with rings, and splotches that occur on a background of similar colors (Bigg 1981). The average birth size of harbor seal pups in the Gulf of Alaska varied by area. Near Kodiak, for exam- ple, newborn pups weighed 12 kg and measured 78 cm in length while in the northeastern Gulf, they weighed 10 kg and were 73 cm in length (Pitcher and Calkins 1979). Adult males averaged 155 cm in length and weighed 85 kg, while females were 145 cm in length and 77 kg in weight through- out the Gulf. Harbor seals use land areas known as terrestrial haulouts for resting and nurturing their young. Haulout substrate is highly variable, ranging from rocky intertidal reefs to broad, flat sandy beaches and calved glacial ice. According to Pitcher (1985), some important characteristics of seal haul- outs are: ready access to water, isolation from disturbance, protection from wind and wave action, and access to food. There are thousands of locations in the Gulf of Alaska where harbor seals haul out. However, Pitcher and Calkins (1979) list only 103 locations where more than 25 seals were sighted (see Fig. 17-4). During the early to mid-1970s, Tugidak Island off the south end of Kodiak Island had the largest concentration of harbor seals on the west coast of North America. However, the numbers have recently declined and Tugidak no longer holds this distinction (Alaska Department of Fish and Game, unpubl. data). Harbor seals, although often considered to be sedentary and limited to coastal areas, are known to move relatively long distances and have been sighted as far as 100 km off- shore (Pitcher and Calkins 1979; Wahl 1977; and Spalding 1964). The movements of 31 radio-tagged seals in the Gulf of Alaska were documented by Pitcher and McAllister (1981). The longest movement was 194 km along the shores of Kodiak Island. One of the tagged seals crossed 74 km of open ocean to occupy a different hauling area, then subse- quently returned to the site where it was tagged. At least for adults, there appears to be considerable fidelity to haulout sites as demonstrated by the fact that 23 of the 31 harbor seals tagged by Pitcher and McAllister (1981) remained at the capture site. There is no evidence of true migration. Both the numbers and the distributions of seals in the Gulf of Alaska remain relatively constant throughout the year. In the Gulf, most harbor seal pups are born between the 5th and the 25th of June (Pitcher and Calkins 1979). Pups nurse for a period of between three and six weeks — after which they completely separate from the female. Ovulation occurs between mid-June and mid- to latejuly, shortly after weaning in those females that have pupped, but implanta- tion is delayed for approximately 11 weeks. Age of first ovula- tion is from 3 to 7 years, and the pregnancy rates for females 8 years old and older is 92 percent. Male seals in the Gulf become sexually mature by age 6 (Pitcher and Calkins 1979). 130 60 150 Figure 17-4. Areas of known concentrations of harbor seals in the Gulf of Alaska. (All sightings were made of hauled-out animals only.) Makini Mammals 541 The prey of harbor seals (by frequency of occurrence) consisted of 73.8% fishes, 22.2% cephalopods — both octopus and squid — and 4.1% decapod crustaceans (pri- marily shrimps). Twenty-seven species of fishes belonging to 13 families were identified as harbor seal prey. The three most-important prey were pollock, octopus (Octopus sp.), and capelin (Pitcher and Calkins 1979). Most investigators agreed upon a dailv consumption rate for harbor seals of 7.5% of the seal's body weight (Ashwell-Erickson and Eisner 1981). Because harbor seals are distributed in small groups throughout coastal areas and because of their relatively shy nature, they are very difficult to count. Various methods have been used to estimate their numbers in a given area, including direct counts of those that are hauled out at a given time, as well as estimates based on harvest statistics. Those estimates that are based on harvest data are probably the most accurate because they take into account the entire population rather than the instantaneous number that are hauled out at a given time. Based on harvest statistics. Pitcher (1985) estimated the abundance of harbor seals in the Gulf of Alaska as follows: Dixon Entrance to Cape Fairweather — 30,000; Cape Fair- weather to Kenai Peninsula, including Prince William Sound — 70,000; Cook Inlet, Kodiak Archipelago, Shelikof Strait, and the south side of the Alaska Peninsula — 55,000. The total estimate for the Gulf of Alaska was 155,000 harbor seals. These estimates were originally made for an environ- mental impact statement in 1973. No data are available to update these estimates, although Pitcher (K. Pitcher, Alaska Department of Fish and Game, pers. comm, 1985) considers them to be imprecise. Recent information gathered by ADF&G suggests that this stock may have declined substan- tially since 1973. Steller Sea Lion The Steller sea lion (Eumetopias jubatus) is the largest and one of the most conspicuous pinnipeds inhabiting the North Pacific Ocean — and its range is restricted to this area. The Steller sea lion is the largest of the eared seals, the Otariidae. The only other member of this family that is found commonly in the Gulf of Alaska is the northern fur seal (CaUorhinus ursinus). The pups are chocolate brown, but because they lack pig- ment in the tips of their hair, they have a frosty appearance. The pups appear to gradually grow lighter in color as the animals get older. Many adults are a yellowish cream color on the back, although some remain darker. Males generally remain darker on the front of the neck and chest and grow a short mane over the back of the shoulders and neck. The mane and the large front shoulders and neck resemble the terrestrial lion — thus the name sea lion. The common name Steller' is used to honor the German naturalist G. W. Steller, who first described this species in 1751. Steller sea lions show a pronounced sexual dimorphism in size. Males average more than twice the weight of females and are about 20% longer. Calkins and Pitcher (1982) found that sea lion pups weigh approximately 23 kg at birth and are 110 cm long (curvilinear length). Average weight and standard length for adults was 263 kg and 228 cm for females and 560 kg and 282 cm for males. Steller sea lions are widely distributed over the continen- tal shelf and throughout the coastal waters of the Gulf of Alaska. Offshore, they are normally found at depths shal- lower than 2,000 m and are frequently found in greatest numbers near the 200-m contour (Consiglieri and Braham 1982). Sea lions use terrestrial haulouts for resting and they tend to gather on traditional, well-defined rookeries in order to pup and breed. Calkins and Pitcher (1982) listed 61 locations in the Gulf where sea lions haul out on a regular basis and 46 more locations which are used irregularly. The latter are referred to as stopover areas. The majority of pups are pro- duced at 11 pupping rookeries (Fig. 17-5). Generally, stop- over areas are used by small numbers of animals — usually less than 200. Haulouts can be used by as few as 50 or as many as 4,000 animals. Rookeries are usually used by several thousand animals during the breeding season. All rookeries become haulouts during non- breeding periods. Some rookery haulouts are used by only a few hundred indi- viduals during winter months while other areas continue to be used by up to 3,000 animals in winter. The haulout behavior of sea lions is complicated and not completely understood. At some haulouts during some peri- ods, there appears to be specific sex and age segregation and usage. On rookeries, non-territorial males apparently stay on the fringes while parturient females and territorial males use the central part of the rookery. The intervening area is used by a mixture of all age classes and by both sexes. Adult sea lions gather on the rookeries beginning about mid-May. Males defend territories on the rookeries and generally exclude other males. Territorial boundaries are often defined by the physical features of the rookery. Females enter and move about within the territories at will, although there appears to be some competition among females for particular locations on the rookery. It is not known whether they are competing for the most desirable location for parturition or for the most desirable males within the territories. Certainly, there is evolutionary advan- tage to mating with the fittest males, although Gentry and Withrow (1978) point out that some females may give birth in one territory, mate in another, and spend the majority of their time in still another. The total range of Steller sea lions extends from the California Channel Islands along the North Pacific Rim to northern Japan. The center of abundance is the western Gulf and eastern Aleutian Islands. Loughlin, Rugh, and Fiscus (1984) estimated a total world population of 2.45- to 2.90 x 105 individuals. Calkins and Pitcher (1982) estimated that there were 1.4 x 105 sea lions in the Gulf of Alaska in 1979. However, recent surveys of all age classes suggest this population may be declining (Calkins 1985a). Pups are born from about May 15 through July 15. The females breed again about 11 days after giving birth (Gentry 1970; Sandegren 1970). Early embryonic growth temporarily ceases at the blastocyst stage which does not implant on the uterine wall until late September or October (Pitcher and Calkins 1981). 542 Biological Resources 160 60 > <=»?. Clubbing Rocks Rock 150 140 Figure 17-5. Locations of major Steller sea lion pupping rookeries in the Gulf of Alaska. Some males are physiologically capable of breeding at three years of age and most are probably capable of breed- ing by age seven years. However, they are not large enough and strong enough to defend territories until about their tenth year. Some females breed for the first time in their third year and bear the first pup at age 4. Most females attain sexual maturity by age 6 and bear a pup each year (Pitcher and Calkins 1981). Pollock is the most important prey species for sea lions in the Gulf of Alaska. Pitcher (1981) found the diet of Steller sea lions in the Gulf to consist of 67% pollock by frequency. Other important prey found were: • squids (Gonatidae) — 23% • octopus— 13% • Pacific cod (Gadus macrocephalns) — 19% • Pacific herring (Clupea harengus pallasii) — 16% • capelin — 16% • salmon — 6% • sculpins (Cottidae) — 6% • flatfishes— 7% • rockfishes — 4%. Harbor seal remains have rarely been found in the stomachs of sea lions in the Gulf of Alaska (Pitcher and Fay 1982). Although information on the food requirements of sea lions is incomplete, Keyes (1968) concluded that sea lions con- sume from 6 to 10% of their body weight per day. Northern Fur Seal The northern fur seal (Callorhinus ursinus) has a thick, heavy, water-repellent coat of underfur, along with unusually large flippers. Adults appear yellowish brown on the rookeries, but at sea they appear black with a gray or light-colored throat. Adult females in prime condition usu- ally weigh between 37 and 40 kg, while males average 127 kilograms. At birth, female pups weigh about 4.5 kg and males weigh about 5.5 kg (Fiscus 1978). For much of their life, fur seals are pelagic and rarely come ashore except on their home islands during the breed- ing season. The northern fur seal is found in the Gulf of Alaska primarily on a seasonal basis, although Kajimura (1980) stated that they can be found in all parts of their range in any month of the year. They are most abundant in the Gulf in the spring, during their annual migration to the Pribilof Islands breeding grounds (Consigleiri and Braham 1982). The spring fur seal distribution in the Gulf of Alaska is shown in Figure 17-6. Some young males and non-pregnant females remain in the Gulf during summer. Small numbers of fur seals regu- larly haul out in summer on Sugarloaf Island in the Barren Islands and at Forrester Island off Dixon Entrance in south- eastern Alaska (Fiscus 1983). Most of the adult population moves to the Pribilof Islands for both pupping and breed- ing, which take place from mid-June through mid-August (Bartholomew and Hoel 1953; Kajimura 1980; and Fiscus 1983). After the breeding season, fur seals remain at the Pribilof Islands until late October when some of the females begin the southward migration. As this southward migration esca- lates, the number of fur seals increases in the Gulf. Some breeding-age males remain in the southeastern Bering Sea, although most of the animals move into the Gulf of Alaska and southward towards their wintering areas (Kajimura, Lander, Perez, York, and Bigg 1980a). Some older males spend the winter in the Gulf (Alexander 1953), while most younger males and females move south to winter along the continental shelf off British Columbia, Washington, Oregon, and California (Kajimura et al. 1980a). Consiglieri and Braham (1982) stated that one large group of fur seals winters off Baranof Island. Fur seals have also been seen during the winter on the edge of Portlock Bank and in the deep waters of the central Gulf (Consiglieri and Braham 1982; Kajimura et al. 1980a). Marine Mammals 543 Distribution ol northern Fui seal Abundant Common Figure 17-6. General distribution of northern fur seals in the Gulf of Alaska during spring. (Modified from Consiglieri and Braham 1982.) When hunters began killing fur seals commercially for their skins in 1786, the Pribilof fur seal population was esti- mated at 2.5 x 106 animals. The herd steadily declined to a low point in 1835, when Russia provided some protection. The herd was allowed to grow to relatively high numbers (numbers unknown) until the United States purchased Alaska in 1867 (Gentry 1981). The herd again decreased until 1910 when fewer than 2.0 x 105 animals remained. The Fur Seal Treaty in 1911 both protected the seals and regulated their harvest and the herd was again allowed to grow. By 1950, the herd was producing over 4.0 x 105 pups annually (Lander and Kajimura 1976). An attempt to stimu- late reproduction by harvesting females between 1956 and 1968 resulted in another herd reduction (Fowler 1982; Gentry 1981; and Ghapman 1973). The Pribilof fur seal herd was estimated at 2.1 x 106 in 1951 and most recently at 8.77 x 105 individuals (Briggs and Fowler 1984). During the breeding season, male fur seals defend their territories and mate with the females shortly after the females give birth to pups (Fiscus 1978). The blastocyst does not implant on the uterine wall until October or November. Most females attain sexual maturity at four or five years of age (Kajimura et al. 1980a) and from that point on, over 80% of the females between the ages of 6 and 17 years become pregnant each year (Kajimura et al. 1980a). Fur seals feed on a wide variety of fish and cephalopods (Kajimura et al. 1980b), and they are capable of diving to 200 m in search of prey — although most feeding dives have been reported to be in the range of 20 to 100 m (Kooyman, Gentry, and Urquhart 1976). Their principal prey in the Gulf of Alaska includes pollock, capelin, sand lance, herring, and several species of squid (Kajimura et al. 1980b). Scheffer (1950) calculated the daily food requirement of fur seals to be 6.7% of the total body weight, whereas Miller (1978) estimated a minimum feeding rate of 14% of body weight per day. Sea Otter The sea otter (Enhydra lutris) is the only marine represen- tative of the mustelid family in North America. It inhabits the nearshore areas of the North Pacific from California to the Kuril Islands. The best paleontological evidence sug- gests that otters, including sea otters, descended from com- mon Asiatic ancestors (Kenyon 1969). Three races of sea otters have been described, and those otters found in the Gulf belong to the race Enhydra lutris lutris (Kenyon 1981). Sea otter pups appear yellowish because of the light col- oration in their guard hairs, although their dense underfur is brown (Kenyon 1969). Adults typically tend to be dark-bodied with buffy to light gray heads. The head tends to become lighter with age, and a more grizzled coloration may appear on other parts of the body. Body color varies from light buff (rare) through shades of brown to nearly black. The coloration of their guard hair ranges from dark to silver white (Kenyon 1969). Sea otters may vary in size according to nutritional conditions, and therefore their overall average size may not be the same for different areas. Based on data from Kenyon (1969), mean body sizes for sea otters in the Aleutian Islands are: • newborns — 2 kg in weight and 57 cm in length • adult female — 21 kg in weight and 125 cm in length • adult males — 28 kg in weight and 135 cm in length. Sea otters are found in nearshore habitats throughout the Gulf of Alaska. Although they are apparently capable of diving to depths in excess of 90 m, they prefer depths of less than 55 m (Kenyon 1981). Their preferred habitat appears to be those waters that are adjacent to rocky coasts that have extensive areas of submerged reefs. Although sea otters favor areas where kelp beds (Alaria sp., Macrocystis sp., and Nereocystis sp.) occur, this does not appear to be a require- ment (Kenyon 1969). 544 Biolocical Resources Certain areas are occupied exclusively by the males, while other areas are used both by females with pups and by small numbers of territorial males. Those areas occupied solely by males tend to be in more exposed, newly colonized loca- tions while areas occupied by females tend to be in bet- ter-protected locations (Garshelis, Johnson, and Garshelis 1984). This pattern indicates that different sexes and age classes may have different habitat requirements (Calkins and Schneider 1985). Sea otters make use of terrestrial haul- out sites, using some sites more frequently than others. Abundant food at accessible depths is probably the most rigid habitat requirement; other habitat characteristics may be desirable, but not necessarily required. The seasonal movements of the otters between their male and female areas are apparently influenced by factors such as breeding, pup-rearing, boat traffic patterns, and protec- tion from inclement weather (Garshelis and Garshelis 1984) — as well as by the availability of food. Although much of the Gulf coast is considered potential sea otter habitat, not all areas have been completely repopulated. At the time when the United States gave protection to sea otters (1911) under the Fur Seal Treaty, several isolated locations of the Alaskan coast had small, remnant populations of sea otters. Those groups that had survived were apparently located in Prince William Sound, at Kodiak Island, on the south side of the Alaska Peninsula, and near Sanak Island (Kenyon 1969). These nucleus populations increased and expanded until they occupied much of Prince William Sound, includ- ing the area of Controller Bay and Kayak Island, the Kenai Peninsula, lower Cook Inlet, the Barren Islands, much of the south side of the Alaska Peninsula, and most of the Kodiak Island area (Fig. 17-7). There are still scattered areas that are not fully repopulated throughout the Gulf. The unoccupied areas west of Cape St. Elias are small and otter populations are increasing within those areas. The Gulf coast from Cape Spencer to Cape St. Elias supports only scattered small groups and individual animals. During the period from 1965 through 1969, the Alaska Department of Fish and Game (in cooperation with the Atomic Energy Commission) perfected techniques for large-scale sea otter translocations (Burris and McKnight 1973). A total of 413 sea otters were reintroduced into areas of former habitat both in the northeastern Gulf and in southeastern Alaska between Yakutat Bay and the Barrier Islands. Data from surveys in 1983 showed this population had grown to more than 1,500 animals (Johnson, Jameson, Schmidt, and Calkins, 1983) and probably exceeded 2,000 animals (Alaska Department of Fish and Game, unpubl. data). Sea otter populations have been increasing throughout most areas of the Gulf of Alaska since 1911. The most recent population estimates by Calkins and Schneider (1985) are shown in Table 17-2. Table 17-2. Estimate of sea otter numbers in the Gulf of Alaska (from Calkins and Schneider 1985). Location Estimate Southeast Alaska Yakutat to Cape St. Elias Prince William Sound Kenai Peninsula and Cook Inlet Kodiak (including Barren Islands) South side of Alaska Peninsula Total 2,000* 100 4,000-6,000 2,500-3,500 4,000-6,000 22,000-25,000 34,600-42,600 From Johnson etal. (1983) and Alaska Department of Fish and Game (unpubl. data). 130 60 60 Sanak^ Sandman Shumagin Islands Island Reefs Present sea otter distribution Locations of nucleus groups (from Kenyon, 1969) 130 150 140 Figure 17-7. Present distribution of sea otters in the Gulf of Alaska with assumed locations of nucleus groups and expansion of translocated populations. Makini Mammais 545 Productivity and reproduction in sea otters have not been completely studied. There appears to be variability in the timing of events between growing populations and those populations that have become well established and exist at a level that is near the habitat's carrying capacity. Sea otters apparentlv mate and give birth at any time of the year (Mmie 1940; Fisher 1940; Barabash-Nikiforov 1947; Lensink 1962; and Kenyon 1969). Schneider (1972) found that in the Aleutian Islands, breeding activity peaked in September and October and parturition reached a peak in April, May, and early June. The average gestation period was estimated to be about 7.5 months. A delayed implantation lasted approximately half of the gestation period. Schneider (1972) found that most females became sexu- ally mature at age 3 and bore their first pup at age 4. The females nursed their pups for as long as a year and rarely became pregnant during this period. Thus, a two-year breeding cycle was postulated for sea otters in the Aleutians (Schneider 1972). However, recent studies in Prince William Sound indicated that pupping may occur annually in areas where the population is well below the habitat's carrying capacity (A.Johnson, U. S. Fish and Wildlife Service, Anchorage, AK., pers. comm., 1984) . Sea otters feed on a wide variety of bottom-dwelling invertebrates and Fishes. Generally, they feed heavily on invertebrates until they deplete the supply, then the otters move to unoccupied habitat or consume fish. Kenyon (1969) found that at Amchitka Island sea otters ate a variety of spe- cies, including: • chitons (Cnptochiton stelleri) • snails (Buccinium sp.) • mussels (Musculus vernicosa) • octopus • rock oysters (Pododesmus macrochisma) • crabs (Cancer sp.) • green sea urchins {Strongylocentrotus droebachiensis) • globe fish (Cyclopterichthys glaber) • red Irish lords (Hemilepidotus hemilepidotus). In the Gulf of Alaska, Calkins (1978) found that otters ate clams, primarily Saxidomus giganteus (81%), but also took octopus, crabs, and sea stars (Evasterias troschelii). Daily con- sumption rates of from 20 to 30% of body weight were esti- mated for otters (Morrison, Roenmann, and Estes 1974; Kenyon 1969). Other Marine Mammals Two species of the large cetaceans listed in Table 17-1 — the blue whale (Balaenoptera miisculus) and the Pacific right whale (Balama glacialis) — are considered endangered. They both exist in such low numbers that their recovery may be extremely slow, and has probably not yet even begun (Mizroch.Rice, and Breiwick 1984; Braham and Rice 1984). For a variety of reasons, the Pacific right whale was highlv sought after by commercial whalers and was consequently reduced to such low levels that the population was dan- gerously near extinction. Less than 200 right whales may remain in the entire North Pacific (Braham and Rice 1984). Blue whales, although present in higher numbers than the right whales, arc also rarely sighted; and very little is known about either their biology or their ecology in the Gulf. Blue whale sightings have been recorded in the west- ern Gulf in the summer, and they apparently migrate south in the winter (Berzin and Rovnin 1966; Rice 1978a; and Consiglieri and Braham 1982). The short-finned pilot whale {Globkepliala nuurorhyruhus) and Risso's dolphin (( irampus griseus) are both rarely sighted in the Gulf. Their range lies mostly to the south and the few sightings that have been made have usually been in summer (Consiglieri and Braham 1982). The northern right whale dolphin is also a species that occurs in more southern, tem- perate waters. Consiglieri and Braham (1982) state that there are no reliable sightings of northern right whale dolphins north of 50°N, although they list three tentative sightings north of 54°N. The Bering Sea beaked whale {Mesoplodon stejnegeri), Cuvier's beaked whale (Ziphius cavirostris), and Baird's beaked whale (Berardius bairdi) are found in the Gulf, but lit- tle is known about them. No population estimates are avail- able for any beaked whales in the Gulf. Bering Sea beaked whales have not been commercially exploited, so little is known about their life history. The only specific informa- tion comes from a few sightings of stranded animals. Morris et al. (1983) speculated that Bering Sea beaked whales inhabit the deep waters of the continental slope. However, the recent strandings of three individuals in Cook Inlet, during the autumn of three successive years indicate that they may, at least occasionally, be attracted to nearshore waters. Although Cuvier's beaked whale and Baird's beaked whale have both been commercially taken in small numbers by Japan, little information is available about either species in the Gulf. They are both thought to inhabit water deeper than 1,000 m (Nishiwaki and Oguro 1971, 1972). Squid and deep water fish appear to be important prey for both species (Nishiwaki 1972; Nishiwaki and Oguro 1971, 1972). Neither food-habit data nor population estimates are available for any of the beaked whales in the Gulf of Alaska. Pacific walruses (Odobenus rosmarus) have occasionally been sighted in the Gulf (Murie 1959; Calkins et al. 1975; Bailey and Faust 1981; and Fay 1982). Fay (1982) reviewed sev- eral sightings of walruses which had apparently entered the Gulf through Unimak Pass in the winter of 1979, and then in the spring had moved north along the south side of the Alaska Peninsula as far as Cook Inlet. He considered these to be extralimital sightings. Walrus sightings continue to be reported from Cook Inlet. California sea lions (Zalophus californianus) have been reported in the Gulf of Alaska on at least two occasions: once from Point Ellrington, outside of Prince William Sound, in June of 1974 (K. Schneider, Alaska Department of Fish and Game, pers. comm., 1974) and once at Point Lull, on Baranof Island, southeastern Alaska, in April 1982. Northern elephant seals (Mirounga angustirostris) are reg- ular summer visitors to southeastern Alaska where each year small numbers are found in the inside waters. Southeastern Alaska can be considered the northern limit of their range. Several individuals have been found stranded at other loca- tions in the Gulf. For example, a subadult male elephant seal 546 Biological Resources was found stranded on Middleton Island in April 1975, and a young female was found stranded on Unalaska Island (in the eastern Aleutian Islands) in October 1976 (R. Nelson, Alaska Department of Fish and Game, pers. comm., 1976). In addi- tion, a badly decomposed elephant seal was found in February 1977 at Wide Bay on the Alaska Peninsula. Discussion and Conclusions Marine mammals in the Gulf of Alaska are ecologically situated as high trophic-level consumers. They feed on a variety of nektonic, benthic, and planktonic animals. The most common prey for marine mammals in the Gulf are: • copepods • euphausiids • schooling fishes such as herring, cod, pollock, capelin, and salmon • cephalopods — primarily squids • other crustaceans. I used the daily consumption rates presented for each spe- cies in this chapter as the basis for calculating an annual con- sumption rate of 7.55 x 106 metric tons of food consumed by the common marine mammals of the Gulf (Table 17-3). This total does not take into account the marine mammals dis- cussed in the section 'Other Marine Mammals'. The method I used to derive this total was to multiply the estimated average daily consumptions by the estimated number of days spent in the Gulf annually, and then multi- ply that total by the estimate for the total number of indi- viduals in the Gulf. This is among the simplest methods for deriving annual consumption rates. It does not fully take into account factors such as differential feeding rates between age classes or between seasons, nor does it consider the different caloric values of the foods that were consumed. Where information was not available, I interpolated it from comparisons with other marine mammals of similar size and with similar prey selection. Therefore, the information presented in Table 17-3 is crude, and is probably a conser- vative approximation. The most accurate and useful information from Table 17-3 is the comparison of the total amount of food that was consumed by the different species. Among cetaceans, the fin whales consumed the most, followed by the sei whales and Dall's porpoises. It seems apparent that the largest species, such as fin and sei whales, should rank high. However, the Dall's porpoise also ranks high, even though it is a small ceta- cean, primarily because of the relative abundance of this species in the Gulf. Steller sea lions had the highest consumption among the pinnipeds. This was because their large size requires a rela- tively high consumption rate. The annual food consump- tion of 5.5 x 105 mt by the Gulf sea lions is over twice as high as the 2.6 x 105 mt of groundfish harvested by commercial fishermen in the Gulf during the 1981 season (Kajimura and Loughlin, in press; Morris et al. 1983). Marine mammals depend, to a large extent, on food spe- cies that are also harvested commercially by man. This means that numerous conflicts have developed between the marine mammals and fishermen. Interactions between man and marine mammals have resulted in actions ranging from inconsistent federal legislation to more direct conflicts between the marine mammals and the fishermen (Metlef and Rosenberg 1984). The complexity of the problem is often reflected in management policy. For example, the Marine Mammal Protection Act of 1972 requires that marine mammals be managed to maintain the health and stability of the ecosystem. In contrast, the (Magnuson) Fish- eries Conservation and Management Act of 1976 mandates that fisheries be managed to provide maximum sustainable yield under current environmental conditions. Numerous conflict situations have developed between commercial fishermen and marine mammals. An example is the Shelikof Strait pollock fishery. This fishery was devel- oped in order to take advantage of the enormous spawning schools of pollock which aggregate in Shelikof Strait between January and March (Loughlin and DeLong 1983). One thousand ninety-three sea lions were caught and killed incidental to this fishery in 1982, and 222 were killed in 1983. Since 1983, the number of sea lions that were killed in this fishery has been lower than the 1983 level (T. R. Loughlin, National Marine Mammal Laboratory, pers. comm., 1985). It is assumed that the reason a large number of sea lions were killed in 1982 involved both the timing and the location of the fishery, coupled with the inexperience of the fishermen (Loughlin and DeLong 1983). Since then, the fishing has taken place earlier in the year and further south in Shelikof Strait — and the fishermen have gained experience in avoid- ing sea lions. Another serious problem that arises from the marine mammal/fisheries interaction is the entanglement of marine mammals in marine debris. Over the last decade, there has been an alarming increase in the amount of debris that is deposited into the world's oceans (Shomura and Yoshida 1985). Much of this debris is discarded net frag- ments. Uchida (1985) estimated that 5,500 km of trawl nets are used in the North Pacific. Trawl-net fragments are com- monly seen on both fur seals and sea lions and nets are the most common debris in which these species become entangled (Fowler 1982; Scordino 1985; and Calkins 1985b). The closed, plastic packing bands which are commonly discarded into the ocean are the second most common type of debris that entangles fur seals and sea lions. Entangle- ment in marine debris can cause mortality in marine mam- mals and it has been implicated as being partly responsible for the continuing decline in the Pribilof fur seal herd (Fowler 1982). Although it probably does cause some mor- tality in sea lions, entanglement is probably not responsible for the decline in these populations. Sea otters are involved in fisheries conflicts because they can substantially reduce benthic invertebrate popula- tions— some of which are commercially valuable. In Prince William Sound, sea otters have been blamed for the decline of shellfish (Garshelis and Garshelis 1984). Substantial (>80%) reductions in the dungeness crab population (Cancer magister) were noted in Orca Inlet following an influx of large numbers of otters. (A. T. Kimker, Alaska Depart- ment of Fish and Game, unpubl. data, 1985; Garshelis and Garshelis 1984). Other crab stocks that are close outside Marinf Mammals 547 Table 17-3. Estimates of annual consumption rates of food by marine mammals in the Gulf of Alaska. Average Daily Est. No. Est. No. Est. ofTotai Types ok Food Consumption of Days of Individ. Annual Species Consumed (kg) in Gulf Using Gulf Consumption (mt) Fin whale Copepods, euphausiids, fish 1,500 150 10,000 2.25 million Sei whale Copepods, euphausiids, fish 1,500 120 8,600 1.55 million Humpback whale rAiphausiids, fish 1,100-' 210 1,200 277,000 Gray whale Unknown in Gulf 600h 45 13,000 351,000 Sperm whale Cephalopods, fish 1,000 120 3,000" 360,000 Minke whale Euphausiids, fish 270* 210" 3,000- 170.000 Killer whale Fish, marine mammals 240a 365* 300 26,300 Belukha whale Fish, cephalopods, shrimp 51 365 500 9,310 Pacific white-sided dolphin Fish, cephalopods 15a 300a 3,000- 13,500 Dall's porpoise Fish, crustaceans 30 300* 150,000* 1.35 million Harbor porpoise Fish, crustaceans 6 365 3,000- I 1 ,000 Total food consumed by common cetaceans 6.59 million Harbor seals Fish, cephalopods, crustaceans 6 365 155,000 340,000 Sea lions Fish, cephalopods 14.3 365 105,000 548.000 Fur seals Fish, cephalopods 7 45 450,000 142,000 Sea otters Benthic invertebrates, fish 10 365 41,000 150,000 Total food consumed by common pinnipeds and sea otters 1.18 million Total food consumed by all common marine mammals 7.77 million a Actual numbers not available; numbers inferred from data available compared to other species. b Gray whale feeding in the Gulf not documented. Prince William Sound may be in jeopardy if the otters fol- low their pattern of depleting abundant benthic inverte- brates and moving to nearby unused habitat. In other areas near Kodiak Island and in lower Cook Inlet commercial fishermen have complained that sea otters are heavily foraging on the already depleted king crab {Paralithodes camtschatica) and tanner crab {Chionoecetes bairdi) populations. Generally, reports of depleted clam popula- tions are common from both sportsmen and subsistence users soon after the otters expand into areas of recently vacant habitat. If they are allowed to expand unchecked, little doubt remains that sea otters will deplete some com- mercially valuable or highly favored invertebrate popula- tions. Although the present legal framework under which sea otters are managed (the Marine Mammal Protection Act of 1972) was supposedly designed to promote both the health and the stability of the marine ecosystem, no provi- sions were made that would give the managing agencies the latitude necessary to resolve conflicting situations — particu- larly situations where marine mammals are responsible for depleting other species. Whale viewing has become a popular activity in recent years. In Glacier Bay National Park, the annual return of humpback whales attracts numerous tour vessels and pri- vate operators intent on viewing these whales. The substan- tial reduction in the number of resident whales in Glacier Bay that began in 1978 and lasted through 1984 has prompted a concern for the whales (Kreiger and Wing 1985). It was assumed that there were two reasons why numbers of resident whales decreased: 1) the increase in vessel traffic and/or 2) changes in the forage in Glacier Bay. The National Park Service took steps to reduce vessel traffic in Glacier Bay during the months of June, July, and August, and also regulated vessel speeds in those areas where whales concentrated (Krieger and Wing 1985). Con- currently, studies were initiated in order to 1) determine the acoustic environment of humpback whales in Glacier Bay and in Frederick Sound; 2) determine the effect of vessel traffic on whale behavior; and 3) determine both the dis- tribution and the abundance of whale prey. Krieger and Wing (1985) concluded that the main reason for the decline of resident whales in Glacier Bay was variation in whale for- age. They predicted that changes in the availability of whale forage will continue and that the humpbacks will respond by varying their use of Glacier Bay. 548 Biological Resources Generally, disturbance from both vessels and aircraft has been noted to have some effect on several different marine mammal species that are commonly found in the Gulf. Fraker el til. (1978) described the disturbance of belukhas by both vessels and aircraft. Johnson (1977) estimated that 10% of the harbor seal pup mortality could be attributed to air- craft disturbance at Tugidak Island. Loughlin (1974) believed the absence of seals in two bays in California was due to extensive commercial and sport boat traffic. Calkins (1979) described disturbance of sea lions by aircraft in the Gulf. Public awareness of and attention to marine mammals have been growing in recent years. A notable example of this is the attention given a proposal to take killer whales for public display from Prince William Sound and southeastern Alaska. Concurrent with their capture proposal, Hubbs Sea World Research Institute began a long-term study of killer whales in those areas (Leatherwood e t al. 1984). Public outcry has jeopardized the capture proposal, even though only 10 whales were to be taken. Certainly, the removal of 10 whales could not have affected the current population of killer whales in these areas, even if all 10 were taken from one area. A great deal of information is available on marine mam- mals in the Gulf of Alaska even though some of the biolog- ical parameters of all the species remain unknown. Com- mercial whaling — which resulted in the decimation of the populations of great whales — also provided most of the information on distribution, numbers, and general biology. Much is yet to be learned about these animals. However, information will be more difficult to obtain because in some cases, the species' numbers are so low that even sightings are rare occurrences. Almost no information is available on beaked whales in the Gulf of Alaska; much is yet to be learned about the breeding biology, food habits, distribu- tion, and numbers of these species. Studies of belukha whales in the Gulf of Alaska have been supported through the Outer Continental Shelf Environ- mental Assessment Program (OCSEAP) and through the state of Alaska's Environmental Assessment Program for hydroelectric projects on the Susitna River (Calkins 1984). Both of these efforts were relatively small and provided only distributional information. Little is known about the food habits, the movements, or the numbers of the belukhas that inhabit the Gulf. Work on Dall's porpoise by the National Marine Fish- eries Service (in response to incidental catches on the high seas) is the best and only extensive work which has been per- formed on a small cetacean in the Gulf. Much of the recent information on pinnipeds in the Gulf was gained through the OCSEAP-sponsored research efforts; however, pinniped research under that program has been terminated in the Gulf. Some information has been provided through studies supported by the National Marine Fisheries Service. However, much work remains to be done on both the distribution and the numbers of pinnipeds in the Gulf. Recent information indicates a decline in both sea lion and harbor seal stocks. Immediate investigation of this problem is critical. Very little is known about either the sea otter's food habits or its abundance over much of its range in the Gulf, and more work is needed to determine the sig- nificance of this species in the ecosystem. Acknowledgments Pauline Hessing participated in the preparation of this chapter and deserves much of the credit for gathering infor- mation for the summaries on cetaceans. Karl Schneider reviewed the manuscript in addition to providing support throughout the preparation of this work. John Burns, Kathy Frost, and Steve Zimmerman provided exceptionally com- plete critical reviews of the manuscript. This chapter was prepared, and much of the data collec- tion accomplished, with support from the Minerals Manage- ment Service, Department of the Interior, through a Memo- randum of Understanding with the National Oceanic and Atmospheric Administration, Department of Commerce, as part of the Outer Continental Shelf Environmental Assess- ment Program. The Alaska Department of Fish and Game contributed my salary and all clerical support. References Alexander, A. 1953 Untitled manuscript concerning fur sea activities in 1892. Records of the U.S. Fish Com- mission. General Services Administration, U.S. National Archives, National Technical Infor- mation Service, Washington D.C. 23 pp. Allen, K. 1974 Current status and effect of a moratorium on the major whale stocks. Report of the International Whaling Commission 24:72-75. Ashwell-Erickson, S. and R. Eisner 1981 The energy cost of free existence for Bering Sea harbor and spotted seals. In: The Eastern Bering Sea Shelf: Oceanography and Resources. D.W. Hood andJ.A. Calder, editors. Office of Marine Pollution Assessment, NOAA. Distributed by the University of Washington Press, Seattle, WA. pp. 869-899. Bailey, E.P. and N.H. Faust 1981 Summer distribution and abundance of marine birds and mammals between Mitrofania and Sutwik islands south of the Alaska Peninsula. The Murrelet 62:34- 42. Baker, R.C., F. Wilke, and H. Baltzo 1970 The northern fur seal. U.S. Fish and Wildlife Service Circular No. 336. 19 pp. Marinf Mammais 549 Baker, C.S., L.M. Herman, A. Perry, W.S. Lawton, J.M. Straley, andJ.H. Straley 1985 Population characteristics and migration of summer and late-season humpback whales (Megaptera novaeangliae) in southeastern Alaska. Marine Mammal Science 1:304-232. Bannister, J. and E. Mitchell 1980 North Pacific sperm whale stock identity: dis- tributional evidence from Maury and Towns- end charts. In: Report of the International Whaling Commission Special Issue 2:219-230. Barabash-Nikiforov, I. 1935 The sea otters of the Commander Islands.yowr- nal of Mammalogy 16:255-261. Barnes, R.D. 1974 Invertebrate Zoology. W.B. Saunders, Phila- delphia, PA. 870 pp. Barnes, G.L. and S.A. McLeod 1984 The fossil record and phyletic relationships of gray whales. In: The Gray Whale Eschrichtius robustus. M.L.Jones, S.L. Swartz, and S. Leath- erwood, editors. Academic Press, Orlando, FL. pp. 3-32. Bartholomew, G.A., Jr. and P.G. Hoel 1953 Reproductive behavior of the Alaska fur seal, Callorhinus ur sinus. Journal of Mammalogy 34:417-436. Berzin, A.A. 1959 [On the feeding of sperm whales (Physeter cata- don) in the Bering Sea]. Rybnogo Khozyaistvo 47:161-165. (In Russian. Translated by Israel Program for Scientific Translations, 1972.) Berzin, A.A. 1970 Kashalot [The Sperm Whale]. Tikhookeanskii Nauchno-Issledovatel'skii Institut Rybnogo Khozyaistva Okeanographii, Moscow, USSR. 367 pp. (In Russian. Translated by Israel Pro- gram for Scientific Translations, 1972. 394 pp.) Berzin, A.A. and A.A. Rovnin 1966 The distribution and migrations of whales in the northeastern part of the Pacific Ocean, Chukchi, and Bering Seas. Izvestiya TINRO 58:179-208. (Translated by U.S. Department of the Interior, Bureau of Commercial Fisheries, Seattle, WA, 1966.) Best, P. 1968 The sperm whale {Physeter catodon) off the west coast of South Africa. Division of Sea Fisheries Investigations (Cape Town) Report No. 66. pp. 1-32. Bigg, M.A. 1981 Best, P. 1975 Review of world sperm whale stocks. 1975 Report to Food and Agriculture Organization of the United Nations Advisory Committee on Marine Resources Research. ACMRR/MM/ EC/18. 35 pp. Harbour seal Phoca vitulina Linnaeus, 1758 and Phoca largha Pallus, 1811. In: Handbook of Marine Mammals, Vol. 2, Seals. S.H. Ridgway and R.J. Harrison F.R.S., editors. Academic Press, New York, NY. pp. 1-27. Blokhin, S.A. 1984 Investigations of gray whales taken in the Chukchi coastal waters, USSR. In: The Gray Whale Eschrichtius robustus. M.L.Jones, S.L. Swartz, and S. Leatherwood, editors. Academic Press, Orlando, FL. pp. 487-509. Braham, H.W. 1984 Distribution and migration of gray whales in Alaska. In: The Gray Whale Eschrichtius robustus. M.L.Jones, S.L. Swartz, and S. Leath- erwood, editors. Academic Press, Orlando, FL. pp. 249-266. Braham, H. and M. Dalheim 1982 Killer whales in Alaska documented in the plat- forms of opportunity program. Report of the International Whaling Commission 32:643-646. Braham, H.W. and D.W. Rice 1984 The right whale, Balaena glacialis. Marine Fish- eries Review 46(4):38-44. Breiwick, J.M. and H.W. Braham, editors 1984 The status of endangered whales. Marine Fish- eries Review 46(4):l-64. Briggs, L. and C.W. Fowler 1984 Tables and figures of the basic population data for the northern fur seals of the Pribilofs. Back- ground paper submitted to the twenty-fourth meeting of the Standing Scientific Committee of the North Pacific Fur Seal Commission, Moscow, USSR, March 29-April 9, 1984. 29 pp. Brodie, P.F. 1971 A reconsideration of aspects of growth, reproduction, and behavior of the white whale (Delphinapterus leucas) with reference to the Cumberland Sound, Baffin Island population. Journal of the Fisheries Research Board of Canada 28:1309-1318. 550 Biological Resources Bouchet, G. 1981 Estimation of abundance of Dall's porpoise (Phocoenoides dalli) in the North Pacific Ocean and Bering Sea. Northwest and Alaska Fish- eries Center Processed Report 81-1, National Marine Fisheries Service, NOAA, Seattle, WA. 25 pp. Burns, J.J. and G.A. Seaman 1985 Investigation of Belukha whales in coastal waters of western and northern Alaska. II. Biol- ogy and Ecology. Final report submitted to NOAA, Alaska Outer Continental Shelf Environmental Assessment Program, Anchorage, AK. 129 pp. Burris, O.E. and D.E. McKnight 1973 Game transplants in Alaska. Wildlife Technical Bulletin No. 4, Alaska Department of Fish and Game, Juneau, AK. 57 pp. Bychkov, V.A. 1967 [On killer whale attacks on fur seals off Tyaleniy Island]. Zoologicheskii Zhurnal 46(1):149-150. (Translator unknown, in files, National Marine Mammal Laboratory, National Marine Fisheries Service, NOAA, Seattle, WA.) Calkins, D.G. 1978 Feeding behavior and major prey species of the sea otter, Enhydra lutris, in Montague Strait, Prince William Sound, Alaska. Fishery Bulletin (U.S.) 76:125-131. Calkins, D.G. 1979 Marine mammals of Lower Cook Inlet and the potential for impact from outer continental shelf oil and gas exploration, development and transport. Research Unit 243. Environmental Assessment of the Alaskan Continental Shelf, Final Reports of Principal Investigators 20:171-263. Calkins, D. 1984 Belukha whales. Susitna hydroelectric project final report: big game studies, Vol. IX. Alaska Department of Fish and Game, Anchorage, AK. 16 pp. Calkins, D.G. 1985a Steller sea lion pup counts in and adjacent to Shelikof Strait. Final report submitted to the North Pacific Fisheries Management Council. Contract 84-1. Alaska Department of Fish and Game, Anchorage, AK. 13 pp. Calkins, D.G. 1985b Steller Sea lion entanglement in marine debris. In: Proceedings of the Workshop on the Fate and Impact of Marine Debris. R.S. Shomura and H.O. Yoshida, editors. NOAA Technical Memoran- dum NMFS-SWFC-54. pp. 308-314. Calkins, D.G. and K.W. Pitcher 1977 Unusual sightings of marine mammals in the Gulf of Alaska. In: Proceedings of the Second Con- ference on the Biology of Marine Mammals, San Diego, California, 12-15 December 1977. p. 53 . (Abstract only) Calkins, D.G. and K.W. Pitcher 1982 Population assessment, ecology and trophic relationships of Steller sea lions in the Gulf of Alaska. Research Unit 243. Environmental Assess- ment of the Alaskan Continental Shelf, Final Reports of Principal Investigators 19:171-264. Calkins, D.G, and K.B. Schneider 1985 The sea otter (Enhydra lutris). In: Marine Mam- mals Species Accounts. J.J. Burns, K.J. Frost, and L.F. Lowry, editors. Wildlife Technical Bulletin No. 7, Alaska Department of Fish and Game, Juneau, AK. pp. 37-45. Calkins, D.G., K.W. Pitcher, and Karl Schneider 1975 Distribution and abundance of marine mam- mals in the Gulf of Alaska. Unpublished report, Alaska Department of Fish and Game, Division of Game, Anchorage, AK. 39 pp. plus 31 charts. Chapman, D.G. 1973 Management of international whaling and North Pacific fur seals: implications for fish- eries management. Journal of the Fisheries Research Board of Canada 30:2419-2426. Chevigny, H. 1965 Russian America: The Great Alaskan Venture. The Viking Press, New York, NY. 274 pp. Chittleborough, R. 1960 Determination of age in the humpback whale, Megaptera nodosa (Bonaterre). Norsk Hvalfangst- Tidende 49:12-37. Consiglieri, L.D. and H.W. Braham 1982 Seasonal distribution and relative abundance of marine mammals in the Gulf of Alaska. Research Unit 68. Partial final report submit- ted to NOAA, Alaska Outer Continental Shelf Environmental Assessment Program, Juneau, AK. 212 pp. Cowan, I.M. 1944 The Dall porpoise, Phocoenoides dalli (True), of the northern Pacific Ocean. Journal of Mam- malogy 25:295-306. Cunningham, W. and S. Stanford 1979 Observations of migrating gray whales (Eschrichtius robustus) at Cape St. Elias, Alaska. Unpublished manuscript, Alaska Department of Fish and Game, Anchorage, AK. 22 pp. Makini Mammals 551 Dalheim, M. 1981 A review of the biology and exploitation of the killer whale, Orciniis orca, with comments on recent sightings from the Antarctic. Report of the International Whaling Commission 31:541-546. Dalheim, M.E., S. Leatherwood, and W.F. Perrin 1982 Distribution of killer whales in the warm tem- perate and tropical Eastern Pacific. Report of the International Whaling Commission 32:647-653. Darling, J.D. 1984 Gray whales off Vancouver Island, British Columbia. In: The Gray Whale Eschrichtius robustus. M.L.Jones, S.L. Swartz, and S. Leath- erwood, editors. Academic Press, Orlando, FL. pp. 267-287. Dorsey, E.M. 1983 Exclusive adjoining ranges in individually identified minke whales {Balaenoptera acutoro- strata) in Washington state. Canadian Journal of Zoology 61:174-181. Fay, F.H. 1974 The role of ice in the ecology of marine mam- mals of the Bering Sea. In: Oceanography of the Bering Sea. D.W. Hood and EJ. Kelley, editors. Occasional Publication No. 2, Institute of Marine Science, University of Alaska, Fair- banks, AK. pp. 383-399. Fay, F.H. 1982 Ecology and biology of the Pacific walrus Odobenus rosmarus divergens Illiger. North Amer- ican Fauna No. 74. U.S. Department of the Inte- rior, Washington, D.C. 279 pp. Fiscus, C.H. 1978 Northern fur seal. In: Marine Mammals of Eastern North Pacific and Arctic Waters. D. Haley, editor. Pacific Search Press, Seattle, WA. pp. 153- 159. Fiscus, C.H. 1980 Marine mammal-salmonid interactions: a review. In: Salmonid Ecosystems of the North Pacific. W.J. McNeil and D.C. Himsworth, editors. Oregon State University Press, Corvallis , OR. pp. 121-132. Fiscus, C.H. 1983 Fur seals and islands. Background paper sub- mitted to the twenty-eighth meeting of the Standing Scientific Committee of the North Pacific Fur Seal Commission, Washington D.C, March 1983. 19 pp. Fisher, E.M. 1940 Earlv life of a sea otter pup. Journal of Mam- malogy 21:132-137. Fisher, H.D. and R.J. Harrison 1970 Reproduction in the common porpoise (Pho- coena phocoena) of the North Atlantic.yr/urrwz/ of Zoology (London) 161:471-486. Fowler, C.W. 1982 Interactions of northern fur seals and commer- cial fisheries. In: Transactions of the Forty-seventh North American Wildlife and Natural Resources Conference. K. Sabol, editor. Wildlife Manage- ment Institute, Washington, D.C. pp. 278-292. Fraker, M.A. 1977 The 1977 whale monitoring program, Mack- enzie Estuary, NWT. Imperial Oil Ltd. Project No. V1771, F.F. Slaney and Co., Ltd., Vancouver, B.C., Canada. 53 pp. Fraker, M.A., D.E. Sergeant, and W. Hoek 1978 Bowhead and white whales in the southern Beaufort Sea. Technical Report No. 4, Beaufort Sea Project, Canadian Department of Fisheries and the Environment. 114 pp. Frost, K. and L. Lowry 1981 Foods and trophic relationships of cetaceans in the Bering Sea. In: The Eastern Bering Sea Shelf: Oceanography and Resources. D.W. Hood and J.A. Calder, editors. Office of Marine Pollu- tion Assessment, NOAA. Distributed by the University of Washington Press, Seattle, WA. pp. 825-836 Fugino, K. 1960 Imunogenetic and marking approaches to identifying subpopulations of the North Pacific whales. Scientific Report of the Whales Research Institute 15:85-142. Gaskin, D.E. 1982 The Ecology of Whales and Dolphins. Heinemann Educational Books, Ltd., London, England. 459 pp. Garshelis, D.L. and J.A. Garshelis 1984 Movements and management of sea otters in Alaska. Journal of Wildlife Management 48:665-678. Garshelis, D.L., A.M.Johnson, and J. A. Garshelis 1984 Social organization of sea otters in Prince William Sound, Alaska. Canadian Journal of Zool- ogy 62:2648-2658. Gentry, R.L. 1970 Social behavior of the Steller sea lion. Ph.D. Dissertation, University of California, Santa Cruz, CA. 113 pp. 552 Biological Resources Gentry, R.L. 1981 Northern fur seal Callorhinus ursinus (Linnaeus, 1758). In: Handbook of Marine Mammals, Vol. I, The Walrus, Sea Lions, Fur Seals and Sea Otters. S.H. Ridgway and RJ. Harrison F.R.S., editors. Academic Press, New York, NY. pp. 143-160. Gentry, R.L. and D.E. Withrow 1978 Steller sea lion. In: Marine Mammals of Eastern North Pacific and Arctic Waters. D. Haley, editor. Pacific Search Press, Seattle, WA. pp. 167- 171. Gosho, M.E., D.W. Rice, andJ.M. Breiwick 1984 The sperm whale, Physeter macrocephalus. Marine Fisheries Review 46(4):54-64. HalLJ.D. 1979 A survey of cetaceans of Prince William Sound and adjacent vicinity — their numbers and sea- sonal movements. Research Unit 481. Environ- mental Assessment of the Alaskan Continental Shelf, Final Reports of Principal Investigators 6:631-726. Hall, J. and J. Johnson 1978 A survey of cetaceans of Prince William Sound and adjacent vicinity — their numbers and sea- sonal movements. Research Unit 481. Environ- mental Assessment of the Alaskan Continental Shelf Annual Reports of Principal Investigators l(Recep- tors: mammals, birds):414-426. Hall, J. and M. Tillman 1977 A survey of cetaceans in Prince William Sound and adjacent vicinity — their numbers and sea- sonal movements. Research Unit 481. Environ- mental Assessment of the Alaskan Continental Shelf, Annual Reports of Principal Investigators l(Recep- tors: mammals):681-708. Harwood, J. and DJ. Garrod 1980 The status of the North Pacific sperm whale. Report of the International Whaling Commission 30:187-192. Henderson, D.A. 1984 Nineteenth century gray whaling: grounds, catches and kills, practices and depletion of the whale population. In: The Gray Whale Eschrichtius robustus. M.L. Jones, L.L. Schwartz, and S. Leatherwood, editors. Aca- demic Press, Orlando, FL. pp. 159-186. Ingebrightsen, A. 1929 Whales caught in the North Atlantic and other areas. Rapport Proces-Verbaux Reunion Conseil International pour VExploration de la Mer 56:1- 26. International Whaling Commission 1981 Report of minke whale subcommittee. Report of the International Whaling Commission 31:103-113. Johnson, A., R.Jameson, T. Schmidt, and D. Calkins 1983 Sea otter survey, southeast Alaska, 1983. Unpublished report, U.S. Fish and Wildlife Service, Anchorage, AK. 10 pp. Johnson, B.W. 1977 The effects of human disturbance on a popula- tion of harbor seals. Unpublished report, Alaska Department of Fish and Game, Anchorage, AK. 11 pp. Johnson, J.H. and A.A. Wolman 1984 The humpback whale, Megaptera novaeangliae. Marine Fisheries Review 46(4):30-37. Jones, L.L., T.C. Newby, T.W. Crawford, and S. Treacy 1980 Progress report on life history studies of Dall's porpoise in the northwestern Pacific, 1978-1979. Document submitted to meeting of the Scientific Subcommittee on Marine Mam- mals, International North Pacific Fisheries Commission, Tokyo, Japan, Feb. 25- 29, 1980. 34 pp. Jonsgard, A. and P.B. Lyshoel 1970 A contribution to the knowledge of the biology of the killer whale, Orcinus orca (L.) Nytt Magazin Zoobgi 18:41-48. Jurasz, CM. and V.P. Jurasz 1979 Feeding modes of the humpback whale, Megap- tera novaeangliae, in southeastern Alaska. Scien- tific Report of the Whales Research Institute 31:60-83. Kajimura, H. 1980 Distribution and migration of northern fur seals in the Eastern Pacific. In: Further analysis of pelagic fur seal data collected by the United States and Canada during 1958-74. Part 1. H. Kajimura, R.H. Lander, M.A. Perez, A.E. York, and M.A. Bigg, editors. Unpublished report of the Twenty-third Annual Meeting, Standing Scientific Committee, North Pacific Fur Seal Commission, April 1980, Moscow, USSR. pp. 4-43. Kajimura, H. and T.R. Loughlin Marine mammals in the oceanic food web of the eastern subarctic Pacific. Bulletin of the Ocean Research Institute, University of Tokyo (in press). Kajimura, H., R.H. Lander, M.A. Perez, A.E. York, and M.A. Bigg, editors 1980a Further analysis of pelagic fur seal data col- lected by the United States and Canada during 1958-74. Part 1. Unpublished report of the Twenty-third Annual Meeting, Standing Sci- entific Committee, North Pacific Fur Seal Com- mission, April 1980, Moscow, USSR. 94 pp. Makinf Mammais 553 Kajimura, H., R.H. Lander, M.A. Perez, A.E. York, and M.A. Bigg, editors 1980b Further analysis of pelagic fur seal data col- lected by the United States and Canada during 1958-74. Part 2. Unpublished report of the Twenty-third Annual Meeting, Standing Sci- entific Committee, North Pacific Fur Seal Com- mission, April 1980, Moscow, USSR. 172 pp. Kasauya, T. 1976 Preliminary report on the biology, catch and populations of Phocoenoides in the western North Pacific. Food and Agriculture Organiza- tion of the United Nations ACMRR/MM/SC/21. 20 pp. Kawakami, T. 1980 A review of sperm whale food. Scientific Report of the Whales Research Institute 32:199-218. Kawamura, A. 1980 A review of food of balaenopterid whales. Scien- tific Report of the Whales Research Institute 32:155-198. Kawamura, A. 1982 Food habits and prey distributions of three ror- qual species in the North Pacific Ocean. Scien- tific Report of the Whales Research Institute 34:59-91. Kenyon, K.W. 1969 The sea otter in the eastern Pacific Ocean. North American Fauna No. 68, U.S. Depart- ment of the Interior, Washington, D.C. 352 pp. Kenyon, K.W. 1981 Sea otter Enhydra lutris (Linnaeus, 1758). In: Handbook of Marine Mammals, Vol. 1, The Walrus, Sea Lions, Fur Seals and Sea Otter. S.H. Ridgway and R.S. Harrison F.R.S., editors. Academic Press, New York, NY. pp. 209-223. Keyes, M.C. 1968 The nutrition of pinnipeds. In: The Behavior and Physiology of Pinnipeds. RJ. Harrison, R.C. Hub- bard, R.S. Peterson, C.E. Rice, and R.J. Schuster- man, editors. Appleton-Century-Crofts, New York, NY. pp. 359-395. Kleinenburger, S.E., A.V. Yablokov, B.M. Belkovich, and M.N. Taresevich 1964 Beluga (Delphinapterus leucas) investigation of the species. (Translated by Israel Program for Scientific Translations, Jerusalem), U.S. Department of Commerce, NTIS Document No. TT-67-51345. 376 pp. Klinkhart, E. 1966 The beluga whale in Alaska. Unpublished report, Alaska Department of Fish and Came, Juneau, AK. 11 pp. Klumov, S. 1963 [Food and helminth fauna of whalebone whales (Mysteceti) in the main whaling regions of the world.] Trudy, Institut Okeanologi 71:94-194. (Fisheries Research Board of Canada Translation Series no. 589.) Kooyman, C.L., R.L. Oentry, and D.L. Urquhart 1976 Northern fur seal diving behavior: a new approach to its study. Science 193:411-412. Krieger, KJ. and B.L. Wing 1985 Location and assessment of humpback whale forage in southeastern Alaska with sonar echo sounding. Unpublished report, Auke Bay Lab- oratory, NOAA, National Marine Fisheries Service, Auke Bay, AK. 66 pp. Lander, R.H. and H. Kajimura 1976 Status of northern fur seals. Food and Agri- culture Organization of the United Nations, Advisory Committee on Marine Resources Research, FAO Scientific Consultation on Marine Mammals, Bergen, Norway, 31 August-9 September 1976. ACMRR/MM/SC/34. 50 pp. Leatherwood, J.S. and M. Fielding 1974 A summary of distribution and movements of Dall porpoises (Phocoenoides dalli), off southern California and Baja California. Food and Agri- culture Organization of the United Nations. ACMRR/42. Leatherwood, S. and R.R. Reeves 1978 Porpoises and dolphins. In: Marine Mammals of Eastern North Pacific and Arctic Waters. D. Haley, editor. Pacific Search Press, Seattle, WA. pp. 97-111. Leatherwood, S., K.C. Balcomb III, C. Matkin, and G. Ellis 1984 Killer whales (Orcinus orca) of southern Alaska. Results of field research 1984. Preliminary report, Hubbs Sea World Research Institute, San Diego, CA. 59 pp. Leatherwood, J.S., R.R. Reeves, W.F. Perrin, and W.E. Evans 1982 Whales, dolphins, and porpoises of the eastern North Pacific and adjacent arctic waters. A guide to their identification. U.S. Department of Commerce, NOAA Technical Report NMFS Circular 444. 245 pp. Lensink, C.J. 1961 Status report: beluga studies. Unpublished manuscript, Division of Biological Research, Alaska Department of Fish and Game, Juneau, AK. 20 pp. 554 Biological Resources Lensink, C.J. 1962 The history and status of sea otters in Alaska. Ph.D. Dissertation, Purdue University, Lafayette, IN. 188 pp. Lockyer, C. 1976a Growth and energy budgets of large baleen whales from the southern hemisphere. Report to Food and Agriculture Organization of the United Nations, Advisory Committee on Marine Resource Research. ACMRR/MM/ SC/41. 