' >'"'■! < iif^ .*>. '*''.* : V.' »ilf^i^iev^^: :.;:-: Pink Salmon, Oncorhynchus gorbuscha, Tagging Experinnents in Soutlieastern Alaska, 1938-42 and 1945 ROY E. NAKATANI, GERALD J. PAULIK, and RICHARD VAN CLEVE SEATTLE. WA April 1975 noaa NATIONAL OCEANIC AND / National Marine ATMOSPHERIC ADMINISTRATION / Fisheries Service NOAA TECHNICAL REPORTS National Marine Fisheries Service, Special Scientific Report— Fisheries Series The major responsibilities of the National Marine Fisheries Service (NMFS) are to monitor and assess the abundance and geographic distribution of fisher>' resources, to understand and predict fluctuations in the quantity and distribution of these resources, and to establish levels for optimum use of the resources. NMFS is also charged with the development and implementation of policies for managing national fishing grounds, development and enforcement of domestic fisheries regulations, surveillance of foreign fishing off United States coastal waters, and the development and enforcement of international fishery agreements and policies. NMFS also assists the fishing industry through marketing ser\'ice and economic analysis programs, and mortgage insurance and vessel construction subsidies. It collects, analyzes, and publishes statistics on various phases of the industry. The Special Scientific Report— Fisheries series was established in 1949. The series carries reports on scientific investigations that document long-term continuing programs of NMFS. or intensive scientific reports on studies of restricted scope. The reports may deal with applied fishery problems. The series is also used as a medium for the publica- tion of bibliographies of a specialized scientific nature. NOAA Technical Reports NMFS SSRF are available free in limited numbers to governmental agencies, both Federal and State. They are also available in exchange for other scientific and technical publications in the marine sciences. Individual copies may be obtained (unless otherwise noted) from D83. Technical Information Division, Environmental Science Information Center, NOAA. Washington, D.C. 20235. Recent SSRF's are: 619. Macrozooplankton and small nekton in the coastal waters off Vancouver Island (Canada) and Washington, spring and fall of 1963. By Donald S. Day, January 1971. iii + 94 pp., 19 figs.. 13 tables. 635. A bibliography of the blackfin tuna, Thunnus atlanticus (Lesson). By Grant L. Beardsley and David C. Simmons. August 1971, 10 pp. For sale by the Superintendent of Documents. U.S. Government Printing Office, Washington, D.C. 20402. 620. The Trade Wind Zone Oceanography Pilot Study. Part IX: The sea-level wind field and wind stress values. July 1963 to June 1965. By Gunter R. Seckel. June 1970, iii + 66 pp., 5 figs. 636. Oil pollution on Wake Island from the tanker R. C- Stoner. By Reginald M. Gooding. May 1971. iii + 12 pp.. 8 figs.. 2 tables. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402. 621. Predation by sculpins on fall chinook salmon, Oncorhynchus tshawytscha. fry of hatchery origin. By Benjamin G. Patten. February 1971, iii + 14 pp.. 6 figs., 9 tables. 622. Number and lengths, by season, of fishes caught with an otter trawl near Woods Hole, Massachusetts, September 1961 to December 1962. By F. E. Lux and F. E. Nichy. February 1971, iii + 15 pp., 3 figs.. 19 tables. 623. Apparent abundance, distribution, and migrations of albacore, Thunnus aialunga. on the North Pacific longline grounds. By Brian J. Rothschild and Marian Y. Y. Yong. September 1970. v + 37 pp., 19 figs., 5 tables. 624. Influence of mechanical processing on the quahty and yield of bay scallop meats. By N. B. Webb and F, B. Thomas. April 1971, iii + 11 pp., 9 figs.. 3 tables. 637. Occurrence of larval, juvenile, and mature crabs in the vicinity of Beaufort Inlet. North Carolina. By Donnie L. Dudley and Mayo H. Judy. August 1971. iii + 10 pp.. 1 fig.. 5 tables. For sale bv the Superintendent of Documents. U.S. Government Printing Office, Washington. D.C. '20402. 638. Length-weight relations of haddock from commercial landings in New England. 1931-55. By Bradford E, Brown and Richard C. Hennemuth. August 1971, v -t- 13 pp.. 16 figs., 6 tables. 10 appendix A tables. For sale by the Superintendent of Documents, U.S. Government Printing Office. Washington, D.C. 20402. 639. A hydrographic survey of the Galveston Bay system, Texas 1963-66. By E. J. Pullen, W. L.Trent, and G. B. Adams. October 1971. v + 13 pp.. 15 figs,. 12 Ubies. For saleby the Superintendent of Documents. U.S. Government Printing Office. Washington, D.C. 20402. 625. Distribution of salmon and related oceanographic features in the North Pacific Ocean, spring 1968. By Robert R. French, Richard G. Bakkala. Masanao Osako. and Jun Ito. March 1971. iii + 22 pp.. 19 figs.. 3 tables. 626. Commercial fishery and biology of the freshwater shrimp. Macrobrachium, in the LowerSt. Paul River. Liberia, 1952-53. By George C. Miller. February 1971. iii -t- 13 pp.. 8 figs.. 7 tables. 627. Calico scallops of the Southeastern United States, 1959-69. By Robert Cummins, Jr. June 1971, iii -t- 22 pp.. 23 figs,, 3 tables. 628. Fur Seal Investigations. 1969. By NMFS. Marine Mammal Biological Laboratory- August 1971. 82 pp.. 20 figs.. 44 tables. 23 appendix A tables. 10 appendix B tables. 629. Analysis of the operations of seven Hawaiian skipjack tuna fishing vessels. June- August 1967. By Richard N. Uchida and Ray F. Sumida. March 1971. v + 25 pp., 14 figs.. 21 tables. For sale by the Superintendent of Documents. U.S. Government Printing Of- fice. Washington. D.C. 20402. 640- Annotated bibliography on the fishing industn,- and biolog>- of the blue crab, CaUinectes sapidus. By Marlin E Tagatz and Ann Bowman Hall. August 1971. 94 pp. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402. 641. Llse of threadfin shad. Dorosoma petenense, as live bait during experimental pole- and-line fishing for skipjack tuna, KaCsuwonus pelamin. in Hawaii. By Robert T, B. Iversen. August 1971. iii + 10 pp., 3 figs., 7 tables. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington. DC. 20402. 642. Atlantic menhaden Brevoortia tyrannus resource and fishery — analysis of decline. By Kenneth A. Henr>'. August 1971. v + 32 pp.. 40 figs.. 5 appendix figs., 3 tables. 2 appendix tables. For sale by the Superintendent of Documents. U.S. Government Printing Office, Washington. D.C. 20402. 643. Surface winds of the southeastern tropical Atlantic Ocean, By John M. Steigner and Merton C. Ingham, October 1971. iii + 20 pp.. 17 figs. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington. D.C, 20402. 630. Blue crab meat. I. Preservation by freezing, July 1971. iii -f 13 pp.. 5 figs., 2 tables. n. Effect of chemical treatments on acceptability. By Jurgen H. Strasser. Jean S. Lennon. and Frederick J. King. July 1971. iii + 12 pp.. 1 fig., 9 tables. 631. Occurrence of thiaminase in some common aquatic animals of the United States and Canada. By R. A. Greig and R. H. Gnaedinger, July 1971. iii + 7 pp.. 2 tables. 632. An annotated bibliography of attempts to rear the larvae of marine fishes in the laboratory. By Robert C. May. August 1971, iii + 24 pp.. 1 appendix I table. 1 appendix II table. For sale Idv the Superintendent of Documents. U.S. Government Printing Office, Washington. D.C. 20402. 633. Blueing of processed crab meat. U. Identification of some factors involved in the blue discoloration of canned crab meat CaUinectes sapidus By Melvin E. Waters. May 1971. iii + 7 pp.. 1 fig., 3 tables. 634. Age composition, weight, length, and sex of herring, Clupea pallasii. used for reduc- tion in Alaska. 1929-66. By Gerald M. Reid. July 1971. iii + 25 pp.. 4 figs.. 18 tables. 644. Inhibition of fiesh browning and skin color fading in frozen fillets of yelloweye snapper (Lutzanus vivanus). By Harold C. Thompson, Jr., and Mary H. Thompson. February 1972. iii + 6 pp.. 3 tables. For sale by the Superintendent of Documents, U.S. Government Printing Office. Washington, D.C 20402. 645. Traveling screen for removal of debris from rivers. By Daniel W. Bates. Ernest W. Murphey. and Martin G. Beam. October 1971, iii + 6 pp.. 6 figs.. 1 table. For sale by the Superintendent of Documents, U.S. Government Printing Office. Washington. D.C. 20402. 646. Dissolved nitrogen concentrations in the Columbia and Snake Rivers in 1970 and their effect on chinook salmon and steelhead trout. By Wesley J. Ebel. August 1971, iii + 7 pp.. 2 figs.. 6 tables. For sale by the Superintendent of Documents, U.S. Government Printing Office. Washington, D.C. 20402. 647. Revised annotated list of parasites from sea mammals caught off the west coast of North America. By L. Margolis and M. D. Dailey. March 1972, iii + 23 pp. For sale by the Superintendent of Documents. U.S. Government Printing Office, Washington, D.C 20402. Continued on inside back cover. NOAA Technical Report NMFS SSRF-686 Marine Biological Laboratory LIBRARY OCT 14 1992 Woods Hole, Mass. Pink Salmon, Oncorhynchus gorbusha, Tagging Experiments in Southeastern Alaska, 1938-42 and 1945 ROY E. NAKATANI, GERALD J. PAULIK, and RICHARD VAN CLEVE SEATTLE, WA April 1975 UNITED STATES DEPARTMENT OF COMMERCE Frederick B. Dent, Secretary NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION Robert M White, Administrator Far aale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 National Marine Fisheries Service Robert W. Schoning. Director """'■sr^*" The National Marine Fisheries Service (NMFS) does not approve, rec- ommend or endorse any proprietary product or proprietary material mentioned in this publication. No reference shall be made to NMFS, or to this publication furnished by NMFS, in any advertising or sales pro- motion which would indicate or imply that NMFS approves, recommends or endorses any proprietary product or proprietary 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 NMFS publication. CONTENTS Page Introduction 1 Historical review 3 Experimental and analytic methods 3 Tags and tagging 3 Preliminary processing of data 4 Release and recovery information 4 Migration routes as determined from tag recoveries 8 Migration between northern and southern southeastern Alaska 8 Migration through Peril Strait 8 Distribution of trap recoveries from experiments in Icy Strait and Chatham Strait 9 Icy Strait 9 Upper Chatham Strait 12 Middle Chatham Strait 17 Lower Chatham Strait 19 Summary and discussion of general migration patterns as determined from tag recaptures ... 21 Relative abundance and migration as determined from trap catch data 24 Rate of travel determined from tagging data 28 Mortality rates 29 Recommendations for the design of future tagging experiments 36 Summary 38 Acknowledgments 39 Literature cited 39 Figures 1. Southeastern Alaska, area of pink salmon tagging experiments in 1938-42 and 1945 2 2. Northern part of southeastern Alaska showing major statistical areas and subareas used for computer analysis of pink salmon tag recapture data 5 3. Locations and code numbers of principal trap sites, 1938-42 and 1945 7 4. Tag recoveries per trap by 20-mile intervals measured from points of release in Icy Strait, 1941 . 13 5. Tag recoveries per trap by 20-mile intervals measured from points of release in Icy Strait, 1942 14 6. Tag recoveries per trap per time period by 20-mile intervals measured from point of release in upper Chatham Strait, 1940 15 7. Tag recoveries per trap by 20-mile intervals measured from point of release in upper Chatham Strait, 1941 16 8. Tag recoveries per trap per time period by 20-mile intervals measured from point of release in upper Chatham Strait, 1942 17 9. Tag recoveries per trap per time period by 20-mile intervals measured from point of release in middle Chatham Strait, 1940. 10. Tag recoveries per trap per time period by 20-mile intervals measured from point of release in middle Chatham Strait, 1941. 11. Tag recoveries per trap per time period by 20-mile intervals measured from point of release in middle Chatham Strait, 1942. 12. Tag recoveries per trap per time period by 20-mile intervals measured from point of release in lower Chatham Strait, 1938. 13. Tag recoveries per trap per time period by 20-mile intervals measured from point of release in lower Chatham Strait, 1939. 