ed ZU Poteet hat wy Ss BALA ee ont : oom ah if We nea had Sneapeaeh Leis eats Pata s ao etre wees eres ae, Ln aten oe me etap se iet eee, Feo ae aber et tenet ees ee hater ak vat ate 2S Statens yeas we peor Seo Berra ace sored Sys 3 nao * 4 4 este tira Moe TES tae ot 3 "eV Pies Saas Se ee iss soa bsehet Ss SS pig g=yre— re teeeTe =e SSS aa 7 ul} ; ny | y ie . i NOAA Technical Report NMFS SSRF-675 Proceedings of the - International Billfish Symposium Kailua-Kona, Hawaii, 9-12 August 1972 Part 1. Report of the Symposium RICHARD S. SHOMURA and FRANCIS WILLIAMS (Editors), SEATTLE, WA “March 1975 noa@a 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 fishery 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 service 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. 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. 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 alalunga, 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 quality and yield of bay scallop meats. By N. B. Webb and F. B. Thomas. April 1971, iii + 11 pp., 9 figs., 3 tables. 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 Lower St. Paul River, Liberia, 1952-53. By George C. Miller. February 1971, iii + 13 pp., 8 figs., 7 tables. 627. Calico scallops of the Southeastern United States, 1959-69. By Robert Cummins, Jr. June 1971, iii + 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. 630. Blue crab meat. I. Preservation by freezing. July 1971, iii + 13 pp., 5 figs., 2 tables. Il. 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 by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402. 633. Blueing of processed crab meat. II. Identification of some factors involved in the blue discoloration of canned crab meat Callinectes sapidus. By Melvin E. Waters. May 1971, iii + 7 pp., 1 fig., 3 tables. 634. Age composition, weight, length, and sex of herring, Clupea pallasti, used for reduc- tion in Alaska, 1929-66. By Gerald M. Reid. July 1971, iii + 25 pp., 4 figs., 18 tables. Continued on inside back cover. 635. A bibliography of the blackfin tuna, Thunnus atlanticus (Lesson). By Grant Beardsley and David C. Simmons. August 1971, 10 pp. For sale by the Superintenden’ Documents, U.S. Government Printing Office, Washington, D.C. 20402. 636. Oil pollution on Wake Island from the tanker R. C. Stoner. By Reginald Gooding. May 1971, iii + 12 pp., 8 figs., 2 tables. For sale by the Superintenden) Documents, U.S. Government Printing Office, Washington, D.C. 20402. 637. Occurrence of larval, juvenile, and mature crabs in the vicinity of Beaufort In North Carolina. By Donnie L. Dudley and Mayo H. Judy. August 1971, iii + 10 pp., 11! 5 tables. For sale by the Superintendent of Documents, U.S. Government Printing Off Washington, D.C. 20402. 638. Length-weight relations of haddock from commercial landings in New Engla\ 1931-55. By Bradford E. Brown and Richard C. Hennemuth, August 1971, v + 13 pp. figs., 6 tables, 10 appendix A tables. For sale by the Superintendent of Documents, U Government Printing Office, Washington, D.C. 20402. 639. A hydrographic survey of the Galveston Bay system, Texas 1963-66. By E. J. Pull) W. L. Trent, and G. B. Adams. October 1971, v + 13 pp., 15 figs., 12 tables. For sale by Superintendent of Documents, U.S. Government Printing Office, Washington, D 20402. 640. Annotated bibliography on the fishing industry and biclogy of the blue cr Callinectes sapidus. By Marlin E. Tagatz and Ann Bowman Hall. August 1971, 94 pp. _ sale by the Superintendent of Documents, U.S. Government Printing Office, Washingt D.C. 20402. 641. Use of threadfin shad, Dorosoma petenense, as live bait during experimental pc and-line fishing for skipjack tuna, Katsuwonus pelamis, in Hawaii. By Robert T. Iversen. August 1971, iii + 10 pp., 3 figs., 7 tables. For sale by the Superintendent! Documents, U.S. Government Printing Office, Washington, D.C. 20402. 642. Atlantic menhaden Brevoortia tyrannus resource and fishery—analysis of decli By Kenneth A. Henry. August 1971, v + 32 pp., 40 figs., 5 appendix figs., 3 tables: appendix tables. For sale by the Superintendent of Documents, U.S. Government Printi Office, Washington, D.C. 20402. 643. Surface winds of the southeastern tropical Atlantic Ocean. By John M. Steigner ai Merton C. Ingham. October 1971, iii + 20 pp., 17 figs. For sale by the Superintendent! Documents, U.S. Government Printing Office, Washington, D.C. 20402. 644. Inhibition of flesh browning and skin color fading in frozen fillets of yello: snapper (Lutzanus vivanus). By Harold C. Thompson, Jr., and Mary H. Thompse February 1972, iii + 6 pp., 3 tables. For sale by the Superintendent of Documents, U. Government Printing Office, Washington, D.C. 20402. 645, Traveling screen for removal of debris from rivers. By Daniel W. Bates, Ernest \ Murphey, and Martin G. Beam. October 1971, iii + 6 pp., 6 figs., 1 table. For sale by t! Superintendent of Documents, U.S. Government Printing Office, Washington, D.' 20402. 646. Dissolved nitrogen concentrations in the Columbia and Snake Rivers in 1970 their effect on chinook salmon and steelhead trout. By Wesley J. Ebel. August 1971, iir + pp., 2 figs., 6 tables. For sale by the Superintendent of Documents, U.S. Governmer Printing Office, Washington, D.C. 20402. 647. Revised annotated list of parasites from sea mammals caught off the west coast « North America. By L. Margolis and M. D. Dailey. March 1972, iii + 23 pp. For sale by Superintendent of Documents, U.S. Government Printing Office, Washington, D.' 20402. NOAA Technical Report NMFS SSRF-675 Proceedings of the International Billfish Symposium Kailua-Kona, Hawaii, 9-12 August 1972 Part 1. Report of the Symposium RICHARD S. SHOMURA and FRANCIS WILLIAMS (Editors) SEATTLE. WA March 1975 UNITED STATES NATIONAL OCEANIC AND National Marine DEPARTMENT OF COMMERCE ve ATMOSPHERIC ADMINISTRATION Fisheries Service Frederick B. Dent, Secretary Robert M. White, Administrator Robert W. Schoning, Director For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 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 NMI'S, 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 22 BGI R UOT se Ue Ee Bowe Re Co aa IG PUG EES ny eA rk let nea ene ern ea oN caeric oy grams eeu Oy iuce emery rar 1 Semneimal] IRSYOLOT Ey IES ee geen ie tea arate in ce OSG Mite dance at ae eee eS Tre VE a Meee Gye On eee egy eae 1 Fan ROU CELOM rare are ie ee gee et cr Te mane: cep icin Sl eter ae avin’ nin eeSca ct oceans accteiny el oberon ye < arevanree 1 EXICKOT OUT G Meeeeersy gee et prec pee este Soe AUS care ee teem cay aN ene tate sae omer MR eT pea Uae aa caceae 1 WMenminsESeSSi OMe oN ret ER rete oy einite Unt asc eiray Mulls |e sey eu ana ieausPauucny (2, Became Aske iL Oiticerspandsorcanizationyol-wOrk ware eek chose aay ise re eet cl een ce cere eee deag ale 4 Oni cerstofashesoym POSIUM! Le eee ee eee, Oe eee lcs eee ci ehee eee cee ete a oa. 4 OnganizabionkonewOrke: soc es ieee see es Sy ee ces ee, oe oe NE ree Oe ene oes 4 ‘Sopitionmealll. Ixy over RS eae eich hae ee ecr cia ee . mueomia capa tb abt giees tig oae cama eh Meleaticne Hlecudis Ncmidenauierc nts 4 Speciessidentitication casino a eae Sen ue te iee Oe Pie ale ten keane rat ean ose 4 [Lit JONSIGINY = <4 Se oe sae ica os Gon les on «pee a eeeeenemeeny cue Reem ee emu ereeriat cence ims vomits a eee ta a? 4 [Distal oxntavorsy, W]e oui Beams Mellae cae imran Gt Ua eterna aire ars Sena hiner imke Pirie Wenner other tar. eoulocyinehotians i 5 IPRGINGRIGS: “SSR eBGH Ben Saree Sle Dante te Tee etna Be ai niin acne aa nesell einai ine weycr aierik tp cdi ans Meena ea 5 SpecialusessronsMercury sin. billfishes) Bae). Noah ye ee ee arg ra ects 6 Rresentationsamrmercte seis) cots stay Taste eee e ciecec ey te eee tad em tiaiee, “cumerd cen cPrane In menteny ase F7ay ret 6 DISCUSSION MBM ee ee ee eet ec eae ne ire hierihaisie Leta Fe oer ences Ohi re lene oe ives apo Ari EN eran a Specialesession-=Sportsmen-sclentists: (4° 4 a0 ue nie ies, Soe idnpoar el a ncn eg trata a 8 SVAN DOSTUTINES UNTNTIV IY oy hoe no op ca ae Tee eee eet UTE lie Se Ne Gite ere eis ec tr emen 8 parle lgpresentaclonw res cls ce wee ea Werte we 2 alae Na eyrmurclns anSps mene ang elegy eileen aun tray nt ra eat 9 DISCUSSION ERS cece ee ee meters tty ROEM IS Fy or ren ne Mr ENT, coEeRG 5 ct) Vc HDR ON cid tee oan ation h(E Dorie 15 PPC KENO WHE OMMEMI teeter hme ne ss oe, ce gece crac Leek cla a oat (eee oma nna UEE Er hye ge atigmectt ema CES ok BCU, Monte 18 Annexes Wn SOlsMATLICIPANES tate eis yaa ae eter rete eo ye Auge MU pray Maui ls Ney sn pei mete an 19 ZeeWwelcoming address by the Honorable Shunichi Kimura 3)... 09.0... - 46. 5. ws ae 23 pee Openmreaddress by sehilips Mi. Roedeles = ace asan ce heh san es cia gant ees ee 24 Am Nc dressnbyeMichiowhakatar © 0 iu ho eueulet yh Seu fe deisriie veep ices tese mace | tele cede eer 26 DeENGdTesSaDVedmeichomas Stuantele sey as dca Sirs Ut eee cent oar yn yenvln Gat Meany Te aren 26 Dame ANd dresseby es bebershithian! 2 Serer secjen ra situ cu ey eet une irene Mette ces Meee: 27 fpelextgoltecablestromyl aH POpper. 202! see ncn he eteeiiaee MME hoe oe Vee et Seam, ilk 8. Potential health hazards of mercury in fish by Albert C. Kolbye ............... 28 9. Status of mercury studies in Hawaii by Richard A. Marland ................. 30 10. Definitions and methods of measuring and counting in the billfishes (Istiophoridae, Xiphiidae) DVB UISSREN es RIVaSen eth cae on eee aoe cl lr een Mites | Pee Oke fae vce oe Seve ee vemL 31 ill DEDICATIONS John K. Howard 1891-1965 _ John K. Howard was an outstanding example of a man whose interest in ocean science led to a second career after retirement from law practice. His many friends throughout the world remember his great enthusiasm, combining a passion for sport fishing with a desire to increase our knowledge of the big- game fishes, in particular the billfishes. He sponsored _and directed a research program at the Institute of Marine Science, University of Miami, and also gave much logistic aid to ichthyologists around the world. His travels took him to East Africa, Australia, New Zealand, and Japan. He also visited Portugal, Spain, and Italy, where he collected large numbers of spear- fish and white marlin in an attempt to solve the specific identity of the Mediterranean spearfish. Shortly before his death he completed, with Dr. Shoji Ueyanagi of Japan, a large report on the seasonal and geographic distribution of billfishes in the Pacific Ocean. His similar work on these fishes in the Indian Ocean was completed by Dr. Walter A. Starck II. John K. Howard was born in Paris, France, on 4 April 1891. He received his undergraduate degree from Harvard College in 1915 and his law degree from Harvard College in 1917. After retiring from law prac- tice he studied ichthyology at the University of Miami. He served in both World Wars as an army of- ficer, achieving the rank of colonel. Oscar Elton Sette 1900-1972 Dr. Sette’s contributions to fisheries science are manifold and cover more than half a century of active work as a fishery biologist and administrator. From 1949 to 1955 he acted as chief of the newly es- tablished Pacific Oceanic Fishery Investigations (POFI), a Honolulu-based research facility of the Fish and Wildlife Service, U.S. Department of the Interior (presently the Honolulu Laboratory of the Southwest Fisheries Center, National Marine Fisheries Service, NOAA, U.S. Department of Commerce). Here he was responsible for the development of a_ high-seas fisheries program in the central Pacific Ocean, a program that laid the groundwork for much of what is known today of the tunas, sharks, and billfishes of this expansive body of water. Although much of the research effort of his staff at POFI was devoted to tunas as the principal pelagic species of commercial interest, Dr. Sette was among the first to recognize the need to study the full spectrum of the food web in order to understand the various biological resources of the ocean. The research on billfishes undertaken dur- ing and after his tenure in Honolulu is a result of his appreciation of the need to collect data from all levels of the ecosystem. Dr. Sette was also one of the first to advocate integrating the field of biology with those of oceanography and meteorology. Oscar Elton Sette was born in Clyman, Wis., on 29 March 1900. In 1910 his family moved to southern California, where he completed his intermediate and high school education. He received his Bachelor of Arts degree from Stanford University in 1922, a Master’s degree in Biology from Harvard University in 1930, and a Doctorate in Biology from Stanford University in 1957. During a career which extended over 50 years, Dr. Sette served in various research and administrative capacities with the California State Fisheries Laboratory, and the National Marine Fisheries Ser- vice and its predecessor agencies. Beginning in 1924 with the U.S. Bureau of Fisheries, he held positions as Chief, Division of Fishery Industries in Washington, D.C.; Chief of the North Atlantic Fishery Investigations; Chief of the South Pacific Fishery Investigations; Chief, Pacific Oceanic Fishery Investigations; and Director, Ocean Research Laboratory, on the campus of Stanford University. De. Sette “retired” in 1970, but continued his research as an “‘annuitant’’ employee of the Federal Government until his death in July 1972. GENERAL REPORT Introduction The Symposium was sponsored by the National Marine Fisheries Service (NMFS) of the National Oceanic and Atmospheric Administration, U.S. Department of Commerce, and was held at Kailua- Kona, Hawaii, from 9 to 12 August 1972. The Sym- posium was cosponsored by the County of Hawaii, the Hawaii State Division of Fish and Game, the Marine Affairs Coordinator of the State of Hawaii, and the Hawaiian International Billfish Tournament (HIBT). The Food and Agriculture Organization of the United Nations (FAO) also actively supported the Sym- posium. Background Since the mid-1960’s the pelagic waters of the world’s oceans extending from about lat. 40°N to 40°S have been fished with longline gear for fish species of commercial importance. The principal species sought have been the tunas; thus, these pelagic fishes have received considerable attention from biologists and fishery administrators. Tunas have been the subject of discussions at the Scientific Meeting on the Biology of Tunas and Related Species held in La Jolla, Calif., 2-14 July 1962; the Symposium on Scombroid Fishes held in Mandapam Camp, India, 12-15 January 1962; and the Governor’s Conference on Central Pacific Fishery Resources held in Hawaii, 28 February-12 March 1966. Further, those tuna species of commer- cial importance have been the focus of attention in re- cent years and have been the subject of review at an- nual international meetings, e.g., Inter-American Tropical Tuna Commission (IATTC) and _ Inter- national Commission for the Conservation of Atlantic Tunas (ICCAT), and domestic meetings, e.g., Pacific Tuna Conferences. Unlike the tunas, the other major group of pelagic fishes taken by longline gear—the billfishes—has received very little attention. The relatively large size attained and the difficulty in obtaining adequate numbers of specimens for examination have kept our knowledge of billfishes to a low level. Studies under- taken by individual scientists have been based on few specimens, specimens principally collected at the centers of sport fisheries. Access to data and specimens collected by the extensive longline fisheries has been limited primarily because the accom- modations aboard commercial longline vessels are limited and fishing trips generally extend over periods of several months. The principal reason for this restricted information, however, has been the lack of urgency and priority expressed by administrators of the major fishing countries. During the past 5 or 6 yr the need to assess the status of stocks of the various species of the billfishes has become apparent. This has been reflected in the concern expressed by sport fishermen throughout the world regarding the declining catches of billfishes and the increased importance of billfishes noted by the commercial interests. The sport fishery catch rates of sailfish in the Pacific waters off Mexico have declined dramatically in the last decade. This decline has been attributed to the intensive longline fishery which started in 1963. In 1970, NMFS held a workshop at the Tiburon Fisheries Laboratory to: 1) review briefly the available background knowledge of billfish biology, 2) evaluate data relating to the assessment of billfish resources, and 3) explore the types of cooperative research need- ed in order to accomplish objectives outlined in 1) and 2) In order to highlight their importance, a special ses- sion on billfishes was held at the 22d Tuna Conference (October 1971) at Lake Arrowhead, Calif. At the con- ference a series of papers presented on billfishes again reiterated the need for a major symposium to bring together all known information on the subject. On the basis of these preliminary meetings, NMFS decided to sponsor an international billfish sym- posium. This was to be the first major symposium organized by the newly created NMFS. In selecting a location for the symposium, the organization com- mittee decided to hold it in conjunction with the HIBT, which is held annually at Kailua-Kona, Hawaii. This joint arrangement had the advantages of 1) having available at the symposium sport fishermen from a number of countries, and 2) permitting billfish specimens to be made available to scientists for — research purposes. Opening Session Mr. Richard S. Shomura, Cochairman of the Symposium, called the meeting to order and in- troduced the Honorable Shunichi Kimura, Mayor of the County of Hawaii. Mayor Kimura in his address’ welcomed the Symposium participants to the Island of Hawaii. He stressed that in developing the islands’ resources there is a need for a well balanced mix of in- digenous basic industries and scientific research in complementary disciplines. Mayor Kimura men- tioned how appropriate in this respect were some of the research projects located on Hawaii, such as those in tropical agriculture, astronomy, geothermal energy, voleanology, and atmospheric sciences. He was delighted that fisheries expertise, in the form of the Symposium and its participants, had come to Kailua- Kona where sport fishing, especially the annual HIBT, is such a valuable part of the recreational and tourist activities. Mr. Shomura then introduced Mr. Philip M. Roedel, Director, NMFS. Mr. Roedel, in his opening ‘See Annex 2. address’, brought greetings from Dr. Robert M. White, Administrator of the National Oceanic and Atmospheric Administration. This was the first scien- tific symposium organized by NMFS since its forma- tion in October 1970. The two primary reasons for holding the Symposium were 1) scientific studies of billfishes on a global scale were very limited, and 2) it would provide a forum for interactions between sport fishermen and scientists with regard to a high-seas fishery. Mr. Roedel noted that notwithstanding the long recognized importance of billfishes in worldwide sports and commercial fisheries, we have very little idea of the size of the resource. Published data on the various species are sparse and scattered, and much in Japanese, and thus the Symposium Proceedings would provide the basic background information es- sential for further detailed studies of the billfishes. Though there are considerable biological, socio- economic, and politico-legal problems to be solved with regard to billfishes, they are included in only one international group concerned with management, i.e., the ICCAT. Mr. Roedel referred to the occurrence of heavy metals in billfishes and the intense public in- terest in this aspect, which had prompted the special symposium evening session on the subject. In conclu- sion, he noted the success of the various cooperative programs between sport fishermen and scientists, es- pecially in tagging, which is important in migration studies of billfishes. Further addresses’ of welcome were made by Mr. Michio Takata, Director, Hawaii State Division of Fish and Game, Mr. J. Thomas Stuart III represent- ing Dr. John P. Craven, Hawaii State Marine Affairs Coordinator, and Mr. Peter S. Fithian, Chairman, Board of Governors, HIBT. Mr. Shomura then read the text of a cable‘ received from Mr. F. E. Popper, Assistant Director-General, Department of Fisheries, Food and Agriculture Organization of the United Nations, Rome, Italy. Dr. F. Williams, Symposium Cochairman, in open- ing the scientific part of the Opening Session indicated that the intention of the organizing committee was to commence with comprehensive and up-to-date reviews, on a worldwide basis, of the commercial and sport fishing fisheries activities for billfish. The two scientists chosen for this task, respectively Dr. Shoji Ueyanagi and Dr. Donald P. de Sylva, are experts in these fields and share a common linkage with the late John K. Howard with whom they worked closely. Dr. Williams then introduced the speakers, whose presentations are given in full in Part 2 of the Proceedings. In his review of the commercial fisheries for billfishes, Dr. Ueyanagi stated that the present world production of billfishes is approximately 100,000 tons "See Annex 3. *See Annexes 4, 5, and 6. ‘See Annex 7. per year, of which more than 90% is taken by the tuna longline fishery. Japan alone produces about 70% of the world’s catch of billfishes and is the principal con- sumer nation of these fish. Although billfishes account for only about 18% of the longline catches, they are presently of con- siderable importance, especially among the fishery products utilized in Japan. Dr. Ueyanagi discussed the value and utilization of billfishes in Japan and described how billfishes have gained status as a quali- ty fish, commanding prices comparable to the tunas. In addition, he described the expansion of the longline fishery, showing that by 1965 the fishery had covered the entire distributional range of the billfishes. Catch and effort data for billfishes indicate that swordfish is the only species which has shown an increase in land- ings in recent years; blue marlin landings have decreased in the South Pacific, Atlantic, and also, toa slightly lesser degree, in the Indian Ocean, while the catch of the striped marlin has fluctuated greatly from year to year. Dr. de Sylva stated that sport fishing for billfishes takes place in nearly all warm waters, primarily in tropical and subtropical seas. In probable descending order of relative abundance, the principal species caught by anglers are: sailfish, white marlin, blue marlin, striped marlin, black marlin, swordfish, and spearfish. He then indicated the areas of the world ocean where the most important sport fisheries are presently located. In some regions maximum angling effort coincides with maximum availability of billfish, while in other regions, especially in the western North Atlantic Ocean, Dr. de Sylva stated that maximum angling pressure is correlated with angling tour- naments which in turn relate to summer vacations and the tendency of most anglers to fish only during good weather. Angling for billfish during the ‘“‘off season” may well produce good results in areas which are heavily fished only at certain periods. It seems likely that new billfishing regions can be developed, but this requires the assistance of local governments to provide or insure adequate sport fishing vessels, docks, bait, and, especially, qualified captains and crew. Dr. de Sylva believes that the relative inefficiency of the gear used by anglers to catch billfish makes it unlikely that angling can seriously deplete the stocks, other factors such as natural environmental fluc- tuations, pollution, or commercial fishing being equal. There is tittle evidence that commercial fisheries are seriously affecting the sport catches. An exception is in the eastern Pacific Ocean, where the mean size of sailfish and striped marlin has decreased; these decreases may be attributed to heavy commer- cial fishing pressure from longline fleets. The economic value of the billfish sport fishery is extremely important to local communities which sup- port angling activities. In spite of some conser- vationist feelings promoting release of billfish which are not tagged, Dr. de Sylva noted that catches could be retained for human consumption without seriously depleting the stocks, thus further contributing to local economics. Officers and Organization of Work Officers of the Symposium Cochairmen: Richard S. Shomura F. Williams Sectional Officers: Section 1. Species Identification Chairman: William J. Richards Rapporteur: Izumi Nakamura Section 2. Life History Chairman: C. Richard Robins Rapporteur: Eugene L. Nakamura Section 3. Distribution Chairman: Nigel Merrett Rapporteur: Witek Klawe Section 4. Fisheries Chairman: Shoji Ueyanagi Rapporteur: James S. Beckett Special Session: Mercury in Billfishes Chairman: Peter S. Fithian Rapporteur: John Baxter Panel Members: James S. Beckett Albert C. Kolbye, Jr. Richard E. Marland Richard S. Shomura Cynthia D. Shultz Special Session: Sportsmen - Scientists Symposium Summary: Frank J. Hester Panel Discussion Chairman: Dudley C. Lewis Rapporteur: Peter S. Fithian Sportsmen: Peter Goadby George Parker Richard H. Stroud Scientists: William L. Craig C. Richard Robins James L. Squire Secretariat: Robert Bonifacio Robert T. B. Iversen Marjorie C. Siu Organization of Work.—Following the overview papers on commercial and sport fishing activities for billfishes given at the opening session, the Sym- posium was organized into four sections and two special sessions. The sections covered the fields of 1) Species Identification, 2) Life History, 3) Distribu- tion, and 4) Fisheries. There were 6 papers con- tributed in Section 1, 13 in Section 2, 10 in Section 3, and 7 in Section 4. A discussion period concluded the presentation of the papers in each section. The first of the special sessions was devoted to consideration of the problems related to the mercury level in fishes and consisted of both formal presentations and a question- and-answer period open to the public. The second of the special sessions was a forum for the exchange of views between sport fishermen and scientists held at the end of the Symposium. It commenced with a sum- mary of the scientific sessions of the Symposium, followed by informal presentations on various billfish topics by a mixed panel of sportsmen and scientists. A subsequent extensive discussion period was open to all. Sectional Reports Species Identification.—At this session six papers were presented covering various aspects of the iden- tification of billfishes from young stages through adults, including the fossil record of these fishes. The fossil record is rather scant, with most of the material consisting of fossilized bills. Additional research in this area of study will add greatly to our knowledge of the phylogenetic relationships of these animals. The identity of adults is quite well understood at this time with the exception of the so-called “hatchet marlin” which occurs in the Atlantic and possibly the Pacific Ocean. Evidence was presented that Tetrap- turus georgel is a valid species in the Atlantic Ocean. The question of whether or not the blue marlins and the sailfishes in the Atlantic and Indo-Pacific Oceans are distinct species, subspecies, or subpopulations is still unresolved, as is the presence of black marlin in the Atlantic Ocean. Research in the sea area off the tip of South Africa should resolve some of these problems. Three papers on the identity of the young stages of billfishes emphasized the need for further research, especially the study of variations in morphology. Data were also presented on additional characters which are useful in the separation of the young of Indo- Pacific species. Fruitful avenues for future research were suggested. These included a need for additional material, particularly small juveniles, and a need to rear these animals in the laboratory. The young stages of swordfish are quite well understood and present no problems. In conclusion, the absence of information on the anatomy of all life stages and of the eggs of istiophorids was commented upon. Further it was stressed that the scientific nomenclature and the common names for these species should remain stabilized and not be allowed to fall into disarray. Life History.—Thirteen papers were presented in the session on life history. Four papers dealt with the general biology of billfishes: the Atlantic blue marlin around Jamaica (not included in Part 2); the Atlantic sailfish off south Florida; billfishes in the eastern tropical Pacific Ocean; and swordfish in the northwest Atlantic Ocean. Another paper discussed present and future research on billfishes in Australia and New Zealand (abstract only, in Part 2). Three papers dealt with morphology: morphometrics of eastern Pacific billfishes; length-weight data of western Atlantic billfishes; and length-weight relations of central Pacific billfishes. Two papers were presented on mer- cury content in billfishes: one on northwest Atlantic swordfish and the other on billfishes from Hawaii and southern California. The remaining three papers dealt with various aspects of life history: food and feeding habits of swordfish in the northwestern Atlantic Ocean; maturation and fecundity of Hawaiian swordfish; and gastric ulcers in blue marlin and black marlin from Hawaii. The papers, and the questions and discussions following the papers, reinforced the belief of biologists that although several aspects of the biology of billfishes are now known, much more must be learned. The life history of any one species is far from being completely known. Much data have been obtained in the past from tax- idermists. The bias of using such data for certain types of studies, such as growth, was explained. Two papers referred to parasites. The existence of substantial literature on parasites of billfishes was pointed out, along with a need to collate this material. Attempts at aging billfish by counting rings of hard parts such as spines was reported for Atlantic sailfish and Atlantic swordfish, but no success had yet been attained owing to the inability to determine what length of time a single ring represented. Pollution was mentioned as a possible factor in decreased sailfish catches off south Florida. Sailfish occur closer inshore than other species of billfishes, and thus could be seriously affected. This was the only time pollution was mentioned. Distribution.—During this section of the Sym- posium it became apparent that many facets of research on istiophorids and xiphiids are of interest, not only to the billfish biologists but also to a much wider scientific community. One report contained in- formation which should be of particular interest to zoogeographers; another was concerned with oceanographic studies directed primarily towards billfish biology. In the latter study ocean temperatures were monitored by means of an airborne infrared sensor, and the data obtained proved to be of immediate use to meteorologists, environmental engineers, and other scientific and technical groups. The Symposium audience was pleased to hear repeatedly just how much the sportsmen have been able to help the scientists. Billfish tagging illustrates this very well. A great deal has been learned about billfishes from recapture of marked fish. Although most of the billfish tagging has been done by sportsmen, the commercial fishery’s role in tagging Operations cannot be overlooked. Activities of the latter is limited mainly to tag returns, including ac- companying data on the fish. Perhaps more billfish could be tagged during commercial operations; this possibility deserves attention from fishery biologists. During the presentation of reports, as well as during the discussion periods, some concern was expressed as to the need for careful planning prior to a tagging program. This is to assure not only maximum inflow of recapture data, but also inflow of data which would definitely aid in analysis of the movements and growth of the fish. An obvious need for better tags, perhaps more sophisticated tags, and better tagging techniques was stressed by several of the speakers. For example, incorporation of tetracycline, lead chelate, or some other compound in the tag could be used to mark time in the bones of the tagged fish and thus aid in age and growth studies by means of hard parts. Most of the participants were greatly impressed with the type of information which results from tracking billfish tagged with the sophisticated ‘‘sonic’’ device described by one speaker. Billfish larvae caught during various scientific cruises provide us with valuable information of the spawning habits of the adults, as well as on the early life history of the istiophorids and xiphiids. Larval studies are hampered by the considerable difficulties encountered in separating the various billfish species. The only exception is the swordfish which, even at a very early life stage, can be separated readily from the other billfishes. The problem of identification of the billfishes is so great that at the conclusion of this Symposium a 2-day workshop to treat this subject will be held in Honolulu and be attended by several larval billfish experts (Working Party on the Early Life History of the Billfishes of the FAO Panel of Experts for the Facilitation of Tuna Research). The problem of evaluating the fishing effort related to the sport fishery catch was raised. This is a difficult problem and will be discussed in the following session. Fisheries.—The papers presented in this section dealt mainly with descriptive accounts of specific fisheries, e.g., the sport fishery in the northeastern Gulf of Mexico, the commercial longline fishery in Hawaii, and the commercial fisheries of Taiwan, and with the presentation and analyses of catch statistics. From the results presented it became apparent that major gaps in our knowledge of billfish biology and population dynamics exist, particularly with regard to age and growth, mortality rates, and stock structure. One paper specifically examined the in- terrelationship of the environment and the distribu- tion of striped marlin. On the basis of data collected to date, much of what we know today of the time and space distribution of billfishes is based on catch statistics collected by the longline fisheries prosecuted by Japan, South Korea, and Taiwan. In addition to being far-ranging, the gear used by the various longline fisheries is essentially the same; thus, the indices of abundance are comparable. This comparability of data was not found to be true for the data collected by the sport fisheries. In the dis- cussion that followed this session, it was recognized by participants that although the sport fisheries for billfishes represents a rich source of good data, biologists are not fully utilizing this source. With a few exceptions, the kinds of catch and effort data collected by individual fishermen, sport fishing clubs, and biologists vary so widely that the data cannot be pooled. One shortcoming noted in sport fisheries data is the lack of recorded zero catches. The importance of this information was discussed in some detail. The need to standardize the collection of billfish statistics from sport fisheries was apparent. Although the billfish landings in some areas, e.g., Taiwan, showed increases in recent years (possibly reflecting increased effort), the general trends for the several species of billfishes noted in the catch statistics of the commercial and recreational fisheries are downward. In the eastern Pacific Ocean the decline in apparent abundance was especially noted for sailfish. The catch rate dropped from 80 fish per 1,000 hooks in 1963, the first year of substantial long- line fishing in the major sailfish grounds of the eastern Pacific Ocean, to 11 fish per 1,000 hooks in 1970; a decline of 86%. Similar declining trends of billfish catches were reported for other areas of the world by Dr. Ueyanagi in his review of the world commercial fisheries for billfishes presented during the opening day’s session. Special Session: Mercury in Billfishes This special session began at 2000 on 10 August 1972, at the Hale Halewai in Kailua-Kona, Hawaii. Approximately 150 people attended; participants were mostly from the sport fishing fraternity. The purpose of the session was to provide participants in the HIBT and the interested public with the latest available information on the problem of mercury in fish and the opportunity to discuss the situation with experts on the subject. Presentations were made by the five panel members; two were summaries of scien- tific papers given at the International Billfish Sym- posium; two described work done in the State of Hawaii; and the fifth featured Dr. Kolbye, who described the effects of mercury on humans, the role of the FDA, and the rationale for its guideline level of 0.5 ppm mercury in fish. Presentations James S. Beckett “Mercury in Northwest Atlantic Swordfish” Mr. Beckett reported that Canada banned the sale of swordfish in 1970. Up until that time the annual swordfish landings in Canada amounted to about 8 million pounds valued at $4 million. Beginning in July 1971, a vessel of the Fisheries Research Board of Canada conducted longline fishing from Cape Hatteras to the Grand Banks to obtain swordfish for analysis of mercury levels. During cruises in July and August 1971, 210 swordfish (lengths ranging from 74 to 247 cm fork length) were taken. Samples of dorsal muscle analyzed for total mercury showed an average of 1.15 ppm and a range of 0.09-4.9 ppm. Differences in mercury level were noted between females and males as well as between tissues; liver and kidney had higher levels than brain tissue. Mr. Beckett reported that swordfish appeared to pick up mercury in southern areas and lose it during the summer on the feeding grounds in northern areas. His conclusion was that the source of mercury is volcanism in tropical areas and that mercury is being picked up by fish through the food chain. The full text of this paper is included in Part 2 of the Proceedings. Richard S. Shomura “Mercury in Several Species of Billfish Taken Off Hawaii and Southern California” Mr. Shomura noted that since December 1970, when the subject of relatively high mercury levels in tunas and swordfish became news, NMFS has had an ongoing sampling program to determine the mercury content in several important sport and commercial fish and invertebrate species. The 56 striped marlin taken from waters off southern California and Hawaii and analyzed for total mercury ranged in size from 56 to 231 pounds (25.4 to 104.8 kg). The total mercury levels for white muscle tissue varied from 0.03 to 2.1 ppm; there was no obvious relationship with size of fish. Although the white muscle of 37 blue marlin also showed a wide variation, a trend of an increasing mer- cury level with increasing size of fish was noted. The mercury levels ranged from 0.19 to 7.86 ppm; fish size ranged from 96 to 906 pounds (43.6 to 411.0 kg). Mr. Shomura reported that the total mercury levels in blue marlin livers ranged from 0.13 ppm to a phenomenal high of 29.55 ppm. He stated that a com- parative study of identical tissue samples analyzed by two laboratories showed wide variations in results; one laboratory reported higher values consistently. He concluded by stating that the NMFS program was collecting mercury data as it relates to the fishery resources and was not presently addressing itself to the effects of mercury on mankind. The full text of this paper is included in Part 2 of the Proceedings. Cynthia D. Shultz “Total and Organic Mercury in Marine Fish” Ms. Shultz reported that a part of their mercury study was concerned with determining the proportion of methylmercury in billfishes. A large number of marlin samples obtained with the assistance of NMFS were analyzed at the University of Hawaii laboratory and also analyzed by an expert in Sweden; the results of the two sets of analyses agreed very closely. Mercury levels in the billfishes ranged from 0.35 to 14 ppm. Of the total mercury, organic (methyl) mercury constituted a small percentage (up to 10%). One example, a 155-pound (70.3-kg) fish, contained 4.1 ppm total mercury and of this 0.54 ppm was organic mercury. A regression analysis of all samples tested showed an asymptotic level of 1.55 ppm organic mercury. Ms. Shultz noted that their studies in- dicated an upper level to the amount of organic mer- cury accumulated and theorized that any amount over and above this level was transformed into in- organic mercury and excreted. She also theorized that mercury in billfishes originates from natural con- tamination, possibly of a volcanic origin; however, much more work needs to be done in this area. This paper authored by J. B. Rivers, J. E. Pearson, and C. D. Shultz has been published in the Bulletin of En- vironmental Contamination and Toxicology 8(5):257- 266, 1972. Albert C. Kolbye, Jr. “Potential Health Hazards of Mercury in Fish” The full text of this presentation appears as Annex 8 of this volume. Richard E. Marland “Status of Mercury Studies in Hawaii” The full text of this presentation appears as Annex 9 of this volume. Discussion.—The following includes some of the more significant questions asked of the panel by the audience, and the panel’s answers.° George Parker (Kailua-Kona, Hawaii): Ms. Shultz referred to fish tolerating a certain amount of methylmercury and then possibly convert- ing it to another form of mercury which is excreted. Might this follow with humans? Ms. Shultz: We don’t know the answer. Our data merely in- dicate that biotransformation may be taking place. Captain Parker: Does methylmercury keep being accumulated? Dr. Kolbye: The biological half-life of methylmercury is 70 days; to stay below the safe blood level the intake of pe ercury should not exceed 30 micrograms per ay. James Delohery (Australia): Would you comment on selenium detoxification? ‘For purposes of brevity, the question and answer section has been abbreviated and in some cases paraphrased. Mr. Beckett: There was some work that suggested that selenium may reduce toxicity of mercury; however, more work is needed. William F. Royce (NMFS, Wash., D.C.): Why did FDA impose a prohibition on the sale of fish with mercury levels over 0.5 ppm rather than merely warn the public such as is done with other products containing poison? Dr. Kolbye: The public has a varying understanding, a varying consumption rate and therefore FDA determined that a guideline was necessary in the interest of protecting the public. With respect to swordfish, 95% of the samples exceed the guideline. There are also FDA guidelines for other food items and toxicants. Witek Klawe (IATTC, La Jolla, Calif.): Would you comment on various articles criticizing the mercury guideline? Dr. Kolbye: FDA is prepared to defend the guideline. Dudley C. Lewis (Honolulu): Why were there no public hearings held before the guideline was set? Were any of the deliberations made public? Was the guideline politically motivated? Dr. Kolbye: Many guidelines do not require hearings. The guideline was reviewed extensively within FDA and by a panel of 12 experts. Testimony was given before the U.S. Senate. Scientific documentation was presented in the Journal of Environmental Health. I don’t know if this is considered making it public. The question as to whether the guideline was politically motivated is ridiculous. Richard F. MacMillan (Honolulu): People have been eating marlin in Kona for generations with no ill effects. Therefore, I question Dr. Marland’s statement that years and years of work is needed to come up with an answer. What is your reaction to the situation in Kona? Dr. Marland: There is no evidence of damage from eating marlin in the United States. However, there has been no systematic search for subclinical symptoms. Studies by trained medical doctors to look for subtle symp- toms would be highly desirable; however, it cannot be done quickly or cheaply. Richard H. Stroud (Sport Fishing Institute, Wash., DiC:): Is the 0.5 ppm guideline for total mercury? In view of recent findings regarding methylmercury not con- stituting 100% of the mercury present, shouldn’t the standard be for methylmercury? Dr. Kolbye: The guideline is for total mercury. Methylmercury is the dangerous form, but much needs to be learned about the toxicity of all forms of mercury found in fish. It would be of interest to determine the exact chemical form of the nonmethylmercury part found in marlin. Fred Rice (Kailua-Kona, Hawaii): Regarding the University of Hawaii study—was mercury added to the feed of the swine? If the swine were fed marlin without the added mercury part, would there be any effects? Dr. Marland: Yes, mercury was added. No, they showed no effects if mercury wasn’t added; however, controlled ex- periments are needed. It is not a question of just feeding marlin containing mercury without ex- perimental controls. Mr. Rice: Is there any information available on what is being done with the marlin being caught? My guess is that probably 90% is being consumed by humans. Does the FDA have authority to intercede in cases where the fish is caught in Hawaiian waters and consumed in Hawaii? Dr. Marland: We don’t know the disposition of the marlin caught. The guideline is a responsibility of the Director of Health for the State of Hawaii. Question: Has the economic impact of setting the guideline been considered? Dr. Kolbye: With the public health at stake it is necessary to act quickly. Severe cases in Japan showing diffuse brain damage give good cause for such a guideline. Richard E. Young (University of Hawaii): Would you comment on the case of the woman in New York who suffered mercury poisoning? Dr. Kolbye: Apparently this woman consumed swordfish daily; however, this cannot be fully documented. Captain Parker: Sweden made a mistake in calculating their guideline. Has anything been done to change it? Dr. Kolbye: They have not changed their guideline. Sweden has taken the following steps: (a) they close certain streams, (b) they advise that no more than one meal per week of fish from certain areas be eaten, and (c) they advise pregnant women not to eat certain fish. Captain Parker: How much trouble would it be to take samples of the dorsal muscle and determine the mercury level? Mr. Beckett: It would be extremely expensive—about $1,000 per sample. Ms. Shultz: The amount of money is not the problem—time is—it requires 45 h to process each sample. Captain Parker: Is it true that broadbill swordfish landed in Califor- nia are sampled for mercury and can be sold if found safe? What is the form of the FDA ban? Dr. Kolbye: Regarding swordfish in California, as far as I know, they are being handled as you have noted. The tuna and other industry people are cooperating in conduct- ing such monitoring programs. It may be possible to do this for marlin; however, it must be done by an accepted laboratory to assure that it is done correctly. Captain Parker: What did the general public hear with respect ta marlin in Hawaii? Are we breaking the law if we give away fish? Dr. Marland: The Director of Health in Hawaii publicized the fact that the marlin contain unsafe levels of mercury, and received a voluntary withdrawal of billfish from the market. If fish are given away it breaks the gentlemen’s agreement. If the fish are not fit for human consumption, they should not be given away or eaten under any circumstances. Peter S. Fithian (Honolulu): Throwing away fish is a philosophical problem. We have run out of time. Thank you all for attending and contributing to this most worthwhile discussion. Special Session: Sportsmen—Scientists Symposium Summary (Frank J. Hestert USA).—Dr. Hester provided the sportsmen-scientist gathering with a summary of the results presented at the scientific sessions and the special session covering mercury in billfishes. His presentation was made with the aid of a number of slides which were used by the various speakers. Since Sections 5 and 6 include sum- maries of the sessions, and the full text of the papers is given in Part 2, only Dr. Hester’s closing statement’ will be included here. It follows: I would like to make some general comments. Billfishes, because of their size and scarcity, are very difficult animals with which to work. It is very dif- ficult to find fresh material and even more difficult to find living material. These are probably the main reasons why today the state of knowledge of billfish biology is really not very far advanced. We are cer- tainly always very grateful for the opportunity to take advantage of a tournament like this, where one can actually see the fish when only a few hours old. This, along with the logbook recording, the cooperative tag- ging programs, and the information from the commer- cial fisheries probably is going to mean that in the next decade we will begin to understand these animals much better. To bring about this understanding will require considerable work on the part of the angler, who will have to be prepared to keep detailed records, and either mail them in or have them delivered at dockside. You will also have to put up with the oc- casional biologist “poking around” your fish. Finally, you should be prepared to change to the metric system of measurements in the very near future and this means you will have to rewrite the International Game Fish Association (IGFA) world records. Thank you very much. Panel Presentation (R. S. Shomura, Symposium Cochairman).