179 pp. Lockyer, C. 1976b Estimates of growth and energy budget for the sperm whale, Physeter catodon. Report to Food and Agriculture Organization of the United Nations, Advisory Committee on Marine Resource Research. ACMRR/MM/SC/38. 33 pp. Lockyer, C. 1981 Estimation of the energy costs of growth, main- tenance, and reproduction in the female minke whale, {Balaenoptera acutorostrata), from the southern hemisphere. Report of the Interna- tional Whaling Commission 31:337-343. Loughlin, T.R. 1974 The distribution and ecology of harbor seal in Humboldt Bay, California. M.S. Thesis, Humboldt State University, Areata, CA. 71 pp. Loughlin T.R. and R.L. DeLong 1983 Incidental catch of northern sea lions during the 1982 and 1983 walleye pollock joint venture fishery, Shelikof Strait, Alaska. Northwest and Alaska Fisheries Center Processed Report 83-15, National Marine Fisheries Service, NOAA, Seattle, WA. 37 pp. Loughlin, T.R., D.J. Rugh, and C.H. Fiscus 1984 Northern sea lion distribution and abundance: 1956- 80. Journal of Wildlife Management 48:729-740. Lowry, L.F., K.J. Frost, and G.A. Seaman 1985 Investigations of belukha whales in coastal waters of western and northern Alaska. III. Foods. Final report submitted to NOAA, Contract No. NA81RAC00049, Alaska Outer Continental Shelf Environmental Assessment Program, Anchorage AK. Alaska Department of Fish and Game, Fairbanks, AK. 24 pp. Lowry, L.F., K.J. Frost, D.G. Calkins, G.L. Swartzman, and S. Hills 1982 Feeding habits, food requirements, and status of Bering Sea marine mammals. Final report, North Pacific Fisheries Management Council, Anchorage, AK. Documents No. 19 and 19A. 574 pp. Masaki, Y. 1976 Biological studies on the North Pacific sei whale. Bulletin of the Far Seas Fisheries Research Institute (Japan) No. 14. 104 pp. Masaki, Y. 1979 Yearly change of the biological parameters for the Antarctic minke whale. Report of the Interna- tional Whaling Commission 29:375-395. Melteff, B.R. and D.H. Rosenberg, editors 1984 Proceedings of the 1983 Workshop on Biological Inter- actions Among Marine Mammals and Commercial Fisheries in the Southeastern Bering Sea, October 18-21, 1983, Anchorage, AK. Alaska Sea Grant Report 84-1, University of Alaska, Fairbanks, AK. 300 pp. Miller, L.K. 1978 Energetics of the northern fur seal in relation to climate and food resources of the Bering Sea. Final report, Marine Mammal Commis- sion Contract MM5AC025. U.S. Marine Mam- mal Commission, Washington, D.C. National Technical Information Service document PB 275-296/2GA. 34 pp. Mitchell, E. 1978 Finner whales. In: Marine Mammals of Eastern North Pacific and Arctic Waters. D. Haley, editor. Pacific Search Press, Seattle, WA. pp. 37-45. Mizroch, S.A., D.W. Rice, andJ.M. Breiwick 1984 The blue whale, Balaenoptera musculus. Marine Fisheries Review 46(4)45-19. Morejohn, G.V. 1979 The natural history of Dall's porpoise in the North Pacific Ocean. In: Behavior of Marine Mammals, Vol. 3, Cetaceans. H.E. Winn and B.L. Ollar, editors. Plenum Press, New York, NY. pp. 45-83. Morris, B.F., M.S. Alton, and H.W. Braham 1983 Living marine resources of the Gulf of Alaska: a resource assessment for the Gulf of Alaska/ Cook Inlet proposed oil and gas lease sale 88. NOAA Technical Memorandum NMFSF/ AKR-5. 231 pp. Morrison, P., M. Rosenmann, andJ.A. Estes 1974 Metabolism and thermoregulation in the sea otter. Physiological Zoology. 47:218-229. Murie, O.J. 1940 Notes on the sea otter. Journal of Mammalogy 21:119-131. Marine Mammals 555 Murie, (). 1959 Fauna of the Aleutian Islands and Alaska Pen- insula. North American Fauna No. 61. U.S. Department of the Interior, Washington, D.C pp. 1-364. Murray, N. and F. Fay 1979 The white whales or belukhas, Delphinapterus leucas, of Cook Inlet, Alaska. International Whaling Commission Working Document SC/31/SM12. 6 pp. Nasu, K. 1974 Movements of baleen whales in relation to hvdrographic conditions in the northern part of the North Pacific Ocean and the Bering Sea. In: Oceanography of the Bering Sea. D.W. Hood and EJ. Kelley, editors. Occasional Publication No. 2, Institute of Marine Science, University of Alaska, Fairbanks, AK. pp. 345-361. Nemoto, T. 1957 Foods of baleen whales in the northern Pacific. Scientific Report of the Whales Research Institute 12:33-89. Nemoto, T. 1959 Food of baleen whales with reference to whale movements. Scientific Report of the Whales Research Institute 14:149-290. Nemoto, T. and T. Kasuya 1965 Foods of baleen whales in the Gulf of Alaska of the North Pacific. Scientific Report of the Whales Research Institute 19:45-51. Nerini, M. 1984 A review of gray whale feeding ecology. In: The Gray Whale Eschrichtius robustus. M.L.Jones, S.L. Swartz, and S. Leatherwood, editors. Aca- demic Press, Orlando, FL. pp. 423-450. Newby, T.C. 1982 Life history of Dall's porpoise (Phocoenoides dalli, True 1885) incidentally taken by the Japa- nese high seas salmon mothership fishery in the northwestern North Pacific and western Bering Sea, 1978 to 1980. Ph.D. Dissertation, University of Washington, Seattle, WA. 150 pp. Nishiwaki, M. 1966 Distribution and migration of the larger ceta- ceans in the North Pacific as shown byjapanese whaling results. Collected Reprints of the Ocean Research Institute, University of Tokyo No. 5 (contribution No. 69). pp. 103-123. Nishiwaki, M. 1972 General biology. In: Mammals of the Sea: Biology and Medicine. S. Ridgway, editor. Charles C. Thomas, Springfield, IL. pp. 3-20. Nishiwaki, M. and C. Handa 1958 Killer whale caught in the coastal waters off Japan for recent ten years. Scientific Report of the Whales Research Institute 13:85-96. Nishiwaki, M. and N. Oguro 1971 Baird's beaked whales caught on the coast of Japan in recent 10 years. Scientific Report of the Whales Research Institute 23:111-122. Nishiwaki, M. and N. Oguro 1972 Catch of Cuvier's beaked whales off Japan in recent years. Scientific Report of the Whales Research Institute 24:35-41. Ohsumi, S. 1965 Reproduction of the sperm whale in the north- west Pacific. Scientific Report of the Whales Research Institute 19:1-35. Ohsumi, S. 1966 Sexual segregation of the sperm whale in the North Pacific. Scientific Report of the Whales Research Institute 20:1-16. Ohsumi, S. 1980 Catches of sperm whales by modern whaling in the North Pacific. Report of the International Whaling Commission Special Issue 2:11-18. Ohsumi, S. and S. Wada 1974 Status of whale stocks in the North Pacific, 1972. Report of the International Wlialing Commis- sion 24:114-126. Ohsumi, S., M. Nishiwaki, and T. Hibiya 1958 Growth of fin whales in the North Pacific. Scien- tific Report of the Whales Research Institute 13:97-133. Okutani, T. and T. Nemoto 1964 Squids as the food of sperm whales in the Ber- ing Sea and Alaskan Gulf. Scientific Report of the Whales Research Institute 18:111-122. Omura, H. and O. Sakiura 1956 Studies on the little piked whale from the coast of Japan. Scientific Report of the Whales Research Institute 11:1-37. Perrin, W.F., editor 1982 Report of the workshop on identity, structure and vital rates of killer whale populations. Report of the International Whaling Commission 32:617- 631. Pike, G.C. 1962 Migration and feeding of the gray whale (Eschrichtius gibbosus). Journal of the Fisheries Research Board of Canada 19:815-838. 556 Biological Resources Pike, G.C. and LB. MacAskie 1969 Marine mammals of British Columbia. Fish- eries Research Board of Canada Bulletin 171. 54 pp. Pitcher, K.W. 1981 Prey of the Steller sea lion, Eumetopiasjubatus, in the Gulf of Alaska. Fishery Bulletin (U.S.) 79:467-472. Pitcher, K.W. 1985 Harbor seal (Phoca vitulina richardsi). In: Marine Mammals Species Accounts. J.J. Burns, K.J. Frost, and L.F. Lowry, editors. Wildlife Technical Bul- letin No. 7, Alaska Department of Fish and Game, Juneau, AK. pp. 65-70. Pitcher, K.W. and D.G. Calkins 1979 Biology of the harbor seal, Phoca vitulina rich- ardsi, in the Gulf of Alaska. Research Unit 229. Environmental Assessment of the Alaskan Continen- tal Shelf, Final Reports of Principal Investigators 19:231-310. Pitcher, K.W. and D.G. Calkins 1981 Reproductive biology of Steller sea lions in the Gulf of Alaska. Journal of Mammalogy 62:599-605. Pitcher, K.W. and D.C. McAllister 1981 Movements and haulout behavior of radio- tagged harbor seals (Phoca vitulina). The Cana- dian Field-Naturalist 95:292-297. Pitcher, K.W. and F.H. Fay 1982 Feeding by Steller sea lions on harbor seals. The Murrelet 63:70-71. Prescott, J.H. and P.M. Fiorelli 1980 Review of the harbor porpoise (Pho- coena phocoena) in the U.S. northwest Atlantic. Final report, Marine Mammal Commission Contract MM8AC016, U.S. Marine Mammal Commission, Washington, D.C. 64 pp. Reilly, S. 1981 Population assessment and population dynam- ics of the California gray whale (Eschrichtius robustus). Ph.D. Dissertation, University of Washington, Seattle, WA. 265 pp. Reilly, S.B. 1984 Assessing gray whale abundance: a review. In: The Gray Whale Eschrichtius robustus. M.L. Jones, S.L. Swartz, and S. Leatherwood, editors. Academic Press, Orlando, FL. pp. 3-32. Rice, D.W. 1963 Progress report on biological studies of the larger Cetacea in the waters off California. Norsk Hvalfangst-Tidende 52:181-187. Rice, D. 1968 Stomach contents and feeding behavior of killer whales in the eastern North Pacific. Norsk Hvalfangst-Tidende 57:35-38. Rice, D.W. 1974 Whales and whale research in the eastern North Pacific. In: The Whale Problem: A Status Report. W.E. Schevill, editor. Harvard Univer- sity Press, Cambridge, MA. pp. 170-195. Rice, D. 1978a Blue whales. In: Marine Mammals of Eastern North Pacific and Arctic Waters. D. Haley, editor. Pacific Search Press, Seattle, WA. pp. 30- 35. Rice, D. 1978b Beaked whales. In: Marine Mammals of Eastern North Pacific and Arctic Waters. D. Haley, editor. Pacific Search Press, Seattle, WA. pp. 89- 95. Rice, D.W. 1978c Sperm whales. In: Marine Mammals of Eastern North Pacific and Arctic Waters. D. Haley, editor. Pacific Search Press, Seattle, WA. pp. 83- 87. Rice, D.W. and A.A. Wolman 1971 The life history and ecology of the gray whale (Eschrichtius robustus). American Society of Mammalogy Special Publication No. 3. 142 pp. Rice, D.W. and A.A. Wolman 1981 Summer distribution and numbers of fin, humpback and gray whales in the Gulf of Alaska. Research Unit 592. Environmental Assess- ment of the Alaskan Continental Shelf, Final Reports of Principal Investigators 20:1-46. Rugh,DJ. 1984 Census of gray whales at Unimak Pass, Alaska, November-December 1977-1979. In: The Gray Whale Eschrichtius robustus. M.L.Jones, S.L. Swartz, and S. Leatherwood, editors. Academic Press, Orlando, FL. pp. 225-248. Rugh, D. and H. Braham 1979 California gray whale {Eschrichtius robustus) fall migration through Unimak Pass, Alaska, 1977. Report of the International Whaling Commission 29:315-329. Sandegren, F.E. 1970 Breeding and maternal behavior of the Steller sea lion (Eumetopiasjubatus) in Alaska. M.S. The- sis, University of Alaska, Fairbanks, AK. 138 pp. Scattergood, L.W. 1949 Notes on the little piked whale. The Murrelet 30:3-16. Makini Mammais 557 Scheffer, V.B. 1949 The Dall porpoise, Ptiocoenoides dalli, in Alaska. Journal of Mammalogy 30:116-121. Scheffer, V.B. 1950 The food of the Alaska fur seal. U.S. Fish and Wildlife Service Leaflet No. 329. 16 pp. Scheffer, V.B. 1953 Measurements and stomach contents of eleven delphinids from the northeast Pacific. The Murrelet 34:27-30. Scheffer, V.B. 1976 The status of whales. Pacific Discovery 29:2-8. Scheffer, V. and J. Slipp 1948 The whales and dolphins of Washington State with a key to the cetaceans of the west coast of North America. American Midland Naturalist 39:257- 337. Schneider, K..B. 1972 Reproduction in the female sea otter. Project progress report, Federal Aid in Wildlife Resto- ration Project W-17-4. Alaska Department of Fish and Game, Juneau, AK. 36 pp. Scordino, J. 1985 Studies of fur seal entanglement 1981-84, St. Paul Island, Alaska. In: Proceedings of the Work- shop on the Fate and Impact of Marine Debris, November 27-29, 1984, Honolulu, HI. R.S. Shomura and H.O. Yoshida, editors. NOAA Technical Memorandum NMFS-SWFC-54. pp. 278-290. Seaman, G.A. andJ.J. Burns 1981 Preliminary results of recent studies of belukha whales in Alaskan waters. Report of the Interna- tional Whaling Commission 31:567-574. Sergeant, B.E. 1969 Feeding rates of Cetacea. Fiskeridirektoratets Skrifter Serie Havunderso'kelser 15:246-258. Sergeant, D.E. 1973 Biology of white whales {Delphinapterus leucas) in western Hudson Bay. Journal of the Fisheries Research Board of Canada 30:1065-1090. Sergeant, D.E. and P.F. Brodie 1975 Identity, abundance, and present status of white whales, Delphinapterus leucas, in North America. Journal of the Fisheries Research Board of Canada 32:1047-1054. Shomura, R.S. and H.O. Yoshida, editors 1985 Proceedings of the Workshop on the Fate and Impact of Marine Debris, 27-29 November 1984, Honolulu, HI. NOAA Technical Memorandum NMFS-SWFC-54. 580 pp. Slepstov, M. 1961 Smith, T. 1980 [Fluctuations in the number of whales of the Chukchi Sea in various years.] Trudy Instituta Morfologii Zhirotnykh Akademii NAUK SSSR 34:54-64. (Translated by U.S. Naval Oceanographic ( )f lice, Washington, D.C., 1970, Translation 478. 18 pp.) Catch of male and female sperm whales l>\ 2-degree square by Japanese pelagic whaling fleets in the North Pacific 1966-77. Report of the International Whaling Commission Special Issue 2:263-275. Smith, G.J.D. and D. Gaskin 1974 The diet of harbor porpoises (Phocoena phocoena (L.)) in coastal waters of eastern Canada, with special reference to the Bay of Fundy. Canadian Journal of Zoology 52:777-782. Spalding, D.J. 1964 Comparative feeding habits of the fur seal, sea lion, and harbour seal on the British Columbia coast. Fisheries Research Board of Canada Bui letin 146. 52 pp. Stroud, R.K., C.H. Fiscus, and H. Kajimura 1981 Food of the Pacific white-sided dolphin, Lagenorhynchus obliquidens, Dall's porpoise, Pho- coenoides dalli, and northern fur seal, Callorhinus ursinus, off California and Washington. Fishery Bulletin (U.S.) 78:951- 959. Tillman, M. 1975 Assessment of North Pacific stocks of whales. Marine Fisheries Review 31(10):l-4. Tillman, M. 1976 Trends in abundance of sperm whales in the area of the North Pacific. Report of the Interna- tional Whaling Commission 27:343-350. Tillman, M. 1977 Estimates of population size of the North Pacific Sei Whale. Report of the International Wlialing Commission Special Issue 1:98-106. Tomilin, A.G. 1957 Kitoobraznye [Cetacea]. Vol. 9 of Zveri SSSR i Prilezhashrhikh stran [Mammals of the U.S.S.R. and Adjacent Countries]. Izedatel'stvo Akademi Nauk SSSR, Moscow. 756 pp. (Translated by Israel Program for Scientific Translations, 1967, 717 pp., NTIS No. TT 65-50086.) 558 Biolocical Resources Uchida 1985 The types and estimated amounts of Fishnet deployed in the North Pacific. In: Proceedings of the Workshop on the Fate and Impact of Marine Debris. R.S. Shomura and H.O. Yoshida, editors. NOAA Technical Memorandum NMFS- SWFC-54. pp. 37-108. Von Ziegesar, O. and CO. Matkin 1985 A catalogue of humpback whales in Prince William Sound, Alaska identiFied by fluke pho- tographs between the years 1977 and 1984. Unpublished report, National Marine Fish- eries Service, National Marine Mammal Labo- ratory Contract No. 41USC252. 24 pp. Wahl, T.R. 1977 Sight records of some marine mammals off- shore from Westport, Washington. The Murrelet 58:21-23. Wolman, A. 1978 Humpback whale. In: Marine Mammals of East- ern North Pacific and Arctic Waters. D. Haley, editor. Pacific Search Press, Seattle, WA. pp. 47-53. Zimushko, V.V. and S.A. Lenskaya 1970 Feeding of the gray whale (Eschrichtins gibbosus Erx.) at foraging grounds. Ekologiya 1:26-35. (Translated by Consultant's Bureau, Plenum Publishing Corporation, New York, NY, 1971. 8 pp.) Ecological Relations 18 Timothy R. Parsons Department of Oceanography University of British Columbia Vancouver, British Columbia, Canada Abstract Ecological relationships in the Gulf of Alaska are discussed separately for four zones: the open ocean, the continental shelf, the fjord, and the estuary. Estimates of primary-to-apex production have been made for each area. The open ocean apex production was estimated to be the lowest at 0.036 g C/m2y, while the continental slope waters (including the shelf break) was the highest at 2.4 g C/m2y. Also consid- ered in this chapter are other important regional properties that influence larval and juvenile fish survival, demersal production, and the physical processes governing pro- duction. Introduction This section formulates some general principles related to production mechanisms in the Gulf of Alaska. The pur- pose is twofold: 1) to integrate detailed descriptions of pro- duction mechanisms from previous chapters, and 2) to con- sider the physical environment as the forcing function for biological production, in order to show how production in different ecological zones may be qualitatively and quan- titatively related. From the great abundance of marine mammals, including whales, seals, and sea lions, and from evidence of formerly abundant sea otters and Steller's sea cows, it is apparent that there is a rich flow of nutrient-laden Pacific waters moving onto the south Alaskan coast. The rea- sons why this highly productive zone exists are the subject of this discussion. Physical Considerations The general physical oceanography of the Gulf of Alaska is described by Reed and Schumacher (Ch. 3, this volume). The area is dominated by a large cyclonic gyre (the Alaskan Gvre) that is formed when part of the Subarctic Current moves east towards Vancouver Island, and then moves on around the Gulf in a northwesterly direction to form the Alaska Current (Favorite, Dodimead, and Nasu 1976). Meso- scale eddies occur as part of the Alaskan Gyre. These eddies, which have diameters of 200 to 300 km, are formed along the coast of Alaska and may be either cyclonic or anti- cyclonic (Tabata 1982: Rover, Hansen, and Pashinski 1979; and Feelv, Baker, Schumacher, Massoth, and Landing 1979). In addition to these current systems, both high wind stress and a large volume of freshwater runoff affect local coastal conditions. Wind-induced convergence (downwell- ing) dominates the Alaskan Shelf from October to March/ April, and relatively weak coastal upwelling occurs from May to September (Ingraham, Bakun, and Favorite 1976; Royer et al. 1979). In coastal areas, the quantity of freshwater runoff determines the depth of the seasonal pycnocline. Coastal water transparency is affected by both the volume of the runoff and the amount of silt carried by the runoff. Fur- ther discussion of these aspects can be found in Sambrotto and Lorenzen (Ch. 9, this volume). In oceanic areas, the depth of mixing depends largely on the establishment of a seasonal thermocline. Physical parameters that affect biological production at the primary level are changes in: 1) solar radiation 2) mixed layer depth 3) extinction coefficient 4) intensity of upwelling or downwelling 5) in coastal areas, bottom topography and tidal velocity. Solar radiation in the Gulf of Alaska increases from less than 100 g cal/cm2d in winter to more than 600 g cal/cm2d in summer. Increased radiant energy affects productivity by establishing a seasonal thermocline and by increasing pho- tosynthesis. With fluctuations in the thermocline, the mixed layer in the open ocean extends to —150 m during the winter, but rises to less than 50 m during the summer. In coastal areas, the mixed-layer depth is governed by the 561 562 Biological Resources halocline, so that in some areas, a mixed layer of only a few meters may support some primary production throughout the year. The amount of production depends on the amount of suspended sediment in the water, because the suspended sediment effectively limits light levels for photosynthesis. Combining radiation and mixed layer factors with Sverdrup's (1953) critical depth model, Parsons and LeBrasseur (1968) produced a general explanation for the timing of the spring bloom in the Gulf of Alaska. Their model indicates that the spring bloom could be initiated in coastal regions by a combination of physical factors during February/March, but that in the central oceanic portion of the Gulf, the spring bloom would not occur until at least May. Subsequent studies have tended to support the general form of this prediction {e.g., Anderson, Parsons, and Stephens 1969; Parsons and Anderson 1970). However, in coastal areas (particularly over the shelf break) physical fac- tors such as local river discharge, tidal mixing, bottom topography, the extinction coefficient, and the intensity of wind-induced upwelling or downwelling alter the above prediction. Many recent analyses of nearshore production processes have employed Simpson and Hunter's (1974) stratification parameter to indicate zones of persistently high primary production. In this model, bottom depths and average cur- rent velocities are employed to show areas where stability and turbulence interface. This is valuable because primary productivity reaches a peak in zones between the two pro- cesses. A local example of this diagnosis is given by Perry, Dilke, and Parsons (1983) for Hecate Strait. In general, stud- ies using the stratification parameter model have shown that both the shelf -break region of the continental shelf and the shallow sill areas (e.g., in the mouth of fjords, Burrell, Ch. 7, this volume) are areas of persistently high production, especially during the summer months when many local waters are depleted of nutrients by the presence of the strong pycnocline. The general effects of the physical properties discussed above are summarized in Figure 18-1. The figure covers four ecological zones characteristic of the marine ecology of the Gulf of Alaska. These zones are: 1) the estuarine habitat, including a relatively narrow margin in the intertidal zone, 2) the fjord, 3) the continental shelf and shelf break, and 4) the open ocean. Seasonal and geographical differences in both primary production and the food chain of these areas can be described using existing data. However, longer-term cyclical events may substantially alter these production processes. Examples of these events include: 1) intrusions of warm water along the coast (Tully and Barber 1960; Gardner 1982), 2) changes in the strength and position of the major current systems (Wickett 1966), or 3) occurrences of large-scale, low-frequency baroclinic waves (Mysak, Hsieh, and Parsons 1982). The Definition of Ecological Zones The four ecological zones illustrated in Figure 18-1 can be defined on the basis of their physical properties. Of these properties, water depth and the timing of the seasonal pyc- Approximate Annual Primary Productivity Of Plankton 50gC/m2 300gC/m2 200 gC/m2 150gC/m2 u 20 Seasonal Pycnoci.ines (o,) f\ / 40 Winter Downwelling Mixing, jl (Convergence) ![J 70- 100 Summer Upwelling ^V (Divergence^.-^^ ^ ^^ ' 200 - Permanent ^ \Pycnocline 500 / 1000- 2000- 3000 4000- 5000 Open Ocean Slope Inner Sill Estuary (and Intertidal) Shelf SiU Fjord Topographic Regions Figure 18-1. Production zones of the Gulf of Alaska showing rel- ative pycnoclines, approximate annual primary productivities, and topographical sections for the four zones. nocline are probably the two most decisive factors in deter- mining primary production. The estuarine pycnocline area is strongly developed throughout the year, but varies in its extent depending on river flow. This pycnocline allows primary productivity to occur very early in the spring or even throughout the year. However, large silt loads generally inhibit the total annual primary productivity by severely reducing light penetra- tion. Seaward from the estuary, strong seasonal ther- moclines form over deep fjord basins. The thermoclines limit vertical mixing and lead to nutrient depletion in the euphotic zone throughout the summer. They also cause the formation of a subsurface chlorophyll maximum at the nutricline. Thermoclines may be eroded by turbulent tidal mixing in the vicinity of shallow sills, resulting in a biological front that gives rise to continued high production throughout the summer. The relatively shallow continental shelf is also sub- ject both to large-scale tidal mixing near the shelf break and to wind-induced nearshore upwelling and downwelling. This mixing pattern on the edges of the shelf and thermal stabilization beyond the shelf lead to very high primary pro- ductivity over a large area between the shelf break and the coastline. In the open ocean, storm activity delays formation of the seasonal thermocline, and this suppresses primary productivity until late in the spring. Open-ocean nutrients are seldom limiting due to heavy grazing pressure on the phytoplankton throughout the summer (McAllister, Par- sons, and Strickland 1960). Although the total annual pri- mary productivity of the oceanic area is low, the pelagic Ecological Relations 563 food-chain efficiency is probably very high relative to coastal regions, where much of the primary productivity sinks to the sea floor and may undergo bacterial decomposi- tion to form part of a benthic food chain. The basic difference in the cycle of phytoplankton and zooplankton in the coastal and oceanic regions of the Gulf can be seen in Figure 18-2 taken from Parsons and LeBrasseur (1968) and from Parsons, LcBrasseur, and Bar- raclough (1970). In the oceanic Pacific, increases in the dom- inant zooplankton species (Neocalamis plumchrus) parallel increases in primary productivity, and chlorophyll a seldom increases above —0.5 mg/m*. In coastal regions however, primary production outstrips zooplankton growth and large blooms of phytoplankton result in sporadic chlo- rophyll a values of ~ 20 mg/m3. The Estuarine/Intertidal Zone The estuarine/intertidal zone is a narrow region along the shoreline of the Gulf of Alaska. If you include the estuarine marsh grasses and algal mat communities and the intertidal kelp and Funis beds, the annual primary produc- tivity of this zone is very high ( > 1,000 g C/m2y in terms of macrophyte production alone) (Mann 1982). However, much of this production passes through a detrital food chain and consequently there is a considerable loss of energy in converting the autotrophic production into bac- teria, fungi, and protozoa. The chief beneficiaries of this production are benthic invertebrates such as clams, amphi- pods, harpacticoid copepods, and nematodes. These inver- tebrates subsequently become food for crabs, shrimp, and flatfish as well as for the juvenile and larval stages of many commercial fish species such as salmon and herring. The primary production of plankton in estuaries may be quite low because silt attenuates the available light. Lar- rance, Tennant, Chester, and Ruffio (1977) found, for exam- ple, that nearshore waters of Prince William Sound had a mean daily productivity of 163 mg C/m-'d and a total sus- pended load of 1.12 mg/1, while offshore, productivity aver- Phytoplankton Coastai Herbivorous Zooplankton * I z < Oceanic /" ^ \ £ / \ w / \ > / \ < / \ bj / \ a* / N / ^— - V^ Jan Feb mar Apr May Ji a Jin Aug Sep Oct Nov dec. Figure 18-2. The general relationship between phytoplankton and herbivorous zooplankton in the coastal and oceanic regions of the Gulf of Alaska. aged 538 mg C/m-'d with a suspended load of 0.31 mg/1. Sam- pling in Howe Sound on the coast of British Columbia produced similar results. Stations under the direct influ- ence of the Squamish River had a mean annual production of —140 g C/m2y, while stations at the mouth of the same inlet had an annual primary production of —400 g C/m2y (Stockner, Cliff, and Buchanan 1977). In addition to containing high silt levels, freshwater runoff from the Alaskan coastal range is generally devoid of nutrients other than silicate (Kinney, Groves, and Button 1970). However, some rivers carry higher loads of organic matter than seawater and this gives rise to high bacterio- plankton production off the mouth of a river where the freshwater and nutrient-rich saltwater mix (Albright 1983; Atlas and Griffiths, Ch. 8, this volume). Estuaries and intertidal waters serve several important functions in supporting higher trophic levels. Bird popula- tions, particularly migrant shore birds, ducks, and geese, are ecologically tied to this zone. Anadromous fish such as salmon and lamprey are dependent on the estuary as a gateway to the rivers. The total fisheries production of this zone is low because the area is relatively small, although marsh grass, eelgrass, and seaweed beds all serve as impor- tant nursery areas for some species. The principal non- migratory fisheries of interest to man are the shellfish such as clams and crabs. The Fjord A recent review of fjord ecology has been given by Mat- thews and Heimdal (1980). Pickard and Stanton (1980) have described the general physical characteristics of fjords, and fjord dynamics are described by Burrell (Ch. 7, this volume). Alaskan fjords are characterized by Matthews and Heimdal (1980) as having well-developed pycnoclines at the head with less well-developed pycnoclines at the mouth where tidal exchange over a shallow sill may cause some mixing. Mixing at the mouth of a fjord forms a front of high biolog- ical activity due to the entrainment of nutrients from below the pycnocline during the summer months (e.g., Parsons, Perry, Nutbrown, Hsieh, and Lalli 1983). A third sub-zonal area of some fjords may exist if an inner sill isolates the head of the fjord from the main basin. This inner basin (some- times called a poll) may be partially filled with riverine sedi- ment. The poll community is generally dominated by nanoflagellates, small zooplankton, small fish, and medusae. In contrast, the main basin of the fjord is generally charac- terized by diatoms producing a summer chlorophyll max- imum at depth, and by large calanoid copepods, eupha- usiids, and substantial fish stocks (e.g., lingcod and hake). Thus the ecology of a typical Alaskan fjord may range from a highly productive region at the mouth and progress through the more stable waters of the main basin of the fjord to a region of low productivity at the head (Matthews and Heimdal 1980). As an example, the mouth of Cook Inlet, and particularly Kachemak Bay, appears to have the typical properties of a frontal zone with primary productivity val- ues of 1 to 7 g C/m2d from June through August when pri- mary productivity in many other regions is much lower due to nutrient depletion (Larrance and Chester 1979). 564 Biological Resources The Continental Shelf and Shelf Break The continental shelf zone (that area out to 200-m depth) is the most productive zone in the Gulf of Alaska. This is due in part to topographical features of the shelf break and in part to its relatively extensive area. Other continental shelves throughout the world are similarly productive (Pingree 1978), although in comparison to the North Atlan- tic shelf, the Pacific Alaskan shelf is narrow. The higher pro- ductivity of the shelf break region is illustrated in Figure 18-3, taken from Larrance et al. (1977). The figure shows results of an autumn survey of daily productivity values. Val- ues along the 183-m contour ran three to five times higher than values measured in the nearshore region. Similar observations have been made for British Columbian waters. The reasons for this zone of high production have been discussed (Mackas 1984; Denman, Mackas, Freeland, Austin, and Hill 1981; and Freeland and Denman 1982). The mecha- nisms leading to high production involve physical processes that contribute to upwelling. These mechanisms include 1) the entrainment of nutrient-rich deep water into the sur- face layer due to the offshore movement of freshwater; 2) wind-induced upwelling, and 3) upwelling caused when a major offshore current interacts with topographic irreg- ularities along the shelf break. The upwelling activity along the shelf break appears to be seasonally reversible. It A. 140 Primary productivity mgC/m-d Benthic invertebrate catch rate | CPUE>50kg/h becomes a downwelling (convergent) system for six to eight months during the winter. The reversal to the predominant downwelling system is due to a shift in wind direction (Ingraham et al. 1976; Royer 1981). Winds are primarily responsible for the summer upwelling on the Alaskan shelf break. However, some areas of the shelf may be subject to this seasonal upwelling for relatively brief periods {i.e., one or two months, Reed and Schumacher, Ch. 3, this volume). In these regions tidal mixing and the interaction of along-shore currents with subsurface topography may be the dominant force leading to the influx of nutrients into the euphotic zone during the summer. An example of tidal mixing as a force is shown in Reed and Schumacher's Figure 3-10, where the stability of the water column over Portlock Bank is dissipated by tidal flow. An example of a current interacting with subsurface topography appears in their Fig- ure 3-8, where an intense, permanent eddy is produced in the lee of Kayak Island. Microflagellate abundance increases from ~104 to 105 cells/1 as one moves from the shelf area to the open ocean zone. Conversely, diatoms form the basis for nearshore plankton blooms (Larrance et al. 1977). From data presented by Larrance (1971) on daily productivities between 160 and 180°W, it is apparent that in nearshore oceanic areas pri- mary productivities of more than 2,000 mg C/m2d could occur from June to August, while offshore the daily primary productivity is generally less than 300 mg C/m2d. If the annual primary productivity for the central oceanic zone is -50 g C/m2y (McAllister 1969), then the near- shore shelf zone must have a minimum production of ~ 300 g C/m2y based on the six-fold daily differences observed by Larrance (1971). This value is similar to recent measure- ments of primary productivity on the continental shelf made in Hecate Strait and Queen Charlotte Sound, which ranged from 1 to 5 g C/m2d during July 1983 (J.R. Forbes, Institute of Ocean Sciences, Canada, pers. comm, 1983). The general form of increased biological production over the shelf area is illustrated in Figures 18-3A and B, which show two data sets: 1) primary productivity (mg C/m2d), and 2) catch per unit effort (CPUE) of benthic orga- nisms. Maximum primary productivity tends to occur along the shelf break near the 200-m contour while maximum benthic production is on the shelf. These patterns are con- sistent with the concept that water moves onto the shelf dur- ing summer, increasing the primary production available to the benthos in shallow areas (Feder andjewett, Ch. 12, this volume). A similar frontal zone is shown in Figure 18-4 from Perry et al. (1983). The cross-sectional data, collected during June from the shelf break on the inside passage of Hecate Strait at approximately 54°N and 130 to 132°W, illustrate that chlorophyll a, nutrients, and zooplankton generally increase in the vicinity of the shelf break where water depth increases from ~ 50 to 300 meters. Figure 18-3. (A) Primary productivity on the Gulf of Alaska Shelf, October to November 1975. (Modified from Larrance et al. 1977.) (B) Areas of benthic invertebrate concentrations on the Gulf of Alaska Shelf expressed as relative catch per unit effort (CPUE). (Modified from Ronholt, Shippen, and Brown 1978.) The Open Ocean The open ocean ecosystem of the Gulf of Alaska is charac- terized by a permanent halocline at depths near 150 m as well as by a seasonal thermocline which is established in April or May and persists until September or October (Tully Ecological Relations 565 Phytoplankton and Nutrients Diatoms * 7 -~ be 6 J B. ZOOPLANKTON andTemperatcre/Salinty Salinity "-..Temperature Noncopepod ""* ~~ Vr-"" Zooplankton "*• ^_ — — _-V \ 200 5 C. Depth Structure and Temperature Profiles v, o 50 100 150 200 250 300 15 Station Number Figure 18-4. Cross-sectional data collected during June from the shelf break front in Hecate Strait at approximately 54°N and 130 to 132°W. (Modified from Perry et al. 1983.) 1965). Once the seasonal thermocline is established, net pri- mary productivity increases from less than 50 mg C/m2d to more than 300 mg C/m-d between March and June/July (McAllister 1969). Intense grazing by zooplankton, which is in phase with the increase in primary production, keeps sur- face waters from becoming nutrient limited. Chlorophyll a levels are —0.5 mg/m3 and the nitrate concentrations are above 5 |i.M, even during the most productive months (June and July) (McAllister et al. 1960; Parsons and LeBrasseur 1968; and Anderson, Parsons, and Stephens 1969). The major group of primary producers in the subarctic ocean waters of the Gulf of Alaska are 8 to 16 urn-sized flagellates (Parsons 1972) belonging to the Haptophyceae, Dino- phyceae, and Cryptophyceae; the dominant diatom found in the area was Denticulopsis seminae (Booth 1975; Taylor and Waters 1982). The standing stock of zooplankton is strongly linked to the seasonal timing of the phytoplankton bloom. The annual production of zooplankton at Ocean Station 'P' (50°N, 145°W) has been estimated to be between 4 and 13 gC/m2 (McAllister 1969). Knowledge of the critical depth and depth of mixing lets one predict the timing of the zooplankton bloom in the Gulf of Alaska (Parsons and LeBrasseur 1968) (Fig. 18-5). This model shows that net primary production becomes positive from February to May. Due to the close coupling between increased primary productivity and zooplankton standing stocks, increases in zooplankton coincide with the general advance of the spring bloom from the coast (in March) to the center of the Gulf (in May). The open ocean ecosystem is a major feeding ground for salmon, particularly the sockeye. The two principal species of zooplankton (Neocakinus crlstatus and N. plumchrvs) arc not directly consumed by salmon to any large extent. Rather, copepods are principally consumed by euphausiids, squid, and myctophids, which in turn are the principal food of salmon. As much as 20% of the annual zooplankton produc- tion in the open-ocean environment of the Gulf of Alaska is indirectly required for salmon growth (LeBrasseur 1972). Large planktivorous predators that prey directly on the copepod biomass include baleen whales and some fish. Bar- raclough, LeBrasseur, and Kennedy (1969) documented the occurrence of dense swarms of copepods that would be attractive to planktivores and result in intensive seasonal grazing. Annual Carbon Budget for the Ecological Zones Estimates for the approximate carbon budget for the four ecological zones are shown in Figure 18-6. Primary pro- ductivity values have been taken from the previous discus- sion, and in the case of the estuarine food chain, the com- bined contribution of allochthonous organic carbon (from the land) and macrophyte detritus is estimated at 100 g C/m2y. This addition is based on a value derived by Stephens, Sheldon, and Parsons (1967) for a similar habitat Station P Wet WeicHI Of Copepods Copepod wet weigh Timing ol the spri Interpolated region of maximum copepod w el weight during Ap: Figure 18-5. Timing of the spring bloom in the Gulf of Alaska. General progress of the spring bloom in oceanic waters is pre- dicted from the Sverdrup model. Actual data on zooplankton standing stock are shown for the month of April. Zooplankton standing stock at Station P in the center of the Gulf (inset). (Modified from Parsons and LeBrasseur 1968.) 566 Biological Resources Pi im.in production 150 \ll(u hthonous carbon 100 30 I lerbivores — e.g. larvaceans, tintinnids, copepods, mussels — filter feeders 3.6 Apex pelagic and epifaunal predators — e.g. herring, seasiars ■♦-0.36 Detritus — 152. Macrofauna — e.g. mollusks, polychaetes — deposit feeders Meiofauna and microfauna- e.g. bacteria, nematodes 15 Apex demersal predators- e.g. crab, flounder, sculpin -»-0.87 Primary production 200 184 Herbivores — e.g. copepods, euphausiids — filter feeders 0 18.4 Apex pelagic predators — e.g. hake, pollock, herring, smelt, whales ♦-1.84 Macrofauna — e.g. sea urchins, polychaetes 2.6 Meiofauna and microfauna — e.g. bacteria, nematodes 5.0 Apex demersal predators- e.g. crabs, cod ♦-0.26 o _ j- Primary production 300 240 Herbivores — e.g. copepods. euphausiids — filter feeders 16.8 Apex pelagic predators — e.g. perch, herring, pollock, birds, sand lance ♦►1.68 Macrofauna — e.g. mollusks, polychaetes — deposit feeders -*. 7.2 Meiofauna and microfauna- e.g. bacteria, nematodes 12 Apex demersal predators- e.g. sole, cod, seastars ♦►0.72 Primary production 49.5 fc Microzooplankton — 1A* Macrozooplankton- 0.61 _ Apex planktivores — 50 4.95/ 5.45 ^ e.g. protozoa e.g. copepods, euphausiids e.g. whales, pomfret < u ' y 013^^-^- 0.008 0 ~1 Planktivores — e.g. myctophids --^(l.(l()5 „ Piscivores — e.g. squid 0.0005 _ Apex predators — e.g. salmon a. o Detritus - Bathypelagic and benthic 0.55 Bathypelagic planktivores 0.055 Apex bathypelagic predators * detritivores »- 0.00085 0.0055 Figure 18-6. Estimated production of organic carbon (g C/m2y) from primary to apex producers in the four ecological zones of the Gulf of Alaska. in the Strait of Georgia. Larrance and Chester (1979) found 40 to 60 g C/m2 sedimented at the mouth of Cook Inlet, of which nearly 90% originated on land. The amount of primary productivity that is sedimented as phytodetritus has been estimated using Suess' (1980) rela- tionship. This relationship gives the fraction of primary pro- ductivity that sinks through the water column as a function of water depth. Water depths of 10, 300, 100, and 3,000 m were assumed for the estuary, fjord, shelf, and open ocean, respectively. Sedimented phytodetritus, together with the allochthonous carbon in the estuary, has been labeled 'detritus' and has been assigned to the benthic community. The partitioning of the detritus into direct consumption by either macrofauna or meiofauna and microflora is based on Schwinghammer's (1981) observation that the total biomass of meiofauna and microflora (including bacteria) is about twice that of the macrofauna. However, while different- sized groups of benthic organisms compete for the same food resource (i.e., sedimented organic matter), Reise (1979) has shown that macrofauna in their role as nonspecific deposit feeders consume many of the microorganisms in sediments. For this reason, the detrital pool has been shared proportionally 2 to 1 between micro- and macrofauna, but the microorganisms have then been shunted through the macrofauna as an additional food supply to this trophic level. Demersal predators such as crabs, sole, cod, and sea- stars have been placed at the top of the benthic food chain (Feder and Jewett, Ch. 12, this volume). In general, the demersal predators represent the production of epifauna, while the infauna and flora are represented by the previous step in the benthic food chain. All ecological efficiencies for the benthic food chain have been assumed to be 10 percent. However, this value may be too high for the initial conversion of detritus and too low for benthic carnivores. While the use of an average ecological efficiency compensates for this difference, the introduction of fewer or more steps in the food chain could alter the pro- duction of apex predators. Ecological Relations 567 That portion of the primary production that is not sedi- mented is assumed to be consumed largely by planktonic herbivores, and, in the case of estuarine/coastal environ- ments, by attached filter feeders such as mussels. The ecolog- ical efficiency for the conversion of primary productivity to secondary productivity has been based on the level of pri- mary productivity, dishing (1971) showed that as primary productivity increased, conversion efficiency decreased. Using this relationship, ecological efficiencies have been calculated by dividing the annual primary productivity by 200 days to give: 1) the approximate daily productivity, and 2) the transfer efficiencies interpolated from Gushing (1971) as 15% for the open ocean, 12% for the estuary, 10% for the fjord, and 7% for the shelf. Since the assimilation ratio decreases exponentially with food intake (Gaudy 1974), it is expected that the low ecologi- cal efficiency of 7% on the shelf would lead to the produc- tion of fecal pellets that are rich in organic material. Using Gaudy's relationship, the assimilation efficiency of her- bivores at the phytoplankton densities typically found on the shelf has been approximated at 50 percent. This means a large fraction of the primary productivity sedimented as fecal pellets is available to the benthos (Hargrave, Phillips, and Taguchi 1976). The input of fecal material from the zoo- plankton community has been graded against assumed eco- logical efficiencies for each ecological zone, to give 90% assimilation at an ecological efficiency of 15%, and 50% assimilation at an ecological efficiency of 7 percent. Corres- ponding assimilation efficiencies are approximately 70% for the fjords and 85% for the estuaries. Any unassimilated fecal material has been added to the detrital pool. An ecological efficiency of 10% has been assumed for converting zooplankton to planktivorous fish. In the open ocean, it has been assumed that there are more steps in the food chain between phytoplankton and apex predator (Rvther 1969; Parsons and LeBrasseur 1970; and Sambrotto and Lorenzen, Ch. 9, this volume in reference to micro- zooplankton grazing). In addition, the divisions of her- bivore production, apex planktivores (e.g., whales), smaller piscivores (e.g., squid), and apex carnivores (e.g., salmon) have been based on LeBrasseur's (1972) suggestion that — 20% of the biomass of herbivore production served as food for salmon in the open ocean. The remainder of the herbivore production is consumed by a variety of species (OGSEAP Staff, Ch. 14, this volume), including baleen whales and pomfret. The ecological efficiency for the con- version of plankton to the latter group has been placed at 5% because of the high metabolic requirements of whales and because of the diversity of food items available to the oceanic apex predators such as pomfret. A summary of apex production is shown in Table 18-1. Walsh and McRoy (1986) estimated the apex production of the Bering Shelf as 0.65 g C/m2y based on 162 g C/m2y pri- mary productivity. Commercial fish production for the North Sea has been estimated as 0.66 g C/m2y based on a pri- mary production of 82 g C/m-y, while for Georges Bank the commercial fish production was estimated as 0.8 g C/m2y based on a primary production of 374 g C/m2y (Cohen, Brosslein, Sissenswine, Steimle, and Wright 1982). Table 18-1. Approximate apex production in the four ecological zones of the Gulf of Alaska. Ri (.ic >\ Primary Apkx Production Production (gC/m^y) Total. (gC/m^y) Demersal Pelagic (gC/m2y) Estuary 1 50 0.87" 0.36 1.23 Fjord 200 0.26 1 .84* 2.10 Slope 300 0.72a 1 .68- 2.40 Open Ocean 50 — 0.036 0.036 'Indicates fisheries which may be partly or extensively used by man (e.g. crabs, mollusks, herring, cod, perch, sole, and salmon). These values from the literature are generally lower than those calculated in Table 18-1 for the Alaskan continental shelf areas. There are probably several reasons for this. In the case of the Bering Sea estimates, the estimated primary productivity was nearly half that for the south Alaskan shelf. This estimate seems reasonable, since water turbulence, which affects the supply of nutrients, is greater along the narrow northern Gulf of Alaska shelf than it is on the wide Bering Sea shelf. The estimates of apex production for the North Sea and Georges Bank (Cohen et al. 1982) apply only to fish. A more important consideration, however, is the assumed coupling between primary production and fish production. These authors suggest that much of the very high primary produc- tion (374 g C/m2y) on Georges Bank is actually exported off the bank, and this gives a relatively low transfer efficiency to fish on the bank. In the North Sea, the primary production is much lower (82 g C/m2y) than on the south coast of Alaska (300 g C/m2y), but it is used as efficiently as on the Alaskan coast. This gives apex productions that are similar in both areas if one allows for the difference in primary production between the two areas. The annual estimated food required for marine birds (~5.5 x 105 mt) on the shelf (DeGange and Sanger, Ch. 16, this volume) represents about 5% of the total apex produc- tion. This estimate assumes that birds prey on fish and they are therefore feeding at a high trophic level. Similarly, it is estimated that sea lions on the shelf require —3.5 x 105mtof fish per year (Calkins, Ch. 17, this volume). This amount is about 3% of the apex shelf production. Fisheries Potential For apex predators (Fig. 18-6), production estimates are also estimates of the standing stock if one assumes an annual production-to-biomass (P/B) ratio (cf. Fig. 73 in Parsons, Takahashi, and Hargrave 1984). For some species, such as salmon, current harvest levels reach nearly 20% of the annual production. This harvest level may be sustainable for P/B ratios that are above 0.5. However, in general, the annual P/B ratio of subarctic apex species, including the wide variety of benthic predators, mammals and birds, is probably no more than 0.1. Furthermore, of this fraction, 568 Biological Resources which is required to replace the standing stock (B), a large part such as seastars, birds, and seals are not harvested by man. In addition, some commercial fish species may be underexploited due to the difficulties involved in har- vesting in certain locations such as on rough bottoms. The relatively high production of the fjord-sill environ- ment is of limited commercial importance since it encom- passes a relatively small area and is confined primarily to the frontal zones that occur at the mouth of certain inlets. How- ever, certain inlets such as Frederick Sound and Glacier Bay are well known for their high productivity because they serve as feeding grounds for the humpback whale. The most productive zone in the Gulf of Alaska is the shelf and slope area, both because of its high primary pro- ductivity and because of its relatively large area. If the total area of the Alaskan Shelf (from Dixon Entrance to 165°W, to a depth of 200 m) is approximately 3.15 x 1011 m2, then according to Table 18-1, the annual production of apex predators in this area is ~ 12 x 106 metric tons. Less than 2% of that tonnage is presently harvested. For slow-growing species, however, most of the production is required for replacement of adult stock (i.e., P/B ratio ~0.1), and it is doubtful that more than 10% of the apex production should be harvested. Assuming that half of the production is unavailable because of harvesting difficulties as discussed above, it is apparent that the probable maximum yield of commercial fish from the shelf is only three times the cur- rent harvest level of 2.0 x 105 mt/y. However, if some of the smaller, faster-growing fish such as the sand lance and the capelin are included as part of the harvest, then the total fishery resource might be increased considerably. This fish- ery tactic has already been employed in the North Atlantic. At present, economically important demersal resources such as crabs and clams are found in the estuarine environ- ment, while others, such as pollock and flatfish, are found on the shelf. Pelagic fisheries such as herring occur to a lim- ited extent at the mouth of fjords and to a much greater extent over the shelf and slope waters. The open ocean apex production is largely unexploited except for the fraction that returns to the coast as salmon. Acknowledgments The author is grateful to Dr. J. R. Forbes (Department of Fisheries and Oceans [DFO], Canada) for discussing the annual primary productivity of the continental shelf, and to Drs. I. Perry (DFO, Canada) and T.K. Newbury (Minerals Management Service, Alaska) for reading an earlier draft of this chapter. Financial support for preparation of this chap- ter was provided by the Minerals Management Service, Department of the Interior, through an interagency agree- ment with the National Oceanic and Atmospheric Admin- istration, Department of Commerce, as part of the Outer Continental Shelf Environmental Assessment Program. References Albright, L.J. 1983 Influence of river-ocean plumes upon bac- terioplankton production of the Strait of Geor- gia, British Columbia. Marine Ecology — Progress Series 12:107-113. Anderson, G.C., T.R. Parsons, and K. Stephens 1969 Nitrate distribution in the subarctic northeast Pacific Ocean. Deep-Sea Research 16:329-334. Barraclough, W.E., R.J. LeBrasseur, and O.D. Kennedy 1969 Shallow scattering layer in the subarctic Pacific Ocean: detection by high frequency echo sounder. Science 166:611-613. Booth, B.C. 1975 Growth of oceanic phytoplankton in enrich- ment cultures. Limnology and Oceanography 20:865-869. Cohen, E.B., M.D. Grosslein, M.P. Sissenswine, F. Steimle, and W.R. Wright 1982 Energy budget of Georges Bank. Canadian Special Publications, Fisheries and Aquatic Sci- ence No. 59. pp. 95-107. Cushing, D.H. 1971 Upwelling and the production offish. Advances in Marine Biology 9:255-334. Denman, K.L., D.L. Mackas, H.J. Freeland, M.J. Austin, and S.H. Hill 1981 Persistent upwelling and mesoscale zones of high productivity off the west coast of Van- couver Island, Canada. In: Coastal Upwelling. F. Richards, editor. American Geophysical Union, Washington, D.C. pp. 514-521. Favorite, F., A.J. Dodimead, and K. Nasu 1976 Oceanography of the subarctic Pacific region, 1960-71. International North Pacific Fisheries Commission Bulletin No. 33. 187 pp. Feely, R.A., E.T. Baker, J.D. Schumacher, G.J. Massoth, and W.M. Landing 1979 Processes affecting the distribution and trans- port of suspended matter in the northeast Gulf of Alaska. Deep-Sea Research 26:445-464. Freeland, H.J. and K. L. Denman 1982 A topographically controlled upwelling center off southern Vancouver Island. Journal of Marine Research 40:1069-1093. Ecological Relations 569 Gardner, G.A. 1982 Biological and hydrographica] evidence for Pacific equatorial water on the continental shelf north of Vancouver Island, British Columbia. Canadian Journal of Fisheries and Aquatic Sciences 39:660-667. Gaudy, R. 1974 Feeding four species of pelagic copepods under experimental conditions. Marine Biology (Berlin) 25:125-141. Hargrave, B.T., G.A. Phillips, and S. Taguchi 1976 Sedimentation measurements in Bedford Basin, 1973-1974. Fisheries and Marine Service Report 608, Department of Fisheries and Oceans, Canada. 129 pp. Ingraham, W.J., A. Bakun, and F. Favorite 1976 Physical oceanography of the Gulf of Alaska, final report. Research Unit 357. Environmental Assessment of the Alaskan Continental Shelf, Quar- terly Reports of Principal Investigators July-Sep- tember 3:845-978. Kinney, P.J., J. Groves, and D.K. Button 1970 Cook Inlet Environmental Data, R.V. Acona Cruise 065— May 21-28, 1968. Report No. R-70-2, Institute of Marine Science, University of Alaska, Fairbanks, AK. 120 pp. Larrance,J.D 1971 Primary production in the mid-subarctic Pacific region. Fishery Bulletin (U.S.) 69:595-613. Larrance, J.D. and A.J. Chester 1979 Source, composition, and flux of organic detritus in lower Cook Inlet. Research Unit 425. Outer Continental Shelf Environmental Assess- ment Program, Final Reports of Principal Investiga- tors 46:1-71. Larrance, J.D., D.A. Tennant, A.J. Chester, and P. A. Ruffio 1977 Phytoplankton and primary productivity in the Northeast Gulf of Alaska and lower Cook Inlet. Final report. Environmental Assessment of the Alaskan Continental Shelf Annual Reports of Principal Investigators for the Year Ending March 1977. 10:1-136. LeBrasseur, R.J. 1972 Utilization of herbivore zooplankton by matu- ring salmon. In: Biological Oceanography of the Northern North Pacific. A.Y. Takenouti, chief edi- tor. Idemitsu Shoten, Tokyo, pp. 581-588. Mackas, D.L. 1984 Spatial autocorrelation of plankton commu- nity composition in a continental shelf eco- system. Limnology and Oceanography 29:451-471. Mann, K.H. 1982 Ecology of Coastal Waters: A Systems Approach. Uni- versity of California Press, Berkeley and Los Angeles, CA. 322 pp. Matthews, J.B.L. and B.R. Heimdal 1980 Pelagic productivity and food chains in fjord systems. In: Fjord Oceanography. H.J. Freeland, D.M. Farmer, and CD. Levings, editors. Plenum Press, New York, NY. pp. 377-398. McAllister, CD. 1969 Aspects of estimating zooplankton production from phytoplankton production. Journal of the Fisheries Research Board of Canada 26:199-220. McAllister, CD., T.R. Parsons, andJ.D.H. Strickland 1960 Primary productivity and fertility at Station "P" in the northeast Pacific Ocean. Journal du Conseil, Conseil Permanent International pour VExploration de la Mer 25:240-259. Mysak, L.A., W.W. Hsieh, and T.R. Parsons 1982 On the relationship between interannual baroclinic waves and fish populations in the Northeast Pacific. Biological Oceanography 2:63-103. Parsons, T.R. 1972 Size fractionation of primary producers in the subarctic Pacific Ocean. In: Biological Oceanogra- phy of the Northern North Pacific. A.Y. Takenouti, chief editor. Idemitsu Shoten, Tokyo, pp. 275-278. Parsons, T.R. and G.C Anderson 1970 Large scale studies of primary production in the North Pacific Ocean. Deep-Sea Research 17:765-776. Parsons, T.R. and R.J. LeBrasseur 1968 A discussion of some critical indices of primary and secondary production for large scale ocean surveys. California Marine Research Committee, California Cooperative Oceanic Fisheries Investigations (CalCOFI) Report No. 12. pp. 54-63. Parsons, T.R. and R.J. LeBrasseur 1970 The availability of food to different trophic lev- els in the marine food chain. In: Marine Food Chains. J.H. Steele, editor. Oliver and Boyd, Edinburgh, Scotland, pp. 325-343. Parsons, T.R., R.J. LeBrasseur, and W.E. Barraclough 1970 Levels of production in the pelagic environ- ment of the Strait of Georgia, British Colum- bia: a review. Journal of the Fisheries Research Board of Canada 27:1251-1264. 570 Biological Resources Parsons, T.R., M. Takahashi, and B. Hargrave 1984 Biological Oceanographic Processes, 3rd Edition. Pergamon Press, New York, NY. 330 pp. Parsons, T.R., R.I. Perry, E.D. Nutbrown, W. Hsieh, and CM. Lalli 1983 Frontal zone analysis at the mouth of Saanich Inlet, British Columbia, Canada. Marine Biology (Berlin) 73:1-5. Perry, R.I., B.R. Dilke, and T.R. Parsons 1983 Tidal mixing and summer plankton distribu- tions in Hecate Strait, British Columbia. Cana- dian Journal of Fisheries and Aquatic Sciences 40:871-887. Pickard, G.L. and B.R. Stanton 1980 Pacific Fjords — a review of their water charac- teristics. In: Fjord Oceanography. H.J. Freeland, B.M. Farmer, and CD. Levings, editors. Plenum Press, New York, NY. pp. 1-51. Pingree, R.D 1978 Mixing and stabilization of phytoplankton dis- tributions on the northwest European Conti- nental Shelf. In: Spatial Patterns in Plankton Communities. J.H. Steele, editor. Plenum Press, New York, NY. pp. 181-220. Reise, K. 1979 Moderate predation on meiofauna by the mac- robenthos of the Wadden Sea. Helgolander wissenschaftliche Meeresuntersuchungen 32: 453-465. Ronholt, L.L., H.H. Shippen, and E.S. Brown 1978 Demersal fish and shellfish resources of the Gulf of Alaska from Cape Spencer to Unimak Pass, 1948-1976: a historical review. Environmen- tal Assessment of the Alaskan Continental Shelf, Final Reports of Principal Investigators 2:1-955. Royer, T.C 1981 Baroclinic transport in the Gulf of Alaska. Part I. Seasonal variations of the Alaska Current. Journal of Marine Research 39:239-250. Royer, T.C, D.V. Hansen, and D.J. Pashinski 1979 Coastal flow in the northern Gulf of Alaska as observed by dynamic topography and satel- lite-tracked drogued drift buoys.Journal of Phys- ical Oceanography 9:785-801. Ryther,J.H. 1969 Photosynthesis and fish production in the sea. The production of organic matter and its con- version to higher forms of life vary throughout the world ocean. Science 166:72-76. Schwinghammer, P. 1981 Characteristic size distributions of integral benthic communities. Canadian Journal of Fish- eries and Aquatic Sciences 38:1255-1263. Simpson, J.H. andJ.R. Hunter. 