25 14. Tag recoveries per trap per time period by 20-mile intervals measured from point of release in lower Chatham Strait, 1941 15. Tag recoveries per trap per time period by 20-mile intervals measured from point of release in lower Chatham Strait, 1942 25 18 20 21 22 24 HI 16. Average number of pink salmon caught per trap per week in each major statistical area in 1938 26 17. Average number of pink salmon caught per trap per week in each major statistical area in 1939 26 18. Average number of pink salmon caught per trap per week in each major statistical area in 1940 27 19. Average number of pink salmon caught per trap per week in each major statistical area in 1941 27 20. Average number of pink salmon caught per trap per week in each major statistical area in 1942 28 21. Exploitation isopleth for the total pink salmon run entering the northern part of south- eastern Alaska, 1938 35 22. Exploitation isopleth for the total pink salmon run entering the northern part of south- eastern Alaska, 1939 36 23. Exploitation isopleth for the total pink salmon run entering the northern part of south- eastern Alaska, 1941 36 24. Exploitation isopleth for the total pink salmon run entering the northern part of south- eastern Alaska, 1942 36 Tables 1. Closing dates of fishing season in major statistical subareas of southeastern Alaska, 1938-42 6 2. Number of salmon traps in major statistical subareas in southeastern Alaska in 1938-42 and 1945 6 3. Number of tagging experiments conducted in southeastern Alaska areas during 1938-42 and 1945 6 4. Number of tags released and number recovered in tagging experiments in southeastern Alaska, 1938-42 and 1945 8 5. Summary of release and recovery information from tagging conducted in southeastern Alaska during 1938-42 and 1945 10 6. Comparison between recoveries in Sumner Strait and total recoveries, July and August 1938-42 and 1945 12 7. Recovery areas of tags released from traps in Icy Strait, 1941-42 14 8. Recovery areas of tags released from traps in upper Chatham Strait, 1940-42 15 9. Recovery areas of tags released from traps in middle Chatham Strait, 1940-42 18 10. Recovery areas of tags released from traps in lower Chatham Strait, 1938-39 and 1941-42. . . 23 11. Total trap catch and catch per trap in major statistical subareas in southeastern Alaska, 1938-42 and 1945 26 12. Time difference between average weekly catches of fish in traps in outer Icy Strait and four inner areas and miles traveled per day 29 13. Time difference between average weekly catches of fish in traps in lower Chatham Strait and two inner areas and miles traveled per day 30 14. Rates of travel of tagged fish estimated by regression technique 31 15. List of ^-values for comparison between mean days out for trap recoveries and mean days out for seine recoveries 32 16. Weekly survival rates, weekly exploitation rates, experimental fishing mortality rates, and other-loss rates for 30 groups of tagged fish 33 IV Pink Salmon, Oncorhynchus gorbuscha, Tagging Experiments in Southeastern Alaska, 1938-42 and 1945' ROY E. NAKATANI,^ GERALD J. PAULIK,' and RICHARD VAN CLEVE' ABSTRACT A total of 20,532 pink salmon {Oncorhynchus gorbuacha) were tagged and released in southeastern Alaska north of Sumner Strait during the years of 1938 to 1942 inclusive, and in 1945. The recovery of 7,027 of these tags in the fish traps confirmed the findings of other in- vestigators that the pink salmon stocks of the northern part of southeast Alaska are separate from those in the southern part. They also show that pink salmon enter the northern part of southeast Alaska through two paths: (1) through Icy Strait, and (2) through the lower end of Chatham Strait. No evidence was found of movement through Peril Strait from Salisbury Sound into Chatham Strait. The centers of density of each group of tags appeared to move in a consistent manner, but a smaller number of tags from each release were dispersed throughout the northern part of southeastern Alaska. Differences were noted between the movements of fish in odd and even years. Also a larger proportion of earlier tagged fish moved to recovery locations father inland. In all areas and in all years the fishing season closed about the time of the greatest abundance of fish in the fishery, therefore the later parts of the runs were not studied. Apparently the 1941 run was the largest and that in 1945 the smallest. Migration rates were studied by plotting the catch per trap as well as by the recovery of tags. The latter showed movements of 9.05 to 33.37 miles per day. Survival rates computed for thirty releases with total tag recovery periods of two or more weeks averaged 0.384. Weekly exploitation rates varied from 0.142 to 0.452 averaging 0.250. The weekly F exponential rate of fishing averaged 0.514. Recoveries of tags from seines were not used since their proportion of tags recovered was less than one-half their proportion of the catch. Recommendations are made for future tagging ex- periments based upon the results of this analysis. INTRODUCTION From about 1920 to 1950 the U.S. Fish and Wildhfe Service (FWS) collected considerable data on Alaska fisheries. An inventory of these data, made under a contract between the University of Washington College of Fisheries and the FWS, disclosed records of pink salmon, Oncorhynchus gorbuscha, tagged in the northern part of southeastern Alaska (Fig. 1) in 1938- 42 and 1945. A total of 20,532 tagged fish were released in 55 tagging experiments during the 6 yr; 7,027 of the tags were recovered. In this report the tagging and recovery data are analyzed; supplemented by records of the daily catches of pink salmon from about 100 traps that operated in the area in the years covered by the experiments. 'Contribution No. 401 from the College of Fisheries, University of Washington. 'Assistant Director, Fisheries Research Institute, College of Fish- eries, University of Washington, Seattle. 'Deceased. Formerly Professor, College of Fisheries, University of Washington, Seattle. 'Professor, College of Fisheries, University of Washington, Seattle. All recovery and catch data were transferred to punch cards and processed through an electronic digital computer at the Research Computer Laboratory, University of Washington. Details of programming for the different analyses, including tables of the data used in the computations, are on file at the National Marine Fisheries Service Auke Bay Fisheries Laboratory at Auke Bay, Alaska, and at the College of Fisheries.' Past reports on salmon tagging experiments in Alaska include those by Rich (1927), Rich and Suomela (1929), and Rich and Morton (1930). The tagging experiments covered in this report must be evaluated with a full understanding of the restrictions imposed on the staff originally responsible for them. The difficulties involved in executing a tagging and recovery program covering an area the size of the northern half of southeastern Alaska and involving a fishery as complex as the pink salmon 'Nakatani, R. E.. G. J. Paulik, and R. Van Cleve. 1963. Analysis of past Alaskan pink salmon tagging experiments, 19.38-1945. Un- published manuscript, 163 p. Fisheries Research Institute, Univer- sity of Washington, Seattle, WA 98195. T 139° Figure 1. — Southeastern Alaska, area of pink salmon tagging experiments in 1938- 42 and 1945. ■^^o "%0 •Sifo -Li 1 1— fishery in this area can be appreciated by those who have attempted such work. Our evaluation has been possible only because of the efforts of the early biologists who collected and preserved the data under difficult conditions. Any criticisms of the techniques or any deficiencies noted in the programs are presented only to facilitate the design of future ex- periments. HISTORICAL REVIEW The first major tagging experiments on pink salmon in southeastern Alaska were conducted in 1924 and 1925 by the Bureau of Fisheries under the direction of Willis H. Rich (Rich 1927) "... to discover the main routes of the salmon migrating through the maze of channels of the Alexander Archipelago and the dis- tribution of the fish following these routes to the various spawning grounds." This work was continued by Rich and Suomela (1929) and Rich and Morton (1930). One of the most significant findings of these early workers was the virtual separation of the southeastern Alaska fishery into two distinct areas — one to the north of Kuiu, Kupreanof, and Mitkof islands, and the other to the south. The interchange of tagged pink salmon between these areas was so small that for all practical purposes the areas could be considered separate. The northern area included Icy Strait, Lynn Canal, Chatham Strait, Frederick Sound, and Stephens Passage; the southern area included Sumner Strait, Clarence Strait, and the south and west coasts of Prince of Wales Island. Tagged pink salmon released in Icy Strait moved eastward and then southward in Chatham Strait to Frederick Sound. In Frederick Sound they traveled eastward and then northward. Most of the pink salmon released in lower Chatham Strait during mid- July moved into Frederick Sound, and those released in early August moved north into upper Chatham Strait and south into Sumner Strait. Fish released in Frederick Sound in early August distributed themselves throughout Frederick Sound and along Stephens Passage. An extensive series of experiments in the southern area and some tagging experiments in the northern portion of southeastern Alaska were reported by Verhoeven.' Verhoeven concluded that the pink salmon spawning migration is a "random to-and-fro" wandering through the fishery. He maintained that the apparent directional tendencies found by other in- vestigators resulted from random movement com- bined with the location of the fishery in relation to the location of the tagging stations. The validity of 'Verhoeven, L. A. 1952. A report to the salmon fishing industry of Alaska on the results of the 1947 tagging experiments. Unpublished manuscript, 21 p. Fisheries Research Institute, University of Wash- ington, Seattle, WA 98195. Verhoeven's hypothesis of random to-and-fro move- ment is of critical importance to the formulation of an acceptable policy for regulating the fishery. If pink salmon move randomly within an area, any geographical variation in fishing intensity in the area would not differentially affect the population. Only the total fishing pressure would determine the escape- ment of any particular stream and would affect all races in the same manner. The primary function of management would then be to define each of these homogeneous areas and to regulate each area as one unit. The independence of salmon stocks in the southern and northern portions of southeastern Alaska was also shown by Verhoeven (citation in footnote 6, Figs. 25, 26). During 1950, 17,400 pink salmon were tagged in Icy Strait and upper Chatham Strait by the FWS (Elling and Macy 1955). Tagged fish were released daily from tagging stations in Icy Strait from 25 July through 14 August, ending the day before the opening of the com- mercial fishing season. Generally speaking, the results of the 1950 tagging experiments agreed with the results of Rich and his colleagues in the twenties. Stream surveys, combined with a daily schedule of tagging, enabled Elling and Macy (1955) to determine when pink salmon destined for a particular spawning stream passed the various tagging sites. However, the limited period during which daily releases were made restricted the utility of the experiments. Different races of pink salmon passing the Icy Strait tagging stations were not separated in time into clear-cut groups. Elling and Macy (1955) found that fish bound for streams in Stephens Passage, Chatham Strait, and Icy Strait passed through Icy Strait about the same time. EXPERIMENTAL AND ANALYTIC METHODS Tags and Tagging The method used in tagging during the 1938-42 and 1945 experiments was described to us by S. J. Hutchinson in a personal interview. S. J. Hutchinson participated in the experiments. Fish were captured in salmon traps and were tagged with a metal strap tag clipped to the dorsal margin of the caudal fin. The method of handling during tagging was similar to that described by Davidson and Christey (1938). In 1938-41, tags were serially numbered so that each fish could be identified on recovery. In 1942 and 1945, a single number was used to identify all fish tagged in an experiment, and in some cases the same identifica- tion number was used for more than one experiment. Problems arising from the confusion between tags recovered from two experiments in 1945 will be dis- cussed in the section on migration through Peril Strait. Preliminary Processing of Data The original tagging and recovery data discussed in this report were found in logbooks, original return forms, summary tables, manuscripts, and cor- respondence. Inasmuch as a large part of the recovery information was taken from summary tables, which were sometimes incorrect or incomplete, considerable effort was expended in comparing these summaries with original records. There was no method by which the date and place of recovery could be absolutely verified, and it was assumed that the summary tables were correct if no evidence to the contrary was found. If information was lacking or if a discrepancy was found which could not be resolved by a search of the records, the recovery was classified as having an un- known