—I would like to start by stating that we are extremely fortunate—and I think this was ex- cellent planning on our part—in having as Chairman of this morning’s Sportsmen-Scientists Panel Session Mr. Dudley Lewis, who took the winning prize in this years HIBT tournament. It is also fitting that he assumed the post as Session Chairman at this closing meeting, since he is the only sportsman-angler who has participated in all 14 of the HIBT tournaments. Mr. Lewis was born in Hawaii some few years ago and has been fishing all of his life. He is presently a prac- ticing lawyer. It gives me great pleasure to introduce Mr. Dudley Lewis. D. Lewis (Chairman) Ladies and gentlemen, the format of the Sym- posium this morning is the following. We have with us three sportsmen and three scientists and I will call alternately on each of the scientists and sportsmen to make a short statement. At the conclusion of their remarks we will welcome questions either from the panel or from the audience. First, I will call on Dr. C. Richard Robins, University of Miami Professor, who has done a lot of research on billfishes, to give you some idea of his work and what can be done to further the dialogue between scientists and sportsmen. C. R. Robins I want to start not with an account of what I or my olleagues have done at the University of Miami, but ith some of the problems that we run into in dealing ith billfishes and what we need in the way of infor- ation. Firstly, we have lost much valuable data from the hotographic record that would have otherwise been vailable to us. If one goes to any of these tour- naments, one cannot help but be impressed with the number and quality of the cameras but, from our standpoint, many of the photographs are of poor quality. Of course, we have nothing against the types of photographs that you want for your own records, but Don de Sylva and I very frequently are called upon to identify fish from photographs. It is extremely difficult to do so when the fish is hanging up and the cameraman is very close causing foreshortening, which jeopardizes our obtaining good body propor- tions. Very often the angler, the captain, or mate will have his hand over some very critical character such as the dorsal or pectoral fin. In taking photographs this is really what we need. First of all I think that every photograph should have a small identification tag with it—it can be just a piece of paper like we’ve had at this tournament—which indicates the locality of capture of the fish, the weight, and the length. Photographs have a habit of going astray for many years and then we get a whole pack from a person say- ing, “I think this is a fish I caught off Malindi, Kenya,” when in fact it may have been one that was caught at Bay of Islands, New Zealand. This leads to difficulties, so if you have an identification tag as part of the photograph there is never any question about the origin of the fish. The next thing is to try to take the side view of the fish with as little distortion as possible. It is often very easy to get to the tower on your boat and shoot a picture of the fish in the cockpit with very little distortion. In other cases it is very sim- ple to allow the fish to hang, as you often do here at Kona, then back off and take a telephoto shot of it and this reduces the distortion. In addition to the side view, it would be very helpful to take a picture of the underside of the fish, at least from the area of the anus forward. The position of the anus relative to the anal fin is very different in the different kinds of marlins, especially in the Atlantic Ocean. In the spearfish the anus is very far forward, in the white marlin it is very far back, and in this new species we call georgei it is in a sort of in-between position. This undershot can also show the very important shape of the pectoral fin. Marlins are wonderful machines, being really well adapted for high-speed swimming in the ocean. The blue marlin, as you know, maintains its depth a long way aft, so if you take the center of gravity of this fish, it is fairly far back. These animals can swim along very efficiently and they keep their pectoral fins pretty much back toward the socket. The black marlin has its weight far forward and really is front heavy. If you could cut the pectoral fins off this fish, it would pitch and go right down toward the bottom. Its pectoral fins are therefore actually stabilizers. If you look at the cross section of the pectoral fin of a black marlin it is very different from that of a blue marlin, being shaped like the cross section of an airplane wing. This fish really flies through the water and gets lift to compensate for pitch. The pectoral fin alone can distinguish the blue marlin from the black marlin, and yet in many photographs Don de Sylva and I are unable to tell anything about the pectoral fin because the fish is hanging up and the fin very commonly will flop down. The shape of the dorsal fin is also important. I think it really doesn’t cost very much to take three photographs, one of the whole fish, one from un- derneath, and one close-up view of either dorsal fin or the pectoral fin. But don’t forget the identification plate with the geographic information on it as a per- manent record. I would like to direct this next remark mainly to the scientists. If you ask anglers to do something, then you should give them specific instructions as to what it is you want, and when you do this you assume cer- tain responsibilities. Nothing makes me madder with scientists than to have one of my colleagues commit anglers to doing something and then never follow-up on it. I’ve seen the late Al Pfleuger of Miami spend a lot of money, and an awful lot of time, gathering data for some biologist and after he did all of this nobody would show up. I think this is the kiss of death in cooperation. If you ask anglers to do something, you have an ethical responsibility to pick up the informa- tion and to provide them with some sort of a report on what it is that you have done with it. D. Lewis Thank you very much, Dick. I will call next on Peter Goadby, an outstanding sport fisherman and author who has traveled all over the world. Peter Goadby (Australia) Australia’s offshore game fishermen have always been proud of the fact that they have cooperated ac- tively with scientists. Being somewhat isolated, we have realized that the sport fisherman is in a unique position to help the scientist because they are the only ones that can help us with things we are unable to learn. If we record data accurately then the scientist can give us a lot of help. We are as proud of our con- tribution to the ‘‘establishment”’ with the capture of blue marlin at Cairns last season as with the 10 marlin we caught averaging 1,000 pounds each. We are for- tunate in Australia at the moment that in addition to the various government agencies and institutions, there is a well-founded university coming into being at Townsville just 250 miles from the Cairns marlin grounds. There is every indication that some research on the black marlin will be undertaken at this institu- tion. The cooperative tagging program in Australia has had remarkable growth, and as an Australian fisher- man | take my hat off to NMFS for the assistance they have given us. It gave us pleasure slamming a tag into a fish knowing that the tag had come from the United States and that the information would come back 10 perhaps from a Japanese or Taiwanese longliner through the United States. This really made us feel we were part of a worldwide program. The growth of tagging in Australia is interesting as 10 yr ago there were probably no more than two or three fish released in any one season and recoveries were nil. As you have already heard, there have been two black marlin recoveries already. The first fish was out ap- proximately 360 days and was returned only 100 miles from where it had been tagged. The second one, 1 of the 169 fish tagged at Cairns last season, was out only 110 days but had traveled something like 1,440 miles in that time. Tagging is now being started in New South Wales and later we will have the help of anglers even farther south. The program will be not only on marlin, as we are encouraging anglers to tag and release every kind of fish including offshore species of sharks like hammerheads, makos, and blue sharks. We are not really encouraging the release of white or tiger sharks, because we feel if someone got ‘chopped up” on the beach and a tagged shark was caught we would certainly be in trouble. Anglers in Australia have long shown their interest in cooperating in any overseas programs. We were most happy to cut the pectoral girdles from black marlin to send to Dr. Robins, and to provide data on the blue marlin in the Pacific. We would be most hap- py to give any help we can on the size and movement of the black marlin, or anything else anyone wants to do on that species. The same applies to any studies on sharks. We still have a lot of dangerous species of sharks in Australia, and if anyone is interested in them we would be happy to help. As I said previously, | this meeting of fishermen and scientists is really great, and I believe the best thing that has happened in sport fishing probably in the last 100 yr. We have always known the names of a lot of scientists, and I guess similarly the scientists have always known the names of a lot of interested charter captains and in- terested sport fishermen. Now we have got names to go with the faces and faces to go with the names, so let us all keep in contact and go forward from here on. D. Lewis Thank you very much, Peter. I shall call on Mr. William Craig, formerly with the California Depart- ment of Fish and Game and now with NMFS. W. Craig (USA) I obtained my experience with the billfishes, primarily striped marlin and broadbill swordfish, dur- ing my time with the California Department of Fish and Game. My main responsibilities were to other major programs and moving around in the billfish fishery was quite incidental and confined simply to compilation of adequate catch statistics for these two species. The mercury problem last year finally gave me an opportunity to join the ‘“‘blood-and-guts”’ detail and to see what a striped marlin looks like. I had, of course, every cooperation from the local sport fishing clubs in California, as otherwise it would have been a monumental task to try to gather all these specimens of striped marlin for determination of mercury con- tent. I might go back and say it was a mandate from the big-game sport fishermen in southern California that made the Department undertake a program to try and clarify the situation with regard to mercury. We collected striped marlin samples and delivered the results of the mercury analyses to the sport fishing clubs. Cooperation can be obtained from sport fishing clubs by working with them but reiterating what Dick Robins said, do not ask for something unless you can follow up on it. Additionally, I would like also to indicate the value of club yearbooks. Some clubs just report their annual catches and their annual buttons and awards, while others present historical data on catches and in- cidents that took place. One particular club yearbook contains a couple of articles by lawyer members that contribute much to our knowledge. I wish to call these types of publications to the attention of scientists because there is certainly a great deal of merit in what the sport fisherman has to offer from his on-the-spot observations. I brought these particular two yearbook issues for Dr. Ueyanagi, because they contain some data on the marlin weight-frequency distributions in the southern California fishery. These data were collected since the publication of his joint paper with Colonel Howard. My small mercury program last summer, which was just a “news note,”’ was picked up and published in this little booklet. If club articles warrant it, and are called to our attention, perhaps we can see that they obtain wider distribution than the clubs themselves can provide. D. Lewis Thank you very much, Bill. I next call on Mr. Richard Stroud, the Executive Vice-President of the Sport Fishing Institute, who will make some remarks on the role of that organization. R. Stroud (USA) It’s a great pleasure to be here, first because it’s the first time I have ever been to Hawaii and secondly, because I guess I am unique at this gathering since I am the only official “hybrid” to appear before you. Although I am sitting on the sportsmen side it is hard for me to determine whether I am really a sportsman or scientist—perhaps a little of both. I have worked in both areas and I enjoy and participate in sport fishing to a great degree. Nevertheless I would like to take a little time to acquaint you with my organization. On the table I have put some propaganda which explains the nature and purpose of our organization and also ital some application blanks. I have also prepared a few mimeographed comments on the role the Institute has played over a long period of time and I invite you to take a copy later. The Sport Fishing Institute is the only national non- profit, tax-exempt conservation organization devoted wholly to the conservation of fisheries resources, and it was designed to help fishing and, consequently, fishermen. It was established in 1949 and functions as a research, education, and professional service type Institute, and is staffed entirely by fisheries scientists. It was designed to be a catalyst for development and promotion of the application of all types of progressive fish conservation programs in order to enhance the sport of fishing. In the course of general overviews of fish conserva- tion it became very apparent, a couple of decades ago, that very little was being done in the inshore area between the seashore and the high seas. The existing institutional agencies were concerned either with in- land types of resources or high-seas resources. There was real diversion of interest away from the very critical and sensitive area of the coastal zone and es- tuarine areas which are vitally important to the con- tinued survival of many of our game fishes. Conse- quently, we attempted to stimulate a lot of activity in this area and founded a research program of our own, small in size but designed to stimulate interest. I think we were successful in doing that. We began making grants as early as 1952. Our first research grant in the billfish area was a small one made in 1958 to an investigator at Yale University to work at an east coast tournament similar to this one. We made a follow-up grant later to South Carolina University in 1959 to develop further studies on the life history of the blue marlin and white marlin. Then we became interested in the work that Frank Mather was doing at Woods Hole, the Cooperative Game Fish Tagging Program, and for more than a decade have provided small but continuing annual support to that program. Based on the research we have done, and the ob- vious problems and needs that existed, we felt it was necessary to enlist the support of the Federal and State governments as much as possible. We have great interest in the Dingell-Johnson Program, which is supported by an excise tax you pay when you buy a reel or big rod. These funds are channeled to the States, which were stimulated to use some of this money for marine game fish research, but there was nothing being done at the Federal Government level. The then Bureau of Commercial Fisheries was in- terested almost exclusively in the high seas. So we drafted a bill, which eventually became known as the Marine Game Fish Research Act and this was passed in 1959. This marked the formal entry of the Federal Government into this area of concern which had been previously neglected. Early in the 1960’s, as you are all well aware, Japanese longlining exerted fishing pressure on the stocks with an evident adverse impact on sport fishing. I am not going to go into that as the analyzed data and results are well known.-In any event it was decided to hold a meeting in Rio de Janeiro in 1966 to consider the formation of a conservation organization to be concerned with research and management of the tunas and tuna-like fishes of the Atlantic Ocean. I was fortunate enough to be an advisory member of the U.S. delegation, together with a representative of the Bureau of Sport Fisheries and Wildlife (the late Albert Swartz). Preceding the Rio conference, a series of meetings was held with representatives of sport fishing interests nationwide, at which we tried to determine the course of action we might possibly pursue in Rio. We decided there were several things we ought to do. First, and most important, we sought to have a separate meeting with representatives of the Japanese delegation, par- ticularly the private individuals representing the commercial fishing industry. We sought four objec- tives: 1) recognition that there was a significant problem of mutual concern due to the longlining ac- tivity; 2) agreement that the longliners should remain a sufficient distance from billfish sport fishing centers to preclude direct conflict; 3) an agreement that even- tually there would be convened an international scientific conference on billfish biology; and 4) management following not less than a decade for research. The Rio conference resulted in the establishment of the International Commission for the Conservation of Atlantic Tunas and this also embraced responsibility for research and management of billfishes. The con- ference also provided the hoped-for opportunity to talk with Japanese commercial fisheries interests. As a result the objectives that I have outlined were sub- stantially agreed to and, in return, the U.S. sport fisheries representatives agreed to promote cessation of destruction of Japanese longline gear. Following the conference, we came back here and held a series of meetings across the United States with representatives of sport fishing groups promoting this latter part of the agreement. Obviously, if you are go- ing to get something you have to give something in return and it seemed to us that this was a very reasonable arrangement. Until recently, aside from a few temporary minor relapses, matters seem to have worked out well since conclusion of the agreement at Rio. Several incidents have occurred, though, which underscore the usefulness of the agreement. In the spring of 1967 for example, my organization formally requested that the Japanese overseas trawlers associa- tion revise previously announced plans for exploratory trawling along the east coast of the United States. As a result of several exchanges of correspondence, these plans were substantially altered so as to operate in waters north of the Miami-West Palm Beach area in Florida, and offshore, well beyond the range of the 1- day charter trips out of the more important angling ports along the Atlantic Coast from Florida to East- 12 port, Maine. Last year several Japanese longliners commenced fishing in the Gulf of Mexico, and are continuing to do so this year, and have come into con- flict with the long range, private charter sport fishing craft characteristic of that area. There was a flurry of excitement over an alleged mass harvest of billfishes based on shark fins, hung to dry in the superstructure of a Japanese ship being misidentified as marlin tails. I had it on the best of authority from NMFS peo- ple that these were indeed shark fins. This point was cleared up, but the longliners remained sufficiently close inshore to come into occasional contact. I un- derstand that some of them have drifted even beyond the legal limit in the past few days, perhaps accident- ally. Based on documented data provided by the Coast Guard on request, and also through the help of NMFS, we relayed this information to our Japanese contacts and suggested that they have a special problem in the Gulf of Mexico. We urged that they in- struct their fishermen, if they intended to continue implementing our unofficial agreement, to move farther back offshore. As yet, nothing has been done but we have some information which suggests such in- structions will be forthcoming. It seems to me that it is highly desirable that ‘‘en- vironmentally concerned’ sport fishermen refrain from the destruction of Japanese longline gear. I can- not emphasize too strongly that if there is to be any kind of a quick settlement to the benefit of American sport fishermen, then we have to hold up our end of the bargain. If it turns out that the Japanese have decided to abrogate the agreement, then we will have to see what other measures may be taken. I am not convinced yet that the agreement is without viability at this time and I believe that we should do everything we can to show we are holding up our end of the bargain. I want to put in a special plea in terms of the official role 1 am supposed to fill here. As far as sportsmen are concerned, I think one of the things you must do, if we are going to find out enough about billfishes to even- tually hold out hope for a bilateral treaty conference with the Japanese and to work out an international rational management plan for these fishes, is to provide money for this research. I do not necessarily mean directly, but at least indirectly, through support of appropriations to the agencies who are doing work. Obviously this is very expensive research, and you have had examples of it here. For example, if we are going to build saltwater study lakes to support adult black marlin as we have heard suggested, I can see that it is going to be fantastically expensive! Even when we are talking about $120 tags, that also is pret- ty expensive. I think there is going to be a great effort made on the part of the Federal Government (NMFS) to show they are spending an awful lot of money right now on billfish research. They are going to take all the different pieces from existing programs with commer- cial fisheries activities and say “this is what we are doing and we are doing a good job.”’ But what we want is additional research if we are going to have answers to these problems. We have got to have additional money to do it and that has got to come out of ap- propriations made by the Congress. Ican tell you right now that the Congress is not very sympathetic and this means you are going to have to get some political pull behind this thing. You are go- ing to have to write your congressmen and tell them to give these boys (NMFS) the money. Our organization will try to spread the word when appropriations time comes around. From the standpoint of the scientists, obviously, I think we want them to do the work and provide the information that’s necessary to come up with the rational management programs. However, I think I would suggest at this time that, philosophical- ly, the scientists are going to have a very difficult problem. They have based most of their work in the past on the concept of maximum sustainable yield, having been trained this way, as this has been the cor- nerstone of commercial fisheries management. I sub- mit to them that this has been an inadequate philo- sophy for rational management of sport fisheries. D. Lewis Thank you very much, Dick. I now call on Mr. James Squire, who is a fishery research biologist with NMFS in La Jolla, Calif. James Squire (USA) Iam with NMFS in La Jolla though formerly I was at the Tiburon Laboratory. You heard Dick Stroud state that about 1960 the Marine Game Fish Program was established and one of the laboratories that it had started was at Tiburon, Calif., with which I became associated in 1960. This laboratory was exclusively for ‘Marine game fish and this function shifted to NMFS ‘in 1970, when there was a revision of programs. I | moved down to La Jolla with a program to study bill- fish migrations through the tagging programs in the Pacific Ocean area. _ There is concern for the billfishes in view of a new increase in the utilization of these resources as in- dicated by actual decline in the worldwide catch of billfishes. As Dick Stroud pointed out, if you are to attempt to manage this resource you must certainly take into account the needs of the users, both sport fishing and commercial. We manage these things in different ways, the commercial fishery on maximum sustainable yield and the sport fishery on large numbers of big fish. These two concepts are in conflict and will certainly have to be resolved in the future. In 1961 we became involved in billfish research in the eastern Pacific Ocean, primarily life history work and the tagging program, looking forward to the day when such information will be needed to make rational management decisions. We indicated at this meeting the problem of obtaining good catch and ef- 13 fort data and this is a field where a sportsman can contribute greatly to research. We get good catch and effort data from the Japanese commercial longline fisheries throughout the world but the collection of similar data from sport fisheries is very poor. What is needed is better fishing logs, and people must be will- ing to carry them and fill them out to the best of their ability. The purpose of all this catch and effort data is to show effectively the catch rate in the sport fishery and how this is possibly being affected by changes in the catch rates in the offshore commercial fisheries, which sample a greater number of fish throughout the eastern Pacific Ocean. I think we can say that the sport fishery probably takes about one twenty-sixth the amount of fish that the commercial fishery takes in the eastern Pacific Ocean. Despite these good data from the commercial fishery, one needs to know how it is affecting the sport fishery if one is involved in any international negotiations. You have to have the scientific proof. This is the reason for encouraging sportsmen and clubs to keep better records of catch and effort. Not only are we interested in the days of fishing with catches, but we are interested also in the number of days when people go out and do not catch fish. Using only days of effort which produce catches does not give a true measure of what is actually going on. We certainly need more data on environmental fac- tors such as temperature and water color. As F. Williams said here yesterday we are studying a living animal in a moving environment and everything is changing from day to day. We need to know how billfish move in relation to the environment because this may tell you why you are not catching fish. There are possibly two reasons, either the environment is not right for the fish, or the year class strength is low and there are not many fish around. To determine which of these factors is more important we must know something about both. We need to know more about migration patterns which sportsmen have assisted us with in the past and are continuing to do. We must define the normal range of the fish in the ocean, as this has a very definite influence on the type of management you might use for the resource. For instance, in the albacore fishery of the North Pacific Ocean you can take fish off Catalina, Calif., and then some 5 mo later they will be south of Tokyo, Japan. You certainly can- not just manage the fish off California, as the resource is ocean wide. This is why migration studies are im- portant. Another example would be the yellowfin tuna in the eastern Pacific Ocean. Scientists have tagged many thousands of them and found a north-south migration pattern with very little east or west move- ment, so they drew a boundary line at long. 130°W. Does this hold for billfish or are they transpacific migrators? This is one of the reasons for starting the tagging program. I think sportsmen realize we have a high mortality rate with tagged billfishes, but they are still willing to tag these fish. I see a challenge here to the sportsmen to find better ways of hooking fish or getting them alongside so that they can be more easily tagged, thereby reducing mortality from this cause. At pres- ent the only way to catch billfish is by hook and line either with the longline or rod and reel. An exception is by harpooning them and that is not very satisfac- tory for our purposes. We need to know the economic value of sport fisheries. The billfish catch by sportsmen is not great, but the sportsmen spend a lot to catch them. The sportsmen, as Dick Robins said, assist us in the collection of biological data but there is one thing that I think they could collect in addition to weight, and that is length; of course, some do this routinely. We should also collect data on the sex of the fish and this is not so difficult. In summary, we should give a little training and urge the marine game fishermen to take an interest in the billfish resources and the future management of them. As Dick Stroud pointed out this needs funds not only from our country but from other countries around the Pacific Ocean (and worldwide). These countries or states should be encouraged to conduct additional work on the billfish resources off their coasts. I urge the marine game fishing world as a whole to get a copy of the Proceedings of this meeting and to read it, because I think you will find we have summarized just about all the knowledge on billfishes worldwide. Hopefully this will give us a better in- formed and enlightened marine game fisherman geared for the billfishes. D. Lewis Thank you very much, Jim. Our last panelist is one that I am sure you all know. You have certainly heard about him, he is one of the pioneer charter captains of Kona, he’s been at it a long time, he is knowledgeable, and it gives me great pleasure to present another good friend of mine, George Parker. G. Parker Thank you, Dudley. Iam a charter boat skipper and I think I have been at this for 28 yr now. This year I am president of the Kona Charter Skippers Associa- tion which comprises some 18, possibly 17 boats now that we lost a boat last night in the Kona area. I have just thought of a real good reason for all of us being here, in addition to the reasons that are quite obvious. It is said that this globe is covered three-fourths by water and only one-fourth by land, and it is for sure the good Lord intended for us to spend three-fourths of our time fishing and the balance ploughing. I cannot tell you how excited I am about this meeting. Kona is just bursting its seams with scien- tists and other people knowledgeable about billfish; 14 all kinds of fish for that matter. I want to emphasize that Kona is certainly proud to have you all here from all over the world for what I understand is the first ever Billfish Symposium. The Charter Boat Associa- tion, which I represent here this morning, could not be happier about this event. It has been said that it is important that the charter boat captains and crews, as well as the private sport fishermen, realize that they can be a very great help to the scientist. They should be alert and report the things they see, the things that happen aboard the boat relating to fish, water currents, temperature, and other conditions of interest. For example such facts that one day we see thousands of porpoises then the next day there isn’t a porpoise near the boat. Or when the humpback whale comes down here what happens then? Does he scare off all the marlin? Do the currents make that much difference to our fishing? We all en- counter these things when we’re at sea but we don’t record them, and although we talk over the Citizen Band (CB) radio to each other about what we think the current is doing and why we are, or are not, catching fish, it never seems to get beyond our association and our daily conversations. Possibly one result of this meeting and what’s been said here this morning might bring about a form that we could have aboard each charter boat to be filled out. We have plenty of time between strikes and it doesn’t have to be something to be done after you get home when you're so tired and can’t think straight. We all have writing space aboard our boats. We could have a pad of forms to fill in, even if it’s virtually © reduced to a form where you just check off the items as you go down a list. At least we have to do something more than we’re doing at present. We’ve got to help the scientists with our firsthand knowledge. We’re out there on the grounds rather like a weather ship out on the channel that reports the weather as it comes through, so we are the outposts and we have to re- spond about fishing. At the coming meeting of the Charter Skippers Association we are going to have some time devoted to the form of help we can offer to the scientists and in turn to ourselves. The realization of what we can do has been growing. Even before this Symposium some of our skippers have been recording certain types of information. It even occurred to me to put a tape recorder aboard my boat and tape what comes in over the CB. This could be one way of start- ing a record of daily fishing conversations; possibly some one on the shore, who has a good CB radio could tape record some of the fishing conversations that go on off the Kona coast. We are so fortunate here to have a calm, comfort- able sea to fish in and some days with a lot of fish. I wonder if we realize how lucky we are. Most good billfishing areas are so rough that you are standing on your beam ends and yet people still go out fishing for them. I would say we are spoiled here with our lee shore that extends out so far that 95% of the time we hardly have a whitecap. I think the 5 fishing days of this tournament have shown people what the Kona coast can be like and why it’s so easy to enjoy a day at sea and land a billfish, if you’re lucky enough to hook into one. Lately we have heard a lot of discussion on conser- vation of fish and possibly the mercury in billfish scare has emphasized this. The belief is now that there is a dangerous level of mercury in the blue marlin and here in Kona we catch more blue marlin than anything else. As I have said before, and I will say again, part of the revenue in the charter service is the sale of fish, if and when the angler leaves it with the skipper. We depend on that sale and it has been some help in holding down our charter prices and without it we are seriously hurt. The blue marlin revenue is shared between the skipper and the crew and some of the boats have gone out of service because they could not take that decrease in the share of the profit. However, it is an ill wind that does not blow some good, and here the good is concerned with con- servation of billfish. I think it’s a general trend at Kona that if a person catches a billfish and it is his first fish, we usually keep the fish because the ego has to be built up witha photograph of the fish hanging at the dock. We can well understand that and it is worthwhile, as well asa beautiful advertisement for the Hawaii tourist in- dustry. So we take that first fish, but how about the second and subsequent fish? The skipper and crew ask the angler if it is just another fish as far as he is concerned or does he care to have the fish mounted. This may be a little expensive for him so they ask if he would like to release the fish and let him fight again. The angler often agrees. Of course there is always the person who can afford to have the fish mounted, so the fish is landed. The next question relates to the type of tag we can put into the fish and how it can be found later. A tag, such as a small dart, can be put in the dorsal muscle of the fish and the time between the first and second capture will show the distance traveled, growth, and possibly conditions under which he is caught. I think we are all fairly familiar with the dart tag procedure, but the previous speaker, Mr. Squire, alluded to something which made me feel I should talk about a type of lure that is able to bring the fish to the boat without injury. Without any blood being shed, and without any interference with his swimming or breathing, the fish can be brought to the boat and kept almost stationary though you have to act quickly if you’re going to tag and release the fish. A lure was developed here in Hawaii about 3 yr ago, and has been improved since then. The concept of taking a billfish with this lure is just the reverse of a normal lure in that this lure has no hooks at all. This new lure was developed with the idea that the billfish already provides the hooks on his bill. The bill in each billfish is covered with a lot of fine teeth and when proper 15 material is applied to that bill you can hold him with the bill and bring him to the boat. As a matter of fact you hold him so well and can guide him to the boat much easier than if he is hooked in the mouth. You can use much lighter tackle to do it. I think that’s what we’re after. I understand from a discussion last night with one knowledgeable person that probably it is not the hook or the dart tag which kills the fish or shortens his lifespan, but an accumulation of lactic acid from use of oxygen during the fight. I understand that oxygen is stored in the red muscle of the fish for an emergency. Then during the fight on rod and reel if he uses it all he is at the same point as the boxer when he is hang- ing on the ropes. Possibly this is what we have to avoid when we tag a fish, that is, we have to eliminate the fight on rod and reel. We go out purposely to tag a fish, possibly with a sonic transmitter in it, and then perhaps the fish will live no longer than 48 h. I believe when the last taggings were done here with sonic transmitter, the billfish did not survive long enough to get the information that was really wanted. We had a special boat down here with all the sonic gear and it seems a shame that these fish appeared to die so soon. I suggest that the new type of lure with a transmitter could be used to tag the fish without a fight; the leader would break after the fish had taken the lure and then the chase with the listening devices would go into effect. Again I want to welcome you all to Kona on behalf of all the skippers, even those who aren’t here this morning. I know they think sport fishing has developed to a very fine point, when these scientists will spend their time and their energy to come and hold a symposium on billfish. I think sometimes we underestimate the importance of the billfish here in Kona, and it was not until the international billfish tournament, originated by Peter Fithian, that we real- ly started to make some strides and realize the impor- tance of the billfish fishery. I take my hat off to Peter Fithian who has brought this to fruition. D. Lewis Thank you very much, George. The meeting is now open to questions from the floor.’ Please identify yourself as this session is being recorded. Discussion Mr. Lewis: In my privileged position as Chairman, I would like ‘For purposes of brevity, the question and answer section has been abbreviated and in some instances paraphrased. Also, ques- tions relating to the mercury problem were similar to those raised during the special session on mercury; thus these have been omitted. to ask the first question. Why do scientists have different length criteria for billfishes?’ Dr. Robins: Generally billfishes from commercial catches or those found in the market places around the world have their bills cut off. If you are dependent upon a measurement that includes the bill then a great deal is lost unless adjustment factors can be used to deter- mine a given length. Also, the bills in two groups of billfishes grow differently. Captain George Parker (Kona) (comment): For a long time there has been some confusion on what constituted a black marlin and how it differed from a blue or striped marlin. In a black marlin the fin is stiff from the outset and you cannot lay it back to the body without breaking the joint; this is not true of the other species. Mr. Goadby (Australia) (comment): The pectoral fin of small (less than 100 pounds) east Australian black marlin can be moved, though they will not lie back completely flat as do those of the blue and striped marlins. Therefore, we must use other identifying characteristics. Mr. Palmer (Australia): During a day’s fishing a fisherman is likely to see a varying number of fish, sometimes surfacing, and sometimes encountering a strike then a miss. To what extent must the data be collected to be useful to the scientist? Mr. Squire: The amount of useful data collected depends on the circumstances and the fishery. We have obtained good data on catch per angler day by use of the card mail-in system. In some fisheries more detailed data are collected by the logbook method. What is needed is a standardized log which will ensure receipt of the kind of statistics needed for the sport fishery. Dr. J. Delohery (Australia): A question to Mr. Stroud. The Atlantic Ocean tuna agreement includes billfishes, while the Indo-Pacific and Pacific Ocean agreements do not. How can we get billfishes included into those two agreements? Mr. Stroud: You would have to amend the articles of the Convention. In case of the ICCAT, the term “and tuna-like fishes’? was included and defined so as to specifically include the billfishes. 7During the course of the Symposium sportsmen and scientists commented on the need for a standardized set of measurements for billfishes. There was a consensus agreement that the publication by L. Rivas entitled “Definitions and methods of measuring and count- ing in the billfishes (Istiophoridae, Xiphiidae)” should be reproduced in this volume, since it is currently out of print. Rivas’ paper appears as Annex 10. 16 Mr. Shomura: A clarification of a point raised by Mr. Delohery. I believe the Indo-Pacific agreement quoted by him relates to the Indo-Pacific Fisheries Council. This is only an advisory body and I believe does not currently have any management responsibilities. Mr. Lester Walls (Oahu): I would like to know if the silver marlin is a definite species or a juvenile fish. Dr. Robins: As far as we know in the Pacific Ocean we have a black marlin, a blue marlin, a striped marlin, a sailfish, and a shortbill spearfish. We have no evidence that there is any other kind of marlin-like fish in the Pacific Ocean. The fact that this “roundscale”’ spearfish or “‘hatchet”’ marlin has been uncovered in the Atlantic Ocean indicates that an eye needs to be kept open for things like this. Mr. Frank Moss (Sport Fishing Annual): Most fishing tournaments generally follow the IGFA rules. These rules are predicated on the use of hooks, so the question arises about IGFA acceptance of a hookless lure. Mr. Elwood Harry (IGFA, Ft. Lauderdale, Fla.): The IGFA through its international committee and clubs has overwhelmingly voted down the use of any entangling devices. Mr. Frank Mather (USA): Question to Peter Goadby. Is a billfish which “lights up” more apt to strike than one that does not? Mr. Goadby (Australia): It appears that fish “light up” more in warm water than they do in cool water. One angler reported that of 11 marlin he caught that had followed the bait, only 1 was seen to “light up.’”’ On the other hand in Cairns, black marlin are observed “‘lit up” from the time they are first sighted. It is my personal belief that the phenomenon is like birds exhibiting their brightest plumage during the mating season. Mr. Eugene Nakamura (USA): I would like to direct a question to some of the sports fishermen here. Fishermen in the Gulf of Mex- ico do not use artificial lures when fishing for billfish, but use fresh or frozen fish. Yet in this area (Hawaii) just about all lures are artificial. Why? Captain Parker (USA): This question comes up frequently on the charter boats. If we need live bait we catch them on the fishing grounds. Anglers are surprised that we troll for so long with artificial lures. We troll at high speeds in order to cover the maximum area. At these speeds it is difficult to maintain a frozen fish or even a freshly caught fish on the hook for any length of time. Also, we consider that the sound of the propeller and the boat’s wake, the sound that the lure makes “‘diving”’ in the water, and the trail of air bubbles created by the lure. are all very important factors. In our ex- perience, the artificial lure also has taken more of the large fish than the skipping bait or the live bait. Each area seems to have one favorite fishing method which is considered to catch the most fish. Mr. R. Johnson (Sports Illustrated): Question to Dr. Robins. Does the hookless lure ex- tend the life of the fish after it has been released? This is apart from any questions of tournament rules. Dr. Robins (USA): Iam not familiar with this particular lure. I am per- sonally convinced that the reason a lot of fish, par- ticularly blue and black marlins, die after release is the build up of lactic acid in the body after they have been ‘‘played’’ for a long time. To investigate this problem we need to use sonic lures and track the fish after release. Mr. R. Johnson: Does Captain Parker consider it possible to main- tain a charter business with customers going out with the understanding that they are to use a hookless lure? Captain Parker: Yes. Trying to build a lure that will hold the fish on the end of the line has been the desire of man ever since fishing began. May I remind you of the advent of nylon lines, the glass fiber rod, and the two-hook lure. Mr. Lewis: As there appear to be no further questions, I will ask Peter Fithian to summarize this session. Mr. Fithian: Thank you, Mr. Chairman. Dr. Robins talked about the valuable information that could be derived from good photographs and how these should be taken to avoid distortion. An identification tag showing loca- tion and time of capture, and weight and length should be visible in the photograph. He said that scientists must follow up on what they request from the sport fishermen and IJ agree that this is a very im- portant point. Mr. Goadby spoke of the active manner in which Australian oceanic game fishermen have cooperated with marine scientists, especially in tagging programs. Results from these have already suggested some interesting migration patterns for the black marlin off the east coast of Australia. Mr. Craig commented on the value of records and other data in fishing club files and how useful club yearbooks can be to the scientist. I know that Mr. Harry of the IGFA always asks clubs to send in their yearbooks and it occurs to me that this might be the simplest way for scientists to get hold of them. Mr. Stroud spoke about the activities of the Sport Fishing Institute. In particular, he summarized the 17 history of the conflicts between the Japanese commer- cial longline fishery for tunas and billfishes and the recreational fisheries in the Western Hemisphere, and how some of the problems were resolved. Finally, Mr. Stroud stated more funds were needed for game fish research and how this might be achieved. Mr. Squire indicated the type of catch and effort data scientists need from the angler. He outlined the type of surveys he makes on an annual basis for the eastern Pacific Ocean area. He also emphasized the need to know how much effort (time) is deployed which results in no catch. Captain Parker commented that he believed the charter boat captains and crew can provide a lot of good data for the scientists, both on the fish and the environment, if only they took the time to record it. He was also very concerned about the lack of revenue from the sale of the fish following the mercury problem, as this is a serious economic problem in the Hawaiian charter boat industry. There was a very in- teresting discussion of the hookless lure, which might be useful for tagging purposes as it causes no damage to the fish, apart from other conservation aspects. The general discussion ranged widely, both on points raised by the panelists and from the floor. The most important related to requests for printed infor- mation on the correct way to measure billfishes and take photographs of them for scientific purposes; detailed standardized logs for sport fishing vessels; tagging methods; international fishery agreements and the billfishes; identification of rare species like the ‘‘hatchet” marlin or “‘roundscale”’ spearfish; and the “lighting up” of billfish at certain times. There was a long and lively discussion of the merits or otherwise of the hookless lure for angling and scien- tific purposes, and the official position of the IGFA with regard to this device from the sportsmanship standpoint. Mr. Chairman, with your permission, I would like to advise this group of some resolutions which the Board of Governors of the HIBT intends to consider and present in a final form at a later date. The first, in draft form, is really addressed to NMFS, which has the authority and responsibility for matters dealing with marine sport fishing throughout the United States of America: “It has been established at the International Billfish Symposium that the successful work on billfishes to date has arisen as a by-product of other research, and whereas the billfish are generally conceded to be the ultimate fishing quarry though lit- tle is known about their biology and distribution, the Board of Governors of the HIBT resolves that the National Marine Fisheries Service be requested to focus attention on billfish research over the next 5- year period in order that a system for rational inter- national management may be realized by a cooperative effort of all those parties involved.” The second will be a very self-serving resolution in which we suggest that the Secretary of Commerce consider appointing to the advisory committee of NMES a representative from the central Pacific Ocean area. In relation to the mercury session, which we pur- posely put on in the evening and at which attendance was not as good as hoped, we are addressing a resolu- tion to the Governor of Hawaii which discusses the problems, both economical and_ philosophical, brought about by State prohibition of the sale of marlin. The Governor is interested in what goes on around this coast; although he is not a fisherman, he is interested in this tournament and serves as Honorary Chairman. We will ask him to direct the ap- propriate department to undertake studies which may lead to an economic use of the carcasses and which might meet both the economical and philosophical re- quirements. There may be some additional things, Mr. Chairman, which we will put in the form of resolutions and present to the Board of HIBT at the appropriate time. A final word, Mr. Chairman, to echo the words of Captain Parker this morning, to say what a pleasure it has been to the HIBT and myself to see you all gathered here in Hawaii. 18 Mr. Lewis: Thank you, Peter. This concludes the proceedings here this morning. However, I do not think we should adjourn before I have had the opportunity to thank Richard Shomura for putting together this meeting. He did a lot of hard work with a fine result. Thank you very much. The meeting is adjourned. Acknowledgment The editors wish to extend their thanks and deepest appreciation to the many individuals who helped to put together this Symposium. Special thanks should be accorded Dr. Robert L. Edwards, who, as Associate Director for Resource Research, NMFS, Washington, D.C., provided initial guidance and support to this Symposium. Finally, the success of the Symposium could not have been achieved without the dedication and outstanding effort extended by Mr. Robert T. B. Iversen, Regional Representative in Hawaii for the Southwest Region, NMFS. Mr. Iversen was solely responsible for handling the many arrangements that needed to be done in Hawaii to prepare for the meeting. Floyd S. Anders, Jr. Deputy Regional Director Southwest Region National Marine Fisheries Service Terminal Island, CA 90731 John L. Baxter Staff Assistant National Marine Fisheries Service Washington, DC 20235 Grant L. Beardsley, Jr. Fishery Biologist Southeast Fisheries Center National Marine Fisheries Service Miami, FL 33149 James S. Beckett Fishery Biologist Biological Station Fisheries Research Board of Canada St. Andrews, N.B., Canada Ed Biaggini, Jr. P.O. Box 167 Cayucos, CA 93430 L. W. Bird 4729 E. 3rd St. Tucson, AZ 85711 Robert Bonifacio Illustrator, Honolulu Laboratory National Marine Fisheries Service Honolulu, HI 96812 Joseph W. Brooks, Jr. Fishing Editor, Outdoor Life 2004 Prince George Road Richmond, VA 23225 John G. Casey Acting Director Narragansett Laboratory National Marine Fisheries Service Narragansett, RI 02882 Gordyn Caughlan 26 Hatfield St. Blakehurst NSW, Australia 2221 Mavis Caughlan 11 Centre St. Blakehurst NSW, Australia 2221 Paul Caughlan President, Port Hacking G.F.C. 26 Hatfield St. Blakehurst NSW, Australia 2221 Terry Caughlan President, Game Fishing Association of Australia 11 Centre St. Blakehurst NSW, Australia 2221 John R. Chibnall P.O. Box 1228 Auckland, New Zealand Sandy Colvin 910 Ala Moana Blvd. #211 Honolulu, HI 96814 John Corbin Hawaii Institute of Marine Biology University of Hawaii Kaneohe, HI 96744 ANNEX | List of Participants 19 William L. Craig Fishery Biologist/Extension Specialist Southwest Region National Marine Fisheries Service Terminal Island, CA 90731 David Cupka Fishery Biologist South Carolina Marine Resources Center Charleston, SC 29412 Donald P. de Sylva Associate Professor of Marine Science University of Miami Miami, FL 33149 H. J. Delohery International Representative 1.G.F.A. 265 Mona Vale Road St. Ives 2073, Australia James Delohery 32 Railway St. Chatswood 2067, Australia Harry L. Fierstine Biological Sciences Department California State Polytechnic College San Luis Obispo, CA 93401 Jack Fischer P.O. Box 822 Kailua-Kona, HI 96740 Peter S. Fithian Chairman, Hawaiian International Billfish Tournament Honolulu, HI 96815 Harry Foehner Outdoor Writer Unofficial Representative Texas International Fishing Tournament Drawer 2626 Harlingen, TX 78550 Peter Goadby Governor, Hawaiian International Billfish Tournament Sydney NSW, Australia Eugene M. Grabbe Manager, Hawaii State Center for Science Policy and Technology Assessment Department of Planning and Economic Development P.O. Box 2359 Honolulu, HI 96804 Doc Halliday P.O. Box 1311 Kailua-Kona, HI 96740 Elwood K. Harry Executive Vice-President International Game Fish Association Fort Lauderdale, FL Frank J. Hester Director, Honolulu Laboratory National Marine Fisheries Service Honolulu, HI 96812 David H. Hopton P.O. Box 1442 Cairns, Australia John Iaea 98-263 Aiea Kai Place Aiea, HI 96701 Robert T. B. Iversen Southwest Region Representative National Marine Fisheries Service P.O. Box 3830 Honolulu, HI 96812 John H. Izatt P.O. Box 610 Cairns, Queensland 4870, Australia J. C. Johnston 27 Wootoona Tce, St. Georges South Australia 5064 Richard W. Johnston 5575 Pia St. Honolulu, HI 96821 John W. Jolley, Jr. Florida Dept. Nat’! Resources Marine Research Laboratory P.O. Drawer “F” St. Petersburg, FL 33731 James Joseph Director, Inter-American Tropical Tuna Commission Scripps Institution of Oceanography La Jolla, CA 92037 Yoshiharu Kato President, Asuka Industries, Inc. Tokyo, Japan Arthur G. Kay No. 13 Belvedere St. Epson Auckland 3, New Zealand Hon. Shunichi Kimura Mayor, County of Hawaii Hilo, HI 96720 R. W. King P.O. Box 890 Balboa, Canal Zone W. L. Klawe Senior Scientist Inter-American Tropical Tuna Commission Scripps Institution of Oceanography La Jolla, CA 92037 Hiroyo Koami President, Institute of Sea Sphere Kanagawa-Ken, Japan Albert C. Kolbye, Jr. Deputy Director Bureau of Foods U.S. Food and Drug Administration Washington, DC 20204 Sheila Koyama RR #1, Box 364 Holualoa, HI 96725 Ritchie Kunichika 1453 B Glen Avenue Wahiawa, HI 96786 Jeffrey M. Leis Hawaii Institute of Marine Biology University of Hawaii Kaneohe, HI 96744 Elizabeth W. Leis Hawaii Institute of Marine Biology University of Kawaii Kaneohe, HI 96744 Dudley C. Lewis Governor, Hawaiian International Billfish Tournament Honolulu, HI Leo Longazamina I.G.F.A. Tahiti 20 Henry Lyman Publisher, Salt Water Sportsman 10 High Street Boston, MA 02110 Bill McGee Box 826 Kealakekua, HI 96750 Richard E. Marland Interim Director Hawaii State Office of Environmental Quality Control Honolulu, HI Joaquin Arvizu Martinez Biologist, Instituto Nacional De Pesca Chiapas 121, Mexico 7 D.F. Mexico Charles O. Mather Professor of Biology Los Angeles City College Los Angeles, CA 90029 Frank J. Mather I Associate Scientist Woods Hole Oceanographic Institution Woods Hole, MA 02543 Walter M. Matsumoto Fishery Biologist Honolulu Laboratory National Marine Fisheries Service Honolulu, HI 96812 Howard E. McHealy P.O. Box 185 Kailua-Kona, HI 96740 Patricia Medvick Department of Oceanography University of Hawaii Honolulu, HI 96822 Nigel R. Merrett National Institute of Oceanography Wormley, United Kingdom John M. Miller Assistant Professor Hawaii Institute of Marine Biology University of Hawaii Kaneohe, HI 96744 Frank T. Moss Editor, Sportfishing Annual New York, NY 10036 Eugene L. Nakamura Director, Panama City Laboratory National Marine Fisheries Service Panama City, FL 32401 Izumi Nakamura Acting Director, Fisheries Research Station Kyoto University Kyoto, Japan John J. Naughton Honolulu Laboratory National Marine Fisheries Service Honolulu, HI 96812 Daphne Nielsen International Representative I.G.F.A. P.O. Box 808 Cairns N.Q., Australia 4870 Ed Nuchley 457 Puahuula PI. Kaneohe, HI 96744 George S. Paika P.O. Box 38 Kailua-Kona, HI 96740 Ernest William Palmer LG.F.A. Rep.