1974 Fronts in the Irish Sea. Nature (London) 250:404-406. Stephens, K., R.W. Sheldon, and T.R. Parsons 1967 Seasonal variations in the availability of food for benthos in a coastal environment. Ecology 48:852-855. Stockner, J.G., D.D. Cliff, and D.B. Buchanan 1977 Phytoplankton production and distribution in Howe Sound, British Columbia: a coastal marine embayment-fjord under stress. Journal of the Fisheries Research Board of Canada 34:907-917. Suess, E. 1980 Particulate organic carbon flux in the oceans — surface productivity and oxygen utilization. Nature (London) 288:260-263. Sverdrup, H.U. 1953 On conditions for the vernal blooming of phy- toplankton.yownW du Conseil Permanent Interna- tional pour I Exploration de la Mer 18:287-295. Tabata, S. 1982 The anticyclonic, baroclinic eddy off Sitka, Alaska in the Northeast Pacific Ocean. Journal of Physical Oceanography 12:1260-1282. Taylor, F.J.R. and R.E. Waters 1982 Spring phytoplankton in the subarctic North Pacific Ocean. Marine Biology (Berlin) 67:323-335. TullyJ.P. 1965 Time series in oceanography. Transactions of the Royal Society of Canada 3:337-366. Tully, J.P. and F.G. Barber 1960 An estuarine analogy in the sub-arctic Pacific Ocean. Journal of the Fisheries Research Board of Canada 17:91-112. Walsh, J.J. and C.P. McRoy 1986 Ecosystem analysis in the southeastern Bering Sea. Continental Shelf Research 5:259-288. Wickett, W.P. 1966 Ekman transport and zooplankton concentra- tion in the North Pacific Ocean. Journal of the Fisheries Research Board of Canada 24:581-594. Section 4 Issues and Perspectives Environmental Issues 19 Laurie E. Jarvela Office of Oceanography and Marine Assessment National Oceanic and Atmospheric Administration Anchorage, Alaska Abstract Much of the research that has been done in the Gulf of Alaska was conducted in response to legislative needs and can properly be characterized as 'policy relevant'. Both the form and the substance of regional research are influenced by a variety of social factors, including: socioeconomic patterns, land ownership and use, and institutional, legislative, and technological change. The social fabric also gives rise to regional environmental issues, which in the Gulf are concerned primarily with fish- eries, environmental degradation, multiple-use conflicts, and environmental hazards. Fisheries issues have existed since Territorial days. They have become complex as more species are harvested, exploitation attains or exceeds sustainable yields, and socioeconomic considerations increase in relative importance. Concern over environmental degradation arose with the advent of large-scale timber and pulp pro- duction, the production and transportation of oil and gas, and a projected increase in mining activity. Marine pollution from municipal waste is not yet widespread because present discharge rates are small relative to the assimilative capacity of the waters that absorb the discharge. Localized pollution has occurred at coastal fish- and shell- fish-processing centers. Foreign fishing activities have been identified as major con- tributors to litter both on beaches and the sea floor. Multiple-use conflicts are increas- ing as competition for finite resources increases. Sport/commercial/subsistence fishery conflicts and marine mammal-commercial fishery conflicts are included among several such conflicts. Seismic and other geophysical hazards are public policy issues that will gain importance as the region's population grows and the potential for a catastrophic event increases. The historic reliance of Alaska on natural resources as an economic base and projections for future development suggest that resource- extraction activities — and their associated perturbations — will continue to require directed research. Alaska's growing energy demands and the abundance of energy sources in the Cook Inlet area may cause coastal energy systems to become an environ- mental issue. Introduction Research frequently results from issues of public impor- tance. Such investigations can be categorized as 'policy rele- "... the way in which we articulate environmental issues vant' and are often implemented by means of either legisla- stems only partly from the forms of nature. Our perception tive or regulatory mandates. Much of the environmental of issues equally reflects the attitudes, wants and ways of liv- research undertaken in the Gulf of Alaska by state and ingof society itself." federal entities has addressed pragmatic questions. In this Robert B. Weeden, Alaska Resource chapter, we 1) identify factors that have influenced regional Development: Issues of the 1980s (1984) oceanographic research, 2) consider in more detail major 575 576 Issues and Perspectives environmental issues, and 3) speculate on future issues. The intent is to provide a context for future discussions of both the status of current research and the implications for resource management that are presented in Chapter 20. Underlying Factors As Weeden noted, environmental issues are made up of a complex summation of society's wants, needs, and attitudes. Furthermore, they are dynamic and liable to wax and wane as the social fabric changes. At a national level, environmen- talism and environmental issues probably reached a zenith in the late 1960s and early 1970s. In Alaska, they have been consistently visible because of the pervasive importance of natural resources to the state's well-being. Some underlying factors that have helped shape regional oceanographic research are described below. Native Claims Settlement Act (ANCSA) conveyed some 160,000 km2 of federal lands and approximately $1.0 billion to the state's Natives. Native-owned corporations created by ANCSA have initiated a variety of business ventures based on natural resource exploitation in the coastal region. Both state and national public interest groups have influ- enced the withdrawal of a large amount of federal land for inclusion in national parks, preserves, monuments, and wildlife refuges. About 400,000 km2 were so designated under Section 17d(2) of ANCSA and the Alaska National Interest Lands Conservation Act (ANILCA) of 1980. Such actions included the creation of the Admiralty Island and Misty Fjords National Monuments, the Wrangell-St. Elias National Park and Preserve, the Katmai National Park and Preserve, as well as additions to the Glacier Bay National Park and Preserve. As of 1984, the federal government owned and managed approximately 900,000 km2 of Alas- kan lands (Morehouse 1984). Socioeconomic Factors Population density in the Gulf is low in comparison with coastal regions in the Lower 48 states. According to the 1980 census, over one-half of the state's population of some 400,000 people was concentrated in the Cook Inlet area. Of these, about 175,000 were in Anchorage, the state's service hub — located at the head of the Inlet. Another 65,000 to 70,000 people lived in about 100 communities scattered along hundreds of kilometers of coastline between Dixon Entrance and the western Aleutian Islands — most of them in the cities of Juneau, Ketchikan, Sitka, and Kodiak. These smaller communities are economically dependent on renewable resources — predominantly fisheries and timber. Most communities in the coastal region are not served either by road or by rail and, therefore, they rely on marine and air transportation for both commerce and travel. In both absolute and relative terms, population growth in the region is dominated by Anchorage and adjoining commu- nities that constitute the so-called 'Railbelt', which extends from Seward to Fairbanks. Since its purchase from Russia in 1867, Alaska's abundant fish, game, timber, and minerals have been the basis for both jobs and income for its residents. Kresge, Morehouse, and Rogers (1977) likened Alaska during the years 1740 to 1940 to a colonial possession due to its highly specialized exploitation of raw materials for export to distant markets and populations. The analogy is still true today. Manufactur- ing plays a relatively small role in the state's economy. The oil industry has formed the dominant sector of the economy since the 1960s. Although oil development in the Arctic has received the most attention, considerable petroleum- related activity has occurred in the Gulf of Alaska region. Land Ownership and Use Both land ownership and use patterns are in transition. The Statehood Act of 1959 gave Alaska authority to selec- tively acquire over 400,000 km2 of federal lands, and also gave the state title to the submerged offshore lands in the territorial sea extending 5 km offshore. Similarly, the Alaska Institutional Factors A considerable marine research capability has evolved within Alaska's academic institutions and resource manage- ment agencies over the past 50 years. The University of Alaska was created by an act of the Territorial Legislature in 1935. The University's Geophysical Institute was established by an act of Congress in 1946. The Institute of Marine Sci- ence (IMS) was founded in 1960 by the state legislature; it is located in Fairbanks, but has research, teaching, and dock- ing facilities at Seward. The University's research capabilities were increased by the establishment of the Alaska Sea Grant Program in 1970, the founding of the Arctic Environmental Information and Data Center (AEIDC) in 1972, and the founding of two affiliate campuses with marine studies programs in Juneau and Kodiak. The conveyance of many natural resource management and regulatory functions from federal to state control fol- lowing statehood resulted in the establishment of the Departments of Fish and Game (ADF&G), Natural Resources (DNR), Community and Regional Affairs (DCRA), and Environmental Conservation (DEC). All have substantial research, management, or regulatory roles involving the marine environment. The infusion of monies into the state treasury resulting from taxes and royalties on North Slope oil production has enabled the agencies to pur- sue a variety of marine resource management and enhance- ment projects. The large federal presence in Alaska predates statehood and will continue because not only much of the state's uplands but also the submerged lands from 5 to 320 km (3 to 200 mi) offshore remain under federal control. Most of the coastal lands of the Gulf of Alaska region are under federal jurisdiction (Fig. 19-1). The U.S. Forest Service has stew- ardship of the huge Chugach and Tongass National Forests. The National Park Service administers Glacier Bay National Park and Preserve, the Wrangell-St. Elias National Park and Preserve, and other lands bordering the Gulf. The U.S. Fish and Wildlife Service manages the many islands composing the Alaska Maritime National Wildlife Refuge, as well as numerous mainland refuges. Environmental Issues 577 .» -o -a c I CT> o ;*■ 578 Issues and Perspectives The National Oceanic and Atmospheric Administration (NOAA) has responsibilities pertaining to the maintenance of environmental quality and to the conservation and exploitation of marine mammals, fish, and shellfish. NOAA's National Marine Fisheries Service (NMFS) and its predecessors, the United States Fish Commission and the Bureau of Commercial Fisheries, have conducted fisheries research in the Gulf of Alaska since the territorial period. Although the NMFS Northwest and Alaska Fishery Center is headquartered in Seattle, it maintains laboratories both at Auke Bay and at Kodiak, Alaska. The advent of the large federal outer continental shelf (OCS) oil- and gas-leasing program, coupled with new leg- islative mandates concerning environmental quality in the 1960s, brought other federal agencies into marine research in the Gulf of Alaska. Oil, gas, and other mineral manage- ment on the OCS was initially the responsibility of the Department of Interior's Bureau of Land Management (BLM), but now resides with the Department's Minerals Management Service (MMS).a The Environmental Protec- tion Agency (EPA) was established in 1970; its activities include the maintenance of marine water quality. Numerous international arrangements have furthered marine research in the Gulf of Alaska (Miles, Gibbs, Fluharty, Dawson, Teeter, Burke, Kaczynski, and Wooster 1983). Most are concerned with Fisheries. The International Pacific Halibut Commission was created in 1925 to promote both stock maintenance and maximum sustained yields for halibut; its United States and Canadian members set fishing seasons and area catch quotas. The International Pacific Salmon Fisheries Commission promotes the conservation of both sockeye and pink salmon stocks; it was formed in 1930 by the United States and Canada. The International North Pacific Fisheries Commission (created in 1952 by Can- ada, Japan, and the United States) promotes and coordi- nates scientific studies of selected fish species, mainly halibut and salmon. The International Whaling Commis- sion, of which the United States is a member, has regulated the taking of whales since 1948. The committee sets quotas by geographical areas, size limits, and closed seasons based on advice from its scientific committee. The North Pacific Fur Seal Commission, created in 1957 by the United States, Canada, Japan and the Union of Soviet Socialist Republics, formulates and coordinates fur seal research programs. There also have been several short-term bilateral research agreements between the United States and other nations that pertain to the Gulf of Alaska. Legislative Influences Legislative influences on marine research in Alaska are numerous and can vary in their scope from statewide to international issues. Upon attaining statehood, Alaska acquired responsibility for natural resources on both the state's uplands and on its submerged lands. Legislative action created the agencies which not only manage the resources, but also regulate activities in the coastal zone. In 1979, the Alaska Coastal Management Program was approved by the federal government. The plan gives the state certain powers to guide any development that takes place in either coastal or offshore waters. It grants those powers through consistency provisions of the federal Coastal Zone Management Act. Federal environmental legislation (see Dolgin and Guilbert 1974; Sive 1976) has provided the impetus for a large amount of marine research in the Gulf of Alaska. The Outer Continental Shelf Lands Act, enacted in 1953, was among the most influential. The Act and its amendments mandated the orderly development of energy resources on the OCS and provided for environmental protection. Another legislative landmark was the National Environmen- tal Policy Act of 1969; it presented a national policy for environmental quality, required environmental impact statements for major actions initiated by federal agencies, and formally involved affected states and other parties in the decision-making process concerning such actions. A variety of other environmental legislation was enacted in the 1970s. The Coastal Zone Management Act, the Marine Mammal Protection Act, the Federal Water Pollution Con- trol Act (and its amendments), the Marine Protection, Research, and Sanctuaries Act, the Endangered Species Act, the Clean Water Act, and the National Ocean Pollution Research and Development and Monitoring Planning Act were passed during that decade. The legislation resulted in considerable research and coordination within and among local, state, and federal agencies in order to comply with requirements concerning waste discharges, ocean dumping, and protection of the environment. As noted by Like (1976): "The history of environmental legislation appears to reveal a transition from dealing with the effects of pollution to exercising controls over its sources." Two federal legal actions relevant to the Gulf of Alaska region have international implications. The Fishery Conser- vation and Management Act (FCMA) of 1976 created a 320 km-wide (200 mile) fishery conservation and management zone surrounding the United States and its possessions. Under the FCMA, the North Pacific Fishery Management Council develops both regulations and catch quotas for the portion of the zone within the Gulf of Alaska. FCMA man- agement includes the foreign fisheries. The Exclusive Eco- nomic Zone Proclamation of 1983 sets forth the United States' sovereign rights to explore, exploit, conserve, and manage natural resources of the seabed and overlying waters (excepting tunas) within the zone, thus extending the FCMA to include non-living resources (Pendley 1984). Technological Factors Technological advances have markedly improved marine research capabilities. This improvement is reflected in both the quality and quantity of the oceanographic data now being acquired in comparison with the data from the era of the Nansen bottle and reversing thermometer. Infor- mation storage and processing have been facilitated by a As part of the OCS leasing program, the BLM and NOAA initiated the Outer Continental Shelf Environmental Assessment Program (OCSEAP) in Alaska in 1974. The goal of OCSEAP is to provide decision- makers with the data and information they need to assess environmen- tal risks of oil and gas development. Environmental Issues 579 devices such as integrated circuits, transistors, and minicom- puters. The coupling of electronic sensors with digital com- puters now allows shipboard data processing and survey refinement at sea. The superior facilities, the seaworthiness, and the endurance of modern oceanographic vessels are greatlv improved over those qualities in their predecessors. Remote sensing from satellites and aircraft is now routinely used for applications requiring the synoptic coverage of large ocean areas. All these technological advances, plus the availability of funds to address information needs, have yielded a quan- tum jump in both the quantity and quality of data collected during the past two decades. The powerful data manipula- tion and analytical capabilities of large computers enable researchers to address problems whose answers were, until recently, merely conjectural. Issues Most of the large variety of present and potential environmental issues pertaining to the Gulf of Alaska region fall into one of four general categories: fisheries, environmental degradation, multiple-use conflicts, and environmental hazards. Fisheries As used here, the term 'fisheries' encompasses the indus- trial use of fish, shellfish, and marine mammals. Fisheries issues normally arise when the goals of maintaining sus- tained yields, satisfying social needs, and satisfying eco- nomic needs conflict with either the condition of the resource, the demands by industry, or with regulatory pol- icies. In Alaska, fisheries issues consist of a significant and continuing suite of high-visibility problems that are impor- tant to both the public and to government, since Alaska fish- eries have played such a dominant economic role in the State's history'. Fish and Shellfish. The major domestic fish and shell- fish fisheries in the Gulf of Alaska have traditionally been directed toward high-value species, and of these fisheries, the salmon industry- is the most notable example. The per- fection of salmon-canning techniques has allowed large- scale exploitation of this resource in Alaska (Berman 1984). The first cannery' was established in southeastern Alaska in 1878 (Pennoyer 1979). The canneries spread rapidly throughout the region and persist to the present, although fresh and frozen products have eroded canned salmon's dominance of the market. Since its inception, the value of the statewide salmon harvest alone has exceeded $3.5 bil- lion (Browning 1980). Exploitation of demersal fish and shellfish began shortly after the salmon fisheries. Many of these latter develop- ments are reviewed in Ronholt, Shippen, and Brown (1977). Halibut were first harvested by United States and Canadian fishermen in the late 1800s and by the early 1900s, the stocks were heavily exploited. Shrimp fishing was relatively insig- nificant until the mechanical peeler was introduced in 1958 (Richardson and Orth 1979), after which the fishery grew rapidly, then declined due to depressed stocks. By the 1960s king and Tanner crabs had become the basis for the most lucrative Alaskan fisheries. However, the decline in king crab stocks that occurred in the 1970s culminated in a pre- cipitous drop in the mid-1980s. The common thread run- ning through the histories of these and other fisheries is their 'boom or bust' character (Crutchfield and Pontecorvo 1969; Gusey 1978, 1979; and Francis 1985). The salmon indus- try has experienced several such cycles. T he Alaskan domestic fisheries have numerous reg- ulatory controls intended to curb the fishing fleets' ability to exceed allowable harvests. Time-area closures, gear and area restrictions, vessel size limitations, and other measures are used. The roe-herring fisheries that in some instances last only a few hours (Rearden 1981; Wiley 1984) epitomize the tight control of some fisheries. The fishing industry's chronic overcapacity and the resulting economic ineffi- ciency are now being addressed through management pol- icies that include socioeconomic considerations. The State of Alaska introduced limited entry to certain fisheries in 1973, in an effort to increase fishermen's earnings (Adasiak 1978). The State also began addressing the financial prob- lems being experienced by processors, the development of previously unused fisheries for selected species, and the marketing of Alaskan seafood products (Hall and Hickey 1983). Ventures to exploit the abundant groundfish resources of the Gulf — resources once monopolized by for- eign fleets — are being used to bring more stability to the industry. Foreign nations began harvesting significant quantities of fish and shellfish from the Gulf of Alaska in the 1960s. Russia andjapan have taken the greatest tonnages; however, several other nations also have participated. The extension of United States territorial waters to 19 km (12 mi) offshore in 1966, coupled with the passage of the FCMA in 1976, has progressively restricted foreign fishing until today; foreign fishermen concentrate heavily on groundfish and sablefish. Walleye pollock currently make up the bulk of the catch from the Gulf of Alaska. American fishermen initially met with limited success in the groundfisheries, primarily due to high processing costs and a lack of viable markets. However, under provisions of the FCMA, the North Pacific Fisheries Management Council can decrease foreign catch quotas if such actions improve opportunities for the domestic industry (Hall and Hickey 1983). Because of these various circumstances, foreign com- panies have formed joint ventures with the American com- panies. The Americans capture the fish and then deliver them to foreign-owned, at-sea processors. American fish- ermen caught about one-half of the groundfish taken from the Gulf in 1984. It is possible that the Gulf of Alaska groundfishery will eventually become an exclusively Ameri- can endeavor (Gorham 1979). Recent annual fish and shellfish harvests from the Gulf have totaled some 3.0- to 4.0 x 105 mt and had ex-vessel values of $200- to $300 million (Alton 1981). Production from the existing fisheries may now be near the maximum allowable levels for sustained yields. Stocks of some species, such as Pacific ocean perch, pandalid shrimp, and king crabs, are currently at low levels. When the stocks recover, 580 Issues and Perspectives management and catch quotas will be more conservative than thev were previously, in order to avoid a recurrence of such conditions. Significantly increased production may be possible if certain species that are currently unfished or little fished are more aggressively exploited. Capelin (Mallotus villosus), sand lance (Ammodytes hex- apterus), mackerel (Scomber japonicus), pomfret (Brama japonica), grenadiers (Macrouridae) and squids are candi- dates for new fisheries. A comprehensive analysis of these and other unused fishery resources of the northeastern Pacific Ocean is presented by Trumble (1973). If a reliable and rapid screening method is developed for paralytic shell- fish toxins, then the razor clam (Siliqua patula) and several species of hardshell clams may become commercially important. Given the finite size of the region's native stocks, aquaculture likely will assume a greater role in fisheries (see Kelly and Hood 1973; Rosenberg 1976, 1977). The State has fostered private salmon-enhancement ven- tures through legislation that lets nonprofit corporations operate hatcheries (Kaill 1979). The success of both Nor- wegian and British salmon-pen ranching in the nearshore waters of those countries could serve as an impetus for sim- ilar ventures in the unpolluted, protected fjords of south- eastern Alaska and Prince William Sound. The intensive exploitation of both commercial fish and shellfish has increased the pressure on resource managers. They are simultaneously expected to conserve stocks, max- imize yields, and satisfy all user groups. Pennoyer (1979) has provided a cogent description of the evolution of fisheries management in Alaska from the time of European entry into the region to the late 1970s. The complexity of present- day fishery management in the Gulf of Alaska region is best exemplified by the salmon fishery. As indicated by Rogers (Ch. 15, this volume), salmon in the Gulf consist of five species and a mixture of age groups that range from smolts to mature fish up to seven years old. Salmon are highly migratory, with stock units that originate from lakes and streams as far north as the Bering Sea, as far south as California, and as far west as the Asian coast. Their life histories are diverse — both among and within species. Individual fish take up ocean residence for periods ranging from a few months to several years. Salmon fisheries can occur anywhere within the fishes' range — from the Bering Sea south to California, as well as across the Pacific to Asia. Both immature and mature salmon are captured. A variety of both active and passive fishing methods are employed: • trolling • purse seining • drift- and set gillnetting • fish traps • weirs • rods and reels. The methods vary widely in efficiency, which in turn var- ies according to stock density and the evolution of the equip- ment and the techniques. Because gear types and locales dif- fer, some fisheries are relatively non-selective for species, age classes, or stock units, while others are very selective. Inevitably, some of the salmon that form the mainstay of any given fishery are caught elsewhere — the so-called intercep- tion problem. Commercial, sport, and subsistence fishermen make up the major user groups that compete for the resource, and their differing desires must be accommodated. Large hatch- ery and aquaculture programs inject additional salmon into the ocean, which then compete with the native fish for prey, alter their genetic makeup by interbreeding (Helle 1976), and endanger the survival of native stocks. This latter effect is hypothesized because returns of artificially propagated salmon can be manipulated to some degree in response to the needs of the harvester. An apparently healthy fishery based on mixed stocks can consist of large numbers of hatchery fish and very few native fish. As hatchery fish become more abundant, the prolonged exploitation of the native fish may drive them to commercial extinction. In addition, how well salmon survive in both freshwater and at sea is strongly affected by a number of factors, including: • climatic conditions • prey availability • disease • predation • other physical and biological factors. The result is a pronounced fluctuation in the interannual return rate. The preceding descriptions of the Gulf of Alaska fish- eries indicate some of the myriad factors that fishery manag- ers consider in developing management schemes. Agree- ments must be reached at local, regional, interstate, and international levels concerning how allowable catches of the various species will be divided among the many user groups. Time, area, and gear restrictions must be developed to ensure that sufficient adults survive to spawn. A large suite of biological data must be available for the analyses that lead to the catch, allocation, and fishery restriction decisions. As the issues have grown more complex, fisheries man- agement has evolved from a primarily biological approach to one that formally includes socioeconomic concerns — and that evolution is continuing. Maximum sustained yield concepts have given way to others such as optimum yield and ecosystem management, the latter of which attempts a more holistic approach encompassing not only the target species, but also their predators and prey {e.g., see Ham- mond 1980). Developments such as these will require not only more knowledge of the biology of individual species, but also information on structure and function of entire marine communities and ecosystems. Marine Mammals. Marine mammals formed the basis for the first economic ventures in Alaska (Fay 1979). In the 1700s, Imperial Russia established stations from which to hunt sea otters and fur seals in the Gulf of Alaska. In the 20 years following the United States' purchase of Alaska in 1867, American sealers killed over two million fur seals, and foreign pelagic sealers also took a significant number (Chap- man 1979). Nearly one million sea otters were harvested dur- ing the period of their exploitation. Pelagic harvests of these Environmental Issues 581 species ended in the early 1900s, at which time both popula- tions were severely depleted. Fur seal harvests continue to this day; however, they are allowed only at rookeries on the Pribilof Islands in the Bering Sea. As a result of these restrictions, both fur seals and sea otters have increased to their pre-exploitation abundances over much of their origi- nal ranges. Commercial whaling in the Gulf of Alaska was begun by Yankee pelagic whalers in 1835 (Bockstoce 1978). Later, shore-based stations were established to exploit seasonal concentrations of the animals (Morgan 1978). Over 8,000 whales were processed at the Port Hobron and Akutan whal- ing stations between 1912 and 1939 (Reeves, Leatherwood, Karl, and Yohe 1985). Russian and Japanese whaling fleets operated in the region from the 1950s to the 1970s (Leather- wood, Bowles, and Reeves 1983). Commercial whaling has been controlled in recent years by three restrictions: 1) the International Whaling Commission's prohibitions on the taking of large baleen whales, 2) the moratorium imposed by the Marine Mammal Protection Act (MMPA) on the tak- ing of any species of marine mammal, and 3) the Endangered Species Act. The Territorial Government of Alaska allowed a regu- lated harvest of both harbor seals and sea lions for commer- cial use in the 1950s. This program continued under control of the Alaska Department of Fish & Game after statehood. Harbor seal harvests increased from between 6,000 and 10,000 animals annually before 1963 to over 50,000 in 1965 due to the demand for pelts in the European fur market (Fay 1979; Pitcher 1984). Harvests then declined to between 8,000 and 12,000 animals by 1972 when the MMPA was enacted. Subsequent seal harvests by Natives have been about 1,000 to 2,500 animals per year. Some harvests of sea lion pups for pelts also occurred between 1959 and 1972. Additional infor- mation on marine mammal exploitation is provided by Cal- kins (Ch. 17, this volume). Since the enactment of the MMPA there has been little, if any, commercial exploitation of marine mammals in Alaska. While the act allows the taking of marine mammals by Natives and some use of their pelts for fur trim on salable handicraft articles, it seems unlikely that intensive exploita- tion will occur because of the limited demand for the hand- icraft products. However, if management of pinnipeds and sea otters is returned to the State of Alaska, regulated har- vesting of the animals may resume. Environmental Degradation The issue of environmental degradation encompasses those agents that cause any alteration to the natural environ- ment that is generally perceived as harmful or aesthetically displeasing. Such agents can be pollutants, activities that cause ecological disturbance, and activities that produce adverse visual impacts. Environmental degradation is an important issue in Alaska because of the State's predomi- nantly pristine character and because its great natural beauty attracts both residents and numerous tourists. Equally important is the unsullied environment's intrinsic capacity to produce many living resources that can be of economic importance. Agents of environmental degrada- tion found in the Gulf of Alaska include pollutants and litter stemming from: • petroleum production • fish processing • logging and pulp manufacture • marine transportation • municipal discharges • non-point sources. Petroleum Hydrocarbon Pollution. Petroleum hydro- carbon pollution of the marine environment is a global problem. Petroleum hydrocarbons come from many sources besides oil and gas production activities. These sources include: • bilge pumping from vessels • marine accidents • natural seepages • loading and transfer operations • refineries • municipal sewage • runoff • atmospheric rainout (NRC 1985). The nature of petroleum, its fate in the ocean, and its effects on organisms and ecosystems have all been the sub- ject of intensive study during the past decade. Comprehen- sive general reviews include GESAMP (1977), Clark (1982), and NRC (1985). The fate and effects of petroleum spills in the ocean are summarized by Gundlach and Boehm (1981), Gundlach, Boehm, Marchand, Atlas, Ward, and Wolfe (1983), Teal and Howarth (1984), and Wolfe (1985). Menzie (1982) describes the environmental implications of offshore oil and gas activities. Particularly pertinent are the reviews of oil weathering and its effects on the biota of the subarctic that were prepared by Malins (1977), Payne and Jordan (1979), Malins and Hodgins (1981), Griffiths, Caldwell, Broich, and Morita (1982), Malins (1982), Malins, Hodgins, Varanasi, Chan, McCain, Weber, and Brown (1982), Rice, Moles, Taylor, and Karinen (1979), and Rice, Moles, Karinen, Korn, Carls, Broderson, Gharrett, and Bab- cock (1984). Drilling discharges in the marine environment are reviewed by Houghton, Critchlow, Lees, Czlapinski, Mil- ler, Britch, and Mills (1981) and NRC (1983). The concern over large-scale petroleum pollution in the Gulf of Alaska arises mainly from oil and gas production activities, oil loading, and tankering in Cook Inlet and Prince William Sound. Oil production in the Gulf began about 1900 at Katalla, 100 km east of Cordova. Between 1902 and 1933, this small field produced 1.54 x 105 bbl of oil (Davis 1984). Exploration elsewhere along the coast was unsuccessful until 1957 when the first commercial well was drilled near Swanson River in the Cook Inlet area. Subse- quent intensive exploration in that area resulted in the dis- covery of seven oil fields and 13 gas fields, including fields in the Inlet proper (AGS 1970). By the end of 1984, Cook Inlet Basin had produced about 1.0 x 109 bbl ( ~ 1.6 x 108 m3) of oil and 3.7 x 1012 ft3 (1.1 x 1011 m3) of natural gas (AOGCC 1985). Annual production is now declining. 582 Issues and Perspectives Exploratory drilling has occurred in coastal waters between the Alaska Peninsula and Yakutat. Six federal outer continental shelf (OCS) lease sales took place in the region between 1976 and 1984. Although over 20 offshore wells were drilled, no commercial finds have thus far been reported in either state or federally controlled waters. A summary of federal OCS sales and associated activities in the Gulf of Alaska is presented by Wiese (1984). The main petroleum loading and shipping locations in the Gulf of Alaska are in Cook Inlet and at Valdez in Prince William Sound. The Drift River and Nikiski terminals serve Cook Inlet; volumes of petroleum products shipped from these terminals have reached as much as 8.0 x 107 bbl of oil and over 2.0 x 1011 ft3 of liquid natural gas annually (Davis 1984). The Valdez terminal — a much larger operation — receives some 1.6- to 1.7 x 106 bbl of oil daily from the North Slope fields via the Trans-Alaska Pipeline for loading on tankers for export. The annual throughput of the terminal was equivalent to 10% of the United States' total domestic consumption of 5.5- to 6.3 x 109 bbl per year in the early 1980s. Spillage at the Valdez terminal has been only about one-half barrel for every million barrels handled. As of 1985, no spills exceeding 1,000 bbl and only one spill over 100 bbl had occurred (Lt. M. Dahl, U.S. Coast Guard, Valdez, pers. comm., 1985). Most of the petroleum hydrocarbons that enter Port Valdez harbor come from ballast water that is offloaded from incoming tankers. The water is treated to remove residual petroleum hydrocarbons and then dis- charged via a submarine diffuser into the inlet. Although the concentration of petroleum hydrocarbons remaining in the discharge is small (< 8 ppm), the absolute quantity that is released is significant — about 300 1 of aromatic hydrocar- bons and 170 1 of dissolved organic compounds for the ~ 3.8 x 104 m3 of ballast water that is processed daily (Lysyj, Rush- worth, Melvold, and Farlow 1979). Concerns about the chronic petroleum hydrocarbon dis- charges into Port Valdez, their potential for accumulation, and the effects they may have on the local ecosystem all prompted the EPA and the Alaska Department of Environ- mental Conservation to require oceanographic investiga- tions both of the fjord and its biota as a condition of any discharge permit. An intensive four-year, pre- and post- operational study was undertaken by the University of Alaska; the project's results are described in Colonell (1980). It was concluded that, at least in the short term, no adverse effects on the fjord were evident. Monitoring of the treated ballast water effluent and receiving waters has continued under National Pollutant Discharge Elimination System (NPDES) permits. Episodic releases of petroleum hydrocarbons into the Gulf of Alaska have come from vessel accidents, from bilge dumping, and from fish canneries. The heavy tanker traffic from Cook Inlet and Valdez thus far has not produced any massive oil spills. The only major oil spill in the region occurred in 1979 when an ore carrier, the Lee Wang Ziyi, cap- sized in Dixon Entrance. Several thousand barrels of bunker fuel and diesel oil from the vessel were carried northward by currents toward Ketchikan, where it washed ashore (Bayliss and Spoltman 1981). Evidence of vessel bilge dumping has been observed on many occasions. In 1970, one such event reportedly killed an estimated 100,000 seabirds near Kodiak Island (Ohlendorf, Risebrough, and Vermeer 1978). Another somewhat unusual problem was encountered at a cannery near Cordova. Many years ago, waste oil was appar- ently disposed of in pits and then covered. The oil slowly percolated through the soil and entered the intertidal zone where it killed numerous organisms. Even this moderate quantity of oil was very costly to recover because it required months of effort that included trenching to collect the oil as it moved toward the beach. Mining and Mineral Transfer Operations. Mining is an environmental issue for the Gulf of Alaska because mine tailings and processing water may be dumped into the Gulf, and pollution may arise from both loading and undersea mining operations. Potential environmental effects include: • turbidity • coastal erosion • physical removal or smothering of marine organisms • particle-size changes • oxygen depletion caused by free sulfide releases (Baram, Rice, and Lee 1978) . The current state of knowledge about the effects of undersea mining on marine ecosystems is rudimentary. Lit- tle underwater mining has occurred in the Gulf of Alaska. A barite deposit at Castle Island was worked from 1967 to 1980 in order to provide oil-field drilling mud. About 2.25 x 106 mt of ore remain there (Baram et al. 1978). Future marine mining may exploit copper (Moore 1978; Heiner, Wolff, and Grybeck 1971), sand and gravel, placer, and sulfide deposits (Clague, Bischoff, and Howell 1984). Two proposed onshore mining projects intend to dis- charge wastes into the marine waters of the Alexander Archipelago. The smaller one, the Greens Creek project, is an underground zinc, lead, silver, and gold mine located at the north end of Admiralty Island. The larger of the two is an open-pit molybdenum mine east of Ketchikan. The expected life of the Greens Creek mine is 11 years. Treated process water would be discharged from a marine outfall at a rate of about 2 m3/min. Potential pollutants in the effluent include milling-process chemicals such as sodium cyanide, copper sulfate, and other organic and inorganic salts (USDA 1983). Treatment would comply with the EPA effluent quality standards. A major concern is the possible bioaccumulation of toxic metals and trace elements in those aquatic organisms that are near the outfall. The behavior of such chemical species in local waters is poorly understood, so it is not now possible to determine the environmental consequences of the pro- posed action (USDA 1983). The complexity of biological sys- tems suggests that a simple relationship between the con- centration and the nature of a sediment-metal and its bioavailability to various organisms in the ecosystem is unlikely (Warren 1981). The proposed Quartz Hill open-pit molybdenum mine (located about 70 km east of Ketchikan) is one of the largest and richest known molybdenum ore bodies. Even though the ore is relatively rich, 99.875% of the extracted material Environmental Issues 583 will be discarded after processing — this in addition to the overburden that must be removed (Snook 1982). If the mine's owners emplov marine disposal, some 3.8- to 7.6 x 10' mt/d of tailings solids will be discharged through a sub- marine outfall into a nearby fjord for a period of 70 years (Ryan 1983). The projected annual discharge from Quartz Hill is equivalent to about 7% of the Mississippi River's sedi- ment discharge and is roughly an order of magnitude greater than the total annual discharge of all dredging wastes that are dumped in the United States — according to data on the latter two sources in Gorsline (1979). Because the tailings have a low acute toxicity for organisms (Mitchell, Morgan, Vigers, and Chapman 1985), smothering and the alteration of the benthic community's composition are the primary concerns. Coastal-water pollution may also result from ore — including coal — that spills at marine-shipment terminals. A terminal constructed at Skagway in the late 1960s served as a shipment point for both zinc and asbestos ore that was mined in the Yukon Territory. Peak annual shipments through the facility reached ~ 7.0 * 105 mt (CSA 1982). The terminal is currently inactive. The effects created by ore that was lost during loading operations at Skagway have been examined bv E.F. Robinson-Wilson (U.S. Fish and Wildlife Service, Juneau, unpubl. data) and G. Malinkey (Alaska Department of Environmental Conservation, unpubl. data). Thev found elevated lead, zinc, copper, mercury, and cad- mium concentrations in the sediments as well as in some of the biota at the loading site. The ore terminal is one of sev- eral Alaska locations selected as long-term monitoring sites for NOAA's Status and Trends Program. Coal exports from Alaska to Korea began in 1984. Because major deposits are located near the coast, it is likely that shipments of large quantities of coal from ports in southcentral Alaska to the Pacific Rim countries will occur. Annual exports could reach 1- to 2 x 107 metric tons. The two most important coal fields are the Beluga field on the west side of Cook Inlet and the Bering field east of Cordova. Identified resources in the Beluga field amount to at least 1.7 x 109 mt, of which at least 7.5 x 108 mt are economically extractable (Davis 1984). Alaskan coal has a low sulfur con- tent (0.2%) (Davis 1984). Since this coal presumably has low toxicity for marine organisms, localized physical effects such as the smothering of infauna and habitat alteration may be the major issues. Logging and Forest Products. Most of Alaska's lumber, wood chip, and pulp production takes place in the Tongass and Chugach National Forests. These Forests total about 9.3 x 104 km2 and border much of the Gulf from Dixon Entrance to Kodiak Island. The primary timber species that are harvested include Sitka spruce and hemlock. While ter- restrial environmental issues concerning the forest- products industry predominate, marine-related issues also are present. Localized pollution occurs in the vicinity of pulp mills. Log storage, transfer, and shipment activities cause physical damage to intertidal habitats, produce leach- ates, create biochemical oxygen demands, and smother biota with tree-bark accumulations (Hansen, Carter, Towne, and O'Neal 1971; Ellis 1973). Log rafts are extensively stored and transported in the marine environments of the Gulf of Alaska. Loggers prefer creek mouths and other shallow embayments for log storage and transfer because they offer protection from both wind and waves, and they provide lower salinity and less exposure of the logs to air at low tide, thereby minimizing the damage caused by marine boring organisms. Such areas also often have the highest local habitat values and the most produc- tive intertidal communities. They are concentration sites for anadromous fishes, waterfowl, and many other animals that frequently forage in the intertidal zone. The comparative richness of such habitats also makes them attractive for both subsistence and recreational use. Research on the effects of log storage and transfer practices on Alaskan intertidal and subtidal habitats has demonstrated that significant accumulations of organic debris may persist for long peri- ods, and that marine organisms may become scarce in trans- fer and storage areas (Ellis 1973). In 1967, the forests bordering the Gulf of Alaska con- tained 86% of the total volume of sawtimber in Alaska (Davis 1984). In 1979, the timber cut in Alaska's national for- ests— essentially the coastal forests — was about one-half of the allowable cut that would still maintain sustained yields. The allowable cut is now even less because land has been reclassified for wilderness areas and parks. Future cuts are unlikely to exceed the 1982 cut of —4.5 x 10s board feet, so little growth in the coastal lumber and pulp industry is expected (Davis 1984). Intertidal and subtidal habitat use by the industry should therefore be comparable in area to that in past years. In 1970, when the timber cut was about 5.6 x 108 board feet, log storage and transfer areas in southeastern Alaska totaled about 2.75 km2 and mill storage areas totaled about 0.5 km2 (ADEC 1971). Questions remain concerning log storage and transfer areas: • How much time is required for the intertidal commu- nities to return to their original states? • Are recovery rates sufficiently rapid to offset the damage that results from the establishment of new transfer sites as logging operations shift to new cutting areas? Due to the slow growth rates of the region's commercial tree species, cutting rotations may be 100 years (Hutchinson and LaBau 1975, p. 36). Assuming that loading and transfer operations would take place at the same location during suc- cessive logging operations in a cutting area, it appears the perturbing episodes would reduce marine productivity for only a relatively short portion of the rotation cycle. How- ever, this conjecture requires confirmation. Public concerns about the impact of timber storage and transfer are being addressed in the Southeastern Tidelands Area Plan (SETAP) that is being developed bv the Alaska Department of Natural Resources. SETAP is intended to resolve issues concerning use of state tidelands and sub- merged lands through improved coordination and by expe- diting the decision-making process that is associated with such usage. The plan will be a basis for State land classifications. Two paper pulp mills are located in Southeast Alaska. One, in Ketchikan, began operation in 1954. The other, in 584 Issues and Perspectives Sitka, started operating in about I960. Both mills employ a dissolving sulfite process. In 1970-1971, the mills produced about 545 mtid of pulp. At that production rate (following chemical recovery and screening), about 1.7 x 104 m3/d of sulfite waste liquor (SWL) were generated by each mill. The SWL is discharged into local marine waters along with wood chips and other waste materials. When the water quality near the mills deteriorated, the pulp mill discharges were investigated by regulatory agen- cies (FWQA 1970; EPA 1971). Conditions observed near the mills included high concentrations of SWL, depressed dis- solved-oxygen levels, sludge accumulations on the sea floor, and reduced numbers of littoral biota. Both investigations produced recommendations for secondary treatment of the SWL effluents to reduce pollutant discharges and to bring the mills into compliance with state and federal water- quality standards. Achieving compliance has been difficult, and the issue is replete with a history of appeals, hearings, and studies. In early 1985, the Ketchikan mill operators agreed to install equipment to achieve compliance with the Clean Water Act (Anonymous 1985). The Sitka mill has yet to receive an operating permit from the EPA. Fish Processing Wastes. Marine dumping of fish- processing wastes has occurred in Alaska since the 1800s, but it only became a public policy issue when water quality dete- riorated in certain coastal locations. Fish- and shellfish-waste discharges from both mobile and shore-based processors at Kodiak, Dutch Harbor, and Akutan have caused pollution. Statistics illustrating magni- tudes of past discharges at those ports are presented inJSTT (1984a). At Dutch Harbor during the 1976 season, ~2.1 x 104 mt of waste was discharged. Discharges at Kodiak amounted to ~ 3.3 x 104 mt in 1971. The shore-based Trident Seafoods plant at Akutan released between 9- and 11 x 104 mt of cod- fish and crab wastes into Akutan Harbor before the plant was destroyed by fire in 1983, after being in operation for about one year. Sidescan sonar surveys of the harbor bottom shortly after the fire showed that the Trident waste pile was about 7 m thick and 200 m in diameter. The survey also detected another waste pile in the harbor that was still iden- tifiable five years after waste dumping had ceased. Processing wastes consist mainly of highly biodegradable constituents such as tissue solids, oil and grease, along with fluids from viscera, heads, bones, and other discarded mate- rials. Wastes are ground up before being discharged. The major constituents that are not highly biodegradable are crab and shrimp shells. Adverse effects from the wastes are coupled to dispersal regimes in the receiving waters. Nox- ious conditions occur when discharge rates exceed disper- sion and biodegradation rates. When there is insufficient water exchange, the biochemical oxygen demand produced by the decaying wastes can cause anoxia. Elevated ammonia levels also may be present. Sedentary benthos are physically smothered by waste accumulations, and visible floating sol- ids attract scavengers such as gulls or rodents, which may cause public health problems (Patten and Patten 1979). Finally, gull concentrations may be hazardous to aircraft in the vicinity of processors. The amount of waste generated by fish processing opera- tions depends upon processing rates, the species that is processed, and the type of processing that is used. The per- cent of waste ranges from between 30 and 35% for salmon, to between 73 and 85% for crabs (EPA 1983). Given those percentages and the recent regional fishery yields, the total annual tonnage of processing wastes discharged into the Gulf of Alaska appears to be 1.5- to 2.5 x 105 metric tons. In 1980, there were 302 applications for National Pollu- tant Discharge Elimination System (NPDES) permits to dis- charge fish processing wastes in Alaskan waters (EPA 1983). The heavy exploitation of currently important commercial fish and shellfish stocks indicates that on a regional basis, fish processing waste discharges will not increase much. Domestic processing wastes may increase if the United States industry gains control of the groundfishery. The rapid deterioration of many of the groundfish species soon after capture means that at least primary processing must occur quickly in order to maintain quality. Therefore, shore-based operations will be restricted to areas where the fish can be rapidly delivered from the grounds. Elsewhere, at least the primary processing has to be done at sea. Fish processing waste discharges may decrease if by-products such as meal and oil, fish silage, and chitin are made from the wastes (JSTT 1984b). The obstacles to by-product use in Alaska have included high production and shipping costs when compared with those of competitors that are located closer to markets, and lack of markets for the by-products. Both these obstacles could disappear if the demand increases. Municipal Wastes. The world's oceans have tradi- tionally been a repository for man's sewage, industrial byproducts, trash, and litter. Municipal wastes enter the marine environment in a variety of ways, the most prevalent being sewage outfalls, storm drains, streams, and ocean dumping. Some constituents of municipal wastes cause pub- lic health problems, adversely affect marine organisms, communities, and ecosystems, or result in aesthetic degrada- tion. Synthetic organic compounds, chlorinated com- pounds, microorganisms, trace metals, biostimulants, and litter are among those constituents that are the most fre- quently implicated. A summary of types of wastes, their fates, and their effects is presented in Goldberg (1979). Excluding the industrial wastes considered previously in this chapter, sources of municipal wastes in the Gulf of Alaska are relatively few, are dispersed, and are small in vol- ume when compared with the waste in other coastal states. The municipality of Anchorage is the largest contributor. In 1981, Anchorage (population then 165,000) released about 9.1 x 104 m3/d of wastewater into Knik Arm. Discharges of Sitka (pop. 8,000) and Haines (pop. 1,350) (which typify smaller coastal communities) were 6,600 and 790 m3/d, respectively. The amount of sewage treatment also varies through the region, ranging from secondary treatment (e.g., Kodiak, Wrangell, Haines) to primary treatment (Anchorage) to none (Sitka) (GAO 1981). Under section 301(h) of the Clean Water Act of 1977, the EPA can allow municipalities to discharge into marine waters sewage that Environmental Issues 585 has undergone less than secondary treatment if the munici- palities demonstrate that dispersion at the outfall will effec- tively dilute the wastewater. The concentration of population in upper (look Inlet has produced the only significant municipal waste pollution in the Gulf of Alaska region. In the early 1960s, Anchorage's raw sewage was discharged through several outfalls onto the broad apron of mudflats extending far offshore into Knik Arm. The outfall configurations caused serious bac- teriological contamination and floating sewage solids (ADHW 1964). In the early 1970s, a municipal trunk and interceptor system, a primary treatment plant that provides wastewater screening and chlorination, and a submarine outfall extending 4.6 m below mean lower low water were constructed (EPA 1982). While the new system alleviated some problems, beaches east of the outfall remained con- taminated. There was also concern that migrating salmon smolts would be affected by chlorinated compounds in the effluent. Due to the rapid population growth in the Anchorage metropolitan area, the existing system is nearing its design capacity and efforts are underway to improve it. The improvements include extending the outfall further offshore to reduce coliform bacterial contamination of the beaches. Stopping wastewater chlorination does not appear to be a viable alternative. Secondary treatment is considered unnecessary at present because the assimilative capacity of the Inlet is believed to be adequate for wastes produced by as many as 1.7 million people (EPA 1982). Non-Point Source Pollutants and Litter. In addition to easily identified sources such as Anchorage, pollutants enter the Gulf of Alaska in a dispersed fashion from vessel dis- charges, upland runoff, and wind and ocean current trans- port. Well-known pollutants with ubiquitous distributions include polycyclic aromatic hydrocarbons, certain nitrogen and sulfur compounds implicated in 'acid rain', organo- chlorine insecticide residues, and petroleum tarballs. Common types of marine litter include polystyrene spher- ules and various other plastics. Mobile pollutants such as DDT and acid rain have stirred international controversies between 'exporter' and 'recipient' countries. Non-point source pollution will become a larger issue as human popu- lations grow and more pollutants enter the biosphere. Relatively few investigations have been made on non- point source pollutants in the Gulf of Alaska. Some effort has been directed toward petroleum hydrocarbons and marine litter. Shaw (1977, 1981) performed reconnaissance surveys to estimate hydrocarbon concentrations at the sea surface, in the water column, in sediments, and in selected biota. Most of the work was done in Cook Inlet and in the Gulf of Alaska between Vakutat and Unimak Island. Most of the non-biogenic hydrocarbons appeared to originate from natural oil seeps, coal outcrops, aeolian transport of com- bustion products, and local pollution sources. Water samples collected in the Gulf indicated total hydrocarbon concentrations at or below the 1-ug/kg level. There was no evidence of petroleum in the samples. Surface tows captured very little floating tar. The estimated arith- metic-mean concentration of tar over the continental shelf of the Gulf was 3.8 x 10"' g/m2, two orders of magnitude below the concentration levels found along major tanker routes in the world ocean. Petroleum hydrocarbons were not observed in water-column samples from (look Inlet, presumably due to the intense tidal mixing in the upper and central portions of the Inlet, which rapidly disperses any hydrocarbons entering the system. However, fossil- and combustion-derived aromatic hydrocarbons were found in lower Cook Inlet sediment samples. Petroleum derived from previously identified oil seeps in the area was not encountered. Litter is ubiquitous on Gulf of Alaska beaches and has been observed in trawl hauls byjewett (1976). Much marine litter is attributable to fishing vessels and consists of long- lived plastic materials. Merrell (1984) found 122 to 345 kg/km of plastic litter of various kinds on 10 one-kilometer beaches of Amchitka Island in the western Aleutian Islands during a study period of 1972 to 1974 and again in 1982. Discarded trawl netting constituted the bulk of the litter in each year. The significant decline in litter between samplings was attributed to decreased numbers of foreign vessels operat- ing in the Gulf by the 1980s. Discarded plastic materials such as netting and uncut strapping are a serious source of entanglement and mortality of marine mammals, birds, and fish. Fowler (1982) estimated that at least 5% of the fur seal population may die annually due to direct effects of fish- eries, including entanglement in lost or discarded fishing gear. Over 200 salmon and 99 dead seabirds were found tan- gled in —1,500 m of monofilament gillnet that was adrift south of the Aleutian Islands (DeGange and Newby 1982). Multiple-use Conflicts Marine mammals and commercial, subsistence, and sport fisheries are among the subjects of the numerous mul- tiple-use conflicts present in the Gulf of Alaska. Marine Mammal-Commercial Fishery Conflicts. Marine mammal-commercial fishery conflicts have existed as long as both users have competed for fish and shellfish. In the Gulf of Alaska, these conflicts are most evident in the salmon troll and gillnet fisheries, the halibut longline fish- ery, and the king crab pot fishery. They center around both gear damage and the loss or damage of fish captured by the gear (Mate 1980). The marine-mammal species most fre- quently involved are sea lions and harbor seals. Because of those depredations, there was a bounty on harbor seals in Alaska from 1927 until the 1960s. Control programs con- ducted in the Copper River Delta and the Stikine River areas during the 1950s removed about 35,000 seals (Matkin and Fay 1980). Marine mammal-commercial fishery conflicts persist in the Copper River Delta. Matkin and Fay (1980) estimated that the monetary loss to the salmon fisheries in 1978 was about $350,000, or about 4% of the gross potential value of the fishermen's catch for that year. Of the 1,000 marine mammals that were killed during the 1978 fishery, approx- imately 90% were harbor seals and sea lions. Since protective legislation was enacted in the 1970s, many marine-mammal populations have grown rapidly, resulting in heightened conflicts. Predation on commercial 586 Issues and Perspectives fish and shellfish is increasing (see Calkins, Ch. 17, this vol- ume). For example, the burgeoning sea otter population in the Cordova area is believed to have markedly reduced local razor clam, Dungeness crab, and other invertebrate macro- benthos stocks. The Dungeness crab fishery in the area is depressed. Crab and clam stocks are unlikely to regain their former levels of abundance unless the number of sea otters decreases. Rosenthal (1977) predicted the current conflict between the crab fishery and the otters while studying otters and their habitats in Prince William Sound. Sea otters can forage to depths exceeding 40 m, and Rosenthal observed very intensive otter predation on both intertidal and sub- tidal invertebrates. Additional marine mammal-commercial fishery con- flicts will arise if forage species such as capelin and sand lance are commercially harvested. Trophic studies have shown that capelin and sand lance are among the most important prey species for both seabirds and marine mam- mals in the Gulf of Alaska (see DeGange and Sanger, Ch. 16, this volume; Calkins, Ch. 17, this volume). Because public attitudes about marine mammals have changed and protective legislation has been passed, manag- ers must use new approaches to fisheries management. Man- agers now must evaluate the impact of fisheries on mam- mals as well as the converse. Such complex considerations have helped spur the development of multi-species and ecosystem management models (see OCSEAP Staff, Ch. 14, this volume.) Marine Mammal-Tourism Conflicts. Humpback whale use of certain areas in the Alexander Archipelago has allegedly decreased because of both disturbance and dis- placement by heavy vessel traffic. The Endangered Species Act mandates that no 'taking' of endangered or threatened species, such as the humpback whale, shall occur. The term 'taking' is broadly interpreted to include not only capture, killing, and injury, but also harassment and other activities that disturb the animals (Chapman 1979). Vessel traffic linked to whale displacement can be construed as harassment. This controversy has been evident in Glacier Bay National Park and Preserve, where humpback whales tradi- tionally feed in summer. The area has also become a popu- lar cruise-ship destination. Whale numbers in the Bay have fallen during the past few summers (Baker, Herman, Bays, and Stifel 1982). Some believe that this change is related to the increased frequency of the cruise-ship visits, while oth- ers argue that it simply reflects the local availability of prey. Further details, both on the issue and on research efforts to resolve it, are presented in Baker, Herman, Bays, and Bauer (1983); Baker et al. (1982); and by Calkins (Ch. 17, this volume). Recreational-Commercial Fishery Conflicts. Through- out the nation, the competition between commercial and recreational fishery users is growing, and conflicts are now commonplace. Alaska is no exception, but such conflicts are currently evident mainly in the more densely populated Cook Inlet area. The Kenai River salmon fishery is a notable example. The River is famous, both for its chinook salmon — which attain weights exceeding 40 kg — and for its prolific sockeye salmon runs, which attract anglers from afar. Both salmon species are taken by contemporaneous commercial gillnet fisheries in the Inlet. Because spawning runs for the two species overlap both in time and in space, an allocation scheme that favors a sport fishery for chinook and a commercial fishery for sockeye has been implemented with varying degrees of success. The commercial sockeye fishery invariably intercepts some Kenai chinooks. In order to maintain a viable stock, a cer- tain minimal number of spawners must escape. This means that the anglers' catch must sometimes be reduced. Restriction of the sport fishery in the River imposes eco- nomic hardships on guides and others who cater to sport fishermen. Restrictions are also perceived by the anglers as inequitable, because they believe they have been denied an equal opportunity to harvest an open-access (i.e., com- mon-property) resource. As a partial solution to the problem, fish traps