date or place of recovery. The changes made as a result of comparison with original records were not many and were usually corrections of obvious errors. In analyses where the recoveries were pooled by geographical areas, recovery reassignments had little effect on the results because the recoveries were usually reassigned to traps near the traps to which they had originally been assigned in the summary tables. The tag return information was transferred to punch cards and processed through an IBM 650 digital computer to compute such additional informa- tion as days out and distance from the tagging station and to punch a final basic card for each return. There were omissions as well as inaccuracies in the data relating to a number of important factors. Distribution of the seine fleet in time and space, the size of the seine catches and the spawning escape- ment, and an accurate measure of recovery effort or outline of the program used for recovery were all un- known. Each of these factors will be discussed in more detail in later sections where they are pertinent. Because almost no information was available on the size and distribution of the seine fleet and its catch, this report is restricted to a consideration of trap catch data and trap recoveries of tagged fish, except in the section on mortality rates. Since about 80% of the recoveries were made by traps, this limitation is not severe. To validate trap catch data, which were submitted by the canneries to the FWS, persons acquainted with trap operations in the areas during the years con- sidered in this report were consulted on methods used to estimate the daily and weekly catches of a salmon trap. No method was found to verify all of the catch data; therefore, no corrections were made in the original cannery records. The fact that catch records kept independently by certain canneries showed ex- cellent agreement with the data submitted to the FWS increased our confidence in the data. Daily catch data for each trap were transferred from the cannery forms to IBM cards identical to those used by the FWS for recording daily trap catches. When more than one brailing in a day was recorded, the sum of the recorded catches was entered on the IBM card. Records from licensed traps that caught few or no fish were omitted. The actual daily catch was not always recorded, and the analysis was based on the weekly catch. Traps were frequently fished more than 1 day without being brailed; they were emptied daily only during the last 2 wk of the fishing season. During the latter part of the season when the runs were heavy, some traps were brailed on Saturday and also on Sunday, a closed day, for the usual fishing period of 5'/2 days a week. Because the operation of traps during the weekend closure is unknown, there is some doubt as to what day those fish recorded as taken on Sunday actually entered the trap. All traps were assumed to have been empty at the beginning of each fishing week and the catches were summed from Monday through Sunday. Release and Recovery Information A statistical coding scheme was used to group the waters of the northern part of southeastern Alaska into statistical areas and subareas (Fig. 2) for com- puter analysis of the tag-recapture and catch data. The closing dates of the fishing season for the years 1938-42 in the major statistical subareas were es- timated from data on the daily trap catches (Table 1). A description of the statistical coding system is available in Simpson (1960). The locations and code numbers of the principal trap sites and the tagging stations are shown in Figure 3. The code numbers used throughout this report are the same as those shown in Figure 3 except for a few minor changes such as those employed in what is known as the Vaughn system (for further information on this system, see the publication cited in footnote 5). The number of traps operating in each major sta- tistical subarea (Fig. 2) each year is given in Table 2. The numbers of tagging experiments conducted during 1938-42 and 1945 are given in Table 3. Release and recovery data are summarized by year in Table 4. Total recoveries, omitting those from streams, during the period from 1938 to 1945 varied from 28% to 38%. The total, over all years, of 7,027 tags recovered from all sources represents 34.3% of the total releases; 79.8% of the total recoveries were recovered in traps and 16.1% in seines. Because only 30 tagged fish were recovered in streams, stream recoveries were not used in any of the analyses and will not be discussed. Basic release and recovery information for each ex- periment is presented in Table 5. The timing of the releases during the season varied considerably from year to year. In only three experiments were less than 100 fish released. Many of the tagging experiments appear to have had a goal of about 500 fish. In addi- tion to recovery percentages by type of gear, Table 5 also contains the mean and variance of the days-out Figured— NOTth- em part of south- eastern Alaska showing major statistical areas and subareas used for com- puter analysis of pink salmon tag recapture data. Table 1.— Closing dates of fishing season in major statistical subareas in southeastern Alaska as estimated from records of daily trap catches, 1938-42. Statistical subarea 1938 1939 1940 1941 1942 Outer Icy Strait 5 August 5 August 5 August 5 August 5 August Inner Icy Strait 7 August 8 August 8 August 8 August 12 August Lynn Canal 11 August 11 August 9 August 10 August 15 August Upper Chatham Strait 21 August 19 August 19 August 21 August 21 August Middle Chatham Strait 21 August 19 August 19 August 21 August 21 August Lower Chatham Strait 21 August 19 August 19 August 21 August 23 August Frederick Sound 21 August 19 August 19 August 21 August 23 August Stephens Passage 21 August 19 August 19 August 21 August 23 August Table 2.— Number of salmon traps in major statistical subareas in southeastern Alaska, 1938-42 and 1945. Statistical subarea 1938 1939 1940 1941 1942 1945 Outer Icy Strait 8 8 6 6 6 6 Inner Icy Strait 19 19 17 10 17 16 Lynn Canal 2 2 2 1 2 2 Upper Chatham Strait 19 19 18 13 18 17 Middle Chatham Strait 19 19 18 12 16 17 Lower Chatham Strait 5 5 4 4 4 4 Frederick Sound 16 16 16 16 16 14 Stephens Passage 12 12 11 11 11 13 Total 100 100 92 73 90 89 Table 3. --Number of tagging experiments conducted in southeastern Alaska areas during 1938-42 and 1945. Area of tagging 1938 1939 1940 1941 1942 1945 Total Icy Strait 0 0 0 6 3 0 9 Upper Chatham Strait 0 0 2 5 1^7 0 14 Middle Chatham Strait 0 0 2 6 2 0 10 Lower Chatham Strait 10 7 0 2 1 0 20 Salisbury Sound 0 0 0 0 0 2 2 Total 10 7 4 19 13 2 55 -/ Recoveries from two releases from trap WE-24 (Figure 3) on consecutive days, 24 and 25 July, could not be separated because identical tags were applied to all fish. Data from these two releases were pooled and treated as if one release had been made on 25 July 1942 for purposes of this report. Figure 3. — Locations and code numbers of principal trap sites, including those used as tagging stations, 1938-42 and 1945. 0 10 20 30 • TRAP LOCATION A TRAP SITE USED AS TAGGING SITE Table 4. --Number of tags released and number recovered 1n tagging experiments in southeastern Alaska, 1938-42 and 1945. No. releases Recoveries in Tota Trap s Seines Gill nets Streams-'' Unknown 1 Year No. % No. % No. % 1938 2,094 537 25.64 102 4.87 2 1 2 643 30.71 1939 2,100 550 26.19 129 6.14 2 5 5 686 32.67 1940 2,339 553 23.64 105 4.49 0 4 10 668 28.56 1941 7,620 2,534 33.25 396 5.20 0 17 22 2,952 38.74 1942 4,962 1,419 28.60 182 3.67 0 3 21 1,622 32.69 1945 1,357 17 1.25 217 15.99 0 0 222 456 33.60 Total 20.472 5.610 27.40 1,131 5.52 4 30 282 7,027 34.32 i/l Not included in number recovered. statistic for recoveries in traps and seines and the mean and variance of the number of miles traveled for recoveries in traps. MIGRATION ROUTES AS DETERMINED FROM TAG RECOVERIES The capture-recapture method of studying animal migration has the inherent limitation that no infor- mation is provided on the actual path followed from the point of original capture to the point of recapture unless multiple recaptures are made. Precise charting of migratory routes requires frequent position deter- mination without disturbing the normal migratory behavior of the animal. Multiple recaptures of the same tag, if any, were not reported for the 1938-42 and 1945 experiments. Determination of migratory pathways was further restricted by locations of release sites and the operation of the commercial fishery that provided the primary recovery effort. Because of these limitations, the analysis presented here is concerned only with broad aspects of the migration patterns. Migration Between Northern and Southern Southeastern Alaska The separation of stocks of southeastern Alaska pink salmon into virtually independent northern and southern runs, as mentioned in the historical review above, has been valuable to fishery management because it permits regulation of the pink salmon fishery as two units. Since all experiments covered in this report were conducted in the northern part of southeastern Alaska, evidence of separation consists only of the lack of recoveries in the commercial fishery operating in the southern part. Of 6,435 recoveries in known gear, only 102 (1.6%) were recovered in Sumner Strait, which forms the northern boundary of the southern part of southeastern Alaska. Only one tagged fish was recovered as far south as Clarence Strait (Fig. 1). The recoveries in Sumner Strait are compared with total recoveries by known gear from all releases in Icy Strait and Chatham Strait in Table 6. The percentage of tagged fish recovered in Sumner Strait increased from Icy Strait southward and was highest for lower Chatham Strait. Only one fish from the releases in Salisbury Sound (Table 3) was recovered in Sumner Strait. These results indicate little transfer of fish from the northern part to the southern part of southeastern Alaska and thus agree with the con- clusions of other investigators. Migration Through Peril Strait There are three possible channels through which pink salmon can enter the inner waters of northern southeastern Alaska from the ocean: Icy Strait, lower Chatham Strait, and Peril Strait (Fig. 2). Because Peril Strait was closed to fishing during the period of these experiments, no tag recoveries could be ex- pected from that area. The yearly occurrence of major runs in Icy Strait and lower Chatham Strait is well known, but there is little information available con- cerning migration of pink salmon through Peril Strait. In 1945, tagging experiments were conducted at the western entrance of Peril Strait in Salisbury Sound (Tables 3 to 5). In the first experiment (5 August), 635 pink salmon were tagged; in the second and third ex- periments (12 August), 722 were tagged. The 12 August experiments were combined because the release traps were only a few miles apart. Two types of tags, one bearing the single number 11 and the other the number 12, were used to identify fish released on 5 August. On 12 August, tags bearing the number 12 were again used and were distinguishable from those used on 5 August only by a hole punched in them. Tags with the number 13 were also released on 12 August. The original records for 1945 showed con- siderable confusion in differentiating between number 12 tags with and without the punched hole. Thus, number 12 tags recovered after 11 August could not be assigned to a single release. A total of 456 (33.6'^) of the tags were recovered; 41.6% of the total recoveries were made at the point of release. Four hundred and eight of the tags were recovered in Salisbury Sound, 12 in other inlets on the west coasts of Baranof and Chichagof islands, 1 in Sumner Strait, and 35 in Chatham Strait close to the east end of Peril Strait. No tags were recovered in Peril Strait or in spawning streams. The 1945 experiments do not provide conclusive evidence on the extent of migration eastward through Peril Strait. The data indicate that most fish in Salisbury Sound in August remained there, but more experiments are necessary. Only seven recoveries were made in Salisbury Sound of the 19,179 tagged fish released in inside waters during 1938-42. Six of the seven were released in Icy Strait and upper Chatham Strait. They may have traveled west through Icy Strait and then south along the west coast of Chichagof Island. The remain- ing recovery was released in lower Chatham Strait. The fact that none of the seven were released in mid- dle Chatham Strait suggests that there is no major migration westward through Peril Strait. Distribution of Trap Recoveries from Experiments in Icy Strait and Chatham Strait The number and percent of recoveries by statistical area for each experiment are listed in Tables 7 to 10 and illustrated in Figures 4 to 15. These figures were constructed as follows: A line was drawn along the center of the channel starting at the tagging station and extending through the main waterways in northern southeastern Alaska. The line was sub- divided into 20-mile intervals in both directions from the tagging station which was taken as the zero point. The number of recoveries per trap in each interval was calculated by alternating 3- and 4-day periods for 2 wk after the release; Sundays (when the fishery was closed) were usually included in the 4-day periods. Thus, each period included about 2% days of fishing. The number of tags recovered after the first 2 wk was small. The lines in Figures 4 to 15 connect the points representing average numbers of recoveries per trap per time period plotted at the centers of the 20-mile intervals. Abbreviations used in Figures 4 to 15 are: IS — Icy Strait; CS — upper and middle Chatham Strait; FS — Frederick Sound; SP— Stephens Passage; and LCS— lower Chatham Strait. In general, the experiments indicated that pink salmon entered the inner waters through Icy Strait and lower Chatham Strait and then spread eastward to Frederick Sound and north into Stephens Passage. For most experiments, fish continued to be recaptured in or near the trap from which they were released until the end of the season. Although the movements oi the centers of maximum density for most groups of tagged fish appeared to be directional, these directed movements were accompanied by a wide dispersion of smaller numbers of tags throughout the entire northern portion of southeastern Alaska. Icy Strait.