—Australia Judge, Hawaiian International Billfish Tournament Member, Deep Sea Mining Committee of U.N. 29 Tarlton St., Somerton Park South Australia 5044 George Parker P.O. Box 38 Kailua-Kona, HI 96740 William J. Richards Fishery Biologist Southeast Fisheries Center National Marine Fisheries Service Miami, FL 33149 Vicky Lynn Ridge Research Assistant Hawaii Institute of Marine Biology University of Hawaii Box 1067 Kaneohe, HI 96744 Luis R. Rivas Fishery Biologist Panama City Laboratory National Marine Fisheries Service Panama City, FL 32401 Jim Rizzuto Kamuela, HI 96743 C. Richard Robins Professor of Marine Science University of Miami Miami, FL 33149 Catherine H. Robins University of Miami Miami, FL 33149 Philip M. Roedel Director, National Marine Fisheries Service Washington, DC 20235 [Presently Coordinator of Marine Recreation Programs for NOAA] William F. Royce, Assoc. Dir. Office of Resource Research National Marine Fisheries Service Washington, DC 20235 Michael Santerre Hawaii Institute of Marine Biology University of Hawaii Kaneohe, HI 96744 Bud Sennett Box 1104 Kailua-Kona, HI 96740 Richard S. Shomura Director, Tiburon Fisheries Laboratory National Marine Fisheries Service Tiburon, CA 94920 [Present address: Director, Honolulu Laboratory National Marine Fisheries Service Honolulu, HI 96812] Marjorie C. Siu Secretary, Honolulu Laboratory National Marine Fisheries Service Honolulu, HI 96812 Robert A. Skillman Fishery Biologist, Honolulu Laboratory National Marine Fisheries Service Honolulu, HI 96812 21 Albert C. Smith Assoc. Prof. of Biology Div. of Natural Science Univ. of Hawaii at Hilo, Hilo College P.O. Box 1357 Hilo, HI 96720 Valentin Sokolov Fishery Biologist, Instituto Nacional de Pesca Chiapas 121, Mexico 7 D.F. Mexico Michelle Rufus Spalding Kailua-Kona, HI 96740 James L. Squire, Jr. Fishery Biologist, La Jolla Laboratory National Marine Fisheries Service La Jolla, CA 92037 H. C. Stecker P.O. Box 400 Kailua-Kona, HI 96740 Richard H. Stroud Executive Vice-President Sport Fishing Institute Washington, DC 20005 Paul J. Struhsaker Fishery Biologist, Honolulu Laboratory National Marine Fisheries Service Honolulu, HI 96812 J. Thomas Stuart III Special Asst. to the Marine Affairs Coordinator, Governor’s Office State Capitol Honolulu, HI 96813 Michio Takata Director, Hawaii State Division of Fish and Game Dept. of Land and Natural Resources Honolulu, HI 96813 Curtis A. ‘““Bud’’ Thompson 75 Kailea Place Kailua, HI 96734 S. Noel Tibbo Acting Assistant Director Biological Station Fisheries Research Board of Canada St. Andrews, N.B., Canada Shoji Ueyanagi Fishery Biologist Far Seas Fisheries Research Laboratory Shimizu, Japan Dan Wallace 3015 Kiele Avenue Honolulu, HI 96815 Les Walls P.O. Box 278 Haleiwa, HI 96712 W. B. Wardily P.O. Box 326 Wahiawa, HI 96786 Paul G. Wares Fishery Biologist Tiburon Fisheries Laboratory National Marine Fisheries Service Tiburon, CA 94920 Billy Watson 868 Center San Luis Obispo, CA 93401 William Watson Hawaii Institute of Marine Biology University of Hawaii Kaneohe, HI 96744 F. Williams STOR Scripps Institution of Oceanography P.O. Box 109 La Jolla, CA 92037 [Present address: Division of Fisheries and Applied Estuarine Ecology Rosenstiel School of Marine and Atmospheric Science University of Miami 10 Rickenbacker Causeway Miami, FL 33149] Peter Wilson P.O. Box 75 Kailua-Kona, HI 96740 George A. Wooller P.O. Box 28-159 Auckland 5, New Zealand C. Yap 1136-A — 20th Avenue Honolulu, HI 96816 22 E. Yee 801 Kaheka Street Honolulu, HI 96814 Howard O. Yoshida Fishery Biologist Honolulu Laboratory National Marine Fisheries Service Honolulu, HI 96812 Richard E. Young Asst. Prof., University of Hawaii 2525 Correa Road Honolulu, HI 96822 Heeny S. H. Yuen Fishery Biologist Honolulu Laboratory National Marine Fisheries Service Honolulu, HI 96812 ANNEX 2 Welcoming Address by The Honorable Shunichi Kimura Mayor, County of Hawaii Thank you very much, Dick. This must be a very competent kind of gather- ing, because for once they got me a maile lei short enough to fit my stature. But you know I'm particularly happy to have Mr. Roedel and Dick and all of you here at this very distinguished gathering of scientists and environmen- talists and sportsmen. I do want to make a confession to all of you though, that the only knowledge that I have about fishing is that I do get seasick and by the food that I eat; I eat raw fish by the tons and I have a 10-gallon aquarium in my house and this is the extent of my abilities as far as the fisheries are concerned. But I do want to, like all of the others, extend a very warm welcome to all of you on this Island; we’re very privileged to have this kind of distinguished group of experts in the marine billfish area. However, I’m going to leave to Mr. Roedel the overview and the technical side because I know absolutely nothing about this area. But I do want to share with you some of the folks that the Island of Hawaii has in the areas of research and scientific endeavor. I have a strong feeling that if this Island is going to depend upon agriculture and the visitor industry, I suspect many of us would be leaving this Island to live in San Francisco or La Jolla or some other swinging place throughout the country; what we really want on this Island is a combination. If we want agriculture, we want agriculture plus the expertise in tropical research in the agricultural area; if we have the visitor industry, we want the visitor industry not solely for itself but because we think that we can combine a very unique destination area. For instance, in this Kona area with Peter Fithian’s imaginative leadership and the big-game fishing area, combined with the things such as Mr. Roedel and Dick and Bob are doing here on the Symposium I think creates a particularly unique and particularly exciting kind of a visitor destination area. And so we’d like to extend all of the best of resources that we have to develop that kind of scientific and research capability. As you know, NOAA already has a major facility up on Mauna Loa with the Atmospheric Research group. Up on Mauna Kea, the tallest mountain that we have, we also have the NASA people with their 85-inch telescope and the French coming in with their 150-inch telescope within a few years. In terms of geothermal kinds of research we obviously have a great ex- pertise in volcanology; we'll try to extend this and participate with the Atomic Energy people and the people in the National Science Foundation and the other agencies so that we can have major research in the area of geothermal power and energy. We have approximately about one quarter million dollars in appropriations from the State and County governments for this particular kind of energy research. And if we look at the rains that fall on these Islands we have a fairly competent area in terms of cloud physics kinds of research at the University of Hawaii Hilo Campus. And we can go on and on. What we’ve done really is take all of the natural resources that are found on this Island and tried to develop them so that we can have fairly substantial research and development kinds of facilities on this Island. As I welcome you here I'd like to also ask your support, your help, and your counsel in how to develop the fisheries kind of expertise on this Island, in terms of developing facilities, in terms of inviting you people back again when you have ad- ditional information and additional need to get together. I’ve already asked Mr. Roedel for his assistance and he’s already given me advice as to how we can go about it to try to extract field station and field facilities and possibilities of a common research station here on the corner area on the Island of Hawaii. We’re pushing for a retreat, a scientific retreat area up on the northern part of this Island, so that we can have scientists come here to do research and, of course, to have a retreat in an area where they can quietly work on their cases and their particular kinds of endeavors. So what we hope to do really on this Island, then, is to create a tremendous expertise in tropical agriculture, both in the business end and in the area of research. We also want to create a very unique visitor area, an area that’s not only wonderful in terms of recreational visits, but also in this kind of a tremendous combination of the Peter Fithians and the National Marine Fisheries Service. Of course, we want to extend our research and development abilities throughout the Island of Hawaii and make these indeed one of four major industries. But in trying to achieve all of these very lofty and great ex- pectations for this Island, we are going to need the help, the expertise, and the counsel of all of you. I hope that I can ask your help in trying to attract to these Islands various scientific conferences and symposiums and retreats because we do not have that much expertise or that much capacity in reaching all of the scientific and research groups that we need to come to this Island to hold their deliberations. So again I want to thank you very much; we’re very happy to have all of you here. It is a great privilege for all of us to have such a gathering of all of the ex- perts in the areas of billfish and marine fisheries. I hope that if there is anything that we can do to make your stay here that much more pleasant or enjoyable please do not hesitate at anytime to call upon myself. Thank you very much. 23 ANNEX 3 Opening Address by Philip M. Roedel Director, National Marine Fisheries Service National Oceanic and Atmospheric Administration U.S. Department of Commerce, Washington, DC Mr. Chairman, Mayor Kimura, distinguished guests, participants in the First International Billfish Symposium. It is a great pleasure to be with you today, for the opening of what I am sure will be a most eventful Symposium. I want first to bring you greetings from the Administrator of the National Oceanic and Atmospheric Administration, Dr. Robert M. White, who asked that I extend his best wishes to all of you. This is a particularly happy occasion for me. I have many pleasant memories of Hawaii, extending back to the Pacific Tuna Biology Conference held in Honolulu in 1961 and including the Hawaii Governor’s Conference on Central Pacific Fishery Resources in Hilo in 1966 in which, I recall, Mayor Kimura participated. There have been others as well, but these two meetings illustrate the importance attached to fishery resources both by officials of the State of Hawaii and by the Federal Government. The Symposium we are opening today is, I believe, a worthy successor to its forerunners. This is the first scientific Symposium sponsored by the National Marine Fisheries Service since its founding nearly 2 yr ago. I think it is especially ap- propriate that the subject is a group of fishes of primary concern in the United States to sport fishermen. I say this because of the origin of NMFS, which was formed in 1970 as a component of the National Oceanic and At- mospheric Administration (pursuant to Reorganization Plan No. 4 of 1970, 84 Stat. 2090). The constituent parts of the new service came primarily from the former Bureau of Commercial Fisheries in the Department of the Interior. The service also includes, however, the migratory marine game fish program of the Bureau of Sport Fisheries and Wildlife, and this gives the new organization a far different role from that of its chief predecessor. The Sym- posium helps emphasize this: The concern of NMFS for the resource as a whole, and its responsibility to all user groups, be they sportsmen, commer- cial fishermen, or someone else. The idea of an International Billfish Symposium actually dates back to the late 1960’s when Richard Shomura was stationed at our Honolulu Laboratory. He maintained his interest when he transferred to the mainland in 1970, and he organized a workshop on billfishes which was held at the Tiburon (California) Fisheries Laboratory in 1971. Final plans for the Sym- posium were developed at that workshop. The Symposium agenda is comprehensive and substantive, and I want to congratulate Mr. Shomura, who served as Chairman of the Organization Committee, and the other committee members, Messrs. Iversen, Squire, and Williams, for a job well done. I want at the same time to express my appreciation to the cosponsors (the County of Hawaii, the Hawaiian International Billfish Tournament, and the State of Hawaii) for all they have done to make this event possible, and to the Food and Agriculture Organization of the United Nations for its support. Why a symposium? There are two primary reasons. First, billfish research in most parts of the world is a by-product of other activities primarily in areas where there is an active tuna research program. Scientific study of the billfishes has thus been relatively limited. Most of what we know about the size and distribution of stocks, and effects of fishing upon them must be in- ferred from catch statistics from the fishing nations, primarily Japan. Because of this generally secondary role, communication among scientists on a worldwide basis has been something less than adequate. This Sym- posium is a step in the right direction toward meeting what we regard as an urgent need for scientists to exchange ideas and viewpoints. Second, and of equal importance, the Symposium will permit interaction, also on a worldwide basis, between scientists and sport fishermen with respect to a major high-seas fishery, something that appears to be both unique and long overdue. Let me turn now to the fishery. While man has harvested billfish since before recorded history and has taken them recreationally for many decades, the total catch has been relatively small until fairly recently. We have, since World War II, seen a marked expansion of longline fishing for hitherto relatively unexploited high-seas stocks. Before that time, billfish had been harvested lightly, primarily because they are nonschooling species scattered over wide areas, and hence were not taken efficiently before the ad- vent of longline gear. The most recent statistics published by the Food and Agriculture Organization of the United Nations show that the global commercial catch in 1970 was about 101 thousand metric tons (Table 1). Of this, about 70 thou- sand were taken in the Pacific Ocean, 20 thousand in the Atlantic Ocean, and 10 thousand in the Indian Ocean. While some 20 nations reported billfish catches in 1970, Japan continued to dominate with some two-thirds (67 thou- sand metric tons) of the total. Taiwan ranked second, with over 15 thousand. Canada, in third place, took under 5 thousand. The United States was 24 eighth, with about 700 metric tons. The U.S. commercial fishery is relatively insignificant; it is sport fishing that is the critical item in this country. The total sport fishing catch is unknown, but it unquestionably adds considerably to the total harvest. Sport fishing for billfishes takes place in many parts of the world: East Africa, Australia, American Samoa, Hawaii, California, the Pacific Ocean waters of Mexico, the Gulf of Mexico, and several areas in the Atlantic Ocean. Commercial fishing is even more widespread but it is basically a high- seas fishery. The sportsmen generally operate much closer to shore. This is not to say there is not or has not been conflict for there has, particularly off the west coast of Mexico and in the Gulf of Mexico, where the longline fishery did intrude into some prime big-game fishing grounds. The big-game anglers watched this incursion and noted the reports of increased catches of billfishes. They understandably became alarmed for the future of their sport, and indeed for the future of the resource itself. What about economics? Hawaii offers a good example of the relative magnitude of sport versus commercial fishing for billfishes in the United States. In 1968 some 35 charter boats earned an estimated $700,000 in charter fees. The commercial value of billfishes landed by the small longline fleet operating in Hawaii that year was about $225,000. In 1970, the value of com- mercial landings of billfishes was about $290,000, but in 1971 it fell to less than $150,000. In 1971, the charter boats numbered about 48, and the earn- ings from sport fishing for billfishes were about $1.3 million. Obviously in Hawaii, revenue from recreational fishing for billfishes far exceeds the economic gains from conventional commercial fishing enterprises. Similar circumstances likely prevail elsewhere. (The marinas and vessels supporting a charter fishery are also commercial enterprises, but they are not identified as commercial fishing enterprises in the usual sense cf that term.) We are thus dealing with a group of oceanic fishes prized equally by sportsmen and by commercial fishermen. They comprise a resource of un- known size, but the rapid growth of the global fishery in itself is enough to give us cause for concern. Through this Symposium, we hope to get a better fix on the present state of knowledge and where we should devote our major efforts in the next few years, if we are to understand the dynamics of these several species. Assuming we have or can soon attain sufficient knowledge of the status of the stocks to permit rational recommendations for management, what then? If analyses of available data indicate a need for reduction in fishing effort on some or all of the stocks, how does one proceed? We are faced with the need to understand some extremely complex biological systems, and with the equally difficult matter of solving political and social problems of allocation among nations and among user groups within nations. Except in the Atlantic Ocean, where billfishes are included in the frame of reference of the International Commission for the Conservation of Atlantic Tunas (ICCAT), no mechanism for international action exists. There is, of course, a Law of the Sea Conference (LOS) scheduled for Geneva in 1973. A number of preliminary meetings have been held, and as a matter of fact, a preparatory meeting is now taking place there with strong representation by knowledgeable fisheries people. On the U.S. side, industry Table 1.—World catch of billfishes by waters, 1970. Indian Species Pacific Atlantic Ocean Total noo nenennn nnn Thousands of Metric Tons-------------- Sailfish 9.1 1.0 1.1 11.2 Blue marlin 1 18.8 3.0 4.1 25.9 Black marlin ff Striped marlin 22.1 0 3.1 25.2 White marlin 0 1.0 0 1.0 Broadbill swordfish 20.4 15.7 2.2 38.3 Total 70.4 20.7 10.5 101.6 Source: FAO Fisheries Yearbook 1970 (not sportsmen) has had considerable input into the preparatory meetings, and NOAA and NMFS have had top level people on the U.S. Delegation. The present U.S. position on fisheries was articulated most forcefully by Ambassador Donald L. McKernan at last spring’s preparatory meeting held at the United Nations in New York. To quote Mr. McKernan, this position is “‘. . . based on a species approach, that is, on the principle that the management and harvesting of fisheries should be governed by the biological distribution and migration of fish stocks, rather than by arbitrary jurisdictional boundaries.”’ The position thus depends on the fact that some species are distributed along coastlines, others are principally migratory on the high seas, while still others are spawned in freshwater and migrate to the coastal areas and onto the high seas. These three categories of coastal, high seas, and anadromous stocks form the basis for the species approach to international management. Marine species in general and billfishes and tunas in particular do not respect the lines drawn in the ocean by governments about their coastlines to delineate their territorial seas or contiguous fishing zones. This is one of the reasons fisheries is probably the thorniest of all the LOS issues. The United States species approach calls for the coastal fishes, such as anchovies, cod, and hake, to be managed by the adjoining country, with that country having a preference in harvesting those stocks. If the adjoining coun- try did not catch all the harvestable surplus of a given stock, other countries could take the remainder. The anadromous species, such as salmon, would be managed throughout their migratory range by the coastal country. The high-seas species, such as tunas and billfishes, would be managed through an international arrangement, either of a regional or worldwide nature, perhaps similar to or based upon existing international conventions for conservation and management of high-seas resources. Existing conven- tions of this nature include the very successful Inter-American Tropical Tuna Commission in the eastern Pacific Ocean, and the more recently established ICCAT (which includes billfishes and to which I have already alluded). The whole question of how best to manage high-seas stocks thus remains unresolved, and we cannot hope for resolution until we know the outcome of Geneva. We can hope that a rational scheme will be forthcoming and that by the time it is effective we will be well on the road toward obtaining the scien- tific knowledge basic to its implementation. I want to turn briefly to a serious problem facing us particularly in the United States. I refer to heavy metals found in small amounts in many fishes, and for one of which, mercury, the U.S. Food and Drug Administration (FDA) has established a guideline of 0.5 parts per million. Certain fish, among them billfish and particularly swordfish, frequently exceed this tolerance. Hawaii offers a good example of the impact of mercury on fishing. Until the heavy metal problem arose in 1970, Hawaii had no difficulty in disposing of the billfish sport catch, for the fish were used as food ashore. Mercury at levels above the FDA guidelines changed this, and both sport and commercial fishermen are now faced with determining how to dispose of the catch. Because of the intense local and worldwide interest in the subject, the scientific papers bearing on it will be summarized at a special public evening session at which Dr. Albert C. Kolbye, Deputy Director, Bureau of Foods, U.S. Food and Drug Administration, will speak. 25 While this is the first time a scientific meeting has been held in concert with the Hawaiian International Billfish Tournament, it is the 14th year for the tournament. Mr. Peter Fithian, its chairman and a participant in the Symposium, is one of the founders of the tournament which has done so much to further sport fishing in Hawaii. Tournaments of this sort are becoming even more popular and more numerous. On the Pacific coast, we have the San Diego Marlin Club In- vitational Light Tackle Tournament. A swordfish tournament will be held for the first time this September near Santa Barbara, Calif. Several southern California billfish clubs stage tournaments about the tip of Baja California, which with the west coast of Mexico from Acapulco to Guaymas, has long been an internationally famous billfish area. One of the pioneer tournaments is that conducted by the Tuna Club of Avalon, the world’s oldest billfishing club. It was founded in 1898 by Dr. Charles F. Holder, the originator of the Tournament of Roses in Pasadena, Calif. The organization began as a bluefin tuna club and held its first tournament in 1899. It expanded to include striped marlin in 1903, and recorded its first swordfish on rod and reel in 1913. All along the Atlantic and Gulf coasts, major billfish tournaments are held annually: from Nantucket and Cuttyhunk, Mass.; Cape May, N.J.; Hatteras, N.C.; Cape Canaveral, Palm Beach, Miami, and Panama City, Fla.; New Orleans, La.; Galveston, Tex.; San Juan, P.R.; and the islands of Cozumel and Mujeres off Yucatan, Mexico. This does not pretend to be a complete list, but it does show the widespread popularity of these tour- naments. No such recitation would be complete without mention of the International Game Fish Association (IGFA), founded over 20 yr ago by Mr. Michael Lerner, who is today its chairman. One of the objectives of this organization is to keep world records of saltwater game fish. The IGFA has as members the competitive clubs around the world and is governed by an international com- mittee. Its contributions to marine game fishing are legendary. I want to touch on cooperative research efforts. We have for several years been conducting a cooperative tagging project off the west coast of Mexico in an effort to monitor the impact of fishing, including the Japanese longline fishery, on billfish stocks. We have expanded our studies this year to utilize the catches made during tournaments to give us additional information on stock and recruitment in the South Atlantic Ocean and Gulf of Mexico. The cooperative game fish tagging program that Mr. Frank Mather of the Woods Hole Oceanographic Institute has fathered for more than 20 yr, will be sup- ported substantially by NMFS as a part of our expanded game fish program. Information to be gained from these studies is vital to our mission of representing all U.S. fishery interests, sport and commercial, in negotiations with other high-seas fishing nations. In closing, I want to propose that this Symposium be dedicated to the memory of two men, one a scientist, one a sportsman, who did much to further our knowledge of the ocean and of fisheries: Dr. O. E. Sette and Col. John K. Howard. Mr. Chairman, Mayor Kimura, I believe we are opening a Symposium that will have a lasting value. I appreciate the opportunity to be a participant. Aloha and mahalo. Address by Michio Takata Director, Division of Fish and Game Mr. Chairman, it is certainly a pleasure to see such an array of scientists and sportsmen from all corners of the earth assembled here for this Sym- posium. I would like to merely add our welcome to that extended by Tom Stuart, on behalf of the Division of Fish and Game of the Department of Natural Resources. I extend my warm welcome and aloha to you all and although we are cosponsors of this Symposium, I must admit that the National Marine Fisheries Service did most of the hard work that went into organizing the Symposium. The National Marine Fisheries Service has put together a fine looking program and I look forward with you to a very in- teresting and productive 3 days of discussion and exchange of ideas and infor- mation about the billfishes. I wish you all a very pleasant visit. Mahalo. ANNEX 5 Address by J. Thomas Stuart II Special Assistant to the Marine Affairs Coordinator State of Hawaii I am happy to be representing Dr. John Craven and the Office of the Marine Affairs Coordinator here today. Increasingly we are aware of the importance of oceanic studies in the future of all nations, but especially those that border the great oceans of our planet. This week’s Symposium is a strong reflection of Hawaii’s deepening in- volvement in our total understanding of one of man’s least understood fron- tiers. Hopefully, the future will see many more such gatherings as today’s. For no matter how specific the subject area, all new findings will benefit more than a few in our continuing quest to find the solutions to problems of pollution, new food resources, better use of a// marine resources—not least of all the more effective and pleasurable use of our leisure time. Thank you. 26 ANNEX 6 Address MY Peter Fithian, Chairman Board of Governors, Hawaiian International Billfish Tournament Aloha. I cannot tell you how delighted the billfish tournament is that you are all here. I do not think that you should all stay in one room at one time because if anything happened I do not know who else would be working on the billfishes. Believe me this is very important to a lot of sportmen like myself. I am sure in this room on Saturday morning that you will get many questions and ask many questions that could throw a lot of light on a lot of subjects which I am sure are near and dear to your hearts and ours. I sincerely hope that as a result of the meetings here between scientists and sportsmen, we will be able to provide all the channels of communication which I think have been sorely lacking in this field. I have no background in science at all. I managed normally to flunk chemistry and physics annually for a number of years, but I do have some feel of how sport fisheries are organized in this part of the world. I am delighted that so many of you have come to Kona. I extend you a warm welcome to come to the pier, wearing your badge please, as it gets a little hectic down there. If there are things you want to do with the fish, please let us know so that we can make arrangements. After all we are told you do not get them every day in your laboratory. We had nine marlin as of noon today, so that means possibly we will have another half dozen before the afternoon is over. Enjoy yourself, this is one of the great fishing areas in the world and one of the very pleasantest places to be located. Aloha. ANNEX 7 Text of Cable from F. E. Popper, Assistant Director-General Department of Fisheries Food and Agriculture Organization of the United Nations Rome, Italy “FAO extends best wishes for successful symposium which will contribute greatly to improve knowledge on billfish biology and resources signed Popper Assistant Director-General (Fisheries).”” 27 ANNEX 8 Potential Health Hazards of Mercury in Fish by Albert C. Kolbye Deputy Director, Bureau of Foods and Acting Director, Office of Science, Food and Drug Administration Washington, DC At the outset, I should like to emphasize several points that I would like you to keep in mind throughout my presentation. I will be talking initially about the effects on health caused by excessive exposures to methylmercury. In the normal course of events there is very little, if any, likelihood that peo- ple living in the United States would receive exposures comparable to the Japanese villagers later described. However, it is necessary to describe what can occur in the extreme if we are to understand the present perspective on mercury as a potential health problem in the United States and why the FDA has set a guideline for mercury in fish. There is no reason for public alarm or distortion of risk by magnification beyond the true perspective, because no health crisis is imminent from mer- cury in fish. We should understand, however, that there is reason to exercise prudence and caution, hence the existence of the FDA guideline. Towards the end of my talk I will go into the guideline itself and explain some of the reasoning behind it. I would also like to emphasize that there has been no ful- ly documented instance of a U.S. resident suffering clinically evident mer- cury poisoning from exposures to mercury in fish. However, the occasional presence of subclinical brain damage from excessive exposures to mercury in fish has not been excluded, particularly in relation to children of mothers who eat unusually high amounts of fish containing substantial amounts of mer- cury in the form of methylmercury. One reason for the guideline is to protect pregnant women from inadvertently damaging their unborn children. The potential health hazards of excessive exposures to mercury in fish primarily relate to the particularly toxic form of mercury most frequently en- countered in both freshwater and pelagic fish. Methylmercury is the par- ticularly toxic organic form which, because of its biochemical characteristics, is almost totally absorbed from the human gastrointestinal tract and cir- culated through the blood to the various organs and tissues where a range of harmful effects can potentially occur. In contradistinction to either inorganic or other organic forms of mercury when ingested, methylmercury can more readily penetrate the ‘blood-brain barrier,”’ enter the brain tissue, and cause irreversible damage to brain cells. If methylmercury were easily and quickly excreted from the human body, then occasional exposures to foods containing higher than normal background levels of methylmercury would present little reason for public health concern. However, such is not the case with methylmercury. When we speak of the biological half-life of a substance, we refer to that period of time necessary before the body can rid itself of 50% of the initial amount present. The biological half-life of methylmercury in humans has been determined by observational studies on exposed humans and by direct experimentation on human volunteers with orally administered radioactively labeled methylmercury. The observational results indicate that 69-70 days and 76-83 days represent the biological half-life for red blood cells and plasma, respectively, after ingestion of fish contaminated with methylmer- cury. The biological half-life of methylmercury-203 as determined by total body measurement of the volunteers was 70-74 days. Why should we be concerned with this biological half-life of 70 days? The practical significance relates to the problem of accumulation in the body if intake exposures are significantly greater than excretion. Please note that various organs such as brain tissue may have a longer half-life than 70 days, while other tissues may have a shorter half-life, thus resulting in the average net half-life of 70 days. Our primary concern is with accumulation of methylmercury in the brain and at this point I should stress not only the adult human brain but more importantly the developing fetal brain. Methylmercury easily crosses the human placenta into the blood of the human embryo as it develops in utero. As the human embryo goes through the various stages of development before birth of the infant, its developing tissues are much more sensitive to damage from toxic substances than are adults. This is especially true for fetal brain tissue which can be exquisitely sensitive by comparison. Accumulation of methylmercury in the human body has been documented many times as to the occurrence of the phenomenon and the brain damage it has caused in humans unfortunately exposed to highly contaminated foods. Additionally, we have other information from accidents and industrial ex- posures of pesticide workers. The results of experimental exposures of test animals, including monkeys, corroborate the cause-effect relationships of methylmercury to brain damage in human adults and infants. I will try to summarize the most significant points of information for you. 28 Two episodes occurred in Japan involving fairly large numbers of people and the opportunity to perform in-depth studies. The villages of Minimata and Niigata suffered similar problems during the 1950’s and early 1960’s. Fish and shellfish in the areas contained high levels of mercury (almost en- tirely in the form of methylmercury) resulting from local pollution by in- dustrial sources. As you know, the Japanese consume more seafood in their average diet than we do. There were 121 cases of human methylmercury poisoning reported in Minimata of whom 46 died. Among the 121 patients, there were 23 infants and children who were affected with a severe cerebral palsy-like disease from 1954 to 1959. The important thing to remember here is that none of these infants and children so affected had consumed any of the contaminated seafood themselves. Most were born with the affliction not only being clinically obvious but in many cases, severe. Some of the severely afflicted have never seen, heard, spoken, or made a purposeful motion in their lives and in the figurative sense they exist as human vegetables. Others are less affected but still severely handicapped. Now comes the “hooker’’—their mothers appeared to be normal. There were no clinically ob- vious signs of poisoning among the mothers at that time, yet their bodies had acted to accumulate methylmercury which was transferred through the placenta to their own children while the children were developing embryos in the womb. An additional 47 people, 6 of whom died, were reported from the Niigata episode. I visited Japan in 1971 to perform a follow-up evaluation on the Minimata villagers and learned that more cases have been recognized than had been reported earlier, apparently due to the delayed effects of methylmercury poisoning not being recognized earlier in some of these patients. One case was of particular interest. It involved a physician who ob- viously would be more likely to recognize the early symptoms of mercury poisoning which include tremor, nervousness, and impairment of both vision and coordination. He celebrated one evening and drank too much. Instead of waking up with a hangover, he awoke the next morning with clinically ob- vious symptoms of mercury poisoning and died 10 days later from the disease. At autopsy, his brain showed advanced tissue damage with all the typical brain tissue pathologic findings of mercury poisoning. Apparently, he had been able to compensate partially for the damage in brain function. Since the onset of the disease in adults can be gradual he was able to compensate enough to live a fairly normal life until additional brain damage from high alcohol consumption tilted the delicate balance of compensation and his brain could no longer function well enough. Similar advanced brain damage has been noted to result in Scandinavia after accidental short-term industrial exposure to alkyl mercuric pesticides in which the worker involved died 20 yr later from an unrelated cause without additional mercury exposures. There have been other unfortunate human ex- periences with methylmercury poisoning dating as far back as the original laboratory workers who first synthesized the compound and as recently as the current massive poisoning outbreak in Iraq due to the wrongful diversion of methylmercury treated seed wheat by farmers into bread. The ability to compensate partially for damaged brain tissue has also been noted in Swedish studies of monkeys experimentally exposed to methylmer- cury. Some of the monkeys apparently were largely unaffected as far as their normal! patterns of brain function were concerned, while others showed gross deterioration of brain function much earlier during the course of the experi- ment even though the exposures to doses of methylmercury were similar. Generally speaking, however, once a monkey showed signs of brain damage, further deterioration was very rapid with death usually following shortly. When some monkeys showed signs of advanced damage, the Swedish in- vestigators then sacrificed several other monkeys apparently unaffected by similar exposures to methylmercury and found extensive brain damage at autopsy. Also, when monkeys apparently unaffected were allowed to live longer, symptoms then occurred with unpredictable sudden rapidity and a quick demise. Similar findings have been noted when cats and rats were studied. These were all adult animals. There are several points that these findings bring to our attention. Severe brain damage from excessive exposures to methylmercury may go undetected in some adults for a while but the damage has occurred even though the time of onset of clinically obvious symptoms may vary with the particular in- dividual. The brain damage is irreversible although partial compensation may temporarily delay onset of obvious disease. Excessive exposure to methylmercury may also contribute to early demise of brain function without being recognized unless specific examinations are performed by pathologists. Excessive exposures to other toxic substances that can damage brain tissue can produce interactive effects and potentially reduce the ability of the human body to tolerate subclinical exposures to methylmercury. Also of interest in Minimata was the observation by public health officials that a number of teenage children in the village who were born around the time of the original episode are now experiencing difficulty in coordination when they attempt to play baseball and basketball. Others have visual im- pairment and more obvious signs. It would appear that subclinical brain damage had occurred earlier in their lives, probably before they were born, but signs of brain damage were delayed and are now beginning to be seen. In Niigata, the lowest blood methylmercury level associated with toxic symptoms was 0.2 ppm. This level has been exceeded by certain Swedish fishermen eating freshwater pike from streams contaminated by mercury effluents from pulp-paper operations. So far, they have not shown any ob- vious symptoms but further investigation is indicated and we hope autopsies are obtainable in the future. However, the blood level at 0.2 ppm mercury has been made the reference point that both Swedish and American health authorities use as the threshold of toxicity. Using the biologic half-life data to perform steady-state calculations, it has been determined that a daily intake not to exceed 0.3 mg would permit a 70-kg (150-pound) individual to remain at or below a blood 29 level of 0.2 ppm. Both the Swedes and the Americans determined that a 10- fold safety factor was necessary and appropriate to protect individuals with unusual susceptibilities and infants from subclinic brain damage. Accordingly, to maintain blood methylmercury levels at or below 0.02 ppm, average total dietary intake of methylmercury should not exceed 30, g per day. This permits an individual to eat 60 g of fish at maximum permis- sible mercury levels (approximately 0.5 ppm) each day over a long period of time, without invading the safety factor and accumulating methylmercury in the body such that blood levels would exceed 0.02 ppm. We know that Americans eat less fish than do the Japanese, consequently since the average serving of fish in America approximates 210 g, which is a little less than 12 pound, this means that two meals of fish at guideline would use up 1 week’s “tation” of methylmercury (additional exposure to inorganic mercury). Or said another way, one meal of swordfish with average mercury content at 1 ppm uses up a week’s ration of methylmercury. Fortunately, most fish from both fresh and salt waters are well below guideline. Since many people who eat fish eat several meals per week, especially ‘‘weight-watching’’ women during their child-bearing years, the FDA guideline exists to protect people who like to eat fish from the potential hazards of accumulating excessive methylmercury in their bodies, and especially to protect children from in utero exposures to methylmercury that could cause clinical or subclinical brain damage. ANNEX 9 Status of Mercury Studies in Hawaii NY, Richard A. Marland Interim Director Office of Environmental Quality Control The State of Hawaii became concerned with the methylmercury in fish products in the month of April last year. By May of last year we had con- ducted sufficient analyses under the auspices of the State Department of Health to show that the average total mercury content of marlin entering the market in Hawaii was just over 4 ppm. These results were corroborated by the laboratory which Ms. Shultz represents here, the Pesticide Study Laboratory. At that point we asked the fishing industry of Hawaii to withhold sale of the blue marlin on a voluntary basis. This has been done ever since the request was made. It was only fair that having had this kind of cooperation from the fishing industry, the State of Hawaii should exert all possible efforts to establish whether removal of this species from the market was justified or to establish the conditions under which it could be sold. The Pesticide Laboratory of the University has been conducting analyses to determine the extent to which methylmercury is present as part of the total mercury value. There are two other efforts now going on, sponsored by the State. One of them is of such size and importance that we have requested funding from the National Science Foundation. We have not yet had an affirmative response, but this would be a 3-yr study at a cost of over $500,000. It will include the evaluation of some 9,000 people in Hawaii who are known to have a fish- eating habit. You’ve heard Dr. Kolbye point out that one serving of fish on the order of 7 ounces per week at 1 ppm gives you a full week’s quota of methylmercury. If you’re talking about a fish of 4 ppm, you get down to something under 2 ounces a week. It is not unusual for people of Japanese ancestry in Hawaii to eat a third of a kilogram of fish a day. On this basis it becomes very important that the fish being consumed to that extent does in- deed contain the lowest possible levels of organic mercury. So the study of these 9,000 people of Japanese ancestry would be conducted as an historical study to determine if there is any evidence in their medical history of an effect of mercury poisoning. There would also be another study of some 300 people of Japanese ancestry. This 3-yr study will involve a very careful monitoring of the diet of these people, examination of their medical history, and observations made by physicians. The participants would all be residents of Lanai; they are already being studied for medical deficiencies. This study, which is an extensive study planned for 3 years’ duration, has not yet been started because the cost of the project cannot be met at the local level. Recognizing that we might not be able to get a human epidemiological study mounted immediately, the University of Hawaii, Department of Animal Sciences, started a program of research in the winter in which they used swine as an experimental animal. Swine, in this case, is an excellent animal because the metabolic system of swine is almost identical to that of human beings. There are some preliminary data available now from this swine-feeding experiment. Substantially there were five groups of swine, one on a control ration of feed, another on normal feed plus 1 pound of raw fish a day, and three experimental groups in which this 1 pound of fish had added mercury of 0.5 ppm, 5.0 ppm, or 50 ppm. These pigs were again subdivided because of the interesting results coming from Ms. Shultz’s work so that we had half of them on organic mercury and half of them on inorganic mercury. Not too surprisingly, of those pigs that were receiving 50 ppm of organic mer- cury, or methylmercury, none lived past 26 days. They were the only pigs on trial that died during the experiment. Pigs that were fed 50 ppm of inorganic mercury showed liver damage and lymph node damage, and as yet we have not conducted the pathological examination of these tissues so we do not know if there was further damage. Pigs that were fed 5 ppm of organic mer- cury in marlin appeared perfectly normal. Upon slaughter, hemorrhage on the periphery of the lymph nodes was noted, the lymph nodes were enlarged, and the livers had developed fatty tissue above them. There seemed, therefore, to be some gross pathology in the pigs that were fed marlin with 5 ppm of organic mercury. Pigs fed 5 ppm of inorganic mercury showed no symptoms or any type of pathology other than perfectly normal growth. Those that were fed the lowest level were perfectly normal, even in the case of 0.5 ppm organic mercury. The reason for selecting these levels, of course, is to establish, as Dr. Kolbye has pointed out, the validity of a 10-fold safety fac- tor. Dr. Kolbye will be pleased to hear that from each of these trials two of the females are being retained for breeding purposes and they will be studied for three generations to see whether or not there is a placental transfer of mer- cury to the offspring. These experiments, we hope, will lead to some type of recognition of the hazard of mercury. We hope the human epidemiology ex- periment will lead to some type of recognition of the risk, these data again to form a base upon which decisions can be made. We wish that we could say at this time that the data are sufficient to make decisions; they are not. We don’t know whether there will be sufficient data. We hope, of course, it will be soon. 30 ANNEX 10 Definitions and Methods of Measuring and Counting in the Billfishes (Istiophoridae, Xiphiidae)'’? by Luis Rene Rivas Abstract The need for definition and standardization of methods of measuring and counting in ichthyology is discussed, with special reference to billfishes. A series of measurements and counts for the latter group is proposed and methods and definitions for each are given. The body length is discussed in more detail in connection with its importance as a base length and attention is called to the need for dissection in order to ascertain accurately the number of spines in the first dorsal and first anal fins. Introduction The need for accurate definition and standardization in the use of biometric and meristic characters in systematic ichthyology has long been recognized (Ricker and Merriman, 1945). It is obvious that with the exception of truly self-explanatory characters, most measurements and counts must be defined in order to enable other workers to interpret the data. The need for standardization arises from the fact that in most cases, different methods (as applied to a given group), no matter how well defined, cannot be equalized for comparative purposes. Owing to the high precision required, lack of definition and standardiza- tion of methods becomes quite a problem in the study of closely related species or infraspecific categories, and especially in the biometric analysis of populations where several independent workers using different methods may be working on the same group. Furthermore, the marked differences in struc- ture existing among certain families of fishes usually prevent the application of a method to groups other than the one for which it was designed. In recent years, the increasing interest in the biometric analysis of pop- ulations of tunas by various independent workers, has brought about the necessity to define and standardize the methods used in measuring and count- ing. The various methods which have been proposed are essentially in agree- ment (Godsil and Byers, 1944:125-129; Marr and Schaefer, 1949; Rivas, 1955) and have been successfully adopted by practically all workers in the field. Also recently, new interest has developed in the taxonomy and population analysis of the sailfishes, spearfishes, marlins (Istiophoridae) and broadbill swordfish (Xiphiidae), a most confused group collectively known as “pillfishes.” As far as can be ascertained, no formal methods of measuring and counting have ever been proposed for the billfishes. A survey of the literature shows that most of the methods used vary among the different workers and that lack of definitions renders the measurements and counts difficult or impos- sible to interpret. In addition, certain methods of measuring and counting employed in the past appear to be unsatisfactory and have resulted in questionable taxonomic interpretations. For reasons already indicated above, the methods employed in the tunas cannot be applied to the billfishes. It is the purpose of the present paper to propose a series of measurements and counts for the latter group, based on previous field and laboratory experience as a result of studies conducted un- der sponsorship of the Charles F. Johnson Foundation. New characters not previously used in connection with billfishes are also included. All the measurements described (excepting body girth) are straight-line distances and are made in metric units to the nearest millimeter, with slide calipers or dividers according to the size of the fish and the distance to be measured. (See also Godsil and Byers, 1944:125, and Marr and Schaefer, 1949:241, 242). In large fish, long measurements beyond the range encom- passed by the larger calipers may be made with a steel tape graduated in metric units. For this purpose sliding metal or wooden arms similar to those used in the calipers should be attached to the tape, taking care that the tape Terains straight during the measurement, with the arms perpendicular to it. As already pointed out by Morrow (1952:53, 54), measurements taken with a tape alone are not satisfactory, since a straight line distance can seldom be obtained. Also, in order to avoid error in the longitudinal measurements, the axis of the body should be maintained as straight as possible. This may be ac- complished by placing the specimen on a flat surface and properly propping up the head, the caudal peduncle and the caudal fin. Although it is conven- tional in ichthyology to use the left side of the fish for the lateral ‘Contribution No. 149 from the Marine Laboratory, University of Miami. This consti- tutes a technical report to the Charles F. Johnson Foundation. 7From Bulletin of Marine Science of the Gulf and Caribbean 6(1):18-27, 1956. Reprinted with permission of editor. 31 measurements, the best, or either side should be selected, according to the condition of the part to be measured. The jaws should be tied closed, es- pecially in connection with measurements involving the tip of the mandible as a point of reference. The numbers in the text for each measurement correspond to the numbers in the figure. Measurements 1.—Body length.—A survey of the literature shows a great deal of inconsistency as to the selection of a body length in billfishes and lack of definition whereby the points of reference of this measurement can be ac- curately established. With very few exceptions, the instrument employed is not mentioned and there is no statement as to whether or not the measure- ment follows the curvature of the body (tape) or constitutes a straight-line distance (calipers or dividers). It must be emphasized that since most, or all, other (relative) body measurements are referred to the body length as a base length, regardless. of the method used in expressing proportions (ratios, regressions, etc.), this character must be defined with great care. It is obvious that if the base length is in error, all body proportions will also be in error regardless of how ac- curately the body parts may have been measured. The ‘‘standard length” or ‘“‘body length” for billfishes as used by most workers in the past does not seem to be satisfactory for various reasons. There has been agreement in the selection of the anterior end-point (tip of bill) but the posterior end point is variously interpreted as “.. . tail base” or“... mid-point of the peduncle . . .”” (Conrad and LaMonte, 1937, table 1 and p. 209); or ‘‘. .. the midpoint of the shallowest vertical diameter of the caudal peduncle,” (Gregory and Conrad, 1939:444), etc. Other workers offer no definitions or simply refer to “standard length” (deBuen, 1950:171) without further comment. Despite lack of absolute standardization (Ricker and Merriman, 1945), most ichthyologists agree in that ‘“‘standard length” is the straight line measurement taken between the tip of the snout and the middle of the caudal base, where the middle caudal ray joins the last (hypural) vertebra. In the billfishes, however, the middle of the caudal base cannot be determined without involved dissection, and the structure of the hypural vertebra and the caudal fin do not permit the determination of an accurate point of reference. Even after performing dissection, the point cannot be estimated from external form. For obvious reasons, the middle point on the posterior margin of the middle caudal rays (crotch of tail) constitutes a much better point of reference from the point of view of accuracy and convenience. In ad- dition, the median caudal rays in billfishes are well protected by the upper and lower lobes of the fin, and are very seldom damaged. As to the anterior point of reference, the tip, or a considerable portion of the distal end of the bill is frequently broken off, or the bill itself may be malformed and not attain its true length. For this reason, many otherwise valuable specimens have to be discarded or an inaccurate body length will result if the tip of the bill is used for the anterior point of reference. The man- dible, on the other hand, is well protected by the bill and its tip is very seldom broken off or malformed. In the light of the above discussion, it is therefore proposed that the body length in billfishes be measured between the tip of the mandible (with the jaws closed) and the middle point on the posterior margin of the middle caudal rays. 2.