could be installed at the mouth of the Kenai River that would selec- tively release enough chinook and sockeye for a sport fish- ery as well as meet spawning management goals. This would also provide an economic substitute for the existing com- mercial fishery. Fish traps were outlawed in Alaska soon after statehood. But, as noted by Straight (1980), there are powerful economic and resource-management arguments in favor of their use, and perhaps one day they will become legal again. Subsistence-related Conflicts. Subsistence is perhaps the most volatile open-access resource issue in Alaska. Since passage of ANILCA, both federal and state fish and game management policies as well as court decisions have given preference to rural residents because the opportunities to earn a cash income are limited and purchased foods may be supplemented with wild fish and game (see Kelso 1981a, 1981b, 1982). Also, living off the land is a traditional way of life in many rural Alaskan communities. However, many urban Alaskans believe that their rights are being abridged by the current policies. In response, the Alaska Department of Fish and Game has formed a Subsistence Division to deal with this complex and controversial issue. The subsistence issue is not yet a major concern with respect to the marine environment, but it relates to alloca- tion of salmon. Large numbers of salmon are captured for subsistence after they enter the rivers. This means that sub- sistence users compete with both commercial and sport fish- ermen for the resource. One potential consequence of an excessive ocean catch is the restriction or the closure of sub- sistence fisheries to ensure that spawning-escapement requirements are met. The subsistence issue has thus far focused on big game such as moose and caribou; however, it seems inevitable that as the population and the competition for resources continue to grow, subsistence issues will extend to the coastal areas as well. Environmental Hazards Various environmental hazards are present in the Gulf of Alaska. Seismicity, volcanism, storms, and other geophysical phenomena present significant threats to both people and property. Environmental Issues 587 Large and relatively frequent earthquakes are charac- teristic of essentially the entire coastline (see Jacob, Ch. 6, this volume). This hazard is exemplified most vividly by the Great Alaskan Earthquake of 1964, which caused 115 deaths and an estimated $330 million in damages in the coastal region. The Great Alaskan Earthquake is extensively docu- mented in an eight-volume. National Academy of Sciences- sponsored report (NRG 1972). A comparably large event may occur soon in the Shumagin seismic gap (Jacob 1983). Continued population growth in the Railbelt will increase the potential for a catastrophe if another great earthquake occurs. The rupture zones of major regional earthquakes often extend for hundreds of kilometers (Sykes, Kisslinger, House, Davies, and Jacob 1980), so the epi- center need not be close to produce damaging results. While regional seismotectonics are fairly well understood, addi- tional, more localized information is needed in order to develop intelligent land-use policies, building codes and practices, and public safety plans that will mitigate the con- sequences of a major seismic event (see Jacob, Ch. 6, this volume). The tsunamis and seiches generated by the Great Alaskan Earthquake of 1964 caused 90% of the deaths in Alaska, along with heavy property damage and fatalities as far away as Crescent City, California. The tsunami produced by the Earthquake was even observed in Antarctica (Selkregg 1974). Landslides and icefalls in coastal embayments also cause loss of life and property in the Gulf. In Lituya Bay, a land- slide in 1958 produced a wave with a runup that reached 530 m above sea level and drowned two fishermen. In 1845, approximately 100 Natives were killed in Yakutat Bay by a wave that was apparently produced by an ice-fall at the head of the Bay (Cox and Pararas-Carayannis 1976). Volcanism is a significant environmental hazard owing to the large number of active, violently eruptive volcanoes similar to Mount St. Helens in Washington State. The Kat- mai eruption of 1912 and eruptions of Mount Augustine in Cook Inlet were comparable events. The social impacts of past eruptions have been limited because there were few people in the danger zones of the events. As the volcanic zone becomes more populated, the potential for a catastro- phe will grow. The hazards associated with volcanism both in Cook Inlet and on the Alaskan Peninsula have been described bv Pulpan and Kienle (1981), Kienle and Swanson (1983), McNutt (1983), and Jacob (Ch. 6, this volume). Near-field volcanic hazards such as pyroclastic flows, dry debris avalanches, wet debris flows, and flood deposits pre- sent the greatest threat. Far-field hazards include ashfalls, acid rain, and tsunamis caused by mass wasting. For exam- ple, some of Mount Augustine's eruptions have produced tsunamis in Cook Inlet. Flash flooding can also result when ice and snow are rapidly melted by subglacial heating. This is a serious hazard in some areas; such volcano-glacier inter- action has occurred at Mounts Katmai and Redoubt (Pulpan and Kienle 1981). Sediment has been deposited at high rates during the Holocene period, and this has led to unstable sediments in the Gulf of Alaska (Hampton, Carlson, Lee, and Feely, Ch. 5, this volume). Unstable sediments are especially prevalent in the northeastern Gulf, where submarine slumps and slides are commonplace. Some cover areas, exceeding 100 km2, have thicknesses of hundreds of meters, and occur on slopes of less than one degree. Unstable sediments are of major concern for the offshore petroleum industry because they can shift and cause structural damage or even failure of the bottom-founded production platforms and pipelines. Many parts of the Gulf of Alaska coastline are undergo- ing rapid change due to ongoing tectonic, glacial, and ero- sive processes. Such activity has been documented in Prince William Sound, Cook Inlet, near Icy Bay, and elsewhere (NRC 1968; Peterson 1979, 1980; and Hampton el ai, Ch. 5, this volume). The implications of rapid coastal erosion or accretion can be considerable. Remedial measures such as the construction of jetties and groins to stabilize beaches, the use of maintenance dredging, or the use of rip-rapping are not only costly, but are often ineffective measures that may themselves produce unforeseen adverse changes. The Alaska Coastal Management Plan denotes areas of signifi- cant geophysical hazard as "areas meriting special attention." Hazards produced by the weather must be included here because the Gulf of Alaska is one of the stormiest oceanic regions in the world. Conditions that are dangerous to mari- ners occur frequently; they include large seas, high winds and, during winter, vessel icing. The same weather also often affects the coastal areas, as documented by Wise, Com- iskey, and Becker (1981). During the winter of 1984-1985, high winds and high tides combined to cause extensive damage and property loss along the waterfronts of Juneau (the state capital), and several other communities in south- eastern Alaska. The Future Having described the underlying factors and issues that have affected oceanographic research in the Gulf of Alaska, it remains to look to the future. A review of two of Alaska's growth forecasts (APU 1984; Morehouse 1984) suggests the following: • Fisheries will remain a major issue — with perhaps some shift of emphasis from 'traditional' fisheries to the groundfisheries and the fisheries for currently unexploited species. • The forest-products industry is expected to experi- ence slow growth, so both logging and pulp-produc- tion issues will remain essentially unchanged. • Oil production in Cook Inlet will decline; however, the level of activity at Port Valdez will remain high into the twenty-first century. • Mining and associated transfer operations could become very important issues if large-scale coal exports or hard-rock mining projects occur. Development in any of these areas will depend on both favorable national and favorable international market conditions. The continued population growth in the Cook Inlet area will exacerbate the existing multiple-use conflicts between subsistence, commercial, and recreational fishery users and 588 Issues and Perspectives will likely generate other open-access resource conflicts. Municipal waste discharges into the marine environment will not assume significantly greater near-term importance because most population growth is expected in upper Cook Inlet where dispersion is highly efficient. Pollution from fish wastes should not significantly increase. Litter is pres- ently the most evident and obtrusive form of non-point source pollution in the Gulf of Alaska. It will become less of a problem only if public attitudes change, regulation and enforcement improve, and use of recalcitrant materials such as plastics for containers and other disposable items decreases. Non-point source pollution will become a larger issue as both regional and global populations grow. Energy systems in the coastal zone may become a major regional issue because the Gulf is rich in potential power sources, and the population growth in Cook Inlet will increase the demand for energy. Possible energy technolo- gies include plants that use coal, the tides, or geothermal energy" to generate electricity. These potential energy sys- tems are described in Davis (1984). Coal-fired electricity generation is particularly attractive because the Beluga coal field is nearby and Cook Inlet offers a virtually unlimited supply of cooling water. Exporting Beluga coal to the Far East would introduce economies of scale in fueling the plant and would improve the economic aspects of both projects. The environmental problems that would arise from a coastal coal-fired power plant could include air pollution, ash disposal, thermal pollution, entrainment of organisms, and the formation of toxic chlorination products (Hall, Howarth, Moore, and Vorosmarty 1978). Upper Cook Inlet, with its large tidal range ( ~ 7.5 m), is among the world's best sites for tidal power generation. Pre- liminary studies suggest that up to 7.5 x 104 gigawatt-hours of energy could be produced annually (Davis 1984). Such a project would raise issues concerning sediment transport through the Inlet, seasonal ice, anadromous fish migration, and navigation. Geothermal activity is commonplace in the northern Gulf of Alaska due to active tectonism and volcanism. Pre- liminary evaluations of the geothermal energy potential have been conducted by the state and federal agencies. The volcanoes of the Aleutian Island chain are obvious examples of energy sources that could be tapped. Their remoteness now precludes their consideration as a viable alternative to more conventional methods of electrical power generation. As the region's population grows and the cost of fossil fuels continues to rise, geothermal energy generation may become economical. Potential problems associated with the marine waste-water discharges that come from geothermal plants include localized temperature increases, the toxic constituents of the effluent, and anoxia. Acknowledgments I thank Neil Davis, University of Alaska, Douglas Wolfe, NOAA, and an anonymous reviewer for critical reviews of the document. Thanks also to the Minerals Management Service Alaska OCS Region staff and the book's scientific and production editors for many constructive questions and helpful suggestions. The preparation of this chapter was supported, in part, by the Minerals Management Serv- ice, Department of the Interior, through an interagency agreement with the National Oceanic and Atmospheric Administration, Department of Commerce, as part of the Outer Continental Shelf Environmental Assessment Program. References Adasiak, A. 1978 The Alaskan experience with limited entry. In: Limited Entry as a Fishery Management Tool: Pro- ceedings of a National Conference to Consider Limited Entry as a Tool in Fishery Management, Denver, July 17-19, 1978. R.B. Rettig andJ.C. Ginter, editors. Washington Sea Grant Publication, University of Washington, Seattle, WA. pp. 271-299. Alaska Department of Environmental Conservation (ADEC) 1971 Inventory of water dependent log handling and storage facilities in Alaska. State of Alaska Department of Environmental Conservation. 36 pp. Alaska Department of Health and Welfare (ADHW) 1964 The pollution of the waters of Knik Arm by waste disposal practices in the greater Anchorage area. State of Alaska Department of Health and Welfare, Southcentral Regional Office, Anchorage, AK. 15 pp. Alaska Geological Society (AGS) 1970 Oil and gas fields in the Cook Inlet Basin, Alaska. Alaska Geological Society, Anchorage, AK. 84 pp. Alton, M. 1981 Gulf of Alaska bottomfish and shellfish resources. National Marine Fisheries Service, Northwest & Alaska Fisheries Center, NOAA Technical Memorandum NMFS F/NWC-10. 51 pp. Anonymous 1985 "Pulp mill, EPA reach accord." News item in Alaska from the Inside (an information service of Alaska Construction & Oil Co. Magazine, Anchorage, AK) Vernon Publishers Inc., Seattle, WA. January 9, 1985. Alaska Oil and Gas Conservation Commission (AOGCC) 1985 Oil and gas production data compiled by the Alaska Oil and Gas Conservation Commission through 11/84. Alaska Report 31(4) (Attachment). Petroleum Information Corporation, Anchorage, AK. Environmental Issues 589 Alaska Pacific University (APU) 1984 A Delphi forecast of Alaska's development: the year 2000 and beyond. Report to State of Alaska Department of Commerce and Eco- nomic Development. Alaska Pacific University, Anchorage, AK. Paginated by chapter. Baker, C.S., L.M. Herman, B.G. Bays, and W.F. Stifel 1982 The impact of vessel traffic on the behavior of humpback whales in Southeast Alaska. Report prepared for National Marine Fisheries Serv- ice, National Marine Mammal Laboratory, Seattle, WA. University of Hawaii at Manoa, Honolulu, HI. 39 pp. Baker, C.S., L.M. Herman, B.G. Bays, and G.B. Bauer 1983 The impact of vessel traffic on the behavior of humpback whales in Southeast Alaska, 1982 season. Report prepared for National Marine Fisheries Service, National Marine Mammal Laboratory, Seattle, WA. University of Hawaii, Honolulu, HI. 30 pp. Baram, M.S., D. Rice, and W. Lee 1978 Marine Mining of the Continental Shelf: Legal, Tech- nical and Environmental Considerations. Balinger Publishing Co., Cambridge, MA. 301 pp. Bayliss, R. and R. Spoltman 1981 The wreck of the Lee Wang Zin. In: 1981 Oil Spill Conference (Prevention, Behavior, Control, Cleanup). R.B. Parrotte, editor. Publication No. 4334, American Petroleum Institute, Washington, D.C. pp. 221-226. Berman, M.D. 1984 Renewable resources. In: Alaska Resources Devel- opment: Issues of the 1980s. T.A. Morehouse, edi- tor. Institute of Social and Economic Research, University of Alaska, Fairbanks, AK and West- view Press, Boulder, CO. pp. 105-134. Bockstoce, J. 1978 History of commercial whaling in arctic Alaska. Alaska Geographic 5(4):l7-25. Browning, R.J. 1980 Fisheries of the North Pacific: History, Species, Gear & Processes. Alaska Northwest Publishing Co., Anchorage, AK. 423 pp. Chapman, D.G. 1979 Marine mammals and ecosystem management. In: Alaska Fisheries: 200 Years and 200 Miles of Change. Proceedings of the Twenty-ninth Alaska Sci- ence Conference. B.R. Melteff, editor. Sea Grant Report 79-6, University of Alaska, Fairbanks, AK. pp. 85-94. Clague, D., J. Bischoff, and D. Howell 1984 Nonfuel mineral resources of the Pacific Exclusive Economic Zone. In: '84 OCEANS Con- ference Record, Vol. 1. Conference Sponsored by: Marine Technology Society, IEEE Ocean Engineering Society, Washington, D.C, Sep- tember 10-12, 1984. IEEE Service Center, Piscataway, NJ. and Marine Technology Soci- ety, Washington, D.C. pp. 438-443. Clark, R.B., editor 1982 The long-term effects of oil pollution on marine populations, communities and eco- systems. Philosophical Transactions of the Royal Society of London, Series B 297:183-443. Colonell, J.M., editor 1980 Port Valdez, Environmental Studies 1976-1979. Occasional Publication No. 5, Institute of Marine Science, University of Alaska, Fair- banks, AK. 373 pp. Cox, D.C. and G. Pararas-Carayannis 1976 Catalog of tsunamis in Alaska. Report SE-1. World Data Center A for Solid Earth Geo- physics, Boulder, CO. 43 pp. Crutchfield, J.A. and G. Pontecorvo 1969 The Pacific Salmon Fisheries: A Study of Irrational Conservation. Johns Hopkins Press, Baltimore, MD. 220 pp. Community and Systems Analysis (CSA) 1982 Skagway coastal management plan public hear- ing. Report prepared for Skagway Coastal Management Program. Community and Sys- tems Analysis, Bainbridge Island, WA. 170 pp. Davis, N. 1984 Energy Alaska. University of Alaska Press, Fair- banks, AK. 530 pp. DeGange, A.R. and T.C. Newby 1982 Mortality of seabirds and fish in a lost salmon driftnet. Marine Pollution Bulletin 11: 322-323. Dolgin, E.L. and T.G.P. Guilbert 1974 Federal Environmental Law. West Publishing Co., St. Paul, MN. 1,600 pp. Ellis, RJ. 1973 Preliminary biological survey of log-rafting and dumping areas in southeastern Alaska. Marine Fisheries Review 35(5-6):19-22. Environmental Protection Agency (EPA) 1971 Effects of pulp mill wastes on receiving waters at Silver Bay, Alaska. Environmental Protec- tion Agency Water Quality Office, Northwest Region, Alaska Operations Office, Anchorage, AK. 64 pp. 590 Issues and Perspectives Environmental Protection Agency (EPA) 1982 Draft environmental impact statement: munic- ipality of Anchorage sewerage facilities expan- sion. Report prepared for EPA with technical assistance from Jones & Stokes, Inc. Environ- mental Protection Agency Region 10, Seattle, WA. 222 pp. Environmental Protection Agency (EPA) 1983 Draft NPDES permit for discharges from Alas- kan seafood processors and associated attach- ments. Provided as enclosures in a memorandum from Environmental Protection Agency Region 10 Director, dated December 1, 1983. Fay, F.H. 1979 Industrial utilization of marine mammals. In: Alaska Fisheries: 200 Years and 200 Miles of Change. Proceedings from the Twenty-ninth Alaska Science Conference. B.R. Melteff, editor. Sea Grant Report 79-6, University of Alaska, Fairbanks, AK. pp. 75-79. Fowler, C.W. 1982 Interactions of northern fur seals and commer- cial fisheries. In: Transactions of the Forty-seventh North American Wildlife Natural Resources Con- ference. K. Sabol, editor. Wildlife Management Institute, Washington, D.C. pp. 278-292. Francis, R.C. 1985 Fisheries research and its application to West Coast groundfish management. In: Fisheries Management: Issues and Options. Proceedings of a Conference Held in Anchorage, Alaska, November 13-16, 1984. T. Frady, editor. Sea Grant Report 85-2, University of Alaska, Fairbanks, AK. pp. 285-304. Federal Water Quality Administration (FWQA) 1970 Effects of pulp mill wastes on receiving waters at Ward Cove, Alaska. U.S. Department of Interior, Federal Water Quality Adminstra- tion, Northwest Region, Alaska Operations Office, Anchorage, AK. 48 pp. General Accounting Office (GAO) 1981 Report to the Congress, entitled "Billions could be saved through waivers for coastal wastewater treatment plants." Report No. CED-81-58. General Accounting Office, Gaithersburg, MD. 55 pp. Group of Experts on the Scientific Aspects of Marine Pollution (GESAMP) 1977 Impact of oil on the marine environment. Group of Experts on the Scientific Aspects of Marine Pollution, United Nations, FAO, Rome. 250 pp. Goldberg, E.D., editor 1979 Proceedings of a Workshop on Scientific Problems Relating to Ocean Pollution, Estes Park, Colorado, July 10-14, 1978. NOAA Environmental Research Laboratories, Boulder, CO. 225 pp. Gorham, A.H. 1979 Joint venture policy and the future of Alaska's groundfishery. In: Alaska Fisheries: 200 Years and 200 Miles of Change. Proceedings from the Twenty- ninth Alaska Science Conference. B.R. Melteff, edi- tor. Sea Grant Report 79-6, University of Alaska, Fairbanks, AK. pp. 513-522. Gorsline, D.S. 1979 Shelf-sediment dynamics and solid-waste dis- posal. In: Ocean Dumping and Marine Pollution. H.D. Palmer and M.G. Gross, editors. Dowden, Hutchinson & Ross, Inc., Stroudsburg, PA. pp. 9-15. Griffiths, R.P., B.A. Caldwell, W.A. Broich, and R.Y. Morita 1982 The long-term effects of crude oil on micro- bial processes in subarctic marine sediments. Estuarine, Coastal and Shelf Science 15:183-198. Gundlach, E.R. and P.D. Boehm 1981 Determine fates of several oil spills in coastal and offshore waters and calculate a mass bal- ance denoting major pathways for dispersion of spilled oil. Final report prepared for NOAA Puget Sound Project Office. Research Plan- ning Institute, Columbia, SC and ERCO, Inc., Cambridge, MA. 28 pp. Gundlach, E.R., P.D. Boehm, M. Marchand, R.M. Atlas, D.M. Ward, and D.A. Wolfe 1983 The fate of Amoco Cadiz oil. Science 221:122-129. Gusey, W.E. 1978 The Fish and Wildlife Resources of the Western Gulf of Alaska. Environmental Affairs, Shell Oil Co., Houston, TX. 580 pp. Gusey, W.E. 1979 The Fish and Wildlife Resources of the Gulf of Alaska. Environmental Affairs, Shell Oil Co., Houston, TX. 334 pp. Hall, C.A.S., R. Howarth, B. Moore HI, and C.J. Vdrosmarty 1978 Environmental impacts of industrial energy systems in the coastal zone. Annual Review of Energy 3:395-475. Hall, W. and J. Hickey 1983 Report and recommendations of the Alaska Fishery Policy Task Force. State of Alaska, Juneau, AK. 200 pp. Environmental Issues 591 Hansen, G., G. Carter, W. Towne, and G. O'Neal 1971 Log storage and rafting in public waters. Pacific Northwest Pollution Control Council. 54 pp. Hammond, K. and A. Green 1980 Fisheries management under the Fishery Con- servation and Management Act, the Marine Mammal Protection Act, and the Endangered Species Act. Final report to Marine Mammal Commission prepared by Ecosystem Model- ing, Houston, TX. 52 pp. plus appendices. Heiner, L.E., E.N. Wolff, and D.G. Grybeck 1971 Copper mineral occurrences in the Wrangell Mountain-Prince William Sound area, Alaska. Mineral Industry Research Laboratory Report No. 27, University of Alaska, Fairbanks, AK. 179 pp. Helle,J.H. 1976 Genetic considerations for salmonid aqua- culture: biological uncertainties. In: Proceedings of the Conference on Salmon Aquaculture and the Alaskan Fishing Community, January 9, 10, and 11, 1976, Cordova, AK. D.H. Rosenberg, editor. Sea Grant Report 76-2, University of Alaska, Fair- banks, AK. pp. 171-190. Houghton, J.P., K.R. Critchlow, D.C. Lees, R.D. Czlapinski, R.C. Miller, R.P. Britch, andJ.C. Mills 1981 Fate and effects of drilling fluids and cuttings discharges in lower Cook Inlet, Alaska and on Georges Bank. Final report prepared for NOAA and BLM. Dames and Moore, Seattle, WA and Northern Technical Services, Anchorage, AK. Paginated by section. Hutchinson, O.K. and V.J. LaBau 1975 The forest ecosystem of Southeast Alaska. 9. Timber inventory, harvesting, marketing, and trends. Technical Report PNW-34, Pacific Northwest Forest and Range Experiment Sta- tion, USDA Forest Service, Portland, OR. 57 pp. Jacob, K. 1983 Seismic hazards. In: A seismotectonic analysis of the seismic and volcanic hazards in the Pri- bilof Islands-eastern Aleutian Islands region of the Bering Sea. Final report prepared for Outer Continental Shelf Environmental Assessment Program. Lamont-Doherty Geo- logical Observatory, Palisades, NY. pp. 117-121. Jewett, S. 1976 Pollutants of the northeast Gulf of Alaska. Marine Pollution Bulletin 7:169. Jones & Stokes and Tetra Tech (JSTT) 1984a Effects of seafood waste deposits on water qual- ity and benthos: Akutan Harbor, Alaska. Report prepared for EPA. Jones 8c Stokes and Tetra Tech, Bellevue, WA. 81 pp. Jones 8c Stokes and Tetra Tech (JSTT) 1984b Alternative seafood waste disposal methods at Akutan Harbor, Alaska. Report prepared for EPA. Jones 8c Stokes and Tetra Tech, Bellevue, WA. 98 pp. Kaill, W.M. 1979 Alaska's private nonprofit hatchery programs: a social experiment. In: Alaska Fisheries: 200 Years and 200 Miles of Change. Proceedings of the Twenty-ninth Alaska Science Conference. B.R. Melteff, editor. Sea Grant Report 79-6, Univer- sity of Alaska, Fairbanks, AK. pp. 455-458. Kelley, E.J. and D.W. Hood, editors 1973 Aquaculture in Alaska. Public Information Bui letin 73-1, Institute of Marine Science, Univer- sity of Alaska, Fairbanks, AK. 20 pp. Kelso, D.D. 1981a Presentation to the Special Committee on Sub- sistence, House of Representatives, Alaska State Legislature. Technical Paper No. 63, Alaska Department of Fish and Game, Division of Subsistence, Juneau, AK. 8 pp. Kelso, D.D. 1981b Technical overview of the state's subsistence program. Technical Paper No. 64, Alaska Department of Fish and Game, Division of Sub- sistence, Juneau, AK. 34 pp. plus appendices. Kelso, D.D. 1982 Subsistence use of fish and game in Alaska. Considerations in formulating effective man- agement policies. Technical Paper No. 65, pre- pared for the Forty-seventh North American Wildlife and Natural Resources Conference, Special Session on Alaska, Portland, Oregon, March 31, 1982. Alaska Department of Fish and Game, Division of Subsistence, Juneau, AK. 28 pp. Kienle, J. and S.E. Swanson 1983 The hazards of Augustine. Northern Engineer 15:10-14, 30-37. Kresge, D.T., T.A. Morehouse, and G.W. Rogers 1977 Issues in Alaska Development. Institute of Social and Economic Research, University of Alaska. Universitv of Washington Press, Seattle, WA. 223 pp. 592 Issues and Perspectives Leatherwood, S., A.E. Bowles, and R.R. Reeves 1983 Endangered whales of the eastern Bering Sea and Shelikof Strait, Alaska: results of aerial sur- veys, April 1982 through April 1983 with notes on other animals seen. Final report prepared for Outer Continental Shelf Environmental Assessment Program. Hubbs Sea World Research Institute, San Diego, CA 320 pp. Like, I. 1976 The frontiers of the National Environmental Policy Act. In: Environmental Legislation: A Source- book. M.R. Sive, editor. Praeger, New York, NY. pp. vi-xiv. Lysyj, I., R. Rushworth, R. Melvold, and J. Farlow 1979 Effectiveness of a large-scale ballast treatment process. In: Proceedings, 1979 Oil Spill Conference, March 19-22, 1979, Los Angeles, California. J.O. Ludwigson editor. Publication No. 4308, Amer- ican Petroleum Institute, Washington, D.C. pp. 133-137. Malins, D.C, editor 1977 Effects of Petroleum on Arctic and Subarctic Marine Environments and Organisms. Academic Press, New York, NY. 2 Vols. Malins, D.C. 1982 Alterations in the cellular and subcellular structure of marine teleosts and invertebrates exposed to petroleum in the laboratory and field: a critical review. Canadian Journal of Fish- eries and Aquatic Sciences 39:877-889. Malins, D.C. and H.O. Hodgins 1981 Petroleum and marine fishes: a review of uptake, disposition, and effects. Environmental Science and Technology 15:1272-1280. Malins, D.C, H.O. Hodgins, U. Varanasi, S-L. Chan, B.B. McCain, D.D. Weber, and D.W. Brown 1982 Sublethal effects of petroleum hydrocarbons and trace metals, including biotransforma- tions, as reflected by morphological, chemical, physiological, pathological, and behavioral indices. Outer Continental Shelf Environmental Assessment Program, Final Reports of Principal Investigators 29:1-229. Mate, B.R. 1980 Workshop on marine mammal-fishery interac- tions in the northeastern Pacific, held at the University Towers, Seattle, WA., 19-20 December 1977. Final report prepared for Marine Mammal Commission, Washington D.C. Oregon State University, Newport, OR. 46 pp. Matkin, CO. and F.H. Fay 1980 Marine mammal-fishery interactions on the Copper River and in Prince William Sound, Alaska, 1978. Final report to the Marine Mam- mal Commission. Institute of Marine Science, University of Alaska, Fairbanks, AK. 71 pp. McNutt, S. 1983 Volcanic hazards. In: A seismotectonic analysis of the seismic and volcanic hazards in the Pri- bilof Islands-eastern Aleutian Islands regions of the Bering Sea. Final report prepared for Outer Continental Shelf Environmental Assessment Program. Lament-Doherty Geo- logical Observatory, Palisades, NY. pp. 122-135. Menzie, D.A. 1982 The environmental implications of offshore oil and gas activities. Environmental Science and Tech- . nology 16:454a-472a. Merrell, T.R., Jr. 1984 A decade of change in nets and plastic litter from fisheries off Alaska. Marine Pollution Bul- letin 15:378-384. Miles, E., S. Gibbs, D. Fluharty, C Dawson, D. Teeter, W. Burke, W. Kaczynski, and W. Wooster 1983 The Management of Marine Regions: The North Pacific. University of California Press, Berkeley, CA. 656 pp. Mitchell, D.C, J.D. Morgan, CA. Vigers, and P.M. Chapman 1985 Acute toxicity of mine tailings to four marine species. Marine Pollution Bulletin 16:450-455. Moore, J.R. 1978 Summary of non-renewable resources. In: Pro- ceedings of a MESA workshop on Prince William Sound. B. Melteff, editor. Sea Grant Report 78-9, University of Alaska, Fairbanks, AK. pp. 50-59. Morehouse, T.A., editor 1984 Alaska Resources Development: Issues of the 1980s. Institute of Social and Economic Research, University of Alaska. Westview Press, Boulder, CO. 212 pp. Morgan, L. 1978 Modern shore-based whaling. Alaska Geo- graphic 5(4):34-43. National Research Council (NRC) 1972 The Great Alaskan Earthquake of 1964. National Research Council, National Academy of Sci- ences, Washington, D.C. 8 Vols. Environmental Issues 593 National Research Council (NRC) 1983 Drilling discharges in the marine environment. National Research Council, National Academy of Sciences. National Academy Press, Wash- ington, D.C. 180 pp. National Research Council (NRC) 1985 Oil in the Sea: Inputs, Fates and Effects. National Research Council, National Academy of Sci- ences. National Academy Press, Washington, D.C. 601 pp. Ohlendorf, H.M., R.W. Risebrough, and R. Vermeer 1978 Exposure of marine birds to environmental pollutants. U.S. Fish Wildlife Service Research Report 9. 41 pp. (Cited In: S.J. Starr, M.N. Kuwada and L.L. Traskey. 1981. Recommenda- tions for minimizing the impacts of hydrocar- bon development on the fish, wildlife, and aquatic plant resources of the northern Bering Sea and Norton Sound. Alaska Department of Fish and Game, Anchorage, AK.) Patten, S.M. and L.R. Patten 1979 Part III: pathobiology. In: Evolution, patho- biology, and breeding ecology of large gulls (Larus) in the northeast Gulf of Alaska and effects of petroleum exposure on the breeding ecology of gulls and kittiwakes. Environmental Assessment of the Alaskan Continental Shelf, Final Reports of Principal Investigators 18:291-314. Payne, J.R. and R.E.Jordan 1979 The fate and weathering of petroleum spilled in the marine environment: a literature review and synopsis. Final report prepared for Outer Continental Shelf Environmental Assessment Program. Science Applications, Inc., Lajolla, CA. 157 pp. Pendley, W.P. 1984 The importance of the EEZ Proclamation. In: Symposium Proceedings. A National Program for the Assessment and Development of the Mineral Resources of the United States Exclusive Economic Zone, November 15, 16, 17, 1983. U.S. Geological Survey Circular 929. pp. 3-9. (available from Distribution Branch, Text Products Section, USGS, Alexandria, VA) Pennoyer, S. 1979 Development of management of Alaska's fish- eries. In: Alaska Fisheries: 200 Years and 200 Miles of Change. Proceedings of the Twenty-ninth Alaska Science Conference. B.R. Melteff, editor. Sea Grant Report 79-6, University of Alaska, Fairbanks, AK. pp. 17-25. Peterson, R.E. 1979 Geologic hazards to petroleum exploration and development in lower Cook Inlet. In: Lower Cook Inlet interim synthesis report. K.B. Macdonald, editor. Prepared for Outer Conti- nental Shelf Environmental Assessment Pro- gram. Science Applications, Inc., Boulder, CO. pp. 50-70. Peterson, R.E. 1980 Geological hazards. In: Northeast Gulf of Alaska interim synthesis report. J.G. Strauch, Jr., editor. Prepared for Outer Continental Shelf Environmental Assessment Program. Sci- ence Applications, Inc., Boulder, CO. pp. 11-37. Pitcher, K.W. 1984 The harbor seal (Phoca vitulina richardsi). Marine mammal species accounts, April 1984. Alaska Department of Fish and Game. 8 pp. Pulpan, H. and J. Kienle 1981 Seismic and volcanic risk studies: western Gulf of Alaska. Annual report for period 1/1/80-12/31/80 submitted to Outer Continental Shelf Environmental Assessment Program. Geophysical Institute, University of Alaska, Fairbanks, AK. 93 pp. Rearden,J. 1981 Herring: an uncommon common fish. Alaska Magazine 47(6):17-19 and 47(7):16-19, 54-55. Reeves, R.R., S. Leather-wood, S.A. Karl, and E.R. Yohe 1984 Whaling results at Akutan (1912-1939) and Port Hobron (1926-1937), Alaska. Report of the Inter- national Whaling Commission 35:441-457. Rice, S.D., D.A. Moles, J.F. Karinen, S. Korn, M.G. Carls, O.O. Broderson, J.A. Gharrett, and M.M. Babcock 1984 Effects of petroleum hydrocarbons on Alaskan aquatic organisms: a comprehensive review of all oil effects research on Alaskan fish and invertebrates conducted by the Auke Bay labo- ratory, 1970-1981. NOAA Technical Memoran- dum NMFS F/NWC-67. 128 pp. Rice, S.D., A. Moles, T.L. Taylor, and J.F. Karinen 1979 Sensitivity of 39 Alaskan marine species to Cook Inlet crude oil and No. 2 fuel oil. In: Pro- ceedings, 1979 Oil Spill Conference (Prevention, Behavior, Control, Cleanup). J.O. Ludwigson, edi- tor. Publication No. 4308, American Petroleum Institute, Washington, D.C. pp. 549-554. 594 Issues and Perspectives Richardson, J. A. and F.L. Orth 1979 The historical role of regulation of foreign fish- ing in the development of Alaska's shellfish industry'. In: Alaska Fisheries: 200 Years and 200 Miles of Change. Proceedings of the Twenty-ninth Alaska Science Conference. B.R. Melteff, editor. Sea Grant Report 79-6, University of Alaska, Fairbanks, AK. pp. 491-501. Ronholt, L.L., H.H. Shippen, and E.S. Brown 1977 Demersal fish and shellfish resources of the Gulf of Alaska from Cape Spencer to Unimak Pass, 1948-1976: a historical review. Environmen- tal Assessment of the Alaskan Continental Shelf Final Reports of Principal Investigators 2:1-955. Rosenberg, D.H., editor 1976 Proceedings of a Conference on Salmon Aquaculture and the Alaskan Fishing Community, January 9, 10, 11, 1976, Cordova, Alaska. Sea Grant Report 76-2, University of Alaska, Fairbanks, AK. 302 pp. Rosenberg, D.H., editor 1977 Proceedings of the Second Alaska Aquaculture Con- ference, January 7, 8, 9, 1977, Wrangell, Alaska. Sea Grant Report 77-7, University of Alaska, Fair- banks, AK. 78 pp. Rosenthal, RJ. 1977 Sea otters and their subtidal habitats in Prince William Sound, Alaska. Report prepared for U.S. Fish and Wildlife Service. Dames and Moore, Inc., Anchorage, AK. 127 pp. Ryan, PJ. 1983 Study of submarine tailings disposal in Boca de Quadra — summary report. Prepared for U.S. Borax and Chemical Corporation, Los Angeles, CA. Bechtel Civil and Minerals, San Francisco, CA. 123 pp. Selkregg, L.L. 1974 Alaska regional profiles: southcentral region. Prepared for State of Alaska. Arctic Environ- mental Information and Data Center, Univer- sity of Alaska, Anchorage, AK. 255 pp. Shaw, D.G. 1977 Pelagic tar and plastic in the Gulf of Alaska and Bering Sea. Science Total Environment 8:13-20. (Reference not seen.) Shaw, D.G. 1981 Hydrocarbons: natural distribution and dynamics on the Alaskan Outer Continental Shelf. Final report prepared for Outer Conti- nental Shelf Environmental Assessment Pro- gram. Institute of Marine Science, University of Alaska, Fairbanks, AK. 33 pp. Sive, M.R., editor 1976 Environmental Legislation: A Sourcebook. Praeger, New York, NY. 561 pp. Snook, J.R. 1982 Petrology and petrography of the Quartz Hill molybdenite deposit. In: Marine Tailings Dis- posal. D.V. Ellis, editor. Ann Arbor Science Pub- lications, Ann Arbor, MI. pp. 279-290. Straight, L. 1980 Sea-salmon and trout: the best use of the ana- dromous salmon ids. In: Allocation of Fishery Resources. Proceedings of the Technical Consultation on Allocation of Fishery Resources Held in Vichy, France, 20-23 April 1980. J.H. Grover, editor. FAO and American Fishery Society, pp. 403-410. Sykes, L.R., J.B. Kisslinger, L. House, J.N. Davies, and K.H. Jacob 1980 Rupture zones of great earthquakes in the Alas- ka-Aleutian Arc, 1784 to 1980. Science 210:1343-1345. Teal, J.M. and R.W. Howarth 1984 Oil spill studies: a review of ecological effects. Environmental Management 8:27-44. Trumble, R.J. 1973 Distribution, relative abundance, and general biology of selected underutilized fishery resources of the eastern North Pacific Ocean. M.S. Thesis, University of Washington, Seattle, WA. 178 pp. U.S. Department of Agriculture (USD A) 1983 Final Environmental Impact Statement, Greens Creek, Admiralty Island, Alaska. U.S. Department of Agriculture Forest Service, Alaska Region Administration Document No. 115. Paginated by section. Warren, L.J. 1981 Contamination of sediments by lead, zinc and cadmium: a review. Environmental Pollution 2:401-436. Weeden, R.B. 1984 Environmental issues. In: Alaska Resource Devel- opment: Issues of the 1980s. T.A. Morehouse, edi- tor. Institute of Social and Economic Research, University of Alaska. Westview Press, Boulder, CO. pp. 135-168. WieseJ.D. 1984 Gulf of Alaska summary report update, May 1984: Outer Continental Shelf oil and gas activities in the Gulf of Alaska and their onshore impacts. Report prepared for the Min- erals Management Service. Rogers, Golden and Halpern, Reston, VA. 27 pp . Environmental Issues 595 Wiley,J. 1984 The sixty-minute season. Alaska Magazine 50(6):46-47. Wise, J.L.. A.L. Comiskey, and R. Becker, Jr. 1981 Storm surge climatology and forecasting in Alaska. Arctic Environmental Information and Data Center, University of Alaska, Anchorage, AK. Paginated by section. Wolfe, D.A. 1985 Fossil fuels: transportation and marine pollu- tion. In: Wastes in the Ocean, Vol. 4: Energy Wastes in the Ocean. I.W. Duedall, D.R. Kester, and P.K. Park, editors. John Wiley & Sons, Inc., New York, NY. pp. 45-93. Management Needs of Scientific Data 20 M. Jawed Hameedi Office of Oceanography and Marine Assessment National Oceanic and Atmospheric Administration Anchorage, Alaska Abstract The United States government has played a key role in sponsoring research in the Gulf of Alaska, particularly since the passage of the National Environmental Policy Act in 1970. Much of this research was focused on environmental issues pertaining to offshore oil and gas development. The scientific data pertaining to management needs are described for three broad subject areas: 1) environmental hazards, 2) pollut- ant transport, and 3) biological production and resources. Present information is adequate to identify both the areas and the phenomena that are hazardous to industrial structures and operations, to calculate oil-spill trajecto- ries and weathering states, to identify those shoreline segments that have the potential to retain spilled oil, and to describe important marine bird, mammal, and fish hab- itats. Six critical coastal habitats are described in the chapter. Data are inadequate to compare the biological productivity of different parts of the Gulf. Data are also insufficient to describe regional ecosystems or to undertake a holis- tic approach to marine environmental assessment. Newly acquired data have progressively improved both the environmental descrip- tions and the analyses in those environmental impact statements prepared during the period from 1975 to 1984 for oil and gas lease sales in northern and western parts of the Gulf, in Cook Inlet, and in Shelikof Strait. These data may have been instrumental in several resource management decisions. The observations in the existing data base are not uniform in their comprehen- siveness for different parts of the Gulf. There is the least amount of data available for southeastern Alaska. Introduction From the exploratory surveys aboard the United States fisheries vessel Albatross in the 1890s to the current fisheries oceanographv study in Shelikof Strait under the spon- sorship of the National Oceanic and Atmospheric Admin- istration, the United States government has played a domi- nant role in sponsoring research in the Gulf of Alaska. Much of the research has focused — and continues to focus — on resource management. In this context, the government's role can be broadly divided into four categories: 1) to con- serve, 2) to predict, 3) to mitigate, and 4) to compensate. The years 1969 and 1970 are the most significant milestones in the government's involvement in research pertaining to national policy and priorities. These two years marked the institutionalization of commitments bv the gov- ernment to improve the quality of public decision-making by means of a more integrated, interdisciplinary use of sci- entific information and methods. The National Environ- mental Policy Act (NEPA) of 1969 (P.L. 91-190, 83 Stat. 852, January 1, 1970) declared a national environmental policy and committed all government agencies to using a system- atic and interdisciplinary approach that would ensure that both natural and social sciences, as well as engineering design criteria, be used in any decision-making process that might lead to an impact on man's environment. In 1970. the Council on Environmental Quality (CEQJ was established by statute, and the Environmental Protection Agency (EPA) and the National Oceanic and Atmospheric Administration (NOAA) were established by Executive Reorganization Plans 3 and 4, respectively. These actions further expanded the government's role in relevant scientific research and the use of scientific data in the decision-making process. 597 598 Issues and Perspectives The significance of the period 1969 to 1970 and of the stat- utory and administrative framework it provided became clearly evident in 1974. On January 23, 1974, President Nixon directed a three-fold expansion of the Department of Interior's outer continental shelf (OCS) oil and gas devel- opment efforts. The continental shelf from Dry Bay to Mon- tague Bay (beyond the 3-mile State jurisdiction) was the first Alaskan area to be included in the OCS oil and gas leasing schedule. The CEQ, at the request of the President, under- took a study of the potential environmental risks and out- lined a number of factors (stated below) relating to oil and gas development in the Gulf: • There is a high probability that oil spills will come ashore from a number of hypothetical production locations. • There will be slow weathering of crude oil in this region due to temperature and sunlight conditions. • There is a high degree of importance attached to biota, particularly bird nesting and fish spawning areas. • There are frequent storms in the area. • There is a potential hazard to industrial installations and facilities from earthquakes and tsunamis. The council stated that there was little or no scientific infor- mation available to properly evaluate these factors. Following the CEQ's study and recommendations, the Bureau of Land Management (the bureau within the Department of the Interior that was responsible for oil and gas leasing at that time) requested NOAA to conduct an environmental study and assessment program in the Gulf. The program was established in 1974 by an interagency agreement between BLM and NOAA. It initially responded to the specific needs, goals, and objectives of BLM in the OCS leasing decisions. In 1975, it was expanded to include research in nine Alaskan OCS areas as well as non-area- specific (generic) studies. This program, known as the Outer Continental Shelf Environmental Assessment Program (OCSEAP), became the largest marine environmental research program ever undertaken. It emphasized both the acquisition and the analysis of data as part of the assessment of those environmental factors identified by CEQ. OCSEAP-sponsored research — particularly the research conducted during the period from 1974 through 1980 — is largely responsible for increasing our current scientific knowledge of both the physical environment and the biolog- ical resources of the Gulf. Other agencies such as the United States Geological Survey, the United States Fish and Wild- life Service, the National Marine Fisheries Service (and other elements of NOAA), and the State of Alaska have also contributed significantly to this knowledge. Other comprehensive and multidisciplinary environ- mental studies have also been conducted in the Gulf (on a much smaller spatial scale) in order to fulfill NEPA require- ments and to obtain mandated scientific information for both State and federal regulatory agencies. Two of these more prominent studies were 1) an evaluation of the possi- ble effects that wastewater discharge from a ballast-water treatment plant would have on the biological resources of Port Valdez (located in Prince William Sound) (Hood, Shiels, and Kelley 1973; Colonell 1980); and 2) an investiga- tion of how mill tailings and other waste products from a proposed molybdenum mine near Boca de Quadra fjord (southeastern Alaska) would affect the environment in the fjord if those wastes were discharged into the water (Ellis 1982). The significance that the scientific data base holds in allowing informed and rational resource management deci- sions to be made or in facilitating selection of a particular engineering design is illustrated in Figure 20-1. Certain for- malized concepts of pollution control strategies (Freeman, Haverman and Kneese 1973) and risk-benefit analyses (Whyte and Burton 1980) are implicit in this figure, devel- oped by Dr. Rudolf J. Engelmann, Director of OCSEAP from 1975 to 1979. The figure was described as an 'Engelmann Curve' by Dr. T. Neil Davis in a Fairbanks news- paper {Fairbanks Daily News-Miner, May 26, 1979). Because the figure actually consists of two separate curves, it will be referred to as the 'Engelmann Diagram' in this chapter to avoid any semantic confusion. According to Figure 20-1, if no consideration is given to 1) the sustainable exploitation level of a resource, 2) the accommodative capacity of a natural body of water, or 3) the safety provisions in an engineering design (each of the three requiring scientific data and their interpretation), then the project is likely to fail — resulting in economic loss (Point 1). A much greater loss to society would occur if the project failure also results in other damages such as the loss of a resource, irreparable damage to the environment, or loss of human life (Point 2). The cost of a project with its own desired safety provi- sions (and minimum expenditure) is shown at Point A. But societies demand greater than the minimum safety margin and a higher safety margin brings a higher cost (Point B). Neither the project nor the society benefits if the safety and Margin of Safety or abatement of Environmental Hazards Figure 20-1. Engelmann Diagram showing the generalized rela- tionships between the costs and the margins of safety in a given project. Management Needs of Scientific Data 599 abatement considerations are far lower than Point A or far higher than Point B. Our society has remained willing to pay for the additional safety margin that lies between points A and B in Figure 20-1. These margins currently take the shape of emission controls for automobiles or factories, traf- fic diversions away from bird nesting colonies or mammal rookeries, or the curtailment of industrial operations in order to reduce the disturbance of a valued species. There are a number of techniques one can use to inter- pret and evaluate scientific data when making resource management decisions. These techniques range from the relatively simple, subjective, and qualitative interaction matrices, such as the Leopold matrix (Leopold, Clarke, Hanshaw, and Balsley 1971), to more objective and complex numerical analvses, such as simulation modeling (Holling 1978). Simulation modeling relies on precise identification of relevant variables and their interrelationships. It is a power- ful and readily adaptable technique which can be used both to mimic natural systems and to compare alternate manage- ment schemes (Holling 1978). The principal disadvantage of simulation modeling is that its results do not reflect the ade- quacy of assumptions that go into the calculations and can only be as good as the input data. There is also danger that results of simulation modeling may be too readily believed by the decision maker. Although there are ample techniques one can use to eval- uate scientific data, and there are clear guidelines for mak- ing a management decision (Holling 1978; Wolfe, in press), it is usually not obvious that scientific data are adequately used as part of the management decision process. This is because most management decisions are not made on the basis of scientific considerations alone; certain economic criteria, the prevailing socio-political environment, and prevalent institutional tendencies also play a significant role. Furthermore, if scientific analysis is not included as an integral part of the decision-making process from the beginning, the evaluation of scientific data will not play a prominent role in the decision (Holling 1978). Under cir- cumstances where scientific study is an afterthought, research and evaluative studies are likely to be either too broad and unfocused to respond to future information requirements, or too narrowly focused on those aspects of the program that are easily quantifiable (Lowry 1980). This chapter describes both those scientific data and models that play a role in the previously stated management concerns. Most of these concerns are focused on environ- mental issues and resource-use conflicts discussed in the previous chapter (Jarvela, Ch. 19, this volume). The text is organized into three areas for which data are available: 1) environmental hazards, 2) pollutant transport, and 3) bio- logical production and resources. No attempt is made to judge either the extent or effective- ness of use of scientific data in management decisions. In recent years, such decisions in the Gulf have included: • selecting the site for the ballast-water treatment plant • selecting and excluding tracts for petroleum development • allocating fisheries resources • designating critical biological habitats • governing vessel traffic near marine bird and mammal habitats. For those interested, there is a case study of Port Valdez in which scientific data were used both to allow for and to monitor wastewater discharge (Shaw and Hameedi, in press). Environmental Hazards Coastal facilities, bottom-founded structures, and sub- bottom installations in the Gulf of Alaska are at risk due to the geologic setting. Surface vessels in the Gulf are subject to frequent storms and high waves. Extremes in meteorologic and oceanographic conditions and other environmental factors pose risks to human life, construction vessels (pipelayers, dredges), support vessels, and industrial installations. A number of environmental factors must be considered before a decision to install a bottom-founded or sub- bottom facility can be made. In the case of petroleum pro- duction platforms, such factors may include: • water depth • tides and currents • storm-wind velocities • storm-wave heights • tsunamis and seiches • ground acceleration due to earthquakes • instability of sea floor sediments • impact load caused by sea ice that impinges upon the structure. Site-specific data are required in order to characterize a particular location as being suitable for the development and operation of an offshore installation. There is also a need for reliable data with broader spatial resolution to facilitate evaluation of the hazards that the environment poses to any structure. Such broader-scope data provide an essential framework with which to evaluate site-specific information and help guide safe and orderly industrial development. The offshore petroleum industry is probably the only industry likely to commit vast resources to the design and the placement of structures on or below the sea bottom. There are petroleum production platforms in Cook Inlet, off the California coast, and off Japan that have been exposed to numerous earthquakes. According to Dunn (1982), the design criteria for Cook Inlet petroleum plat- forms have included deck loading (8- to 10 x 103 mt), wave height (12-15 m), ground acceleration (0.2 gr), and ice load- ing (1 m). The industry experience and data base in this field are growing, but more extensive and longer-term data are needed because some environmental parameters must be described in statistical terms (Dunn 1982). Seismic Hazards Jacob (Ch. 6, this volume) has described the seismotec- tonic setting of the Gulf of Alaska. The high level of tectonic 600 Issues and Perspectives activity, coupled with the expectation of a large earthquake within the next two to three decades, presents a substantial hazard to human life and property. Three of the ten largest earthquakes in the world since 1904 have occurred in the Gulf of Alaska/Aleutian region. The Great Alaskan Earth- quake of 1964 was perhaps the most significant event in terms of its magnitude and the extent of damage it caused. The Shumagin and Yakataga seismic gap areas are identi- fied as the most likely sites for the next great earthquakes in the Gulf (Savage, Lisowski, and Prescott 1986). A number of tectonic models have been developed to describe the seismotectonic framework for the Gulf. These models are based on an evaluation of historic earthquake records, the regional geology, and an analysis of data obtained from both regional and worldwide seismograph networks. The synthesis of data in the form of a seismic- exposure analysis is an important and useful step in assess- ing environmental hazards. Woodward-Clyde Consultants (1982a, b) modified existing software and applied it to seis- mic-exposure analysis and mapping for the Gulf of Alaska region. The modification was made in order to account for seismic gaps, to use newly acquired data on ground-motion attenuation, and to establish initial seismicity conditions and source geometries that would be consistent with recent observations. A schematic representation of the seismic- exposure model is shown in Figure 20-2. The results of the Woodward-Clyde study can be used to obtain single-point values of seismic exposure at a given site. They can also be used in combination with a grid of sites to create seismic exposure maps. Six such maps have been produced. These maps show the probabilities of exceedence (at the 33% level) for typical ground-motion parameters such as maximum horizontal acceleration. The exceedence probabilities were calculated for the 1981 to 2021 period. Maximum ground-acceleration contours that showed high values in seismic gap areas are presented by Jacob (Ch. 6, this volume: Figs. 6-31 and 6-32). Seismic-exposure maps are very useful to resource man- agers for tasks such as establishing seismic zones and creat- ing design guidelines. Offshore industries' personnel use the maps for planning site-specific studies and for deter- mining engineering design specifications. Researchers also use the seismic-exposure maps for evaluating the reliability of input data and model parameters. The use of these maps is currently limited by: 1) the lack of integration of the seis- micity records from great earthquakes in the analysis, 2) the lack of any recent redefinition of seismic-gap zones, and 3) the need for substantive additional data on ground-motion attenuation and scaling factors that can be applied to the Gulf (Jacob and Hauksson 1983). Volcanic Hazards Another manifestation of the tectonic setting of the Gulf and, in particular, of the subduction of the Pacific Plate under the North American Plate, is the nearly forty vol- canoes both on the Alaska Peninsula and in the Aleutian Islands. A number of these volcanoes have erupted during this century (e.g., Katmai-Novarupta in 1912, and Mount Augustine in 1883, 1963-1964, and 1976) (Kienle and Shaw 1979) — Mount Augustine also erupted again in 1986. The following phenomena that are commonly associated with volcanic eruptions pose substantial hazards: 1) violent explosive eruptions, directed blasts, volcanic bombs, glowing avalanches and nuees ardentes, heavy debris falls, and tectonically induced sea waves 2) hazardous atmospheric phenomena, including tur- bulent ash clouds, noxious gas clouds, and corrosive rains 3) pyroclastic flows, lava flows, mud falls, and flash floods in river valleys. Inputs Analysis Results Source Seismicity Model Location and Source Geometr Recurrence Magnitude Range Exposure Analysis Model: Obtain cumulative distribution function based on contribution of all sources Seismic Exposure Map Attenuation Model \ ^ >■ Site Conditions X Transmission Path Conditions a Magnitude and Distance / IE Exposure Evaluation Criteria Repeat For All Sites Period of Interest Probability of Exceedance Probabilities For Sensitivity Analysis Figure 20-2. Schematic diagram of the elements of a seismic-hazard evaluation, as implemented in a seismic-exposure software package by Woodward-Clyde Consultants (1982a). Management Needs of Scientific Data 601 At present, the area of highest risk to human life and prop- erty as a result of falling volcanic bombs, pyrociastic flows, and tephra accumulation in the Gulf has heen (and is likely to he) restricted to the immediate vicinity of St. Augustine Island. The volcanic gas plumes and ash from the 1986 erup- tion spread northward and eastward to a much larger area. This was predicted hy Kienle and Swanson (1980). In comparison with seismic hazard studies, research on volcanic hazards has not heen extensive; however, events that have led to major volcanic eruptions and the areal extent of damage from those eruptions are well docu- mented (Kienle and Shaw 1979; Kienle and Swanson 1980; and McNutt 1983). The geophysical precursors to the erup- tions of Mount Augustine volcano have been described by Kienle and Swanson (1980), and seismicity appears to be the most reliable predictive sign. These authors also produced a volcanic hazard map in the event of future eruptions (such as that in 1986) of the volcano. Four hazard zones were delineated, from very high to very low hazard areas. Offshore oil and gas lease sale blocks in Cook Inlet were located outside the high hazard zone in which there could be potential loss of life and property from pyrociastic flows as well as from volcanic gases and tephra accumulations (Fig. 20-3). The low hazard zone — an area in which there was only low ash accumulation — extended about 1,000 km eastward to Sitka and 400 km northward to Talkeetna. The areal extent of this zone was determined by the prevailing high-latitude westerly winds. After the 1986 eruption, actual ash-fall patterns were found to be precisely as pre- dicted. McNutt (1983) also produced maps of potential ash accumulation from 'once-per-hundred-year eruption' probability data for major volcanoes located on the Alaska Peninsula. Sediment Instability and Erosion Hampton, Carlson, Lee, and Feely (Ch. 5, this volume) have described both the distribution and the properties of sea-floor sediments as well as having delineated areas where there are potential instabilities on the sea floor. Two of the most striking and well-studied sediment-slump and sedi- ment-slide areas are located on the northern portion of Kayak Trough and in the area seaward of Icy Bay. The sedi- ment slide near Kayak Trough covers an area of over 250 km- and has a volume of nearly 6 km'5 (Molnia, Carlson, and Bruns 1977). This slide could have been triggered recently by an earthquake. A sediment slide near Icy Bay that covers an area 90 km long and 10 to 20 km wide is also believed to have occurred recently. It could have been caused by rapid sedi- ment accumulation combined with an increase in the slope angle (Carlson 1978). Sediment sliding is not known to occur in the western Gulf of Alaska, although the shallow troughs that intersect the shelf off Kodiak Island have slopes that should be con- ducive to slides (Hampton etal, Ch. 5, this volume: Fig. 5-4). Sediment distribution data and the high-resolution maps produced by the United States Geological Survey were very useful in selecting lease tracts in the northeastern Gulf (U.S. Department of the Interior 1980). Sediment sliding or slumping is not considered a hazard in Cook Inlet. Rather, potential bedform movement such as the sand waves or sand ripples that result from tidal currents or storm waves may pose hazards to bottom-founded installations. Under present hydraulic conditions in Cook Inlet, large sand waves — some of which are 5 to 10 m high and 500 to 1,000 in long — are believed to move very slowly, perhaps only tens of centimeters per year (Hampton et al., Ch. 5, this volume). The superimposition of bedforms of dif- ferent sizes and their respective orientations suggest that the time scale for different bedform movements may vary widely — from daily to episodic or even geologic. Such move- ments should be evaluated before installing bottom- founded or sub-bottom structures such as drilling plat- forms or pipelines. A large portion of the sediment that is brought into Cook Inlet by rivers remains suspended due to strong tidal mixing and is subsequently transported out of the Inlet. The most important of the river systems that empty into Cook Inlet in terms of sediment load is the Susitna/Knik/Matanuska sys- tem. Depending upon the sediment grain characteristics and the prevailing current regime, sediment leaving the Inlet may be deposited in Shelikof Strait or in the region of the Kennedy and Stevenson Entrances. Sediment accumula- tion within Cook Inlet occurs only in protected, semi- enclosed embayments such as Tuxedni, Chinitna, Kachemak, and Kamishak Bays. The high concentration of suspended sediment in water, coupled with strong currents that exceed 300 cm/s in certain locations, has the potential to be highly abrasive and could damage protective coatings. However, such hazards are relatively unimportant, even though they could be expensive to counteract. Oceanographic Hazards High winds, large waves, and accumulating or drifting sea ice all pose hazards to facilities and their operations. It is usually not the normal events that cause concern, but rather the extreme events that may cause loss of life and damage to property. Brower, Searby, Wise, Diaz, and Prechtel (1977) calcu- lated values for maximum sustained winds, maximum sig- nificant wave heights, and extreme wave heights for six seg- ments of the Gulf ranging from southeast Alaska to Unimak Pass. The oceanic area south of the Kodiak Archipelago is expected to have stronger winds and higher waves than the other areas. Winds approaching 47.6 m/s (87 kt), waves with maximum significant heights of 17 m, and extreme waves over 30 m high can have 25-y cycles over most of the Gulf. The 100-y or 'engineering design' events are a 54.7 m/s (100 kt) wind, a maximum significant wave height of 22 m, and an extreme wave height of 39 meters. This implies that the probability in any given year for a 54.7 m/s (100 kt) wind or an extreme wave height of 39 m is one percent. Sea ice occurs in Prince William Sound, Cook Inlet, along smaller stretches of coastline south of the Alaska Peninsula, and in Shelikof Strait. Shallow embayments and coves may be seasonally covered with ice, although in most areas ice formation and break-up occur several times during the winter. Small segments of ice broken off glaciers (called 'bergy bits') have been found floating several kilometers from their origin. Except for small craft, they rarely pose any danger to marine transportation and shipping. 