^ — Six experiments were conducted in Icy Strait in 1941 (Fig. 4, Table 7) and three in 1942 (Fig. 5, Table 7). The recoveries from Icy Strait releases in 1941 in- dicated no clear-cut differences in distribution between the six experiments conducted during July and August. Recoveries of tagged fish in Icy Strait from releases in early August were restricted by the closure of fishing about 8 August. By the third day after release tagged fish from Icy Strait were spread throughout middle Chatham Strait. While some mov- ed rapidly others lagged behind, with the result that the fish were distributed along the entire route traversed. Usually the center of density of the tagged population was found in middle Chatham Strait dur- ing the second half of the first week (days out 4-6, Fig. 4). Although the tagged fish appeared to delay at the entrance to Frederick Sound, by the first part of the second week they were well distributed throughout Frederick Sound and lower Stephens Passage. During the third and fourth weeks after release it was usually difficult to recognize any center of density for one of the tagged populations. There was little migration into lower Chatham Strait of the fish released in Icy Strait in either 1941 or 1942; 1.04% of all releases in 1941 and 0.07% of those in 1942 were recovered in lower Chatham Strait. There were some striking differences between the movements of the tagged groups in 1941 and 1942. These differences may indicate a difference in the racial composition of the even-year and odd-year stocks in Icy Strait. Tagged pink salmon released in 1942 (Table 7) did not move to the east and south as rapidly as those released in 1941. The proportion ul- timately destined for Frederick Sound or Stephens Passage seemed to be less in 1942 than in 1941. This difference is especially large for the release made on 18 July 1942, as compared with the three July releases in 1941. Recoveries in Icy Strait from the July release in 1942 were slightly greater than from the July releases in 1941, but the percentage of recoveries in waters to the south and east in 1942 was markedly reduced. Total percentages recovered for the August releases in the 2 yr were similar; the 1942 experiments showed proportionately more fish recovered in Icy Strait and Table 5. --Summary of release and recovery information from tagging conducted in southeastern Alaska during 1938-42 and 1945. (See Figure 3 for location of traps where tags were released.) Trap number and release Total releases Total recoveries Percent recoveries No. recoveries in known gear Percent recoveries in Days 1 Tl 3ut for recoveries in raps Seines Miles traveled for recoveries in traps date Traps Seines Other Mean Variance Mean Variance Mean Variance Icy Strait IS-34 12 Aug. 1941 520 217 41.7 210 87.6 12.0 0.4 7.9 31.3 9.3 57.5 74.9 2,548 19 Aug. 1941 475 235 49.5 230 87.2 11.9 0.9 6.3 22.9 6.1 13.0 70.6 2.250 26 Aug. 1941 602 290 48.2 277 85.5 13.5 1.0 7.5 28.8 9.7 34.5 76.5 2.067 2 Sept. 1941 500 177 35.4 166 80.8 18.6 0.6 7.8 24.9 8.1 24.1 93.0 2,138 5 Sept. 1941 500 141 28.2 131 73.1 25.5 1.4 6.7 19.3 6.9 17.8 83.7 2.159 13-26 7 Sept. 1941 300 114 38.0 96 80.7 17.5 1.8 6.4 15.1 4.9 11.2 87.2 1,250 IS-34 18 Aug. 1942 485 176 36.3 176 77.3 21.0 1.7 8.6 44.1 7.6 35.1 46.0 818 2 Sept. 1942 495 160 32.3 160 78.8 20.0 1.2 7.3 24.2 6.1 54.2 44.1 810 IS-24 9 Sept. 1942 496 174 35.1 174 92.0 8.0 0.0 5.2 12.3 5.5 18.5 34.6 759 Upper Chath. am Strait ME-36 13 Sept. 1940 500 150 30.0 150 85.3 14.7 0.0 2.1 3.0 2.9 6.8 24.9 1.498 WE-25 13 Sept. 1940 500 127 25.4 120 77.2 22.1 0.7 2.8 3.7 4.5 6.8 38.2 ~ WE-24 13 Aug. 1941 375 116 30.9 116 87.9 12.1 0.0 6.8 29.6 10.6 98.8 56.2 " 19 Aug. 1941 74 25 33.8 24 83.3 16.7 0.0 6.4 23.9 9.9 86.8 26.8 - 26 Aug. 1941 500 257 51.4 247 89.5 10.5 0.0 6.7 27.7 6.9 20.7 55.1 ~ 2 Sept. 1941 500 172 34.4 161 82.0 15.7 2.3 6.5 16.3 10.4 33.7 52.0 - 9 Sept. 1941 300 101 33.7 90 79.0 17.0 4.0 5.8 8.6 10.7 86.2 46.8 - 25 Aug. 1942 250 85 34.0 84 96.5 2.3 1.2 10.2 50.4 - - 16.8 - 2 Sept. 1942 249 86 34.5 85 87.2 11.6 1.2 7.6 31.4 - - 14.7 - WE-32 9 Sept. 1942 498 171 34.3 171 96.5 2.9 0.6 5.1 14.6 - - 24.6 853 16 Sept. 1942 499 157 31.5 157 93.0 7.0 0.0 2.7 2.2 - - 17.1 338 WE-24 18 Sept. 1942 499 88 17.6 88 90.9 8.0 1.1 2.0 1.7 - - 28.3 - WE -43 18 Sept. 1942 321 113 35.2 96 - - - - - - - - - Hiddlt i Chatham Strait WE-69 12 Sept. 1940 999 322 32.2 320 84.5 13.0 2.5 4.2 3.0 5.6 11.6 32.5 16 Sept. 1940 400 69 17.3 68 79.7 18.8 1.5 2.3 1.8 4.0 3.8 38.3 WE-65 13 Aug. 1941 150 59 39.3 59 89.8 10.2 0.0 5.3 12.2 — - 35.1 WE-69 20 Aug. 1941 424 223 52.6 223 89.7 9.9 0.4 4.4 18.9 10.4 33.7 35.2 10 T«ble 5. --Summary of release and recovery information from tagging conducted in southeastern Alaska during 1938-42 and 1945. (S( Figure 3 for location of traps where tags were released. )— Continued. Trap number and release Total releases Total recoveries Percent recoveries No. recoveries in known gear Percent recoveries i n Daysy Dut for recoveries in raps Seines Wies travelsd for recover1»t in traps date Traps Seines Other Mean Variance Mean V ariance Mean Variance 27 Aug. 1941 500 251 50.2 251 90.8 9.2 0.0 6.1 33.6 10.7 86.2 36.9 — 3 Sept. 1941 500 194 38.8 193 87.1 12.4 0.5 5.3 10.6 6.9 12.7 32.5 - 10 Sept. 1941 300 107 35.7 107 84.1 15.9 0.0 5.6 9.0 7.3 5.4 31.6 ~ 17 Sept. 1941 400 135 33.8 135 86.7 13.3 0.0 3.0 1.1 3.0 0.8 30.4 - 11 Sept. 1942 177 67 37.9 67 82.1 17.9 0.0 4.3 7.8 - - 31.8 - IS Sept. 1942 496 168 33.9 168 97.6 2.4 0.0 3.5 4.4 -- — 23.0 -■ Lower Chatham Strait EA-45 7 Aug. 1938 325 61 18.8 59 91.8 4.9 3.2 7.1 59.9 - - 14.0 404 8 Aug. 1938 174 27 15.5 27 96.3 3.7 0.0 6.2 52.4 - - 25.4 918 14 Aug. 1938 100 18 18.0 18 94.4 5.6 0.0 10.6 59.6 - - 38.4 899 15 Aug. 1938 100 19 19.0 19 94.7 5.3 0.0 16.2 94.3 - - 63.8 659 23 Aug. 1938 100 24 24.0 24 91.7 8.3 0.0 6.5 34.8 - - 53.4 783 26 Aug. 1938 71 25 35.2 25 96.0 4.0 0.0 5.8 35.6 ~ - 30.9 796 6 Sept. 1938 375 120 32.0 120 80.8 19.2 0.0 6.2 13.2 8.2 11.5 31.2 788 EA-46 8 Sept. 1938 124 55 44.4 54 80.0 18.2 1.8 3.8 6.2 6.0 3.3 13.6 244 EA-45 9 Sept. 1938 350 168 48.0 167 82.7 16.7 0.6 3.6 4.7 6.0 8.3 19.7 340 12 Sept. 1938 375 125 33.3 125 74.4 25.6 0.0 3.5 3.8 4.3 4.2 18.1 608 EA-46 11 Aug. 1939 75 17 22.7 17 82.4 17.6 0.0 10.8 41.7 ~ - 47.5 511 EA-45 16 Aug. 1939 425 131 30.8 129 93.1 5.3 1.5 7.4 39.5 - - 59.8 314 EA-46 23 Aug. 1939 115 22 19.1 22 72.7 27.3 0.0 5.6 22.7 ~ - 37.0 431 EA-45 4 Sept. 1939 385 125 32.5 125 81.6 18.4 0.0 5.4 13.5 6.1 9.9 46.4 507 5 Sept. 1939 125 47 37.6 46 76.6 21.3 2.1 7.2 21.1 9.1 12.1 43.2 753 EA-46 6 Sept. 1939 475 154 32.4 154 78.6 21.4 0.0 5.4 16.6 8.8 10.3 30.2 820 EA-45 13 Sept. 1939 500 190 38.0 186 73.2 24.7 2.1 3.8 3.1 4.2 1.1 20.6 737 10 Sept. 1941 300 74 24.7 74 90.5 9.5 0.0 4.6 8.5 - - 41.3 370 16 Sept. 1941 400 66 16.5 65 86.4 12.1 1.5 3.8 1.0 ~ - 32.7 217 13 Sept. 1942 497 176 35.4 176 88.7 11.3 0.0 5.9 5.3 6.9 12.6 44.0 607 WE-11.3 SalisI Dury Sound 5 Sept. 1945 635 219 34.5 140 3.8 62.2 34.0 - - 5.7 20.6 - - We-11.2 12 Sept. 1945 722 237 32.8 94 4.1 39.2 56.7 - -- 4.3 12.2 - - 11 Table 6. --Comparison between recoveries 1n Sumner Strait and total recoveries (grouped by release area and month), July and August, 1938-42 and 1945. Release area Total Sumner Strait Percent recoveries in and month recoveries-' recoveries Sumner Strait Icy Strait July 893 2 0.22 August 727 2 0.27 Upper Chatham Strait July 471 1 0.21 August 1,114 8 0.72 Middle Chatham Strait July 533 9 1.69 August 1,053 25 2.37 Lower Chatham Strait July 344 21 6.10 August 1,300 34 2.62 All area combined July 2,241 33 1.47 August 4,194 69 1.64 Total 6,435 102 1.59 -^Total recoveries include only recoveries in known type of gear and with a known recovery location. upper Chatham Strait. A direct comparison is dif- ficult, however, because of the proximity of the release dates to the closing dates for the season. In summary, it appears that although fish tagged in Icy Strait were recovered throughout the fishing grounds in southeastern Alaska, the prevailing move- ment was eastward through Icy Strait, southward into Chatham Strait, and then eastward into Frederick Sound and Stephens Passage (Figs. 4, 5). Superim- posed on this basic directed movement was a promi- nent nondirected or random type of movement. The proportion of Icy Strait fish going into Lynn Canal and lower Chatham Strait does not appear to be significant. A large percentage of the fish tagged in Icy Strait in 1941 moved very rapidly through Icy Strait into the middle Chatham Strait area. Upper Chatham Strait. — Tagging experiments were conducted in upper Chatham Strait in 1940, 1941, and 1942. Two releases were made in 1 day (13 August) in 1940 (Fig. 6, Table 8). One release was at trap WE-36 on the east side of upper Chatham Strait and the other at trap WE-25 on the west side. The fishery in Icy Strait had already closed by 13 August and there were only 6 days remaining until the end of the season in Chatham Strait. The distributions of recoveries from the two releases did not differ greatly. Most recoveries were made in Chatham Strait near the tagging trap; however, by the second half of the first week after release, the tagged fish had scattered throughout Frederick Sound and Stephens Passage. The bulk of the recoveries of the group released from WE-36 was made within a 9-mile radius of the tagging trap (Fig. 6). Aside from the relatively large numbers recovered in the immediate vicinities of the release points, most of the remaining tagged fish moved rapidly to the south and then east into Frederick Sound. Only one tag of the total recoveries from both releases was from lower Chatham Strait. Data from four releases in upper Chatham Strait in 1941 are shown in Figure 7 and Table 8. In addition, data from one experiment in 1941 (19 July) with fewer than 50 recoveries are included in Table 10. The general movement of fish tagged and released in upper Chatham Strait in 1941 resembled that of the fish tagged in eastern Icy Strait in 1941. A few tagged Figure 4. — Tag recoveries per trap by 20-inile intervals mea- sured from points of release in Icy Strait, 1941-42. The average number of recoveries per trap per time period are plotted at the centers of the 20-mile intervals. 12 0 3 DAYS OUT JULY \2 IS it 200 200 200 100 CS I FS ISP 100, . _ --- CS i FS ISP" . IS MILES FROM TRAP SITE CS'^°I FS Ispl ">' 100 CS I FS 200 13 Table 7. --Recovery areas of tags released from traps in Icy Strait, 1941-42. Year and date of release (trap number No. releases Icy No. Strait % Upper and Middle Chatham Strait No. % Lower Chatham Strait No. % Frederick Sound Sumner Strait No. % Total in parentheses) No. % No. % 1941 12 July (IS-34) 520 63 12.1 90 17.3 6 1.2 30 5.8 1 0.2 190 36.5 19 July (IS-34) 475 70 14.7 107 22.5 6 1.3 22 4.6 0 0.0 205 43.2 26 July (IS-34) 602 70 11.6 138 22.9 5 0.8 35 5.8 0 0.0 248 41.2 2 Aug. (IS-34) 500 23 4.6 84 16.8 4 0.8 31 6.2 1 0.2 143 28.6 5 Aug. (IS-34) 500 22 4.4 59 11.8 3 0.6 18 3.6 0 0.0 102 20.4 7 Aug. (IS-26) 300 0 0.0 62 20.7 5 1.7 21 7.0 0 0.0 88 29.3 Total 2,897 248 8.6 540 18.6 29 1.0 157 5.4 2 0.1 97 6 33.7 1942 18 July (15-34) 485 81 16.7 52 10.7 0 0.0 3 0.6 0 0.0 136 28.0 2 Aug. (IS-34) 495 77 15.6 47 9.5 0 0.0 2 0.4 0 0.0 126 25.4 9 Aug. (IS-24) 496 17 3.4 130 26.2 1 0.2 12 2.4 0 0.0 160 32.3 Total 1,476 175 11.9 229 15.5 1 0.1 17 1.2 0 0.0 422 28.6 < a. 0-3 LU R > O u LU a. 1 00 50 0-3 DAYS OUT JULY 18 IS-3H AUGUST 2 IS-3a I 100 I I 200 100 I I 200 CS FS SP' AUGUST 9 IS-2a IS "I I iod CS FS'SP 200 4-6 DAYS OUT I I ^O" 100 I I 200 CS ' FS SP" 7-10 DAYS OUT I ^00 100 I I 200 I FS SPi iod 0 I 100 IS ' CS FS'SP IS ' CS FS'sP MILES FROM TRAP SITE 200 11-13 DAYS OUT .Z:-:^ I 100 I I 200 100 I I 200 ' FS SP' I iod CS FS'sP Figure 5. — Tag recoveries per trap by 20-inile intervals measured from points of release in Icy Strait, 1942. The average number of recoveries per trap per time period are plotted at the centers of the 20-mile intervals. 