—Body girth.—Measured with a tape on one side of the body following its curvature from the uppermost point on the edge of the dorsal groove, vertical- ly to the edge of the pelvic groove (midline of belly in the swordfish); the resulting figure is then multiplied by two. This character, when expressed as a proportion of the base length, serves as a good indicator of the degree of robustness of the body. 3.—First predorsal length.—Measured from the tip of the mandible to the origin of the first dorsal fin. The latter point is the intersection of the anterior margin of the fin with the contour of the back when the fin is held erect. 4.—Second predorsal length.—Measured from the tip of the mandible to the origin (as defined above) of the second dorsal fin. The origin of the second dorsal is not as clearly defined as that of the first, and the point must be es- timated as accurately as possible. Since this is a long measurement, the error, if any, is negligible. 5.—Prepectoral length.—Measured from the tip of the mandible to the origin of the pectoral fin. The origin of the pectoral fin is the intersection of its anterior basal margin with the side of the body, when the fin is held erect. Figure 1.—Lateral and ventral views of a marlin, showing location of measurements. The numbers correspond to the numbers in the text. 6.—Prepelvic length.—Measured from the tip of the mandible to the origin of the pelvic fin. The latter point is the intersection of the anterior basal margin of the pelvic fin with the belly when the fin is held erect. 7.—First preanal length.—Measured from the tip of the mandible to the origin of the first anal fin. The latter point is determined in the same manner as the origin of the first dorsel fin (See above). 8.—Secoad preanal length.—Measured from the tip of the mandible to the origin of the second anal fin. The latter point is determined in the same man- ner as the origin of the second dorsal fin (See above). 9.—Origin of first dorsal to origin of pectoral.—This character is self- explanatory according to descriptions of these fin origins as given above (See first predorsal length and prepectoral length). 10.—Origin of first dorsal to origin of pelvic.—This character is self- explanatory according to descriptions of these fin origins as given above (See first predorsal length and prepelvic length). It constitutes a good indicator of the anterior depth of the body. 11.—Origin of second dorsal to origin of second anal.—The character is self-explanatory according to descriptions of these fin origins as given above (See second predorsal length and second preanal length). It constitutes a good indicator of the posterior depth of the body. 12.— Origin of pelvic to vent.—Measured from the origin of the pelvic fin (See prepelvic length) to the anterior border of the anus. 13.—Origin of pelvic to nape.—Measured from the origin of the pelvic fin (See prepelvic length) to the nearest point on the midline of the nape. This character gives good quantitative expression of the “hump”’ associated with ontogenetic stages of certain species. 14.—Greatest depth of body.—This character is self-explanatory. Its points of reference correspond with those for body girth as described above. 15.—Depth of body at origin of first dorsal_—Measured from the origin of the first dorsal (See first predorsal length), vertically to the midline of the isthmus, not including the branchiostegal membrane if it extends to the latter point. This character is a good indicator of the posterior depth of the head and may be used in connection with origin of pelvic to nape, to obtain a quantitative interpretation of the magnitude of the “hump.” 32 16.—Depth of body at origin of first anal.—Measured from the origin of the first anal fin (See first preanal length), vertically to the edge of the dorsal groove. This character is a good indicator of the middle depth of the body. 17.—Least depth of caudal peduncle.—Measured at the precaudal transverse grooves. 18.—Width of body at origin of pectorals.—Measured between the origins of both pectoral fins (See prepectoral length). This character is a good in- dicator of the anterior width of the body and may be more accurately and conveniently obtained with the fish hanging by the tail. 19.—Width of body at origin of first anal.—Measured at the widest point on the vertical from the origin of the first anal fin. This character is a good in- dicator of the middle width of the body and may be more accurately and con- veniently obtained with the fish hanging from the tail. 20.—Width of body at origin of second anal.—Measured according to the same procedure described for the above character. This character is a good indicator of the posterior width of the body. 21.— Width of caudal peduncle at keel.—Measured between the outermost point on the edge of each caudal keel (swordfish). Upper caudal keels in sailfish, spearfish and marlin. 22.—Length of upper caudal keel.—Measured between the points where the keel merges with the caudal peduncle anteriorly and with the caudal fin posteriorly. These points, although not well defined, may be estimated fairly accurately. Same procedure for single keel of swordfish. 23.—Length of lower caudal keel.—Measured according to the same procedure described above for the upper caudal keel. 24.—Head length.—Measured from the tip of the mandible to the most distant point on the margin of the opercle. 25.—Snout length.—Measured from the tip of the mandible to the most anterior point on the fleshy margin of the orbit. 26.—Bill length.—Measured from its tip to the most anterior point on the fleshy margin of the orbit. 27.—Preopercular length.—Measured from the tip of the mandible to the most distant point on the margin of the preopercle. 28.—Maxillary length.—Measured from the tip of mandible to the posterior end of the maxillary. 29.—Orbit diameter.—Measured as a horizontal distance from the most anterior point on the fleshy margin of the orbit. 30.—Iris diameter.—Measured as a horizontal distance from the most anterior point on the margin of the (ossified) sclera. 31.—Jnterorbital width.—Measured as the shortest distance between the uppermost point on the fleshy margin of the orbits. 32.—Tip of mandible to tip of bill_—This character is self-explanatory. Care must be taken that the jaws are well closed. 33.—Depth of bill.—Measured on the vertical passing through the tip of the mandible. 34.—Width of bill—Measured on the vertical passing through the tip of the mandible. 35.— Origin of first dorsal to edge of fin.—Measured from the origin of the first dorsal fin (See first predorsal length) to the nearest tip (on dorsal edge) of a dorsal spine. This measurement is connection with the anterior height of the fin (see below) gives a good quantitative interpretation of the magnitude of the anterior dorsal lobe. 36.—Length of second dorsal base.—Measured from the origin of the sec- ond dorsal fin (See second predorsal length) to the end of the fin base. The latter point is the intersection of the posterior basal margin of the last ray with the back. 37.—Length of first anal base.—Measured from the origin of the first ana! fin (See first preanal length) to the end of the anal groove. To the last (very short) discernible spine in the swordfish. 38.—Length of second anal base.—Measured according to the same procedure described above for the length of the second dorsal base. 39.—Anterior height of first dorsal.—Measured from the origin of the first dorsal fin (See first predorsal length) to the tip of the lobe. 40.—Length of middle dorsal spine.—The 25th dorsal spine measured (erect) from its intersection with the dorsal groove to its tip. This character is a good quantitative indicator of the ontogenetic changes in height undergone by the first dorsal fin. 41.—Anterior height of second dorsal.—Measured from the origin of the sec- ond dorsal fin (See second predorsal length) to the tip of its anterior lobe. 42.—Height of first anal.—Measured according to the same procedure described above for the anterior height of first dorsal. 43.—Anterior height of second anal.—Measured according to the same procedure described above for the anterior height of second dorsal. 44.—Length of pectoral.—Measured from the origin of the pectoral fin (See prepectoral length) to its tip, with the anterior basal margin of the fin perpen- dicular to the body. 45.—Length of pelvic.—Measured according to the same procedure described above for the length of the pectoral. The fin should be held straight and stretched to its full length. 46.—Length of. second dorsal.—Measured from the origin of the second dorsal fin (See second predorsal length) to the tip of the last (suctorial) ray held straight and against the middorsal line of the back. 47.—Length of second anal.—Measured according to the same procedure described above for the length of second dorsal. 48.—Length of upper caudal lobe.—Measured from the posterior end of the upper caudal keel to the tip of the upper caudal fin lobe. 49.—Length of lower caudal lobe.—Measured according to the same procedure described above for the length of upper caudal lobe, but using the end of the lower keel as point of reference. 50.—Caudal spread.—Measured between the tips of the caudal fin lobes. 51.—Caudal angle.—Measured by joining three points of reference represented by the tips of the caudal fin lobes and the middle point on the posterior margin of the middle caudal ray. This character is a good quan- titative indicator of the change of angulation and concavity of the caudal fin among species and ontogenetically within a species. Counts 1.—Dorsal spines.—The number of dorsal spines has not been widely used as a taxonomic character in billfishes and there is reason to believe that most of the few counts reported in the literature are not accurate. Careful inspection of the anterior part of the dorsal fin will show that the first two or three spines are very close together, and therefore difficult or im- possible to count without dissection. Very often the first and even the second 33 spine is extremely short. They are easily missed if the skin covering is not peeled off to the base of the fin and the spines separated with the point of the knife. Posteriorly, and especially in adult marlins, the dorsal spines gradually decrease in length and become very short or obsolete as the second dorsal fin is approached. This condition appears to be correlated with growth, since in the post-larval and juvenile stages of billfishes (Beebe, 1941; Arata, 1954) the first dorsal fin is continuous with the second, but in the young adult stages a gap appears externally between these two fins. This gap becomes progressive- ly longer as the fish becomes older and is quite extensive in very large specimens. Dorsal spine counts in billfishes without consideration of the above facts, would be inaccurate and lead to false taxonomic interpretations, when samples of widely differing age groups are compared. Dissection of the anterior part of the fin obviously should always be made, and posteriorly, attention should be paid to the magnitude of the gap and the resulting degree of external discontinuity between the first and second dorsal fins. If the dis- tance between the last dorsal spine and the origin of the second dorsal fin is about equal to or somewhat greater than the distance between the last dorsal spine and the preceding one, no obsolete spines are then present. It is recommended that if the gap is of a magnitude indicating the existence of one or more obsolete spines the dorsal spine count be followed by the sign plus (+). 2.—Dorsal rays.—All rays are counted. In this fin the rays are easily made out without dissection. 3.—Anal spines.—Counted according to the same procedure described above for the dorsal spines. The discussion given above in connection with the dorsal spines also applies to the anal spines. 4.—Anal rays.—Same procedure as described above for the dorsal rays. 5.—Pectoral rays.—All rays are counted. Although all rays are made out in this fin without dissection, care must be taken that the posterior part of the fin is well spread out so that the very small posterior rays are not missed. References ARATA,G. F., JR. 1954. A contribution to the life history of the swordfish, Xiphias glad- ius Linnaeus, from the south Atlantic coast of the United States and the Gulf of Mexico. Bull. Mar. Sci. Gulf and Caribbean, 4 (3):183-243, figs. 1-19. BEEBE, W. 1941. A study of young sailfish (Istiophorus). Zoologica, N.Y., 26(20): 209-227, figs. 1-9, pls. 1-5. BUEN, F. DE 1950. Contribuciones a la Ictiologia, II. La familia Istiophoridae y de- scripcion de una especie uruguaya (Makaira perezi de Buen). Publ. Cient. S.O.Y.P. Montevideo, (5):163-178, figs. 1-4. CONRAD, G. M. andF, LAMONTE 1937. Observations on the body form of the blue marlin (Makaira nigri- cans ampla, Poey). Bull. Amer. Mus. nat. Hist., 74 (4):207-220. GODSIL, H. C. andR. D. BYERS 1944. A systematic study of the Pacific tunas. California Div. Fish and Game, Fish Bul!. (60):1-131, figs. 1-76. GREGORY, W. K. andG. M. CONRAD 1939. Body-forms of the Black marlin (Makaira nigricans marlina) and Striped marlin (Makaira mitsukurii) of New Zealand and Australia. Bull. Amer. Mus. nat. Hist., 76 (8):443-456, figs. 1-2, pls. 3-6. MarR, J. C. andM. B. SCHAEFER 1949. Definitions of body dimensions used in describing tunas. Fish. Bull. U.S., 51 (47):241-244, fig. 1. Morrow, J. E., JR. 1952. Allometric growth in the striped marlin, Makaira mitsukuri, from New Zealand, Pacif. Sci., 6 (1):53-58. RICKER, W. E. and D. MERRIMAN 1945. On the methods of measuring fish. Copeia, (4):184-191. Rivas, L. R. 1955. A comparison between giant bluefin tuna (Thunnus thynnus) from the Straits of Florida and the Gulf of Maine, with reference to mi- gration and population identity. Proc. Gulf & Carib. Fish. Inst., 1954 (1955):133-149, fig. 1. t U.S. GOVERNMENT PRINTING OFFICE: 1975—698- 164/23 REGION I0 4 Se = 648. Weight loss of pond-raised channel catfish (Jctalurus punctatus) during holding in processing plant vats. By Donald C. Greenland and Robert L. Gill. 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 (Euthynnus pelamis) in the eastern tropical Pacific. By Maurice Blackburn and Michael Laurs. January 1972, iii + 16 pp., 7 figs., 3 tables. For sale by 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 (Scomberomorus maculatus) during frozen storage. By Robert N. Farragut. February 1972, iv + 12 pp., 6 figs., 12 tables. For sale by the Superintendent of Decuments, U.S. Government Printing Office, Washington, D.C. 20402. 651. The effect of premortem stress, holding temperatures, and freezing 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 Michigan. By James E. Ellis. March 1972, iv + 10 pp., 11 figs., 4 tables. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402. 654. An electric detector system for recovering internally tagged menhaden, genus Brevoortia. By R. O. Parker, Jr. February 1972, iii + 7 pp., 3 figs., 1 appendix table. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402. 655. 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. 656. The calico scallop, Argopecten gibbus. By Donald M. Allen and T. J. Costello. 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 + 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. Quast and Elizabeth L. Hall. July 1972, iv + 47 pp. For sale by the Superinten- dent of Documents, U.S. Government Printing Office, Washington, D.C. 20402. 659. The Southeast Fisheries Center bionumeric code. Part I: Fishes. By Harvey R. Bullis, Jr., Richard B. Roe, and Judith C. Gatlin. July 1972, xl + 95 pp., 2 figs. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. . A freshwater fish electro-motivator (FFEM)-its characteristics and operation. By James E. Ellis and Charles C. Hoopes. November 1972, iii + 11 pp., 9 figs. . A review of the literature on the development of skipjack tuna fisheries in the cen- 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- ice, Washington, D.C. 20402. A 662. Seasonal distribution of tunas and billfishes 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 1967. By Kenneth D. Waldron. December 1972, iii + 16 pp., 2 figs., 1 table, 4 appendix tables. For sale by the Superintendent of Documents, U.S. Government Print- ing Office, Washington, D.C. 20402. 664. Tagging and tag-recovery experiments with Atlantic menhaden, Brevoortia tyran- nus. By Richard L. Kroger and Robert L. Dryfoos. December 1972, iv + 11 pp., 4 figs., 12 tables. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402. ts 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, D.C. 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, D.C. 20402. 667. An analysis of the commercial lobster (Homarus americanus) fishery along the coast of Maine, August 1966 through December 1970. By James C. Thomas. June 1973, v + 57 pp., 18 figs., 11 tables. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 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, D.C. 20402. 669. Subpoint prediction for direct readout meteorological satellites. By L. E. Eber. August 1973, iii + 7 pp., 2 figs., 1 table. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402. 670. Unharvested fishes in the U.S. commercial fishery of western Lake Erie in 1969. By Harry D. Van Meter. July 1973, iii + 11 pp., 6 figs., 6 tables. For sale by the Superinten- dent of Documents, U.S. Government Printing Office, Washington, D.C. 20402. 671. Coastal upwelling indices, west coast of North America, 1946-71. By Andrew Bakun. June 1973, iv + 103 pp., 6 figs., 3 tables, 45 appendix figs. For sale by the Superintendent of Documents, U.S. Government Printing Office, 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 Documents, U.S. Government Printing Of- fice, Washington, D.C. 20402. 673. Abundance and distribution of inshore benthic fauna off southwestern Long Island, N.Y. By Frank W. Steimle, Jr. and Richard B. Stone. December 1973, iii + 50 pp., 2 figs., 5 appendix tables. 674. Lake Erie bottom trawl explorations, 1962-66. By Edgar W. Bowman. January 1974, iv + 21 pp., 9 figs., 1 table, 7 appendix tables. UNITED STATES DEPARTMENT OF COMMERCE NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION NATIONAL MARINE FISHERIES SERVICE SCIENTIFIC PUBLICATIONS STAFF ROOM 450 1107 N.E. 45TH ST SEATTLE, WA 98105 OFFICIAL BUSINESS OuT! On % aperiCan r 4 @ "NN aiN2° 7776-1919 FOURTH CLASS POSTAGE AND FEES PAID U.S. DEPARTMENT OF COMMERCE COM-210 INOUAA ITRINIVIFS SORF-O/9 t 4 STATES NOAA Technical Report NMFS SSRF- 6/5 U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Marine Fisheries Service Proceedings of the International Billfish Symposium Kailua-Kona, Hawaii, 9-12 August 1972 Part 2. Review and Contributed Papers — RICHARD S. SHOMURA and FRANCIS WILLIAMS (Editors) Seattle, Wa July 1974 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 fishery 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 service 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. 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. 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 alalunga, 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 quality and yield of bay scallop meats. By N. B. Webb and F. B. Thomas. April 1971, iii + 11 pp., 9 figs., 3 tables. 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 Lower St. Paul River, Liberia, 1952-53. By George C. Miller. February 1971, iii + 13 pp., 8 figs., 7 tables. 627. Calico scallops of the Southeastern United States, 1959-69. By Robert Cummins, Jr. June 1971, iii + 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. 630. Blue crab meat. I. Preservation by freezing. July 1971, iii + 13 pp., 5 figs., 2 tables. II. 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 by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402. 633. Blueing of processed crab meat. II. Identification of some factors involved in the blue discoloration of canned crab meat Callinectes 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. Continued on inside back cover. 635. A bibliography of the blackfin tuna, Thunnus atlanticus (Lesson). By Grant v, 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. q 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. 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 by 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 + 13 pp., li 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 tables. For sale by the | Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402. 640. Annotated bibliography on the fishing industry and biology of the blue crab, Callinectes 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, Wein D.C. 20402. 4 ¥ 641. Use of threadfin shad, Dorosoma petenense, as live bait during experimental pole- | and-line fishing for skipjack tuna, Katsuwonus pelamis, 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, D.C. 20402. z | 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. 642. Atlantic menhaden Brevoortia tyrannus resource and fishery—analysis of declin By Kenneth A. Henry. August 1971, v + 32 pp., 40 figs., 5 appendix figs., 3 tables. appendix tables. For sale by the Superintendent of Documents, U.S. Government Printin, Office, Washington, D.C. 20402. 644. Inhibition of flesh browning and skin color fading in frozen fillets of yellowe: 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. 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. 7 646. 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 + ‘ pp., 2 figs., 6 tables: For sale by the Superintendent of Documents, U.S. Governme Printing Office, Washington, D.C. 20402. 647. Revised annotated list of parasites from sea mammals caught off the west coast o} 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. 20402. U.S. DEPARTMENT OF COMMERCE Frederick B. Dent, Secretary NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION Robert M. White, Administrator = 2 NATIONAL MARINE FISHERIES SERVICE MENT OF Robert W. Schoning, Director NOAA Technical Report NMFS SSRF-675 Proceedings of the International Billfish Symposium Kailua-Kona, Hawaii, 9-12 August 1972 Part 2. Review and Contributed Papers RICHARD S. SHOMURA and FRANCIS WILLIAMS (Editors) KOS x © = S <= = 2 a Seattle, Wa » = July 1974 A x 776 491° For sale by the Superintendent of Documents, U.S, Govern ment Printing Office Washington, D.C. 20402 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 REVIEW PAPERS UEYANAGI, SHOJI. A review of the world commercial fisheries for billfishes ........ DESYLVA, DONALD P. A review ofthe world sport fishery for billfishes (Istiophoridae ANC NUP MIG AG) seep ners te ceere cere eter cece nese ue etetcyamsdacereuenetc tes Sense taMave rcs aeacila cn oaE Mops lavresepon altho CONTRIBUTED PAPERS Section 1. Species Identification. FIERSTINE, HARRY L. The paleontology of billfish — The state of the art .......... NAKAMURA, IZUMI. Some aspects of the systematics and distribution of billfishes .. ROBINS, C. RICHARD. The validity and status of the roundscale spearfish, Tetrapturus REO REL cin ic eres wie cele es ee en be eee ele cele wie weal a 0 ces u so ue sia wie ee wleis ive eieie leis ee win sie ole RICHARDS, WILLIAM J. Evaluation of identification methods for young billfishes ... UEYANAGI, SHOJI. On an additional diagnostic character for the identification of bill- fish larvae with some notes on the variations in pigmentation ...............-.2-..0.04. DE SYLVA, DONALD P., and SHOJI UEYANAGI. Comparative development of At- lanticiand= Mediterranean billfishes; (Istiophondae) ase. se ence se ei ne ctl actos Section 2. Life History. DE SYLVA, DONALD P. Life history of the Atlantic blue marlin, Makaira nigricans, Wwithuspecialsneference tow amalcannwatersi ame sm a tle seers alten eycotraaeree nay street JOLLEY,JOHN W.,JR. On the biology of Florida east coast Atlantic sailfish (Istiophorus (BUGS ID TLD) | See ENS Hig ENG Nee CG OR PAD COIR fo tS. GO RS CHE ee eer ose een Ol rE ELDRIDGE, MAXWELL B., and PAUL G. WARES. Some biological observations of billfishes taken in the eastern Pacific Ocean, 1967-1970 ........... 0... ce ccc cece cece MATHER, CHARLES O. Scientific billfish investigation: present and future; Australia, INe wr/ealandw Atria einer re aay etre cess EET TERE era idea erent senaven BECKETT,JAMES S. Biology of swordfish, Xiphias gladius L., in the Northwest Atlan- LICR CCAM ee ee ec eect ee eh coe a pe ce MS Ace le oe SE TR Tt ORNS Se Sp WARES, PAUL G., aon GARY T. SAKAGAWA. Some morphometrics of billfishes fromythesEastermybachtci@ceany seresce nce coe Meee ter ee Ee one eee LENARZ, WILLIAM H., and EUGENE L. NAKAMURA. Analysis of length and weight data on three species of billfish from the Western Atlantic Ocean .............. SKILLMAN, ROBERT A., and MARIAN Y. Y. YONG. Length-weight relationships for six species of billfishes in the Central Pacific Ocean................ 0c cece eee eee SCOTT, W. B.,andS.N.TIBBO. Food and feeding habits of swordfish, (Xiphias gladius [innacus) ini theaNorthwestyAtlantici\Ocean!. 4. aay eeee ee re nee etseae tee UCHIYAMA, JAMES H., and RICHARD S. SHOMURA. Maturation and fecundity of swordfish (Xiphias gladius) from! Hawatiam watersee cs o8. ee ee a, ee slot oe IVERSEN, ROBERT T. B., and RICHARD R. KELLEY. Occurrence, morphology, and parasitism of gastric ulcers in blue marlin, Makaira nigricans, and black marlin, Makatraxindica stromplawaitrr tree eer aya te Ferre en ee ee eee Sere re ae BECKETT, JAMES S., and H.C. FREEMAN. Mercury in swordfish and other pelagic SpeciesurombmthenwestempAtianticn@ceanty- yeti eee eee cen ee eee eee SHOMURA, RICHARD S., and WILLIAM L. CRAIG. Mercury in several specie’ of billfishes taken off Hawaii and southern California iil Section 3. Distribution. ROBINS, C. RICHARD. Summer concentration of white marlin, Tetrapturus albidus, WwestottherS traitiot Gibraltar so ssc. ieeog cs is cee Se ee a ee eee 164 PENRITH, MICHAEL J., and DAVID L. CRAM. The Cape of Good Hope: A hidden AnMeTtOMDU FISHES ee save cceke. o/c axes sueteyes Sie evo) cues Seanad, oye ONE AIO cae LESION ee EC Oe 175 SQUIRE, JAMES L., JR. Catch distribution and related sea surface temperature for striped marlin (Tetrapturus audax) caught off San Diego, California................... 188 MATHER, FRANK J. III, DURBIN C. TABB, JOHN M. MASON, JR., and H. LAWRENCE CLARK. Results of sailfish tagging in the Western North Atlantic (OG SEN A arene ante rene Sr iret omic dite ton cen moo S GTM o EEE ee arito cb 66 a 194 MATHER, FRANK J. III, JOHN M. MASON, JR., and H. LAWRENCE CLARK. Migrations of white marlin and blue marlin in the Western North Atlantic @cean'— tageing results/since May; 1970.0 2. 3c ce -oeareioccne ) eee eee 211 SQUIRE, JAMES L., JR. Migration patterns of Istiophoridae in the Pacific Ocean as determined by cooperative tagging: programs®....-). ..s- 10% Figure 17.—Larval distribution and fishing grounds for striped marlin in the Pacific and Indian Oceans. quire a thorough knowledge of these fish if we are to assure their continued and rational utilization. To attain this goal, mutual cooperation between com- mercial and sport fishing interests is necessary. Finally, in closing, I would like to express my hope that this international gathering will serve to deepen the understanding between scientists and fishermen of the various nations regarding the future of the billfish resources, and will bring about cooperative effort to advance research as well as fishery endeavors to our mutual advantage. ACKNOWLEDG MENT I sincerely thank Tamio Otsu of the National _ Marine Fisheries Service, Honolulu, who helped me with the English translation and critical review of the manuscript. I am also grateful to Hiroyo Koami of the Tsukiji Fish Market Co. Ltd. who provided me with the information on value and utilization of bill- fishes. LITERATURE CITED FAO 1971. Yearbook of fishery statistics. 1970. Vol. 30. 1972. Report of the fourth session. FAO expert panel for the Ibt facilitation of tuna research. La Jolla, California, U.S.A., 8-12 November 1971. FAO Fisheries Rept., No. 118. FISHERIES AGENCY OF JAPAN, RESEARCH DIVI- SION. 1972. Annual report of effort and catch statistics by area on Japanese tuna longline fishery. 1970. KANEKO, ET AL. 1958. Archaeological researches of the Tateyama Natagiri cave. In: Report of the Archaeology Laboratory of the Waseda University, Vol. 6. KIKAWA, S., T. KOTO, C. SHINGU, and Y. NISHIKAWA 1969. Status of tuna fisheries in the Indian Ocean as of 1968. S. Series (2), Far Seas Fish. Res. Lab. 28 pp. KUME, S. In press. Tuna fisheries and their resources in the Pacific Ocean. (Submitted to the 15th IPFC session, Symposium on coastal and high seas pelagic resources.) MINISTRY OF AGRICULTURE AND FORESTRY, STATISTICS AND SURVEY DIVISION, JAPAN. 1972. Yearbook of production statistics for fisheries and aquaculture. 1970. UEYANAGL, S. 1974. On an additional diagnostic character for the identifica- tion of billfish larvae with some notes on the‘ variations in pigmentation. Jn Shomura, Richard S., and Francis Wil- liams (editors), Proceedings of the International Billfish Symposium, Kailua-Kona, Hawaii, U.S.A., 9-12 August 1972, Part 2. Review and Contributed Papers. U.S. Dep. Comm., NOAA Technical Report NMFS-675, p. 73-78. UEYANAGI, S., NISHIKAWA 1970. Distribution, spawning, and relative abundance of bill- fishes in the Atlantic Ocean. Bull. Far Seas Fish. Res. Lab., (3): 15-55. S. KIKAWA, M. UTO, and Y. REVIEW PAPERS A Review of the World Sport Fishery for Billfishes (istiophoridae and Xiphiidae)' DONALD P. DE SYLVA? ABSTRACT Sport fishing is conducted for billfishes (Istiophoridae and Xiphiidae) in nearly all warm oceans, primarily in tropical and subtropical seas. In probable order of descending catch rate, the principal species caught by anglers are sailfish, white marlin, blue marlin, striped marlin, black marlin, swordfish, and longbill spearfish; the shortbill and Mediterranean spearfishes are rarely taken by anglers. Important sport fisheries are presently concentrated from Massachusetts to North Carolina and about Bermuda, southeast- ern Florida, the northern and northeastern Gulf of Mexico, the Bahamas, the larger islands of the Caribbean, Venezuela, the eastern tropical Pacific between southern California and Chile, Hawaii, New Zealand and eastern Australia, Kenya to Cape Town, South Africa, Ivory Coast to Senegal, West Africa, and off Portugal, Spain, and Italy. In some regions maximum angling effort coincides with maximum availability of billfish, while in others, especially in the western North Atlantic, maximum angling pressure is correlated with angling tournaments which in turn relate to summer vacations of tourists and the tendency of most anglers to fish only during the day and when the weather is favorable. Angling for billfish during the ‘‘off-season’’ may well produce good results in areas which usually are heavily fished only at certain periods. New billfishing regions probably can be developed, but this requires the assistance of local governments to provide or ensure adequate sportfishing vessels, docks, bait, and, especially, qualified captains and crews. Because of the relative inefficiency of the gear used by anglers to catch billfish, it is unlikely that angling can deplete the billfish stocks, other factors such as natural environmental fluctuations, pollution, or commercial fishing being equal. There is evidence that commercial fishing in the eastern Pacific is affecting the sport catches of sailfish and striped marlin. Based on commercial catch data, the mean size of sailfish and striped marlin and their hooking rate have decreased. In the Caribbean the catch rate of blue marlin and white marlin by commercial fishermen has decreased; this phenomenon may be attributed to heavy commercial fishing pressure from longline fleets. The economic value of the billfish sport fishery is extremely high to local communities which sup- port angling activities. In spite of some aesthetic feelings which promote releasing of billfish which are not tagged, it would appear that catches by anglers could be retained for human consumption without seriously depleting the stocks, thus further contributing to local economy. Sport fishing for billfishes poses special problems because of the complexity, expense, expertise required, and lack of basic information on the fisheries and the fishermen. Possible solutions to these are discussed. Since the end of World War II, the sport fishery for billfishes (Istiophoridae and Xiphiidae) has developed markedly geographically and in effort ex- pended. Better and cheaper air travel, fast sportfish- ing boats equipped with excellent tackle and fish- finding devices, and increased leisure time in many ' Scientific Contribution No. 1695, University of Miami, Rosenstiel School of Marine and Atmosphenc Science. * Associate Professor of Marine Science, University of Miami, Rosenstiel School of Marine and Atmospheric Science, Miami, Fl. 33149. 12 countries have enabled the average man to make dreams of catching giant marlin—which he once could only read about in magazines such as Field and Stream—become a reality. The increase in size and scope of the billfish sportfishing industry, for it has become a virtual industry, has more than paral- leled the expansion of the commercial fishery for billfishes on the high seas of the world. Each in- terest is legitimate, but because both industries are seeking the same resource, including the ecologi- cally and economically related tunas, legitimate concern is expressed by each interest that his own kind of fishing may eventually be excluded. An article in the New York Times, during November, 1969, revealed a brief economic survey carried out by one of their reporters prior to the U.S. Atlantic Tuna Tournament. Tournament anglers were polled prior to the tournament concerning ex- penses incurred in catching billfish and tunas, includ- ing the money spent when fish were not caught. Perhaps not surprisingly, they reported that the av- erage cost to the angler to catcha sailfish was $4,000, a blue marlin $10,000, and a swordfish $20,000. One may argue that these figures may be too high or too low; nevertheless, they indicate the economic im- portance of the sport fishery for billfishes. It is especially noteworthy that both the commer- cial and sport fisheries are based on biological re- sources about which we know very little, nor do we understand much about the environment of bill- fishes. They spend their life cycle on the ‘‘high seas,’ where their breeding and feeding must be studied from inference, based on examination of dead specimens. We can generally only speculate on their habits and attempt to forecast what oceanographic conditions may be associated with their movements; to attempt to maintain and study a 200-kg marlin in a tank is presumably beyond the technological capabilities of even the most clever aquarists. A preliminary bibliography of the billfishes (de Sylva and Howard, MS)? contains over 2,000 refer- ences, yet even if we use the sum total of knowledge of these references, which dates back over 400 years, we really have very little comprehensive knowledge about the habits of the billfishes. We must be especially grateful to the Japanese commer- cial fishermen and scientists working with them, as well as fishermen and scientists of other countries, who have so enriched the literature with their study of thousands of billfishes from all over the world. To those billfish anglers who decry the large number of billfishes caught by Japanese longlines, the following quote from the late Colonel John K. Howard (in Howard and Ueyanagi, 1965:4) seems in order: ‘‘In the last analysis, if it were not for the extraordinary foresightedness, initiative, and organizing ability of the great Japanese fishery companies, as well as the energy, high quality of seamanship, and great tech- * de Sylva, Donald P. and John K. Howard. 1972. A prelimi- nary bibliography of billfishes (Istiophoridae, Xiphiidae, and re- lated fossil families). U.S. National Marine Fisheries Service, July, 1972, 160 pp. Mimeogr. 13 nical fishing skill of their ships’ officers and crews, there would be no catches of istiophorid fishes from all over the world to serve so usefully in this distribution study.’’ It is difficult to ascertain just how long man has intentionally fished for billfishes for sport, but such recreation is probably a.relatively recent product of our age of leisure. Billfishes have been caught for food commercially for centuries, using harpoons, longlines, traps, or nets, but it is only with the rela- tively recent appearance of multiplying reels, lami- nated bamboo poles and Fiberglas rods, and light line that man could hope to derive pleasure from fighting a billfish in a reasonably sportsmanlike manner. In the Pacific, the first billfish to be taken on hook and line was a striped marlin taken in 1903 off Ava- lon, California (Howard in Howard and Ueyanagi, 1965:10). Sport fishing for billfishes could not have been well developed at the turn of the century, for Charles F. Holder, one of the deans of early big game fishing, and founder of the Tuna Club at Ava- lon, California, in his comprehensive book “‘Big game fishes of the United States’’ (Holder, 1903), does not mention swordfish, marlin, or sailfish. It is believed, however, that Holder was also one of the pioneers in the popularization of fishing for sailfish in Florida, probably during the period from 1905 to 1910. Angling for billfish remained the sport of the very wealthy, and it was not followed by many de- votees until the 1920’s when Ernest Hemingway synonymized billfishing in the Bahamas and off Cuba with gutsy adventure stories. It was also about this time when Zane Grey became enthralled with his angling experiences with giant swordfish and marlin in the Pacific. These narratives certainly must have tingled the hearts of those thousands of snowbound northerners who vicariously sped off to sea to troll for “‘The Big One.”’ Up to the time of World War IT, billfishing, as well as tuna fishing, grew in popularity, especially off Florida, the Bahamas, and southern California. Dur- ing this time Hemingway, Tommy Gifford, Van Campen Heilner, Michael Lerner, Kip Farrington, Zane Grey, and John K. Howard were among those pursuing the ocean gamesters with relatively primi- tive fishing vessels and tackle. The war found many of the marlin.boats and their skippers tied up in antisubmarine service or Coast Guard patrols. Nevertheless, sport fishing for bill- fishes, and even marlin tournaments such as at Ocean Citv. Maryland, continued sporadically be- cause it took more than mines, torpedoes, and gas rationing to deter a true billfish angler. After the war, better and faster sportfishing vessels, electronic navigational and depth-finding gear, and greatly im- proved tackle, such as Fiberglas rods and monofila- ment line, improved the efficiency of the billfish and tuna angler and his vessels. With these additions came a new wave of wealthy and mobile anglers to explore untried areas of the world. But such men failed to hold the monopoly on new fishing grounds and big fish because, often to the dismay of estab- lished world-record holders, the “‘little man’’ with no angling experience, thanks to excellent captains, dedicated mates, and superb tackle and boats, has frequently broken the world’s record for billfish. Sport fishing for marlin, sailfish, and swordfish is no longer a rich man’s exclusive pastime: it is now within the reach of nearly anyone’s budget to spend $100 a day to be reasonably assured of at least seeing a billfish. Further the thrill of hooking a billfish and watching its acrobatics is virtually unparalleled in the excitement of sport. SPECIES CAUGHT BY ANGLERS Data on the number of different species of bill- fishes caught by anglers around the world are virtu- ally non-existent. Individual anglers and captains sometimes maintain logbooks, while tournaments may reveal how many of the different species are taken over a short time span. Probably the best estimates of relative abundance are obtained from taxidermists, because a billfish is considered a highly desirable, spectacular trophy which can be mounted as a memoir to an exciting day. Anglers apparently do not differentiate in their desire to have a large fish mounted in contrast to a small one, in spite of the cost differential, or between a sailfish and a marlin. We may thus assume that taxidermists’ records pos- sibly reflect the relative availability of different species of billfish. Invaluable data on size, locality, and date of capture are thus available for scientific studies from taxidermists’ records. Based upon such records and intuition from twenty years of working with billfish and billfish anglers, I suspect that in probable order of descend- ing importance in terms of the number caught (or released), the principal species are: sailfish, Istiophorus platypterus*; white marlin, + For the purposes of this discussion, I follow Morrow and Harbo (1969) in recognizing a single, worldwide species. Simi- larly, for the purposes of this review, I concur with our earlier 14 Tetrapturus albidus; blue marlin, Makaira_ nigri- cans; striped marlin, Tetrapturus audax; black marlin, Makaira indica; swordfish, Xiphias gladius; and longbill spearfish, Tetrapturus pflue- geri (see Robins and de Sylva, 1961 and 1963, fora discussion of recent nomenclature). The shortbill spearfish, Tetrapturus angustirostris, from the Indo-Pacific, is largely confined to the high seas. A specimen has been taken from Australia (Goadby, 1970) on hook and line, while it is occasionally taken by anglers in Hawaii (Peter Fithian, personal com- munication). In recent years, anglers fishing off southern California have become familiar with this species; William L. Craig (personal communication) reports the following verified catches by anglers: off the Coronado Islands, 4 September 1966, 5 feet, 2034 pounds; 20 miles southwest of North Coronado Island, 31 August 1968, 434 pounds; 20 miles south of Pyramid Head, San Clemente Island, 28 August 1969, 45 pounds. The Mediterranean spearfish, Tet- rapturus belone, though locally and seasonally common off Sicily, has not been reported from an- glers’ catches (de Sylva, 1973). The remaining known member of the billfish group, the roundscale spearfish, Tetrapturus georgei, from the northeastern Atlantic and west- ern Mediterranean, is apparently quite rare and, to our knowledge, has not been taken by anglers (Rob- ins, 1974a). The identity of two unidentified specimens of bill- fish has not been clarified. A juvenile specimen of about 40 mm, on loan to the author from the British Museum (Natural History), was lost in a fire in 1967. The specimen had peculiar markings on the dorsal fin which are reminiscent of those of the white marlin (de Sylva and Ueyanagi, MS). Neither the adult of T. belone nor that of T. georgei has extensive mark- ings on the dorsal fin: possibly this represents the juvenile of an undescribed species which, though rare, could enter into the sport fishery. The other unidentified billfish, from the northern Gulf of Mexico, poses special problems. A speci- men was caught by Robert Ewing off South Pass (Mississippi River; delta of Louisiana) and, while superficially resembling a white marlin, lacks the distinctive pattern of spots on the dorsal fin, and the dorsal and anal fins are not typically those from a white marlin. I have heard of two other specimens taken from the northeastern Gulf of Mexico. John findings (Robins and de Sylva, 1961) that the blue marlin rep- resents a single, circumtropical species. Rybovich (personal communication), upon examin- ing slides of this fish, indicated that Cuban and Ven- ezuelan commercial fishermen have long been famil- iar with this form which they called “‘hatchet mar- lin’? or ‘‘axe marlin,’ in allusion to the truncated dorsal lobe. This form (or species?) could enter the sport fishery in some locations; its taxonomic rela- tionships are presently under study by the author and Dr. C. Richard Robins. DISTRIBUTION OF SPORT FISHING EFFORT FOR BILLFISH Billfishes are found throughout the tropical and temperate seas of the world. With the advent of organized commercial fisheries for tuna and bill- fishes, a mass of data has accumulated on the dis- tribution of billfishes throughout the world’s oceans based largely on longline catches (see for example Howard and Ueyanagi, 1965, and references therein; Fox, 1971: Howard and Starck, 1974; Nankai Regional Fisheries Research Laboratory, 1954; 1959; Ueyanagi et al., 1970). Longline catches give some indications of the depth where billfish actually occur because baits are distributed, from many miles of floating line, from the surface to a depth of over 150 m. Billfishes are thus caught using dead baits drifted at various deeper levels, where billfishes apparently spend most of their time. Bill- fishes may be taken in the upper levels during set- ting and retrieving of the longline, when the baits are moving through the water (Fox, 1971). In con- trast, the sport fishery techniques used for billfishes (which are described subsequently) generally in- volve a bait which is trolled at the surface, which 1s not believed to be a normal part of the billfish envi- ronment. Thus, for a trolled bait to be seen by a billfish, water transparency must be good and sea conditions such that the bait is visible to the billfish. Considering the small size of the bait and the depth at which billfish normally swim, it is indeed surpris- ing that anglers catch as many fish as they do. We might say that the angler trolling a mullet at the surface will catch only a fraction of the billfish which swim 100 m beneath his boat. Thus, while from the biological standpoint the distributional charts based on longline catches show- ing when and where marlin occur are valuable to the prospective longliners, they are of less value to the angler because he is not fishing at the depths where the marlin may be actually commonest and, theoret- 15 ically, he might troll for months without ever raising a marlin from the depths. Nevertheless, the angler will certainly have a much better statistical chance of success if he fishes when and where billfish are known to occur in commercial catches. In the sub- sequent section, therefore, reference is made fre- quently, where appropriate, to geographic areas which are potentially important sport fishing centers for the various species, as well as to those which are already known to be good for billfishing. Billfish Species and their Distribution Sailfish are found throughout tropical seas, usu- ally close to large land masses. In comparison to other billfishes, sailfish are found less about islands and tend to come closer to shore into “‘green water,” in contrast to the ‘‘blue-water’’ nature of the other billfishes, possibly merely because of their relative abundance. Sailfish are not especially migratory, al- though some tagged individuals have traversed great distances. They reach a weight of over 100 kg, and are highly prized by anglers. The juveniles, espe- cially, make handsome mounted specimens. A popu- lar account on sailfishing is presented by Tinsley (1964). White marlin are found only in the Atlantic. Al- though they form dense, seasonal aggregations in coastal waters, whites occur far offshore prior to the spawning season. They tend to migrate consider- ably, and probably consist of two or more popula- tions. White marlin occur frequently in blue water, although one of the largest concentrations available to anglers is in the green, phytoplankton-rich coastal waters of Venezuela. This species, which reaches a weight of about 73 kg, is a spectacular jumper whose acrobatics are perhaps comparable only to those of the related striped marlin. Blue marlin are confined to the tropics of the world oceans, and apparently do not migrate widely. In the northern hemisphere of the Atlantic and Pacific Oceans they seem to move in a southeast to north- west direction between May and September and conversely from northwest to southeast from November to March. Blues are common near large islands and in the open sea, preferring clear blue water. The International Game Fish Association (IGFA) presently recognizes, for angling purposes, the Atlantic blue marlin and the Pacific blue marlin, though taxonomic differences may not exist. In the Atlantic, the blue marlin reaches nearly 550 kg, while in the Pacific a specimen of 820 kg was landed on hook and line off Honolulu. Striped marlin are known only from the Pacific and Indian Oceans, although there are records from off Cape Town, South Africa, from the waters of the Agulhas Current, which is geographically in the At- lantic. In the Pacific Ocean the distribution of striped marlin is horseshoeshaped, with a wide latitudinal distribution in the open spaces of the North and South Pacific Oceans. The contiguous distribution connecting these arms occurs in the tropical eastern Pacific, with the open end in the western Pacific. Striped marlin usually do not come as close to land masses as the sailfish or black marlin. Migrations are pronounced, and populations occur in the North and South Pacific Oceans. Like their relative, the white marlin of the Atlantic, striped marlin are spectacular jumpers. Striped marlin grow to about 230 kg. Black marlin are reported with authenticity only from the Pacific and Indian Oceans. However, Wise and Le Guen (1969), in their analysis of the Japanese longline records, noted that Japanese fishermen report black marlin from the Mid- Atlantic Ridge of the South Atlantic. In a more detailed analysis, Ueyanagi, et al. (1970) show black marlin to be scattered throughout the Atlantic from lat. 30°N to lat. 20°S. In the Pacific and Indian Oceans, they occur in the warmer parts of the oceans near land masses, and are relatively non- migratory. Because of their large size, they are av- idly sought by anglers. The current world record black is 709 kg. A color phase of the black marlin from Tahiti has been long known as the “‘silver mar- lin’’ because of the silvery sheen on the sides. Blue marlin from Pacific Panama frequently exhibit this silvery pattern, which may reflect local food habits or behavioral patterns. The broadbill swordfish represents the height of frustration to the angler. Locally it may be abundant but this species frequently refuses to accept an ap- parently attractive bait. It is perhaps the most widely distributed of the billfishes, yet the occur- rence of the swordfish in sport fish catches is extremely rare. Swordfishes occur throughout tem- perate seas, where they are frequently the subject of intensive commercial fisheries. The larvae are common in tropical seas. Apparently the swordfish undergoes tropical submergence, occurring at great- er depths toward the equator and surfacing toward higher latitudes. In temperate waters, anglers spot and catch swordfish close to the surface, and in the 16 tropics the longline catches disclose their presence in deeper strata. Swordfish are usually found far from land masses, though local disfiguration of bot- tom topography, combined with upwelling, brings food sources closer to them. Swordfish seldom jump, yet they are huge fish, and their scarcity in anglers’ catch records and reluctance to take a bait relegate them as a special prize. The present angler record is about 537 kg, although somewhat larger fish are reported to be occasionally captured com- mercially. The longbill spearfish is the only one of the four spearfish (sensu strictu) to be taken regularly by anglers. Although this species had been taken by anglers in the western Atlantic for years, it was recognized as distinct from other billfishes only rela- tively recently by the late Al Pflueger who, together with marine scientists, considered it to be similar to the Mediterranean spearfish. Finally, through the efforts of the late John K. Howard, Dr. C. Richard Robins of the University of Miami was able to ex- amine 27 spearfish from the Mediterranean. This study led to the conclusion that the western Atlantic form was a distinct and undescribed species, which was subsequently named 7. pfluegeri (Robins and de Sylva, 1963). This predominantly offshore species ranges from Georges Bank, Bermuda, the northern Gulf of Mexico, and from Puerto Rico to Brazil. Japanese longline records list spearfish from the Mid-Atlantic Ridge and the Northeast Atlantic to off South Africa (Ueyanagi et al., 1970), but it cannot be stated with certainty as to what species they refer, or even if there is more than one species. In any event, the longbill spearfish is found offshore, being taken only occasionally by anglers. We have data on about 75 fish taken to date, the largest being 40 kg. A summary of the biology and distribution of this species is presented by Robins (1974b). Important Geographic Regions for Sport Fishing for Billfishes North America.—The northernmost billfish con- centration in North America 1s the late summer con- centration of swordfish at Cape Breton, Nova Scotia, which supports one of the oldest of the bill- fish sport fisheries (Fig. 1). Swordfish are rela- tively common south to Montauk, Long Island, New York, where they are taken commercially and for sport. White marlin are not uncommon in late summer from Cape Cod to Montauk. Occasional sailfish and white marlin have been recorded. Figure 1.—Principal areas of sport fishing for billfishes . Middle Atlantic Bight.—This region from Mon- tauk to Hatteras, North Carolina, harbors large con- centrations of migrating white marlin during the summer. Large blue marlin are taken frequently off Hatteras, occasionally straying northward, together with sailfish. Swordfish are sufficiently common off Hatteras to support a local, commercial longline fishery, but this species is taken only rarelv by an- glers. Southeast Atlantic Coast.