602 Issues and Perspectives Area of very high risk to human life and property asso- ciated with falling volcanic bombs, pyroclastic flows, volcanic gases, thick tephra accumulation and mudflows (on or nearshore only). Area of high risk to human life and property caused by pyroclastic flows, volcanic gases and tephra accumulation. (Extent uncertain in striped area.) Area of low risk to human life and moderate risk to property caused by volcanic gases and tephra ace umulation. Area of no risk to human life and low risk to property caused by volcanic gases and tephra accumulation. I I Area of no risk to human life or property. .J Extent of 1976 pyroclastic flows. Extent of offshore pyroclastic deposits based on bathymetry. Extent of volcanic bomb fall for 1976 eruption. (Fragments >15cm diameter.) H Offshore lease blocks. a Volcanoes. Figure 20-3. Regions of volcanic hazard from both current and future eruptions of Augustine volcano. Planned oil and gas lease sale tracts are also shown. (Modified from Kienle and Swanson 1980.) Management Needs of Scientific Data 603 Nearly 200 vessel-icing incidents were recorded dining the period of 1979 through 1984 in the Gulf, most of them occurring in the western part (Pease and Comiskey 1985). Ice accretion can increase a vessel's weight, elevate its center of gravity, or decrease its metacentric height, causing it to lose balance, capsize, and eventually sink. Structural icing may be a more serious hazard to vessels operating in the Gulf than was previously thought. Nomograms that are used to calculate icing rates under different air-temperature, wind- speed, and seawater-temperature conditions have been recentlv revised (Pease and Comiskey 1985; see also Wilson and Overland, Ch. 2, this volume). Pollutant Transport The ability to describe both the mechanisms and the processes that govern the transport of water-borne pollu- tants is critical to predicting the consequences of oil spills or waste discharges. Predicting pollutant trajectories and map- ping exposure fields can only be done reliably if the scien- tific data regarding currents and meteorological conditions are reliable. Any conceptual or numerical model that describes contaminant transport in the marine environ- ment should be able to describe both the amount and the weathering state of a pollutant on the sea surface, in the water column, and on the sea bed — both along and at the end of its trajectory or plume. Such models should also provide: • data that can help minimize the risk to environmen- tally sensitive areas • information on probable trajectories and landfalls in the event that pollutants are accidentally released • information that can be used during pollutant con- tainment and clean-up operations both in coastal and in nearshore areas. Basic data for such models may be acquired from sources such as: • literature summaries • hvdrographic data • current-meter and pressure-gauge records • drift-buoy trajectories • satellite and other remotely sensed imagery • local and regional wind fields • pollutant weathering or removal rates. Advective and Dispersive Regimes Wilson and Overland (Ch. 2, this volume), and Reed and Schumacher (Ch. 3, this volume) have reviewed data from a large number of studies on meteorology and phvsical oceanography, respectively. Major features of the Gulf of Alaska circulation are shown in Reed and Schumacher's Fig- ure 3-1. It is now possible to make general statements on the advective and mixing processes that are likely to be respon- sible for shaping pollutant trajectories or plumes. A comparison of the relative magnitudes of the kinetic energy components (mean flow and its fluctuations) shows that currents seaward of the continental shelf (dominated by the Alaska Current and Alaskan Stream) are characterized by a strong mean flow and moderate-to-weak high- frequency fluctuations. This implies that there would be a rapid transport of pollutants in the direction of the mean flow. On the other hand, currents on the continental shelf are characterized by a weak mean flow (as much as an order of magnitude lower than those off the shelf), but they have a high-energy tidal component. This means that pollutants are likely to remain on the shelf for a longer period of time, but their concentration will be more rapidly reduced by strong tidal mixing. Off the Kodiak Archipelago — where shallow banks are separated by deep troughs — tidal variance in currents over the banks is higher than the variance in the troughs (Reed and Schumacher, Ch. 3, this volume). The fact that high- salinity water occurs in the Kodiak Archipelago troughs (val- ues >33"/oo have been observed in Kiliuda Trough) strongly suggests that the source of this water is the shelf-edge por- tion of the Alaskan Stream. Current-meter records show flow events that might transport shelf-edge waters (and associated pollutants) shoreward into Kiliuda Trough. The influence of the Alaskan Stream on circulation in these troughs is demonstrated by a shoreward flow on the upstream side and seaward flow on the downstream side (Lagerloef 1983). Pollutants released on the outer shelf could impinge upon shorelines and bays, particularly those that lie at the head of troughs. The mechanisms that are responsible for eddies, such as those located west of Kayak Island, off Sitka, and off Van- couver Island, are potentially significant to pollutant reten- tion and transport. Except for the eddy off Vancouver Island (which is frequently initiated by local alongshore winds), such mechanisms have not been studied in detail (Thomson and Gower 1985). Pollutant transport, particularly spilled-oil trajectories, is greatly influenced by both prevalent wind conditions and episodic meteorologic events. Oil spilled on the North Albatross Bank would be pushed offshore into the Alaskan Stream by strong southwesterly winds and then advected out of the area. However, if the winds were strong and north- easterly, spilled oil would be advected into Chiniak Bay. A review of offshore-wind records shows that either of these winds — as well as other winds — can occur in the Kodiak region during any given period (Brower et al. 1977). Along the coast, pollutants would be transported by the coastal current (known as the Kenai Current off the Kenai Peninsula) in a counterclockwise direction at different speeds, but would be contained within a narrow band. The current speed off Kenai Peninsula varies between 20 and 100 cm/s. Local bathvmetrv and topographic features will modify this transport pattern, causing oil to smear long stretches of coastline and causing oil and other pollutants to be retained in eddies and deposited in bavs. 604 Issues and Perspectives (look Inlet's water circulation is dominated by strong tidal currents, and its winds are modified by both the local orography and the Inlet's configuration (Greisman 1985). Water from the Gulf of Alaska flows into the Inlet through Kennedy Entrance. This water — which is characterized by low turbidity, high salinity, and a high concentration of inorganic plant nutrients — flows north along the eastern side of the Inlet. Its northward extent varies with the seasons and is largely determined by the degree to which it mixes with the southward-flowing, turbid, low salinity water from upper Cook Inlet. During fall, when outflow from the upper Inlet is reduced, the Gulf water can still be identified as far north as the Forelands. The southerly flowing water along the west side of the Inlet is readily recognized by its heavy suspended-sediment load, with high suspended-sediment concentrations occurring in Tuxedni Bay, the Forelands, and upper Cook Inlet. Within Shelikof Strait, the outflowing Cook Inlet water mixes with Gulf water that is flowing through Kennedy Entrance. This mixing creates a complex hydrographic structure that includes strong surface-temperature and sus- pended-particulate gradients. The flow through Shelikof Strait is predominantly southerly. Winds are greatly influ- enced both by the coastal mountain range and by the gaps between the coastal mountains. Two fjords have been extensively studied: Port Valdez in Prince William Sound, and Smeaton Bay in Southeast Alaska. Water circulation in Port Valdez is typically that of a positive estuary: brackish water flows seaward in the surface layers and saline water flows landward at depth. Current speeds range between 20 and 25 cm/s with a mean, non- tidal component of about 2 to 3 cm/s (Muench and Nebert 1973). Nebert (1982) suggested that the circulation in Smeaton Bay might be opposite that found in typical positive estuary. Thus, materials added in upper waters would be mixed downward into the outward-flowing layer. Such a pattern may be advantageous for dumping marine tailings at depth since it would be less likely that turbidity would be carried into the upper, biologically productive layers. However, field data in support of the suggested cir- culation scheme in Smeaton Bay are few and not conclusive. More research, including numerical modeling of circula- tion, is in progress. Both regional ocean-circulation data and meteorology data are used extensively to describe the environments that would be affected by OCS oil and gas development. These data are also used to calculate hypothetical oil-spill trajecto- ries and assess environmental risks associated with the development. This information is contained in several environmental impact statements for leases in areas of the northern Gulf of Alaska, in lower Cook Inlet, and in the Kodiak region. Site-specific data, including dispersion esti- mates, were obtained in Port Valdez. These data were used to delineate the type of mixing zone that would be required to achieve a sufficient oil and grease dilution for the effluent that would be discharged from a ballast-water treatment plant (Colonell 1980; Hood, Shiels, and Kelley 1973). Other studies are gathering field data and formulating dispersion models for Port Valdez, Smeaton Bay, and Boca de Quadra to predict mine-tailing plumes and their associated pollut- ant discharges. Numerical Modeling Numerical modeling of the ocean circulation in the Gulf has been conducted for a number of purposes, including: • to diagnose the Gulfs salient features (Gait, Overland, Smyth, Han, and Pease 1977; Gait and Watabayashi 1980) • to simulate tidal heights and the associated currents (Mungall 1973; Harding 1976) • to calculate hypothetical oil-spill trajectories for use in environmental impact analyses and assessments (Schlueter and Rauw 1981). Each of the numerical modeling studies varies markedly in terms of the areas covered and the primary focus. The oil-spill trajectory model is a series of algorithms that use data on regional winds, currents, geography, and bathyme- try. The model then predicts the movement of a floating oil mass and presents the results in both digital and graphic for- mats. Many terms and coefficients in each algorithm require either actual time-series observations or a statistically gen- erated data set for the oil-spill trajectory simulation period. Most of the resource assessment reports and environ- mental impact statements for OCS leases in the Gulf of Alaska were prepared before 1984. Although capability exists to do so now, the earlier documents did not include data on petroleum-hydrocarbon dispersion and weather- ing in either the oil-spill trajectory calculations or the oil-spill risk assessments. The environmental impact state- ments include the probabilities that spilled oil would reach a certain shoreline segment or biologically important area — probabilities that are based solely on meteorologic and oceanographic data. In addition, they provide com- bined probabilities that spilled oil would contact either the shore or other biologically important areas at some point during the production period of an oilfield, given the resource estimate and probable oil-spill rate (U.S. Depart- ment of the Interior 1984). For OCS leases in the Bering Sea, Liu and Leendertse (1985) provide a more comprehensive accounting of those factors that determine oil-spill trajecto- ries, factors that include sea-ice cover, stochastically gener- ated wind fields, dispersion, and weathering. The oil trajec- tory and weathering models, including a trajectory model developed by NOAA to support federal response to marine spills of hazardous substances (Torgrimson 1984), were suc- cessfully applied to both the movements and the weathering state of 750 m3 of JP-5 jet fuel that spilled from the M/V Cepheus near Anchorage in January 1984. In those instances where numerical modeling was intended to serve a diagnostic purpose, it has been possible to simulate major circulation features for both the continen- tal shelf and the slope that agree with observations. It has also been possible to identify regional responses that are associated with different forcing mechanisms such as den- sity- or wind-driven circulation. The diagnostic model shows that the coherence-length for currents — which is Management Needs of Scientific Data 605 controlled by the conservation of potential vorticity along isobaths — is typically ~30 km over the shelf and ~300 km over the slope (Gait el al. 1977; Gait and Watabayashi 1980). Spilled Oil Retention Potential The coastline extending from Cross Sound to the south- ern extent of the Kodiak Archipelago has been surveyed to characterize and classify its segments in terms of their oil-spill retention potential and their habitat vulnerability. Vulnerability indices (usually ten) have been developed based on a number of factors that include: • beach morphology • sediment grain-size distribution • prevailing wave patterns • inferred alongshore transport • major biotic assemblages. According to this classification, about 23% (or 410 km) of the shoreline between Dry Bay and Hinchinbrook Entrance has the potential to retain spilled oil for more than ten years (Ruby 1977). It is noteworthy that vulnerable segments of the coastline, such as the Copper River Delta, include some very impor- tant biological habitats. In contrast, only about 2% (or 110 km) of the Kodiak Archipelago is classified as having a potential to retain spilled oil for ten years or longer (Hayes and Rubv 1979). Sand and gravel beaches — comprising 70% of the Archipelago shoreline — may allow deep burial of spilled oil. These beaches were classified as having moder- ate risk for spilled— oil retention (vulnerability index between 6 and 8). This coastline mapping has been useful to various agencies in their evaluation of coastal development projects, their preparation of coastal management plans, and their preparation of contingency plans for oil-spill cleanup operations. Oil Weathering Scientists have completed a major crude-oil weathering study that culminated as a computer model (Payne, Kirstein, McNabb, Lambach, Redding, Jordan, Baxter, and Gaegel 1984). During the study, they used kinematic and ther- modynamic data on crude oils extracted from the literature, then they obtained new data from a series of experiments they conducted in test chambers, flow-through aquaria, and wave tanks. These experiments simulated conditions typical of the Gulf of Alaska. Many experiments were conducted at the Kasitsna Bay Laboratory, located near Seldovia in Cook Inlet. The weathering study provided data on a number of processes, including: • evaporation/dissolution • surface slick formation • oil-droplet dispersion • dispersed and dissolved oil adsorption on suspended particulate matter • water-in-oil emulsion (mousse) formation • microbial degradation. The oil-weathering model takes into account the oil's composition in terms of its boiling-point/distillation-cut data. The model focuses on those major oil-weathering processes that determine the mass balance of any spilled oil. Microbial degradation is not considered because of its low significance in affecting the mass balance. The sedimenta- tion of oil is also not included as part of the model. Both the nature and the amount of oil that is transported to the sea bottom depend greatly on 1) the oil's composition, 2) the sediment's affinity to accumulate oil, and 3) physical factors such as water depth, tidal mixing, and wave-induced turbulence. In the open waters, transportation of oil to the sea bottom is likely to be widely spread and may not result in high concentrations. Biological Production and Resources The Gulf of Alaska's continental shelf and overlying waters are highly productive, sustaining an abundance of flora and fauna. The living marine resources are (and have been for centuries) of central importance to both the exis- tence and the way of life of the people in this region. For decades, salmon, crab, shrimp, halibut, clams, and scallops have been exploited either commercially or for subsistence and sport fishing. Until recently, commercial exploitation of marine mammals was common. The importance of com- mercial fishing to the regional economy is underscored by the annual value of the catch, which was estimated at $350 million in 1984. There is currently no commercial harvest of marine mammals or birds, although subsistence use may occur in some areas. The shelf is heavily used as a feeding area in the spring and summer by birds such as the black-legged kittiwake, the tufted puffin, and others. Winter residents such as the mal- lard, the oldsquaw, and the Steller's eider, as well as tran- sient populations of short-tailed and sooty shearwaters, also feed in the shelf waters. Shearwaters dominate the spring/ summer pelagic bird community, constituting about 84% of the numbers and 83% of the biomass (DeGange and Sanger, Ch. 16, this volume). Both the deltaic and intertidal areas are heavily used by migrating birds. Nearly 10 million birds — consisting largely of western sandpiper and dunlin — feed on the rich biota of the Copper River Delta for a short period each year. Marine mammals both feed and breed throughout the region (Calkins, Ch. 17, this volume). Steller sea lions, harbor seals, and sea otters are common and probablv dominate ecologically. Several species of cetaceans, including some listed as endangered species, migrate through and feed on the shelf or offshore. Dall's porpoises and humpback whales may also use the shelf area for calving. The sustenance and the growth of these large and varied animal populations require not only large quantities of food but also effective mechanisms for partitioning the resources in both the pelagic and the benthic environments. Because greater emphasis has been placed on research on marine birds, mammals, and fisheries in the Gulf, data on lowei trophic levels — particularly plankton — are relatively mea- ger. It is, however, possible to speculate on the basic func- 606 Issues and Perspectives tional aspects of the shelf ecosystem by considering the food habits of those species which have been studied. This infor- mation can be coupled with knowledge of the circulation and mixing regimes, and further information can be extrap- olated from data on the biological productivity of similar areas of the world. However, the lack of data precludes using community structure analysis to evaluate those ecosystem properties such as resilience and stability. Primary Productivity and Trophic Links The data on the Gulfs primary productivity are sporadic in terms of both time and space, but suggest that its seasonal cycle is typical of most subarctic marine environments. This contention is supported by phytoplankton productivity, biomass, and inorganic plant nutrient data obtained at a variety of locations, including: 1) in the open ocean at Station P (McAllister 1969), 2) over the continental shelf (Larrance, Tennant, Chester, and Ruffio 1977), 3) in fjords (Goering, Shiels, and Patton 1973; Iverson, Curl, O'Connors, Kirk, and Zakar 1974), and 4) in estuaries (Larrance and Chester 1979). This subject is treated in detail by Sambrotto and Lorenzen (Ch. 9, this volume). The effects that water-column stratification, sunlight, and nutrient levels have on primary productivity in lower Cook Inlet are reported by Larrance et al. (1977) and Lar- rance and Chester (1979). Their observations were made at stations along a transect between Kachemak and Kamishak Bays. Maximum productivity occurred in Kachemak Bay in early May, in mid-Inlet in late May, and in Kamishak Bay in July. They reported primary productivity rates in Kachemak Bay (which receives nutrient-rich waters from the open shelf) that ranged from 1 to 8 g C/m-d during May through August. In Kamishak Bay, which is usually turbid, primary productivity rates were between 0.1 and 7 g C/m2d. Any pri- mary productivity values that exceed 5 g C/m-d are consid- ered exceptionally high. A single phytoplankton bloom cannot sustain the variety of life forms and trophic levels in the Gulf and adjoining coastal regions throughout the year. On the Kodiak Archi- pelago— as on other highly productive continental shelves that have shallow banks — primary productivity takes place in late spring and continues into the summer. Productivity increases often occur that are both of short duration and of limited spatial extent. These increases depend on the same three parameters as those governing the vernal increase in phytoplankton productivity: 1) mixing of the water column followed by stabilization, 2) an adequate supply of inorganic plant nutrients, and 3) the availability of sunlight. Such pri- mary productivity increases on the Kodiak shelf may be facilitated by vertical mixing that is induced by storms in a situation similar to that found in the eastern Bering Sea (Sambrotto, Niebauer, Goering, and Iverson 1986). The importance of frontal zones to the enhancement of both biological richness and productivity is well recognized in many areas. These features are characterized by locally intense gradients in hydrographic properties, circulation, or biological features (Bowman 1978). Frontal zones exist in Shelikof Strait, in Cook Inlet (commonly known as the 'trash line1), and off the Kodiak shelf break. The increase in phy- toplankton biomass (or of other biota) in frontal zones could result from 1) matter that accumulates due to con- vergence, 2) increased productivity when divergence occurs on one side of the front, or 3) admixing of the water masses on opposite sides of the front (Savidge 1976). Iverson, Coachman, Cooney, English, Goering, Hunt, Macauley, McRoy, Reeburgh, and Whitledge (1979) demon- strated the significance of both fronts and interfrontal zones to the pelagic trophic structure in southeastern Bering Sea. There are no published data from the Gulf of Alaska that correlate the physical dynamics of the fronts with the biolog- ical richness or the productivity of the area. Field data with horizontal resolutions of from 0.1 to 1.0 km and vertical reso- lutions of from 0.5 to 5.0 m are usually required to ade- quately hypothesize (or observe) front domains in either along-front (ca. 30-300 km) and cross-front (ca. 60-600 m) directions (Bowman 1978). The importance of frontal- dynamics research as it relates to understanding the Gulfs productivity (and taking into account productivity's spa- tial-resolution and data synopticity requirements) has not been widely acknowledged. The physical environment also exerts an influence on both the taxonomy and the size composition of the planktonic primary producers. This influence is enforced via size-selective feeding at succeeding trophic levels and it has important implications in terms of the yield available to apex predators (Landry 1977; O'Brien 1979). The predomi- nant phytoplankton size and the trophic structure of vari- ous plankton communities are fundamentally different in areas where there is either a high or a low fisheries yield. This difference is due to the trophic position offish relative to the primary production source (i.e., whether the source is diatoms or flagellates). The relatively high abundance of large phytoplankton species — particularly pelagic diatoms in nutrient-rich waters — leads to desirable food chains in terms of fisheries. Decreased nutrients and increased stratification shift the growth advantage to dinoflagellates and microflagellates, often leading to food chains that culminate in jellyfish and chaetognaths (Greve and Parsons 1977). The degree to which the water column primary produc- tion is used by herbivores (and the succeeding trophic lev- els) is important in determining the overall economy of the sea. There seem to be energetic benefits derived from pref- erential feeding on larger prey. Both the seasonal presence of large, oceanic copepods, such as Neocalanus plumchrus and Neocalanus cristatus, and the timing of their grazing cycle result in an efficient transfer of organic matter to higher trophic levels. In such cases, there is no time lag between intensive grazing pressure and phytoplankton primary pro- duction. Consequently, only relatively small amounts of organic matter are lost to the water column. The onshelf advection of oceanic water over the shelf, which is docu- mented for some areas of the Kodiak shelf (Lagerloef 1983), probably accounts for the presence of these large copepods inshore (Vogel and McMurray 1986). Smaller neritic and oceanic copepods usually predomi- nate on the shelf and in coastal areas. Such copepods (Pseudocalanus sp., Acartia sp., and Oithona spp.) breed follow- ing intensive feeding, and their brood size depends on the Management Needs of Scientific Data 607 amount of food they have consumed. Maximum grazing occurs from two to six weeks after the spring phytoplankton growth. The delay in the maximum use of the phy- toplankton results in 1) an unbalanced plankton cycle, 2) the loss of a large quantity of organic matter that falls to the bot- tom, and 3) an inefficient use of the resources in the water column. Energetic benefits to fish from preferential feeding on large prey have heen demonstrated both theoretically and experimentally (Kerr 1971; O'Brien 1979). For example, salmonid juveniles can obtain between 5 and 10 times their daily ration from large copepods compared with small copepods. They showed a 4% per day growth rate when fed on Neocalanus plumchrus which averaged 3 mg each, com- pared with no growth when fed on cyclopoids that averaged 0.1 mg each. These copepods were both available at the same concentration (LeBrasseur 1969). Large copepods are not preferred by jellyfish such as Pleurobrachia sp., which has a much higher food intake and growth rate when feeding on small copepods (Greve and Parsons 1977). Maximum abundance of planktivorous fish (mainly young salmonids) occurs in the Strait of Georgia, British Columbia, either after or in association with the maximum abundance levels of Neocalanus plumchrus. Small copepods, such as Pseudocalanus minutus, occur in summer when ctenophore and jellyfish populations are also at high levels (Parsons, LeBrasseur, and Barraclough 1970). It appears that trophic pathways leading toward jellyfish and ctenophores are favored where nutrient concentration and supply are low. In addition to copepods, amphipods and euphausiids are important and, in some cases, are the dominant food in the pelagic environment. They are consumed by Pacific salmon juveniles, herring, capelin, Atka mackerel, and Pacific sand lance juveniles, as well as by pelagic birds and marine mam- mals (see Science Applications, Inc. 1980 for a review of data for the Kodiak region). Food webs where euphausiids are the principal intermediate element may be similar to those based on large copepods. The importance of amphipods to shelf predators has only recently been recognized. Cross, Fresh, Miller, Simenstad, Steinfort, and Fegley (1978) showed that 53 out of 55 nearshore fish species preyed upon gammarid amphipods. These amphipods accounted for more than 50% of the total Index of Relative Importance (IRI) for 31 different species, and accounted for more than 75% of the IRI for 9 of those species. The relative role of a carnivorous amphipod, such as the genus Parathemisto, is not well known. Food webs leading to or including carnivorous amphipods are distinct from (but probably exist concurrently with) food webs involving large copepods. The webs may involve: 1) small phvtoplankton, 2) protozoa, small copepods, and larvae, 3) carnivorous amphi- pods, or 4) larger carnivores (Nemoto 1970). Such food webs may allow for increased food resources for animals of both commercial and aesthetic value and may counteract the for- mation of food chains culminating in jellvfishes. It is not known whether such alternative trophic pathways exist over large areas of the Gulf. Both the richness and the productivity of the benthos depend on primary productivity both in the water column (in the form of plankton and fecal pellets sinking to the bot- tom) and on the sea bottom (in the form of bacteria, micro- algae, and macrophytes). The flux of organic matter to the sea bottom is higher in shallow waters, due in part to ineffi- cient phytoplankton grazing by small copepods (Parsons, Ch. 18, this volume). Such data from the Gulf are few. Larrance and Chester (1979) showed that the daily loss of phytoplankton to the sea bottom was 8% of the standing stock in both Kachemak Bay (less than 100 m deep) and in Kamishak Bay (less than 50 m deep). These values are rather low for the neritic environment and suggest that herbivore grazing rather than algal cells sinking to the bottom repre- sents the major loss of phytoplankton from the water col- umn in these bays. Organic matter sinking from the water column combined with other detrital and living food sources forms an important source of nutrition for suspen- sion- and deposit-feeding fauna. King crab, Tanner crab, Dungeness crab, and pink shrimp are all primarily car- nivorous, and obtain a large part of their food by consuming detritus and detritivores. Pacific halibut, Pacific cod, and walleye pollock are also carnivores that use both benthic and demersal fauna such as shrimp and flatfish. Both shrimp and flatfish either directly or indirectly feed on detritus. Organic matter produced by benthic microalgae and bac- teria is expected to make a significant contribution to the overall trophodynamics of a coastal marine ecosystem. Atlas and Griffiths (Ch. 8, this volume) have discussed both the possible mechanisms and the magnitudes of organic pro- duction by bacteria in lower Cook Inlet. Quantitative data are not available, but bacterial production can be utilized in conventional food chains through a microbial loop: photo- synthesized organic matter to bacteria — bacteria to hetero- trophic flagellates — heterotrophic flagellates to microzooplankton. Brown algae, including kelp (Alaria spp., Agarum cribrosum, Laminaria groenlandica, and Nereocystis luetkeana) — and in some intertidal areas, the rockweed Fucus sp. — are widespread on rocky shores throughout the Gulf of Alaska. In dense patches, plant biomass can be very high: 10 to 20 kg wet weight/m2 off Kodiak (Calvin and Ellis 1978) and approaching 30 kg wet weight/m2 in Prince William Sound (Lees, Houghton, Erikson, Driskell, and Boettcher 1980). These biomass values are comparable to values from some of the richest seaweed-producing areas of the world such as Nova Scotia and Scotland. Macrophyte productivity estimates, based on a few data obtained during summer 1978, ranged from less than 0.2 kg C/m2y to over 4 kg C/m2y. The highest values were for Nereocystis sp. and Laminaria sp. in Prince William Sound (Lees et al. 1980). Macrophyte production may be an order of magnitude higher than primary productivity in the water column on a unit-area basis. However, very little of the mac- rophyte production (probably less than 10%) enters the food web through the grazing pathways because only a few animals — both in terms of species and numbers — feed directly upon macroalgae (Velimirov, Field, Griffiths, and Zoutendykl977). The detritus produced by macrophytes forms an impor- tant substrate for a variety of fauna and flora (including bac- 608 Issues and Perspectives teria), which are, in turn, consumed by larger animals and eventually contribute to the production of apex predators (Mann 1972). There is evidence that organic matter originat- ing with macrophytes is transported to the shelf areas — notably to the shallow banks where it can be retained and recirculated by currents that are predominantly tidally driven. A strong storm can uproot as much as 10% of the primary producer stock (Velimirov et al. 1977). Although actual data are lacking (only a few visual observations have been reported over the Kodiak shelf), significant algal drift and leaf litter can be predicted from the high wind waves and the frequent storms that are typical for the area. A plausible scenario for the decomposition and the use of macrophyte leaf litter may be as follows. First, epiphytic communities are torn off along with leaf blades and fronds and are removed from the region. Then, initial autolysis results in the release of dissolved organic matter, which is acted on by bacteria (and possibly fungi). Next, small preda- tors such as nematodes and ciliates build up on the drifting material, and animals that are feeding on the detritus strip off the fauna — then their subsequent feces are recolonized by bacteria. Finally, detritivores are consumed by larger, benthic predaceous species, some of which are commer- cially harvested. In this scenario, the cumulative role of the microorganisms is making macrophyte energy stores avail- able to the higher forms. This may be an important trophic pathway that is responsible for the high biological produc- tivity of the Kodiak shelf. Annual Production and Fisheries Yield The most easily recognizable results of the biological pro- duction in a region are the economic value of its harvest and the wildlife that region can sustain. In the nutrient-rich waters of upwelling areas, there may only be 1.5 to 2 trophic levels between algal production and planktivorous fish pro- duction. The overall efficiency of a food chain that has two trophic levels and 20 % efficiency at each level would be 4 % , and the yield to fisheries would be quite high in proportion to primary production (Crisp 1975). In the less fertile waters of oceanic areas, there are usually five or more trophic levels, each with lower efficiencies (about 10% ). These conditions lead to an overall trophic effi- ciency of ~ 0.001 percent. Ryther (1969) demonstrated that because of this low efficiency (and lower primary produc- tion), oceanic areas — despite their huge extent — contrib- uted less than 1% of the world's total fish production. The remaining fish production came from areas of the continen- tal shelf (54% of the total) and from upwelling areas (44% of the total). As noted earlier, the daily primary productivity rates in the Gulf are high. Accurate annual production estimates for much of the Gulf have not been made. Annual production estimates are only available for two areas in Prince William Sound: 1) Port Valdez (150 g C/m2) and 2) Valdez Arm (220 g C/m2) (Goering, Shiels, and Patton 1973). Data tabulated by Larrance and Chester (1979) can be used to calculate pri- mary production values for the phytoplankton growth sea- son (March to August) that exceed 500 g C/m2 in Kachemak Bay, 240 g C/m2 in the middle portion of lower Cook Inlet, and 250 g C/m2 in Kamishak Bay. Koblents-Mishke (1965) estimated (from little data) annual primary production rates of 100 g C/m2 for open shelf waters of the Gulf. Larrance (1971) reported values ranging from 20 to 200 g C/m2 for the northern North Pacific Ocean along the 176°W meridian during a three- year period from 1966 to 1968. The average annual primary production at Station P (located at 50°N and 145°W), during 1961 through 1966 was 48 g C/m2 (McAllister 1970). Data on macrophyte and kelp production are even more sparse; a representative figure for annual production in the littoral zone is 500 g C/m2. The 1984 commercial finfish and shellfish harvests in the Gulf of Alaska were over 50 x 104 mt and nearly 2 x 104 mt, respectively (Alaska Department of Fish and Game, unpubl. data; National Oceanic and Atmospheric Administration 1985). The finfish catch consisted of groundfish (68%), Pacific salmon species (25%), herring (4%), and halibut (3%). The shellfish catch consisted of Tanner crab (51%), Dungeness crab (23%), shrimp (23%), king crab (2%), and razor clam (1%). Based on these data, we can make a tenuous attempt to relate the commercial fish catch to the total primary produc- tion for the Gulf of Alaska. The continental shelf area of the Gulf is 3.62 x 105 km2 (McRoy and Goering 1974), about 1.8 x 105 km2 of which is open shelf, and the remaining area is fjords, embayments, and estuaries (Rand-McNally 1977). If one assumes that 100 g C/m2 is representative of the annual primary production for the open shelf and 200 g C/m2 is representative of production for inshore waters, the total annual water column primary production is 5.4 x 107 mt of carbon. Macrophyte production can be estimated at 6 x 105 mt of carbon if one assumes that 80% of the 75,680-km- long tidal shoreline of Alaska is located in the Gulf and that the average width of the littoral zone where macrophyte production takes place is 20 meters. This means that the sum of both water column and macrophyte production is equivalent to 5.5 x 107 mt of carbon. The commercial finfish and shellfish catch data, given as wet weight and usually referred to as biomass, can be con- verted into organic carbon equivalent amounts using con- version factors and ratios from Winberg (1956), Nishiyama (1975), and Crisp (1975). Using these conversion factors, the 1984 commercial finfish catch is equivalent to 5 x 104 mt of carbon, and the shellfish catch is 5.9 x 102 mt of carbon, resulting in a total catch value of slightly over 5 x 104 mt of carbon. The proportion of the total primary production ( ~ 5.5 x 107 mt of carbon) that is represented in the Gulf commercial fisheries catch is very small — 0.09 percent. This is only slightly higher than the value given for oceanic regions by Ryther (1969). Parsons (Ch. 18, this volume), using a primary production value of 300 g C/m2, gives a percentage of apex production (not commercial catch) to primary production that ranges from 0.8 to 1.0 percent. His corresponding val- ues for the open ocean are not included. In the North Sea, where the fishery consists offish such as herring from lower trophic levels and where fishing is more intense, a much Management Needs of Scientific Data 609 higher proportion (0.8%) of the primary production is har- vested. In the southeastern Bering Sea, where the fishery consists of both invertebrate apex predators and zoo- phagous fish (capelin and herring), the harvest was esti- mated at 0.4% of the total primary production (Walsh and Mc Roy 1986). The relatively low level of commercial Fisheries catch in the Gulf of Alaska in relation to total primary production may be explained by one or more of the following reasons: 1) A large proportion of the commercial fisheries catch is composed of Pacific salmon species along with a minor amount of halibut. These species are car- nivorous, and their high respective positions in the trophic structure are characterized by low overall trophic efficiencies. Conversely, it can be stated that the salmon catch in coastal waters also represents — to an unknown extent — production that is imported from the open ocean. 2) Much of the fisheries resource is not harvested. In 1984, the total catch allowed for foreign fishing in the Gulf was set at 320,686 mt, of which 119,910 mt remained unallocated. The 1984 total foreign catch amounted to 123,079 mt — 77,697 mt less than was allo- cated and 197,607 mt less than was allowed (NOAA 1985). 3) The region's mammal and bird populations are very significant consumers. Their yearly consumption — based on estimates from DeGange and Sanger (Ch. 16, this volume) and from Calkins (Ch. 17, this volume) — is —6.5 x 104 mt for birds and 7.7 x 105 mt for mam- mals. This amounts to — 8.4 x 105 mt of carbon each year for both groups, with birds accounting for less than 10% of the total. This amount is 16 times the amount of carbon removed by the commercial fish- eries, and accounts for 1.5% of the total carbon that is fixed in the system. 4) Primary production estimates may be too high, and efficient trophic pathways are not widespread in the region. Critical Habitats The biological richness of the Gulf of Alaska makes this region invaluable as a fish and wildlife resource area. For example, one of the world's largest harbor seal concentra- tions is at Tugidak Island. Large numbers are also found at Sitkinak Island, Geese Island, Aiaktalik Island, Ugak Island, and Shuyak Island — all in the western part of the Gulf. Very large Steller sea lion rookeries and hauling-out grounds are located on Sugarloaf Island, Marmot Island, Chirikof Island, and on Chowiet Island as well as in Puale Bay. Each of these major rookeries contributes pups to other distant areas of the Gulf. Sea otters — which had been hunted to very low lev- els by the turn of the century — have recovered as a result of legal protection. Moderate to high sea otter population den- sities are building at many locations such as Marmot and Chiniak Bays, and the species is expected to reinhabit its previous range throughout the Gulf. The largest seabird colonies — located on the Barren Islands — are dominated by three species: 1) the fork-tailed storm petrel (300,000 birds), 2) the common murre (60,000 birds), and 3) the tufted puffin (950,000 birds). Another large bird colony that is dominated by black-legged kit- tiwakes (160,000 birds) is located on Middleton Island. The large bird colonies of Cook Inlet (nearly 80,000 birds) are located in Tuxedni Bay and are composed of black-legged kittiwakes, common murres, horned puffins, and glaucous-winged gulls. Numerous other bird colonies have been identified and mapped by the United States Fish and Wildlife Service (Sowls, Hatch, and Lensink 1978). Millions of shearwaters from the Southern Hemisphere visit the western Gulf of Alaska during spring and summer where they feed intensely in the pelagic zone. In addition, most of the world's population of western sandpipers and the entire western-Alaska breeding population of dunlin are believed to migrate through the Copper River Delta. All nearshore and shelf waters, embayments, coastal streams, and rivers are used by both finfish and shellfish either as migratory pathways or as preferred habitats for feeding, breeding, spawning, or rearing of young. Kelp beds are particularly important because they are protective hab- itat for many species, including the larval and juvenile stages of the commercially valuable Pacific salmon as well as king and Tanner crabs. Given the widespread distribution of biota throughout the Gulf and the sporadic nature of the existing database, it is difficult to designate certain areas as biologically more sig- nificant than others. The biological productivity (and the species richness that results) appears to be higher in the cen- tral and western parts of the Gulf than it is in the eastern part, but this observation could be the result of a greater number of studies conducted in the Cook Inlet and the Kodiak regions. In coastal areas under its jurisdiction, the State of Alaska defines biologically sensitive areas in the context of its resource management policies (Kramer, Clark, and Can- nelos 1978). Accordingly, sensitive areas include (but are not limited to): • estuaries • wetlands • river deltas • fish spawning grounds • intensive-use habitats • bird-nesting areas • waterfowl and shorebird staging areas • migration routes • wildlife wintering habitat • sea-mammal rookeries and hauling-out grounds. Under Alaska Statutes Title 16, Chapter 20 (Conservation and Protection of Alaska Wildlife), the State has designated certain areas as critical habitats to protect and preserve hab- itats that are especially crucial to the perpetuation of the fish and wildlife, and to restrict all uses not compatible with that purpose. To date, six critical habitats are identified in the coastal areas of the Gulf (Figure 20-4). Additional critical 610 Issues and Perspectives 150 145 140 Figure 20-4. Locations of the six critical biological habitats that have been designated by the State of Alaska. habitats can be added by legislative approval. No critical habitats have been designated by the Federal government in this region. Characteristics of critical habitats. Key features of the currently designated State of Alaska critical habitats are noted below: Copper River Delta, (a) One of the worlds most important waterfowl and shorebird concentration and feeding areas. The tidal flats and marshes of the Delta — which encompass 500 km2 — are host to more than 20 million birds during the peak of the spring and fall migration, (b) A migratory and staging area for most of the world population of western sandpiper and the entire western Alaska breeding popula- tion of dunlin, (c) An important breeding and nesting area for many waterfowl species, especially dusky Canada goose and trumpeter swan, (d) The waterfowl found in the Delta include such trans-Pacific migrants as the pintail and the American widgeon, (e) A major fishery for Dungeness crab, king salmon, sockeye salmon, and coho salmon, (f) An important habitat for harbor seals during summer, particu- larly in the Barrier Islands seaward of the Delta. Clam Gulch. A large concentration of razor clams used heavily for both recreation and subsistence. Fox River Flats, (a) A foraging area for thousands of water- fowl and shorebirds. (b) A feeding area for chum and pink salmon, shrimp, and Dungeness crab, (c) A breeding area for about 800 geese and ducks, (d) A heavy-use area for sport fishermen, hikers, and recreationists during summer and fall. Kachemak Bay. (a) An extensive commercial fishery for king crab, Tanner crab, Dungeness crab, shrimp, Pacific salmon, Pacific herring, and Pacific halibut, (b) The single most important fish spawning area in Cook Inlet during spring (the inner portion of the Bay), (c) An abundance of larval and post-larval stages of king crab, Tanner crab, Dun- geness crab, and various species of pandalid shrimp throughout the year, (d) A number of important seabird colonies on Gull Island, Sixty-foot Rock, and Grass Island, (e) A wintering area for approximately 10,000 white-winged scoters. An important concentration area for marbled and Kittlitz murrelets during summer, (f) A high density of sea otters in the kelp beds. Harbor seal, Steller sea lion, harbor porpoise, Dall's porpoise, and killer whale are also fre- quently found here. Kalgin Island, (a) A spring staging area (because the wet- lands here thaw early) for migratory waterfowl that include dabblers, snow geese, Canada geese, and swans, (b) A habitat for breeding waterfowl such as pintails, mallards, and teals. (c) A high density area for harbor seals during summer, (d) An important moose habitat. Chilkat River Flats, (a) A fall and winter gathering area for northern bald eagles, representing the largest known con- centration of the species (2,500 or more birds) in the world, (b) An important habitat for the northern bald eagle for feeding (on chum, coho, and sockeye salmon), for nesting (primarily in cottonwood trees), and for breeding (approx- imately 30% active nests). Endangered Species Seven species of whales and two species of birds that occur in the region either seasonally or at irregular intervals have been designated as endangered species (Federal Regis- ter, 48 (145), 1983). The Endangered Species Act as amended (P.L. 97-304, 96 Stat. 1411, October 13, 1982), defines 'endangered species' as any species in danger of extinction throughout all or a significant portion of its range. Such danger can be due to: 1) destruction, modification or curtail- ment of its habitat or range, 2) overuse of the species for commercial or other purposes, 3) disease or predation, 4) inadequacy of existing regulatory mechanisms, or 5) other natural or manmade factors affecting its continued exis- tence. These species, their habitats, and their migratory range must be protected from adverse impact due to human activities. Management Needs of Scientific Data 6T1 The populations of the endangered cetacean species were greatly diminished as a result of commercial whaling. Even though protected by the Endangered Species Act, other acts, and by international agreements, only the gray whale population — which was almost exterminated early in the century — appears to have recovered to its pre-exploit- ation level. Its North Pacific population is estimated at about 1:5,000 to 17,000 animals, most of which use the Gulf (Reillv 1984). Populations of some other endangered whale species are still very small (Wolman 1978; Calkins, ( '.h. 17, this volume). Because of the whales' cosmopolitan nature and their extensive seasonal migration, scientific data bases for most species are both sporadic and unsatisfactory. The present knowledge of the distribution and the biology of the gray whale, which migrates dose to the shore, is the best available among endangered species that occur in the Gulf (Jones, Swartz, and Leatherwood 1984). The population distribu- tion, habitat use, and feeding data that do exist for other spe- cies are scant and, for the most part, are based on extrapola- tions from other areas of the North Pacific Ocean (Calkins, Ch. 17, this volume). (.lacier Bay (southeastern Alaska) is the only area where site-specific studies have been done on habitat characteriza- tion, food resources, and the impact that motorized vessel traffic has on the occurrence and behavior of the humpback whale (Baker, Herman, Bays, and Bauer 1982). The Aleutian Canada goose is probably not found in the Gulf. Its known breeding ground is Buldir Island, and it is suspected that during migration, the geese fly east to Unimak Pass and then across the Pacific Ocean to their win- tering grounds in California. Sightings of short-tailed albatross have been recorded at certain sites in the Gulf, but sufficient data do not exist to establish their migratory routes or habitat use in the Gulf of Alaska. Other Data It is evident from the above account that those species that have a high visibility, are susceptible to environmental pollution, have commercial value, or are under legal protec- tion have received priority for research. We know the com- position of both the bird and mammals faunas as well as the location and the approximate size of the seabird colonies and the marine mammal rookeries and haul-out areas. Data on both pelagic and non-colonial birds are relatively few but are sufficient to describe the species distribution, the population sizes, and the habitat use for many areas. Data concerning the food and the feeding habits of selected species have also been obtained, and some calcula- tions have been made for their energetics and their growth rates. Fecundity rates, breeding phenologies, and other life- history information are also available for a number of spe- cies such as the harbor seal, the Steller sea lion, the black- legged kittiwake, the tufted puffin, and others. Benthic macroinvertebrate distributions have been established for some areas, and the food webs have been described for a few species. This improved data base is reflected in progressively better environmental descrip- tions and issues analyses in the several environmental impact statements that were prepared during the period from 1975 to 1984 for planned OCS oil and gas lease sales in the Gulf. Special considerations can now be offered that can minimize the impacts from industrial installations and other activities on a number of species. Commercial- and sport-catch statistics, estimates of pop- ulation- or stock sizes, and the general life-history data of the commercially important tin fish and shellfish have been obtained and maintained by the fisheries management agencies of the State of Alaska and the Federal government for a number of years. These data are mostly for the adult forms, but data on the early life history, including the larval and thejuvenile forms, are far more scant and sporadic, and are generally inadequate to describe the population dynam- ics of any given species. The overall fisheries data are spa- tially very limited when viewed in light of the expanded U.S. Fishery Conservation Zone (FCZ), and in light of increasing efforts to harvest larger quantities of groundfish (pollock, cod, sablefish, and Pacific ocean perch) on the continental shelf and slope. Estimates of both the size of the fish population and the maximum allowable commercial catch (maximum sustaina- ble yield [MSY]) that will still ensure perpetuation of the spe- cies exist for only a few species. Such species include those whose life histories, population dynamics, and ecology are well known and for which resource management policies exist (e.g., the Pacific salmon species and the Pacific halibut). In most cases the calculated MSY is modified by ecological, economic, and social factors so that catch allowances are actually based on optimum yield (OY). Special considera- tions are given to aquaculture, extended jurisdiction, coastal-zone management policies, international negotia- tions, employment, and market conditions. Multispecies numerical models are intended to provide both quantitative recruitment assessments and population forecasts for particular fisheries. These assessments and forecasts are aimed at facilitating decisions made by resource managers and by the fishing industry. Results from numerical simulation tests, particularly those for which the data base is limited, are usually based on simplified assump- tions and inadequate understanding of variability. While they may provide considerable insight into the adequacy of the data base, they often have little predictive value. There are extremely serious deficiencies in the often-used strategy of hierarchical arrangement of trophic levels — which aggre- gates species at the level of a guild — when describing ecosystems or when modeling multi-species interactions (Cousins 1985). Such approaches are not suitable for devel- oping resource management strategies, i.e., for fisheries (Beddington 1986). Continued, but preferably more intensified research is needed on the biology of target species and on pertinent environmental parameters in order to monitor variability and forecast abundance of fish and shellfish populations. Without such efforts, the goal of preventing over-fishing, rebuilding overfished stocks, and realizing the full potential of the United States fishery resources — notably in the expanded Fishery Conservation Zone — will remain elusive (Fishery Conservation and Management Act, P.L. 94-265, 90 Stat. 331, April 13, 1976). 612 Issues and Perspectives Conclusion Our understanding of the Gulf of Alaska's environment and its biological resources has greatly improved during the past 15 years. The investigations that were carried out dur- ing this period were aimed at providing a scientific frame- work to use in making resource management decisions and in preparing environmental impact statements. Environ- mental issues, particularly those pertaining to petroleum development and transportation, have figured prominently in both the planning and the funding of research. As a result, existing data are not uniform either in their scope or in their comprehensiveness for different parts of the Gulf. In addition, a substantial amount of the biological and phys- ical data gathered over the last 15 years remains either unanalyzed or unreported. Even within the limits of the existing data base, it is possi- ble to identify those areas and phenomena that are hazardous to industrial structures and to operations in the marine environment. For example, prominent ocean- circulation features are documented well enough to let us do spilled-oil trajectory and oil weathering-state calcula- tions. The entire coastline, with the exception of Southeast Alaska, has been surveyed and its various segments cate- gorized for their spilled-oil retention potential. However, seasonal variability (in many cases) and annual variability (in nearly all cases) have not been established for the phe- nomena and processes that have been studied so far. Even in those cases for which many years of data are available, the problems of interannual variability in both the oceanographic features and the biological populations remain unresolved (Frost 1983). Both spatial spottiness in the data and an imbalance in the disciplinary coverage pose significant impediments to a comprehensive or holistic approach to marine environmen- tal assessment (Holling 1978). The present data are inade- quate to evaluate the biological productivity of many differ- ent areas within a region as is required by the OCS Lands Act as amended (P.L. 95-372, 92 Stat. 629, September 18, 1978). Data are also inadequate to estimate the biological community's diversity, its productivity, or its stability as required by the Federal Water Pollution Control Act (or Clean Water Act) as amended (P.L. 95-576, 92 Stat. 2467, November 2, 1978). The importance of having a comprehen- sive understanding of the various marine ecosystems is also underscored by the Marine Protection, Research, and Sanc- tuaries Act as amended (P.L. 95-153, 91 Stat. 1255, November 4, 1977). There are many research needs — stated along disciplin- ary lines and each with its own scientific merit — that have been noted by the authors who have contributed to this vol- ume. The uneven nature of the existing data, both in terms of location and in terms of various disciplines, is also reflected in the relative comprehensiveness and scope of individual chapters. The contentious interpretations of the same data set — "sufficient information exists to safeguard the environ- ment" versus "major gaps in existing information preclude an adequate assessment of environmental impacts" — can best be viewed in the context of the Engelmann Diagram (Fig. 20-1). While a convincing argument can be made to strive continually to reduce the overall risks to society, the increased role of the government in such endeavors (at greatly increased expenditure of public funds) should be viewed in light of its effectiveness — both in terms of cost and attainment of objectives. The criteria for determining the significance of environ- mental impacts — even in a relative sense — are not clearly defined, although Duinker and Beanlands (1986) have recently discussed four perspectives on impact significance. These perspectives are related to 1) statistical, 2) ecological, 3) social, and 4) project-induced changes. Research continues in an effort to assess the resource potential in the United States' Exclusive Economic Zone, to guide future industrial development both in offshore and coastal areas, and to help improve scientific understanding of the physical environment and biological resources of this region. Disseminating scientific information to the public and publishing research papers in scientific journals have been a major part of the research programs conducted in the Gulf. Research reports and publications that resulted from OCSEAP funding are listed in a bibliography (NOAA 1984). Environmental data were reviewed and summarized peri- odically between 1974 and 1980. Synthesis meetings among scientists were attended by government and industry repre- sentatives, and by individuals from various interest groups. The meetings provided a forum to present both newly acquired data and the interpretation of those data as they related to OCS lease sale decisions for the northern and western Gulf, for Cook Inlet, and for Shelikof Strait. Proceedings from synthesis meetings became widely read source documents for those seeking environmental information. It is to the credit of the management of the research programs conducted in this region that a number of single-source reference volumes have been prepared (AEIDC 1974; Hood et al. 1973; Colonell 1980; Ellis 1982). The publication of this volume is another step in that direction. Acknowledgments The preparation of this chapter was funded, in part, by administrative support provided by the Minerals Manage- ment Service, Department of the Interior, through an inter- agency agreement with the National Oceanic and Atmos- pheric Administration, Department of Commerce, as part of the Outer Continental Shelf Environmental Assessment Program. Management Needs oe Scientific Data 613 References Arctic Environmental Information and Data Center 1974 The Western Gulf of Alaska: A Summary of Available Knowledge. University of Alaska, Anchorage, AK. 599 pp. Baker, C.S., L.M. Herman, B.C. Bays, and G. Bauer 1982 The impact of vessel traffic on the behavior of humpback whales in Southeast Alaska: 1982 season. Progress report to NOAA, National Marine Fisheries Service, National Marine Mammal Laboratory, Seattle, WA. 31 pp. plus appendices. Beddington,J.R. 1986 Shifts in resource populations in large marine ecosystems. In: Variability and Management of Large Marine Ecosystems. K. Sherman and L.M. Alexander, editors. American Association for the Advancement of Science, Washington D.C. pp. 9-18. Bowman, M.J. 1978 Proceedings of the workshop. In: Ocean Fronts in Coastal Processes: Proceedings of a Workshop held at the Marine Sciences Research Center, May 25-27, 1977. M.J. Bowman and W.E. Esaias, editors. Springer- Verlag, New York. pp. 6-13. Brower, W.A., H.W. Searby, J.L. Wise, H.F. Diaz, and A.S. Prechtel 1977 Climatic Atlas of the Outer- Continental Shelf Waters and Coastal Regions of Alaska, Vol. 1: Gulf of Alaska. Publication B-27, Arctic Environmental Infor- mation and Data Center, University of Alaska, Anchorage, AK. 439. pp. Calvin, N.I. and R.J. Ellis 1978 Quantitative and qualitative observations on Laminaria dentigera and other subtidal kelps of southern Kodiak Island, Alaska. Marine Biology (Berlin) 47:331-336. Carlson, P.R. 1978 Holocene slump on continental shelf off Mai- aspina Glacier, Gulf of Alaska. Bulletin of the American Association of Petroleum Geologists 62:2412-2426. Colonell, J.M., editor 1980 Port Valdez, Alaska: Environmental Studies, 1976-79. Occasional Publication No. 5, Institute of Marine Science, University of Alaska, Fairbanks, AK. 373 pp. Cousins, S. 1985 Ecologists build pyramids again. New Scientist 406:50-54. Crisp, DJ. 1975 Secondary productivity in the sea. In: Productiv- ity of World Ecosystems. National Academy of Sci- ences, Washington, D.C. pp. 71-89. Cross, J.N., K.L. Fresh, B.S. Miller, C.A. Simenstad, S.N. Steinfort, andJ.C. Fegley 1978 Nearshore fish and macroinvertebrate assemblages along the Strait of Juan de Fuca including food habits of the common near- shore fish. NOAA Technical Memorandum ERL/MESA-32. 