14 I 0 I h" I ' cs 'fs' sp MILES FROM TRAP SITE Figure 6. — Tag recoveries per trap per time period by 20-inile intervals measured from the point of release in upper Chatham Strait, 1940. fish from both the July and August releases in upper Chatham Strait were recovered to the northwest of the point of release in northern Chatham Strait and in Icy Strait, but most tags were recovered in middle Chatham Strait and in Frederick Sound. For all of the 1941 releases except the last one on 9 August, the center of density of the tagged population moved rapidly to the middle Chatham Strait area and remained there for the first l'/2 wk after release (Fig. 7). For the 9 August release the center of maximum density shifted from middle Chatham Strait to Frederick Sound at the beginning of the second week. There was a minor movement of tagged fish into lower Chatham Strait in 1941. The major movement, however, was clearly eastward into Frederick Sound from middle Chatham Strait. Most of the recoveries were made in Chatham Strait during the first week after release. Of course, the usual trickle of scattered recoveries continued until the end of the fishing season. The recovery percentage of 46% from the 26 July release was unusually high and was the result of unusually high recovery percentages in both Chatham Strait and Frederick Sound. Six releases were made in upper Chatham Strait in 1942, all quite late in the season (Fig. 8, Table 8). The Table 8.— Recovery areas of tags released from traps in Upper Chatham Strait, 1940-42. Recoveries ir Year and date Upper and Middle Lower of release Chatham Chatham Frederick Sumner (trap number No. releases Icy No. Strait i Strait No. % Strait No. % So jnd Strait No. % Total in parentheses) No. % No. i 1940 13 Aug. (WE-36) 500 0 0.0 109 21.8 1 0.2 18 3.6 0 0.0 128 25.6 13 Aug. (WE-25) 500 0 0.0 77 15.4 0 0.0 21 4.2 0 0.0 98 19.6 Total 1,000 0 0.0 186 18.6 1 0.1 39 3.9 0 0.0 226 22.6 1941 13 July (WE-24) 375 13 3.5 46 12.3 9 2.4 34 9.1 0 0.0 102 27.2 19 July (WE-24) 74 5 6.8 15 20.3 0 0.0 1 1.4 0 0.0 21 28.4 26 July (WE-24) 500 14 2.8 146 29.2 10 2.0 60 12.0 0 0.0 230 46.0 2 Aug. (WE-24) 500 9 1.8 94 18.8 3 0.6 33 6.6 1 0.2 140 28.0 9 Aug. (WE-24) 300 0 0.0 57 19.0 1 0.3 19 6.3 0 0.0 77 25.7 Total 1.749 41 2.3 358 20.6 23 1.3 147 8.4 1 0.1 570 32.6 1942 25 July (WE-24) 250 21 8.4 56 22.4 0 0.0 5 2.0 0 0.0 82 32.8 2 Aug. (WE-24) 249 12 4.8 59 23.7 0 0.0 4 1.6 0 0.0 75 30.1 9 Aug. (WE-32) 498 18 3.6 134 26.9 0 0.0 13 2.6 0 0.0 165 33.1 16 Aug. (WE-32) 499 0 0.0 143 28.7 1 0.2 2 0.4 0 0.0 146 29.3 18 Aug. (WE-24) 499 0 0.0 71 14.2 1 0.2 8 1.6 0 0.0 80 16.0 18 Aug. (WE-43) 321 0 0.0 71 22.1 0 0.0 2 0.6 0 0.0 73 22.7 Total 2,316 51 2.2 534 23.1 2 0.1 34 1.5 0 0.0 621 26.8 15 AUGUST 9 WE 2H 100 I FS ISP 100 I I FS 'SP IS I CS MILES FROM TRAP SITE J ' FS 'SP Figure 7. — Tag recoveries per trap by 20-niile intervals measured from the point of release in upper Chatham Strait, 1941. first release was on 25 July and the last on 18 August. The distributions of recoveries from all releases in- dicate extensive milling of pink salmon in the eastern end of Icy Strait and throughout upper and middle Chatham Strait. The type of movement observed in 1942 is in direct contrast to that observed in 1941, when the fish moved rapidly to the south. For the earlier experiments in 1942 the center of density remained at the tagging station and there was a slow diffusion in both directions. In the later releases the closure of the fishing season in Icy Strait restricted recoveries there. Nevertheless there was only a slight shift of the center of density of the tags to the south of the release point. Although there was some movement of tagged fish into Frederick Sound from releases in August, this movement was of a secondary nature. The 1942 experiments did not show any clear progression of centers of concentration to the south and east in successive recovery periods as did the 1941 experiments. Recoveries from the two experiments on opposite sides of the channel on 18 August 1942 indicate that fish tagged in the northwestern part of upper Chatham Strait (at trap WE-24) had ceased moving rapidly and were probably milling about near the spawning streams, whereas a large pecentage of those tagged to the south on the eastern shore (at trap WE- 43) were still moving actively through Chatham Strait headed for the inner waters of Frederick Sound and Stephens Passage. In summary, the results of the tagging experiments conducted in upper Chatham Strait supported the general movement patterns hypothesized above on the basis of releases made in Icy Strait. In 1941, and to a lesser extent in 1940, fish tagged in upper Chatham Strait moved rapidly southward in Chatham Strait and then dispersed into Frederick Sound. The most dense concentrations of tagged fish remained in the middle Chatham Strait area for the first 1 V2 wk after release. In 1942, however, the fish tagged in upper 16 I 100 I |?oo Id I ">o I 200 |o I '<>o| I loo I o I lool | ' FS ■$? ' IS ' CS ' FS 'SP IS ' CS ' FS "SP IS ' CS ' FS 'sp MILES FROM TRAP SITE Figure 8. — Tag recoveries per trap per time period by 20-inile intervals measured from the point of release in upper Chatham Strait, 1942. Chatham Strait exhibited a much stronger tendency to linger in the upper Chatham Strait area and a much weaker tendency to migrate southward and eastward. There appears to be considerable variabili- ty from year to year in the racial composition of the pink salmon runs found in upper Chatham Strait in the months of July and August. Middle Chatham Strait.— Two tagging experiments were conducted in middle Chatham Strait in 1940, six in 1941, and two in 1942. All releases of tagged fish, with the exception of that on 13 July 1941, were made from trap WE-69 within 15 miles of the junction of Chatham Strait and Frederick Sound. The exception was from trap WE-65, 4 miles north of the site of the other releases. Results from the two 1940 experiments are shown in Figure 9 and Table 9. The first release (12 August) in- volved 999 tagged fish, and thus constituted the largest single release of the experiments covered in 17 0 I I 100 ioo| 7-10 DAYS OUT 100 100 IS" CS ' FS ' SP' IS ' MILES FROM TRAP SITE 100 CS FS ' SP' 100 Figure 9. — Tag recoveries per trap per time period by 20-mile intervals measured from the point of release in middle Chatham Strait, 1940. Table 9. --Recovery areas of tags released from traps in Middle Chatham Strait, 1940-42. Recover ies in Uppe " and Year and date Middle Lower of release Chatham Chatham Frederick Sumner (trap number No. releases Icy No. Strait % Strait No. % Strait No. % Sound Strait No. % Total in parentheses) No. i No. % 1940 12 Aug. (WE-69) 999 0 0.0 86 8.6 8 0.8 178 17.8 0 0.0 272 27.2 16 Aug. (WE-69) 400 0 0.0 14 3.5 2 0.5 39 9.8 0 0.0 55 13.8 Total 1,399 0 0.0 100 7.1 10 0.7 217 15.5 0 0.0 327 23.4 1941 13 July (WE-65) 150 1 0.7 7 4.7 11 7.3 34 22.7 0 0.0 53 35.3 20 July (WE-69) 424 4 0.9 30 7.1 26 6.1 140 33.0 0 0.0 200 47.2 27 July (WE-69) 500 3 0.6 74 14.8 9 1.8 137 27.4 5 1.0 228 45.6 3 Aug. (WE-69) 500 0 0.0 38 7.6 4 0.8 127 25.4 0 0.0 169 33.8 10 Aug. (WE-69) 300 0 0.0 16 5.3 7 2.3 67 22.3 0 0.0 90 30.0 17 Aug. (WE-69) 400 0 0.0 8 2.0 5 1.3 102 25.5 2 0.5 117 29.3 Total 2,274 8 0.4 173 7.6 62 2.7 607 26.7 7 0.3 857 37.7 1942 11 Aug. (WE-69) 177 0 0.0 24 13.6 2 1.1 28 15.8 0 0.0 54 30.5 15 Aug. (WE-69) 496 0 0.0 81 16.3 0 0.0 74 14.9 0 0.0 155 31.3 Total 673 0 0.0 105 15.6 2 0.3 102 15.2 0 0.0 209 31.1 18 this report. For the second experiment (16 August), only 13.8% of the tags were recovered because it was close to the end of the fishing season. The most promi- nent feature of the recoveries from both of these releases was the rapid movement of a large proportion of the tagged fish into Frederick Sound; 66.4% of the total recoveries from both releases were made in Frederick Sound. Less than 1% were made in lower Chatham Strait. Although there was some dispersion northward into middle Chatham Strait, few tagged fish traveled as far north as upper Chatham Strait. It appears that most fish in the vicinity of trap WE-69 in August were en route to streams in Frederick Sound and Stephens Passage. The most noticeable feature of the distributions of recoveries from the six experiments in 1941 (Fig. 10, Table 9) is the uniformly high percentage returned from Frederick Sound — 70.8%. In 1941 the movement of tagged pink salmon from middle Chatham Strait into Frederick Sound was even more rapid and more pronounced than in 1940. Only a negligible movement in the direction of Icy Strait was indicated. Recoveries in middle and upper Chatham Strait were not large, even though they were augmented by heavy recap- tures in trap WE-67 just 2 miles from the point of release. Proportionately more of the tagged fish entered lower Chatham Strait in 1941 than in either 1940 or 1942. This was partly the result of the timing of the releases. Only in 1941 were releases made in Ju- ly; recoveries in lower Chatham Strait from these July releases were higher than from the August releases in any of the 3 yr (Table 9). In 1941, 2.7% of the total recoveries from all six releases were made in lower Chatham Strait. The geographical distributions of the recoveries from the two releases in 1942 in middle Chatham Strait were similar (Fig. 11, Table 9). The distribution of recoveries in 1942 differed markedly from those in 1940 and 1941. Tagged fish were recaptured in about equal numbers in Frederick Sound and in middle Chatham Strait. The 48.6% of the recoveries made in Frederick Sound are considerably lower than the 66.4% in 1940 and the 70.8% in 1941. Recoveries in lower Chatham Strait were scarce in 1942; only two tagged fish were reported from there. Recovery patterns for both experiments in 1942 were symmetrically distributed about the release point. In summary, tagged fish released in middle Chatham Strait showed little movement into the lower Chatham Strait area. In 1941, and to a somewhat lesser extent in 1940, there was a strongly directed movement of tagged pink salmon from mid- dle Chatham Strait into Frederick Sound and southern Stephens Passage. Fish tagged in 1942 did not exhibit a strongly directed movement but rather milled about in the general area of the release point in middle Chatham Strait, gradually dispersing both northward into Chatham Strait and eastward into Frederick Sound. The difference between the migratory behavior of fish tagged in 1942 and those tagged in 1940 and 1941 in middle Chatham Strait is exactly the same as observed for fish tagged in Icy Strait and upper Chatham Strait in these 3 yr. Lower Chatham Strait. — There were 10 ex- periments in lower Chatham Strait in 1938, 7 in 1939, 2 in 1941, and 1 in 1942. Only four of the experiments in each year in 1938 and 1939 provided enough recoveries to give a coherent picture of the movement of the tagged fish. All of the releases in lower Chatham Strait were made from either trap EA-45 or trap EA- 46 in Tebenkof Bay. The results of the 1938 experiments (Fig. 12, Table 10) show that the tagged pink salmon were recaptured mainly in lower Chatham Strait — 79.5% of the recoveries were made in the six traps along the west coast of Kuiu Island within 22 miles of the point of release. Of the combined recoveries from the four releases, 15.8% were made in Frederick Sound, 2.1% in middle Chatham Strait, and 2.6% in Sumner Strait. Although the total percentage of recoveries from the 1939 experiments (Fig. 13, Table 10) remained remarkably constant from the first release on 16 July until the last on 13 August, the geographic distribu- tion of the recoveries changed drastically between the first and last releases. The percentage recoveries returned from Frederick Sound were as follows: 91.8% for the 16 July release, 62.7% for 4 August, 33.1% for 6 August, and 16.5% for 13 August. And, as the percent- age of recoveries taken in Frederick Sound decreased, the percentage taken in lower Chatham Strait in- creased (Table 10). The strong movement into Frederick Sound for the earlier releases in 1939 is in sharp contrast to the results obtained in 1938. Although the timing of the 1938 releases was similar to that of the 1939 releases, the relative numbers of recoveries made in Frederick Sound and Stephens Passage were consistently low for all of the 1938 ex- periments. There was a minor movement of tagged pink salmon into middle Chatham Strait and into Sumner Strait in 1939; 6.4% of the recoveries were from middle Chatham Strait and 5.2% from Sumner Strait. For the last release in 1939, as in 1938, the fish showed a strong tendency to linger in Tebenkof Bay near the release trap. The distribution of recoveries from the two tagging experiments in lower Chatham Strait in 1941 are shown in Figure 14 and Table 10. Releases were made on 10 and 16 August; the recoveries were restricted because it was close to the end of the fishing season. For both experiments the recoveries were apportioned in a similar manner between general recovery areas (Table 10): 62.4% of the pooled recoveries were from Frederick Sound, 32.0% from lower Chatham Strait, and 5.6% from upper and middle Chatham Strait. The center of density of the tagged fish released on 10 19 Figure 10. — Tag recoveries per trap per time period by 20-niile intervals measured from the point of release in middle Chatham Strait. 