—White marlin, blue marlin, and sailfish are found scattered southward from Hatteras to Cape Canaveral, Florida, but they are not usually available for sport fishing because the Gulf Stream is far offshore and not easily acces- sible to sportfishing boats. From about Stuart, Florida, south of Cape Canaveral, through the Florida Keys billfishes may be quite common periodically. Sailfish may be abundant at times and blues and whites probably occur throughout the year. Most angler-caught longbill spearfish are re- ported from this region, and swordfish are not in- frequently taken, the latter catches being made usu- ally by anglers inadvertently drifting baits deep from disabled boats. Gulf of Mexico.—The eastern Gulf of Mexico supports little billfish sport fishing because of the long distance (40-80 nautical miles) to ‘“‘blue water”’ where billfishes occur, although organized activity off St. Petersburg, Florida, is beginning to pinpoint the relation between surface currents and billfish distribution. In the northeastern Gulf from around Panama City, Florida, there have been a number of sailfish, whites, and blues taken by a growing sport- fishing fleet, and swordfish are occasionally seen at the surface. Nearly all the fishing is carried out in the “Loop Current.’’ Heavy billfishing occurs off the Mississippi Delta for all species of Atlantic billfish. Swordfish have been seen there with increasing fre- quency, and a few are taken on rod and reel. The ING Texas coast, especially off Port Aransas, yields good catches of sails and whites, while farther offshore blue marlin probably occur throughout much of the year. No regular sport fishing for billfish is conducted in the Gulf between the Mexican-Texas border south- ward until Cozumel where, in the past two years, fleets of American Sportfishermen have traversed the Florida Current to partake of some very exciting fishing for sailfish and white marlin. The results of fishing suggest a catch rate per boat as high as ex- perienced anywhere in the Atlantic. Eastern Central America.—Mather (1952) re- ported sailfish, white marlin, and blue marlin widely distributed all along the Central American coast to the Gulf of Mexico at Cozumel, but no extensive fishery is known from this region. There is no reason, however, to believe that sport fishing for billfish should not be reasonably productive along parts of the Central American coast, especially in view of the heavy concentration of blue marlin re- ported there by Ueyanagi et al. (1970). Northeastern South America.—Very good angling for sailfish has been reported off Cartagena and Santa Marta, Colombia, but this effort is limited to tournaments, which frequently produce relatively large fish. Possibly the best angling anywhere for white mar- lin occurs along the coast of Venezuela off Carabal- leda, east of La Guaira. The entire coast here is excellent at least to Puerto Cabello, where blues and sails occur, and where whites are common. Spear- fish are occasionally landed along this coast. The waters from Puerto Cabello westward to Lake Maracaibo have not, to my knowledge, been ex- plored by anglers. East of Venezuela, the heavy influx of fresh water from the Orinoco and Amazon Rivers, with the as- sociated high turbidity, does not favor billfish sport fishing, although commercial fishermen do catch billfishes offshore of and beneath the relatively shal- low freshwater effluent. From Fortaleza, Brazil, to Sao Paulo, billfishing activity is limited, probably because blue water is too far offshore and outside the range of most Sportfishermen. Longliners take good catches of blue and white marlin offshore of the entire coast. Whites, sails, and blues are taken by those intrepid anglers capable of the offshore run of 150 to 200 nautical miles to the warm, blue wa- ters. Farther south, swordfish are scattered off southern Brazil and even Uruguay and Argentina, but sport fishing for them off eastern South America apparently is extremely limited. Bermuda.—Turning northward again to the west- ern tropical North Atlantic, Bermuda has been a historical focal point for big game fishing, with bill- fish species being well represented from the waters of Bermuda and the adjacent Sargasso Sea. Al- though large whites and blues are caught with regu- larity, these waters do not yield billfish in large num- bers. Mowbray (1956) showed that billfish could be taken off Bermuda by deep drift-fishing, which may well be a valuable technique in the oceanic tropics in locating billfish which penetrate the thermocline in search of food. Bahamas.—The 3,000 islands comprising the Bahamas have always lured tourists, yet the waters surrounding only a few of them have been fished for billfishes. This is undoubtedly due to the tremen- dous geographical expanse covered by these islands and the relative lack of port facilities for big-game fishing. Notable exceptions are Bimini, Cat Cay, Chub Cay, and Walker Cay, which are less than 200 island-hopping nautical miles from the mainland United States. These islands have historically pro- duced many world-record game fish, including sev- eral-score records for billfishes on various kinds of tackle. Blue marlin apparently occur throughout the year, with whites and sails being caught especially in the spring. A few spearfish are taken annually, and swordfish are seen though seldom hooked. Charts based on Japanese longline catches show heavy con- centrations of blue marlin several hundred nautical miles east of Eleuthera and Abaco Islands in late spring and summer, but the distances from even the nearest major port (i.e., Nassau) are presently too far for most anglers. Caribbean.—Cuba, the largest island of the Caribbean, and a historical producer of the blue marlin and white marlin, is presently off limits for most anglers. An annual Ernest Hemingway Tour- nament still yields good catches of white marlin ac- cording to the Cuban journal Mar y Pesca, while commercial fishermen fish deep, using drift lines, to catch the kind of swordfish and blue marlin revered in Hemingway’s *‘The Old Man and the Sea.’ From commercial catch records spearfish are apparently found scattered along the coast and in offshore wa- ters; however, they have not been reported by an- glers. Jamaica is a superb fishing area for small blues of about 70 kg, these fish being especially numerous during the fall sport fishery on the northeastern coast of Jamaica. Large blues are taken by commercial 18 drift-fishermen along the northwest, the south, and, especially, the northeast coasts of Jamaica. Sword- fish are occasionally taken by drift fishermen fishing deep off Jamaica, as well as throughout most Carib- bean waters, but these strata are not fished by sport fishermen. A few blue marlin are taken by anglers in the nearby Cayman Islands, but fishing effort is too sporadic to suggest definitive fishing areas or sea- sons. The Dominican Republic has yielded good catches of white marlin, especially about Boca de Yuma on the southeastern coast. Sailfish and, occa- sionally, blue marlin are taken there. The rest of Hispaniola, though potentially exciting for billfish, has not been explored. The north coast of Puerto Rico has long been an excellent spot for blue marlin, including a one-time world’s record of nearly 344 kg. In past years good catches of blues, plus a few whites and sails, and occasional spearfish and swordfish have been made. Presently, the sport catch seems to be attenuating, possibly in conjunction with the increasing levels of pollution in Puerto Rican waters. Over the years the habitat east of Puerto Rico, especially the Virgin Islands, has consistently pro- duced good catches of relatively large blue marlin, together with scattered catches of whites and sails. Reputedly, blue marlin of over 500 kg have been hooked and lost east of St. Thomas. There is no reason to doubt these claims, for shark-mutilated carcasses of large marlin of at least this size have been seen or brought in by fishermen fishing in waters off the large islands of Puerto Rico and Cuba. However, in view of the reports of black marlin from mid- Atlantic waters (Ueyanagi et al., 1970), the identity of these large fish is speculative. The waters of the Leeward and Windward Is- lands, from Anguilla to Grenada and Barbados, yield an occasional billfish to commercial drift- fishermen. Angling effort is presently almost nonex- istent in this region, possibly due to lack of harbor facilities or appropriate sportfishing boats. In addi- tion, billfishes, as reflected in commercial catches, do not seem especially abundant here in compari- son with other tropical western Atlantic grounds. West Coast of South America.—The angling world’s record broadbill swordfish of 537 kg was taken at Iquique in northern Chile. Although local sportfishing activity is centered in Iquique, the facilities are limited and fishing effort not extensive. Swordfish are taken commercially at least as far south as Valparaiso by harpoon (Manning, 1957); sportfishing facilities are not well developed there. Striped marlin are also very common in northern Chile and are taken by sport anglers fishing off Iquique. Black marlin and sailfish may occur when tongues of warm water penetrate from the north. Swordfish, striped marlin, and black marlin histor- ically are relatively common in Peru. Large blacks have been taken by commercial and sport fishermen working out of Cabo Blanco, but in recent years angling has attenuated in part due to an apparent lack of interest by foreign anglers and allegedly in part due to the reported offshore displacement of the Peru Current which harbors these large billfish and the complex food web upon which the large billfishes depend. Large black and striped marlin occur abundantly all along the Ecuadorian coast, outside of the Gulf of Guayaquil, between Manta and Esmeraldas, includ- ing Isla de la Plata. Recently, excellent-angling for striped marlin has been reported off La Puntilla, west of Guayaquil. Blue marlin and sailfish are common when warm currents predominate, while black and striped marlin favor cooler waters, as do the occasional swordfish hooked offshore. Sport fishing for billfish has never been adequately explored along Colombia’s west coast. Very large sailfish and black marlin are seen or hooked offshore, especially around Gorgona and Gorgonilla Islands, southwest of Buenaventura. Blue marlin are also reported here and, undoubtedly, striped marlin occur seasonally during cooler periods. Western Central America.—Billfishing is excel- lent all along Panama’s Pacific coast. Pinas Bay and the Pearl Islands are historically the headquarters for excellent billfishing in Panama waters where black, blue, and occasionally striped marlin abound. Sailfish are especially large and plentiful all along Pacific Panama. Anglers devoted to fishing with light tackle and artificial flies speak reverently of sailfishing in these waters. Some sport fishing for Pacific sailfish occurs near Puntarenas, Costa Rica. Heavy surf and swells re- duce the feasibility of launching small angling boats safely. = Off Nicaragua, black marlin and sailfish are re- ported by commercial fishermen, but the surf and swell are similar to that of the Costa Rican coast. In addition to the lack of adequate sportfishing ports and facilities, the sea conditions discourage sport fishing for billfishes. The Pacific coast of Honduras northward to Mex- ico is characterized by a shortage of large waterfront 19 cities and suitable ports. El Salvador commercial fishermen report sailfish from this coast. However, this entire region, though rich in fish and good fishing waters, suffers from a lack of protected harbors and fishing docks, facilities which are expensive and dif- ficult to build and maintain. Western North America.—Sailfish, striped mar- lin, blue marlin, and, to a lesser extent, black marlin occur all along Mexico’s Pacific coast. The best- known ports are Acapulco and Mazatlan, although in recent years Cabo San Lucas (in Baja California) and Manzanillo have reported excellent catches of billfishes. Sailfish and striped marlin are common in the lower parts of the Gulf of California as far as Isla Tiburon. Commercial longliners fishing just offshore of these areas have captured prodigious numbers of striped marlin and sailfish; their efforts are evidently affecting the size of the individual sport fisherman’s catch (Gottschalk, 1972). Swordfish are frequently seen off Baja California and are occasionally hooked by anglers. Striped marlin and swordfish have been fished by anglers since the turn of the century. The Tuna Club of Avalon has consistently made good catches along the continental shelf of southern California (Howard and Ueyanagi, 1965). Recent shifts in the currents off southern California apparently have affected the distribution of swordfish and striped marlin and their availability to the angler. Europe.—Sport fishing for billfishes in European waters is limited, and concentrated about the Straits of Gibraltar and the western Mediterranean Sea. Spanish and Portuguese anglers fish for broadbill swordfish (Cordeira, 1958) and catch an occasional white marlin; these species are also caught around the Azores. According to various reports from the journal Mondo Sommerso, sport fishing for white marlin is frequently successful in the Ligurian Sea, off northwestern Italy, while blue marlin are also occasionally taken (Mondo Sommerso, 1968). Most angling is sporadic, however, because of the relative scarcity of billfishes other than swordfish. Little angling information for swordfish is available for most of the Mediterranean, and it is unknown if sport fishing is presently carried out in the Black Sea or the Sea of Azov. Swordfish are taken commercially from the Black Sea and the Sea of Azov (La Monte and Marcy, 1941). La Monte and Marcy reported that, at the time of their writing, there was no sport fishing for swordfish in the Sea of Marmora (Tur- key), though Lebedeff (1936) reported excellent angling there for swordfish. Mediterranean spearfish are taken commercially in the central Mediterra- nean, including the Ligurian, Tyrrhenian, Ionian, and Adriatic Seas, but there are no reports of catches by anglers (de Sylva, 1973). Africa.—Sailfish occur along the African coast from at least Dakar to the Gulf of Guinea. This species supports a sizeable commercial fishery off the Gulf of Guinea (Ovchinnikov, 1966). The world-record Atlantic sailfish of 64 kg came from the Ivory Coast, a location where sailfish are reported to occur frequently. Undoubtedly, sailfish are poten- tially plentiful to the angler along the coast from Dakar into the Gulf of Guinea, although angling facilities including suitable trolling boats are proba- bly scarce. Blue marlin are reported from off Dakar, Guinea, Sierra Leone, and into the Gulf of Guinea, and have been caught by anglers at Ascension and St. Helena Islands. Black marlin are reported in the Japanese longline catches to occur along the Mid- Atlantic Ridge (Ueyanagi et al., 1970); however, no authenticated catch has been made by a commercial or sport fisherman. Swordfish are frequently taken from deep waters along the West African coast. East and South Africa.—Excellent marlin and sailfish angling (Williams, 1970) occurs from Malindi (Kenya) southwards to Durban (Natal). Black mar- lin, striped marlin, blue marlin, and sailfish are taken seasonally along the coast. White marlin, shortbill spearfish, and longbill spearfish have been reported from waters off South Africa, in an area of mixing between Atlantic and Indian Ocean currents (Pen- rith and Wapenaar, 1962; Ueyanagiet al., 1970), but their occurrence is rare. Kenya and Mozambique are also extremely important areas for sportfishing for black marlin and sailfish (Howard and Ueyanagi, 1965), while swordfish are taken on longlines in this region. Large black marlin are taken commercially off northern Madagascar, and sailfish are reported to be taken commercially from waters around the Comoro Islands. There is good angling for black marlin off Mauritius, while commercial charts reveal heavy concentrations of black marlin in the Indian Ocean east of Madagascar along the parallels of lat. 0-10° (Howard and Ueyanagi, 1965; Howard and Starck, 1974). To the north, sailfish have been caught by anglers in the Gulf of Aqaba, Red Sea, and the Gulf of Aden. This species may develop as a sportfishing resource as facilities become available. However, no data are available on seasonal or relative abundance of sail- fish in this area. Large sailfish are taken occasionally by anglers in the Persian Gulf. India and Ceylon.—Black, blue, and striped mar- lin and sailfish are known to occur in Indian coastal waters, but there has been little angling expended in the area. Ceylon has yielded some large black mar- lin, while shortbill spearfish and swordfish are com- mercially taken in deeper waters. Deraniyagala (1937: 348) reported that the swordfish ‘‘is not un- common in deep water to the south and east of Ceylon.” In the central Indian Ocean east to Sumatra and western Australia, commercial fishing records re- veal good catches of black, blue, and striped marlin. Occasional swordfish and shortbill spearfish are also taken. However, sportfishing facilities are limited in these waters and probably will not increase greatly in the future. Howard and Starck (1974) present sea- sonal distribution charts of longline catches of bill- fishes from these waters. The South China Sea and Malaysia.—From longline catch records marlin and sailfish are re- ported to occur throughout Indonesia, the South China Sea, and the Timor and Arafura Seas. Little sport fishing occurs in these waters, largely because of the lack of port facilities and angling equipment. Commercial concentrations of black marlin occur throughout this region. Patrol boats working the In- dochina coast have, in their so-called leisure time, seen and hooked black marlin not far from South Viet-Nam, though the fish are small and scattered. Although sailfish are common in the fall season close to the coast off Nhatrang, South Viet-Nam, the shal- low continental shelf along Indochina appears un- favorable ecologically for the larger members of the billfish family. Japan and the East China Sea.—Huge concen- trations of striped marlin and sailfish occur off south- erm Japan. But these concentrations are sufficiently far offshore to be past the ordinary range of potential sportfishing vessels. Presently, however, there is little demand for offshore sportfishing facilities in the area despite the occurrence of many potential game fish species in Japanese waters. Black marlin occur throughout this region, but are not fished for by anglers. Billfishes are also common east of Taiwan, where they are taken commercially, but no sport fishery exists for them. Indonesia, Philippine Sea, and the Philippines.—Billfishes are relatively uncommon in this region, possibly because the thermocline, which is reported to concentrate food, is deep and below angling depths. Scattered catches of black marlin and sailfish are reported by commercial fishermen, but it would appear that the development of billfish angling would be limited in this area because of the probable scarcity of billfish. According to longline records, black marlin and sailfish are found in con- centrations in the various seas throughout In- donesia. Striped marlin are common south of Java. Micronesia and Melanesia, including New Guinea.—Black marlin occur in commercial quan- tities close to New Guinea, but these fish are not sought by anglers. High concentrations of black mar- lin and sailfish occur in the East Java Sea, and the area between New Guinea and Australia, as well as in the Caroline and Solomon Islands and the Banda and Timor Seas. While these areas are not presently fished by anglers, they may offer good sportfishing potential. Goadby (1970:71) wrote that ‘‘big fish are all through these islands,”’ referring to the New Heb- rides, the Solomons, Tonga, the Gilbert and Ellice Islands, and Western Samoa. Blue marlin are com- mon about New Hebrides, while New Caledonia has blacks and blues. In Samoa there are two commer- cial tuna canneries at Pago Pago; the Japanese report high catches of tuna, together with billfishes, from these waters. Blues, blacks, and sails are common offshore. Good potential sportfishing areas for blues exist throughout the Marshall and Marianas Islands, while Papua and New Guinea yield small black marlin and sailfish. Near Fiji, big black marlin estimated at nearly 700 kg have been taken by commercial fishermen on hand- and longlines working off Suva and Koro Levu. These large blacks are especially prevalent during October. Sailfish up to nearly 80 kg and big blue marlin are not uncommon. Australia. —When dealing with sport fishing in the Pacific, it is difficult to refer to anything but Peter Goadby’s recent book, **Big Fish and Blue Water’’ (Goadby, 1970). In addition to tracing the history of big-game fishing off this productive coastline, Goadby deals with the actual and potential fishing for various billfishes from the major Pacific ports. The serious or potential angler is referred, therefore, to his book. A few of the high points involve the superb billfishing in Australia. Off Queensland, in the northeast, huge black marlin in the 450- to 550-kg class have been taken with increasing frequency. Fishing off Cairns and all along the Great Barrier Reef yields blacks, as do the areas of South Queens- land and New South Wales. Sailfish are commonly taken off the Great Barrier Reef off North Queens- land, while New South Wales is good for striped marlin. There are no authenticated records of any species of marlin taken from waters off Tasmania, although swordfish are taken from these cool waters. Off Western Australia, black marlin and sailfish are occasionally taken, while longline records show heavy concentrations of black marlin off North- western Australia. Among the many firsts for Australia, listed by Goadby, is the first record of a shortbill spearfish (20+ kg) taken on rod and reel, off Port Stephens north of Sydney. New Zealand.—Since Zane Grey’s early big- game fishing operations, northern New Zealand waters have been a continued attraction for fishing for swordfish and striped marlin. The Bay of Is- lands yields many large striped marlin as well as large black marlin, and in recent years more blues have been caught, possibly because anglers have only recently been aware of their presence in the South Pacific. French Polynesia and the Line Islands. —Heavy concentrations of blue marlin have been reported by Japanese longliners to occur throughout the Society Islands and the Tuamotu archipelago. Reports of giant blue marlin taken by native fishermen continue to emanate from Tahiti, but blue marlin sport fishing based in Tahiti has not yet been widely developed. A blue marlin es- timated at over 1,140 kg was caught off Moorea by a commercial fisherman, and blues over 330 kg are common. The black marlin frequently taken in waters off Tahiti exhibit a pale color phase, which Zane Grey referred to as the ‘“‘silver marlin.”’ Large sailfish are frequently taken off Tahiti, one of which weighed nearly 90 kg. The Hawaiian Islands.—Last, but not at all least, are the Hawaiian Islands, whose sport fish- ing catches are world famous. Of course, the Kona coast continues to yield good catches of blue mar- lin and striped marlin. Blue marlin are also taken close to Oahu over the nearby banks. A huge blue marlin (an 820-kg fish) was taken off Oahu; how- ever, it was ineligible for IGFA recognition be- cause several anglers fought the fish. During periods of cooler water, striped marlin are com- mon. Goadby (1970) reported that Kauai, the western side of Molokai, and the south coast of Maui are all excellent grounds for billfishing. Sail- fish are occasionally caught by anglers, while spearfish and swordfish are taken by commercial longliners. For further detailed information on Hawaiian billfishing, Goadby’s book is the source. Royce (1957) and Strasburg (1970) have discussed the distribution and size composition of billfishes taken by longline vessels in Hawalian waters and other regions of the Central Pacific. MECHANICS OF THE SPORT FISHERY Sport fishing for billfish, as well as tuna, is unique in its requirements for specialized and ex- pensive gear. With few exceptions, the success of an angler in finding, hooking, and landing a billfish is directly proportional to the finding, fishing, and maneuvering expertise of the captain and mates, the overall character of the sportfishing vessel and the quality and resolving power of its navigational and depth-sounding equipment, the reliability of the rods and reels, and the special know-how re- quired of the captain or mate to make a dead bait troll so that it ‘‘swims’”’ like a live one. The cost to a banker from Chicago or a secretary from New Orleans will still cost $100 to $1,000 a day, depend- ing on where the billfish are sought and the captain’s reputation as a skilled ‘‘fish-getter.”’ Of course, the person who chooses to own a billfish- ing vessel and maintain a captain, mate, and the vessel’s annual expenses will have to underwrite costs well over the $100,000 mark. Exact data on expenses incurred by billfish and tuna anglers are not presently available. We are currently collecting and analyzing these kinds of data as part of a sur- vey of the billfish and tuna sport fishery of the western hemisphere for the National Marine Fisheries Service. In the questionnaires we mailed to thousands of big-game anglers, we requested confidential information on the various expenses incurred in fishing for billfish and tuna. Most an- glers happily complied, but some who did not indi- cated that if they ever stopped to calculate how much they spent they would never go fishing again. Billfishing might thus be classed as the sport of kings merely because of the cost. But the re- wards are high, the excitement is tense, the memories are forever, and an increasing number of persons in the middle-income bracket are finding ways to save their money for that dream trip to troll off Hawaii or Bimini for that big blue. The most complete description of a Sportfisherman—this being an inboard power boat designed specially for offshore fishing—is given by Rybovich (1965), and for detailed information the reader is referred to this article. Sportfishermen are usually 36 to 42 feet long, and have numerous specific features which are unique (Fig. 2). Among these are the tuna tower, especially kelpful in locat- ing billfish or tuna, baitfish, or birds feeding on the baitfish which frequently indicate billfish. Better visibility from the tower permits the captain to ‘bait’? the fish, such as is done for swordfish and tuna, by circling them with a trolled bait. The flying bridge, from which the captain can maneuver the boat while looking ahead or watching the angler and the fish he may be fighting, has its own set of con- trols. Outriggers have long been used to skip trolled baits at the surface on the theoretical premise that billfish will think that they are seeing their favorite food—flyingfish—and will be irresistibly drawn to them. In reality, billfish hardly ever eat flyingfish, but it gives the angler a thrill when that rare stray marlin comes up from the depths to see what damn fool is dragging an estuarine mullet 50 nautical miles offshore. The line from the rod and reel in the cock- pit is fastened to a line from the outrigger tip by a spring-release clip so that when a fish hits the bait, it drops back. According to the late Tommy Gif- ford, inventor of the drop-back technique, this gives \ 1 ANTENNA \ 2 TOWER OR TUNA TOWER 3 TOWER OR TUNA TOWER 4 FLYING BRIDGE ! 5 COCKPIT OR LOWER CONTROL STATION 6 OUTRIGGER 12 LADDER Figure 2.—Schematic diagram of a Sportfisherman (from Rybovich, 1965). the fish the impression that it has killed its prey. In any event, the billfish has a second chance to swal- low the trolled bait during the brief instant when the bait is not moving through the water. And because outriggers are rather expensive, the drop-back technique, though not necessarily effective in catch- ing fish is great for outrigger manufacturers. A gaff (a large, barbless hook attached to a handle) or a flying gaff (a hook which detaches from the handle, for large fish) may be used to bring small fish on board. For larger fish, a gin pole is used. The gin pole is a vertical beam, ap- proximately 10 x 10 cm, with a block and tackle at its upper end, used to lift large fish into the boat. A tail rope (a noose which can be slipped about the caudal peduncle of a large fish) is suspended from the gin pole, and the catch hoisted on board. In recent years, the tuna door on the transom has be- come popular. The door is merely opened and the fish dragged on board at waterline level. This method is also much safer to the onlookers who may lose limbs from the thrashing spear of the aptly named billfish. The teaser is a hookless wooden, plastic, or metallic object, usually of bright color or reflective substance, which is towed from a short, heavy cord from behind the boat. Teasers vary from highly machined and expensive darting and flash- ing objects to rubber squids and fish, or to beer- can openers, sardine cans, bed sheets, and under- wear. In fact, probably teasers, whatever their origin, are equally as important in attracting billfish as the type of baits presented. A single fighting chair with the built-in footrest is usually amidships in the cockpit, but there may be two or three. This sturdy, specialized chair is on a swivel with a gimballed rod holder at the base of the seat for use when fighting the fish, as well as one or two rod holders on the arm rest. The ideal Sportfisherman is basically designed for range, speed, and maneuverability, and has the ability to tolerate reasonably bad weather, a period when billfish frequently are more active. These boats historically were gasoline-powered, but high-performance diesel engines (although at a higher price) can add endurance and range to a Sportfisherman. Boats capable of 20 to 30 knots are not uncommon today. Such vessels are not meant for the angler’s comfort for more than a day, although the crew may live aboard. The most important facilities to the angler are a good livebait _ well and a good ice box for fresh bait and ice. Speed and maneuverability, so important to bill- fishing, are a function of hull design. Specific types of hull designs vary somewhat with each manufac- turer of Sportfishermen (e.g., Hatteras, Bertram, Huckins). Recently, however, there has been a trend to a specifically designed small Sportfisher- man having an open-cockpit, in the size range of 7 to 10 m, usually with a deep V-hull (Robert D. Stearns, personal communication). Rybovich (1965) summarized the principles in- volved in considering speed and maneuverability, as well as theories behind the outrigger, flying bridge, gin pole, transom door, tuna tower, fishing tackle, and electronic equipment, all peculiarities of sport fishing for billfishes and tuna. Electronic equipment is extremely important in locating fish. Wealthier anglers may employ their own spotter planes to help them locate fish, in much the same way menhaden commercial fleets have their planes to indicate when and where to set their purse seines. In lieu of spotter planes, the captain of a Sportfisherman must attempt to locate or return to a fishing spot which he knows to be productive. For this he needs an RDF or, better, radar and loran; possibly the more affluent anglers will be using satellite navigators at $45,000, a small price to pay when one has already spent $100,000. A good depth indicator, preferably a recorder on which one can detect bottom contours for future reference, will help the angler to find his favorite fishing ground, as well as his safe return home. The tackle itself is extremely specialized. Be- cause of the large fish involved and the speed of the trolling boat, the force exerted on all gear is quite large. Fiberglas rods are custom-built for bill- fishing, while reels must be carefully constructed and maintained. Line which has a breaking strength of 12, 20, 30, 50, 80, and 130 pounds is used for various species, depending on the circum- stances, each of which relegates fish caught on that test line to a particular category within the IGFA classification. Wire leaders are specially and care- fully prepared, as are the swivels and snaps for the terminal tackle. Hooks, which are expensive, are carefully chosen for the type of fishing and the species sought. Baits are frequently among the most controver- sial item for billfishes. One can travel far and wide and never get the same answer from fishing cap- tains. Among the most widely used billfish baits in the United States are the mullets (Mugil), possibly because of their availability. Bonefish (Albula spp.) are popular, as are balao, or ballyhoo (Hemiramphus and_ relatives), mackerel (Scombeéromorus), barracudas (Sphyraena), dol- phin (Coryphaena), rainbow runner (Elagatis bipinnulatus), jacks (Caranx spp.), tunas and bonitos (Thunnus, Katsuwonus, Euthynnus, Sarda), squids of several genera, flyingfish (Ex- ocoetidae), and artificial and rigged eels (Anguilla) and eel skins. Artificial lures trolled as baits are locally popular, including rubber squids, sauries, mackerel, bonitos, halfbeaks, and eels. One of the largest restrictions to the development of sport fishing for billfish in new areas is the guarantee that an adequate, continual supply of fresh bait will be available, and at a reasonable price. Anglers and skippers have been reluctant to use preserved or artificial bait, in spite of the high billfish catches obtained by commercial longliners using salted or dried bait (squids, sauries, mack- erel, which are not even trolled), or the probable inability of billfishes to distinguish between trolled baits which are fresh or preserved in Formalin. It is important to note that anglers using exper- tise, boats, tackle, bait, and navigational equip- ment which are minimal in quality probably will catch fish, but that the quality of these facilities and expertise is directly proportional to angling success. A rule which might be applicable to bill- fishing is that the more you spend the more you catch. Finally, it should be stressed that billfish angling is very inefficient. A few captains troll a single bait, while most troll four (two outriggers with skipped bait and two baits trolled slightly subsur- face from ‘‘flat-lines’’) or six (four outriggers and two flat-lines). These baits are being trolled at or within a meter of the surface; hence, the billfish, which normally are subsurface feeders, may not see these relatively tiny baits, especially if the sea surface is rough, or if visibility is poor due to clouds or turbid water from various causes, and under such conditions the chance of catching a bill- fish therefore becomes less. This method is in con- trast to the relatively successful commercial long- line which fishes from near the surface to over 150 m beneath the surface and which entails up to 60-75 km of longline involving up to 2,000 hooks. That the angler may catch more billfish when none appears at the surface has been shown in numer- ous angling tournaments by the intrepid and non- conformist anglers who dared to drift a bait at 50-100 m. Those who did occasionally won the tournament (and within the confines of IGFA rules), yet were suspect and outcast because of their devious ways. It may be concluded that while billfish captains and anglers are usually quite suc- cessful, most seldom attempt to try new ideas which will deviate from past tried and true methods. SIZE OF CATCH It is interesting to speculate on who catches the largest individual billfish, using what type of lure, under what conditions, and where. No data are available to compare the efficiency of sport and commercial fishermen using trolled baits versus longline per hook. Clearly, longlines are more effi- cient because they fish at the depth where billfish feed, and because there are more hooks fishing at that depth. Yet we do not know if a cleverly rigged, surface-trolled mullet, fished at the sur- face will catch more fish per unit effort of hook. Similarly, data are unavailable to determine wheth- er a longline or angler-trolled bait catches larger fish. There is no evidence either way that the very large billfish—those above 500 kg—are more or less able to break the hook or gangion (drop-line) on a multiple-hook longline rig, versus whether they are easier to fight and land on a single hook. This con- troversial question is open to serious discussion, for it is equally meaningful to the commercial or sport fisherman who wants large fish. If only large fish are available to the longliners yet they cannot be landed because they snap the hook or gangion, then there is no point in fishing for them, and therefore areas reportedly harboring large fish could be avoided. Conversely, the angler is usually not interested in large numbers of small marlin, and would tend to seek those huge marlins which can be hooked, fought, and landed which take ad- vantage of the ‘‘give’’ in monofilament or Dacron line, the bend of the rod, and the captain’s ability to determine the fight which the fish will be able to offer. Data are needed on all billfishes caught by the angler. Possibly, only small fish are released, so that the scientist obtains a biased estimate of the size of the angler catch, whereas fishermen who fish commercially for billfish retain all fish. Examina- tion of taxidermists’ records, however, do not sug- gest differential release of very small or very large fish, although very small billfish (less than 5 kg) are uncommon in anglers’ catches because of the large baits trolled. Earle (1940) and de Sylva and Davis (1963) pre- sented data on sizes of white marlin from the Mid- dle Atlantic Bight, from Long Island, New York, to Hatteras, North Carolina, while Erdman (1962, 1968) and de Sylva (1963) reported on sizes of blue marlin taken at Puerto Rico and Jamaica, respec- tively. Williams (1970) presented extensive length and weight data on sailfish taken from off Kenya, East Africa. Size distribution of sailfish, as re- flected in taxidermists’ records, from the south- eastern United States, were reported by de Sylva (1957). To this writer's knowledge, these represent the sum total of published size data on the sport fishery for billfishes. A detailed analysis of the size-frequency distribution of billfish in the sport catch in the western hemisphere is presently being carried out by the writer, but, except for a few specific areas (Maryland, North Carolina, south Florida, Jamaica, Puerto Rico, the northern Gulf of Mexico), few good data are available. There- fore, a request is made herein to any anglers or angling clubs in the western hemisphere who have records of the size of billfish they have caught, or catch per effort data, to submit them for analysis. TIME OF BILLFISH ANGLING Swordfish feed more frequently at night, as indi- cated by longline catches, although they are taken by anglers during the day. Possibly the difficulty which anglers experience in getting a swordfish to take a bait is associated with its poor daytime visi- bility, or because it also feeds by smell. The istiophorid fishes feed largely by sight. Longline catches, and the condition of the stomach contents of billfishes, indicate that they feed at dawn and dusk, when they probably rise closer to the surface, descending to deeper levels during daylight hours, possibly just above the thermo- cline. The angling effort for istiophorids is conducted almost exclusively from 8, 9, or 10 a.m. until 4, 5, or, at the latest, 6 p.m. Hence, most angling for billfish is done not only when they are not actively feeding, but also when they are swimming at sub- surface depths. That small fraction of the billfish population which does rise to the bait trolled dur- ing daylight hours may be hitting the bait out of curiosity, as evidenced by the occasionally very full stomachs of billfish taken by anglers. In short, billfish anglers usually fish at the wrong time. Sport fishing for billfish is often merely a part of the overall relaxation pattern for an angler, and he usually fishes during the day and returns relatively early, usually well before dusk, for relaxation back at port. Hence, even though the captain may feel that he should fish later, the angler may suggest that fishing cease earlier. Of course the frequently long runs to and from the fishing grounds and the sometimes tortuous navigation path back home may not permit the captain to fish late. Those cap- tains who make runs to the fishing grounds and overnight on them, so that they can fish earlier or later than usual, frequently make good catches. Few data are available from anglers’ or captains’ logbooks on the best time of fishing. However, data from the Bahamas and Jamaica suggest that from 6 to 9 a.m. and from 3 to 6 p.m. are the best for getting strikes (de Sylva, 1974). It is not known if billfish will take a trolled bait between 6 p.m. and 6 a.m. because little, if any, angling is con- ducted during this period. SPECIAL PROBLEMS OF THE BILLFISH SPORT FISHERY Sport fishing activities for billfish in the past have not been well documented. There is a press- ing need for qualitative and, especially, quantita- tive information if this valuable fishery is to be managed, and if the potential sociological conflict between sport and commercial fishermen is to be resolved. Now that we are faced with growing en- vironmental problems, such as the deleterious ef- fects of polluted water on sailfish or the high con- centrations of heavy metals in swordfish, we must pay more attention to the dynamics of the marine environment. These much-needed data can only be obtained through the cooperation of the angler, commercial fisherman, boat captain, the sport and commercial fishing industry, and the scientist. Let us consider, therefore, the components of the sport fishery which are so peculiar to billfish. The Fishing Grounds Sportfishing grounds for billfish are greatly in need of having their ecological characteristics de- fined. There is a serious lack of information on the physical and chemical characteristics of the angling grounds, including the distribution of temperature, salinity, oxygen, and turbidity, and their interaction with plankton, micronekton, and billfish. How these factors interrelate with one another may af- fect the feeding, vertical and horizontal move- ments, and general behavior of both the billfishes and their food. Most of all, these data are needed so that the scientist can reduce them into terms readily understandable to the angler. The term ‘‘fisheries oceanography” has been used to describe the appli- cation of oceanographic principles so that the com- mercial fishing boat skipper can locate commercial concentrations of fish (Hela and Laevastu, 1971). However, this concept has seldom been used either by captains of Sportfishermen or by scientists to locate good billfishing grounds for the angler. This seems to me one of the mutual goals of scientists and anglers. Fishing grounds can sometimes be improved through artificial habitats. Artificial reefs are bot- tom structures used to attract bottom or midwater game fishes, yet the tsuke rafts of the Japanese —bales of straw or other floating or anchored structures—could be used to attract small fishes upon which billfish feed. Possibly the greatest threat to our billfish sport fisheries resources in not overfishing but manmade environmental changes. Billfish sport and com- mercial fishery interests must join together in re- ducing present pollution levels and preventing new sources of marine pollution. Pesticides, PCBs, heavy metals, sewage wastes, and various hy- drocarbons (mostly oils and tars) not only are poten- tially dangerous to various stages of the life cycle of billfish and the organisms on which they feed, but these compounds are concentrated sublethally in various parts of the billfish, making them poten- tially dangerous to human consumers (Wilson and Mathews, 1970). Pollution damages not only the living resources but also the fishing grounds by removing oxygen, adding toxins which may cause fish to change their behavioral, migratory, repro- ductive, or feeding habits, and increasing turbidity so that billfish cannot see baits trolled from boats. In Palm Beach County, Florida, the latter phenomenon apparently has forced billfish anglers to go much farther away to find sailfish, with a re- sulting increase in fuel costs and a lessened amount of time which can be devoted to actual angling. Dredging, filling, and the disposal of untreated sewage all combine to turn Palm Beach’s once-blue sailfish waters to the shade of weak coffee. The basic problem is that such environmental degrada- tion is not being documented, which is sorely needed if appropriate restorations are to be made. A special occupational hazard of billfish and tuna anglers is the shark problem. A single shark bite will disqualify a potential record game fish from qualifying under IGFA rules and, hence, the angler needs to boat his fish safely and rapidly. Sharks occur wherever billfish swim, but their ten- dency to attack billfish is not well understood. In very clear tropical waters they tend to attack less, while in murky or polluted waters they become fierce, frequently going into the so-called ‘‘feeding frenzy.’’ A knowledge of why sharks attack a bill- fish might aid the angler in avoiding areas of poten- tial shark attack and, hopefully, lead to some effec- tive shark repellent. Habitat improvement, pollution reduction, and shark deterrents are all important goals to billfish anglers which could be cooperatively studied by anglers, boat captains, tackle and boat maufactur- ers, local, state, and federal governments, and sci- entists. Such cooperation, at all levels, should be one of the goals of this Symposium. The Boat Captain Like all ship captains, the captain of a Sport- fisherman is stubborn, brilliant, cantankerous, ded- icated, independent, and unshakable in his habits. If he is an unusually competent fish-getter, his be- liefs are even more entrenched, while if he does not produce for the angler consistently, he can blame his poor catches on wrong tides, poor weather, lack of baitfish on the grounds, bad bait, too low water temperatures, pollution, nuclear fallout, or Japanese longliners. With all his other problems of keeping his ship operating perfectly, catering to wealthy and often difficult anglers, catching fish, and getting back to port, the skipper actually has little time to learn new techniques or to search for new areas even if he wants to. Scientists stress the need for accurate log books to be placed aboard Sportfishermen so that strikes, water temperatures, bird flocks, and sea and wind conditions can be recorded. Many skippers actively tag billfish in cooperation with tagging programs of Woods Hole Oceanographic Institution or the Tiburon Fisheries Laboratory, though the maintenance of carefully maintained logbooks is frequently beyond the physical capabil- ity of the captain. Most billfish captains are intelligent, friendly, and inquisitive about marine science, and espe- cially about the fish upon which they depend for their living. Many can and will help scientists in the acquisition of reasonable quantities of data which will yield information for science as well as to help him make a better living. Sport fishing cap- tains have cooperated with scientists by tagging | fish, collecting specimens, stomach contents, or gonads, collecting water samples and plankton, taking water temperatures, and releasing drift cards for current studies, as well as by maintaining logbooks of when and where they caught fish. But the boat captain really has little scientific informa- tion on the habits or ecology of billfish, and he can obtain this only through conversation, in nonscien- tific language, or by reading nontechnical articles. It is the duty of the scientist to supply this infor- mation if he is to receive continued cooperation. Excellent examples are the newsletter which Frank Mather sends to all his billfish taggers and the circular of the Southwest Fishery Center _(NMBS) sent to anglers in the Hawaiian Interna- tional Billfish Tournaments. A similar but different service is performed by the International Game Fish Research Conference, sponsored by the In- ternational Oceanographic Foundation in Miami. At these annual meetings, anglers, guides, boat captains, news writers, and scientists gather to- gether informally to discuss game fish and game fish research. The cooperation of the billfish captain is most important if adequate, meaningful scientific data are to be collected. Scientists interested in billfish research have only three methods of recourse to secure data: they can collect billfishes themselves, a highly expensive, time-consuming, and ineffi- cient technique (especially since most scientists are notoriously poor anglers!); they can rely on commercial longliners, who are invaluable, but who usually cannot supply data from coastal sport fishing areas where longlining is sociologically off- limits; or they can rely on a large number of sport- fishing boats to gather quasi-synoptic data. For this, the boat captain is indispensable. The Angler The billfish angler may be little more than a pawn as far as billfishing is concerned. In spite of _ the payments he makes and the distances he _ travels to catch billfish, he is at the mercy of the _ habits of the billfish, the expertise of the captain and mates, and the dependability of the fishing boat. His expertise in most cases is not required to catch the billfish, for the captain finds the fish, and he and the mate tell the angler when and how to set the hook and how to fight the fish; the angler, essentially, merely reels, pumps, and reels, until the mate grabs the wire leader, then the bill, and then gaffs and boats the fish or releases it. Yet the skillful captain permits his angler to believe that he has caught the fish ‘‘all by himself.’’ It is little wonder, then, that after one sailfish, the angler may become a self-styled expert, thereafter fre- quently suggesting to the captain how to run the boat and how fast to troll. It is here that the scientist must rely on the boat captain to help him win over the angler to cooper- ate in supplying scientific data. A well-informed boat captain can convince the angler that he should tag and release his fish, or open the stomach, or bring the fish in for study. Only too often, anglers frustrate scientists’ efforts to obtain a sufficient number of billfish for study because they believe ‘it’s bad conservation’? not to release. Thus, the scientist is deprived of the much-needed data which will enable him to determine what is ‘‘bad conservation’? and an appropriate management program. Such cooperation requires the scientist to communicate his thoughts to the angler, as well as to the boat captain. Catch and effort data, economic information, logbook data, tagging information, and moral and financial support may all emanate from the billfish angler, but it is a matter of supplying information and education on the part of the scien- tist. The Sportfishing Industry As such, there is no real sportfishing industry in the sense that there is a commercial fishing industry. Sport fishing is represented by builders of boats, motors, rods, reels, tackle, lures, and various specialized gear for billfish such as fighting chairs, gin poles, and outriggers. There is no single, unified voice which speaks on behalf of this broad field. The American Fishing Tackle Manufacturing As- sociation is extremely important, but represents only a small portion of the industry. The single most important influence in the de- velopment of sport fishing, including billfish and their research and conservation, has been the Sport Fishing Institute, Washington, D.C. In its monthly Bulletin, it reports on latest research finds, angling activities, legislation important for sport fisheries, conservation programs, education in the aquatic sci- ences, and a host of other items. This Symposium may have had its roots with the Sport Fishing Insti- tute, because it was this organization which met informally with Japanese negotiators in Brazil in May, 1966, at the height of the controversy between sport fishermen and Japanese longline fishermen, to reach peaceable, workable solutions. This meeting also focused attention on the need for much more biological, statistical, and economic data on billfish, which various research organizations have attempt- ed to collect since that meeting. Agencies such as the Sport Fishing Institute can act catalytically to bring together anglers, scientists, boat captains, commercial fisheries interests, and state, local, and national governments. They can promote the ideas for the development of new kinds of lures, sonic or optical teasers, better boats and navigational equipment, new kinds of baits, and scores of concepts which, if effected, would benefit everyone. Most of all, such an organization can promote good will among all factions and can help prevent much of the misunderstanding and distrust which frequently occurs when several kinds of ex- ploiters are competing for the same resource. The Multiple-use Concept for Billfish Billfishes perhaps represent one of the ideal or- ganisms to mankind. They are spectacular fighting fish for the angler, and their unpredictable leaps, jumps, skittering, greyhounding, and tailwalking have resulted in reverent terms for billfish acrobatics when they are being hooked and fought. When re- leased, they give the angler a spiritual sense of gratification in having let a magnificent sea creature go, to swim again with its man-spared life, perhaps to take his or someone else’s hook one day. Even bet- ter, a fish marked with a tag may be caught again, possibly a few miles away, or possibly several thousand miles away and several years from now, to give science valuable information on its habits. When mounted by a taxidermist and, posed on the den wall, a billfish is a magnificent memento of a splendid day’s action. The profit to the taxidermist is considerable, while the agent, who may be a boat captain, a mate, a dockmaster, as a specific task, receives a percentage of the taxidermist’s cost, which averages about $2 per inch, which isn’t really very much after one has spent perhaps a thousand dollars to get to the angling grounds. A billfish caught by an angler and kept chilled or out of the sun is still available as food. Fresh billfish are excellent to eat and, depending on the species, range from fair to excellent as food. Billfish can be eaten fresh, smoked, canned, salted, baked, fried, curried, sautéed, or, especially, smoked. Smoked billfish is somewhat like Canadian bacon in flavor, and can be served as a staple food or hors d’ oeuvres. Few fish are more adaptable or have fewer small bones for the connoisseur to discard. Finally, after the fish is hooked, fought, landed, professionally photographed, skinned and mounted, smoked, and eaten, the last remnants of the fish—the bones and guts—still remain for the scientist to study. Billfish can, of course, be carefully and easily skinned so that the fish is intact for a taxidermist’s mounting yet remains available for scientific study. In short, the billfish is the complete fish for the complete angler—something for everyone. To avoid excessive support for my taxidermist colleagues, I will avoid a discussion of the extremely valuable information which they freely supply to scientists, such as specimens, stomach contents, and gonad collections. Thus, a billfish is truly a multipurpose fish, a sort of biological schmoo, as long as there are plenty of them to satisfy the needs of all legitimate interests while still maintaining the biological stocks. The ra- tional utilization and management of these stocks must necessarily depend on scientific information derived from size composition, population esti- mates, and growth and mortality calculations. As long as the scientist believes that there are adequate biological stocks to support a sport and commercial fishery, then there appears to be no reason why billfish can not be utilized for as many human- oriented uses as possible, other factors being equal. Billfish as food, as taxidermists’ mounts, and as scientific specimens should thus be utilized, either by catching, mounting, studying, and eating them or by tagging and releasing them. It is here, especially, where a cooperative management and marketing program, or both, is needed on the part of anglers, the sport fishing industry, guides and captains, and governments. The best use for a resource is rational economic and biological exploitation, rather than ‘“‘blind’’ conservation (de Sylva, 1957). The ever-present problem in billfish research deals with conservation versus aesthetics. Scientists may hate to see a magnificent marlin brought in to the dock, hung on a hook for photography, and al- lowed to rot, while anglers feel exactly the same way. Yet both groups are displaying emotions. The scientist must determine if such a demise for large marlins is biologically deleterious to the stock, while the angler should analyze if his indignation against desiccated sailfish hanging on a rack is not really the feeling for virtue, aesthetics, and sportsmanship. Thus, we are faced with conservation versus aesthet- ics: we must not confuse the two concepts. It is perfectly justifiable to release a dozen sailfish, even though they are already senescent, for sportsman- ship purposes, in hopes that you may catch them again or, if they are tagged, that you will catch one of your own tagged fish. But one must be careful not to confuse aesthetics with conservation. Conservation means the wise utilization of existing stocks, based upon scientific evidence, whereas aesthetics reflect how the angler feels emotionally toward the same stock, without benefit of adequate scientific evi- dence. All too often our sport fishery for billfish, and many other resources, has been regulated, legis- lated, and dominated by aesthetic criteria rather than by scientific facts. Billfishes can and should be used by many persons and countries. These countries, and their alleged factions of sport and commercial billfishermen, tackle manufacturers, and boatmen, require a well- coordinated regular program based on scientific evi- dence which is, in turn, based upon goals mutually decided upon by scientists, anglers, boat captains, commercial fishermen, and outdoor writers. Such programs could include tagging, stomach analysis, gonad collection, and collection of environmental information based upon data required by scientists. Unless we obtain adequate scientific information on this valuable resource, we may be faced with Orwel- lian national and international regulations that none of us can accept. The Billfish Tournament Friendly competition among men, as exemplified by amateur sports, initially was intended to test comparative feats of skill, strength, and endurance. But the tournament may bring out the best and the worst in all of us, and sometimes we forget why we are fishing. The lure of prize money or trophies frequently affects man, and his actions are not al- ways what his original intentions were. Billfish tour- naments usually involve strict rules of trolling, bait usage, chumming, line tests, and method of release, and an angler, or even his captain or mate, may be tempted to overlook these rules if it seems expedi- tious in order to wina tournament. While the competi- tive sport of winning is important, it perhaps should 29 not be reflected in trophies for the anglers and money for the winning crew. An ideal tournament to dis- courage bad sportsmanship is perhaps where everyone wins a first prize. Tournaments have many advantages, however. Anglers and captains have a chance to test their skills, new tackle, and their Sportfishermen under severe conditions imposed by intense fishing. The comradeship at cocktail hour is perhaps underesti- mated, for here old acquaintances are met and new friendships made. These happy hours are especially auspicious for the scientist, for here he can infor- mally exchange information with anglers, captains, and crew. Tournaments are also important in that during a short period of time, a large number of fish may be brought in for research for scientific observa- tions, or a great many billfishes can be tagged and released, or a considerable number of nearly synop- tic observations can be made by anglers and captains on the fishing grounds. Successful tournaments are frequently those in which angling and science work together, especially when the angler and captain feel that they are contributing something to science which may improve their billfishing some day. The Hawaiian International Billfish Tournament is an outstanding example of such cooperation. The Role of Local, State, and National Governments Governments can benefit from encouraging bill- fish angling in their waters because of the revenue brought in by an angler and spent on boat charters, hotel, food, and, especially, alcohol, airline travel, car rental, and souvenirs, as well as miscellaneous funds spent by his family which may accompany him. Increasingly, more airways are including big- game fishing as part of a package tour for a vacation. Underwriting costs could be done by governments for the acquisition and development of better sport- fishing vessels, docks, fueling facilities, bait collec- tion and storage, and exploratory angling for new fishing grounds. Such costs can seldom be borne by individual boat captains. Governments can offer in- centives for the training of capable fishing mates, and can reduce the high import taxes on boats, gasoline, and tackle used in angling. All levels of government should be concerned with protecting their valuable fisheries resources, as well as developing them. Outmoded laws should be re-evaluated and replaced with laws based on cur- rent scientific findings. For such reasons, it is impor- tant for the governments to work closely with scien- tists. Also, anglers and boat captains are seldom represented at government levels or are advisors to them. Finally, all levels of government should sup- port scientific research, exploratory fishing, and the development of angling for billfish. More coopera- tion is needed among the anglers, scientists, and governments. Possibly here is where private organi- zations such as the Sport Fishing Institute can be a catalyst to motivate cooperative efforts. The Scientist The greatest hindrance to the development of bill- fish research has been the scientist, partly because of lack of funds and partly because of a lack of interest. With the exception of the Japanese research pro- grams, there have been no well-funded, long-term, or comprehensive studies on billfishes. Most scientific publications on billfish have been done on a financial shoestring or are a spinoff pirated from another pro- ject. Anglers, commercial fishermen, boat captains, and scientists must urge that adequate funds be made available for long-term comprehensive studies. A scientist must convince funding agencies that re- search on billfish is needed; he can be aided morally by anglers, captains, commercial fishermen, the sport fishing industry, and local governments in his quest for support. And, most important, the scientist must clearly communicate his research interests with the granting agencies, as well as the persons from whom he seeks collateral support. During these studies, if he receives financial support, he is continually obliged to report his findings—including those relating science and billfishing—to the sportsmen, boat captains, and the sport fishing in- dustry in understandable language. Supporters of billfish research want and deserve results. What are some of the directions billfish research should take? The pure scientist should rightfully be interested in billfish systematics and evolution, re- production and development, behavior, food and feeding, life history, ecology, and any facets of the broad fields which he wishes to pursue. It is presently impossible with our knowledge and facilities to capture, transport, and maintain in capitivity an adult billfish. However, behaviorists using submersibles and even scuba should attempt to study the daily activities of billfish in their natural habitats including their horizontal and vertical mi- grations. Such observations might offer clues to the visual and olfactory senses of billfish, information 30 which would be valuable to billfish anglers. Rearing of eggs and larvae can probably be done to at least the juvenile stage, and such information should re- veal valuable information on the physiological re- quirements and behavioral ecology of billfishes. Tagging studies should be intensified to include tagging of smaller specimens of billfish (1.e., those with a potentially longer life span ahead of them) concomitant with genetic and morphometric studies of subpopulations. By studying catch rates from an- glers’ logbooks and tournament records, fluctua- tions in catch per unit of effort can be detected. The problem of the fishing grounds has already been discussed, but this problem should be reviewed here to stimulate further study. Environmental (i.e., physical, chemical, and biological) information should be obtained about billfish habitats, including information on environ- mental fluctuations, hopefully at the same time span and in the same areas that biological data are being gathered on billfishes. Knowledge of temperature, salinity, turbidity, density, thermocline structure, and plankton patterns in relation to billfish distribu- tion can be jointly analyzed by biologists and physi- cal oceanographers. The effects of pollution on billfishes should be studied, including the transfer of contaminants through the food web. Heavy metals, chlorinated hydrocarbons (including DDT and PCBs), sew- age and industrial wastes, various hydrocarbons and their fractions, and radionuclides may adversely af- fect billfish at some stages of their life history, or may interfere sublethally with metabolic processes, such as reproduction or migrations. Finally, man- made contaminants may build up via the food web to high concentrations in various parts of billfish flesh, at which levels they are a potential hazard to the hu- man consumer. Who is going to do all this work? There are already many needy research projects going unsolved and unfunded. The problem is particularly difficult with the hard-to-study big-game fishes because of the ex- pense and time involved, and the good possibility that the investigator will end up with few or incon- clusive data. Hence, this type of study is likely to be done by a technician working 8 a.m. to 5 p.m. during the week, and it is virtually impossible to study bill- fish on such a schedule. The alternative is to attract imaginative young students to these problems. Yet, few students will embark upon a master’s or doctoral program unless there is some assurance that they will obtain their degree in a reasonable time, and that the results, even though negative, will be scien- tifically acceptable. It has been my experience that few students will attempt theses as risky as those involved studying the unpredictable billfish. One answer may be in providing adequate funds to senior investigators who can conduct long-term re- search and relegate a small portion of that research to their students for a suitable graduate degree. Once all of this research has been completed, how does it relate to the angler, the boat captain, and the management of the resource? The biological and environmental data, used judiciously, can serve as management tools. Through cooperative studies which actively involve the angler and boat captain, the scientist can obtain biological, statistical, and environmental data. Such data can be valuable to the angler and boat captain, for the scientist may be able to make reasonably accurate forecasts of when and where the billfish angler should fish, at what depth, at what time, using what kind of bait, and at what trolling speed. These are not unreasonable demands of the angler to make of the scientist. Scientists should also work with the boat captain and the sportfishing industry in the application of behavioral principles in developing new kinds of arti- ficial lures which utilize the visual or sonic responses of billfish, or in developing of artificial floating habitats which might attract and concentrate billfish. This scientific information should be sorted out in such a way as to be meaningful for the layman to understand the fish they seek, and possibly to catch more billfish or even to be able to catch billfish when no one else can. To date, marine science has greatly aided commercial fisheries, but there are few in- stances where marine science has contributed prac- tical solutions to the anglers’ problems. The key words are cooperation and advice which will benefit all parties without damaging the billfish resources. A first step is to determine if commercial fishermen can continue to take large quantities of billfish without depleting the resource or reducing the billfish sport fishery catch. A second point is that environmental degradation favors neither sport nor commercial fishermen. All persons interested in bill- fishes and billfishing must work together openly and intelligently, as we have done at this Symposium, to resolve alleged differences among ourselves, to abate marine pollution, and to urge more research and intelligent communication. 31 POSTSCRIPT The foregoing discussion of the billfish, boats, gear, angling methods for billfish, and the future pertains to the most successful kind of billfish an- gling. Yet we know that such expense and time can only be enjoyed by a small percentage of recreational fishermen in a small part of the world. Parentheti- cally, we may ask ourselves why we need or even tolerate such expensive pleasures in a world fraught with hunger, disease, hatred, and war? Possibly, we may reply, if we had the option for some form of relaxation, from throwing pebbles in the pond in Iowa to trolling for black marlin off Australia, that such relaxation regardless of expense, could enable us to be at peace with ourselves and our fellow men. One may argue whether we really need something as expensive as angling for billfish. But how many of us, either as oceanographers, or anglers, or plumbers, or book clerks, rest our Mitty-like hopes and imagination in defeating the invading Mongol hordes, or in subduing the Nile crocodile, or in or- biting the moon, or—something with which all of us can identify—in landing that monster blue marlin off Tahiti that Zane Grey once told us about? ACKNOWLEDGMENTS The late Colonel John K. Howard was especially helpful in supplying information and data on sport fishing for billfish in all parts of the world. The late Albert Swartz and Al Pflueger, Sr., and Richard H. Stroud and Paul E. Thompson gave freely of their time and suggestions. This research was supported in part by the Bureau of Sport Fisheries and Wildlife, Contracts BSFW 14-16-0008-775/DI-14-16-0008-957, and the Maytag Chair of Ichthyology, University of Miami. LITERATURE CITED CORDEIRA, A. 1958. Espadartes do Sesimbra. Pedidos a Edicées “DIANA,” Ave. Infante Santo, Lisbon, 89 pp. DERANIYAGALA, P. E. P. 1937. The swordfish Xiphias of the Indian Ocean. Ceylon J. Sci., Sec. B, 20(3):347-349. DE SYLVA, D. P. 1957. Studies on the age and growth of the Atlantic sailfish, Istiophorus americanus (Cuvier), using length-frequency curves. Bull. Mar. Sci. Gulf Caribb. 7(1):1-20. 1963. Preliminary report on the blue marlin sport fishery off Port Antonio, Jamaica. Inst. Mar. Sci., Univ. of Miami, Spec. Rept., 15 pp., mimeogr. 1973. Family Istiophoridae, pp. 477-481. Jn Hureau, J. C., and Th. Monod, editors, Check-list of the fishes of the North-east Atlantic and the Mediterranean. Vol. 1, UN- ESCO, Paris. 1974. The life history of the Atlantic blue marlin, Makaira nigricans, with special reference to Jamaican waters. In Richard S. Shomura and Francis Williams (editors), Pro- ceedings of the International Billfish Symposium, Kailua-Kona, Hawaii, 9-12 August 1972, Part 2. Review and Contributed Papers. U.S. Dep. Comm., NOAA Tech. Rep. NMFS SSRF [Abstract only.] DE SYLVA, D. P., and W. P. DAVIS. 1963. White marlin, Tetrapturus albidus, in the Middle At- lantic Bight, with observations on the hydrography of the fishing grounds. Copeia, 1963:81-99. DE SYLVA, D. P., and S. UEYANAGI. MS. Comparative development and distribution of the bill- fishes (Istiophoridae) of the Atlantic and Mediterranean. To be submitted to DANA Reports. EARLE, S. 1940. The white marlin fishery of Ocean City, Maryland. U.S. Fish Wildl. Serv., Spec. Sci. Rep. 6:15 p. ERDMAN, D. S. 1962. The sport fishery for blue marlin off Puerto Rico. Trans. Amer. Fish. Soc., 91:225-227. 1968. Spawning cycle, sex ratio, and weights of blue marlin off Puerto Rico and the Virgin Islands. Trans. Am. Fish. Soc. 97:131-137. FOX, W. W. 1971. Temporal-spatial relationships among tunas and bill- fishes based on the Japanese longline fishery in the Atlantic Ocean, 1956-1965. Sea Grant Tech. Bull, Univ. Miami, 12: 78 p. GOADBY, P. 1970. Big fish and blue water. Angus and Robertson, Syd- ney, 334 pp. GOTTSCHALK, J. S. 1972. Longlines and billfish. Paper presented at the Con- vention of the Outdoor Writers Association of America, Mazatlan, Mexico, 26 June 1972. Natl. Mar. Fish. Serv., U. S. Dept. Commerce, Washington, D.C., 22 p. (Dupli- cated.) HELA, I., and T. LAEVASTU. 1971. Fisheries oceanography: new environmental ser- vices. Fishing Books (News) Ltd., London, 238 p. HOLDER, C. F. 1903. Big game fishes of the United States. The Macmillan Co., N.Y., 435 p. HOWARD, J. K., and W. A. STARCK, II. 1974. Distribution and relative abundance of billfish (Is- tiophoridae) in the Indian Ocean. Stud. Trop. Oceanogr. Miami. Jn press. HOWARD, J. K., and S. VEYANAGI. 1965. Distribution and relative abundance of billfishes (Istiophoridae) of the Pacific Ocean. Stud. Trop. Oceanogr. Miami 2:1-134 + Atlas. LA MONTE, F. R., and D. E. MARCY. 1941. Swordfish, sailfish, marlin, and spearfish. Ichthyol. Contrb. Inst. Game Fish Assoc. 1:1-24. LEBEDEFF, W. A. 1936. Paradise for big game fishing. Fish. Gazette, Oct. 3, 1936, p. 420-421. 32 MANNING, J. A. 1957. Summary or investigations on the pelagic fish survey of Chilean waters with special reference to the swordfish, marlins, and tunas. Fla. Bd. Conserv., Univ. Miami, Rept. $7-4:12 p. MATHER, F. J., II. 1952. Sport fishes of the vicinity of the Gulf of Honduras, certain Caribbean islands, and Carmen, Mexico. Proc. Gulf Caribb. Fish. Inst., 4th Annu. Sess., p. 118-129. MONDO SOMMERSO. 1968. Il favoloso marlin blu nel mari italiani. Mondo Sommerso, 10(11):i. MORROW, J. E., and S. J. HARBO. 1969. A revision of the sailfish genus /stiophorus. Copeia 1969:34-44. MOWBRAY, L. L. 1956. The modified tuna long-line in Bermuda waters. Proc. Gulf Caribb. Fish. Inst., Eighth Annu. Sess., 137-142. NANKAI REGIONAL FISHERIES RESEARCH LABORATORY. 1954. Average year’s fishing condition of tuna longline fisheries, 1952 edition. [Introduction and albacore section.] Nippon Katsuo-Maguro Gyogyokumiai Rengokai. [In Jap.] (Translated by W. G. Van Campen, 1956, 131 p.; available U.S. Fish Wildl. Serv., Spec. Sci. Rep. Fish. 169.) OVCHINNIKOYV, V. V. 1966. [Marlin—new object of a fishery]. Ryb. Khoz. 1:11-12. [In Russian.] PENRITH, M. J., and M. L. WAPENAAR. 1962. The marlins (Makaira spp.) at the cape. J. Sci. Soc. Univ. Capetown 5:33-35. ROBINS, C. R. 1974a._ The validity and status of the roundscale spearfish, Tetrapturus georgei. In Richard S. Shomura and Francis Williams (editors), Proceedings of the International Bill- fish Symposium, Kailua-Kona, Hawaii, 9-12 August 1972, Part 2. Review and Contributed Papers. U.S. Dep. Comm., NOAA Tech. Rep. NMFS SSRF-675, p. 54-61. 1974b. Synopsis of biological data on the longbill spear- fish, Tetrapturus pfluegeri Robins and de Sylva. In Richard S. Shomura and Francis Williams (editors), Pro- ceedings of the International Billfish Symposium, Kailua-Kona, Hawaii, 9-12 August 1972, Part 3. Species Synopses. U.S. Dep. Comm., NOAA Tech. Rep. NMFS SSRF. ROBINS, C. R., and D. P. DE SYLVA. 1961. Description and relationships of the longbill spear- fish, Tetrapturus belone, based on western North Atlantic specimens. Bull. Mar. Sci. Gulf Caribb. 10:383-413, 5 figs. (1960). 1963. A new western Atlantic spearfish, Tetrapturus pfluegeri, with a redescription of the Mediterranean spearfish, Tetrapturus belone. Bull. Mar. Sci. Gulf Ca- ribb. 13:84-122, 5 figs. ROYCE, W. F. 1957. Observations on the spearfishes of the Central Pacific. U.S. Fish Wildl. Serv., Fish. Bull. 57:497-554. RYBOVICH, J. 1965. Sportfisherman [boat]. Jn McClane, A. J. (editor), McClane’s standard fishing encyclopedia, p. 851-862. Holt, Rinehart and Winston, N.Y., 1058 p. STRASBURG, D. W. 1970. A report on the billfishes of the central Pacific. Bull. Mar. Sci. 20:575-604. TINSLEY, R. 1964. The sailfish—swashbuckler of the open seas. Univ. Fla. Press, Gainesville, 216 p. UEYANAGI, S., S. KIKAWA, M. UTO, NISHIKAWA. 1970. Distribution, spawning, and relative abundance in the Atlantic Ocean. Bull. Far Seas Fish. Res. Lab. 3:15-55. [In Japanese with English summary.] and Y. 33 WILLIAMS, F. 1970. The sport fishery for sailfish at Malindi, Kenya, 1958-1968, with some biological notes. Bull. Mar. Sci. 20:830-852. WILSON, C. L., and W. H. MATHEWS (editors). 1970. Man’s impact on the global environment. MIT Press, Cambridge, 319 p. WISE, J. P., and J. C. LE GUEN. 1969. The Japanese Atlantic long-line fishery, 1956-1963. Proc. Sympos. Oceanogr. Fish. Res. Trop. Atlantic —review paper and contribution, UNESCO/FAO, p. 317-347. CONTRIBUTED PAPERS Section 1.—Species Identification . The Paleontology of Billfish—The State of the Art HARRY L. FIERSTINE- ABSTRACT The major osteological features are described for living billfishes. All billfish remains are reviewed critically and some questionable forms are placed in Xiphioidei Incertae Sedis (uncertain status). The remaining xiphioids are placed into three families: Istiophoridae, Xiphiidae, and Xiphiorhynchidae. A new undescribed xiphiid from Mississippi shows that the billfish lineages must have diverged prior to the Eocene. Areas of research are suggested that will help place the paleontological studies on a more secure foundation. Although billfish fossils have been known for over 130 yr (Agassiz, 1838), Regan (1909) and Berg (1940) have been the only ones to summarize the paleon- tological knowledge of this important group. This paper reviews all fossil groups that are generally considered to be billfish and separates the question- able from the unquestionable forms. In order to put the paleontological and phylogenetic discussion ona firm foundation, I have summarized some of the major osteological features. In addition, I have pointed out some areas of research that will aid fu- ture paleontological studies. OSTEOLOGICAL INFORMATION Since crania, rostra, and vertebrae are the most common billfish structures found in the fossil record, the following review of recent osteology will em- phasize them. Various authors (Gregory and Conrad, 1937; Nakamura, 1938; Nakamura, Iwai, and Matsubara, 1968; Ovchinnikov, 1970) have shown that the rostra, skull, and vertebrae differ greatly between the Xiphiidae (swordfish), on the one hand, and the Istiophoridae (marlin, sailfish, and spearfish), on the other hand. In general, the skeleton is lighter and ‘Biological Sciences Department, California Polytechnic State University, San Luis Obispo, CA 93407, and Research As- sociate, Vertebrate Paleontology, Natural History Museum of Los Angeles County, Los Angeles, CA 90007. 34 less ossified in the Xiphiidae than in the Is- tiophoridae. The swordfish (Fig. 1) has a flattened rostrum, a short occipital region of the skull, and a one-piece lower jaw without a symphyseal joint. The istiophorids (Fig. 2) have a rounded rostrum, a comparatively longer occipital region, and a lower jaw with a predentary bone and a symphyseal joint. The vertebrae (Fig. 3) of the swordfish (when com- pared with the istiophorids) lack the overlapping processes, the centra are more cube-like than elon- gate, and the caudal skeleton (Fig. 4) has more separate bones (Fierstine and Applegate, 1968; Fierstine and Walters, 1968). Comparative osteology has been little help in dis- tinguishing between the various members of the fam- ily Istiophoridae. Tetrapturus and Istiophorus have 12 + 12 = 24 vertebrae and Makaira has 11 + 13 = 24 vertebrae. Since only isolated vertebrae have been found in the fossil record for istiophorids, this vertebral difference has not been useful to paleon- tologists. In general, there is generic similarity in bone morphology. In Makaira the bones are usually more massive than the other genera and the vertebral centra are much wider anteriorly (Fig. 5) than posteriorly (Nakamura et al, 1968). The bones of the branchial apparatus and limb girdles have been studied by Nakamura (1938) and Nakamura et al (1968), and they have very briefly discussed the similarities and differences between the various species. These studies will prove useful when complete fossil skulls of istiophorids are found or when individual bones are recognized. Figure 1.—Swordfish (Xiphias gladius) skull. A. Dorsal view. B. Lateral view. (From Gregory and Conrad, 1937.) REVIEW OF THE FOSSIL RECORD Generally, taxonomists (Berg, 1940; Regan, 1909; and Romer, 1966) recognize five billfish families: Blochiidae, Istiophoridae, Paleorhynchidae, Xiphiidae, and Xiphiorhynchidae. I will use these families as a starting point for the following discus- sion. I agree with Gosline (1968, 1971) that these 35 Figure 2.—Striped marlin (Tetrapturus audax) skull. A. Dorsal view. B. Lateral view. _veucal sore an. paremal LYLE 0D YSIS neural SAne axerior reutal WN Zygapoply sis OSL. TYG. aneriot neural zygapopys's Xiphias Figure 3.—Trunk vertebrae of billfish. (From Gregory and Conrad, 1937.) families should be placed in their own suborder, the Xiphioidei, within the Order Perciformes. I have neglected to include the family Luvaridae within the Xiphioidei because I do not believe it belongs there (it has a peculiar vertebral column and no rostrum) and because it has no fossil record. Istiophotus Figure 4.—Caudal skeletons of billfish. (From Gregory and Conrad, 1937.) Figure 5.—Two successive caudal vertebrae from a black marlin (Makaira indica) showing the transverse flanges (Tr) that project from each centrum. 36 The Blochiidae contains two distinct fossil forms, Blochius longirostris and what I call the ‘‘Cylin- dracanthus group’’. Complete skeletons of Blochius (Fig. 6) have been found in the Lower Eocene de- posits of Monte Bolca, Italy. The skeletons are about 1 m long and exhibit many billfish characters such as: a round and elongate rostrum, a low ver- tebral number, elongate vertebrae, and a deeply forked caudal fin. To the best of my knowledge no one has critically studied Blochius since Woodward (1901) published his catalogue of fossil fishes. Figure 6.—A. Reconstruction of Paleorhynchus glarisianus. B. Reconstruction of Blochius longirostris. (From Gregory and Conrad, 1937; after Woodward, 1901.) The “‘Cylindracanthus group” (A glyptorhynchus, Congorhynchus, Cylindracanthus, Glyptorhyn- chus, Hemirhabdorhynchus, etc.) are all known by small, cylindrical, elongate structures (Fig. 7) that are thought to be rostral tragments of a Blochius-like fish (Carter, 1927). A few vertebrae have been attributed to the ‘‘Cylindracanthus group’’ because they were found associated with the rostra (Leriche, 1910), but the evidence that they belong to the “Cylindracanthus group’ is simply circumstantial. In order to tidy up the billfish classification, I have chosen (Fierstine and Applegate, in press) to put the “Cylindracanthus group’? and Blochius into the Xiphioidei Incertae Sedis. Although the establish- ment of a category with uncertain affinities avoids the responsibility of making a precise taxonomic decision, it emphasizes our lack of knowledge of its members. ‘ The Istiophoridae contains the living genera /s- tiophorus, Makaira, and Tetrapturus, and the fossil genera Brachyrhynchus, and possibly Acestrus. Acestrus (Fig. 8) is only known from the Early Eocene and the remains consist of the posterior part of skulls. Casier (1966) felt that these crania be- longed to a billfish, but he also noted the similarity to the extinct scombrid, Scombrinus. The cranial fragments of Acestrus are quite small, only 50-60 mm Figure 7.—Rostra of the ‘‘Cylindracanthus group’’ A, B. Cylindracanthus rectus. C, D, E. Aglyptorhynchus venablesi F. Aglyptorhynchus sulcatus. (From Casier, 1966.) in length. It is possible that these small skulls belong to one of the small spearfishes. Three species of Brachyrhynchus have been described from rostra found in the Eocene of Belgium and the Pliocene of Italy. Woodward (1901) thought that Brachyrhyn- chus was probably identical with /stiophorus. Based upon the figures that I have seen, I agree that Brachyrhynchus belongs to an extant genus of the Istiophoridae. Most paleontologists (Woodward, 1901; Leriche, 1910; Casier, 1966) seem to have lumped all living istiophorid species into a single genus (Istiophorus or Tetrapturus) and to the best of my knowledge, Fierstine and Applegate (1968) have been the only paleontologists to try to place the fossils into one or more of the three extant genera. Our attempt was not too fruitful because of the lack of comparative os- teological studies on the living forms. Nevertheless, we recognized a predentary bone and a rostrum (Fig. 9) from the Miocene of California as belonging to Makaira sp. The identifications were based on the fact that these structures were much larger and more massive than the similar structures in Istiophorus and Tetrapturus. 37 Figure 8.—Diagrams of the occipital region of several scombroids and xiphioids. A. Wetherellus. B. Scom- brinus. C. Acestrus sp. D. Acestrus ornatus. E. Xiphiorhynchus. (From Casier, 1966.) Figure 9.— Makaira sp. from the middle Miocene of California. Rostrum, lateral view (A) and dorsal view (B). Predentary, lateral view (C) and dorsal view (D). (In part from Fierstine and Applegate, 1968.) a ! PE ypaepyyy 5| si w sssitieee i Unistivetin Ft cal eine u > fat olan cl rerlsn i nolan strata liable 1 ‘l vndin ME tanh z Lay tutrghentin | ¥ nuihng ak 38 The Paleorhynchidae (Fig. 6) comprises five gen- era (Enniskillenus, Homorhynchus, Hemirhynchus, Paleorhynchus, ana Pseudotetrapturus) that are found from the Eocene to the Oligocene of Europe. One species, Pseudotetrapturus luteus, reaches up to 4m in length (Danil’chenko, 1960), although other species usually are no longer than | m in length. Their vertebral count varies from 45 to 60. Accord- ing to Danil’chenko (1960), P. luteus resembles Te- trapturus in dimensions and body form and in the structure of the elongated snout, but it differs from Tetrapturus in the far greater number of vertebrae, the much longer lower jaw, the more dorsal position of the pectoral fins, and the presence of large scales. Since I feel that the resemblances to the istiophorids are probably a result of convergence, I choose to put them in the Xiphioidei Incertae Sedis. The family Xiphiorhynchidae is known from five species found in the Eocene of Africa, America, and Europe. The original description was from cranial fragments and subsequently various rostra were thought to be conspecific with the cranial fragments (Wocdward, 1901). The crania (Fig. 10) are similar in proportions to those found in the Istiophoridae. Re- cently the Los Angeles County Museum of Natural History was given a large rostrum and two as- sociated vertebrae (Figs. 11, 12) which belong to a new species of Xiphiorhynchus (Fierstine and Ap- plegate, in press). One vertebra, an abdominal, is similar in size and shape to an abdominal vertebra of a black marlin (Makaira indica), whereas the other vertebra, a caudal, is similar in shape to that of a swordfish. Both vertebrae are strongly ossified like Figure 10.—Semidiagrammatic reconstruction of Xiphiorhynchus priscus. A. Dorsal view of skull. B. Lateral view of opercular region. (From Casier, 1966.) Oc RoE Figure 11.—Rostrum of Xiphiorhynchus sp. from the Eocene of Mississippi. A. Lateral view. B. Dorsal view. C. Ventral view. D. Cross-section taken 220 mm from distal tip. E. Cross-section taken 170 mm from distal tip. My eTAC | 1 40 those of the Istiophoridae. The large rostrum is simi- lar in size and shape to that of the genus Makaira except that it is more flattened at its base. In cross- section, the xiphiorhynchid bill (Fig. 11) has a cen- tral longitudinal nutrient canal as well as two or more pairs of lateral nutrient canals. Istiophorids have only one pair of lateral longitudinal canals and lack a central canal. Xiphiids have a central longitudinal canal with only one pair of lateral canals. In short, this new species of Xiphiorhynchus seems to be in- termediate to both the Istiophoridae and the Xiphiidae. The Xiphiidae has a poor fossil record and this may be due to the poor ossification of its bones. Leriche (1910) identified one caudal vertebra from the Oligocene of Belgium as Xiphias rupelensis and it is similar to the hypural plate of Xiphias gladius. Most references to fossil Xiphiidae refer to the “Cylindracanthus group’’ or to the Istiophoridae. Recently Shelton Applegate of the Los Angeles County Museum of Natural History found a rostrum in the Eocene of Mississippi. It is 750 mm long, is depressed, and has across section at its base similar to a double-bladed axe. Distally the sharp lateral edges become blunt and the edge has a scalloped margin. Although the rostrum is unique, I strongly feel that it belongs to an yet unknown xiphiid. In summary then, the classification of billfish should be: ORDER PERCIFORMES SUBORDER XIPHIOIDEI FAMILY ISTIOPHORIDAE (? Acestrus, Brachyrhynchus, Istiophorus, Makaira, Tet- rapturus ) FAMILY XIPHIORHY NCHIDAE (Xiphiorhynchus) FAMILY XIPHIIDAE (Xiphias, and unde- scribed Eocene genus) XIPHIOIDEI INCERTAE SEDIS FAMILY PALEORHYNCHIDAE (En- niskillenus, Hemirhynchus, Homorhynchus, Paleorhynchus, Pseudotetrapturus) FAMILY BLOCHIIDAE (Blochius, ? “‘Cylindracanthus group’’) Figure 12.—Two vertebrae of Xiphiorhynchus sp. from the Eocene of Mississippi. A. Lateral view of abdominal vertebra. B. Ventral view of abdominal vertebra. C. Lateral view of caudal vertebra. D. Ventral view of caudal vertebra. At this time it is difficult to propose any phylogenetic scheme. Evidence seems to suggest that at least three billfish groups had differentiated and were living contemporaneously during the Eocene. Members of the recent genera were living in Miocene seas and they may be conspecific with those that are alive today. Whatever form was the common ancestor to the istiophorid and xiphiid lineages had to be in existence prior to the Eocene. AREAS OF RESEARCH Comparative osteological studies on recent bill- fish are needed in order to reasonably evaluate the fossil forms. Good osteological collections are rare because museums and universities lack the neces- sary storage space; thus they usually avoid the prep- aration of large skeletons. Therefore, my first suggestion would be for more skeletons. A study of the relative size and dimensions of the rostra and vertebrae would be very useful. Since these struc- tures are usually found separate from the rest of the skeleton, simple comparative morphometric data _ would aid their identification. Even though paleon- tologists have placed importance on the histology of fossil bills, the placement and number of nutrient canals and the structure of the denticles are not known for many of the recent forms. The functional anatomy of the feeding apparatus and the method of locomotion are not known. For example, the function of the predentary bone has been surmised (Fierstine and Applegate, 1968) and the role of the bill itself is just conjecture (Wisner, 1958; Tibbo, Day, and Doucet, 1961). The presence of the predentary bone may be an adaptive feature for large “‘slab-sided’’ fish with elongated upper or lower jaws. Aspidorhynchid holosteans (Fig. 13) have a predentary bone (Orlov, 1964; Zittel, 1932) and the extinct clupeiform suborder Saurodontoidei has an edentulous predentary which extends the lower jaw well beyond the upper (Bardack, 1965). Neither of these groups are thought to be directly related to each other or to the istiophorids (Green- wood, Rosen, Weitzman, and Myers, 1966; Gosline, 1968, 1971). No one has reliably measured the swimming speed of a billfish or analyzed their swimming movements. It is fairly obvious that the size and behavior of these fish are difficult barriers, but they could be over- come. A better understanding of the feeding and locomotory apparatuses would help us explain the differences between the istiophorids (rounded bill, 4] predentary bone, elongate centra with overlapping processes, fused caudal skeleton) and the xiphiids (depressed bill, no predentary bone, cube-like centra with no overlapping processes, no pelvic fins). . a cs aes ; No, SSE Bee 5 Se Figure 13.—Two other examples of fish with predentary (pmd) bone. A. Aspidorhynchus acutirostris from the Jurassic of Solenhofen, Germany. (From Zittel, 1932.) B. Unidentified saurodontid. Age (probably Cretaceous) and location unknown. The European fossil billfish need to be studied by someone who is familiar with the recent forms. There is no fossil group that does not need review. What is Brachyrhynchus? Is it a synonym of some recent istiophorid? Is Acestrus an istiophorid? Paleorhynchids are now well-known from Russia (Danil’chenko, 1960). Their large size and body shape may be adaptive features that result from con- vergence and are not a result of any relationship to the xiphioids. Since their upper and lower jaws are nearly equal in length, the paleorhynchids remind me of a huge needlefish (Order Beloniformes). Are the smaller paleorhynchids just the juveniles of the much larger Pseudotetrapturus luteus? If nothing else, the quality of the illustrations of P. luteus needs to be improved. The study of Blochius would be especially reward- ing. Of all the uncertain groups, it seems to be the most likely candidate to be included in the Xiphioidei proper. Dr. George Myers (pers. comm.) once told me that Blochius had a predentary bone. No mention is made of this structure in the literature. In addition Blochius needs to be redrawn, as all available figures stem from a diagrammatic line drawing in Woodward (1901). Figure 14.—Cross-section of a rostrum of Glyptorhynchus sp. from the Miocene of California. A. Low power. B. Medium power. C. High power. 42 The ‘‘Cylindracanthus group” is currently in tax- onomic chaos. Casier (1966) divided the group into two parts; he placed one group in the family Blochiidae of the Order Heteromi (=Notacanthi- formes) and the other group in the family Xiphiidae of the Order Scombromorphi (=?Scombroidei). No explanation was given as to why there was a re- lationship to the Order Notacanthiformes. Carter (1927) showed that a Cylindracanthus rostrum was similar histologically to a bill fragment of Blochius and he also showed that it was similar to a spine of the living trunkfish, Ostracion. Does this mean that the Cylindracanthus structures are bills or spines? What other structures would have a similar histology? The microscopic interpretation is very equivocal. Carter (1927) stated that the Cylindracan- thus rostrum was composed of dentine. Tor Orvig (pers. comm.) interpreted Cylindracanthus bills to be composed of acellular bone. Rainier Zangerl (pers. comm.) interpreted a photomicrograph (Fig. 14) of a ground thin section of a Glyptorhynchus rostrum as dentine whereas, Melvin Moss (pers. comm.) has suggested that the same structure is composed of acellular bone. The rostra of the ‘‘Cylindracanthus group’’ are characterized by two or more rows of ‘‘alveoli’’ (Fig. 15) on one surface, the supposed ventral sur- face. The ‘‘alveoli’’ are thought to have contained denticles, but no tooth-like structures have ever been present. I personally think that most, if not all, o i= oa / Q Figure 15.—Rostrum of Glyptorhynchus sp. from the Miocene of California. A. Lateral view. B. Ventral view showing two alveolar grooves. 43 of the ‘‘Cylindracanthus group”’ rostra will prove to be fin spines. These structures are too numerous and common in the fossil record for each to represent an individual fish. Much of our lack of knowledge of fossil billfish stems from the paucity of comparative anatomical studies. Once this foundation is built there are many intriguing problems to solve in the fossil record. It is my hope that this paper has served as a stimulus for others to enter an uncrowded research field. LITERATURE CITED AGASSIZ, L. 1838. Recherches sur les Poissons fossiles. Neuchatel. 5:89-92. BARDACK, D. 1965. Anatomy and evolution of chirocentrid fishes. Univ. Kans. Paleontol. Contrib., Vertebrata, Art. 10, 87 p. BERG, L.S. 1940. Classification of fishes both recent and fossil. (In Rus- sian and English.) Trav. Inst. Zool. Acad. Sci. URSS, Vol. 5(2):87-517. CARTER, J. 1927. The rostrum of the fossil swordfish, Cylindracanthus Leidy (Coelorhynchus Agassiz) from the Eocene of Nigeria (with an introduction by Sir Arthur Smith Wood- ward). Geol. Survey Nigeria, Occ. Paper no. 5:1-15. CASIER, E. 1966. Faune ichthyologique du London clay. British Mus. (Nat. Hist.), Lond., 2 vols., 496 p., 68 plates. DANIL’CHENKO, P.G. 1960. Bony fishes of the Maikop Deposits of the Caucasus (translated from Russian). Akad. Nauk SSSR, Tr. Paleon- tol. Inst. 78, 247 p. (Translated by Israel Program Sci. Transl., 1967, 247 p.) FIERSTINE, H.L., and S.P. APPLEGATE. 1968. Billfish remains from Southern California with remarks on the importance of the predentary bone. Bull. South. Calif. Acad. Sci. 67:29-39. In press. Xiphiorhynchus kimblalocki, a new species of fos- sil billfish from the Eocene of Mississippi. Bull. South. Calif. Acad. Sci. FIERSTINE, H.L., and V. WALTERS. 1968. Studies in locomotion and anatomy of scombroid fishes. Mem. South. Calif. Acad. Sci. 6:1-31. GOSLINE, W.A. 1968. The suborders of perciform fishes. Proc. U.S. Natl. Mus. 124(3647):1-78. 1971. Functional morphology and classification of teleostean fishes. U. Hawaii Press, Honolulu, 208 p. GREENWOOD, P.H., D.E. ROSEN, S.H. WEITZMAN, and G.S. MYERS. 1966. Phyletic studies of Teleostean fishes, with a provi- sional classification of living forms. Bull. Am. Mus. Natl. Hist. 131:339-455. GREGORY, W.K., and G.M. CONRAD. 1937. The comparative osteology of the swordfish (Xiphias) and the sailfish (Istiophorus). Am. Mus. Novitates, 952:1-25. LERICHE, M. 1910. Les Poissones oligocenes de la Belgique. Musee Royal d’Historie naturelle de Belgique, Memoirs. 5:231-363. NAKAMURA, H. 1938. Report of an investigation of the spearfishes of Formo- san waters. Reports of the Taiwan Government-General Fishery Experiment Station 1937, No. 10. (U.S. Fish Wildl. Serv., Spec. Sci. Rep. Fish. 153, 46 p. Translated from Japanese by W.G. VanCampen in 1955). NAKAMURA, I., T. WAI, and K. MATSUBARA. 1968. A review ofthe sailfish, spearfish, marlin and swordfish of the world. (In Japanese.) Misaki Mar. Biol. Inst., Kyoto Univ., Spec. Rep. 4, 95 p. ORLOV, YU. A. (EDITOR) 1964. Fundamentals of Paleontology. Vol. 11, Agnatha, Pisces. Moscow, 825 p. (Translated by Israel Program Sci. Transl., 1967, 825 p.; available U.S. Dep. Commer., Clearinghouse for Fed. Sci. and Technol. Information, Springfield, VA, as TT66-51147.) OVCHINNIKOV, V.V. 1970. Swordfishes and billfishes in the Atlantic Ocean. Ecol- ogy and functional morphology. Atl. Sci. Res. Inst. Fish. Oceanogr., 77 p. (Translated by Israel Program Sci. 44 Transl., 1971, 77 p.; available U.S. Dep. Commer., Natl. Tech. Inf. Serv., Springfield, VA, as TT71-50011.) REGAN, C.T. 1909. XI—On the anatomy and classification of the scom- broid fishes. Ann. Mag. Nat. Hist., Ser. 8(3):66-75. ROMER, A:S. 1966. Vertebrate paleontology. 3rd ed. Univ. Chicago Press, Chicago, 468 p. TIBBO, S.N., L-R. DAY, and W.F. DOUCET. 1961. The swordfish (Xiphias gladius L.), its life-history and economic importance in the northwest Atlantic. Fish. Res. Board Can., Bull. 130, 47 p. WISNER, R.L. 1958. Is the spear of istiophorid fishes used in feeding? Pac. Sci. 12:60-70. WOODWARD, A:S. 1901. Catalogue of the fossil fishes in the British Museum (Nat. Hist.) Part 4, 636 p., 19 plates. ZITTEL, K.A. VON 1932. Text-book of paleontology. Vol. 2. (Translated by Charles R. Eastman). Macmillan and Co. Ltd., Lond., 464 p. Some Aspects of the Systematics and Distribution of Billfishes IZUMI NAKAMURA! ABSTRACT Until recently the classification of billfishes (Xiphiidae and Istiophoridae) was confused. Recent workers have consolidated the nominal species and reduced the number of species considerably. A key, with figures, is presented which includes two families, four genera, and 11 species. Makaira mazara is considered distinct from M. nigricans because of consistent differences in the pattern of the lateral line system. Tetrapterus platypterus is tentatively separated from T. albicans although existing differences are minor and could be referable to the subspecific level. The worldwide distribution of billfishes is given; distributions are based primarily on data from the Japanese longline catch for 1964-69. Despite their importance to sport and commercial fisheries and the large size attained by many of them, the fishes of the superfamily Xiphiicae (families Xiphiidae and Istiophoridae) have been little under- stood and until recently their systematics have been highly confused. The separation and nomenclature of the species of billfishes has been a difficult prob- lem; this arises partly because the structure and characteristics of some “‘species’’ are quite similar, and also because the original description of most of the species has been inadequate. Thus, it is impossi- ble to identify the different species immediately from the original descriptions. Goode (1880, 1882) classified the billfishes of the world into one family, two subfamilies, four genera, and 17 species. Jordan and Evermann (1926) clas- sified the billfishes into two families, four genera, and 32 species. Recently LaMonte and Marcy (1941) and Rosa (1950) classified the billfishes into four genera, 13 species and four subspecies, and four genera, 15 species and four subspecies, respectively, in their revisional works. Several authors have con- tributed substantially to the knowledge of the Indo- Pacific billfishes (e.g. Nakamura, 1938, 1949; Royce, 1957; Howard and Ueyanagi, 1965). Robins and de Sylva (1960, 1963) provided comprehensive discussions of the systematics of the Atlantic bill- fishes. Nakamura, Iwai, and Matsubara (1968) classified the billfishes of the world into two families, four genera, and 11 species, using external and internal characters such as shapes of snout, fins, skull, ver- tebrae, viscera and nasal rosette, compression of body, position of anus, pattern of lateral line system, arrangement of scales, relative position of second dorsal and second anal fins, color and color patterns. The key given below is modified after that paper. Key to Families, Genera and Species of Billfishes (See Figure 1 for illustration of key characters) la. No pelvic fin. A single caudal keel on side. Snout long and swordlike in shape and depressed in cross-sectional view. No scales on body. No teeth. Base of first dorsal fin short and well separated from base of second dorsal fin (Xiphiidae, Xiphias) ....... ‘Fisheries Research Station, Kyoto University, Maizuru, Kyoto 625, Japan. .... Swordfish, Xiphias gladius Linneaus, Figure 1A ‘DOIPUL “WM suvousiu “pot DADz=DUI "WY XDpnv - 7 “A snpiq]D ‘[ °9) Madanpfd *[ * auojag (a Siisossnéduv °f *@ suvoiqiy "J “dD snaajdkjnjd +] -@ snipyjs “x Ww “AQ¥ 9} UI posn sjutod jueyOdu ay] MOUS SMOLIY “uly [e10]9Ed JO aSeq OY} Je UdYe} SUOIIDES JO SMAIIA JBUOI}DAS-SSOID MOYS SaIdads Yd¥A JO IYBL dy) 0} SoINSIY “soysipfiq Jo souvivodde jeussxq—"] ondi4 46 3a. 3b. 4a. 4b. Sa. 5b. 6a. 6b. Ta. 8a. Pelvic fin present. A pair of caudal keels on each side. Snout somewhat shorter and nearly rounded in cross-sectional view. Body covered with small elongated bony scales. Many small teeth. Base of first dorsal fin long and close to base of second dorsal fin @istic phoridae) big wre ve pB = Reape rere raicyeyeaereks epsye chrsiahe cee 4. ssentwortens ebeke peireiseyeasys ielcre*reeuayete vid enoreteee 2 . First dorsal fin considerably higher than body depth at level of mid-body. Pelvic fin rays very long with well developed membrane (/stiophorus), Figure 1B, 1C ............... 3 . First dorsal fin only slightly higher to slightly lower than body depth at level of mid-body. Not sail-like in shape. Pelvic fin rays not as long, with moderately developedimembranes, Pig ure! [aK Se) eo aS RAEN ea MM es cen ac asian een rata ch Pah cpa 4 Pectoral fin and caudal fin short in specimens of about 90 cm body length. Dis- tributedsnsthe#indo=Pacific Oceanic leek ttces thc eo he creas foe chee nem orotate 5.10 aa OIC ec eee Indo-Pacific sailfish, /stiophorus platypterus (Shaw and Nodder), Figure 1B Pectoral fin and caudal fin long in specimens of about 90 cm body length. Distributed in the Atlantic Ocean ...... Atlantic sailfish, /stiophorus albicans (Latreille), Figure 1C Height of anterior part of first dorsal fin slightly higher than or nearly equal to body depth. Body well compressed. External margin of head between preorbital and origin of first dorsal fin slightly elevated or not elevated (Tetrapturus), Figure 1, D-H ..... 5 Height of anterior part of first dorsal fin lower than body depth. Body not well compressed. External margin of head between preorbital and origin of first dorsal rinehighliyrelevatedi(Makaira)y Figure ls TeKo eee. et ea ees oe eee dee 9 Anterior fin rays of first dorsal fin slightly higher than the remainder; latter nearly equal in height to end of the fin. Anus situated far in front of origin of first anal fin. Second anal fin situated somewhat before second dorsal fin, Figure 1, D-F ............. 6 Anterior rays of first dorsal fin somewhat higher than remainder of the fin; the height decreasing gradually posteriorly. Anus situated near origin of first anal fin. Second anal fin situated about under second dorsal fin, Figure 1, G-H ..................05. 8 Pectoral fin width less than 6.5 times pectoral fin length and 1.6-2.5 times head ESET, on See eae ieee ae Gea 4 eS ob RO URC TL ATEN cg RRR res Re Ri A ae Re he Ra 7 Pectoral fin width more than 6.5 times pectoral fin length and 1.0-1.4 times head lensthe awe fee Longbill spearfish, Tetrapturus pfluegeri Robins and de Sylva, Figure 1F Snout short; bill length about 1.6 times head length................0.000000000020005 BOR OV a: PORCH EN fave cy Ath Ee aN Shortbill spearfish, Tetrapturus angustirostris Tanaka, Figure 1D snoutlongibilliength abouti22=1e5timesvhead! length’ 4, 42s4c2 ss eeeeie tee see soe COIS CO ROL IOI Ser CRIT TEPER Mediterranean spearfish, Tetrapturus belone Rafinesque, Figure 1E Pectoral fin wide, its tip rounded. Tips of first dorsal fin and first anal fin [RUN eer c oo ee es OM Up A EO GRO OE hee nen White marlin, Tetrapturus albidus Poey, Figure 1G 47 8b. [OLONIO LSA “a o-oo Coo GCG) on SNES Te cer 9a. 9b. 10a. Lateral line system with simple loops Pectoral fin can be folded back against side of body Pectoral fin rigid cannot be folded back against side of body Pectoral fin narrow, its tip pointed. Tips of first dorsal fin and first anal fin Striped marlin, Tetrapturus audax (Phillipi), Figure 1H 10 Black marlin, Makaira indica (Cuvier), Figure 1K Bee ER yD Once DED coe Indo-Pacific blue marlin, Makaira mazara Jordan and Snyder, Figure 11 10b. CLASSIFICATION PROBLEMS WITH SOME SPECIES OF BILLFISHES While re-examining the study of the world bill- fishes made by Nakamura, et al. (1968), C.L. Hubbs (personal communcation) has made me aware of the critical opinions expressed by some researchers about this work. Hubbs stated his views as follows: “Two of the main problems involve the name we should use for California species of /stiophorus and Makaira. 