188 pp. Duinker, P.N. and G.E. Beanlands 1986 The significance of environmental impacts: an exploration of the concept. Environmental Man- agement 10:1-10. Dunn, F.P. 1982 Platform design/construction - overview (SPE Paper 9999). In: Proceedings of the International Meeting on Petroleum Engineering, Beijing, China, March 1982. Society of Petroleum Engineers, Dallas, TX. pp. 397-407. Ellis, D.V., editor 1982 Marine Tailings Disposal. Ann Arbor Science, Ann Arbor, MI. 368 pp. Freeman, A.M., Ill, R.H. Haveman, and A.V. Kneese 1973 The Economics of Environmental Policy. John Wiley 8c Sons, New York, NY. 184 pp. Frost, B.W. 1983 Interannual variation of zooplankton standing stock in the open Gulf of Alaska. In: From Year to Year: Interannual Variability of the Environment and Fisheries of the Gulf of Alaska and the Eastern Bering Sea. W.S. Wooster, editor. Washington Sea Grant Publication 83-3, University of Washington, Seattle, WA. pp. 146-157. Gait, J.A., J.E. Overland, C.S. Smith, Y.J. Han, and C.H. Pease 1977 Numerical studies of Alaskan region. Research Unit 140. Environmental Assessment of the Alaskan Continental Shelf Annual Reports of Principal Inves- tigators 14:329-406. Gait, J. A. and G. Watabayashi 1980 Modeling report to OCSEAP. Environmental Assessment of the Alaskan Continental Shelf. Final Reports of Principal Investigators 26:1-61. Goering, J.J., W.E. Shiels, and C.J. Patton 1973 Primary production. In: Environmental Studies of Port Valdez. D.W. Hood, W.E. Shiels, and EJ. Kelley, editors. Occasional Publication No. 3, Institute of Marine Science, University of Alaska, Fairbanks, AK. pp. 251-279. 614 Issues and Perspectives Greisman, P. 1985 Western Gulf of Alaska tides and circulation. Research Unit 657. Final report submitted to NOAA, Alaska Outer Continental Shelf Environmental Assessment Program. Dobrocky-Seatech Ltd., Sidney, B.C. 112 pp. Greve, W. and T.R. Parsons 1977 Photosynthesis and fish production: hypo- thetical effects of climatic change and pollu- tion. Helgolander wissenschaftliche Meeresunter- siuhungen 30:666-672. Harding, J. M. 1976 Tidal currents and pollutant dispersal in the western Gulf of Alaska as derived from a hydro- dynamic-numerical model. Research Unit 235. Environmental Assessment of the Alaskan Continen- tal Shelf, Quarterly Reports of Principal Investigators July-September 3:781-825. Hayes, M.O. and C.H. Ruby 1979 Oil spill vulnerability, coastal morphology, and sedimentation of the Kodiak Archipelago. Research Unit 59. Environmental Assessment of the Alaskan Continental Shelf Final Reports of Principal Investigators 2:1-155. Holling, C.S., editor 1978 Adaptive Environmental Assessment and Manage- ment. John Wiley & Sons, New York, NY. 377 pp. Hood, D.W., W.E. Shiels, and EJ. Kelley, editors 1973 Environmental Studies of Port Valdez. Occasional Publication No. 3, Institute of Marine Science, University of Alaska, Fairbanks, AK. 495 pp. Iverson, R.L., H.C. Curl, Jr., H.B. O'Connors, Jr., D. Kirk, and K. Zakar 1974 Summer phytoplankton blooms in Auke Bay, Alaska, driven by wind mixing of the water col- umn. Limnology and Oceanography 19:271-278. Iverson, R.L., L.K. Coachman, R.T. Cooney, T.S. English, J.J. Goering, G.L. Hunt, M.C. Macauley, C.P. McRoy, W.S. Reeburgh, and T.E. Whitledge 1979 Ecological significance of fronts in the south- eastern Bering Sea. In: Ecological Processes in Coastal and Marine Systems. R.J. Livingston, edi- tor. Plenum Press, New York, NY. pp. 437-466. Jacob, K.H. and E. Hauksson 1983 A seismotectonic analysis of the seismic and volcanic hazards in the Pribilof Islands- eastern Aleutian Islands region of the Bering Sea. Research Unit 16. Final report submitted to NOAA, Alaska Outer Continental Shelf Environmental Assessment Program. Lamont- Doherty Geological Observatory, Palisades, NY. 236 pp. Jones, M.L., S.L. Swartz, and S. Leatherwood, editors 1984 The Gray Whale Eschrichtius robustus. Aca- demic Press, Orlando, FL. 600 pp. Kerr, S.R. 1971 A simulation model of lake trout growth. Jour- nal of the Fisheries Research Board of Canada 28:815-819. Kienle, J. and G.E. Shaw 1979 Plume dynamics, thermal energy and long dis- tance transport of volcanian eruption clouds from Augustine Volcano, Maska. Journal of Vol- canology and Geothermal Research 6:139-164. Kienle, J. and S.E. Swanson 1980 Volcanic hazards from future eruptions of Augustine Volcano, Alaska. Report UAG R-275, Geophysical Institute, University of Alaska, Fairbanks, AK. 122 pp. Koblents-Mishke, O.I. 1965 Primary production in the Pacific. Oceanology 5(2):104-116. Kramer, L.S., V.C. Clark, and G.J. Cannelos 1978 Planning for Offshore Oil Development: Gidf of Alaska OCS Handbook. Alaska Department of Community and Regional Affairs, Juneau, AK. 257 pp. Lagerloef, G.S.E. 1983 Topographically controlled flow around a deep trough transecting the shelf off Kodiak Island, Alaska. Journal of Physical Oceanography 13:139-146. Landry, M.R. 1977 A review of important concepts in the trophic organization of pelagic ecosystems. Helgolander wissenschaftliche Meeresuntersuchungen 30:8-17. Larrance,J.D. 1971 Primary production in the mid-subarctic Pacific Ocean region, 1966-68. Fishery Bulletin (U.S.) 69:595-613. Larrance, J.D. and A.J. Chester 1979 Source, composition, and flux of organic detritus in lower Cook Inlet. Research Unit 425. Outer Continental Shelf Environmental Assess- ment Program, Final Reports of Principal Investiga- tors 46:1-71. Larrance, J.D., D.A. Tennant, A.J. Chester, and P.A. Ruffio 1977 Phytoplankton and primary productivity in the northeast Gulf of Alaska and lower Cook Inlet. Research Unit 425. Environmental Assess- ment of the Alaskan Continental Shelf, Annual Reports 10:1-136. Management Needs of Scientific Data 615 LeBrasseur, R.J. 1969 Growth of juvenile chum salmon (Oncorhynchus keta) under different feeding regimes. Journal of the Fisheries Research Board of Canada 26:1631- 1645. Lees, D.C., J. P. Houghton, D.E. Erikson, and VV.B. Driskell, and D.E. Boetteher 1980 Ecological studies of intertidal and shallow sub- tidal habitats in lower Cook Inlet, Alaska. Research Unit 417. Final report submitted to NOAA, Alaska Outer Continental Shelf" Environmental Assessment Program. Dames and Moore, Anchorage, AK. 406 pp. Leopold, D.B.,Jr., F.E. Clarke, B.B. Hanshaw, andJ.R. Balsley 1971 A procedure for evaluating environmental impact. U.S. Geological Survey Circular 645. 13 pp. plus appendix. Liu, S.K. andJJ. Leendertse 1985 Modeling of the Alaskan coastal waters (draft). Research Unit 435. Final report submitted to NOAA, Alaska Outer Continental Shelf Environmental Assessment Program. The Rand Corporation, Santa Monica, CA. 148 pp. LowTy, G.K.,Jr. 1980 Policy-relevant assessment of coastal zone management programs. Coastal Zone Manage- ment Journal 8:227-255. Mann, K.H. 1972 Macrophyte production and detritus food chains in coastal waters. In: Proceedings of the IBP-UNESCO Symposium on Detritus and its Eco- logical Role in Aquatic Ecosystems, Pallanza, Italy. U. Melchiorri-Santolini andJ.W. Hopton, editors. Memorie DelFInstituto Italiano Di Idrobiologia. Vol. 29 supplement, pp. 353-383. McAllister, CD. 1969 Aspects of estimating zooplankton production from phytoplankton production, fournal of the Fisheries Research Board of Canada 26:199-220. McAllister, CD. 1970 Some aspects of nocturnal and continuous grazing by planktonic herbivores in relation to production studies. Ph.D. Dissertation, Univer- sity of Washington, Seattle, WA. 272 pp. McNutt, S.R. 1983 Volcanic hazards. In: A seismotectonic analysis of the seismic and volcanic hazards in the Pri- bilof Islands-eastern Aleutian Islands region of the Bering Sea. Research Unit 16. K.H. Jacob and E. Hauksson, compilers. Final report sub- mitted to NOAA, Alaska Outer Continental Shelf Environmental Assessment Program. Lamont-Dohertv Geological Observatory, Pal- isades, NY. pp. 122-136. McRoy, C.P. and J.J. Goering 1974 Coastal ecosystems of Alaska. In: Coastal Fxologi- cat Systems of the United States. H.T. Odum, B.J. Copeland, and E.A. McMahan, editors. The Conservation Foundation, Washington, D.C. pp. 124-131. Molnia, B.F., P.R. Carlson, and T.R. Bruns 1977 Large submarine slide in Kayak Trough, Gulf of Alaska. Reviews in Engineering Ceology 3:137-148. Muench, R.D. and D.L. Nebert 1973 Physical oceanography. In: Environmental Stud- ies of Port Valdez. D.W. Hood, W.E. Shiels, and E.J. Kelley, editors. Occasional Publication No. 3, Institute of Marine Science, University of Alaska, Fairbanks, AK. pp. 103-149. Mungall,J.CH. 1973 Cook Inlet tidal stream atlas. Report 73-6, Institute of Marine Science, University of Alaska, Fairbanks, AK. 24 pp. National Oceanic and Atmospheric Administration (NOAA) 1984 Comprehensive Bibliography. NOAA, Ocean Assessments Division, Juneau, AK. 607 pp. National Oceanic and Atmospheric Administration (NOAA) 1985 Fisheries of the United States, 1984. Current Fishery Statistics No. 8360. U.S. Department of Commerce, Washington, D.C. 121 pp. Nebert, D.L. 1982 The circulation of the Smeaton Bay and Boca de Quadra fjord systems. In: Marine Tailings Dis- posal. D.V. Ellis, editor. Ann Arbor Science, Ann Arbor, MI. pp. 291-310. Nemoto, T. 1970 Feeding patterns of baleen whales in the ocean. In: Marine Food Cluiins. J.H. Steele, editor. Uni- versity of California Press, Berkeley, CA. pp. 241-252. Nishiyama, T. 1975 Ecological approach to fisheries. In: Bering Sea oceanography: an update. Y. Takenouti and D.W. Hood, editors. Report No. 75-2, Univer- sity of Alaska, Fairbanks, AK. pp. 153-156. O'Brien, WJ. 1979 The predator-prey interaction of plank- tivorous fish and zooplankton. American Scien- tist 67:571-581. Parsons, T.R., R.J. LeBrasseur, and W.E. Barraclough 1970 Levels of production in the pelagic environ- ment of the Strait of Georgia. British Colum- bia: a review. Journal of the Fisheries Research Board of Canada 27:1251-1264. 616 Issues and Perspectives Payne, J.R., B.E. Kirstein, G.D. McNabb, Jr., J.L. Lambach, R. Redding, R.E. Jordan, D.M. Baxter, and R. Gaegel 1984 Multivariate analysis of petroleum weathering in the marine environment. Research Unit 597. Final report submitted to NOAA, Alaska Outer Continental Shelf Environmental Assessment Program. Science Applications International Corporation, Lajolla, CA. 569 pp. Pease, C.H. and A.L. Comiskey 1985 Vessel icing in Alaskan waters - 1979 to 1984 data set. Data Report ERL/PMEL-14, NOAA, Pacific Marine Environmental Laboratory, Seattle, WA. 15 pp. Rand-McNally 1977 The Rand-McNally Atlas of the Oceans. Rand McNally and Company, Chicago, IL. 208 pp. Reilly, S.B. 1984 Assessing gray whale abundance: a review. In: The Gray Whale Eschrichtius robustus. MJ. Jones, S.L. Swartz, and S. Leatherwood, editors. Academic Press, Orlando, FL. pp. 203-223. Ruby, C.H. 1977 Coastal morphology, sedimentation, and oil spill vulnerability: northern Gulf of Alaska. Technical Report No. 15-CRD, University of South Carolina, Columbia, SC. 223 pp. Ryther,J.H. 1969 Relationship of photosynthesis to fish produc- tion in the sea. Science 166:72-76. Sambrotto, R.N., H.J. Niebauer, J.J. Goering, and R.L. Iverson 1986 Relationships among vertical mixing, nitrate uptake, and phytoplankton growth during the spring bloom in the southeast Bering Sea mid- dle shelf. Continental Shelf Research 5:161-198. Savage, J.C., M. Lisowski, and W.H. Prescott 1986 Strain accumulation in the Shumagin and Yakataga seismic gaps, Alaska. Science 231:585-587. Savidge, G. 1976 A preliminary study of the distribution of chlo- rophyll a in the vicinity of fronts in the Celtic and Western Irish seas. Estuarine and Coastal Marine Science 4:617-625. Schlueter, R.S. and C.I. Rauw 1981 Oil spill trajectory simulation, lower Cook Inlet-Shelikof Strait, Alaska. Final report sub- mitted to NOAA, Alaska Outer Continental Shelf Environmental Assessment Program. Dames and Moore, Anchorage, AK. 51 pp. plus maps. Science Applications, Inc. 1980 Environmental Assessment of the Alaskan Outer Continental Shelf: Kodiak Interim Syn- thesis Report - 1980. Boulder, CO. 326 pp. Shaw, D.G. and M.J. Hameedi, editors In press Environmental Management of Port Valdez, Alaska. Springer-Verlag, New York , NY. Sowls, A.L., S.A. Hatch, and C.J. Lensink 1978 Catalog of Alaska seabird colonies. Special Publication FWS/OBS-78/78, U.S. Department of the Interior, Fish and Wildlife Service, Anchorage, AK. 153 maps and supporting text. Thomson, R.E. andJ.F.R. Gower 1985 A wind-induced mesoscale eddy over the Van- couver Island continental slope. Journal of Geo- physical Research 90C:8981-8993. Torgrimson, G.A. 1984 The on-scene spill model. NOAA Technical Memorandum NOS OMA 12. 50 pp. U.S. Department of the Interior 1980 Final Environmental Impact Statement (Sale No. 55). Bureau of Land Management, Wash- ington, D.C. 2 vols. U.S. Department of the Interior 1984 Draft Environmental Impact Statement: Gulf of Alaska/Cook Inlet lease offering. Minerals Management Service, Alaska OCS Region, Anchorage, AK. Multiple pagination. Velimirov, B., J.G. Field, C.L. Griffiths, and P. Zoutendyk 1977 The ecology of kelp bed communities in the Benguela upwelling system. Helgoldnder wissenschaftliche Meeresuntersuchungen 30:495- 518. Vogel, A.H. and G. McMurray 1986 Seasonal population density distribution of copepods, euphausiids, amphipods and other holoplankton on the Kodiak shelf. Outer Conti- nental Shelf Environmental Assessment Program, Final Reports of Principal Investigators 46:423- 659. Walsh, J.J. and C.P. McRoy 1986 Ecosystem analysis in the southeastern Bering Sea. Continental Shelf Research 5:259-288. Whyte, A.V., and I. Burton, editors 1980 Environmental Risk Assessment. John Wiley & Sons, New York, NY. 157 pp. Winberg, G.C. 1956 Rate of metabolism and food requirements of fish. Nauchnye Trudy Belorusskovo Gos- uderstvennovo Universitata Imeni VI Lenina Miusk. 253 pp. (Fisheries Research Board of Canada Translation Series No. 194) Management Needs of Scientific Data 617 Wolfe, D.A. In press A decision-analytic approach for develop- ment of optimal waste management strategies. In: Oceanic Processes and Marine Pollution, Vol. 3: Marine Waste Management. M.A. Champ and P.K. Park, editors. Robert E. Krieger Publishing Company, Malabar, FL. Wolman, A. A. 1978 Humpback whale. In: Marine Mammals of East- ern North Pacific and Arctic Waters. D. Haley, edi- tor. Pacific Search Press, Seattle, WA. pp. 46-53. Woodward-Clyde Consultants 1982a Development and initial application of soft- ware for seismic exposure evaluation, volume I: software description. Research Unit 590. Final report submitted to NOAA, Alaska Outer Continental Shelf Environmental Assessment Program. San Francisco, CA. 192 pp. Woodward-Clyde Consultants 1982b Development and initial application of soft- ware for seismic exposure evaluation, volume II: seismic exposure software application. Research Unit 590. Final report submitted to NOAA, Alaska Outer Continental Shelf Environmental Assessment Program. San Francisco, CA. 129 pp. Glossakv 619 Glossary The terms defined in this section were selected from the text of the 20 chapters in this book. Definitions of some terms are general and comprehensive in nature, whereas others are specific and relate only to the subject matter of the chap- ters from which they were taken. For more general defini- tions of some terms, and for definitions of terms not included in this glossary, the reader is encouraged to refer to other glossaries or dictionaries of scientific/oceanographic terms such as: Baker, B.B., Jr., W.R. Deebel, and R.D. Geisenderfer, editors 1966 Glossary of Oceanographic Terms, 2nd edi- tion. U.S. Naval Oceanographic Office, Wash- ington, D.C. 204 pp. Considine, D.M., editor 1983 Van Nostrand's Scientific Encyclopedia, 6th edition. Van Nostrand Reinhold Co., New York, NY. 3,067 pp. Accretion — The addition of crustal material to existing crust. Acid rain — Rain that has a depressed pH due to presence of hvdrolvzed end products from oxidized sulfur-, nitro- gen-, or halogen-containing compounds. Acoustic anomalies — Variations in sound velocity, refrac- tion, or reflection from that expected in a continuous medium; a phenomenon of great importance in geophys- ical studies. Acoustic surveys (biological) — The use of reflected sound to determine the relative distribution or density of school- ing fish or plankton. Advection — Differential motion within a fluid; changes in properties (e.g., temperature, salinity) that take place in the presence of horizontal or vertical flows of seawater (i.e., currents) represent advective changes. Age structure — The distribution of the various age groups within a stock or population of animals. Alaska Coastal Management Program — A state program, mandated by the Alaska Coastal Management Act of 1977, which seeks to balance utilization and protection of the coastal area. Alaska National Interest Lands Conservation Act (P.L. 96-487, 16 U.S.C. 3101 etseq.) — This act is the last stage of a process begun in 1958 with the passage of the Statehood Act and followed by conveyances of federal lands to state and native ownership. It sets aside federal lands for national parks, preserves, wildlife ranges, and wilderness areas. Alaska Native Claims Settlement Act of 1971 (P.L. 92-203, 43 U.S.C. 1601 et seq.) — This law provides for the conveyance of about 44 million acres of land and almost one billion dollars to Alaska's natives in exchange for the extinguish- ment of all further claims to lands. In addition, it estab- lishes twelve regional native corporations and a thir- teenth region' corporation for Alaskan Natives residing out of state. Alaskan Gyre — The dominant circulation feature in the Gulf of Alaska formed by the counterclockwise flow of the Subarctic Current and its continuation as the Alaska Cur- rent. Alcid — Any of 16 species of diving seabirds (Alcidae) that are found exclusively in the northern hemisphere (e.g., murres, puffins, and auklets). Aleutian Canada goose — Branta canadensis leucopareia, a small subspecies of Canada goose that nests in the Aleu- tian Islands. Aleutian Tern — A medium-small fish- and plankton-fee- ding seabird (Laridae, Sterna aleutica) that nests in scat- tered locations in coastal Alaska and presumably winters in the western North Pacific. Alevin — A young fish in which the egg sack has been absorbed. Algorithm — In computer science, a detailed logical process (or an analysis procedure) which generates the solution of a particular problem. Allele — Abbreviation for allelomorph; any one of the alter- native forms of a gene. A single gene may have several alternative forms, called multiple alleles. Allochthonous carbon — Carbon derived from outside the area or ecosystem being considered; the converse of auto- chthonous, which is carbon produced within a designated ecosystem. Allochthonous microorganisms — Foreign microorganisms that do not occupy the functional niches of that ecosystem. Amphiboreal — Occurring in the north temperate zones of the Atlantic and Pacific Oceans. Amphipoda — Small, laterally compressed crustaceans com- monly occurring in marine benthic and planktonic com- munities. There are also some freshwater and semi- ter restrial species. Anadromous fishes — Fishes that migrate from the sea to spawn in freshwater. Ancient murrelet — A small burrow- or crevice-nesting div- ing seabird (Alcidae, Synthliboramphm antiquus), with pre- cocious young, that nests throughout the Gulf of Alaska. 620 Glossary Anova — The abbreviation for 'analysis of variance', a statis- tical technique used to test whether two or more sample means could have been obtained from populations with the same parametric mean. Anoxic — Without oxygen; converse of oxic. Anticline — A geological term referring to a fold with strata sloping downward on both sides from a common crest. Anticyclone — An extensive system of winds spiraling out- ward from a high-pressure center, circling clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere. Apex carbon budget — Carbon budget taken to the top (apex) of the food chain. Apex predators — Predators located at the top of a food chain. Apparent oxygen utilization — The difference between the saturation oxygen concentration and the measured oxy- gen concentration; used as a measurement of respiration in the subsurface waters of the ocean. Aragonite pteropod test — The hard shell of certain species of free-swimming gastropod mollusk (Pteropoda; see pteropods). Aragonite is one of the two common crystal forms of calcium carbonate found in the marine environment. Arctic fox — Alopex lagopus, a small fox of open arctic habitats that was introduced by fox farmers on many islands in the Aleutian chain and western Gulf of Alaska. Arrowgrass — Triglochin sp., a grass-like wetland plant in the rush family that is a favorite food of geese. Artificially propagated salmon — Salmon that are produced from the egg to the smolt stage under the direct control of man, thereby reducing natural losses due to predation, disease, and physical factors. Aseismic — Pertaining to the property of a portion of the earth to be free of earthquakes. Aseismic front — The line or locus in subduction zones more or less parallel to the trench, at which the plate inter- face between the subducting and overriding plates has a transition from seismic-brittle behavior at depths shal- lower than about 40 km to aseismic (ductile) behavior at greater depths. Assimilation efficiency — The amount of energy retained by an organism divided by the amount consumed. Assimilative capacity — The capacity of a water body to receive, dilute, and carry away wastes without harming water quality. In the case of organic matter, it includes the capacity for chemical and biological oxidation. Asthenosphere — See mantle. Atmospheric input function — The rate (over time) at which a substance is added to the ocean from the atmosphere. Austral winter — Winter in the Southern Hemisphere. Autochthonous carbon — Carbon produced within a desig- nated ecosystem; the converse of allochthonous, which is carbon imported into the system. Average carbonaceous compound index (UAI) — A numer- ical descriptor of the ability of microbial populations in a community to utilize different classes of compounds; essentially identical to nutritional versatility index. Baleen whales — Whales of the suborder Mysticeti contain- ing a horn-like material (also known as whalebone) on their upper jaws that functions to filter food from the water. Unlike the toothed whales (suborder Odontoceti), which have one external blowhole, the baleen whales have two external blowholes. Baroclinic flow — A flow that exists where surfaces of uni- form density (isopycnal surfaces) are inclined to surfaces of uniform pressure (isobaric surfaces). This is the flow traditionally computed by the geostrophic method. Baroclinic wave — A wave in which the isopycnals follow a wave motion but the surface is relatively undisturbed (e.g., an internal wave). Barotropic flow — A flow where surfaces of uniform density and pressure are parallel. Such a system has the same speed and direction throughout the water column and usually must be measured. Bathylagids — Small fishes called deep-sea smelts (family Bathylagidae) which have an adipose fin, large eyes, and a small mouth. Bathymetry — The shape or relief of the ocean bottom, especially depth contours as obtained from a map or nau- tical chart. Bathythermograph — An instrument that provides a contin- uous trace of temperature versus depth, usually only in the upper 300-500 meters. The older instruments were mechanical devices that obtained data on a coated glass slide. The newer system uses expendable thermistors that transmit data by a thin wire to shipboard recorders. Beaked whales — Toothed whales (suborder Odontoceti) ranging in length from 4 to 13 m, whose jaws are more or less attenuated, forming a narrow beak. Bed-load — Pertains to the amount of solid material carried by moving water, such as a current, stream, or river. Benthic autotroph — An organism that dwells on the bottom of a river, lake, or ocean and assimilates energy from either sunlight (e.g., most plants) or inorganic compounds (e.g., sulfur bacteria). Glossary 621 Berg)' bits — Small chunks of ice, generally less than 5 m high, which have broken off from coastal glaciers. Bioavailability — The ability of a substance to be taken up and incorporated into the cells of an organism through ingestion, respiration, or absorption. Extrinsic factors that control bioavailability include the chemical nature of the substance, the amount of substance present, and the nature of the site at which the exposure occurs. Intrinsic factors include the organism's susceptibility to the sub- stance (i.e., rejected, accepted, or metabolized). Biogenic particle flux — The rate at which the biologically produced fraction of suspended particles settle to greater depths in the ocean. Black mat syndrome — A fungal disease affecting crabs. Blastocyst — The blastodermic vesicle; the blastula stage in early mammalian development which becomes the embrvo. Blue mussel — A common intertidal bivalve mollusk (Mytilus edulis) that attaches to the substrate with short, filamen- tous 'byssal threads'. Bolus — An approximately spherical mass of water, often with physical characteristics (e.g., salinity, temperature) which distinguish it from the surrounding water mass. Boreal fauna — Animals that inhabit the north temperate zone. Bottom drifter — A device, often a bottle or plastic card, which is designed to drift in the bottom several meters of the water column. Boundary current — A current which occurs on the periph- ery of a large-scale circulation system such as the sub- arctic gyre. Box model — A method of describing mass flow or flux of constituents within a system by defining homogeneous sub-compartments or 'boxes'. Brittle(geophysical) — The sudden localized loss of shear strength in an otherwise elastic solid material. Browser — An animal that feeds on the shoots, twigs, and leaves of trees and shrubs or, in the marine environment, on algae. Bubble net feeding — A feeding method observed in humpback whales in which a chain of bubbles is blown as the whale swims in a circular pattern, causing food (e.g., euphausiids) to mass in the center of the ring. The whale then rises to feed in the resulting concentration. Bubble-phase gas — A volatile material trapped in sedi- ments or rock in the form of clatherates or liquids that has formed a small globule of gas trapped in the liquid or solid medium. By-catch — Species of fish caught incidentally in the fish- eries for other species; also called 'incidental catch'. Cackling Canada goose — Brant a canadensis minima, a small subspecies of Canada goose that nests in western Alaska and stages in Cook Inlet during spring migration. Calanoid copepod — Member of the crustacean class Copepoda, order Calanoida; often the most common taxon of small crustacean comprising the marine zoo- plankton community. Canadian Ocean Weather Station T' — The site in the North Pacific (5()°N, 145°W) of weather and oceanographic monitoring since the early 1950s. Capelin — Mallotus villosus, an abundant, small schooling smelt (family Osmeridae) that is an important prey of sev- eral kinds of fish, marine mammals, and seabirds throughout coastal Alaska. Carrying capacity — The maximum number or weight of individuals in a species which can be maintained in a hab- itat without depletion of food or other ecological factors. Catch per unit effort (CPUE) — A statistic, based on catches taken per unit of fishing effort, which is sometimes used to estimate the relative abundance of a species. Central Subarctic Domain — One of the water masses identi- fied by Dodimead et al. (1963) and typical of much of the eastern Gulf of Alaska. Cephalopods — The molluscan taxon comprising the squids and octopuses. Chaetognaths — Small, torpedo-shaped carnivorous inver- tebrates of the phylum Chaetognatha, often termed 'arrow worms'. Chinook salmon (Oncorhynchus tshawytscha) — A common name for the largest of the salmon species of the genus Oncorhynchus; also called king, quinnat, or tyee. Chlorophyll a — A pigment, found in all plant chloroplasts, that absorbs visible light as the first step in photosynthesis. Chlorophyll degradation products — A multiplicity of prod- ucts formed when chlorophyll is decomposed. Choanocyte — Collar cell; a type of cell peculiar to sponges. The cells form an epithelium in certain chambers and passages through the sponge; each cell has a funnel- shaped, mucus covered, gelatinous collar and a single flagellum originating from the cell in the center of the collar. Choanoflagellates — Small (<5 urn) phytoplankton charac- terized by the presence of a collar-like structure at the base of the associated flagella. Chum salmon — A common name for fish of the salmon spe- cies Onrorhyttfhus keta, which is also known as dog salmon. Cladocerans — Small crustaceans of the suborder Cladocera, most commonly occurring in freshwater, but with repre- sentatives in coastal marine waters. 622 Glossary Oast — A fragment of a detrital (or clastic) rock, often used as a synonym for a inegaclast, a larger clastic particle within a rock of prevailing finer grain. Cloud streets — Approximately parallel lines or streaks of clouds with clear spaces in between and with width scales from 1 or 2 km to 20 kilometers. Clouds are organized into these lines by instabilities in the atmospheric boundary layer. Cluster analysis — A process of classifying or grouping vari- ables, subjects, or sampling units by combining similar units to form small classes, then combining small classes into larger classes, and so on. Clutch — The number of eggs laid by a female bird during one nesting attempt. Cnidaria — A phylum containing the jellyfishes, sea anemo- nes, and corals; also called Coelenterata. Coastal wind jets — Winds along mountainous coastlines that, in adjusting to the inability to flow through a moun- tain wall, turn from their offshore geostrophic orienta- tion to a new direction aligned closer to the direction of the pressure gradient and to a new speed that allows for the conservation of mass and momentum for the onshore flowing air mass. Coastal Zone Management Act of 1972 (P.L. 92-583, 16 U.S.C. sec. 1451 et seq.) — This law defines the national pol- icy concerning the nation's coastal zone by declaring that it is in the nation's interest to preserve, protect, develop, and, where possible, to restore or enhance the resources of the coastal zone. It also promotes federal-state cooper- ation in matters concerning the coastal zone and the establishment and implementation of state coastal zone management programs. Coccolithophores — A family of planktonic dinoflagellates characterized by an external covering of calcareous plates. Coherence — The existence of a correlation between the phases of two or more phenomena, so that coupling or interference effects may be produced between them. Commercial extinction — In the context of fisheries, a spe- cies or stock reduced to such small numbers that it no longer makes an economic contribution to the fishery. Community composition — The species of organisms mak- ing up a biological assemblage at a given time and location. Compensation light intensity (Ic) — The light intensity at which the rates of photosynthesis and respiration are equal. Competitive exclusion — A situation resulting when one individual or species uses or defends a resource to the extent that the resource becomes unavailable to other individuals or species. Conservative constituent or parameter — A constituent or parameter whose concentration or value may be affected by mixing of different water masses, but not by physical- chemical reactions or biological processes. Conservative tracer — A material whose concentration in seawater is not changed by chemical or biological processes. Consumption rate — The amount of prey ingested by an organism in a given period of time. Convergence — Act of approaching the same point from dif- ferent directions; see also plate tectonics and downwelling. Copepod nauplii — The first stage after hatching in the development of copepod crustaceans from eggs to adults. Copiotrophs — Microorganisms that grow at high nutrient concentrations. Coralline algae — Calcareous red algae of the family Corallinaceae. Coriolis Force — The deflecting force of the earth's rotation; a fictitious force used mathematically to describe motion relative to a noninertial, uniformly rotating frame of ref- erence such as the earth. Cosmogenic — Originating in space or in the upper regions of the earth's atmosphere. Council on Environmental Quality — A three-person coun- cil of experts created in the Executive Office of the Presi- dent under Title II of the National Environmental Policy Act of 1969 (NEPA, 42 U.S.C. 4332 et seq.) to assist and advise the President. Crested auklet — A small plankton-feeding alcid {Aethia cristatella) common to the Bering Sea and Aleutian Islands. Critical depth (Zcr) — The maximum depth of surface water mixing that will sustain net water column photosynthesis. Crust — The outer rocky layers of the earth with seismic P-wave velocities less than about 8 km/s. Oceanic crust is usually less than 10 km thick; continental crust is typically between 20 and 40 km thick. CTD stations — Sampling, at discrete sites, with continuous profiling devices that electronically sense conductivity, temperature, and depth. Ctenophores — Small jelly-like forms of the phylum Ctenophora, distinguished from the true jellyfishes (phy- lum Cnidaria) by having eight rows of swimming cilia and two tentacles. Cyclonic gyre — An air or water mass that circulates coun- terclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. Glossary 623 DDT — Dichlorodiphenyltrichloroethane; a chlorinated hydrocarbon that has been widely used as a pesticide. Due to its toxicity to a variety of non- target organisms, and to its mobility and persistence in the environment, use of DDT is now tightly controlled in the United States and many other countries. Decapods — Members of the crustacean order Decapoda, including shrimps and crabs. Deep sections — Cross sections of vertical properties (e.g., temperature, salinity) at ocean depths greater than 1,000 meters. Demersal fishes — Bottom-dwelling fishes. Dendrogram — A diagram showing the relationships pro- duced by a hierarchical classification; that is, a classifica- tion in which the classes are ranked such that every unit belongs to a class, and every class to a higher-ranking class, up to the highest class, which is the totality of all units. Denitrification — The conversion of fixed forms of nitrogen, such as nitrate ions, to atmospheric nitrogen (N<>). Density gradient — The change in density per unit horizon- tal (or vertical) distance. Density slope — The slope (change in depth divided by dis- tance) of a constant-density surface. Detrital food chain — A food chain based on the consump- tion of detritus (i.e., particulate organic debris). Diagenesis — Changes that take place in the conversion of a sediment to a rock, and the processes that bring about these changes. Delta I3C— Three common forms of carbon are found in the atmosphere — 12C, 13C, and 14C. Marine primary pro- ducers have a less negative ratio of ^C/^C than do ter- restrial primary producers. Therefore, the tissues of ani- mals which prey on marine primary producers should also have a less negative ratio. The unit of A13C has been developed as a means of discriminating very small dif- ferences between two large numbers. A„c = 13C/12C Sample _ j x 1 000 13C/12C Standard Diamict sediment — Sediment consisting of particles of two classes or modes; usually large clasts in a finer-grained matrix. Differential Ekman pumping — An effect of spatial varia- tions in local wind-stress curl that results in horizontal differences in vertical velocity. These differences in ver- tical velocity cause changes in the depth of density sur- faces that change geopotential anomaly and geostrophic flow. Dinoflagellate resting cysts — Typically, a part of the life cycle of coastal marine dinoflagellates that allows them to survive periods unfavorable for growth. Dipteran larvae — Worm-like immature stage in the life cycle of flies of the insect order Diptera. Direct count — A method for enumerating microorganisms based upon direct microscopic observation, often after staining with a fluorescent dye such as acridine orange. Diversity index — A numerical descriptor that reflects the number of different species and their relative abun- dances within a community. Double-crested cormorant — A large, diving, fish-eating seabird (Phalacrocoracidae, Pliakicrocorax auritus) that has two small crests on its head during the breeding season. Downwelling — Vertical sinking of upper ocean layers which may result from either convergence of ocean currents or increased water levels along the coast owing to wind stress; opposite of upwelling. Drag (transfer) coefficient — When momentum is trans- ferred from the atmosphere to the earth's surface, a drag force per unit area (stress) is exerted on the surface. The drag coefficient is a convenient, dimensionless number that relates the momentum transfer (stress) to the nearsur- face wind speed. Drogued drifter — A device used to follow ocean currents, consisting of a surface float connected to a subsurface drogue (parachute, panel, or vane) used to couple the assembly to the subsurface current. Ductile — Pertaining to the plastic, flow-like deformation of materials without breaking. Dusky Canada goose — Branta canadensis occidentalis, a dark subspecies of Canada goose that nests exclusively on the Copper River Delta. Dynamic centimeters — A unit used for computing values of geopotential anomaly. It is derived from the vertical (pres- sure) integral of specific volume anomaly and equals 10 ergs per gram. It is approximately equivalent to 0.98 lin- ear centimeters. Eared seal — A member of the pinniped family Otariidae (fur seals and sea lions) that has rolled-up external pinnae (ears). Earthquake — The sudden shear failure of a stressed elas- tic-brittle portion of the earth. Earthquakes are the man- ifestation of a dynamic slip on a fault that radiates seismic waves. Ecological efficiency — A ratio: the amount of energy extracted from a lower trophic level by an upper level. divided by the amount of energy supplied to the lower level. 624 Glossary Eddy heat flux — A flux or transfer of heat resulting from correlated deviations of current and temperature. Eddy kinetic energy — Energy per unit mass at frequencies higher than the mean of net flow; determined hy comput- ing the variance of velocity, and taking one half of it over the record length. Ekman transport — Wind stress (or drag) on the ocean sur- face produces motion in the upper, mixed layer of the ocean (usually between 10 and 100 m deep). This oceanic response to the wind is termed Ekman transport. El Nino — An intermittent event (typically every 3-7 years) of about one year's duration that produces marked warm- ing of upper ocean waters in the central and eastern equa- torial Pacific. The events may interrelate with atmo- spheric systems globally, and they may affect temperature and sea level along the eastern Pacific margin as far north as the Gulf of Alaska. Elastic (geophysical) — The behavior of solid matter in which stresses and strains relate linearly to each other. Emery and Hamilton pressure index — An index that com- pares winter mean pressure south of the Aleutian Islands to that over coastal California (pressure at 40°N, 120°W minus the pressure at 50°N, 170° W; Emery and Hamilton, 1985). High values of the index correspond to low relative pressure near the Aleutians, which relates to more intense and/or frequent cyclone activity in the Gulf of Alaska. Emperor goose — A medium-sized goose {Chen canagica) that nests in western Alaska and is the only abundant goose that winters in Alaska. Endangered Species Act (of 1973) (P.L. 93-205, 16 U.S.C. 1531 et seq.) — This act provides for the conservation of endangered and threatened species of fish, wildlife, and plants. Endogenous — Originating within the organism. Engelmann diagram — A schematic illustration showing relationships between costs and margins of safety in a project. Environmental degradation — A change in the environment that is harmful to the environmental systems or aesthet- ically displeasing to a majority of people. Environmental hazards — Those elements in the physical environment harmful to man and caused by forces extra- neous to him. Epibenthos — Organisms occurring on (but seldom in) the sea floor. Epicenter — Position of the nucleation point of an earth- quake projected on the earth's surface. Its coordinates are given by geographic latitude and longitude. Epipelagic zone — The surface layer of the ocean where pho- tosynthesis and seasonal changes in temperature and sali- nity occur; the upper 200 meters. Equitability index (J') — A measure of diversity that describes the evenness of distribution of species within the community. Errantiates — A classificatory grouping of polychaete worms that includes free-living species. Eulachon — Thaleicthys pacificus, a species of smelt (family Osmeridae), commonly called candlefish, that is an important prey species for several kinds of fish and sea birds throughout coastal Alaska. Euphausiids — Small, active, shrimp-like crustaceans of the order Euphausiacea. Euphotic zone — The uppermost layer of a body of water receiving sufficient light for photosynthesis. Euryhaline — Able to tolerate wide fluctuations in salinity. Eutrophic — A description of relative water column produc- tivity referring to the most productive of conditions. Exceedence probability — The probability that a given level of ground motion, expressed as a given parameter (e.g., ground acceleration), will not be exceeded within the period of interest. Exclosure — An area from which intruders (e.g., predators) are excluded, especially by fencing. Exclusive economic zone (EEZ) — The contiguous zone extending offshore 200 nmi from the United States and its territories, proclaimed by President Reagan on March 10, 1983. The intent of the proclamation was to set forth the United States' sovereign rights to the mineral resources of the zone. Extreme wave height — In oceanography, an empirical esti- mate equaling 1.8 times the average height of the highest one-third of all observed waves. Fastidious — Term used to describe microorganisms that grow only under very restricted nutritional and environ- mental conditions. Fault — An internal surface in the earth's crust across which repeated slip has occurred. A normal fault occurs when the hanging (upper) wall has apparently moved down with respect to the foot (lower) wall. A thrust or reverse fault occurs when the hanging wall has apparently moved up relative to the foot wall. Fault plane — A plane that contains the surface of slippage during an earthquake. One of the two orthogonal nodal planes in the P-wave radiation pattern of an earthquake coincides with the fault plane. Glossary 625 Fecal pellets — Particles voided from an animal's digestive tract; often discussed with respect to zooplankton {e.g., copepods). Fecundity — The potential reproductive capacity as meas- ured by an individual's production of young. Federal Water Pollution Control Act of 1972 (FWPCA) (33 U.S.C. 1251 et seq.) — This act sets forth policy concerning the restoration and maintenance of the quality of the nation's navigable waters and the elimination of dis- charges of pollutants into the waters. Fetch — The distance the wind has blown over a surface. Five hundred millibar height — The height above mean sea level of the 500 nib constant pressure surface, typically near 5.5 km altitude. Since the average surface pressure is ~ 1,000 nib, about half of the mass of the atmosphere is above this height and half is below. At mid-latitudes this is the approximate height of the winds that steer the motion of the large high and low atmospheric pressure systems. Fjord — A deep (and frequently long, narrow, and steep- sided), high-latitude estuary excavated or modified by land-based ice; usually, but not necessarily, bounded sea- wards by a sill. Flagellate — Members of the protozoan subphylum Mas- tigophora, which possess one or more filiform appen- dages (flagella) as adult locomotor organelles. Fledging success — The proportion of young birds that suc- cessfully leave the nest relative to the number of young that hatch. Flick feeding — A feeding method observed in humpback whales in which the flukes are suddenly flexed forward, creating a wave that concentrates planktonic food. Fluorometer — An instrument that can detect the presence of fluorescent materials; most commonly used in oceanography to measure the concentration of chlo- rophyll in seawater. Fluorometry — An analytical technique in which the stimu- lated emission of light from a substance (usually in solu- tion) is measured. Fluvial — Pertaining to, or inhabiting, a river or stream formed by action of flowing water. Food chain — The theoretical flow of energy from plants through a series of other organisms; members of each link in the chain feed upon the members of the one below and are consumed by the members of the one above. Free sulfide — Uncombined sulfide ions often present under anaerobic conditions in marine waters. Freshet — Freshwater snow-melt discharge, usually in the spring. Frontal systems — Ocean areas in which relatively sharp horizontal gradients in properties are found, usually asso- ciated with temperature or salinity. Frustulcs — The two siliceous plates that enclose a diatom; composed mainly of silica. Fugitive species — A species adapted to colonize newly dis- turbed habitats. A fugitive species often has a life history characterized by short life span, short development time to reach maturity, and many reproductive periods per year. Fulvic acid — A functionally defined fraction of humic mate- rial soluble at low pH values (see humic acid). Gadwall — Anas strepera, a species of duck that nests in wet- lands bordering the Gulf of Alaska. GAK line — Acronym for Gulf of Alaska. The GAK line is a series of oceanographic stations transecting the continen- tal shelf from a point at the mouth of Resurrection Bay. This series of stations has been monitored at irregular intervals since 1970 by scientists at the Institute of Marine Science, University of Alaska. Gap winds — Air motion from an area of higher pressure to an area of lower pressure through a region restricted by the terrain. Genotype — The genetic constitution of an individual, with- out regard to its outward appearance (phenotype). Geopotential anomaly — For a mass of water at a given pres- sure, the difference between the depth of the water mass as calculated from its potential energy and the actual geo- metric depth of the water mass; most often used to infer the direction of water movement at different depths in the ocean. GEOSECS — An acronym for geochemical ocean sections, a large multi-institutional program, supported by the National Science Foundation, that conducted a coordi- nated mapping of chemical concentrations in the world's oceans during the period from 1972 to 1977. Geostrophic flow — Flow that assumes a balance between the pressure gradient and deflective or Coriolis forces in the equation of motion. This is the component of flow com- puted from geopotential anomalies derived from hydro- graphic casts. Geostrophic relation — An assumption that pressure gra- dients and the earth's deflective forces balance locally; used to compute geostrophic flow. Geostrophic winds — Air flow that is necessarv to balance the force of a pressure gradient and the effects of a uni- formly rotating reference frame (see Coriolis force). The geostrophic wind is always parallel to contours of con- stant pressure (isobars) and has a magnitude inversely proportional to the distance between adjacent isobars. 626 Glossary Geothermal energy — Energy available from heated vapors or water from sources beneath the earth's surface. In Alaska, many potential geothermal energy sources are associated with volcanoes and volcano-like features. Gill net — A fixed vertical net, having the head rope buoyed and the bottom rope weighted, in the meshes of which fish become entangled by their gill covers. Set gill nets have one end anchored to shore; drift gill nets float free in the water. Glacial-fluvial sediments — Pertaining to sediments derived from or associated with glaciers. Glaucous-winged gull — A large seabird {Larus glaucescens) that nests in the Gulf of Alaska. Gonatid squid — Any of several species of abundant oceanic squids of the family Gonatidae. Graben — An unusually elongated depression of the earth's crust between two parallel faults. Gram-negative bacteria — Bacteria with a complex cell wall containing murein and an envelope containing lipopolysaccharides; bacteria that decolorize and there- fore appear pink using the Gram stain procedure. Gyre — A very large-scale ocean circulation system whose currents impart a tendency to clockwise or counterclock- wise rotation. The Pacific subarctic gyre has a coun- terclockwise rotational tendency. Half-saturation constant — Term applicable to uptake of a limiting nutrient by an organism; the concentration of the limiting nutrient when the uptake rate is half of the maximum rate observed for that particular organism and nutrient. Halocline — Region of maximum change of salinity per unit depth. Harpacticoid copepods — Small benthic copepods of the order Harpacticoida. Hatching success— The percent of eggs that hatch relative to the number laid. Haulouts — Areas where marine mammals rest on a beach. Hematopoietic necrosis — A disease condition evidenced by bloody, dead tissue. Hemolymph — The nutritive circulatory fluid, similar to blood or lymph, of invertebrates. Herbivorous grazing — Selective consumption of plants; often used to designate consumption of phytoplankton by herbivores, mainly zooplankton. Heterotrophic activity — A measure of relative bacterial pro- ductivity, based upon the uptake of radioactive isotope- labeled organic compounds. Hippolytid shrimp — Any of several species of shrimp in the family Hippolytidae. Holoplankton — Organisms that are a permanent compo- nent of the zooplankton community. Horizontal divergence — Movement, in a horizontal plane, away from a common point. Hot spot — The spot-like locus of persistent upwelling of mantle-derived magma. Humic acid — A functional fraction of humic material solu- ble at high pH, but which precipitates on acidification (see fulvic acid). Humic substances — High molecular weight, acidic organic polymers containing active hydrophilic phenolic and oxylic groups; generally resistant to chemical and micro- biological degradation. Hybridize — The sexual crossing of genetically dissimilar individuals. Hydrocarbon degraders — Microorganisms capable of meta- bolizing hydrocarbons. Hydrocast — A vertical sampling of oceanic water at a fixed site. Until the development of CTD sensors, hydrocasts were made by lowering bottles (with reversing ther- mometers) on a wire to obtain temperatures and samples for analyses of salinity and other properties. Hydrographic time series — A time series of any oceanographic property (at discrete depths or continu- ous in the vertical) at a fixed site. Hydromedusae — The free-swimming medusoid forms of some species of hydroids (phylum Cnidaria, class Hydrozoa). Hypocenter — Position (depth, latitude, longitude) of the nucleation point of an earthquake. Ice scour — Removal of attached organisms by moving ice. Ichthyoplankton — The eggs or larval stages offish that drift or swim weakly in the water column. Imbricate — In structural geology, pertaining to the shin- gling arrangement of thrust faults that form thrust belts with inclined stacks of thrust sheets. Incubation period — The period in the reproductive cycle of egg laying animals which occurs after egg laying and before hatching. Interception fishery — A fishery that catches fish in migratory paths; often refers to salmon caught as they return to their home streams to spawn. Glossary 627 International North Pacific Fisheries Commission (INPFC) — A research and coordinating body, composed of representatives from the United States, Canada, and Japan, which establishes management measures to con- serve stocks of fishes in the North Pacific Ocean. The com- mission sponsors relevant fisheries research and pub- lishes the results in the INPFC Bulletin. International Pacific Halibut Commission (IPHC) — Formed in 1923 with the United States and Canada as the onlv members, this body carries out research and estab- lishes the management measures under which halibut catches by the two countries are regulated. International Pacific Salmon Fisheries Commission (IPSFC) — Created by treaty in 1937, the goal of the com- mission is the restoration of the Fraser River sockeye salmon runs and equal division of catches between Cana- dian and United States fishermen. International Whaling Commission (IWC) — This commis- sion was established in accordance with the International Convention for the Regulation of Whaling, which entered into force in 1948. The commission is responsible for amending the regulations that govern the conduct of whaling by the contracting governments. Interstitial water — Water occurring in the interstices between particles. Isochron — A line or contour of constant age. Isohaline — A surface of constant salinity. Isopycnal surface — A surface of constant densitv. Isotopic fractionation — Small separations between the iso- topes of an element that occur during chemical and bio- logical processes. Jacks — Members of the fish family Carangidae; also sexually precocious male salmon. Katabatic winds — Winds that flow down slopes that are cooled by radiation, the direction of the flow being con- trolled almost entirely by orographical features. Killer whale — Orcinus orca, toothed whales with tall, wide dorsal fins and bodv length up to 9.5 meters. Kinematics — In fluid dynamics, the characteristics of differ- ent kinds of pure motion; that is, without reference to mass or the causes of motion. Kuroshio water — Water resulting from the continuation of the Kuroshio Current into the western North Pacific. Larvaceans — Small, free-swimming members of the sub- phylum Urochordata (Tunicata), which feed primarily by filtering particulate matter from seawater. Latent heat flux — The quantity of heat transferred between the earth's surface and the atmosphere through evaporation. Leachates — Liquids that have percolated through a medium and have extracted dissolved or suspended mate- rials from it. Lead-210 (or -l0Pb) analysis — Lead-210 is an unstable, alpha-emitting product of U-234 with a half-life of 21.4 years. Lead-210 measurements may be used to determine either the age of sediments or sedimentation rates. Leopold matrix — A tabulated arrangement of a set of possi- ble developmental actions with a set of potentially impacted indicators, sometimes used as an environmen- tal assessment technique. Lesser Canada goose — Branta canadensis parvipes, a sub- species of Canada goose that nests in southcentral and interior Alaska. Light extinction coefficient — The proportion of light absorbed per meter in water. This varies from 0.04/m in the clearest ocean water to 0.4/m or more in very turbid water. Light saturation — That amount of light beyond which there is no increase in productivity by plants. Limpet — Any of several species of dorso-ventrally com- pressed (Chinese hat shaped) gastropod mollusks which hold tightly to rocks. Lipid reserves — Special triglycerides that many zoo- plankton store for use as energy reserves during times of food shortage {i.e., winter). Liquefaction — The property of unconsolidated sediments to lose their shear strength during shaking, rendering them capable of flowing like a liquid. Listric — Pertaining to the orientation of faults whose dip angles decrease with depth. Lithosphere — The outer shell of the earth that maintains relatively high rigidity and integrity of matter during tec- tonic processes. Its thickness can measure a few tens of km for young oceanic lithosphere and in excess of 100 km for old continental lithosphere. The lithosphere contains both brittle crust and the partly seismogenic and partly ductile (but strong) portions of the upper mantle. Litter — Scattered rubbish; considered herein to consist of materials discarded by man. Littoral zone — The expanse of shoreline between high and low tides. 628 Glossary Longline — A long, negatively buoyant fishing line, having many short subsidiary lines attached to it, each with one or more baited hooks. Longlines may extend for several miles. Loon — Anv of four species of large, fish-eating birds (Gaviidae) that nest primarily on freshwater and winter at sea. Lumpfish — A group of small- and medium-sized fishes of the family Cyclopteridae. Lunge feeding — A feeding method observed in humpback whales in which the animals lunge forward with their mouths open to collect food. Lymphocystis — A viral disease that affects flatfish. Maximum sustainable yield — The largest annual commer- cial and sport catch, in terms of weight offish, that can be taken continuously from a stock under existing environ- mental conditions. Mean kinetic energy — Energy per unit mass associated with the mean or net flow; proportional to one-half the prod- uct of its mass and the square of its speed. Mechanistic approach — Involving the study of the proc- esses underlying the organization of natural communities. Medusae — Bell-shaped, usually free-swimming forms of many members of the classes Hydrozoa and Scyphozoa of the phylum Cnidaria. Megazooplankton — Zooplankton larger than 1.0 cen- timeter. Macrofauna— Fauna (animals) larger than 0.5 millimeters. Meiofauna —Fauna in the size range 0.05 to 0.5 millimeters. Macrophages detritivore — An organism that feeds on rela- tively large particles of freshly dead or partially decom- posed organic matter. Macrophyte — An individual plant large enough to be seen easily with the unaided eye. In marine biology, this term is often used to refer to the large kelp species which are abundant in northern coastal waters. Macrozooplankton — Zooplankton large enough to be retained by a net with 183 tim mesh. Magnitude — A logarithmic measure of the source size and source strength of an earthquake, usually inferred from quantities that can be measured on seismograms. Magnuson Fishery Conservation and Management Act of 1976 (16 U.S.C. 1801 et seq.)