1941. 100 IS 0 I I 100 lOOl cs I FS I spi is' cs MILES FROM TRAP SITE 0 I I lo'o Tool 1 FSlspl isl CS I FS I SPl 20 0-3 DAYS OUT August 11 WE-69 ISl CS I FS 'SP FS I SPl is' CS I FS • SPI MILES FROM TRAP SITE CS I FS ISPl Figure 1 1 . — Tag recoveries per trap per time period by 20-inile intervals measured from the point of release in middle Chatham Strait, 1942. August had moved into Frederick Sound during the latter part of the first week and during the second week continued to drift eastward. Thus, in 1941 the migratory behavior of fish tagged during August in lower Chatham Strait was quite different from that of those tagged during August in 1938 and in 1939, when more of the fish remained near the tagging station in- stead of moving into Frederick Sound. The infrequent recoveries in lower Chatham Strait from releases in Icy Strait and in upper and middle Chatham Strait in 1941, coupled with the sparse recoveries in the northern areas from releases in lower Chatham Strait, indicate that most of the fish moving through lower Chatham Strait in mid-August of 1941 were en route to streams in lower Chatham Strait, Frederick Sound, and Stephens Passage. The results from the single release in lower Chatham Strait in 1942 are given in Figure 15 and Table 10. For 68 of the tags recovered from this experi- ment, only the date of recovery was given. The dis- tribution of the recoveries for which the locations were known was similar to the distributions observed for the 1941 experiments except that relatively more tagged fish were recaptured in middle Chatham Strait. However, unless it is assumed that the 89 tags with known recovery locations constituted a represen- tative sample of the recoveries, the movements in- dicated cannot be accepted without serious reserva- tion. Summary and Discussion of General Migration Patterns as Determined from Tag Recaptures From each of the pink salmon tagging experiments a sequence of spatial distributions of tag recaptures per unit of effort during successive recovery periods was determined. The apparent migratory pattern generated by the recaptures from a single release may be described as the result of an interaction of two basic types of movement — one directional, the other random. The directional component is defined as a movement with complete spatial orientation, whereas the random component is a nondirected movement in which the fish disperse in all possible directions about a center of density. It is obvious, of course, that any particular geographical distribution of recoveries is affected by the distribution of recovery effort and also by the particular mixture of racial stocks represented in the population of tagged fish. Verhoeven (see footnote 6) concluded that pink salmon migration consisted largely of a random to- and-fro movement. He was influenced by multiple recaptures of several fish tagged in the Ketchikan area of southeastern Alaska, and it is not possible to deter- mine if the successive recapturing altered the natural migratory behavior of the fish. The experiments reported here neither confirm nor definitely refute Verhoeven's hypothesis of random to-and-fro move- ment. However, the results of these experiments do 21 3 - 2 - 0-3 DAYS OUT JULY 7 EA-'45 a.i < H UI 0. 5° LU u m q: q:3 LU DQ 5 :3 2 ? I I lioo 200 AUGUST 6 -EA H5 I h" .^, 12.00 / AUGUST 9 EA-45 I I 100 1113 DAYS OUT ? I I I 100 200 200 |100 200 I 1''°° AUGUST 12 EA-15 0 I I llOO 1 FS r rs <;pl CS > FS LCS SPl 200 Oil 100 200 Oil jlOO CS IPSLCSSPI CS 'FSLCSSP' MILES FROM TRAP SITE 200 Oil 100 CS IFS LCS SPI Figure 12. — Tag recoveries per trap per time period by 20-inile intervals measured from the point of release in lower Chatham Strait, 1938. indicate that the movement of pink salmon can be more adequately described as consisting of a random and a directional component with the relative impor- tance of the two components varying from year to year. In 1942 fish tagged in Icy Strait, upper Chatham Strait, and middle Chatham Strait distributed them- selves as might have been predicted on the basis of the random to-and-fro hypothesis. In 1941 the move- ments of fish tagged at the same locations showed a much stronger directional component. These tagged fish migrated in large numbers to the Frederick Sound-Stephens Passage region. Thus, it appears that the particular mixture of racial stocks in a given sec- tor of the fishing grounds varies greatly from year to year. There was some indication from these ex- periments that the random component of movement was relatively stronger in even years. The apparent random component of the migration of pink salmon may be an inherent characteristic of this species, which spawns in a large number of widely dispersed streams. A different behavior might be ex- pected for sockeye salmon, Oncorhynchus nerka, seeking one major spawning ground. The results of these experiments do not provide information on the cause of the random dispersion of tagged fish. This effect could be caused either by the erratic wanderings of tagged fish or could be the result of the superim- position of a great number of directional migrations 22 Table 10. --Recovery areas of tags released from traps 1n Lower Chatham Strait, 1938-39 and 1941-42. Recoveries in Upper and Year and date Middle Lower of release Chatham Chatham Frederick Sumner (trap number No. releases Icy Strait No. % Strait Strait No. i No. i Sound Strait No. % Total in parentheses) No. t No. t 1938 7 July (EA-45) 6 Aug. (EA-45) 9 Aug. (EA-45) 12 Aug. (EA-45) Total 1939 16 July (EA-45) 4 Aug. (EA-45) 6 Aug. (EA-46) 13 Aug. (EA-45) Total 1941 10 Aug. (EA-45) 16 Aug. (EA-45) Total 1942 13 Aug. (EA-45) 325 375 350 375 1,425 425 385 475 500 1,785 300 400 700 497 0 0.0 0 0.0 0 0.0 0 0.0 1 0.3 47 14.5 8 2.5 4 1.1 65 14.7 30 8.0 1 0.3 124 35.4 12 3.4 2 0.5 80 21.3 11 2.9 0.0 56 17.2 2.1 97 25.9 0.6 139 39.7 0.0 93 24.8 0.0 0.6 306 21.5 61 4.3 10 0.7 385 27.0 0 0.0 0 0.0 2 0.5 112 26.4 0 0.0 12 3.1 19 4.9 64 16.6 0 0.0 10 2.1 63 13.3 40 8.4 0 0.0 9 1.8 105 21.0 23 4.6 8 1.9 122 28.7 7 1.8 102 26.5 8 1.7 121 25.5 2 0.4 139 27.8 0.0 31 1.7 189 10.6 239 13.4 25 1.4 484 27.1 0 0.0 6 2.0 20 6.7 41 13.7 0 0.0 1 0.3 20 5.0 37 9.3 0 0.0 67 22.3 0 0.0 58 14.5 0.0 7 1.0 40 5.7 0.0 23 4.6 11 2.2 78 11.1 55 11.1 0 0.0 125 17.9 0.0 8! ;9l^17.9 — Does not include 68 tags which were recorded as trap recoveries and were accompanied by the dates of recovery but not the locations. for tagged groups composed of a variety of racial stocks spawning in streams located in different direc- tions from the point of release. In spite of the considerable intraseasonal and in- terseasonal variability observed, the following salient features of these experiments are still of considerable interest for determining management policy for fisheries in southeastern Alaska. 1. Results of these experiments confirm the find- ings of other investigators showing the virtual separa- tion for pink salmon management of southeastern Alaska into a northern and a southern part with Sumner Strait composing the northern boundary of the southern part. 2. The pink salmon stocks found in Icy Strait, up- per Chatham Strait, and middle Chatham Strait appear to be fairly distinct from those found in lower Chatham Strait. There was only a limited exchange of fish between lower Chatham Strait and middle Chatham Strait. Fishing in Icy Strait, upper Chatham Strait, and middle Chatham Strait would not be expected to have a major effect on spawning es- capements in the lower Chatham Strait area and cor- respondingly the fishery in lower Chatham Strait would not have a great effect on the stocks from mid- dle Chatham Strait, upper Chatham Strait, and Icy Strait. Any effect would diminish with increasing dis- tance moving northward from lower Chatham Strait. 3. Stocks spawning in the watersheds adjoining Frederick Sound and Stephens Passage use both Icy Strait and lower Chatham Strait as major passageways from the ocean. The numbers of fish reaching Frederick Sound and Stephens Passage would be influenced by the intensities of fishing along both of these routes of entry. The experiments reported here do not provide any information on the relative numbers of fish using these two routes of en- try. 4. There was a strong intraseasonal trend in the movement patterns. It was generally observed that the earlier in the season the group was tagged, the larger was the proportion of fish destined for spawning grounds distant from the point of release. Usually fish tagged later in the season exhibited a more restricted range of movements about the point of release. 23 cs I 0 I I i'oo 100 I 0 I I 100 100 I 0 I I i I 'LC5 Fs'sp' rs ' ii r.s F?;'<;p ' rs ' m r<; pc' <;pi CS 100 I 0 I I >00 100 0 I ^00 'LCSFS'SP' CS ' 'LCSFS'SP' CS ' ■! r«; F=;l i^p- MILES FROM TRAP SITE 'LCS FS' SP" Figure 13. — Tag recoveries per trap per time period by 20-inile intervals measured from the point of release in lower Chatham Strait, 1939. RELATIVE ABUNDANCE AND MIGRATION AS DETERMINED FROM TRAP CATCH DATA Neither total trap catch nor catch per trap could be used to estimate the size of the pink salmon runs in the different years because in all years and in all areas the fishing season closed about the time of greatest abundance of fish. Thus, catch data did not measure the late parts of the runs. Furthermore, no informa- tion was available on seine catches or on escapement to spawning streams. Both total trap catch and catch per trap by statistical area are listed in Table 11. The number of traps used in the calculations was the number of traps for which weekly catches were known. The catch per trap and total catch in different years were not proportional; in particular, the largest catch was taken in 1941 when the fewest traps operated. The total catch was influenced more by the number of fish available than by the number of traps. Both total catch and catch per trap show that the largest run was in 1941 and the smallest in 1945. Runs in 1938 and 1940 were approximately equal and were larger than the 1939 run but smaller than the 1942 run. The catch data and tagging data are in general agreement with respect to the indicated paths of 24 3 - Ui ^2- ^ 0-3 DAYS OUT AUGUST 10 EA-45 uj 100 I 0 I I VOO 100 I 1-1 - ai ^, in UJ cn UJ > o u LU on LU CQ 5 Z 4-6 DAYS OUT 7-10 DAYS OUT 11-13 DAYS OUT 0 I I VOO 100 I 0 I I 100 3 - AUGUST 16 EA-45 100 CS 0 I I 100 100 Lcs'fs'sp' CS 0 I 'LCS' FS 100 SP' CS ' MILES FROM TRAP SITE ■lcs'fs' SP' 100 CS 0 J I 100 "LCSFS'SP' Figure 14.— Tag recoveries per trap per time period by 20-inile intervals measured from the point of release in lower Chatham Strait, 1941. migration. Both types of data show two main migra- tion routes, one starting in Icy Strait and leading south through upper and middle Chatham Strait into Frederick Sound and the other leading from lower Chatham Strait into Frederick Sound. In Figures 16 to 20, the weekly catch per trap is plotted against time in weeks for the major statistical subareas for the years 1938-42. Lynn Canal is included with upper Chatham Strait. The vertical lines represent the dates, obtained by linear interpolation, at which the catches per trap were 10,000 and 20,000 fish per week. The time difference in days between the 10,000- and 20,000-fish-per-week levels in outer Icy Strait and four inner areas is given in Table 12. The catch per trap during the seventh week in inner Icy Strait in 1938 reached 19,806 but not 20,000 and, although omitted from Figure 16, the time difference was calculated and is given in Table 12. Table 13 lists time differences between lower Chatham Strait and two inner areas. In all years, the average catch increased first in out- er Icy Strait and then in inner Icy Strait, upper Chatham Strait, and middle Chatham Strait in that order, as would be expected if the fish were entering through Icy Strait and moving south. Since traps in 100 Ilcs' fs'sp' from trap site Figure 15. — Tag recoveries per trap per time period by 20-mile intervals measured from the point of release in lower Chatham Strait, 1942. 