1 see that you have definitely listed sepa- rately /stiophorus platypterus and I. albicans and also Makaira nigricans and M. mazara. In recent correspondence with Dr. Robins I find that he feels that these two pairs of species, as you recognize them, are either identical or only subspecifically separable. In both cases he seems to find that the differences are rather definitely related to the fact that the species grow larger in the eastern Pacific than they do in the Atlantic. In the case of the two blue marlins, he says that he has found indications that the degree of network of the lateral line system and the differences in the osteology that have been used are both dependent on size of fish, but that probably does not explain all the differences.” In Nakamura, et al. (1968), both/. platypterus and I. albicans were recognized only tentatively as valid species; principally because data were lacking to establish with certainty whether the two forms were conspecific, subspecies, or distinct species. While data are still inadequate, I now feel that both forms can be recognized as subspecies. I consider that some distinctions noted between these two forms, especially in species of 90 cm, could be referable to subspecific status. These features include differ- ences in maximum body length attained, relative length of pectoral fin (Fig. 2) and spread of caudal fin 48 sof 5 QS? e fo 0 [ eee & 8 Al apn —_ ° = 0,0 ok B ee 0 100 200 cm BODY LENGTH 72 Figure 2.—Relationships between pectoral fin and body length in sailfish. Open circles show data from the Atlantic sailfish and solid circles show data from the Indo-Pacific sailfish. Data from Vick (1963) and Royce (1957) are in- cluded. (Fig. 3). Morrow and Harbo (1969) reported that analysis of morphometric and meristic characters of sailfish from various localities in the Atlantic, Pacific, and Indian Oceans indicated that the genus is monotypic, composed of a single species that shows remarkably little variation in the characters examined. Further study of anatomical, ecological, behavioral, and other biological aspects is necessary to clarify the problems of speciation in sailfish. Until this is achieved, I retain the use of /. platypterus for the Indo-Pacific sailfish and J. albicans for the At- lantic sailfish. I believe that both M. mazara and M. nigricans are distinct species chiefly because of differences in the pattern of the lateral line system. In the speci- mens I examined, the differences were constant with growth (Fig. 4). It should be pointed out, however, that the lateral line systems of individuals larger than SPREAD CAUDAL uo oOo ‘doen 200 100 BODY LENGTH Figure 3.—Relationship between spread of caudal fin and body length in sailfish. Open circles show data from the Atlantic sailfish and solid circles show data from the Indo-Pacific sailfish. Data from Vick (1963) and Royce (1957) are included. 200 cm body length of both species are difficult to observe, because the lateral line system is covered under the thick skin and scales. For specimens less than 100 cm body length of both species, the charac- teristic patterns of the lateral line systems are easily recognized. In the Yaizu Fish Market, which is rec- ognized as the world’s largest landing market for tuna longliners, I observed and was able to separate many specimens of M. mazara and M. nigricans on the basis of different patterns in the lateral line sys- tem. With large specimens in which the lateral line was covered, I could not distinguish the species. I consider that the differences in the lateral line sys- tem are important enough to warrant recognition of both species. Tetrapturus georgei Lowe was recognized by de Sylva (1972) as a valid species distributed in the western Mediterranean and off Spain and Morocco. Because of lack of specimens I have omitted consid- eration of T. georgei in this paper. DISTRIBUTION OF BILLFISHES The distribution of the billfishes discussed in the following sections is based primarily on unpublished data obtained from the Japanese longline catches made in the Pacific, Indian, and Atlantic Oceans. These data were made available by the Far Seas Fisheries Research Laboratory, Shimizu, Japan. The fishing grounds of the Japanese longliners ex- 49 tend from lat. 50°N to lat. 45°S in the Pacific Ocean, from the northern sectors of the Arabian Sea and Bay of Bengal to lat. 50°S in the Indian Ocean, and from lat. 50°N to lat. 50°S in the Atlantic Ocean. Xiphias gladius This species is distributed in the tropical and temperate waters of the Pacific, Indian, and Atlantic Oceans. Good commercial fishing grounds are lo- cated in the northwestern Pacific, off the Pacific coast of Mexico, off Ecuador, in the Arabian Sea, off Newfoundland, off southern Brazil, and the Gulf of Te cece moeemecete ase? Creecss cowes.. | ° { H SGieraes coc cdecccocccscce ts tree ee ee, oe ere ere La + oom oes x oc a a % 2 20 cc ececees comes ecccocccs . Pens rd Messascemete, sg a J Figure 4.—Variations with growth of the lateral line sys- tems of the Indo-Pacific blue marlin (A-G) and the Atlantic blue marlin (H-J). Body length: A. 17.7 cm, B. 81.0cm, C. 84.3 cm, D. 112.9cm, E. 119.5cm, F. ca. 185cm, G. ca. 260 cm, H. ca. 140 cm, I. 188.0 cm, J. ca. 205 cm. Figure 5.—Distribution of swordfish, Xiphias gladius, based on catch data from Japanese longline fishery during 1964-69. A. Good fishing grounds. B. Presumed northern and southern limits of swordfish. Guinea (Fig. 5). Based on data of commercial catches, the limits of distribution appear to be about lat. 5O°N to 35°S in the Pacific, lat. 45°S in the Indian Ocean, and lat. 45°N to 40°-45°S in the Atlantic (Fig. 5). This species is more abundant in coastal waters, but distribution is scattered and continuous in tropi- cal open sea areas. Istiophorus platypterus This species is distributed in the tropical and temperate waters of the Pacific and Indian Oceans. Good commercial fishing grounds are located in waters of the eastern tropical Pacific from Baja California to Ecuador, the Coral Sea and around New Guinea, the East China Sea, the adjacent wa- ters of southern India and Ceylon, and the Mozam- bique Channel (Fig. 6). The latitudinal limits of /. platypterus appear to extend from lat. 40°-45°N in the North Pacific and about lat. 40°S in the South Pacific, and in the Indian Ocean as far south as lat. 40°S. In the Japan Sea, sailfish migrate northward with the Tsushima Current during summer and mi- grate southward against the current during autumn. Istiophorus albicans This species is distributed in the tropical and temperate waters of the Atlantic Ocean. Good commercial fishing grounds are located in the Gulf of Mexico, the Gulf of Guiana, and the coastal waters off South America from Panama to Brazil (Fig. 6), The distributional limits are about lat. 40°N to lat. 35°-40°S in the Atlantic Ocean. Tetrapturus angustirostris This species is widely distributed in tropical and temperate offshore waters of the Indian and Pacific Oceans. Catches of this species are always low, except in the northwestern Pacific between lat. 15° and 30°N, where catches are relatively higher from about November through February (Nakamura, 1951; Royce, 1957; Ueyanagi, 1963). The distribu- tional limits are about lat. 35°N to 35°S in the Pacific and Indian Oceans (Fig. 7). Tetrapturus belone This species is distributed in the Mediterranean and Adriatic Seas (Fig. 7) and is relatively rare. It occurs most commonly in the central Mediterranean (de Sylva, 1972). This species is not taken commer- cially. Tetrapturus pfluegeri This species is known with certainty only from the western North Atlantic where it occurs from south- ern New Jersey to Venezuela and from Texas to Figure 6.—Distribution of fishes of genus /stiophorus based on catch data from Japanese longline fishery during 1964-69. A. Good fishing grounds for the Indo-Pacific sailfish. B. Good fishing grounds for the Atlantic sailfish. C. Presumed northern and southern limits of the Indo-Pacific sailfish. D. Presumed northern and southern limits of the Atlantic sailfish. A] Bi CH25 Figure 7.—Distribution of fishes of genus Tetrapturus based on catch data from Japanese longline fishery during 1964-69. A. Good fishing grounds for striped marlin, T. audax. B. Good fishing grounds for white marlin, T. albidus. C. Presumed distribution areas of the longbill spearfish, T. pfluegeri. D. Presumed distribution areas of the Mediterranean spearfish, T. belone. E. Presumed northern and southern limits of the striped marlin. F. Presumed northern and southern limits of the white marlin. G. Presumed northern and southern limits of the shortbill spearfish, T. angustirostris. Puerto Rico (Robins and de Sylva, 1963). Longbill Tetrapturus albidus spearfish have been caught off the east coast of the United States and in the Central and South Atlantic This species is distributed in the tropical and Oceans (Fig. 7). temperate waters of the Atlantic. Good fishing 51 grounds are located in the Gulf of Mexico, Carri- bean Sea, and the southwestern Atlantic (Fig. 7). The distributional limits are about lat. 45°N to lat. 40°S in the Atlantic Ocean. This species is caught in the Mediterranean Sea from Gibraltar to Italy (de Sylva, 1972). Tetrapturus audax This species is distributed in the tropical and temperate waters of the Indian and Pacific Oceans (Fig. 7). Based on catch data, the distributional pat- tern of this species in the Pacific is horseshoe-shaped with the base located along the central American coast. The latitudinal limits are about lat. 45°N to lat. 35°-40°S in the Pacific Ocean, as far south as lat. 45°S in the western South Indian Ocean and lat. 35°S in the eastern South Indian Ocean. Makaira mazara This species is distributed in the tropical and temperate waters of the Indian and Pacific Oceans. The Indo-Pacific blue marlin is the most tropical of the marlin species and it is primarily distributed in equatorial areas (Fig. 8). Good fishing grounds are located in the equatorial and tropical central Pacific Ocean, the South Pacific Ocean, and the equatorial Indian Ocean. The distributional limits are about lat. 45°N in the western North Pacific Ocean, lat. 35°N in the eastern North Pacific Ocean, lat. 35°S in the South Pacific Ocean, lat. 40°-45°S in the western South Indian Ocean and lat. 35°S in the eastern South Indian Ocean. Makaira nigricans This species is distributed in the tropical and temperate waters of the Atlantic Ocean and is the most tropical of the Atlantic billfishes. Good fishing grounds are located in the Gulf of Mexico, around the West Indies and off central Brazil (Fig. 8). The distributional limits are about lat. 40°N to lat. 40°S in the Atlantic Ocean. Makaira indica This species is distributed in the Indian and Pacific Oceans (Fig. 8). A few catches of this species have been recorded by fishermen from the Atlantic Ocean; however, the identifications have not been validated. It is conceivable that stray black marlin may invade the Atlantic Ocean by way of the Cape of Good Hope. In Figure 8, the dotted line shows the 60 AY 0 Rol —P Figure 8.—Distribution of fishes of genus Makaira based on catch data from Japanese longline fishery during 1964-69. A. Good fishing grounds for the Indo-Pacific blue marlin, M. mazara. B. Good fishing grounds for the Atlantic blue marlin, M. nigricans. C. Good fishing grounds for the black marlin, M. indica. D. Presumed northern and southern limits of the black marlin. E. Presumed northern and southern limits of the Atlantic blue marlin. G. Presumed invasion of the black marlin from the Indian Ocean to the Atlantic Ocean. or iw) presumed movement of black marlin from the Indian Ocean to the Atlantic Ocean. The black marlin, thus, is obviously a species of both tropical and temperate waters. Good fishing grounds are located in the East China Sea, Arafura Sea, Sulu Sea, Celebes Sea, Coral Sea, Formosa, northwestern Australia, Ecuador, and Pinas Bay in Panama (Fig. 8). The distributional limits are about lat. 40°N in the North Pacific and lat. 45°S in the South Pacific and Indian Oceans. ACKNOWLEDGMENTS I wish to acknowledge Drs. Shoji Ueyanagi and Shoji Kikawa of Far Seas Fisheries Research Laboratory for their advice and for providing catch and effort data from the Japanese tuna longline fishery. I am also indebted to Susumu Kato of Na- tional Marine Fisheries Service, Tiburon Fisheries Laboratory, for his help and review of the manu- script. LITERATURE CITED DE SYLVA, D.P. 1972. Check-list of the fishes of the North-East Atlantic and ofthe Mediterranean. Family Istiophoridae. Univ. Miami, Rosenstiel Sch. Mar. Atmos. Sci., 9 p. GOODE, G.B. 1880. Materials for a study of the swordfish. U.S. Comm. Fish and Fish., 8:287-394. 1882. The taxonomic relations and geographical distribution of the members of the swordfish family Xiphiidae. Proc. U.S. Natl. Mus. 4:415-433. HOWARD, J.K:, and S. UEYANAGI. 1965. Distribution and relative abundance of Billfishes (/s- tiophoridae) of the Pacific Ocean. Univ. Miami Inst. Mar. Sci., Stud. Trop. Oceanogr. No. 2, 134p., 38 maps inatlas. JORDAN, D.S., and B-W. EVERMANN. 1926. A review of the giant mackerel-like fishes. tunnies, 53 spearfishes and swordfish. Calif. Acad. Sci., Occas. Pap. 12:1-113. LAMONTE, F., and D.E. MARCY 1941. Swordfish, sailfish, marlin and spearfish. Int. Game Fish Assoc., Ichthyol. Contrib. 1(2):1-24. MORROW, J.E., and S.J. HARBO. 1969. A revision of the sailfish genus /stiophorus. Copeia 1969:34-44. NAKAMURA, H. 1938. Report of an investigation of the spearfishes of Formo- san waters. [In Jap.] Rep. Taiwan Gov.-Gen. Fish. Exp. Sta. 10:1-34. 1949. The tunas and their fisheries. [In Jap.] Takeuchi Shobo, Tokyo, 118 p. 1951. The tuna longline fishery and its fishing grounds. [In Jap.] Assoc. Jap. Tuna Fish. Coop., Tokyo, 144 p. NAKAMURA, L., T. IWAI, and K. MATSUBARA. 1968. A review ofthe sailfish, spearfish, marlin and swordfish of the world. [In Jap.] Kyoto Univ., Misaki Mar. Biol. Inst., Spec. Rep. 4:1-95. ROBINS, C.R., and D.P. DE SYLVA. 1960. Description and relationships of the longbill spearfish Tetrapturus belone, based on western North Atlantic specimens. Bull. Mar. Sci. Gulf Caribb. 10:383-413. 1963. A new western Atlantic spearfish, Tetrapturus pfleu- geri, with a redescription of the Mediterranean spearfish Tetrapturus belone. Bull. Mar. Sci. 13:84-122. ROSA, H., JR. 1950. Scientific and common names applied to tunas, mack- erels and spearfish of the world with notes on their geo- graphic distribution. Food Agric. Organ. U.N., Washing- ton, D.C. 235 p. ROYCE, W.C. 1957. Observations on the spearfishes of the central Pacific. U.S. Fish Wildl. Serv., Fish. Bull. 57:497-554. UEYANAGIL, S. 1963. A study of the relationships of the Indo-Pacific is- tiophorids. [In Jap.] Rep. Nankai Reg. Fish. Res. Lab. 17:151-165. VICK, N.G. 1963. A morphometric study of seasonal concentrations of the sailfish, Jstiophorus albicans, in the northern Gulf of Mexico, with notes on other Gulf Istiophorids. Texas A. & M. Univ., Res. Found. Proj. 286D:1-41. The Validity and Status of the Roundscale Spearfish, Tetrapturus georgei' C. RICHARD ROBINS? ABSTRACT A fourth Atlantic species of the istiophorid genus Tetrapturus was discovered in 1961 among commer- cial catches landed in Sicily, Portugal, and Spain. Subsequent efforts to obtain information have failed because the fishermen do not distinguish the species and it is apparently much less common than 7. belone in Sicily and 7. albidus in Spain and Portugal. The species is described in detail. Important distinguishing features are: the form of the scales on the midside, the shape of the lobes of the spinous dorsal and anal fins, the position of the anus, and the pectoral-fin length. The nomenclatural validity of Tetrapturus georgei Lowe is discussed and reasons are given for applying this name to the newly discovered species. In 1961 the author traveled to Sicily, Portugal, and Spain to study 95 specimens of istiophorid fishes that had been purchased and retained in commercial freezers for the purpose. Of 36 specimens examined in Sicily, 35 were Mediterranean spearfish, Tetrap-+ turus belone Rafinesque, and these formed the basis for the redescription of the species by Robins and de Sylva (1963). Of the remaining 59 specimens, 56 were white marlin, Tetrapturus albidus, which formed the basis of reports by Rodriguez-Roda and Howard (1962) and Robins (1974). Four specimens represented an unknown species of Tetrapturus, whose presence had been unsuspected. Based ona study of this material, Robins prepared and distributed a two page mimeographed leaflet requesting additional records and data. Inasmuch as the fishermen have never clearly distinguished the Mediterranean spearfish and the white marlin, it is not surprising that this additional spearfish should go undetected and no additional data have been forth- coming. This report describes the species here called the roundscale spearfish, and the scientific name Tet- rapturus georgei Lowe is applied to it in lieu of proposing a new name for it. ‘Contribution No. 1708 Rosenstiel School of Marine and At- mospheric Science, University of Miami. *School of Marine and Atmospheric Science, University of Miami, Miami, FL 33149. 54 TETRAPTURUS GEORGE! LOWE Roundscale spearfish Nomenclature. Lowe (1840:36-37) did little more than announce his intention to describe a new species of Tetrapturus by which he would com- memorate ‘‘by its specific name the valuable assis- tance rendered to the cause of ichthyology by Mr. George Butler Leacock.’’ The only data are: 1) that the specimen was from Madeira; 2) that its pectoral fin was proportionally twice as long as in the descrip- tion of 7. belone by Valenciennes, in Cuvier and Valenciennes (1831), and that its body was “‘clothed with large scales of a peculiar shape and nature.’’ No additional data were ever published, later accounts (Lowe, 1841:93; 1849:3) merely repeating the origi- nal. This was discussed by Robins and de Sylva (1960:397-398) who stated ‘‘The identity of T. geor- gii Lowe. . .will probably never be solved.”’ The discovery of an additional species from near Madeira requires reassessment of 7. georgei. Beyond the three points of fact mentioned above, the matter becomes an exercise in logic. Even the matter of the scales involves interpretation. Including the roundscale spearfish, as many as six species of Istiophoridae might occur in the vicinity of Madeira at least occasionally. According to Maul (in litt.), istiophorids are rare at Madeira and only appear during the summer. The white marlin, 7. albidus, is likely the most abundant, as is supported by data in Ueyanagi et al. (1970) and Robins (1974). Moreover, a photograph sent by Maul in 1961 was identified by Robins as that of a white marlin. (This and other photographs were destroyed in a fire in 1967, but a surviving letter from Howard to Maul, 3 March 1961, discussed this photograph in detail.) This species has long pectoral fins in adults, 19-27 percent of body length for eastern Atlantic speci- mens vs. 10-13 percent of body length in adults of T. belone (Robins and de Sylva, 1963, Table 4), these data agreeing well with point two in Lowe’s descrip- tion. Valenciennes, in Cuvier and Valenciennes (1831), made no mention of scales in 7. belone and thus there is no solid basis for judging Lowe’s use of “‘peculiar.’” Compared to the naked Xiphias or to more typical fishes, the long needle-like scales of most istiophorids are indeed peculiar. T. albidus is unique in the family for the unblemished record of its specific name. It has always gone under Poey’s name, although for many years it was referred to as Makaira and by some authors as Lamontella before Robins and de Sylva (1960) returned it to Tetrap- turus. If it is judged that T. georgei is most likely the white marlin, the author would petition the In- ternational Commission of Zoological Nomencla- ture to reject the earlier name T. Georgii Lowe and preserve the well known junior name 7. albidus Poey for this important game and food fish. The roundscale spearfish as noted below occurs in the eastern Atlantic, not far from Madeira, as wellas in the Mediterranean. No doubt it reaches Madeira and many, if not all, of the eastern North Atlantic records of 7. pfluegeri in Japanese literature (Ueyanagi et al., 1970) may be referable to it. Its pectoral-fin length varies from 20-26 percent of body length, also agreeing with Lowe’s value. Its scales along the sides are rounded with posterior spikes, thus being less specialized than other istiophorid fishes. Whether these less modified scales are more ‘“‘peculiar’’ depends on one’s viewpoint. T. georgei easily could apply to this species which otherwise has no scientific name. In the interests of avoiding the need for a new name in a family with a cluttered nomenclatural history and in the interest of avoiding any possibility of applying T. georgei to T. albidus the author here restricts the name T. georgei to the roundscale spearfish. Other species of Istiophoridae are judged to be less likely candidates. T. pfluegeri also has a long pectoral fin in adults (19-22 percent of body length) 50 though not so long as in the two species already discussed. Further, its occurrence as far east as the Azores (Ueyanagi et al., 1970: Fig. 7) may in fact be based on the roundscale spearfish. The sailfish, /s- tiophorus platypterus Shaw and Nodder, has a short pectoral fin in the small-sized Atlantic fishes (14-19 percent of body length), and its remarkable dorsal fin surely would have elicited a comment from Lowe. The blue marlin (Makaira nigricans) is rare in the eastern North Atlantic but does occur at Madeira. G.E. Maul, in a letter (24 February 1961) to John K. Howard, refers to istiophorids in excess of 1,000 Ib. These could be nothing else but blue marlin. This species has a fairly long pectoral fin (adults of Atlan- tic fish usually 18-24 percent of body length). The Mediterranean spearfish, T. belone Rafinesque, is not known to occur outside of the Mediterranean but may do so. It, of course, was the fish Lowe used as a basis of comparison and it has a short pectoral fin as already noted. Perhaps the most decisive statement that can be made of T. georgei is that it is not T. belone, and that authors like Albuquerque (1956), who treated it as a synonym of T. belone and thus extended the range of T. belone to Madeira, were in error. Synonymy. Tetrapturus Georgii Lowe, 1840:36-37 (original description; type locality: Madeira) 1841:93; 1849:3 (original account re- peated). Tetrapturus georgii Robins and de Sylva, 1960:397-398 (name discussed, regarded as unidenti- fiable). No other name has ever been applied to the species although the reference by Rodriguez-Roda and Howard (1962:495) to two unidentified speci- mens under study by Robins refers to this species. The name is here modified to Tetrapturus georgei for reasons discussed by Bailey et al. (1970:5). Taxonomy. The roundscale spearfish is referred to Tetrapturus Rafinesque (1810:51-55; type species T. belone by monotypy) as defined by Ro- bins and de Sylva (1960:403-404 and in key). Lowe’s specimen of T. georgeii and his notes on it were apparently destroyed. Lowe perished in a shipwreck in the Bay of Biscay in 1874, and it is said that he had a large collection of Madeiran specimens and his manuscripts with him. Diagnosis. Scales on sides of body round an- teriorly usually with two or three posterior projec- tions, the scales only slightly imbricate and soft. Scales dorsally and ventrally elongate imbricate and stiff, more typical of the Istiophoridae. Anterior lobe of spinous dorsal and anal fins rounded. Spinous dorsal fin high, unspotted. Nape moderately humped. Anus moderately far from anal-fin origin, the distance between them equal to about one-half the height of the first anal fin. Pectoral fin long in adults, subequal to pelvic fins, reaching beyond curve of lateral line. Isthmial groove present. Eye moderate about 2.9 percent of body length. Verte- brae: 12 precaudal plus 12 caudal. First dorsal-fin elements: 43-48. Material examined. CRR-Med-1, male, fairly large but not in spawning condition, 1,600 mm body length, 21.5 kg, Sicily, near Messina, 2 August 1961 (specimen not retained). CRR-EAtI-1, female (no well developed ova), 1,570 mm body length, 20 kg, Portugal, trap off Faro, Cape Santa Maria, 27 May 1961 (piece of skin and pectoral girdle catalogued as UMML 11076). CRR-EAtI-2, female (no well de- veloped ova), specimen broken, no measurements recorded, 23.5 kg, Portugal by longline off Cape Santa Maria, 9 August 1961. CRR-EAtI-3, female (no well developed ova), 1540 mm body length, 23.5 kg, Strait of Gibraltar, 5 October 1961. Robins and de Sylva (1960:405-406) presented a key to the known species of Istiophoridae. At that time T. pfluegeri had not been distinguished from 7. belone and the reference in the key to 7. belone in fact refers to T. pfluegeri. Table 1 contrasts the four Atlantic species of Tetrapturus. Taxonomic status. T. georgei is easily separable from other species in the genus by the characters given in the diagnosis and in Table 1. Although in some features it is intermediate between belone and albidus, it is extreme or unique in others so that it can not be a hybrid between them (see below). With so few specimens examined little can be said of varia- tion and certainly nothing is known of its population structure. Common names. Roundscale spearfish is pro- posed as the English common name for the species in recognition of its peculiar lateral scales. Lowe (1840) referred to it as peito. Albuquerque (1956) and others have used peto, but they have failed to distinguish istiophorid species, and peito or peto may be taken as comparable to the more general English word billfish rather than as a name for any one species. Morphology. Morphometric data are presented in Table 2. Fin-ray counts are (in each instance the order of presentation is Med-1, EAtl 1, 2, 3): first dorsal 48, 45, 47, 43; second dorsal -, 7, 6, 6; first anal 16, 14, 15, 16; second anal -, 5, 7, 6; pectoral 19, 20, 56 20, 19. There were 12 caudal, 12 precaudal, and 24 total vertebrae in all four specimens. The general body form of istiophorids changes with growth. Because all four specimens of georgei are of nearly the same size, the description below will apply only to adults. Juveniles and earlier life stages are unknown. The dorsal profile is concave above the posterior part of the head, the nape being moderately humped. Exclusive of the sheath for the spinous dorsal fin, the dorsal and ventral profiles are nearly parallel. Be- hind this point the body narrows rapidly to the caudal peduncle. The general body form is best seen in Figure 1. The body is fairly robust, being proportionally wider at the pectoral and first anal fin than T. belone and nearly equal to T. albidus in this regard. The dorsal fin is moderately high posteriorly, its height at the 25th spine varying widely from 5.0-9.2 percent of total length. This is comparable to that of T. belone at the same size and higher than inalbidus. The anterior lobe of the spinous dorsal fin is high (18-24 percent body length) and broadly rounded; likewise the first anal fin is high (12-15 percent body length) and broadly rounded. The dorsal fin is com- pletely unspotted. This feature was checked espe- cially on the sheathed portion of the fin where spots will persist even after severe treatment of sun dry- ing, freezing, or preservative. In this regard georgei is similar to pfluegeri, belone, and angustirostris. None of the specimens exhibited bars on the body but these would have disappeared in the frozen specimens, so this condition is uncertain. However, neither belone nor pfluegeri is barred. In istiophorids the pectoral fin usually is allomet- ric in growth, sometimes, as in pfluegeri and audax, changing very rapidly from a short fin to long fin condition in a short size range. This fin is long in georgei, but the time or size of changeover is un- known. Presumably juveniles will have short pec- toral fins. Figure 1.—Outline drawing of Tetrapturus georgei based on three photographs taken by Raimondo Sara of a speci- men caught off Messina, Sicily, 1961, and with reference to measurements of other specimens (vertical dashed line indicates position of anus). (€p-OP ATlensn) Sp-8E rele aul] [e1aye] JO 9AIND puodaq Suryseas sulJ o1Ajad 0] [enbaqns ‘suo7T juasund ‘pajurog s}Ods yor]q Yysinfq snorowmu YA popunoy uly [Bue say JO JYsI9Yy oy) 19}1eNb 2uo ynoqe pue yjsus] Apoq juao -lad 7'¢-¢°¢ Way) UsaMJaq J0Ur} -SIP 94} ‘UISIIO UJ-[eUe 0} aSO[D 8P-ty 67 oul] yeiaje] JO aAind puodag surysee1 “suly dtAjad 0} [enbaqns ‘suo7] yos ‘sjurod Jolia}sod adie] May YIM papunoy poyodsuyp papunoy uy [Bue ysay JO 1YSIOY JfeY jnoqe pue yysuay Apog juadiad 9°/-g*p way) U99M}9q BOURISIP 9) ‘UITIIO Uy -[BUB O} JOLIO}UB IeJ A[a}e.1IPO| (Sp-tp Alfensn) 9p-6¢ OEP 'T aul] [e19}e] JO IAIN Bul -yora. AJaieg ‘s]jNpe Ul UdAd “04S juasund ‘pajuiog penodsuy PoyUulod ‘uly [BUR JSIIJ JO 1YSIOY Surpaaoxa 10 0} Jenbo puv yy3ua} Apoq judo -lad [[-g°2 Way) usaMJAq JOURISIP 24) ‘UISIIO UJ-[BUL O} JOLIA}UL IBY (IS-8p Allensn) ¢¢-¢p 6 CPT oul] [e1aj}e] JO dAInd puofaq Suryoras ‘suly orajad 0] [enbaqns ‘3u07 juasund ‘paulog poyodsuy (s]]npe ade] ul papuno. Apyss [esiop ay) payurog “uly [BUR ISA JO TYs1ay ULY] 19] e913 Ajjensn pure yysuez Apoq quas -lad [[-p°g Way) U99MJAq ddUL}SIP 24} “UISIIO Uy-;BUe 0} 1OLID]UR ey syUsU3]9 uly [B@s1op sity (yi3u2] Apoq jo yusoiad ul) I9]9WeIP IGIO s]jnpe ul ysus] UIJ-[B10199q syjnpe ul opts -pIuw suoye sayeog uly [BSIOp sty JO u19}ed suly jeue pure [esiop JsIlJ JO saqoy snur JO uonIsog SSS SS eS ee ee ee a ee eee ee UPTV SHUM ysyivads aeospunoy ysyivods uvauriiajipayy ysyjaeads ][1qsuo7 Snpiq|D snanidvaya [ 1984008 Snanjdvaja [ auojag snanjdv.ja J Masanyd snanidvaja I SS Ee ee se ee ee ee ee Rae ee ‘S19}DVILYD ISOUTvIP SOW IY} UO paseq sninidv.a J Jo saideds oNULPY ANOJ JO UOSLIRdWOD—"| 21qR, Jajovreyo 57 Table 2.—Morphometric data for three specimens! of Tetrapturus georgei expressed in millimeters and in percentage of body length. Measurements are as defined by Rivas (1956) unless otherwise indicated. Numbers in parentheses refer to the numbered definitions of Rivas; see Robins and de Sylva, 1960:384-385 for explanation of abbreviations. Specimen number EAtl-3 EAtl-1 Med-1 Body length(1) 1540 1570 1600 First predorsal length (3) 360 23 346 22 360), 22 Second predorsal length (4) — — 1,270 81 102950 mil Prepectoral length (5) Chik, 9 a7) 393 mee25 390 8624 Prepelvic length (6) 440 29 ADS 27 420 26 First preanal length (7) 5 ear59 950-60 940 59 Second preanal length (8) 12357) SOh 242) 79891 ;280% 780 Orig. D: to orig. Pi (9) 212 14 17Ob uel 172 10 Orig. Di to orig. Pe (10) 270 ~=618 232 15 235 15 Orig. Dz to orig. Az (11) 153 9.9 145 9.2 147 9.2 Tip mandible to anus 856 = 56 825 52 830 52 Orig. Pe to nape (13) 260 17 238 15 245 15 Greatest body depth (14) 275 18 231 15 240 15 Depth at orig. Di (15) 258 7 216 14 222 14 Depth at orig. Ax (16) 220 14 205 13 210 13 Least depth cp (17) 66 4.3 54 3.4 60 3.8 Width at Pi base (18) 1S TES 96 6.1 110 6.9 Width at Ai orig. (19) 125 8.1 113 IP 122 7.6 ‘The fourth specimen, EAtl-2, was damaged and no measure- ments were taken. Flesh color is of uncertain value in istiophorid taxonomy but does reflect differences in myoglobin content. In T. georgei the flesh is distinctly redder than in belone and more like T. albidus. Perhaps the most diagnostic feature of georgei is its lateral squamation. An area 100 x 100 mm is illustrated in Figure 2. Dorsal and ventral to this area, the scales are more elongate, stiffer, and with only one point or two closely approximated points. The lateral scales are softer and more flexible than in all other istiophorids. In counting vertebrae, the au- 58 Specimen number EAtl-3 EAtl-1 Med-1 Width at A» orig. (20) 92 6.0 90 S\s7/ 91 5\57/ Width cp (in front of keels) 54 SED) 45 2.9 ANS) 25) Length upper keel (22) 58 3.8 4] 2.6 5 3:3 Length lower keel (23) 53 3.4 51 3.2 49 3.1 Head length (24) 414 27 385 24 385 24 Snout length (25) —_208 14 185 12 188 12 Bill length (26) 484 931 — — — — Maxillary length (28) 265 17 243 16 240° 15 Orbit diameter (29) 45 2.9 46 2S) 46 28) Depth of bill (33) 15.4 1.00 12.8 0.82 — — Width of bill (34) 22.4 1.4 22.0 1.4 _ = Height Di (39) 371 24 274 —s«'18 Pespy - ils Length 25th Di spine (40) 141 9.2 78 5.0 92 5.8 Height D2 (41) 67 4.4 69 4.4 61 3.8 Height A, (42) 236 15 190) 12 2107 als Height Az (43) 51 3.3 — — 48 3.0 Length P: (44) 405 26 — — 330) 21 Length P» (45) 328 =. 21 — — 344522 Length last De» ray 107 6.9 105 6.7 — os Length last Ao ray 92 6.0 97 6.2 82 Se Orig. D: to orig. De 910 59 936 ~=—-660 930 58 Anus to orig. Ai 74 4.8 120 Ws ile 7.0 Weight (kg) 23:5 20 PN 5) thor makes a slit along one side to expose the centra. In running one’s hand along this section, one always moves from front to back to avoid the very sharp posterior spine of istiophorid scales. The soft scales of georgei offer no such danger. The lateral line is simple as in all species of Tetrapturus. Relationships. T. georgei most resembles the white marlin, 7. albidus. This is due largely to the somewhat humped nape and the broadly rounded anterior lobes of the first dorsal and anal fins. Beyond that, however, comparison of the data in Table 2 with those presented by Robins (1974) for white marlin from the eastern Atlantic reveals dif- ferences only in four features: the width at the sec- ond anal fin (less in georgei), the orbit diameter (less in georgei), the length of the 25th dorsal spine, a measure of the posterior height of the fin (greater in georgei), and the distance from the anus to anal fin (greater in georgei). The discovery of georgei makes more complete the transition between Tetrapturus albidus and T. audax on the one hand, called marlins because of their form and size, and the smaller species of spear- fish, T. belone, T. angustirostris, and T. pfluegeri. Structurally, and in reference to the dendrogram in Robins and de Sylva (1960: Fig. 5), both pfluegeri and georgei would fall between T. belone and T. albidus. There is thus no clear division of the genus and no basis for recognizing as distinct subgenera Tetrapturus and Kajikia. The continued placement of albidus in Makaira by Ovchinnikov (1970) is unexplained and naive. Likewise Ovchinnikov’s distribution of T. belone is confused with pfluegeri, and his inclusion of georgei as a synonym of belone is incorrect. Distribution. Tetrapturus georgei is positively known only from the specimens reported on here from Sicily, the Strait of Gibraltar, and the adjacent Atlantic Ocean off southern Portugal. Its occur- rence at Madeira is inferred by application of the name georgei. Obviously this species can be ex- pected to range widely in the eastern and perhaps central north Atlantic. Many of the records of Tet- rapturus pfluegeri from these regions may be of georgei. Clarification of the central and eastern At- lantic records of spearfish from Japanese data (Ueyanagi et al., 1970) is of vital importance. The larvae and juveniles and their areas of occurrence are unknown. Data are too few to permit discussion of seasonal or annual variation in occurrence beyond the point that all istiophorids reaching Madeira and the southern coasts of Portugal and Spain do so during the warm months and that a movement south and west during the cold season may be assumed. Hybridization. Hybrids in fishes are usually in- termediate in characters most often used by sys- tematists (i.e., fin-ray counts, body proportions) be- cause these characters apparently are polygenic and the genes pleiotropic. This has been frequently dis- cussed but perhaps nowhere more clearly than by Hubbs (1940:205-207; 1943). Whenever a rare species occurs which is intermediate in its characters 59 CS PEI LEE s =a ES SSeS See Figure 2.—Squamation of Tetrapturus georgei, patch 100 < 100 mm from right side below spinous dorsal fin. Draw- ing by Charles D. Getter. between two more common species, there are a priori grounds for believing it to be based on hybrids between the two. Natural hybrids in fishes are most common among freshwater species where man’s al- teration of the environment has resulted in break- down of ecological barriers. Hybrids are rarer among coastal fishes, rarer still in the stable envi- ronment of the tropical reefs, and unknown among truly oceanic fishes. Hybridization in a long estab- lished pelagic family like the Istiophoridae would seem to be highly unlikely. Two possible hybrid combinations were consid- ered in analyzing the characters of georgei: 1) Tet- rapturus albidus x T. belone, and 2)T. albidus x T. pfluegeri. Analysis of Table 1 shows that T. georgei is intermediate in several of its most diagnostic characters between T. albidus and both pfluegeri and belone, namely the position of the anus and the diameter of its orbit. Its squamation is unique and the shape of its dorsal- and anal-fin lobes are as in albidus. Additional data for pfluegeri are available in Robins and de Sylva (1960, 1963) for belone in Robins and de Sylva (1963) and for albidus in Rob- ins (1974). In the height of its first dorsal and anal fins, georgei is as extreme as albidus. In short, no good case can be made to consider georgei to be based on hybrids. Also, available evidence on spawning grounds of belone and albidus indicates that these species are at least 2,000 miles apart at spawning time. 7. albidus and T. pfluegeri broadly overlap geographically, but whether georgei occurs in the western Atlantic is unclear. Fishermen, particularly those working in the Gulf of Mexico, have described a fish they term a hatchet marlin in reference to the high and squarish anterior lobe of its dorsal fin. D.P. de Sylva has discussed this fish at this conference and has shown color slides provided by Robert Ewing of Monroe, Louisiana. I have also studied a series of black and white negatives of this fish. The shape of the first dorsal is dramatically like that in georgei (see Figure 1) and the scales appear large and rounded. How- ever, the spinous dorsal and first anal fins appear much higher in the fish from the Gulf of Mexico. Certainly it appears that the hatchet marlin and the roundscale spearfish are closely related, if not iden- tical, but no specimens of the former have ever been studied by scientists, and among contemporary biologists, only the writer has seen specimens of georgei. This species needs publicity in game-fish circles, with arrangements made to freeze specimens and bring them to the attention of appropriate scien- tists for study. This also calls attention to the grow- ing need to provide contingency funds to preserve and ship such specimens, or to provide travel funds for scientists to the specimens when such rarities are caught by anglers. Reproduction. All three of the known females were in a refractory state with no developed ova. They were collected 27 May, 9 August and 5 Oc- tober. All were adults and this slim evidence may be taken to indicate that in georgei, like its Atlantic congeners, spawning is over by early summer. The only male, collected 2 August, still had fairly large testes but was not in spawning condition. Nothing else is known of the bionomics and life history of the species. An additional species of Tetrapturus is shown to exist in the northeastern part of the Atlantic Ocean and in the Mediterranean Sea. The name Tetrap- turus georgei Lowe, previously regarded as uniden- tifiable, is applied to this species. The nomenclature is discussed in detail, and reasons for so restricting and applying this name are given. The species is described on the basis of study of three females and one male, all adults. Morphomet- ric data are available for three, one having been mutilated in a way that such data were unusable. T. georgei is contrasted with the other Atlantic species of Tetrapturus: T. belone, T. pfluegeri, and T. al- bidus. The possibility that the specimens of georgei represent hybrids between other species is discussed and rejected. Known information on distribution and reproduc- tion are summarized. ACKNOWLEDGMENTS Many persons have aided the University of Miami's long-term program on billfishes, and the trip to southern Europe in particular involved much cooperation with local biologists, fishermen, and of- ficials. Their names are documented in detail by Robins and de Sylva (1960, 1963). Special thanks are due the late John K. Howard for his persistent sup- port of billfish research and to Raimondo Sara, Rui Monteiro, and Julio Rodriguez-Roda for their con- siderable help in Sicily, Portugal, and Spain respec- tively. LITERATURE CITED ALBUQUERQUE, R.M. 1956. Peixes de Portugal e ilhas adjacentes. Port. Acta Biol. Ser. B 5:1-xvi+1-1164, 445 figs. BAILEY, R.M., J.E. FITCH, E.S. HERALD, E.A. LACH- NER, C.C. LINDSEY, C.R. ROBINS, and W.B. SCOTT. 1970. A listof common and scientific names of fishes from the United States and Canada (third edition). Am. Fish. Soc., Spec. Publ. 6, 149 p. CUVIER, G., and A. VALENCIENNES. 1831. Histoire Naturelle des Poissons. Paris 8:i-xix, 1-509. HUBBS, C.L. 1940. Speciation of fishes. Am. Nat. 74:198-211. 1943. Criteria for subspecies, species and genera, as deter- mined by researchers on fishes. Ann. N.Y. Acad. Sci. 44:109-121. LOWE, R.T. 1840. On new species of fishes from Madeira. Proc. Zool. Soc. Lond. 8:36-39. 1841. Description of some new species of Madeiran fishes, with additional information relating to those already de- scribed. Ann. Mag. Nat. Hist., Ser. 1, Vol. 7:92-94. 1849. Supplement to *‘A synopsis of the fishes of Maderia’’. Trans. Zool. Soc. Lond. 3:1-20. OVCHINNIKOV, V.V. 1970. Swordfish and billfishes in the Atlantic Ocean. Ecology and functional morphology. Atl. Sci. Res. Inst. Fish. Oceanogr., 77 p. (Translated by Israel Program Sci. Transl., 1971, 77 p; available U.S. Dep. Commer., Natl. Tech. Inf. Serv., Springfield, VA, as TT71-50011.) RAFINESQUE, C:S. 1810. Caratteri di alcuni nuovi generi e nuove specie di ani- mali e piante della Sicilia. Palermo, 105 p., 20 pls. RIVAS, L.R. 1956. Definitions and methods of measuring and counting in the billfishes (Istiophoridae, Xiphiidae). Bull. Mar. Sci. Gulf Caribb. 6:18-27. ROBINS, C.R. 1974. Summer concentration of the white marlin, Tetrap- turus albidus, west of the Straits of Gibraltar. Jn Richard S. Shomura and Francis Williams (editors), Proceedings of the International Billfish Symposium, Kailua-Kona, Hawaii, 8-12 August 1972, Part 2. Review and Contrib- uted Papers. U.S. Dep. Commer., NOAA Tech. Rep. NMES SSRF-675, p. 164-174. ROBINS, C.R., and D.P. DE SYLVA. 1960. Description and relationships of the longbill spearfish, 61 Tetrapturus belone, based on the western North Atlantic specimens. Bull. Mar. Sci. Gulf Caribb. 10:383-413. 1963. A new western Atlantic spearfish, Tetrapturus pflue- geri, with a redescription of the Mediterranean spearfish Tetrapturus belone. Bull. Mar. Sci. Gulf Caribb. 13:84-122. RODRIGUEZ-RODA, J., and J.K. HOWARD. 1962. Presence of Istiophoridae along the South Atlantic and Mediterranean coasts of Spain. Nature (Lond.) 196:495-496. UEYANAGI, S., NISHIKAWA. 1970. Distribution, spawning, and relative abundance of bill- fishes in the Atlantic Ocean. Bull. Far Seas Fish. Res. Lab. (Shimizu) 3:15-55. S. KIKAWA, M. UTO, and Y. Evaluation of Identification Methods For Young Billfishes' WILLIAM J. RICHARDS? ABSTRACT Most of the papers published from 1831 to date which deal with the identification of young billfishes (Families Xiphiidae and Istiophoridae) are reviewed. The present knowledge of the identification of adults is compared with the identification of young and problem areas are defined. Suggestions are made to resolve the present problems encountered with the identification of the young stages (eggs, larvae, and juveniles). These suggestions include the need for detailed osteological descriptions of the young, the need for an increased effort to collect specimens, and the need to artificially rear specimens in the laboratory. The purpose of this paper is to review the identifi- cation work that has been done on young billfishes over the years, to summarize the present methods used for identifying young billfishes, and to evaluate the identification methods. Knowledge of the young stages of fishes is useful for determining spawning areas and times, and for estimation of sizes of adult spawning stocks. Prerequisite to this knowledge is the ability to iden- tify the young stages of the species in question —from eggs through larvae to juveniles. Currently, there are two methods available to us to make these identifications. Both methods require a complete series of specimens which will show all the different stages of development plus the indi- vidual variations which may be found in a particular species. The first method is to artificially fertilize eggs, then rear the products in the laboratory. This tech- nique provides an ideal series of specimens with the only limitations being anomalies resulting from rear- ing under artificial conditions, and the possibility that your material is influenced by a limited number of parents. Both limitations can be circumvented by comparing reared specimens with specimens caught in the wild. Wild caught eggs can be collected and brought into the laboratory and reared, thus avoiding the difficulties of catching ripe fish or by maturing ‘Contribution No. 228, National Marine Fisheries Service, Southeast Fisheries Center, Miami Laboratory, Miami, FL 33149. *NOAA, National Marine Fisheries Service, Southeast Fisheries Center, Miami Laboratory, Miami. FL 33149. gonads artificially. This method has been used suc- cessfully for very early stages of billfishes (Sanzo, 1922). The second method ts to collect a large series of specimens in the field over a wide enough size range so that one can work backwards from the adult, utilizing characters common to the adults, then to juveniles, larvae, and eggs. This approach requires that enough specimens be collected to develop suffi- cient series so that all the necessary characters will be available. The problems inherent in the rearing method are not relevant to this method, particularly when the material is from a wide geographic range, preferably the entire spawning range of the species. The prerequisite for the taxonomic approach is a firm knowledge of the adults. Unfortunately, some adult taxonomic problems still exist and the first section briefly summarizes these problems. IDENTIFICATION STATUS OF ADULTS Nakamura, Iwai, and Matsubara (1968) com- pleted the most recent review of the billfishes of the world. They recognized 11 species in two families, Xiphiidae and Istiophoridae; the former monotypic, the latter with 10 species in three genera. These species, their English and Japanese names, and their distributions are: Xiphias gladius Linnaeus, 1758. Swordfish, Mekajiki. Cosmopolitan. Istiophorus platypterus (Shaw and Nodder, 1792). Pacific sailfish, Bashokajiki. Indo-Pacific Ocean. Istiophorus albicans (Latreille, 1804). Atlantic sailfish. Nishibashokajiki. Atlantic Ocean. Tetrapturus angustirostris Tanaka, 1914. Short- bill spearfish, Furaikajiki. Indo-Pacific Ocean. Tetrapturus belone Rafinesque, 1810. Mediterra- nean spearfish, Chichukaifurai. Mediterranean Sea. _ Tetrapturus pfluegeri Robins and de Sylva, 1963. Longbill spearfish, Kuchinagafurai. Atlantic Ocean. Tetrapturus albidus Poey, 1860. White marlin, Nishimakajiki. Atlantic Ocean. Tetrapturus audax (Philippi, 1887). Striped mar- lin, Makajiki. Indo-Pacific Ocean. Makaira mazara (Jordan and Snyder, 1901). Blue marlin, Kurokajiki. Indo-Pacific Ocean. Makaira nigricans Lacépede, 1803. Atlantic blue marlin, Nishikurokajiki. Atlantic Ocean. Makaira indica (Cuvier, 1831). Black marlin, Shirokajiki. Indo-Pacific Ocean, possibly Atlantic Ocean. Several papers published prior to and after Nakamura et al. (1968) disagree with the opinions expressed. Morrow and Harbo (1969) state that there is only one worldwide species of /stiophorus and that their data (which they do not present) do not support the contention made by Nakamura et al. (1968) that small Atlantic specimens (less than 90 cm) can be separated from small Indo-Pacific speci- mens based on relative lengths of the pectoral fin. Two papers (Morrow, 1964; Robins and de Sylva, 1960) consider the blue marlin to be one species. Nakamura et al. (1968) state that their conclusion is tentative. Nakamura et al. (1968) also state that 7. audax may represent two species, one in the North Pacific and one in the South Pacific. Another species of spearfish, the roundscale spearfish, T. georgei (Lowe, 1840), is now recognized in the eastern At- lantic by Robins (paper presented at this sym- posium). Another problem is that the presence of the black marlin in the Atlantic has not, as yet, been thoroughly documented. However, for purposes of identification of the young, some of the current tax- onomic problems should make little difference. HISTORICAL SUMMARY OF DESCRIPTIONS OF YOUNG BILLFISHES Nineteenth Century Cuvier ( in Cuvier and Valenciennes, 1831) was the first to describe young stages of a billfish. He gave a brief description of a young swordfish and included a figure of a juvenile. He also described a young 108-mm sailfish as a new species, His- tiophorus pulchellus, and included a fine illustration of the spectmen. Morrow and Harbo (1969) place this species in the synonymy of J. platypterus. Ruppell (1835a) described an 18-inch juvenile sail- fish from the Red Sea which he also described as new as H. immaculatus. Two précis of Ruppell’s de- scription appeared in the same year (1835b, 1835c), but only his 1835a paper included an illustration. Morrow and Harbo (1969) also placed this species inthe synonymy of J. platypterus, although the name is misprinted as H. immaculatis in their paper. Gunther (1873-74) described and figured three young billfish which were later figured and briefly de- scribed by him again in 1880. The three figures defy identification because of distortions, lack of detail, and apparent errors by the illustrator, particularly in fin shape and detail. In his 1880 paper there is a brief description of a young swordfish and crude drawing of it. Litken (1880) briefly describes young istiophorids varying in length from 5.5 to 21 mm and compares them with those described by Gunther. He presents a figure of his smallest specimen (5.5 mm) and repro- duces Gunther’s original plates. He also describes young swordfish specimens in his possession and reproduces the figure of XY. gladius from Cuvier. Lutken made no attempt to assign the young is- tiophorids to any particular species. Goode (1883) reviews these earlier works, reproduces all of the figures thus far cited, and adds one note on the report of a young swordfish by Steindachner (a publication I have not seen). His paper also includes an English translation of Lutken’s (1880) Danish text. Twentieth Century Lo Bianco (1903) reported on the capture of young X. gladius and later (1909) reported on the capture of two 10-mm istiophorids in February from the Mediterranean, southeast of Capri. Since T. belone is the only istiophorid known from the Mediterra- nean, they are presumed to be larvae of T. belone. Padoa (1956) reviews this evidence, illustrates one of the specimens, and further reviews Ginther’s and Liitken’s work which includes reproductions of their figures. Sanzo (1909, 1910, 1922, and 1930), in several papers on swordfish, described eggs; described eggs and larvae at hatching; reexamined eggs and larvae; reared larvae from eggs through the yolk sac stage; described a 13-mm specimen; and described a 6-mm specimen. Sella (1911) confirmed Sanzo’s (1910) work. Regan (1909) pointed out the resemblance ofa young Xiphias (200 mm in length) to the fossil species Blochius longirostris. Regan (1924) de- scribed and figured this 200-mm juvenile and noted that Phaethonichthys tuberculatus Nichols, 1923, is actually a young swordfish and placed it in the synonymy of X. gladius. Fowler (1928) also figured a young swordfish (ca. 225 mm) and like Regan (1924) noted that P. tuberculatus Nichols was a synonym of X. gladius. Therefore, by early in the century the young stages of swordfish were well described. Later accounts which include descrip- tions of young swordfish are Arata (1954); Yabe (1951); Yabe, Ueyanagi, Kikawa, and Watanabe (1959); Jones (1958); Nakamura et al. (1951); Gor- bunova (1969): Taning (1955); and Tibbo and Lauzier (1969). Several authors have described a few specimens of istiophorids (presumed sailfish) prior to descrip- tions of complete series. These descriptions are by Uchida (1937); Nakamura (1932, 1940, 1942, 1949); La Monte and Marcy (1941); Baughman (1941); Beebe (1941); and Deraniyagala (1936, 1952). Com- plete series of larval through juvenile stages of sail- fish were both published in 1953. One by Voss (1953) was based on Atlantic specimens, the other by Yabe (1953) was based on Pacific specimens. Following these two publications, several papers also de- scribed sailfish based on complete series or else give important data on young forms. These studies are by Ueyanagi and Watanabe (1962, 1964); Gehringer (1956, 1971); Jones (1959); Jones and Kumaran (1964); de Sylva (1963); Ueyanagi (1963b); Arnold (1955); Springer and Hoese (1958); Mito (1966, 1967); Sun’ (1960); Laurs and Nishimoto (1970); and Strasburg (1970). Most of the work on identification of young stages of istiophorids other than sailfish has been done by Japanese scientists, particularly Dr. Shoji Ueyanagi on Pacific species. Ueyanagi (1957) demonstrated that Kajikia formosana (Hirasaka and Nakamura) was actually the young of the striped marlin, T. audax. He (Ueyanagi, 1959) also described a com- plete series of striped marlin young ranging in length from 2.9 to 21.2 mm in standard length. Nakamura (1968) described the young juveniles of this species. The larvae of shortbill spearfish, T. angustiros- tris, were described by Ueyanagi in two papers (1960b, 1962) followed by a description of a juvenile by Watanabe and Ueyanagi (1963). A larva of the black marlin, M. indica, was first 64 mentioned by Ueyanagi and Yabe (1959), then de- scribed by them in a subsequent paper (1960). Smal- ler larvae were reported later in that year by Ueyanagi (1960a). Larvae of the Pacific blue marlin, M. mazara, were described by Ueyanagi and Yabe (1959). At- lantic blue marlin (M. nigricans) larvae were first described by Gehringer (1956), although he sug- gested that they were T. belone. Ueyanagi (1959) suggested that they were in fact M. nigricans. Juveniles of M. nigricans have been subsequently described by de Sylva (1958), Caldwell (1962), Eschmeyer and Bullis (1968), and Bartlett and Haed- rich (1968). Ueyanagi (1957) described the juvenile stage of M. mazara. The larvae of white marlin, T. albidus, have yet to be described, although Ueyanagi (1959) suspected that some of Gehringer’s (1956) sailfish larvae may be the larvae of this species. De Sylva (1963) de- scribed a juvenile white marlin and a photograph ofa 74-inch juvenile has been published (Florida Board of Conservation, 1968). Ueyanagi, Kikawa, Uto, and Nishikawa (1970) plot the distribution of white marlin larvae, but do not describe their features. Larvae of T. pfluegeri and T. georgei have not been described, although Robins and de Sylva (1963) described a large juvenile of the former species. Sparta (1953, 1961) has briefly described the eggs and young of T. belone. A number of summary papers have been written which discuss the identification of young billfishes. These are La Monte (1955); Padoa (1956); Jones and Kumaran (1964); Ueyanagi and Watanabe (1962, 1964); Strasburg (1970); Howard and Ueyanagi (1965); Ueyanagi (1963a and b); and Ueyanagi (1964). The last includes an excellent account for identifying young Indo-Pacific species. To summarize the published work to date on the identification of young billfishes, the following stages have been described: eggs, larvae, and juveniles of X. gladius; the larvae and juveniles of all the Indo-Pacific istiophorids with the exception of juvenile black marlin; larvae and juveniles of At- lantic sailfish; juveniles of Atlantic blue marlin; juveniles of the white marlin; a juvenile of the west- ern Atlantic longbill spearfish; and the eggs and a few young specimens of the Mediterranean spear- fish. Nothing has been published on the young of the roundscale spearfish. IDENTIFICATION METHODS There is no problem in separating young swordfish from istiophorids since the former lack the strong pterotic and preopercular spines which are so prom- inent in the latter in the early stages. In sizes over 20 mm, the young are very dissimilar in appearance. The identification problems lie within the is- tiophorids. Ueyanagi (1964) has summarized the present methods used to identify young stages of istiophorids from the Indo-Pacific Ocean. No pa- pers have appeared as yet distinguishing all the species of the Atlantic from one another. One major problem with this group is that meristic characters are not particularly useful. The full complement of fin rays does not appear until the young are at least 20 mm in length and, as I have shown in Table 1, the counts exhibit little interspecific differences with overlap in range of nearly every character. Only the swordfish is separable on vertebral numbers (26 ver- tebrae compared with 24 for istiophorids). The genus Makaira has 11 precaudal and 13 caudal vertebrae, whereas /stiophorus and Tetrapturus have 12 pre- caudal and 12 caudal vertebrae. This character is difficult to use with specimens less than 20 mm in length. The only other meristic character (with the obvious exception of the pelvic rays, since they are lacking in swordfish) of any use is the number of first dorsal rays. This will separate some species from each other, but there is sufficient overlap so that the number of rays alone cannot be used. Forexample, a specimen with a count of 42 could not be T. angus- tirostris or T. pfluegeri, but it could be any of the others. Therefore, first dorsal counts are only useful to eliminate some species. I have reproduced here Ueyanagi’s methods for separating the Indo-Pacific species of istiophorids as follows (I have changed his names to conform with present practices): ‘It is not easy to identify the larvae of different istiophorid species, because of their close resem- blance with each other and of marked difference from their respective adults, generally speaking, in their morphological characteristics. This is particularly true with those of very early stage before the snout develops its specific characteris- tics. However, the specific separation of the lar- vae is possible throughout their entire range mainly on the basis of their head profile. ‘*Following are the criteria for identification: ‘*(1) Larvae under 5 mm in length: The characters, as shown in Table [2], can be used for specific separation, although snout length does not pro- vide a useful clue. “*(2) Larvae between 5 and 10 mm in length: Be- sides the criteria given in Table [2], snout length and size of eyes can be used. [M. mazara] larvae are recognized by their short snout. The ratio of snout length to diameter of orbit is largest in [/. platypterus], smallest in [M. mazara], and is be- tween in [7. angustirostris]. More precisely, the ratio tends to be > 1 in [/. platypterus], < 1in[M. mazara], and = | in [T. angustirostris] in speci- mens 7-8 mm length. **(3) Larvae between 10 and 20 mm in length: They are grouped into two on the basis of their snout length; the long snout group with [T7. angustirostris], [I. platypterus], and [T. audax], and the short snout group with [M. mazara] and [M. indica]. In the former, the snout length ex- ceeds !