— This law established the United States' 200-nmi fisheries conservation zone, and created eight regional fisheries management councils to regulate the take of fish within their geographic areas of concern. Mantle — The ~ 2,800-km thick, compositionally dense por- tion of the earth that lies between the less dense crust and the much denser liquid core of the earth. Relatively rigid portions of the upper mantle are part of, and move with, the plate-like lithosphere, which overlies the weak ductile asthenosphere, which in turn overlies the lower mantle at depths beneath about 650 kilometers. The lower mantle is sometimes also referred to as mesosphere. Marbled murrelet — A small, coastal alcid (Brachyramphus marrtwratus) usually seen in pairs. Marine Protection, Research, and Sanctuaries Act of 1972 (33 U.S.C. 1401 et seq.) — This act prohibits unregulated dumping of material into ocean waters, and requires per- mits for the dumping of dredged materials. Meroplankton — Organisms that are only temporary mem- bers of a zooplankton community. Mesosphere — See mantle. Metabolic rate — The rate at which an animal chemically converts food into body tissues, carbon dioxide, and waste products. Metacentric height — The distance of the metacenter above the center of gravity of a floating body. Metacenter is the point of intersection of a vertical line through the center of buoyancy of a floating body and a vertical line through the new center of buoyancy when the body is modified or displaced. Microaerophilic marine environments — Regions of reduced oxygen tensions where microorganisms that require oxygen, but are also sensitive to it, can live. Microflora — Plants or bacteria smaller than 50 microns (0.05 mm). Micronekton — Small, free-swimming animals that have the ability to swim against weak vertical and horizontal currents. Microzooplankton — Zooplankton smaller than 183 microns (0.183 mm). Milt — The mass of sperm released by a male fish. Mineralization — The conversion of organic matter to inorganic compounds such as carbon dioxide and water. Mitigation — A system of programmatic measures to reduce or minimize the damaging effects from an unwanted occurrence. Mixed layer depth (MLD) — The depth of surface wind-mix- ing, usually taken as the depth at which a significant tem- perature change from the surface value takes place. Glossary 629 Mixed-stock fishery — A fishery in which different stocks of the same fish species are taken. Mixing rates — The rate at which water masses are mixed with each other by physical processes such as diffusion or tidal flow. Mysids — Small shrimp-like crustaceans of the order Mysidacea, distinguished from euphausiids hy the pres- ence of a small balancing organ", or statocyst. Mysticetes — See baleen whales. Naked flagellates — Small (<5 microns) planktonic cells pos- sessing at least one flagellum, but without any hard cover- ing such as coccolithophorids or silicoflagellates have. Nanoplankton — Plankton in the size range of 5 to 20 microns (0.005 to 0.02 mm). National Environmental Policy Act of 1969 (P.L. 91-190, 42 U.S.C., 4321 et seq.) — This act promotes efforts to prevent or eliminate damage to the environment. National Pollutant Discharge Elimination System (NPDES) — Embodied in subsection 1342 of the Federal Water Pollution Control Act of 1972, NPDES sets out guidelines which control the discharge of pollutants into navigable waters. NEGOA — An acronym for the northeast Gulf of Alaska, used mostly in connection with OCSEAP studies of the region of the North Pacific King on the continental shelf between Hinchinbrook Island and Yakutat Bay. Nepheloid layer — A layer in a liquid containing large amounts of suspended particles; usually found in the ocean where near-bottom turbulence is sufficient to maintain a layer of suspended sediments. Nephelometer — An instrument used to measure the trans- mission of light through a water sample. Its main applica- tion is in estimating the concentration of suspended par- ticles in seawater. Nereid polychaetes — Segmented benthic marine worms of the genus Nereis (phvlum Annelida, class Polychaeta) that produce a sexually ripe swimming stage for reproduction. Neritic species — Marine forms that are found in nearshore habitats. Net photosynthesis — The organic matter produced by plants after adjusting gross photosynthesis for losses due to respiration. New nutrients — Exogenous nutrient supply for phy- toplankton production; contrasted with regenerated sup- ply from in situ consumption and degradation. New production — Phytoplankton fixation of carbon based on the use of NO., as the nitrogen source. When nitrogen in the form of Nil ,+ is used, this is considered re< \< ling. since NH,+ is only present when fixed carbon is being consumed and regenerated bv respiring organisms. Nitrogen fixation — The conversion of atmospheric nitro- gen (N.,) to fixed forms of nitrogen, such as ammonium ions. Nitrogen-15 (lr'N) — A heavy isotope of nitrogen that can be used as a tracer in studies of marine productivity. NO — A computed chemical parameter (9 x nitrate con- centration plus the dissolved oxygen concentration) that is conservative if Redfield stoic biometry is approximated. Nodal plane — A theoretical plane through a seismic source that contains directions in which the radiation pattern for a specified type of seismic wave has zero amplitude; see also fault plane. Nomogram — A graphical representation of numerical rela- tionships among three or more variables. Non-point source — Any unconfined area from which pol- lutants are discharged. Nanoplanktonic heterotrophic flagellates — Very small non-photosynthetic flagellates that occur within plank- tonic communities. Normal fault — See fault. NORPAC — Acronym for North Pacific; an informally organized group of scientists responsible for collating and publishing much of the oceanographic data collected in the North Pacific Ocean during the period of approx- imately 1930 to 1965. These data were published in several volumes by the University of California Press. This data set is collectively known as the NORPAC data. North Pacific oscillation index — A measure of the dif- ference in mean winter air temperature anomalies between St. Paul Island in the southern Bering Sea and Edmonton, Canada. An intensified Aleutian low pressure area in the eastern North Pacific occurs when there is a cold anomaly in winter temperatures at St. Paul and a warm anomaly at Edmonton. Nuee ardente — In volcanology, an extremely hot gaseous cloud of volcanic ash released during an explosive erup- tion; may flow downslope like an avalanche at high speeds. Numerical taxonomy — An approach used for classifying organisms based upon sets of phenotypic characteristics rather than upon a hierarchical scheme. Nutricline — Region of maximum change in a nutrient with depth. 630 Glossary Nutrient mass balance — A quantitative measurement of the amount of nutrients in a system; it involves computing the amount in organic form (biomass), inorganic form, and supply through advection or diffusion; a method recently used to estimate primary production. Nutritional versatility index — A numerical descriptor of the ability of microbial populations in a community to utilize different classes of compounds, a property presumably related to the substrates that are naturally available. Sepa- rate indices are calculated for different classes of sub- strates; the indices have a scale of 0 to 1 and are calculated by determining the proportions of representative micro- organisms that can grow on various individual substrates within each class of compounds. Ocean Weather Station T' — See Canadian Ocean Weather Station T\ OCSEAP — An acronym for the Outer Continental Shelf Environmental Assessment Program. OCSEAP is an Alas- kan research program managed by the National Oceanic and Atmospheric Administration and funded by the Min- erals Management Service of the Department of Interior. Odontocetes — Dolphins, porpoises and whales of the sub- order Odontoceti that have teeth but no baleen, and a sin- gle external blowhole. Oligotrophs — Microorganisms that grow at low nutrient concentrations. Ontogeny — Developmental history of an organism from zygote to maturity. Open-access resource — A resource that is not owned. Optimum yield — In the context of the United States fish- eries policy, the amount offish that will provide the great- est overall benefit to the United States; prescribed on the basis of maximum sustainable yield for a fishery as modi- fied by any relevant ecological, economic, or social factors. Orography — Study of the physical geography of mountains and mountain ranges. Osteichthyes — The class to which bony fishes belong. Ostracods — Small marine crustaceans of the class Ostracoda which possess a bivalved carapace (shells) that partially encloses the body. Ovovivparous — Producing eggs that hatch within the body of the female. Oxygen minimum — Those depths in the ocean where the oxygen concentration is less than that at both shallower and greater depths. In the Gulf of Alaska, the oxygen min- imum generally occurs at a depth of about 1,000 meters. P/B ratio — Ratio of production to biomass. Pacific intermediate water — That mass of water typically occurring at depths of 200 to 800 m in the North Pacific Ocean which formed as a result of the cooling of surface waters along the coast of the U.S.S.R. during winter months. Pandalid shrimp — Any of several species of shrimp of the genus Pandalus (order Decapoda) that are highly sought in commercial fisheries in Alaska. Papillomatosis — A viral disease resulting in formation of benign tumors. Paralytic shellfish poisoning (PSP) — A human pathological condition caused by the ingestion of shellfish that have previously accumulated toxins from dinoflagellates in the surrounding water. While apparently not harmful to the shellfish, these toxins can cause death by respiratory failure in mammals. Particulate flux — The rate of sinking of particulate material from the surface waters of the ocean. Patchiness — Variability (in space and/or time) of biological populations. Pathogen — A microorganism that causes disease. Pathogenicity test — A test conducted to determine whether a particular microorganism causes a specific disease condition. Peak uptake — The maximum utilization of nutrients, especially nitrogen, by phytoplankton during photosynthesis. Pelagic — Free-living in the water column. Pelagic amphipods — Amphipods that complete their life histories entirely in the water column. Pheopigments (or phaeopigments)- chlorophyll (e.g., via acidification). -Degraded forms of Photosynthesis — The conversion of light energy to chem- ical energy during the synthesis of organic material by plants. Physiological tolerance index (P) — A numerical descriptor of the ability of microbial populations in a community to tolerate deviations in particular environmental param- eters such as variations of temperature and salinity from ambient conditions at the time of sampling. Separate indices are calculated for different environmental fac- tors; the indices have a scale of 0 to 1 and are calculated by determining the proportions of representative micro- organisms that can grow under various fixed conditions. Phytodetritus — Detritus derived from plants. Phytoplankton — Typically, microscopic, single-celled plants that grow in surface waters. Glossary 631 Piedmont glacier — A glacier formed by the coalescence of two or more valley glaciers behind the base of a steep slope. Pigment budget — A method to measure phytoplankton growth and sinking and grazing losses based on plant pig- ment changes in the surface layer and the rate of pigment deposition in subsurface traps. Pink Salmon — A common name for fish of the salmon spe- cies Oncorhynchus gorbuscha, which are also known as humpy or humpback salmon. Pioneer species — See fugitive species. Piscivorous — Fish-eating. Planktivorous — Plankton-eating. Plantigrade — The young postlarva of the bivalve molluscan family Mytilidae (mussels). Plasma volume — The volume of cell protoplasm within a plant cell. This may be significantly less than the volume contained bv the cell wall. Plastic limit — The point at which the capability of a plastic to be continuously deformed is exceeded. Plate count — A method for enumerating microorganisms based upon the reproduction of individual, viable micro- bes to form macroscopic colonies that can be counted. Plate tectonics — A largely kinetic working hypothesis that assumes that the earth's lithosphere is broken up into sev- eral distinct plates (about 100 km thick) that internally deform very little (are rigid) but can move readily with respect to each other. Pleuronectid — Any of several species of flatfishes (family Pleuronectidae) in which both eyes appear on the right side of their body. In contrast, flatfishes of the family Bothidae have both eyes on the left side of their body. Poll — An estuarine area at the end of a fjord separated from the main body of the fjord by a shallow inner sill. Polychaetes — Segmented marine worms of the class Poly- chaeta (phylum Annelida). Pre-recruits — Fish that are too small, too young, or other- wise unavailable to a fishery. Primary carnivores — The first level of herbivore-eating predators in the food chain. Predators that eat primary carnivores are secondary carnivores. Prodelta — The marine area immediately in front of the delta, usually at the mouth of a river. Progradation — A seaward advance of the shoreline result- ing from the nearshore deposition of sediments brought to the sea bv rivers. Propagule — The minimal number of individuals of a spe- cies capable of successfully colonizing a habitable island. Proteolytic — Capable of degrading proteins. Pseudocomponents — In petroleum engineering, refers to fractionation of oil in a true-boiling-point distillation column yielding components of the oil characterized only by boiling point and density. Pseudomonads — A group of metabolically versatile bac- teria that are Gram negative, motile by polar flagella, and obligately respiratory. Psychrophiles — Microorganisms with optimal growth tem- peratures below 15C that generally can only grow at low (<20C) temperatures. Pteropods — Small mollusks (order Opisthobranchiata) which are modified for pelagic life. Pycnocline — Region of maximum change in density with depth, typically 50 to 200 m in the subarctic Pacific. Pyranometer — An instrument that measures the amount of sunlight received at a given place. Pyroclastic flows — Volcanic materials that have been explosively or aerially ejected from a volcanic vent and that move downslope under the influence of gravity. Recruits — The supply offish that becomes available at some particular stage in the life history of the species. Red tides — Reddish appearance of inshore waters owing to blooms of dinoflagellates or other protozoans; paralytic shellfish toxins are sometimes associated with red tides. Refractive index — The ratio of the speed of light in a vac- uum to the speed of light in the medium under consideration. Regenerated production — Primary production that results from utilization of nutrients derived from respiration and recycling of organic matter in the euphotic zone. Relict — An organism or material of earlier time surviving in an environment that has undergone considerable change. Reproductive success — Refers to the number of offspring produced per egg during a breeding attempt. Residence time — Volume of water in an environment (e.g., an estuary) divided by the input or removal rate. In chem- istry, the residence time of an element is the average time that it remains in sea water before removal by some pre- cipitation process. Reverse fault — See fault. 632 Glossary Reversing thermometer — A specialized thermometer used for recording water temperatures at discrete depths. Reversing thermometers were the primary instruments for temperature measurements in physical oceanographic research from about 1900 to the 1960s, when thev were replaced by electronic instruments (e.g., CTD). Rheology — The quantitative description of the relation between strain and stress in earth materials. Ridge push — One of the fundamental driving forces for plate motion; ridge push is a gravitational force that points in the direction of a gradient from high to low topography near mid-ocean ridges. River otter — Lutra canadensis, a semi-aquatic carnivore of the weasel family. Roe-herring fishery — A seine and gillnet fishery directed toward the capture of ripe female Pacific herring (Clupea harengus pallasii) in order to obtain their roe. Most of the roe is exported to the Orient, where it is considered a delicacy. Rorqual — Whales of the genus Balaenopteridae (suborder Mysticeti) that possess numerous ventral grooves and a dorsal fin. Rossby radius of deformation — The horizontal scale at which rotational effects become as important as buoy- ancy effects. Near a mountainous coastline, it is the dis- tance offshore within which the flow adjusts to the pres- ence of a mountain barrier. Runs — Groups of fish, particularly those ascending a river from the sea. S distribution — The horizontal and vertical salinity field. Sac roe — Eggs of fishes held in a soft-walled membrane; used to designate the roe of herring. Saccharolytic — Capable of degrading carbohydrates. Salmonids — Members of the fish family Salmonidae, which includes the salmons, trouts, and whitefishes. Salps — Pelagic tunicates of the class Thalliacea. Scutum — One of the anterior, paired, movable plates which, along with the paired terga, form the operculum that covers the aperture of an acorn barnacle. Sea stack — A small, steep-sided, rocky projection above sea level near a coast. Sea-level pressure — The atmospheric pressure exerted on a unit area at mean sea level from the weight of the atmos- phere directly over the unit area. Seamount — A submarine mountain, usually of basaltic magma, emplaced onto an oceanic crust of generally younger age. Seasonal thermocline — A discontinuity in the vertical tem- perature profile caused by surface heating in the summer. Secchi disk — A simple instrument used to measure the light extinction properties of surface waters by measuring the depth at which the disk disappears from view. Secondary bloom — A phytoplankton bloom of lesser inten- sity, and usually occurring later in summer, than the pri- mary spring bloom in temperate-boreal regions. Sedge — Fresh- or brackish-water plants of the family Cyperaceae which resemble grasses but have solid rather than hollow stems. Sediment failure — A term used to designate the point when sediment moves under stress. Sediment traps — Containers, open at their upper end, which are suspended at selected depths to measure the amount of sinking material. Seiche — A standing wave in a confined body of water, such as a lake, bay, or fjord, which continues oscillating after the cessation of the originating atmospheric or seismic force. Seismic (seismogenic) — The property of brittle rock to fail suddenly under stress, thereby causing earthquakes. Seismicity — The occurrence of earthquakes as quantified by their patterns in space, time, and magnitudes. Semidemersal — Refers to animals that often occur near the bottom, but which may be caught in the water column. Senescence — That period in the life of an individual when its powers are declining prior to death. Sensible heat flux — The quantity of heat (thermal energy) transferred between the earth's surface and the atmosphere. Seston — A general term referring to all suspended matter in water. Set gill net — A gill net that is anchored to shore. Sexual dimorphism — A difference in appearance, such as size, between the male and female members of a species. Shannon index (H') — An index used to describe the diver- sity of organisms within a community. Shelf break — The outer edge of the continental shelf; marked by an increase in slope as the bottom descends to the abyssal plain. Siblicide — The killing of a brother or sister by a sibling. Glossary 633 Sigma-t — A term used to describe the density of seavvater. Because the significant part of a seawater density meas- urement is usually beyond the third decimal, a conversion has been adopted: Sigma-t = (density - 1) x 1,000; thus a density of 1.02750 g/cm3 = sigma-t of 27..r>0. Significant wave height — The average height of the one- third highest waves measured in a given wave group. Siliceous ooze — A type of marine sediment composed largely of diatom frustules. Silicic acid — The soluble form of silicon in seawater that is conventionally analyzed ('soluble reactive silica'). Silver salmon — A common name for fish of the salmon spe- cies Oncorhynchus kisutch, which is also known as coho salmon. Simulated in situ incubations — A method used to measure phytoplankton growth rates by incubating bottles of water from selected depths on the deck of a ship. The bot- tles are covered with various light filters to simulate the light conditions at the depths from which the water was collected. Slab pull — One of the fundamental driving forces of plate tectonics, which arises during plate convergence when the negative buoyancy of a cold, dense slab exerts a down- ward directed force onto the slab as it descends into the warmer, and hence less dense mantle. Smectite — A green clay. Sockeye salmon — A common name for fish of the salmon species Oncorhynchus nerka, which is also known as red salmon. Southern ocean — Refers to the Antarctic Ocean. Spawning aggregation — Large numbers of a species that gather together for the act of spawning. Specific growth rate — A growth rate in terms of the uptake of a selected element (i.e., carbon or nitrogen). This may or may not correspond to the actual growth rate of the organism, depending on whether or not growth is bal- anced. Sphagnum bog — Freshwater, acidic wetland characterized by an abundance of mosses of the genus Sphagnum. Spring bloom — A rapid increase in the growth of phy- toplankton; usually observed at mid- to high latitudes during spring, due to the increase in daylight coupled with decreased surface-water mixing. Squamish wind — Local Canadian name for a katabatic wind. Standing crop — The amount of plant material present at a given point at a given time. Stochastically — In mathematics, pertaining to random variables. Stock — Generally pertaining to commercially caught fish that are genetically of one line of origin. Stock density — The number of individuals of the target spe- cies available per unit volume or area. Stratification — The restriction of vertical mixing in water columns caused by density differences between water layers. Streamline — A fluid line having the property that the tan- gent at every point on the line is aligned with the fluid's local velocity. Strike slip — Movement in which the slip across a steeply dip- ping fault is mostly horizontal. Subduction — The 'pulling under' of one lithospheric plate- beneath another. Submarine diffuser — A device at the terminus of an outfall in which a high-velocity, low-pressure stream of fluid is converted into a low-velocity, high-pressure flow to pro- mote rapid mixing and dilution of the discharge with receiving waters. Subsistence fisherman — A person whose primary moti- vation to fish is to obtain food, in contrast to a commercial fisherman, who is motivated by economic gain, and an angler, who fishes mainly for sport. Supralittoral fringe — In the Stephenson Universal Zona- tion scheme, the highest zone on the shore bounded below by the upper limit of barnacles and above by the upper limit of Littoritia. Surface gill net — A gill net that floats on the surface and is free to move with the currents (i.e., drift net). Surge channel — A deep channel in the seaward face of a rock or coral reef or platform through which water moves freely. Suspended load — The total weight of particles suspended in a volume of water. Sustained winds — Winds averaged over a period of one minute. Sympatric — Pertaining to two or more populations of closely related species that occupy identical or broadly overlapping geographical areas. Sympatric speciation — Speciation which occurs within the same range. Synoptic survey — An areal grid of observations occupied over a brief period of time. There is no precise definition of what is and is not 'synoptic'. Station 'P' — See Canadian Ocean Weather Station 'P'. 634 Glossary Synopticity — In oceanography, relating to or displaying oceanic conditions as they exist simultaneously over a broad area. T distribution- field. -The horizontal and vertical temperature Taku wind — An Alaskan term for cold air draining from interior glacial or ice-field regions. Talus slope — Slopes of unevenly sized rock debris produced by the fracturing of rock faces. Tectonics — The study of the processes that form the large-scale structures of the earth. Teleseismic — Pertaining to the distance far from the hypoc- enter of an earthquake, usually more than 1,000 m away. Tephra — A general term for all fragmented rock material formed by volcanic eruption. Terpenes — A complex variety of organic compounds found in many plant and animal materials. Most terpenes found in ocean water are presumed to have originated in the ter- restrial environment, and thus have the potential for identifying marine waters that have been directly influ- enced by continental inputs. Terrane — A fault-bound piece of the earth's crust with a geologic record of evolution that is clearly distinct from now adjacent pieces of crust. Terrigenous — Derived from the land, especially by erosion. Thalweg — The line joining the deepest points of a stream channel, often used as a synonym for the profile of a val- ley. Thermocline — The region in a thermally stratified body of water in which the temperature decrease with depth is greater than that of the water above and below. Thirty-five hour filter — A computational procedure for smoothing and removing high-frequency fluctuations in data. This filter is mainly used in physical oceanographic calculations to remove tidal energy; more than 99% of the amplitude of fluctuations of periods less than 25 hours is removed by the procedure. Thrust fault — See fault. Tidal prism — In an estuary, the volume of water between high and low water levels. Time series — A series of measurements made at the same geographic area so that seasonal and longer time-scale trends can be resolved. Toothed whale — Whales of the suborder Odontoceti; all of these animals (including porpoises and dolphins) have teeth instead of baleen, and have a single blowhole. Tower counts — Fish counts made from a tower which per- mits the observer to look down into the target area. Trammel net — A form of gill net consisting of two taut outer nets of large mesh and a larger slack middle net of finer mesh, all three being attached to each other at the head, foot and ends. Transfer efficiency — The fraction of biomass actually used for growth by trophic level i as obtained from the trophic level just below it (?'-!). Transition waters — Ocean waters intermediate in character between two recognized water masses. Trench — A long, narrow depression of the deep-sea floor having relatively steep sides; ocean trenches can be up to 11 km deep and are usually found at an active plate bound- ary where an oceanic lithospheric plate subducts. Triple junction — The locus where three plate boundaries meet. Depending on the type of boundaries that meet, the triple junction is named accordingly (e.g., a trench- ridge-transform triple junction). Trophic studies — Investigations of food chain phenomena; that is, investigations of the relationships among preda- tors and their prey and/or herbivores and the plants they utilize for nutrition. Trophodynamic modeling — Modeling of an ecosystem based on transfer of energy (food) through the food chain. Try net — A small trawl, about 4 to 5 m wide, with com- paratively small meshes (< 5 cm). Tsunami — A large sea wave caused by an earthquake or vol- canic eruption. Tule goose — Anser albifrons gambelli, a large subspecies of the white-fronted goose which nests dn marshes in western Cook Inlet. Tunicates — Soft-bodied animals belonging to the sub- phylum Urochordata, characterized by the presence of an enclosing mantle. U.S. Fishery Conservation Zone — A zone contiguous with the territorial seas of the United States and extending sea- ward 200 nmi; see Magnuson Fishery Conservation and Management Act of 1976. Ultraplankton — Plankton too small (< 5 microns) to be seen with ordinary microscopes. Ulvoid — Characteristic of the green algal family Ulvaceae; most species have broadly expanded, membranous, green blades. Glossary 635 Upwelling — The replacement of surface water with deeper, Year class — That part of a population that was produced cooler and usually more nutrient-rich water; can result during one year. from diverging ocean currents or decreased water level along the coast owing to wind sheer; opposite of down welling. Variance — The square of the standard deviation from the mean value. For current velocity, one-half the variance equals the fluctuating or eddy kinetic energy per unit mass. Verrucaria zone — The zone that commonly forms in the lower part of the supralittoral fringe and is distinguished by black crusts composed of blue-green algae, or by lichens of the Verrucaria type. Vertical eddy diffusivities — The rate at which waters, or materials dissolved or suspended in them, are mixed with those at greater or shallower depths by diffusive processes. Vertical stability — The resistance of a water column to mixing. Volcanic front — A theoretical linear locus in a subduction zone drawn along strike, and seaward of, a volcanically active arc. In map view, it separates the areas with and without active volcanoes. Voles — Small, mouse-like rodents (e.g., Microtus spp.) having short limbs and a short tail. Vorticity — A tendency for spin or shear in motion. Plane- tary vorticity exists because of the earth's deflective force; relative vorticity results from local shear or curvature in the flow. In oceanography, refers to the horizontal cir- culation of a fluid particle about a vertical axis. Wadati-Benioff zone — The dipping zone of subcrustal earthquakes in a subduction zone which occurs in the cold and brittle stressed portions of a subducting lithospheric plate as it descends into the otherwise aseismic mantle. Wandering tattler — A shorebird (Heteroscelus incanus) that nests in alpine tundra and winters along rocky shorelines. Weir — A fence set in a stream or in a channel to capture fish. Weir counts — Counts of migrating fish (e.g., salmon) that have been caught in a weir. Wetlands — An areas of low-lying land, inundated perma- nently or periodically by fresh- or saltwater. Wind forcing — Various aspects of the wind field that pro- duce effects in the ocean. Zoogcographic affinity — A description of the geographical distribution of an animal. Index 637 abundance 351 Acanthomysii 509 \( ai in.i 311,330 Acartia longiremis 290-92,295 accretion 587,603 .ic c i etionar) prism 150,157 Achromobacter 222 acid rain 585,587 Acinetobacter 223 Armiiea (sex- Solum mam) a< oustu -.in ve) 436 Acridine Orange Direct Count 221 Actinomycetes 222 Actitis macularia (see spotted sandpiper) Adak Bay 264 Adak Island 249,264,469 Admiralt) Island 307,576,582 advection 82,85,192,197,200,201,205,262, 264,513,606 Aegma titreu 291 iethia cristatella (see crested auklet) .4. pusilla (see least anklet) Afognak Island 128.157.372.376.442 Agarum cribrosum 325.326,607 age structure 430,463 Aglantha digitate 291 Agonus acipenserinus (see sturgeon poacher) Ahtna Indians 15 Aiaktalik Island 609 Aialik Bay 85.350.364.382,383.387 Aialik Glacier 382 Aialik Inlet 195,196,199,202 Akutan Island 176 Akutan Whaling Station 581 Alalia crispa 328,330.331 l.fistulosa 325,326.331.333 A. spp. 607 Alaska Bay 8 Alaska Coastal Current 63,66,67,86,87 biological significance 6,264-67,273,294, 349,382.387,388,412,486.513 origin and trajectory 6.8.9,49.66,67.73. 83.9(1.199,207,504 sediment transport 381.382 velocity and transport 6,49,65,71,73,83, 113.262,603 Alaska Coastal Management Plan 587 Vlaska Coastal Management Program 578 Alaska Current 6,59,60,86,293 biological significance 294,412,430-32, 437.513 origin and trajectory 9.59.504.561 velocity and transport 262 Alaska Department of ( ommunit) and Regional Affairs (DCRA) 545,576 Alaska Department of Knvironment.il ( lonser vat ion (DEC) 582,583 Alaska Department of I'ish and ( lame (ADF&G) 348,350,356.359,369 78.380. 388,400,413,439,442.443.444,461, 464, 170, 515,536,540,541,544,545,546,548,576,586, 608 Alaska Department of Natural Resources (DNR) 576.583 Alaska Maritime National Wildlife Refuge 576 Alaska National Interest Lands Conservation Act(ANILCA) 57t>, 586 Alaska Native Claims Settlement Act (ANCSA) 576 Alaska Peninsula 8,129.433,438 biological resources 380,412,438-44,469, 482,483,486,489,491.502,529,533,537. 541.544,545 boundary of Gulf 8 fisheries 439-44 geology 6,94,118,129,131,132,150,156-58, 174,176,309,387.600 human history/exploration 13,15 meteorology 39,40,44,45 microbiology 235 sea ice 601 water mass boundary 66,67,262,265,294, 429,433,504,582 Alaska Pipeline 9.168,236,306,582 Alaska Sea Grant Program 576 Alaska Stream (see Alaskan Stream) Alaska surf clam (see pinkneck clam) Alaskan continental shelf 222,224,227,567 Alaskan Gyre 61,256,258,260,274,418,504. 561 Alaskan pollock (Theragra chalcogramma) 400 abundance 448,546 in diet of birds 437,512,515 in diet of fish 410,411,437 in diet of invertebrates 438 in diet of mammals 437,532,533,536,538. 539,541-43 distribution 294,350,363,372,403,407. 408.434.437.443,448 ecology 449,607 I isherv 7,21,348,418,422,434-37,546,579. 611 food habits 294.363,372,385,410,429.430. 437.438.607 lifehistory 265,407.408.436 Alaskan Range 152 Alaskan ronquil 408,409 Alaskan Stream 59,60,67,79,293 biological significance 264.269,274.294, 337,412.426.434 origin and trajectory 6,8,59,60,96,253 sediment transport 120, 381.421) velocit) and transport 19,59,60,61,63,67, 113,441.603 Alaskan Stream domain 253 albacore tuna {Thunnus alalunga) I (0 albatross 504-6,511,513,611 Albatross Bank 115,117,118,120,377, 138,603 Alberni Inlet 192.193 akid ■199.501,502.50 1-6.5091 1.515 alcvonarian 362 Alepisaurusferox (see lancet lish) Aleut midden 325 Aleutian Canada goose (Branta canadensis leuco- par) 482,611 Aleutian Islands 8,249,307 birds 493,495,501,502,505 chemical oceanography 60,80 fisheries 423,424.442 fishes 422,428,430,432-34,438,4 10 geology 156,588,600 human history 15,576 invertebrates 380,444,445 mammals 323,541,543,545,546 meteorology 32,36,38.39,49 other biota 223,225,258,311.313.314,333 physical oceanography 6,45.59,262.412 pollution 585 Aleutian low 32,35,38,43.49.50,82.83 Aleutian Passes 264,273,383,385 Aleutian Province 310.311.313 15 Aleutian storm track 6,31.33.37 Aleutian tern (Sterna aleulica) 499.507.508 Aleutian Trench 6,9.79,145,147,150.152,168. 434 alevin 465 Alexander Archipelago 8.9,13,16.19.249. 582,586 algae abundance/biomass 315.328.383 distribution 334 diversity 313.330 ecology 313.315,316,321,325,327.328,330, 334.371.409 macroalgae 306,308,310,316,321,325,327, 328.371,383,409, 185 microalgae 198,251,315,607 algal growth rate 256 alginase 232,233 AlitakBay 373-76,400.403 alkalinity budget 82 allele 431 Allocenirolus fragilis (see also, sea urc Inn) 359 allochthonous carbon 7,383,566 Alopex lagopus (see An tit fox) Alsek (Seavalle) , Canyon, Trough) 93,96, 105-9,113,114,133,353,356,359,360 Alsek River 93.105.107.108,113.11 1.133 Alvinia compacla 485 Amatuli ["rough 94,115,122 638 Index Amchitka environmental studies 806,310,327,328, 331 human history 325 intertidal ecology 310,31315,325,327,331, 333,380,528 invertebrates 314,315,326 macrophytes 314 mammals 325 pollution 585 seismicity 156 Amchitka Island 310,31315,325,327,333, 545,585 Amchitka Pass 426,535 American black oystercatcher (Haematopus bachmam) 486,487,489 American Mail Line (AML) ships 256 American widgeon (Anas americana) 483,610 American vellow skunk cabbage (Lysichitum americanum) 485 amino acid 225,226,234,268 Ammodytes hexapterus (see Pacific sand lance) Ampelisca hessleri 362 A. spp. 372.378 amphipod 286,289,291,294,330,362,363, 370,372,377,378,409-11,437,438,485,489, 508,509,511,534,563,607 Amphipoda (see amphipod) Amphiura psilopora 380 anadromous fish 9,439,461,537,538,563, 583,588 Anarkhas orientalis (see Bering wolffish) Anas acuta (see northern pintail duck) A. americana (see American widgeon) A. crecca (see green-winged teal) A. platyrhyncos (see mallard duck) A. slrepera (see gadwall) Anchor Point 45,371 Anchorage 8,47,126,165,168,173-77,307,417, 479,496,545,575,576,584,585,597,604 anchovy (Engraulis mordax) 538 ancient murrelet (Synthliboramphus antiquum) 499,501,505,510,511,514 anemone 359,375,377,380 Aniakchak Volcano 174,175 Anoplopoma fimbria (see sablefish) anova ( = analysis of variance) 262,323 anoxia 85,193,205,207,272,376,380 Anser albifrons (see white-fronted goose) Anser albifrons gambelli (see tule goose) Anthozoa 311 anthropogenic carbon 205 anthropogenic chlorofluoromethane 82 anticline 115,117 apex predator 7,386,515,566-68,606,608, 609 Aphriza virgata (see surfbird) aplacophoran mollusk 363 apparent oxygen utilization (AOU) 79 aquaculture 22,580,611 British salmon pen ranching 580 mariculture 22 aragonite pteropod test 82 saturation 81 Architeuthidae 445 Arctic cod (Boreogadus saida) 532,538 Arctic Environmental Information and Data Center (AEIDC) 310,576,612 Arctic fox (Alopex lagopus) 490 Arctic ground squirrel (Citellus parryi) 491 Arctic tern (Sterna paradisea) 499,505,507, 508 Arctic-boreal species 313 Arctic-Yukon-Kuskokwim area 419 Arenaria interpres (see ruddy turnstone) A. melanocephalas (see black turnstone) aromatic hydrocarbon 84,582,585 arrowgrass (Triglochm) 485 arrowtooth flounder (Atheresthes slomias) 350,385,403,408 arthropod 355,360,362,364,369,374,440 arylsulfatase 231,232 ascidian 357,380 aseismic (tectonics) 147,149,150,154,157,158, 168 Asia 7,33,34,36,37,39,305,311,313,314,333, 429,434,442,461-63,468,473,486,496,543, 579,580 assimilation efficiency 567 assimilative capacity 575,585 Astarte sp. 362 Astartidae 372,377,378 asthenosphere 146,147 Athabascan Indian 15 Atheresthes stomias (see arrowtooth flounder) Atka mackerel (Pleurogrammus monoplerygius) 7,294,350,417,422,438,607 Atlantic cod (Gadus morhua) 422,434,437, 539 Atlantic mackerel (Scomber scombrus) 539 Atlantic puffin (Fratercula arctica) 511 Attu Island 307 Augustine Island 47,367,371,386,601 Augustine Volcano 150,172,174,175,371,601 Augustine, Mount (see Mount Augustine) Auke Bay 268,270,273,275,291,307,318,320, 321,323,335,578 Aulorhynchu.s flavidus (see tubesnout) automatic jigging (fishing) machine 402 avalanche 165,172,175,176,587,600 Axinopsida 362,364,367,376,377,381,382 A. serncata 362,364,367,376,381 A. spp. 377 A. viridis 382 Axiothella catenata 373 Aythya marila (see greater scaup) B Bacillus 222 bacteria 221-29,231-34,236,237,267,308,372, 563,566,585,607,608 bacterioplankton 563 Baird's beaked whale (Berurdius bairdi) 545 Baja California 33,438,502,530,533,534 Balaena glacialis (see Pacific right whale) Balaenoptera acutorostrata (see minke whale) B. borecdis (see sei whale) B. musculus (see blue whale) B. physalus (see fin whale) Balaenopteridae 530-32 Balanus crenatus 376 B. glandula 305,316,318-21,325,327,330, 331,334,335,485 B. rostratus 367,380 B. spp. 371,374,377 bald eagle (see northern bald eagle) baleen whale 530,533-36,565,567,581 Baltic Sea 230,319,361 Banjo Point 328,330,331 Baranoflsland 16,439,542,545 Baranof, Alexander A. 16 Barber, Point (see Point Barber) barnacle (see also, specific names) 292,316, 319-21,323,325,327,330,335,367,370-72, 375-77,380,382,485,533 baroclinic flow 61-63,67,190 baroclinic forcing 262 baroclinic wave 562 barotropic flow 62,71 barotropic mode 57 barotropic pressure gradient 49 Barren Islands 367,370,480,495,508,513, 537,542,544,609 Barrow's goldeneye (Bucephala islandica) 483,485 basalt 148,150,161 basket star (Gorgonocephalus caryi) 357,362, 378 bathymetry 57,123,162,173,269,351,373,426, 603,604 Bathyplotes sp. 362 beaked whales (Ziphiidae) 420,527,530,545, 548 Beaufort Sea 221-23,226,231,232,234,369, 537 Bedford Basin 197 bedload 115,120,124,131,133 Belkofski Island 16 belt transect 335 Beluga coal field 583,588 Beluga River 537 belukha whale (Delphinapterus leucas) 420, 527-30,537,548 Beneckea 223 benthic amphipod 534 benthic autotroph 315 benthic community 202,230,232,315,566, 583 benthic macrophyte population 326 benthic production 347,348,353,367, 385-87,564 benthos 17,347-96 abundance/biomass 50,352,360,380,383, 386,387,607 distribution 200,201,347,348,352,362-64, 382,386,564 diversity 383,386 dynamics 200,383,386,387,567,607 ecology 50,347,348,382 species composition/diversity 201,348, 352,362,364,383 benzanthracene 235,236 Berardius bairdi (see Baird's beaked whale) Index 639 i>cig\ i)ii <>o:i Bering ( lanyon 359,360 Bei ing cisco (Coregonus laurettae) 408 Bering Field 583 Bering Glacier 93,107,114,348 Bering Island 314 Bering poacher (Ocella dodecaedron | 103 Bering River 7,4(54.48(> Bering Sea benthos 385,387 biological features 17,226,313,380 birds 489,495,502,504,510,512-15 circulation 83.294 continental shell 21 geomorphology 8.163,164 human history/exploration 13,15,604 manunals 528. 5:50.5:51. 533, 534, 537,539, 542.581 meteorology 33,38,39 microbiology 22:5.227 pin toplankton/algae 264,328 pollock/other fish 418,421-24,426,428, 130, 1:52 37. 439-44, 448.464, 467. 468,580, 609 storms 35-37,42,606 volcanism 150,161 zooplankton 286-88,292,293 Bering Sea beaked whale (Mesoplodon stejnegeri) 545 Bering Sea Shelf 150.161,163.164,426,434, 440,567 Bering Strait 9.13.313,319,418 Bering 1 rough 96,101,109 Bering wolffish (Anarichas orientalis) 402 Beringian planktivore 514 Berner's Bay 307 Berr\teulhis magister (see also, squid) 360, 444,445 biochemical affinity 436 biogenic particle flux 82 biological production 50,274,561,564,597, 599,605.608 biologically sensitive area 609 bivalve 272,359,360,362-64,366,367,370-72, 376-78,380-82,387,485,489,534 black mat svndrome 227 black rockfish {Sebastes melanops) 408,409 black scoter (Melanilta nigra) 483 black turnstone (Arenaria melanocephalas) 487 black legged kittiwake (Rissa tridactyla) 295, 376,479,496,497,499.505,507,514,515.605. 609,611 Blackburn, Mount (see Mount Blackburn) blackcod (see sablefish) Blackstone Bay 349,363 blastocyst 541.543 Blue fjord 349.363.382 blue king crab (Paralithodes platypus) 386 blue mussel (Mytilm sp.) 485,515 blue whale {Balaenoptera muscidus) 295.530, 545 Bluff Point 370,371 Boca de Quadra fjord 84,189-93,195, 197-200.202-8.268.273.307.598.604 Bona, Mount (see Mount Bona) bongo net 401,407 Bonin Island 532 Bootlegger Cove Formation 173 Bonier Ranges fault 156,157,161 boreal fauna 313 Boreogadtts saida (see Arc tit cod) bottom drifter 417.441 bottom trawl 360, 120,438, 1 18 boundary current 57,62,63 box model 189.202 brachiopod 311,360,362,364,367,372,375, 377,381 Brachiopoda (see brachiopod) Brachyramphus brevirostris (see K it tlitz's murrelet) B. marmoratum (see marbled murrelet) brachyuran crab 411 Bramajaponica (see pomfret) Brandt's cormorant (Phalarrororax penicillatus) 495 brant (Branta bernicla nigracans) 481-83 Branta 481,482 liranta bernicla nigracans (see brant) Branta canadensis (see Canada goose) B. canadensis julva (see Vancouver Canada goose) B. canadensis leucopar (see Aleutian Canada goose) B. canadensis minima (see cackling Canada goose) B. canadensis occidentals (see dusky Canada goose) B. canadensis parvipes (see lesser Canada goose) B. canadensis taverner (see Taverner's goose) breeding phenology 611 breeding season 495,499-502,505,514,531, 541-43 Brisaster townsendi (see heart urchin) Bristol Bay 226,231,439,442,461-70,473,512, 537 British Columbia biology 419 birds 482,488,499,501,502,508,510,511 chemical oceanography 233 circulation 197,199,203,262 environmental impact 235,236 fisheries 13,431,467,607 fishes 50,226,402,412 geology 8,150 invertebrates 316 mammals 535,536,542 meteorology 189,191-93 microbiology 229,236 physical oceanography 43,84,188 phytoplankton 202 zooplankton 201,286,288,294,295 brittle star (Ophiura sarsi) 359,362,376,377, 111 brown bear (L'rsus arctos) 491 browser 315,353,372,373,376,377 bryozoan 327,362,367.369.371,380.381 bubble net 533 bubble-phase gas 107,118 Bnci inium 5 15 Bucephala albeola (see bufflehead) B. clangula (see common golden eve) /{. island a a (sec Barrow's goldcneye) bufflehead (Bucephala albeola) 483 Buldir Island 380,611 buoy 18, 41, 45.65. 67, 84. 147. 161, 295. 417. 424, 426,427,445,446,535,603 Bureau of Commercial Fisheries 19,348, 350,578 Bureau of Land Management (Bl.M) 19,21, 286,578,598 Bute Inlet 208 butter dam (Saxidomus giganteus) 545 butter sole (lsupsetta isolepis) 350,408 by-catch 434,448,449 cackling Canada goose {Branta canadensis min- ima) 482,483 C.adulus 351 Caines Head 364 calanoid copepod 200,256,287,294,409, 437,511,514,531,563 Calanus cristatus (see Neocalanus crista! us) C. finmarchicus 287 C. marshallae 288,290-92,295 C.patijicus 287,289 C. plumchrus (see Neocalanus plumchrus) Calidris alpina (see dunlin) C. canutus (see red knot) C. mauri (see western sandpiper) C. minutilla (see least sandpiper) C. ptilocnemis (see rock sandpiper) California biological aspects 223,433,438,439,445, 464,467,482,483,502,505,511,531.533, 534,538,539,541-43,548,580,611 geological aspects 7,145,169,599 physical oceanography 33,37,38,72,172, 587 California coast 33,37,293 California Current 293,504 California earthquakes 169 California sea lion (Zalophus californianus) 530,545 Callisto Head 364,382 Callorhinus ursinus (see northern fur seal) caloric value 546 calving area 532,534 Canada goose (Branta canadensis) 481-83, 485,610.611 Canadian Arctic Expedition 285 Canadian Ocean Weather Station P 7,19,58, 77,78,80,249,250,251,253-56,258.260,262, 274,285,286,535,538,539,545,565,606,608 Cancer magister (see Dungeness crab) C. oregonensis tin Cannikin detonation 310.328.330.331 Cape Chiniak 426 Cape Cleare 348. 349. 351. 357. 426.427 Cape Douglas 45,65,94,120,126,128,131,132, 370 Cape Edgecumbe 9 640 Index ( lape Fairfield 356 Cape Fairweather 9,351,541 CapeFlatterv 12 I. 127 Capelgvak 8,372 Cape Kaguyak 313 CapeNavarin 424 Cape Ninilchik 124 CapeSitkinak 313 Cape Sencer 8,348,381,384,429,544 Cape St. Elias 8.9,481,495.497,499,502,514, 5:52.5:53,544 Cape Suckling 356 Cape Yakataga 106,315,316,359 capelin (see white capelin) carbon budget 565 carbon isotope data 79 carbon-to-nitrogen ratio 268,269,274 carbonaceous compound index (UAI) 225 carbonate ion activity 81 Carcinonemertes errans 371 Carditidae 372,378 Cardium sp. 372. 378 Carex spp. 485 caribou 586 caridean shrimp 411 Carnegie Expedition 285 carrying capacity 529,534,545 Cassin's auklet (Ptychorarnphus aleuticus) 499, 501,502,505,510,511.514 Castle Island 582 Castle Mountain 152,156,163 catch per unit of effort (CPUE) 355 catchment areas 189,199,207 cell carbon 251 cellulase 231 Central Alaska 85,152,156,163,174,199,256, 419.461.464-68.474,486,583 Central Pacific 34,462.467,469 Central Subarctic Domain 249,253,254, 256,258,274 Central Subarctic Water 256 Cenlropages abdominalis 288,290,295 cephalopod 15,286,360,444,445,508,511, 527,531,535,539,541,543,546 Ceralium longipes 271 Cerorhinca monocerata (see rhinoceros auklet) cetacean 8,527-30,539,545,546,548,605,611 Chaetoceros concavicornis 262 C. debilis 260 C. spp. 270 Chaetoderma robusta 363,364 chaetognath 286,289,290,437,606 Chagulak Island 493 Challenger Expedition 17,18,285 Charadrius semipalmatus (see semipalmated plover) Chatham Strait 331,439,533 Chen caerulescens (see snow goose) C. canagica (see emperor goose) Chenaga Village 172 Chernofski 16 Chesapeake Bay 222,225,226,440 Chignik 439,442 Chilkat River Flats 610 China 16 Chiniak 115,117-20,378,406,407,426,442, 480,497,499,603,609 Chiniak Bay 406,407,480,497,499,603,609 Chiniak Trough 115,118-20,378 Chiniak, Cape (see Cape Chiniak) ChinitnaBay 309,601 Chinook salmon (see king salmon) Chionoecetes bairdi (see Tanner crab) C. spp. Ill Chirikof Island 93,94,96,126,132,373,378, 424,609 Chisik Island 367,480,499 chitin 227,362 chiton (Cryptochiton stelleri) 325,545,584 chlorite 107.117,123,126 chlorofluoromethane 82.86,87 chlorophyll 7,200,249,251,254-56,258,264, 265,267-69,272,273,562-65 choanoflagellate 262 Chowiet Island 609 Chthamalus dalli 305,327,334 C. stellatus 316 Chugach National Forest 583 Chugach-St. Elias Range 152,161 Chugachimiut Eskimo 15 Chukchi Sea 13,236,533,534,536 chum salmon (Oncorhynchus kela) 229,405, 408,409,419,463,464,466-68,473 ciliate 608 circumpolar 222,313,496,499 Citellus parryi (see Arctic ground squirrel) Citrobacter 227 cladoceran 290,294,295 clam abundance 563 in diet of birds 485,512 in diet of fish 410 in diet of invertebrates 359,370,371,375, 380,382,386 in diet of mammals 545,547 distribution 309,367,372,377,383,386, 387,419.568 fishery 563,580,586,605,608 populations 308,387 toxicity 19,272 Clam Gulch 610 Clangula hyemalis (see oldsquaw) Clean Water Act 578,584,612 Cleare, Cape (see Cape Cleare) Clinocardium 351,359,362,376,377 C. ciliatum 359,362,376,377 C. nitidella 351 Clione limacina 289 cloud streets 42 Clupea harengus pallasii (see Pacific herring) cluster analysis 222,311,313.366 clutch 495,515 Cnidaria 286,288,290,291 coastal development 347,605 coastal wind jet 31 Coastal Zone Management Act 578 coccolithophorid 251,262 cockle 360,362,376 cod abundance 403,408,412,422,449 in diet of birds 512,607 in diet of fish 410,607 in diet of mammals 532,533,535-39,542, 546,607 distribution 350,403,408,409,412,420, 422 ecology 449,563,566 fishery 7,347,348,413,418,421,422,611 food habits 370,372,374,430,443,607 life history 424,432,437 processing waste 584 coho salmon (Oncorhynchus kisutch) 463,464, 610 Collembola 330 Collisella digitalis 327 C. strigatella 327 Cololabis saira (see saury) Columbia Bay 349,363 Columbia River 81,192,193,227,418,463,464 Coins halli 359 Commander Islands 314,315,434,496 commercial extinction 580 commercial fishermen 461,546,547 commercial fishery 372,386,400,424,439, 532,575,585,586,610 commercial sockeye fishery 586 commercial whaling 530,532,534,548,581, 611 common eider (Somateria mollissima) 483 common goldeneye (Bucephala clangula) 483,485,486 common loon (Cavia immer) 481,482 common merganser (Mergus merganser) 483, 485 common murre (Uria aalge) 499,505,506, 510,511,515,609 common raven (Corvus corax) 495,514 common snipe (Call inago gall inago) 486,489 community composition 260,270,286,289, 294,305,313,347 compensation light intensity (Ic) 255 competitive exclusion 320,430 Conchoecia 289 conservative constituent 202 conservative tracer 82,86,206 consumption rate 8,205,206,438,443,527, 531,535,538,541,545,546 continental plate 32,147,150 continental shelf birds 481,504,505,512,514 chemical oceanography 77,585 circulation 6,7,418,422,603,604 environmental studies 18,19,21,23,50,57, 73,177,237,275,296,306,388,399,413,417, 450,474,480,516,548,568,578,598 fishes 347,403,407,421,424,428,429,434, 438,608,611 geology 94,106,107,115,152,156 geomorphology 96,126,133 invertebrates 442,443 meteorology 82,513 microbiology 222,224,227 physical dimensions 8,9,250 physical oceanography 86,87 productivity 562,564,567,568,605,606 641 zooplankton 286 continental slope biological aspects 353,430,433,535,545 circulation 59,429,561 geological aspects 94,101,115,117,118,120, 149,348 Controller Bay 544 convergence 201,293,606 meteorology (7,50,66,82,561 physical oceanography 49,50.66.82,86, 188,190-93,201,203,293,295,561,606 tectonic activity 147.149,154.160 Cook, Captain James (see explorers) Cook Inlei benthos 366 birds 480-83.486-88.490.513,516,609 chemical oceanography 82,267 tin nlation 67,96,125,133,263,366,446, 604,606 earthquakes 165,175 environmental studies 19.21.42,84,156. 306-9,316,364,576,581-83,585-88,599,601, 60410.612 exploration 13,15 fisheries 418 fishes 349,401,403,408,41113,424,437, 439,442,610 geological oceanography 149,150.156,157, 160,172 geomorphology 6,120.121,127 invertebrates 318.320,349,350.359,366, 372,376,382,383,386,387 macrophytes 331.333,368 mammals 528,537-39,544,545,547 meteorology 46,47,265 microbiology 222.225,226,229,230, 234-36 physical dimensions 250 physical oceanography 65 phvtoplanklon 270,607 productivity 7,9,22,273.608 sea ice 42.44.45,131 sedimentation 86,121,123,124,126,128,129, 208,271,566 volcanism 94,156,157,174 coonstripe shrimp (Pandalus hypsinotus) 363, 369,371,372.441 copepod (see also, specific names) 200,201, 229,256,258,267,285-96,385,409,424,430, 432,436,437,439,511,514,527,530-32,546, 563,565,606,607 copepod nauplii 294.295 Copepoda (see copepod) copepodile stage 201 copiotroph 222 Copper Riser 249 biology 9.353.381,540 chemistry 83,207,381 circulation 189,199.264,381,382,428,445. 540 geology 94. 101, 106-8. 111. 113.11 4.117.120. 123.126.133.208,264.271.351.382 human history 15 meteorology 43,49 Copper River Delta 8.15.111.114.168,269,479, 481-83. 485-90. 516. 585, 605. 1)09.6111 Copper River prodelta 101,106,11 1 Copper- Bering River delta 486 coralline algae 327,409 Cordova 328,581-83,586 C.oregonu\ lavrettae (see Bering cisco) Corethron hystrix 262 Coriolis force 33.45.17 Corvus caurinus (see northwestern crow) C. corax (see common raven) ( orycaeus sp. Coryphaenoides spp. (see rattails) Coscinodiscus marginalus 262 Costaria costata 326 cottid 399.402,410-12,418 Cottidae 418,485,542 Council on Environmental Quality (CEQ) 597.598 crab abundance/distribution 21,247,348,350, 355,357,359,362-64,369,374,382,418, 442-44,448,563,566,568,605,610 in diet of birds 485,489,563,566 in diet of fish 410,411,436,437,563,566 in diet of sea otters 545,547,563,566 diseases 227,228,444 ecology 369,412,443,444,563,566,607-10 fishery 7,21,348,355,357,417,419,440,442, 448,579.605 fishery conflicts 585,586 food habits 363,372,380,386,387,409, 563,566,607,608 juveniles 292,361,327 processing waste 584,585 Crangon communis 361,363 C.dalli 369.372 C. septemspinosa 372 C. spp. 362 crangonid shrimp 350,362,369,370,372, 374,440,441 Crescent City, California 172,587 crested auklet (Aethia cristalella) 499,502. 508,509,511,514 critical depth (Zc, ) 198,255,258,562,565 critical habitat 479,597,609,610 Cross Sound 9,93,94,96,101,106.115,132,160, 605 Crustacea abundance 313,314,362,369.387 in diet of birds 509-11 in diet of fish 411 in diet of invertebrates 371,372,386,445 in diet of mammals 539,541,546 distribution 313-15,333,362-63,374 food habits 362,376 Cryptockiton slelleri (see chiton) Cryptomonas 262 Cryptophyceae 565 CTD station 67,77,446 C.tenodiscus crispatus (see mud star) ctenophore 288.291,607 Cube Cove 307 Cucumaria 369.374,375,485 C.fallax 369 C. sp. 374,375 ( urn, k can 363 c lunulas c onvec live c ell 42 current metei 79,82,94,295, 126 c nuhi oat trout (Salmo clarkii) 138 cuttlefish 444 Cuvier's beaked whale t/.i/iluus ravirostris) 545 cyclonic gyre 6,83,561 cyclonic low-pressure system 33 cyclonic vorticity 6 c vc Ionic wind 49,418 Cycloptcrichthys glabn (see globe lish) Cyclopteridae 418,535 Cyclorrhynchus psittacula (see parakeet auklet) Cygtius buccinator (see trumpeter swan) C. columbianus (see tundra swan) Cymathere triplicata 326 Cyphocaris challengeri 291 cyprid 319,321 Cylophaga 222 D dabbling duck 485.610 Dall's porpoise (Phocoenoides dalli) 420.445. 527,537,539,546,548,605,610 Dall, Dr. William H. 18 DDT 585 Deadman Bay 403 decapod 286,294,375,509,534,541 deep-sill fjord 195 deep-water exchange 193 Delphinapterus leucas (see belukha whale) demersal fish 294,295,347,349,370,386, 408,418,420-22,426,429,448,449,579 pelagic larvae of 420 Denali Fault 150 Denali, Mount (see Mount Denali) dendrogram 307,311,313 denitrification 233-35 density differential 193 density gradient 32.65,196 density slope 60 Dentalium sp. 363 Denticulopsis seminar 260.262.565 Department of Community and Regional Affairs (see Alaska Department of Community and Regional Affairs) Department of Environmental Consen ation (see Alaska Department ol Environmental ( li »nsei \ ation) Department offish and Came (see Alaska Department offish and Came) Department of Interior (see United Slates Department of the Interior) Department of Natural Resources (see Alaska Department of Natural Resources) Department of the Interior (see United States Department of the Interior) deposit feeder 315.353.356.359.362.364. 372,373,375-77,380,383,384,386,566 Derickson Bay 349.363.382 detrital food chain 228.233. 111,563 detrital microorganism 221 detritivore 315,607,608 642 detritus 387 allochthenous 161,222,228,232,383,388, 565 autochthonous 161,198,199,202,204,222, 388 definition 228 fecal pellets 607 feeders 352,353,359,372.382,566,608 inorganic debris 113 phytodetritus 205,486.565,566,607 suspension 382,387 detritus feeder 353 diagenetic process 132 diamicton 96,113,115 Diamond Gulch 371 diatom bloom 197.198,201,270,272,273,319 diatoms (see also, specific diatoms) 118,133, 199,200,204,249-51,254,256,260,262,264, 267, 269,270,272,273,315,316,319,327,330, 372,439,563-65,606 Dick's Head 320 Dick, Port (see Port Dick) Dictyocha fibula 269 diel vertical migration 387 differential feeding rate 546 dinoflagellate 271-73,606 Dinophyceae 565 dip-slip 152 Dipsacaster borealis (see also, sea star) 380 Diptera 330,489 direct count 221,222,537,541 directed blast 600 discord mussel (Musculus discors) 485 discrete stock 443,448 Disenchantment Bay 360 dissolved organic carbon (DOC) 206,207, 226,228 diurnal tidal currents 126 diver transect 402 diversity index 226 Dixon Entrance 331,412,528,541,542,568. 576.582,583 dodecane 236 dog salmon (see chum salmon) Dolina Point 313 Dolly Varden trout (Salvelinus malma) 408, 410,438 double-crested cormorant (Phalacrucorax auritus) 495 Douglas, Cape (see Cape Douglas) downwelling 6,49,57.73,82,188,191,194,203, 294,561,562,564 Drake, Sir Francis (see explorers) drift card 417,427,446 Drum, Mount (see Mount Drum) Dry Bay 359,598,605 duck 7,481,483,485,486,563,610 dungeness crab (Cancer magister) abundance/biomass 355,359,360,362, 370.387 disease 227,228 distribution 348,355,359,360,377,380, 387.610 feeding 377 fishery 359,364,369,370,375-77,380,442, 586,608,610 food habits 359. 367,370-72, 376,377, 607, (ilO life history 367,610 as prey 367,546,586 dunlin (Calidris alpina) 7,479,486-89,605, 609,610 dusky Canada goose (Branla canadensis occiden- tal) 482,610 dusky rockfish (Sebastes ciliatus) 408,409,411 Dutch Harbor 71.72,81,176,584 eared seal 541 earthquake, 1972 Sitka (see Sitka earthquake of 1972) earthquake, 1979 St. Elias (see St. Elias earth- quake of 1979) earthquake, Great Alaskan (see Great Alaskan Earthquake of 1964) east Pacific high 33,35,39,49,50 eastern Aleutian Arc 150,167 eastern Aleutian Islands 175,305,313,333, 502,536,541,546 eastern subarctic Pacific 258,260 Echinarachnius parma (see sand dollar) echinoderm (see also, specific echi- noderms) 7,305,313-15,333,355,360-62, 369 Echinodermata (see echinoderm) ecological efficiency 566,567 ecological zone 561,562,565,567 ectoproct 364,375 eddy (see also, gyre) flow 71,73,427,431,564 flux 57,63 turbulence 364,388 eddy heat flux 63 eddy kinetic energy 67 Edgecumbe Volcano (see Mount Edgecumbe) Edgecumbe, Cape (see Cape Edgecumbe) Edgecumbe, Mount (see Mount Edgecumbe) Edmonton, Canada 38 eelgrass (Zostera marina) 308,310,439 eelpout 403 egg harvesting 439 Egg Island Trough 96,101,107,351,357 Ekman pumping 60 Ekman transport 6,32,49,50,82,188,190,191, 193,293,295 El Nino Current 71,195,470,515 Elassochirus tenuimanus 335 Eleginus gracilis (see saffron cod) elephant seal (see northern elephant seal) Ellrington, Point (see Point Ellrington) Elson Lagoon 231 Emerson, Prof. Benjamin K. 18 Emery and Hamilton Pressure Index 38,43 emperor goose (Chen canagica) 483,485 Emperor Seamount Chain 79 Empleclonema 311 Endangered Species Act of 1973 527,529, 535,578,581,586,610,611 endemic species 305,313,333 Endicott Arm 6,86.190,193,196 Engelmann Curve 598 English Channel 18 English sole (Parophrys vetulus) 408 Engraulis mordax (see anchovy) Enhydra lutris lutris (see sea otter) entrapment 67,85,187,190,198,199,563,564, 588 environmental degradation 575,579,581 environmental hazard 575,579,586,587, 597,599,600 Environmental Protection Agency (see United States Environmental Protection Agency) Eopsettajordani (see petrale sole) epibenthic diet 409 epibenthic invertebrate 350,369 epibenthic prey 511 epibenthic sled sample 401,407 epicenter 9,155,158,328,587 epifaunal production 353,386 epipelagic zone 291 epiphytic community 608 Equisetum (see horsetail) equitability index 226 errantiate 410 escapement (see spawning escapement) Escherich ia coli 227 Eschrichtius robustus (see gray whale) Etches, Port (see Port Etches) Ethmodiscus rex 260 Eucalanus bungii 201,287,288,290,293,295, 385 Eucampia zodiacus 260 eulachon (Thaleicthys pacificus) 537-39 Eumetopias jubatus (see Steller sea lion) Eumicrotremus derjugini (see leatherfin lump- sucker) Eunephthya rubiformis 362 Euphausia pacifica 289,291,294,536 euphausiid (see also, specific names) 285, 286,289-91,294-96,387,409,430,432,436, 437,439,445,479,508-511,514,527,530-33, 536,546,563,565,607 euphotic zone 7,18,82,198-200,202,203,205, 251,255,258,260,263,264,268,269,513,562, 564 Eurasia 496 European fur market 581 euryhaline 316,318 eutrophic 268 Evasterias 305,320,321,323,334,335,545 E. troschelii (see also, sea star) 320,321,334, 545 even-year run 17,532,542,463,580 exclosure 335 exclusive economic zone (EEZ) 578,612 exogenous nutrient supply 203 exploitable stock 436,438,447-49 exploitation rate 464 explorers Bezerra and Grijalna 9 Balboa 9 Baranof 16 Bering 9,15.17 Bregin 9 Index 643 Byron 9 Cabrillo 9 Carteret 9 Cavendish 9 Cook 9 d'Ulloa 9 de Pages 9 Drake, Sir Francis 9 Grijalva 9 Hamel 9 Hecta 9 Lentz 1~ Magellan 9 Malaspina 13,17 Mendaria 9 Nowosilzoff 9 Quiros 9 Spilberger 9 Valle 9 Wallis 9 extinction coefficient 251,255,561,562 extreme wave height 96,601 F.vak native 15 Fairbanks 77,86,87,161,296,388,576,598 Fail Held, Cape (see Cape Fairfield) Fairweather Fault 101,145,147,155,160,161, 172 Fairweather Grounds 532,535,538 Fairweather, Cape (see Cape Fairweather) Fairweather, Mount (see Mount Fairweather) Fairweather-Lituya Bay Earthquake 152 False Pass 273,424 Fanafjord 203 fault plane 117.159 feather star 362 fecal pellets 86.256.267,567,607 fecundity 424.430,432.439,611 Federal Water Pollution Control Act (FWPCA) 578.612 fetch 45 fin whale (Balaenoptera physalus) 530-32,546 ("inner whales (see also, specific whale names) 530,535 fish eggs 50,285,407-9,432,434,443,445,449 fish larvae 294.407,420,430,434 fish meal 439 fish processing 581,584 fish stock exploitation 515 fish trap 580,586 fish-processing waste 584 Fisher Caldera 175 fisheries conflict 546,579.580 gillnet 401.402.406.408.440,464,467,469, 510,539,580,585.586 high seas 461-63.469 hook-and-line 101,402,406,431 interception 464,580 jigging 402. 438 longline 413,420-22,433,438,467,585 non-aboriginal 422 seine 401.406.408,467 sei gill net 580 sin imp 579 si u keye 586 spoil 586 standardized i at< h 16 l subsistence 575 surface gill net 101 li.munclnct 400-2.406-8.410.506 troll 383 tr\ nel 373,376,401,406-8, 111 Fisheries Research Board ol Canada 19 Fisheries Research Institute (F'RI; University ol Washington) 310,399,400,469 Fishery Conservation and Management Act ofl976(FCMA) 429,546,578,579 Fishery Conservation /one (FCZ) 8, (ill fjord 187-217 biological production 386,387 fringing 190,195,196,207 glacial 6,187,198.199,208 in-fjord processes 188 processes 188 fjord-estuary 187,188,200,208 flagellate 198,228,229,249,251,262,269-73, 563-65,606,607 flash flood 587,600 flatfish (see also, specific names) 7,226,347, 348,367.399,403.405,407,408,411,412,418, 420,448,537,542,563,568,607 flathead sole (Hippoglossoides elassodon) 350, 359,372,399,403,408,410 Flattery, Cape (see Cape Flattery) Flavobacterium 222 fledging success 496,499 Flemish Cap 432 flick feeding 533 flounders (Pleuronectidae) 403,418 fluorometer 87,251 Flustrella sp. 371 food chain 7,228,229,233,250,258,386.512, 562,563,565-67,606-8 food web 197,221,237,267,294,367,385,400, 410,486,607,611 Foraminifera 370,371 fore-arc 167,173 foreign fleet 445,579 Forelands, The 9,94,114,120,123,124,133,604 fork-tailed storm petrel (Oceanodroma jurcata) 491,495,505,507,508,514,609 Forrester Island 480.490,501,502,511,542 Fox River flats 610 Fragilariopsis sp. 269 Fraser River 43,198,292,463,466,473 Fraser River delta 488 Fratercula arctica (see Atlantic puffin) F. cirrhata (see tufted puffin) Frederick Sound 482,533.548,568 Freon-11 82 Freon-12 82 frontal system 264,294.381,513 frontal zone 199.563,564,568,606 frost-degree-days 44 Frosty Peak 175 fry 132,197,229,331,462,463 Fuctu 200,327,328,330,331,563,607 F.distichm 328,330 F. sp. 607 fugitive spec ies 326 I- nl warns tfUii i/ilis (sec noil hern fulmar) fulvu .hhI 207 fungi 563,608 fur seal (see northern fur seal) Fur Seal Convention ol 1911 529 Fur Seal Treaty Aci ol 1911 527,529 Fusitriton oregonensii (see Oregon triton snail) Gadidae 348,535 Gadus macrocephalus (see Pacific cod) (,. morhua (see Atlantic cod) gadwall {Anas strepera) 483 GAKline 19.82 Galena Bay 271,363 Gallinago gallinago (see common snipe) gammarid amphipod 313,315,330.409-11, 437,438,485,508,509,511,607 gap wind 31,32,46 gas charging 107,114 gas leasing program 19,578 gastropod 316,320,359,362,370,376,411. 185, 489,509,534 Gavia immer (see common loon) G. pacifica (see Pacific loon) G. slellala (see red-throated loon) Geese Island 609 geographic speciation 428 geohazards atlas 177 geomorphology 7,93,94,96,101.115.120,126, 133,348 geopotential anomaly 67,79 Georges Bank 440,567 GEOSECS (program) 77.79.81,86 geostrophic flow 47.59.61.63.67.188.447 relation 58 wind 33 geothermal energy 588 glacial meltwater 107,189,199,347,382 Glacier Bay 94,106,111,112.115.306.316.533. 