25 Table 11. --Total trap Alaska, 1938- catch and catch per trap 42 and 1945. (See Table In major statistical subareas in southeastern 2 for number of traps in each area.) 1935 Catch Catch/trap 1939 Catch Catch/trap~ 1J40 Catch Catch/trap Statistical subarea Outer Icy Strait Inner Icy Strait Lynn Canal Upper Chatham Strait Middle Chatham Strait Lower Chatham Strait Frederick Sound Stephens Passage Total Outer Icy Strait Inner Icy Strait Lynn Canal Upper Chatham Strait Middle Chatham Strait Lower Chatham Strait Frederick Sound Stephens Passage Total 584,181 72,023 604,388 31,810 86,230 43,115 2,188,491 115,184 1,627,369 81.368 608,327 101,388 1,239,817 82,654 483,807 40,317 258,991 32,374 249.440 13,128 51,105 25,553 844,979 44,473 817,293 43,015 531,542 106,308 1,464,014 97,601 917,698 76,745 379,451 54,207 860.957 45,314 53.947 26,974 2,503.038 125.152 1.318.151 73.231 515.610 171.870 1.066.645 66,665 710,431 64,585 7,422,610 73,491 5,135,062 51,869 7,408,230 77,169 1941 1942 Catch Catch/trap Catch Catch/trap 1945 Catch Catch/traF 1,209,224 201,537 1,934,492 193,449 102,915 102,915 4,701,101 361,623 2,866,237 238,853 2,622,128 655,532 5,139,320 321,208 2,794,745 254,068 425,860 70,977 1,121,161 65,951 136,218 68,109 2.616,757 145,375 940,765 58,798 824,650 206,163 1,962,959 122,685 1 ,088,965 98,997 176,234 29,372 395,678 24.730 44.806 22.403 827,868 48,698 647,114 38,066 413,057 103,264 681.857 48,704 421,055 32,389 21,370,162 292,742 9,117,335 101,304 3,607.669 40.536 I23 0.98 - \ \ \ \ < 1- O 1 \\ V \ \ A= 0-50 O 0.77 z I • \ \ ^ LL \ \ \^ A= 0.10 EXPONENTIAL o en ■ \ S \ \ \^^ A= 0.20 ^0.35 - \ < 0.30 ^\^ S \ /i= 0. 10 ^^^^^ 0. 11 , 1 —1 — u 1 1 0 1 2 3 4 5 6 7 LENGTH OF WEEKLY OPEN PERIOD (DAYS) Figure 24. — Exploitation isopleth for the total pink salmon run entering the northern part of southeastern Alaska, 1942. Tri- angular entry pattern and periodic fishery assumed; /u = rate of exploitation or fraction of run taken in catch. 1.19 12 3 4 5 6 7 LENGTH OF WEEKLY OPEN PERIOD (DAYS) Figure 23. — Exploitation isopleth for the total pink salmon run entering the northern part of southeastern Alaska, 1941. Tri- angular entry pattern and periodic fishery assumed; /j = rate of exploitation or fraction of run taken in catch. The computations of exploitation rates of about 50% are completely dependent on the assumption that incomplete reporting or immediate tag loss and mortality or both caused about half of the tagged fish to become "unavailable." If, however, the overall average F value of 0.514 computed directly from the 1938-42 and 1945 tagging data is correct, the average rate of exploitation for these years drops to 0.32. For the reasons mentioned earlier, the authors feel that the higher rate of exploitation is more nearly the cor- rect value. Of course, the rate of exploitation on any particular stock may have been quite different than the overall average. In the exploitation isopleth com- putations, the fractions removed by fishing from stocks in the first part of the entry triangle were con- siderably higher than from stocks in the second part. Approximately 7% of the fish in the entry patterns used to calculate Figures 21-24 entered after the season had been closed and for that reason suffered no fishing mortality. RECOMMENDATIONS FOR THE DESIGN OF FUTURE TAGGING EXPERIMENTS Tagging experiments are a basic method of generating knowledge needed to determine optimum policies for managing the pink salmon resource of southeastern Alaska. A primary objective of manage- ment is to regulate the commercial fishery to allow the quantity and quality of escapement that will max- 36 imize either biological or economic productivity of the resource. It is obvious that any tagging experiment should be designed to answer specific questions which are clear- ly stated at the time the experiment is being designed. The suggestions offered here are general and applicable to most tagging experiments regardless of whether their primary objective is to determine migratory routes, rates of travel, rates of exploitation on various stock units, rates of escapement into par- ticular watersheds, racial compositions of populations in various fishing areas at different times, numerical abundance of particular stock components, or any combination of these. Establishment of an efficient data collection system is essential. Accurate and complete records of tag releases, recoveries, commercial effort (in terms of standardized units and catches by time-area strata of appropriate size), and timing and abundance of es- capements into various watersheds are needed. Release information should include hydrological and meteorological data. Fish should be released in groups, and conditions prevailing at the time of release should be recorded. Exact locations and recapture times for a purse seine fishery can probably be obtained only through a logbook system. Logbooks also should be used to collect data on the number and location of the sets made each day by an individual boat. To determine the amount of incomplete recovery and reporting of recaptured tags, trained fishery biologists should sample the catch independently in a manner that does not interfere with normal recovery procedures used by fishermen. Sampling designs for estimating the extent of incomplete reporting are given by Paulik (1961). In some circumstances it is advisable to include double tagging experiments to determine tag loss (GuUand 1963). Data collection and record-keeping methods should be standardized, and data forms that allow im- mediate transfer of field data to punch cards should be used. With proper mechanization and data-han- dling procedures, it is feasible to carry out an analysis of partial data from an experiment while the experi- ment is still in progress. Feedback from this type of simultaneous analysis permits an evaluation of ex- perimental techniques that would not otherwise be possible until it was too late to correct faulty procedures. A special effort should be made to collect recovery information on a daily basis in the immediate vicinity of release sites. These data can be used to develop cor- rection factors to adjust mortality rate estimates for the bias caused by nonavailability of tagged fish shortly after their release (see discussion of type C error in Ricker 1958, p. 122-126). The method of capturing fish for tagging and the types of tags applied should not interfere with the ob- jectives of the experiment. Installation of salmon traps at key locations along primary migration routes should be considered for major tagging experiments. These traps would be used for the sole purpose of cap- turing fish for tagging and would assure a fixed point of release and permit closer control of tagging tech- niques than would be possible with purse seines. Traps should also provide holding facilities so that fish could be released in batches of some minimum critical size. Migratory delays should be held to a minimum to reduce the possibility of abnormal behavior. If tagging is carried out from both seines and traps, simultaneous releases should be made to allow a comparison between the two methods of tag- ging. The numbers of tags released at any one time should be as large as feasible, e.g., at least 500 fish, or if a breakdown of recoveries into fine time-area strata is desired, 1,000 fish. The use of re-releases of recap- tured tagged fish and also the possibility of tagging a selected subsample of fish with battery-powered transmitting tags should be investigated for studies of migratory behavior. The spatial and temporal distribution of the releases should cover the entire geographical region- time space occupied by the populations being studied. Extrapolation of tagging results to populations found at times and in places not included as part of the tag- ging experiment is generally not advisable. In some cases it may be necessary to make preseason releases, closed-period releases, and postseason releases. Preseason and closed-period releases provide data for separating the fishing mortality rate from the escape- ment rate and for testing various hypotheses about temporal changes in the escapement rate. The possibility of using simultaneous translocation ex- periments to study migratory patterns should be in- vestigated. It is advisable, if funds are limited, to make fewer releases and to allow sufficient funds for an adequate recovery program. Depending somewhat on the objec- tives of the experiments, it is usually desirable to con- duct spawning ground surveys in major watersheds and to enumerate spawning populations wherever possible. Even if great effort is expended on tagging, the results of a tagging experiment will be in- conclusive if the recovery effort is inadequate. When possible, new experiments should maintain continuity with earlier experiments. Experimental methods should be standardized and changes thereafter should be made only with proper duplica- tion using old and new techniques at the same time and place to obtain correction factors that will allow assimilation of the new findings with knowledge gained from past experiments. It has now become technically feasible to integrate a great deal of information concerning the dynamic behavior of a complex system such as the pink salmon fishery in southeastern Alaska into a large-scale com- puter simulation program. Agencies concerned with 37 managing the salmon resources in southeastern Alaska should investigate the practical feasibility of establishing and maintaining an open-ended com- puter simulation model of this resource for use as a basic planning tool. Alternative policies could be evaluated on this type of simulation model to deter- mine which ones are most promising. Such a simula- tion model would be an invaluable aid in designing future tagging experiments. This type of model could be used to optimize the distribution of tagging and recovery effort and would aid in development of techniques for analyzing and interpreting tagging data. A more detailed discussion of the uses of simula- tion models for planning resource management strategies is given by Paulik (1967). SUMMARY Records of pink salmon tagging experiments conducted by the U.S. Fish and Wildlife Service in the northern part of southeastern Alaska each year from 1938 through 1942 and in 1945 were transferred to punch cards and analyzed using electronic data processing equipment. During these 6 yr 55 releases were made: 20,472 fish were tagged and 7,027 of the tags were recovered. No spawning ground surveys were made, and only 30 tagged fish were recovered in streams. Total recoveries from all sources other than streams varied from a low of 28.6% in 1940 to a high of 38.7% in 1941; 79.8% of the recoveries were from traps and 16.1% from seines. The analysis of tag recoveries is supplemented by an analysis of the recorded daily catches of pink salmon from about 100 traps that operated in the northern part of southeastern Alaska during these years. In most years (with the exception of 1941 and to a lesser extent 1942) releases of tagged fish were restricted to a few localities and were not well dis- tributed in time. No multiple recaptures were reported. Little information could be found on the size and distribution of the seine fleet, and the recorded data accompanying tag recoveries by seines were in- complete. The analysis is restricted for the most part to trap catches and trap recoveries. Recoveries in the southern part of southeastern Alaska, i.e., to the south of Kuiu, Kupreanof, and Mitkof islands, were infrequent from these releases, which were made in the northern part. The lack of movement to the south confirms findings of earlier in- vestigators that exchange of pink salmon between the northern and southern parts of southeastern Alaska is of no practical significance and that the pink salmon runs in these areas should be regarded as distinct from one another and managed as two independent units. None of the tagged fish released in middle Chatham Strait were recovered in Salisbury Sound on the west coast of Baranof Island, which indicates that there was no westward movement through Peril Strait. Limited tagging in Salisbury Sound in 1945 suggests that Peril Strait is not an important entryway