548,568,576.586,611 Glacier Bay National Park and Preserve 6,547,576,586 glass shrimp 291 glaucous-winged gull (Larus glaucescms) 495-97,505,507,508,514,609 globe fish (Cyrlopterichthys glaber) 545 Globicephala macrorhynchus (see short-finned pilot whale) Glycymeridae 372,377 Glycymeris subobsoleta 362,366,367,383 Golfingia vulgaris 364 Gonatidae (see also, squid) 535.539.542 Gonatopsis borealis 444 Gonatus fabric! i 444 Good Friday Earthquake of 1964 (see Great Alaskan Earthquake of 1964) Gorgonocephalus caryi (see basket star) Government Hill 173 grab methods (benthic sampling) 348.361 graben 117.173 644 Graham Island 348 Graham, Port (see Port Graham) Gram-negative (bacteria) 222,223 Grampus giiseus (see Risso's dolphin) Grass Island till) ( .i a\ ina Point 362 Gravina, Port (see Port Gravina) gray whale (Eschricktius robustus) 8,528,530. 533,534, (ill grazer effects on phvtoplankton 189.200,251, 256,258,274,287,292,293,295,386,562, 565.ti0ti.ti07 herbivore grazing 250,251,256.258,264. 267.274.287.292,315,326,327,562,565, 606.607 vertical transport mechanisms 254,256, 267,385 zooplankton 250,251,256,264,274,287, 293,567,607 Great Alaskan Earthquake of 1964 6,7,9,101, 115,133,145,146,152.158.172-74,177.306,308, 497,587,600 great sculpin (Myoxoce filial us polyacantho- cephalus) 403,407,408,410 Great Sitkin Island 8,77 greater scaup (Aythya marila) 483 grebe (see individual species) 481,482 green sea urchin (Strongylocenlrolusdroebaihien- sis) 321,323,326,327,335,357,359,369, 545 green-winged teal (Anas crecca) 483 greenlings (Hexagrammidae) 399,405,406, 408-10.412,438,532 Greens Creek Project 582 grenadiers (Macrouridae) 580 groove-throated mysticctes (see rorqual) groundfish 399,417,418,546,579,584,587, 608,611 growth rate 226,254,256,295,316,333,367, 424,430,432,433,437,448,473,537,583,607, 611 Gulf of Alaska Shelf 82,83,85,96,106,107, 109.112.114,132,199,249,347,351,356,567 Gull Island 610 gunnel 410 Gymnocanlhus spp. 403 gyre Alaska Peninsula (Western Subarctic Gyre) 67,434 Cook Inlet 366,387 Gulf of Alaska 6,59,61,62,81,256,258,260, 294.418,422,561 Kayak Island 82,83,113,380,386,387,564 Kodiak Island 443,444 H llaemalopus barhmani (see American black oystercatcher) Haines, Alaska 147,234,235,584 hake (see Pacific hake) half-saturation constant 198 Haliaeelus leucocephalus (see northern bald eagle) halibut (see Pacific halibut) halocline 19,253,255,561,562.564 Halocynthia hilgendorfi igaboja (see also, tuni- cates) 357 Halosaccion glandiforme 330,331 Haptophyceae 565 harbor porpoise (Phocoena phocoena) 420, 537,539,540,610 harbor seal (Phora vitulina richardsi) 325, 420,528-30,540-42,548,581,585,605,609-11 hardshell clam 580 harlequin duck (Hislrionicus hislrionicus) 483,485 harpacticoid copepod 229,294,311,409,563 Harriman Alaska Expedition 18,285,306 Hawaii 7,16,17,39,145,172,173,223 Hawaiian Islands 16,79,532,535 Hayes, Mount (see Mount Hayes) heart urchin (Brisaster townsendi) 348,359, 363,364 heat, latent flux 34,41 Hecate Strait 269,424,562,564 Hedophyllum 328,330,331 H. sessile 328,331 Helwmetra glacialis 362,364 H.glacialis maxima 362,364 H. sp. 362 Hemiaulus sinensis 260 Hemilepidotus hemilepidotus (see red Irish lord) H. jordani (see yellow Irish lord) hemlock 583 HenningBay 152 herbivore 7,200,228,250,256,292,295,315, 330,429,567,606,607 herbivory 315,316,327.330 hermit crab (Pagnrus hirsutiusculus) 363,367, 370-72,382,411,485 herring (see Pacific herring) herring gull (Larus argenlatus) 496 herring roe (see roe herring) Heieromasius filiformis 364 Heteroscelus incanum (see wandering tattler) heterotroph 222,226,228-32,234,236,267 heterotrophic bacteria 222 heterotrophic flagellate 228,229,607 hexadecane 235 Hexagrammidae (see greenlings) Hexagrammos 406,408,438,532 H. decagrammus (see kelp greenling) H. lagocephalus (see rock greenling) H. octogrammus (see masked greenling) H. slelleri (see whitespotted greenling) Hiatella sp. 485 Hinchinbrook Entrance 353,355,356,362, 381,382,386,387,533,605 Hinchinbrook Island 101,106,111,113,114,320, 362 Hippoglossoides elassodon (see flathead sole) Hippoglossus slenolepis (see Pacific halibut) hippolytid shrimp 440,441 Hislrionicus hislrionicus (see harlequin duck) Hobron, Port (see Port Hobron) Hokkaido Island 250,251,419 Hokkaido University 19,80,250,251 Holocene 96,101,106-8,111,113,114,119,128. 131-33,155,174,175,587 holoplankton 200 Homathko River 208 Homer 173 Homer Spit 232,309,372 Honolulu 173 horned grebe (Podiceps auritus) 482 horned puffin (Fralercula corniculala) 502, 504,505,510,511,514,515,609 horsetail (Equiselum) 485 hot spot 149,387,388 Howe Sound 563 Hudson Bay 9,13 humate 207 humic material 200,207 humic-metal compound 207 humpback salmon (see pink salmon) humpback whale (Megaptera novaeangliae) 530,532,533,547,548,568,586,605,611 humpy shrimp (Pandalus goniurus) 363,369, 371,372,440,441 hydrocarbon degrader 235 hydrocarbon utilizer 221,235,236 hydrocast ( = hydrographic cast) 58,60,63 Hydrodamalis gigas (see Steller sea cow) hydrolase 231 hydromedusae 291 hyperiid amphipod 363,508 Hyphymicrobium 222 hypocenter, teleseismic 156,157,159 Hypomesus preliosus (see surf smelt) I ice-scour 316 ichthyofauna 325,399,407,408 ichthyoplankton 407,424,436 Icy Bay 6,47,82,84,101,105,106,108,109,111, 114,115,133,315,349,351,355,359,483,536, 539,587,601 Icy Bay-Malaspina slide area 101,105 IFC drift-bottle program 427 Igvak, Cape (see Cape Igvak) Iliamna Volcano 158 illite 107.117,123,126,129 imbricate faulting 155 incubation period 251,495,497,501,504 index of relative importance (IRI) 507,607 index of stomach fullness (ISF) 508 infauna 306,347,348,350 abundance/biomass 352,353,360,361,363, 366,382-85,387 in diet of invertebrates 375,376,380 distribution 348,350,352,362,376,382, 383,386 ecology 366,367,378,383,566 environmental impact 347,583 species composition/diversity 202,352, 360-63,367,376,378-84,387 infaunal production (see productivity) Insecta 311 Institute of Marine Science (IMS; University of Alaska) 16,77,84,87,187,208,296,388, 576 interannual variation 31,71,293,399,405, 412,467,469,470,474 interfronlal zone 606 Index 645 intermediate water (see Pa< ilii intermediate water) international Convention for the Regulation ofWhaling 529 International Fisheries Commission (IFC) 58,285,417,424 International Fur Seal Treaty (see Fur Sea I Treai\ Acl ol 1911) International North Pacific Fisheries Com- mission (INPFC) 8,23,417,440,444,461, li)2. 164,578 International Pacific Halibut Commission (IPHC) 285,348,424,578 International Pacific Salmon Fisheries ( (mi mission (IPSFC) 578 International Whaling Commission (IWC) 527,529-32,536, 578,58 1 intertidal beaches 399 bench 328,331 Iridaea cornucopiae 330,331 iron, soluble 207 Irving-Williams Series of Complexation 207 sland arc 147,156,374 iij)siiia isolepis (see butter sole) isostas\ 162 sotherin 147,535 isotopes, radioactive "c 81 '"Cc 81 95Nb 81 l06Ru 81 90Sr 81 95Zr 81 isotopes, stable 7Be 81 '2C 81 'K: 81 '5N 128 -"-'-Rn 80 aasRa 86,87 isotopic fractionation 81 Izembek Lagoon 235,483 Izhut Bay 373,376,377,400,406-8 ) Jaccard's Coefficient of Similarity 311 jack (salmon) 464 Jackson Point 318,334 Japan 7.145,169,234,250,258,285,327, 421-24,437. 461-63, 502. 504. 529, 536.541, 545, 578.579.599 [apanese fisheries 424,433,434,462,539 fisheries research 445 human history 9 vessels 18 Japanese pilchard 434 Japanese whaling Meet 581 jellyfish 200. 508. 606. 607 Johnston Strait 473 Jones Act 16 Josenfjord 190 Juan de Fuca Strait 9,13,192,193, 173 Juan tie Fuca Plate I 17.1 18.150 (uneau 307,534,576,583,587 |u\ enile c I. mis 386 cod 122.121 diseases 224 fish, general 50. 274. 295, 387. 101. 103. 107, 111, 413, 120, 145. 449, 563, 607. till fisheries 107, 1 19,464. 174.611 food habits 371.411,449,512,563 greenlings 438,607 habitats 50,413,609 halibut 418.424.425 killer whales 536 king crabs 371.374 other invertebrates 321,367,386,445 pacific herring 411,439.410.512,607 pat ific ocean perch 429,430,432 pollock 294,411,437 sablefish 433,434 salmon 224,274,405,411,418,450,462-64, 474,512,607,609 shellfish, general 316.321,323,367,386. 441,444,449.609,611 Tanner crab 361,370,377,382,609 Kachemak Bay 232 benthos 366-71,383,387 birds 481,485-88,511 chemical oceanography 86,229,230,231, 233-35,267,383 circulation 383 environmental effects 236,237 fisheries 372,402,408,439,608,610 geology 9,367 geomorphology 120,366 human history 15 invertebrates 372 macrophytes 232 microbiology 232-36 phytoplankton 7,265,267 productivity 230,232,309,366,386,563, 606-8 sedimentation 7,126,230,231,235,601 zooplankton 287,292 Kaguyak, Cape (see Cape Kaguyak) Kaiugnak Bay 400, 403, 405-7 Kalgin Island 45,120,126,309,364.366.367, 610 Kalsin Bay 400,406 Kamchatka Current 315 Kamchatka Peninsula 152,165,315,419, 134 Kamishak Bay benthos 367,369-71,383,387 chemical oceanography 235,265.383,386 circulation 383 fisheries 402,408,608 geology 9 geomorphology 120,366 microbiology 235 phytoplankton 7.267 productivit) 366,606-8 sedimentation 7.126.235,601 kaolinite 107.117.123 Kasilol 16 Kasitsna K.i\ 230.231. 23 1.235 Kasitsna Ba) I ,aboi atoi \ 605 katabatic wind 31, 16.47 Katmai eruption 120.174,587 Katmai National Pai k and Preserve 576 Katmai Volt ano 118 Katmai, Mount (see Mount Katmai) KayakEddy 65,73 Kayak Island benthos 355,381,386 birds 482 circulation 82,83,564,603 fisheries 350.359 geology 10C), 107, 154, 165 geomorphology 65 human history 9 mammals 544 microbiology 2.31 oceanography 428 physical oceanography 445 sedimentation 111.113,114,380 Kayak Island gyre 387 Kayak Trough 101,107-9,355,359,386,601 kelp 306,309,377 biomass 327,331 distribution 325,327,331,364,368. 109, 607 in diet ol sea urchins 325 ecology 326.327, 405,410,438,609. (ill i productivity 233,327,331,333,368,608 kelp greenling (Hexagrammos decagrammus) 408,409.438 Kenai Current (see Alaska Coastal Current) Kenai Peninsula 8,187.316 benthos 318,320.348 birds 419 circulation 9,49,60,65,66,73,83,96 fisheries 386,400 geology 94,133,157,159,162,173 geomorphology 120 habitat types 306 human history 16 mammals 541,544 oceanography 172,445,446 pollution 603 productivity 267 sea ice 45,316 sedimentation 124 volcanism 175 Kenai River 586 Kenai Shelf 7,22.249,274 Kennedy Entrance 65,71, 126.366.367. 604 Keta River 189,207 Ketchikan 6,187,271,273,307,576,582-84 Kiliuda Bay 373. 375-77. too. 406. 408 Kiliuda Trough 71,115,117-19,378,379,387, 442,603 killer whale (Orcintu orca) 536,537,5 18,610 king crab (Paralithodes spp.) abundance/biomass 21,369,371,374,375, 377,386 indietoffish 111.133 in diet ol sea otters 547 diseases 228 distribution 371,374,375-78,380,386,610 646 Kim \ fishery 7,371,374,375,377,378,380,448, 579,585,608,610 Food habits 350,371,375-77,380,386,607 life history 371,374,377,443,444 king eider (Somateria spectabilis) 485 knii; salmon {Oncorhynchus tshawytscha) 408, 118.419,429,430,463-67,47:5.586.610 Kitimat 193 kitoi Bay 226 Kittlitz's murrelet (Brachyramphus brevirostris) 199.508,509,610 Klebsiella pneumoniae 227 Knight Inlet 201 KnikArm 584,585 Kodiak Archipelago 7,8,131,132,349,372, 387,400.403,406,407,412,483,499,541,601, 603,605,606 Kodiak Island 8,249.285,306,348,583 benthos 372-78 birds 480-83.485,486,490,497,499,502, 505,506,514,515,582 circulation 6,59-61,63,67,253,264,412, 426,444 diseases 226,227 ecology 313,315,331,352 fisheries 380,403,439,442 fishes 400,436,437,438 geology 9,96,117,131,157,159,162,164,309 geomorphology 94 human history 15 invertebrates 371,440,441 mammals 529,530,532-34,536,537,540, 544,547 meteorology 73 microbiology 225 oceanography 18,44,46,49,405,427,428, 446 phytoplankton 258 sedimentation 129,208,387,601 volcanism 174 Kodiak Shelf 93,94,96,115,117-20,132,133, 260,349,350,374,387,443,606,608 Korea 421,424,433,434,437,439,501,583 Kotzebue-Lentz Expedition 17 Kruzenstern 17 Kruzof Island 174 Kupreanof 176 Kuril Islands 543 Kuroshio Current 62 Kuroshio water 256 Kvichak River 469 Lacuna variegata 485 Lagenorhynchus obliquidens (see Pacific white- sided dolphin) Lagoon Point 313,318 lahars (volcanic mud flow) 175 Lakelliamna 466,470 LakeNitinat 207 Laminaria groenlandica 326,327,331,333,607 /.. longipes 326,330,331,333 L. sp. 607 L. spp. 231,325,326,364 lamprey {Lampetra sp.) 532,563 lancet fish (Alepisaurusferox) 535 Laqueus sp. 362,364 Larus argentatus (see herring gull) L. carats (see mew gull) L. glaucescens (see glaucous-winged gull) larvacean 288,290,295,409 larval fishes 294,295,399 Latouche Island 318 Latouche Point 320,331,333,335 lava flows 175,176,600 Leach's storm petrel (Oceanodroma leucorhoa) 491,495,505 least auklet (Aethia pusilla) 499,502 least sandpiper (Calidris minutilla) 486,488 leatherfin lumpsucker (Eumicrolremus derjugini) 402,403 Lee Wang Zin (shipwreck) 582 Leopold Matrix 599 Lepidopsetta bilineala (see rock sole) Leptocottus armatus (see Pacific staghorn sculpin) lesser Canada goose (Branta canadensis parvipes) 482 light extinction coefficient 251,255 measurement 251 saturation 260 Ligia pallasii 330 Limacina helicina 289,290 Limanda aspera (see yellowfin sole) Lirnnodromus griseus (see short-billed dowitcher) L. scolopaceus (see long-billed dowitcher) limpet (Notoacmea spp.) 325-27,489 Lindaspollene (see poll) lingcod (Ophiodon elongatus) 400,409,413, 417,438 lipid reserve 287 liquid limit 129 Lissodelphis borealis (see northern right whale dolphin) listric thrust fault 161 litharenite 107 lithosphere 94,146,147,150,156,159-61 lithospheric plate 93,101,132 litter, marine 575,581,584,585,588,608 little piked whale (see minke whale) littoral zone 200,306,316,327,335,608 Littorina aleutica 330 L. atkana 330 L. scutulata 327 L. sitkana 320,327 L. spp. 331 Lituya Bay 101,106,107,111,115,152,155,172, 349,359,587 Loch Etive 202 log rafts 583 Loligo opalescens 444,445 long-billed dowitcher (Lirnnodromus scolopaceus) 488 longfin smelt (Spirinchus thaleichthys) 408 longsnout prickleback (Lumpenella longirostris) 403 loon 481,482 Low Cape 313,315,316,318 Lower Cook Inlet (see Cook Inlet) Lull, Point (see Point Lull) Lumbrineris sp. 364 Lumpenella longirostris (see longsnout prickle- back) Lumpenus medius (see stout eelblenny) L. sagitta (see snake prickleback) lumpfish 535 lunge feeding 533 Lulra canadensis (see river otter) lymphocystis 226,227 Lysiclutum americanum (American yellow skunk cabbage) 485 Lysippe labiata 380 M mackerel 7,294,350,417,422,438,533,539, 580,607 Macleod Bay 335 Macoma balthica 308,489 M. brota 364 M. calcarea 367 M. spp. 372,376,377 macrobenthos 363,386,586 biomass 7 Macrocystis pyrifera 331 macrophagus detritivore 315 macrophyte abundance/biomass 7,200,231,309,368, 486,563,565,608 distribution 200,309,331.565 ecology 200,231,309,331,486,608 production 563,607,608 species composition 331,368,411,607 Macroui idae (see grenadiers) macrozooplankton 249,251,256,264 magnetic bight 148 magnetic lineation 148 Magnuson Fishery Conservation and Manage- ment Act (see Fishery Conservation and Management Act of 1976) MakushinBay 310 Makushin Volcano 176 Malaspina Glacier 6,9,47,93,101,105-9.111, 113,114,351 Malaspina, Alessandro (see explorers) mallard duck (Anas platyrhyncos) 483,485, 605.610 Mallotus villosus (see white capelin) mammals gestation 531-33,535-39,545 haulout 540,541,544 rookery 599,609,611 Mann-Whitney U-Test 323 mantle 106,146,147,149,150,156,157,159,161, 319 marbled murrelet (Brachyramphus marmoratum) 499,505,509,510 mareography 177 Margarita pupillus (see puppet margarite) Marianas Islands 532 mariculture (see aquaculture) marine agar (2216) 222,223 Index 647 Marine Mammal Protection Act (MMl'A) 527,529,546,547,578,581 marine OlUStelid (see, for example, sea otter) 8,527,528,530 Marine Prolci lion, Rescan h. and Sam mai ies Ad 578.612 Marine Resources Monitoring. Assessment, and Prediction (MARMAP) H7.441 Marmot Ba\ 537 Marmot Island 609 marsh grass 238,563 Martin River 232 masked grcenling [Hex/igrammos tit togra mm us) 408,409 mass balance 204,207.249.251,27 4,295,605 Matanuska River 124.126 maximum significant wave height 96,601 maximum sustainable vicld (MSY) 529,546, 611 McClureBaj 349,363,382 McKinlev, Mount (see Mount McKinlev) medusae 290,291,563 Megaptera novaeangliae (see humpback whale) megazooplankton 256 meiobenthos 386 meiofauna .'508.347,353,386,566 Melanitta fusca (see white-winged scoter) ,\/. nigra (see black scoter) M, perspicillata (see surf scoter) Melinnu cristata 364,382 Melosira sulcata 270 meltwater 9,107,112.113.115,131,133,189,199, 347,382 Mendenhall Glacier 6,268 Merchant Marine Act of 1920 16 Mergus merganser (see common merganser) Merluccius product us (see Pacific hake) meroplankton 202,292 mesocosm 200 Mesoplodon stejnegeri (see Bering Sea beaked whale) metabolic rate 512,530 Metridia lucens 531 M. okhotensis 292 .\/. pacified 287,289,291 Metridium senile 359,375,377 mew gull (Larus canus) 496,507,508 Mexican Coast 532 microaerophilic marine environments 234 microalgae 327,607 Microcladia borealis 330 Micrococcus 228 Microcyclus 222.223 microflagellate 249,262,270,564,606 microflora 237,347,353.386,566 Mirrtigadus proximus (see Pacific tomcod) microheterotroph 228,229.234 micronekton 286,290,291,295 microsporidian 371,443 Microtia spp. (see vole) microzooplankton 249,251,256,274,286, 292,567,607 mid-ocean ridge basalts (MORB) 150 mid-oceanic ridge 148 mid-water trawl 401.445 Middle Albatross Bank 115.117. 118.120.377 Middle Bank 355. 357. 359. 381) Middleton Island 106,107,113,114,154,168, 180, 183, 197. 199,502,511,513,536,546,609 midlillor.il /one 316.327 migration birds 7.179. -181-83. 186-89. 609,610 mammals 528,530.532-35.537-10.5 12. 609.1)11 non salmonid fishes 421,424, 130. 431. 137, 139.440,443,444,445.537 salmon 462-64,467, 169, 170,473,537,609 vertical (fish) 121.432 vertical (zooplankton) 201.291,387.405, 420,432 zooplankton 201.202. 291. 295, 421 Milrow detonation 310,328 mill 38,43,49,118,129,202,274,400,437,439 mineralization 84,203,233,234,236 Minerals Management Service (MMS) 23, 50,73,177,208,237,275,296,388,413,450, 474,516,548,568,578,612 minke whale (Halaenoptera acutorostrata) 530, 535-37 Miocene (period) 94,115,131,133 Mirounga angustirostris (see northern elephant seal) Mississippi River 583 Misty Fjords National Monument 576 Mitrella gouldi 359,362,377 mixed layer 188,191,251,255,258,265,268, 290.561,562 mixed-stock fishery 464 mixingrate 86,254 Moho 161 Mollusca (see mollusk) mollusk 444,535 abundance/biomass 7,355,360,361,362, 364,366,367,369,370,372,374 in diet of birds 509 in diet of invertebrates 362,372,386 in diet of mammals 535 distribution 310,313-15,333,351,355,362. 363,367,382 ecology 327,330,348,367,372 fishery 15,272,440 toxicity 19,272 molybdenum 307,582,598 moment-magnitude scale 152 Monodon monocerus (see narwhal) Montague Bay 598 Montague Island 9,94,96,106.111.114.117.132. 152,162.173.306,320,335,537 moose 586,610 Moraxella 223 Moroteuthis robusta (see also, squid) 444 mortality 292.320.321,327,328,330.367. 132. 437,438,443,444,447-50,473,474,495,514, 546,548,585 Mount Augustine 7,120,587,600.601 Mount Blackburn 150 Mount Bona 150 Mounl Denali 152,156,163 Mount Drum 150 Mount Edgecumbe 150,163,176 Mount Fail weathei 6,9 Mount I laves [50 Mouni Katmai 17 I Mount \I( kmlcv 8,150,161 Mount Pavlol 0 Mount Redoubt 174-76,587 Mounl Regal 150 Mouni Sanford 150 Mounl Spun 150,174.175 Mount St. Elias 6,9.113.156 Mount St. Helens 174.587 Mount Veniaminof 175,176 Mount Vsevidof 175 Mount Westdahl 170 Mount Wrangell 94,149,150,156,161,174 mousse 605 mud star (Ctenodiscus crispatus) 348,355-57, 359,361-64,373 Muir Inlet 115 Muir, John 18 multiple-use conflict 575,579,587 multispecies numerical model 611 municipal discharge 581 municipal waste 575,584,585,588 Musculus discors (see discord mussel) M. vernicosa (see mussel) 545 mussel 13,308,316,320,321,325,327,377,485, 515,545,567 mustelid 8,527,528,530,543 Mutnaia Gulch 371 Mya spp. 377 myctophid 445,539,567 Myctophidae (see myctophid) Myoxocephalus jaok (see plain sculpin) Al niger (see warthead sculpin) M. polyacanthocephalus (see great sculpin) M. scorpius (see shorthorn sculpin) M. spp. 407,408 Myriochele heeri 362.364 M. occulata 364 mysid 294,485,509-11,534 Mytilidae 371 Mytilus californianus 305.320,334 M.edulis 305,315,316.320.321. 323. 325. 327,331.334.485,489 N n-alkane 235 Nanaimo River 207 nanoplankton 228,229.258 Nansen bottle 578 naphthalene 235 Naptowne glaciation 131 Narragansett Bay 233.234 narwhal (Monodon monocerus) 537 Xatica clausa 359,377 N. spp. 363 National Academy of Sciences 587 National Environmental Policy A< t ol I960 (NEPA) 582,597,598 National Marine Fisheries Sei vice i \ \l 1 S i 19,275,307,348,388,400,417,534,536,548, 578,598 648 Index National Ocean Pollution Research and Developmental and Monitoring Planning Act 578 National ( )i cum and Atmospheric Admin- istration (NOAA) 19,21,23,41,46,47,49, 50,58,73,87,132,173,177,208,237,275,286, 296,388,413,417,443,450,474,516,548,568, 575,578,583,597,598,607-9,612 National Park Service 548 National Pollutant Discharge Elimination Sys- tem (NPDES) 584 natural mortalit) 333,432,437,438,447,449, 474 natural selection 474 nauplii 292,294,295,319,409,424,439 Navarin, Cape (see Cape Navarin) Near Islands 380 near-field volcanic hazard 587 nearshore /one 107. 114, 399.400, 407, 409. 41:5.505 nekton 17.197,291,295,424,429.546 Nelson Bay 349 nematode 228,229,311,563,608 nemertean worm 311,371,374 Neocalanus cristatus 287,288,293,295,385, 531,565,606 N.plumchrui 201,256,290-93,532,563,606, 607 N. spp. Neomolgus littoralis 330 nepheloid layer 111,129 Nephtys punctata 364,382 Nereocystis luetkeana 326,331,607 N. sp. 607 neritic species 270,287,288,290,292,531 nestling clam (Saxicavidae) 372,380 net photosynthesis 255 neuston net 401,407 New England Coast 431 New York 16,18 Newfoundland 432,515 Nikiski 270,582 Nikolski 16 Ninilchik 16 Ninilchik, Cape (see Cape Ninilchik) nitrate concentration 6,19,78,199,203,235,254, 256,258,265,267,268,274,565 cycling 50,80,233-35,251,254,258,264, 265,268,271,274 distribution 78,80,199,203,254,264,265, 267,271,274 nitrogen acid rain 585 concentration 233,236,268,269,382 cycling 84,221,233-35,251,258,267-69.274 distribution 267,382 fixation 233,235 nitrogen cycling 221,233,234 nitrogen fixation 233-35 nitrogen-15 (15N) 198 Nitzschia 269 Nixon. President Richard M. 19.233.234, 598 NO* index 206 NOAA Ship Discoverer 47,237,388 NOAA's Status and Trends Program 583 nodal plane 159,160 nomogram 44,603 non-point source pollution 581,585,588 normal fault 159,161,164 NORPAC (see North Pacific Oceanographic Program) North Albatross Bank 377,603 North American Plate (NAM) 145,149,150, 152,156,162,163,600 North American salmon 7.461,462,465,474 North Carolina 233 North Pacific Current 6,9,59,253,504 North Pacific Fur Seal Commission 578 North Pacific High 82 North Pacific Oceanographic Program (NOR- PAC) 17,19,77,79,86,285,286 North Pacific Oscillation Index (NPO) 38, 43,296,580 North Pacific Rim 541 North Sea 432,441,449,567,608 North Slope 576,582 Northeast Gulf of Alaska (NEGOA) Shelf 294,348,351,353,381,382,385,386 Northeast Gulf of Alaska (NEGOA) 8,9,21 benthos 348,349,351,353,355,360,378, 380-82,384-86 fisheries 355,378,386 geomorphology 96,107,384 microbiology 223 seismicity 156,157 zooplankton 287,288,294,385,386 northern bald eagle (Haliaeetus leucocephalus) 495,514,610 northern elephant seal (Mirounga angustirostris) 530,545 northern fulmar {Fulmarus glacialis) 491,493, 505-507,511,514 hatching success 495-97,499 northern fur seal (Callorhinus ursinus) abundance 527,541-43,580,581 biology/life history 541-43 distribution 528,530,541,542 food habits 440,445,543 harvest/management 528,578,580 resource conflict 546,585 treaty 527,529,543,544 northern pintail duck (Anas acuta) 7,479, 483,610 northern right whale dolphin (Lissodelphis borealis) 545 Northwest and Alaska Fishery Center 578 northwestern crow (Corvus caurinus) 495 Norton Sound 232,442,499,539 Norwegian coast 6,190,200 Norwegian Coastal Current 73 Notoacmea scutum (see limpet) N. persona 327 Nova Scotia 197,199,203,233,607 Novarupta 174. 600 Nucella ( = Thais) 316,320,321,323 N. lamellosa 316 N. lima 316,321 Nucula tenuis 362,367,372,376,377 Nuculana fossa 362-64,367,372,375-77,386 N. sp. 363,364,382 nuees ardente (see also, volcanism) 600 NukaBay 94,115,133 Nunivak Island 424,496 nursery 49,50,197,367,370,371,387,403,405, 424,461-563 nursery areas 50,197,405,461,462,563 Nushagak River 463,469,473 Nushagak/Togiak 469 nutrients depletion 263,362,363 inorganic 604 limitation 250 •new' 198,199,203 supply 7,203,264,513 nutritional versatility index 225 o Ocean Cape 19,426,427 Ocean Station P (see Canadian Ocean Weather Station P) Ocean Station Papa (see Canadian Ocean Weather Station P) Ocean Weather Station P (see Canadian Ocean Weather Station P) oceanic plates 146,147,150,152,157,161 Oceanodroma furcata (see fork-tailed storm petrel) O. leucorhoa (see Leach's storm petrel) Ocella 491,495 O. dodecaedron (see Bering poacher) OCSEAP 7,9,21,57,63,82,83,156,168,177, 237,250,274,296,306,307,310,347-49,355, 360,371,399,417,418,440,441,445,446,480, 548,582,598,607,612 octopus 369,444,538,541,542,545 odd-year run 463 Odobenus rosmarus (see Pacific walrus) Odonthaliafloccosa 331 odontocetes 535,537 Odontogena borealis 364 Oenopota sp. 359,377 offshore mining 347 Oikopleura spp. 289-91,295 oil and gas development environmental issues/studies 9,19,578, 581,582,597,598,601,604 leasing program 19.578,597,598,601 marine pollution 235,575 production 581.582,587 oil and gas lease sale 597,601 oil-spill trajectory 597,604 Oithona helgolandica 291 O.similis 291,292 0. spp. 606 Okmok (volcano) 176 Old Crow (tephra) 174 oldsquaw (Clangula hyemalis) 483,485,486, 605 Olga Bay 375 Oligochaeta 311 oligotroph 222,224-26 OlsenBay 308 Index 649 omnivore 315 on-shore convergence 190-92,203 Onchidoris bilamellata 321,323 Oncorhynchm (see l'.u ifi< salmon) O.gorbuscha (see pink salmon) 0. keta (see chum salmon) 0. kisuli It (see coho salmon) (). nerka (sec soi kevc salmon) (). spp. 399,438,461 0. tshawytscha (see king salmon) onshore- mining project 582 (hi\rhoteuthi\ boreal i juponii us 111 open-access resource 586,588 Ophiodon elongatus (sec lingcod) Ophiura sarji (sec brittle siai i 0. spp. 380 ophiuroid 348,361,362,370,377;380 opportunistic feeder 538 optimum sustainable population (OSP) 529 optimum yield (OY) 580,611 Orcalnlci 308,546 Orchestia sp. 330 Orcinusorca (see killer whale) Oregon 9,36,227,432,463,474,483,539,542 coho salmon 463 Cook's voyage 9 hatcher) salmon stocks 474 marine mammal ranges 539.542 Pacific ocean perch 432 storm tracks 36,37 Vibrio in crabs 227 waterfowl wintering 483 Oregon ti iton snail (Fusitrilon oregonensis) 380 organic material labile 203 particulate carbon 232.258 particulate flux 251 particulate material 84,2(17,251,258,268 particulate organic carbon (poc) 127, 156,157.159,207.262.363.364,378.382, 388 particulate organic material 199 organo-metallic bonding 207 orography 37,604 oscillators tidal How 427 Osmeridae 532 Osteichthys 286 ostracod 289 Otariidae 541 Otter trawl 373. 403. 406. HO, 111, 421 Outer Continental Shelf (OCS) (see continen- tal shelf) Outer Continental Shelf Lands Act 578,612 ovovivi parous 430,432 ovulation 4 40,531). 540 oxygen minimum 6,77-80 Pacific cod {Gadus macrocephalvs) 7.348,350. 370.372.37 t. 399. 403. HO, 117. 418.420. 122 2 4.430.432,434.443.512.542,607 Pacific hake (Merluccim pi mint tus) 350.420. 430,538.563 l'.u ilu halibut (HippOgloSSUS stentilepts) abundance 403,408 distribution 357,42 1,441 fishery 7,399,412,418,421,424,425,433, 138,579,585,605,608-10 life history 19,418. 122.425-28. 132. 13 1 predation 370,372.371,143.607 resout i c management 285.3 18,578,611 l'.u ilk herring (Clupea harengiu pallasii) 50, 197,294,295,399,400, 106, 108-12,417,418, 432.434, 437-40, 511, 512. 533, 534, 536-39, 5 12. 543,546,563,568,579,607-10 Pacific Intermediate Water 19.77-79.81,82, 86.190,193,202,434 Pacific Islands 486 Pacific littlenec k clam {Protothaca Uaminea) 485 Pacific loon (Gavia pacifica) 481,482 Pacific mackerel (Scomber japonic u\) 533.580 Pacific Ocean alkalinity budget 82 Pacific ocean perch (Sebastes alutus) 7.417, 418,421,422,429-32,434,436.437,443,448, 450,579,611 Pacific Oceanographic Group 19 Pacific Plate 6.145,148-50,152,156,158-61,163. 164,168.600 Pacific pollock (see Alaskan pollock) Pacific right whale (Balaena glacialis) 8.420, 529,530,532,545 Pacific Rim 146,433,541,583 Pacific salmon (Qncorhynchus spp.; see indi- vidual species) 399,412, 417, 438, 461, 462. 578,607-11 Pacific sand lance (Ammodytes hexapterus) abundance 405-8 conflicts 512,586 in diet of birds 376,485,508,509,511,515 in diet of fish 410,411 in diet of mammals 376,532,536,539,543 distribution 405-8,412 fishery 568,580 food habits 409,411.412,1)07 life history/ecology 405-7,512 Pacific sandflsh (Trichodon Irirhodon) 405, 406 Pacific staghorn sculpin (Leptocottus armatus) 408 Pacific Subtropical Gyre 62 Pacific tomcod (Microgadus proximus) 408 Pacific walrus (Odobenus rosmarus) 420,528, 530,537,545 Pacific white-sided dolphin (Lagenorhynchtt.s obliquidens) 420,538 Pacific whiting (see Pacific hake) Pagurus hirsuliusculus (see hermit crab) P. ochotensis 371 P. spp. 362 Palache, Dr. C:. 18 Palmaria palmata 331 Palmer. Alaska 115.173.486.505 Pamplona Ridge 107,170 PamplonaSpur 101,106,107,113 Pamplona Trough 96,101 pandalid shi imp 202,348,350,363,366,369, 371,372,374,377,386,387,399,419,440-42, 511,512,579,610 Pandalidae 3 18.301,. I io Pandalopsis dispai (sec sidesti ip<- sin imp) Pandalus borealii (see pink sin imp) /'. goniw us (see humpy slu imp) /'. hypsinotui (see coonstripe shrimp) P. Jordan i I 1 1 /'. montagui tridens 111 P.platyceros I 11 P. stenolepis 140 Pandora gt andi s 367 papillomatosis 226,227 ParacaUmus parvus 200.291 Paracallisoma alberti 508 Paraclunio alashensis 330 parakeet anklet {Cyclorrhynchus psittacula) 199,502,509,510,51 1 Paralithodes camtschatica (sec red king ( i ab) P. platypus (see blue king crab) paralytic shellfish poisoning (PSP) 13.273 parasitic copepod 532 Parasitus sp 330 Parathemisto libellula 363 /'. pacifica 289 Parophrys vetulus (see English sole) parturition 430,539,541,545 Pasiphaea pacifica 291 pasiphaeid shrimp 441 past consolidation stress 109 patchiness 264,295 pathogenicity test 228 Patton Bay Fault 162,163 Pavlof (volcano) 6,158.176 Pavlof, Mount (see Mount Pavlof) pea crab (Pinnixa occidentalis) 380 Pecten caurinus (see weathervane scallop) Pectinidae 372,378 pelagic bird 437,512,605,607 pelagic cormorant (Phalacrocorax pelagic us i 495,508,514 pelagic fish 7.197,294.295.403.409. 411.438. 440,445,511,568 pelagic fish eggs and larvae 50.420 pelagic harvest 580 pelagic trophic structure 606 pelagic zone 291,405,609 petrale sole {Eopsetta jordani) 430 Petrel Island 495 petroleum hydrocarbon pollution 581 petroleum production 581.599 petroleum spills 581 Peulik (volcano) 176 Phaeocystis pouchetii 262,270,271 phaeopigment 200 Phalacrocorax auritus (see double-crested i "i morant) P.pelagicus (see pelagic cormorant) P. penicillatus (sec Brandt's ( ot mm ant I P. utile (see red-faced cormorant) Phalaropus lobatus (see red-necked pha- l.irope) Phascolion Urombi 36 t phenolog) 479.480. 191,51 1,516 Phoca vitulina rit hardsi i sec hai bor seal) Phocoena phocoena (see harbor porpoise) Phocoenoides dalli (see Hall's poi poise) phosphatase 231.232 650 Index phosphate 6,19,233,236,251,254 photoperiod 463 photosynthesis 228,231,251,255,260,264, 267,268,561,562,607 Physeter catadon (see sperm whale) P. macrocepludus (see sperm whale) phytane 235 phytodetritus (see also, detritus) 566 phytogenous material 197,200 phytoplankton 249-82 abundance/biomass 18,200,232,251,254, '-»:>s.267,269,271,291-93,383,430,562,563, 566,567,606-8 blooms 50,200,225,229,230,232-34,287, 288,291,383,486,513,514,562,565,606, 607 in diet of zooplankton 287,292,293,295, 526 distribution 287.562,567,606.608 ecology 287,292,293,512,562,563,566, 567,606-8 nutrients 513,563 production 7,188,197-200,202-4,221,233, 249,251,255,263,265,267,268,273,274, 285,287,295,383,606 sinking rate 256,267 size distribution 258 studies/sampling 295 piedmont glaciers 113 pigeon guillemot 499,505,508,509 pigment budget 251,256 pilot whale 420,545 pink salmon (Oncorhynchus gorbuscha) 197, 295,405,408,409,463-65,467-69,473,578, 610 pink shrimp (Pandalus borealis) 350,355,357, 361-63,374-76,380,440,441,607 pinkneck clam (Spisula polynyma) 367.371, 377.485 pinniped 8,445,527,528,530,540,541,546, 548,581 Pinnixa occidentalis (see pea crab) pintail duck (see northern pintail duck) pioneer species 316 Pisaster ochraceus 305,320,334 plaice 432,437 plain sculpin (Myoxocephalus jaok) 407 planktivorous fish 295,567,608 planktonic Crustacea 445,511 planktonic decapod 534 Planktoniella sol 260 plantigrade 321,323,327 plastic limit 129 plasticity index 108,111,129 plate count 221 Platichthys stellatus (see starry flounder) Platyhelminthes 311 Pleistocene (epoch) 7,93,94,96,106,113,115, 117.119,128,129,132,162 pleomorphism 224 Pleurobrachia sp. 607 Plenrogrammus monopterygius (see Atka mackerel) Pleuronectidae 348,418,420,537 Pod/reps auritus (see horned grebe) P. gri.segeria (see red-necked grebe) Pododesmus macrochisma (see rock oyster) Potion sp. 290,295 Point Barber 320,335 Point Kllrington 545 Point Lull 545 Poisson model 170,172 poll 196,199,200,563 pollock (see Alaskan pollock) pollutant transport 597,599,603 pollution 226,335,347,575,578,581-85,588, 611,612 Polychaeta (see polychaete) polychaete 291,313-15,333,351,359-64,367, 370-73,376,377,380,382,386,399,410,411, 534 Polydora ciliata 359 Polysticta stelleri (see Steller's eider) pomfret (Brama japonica) 445,567,580 Porifera 311 Porphyra sp. 316,327,330,331 porpoise 420,445,527,530,537,539,540,546, 548,605,610 Port Dick 316 Port Etches 349,362,382,386 Port Graham 172,175 PortGravina 349,362 Port Hobron 581 Port Nellie Juan 363,382 Port Valdez 9,84,85,115,172,190,191,197-99, 201,235,236,267,273,308,316,318,319,321, 323,335,349,361,363,381,382,386,582,587, 598,599,604,608 Portlock Bank 65,115,117.377,387,438,536, 538,542,564 Pratt Seamount 59 predation 374,444,447,449,450,496,610 apex predator 7,386,515,566-68,606,608, 609 by birds 497 by fish 429,430,443 by invertebrates 321,323,327,357,371,438 by mammals 315,327,438,497,585,586 effects on birds 496,497,499,514 effects on crabs 443 effects on community structure 319,320, 448,449 effects on fish eggs and larvae 438 effects on fish stocks 432,580 in subtidal communities 315 on benthic invertebrates 316,586 predictive fisheries model 274 pressure gauge 603 gradient force 45 ridges (geologic) 173 ridges (meteorologic) 34,37,39,50 transducer 94 prey 8,208,229,319-21,323,325,327,347,359, 361,362,370,371,375-78,380,382,411,429, 435-39,445,447-50,479,485,490,506-12,515, 516,531-33,535,537,538,541-43,545,546,548, 563,565,567,580,586,606,607 Pribilof fur seal (see northern fur seal) Pribilof Islands 424,426,493,499,529,542, 581 primary plates 146 primary production 7,19,22,80,187,188,197, 200,202-4,221,228,232-34,249-51,255,263, 267,268,273,274,285,287,288,292,293,295, 309,331,333,366,369,382,383,385-87,512, 513,562-68,606-9 Prince Rupert 191 Prince William Sound 8,9,19 benthos 306 biological productivity 355,356,563,607, 608 birds 481-83,485,495,499,509 environmental studies 306,529,580-82, 586,587,598 fisheries 439,441,442,464,465,546,580, 586 fishes 400,402,408,411,412,418,439,463, 465,485,509 geological oceanography 94,96,106 geomorphology 382 human history 15 invertebrates 306-8,316,318-20,327,328, 335,355,356,361-63,381,382,411,441,442, 485.547,586 macrophytes 331,333,607 mammals 529,530,532,533,536,537,539, 541,544-48,586 microbiology 231,235 phytoplankton 249,264,267,270 physical oceanography 19,67,73,83,85, 191,316,318,319,381,382,427,441,445,604 sea ice 45,316,319,601 sedimentation 111,113-15,132,231,319,381, 382 tectonic activity 6,149,152,154-56,162,168, 172,327,587 zooplankton 7,200,201,264,285,291,292 Prince William Sound Earthquake 154,155, 162,168 pristane 235,236 Procellariiformes 491,495 prodelta 101,105-7,114,208 production-to-biomass (P/B) ratio 567,568 productivity infaunal 347,353,357,385-87 phytoplankton 199,233,249,255,265,606 secondary 273,292,293,513 'new' 251 progradation 124,128 prograde 115,131 protection stock 529 protobranch 351,362,363,386 Protogonyaulax 273 Protothaca staminea (see Pacific littleneck clam) Protozoa 286,563,607 Psephidia lordi 377 Pseudocalanm 200,288-92,294,295,606,607 P. minutus 200,606,607 Pseudoeunotia doliolus 260 Pseudomonas 221-23 Pseudoscorpionida 311 Psittichthys melanosticus (see sand sole) Psolus chitinoides 362 pteropod 82,286,289-91 PtUosarcus gurneyi (see sea pen) Ptychoramphus aleuticus (see Cassin's auklet) Puale Bay 609 Index 651 puffin 295,499,502,504-6,510-12,514,515, 605,609, (ill Pu//inusgriseus (see sooty shearwater) /'. trmtiro\tri\ (see short-tailed shearwater) Puget Sound rockfish (Sebastes emphaeus) 409 Pugettia gracilis 410 puppet margarite (Margarita pupillus) 485 purse seine 467,580 pycnocline 60,200,561-63 Pycnopodia helianthoides (see sunflower sea star) Pygospio elegans 359 pyroclastic flow 165,587,600,001 Q-mode factor analysis 117 quadrat 307,311,318,335 qualitative interaction matrix 599 Quart/ Hill open-pit molybdenum mine 582 Quaternary 101,106.150.101.174 Queen Charlotte Islands 8.146-49.249,269. 353,427.505 Queen Charlotte Sound 564 Queen Charlotte-Fairweather Fault System 145 Queen Elizabeth 9 railbelt 576,587 Rajidae (see also, skate) 535 rattail (Coryphaenoides spp.) 535 razor clam [siliqua patula) 308,309,512,580, 586,608,610 recolonization 315,326 recruitment 200-2,308.316,321,323,326,374. 417,422,438,444,447-49.611 red fox (Vulpesfitlva) 490 red Irish lord {Hemilepidolus hemilepidolus) 350,399.409.545 red king crab (Paralithodes camtschatica) abundance/biomass 369,376,442-44 in diet of fish 443 diseases 443 distribution 350,364,374,376,442,443 fishery 348,364,374,387,440,442,443 food habits 269,350,367.371 life history 374,442.4 '3 red knot (Calidris canutus) 488,489 red salmon (see sockeye salmon) red tide 272 red-faced cormorant {Phalacrocorax urile) 495,514 rednecked grebe (Podiceps grisegena) 482 red-necked phalarope {Phalaropus lobaliis) 486 red-throated loon (Gavia \tellata) 481 redfish 431.432 Redoubt, Mount (see Mount Redoubt) refractive index 117.118 Regal. Mount (see Mount Regal) regenerated ammonia 198 relative vorticity 37 relict 93.113.124.125 remineralization 84,203 reproductive biology 424, -125. 130,433, 437-39,441,443,445,491,502,530,538,539 reproductive cycle 533-36 reproductive potential 462,474,535 reproductive success 49,227,479,480,491, 493,495-97,499,504,514,515 residence time 65,86,189,197-200,203,207, 366,383,386,388 Resurrection Bay 19,82-86,115,190,194,195, 197,199.204,205,207,267,273,308,350,363, 364,382,486 rhinoceros auklet (Cerorhinca monocerata) 502,510,511 Rhizosolenia alata 262 R. hebatata I. hiemalis 260 R. styliformis 262 Rhode Island 233 right whale (see Pacific right whale) Rissa tridactyla (see black-legged kittiwake) Risso's dolphin (Grampus griseus) 545 river otter (Lutra canadensis) 490,497,530 rock greenling (Hexagrammos lagucephalus) 406,409,410 rock oyster (Pododesmus macroschisma) 545 rock sandpiper (Calidris ptilocnemis) 486,487 rock sole (Lepidopsetta bilineata) 226,350, 372,399,403,407-10 rockfish (Scorpaenidae) 400,402 abundance 400,412,418,428,429,431 distribution 403,408,409,431,432 ecology/life history *30-32 fishery 348,413,434 food habits 411,430,445,450,532,535,542 Rocky Bay 349,36? roe herring 418 rorqual 530,532,533 Rossby Radius of Deformation 46 Rossia pacifica (see also, squid) 360 ruddy turnstone (Arenaria interpres) 488 Russell Fjord 6,85,206,293 Russell's model 447 Russia 8,13,15,16,19,94,154,433,527,529,543, 576.579,580,581 Rvuko Island 532 Saanich Inlet 205,206,233,236 sabellid polychaete 372,380 sablefish (Anoplopoma fimbria) distribtuion 350,433,611 ecology/life history 418,420,432-34 fishery 7,433,579,611 food habits 512 sac roe (herring) 418,439 saccharolytic 225 Sadie Cove 233 saffron cod (Eleginus gracilis) 533,538,539 Sagitta elegans 289,292 Saguenay Fjord. Quebec 208 Salix sp. (see willow) Salmo clarkii (see cutthroat trout) S.gairdnerii (see steelhead trout) salmon 226,229,418,419,438 artifically propagated 580 fry 197.229 harvest 579 industry 579 juvenile 007 research 444.461.462 run 461,464-66,473,474,586 tower count 464 salp 256,327 Salvelinus malma (see Doll) Varden trout) Sanak Island 373,544 sand dollar (Ei bniarai liiini\ par ma) 348.366. 367.369,372,377,383 sand lance (see Pacific sand lance) Sand Point 67 sand sole (Psittichthys melanosticus) 407,408 Sanford, Mount (see Mount San ford) Santa Barbara 424 sardine (Sardinops sajax) 532 Sardinops sajax (see sardine) Saunderia marinus 330 saury (Cololabis saira) 533 Saxicavidae (see nestling clam) Saxidomus giganteus (see butter clam) scallop (Pecten spp.) 347,348,359,360,369, 377,381,419,440,605 scavenger 315,355,357,359,368-71,374,375, 377,584 Scolecithricella minor 290 S. ovata 289 Scoloplos armiger 373 Scomber japonicus (see Pacific mackerel) S. scombrus (Atlantic mackerel) Scorpaenidae (see rockfish) Scotch Cap 172 Scotland 200,316,607 sculpins (Cottidae) 350,370,402,403,40710. 412,418,485,538,542 sea cucumber 362,363,369,377,485 sea lion (see California or Steller) sea otter (Enhydra lutris lulris) 306,307,315, 320,323,325-27,420,527-30,543-48,580,581, 586,605,609,610 sea pen (Ptilosarcus gurneyi) 353,362,363, 367,374,377,378 sea stack 328,499 sea star (Evasterias troschelii) 307,327,350. 357,359,360,362,376,377,380,386,545 sea surface temperature (SST) 17,432,473 sea urchin (see also, individual species) 15. 307,316,320,321,323,325-27,357,359,369, 380,409,419,545,566,568 sea-level pressure 31-33.37,38,46 seal 561,605 abundance/biomass 420,541,547.548.609. 610 in diet of marine mammal 537,542 distribution 530.540,541.545.546.609, 610 ecology/life history 325,540,568,610,611 food habits 440,445,541.543.547.611 harvest/management 529.543,578.580. 581 resource conflict 546,585 652 seamoimt 18.59.79,117.148,504 Seattle 16,81,296,399,413,474,578 Sebastes 408.409.411,418,428-32,532 S. alutus (see Pacific ocean perch) S. ciliotus (see dusky rockfish) S. emphaeus (see Puget Sound rockfish) 5. entomelas (see widow rockfish) S.flavidus (see yellowtail rockfish) .V. melanops (see black rockfish) Secchi disk 251 sedentariate 410 sedentary benthos 584 sediment clast 120,123,165,372,587,600,601 diagenetic 132 diamict sediment 112 failure 105-7,114,115 fluvial 7,84,93,119,123,133 glacial-fluvial 93 glacial-silt loading 199 mudfall 600 siliceous ooze 254 suspended load 107,115,133,207,563 trap 86,111,113,251.256,267 unstable 381,587 sei whale (Balaenoptera borealis) 295,527,531, 532,546 seiche 6,145,152,164,173,587,599 seismic exposure map 170,172,600 seismic gap 152,154-56,158,165,167,168,170, 172,177,587,600 seismic profile 94.101,114,129 seismicitv 145-47,149,152,154-58,165,167,171, 172.176.586,600,601 seismotectonics 157,587,599,600 Seldovia 71,72,173,605 selective fishery 463 Semibalanus balanoides 305,316,318-21,327, 334,335 S. cariosus 305,316,325,330,331,334 Semidi Islands 480,482,493,502.504,514, 515 semipalmated plover (Charadrius semipalmatus) 486 sensible heat flux 34,41 serpulid polychaete 327,364,372 Serripes groenlandicus 359.362 S. sp. 372,378 seston 84 setup, sea surface 190,191 Seward 66,67,71,72.161,164,173,267,424,576 Seward Peninsula 161.164 Seward, William H. 16 sexual dimorphism (in sea lions) 541 sexual maturity (in marine mammals) 531, 532,534,536,537,539,542,543 Shannon Diversity Index 226,364 sharp-headed finner (see minke whale) shearwater (Puffinus spp.) 295,376,445,479, 489,504-6,508,512-15,605,609 Sheep Bay 349,362 shelf break 6-8,82,83,93,96,111,115,117.126, 133,199,249,262,269,294,351,353,381,428, 504.505,513,561,562,564,606 ShelikofStrait 8.9 environmental studies 21,206,612 fisheries 7.380.387,436,546 fishes 7,436,437 geomorphology 94,126,127,133 invertebrates 306,309,373,380,387 mammals 537,541 meteorology 46 microbiology 222,234,235 physical oceanography 46,65,67,71,96, 133,262,427,437,601,604,606 sedimentation 94,126-29,131-33,208 tectonic activity 96,128,156,172 shellfish (see also, individual species) 7,13, 19,221,227,273,295,296,348,350,369-71, 375,376,383,419,420,448,449,512,546,563, 575,578-80,584-86,608,609,611 Shemya Island 305,313,315,325,333 Shishaldin Volcano 176 shorebirds 479-81,486-89,515,516,609,610 short-billed dowitcher (Limnodromus griseus) 486,488 short-finned pilot whale (Globicephala mac- rorhynchus) 420 shorthorn sculpin (Myoxocephalus scorpius) 407 short-tailed albatross 611 short-tailed shearwater (Puffinus tenuirostris) 479,489,504,505,508,512 shrimp 348,350,419,605 abundance 355,357,361-64,369,372, 374-76,386,441,442,579,584,605,610 benthos 347,355,357,361-64,369 in diet of birds 485,511,512 in diet of crabs 370,372,377 in diet offish 363,372,410,411,436,437 in diet of mammals 541 distribution 202,357,361-64,369,374-76, 386,387,418,441,442,584,605,610 fishery 7,21,350,364,369,371,375,376,380, 440,441,512,579,608 food habits 372,380,386,563,607 life history 291,441 Shumagin/Shumagin Islands 8 birds 480,502,513,514 fisheries 418,436,438,439,443,464,469 fishes 418,425,436,438,439,469 invertebrates 372,373,418,442,443 macrophytes 331 physical oceanography 67,264 shelfgeology 132,170,173 tectonic activity 154,156-58,160,167,168, 170-74,177.587,600 shumagin seismic gap 154,156,158,168, 587 Shuyak Island 128,609 Siberia 424,482 Siberian high pressure system 32,33,38,50 sidestripe shrimp (Pandalopsis dispar) 256, 361-63,372,440,441 significant wave height 45,96,601 silicate 6,19,78,79,124,126,199,203,204,256, 260,563 silicoflagellate 262,269 Siliqua patula (see razor clam) sill 84-86,115,120,126,131,132,187,190,193-206, 208,363,364,382,383,387,499,562,563,568 silt loading 199 Silver Bay 190 silver salmon (see coho salmon) Simpson Bay 349,362 Simpson index of dominance 364 simulation modeling 599 Siphonaria thersites 327,331 Sipuncula 311 Sitka 16,59,71,72,152,154,174,176,320,327, 377,380,499,529,536,576,583,584,601,603 Sitka earthquake of 1972 152,154 Sitka spruce 486,583 Sitkalidak Island 380,480 Sitkalidak Strait 377,499 Sitkinak Island 117,377,609 Sitkinak Trough 115,117-20 SiwashBay 318,319,335 Sixty-foot Rock 610 Skagway, Alaska 583 skate (Rajidae) 535 Skeletonema costatum 264,270 slide 6,93,101,105-7,112,115,117,120,133,145, 152,164,172-74,334,587,601 Smeaton Bay 198,200,202,207,268,271-73, 604 Smeaton Bay-Wilson Arm 268 smectite 107,109 smelt (Osmeridae) 407,408,532,538 Smithsonian Institution 18 smolt (salmon) 450,464,469,470,473,474, 580,585 snail 347,359,363,371,377,380,403,411,418, 419,440,485,545 snailfish (Cyclopteridae) 403,418 snake prickleback (Lumpenus sagitta) 406 snipe (see common snipe) snow goose {Chen caerulescens) 482,483,516, 610 sockeye salmon (Oncorhynchus nerka) 226, 419,461-65,468,469,473,586,610 solar radiation, incident 251,255 Solariella obscura 359 S, sp. 377 Somateria mollissima (see common eider) 5. spectabilis (see king eider) sooty shearwater (Puffinus griseus) 376,445, 489,504,505,508,605 South Albatross Bank 377 South Kodiak Island 377 South Sitkalidak Lagoon Southeast Alaska birds 486,490,495,499,501,502,504,511-14 chemical oceanography 234 environmental studies 548,579,580,583, 587,598,611 fisheries 400,464,579,580 human history 15 mammals 530,532-34,536,537,542,544, 545,548,611 other biota 227,233,316,318-20,333,402, 464,537,580 physical oceanography 294,316,318,587 plankton 197,234,294 tectonics 165 Southern Ocean 254 Soviet Union 421,439,534 spawning aggregation 436,438 Index 653 spawning escapement 461,464,466,470,474. 586 Spencer. Cape (see Cape Spencer) sperm whale (Physeter catodon; Physeter mac- rocephalus) 430,444,445,530,535 Spun haetopta u s sp. 370 spionid polychaete 359 Spiophanei kroyeri 364 Spirillum 222 Spirinchus thaleichthys (see longfin smelt) Spirontocarii sp. 485 Spisula polynyma (see pinkneck clam) sponge 370-72.377.380.4O1.) sport Rshermen 586, (ill) spotted sandpiper (Actitis macularia) 486 spring bloom 198-200,202,208,234.258.265, 272.383.562.565 Spring Point 309 Spinr. Mount (see Mount Spun)' Squamish River 563 Squamish (wind) 193 squid abundance/biomass 444,445 in diet of birds 445,511 in diet of fish 445,565 in diet of mammals 444,445,530,532,538, 539,541-43,545,546 distribution 444,445 ecology/life history 444,445,565,567 fishery 360,440,444,580 food habits 385,438,445,567 squid standing stock 445 St. Augustine Volcano 150,172 St. Elias Earthquake of 1979 154.155 St. Elias Mountain (see Mount St. Elias) St. Elias Range 94,145,152,161 St. Elias, Cape (see Cape St. Elias) St. Elias, Mount (see Mount St. Elias) St. Helens, Mount (see Mount St. Helens) St. Lawrence River 208 St. Lazaria Island 490,513 St. Matthew Island 493 St. Paul Island 38 standing crop 249,254,256,262,265,267, 268,272,274,309 Staphylococcus 228 starfish (see also, sea star) 316 Starrigavin Bav 307 starry flounder (Platichthys stellatus) 372, 403,408 Statehood Act of 1959 576 static triaxial strength 129 Station P (see Canadian Ocean Weather Sta- tion P) Station 'P' (see Canadian Ocean Weather Sta- tion P) Station Papa (see Canadian Ocean Weather Station P) steelhead trout (Salmo gairdnerii) 438 Steller bluejav 17 Steller sea cow (Hydrodamalis gigas) xi-xiv,17, 561 Steller sea lion (Eumetopias fubalus) 17. 527-58,605 abundance 420,541,548 in diet of mammals 537 distribution 376,420,528.530,541,609, till) ecology/life history 530.541,561,567,610. (ill food habits 376,542, 546,567. (ill harvest 581 resource conflict 546,585 Steller's eider (Polysticta stelleri) 485,605 Steller, GeorgWilhelm 17,541 Stephens Passage 439,533 Sterna aleutica (see Aleutian tern) S. paradisaea (see Arctic tern) Sternaspii scutata 362-64,373 Stevenson Entrance 46,120.131,367,383,387, 601 Stevenson Trough 115.117.120,378 Stikine River 585 Stikine River delta 479,482,483,486-88,516 stout eelblenny (Lumpenus medins) 403,407, 408 Strait of Georgia 13,197,198,201,285,290. 292,316,565,566,607 Strait of Juan de Fuca 9,13,193,473 stratigraphy 94,106,117,123,128,132,149 streamlines 34 strike slip 101,152,158,160,161,163 Strongylocentrotus 316,321,323,325-27,335, 357,369,380,409 5. droebachiensis (see green sea urchin) S. franc iscanns 326,327 S. polyaca nthus 325 S.purpuratus 326,327 sturgeon poacher (Agonus acipenserinus) 408 Stylatula gracile (see also, sea pen) 378 sub-sill water 193,196,205 subarctic boundary 253,504 Subarctic Current (see also, North Pacific Current) 253,561 Subarctic Gyre 59,61,418,434 Subarctic Pacific Region 418 subduction 145-47,149,150,155,156,158,161, 164,169,170,173,176,600 submarine diffuser (see also, submarine out- fall) 582 submarine outfall 583,585 subsidence 6,145,162,164,173 substrate type 306-8,348,367,374 Suckling, Cape (see Cape Suckling) Sugarloaf Island 542,609 sulfite, free 582 sulfite waste liquor (SWL) 584 sunflower sea star (Pycnopodia helianthoides) 307.327,335,350,359,360,362,376,377,386 super-critical tidal flow 193 supralittoral fringe 330 surf scoter (Melanitta perspicillata) 483 surf smelt {Hypomesus pretiosus) 408 surfbird (Aphriza virgata) 486,487 surge channel 331 Susitna River 8,93,482,548 Susitna River drainage 482 Susitna Valley 47 Susitna-knik-Matanuska River system 126 suspended load 107,115,133.207,563 suspension feeder 315,353,357,360,363, 364,372,374,376-78,380-83 Sutlik Island 504 swan (sec also. ( i c " " "■ s|"'' l(si 150,157 17 I 175,481,482,581,587,601,610 Swanson River 581 sympatric 428-30,537 Synaptidae 363 synoptic survey 58, 570. 606 Synthliboramphus antiquum (see ancient murrelet) tag (salmon) 467-69 Taiwan 532 Taku (wind) 46,193 Talkeetna 601 talus slope 499,502,504.514 Tanaina Indians 15 Tanner crab (Chionocetes bairdi) abundance/biomass 7,355,362,369,374. 375,377,380,381,386,387,579 in diet of fishes 370,386.411,437 in diet of invertebrates 362,380 diseases 227 distribution 7,350,356,357,359,361-63, 367,370,371,376-78,380,386,387 ecology 367,369-71,387,609 fishery 348,355,356,364,369,375-78,380, 387,579,608,610 food habits 350,355,357,362,367,369, 370-72,375-77,381,382,386,607 life history 361,367,370,371,382,387,437, 609,610 resources conflict 418,547 Tarr Bank 106,107,113,114,133,351,353,357. 381.386,387 Taverner's goose (Branta canadensis taverner) 482,483 Taylor Bay 6,115 teal 483,610 tectonic 5,6,93,94,126,132,133,145-47,149. 150,154,156,157,161-64,167,169,173,176,177. 308,587,599,600 tectonically induced sea wave 600 tectonism 7,132,133,588 teleseismic 155,156,158,159,161.173 Tellina nuculoides 366,367,383 T. spp. 367 Telmessus cheiragonus 410 temperature distribution 7.200.202.205. 328,424,445,469,601 Tenakee 273 tephra 174.175,601 terebellid polychaete 364,372,377 Terebellides stroemi 364 Terebratulina unguicula 372 terpene 87 terrane 145.149,150.152.161.163.170 terrigenous (material) 96,113,117-19,149,383, 386,387 territorial (behavioral) 536,541-44 territorial (political) 16,113,575,576,578,579, 581 Thalassioncina nitzicliionles 260 Thalassiophyllum clathrus 325 Thalassiosira aestivalis 270 654 Index /'. nordmskioeldi 199.272 T. spp. 270 Thalassiothrix longissima 260 ThaUicthys pacificus (see eulachon) thalweg 101 Tharyx sp. 364 Theragra chalcogramma (see Alaskan pollock) thermocline 39,251,256,293,428,561,562, 564,565 thick-billed murre (Una lomvia) 499,505, 510,511 tholeiitic 150 Three Saints Bay 15,306,309 thrust fault 146,158,160,161,164 Thumb Cove 364,382 Thunnus alalunga (see albacore tuna) thyasirid bivalve (see also, mollusk) 364 Thyasiridae 363,364 Thysanoessa inermis 290,508,510,531 T. longipes 289,531,533 T. raschii 292 T.spinifera 294,531,536 tidal current 7,45,67,93,96,124,126,133,193, 348,366,384,386,387,447,601,604,608 tidal energy 7,196 tidal power generation 588 Tlingit 15 Togiak 469 toluene 236 tomcod (see Pacific tomcod) Tumopteris septentrianalis 291 Tongass National Forest 576 Tonsina Creek 364 toothed whales (Odontoceti) 445,530,535 Torch Bay 307,315,320,326,327 Totschunda (fault) 152,156,163 tow net 401,406,408 toxin 19,272,580 Trans-Alaska Pipeline 9,236 Transpacific ocean currents 418 transform motion 145,147,160 transition domain 504 transitional waters 254,260 trash line 606 Trelease, Prof. William 18 Trichodon trichodon (see Pacific sandfish) Trichomaris invadens 227 Triglochin (see arrowgrass) Trinity Island 117,372,377 triplejunction 147-49 trophic efficiency 608 group 315,347,348,366,372,373,377,380 level 23,228,232,294,305,315,511,512,514, 516,563,566,567,605,606,608 pathway 200,607-9 studies 586 trophic-level simulation model 21 trophodvnamic modeling 274 Tropidoneis antarctica 260 true cod 422 trumpeter swan (Cygnus buccinator) 482,610 tsunami 7,145,152,154,164,172,173,175-77, 587,598,599 tubenose (birds) 504,505 tubesnout (Aulorhynchusflavidus) 408,409 Tucker trawl 286,401 tufted puffin (Fratercula cirrhata) 295,502, 504,505,510-12,515,605,609,611 Tugidak Island 540,548,609 tule goose (Atiser albifrons gambelli) 482 tuna (see albacore tuna) tundra swan (Cygnus coluntbianus) 482 tunicate 256,409 turbidite 149 turbulent ash cloud 600 Turnagain Arm 8,120 Turnagain Heights 173 turnover rate 197,233,487,488 nitrogen 233 phytoplankton 197 phvtoplankton carbon 197 shorebirds at feeding sites 487,488 Tutka Bay 233 Tuxedni Bay 124,367,604,609 u Ugaiushak Island 480 Ugak Bay 373,375 Ugak Island 609 Ukinrek Maars (volcano) 158,176 ultraplankton 271,272 Umnak Island 175,176 Unalaska 13,16,154,156,176,310,316,333,335, 441,536,546 Unalaska Island 156,176,310,441,536,546 Unaquik Inlet ( = Unakwik Inlet) 349,363 underwater mining 582 Unimak Island 147,148,150,172-76,424,464, 469,585 Unimak Pass 8,13,310 currents 6,59,66,67,73,262,426-28 winds/upwelling 49,264 Unimak-Shumagin Islands 469 United States Department of the Interior 19,23,50,73,87,177,208,237,250,275,296, 388,413,450,474,516,548,568,578,598,601, 604,612 United States Environmental Protection Agency (EPA) 578,597 United States Fish and Wildlife Service (USF&WS) 334,479,480,482,483,485, 487,491,495,499,502,505,511,512,515,516, 545,576,598,609 United States Fish Commission 578 United States Geological Survey (USGS) 598,601 University of Alaska 77,82,84,87,296,482 University of Washington 81,296,508 Upper Cook Inlet birds 516 circulation 126,366 earthquakes 175 environmental studies 585,588,604 geology 156,160 geomorphology 120 invertebrates 366 mammals 537,539 sedimentation 123,126 upwelling 6,195,264,267 biological production 199,222,273,274, 293,294,437 chemical oceanography 79,81,82,206, 256,264 fisheries 608 meteorology 46,49,73,193,562 physical oceanography 6,46,49,73,79,81, 82,188,190,191,193,195,206,256,263,264, 269,273,293,294,296,437,513,561,562, 564 upwelling-downwelling index 188 Uria aalge (see common murre) Uria lomvia (see thick-billed murre) Urochordata 311 Ursus arctos (see brown bear) Valdez 9,308,318,349 biota 197-99,201,235,236,267,270,273, 308,316,318,319,321,323,361,363,382,386, 482,483,608 chemical oceanography 84,199,236,318, 319,381,604 environmental studies 84,599,604 geology 115,172,199,319,381,382 meteorology 319 physical oceanography 84,85,190,191,199, 267,319,604 pollution 235,308,582,598,599 sea ice 316,319 TAP terminal 236,582,587 Valdez Arm 198,199,267,270,361,482,483, 608 Valdez Estuary 236 Valdez Inlet 172 Vancouver Canada goose (Branta canadensis fulva) 482 Vancouver Island 148,192,193,195,205-7, 269,424,433,473,561,603 Vancouver, Capt. George 9,13 vane shear strength 129 Veneridae 377 Veniaminof, Mount (see Mount Veniaminof) Verrucaria 327 vertical eddy diffusivity 81 vertical stability 255 vessel icing 587,603 vessels Acona 19 Albacore 597 Albatross 17-19,285,417,597 Atrevida 13 Brown Bear 19 Capricorn 18 Carnegie 18 Cedarwood 19 Cepheus 604 Chatham 13 Dana 18 Descubierta 13 Discoverer 47,237,388 Discoverer II 18 Discovery 13 Index 655 Eddy 17 Galathea 18 lush Stardust 235 Mansyu 18 Midpacific 18 Nadiejeda 1 7 Aw Attton 9,13 New Archangel 16 Oshora Maru 19 Pennsylvania 6 Ptaw/ 31,62,146 Predpriatie 17 Ramapo 18 Resolution 9.13.606 Shintoka Mam 18 SnWWus 18 ,S7. Paid 9 St. Peter 9.17 7Vrra A'oz'a 17 Wrioz 19 Vityaz 17 viable plate count 221 Vibrio alginolyticus 227 I', cholerae 227 V. parahaemolyticus 227 l'. vulnificus 227 Vitus Bering 9,15.17 volcanic arc 149.160,163.167 volcanic bomb 371,600,601 volcanic hazard 145,164,165,174,175,587, 600,601 volcanism 146,150,152,161,586-88 vole (A/iV ro?u.s spp.) 491 vortices 443 vorticity 6,37,67,605 vulnerability index 605 Yulpes julva (see red fox) W Wadati-Benioffzone 147.149,150,157-60 walleye pollock (see Alaskan pollock) walrus (see Pacific walrus) wandering tattler (Heteroscelus incanum) 486 warthead sculpin (Myoxocephalus niger) 407 Washington State 466.482,496,502,587 wave tank 605 weathervane scallop (Pecten caurinus) 348, 359,360,369,419 weir 464,580 West and Outer Bavs 319,335 West Bay 319 Westdahl, Mount (see Mount Westdahl) 176 Western Alaska 161,274,331,419,464-68,470, 473,488,610 Western Aleutians 33,60,305-7,311,313-15. 323,333,428,468,505,535,576,585 western sandpiper (Calidris mauri) 7,479, 487-89,610 Western Subarctic Gyre 434 wetlands 481,482,486.489,609,610 whale (see also, individual whale species) 8,420,430,444,527,530-38,545,548.568, 605.610.611 environmental impacts 545.547.548,586 food habits 294,295,430,444,445,546, 565,567 resource management 529,578 whaling 16,527,529-32,534,536,545,518. 578,581.611 Whale Island 315.316.318 whaling licet 581 white capelin (Mallotus villosus) 295,376, 399,403,405-12,479,508,509,511,512,515, 532-34,538,539,541-43,546,568,580,586, 607,609 While River 150.171 white whale (see belukha whale) white fronted goose (Auser albtfrons) 482 while-sided dolphin (see Pacific white-sided dolphin) white-winged scoter (Melanitta fusra) 483, 485,610 whitespotted greenling (Hexagrammos stelleri) 408,410 Wide Bay 546 widgeon (see American widgeon) widow rockfish (Sebastes entomelas) 411 wind anticyclonic 34,37,418 forcing 57,71 maximum sustained 601 stress 34,38-40,60,73,264,418,444,513,561 wintering area 487,533,542,610 wolffish (see Bering wolffish) Womens Bay 470 Wood River 469 Wooded Islands 480 wrack (see Fuciis) Wrangel Island 482 Wrangell 94,145,149,150.156,157,161,174,576, 584 Wrangell Mountain (see Mount Wrangell) Wrangell-St. Elias National Park and Pre- serve 576 Wrangellia terrane 150 Yakataga 106,113,154-56,163.167,168,170,177, 315,316,348,359,600 Yakataga Formation 113 Yakataga Seismic Gap 154-56,168,170 Yakataga, Cape (see Cape Yakataga) Yakataga-Yakutat region 348 Yakobi Valley 96,101.106,107 Yakutat 21 biota 306.311.313,333,418,428,482,483, 486-88.532 chemical oceanography 206 environmental studies 21.83,306,348,582, 585 fisheries 464 geomorphology 96,101,105,106 physical oceanograph) 63,67,71.72,206, 418.427,428 sedimentation 105-8 tectonic activity 172 Yakutat Bank 353.359.384.386 Yakutat Bav 9,106.285 biota 351,353,359,360,386,424,439,536. 537,544 environmental studies 249,348 (49 fisheries 359,386 geomorpholog) 105, 106 physical oceanograph) 15,113,193,195, 127 sedimentation 101,105-7,109,111-] 1.360 tectonic activity 165,167,172,587 Yakutat Block 145,150,152,161,163 Yakutat Canyon 353,356,359,360 Yakutat Valley 96,101,106.107 year-class strength 50,444 yellow Irish lord {Hemilepidotui jordani) 399, 403,410,545 Yellow Sea 434 yellowfin sole (Limanda aspera) 226,350,386, 399,403,406,408,410,432 yellowtail rockfish (Sebastes flavidus) 408, 409 Yersinia enterocolytica 227 Yoldia seminuda 367 Y. sp. 363 Kspp. 362.363.372,376 Yukon River 232,464 Yukon-Kuskokwim Delta 482,486,489 ZaikofBay 320,335,349,362,381,382 Zaikof Point 408 Zalophus californianus (see California sea lion) Ziphiidae (see beaked whales) Ziphius cavirostris (see Cuvier's beaked whale) zodiac fan 149 zoophagous fish 609 zooplankton 285-303 abundance 7.200-202,265,386,514,563, 565 in diet of benthic invertebrates 362,363 in diet of birds 514 in diet of fish 411,420,429,430,436,437 distribution 7.200-202,363,382,383,387. 429 ecology 200-202,255,274.386,429,436. 437,563,567,607 gelatinous 411 grazing on phytoplankton 7,200-202,256, 258,264,265,274,565,567,607 species composition 200-202,258 The technical editing, graphics production, and preparation of this volume for printing were carried out through the combined efforts of Northwest Cartography, Inc. of Seattle, Wash- ington and Talasaea Consultants of Bellevue, Washington. The following individuals are acknowledged for their dedication and performance over the duration of this project: Project Administrator Project Manager R. Bradford Harvey William E. Shiels III Technical Editing Lead Technical Editor Technical Editors Editorial Assistants Brian L. Brandt Rita A. Horner, Ph.D. Amy Schoener, Ph.D. David G. Stanton Walter H. Kilbourne III Word Processing Janet G. Elliott Graphics and Publication Production Production Supervisor Lead Graphics Specialist Graphics Specialists Typesetting Computer Programming and Production Programming Production Daniel Handschin Debra R. Slotvig Mary T. Aslin ScotN. Barg Cynthia A. Hess Patrick Jankanish The Type Gallery Seattle, Washington T. Scott Oswald James S. Woolley Kevin J. Connolly Ross A. McKenzie Steven D. Beimborn ' ' *. I ^FAIRBANKS '■'A-*' .Delta Af^oi*.^ Clenhallenj Columbia <* J Valde/> V: -A »* If. » HVhi(M>r0 nai J' 1 #>>{ Seward .''TU *&2 v ( HORSt ^^So Watson Lake ^ >s V. ;V Montague I ^» ' Haglrx .'ce/ielil .Cordova hoot f^ , O' . ^ j»- *G/"? CaP? *akata*a V.ate/>rW - 'Ts^ '> Cape St Elias -^^ j ~- ^j* ^Pamplona A* Caf<, 'VM>si