into in- ner waters, but the experiments were too few to es- tablish the magnitude of the eastward movement through Peril Strait. The geographical distribution of recoveries showed that one main migration route is through Icy Strait and upper Chatham Strait to middle Chatham Strait; from there the pink salmon disperse eastward into Frederick Sound and Stephens Passage. The other major passageway from the ocean is through lower Chatham Strait into Frederick Sound and Stephens Passage. While some segment of each tagged group moved rapidly along one of the main migratory paths, others lagged behind, with the result that tagged fish were distributed along the entire way traversed and recoveries continued to be made from all points along the route until the end of the season. Some fish re- leased in Icy Strait moved through upper and middle Chatham Strait in 1 to 2 days and were found in Frederick Sound within 3 to 5 days. The data show there was not a major exchange of fish between lower Chatham Strait and middle Chatham Strait. The stocks found in Icy Strait, upper Chatham Strait, and middle Chatham Strait are to a large extent distinct from those found in lower Chatham Strait. Fish tagged later in the season exhibited a more restricted range of movements about the point of release than those tagged earlier. Groups tagged earlier in the season contained larger proportions of fish destined for spawning grounds distant from the release points. The movement pattern of a group of tagged pink salmon appears to be made up of a random compo- nent superimposed upon a directional component. The relative strengths of these two components vary considerably from year to year. Also the particular mixture of racial stocks in a given sector of the fishing ground at any time during the season varies greatly from year to year. Analysis of data on catch per trap per week con- firmed the major migratory routes as determined from the analysis of the tagging data. Catches increased in an orderly fashion for traps along the northern entry route. The buildup of catches in Frederick Sound and Stephens Passage was earlier than in middle Chatham Strait but never preceded the increase in lower Chatham Strait. The timing of catch increases in lower Chatham Strait was similar to that in inner Icy Strait. The populations in Frederick Sound and Stephens Passage were composed of a mixture of fish that had entered through both the northern and the southern entry ways. The rate of movement of the center of density of a single release of tagged fish was estimated from locations of median tag recaptures on successive days; the rate of movement of the leading edge was es- timated from the second farthest recovery each day. 38 The leading edge moved at rates of 9.1 to 33.4 miles per day and averaged about 18 miles per day, and the center of density moved at rates of 1.0 to 15.4 miles per day and averaged about 8 miles per day. In 1942 both of these measures of rate of travel for tagged fish were considerably lower than in 1941. Weekly rates of survival and exploitation were calculated for 30 experiments which had sufficient numbers of recoveries adequately distributed in time. For these experiments the average weekly survival rate is 39.4^r and the average weekly exploitation rate is 25.0%. A comparison of the exponential fishing rate of 0.514 with the exponential other-loss rate of 0.595 indicates that the rate of removal of tagged fish by the fishery was slightly less than the rate of removal from all other causes combined. The estimates of exponen- tial fishing rates were considerably lower than es- timates obtained from tagging experiments in Icy Strait in 1950. Part of the discrepancy between the es- timated fishing rates in 1950 and in the earlier years appears to be the result of incomplete detection and reporting of recaptured tags in the earlier ex- periments. A computer program that calculates the total rate of exploitation on a run of salmon when recuitment, outmigration, and fishing occur simultaneously was used to estimate the fraction of the total run removed by the fishery in 1938, 1939, 1941, and 1942. The tim- ing of the entry of pink salmon into the fishing ground was determined from an analysis of the catch data. The average rate of exploitation on the total run dur- ing the years included in this analysis is between 32% and 51%. The exact figure cannot be estimated without further knowledge of the extent of incomplete reporting and tag loss. A series of recommendations for designing future tagging experiments is presented. It is suggested that the planning and design of tagging experiments could be improved significantly by first simulating the ex- periments on an open-ended digital computer simula- tion model of the pink salmon fishery in southeastern Alaska. ACKNOWLEDGMENTS It is a pleasure to acknowledge three persons who contributed substantially to the preparation of this manuscript. Sandra Anderson edited an early draft of the report and carried out many of the numerical calculations; much of the section on migration rates is based on her ideas. Jerry Jaffee and Lawrence Gales wrote the computer programs used to process the tagging data. LITERATURE CITED DAVIDSON, F. A., and L. S. CHRISTEY. 1938. The migrations of pink salmon (Oncorhynchus gor- buscha) in the Clarence and Sumner Straits regions of South- eastern Alaska. U.S. Bur. Fish., Bull. 48:643-666. ELLING, C. H., and P. T. MACY. 1955. Pink salmon tagging experiments in Icy Strait and Upper Chatham Strait, 1950. U.S. Fish Wildl. Serv., Fish. Bull. 56:331-371. FISHER, R. A. 1950. Statistical methods for research workers. 11th ed., rev. Oliver and Boyd, Edinb., 354 p. GULLAND, J. A. 1963. On the analysis of double-tagging experiments. Int. Comm. Northwest Atl. Fish., Spec. Publ. 4:228-229. PAULIK, G. J. 1961. Detection of incomplete reporting of tags. J. Fish. R«s. Board Can. 18:817-832. 1962. Use of the Chapman-Robson survival estimate for single- and multi-release tagging experiments. Trans. Am. Fish. Soc. 91:95-98. 1963. Exponential rates of decline and type (1) losses for populations of tagged pink salmon. Int. Comm. Northwest Atl. Fish,, Spec. Publ. 4:230-237. 1967. Digital simulation of natural animal communities. In T. A. Olson and F. J. Burgess (editors). Pollution and marine ecology, p. 67-85. Intersci. Publ., N.Y. PAULIK, G. J., and J. W. GREENOUGH, JR. 1966. Management analysis for a salmon resource system. In K. E. F. Watt (editor). Systems analysis in ecology, p. 215- 252. Acad. Press, N.Y. RICH, W. H. 1927. Salmon-tagging experiments in Alaska, 1924 and 1925. U.S. Bur. Fish., Bull. 42:109-146. RICH, W. H., and F. G. MORTON. 1930. Salmon-tagging experiments in Alaska, 1927 and 1928. U.S. Bur. Fish., Bull. 45:1-23. RICH, W. H., and A. J. SUOMELA. 1929. Salmon-tagging experiments in Alaska, 1926. U.S. Bur. Fish., Bull. 43(Part 2):71-104. RICHER, W. E. 1958. Handbook of computations for biological statistics of fish populations. Fish. Res. Board Can., Bull. 119, 300 p. SIMPSON, R. R. 1960. Alaska commercial salmon catch statistics 1951 - 1959. U.S. Fish Wildl. Serv., Stat. Dig. 50, 115 p. WELCH, B. L. 1938. The significance of the difference between two means when the population variances are unequal. Biometrika 29:350-362. 39 ft U. 5 GOVERNMENT PRINTING OFFICE: 1975-698- 199/26 REGION 10 G4S. Weifjht loss of pond-raiHed channel catfish {Ictolurus punctatus) during holding in processini; plant vats. By Donald C. Greenland and Robert L. Gilt. December 1971. iii + 7 pp., 3 figs., 2 tables. For sale by the Superintendent of Documents. U.S. Government Printing Office. Washington, D.C. 20402. 649. Distribution of forage of skipjack tuna iEuthynnus pelamis) in the eastern trt>pical Pacific. By Maurice Blackburn and Michael Laurs. January 1972. iii + 16 pp., 7 figs., 3 tables. For sale bv the Superintendent of Documents. U.S. Government Printing Office. Washington, D.C. 20402. 650. Effects of some antioxidants and EDTA on the development of rancidity in Spanish mackerel iScomberomorus maculatus) during frozen storage. By Robert N. Farragut. February 1972, iv + 12 pp.. 6 figs., 12 tables. For sale by the Superintendent of Documents. U.S. Government Printing OITice, Washington, D.C. 20402 651. The effect of premortem stress, holding temperatures, and freezmg on the biochemistry and quality of skipjack tuna. By Ladell Crawford. April 1972, iii + 23 pp.. 3 figs., 4 tables. For sale by the Superintendent of Documents. U.S. Government Printing Office. Washington. D.C. 20402. 653. The use of electricity in conjunction with a 12.5-meter (Headrope) Gulf-of. Mexico shrimp trawl in Lake Michipan. By .James E, Ellis. March 1972. iv + 10 pp.. 11 figs.. 4 tables. For sale by the Supenntendent of Documents. U.S. Government Printing Office, Washington. DC. 20402. 654. An electric detector system for recovering internally tagged menhaden, genus Breuoortia By R. O Parker. .Ir. February 1972. iii + 7 pp., .i figs.. 1 appendix table. For sale by the Superintendent of Documents. U.S. Government Printing Office. Washington. DC. 20402. 6,55, Immobilization of fingerling salmon and trout by decompression. By Doyle F. Sutherland. March 1972. iii + 7 pp.. 3 figs.. 2 tables. For sale by the Superintendent of Documents, U.S. Government Printing Office. Washington, D.C. 20402. 662. Seasonal distribution of tunas and billfisliet* in the Atlantic. By John P Wise and Charles W Davis January 1973, iv + 24 pp.. 13 figs . 4 tables For sale by the Superinten- dent of Documents, U.S. Government Printing Office, Washington, D.C. 20402. 663. Fish larvae collected from the northeastern Pacific Ocean and Puget Sound during April and May 1%7 By Kenneth D. Waldron. December 1972. iii ■^ 16 pp.. 2 figs., 1 table, 4 appendix tables For sale by the Superintendent of DocumenU. U.S. Government Print- ing Office. Washington. DC 20402 664. Tagging and tag-recovery experimenU with Atlantic menhaden, Brtvoortia tyran- nus. By Richard L. Kroger and Flobert L. Dryfoos. December 1972. \v + 11 pp., 4 figs., 12 tables For sale by the Superintendent of Documents. US. Government Printing Office Washington, DC. 20402 665. Larval fish survey of Humbolt Bay, California. By Maxwell B. Eldridge and Charles F. Bryan. December 1972, iii + 8 pp.. 8 figs., 1 table. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC. 20402. 666. Distribution and relative abundance of fishes in Newport River, North Carolina. By William R. Turner and George N. Johnson. September 1973, iv + 23 pp.. 1 fig.. 13 tables. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402. 667. An analysis of the commercial lobster {Homarm americanus) fishery along the coast of Maine, August 1966 through December 1970. By James C. Thomas. June 1973, v -f 57 pp , 18 figs., 11 tables. For sale by the Superintendent of Documents. U.S. Government Printing Office. Washington, DC. 20402. 668. An annotated bibliography of the cunner, Tautogolabrus adspersus ( Walbaum). By Fredric M. Serchuk and David W Frame. May 1973. ii + 43 pp. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC. 20402. 6,56. The calico scallop, ^r^opecf en ^t66ti5. By Donald M. Allen and T. J. Costelio. May 1972, iii + 19 pp., 9 figs.. 1 table. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington. D.C. 20402. 657. Making fish protein concentrates by enzymatic hydrolysis. A status report on research and some processes and products studied by NMFS. By Malcolm B. Hale. November 1972. v -f 32 pp.. 15 figs.. 17 tables. 1 appendix table. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington. D.C. 20402. 658. List of fishes of Alaska and adjacent waters with a guide to some of their literature. By Jay C. Quasi and Elizabeth L. Hall. 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July 1972. xl + 95 pp.. 2 figs. For sale by the Superintendent of Documents. U.S. Government Printing Office. Washington. DC. ■20402. 660. A freshwater fish electro-motivator (FFEM)-its characteristics and operation. By James E. Ellis and Charles C. Hoopes. November 1972. iii + U pp.. 9 figs. 661. A review of the literature on the development of skipjack tuna fisheries in the cen- tral and western Pacific Ocean. By Frank J Hester and Tamio Otsu. January 1973. iii + 13 pp.. 1 fig. For sale by the Superintendent of Documents. U.S. Government Printing Of- fice. Washington. D.C. 20402. 672. Seasonal occurrence of young Gulf menhaden and other fishes in a northwestern Florida estuary By Marlin E. Tagatz and E. Peter H. Wilkins. August 1973. iii ■¥ 14 pp., 1 fig.. 4 tables. For sale by the Superintendent of DocumenU, U.S. Government Printing Of- fice, Washington, DC. 20402. 673. Abundance and distribution of inshore benthic fauna off southwestern Long Island, NY. By Frank W. Steimle. 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