/; of their body length, while in the latter, it does not. For the specific separation of the former group, Table [2] applies; [7. angustirostris] 1s dis- tinguishable by black chromatophores on bran- chiostegal membrane, while [/. platypterus] is separated from [T. audax] by the difference of their head profile: Unlike [T. audax] with a straight snout, [/. platypterus] has a beak-like snout. And because of this difference in the shape of the snout, they are separable by the difference Table 1.—Meristic characters of adult billfishes based on data compiled from Nakamura et al. (1968) and Merrett (1971). First Second First Dorsal Dorsal Anal Species Rays Rays Rays T. platypterus Atlantic 42-47 6-7 11-15 Pacific 42-48 6-7 12-15 T. belone 39-46 5-7 11-16 T. pfluegeri 44-50 6-7 13-17 T. albidus 38-46 5-6 12-17 T. audax 37-42 5-7 13-18 T. angustirostris 47-51 6-7 12-15 M. nigricans 41-43 6-7 13-15 M. mazara 40-44 6 12-15 M. indica 37-42 6-7 12-14 X. gladius 38-49 4-5 12-16 Second 65 Vertebrae Anal Pectoral Pelvic Pre- Ray 6-7 6-7 6-7 6-7 5-6 5-6 6-7 6-7 6-7 6-7 3-4 s Rays Rays caudal Caudal Total 17-20 3 12 12 24 17-20 3 12 12 24 16-20 3 12 12 24 17-21 3 12 12 24 18-21 3 12 12 24 18-23 3 12 12 24 18-19 3 12 12 24 18-21 3 11 13 24 21-23 3 11 13 24 19-20 3 11 13 24 17-19 0 10-11 15-16 26 of the location of snout in terms of the center of eyes. In [/. platypterus], the center of eyes is above the tip of snout, while in [7. audax], they are on a nearly same level. “*Separation of [M. indica] from [M. mazara] can be made on the basis of the form of the pectoral fin. ‘*(4) Larvae over 20 mm in length: On top of the criteria of Table [2], the following characters, as listed in Table [3], can be applied.” Ueyanagi has assumed for the identification of Atlantic specimens that M. nigricans will resemble M. mazara, T. pfluegeri will resembie 7. angustiros- tris, and T. albidus will resemble T. audax. In his 1959 paper he tentatively identified Gehringer’s (1956) unidentified specimens as blue marlin and some of his sailfish specimens as white marlin be- cause Gehringer’s illustrations resembled Pacific blue marlin and striped marlin. EVALUATION OF IDENTIFICATION METHODS The basic problem with the identification methods used for these young fishes is that only one character is used and this character is poorly sub- stantiated with other characters. For example, when examining Ueyanagi’s tables of diagnostic characters for larvae less than 5 mm in length (Table 2), only one character separates each of the five species considered—spearfish has branchios- tegal pigment, striped marlin has the tip of the snout and center of eye on the same plane, etc.; other- wise, they have the other characters in common. In larvae between 5 and 10 mm, relative snout length is used since sailfish have a relatively long snout, blue marlin a relatively short snout, and spearfish a snout of intermediate length. For larvae between 10 and 20 mm in length the snout length and snout shape are slightly more reliable. With larvae over 20 Table 2.—Summary of the prominent diagnostic characters of istiophorid larvae less than 5 mm in length modified from Ueyanagi (1964). Species characters Tetrapturus I stiophorus Tetrapturus angustirostris — platypterus audax Profile of head Tip of snout is Same as 7. lower in level than center of Tip of snout and center of eye are ona angustirostris Makaira mazara Tip of snout is lower in level than center of eye. nearly equal eye. level. Anterior edge Same as T. Same as T. Anterior edge of orbit does angustirostris angustirostris _ of orbit not project projects forward. forward. Presence or Present Absent Absent Absent absence of Chromatophores chromatophores generally present on the branch- on the peripheral iostegal zone of lower membrane. jaw membrane. Pectoral fins Fins extend Same as T. Same as T. Same as T. along the lateral angustirostris side of the body and can be readily folded against the side of the body. angustirostris angustirostris Makaira indica Same as M. mazara Anterior edge of orbit does not project forward. Absent Fins stand out from the lateral side of the body at a right angle and cannot be folded against the body without breaking the joint. mm in length, three more characters are useful —number of dorsal rays, shape of the dorsal fin, and the nature of the lateral line. Another problem with some of these characters is that they are very difficult to use. The number of dorsal fin rays that I have compiled in Table 1 ex- hibits a greater range than those given by Ueyanagi (Table 3). Therefore, a young specimen with ray counts at the extreme of the range—for example, a spearfish with 47 dorsal rays—is within the range of the sailfish. This specimen could be further compli- cated by having its dorsal fin fixed in the retracted position. Such a specimen is difficult to evaluate because it is almost impossible to erect the dorsal fin to determine its shape. Measurements are very difficult to make, particularly on the very small specimens less than 8 mm in standard length and, more often than not, the bodies are bent and the opercles are expanded. This latter feature makes it very difficult to maintain the animal on its side for making measurements under a microscope. Even when opercles are flattened in their normal posi- tion, measurements are difficult because the ob- server has to carefully manipulate the specimen in order to maintain the two points of measurement on a plane parallel to the plane of the measuring device. Determining whether or not the anterior edge of the orbit projects is very difficult to evaluate. I have trouble with this character when I am simultane- ously comparing this feature on specimens which have it projected and those which do not. Invari- ably, there are specimens for which this decision cannot be made. I have this same trouble with the character of whether or not the tip of snout is above, below, or on the same plane as the eye. If the specimen is fixed with its mouth open the tip of the snout is invariably above the center of the eye. Attempts to close the mouth generally distort the specimen so that this character is unusable. I am suspicious of the premise that Indo-Pacific cognate species will resemble those from the Atlan- tic. Both white marlin juveniles collected in the At- lantic have 4 or 5 prominent ocellus-like spots (bright orange in life) on the dorsal fin. Its cognate from the Pacific, the striped marlin, as illustrated by Nakamura (1968), has a solid black dorsal fin. In order to evaluate these identification methods more fully, I examined 86 istiophorid young ranging in standard length from 2.8 mm to 20.8 mm. Six of these specimens were collected and identified by Ueyanagi—five were Pacific blue marlin and one was an Atlantic blue marlin. The remaining 80 were all collected in the vicinity of Miami or in the cen- tral Gulf of Mexico and the distribution of adults from these areas could reveal the presence of the young of four species—sailfish, blue marlin, white marlin, and longbill spearfish. Only 11 specimens were 12 mm or longer in standard length. For each specimen I made the following measurements: standard length (tip of snout to the end of the notochord or hypural plate), snout length (from the tip of the snout to the anterior edge of the orbit), tip of snout to center of eyeball, horizontal diameter of the eye, horizontal diameter of the orbit, head length, distance upper jaw extended beyond the lower jaw, and length of the pelvic fin. On a few specimens, the vertical diameter of the eye and orbit were taken, but I eliminated this measurement because on many specimens the upper jaw bones projected above the lower rim of the orbit and eye, Table 3.—Diagnostic characters usable in distinguishing the istiophorid larvae more than 20 mm in standard length modified from Ueyanagi (1964). Makaira Makaira Tetrapturus Species Tetrapturus Istiophorus characters angustiroStris platypterus Number of first More than 48 43-47* dorsal fin rays Shape of first dorsal fin Anterior-high type type Lateral line Single Single Poterior-high audax mazara indica Less than 45 Less than 45 Less than 45 Anterior-high type Anterior-high type Anterior-high type(presumed) Single Complex-having Not single (?) branches (obscure)** *This range is estimated from a small number of specimens. **Lateral line pattern not yet ascertained. making the measurement difficult to make with any accuracy. Ueyanagi and Yabe (1959) used this measurement in their description of the blue marlin. From these measurements I calculated standard length minus snout length and trunk length (stan- dard length less head length). No meristic data were taken because of the small size of the specimens. Other data collected included the position of the snout in relation to the center of the eye (whether the snout was above, equal, or below a plane pas- sing along the body axis through the center of the eye), the position of the pterotic spine (whether it was nearly parallel to the body axis or whether is projected upward at a 45° angle). This character was suggested to me by Dr. Ueyanagi (pers. comm.) as a possible means for separating striped marlin (parallel to the body) from sailfish (project- ing upward). The remaining data collected con- cerned the number and location of chromatophores on the lower jaw, gular membrane, and branchios- tegal membrane. First, the extent of pigmentation along the ramus of the lower jaw was noted, particu- larly whether this pigment was confined to the tip of the lower jaws or whether it extended posteriorly along 4, %, 34, or % of the distance of the lower jaw. In instances where this pigment varied from left to right side, the greatest value was used. The number of pigment cells occurring on the gular area was counted. These cells were always on the mid- line and variations of none, one, two, three, or more than three, were observed. Cases of more than three cells appeared as a distinct row along the mid- line and were noted as a row. Number and location of pigment cells on the branchiostegal membrane were also noted. In all but one specimen having branchiostegal membrane pigment, one cell occui- red anteriorly on the midline. The one unusual specimen had one cell slightly displaced to the left. These variations of pigment are shown in Figure 1. A rough analysis of the measurements produced generally negative results. The purpose of these analyses was to determine if more than one group was visible from inspection of plotted values. The only plots which did show differences were those involving the length of the snout. I show one such plot (Fig. 2) where the eye diameter divided by snout length and expressed in percent is plotted against standard length minus snout length. Speci- mens greater than 9 mm in standard length (greater than 7.5 mm in standard length minus snout length) showed separation into two groups. The 10 speci- mens with values greater than 75 percent included 68 Gular membrane Branchiostegal Pay and membrane a. Chromatophore on tip of lower jaw ostegal Figure 1.—Diagramatic sketches of the pigment pattern on the lower jaw, gular and branchiostegal membrane of young istiophorids. a. Pigment pattern exhibits chromatophores concentrated on the tip of the lower jaw, one chromatophore on the posterior edge of the gular membrane midline, and no chromatophores on the bran- chiostegal membrane. b. Pigment pattern exhibits chromatophores extending along % the length of the left and right rami of the lower jaw, a row of cells on the midline of the gular membrane, and no chromatophores on the branchiostegal membrane. c. Pigment pattern exhibits chromatophores extending along %4 the length of the lower jaw rami, one cell on the posterior edge of the gular mem- brane midline, and one cell on the midline of the branchio- stegal membrane. d. Pigment pattern exhibits chromato- phores extending along % of the length on the right rami and along % of the length of the left rami of the lower jaw, one cell on the midline of the gular membrane, and one cell on the branchiostegal membrane. three blue marlin identified by Ueyanagi and seven specimens from my collections. These 10 have short snouts and I feel confident that they are blue marlin. In other plots which involved snout length, these 10 specimens were obviously different. I then ex- amined the additional data from these 10 specimens to see ifthey shared any other character. Eight of the 10 lacked gular pigment; the other two (a 10-mm specimen provided by Ueyanagi and a 12.1-mm specimen from my Miami material) each had one 200: 180 ) e BLUE MARLIN 160 © UNKNOWN SPECIES 140 5 "9 =z = 120: Lone 3 Ser, = ge eFBo e ° co 8 GIP ‘ e = § [om e = & 80 ° e = : ° e %e = RO ae r—) eprey hs = 60 P Pas oP 3 » 5 20 i?) 2 4 6 8 10 12 4 16 18 20 STANDARD LENGTH MINUS SNOUT LENGTH Figure 2.—Relation between eye diameter divided by snout length expressed in percent and standard length minus snout length in mm for istiophorid young. Blue marlin indicated by open circles, unknown species by closed circles. chromatophore on the midline of the gular mem- brane. None of the 10 had any pigment on the bran- chiostegal membrane. Lower jaw pigment was con- fined to the tip or never extended back further than Y the length of the ramus. Eight of the 10 specimens had the tip of the snout below a plane drawn along the body axis through the eye; two had the tip level with the eye (the 12.1-mm Miami specimen and a 9.9-mm specimen from the Gulf of Mexico). The nature of the pterotic spine was variable—five specimens had nearly level spines, two had their spines projecting sharply upwards, and three had their spines directed upwards at a slight angle. The anterior edge of the orbit projected anteriad but no more so than many of the long-snouted specimens. The three blue marlin identified by Ueyanagi, which were smaller than 9 mm in standard length, are also shown in Figure 2. They are very similar to the other blue marlin specimens. They all lacked gular pigment, had pigment confined only to the tip of the lower jaw, lacked branchiostegal pigment, and had the tip of the snout below the level of the eye. Two of the specimens had sharply angled upward pterotic spines, while one had this spine slightly angled up- ward. All of the remaining specimens were grouped ac- cording to their pigment patterns. These groups are: 69 Group 1—distinct row of pigment on gular mem- brane midline; no branchiostegal pigment. Group 2—distinct row of pigment on gular mem- brane midline; branchiostegal pigment present. Group 3—two or three pigment cells on bran- chiostegal membrane; no branchiostegal pigment. Group 4—two or three pigment cells on gular membrane midline; branchiostegal pigment present. Group 5—one pigment cell on gular membrane midline; no branchiostegal pigment. Group 6—one pigment cell on gular membrane midline; branchiostegal pigment present. Group 7—no pigment on gular membrane mid- line; no branchiostegal pigment present. Group 8—no pigment on gular membrane midline; branchiostegal pigment present. The numbers of specimens in each of these groups, their size range, and frequency occurrence of the other characters studied are shown in Table 4, along with the data on the 13 blue marlin specimens. As one can see, there does not seem to be any relation between any particular set of characters one may choose. Those five specimens shown in Figure 2 with eye/snout percentages greater than 120 per- cent (very short snout) occur in Groups 7 (1), 1 (2), 5 (1), and 6 (1). Categorizing the blue marlin speci- mens in a like manner, 11 would be included in Group 7 and 2 included in Group 5S. If there is valid- ity to these groups then two of these five small specimens could be considered to be blue marlin since they occur in Groups 5 and 7. I have presented this evidence to illustrate the variability of the characters used to identify larvae. Table 4 demonstrates that one can choose any par- ticular character and separate larvae into groups, but it is difficult to substantiate any particular character with other characters. Since my material comes from a relatively small area, I may not have young of all the species which occur here. But whatever is the case, it appears that there is a great deal of variation in the characters. Ueyanagi’s studies have been based on Pacific material so, perhaps, the variability that I find is confined to Atlantic specimens. CONCLUSIONS It is evident that a great deal of work is necessary to resolve the identity of young istiophorids. Primar- ily, it is necessary to collect a great deal of material from different areas and at different times of the year. Information from gonad maturation studies of all the species would be helpful to predict where and Table 4.—Frequency distribution of pigment patterns, snout and pterotic spine positions for istiophorid larvae. Branchiostegal lower jaw Pigment on Pterotic spine Gular Pigment pigment ramus direction Snout to eye Group or Size range 2-3 ] 0 Pres- Ab- species No. (mmSL) Row cells cell cell ent sent >% <% _ up _ intermediate level below level above 1 9 3.3-20.2 9 0 0 0 0 9 9 0 0 3 6 7 0 2 2 2 5.9-11.5 2 0 0 0 2 0 2 0 0 2 0 2 0 0 3 6 4.7-10.0 0 6 0 0 0 6 2 4 0 3 3 S 1 0 4 4 4.5- 7.6 0 4 0 0 4 0 2 2 1 2 1 4 0 0 5 21 3.7-10.9 0 0 21 0 0 21 9 12 5 8 8 16 5 0 6 14 4.4-14.5 0 0 14 0 14 0 6 8 3 2 9 12 1 1 7 9 2.8- 9.3 0 0 0 9 0 9 2 7 2 2 5 7 2 0 8 8 5.3-11.3 0 0 0 8 8 0 3 5 3 2 3 5 2 1 Blue 13 3.7-20.8 0 0 2 11 0 13 0 13 4 4 5 11 2 0 marlin when young may be expected. Now that we have the ability to rear pelagic fishes from the egg, a concentrated effort directed at billfish would be a great step towards solving the problem. It is also necessary to study internal features of the young, particularly the osteology of the axial skeleton which has proved useful for identifying young tunas. ACKNOWLEDGMENT I want to express my deepest gratitude to my colleague and friend Shoji Ueyanagi, Far Seas Fisheries Research Laboratory, Shimizu, Japan, for his interest in my studies of these fishes. Ueyanagi suggested many of the various avenues of research which I followed in this study and I greatly ap- preciate all of his help and encouragement. LITERATURE CITED ARATA, G.F., JR. 1954. A contribution to the life history of the swordfish, Xiphias gladius Linnaeus, from the South Atlantic coast of the United States and the Gulf of Mexico. Bull. Mar. Sci. Gulf Caribb. 4:183-243. ARNOLD, E.L., JR. 1955. 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Wise and Gabrielle M. Ranallo, 1967, Transl. No. 12 of the Trop. Atl. Biol. Lab., 49 p.; avail. at Bur. Commer. Fish. (Natl. Mar. Fish. Serv.), Miami, Fla.] REGAN, C.T. 1909. On the anatomy and classification of the scombroid fishes. Ann. Mag. Nat. Hist., Ser. 8, 3:66-75. 1924. A young swordfish (Xiphias gladius), with a note on Clupeolabrus. Ann. Mag. Nat. Hist., Ser. 9, 13:224-225. ROBINS, C.R., and D.P. DE SYLVA. 1960. Description and relationships of the longbill spear- fish, Tetrapturus belone, based on western North Atlan- tic specimens. Bull. Mar. Sci. Gulf Caribb. 10:383-413. 1963. A new western Atlantic spearfish, Tetrapturus pflue- geri, with a redescription of the Mediterranean spearfish Tetrapturus belone. Bull. Mar. Sci. Gulf Caribb. 13:84-122. RUPPELL, M.E. 1835a. Mémoire sur une nouvelle espece de poisson du genre Histiophore, de la Mer Rouge. Trans. Zool. Soc. Lond. 2:71-74, plus 1 plate. 1835b. 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On Kajikia formosana (Hirasaka et Nakamura). [In Jap., Engl. summ.] Rep. Nankai Reg. Fish. Res. Lab. 6:107-112. 1959. Larvae of the striped marlin, Makaira mitsukurii (Jordan et Snyder). [In Jap., Engl. summ.] Rep. Nankai Reg. Fish. Res. Lab. 11:130-146, 2 pl. 1960a. On the larvae and the spawning areas of the shiroka- jiki, Marlina marlina (Jordan & Hill). [In Jap., Engl. 72 summ.] Rep. Nankai Reg. Fish. Res. Lab. 12:85-96. 1960b. Preliminary note on the larvae of the shortnosed spearfish, Tetrapturus angustirostris (Tanaka). [In Jap., Eigl. summ.] Rep. Nankai Reg. Fish. Res. Lab. 12:97-98. 1962. On the larvae of the shortnosed spearfish, Tetrapturus angustirostris Tanaka. [In Jap., Engl. summ.] Rep. Nankai Reg. Fish. Res. Lab. 16:173-189. 1963a. Methods for identification and discrimination of the larvae of five istiophorid species distributing in the Indo-Pacific. [In Jap., Engl. summ.] Rep. Nankai Reg. Fish. Res. Lab. 17:137-150, 4 pl. 1963b. A study of the relationships of the Indo-Pacific is- tiophorids. [In Jap., Engl. summ.] Rep. Nankai Reg. Fish. Res. Lab. 17:151-165, 2 pl. 1964. Description and distribution of larvae of five is- tiophorid species in the Indo-Pacific. Mar. Biol. Assoc. India. Proc. Symp. Scombroid Fish. Mandapam Camp, Part I:499-528. UEYANAGI, S., NISHIKAWA. 1970. Distribution, spawning, and relative abundance of billfishes in the Atlantic Ocean. [In Jap., Engl. summ.] Bull. Far Seas Fish. Res. Lab. (Shimizu), 3:15-55. UEYANAGI, S., and H. WATANABE. 1962. Methods of identification for larval billfishes and young tunas (I). [In Jap.] Prelim. Rep. Nankai Reg. Fish. Res. Lab., Kochi, 17 p. 1964. Methods of identification of larvae of tunas and young billfishes (II]). Nankai-ku suisan kenkyo-sho, maguro gyogyo kenkyu kyogikai shirajo (Nankai Reg. Fish. Res. Lab., Materials for Tuna Fisheries Research Council, Kochi). 16 p. (In Jap., Engl. translation of sec- tions pertaining to larval tunas by Bur. Commer. Fish., Honolulu). UEYANAGI, S., and H. YABE. 1959. Larva of the black marlin (Eumakaira nigra Nakamura). [In Jap., Engl. summ.] Rep. Nankai Reg. Fish. Res. Lab. 10:151-169. 1960. On the larva possibly referable to Marlina marlina (Jordan & Hill). Records of Oceanographic Works in Japan, New Ser. 5(2):167-173. VOSS, G.L. 1953. A contribution to the life history and biology of the sailfish, Istiophorus americanus Cuv. and Val., in Florida waters. Bull. Mar. Sci. Gulf Caribb. 3:206-240. WATANABE, H., and S. UEYANAGI. 1963. Young of the shortbill spearfish, Tetrapturus angus- tirostris Tanaka. [In Jap., Engl. summ.] Rep. Nankai Reg. Fish. Res. Lab. 17:133-136. YABE, H. 1951. Larva of the swordfish Xiphias gladius. [In Jap., Engl. summ.] Jap. J. Ichthyol. 1:260-263. 1953. On the larvae of sailfish, /stiophorus orientalis collected in the South-western Sea of Japan. [In Jap., Engl. summ.] Contrib. Nankai Reg. Fish. Res. Lab. 1(6):1-10. YABE, H., S. UEYANAGI, WATANABE. 1959. Study on the life-history of the sword-fish Xiphias gladius Linnaeus. [In Jap.. Engl. summ.] Rep. Nankai Reg. Fish. Res. Lab. 10:107-150. S. KIKAWA, M. UTO, and Y. S. KIKAWA, and H. On an Additional Diagnostic Character for the Identification of Billfish Larvae with Some Notes on the Variations in Pigmentation SHOJI UEYANAGI ABSTRACT The larvae of five species of billfishes (Istiophoridae) occurring in the Indian and Pacific Oceans —sailfish, [stiophorus platypterus; shortbill spearfish, Tetrapturus angustirostris; striped marlin, T. audax; blue marlin, Makaira mazara; and black marlin, M. indica—have now been identified. The identification of these larvae has depended on such characters as the shape of the pectoral fin, pigmentation of the branchiostegal membrane, pigmentation of the lower jaw membrane, and head profile. Some problems in identification remain, however, as for example in the differentiation between very small larvae (under 7 mm) of striped marlin and blue marlin. Recent studies have resulted in additional diagnostic characters which differentiate between these two species, namely the differences in the pterotic and preopercular spines. The larvae of sailfish generally have pigment on the posterior half of the lower jaw, and this pigmentation is recognized to be species specific. There exist, however, some larvae of this species which lack this characteristic pigmentation, and the occurrence of these larvae seems to vary geographically from the more typical sailfish larvae. One of the problems related to the identification of billfish larvae concerns the identification of the lar- vae of striped marlin, Tetrapturus audax. The head profile (“‘the tip of the snout and the midpoint of the eye are on a nearly equal level’’) has been regarded as a diagnostic character for this species. However, unlike the pigmentation pattern, this character is rather difficult to use, and there is a possibility of error depending on the physical condition of the specimens examined. For example, sailfish, /s- tiophorus platypterus, larvae have been erroneously identified as striped marlin due to the occasional close resemblance in this particular character (Ueyanagi, 1959: Figs. 4 and 5; Ueyanagi, 1963). Furthermore, in very small specimens of striped marlin and blue marlin, Makaira mazara, where the snout has not yet lengthened, discrimination be- tween the two species is very difficult. Because of these problems in identification, further studies were conducted to locate additional diagnostic characters. As a result, it was found that the pterotic and preopercular spines are effective "Far Seas Fisheries Research Laboratory, Shimizu, Japan. 73 characters particularly in differentiating the larvae of striped marlin from those of the other species. GENERAL DESCRIPTION OF THE PTEROTIC AND PREOPERCULAR SPINES Spination on the head is a prominent characteristic of the larval stages of billfishes, and chief among the spines are the pterotic spine and the main preopercu- lar spine (the latter is hereafter referred to simply as preopercular spine). Although there are some varia- tions among species in the length of the spines, the development of the spines appears to progress uni- formly in all species. For this reason, the following general description of the development of these spines is restricted to that of blue marlin. The pterotic and preopercular spines are absent in larvae under 3 mm in total length. After about 3 mm, the spines appear. They lengthen rapidly with growth of the larvae and are markedly developed when the larvae are about 6-7 mm long. At this size, the preopercular spine reaches slightly posterior of the anus when pressed against the side of the body. After the larvae exceed about 8 mm, the pterotic spine becomes shorter relative to body length, and growth rate of the preopercular spine also decreases with growth of the larvae. At a length of 11-12 mm, these spines virtually stop growing and their lengths relative to body length begin decreasing. DESCRIPTION OF THE PTEROTIC AND PREOPERCULAR SPINES BY SPECIES The following is a brief description of the pterotic and preopercular spines in the larvae of the Indo- Pacific billfishes. Black marlin, M. indica, is omitted due to lack of sufficient numbers of specimens. All descriptions are of the lateral aspect of the larvae. Blue marlin (Fig. 1) The pterotic spine rises obliquely from its base. In specimens larger than 4 mm, the spine tip extends well beyond the dorsal profile of the larva. The preopercular spine is slightly concave downwards near its base but on the whole, it is very slightly Figure 1.—Larvae of blue marlin, Makaira mazara. Top to bottom: 3.5, 6.0, and 7.6 mm in total length. concave upward. Viewing it from the side, it runs very nearly parailel to the ventral profile of the larva. Sailfish (Fig. 2) The pterotic spine rises obliquely from its base. The spine is relatively longer than in the larvae of other species, and its tip extends markedly beyond the dorsal profile. As in the blue marlin the preoper- cular spine extends parallel to the body axis of the larva but it is not as curved as in blue marlin. Shortbill spearfish, T. angustirostris (Fig. 3) Both the pterotic and preopercular spines are shaped very similarly to those in the blue marlin. The preopercular spine is, however, shorter than in blue marlin and is also inclined further downward. Fur- thermore, the secondary preopercular spines are quite well developed in this species. Figure 2.—Larvae of sailfish, /stiophorus platypterus. Top to bottom: 4.2, 6.5, and 8.3 mm in total length. Striped marlin (Fig. 4) In specimens under 4 mm in total length, the ptero- tic spine is inclined very slightly upward from the base, but with growth of the larvae, it runs very nearly parallel to the body axis. Thus the spine tip does not extend beyond the body profile as in other _ species. The preopercular spine is inclined sharply downward, forming a large angle with the body axis. The spine is nearly parallel to a line which might be drawn along the edges of the upper and lower jaws. In order to facilitate comparison of the spines in the different species, schematic drawings of head profiles of the four species were prepared (Fig. 5). USE OF THE SPINES AS DIAGNOSTIC CHARACTERS The larvae of sailfish and shortbill spearfish can be identified reliably on the basis of pigmentation on the lower jaw or on the branchiostegal membrane and | Figure 3.—Larvae of shortbill spearfish, Tetrapturus an- _ gustirostris. Top to bottom: 3.6, 5.5, and 8.6 mm in total length. Figure 4.—Larvae of striped marlin, Tetrapturus audax. Top to bottom: 4.1, 5.6, and 8.9 mm in total length. therefore identification of these species need not depend on supplementary characters such as spines. In the case of the blue marlin and striped marlin, however, supplementary diagnostic characters are essential in order that these species may be identified without error. The spine characteristics are particu- larly useful in differentiating the very small larvae, especially of blue and striped marlin smaller than 7 mm. As mentioned previously, there are occasional specimens of sailfish larvae whose head profile very closely resemble that of striped marlin larvae. In these cases, also, the use of the supplementary characters will prevent errors in identification. Although both the pterotic and preopercular spines tend to ‘‘degenerate”’ after the larvae attain a certain size, and thus become less useful as diagnos- tic characters, there are fortunately other characters which can be used effectively in the identification of larger specimens. The spines are thus useful and A. BLUE MARLIN. B. STRIPED MARLIN C. SAILFISH D. SHORTBILL SPEARFISH Figure 5.—Head profiles of larvae of four species of Indo-Pacific billfishes, with emphasis on the pterotic and preopercular spines. (Top row—about 4 mm; middle—about 6 mm; bottom—about 8 mm.) effective diagnostic characters for larvae generally under 12-13 mm in total length. The spines are occasionally found broken on specimens, but this should not deter their use since striped marlin can be reliably identified if there are at least one-half of the pterotic spine and one-third of the preopercular spine left for examination. THE LARVAE OF ATLANTIC BILLFISHES Although detailed studies were not possible due to the small numbers of larvae available from the Atlan- tic Ocean, it was, however, noted that the features of the pterotic and preopercular spines of the Atlantic species closely resembled those of the related Indo-Pacific species. Namely, the spines on the lar- vae of the Atlantic blue marlin, M. nigricans (Fig. 6), resembled those of the Indo-Pacific blue marlin; those of the Atlantic white marlin, T. albidus (Fig. 7), resembled those of the Indo-Pacific striped mar- lin; those of the Atlantic longbill spearfish, T. pflue- geri (Fig. 8), resembled those of the Indo-Pacific shortbill spearfish: and those of the Atlantic sailfish, 76 I. albicans (Fig. 9), resembled those of the Indo- Pacific sailfish. Thus it appears that the differentia- tion between the larvae of the Atlantic blue marlin and white marlin can also be made on the basis of these spines. VARIATIONS IN PIGMENTATION OF THE LOWER JAW OF SAILFISH Based on five specimens, Ueyanagi (1963) pre- sented a preliminary report on sailfish larvae which lacked the characteristic pigmentation on the pos- terior half of the lower jaw. Since then, additional studies have resulted in the examination of 37 such Figure 6.—Larva of the Atlantic blue marlin, Makaira nigricans, 9.0 mm in total length. Figure 7.—Larvae of the Atlantic white marlin, Tetraptu- rus albidus. Upper, 6.5 mm; lower, 11.2 mm in total length. Figure 8.—Larva of the Atlantic longbill spearfish, Te- trapturus pfluegeri, 8.3 mm in total length. Figure 9.—Larva of the Atlantic sailfish, Istiophorus albi- cans, 11.8 mm in total length. specimens from the Coral Sea and 23 from the waters northwest of Australia. The Coral Sea specimens CU measured between 2.5 and 29.5 mm while the latter group of specimens measured 4.0-37.6 mm in total length. All of the specimens lacked the characteristic pigmentation, but from head profile and body form characteristics, they were identified as larvae of sail- fish. The areas of capture of sailfish larvae, both those with and without pigmentation, were plotted by unit areas of 1° square (Fig. 10). The larvae of sailfish are very sparsely distributed in offshore pelagic waters. Rather, they tend to be found most abundantly near land masses. This is seen to be true for both the pigmented and non- pigmented specimens. The non-pigmented larvae, however, seem to show an even greater affinity for land masses. Generally, both types of larvae were found in waters northwest of Australia (south of lat. 10°S), but in the Coral Sea the specimens were ex- clusively those whichlacked pigmentation. In regard to the occurrence of the non-pigmented sailfish larvae, Ueyanagi (1963) pointed out the pos- sibility that these may represent a separate subpopu- lation or even be larvae of another species. Since from the taxonomic point of view it is very unlikely that they can be another species, I shall discuss some points here relating to the possibility that these are larvae of a separate subpopulation of sailfish. These points are: 1) It is unlikely that these are specimens in which the pigments had faded since there are as many as 60 such specimens available. While it does appear that the pigments on the lower jaw do fade out after the larvae reach about 60 mm in length, the specimens on hand are all under 40 mm in total length. 2) If these non-pigmented cases are due to indi- vidual variations, they would be expected to be dis- tributed randomly throughout the distributional area rather than localized as in Figure 10. 3) It has been seen that pigmentation in the larval stages of closely related species is very similar. For example, the larvae of the Indo-Pacific shortbill spearfish and the Atlantic longbill spearfish both have pigmentation on the branchiostegal membrane. The Indo-Pacific sailfish and the Atlantic sailfish both have a pigmented lower jaw in their larval stages. These pigmentation patterns can therefore be considered to manifest close genetic relation- ships. The non-pigmented types are very probably variations of a genetic nature rather than those re- sulting temporarily from environmental influences. Judging from the above-mentioned points, it ap- pears that the non-pigmented larvae of the sailfish @- TYPICAL PIGMENTED LARVAE Sailfish x - LARVAE WITHOUT PIGMENTS HB - BOTH A AND B (A). (B). E Figure 10.—The occurrence of the two types of sailfish larvae (typical pigmented larvae and larvae without pigments) in the Indian and Pacific Oceans. belong to a separate subpopulation from the pig- mented larvae. To prove this point will require de- tailed studies on the ecology of the larvae as well as of the adults. If this hypothesis is correct, then studies of larval morphology will contribute not only to species identification, but also serve as a new approach towards population identification. ACKNOWLEDGMENTS _I wish to sincerely thank Tamio Otsu of the Na- tional Marine Fisheries Service, Honolulu, who helped me with the English translation of the manu- script. Thanks are also due to Walter M. Matsumoto 78 who read the manuscript. I am grateful to Teiko Doi who assisted in finding the diagnostic characters of the larvae and prepared the illustrations. LITERATURE CITED UEYANAGI, S. 1959. Larvae of the striped marlin, Makaira mitsukurii (Jordan et Snyder). (In Japanese, English summ.) Rep. Nankai Reg. Fish. Res. Lab. 11:130-146, 2 plates. 1963. Methods for identification and discrimination of the larvae of five istiophorid species distributing in the Indo- Pacific. (In Japanese, English summ.) Rep. Nankai Reg. Fish. Res. Lab. 17:137-150, 4 plates. Comparative Development of Atlantic and Mediterranean Billfishes (Istiophoridae)' DONALD P. DE SYLVA? and SHOJI UEYANAGI? ABSTRACT Developmental stages from about 5 mm to the adult stage are described, illustrated, and compared for the following species: Atlantic sailfish, /stiophorus platypterus; white marlin, Tetrapturus albidus; Mediterranean spearfish, Tetrapturus belone; longbill spearfish, Tetrapturus pfluegeri; and Atlantic blue marlin, Makaira nigricans. Most descriptions are based on material from the western North Atlantic Ocean including the DANA collections from the Sargasso Sea. The status of two other billfish—Tetrapturus georgei from the eastern Atlantic and the so-called ‘‘hatchet marlin’’ of the western Atlantic—is discussed briefly in reference to the identity of an unidentifiable juvenile from the Mediterranean Sea. ‘This paper was presented orally, but only title and abstract were submitted for publication. The full text of the paper will be submitted to the DANA Reports for publication. “School of Marine and Atmospheric Science, University of Miami. *Far Seas Regional Fisheries Station, Shimizu, Japan. 79 Section 2.—-Life History. Life History of the Atlantic Blue Marlin, Makaira nigricans, with Special Reference to Jamaican Waters! DONALD P. DE SYLVA? ABSTRACT Nomenclature and systematics of the Atlantic blue marlin are briefly reviewed. Its seasonal distribu- tion in the Atlantic is analyzed from commercial and sport fish records. The spawning season in the North Atlantic, which occurs from late spring through late fall, is discussed. Larvae and juveniles are not common, but are easily identifiable. Spawning probably occurs far offshore, with the young developing in waters of the high seas. Feeding probably occurs in the deeper strata. Tunas, frigate mackerels, and cephalopods are the main food items. The growth rate has not been determined, but it is suspected that blue marlin exceed 15 years. Females attain a much larger size than the males; this is attributed to differential mortality. The blue marlin probably undergoes reasonably extensive migrations, and may be considered to comprise populations at least in the North Atlantic and South Atlantic Oceans. The sport fishery, which is extensive and expensive, and valuable economically, is thoroughly discussed. The commercial fishery for the species in the Atlantic is incidental to the tuna fisheries, yet there are some indications that the blue marlin is in some danger of being depleted through commercial activities. "This paper was presented orally, but only title and abstract were submitted for publication. “School of Marine and Atmospheric Science, University of Miami. On the Biology of Florida East Cost Atlantic Sailfish, (Istiophorus platypterus)' JOHN W. JOLLEY, JR.’ ABSTRACT The sailfish, [stiophorus platypterus, is one of the most important species in southeast Florida’s marine sport fishery. Recently, the concern of Palm Beach anglers about apparent declines in numbers of sailfish caught annually prompted the Florida Department of Natural Resources Marine Research Laboratory to investigate the biological status of Florida’s east coast sailfish populations. Fresh specimens from local sport catches were examined monthly during May 1970 through September 1971. Monthly plankton and ‘‘night-light’’ collections of larval and juvenile stages were also obtained. Attempts are being made to estimate sailfish age using concentric rings in dorsal fin spines. If successful, growth rates will be determined for each sex and age of initial maturity described. Females were found to be consistently larger than males and more numerous during winter. A significant difference in length-weight relationship was also noted between sexes. Fecundity estimates varied from 0.8 to 1.6 million ‘“‘ripe’’ ova, indicating that previous estimates (2.5 to 4.7 million ova) were probably high. Larval istiophorids collected from April through October coincided with the prominence of ‘‘ripe’’ females in the sport catch. Microscopic examination of ovarian tissue and inspection of ‘‘ripe’’ ovaries suggest multiple spawning. Florida’s marine sport fishery has been valued asa $200 million business (de Sylva, 1969). Atlantic sail- fish, Istiophorus platypterus (Shaw and Nodder), range throughout coastal waters and reside year- round in Florida where they are prominent among some 50 species of marine sport fishes. Sailfishing on Florida’s east coast became popular during the 1920’s and 1930’s (Voss, 1953). Sailfish have been categorized as the most sought-after species by southeast coast marine charter boat anglers (Ellis, 1957). In addition, Ellis showed that sailfish were taken on 20% of the fishing trips sampled, but made up only 3 to 5% of the total numbers of fish caught. McClane (1965) estimated that more than 1,000 sail- fish were caught each year between Stuart and Palm Beach: thus, this area became knownas the ‘“‘sailfish capital of the world.” The University of Miami Marine Laboratory (now Rosenstiel School of Marine and Atmospheric Sciences) initiated studies on the biology of sailfish ‘Florida Department of Natural Resources Marine Research Laboratory Contribution No. 208. *Florida Department of Natural Resources Marine Research Laboratory, 100 Eighth Avenue SE, St. Petersburg, FL 33701. 81 in 1948 at the request of the Florida Board of Con- servation (now Florida Department of Natural Re- sources [FDNR]). Voss (1953, 1956) described post- larval and juvenile stages and discussed the general biology of Florida’s sailfish populations. De Sylva (1957) described age and growth from length fre- quencies from the sport catch (Petersen method), but suggested the results be checked by a more con- ventional method; specifically, annular marks. Further, de Sylva found a wide range in weight for a given length and age, suggesting the possibility of differential growth and/or mortality of sexes. Gross morphology and histology of gonads from Indian Ocean billfishes were described by Merrett (1970), but a thorough understanding of maturational cycles in Atlantic sailfish has yet to be obtained. Florida’s interest in the species was renewed in March 1970 by local concern for the welfare of the Palm Beach sailfishery. John Rybovich, Jr., repre- senting local charter boat captains and anglers. ex- amined catch statistics compiled by the West Palm Beach Fishing Club and Game Fish Research As- sociation, Inc., and noted that the yearly catch of ‘“‘gold button’’ sailfish (specimens eight feet or longer) had decreased significantly since 1947 (Fig. 1). Two gold button sailfish were reported in 1970, six in 1971, and three in 1972. In addition, total numbers of sailfish of all sizes declined during the famous Silver Sailfish Derby from 1948 to 1967 (Fig. 2). Palm Beach anglers presumed that these declines represented a reduction in numbers of locally avail- able sailfish. However, verification of their conclu- sion relies upon careful examination of several con- tributing factors. An objective examination into the apparent de- cline of total numbers of sailfish (Fig. 2) revealed 110 40 Gold Button Sailfish (number) a ° ++ $+ + +++ Figure 1.—Total number of *‘gold button”’ sailfish record- ed by the West Palm Beach Fishing Club, 1935 to 1971. A “ell i c 355 q — no.sailfish 2 \ \ =< no. boat-days x . \. 5 ~ 30 \ a) 3 x Se bu riia F “4 0 xh ay . wy 20), ‘ aA = 3 oN qs SPN Oe on SNS me SN . Cus | NN u | ~ x= ow 10+F -~ Ne- Cee ane enews PR Re Eh ee ew he Penta - a | Om Or era sel) Gem ir tecepens [at akl Wot y VF ve5s= oO 5} 1935-39 40-47 48-52 53-57 58-62 63-67 YEARS Figure 2.—Sailfish catch and effort data reported for five- year periods during the Silver Sailfish Derby, 1935 to 1971. 82 Mean Number Of that Silver Sailfish Derby tournament effort (boat- days) decreased concomitantly (except during 1953-57) and apparently has stabilized since 1967. Reasons for this decline are not known. Calculations of catch per unit of effort (Fig. 3) from three popular — Silver Sailfish Derby *~< Masters Angling Tournament Sailfish/Boat /Day no data 25 L “s 1935 + + +h 50 55 70 Year + 40 Figure 3.—Mean catch per unit of effort calculated from records of three popular sailfishing tournaments. sailfishing tournaments held in the Palm Beaches (Silver Sailfish Derby, 1935 to 1971; International Women’s Fishing Association, 1956 to 1966; and Masters Angling Tournament, 1963 to 1971) re- vealed fluctuating patterns of relative abundance, but did not suggest a continued decline. Combined mean catch per unit of effort for these tournaments was 1.31 sailfish/boat-day (approximately 0.16 to 0.22 sailfish per hour). These figures exceed those reported for sailfisheries in the Gulf of Mexico (Nakamura, 1971; Nakamura and Rivas, 1972) and those at Malinda, Kenya (Williams, 1970). Wise and Davis (1973) found that Japanese longline catches in the Atlantic during 1956 to 1968 showed a signifi- cant increase in sailfish and spearfish per 1,000 hooks fished. This apparently suggests that the magnitude of Atlantic sailfish stocks had not been affected ad- versely up to 1968. Obviously there is much contradictory informa- tion. Many knowledgeable anglers and boat captains insist that tournament catch per unit of effort has been maintained only by extending the fishing area northward in recent years and improving fishing methods. Thus the FDNR initiated studies designed to fully investigate the biological status of the species. Further assessment of the welfare of south- east Florida sailfish stocks may then be made. METHODS AND MATERIALS Sailfish taken by the sport fishery were examined from May 1970 through September 1971. Weekly visits to Pflueger Taxidermy in Hallandale and West Palm Beach, and Reese Taxidermy in Fort Lauder- dale, facilitated examination of moderate numbers of specimens taken mainly from offshore Fort Pierce to Miami (Fig. 4). Occasionally, specimens from Georgia, Virginia, Bahamas, Florida Keys, and Destin, Florida were also examined. Twenty-five to 35 fresh specimens were selected each month from a size range representative of the sport catch. Total, fork, standard, ‘‘body’’ (Rivas, 1956), and ‘‘trunk’’ (de Sylva, 1957) lengths were obtained to the nearest 0.5 cm with a 3 m measuring board. Total weight was taken to the nearest 0.2 kg, using a 68.0 kg capacity Chatillon (Model 100)° spring scale. Additional information was recorded concerning position of hook, bait used in capture, stomach contents, and presence of para- sites Two or three anterodorsal fin spines from each specimen were cleaned and placed in numbered en- velopes. Spines were allowed to dry for several months before sectioning with a No. 409 emery disk (24.0 mm diameter x 0.5mm thickness) mounted ina high speed Dremel Moto Tool (Model 270) with speed control (Model 219). This unit was mounted on an aluminum platform. A spring-loaded battery clamp was attached to a 180° rotating lever approxi- mately 1 inch in front of the tool chuck. This securely held each spine during sectioning. Two or three cross sections were cut at 2.5 to 5.0 mm above the expanded base (condyle) of each spine (Fig. 5). Each section was then ground to approximately 0.75 mm with a No. 85422 grinding stone at low speed. Spinal sections were stored dry because water or glycerol causes excessive clearing. During examinations, however, spinal sections were temporarily im- mersed in glycerol and examined with a binocular dissecting microscope against a black background under reflected light. Circuli in each section have been counted once, but three additional independent readings will be made later by two biologists without reference to collection data. Gonadal condition was evaluated macroscopi- cally and a sample of tissue was removed for his- tological preparation. Gonadal tissue was initially z Reference to trade names does not imply endorsement by the National Marine Fisheries Service, NOAA. 83 7e000 / Py (aren ! ie ro e* - ’ ee 7 7 1 / rc W 1 1 U a ! Sa) H) y het ; ea ead f 4s © f = 4 < He ECE 1 o \ * i} d \ , 1 7 F PJ » ° ei: : So ) Fm i > ; pcteaet Witt) ! ’ ‘ 4 Paim Beach{x * * x Be ass) ! t \ / E fitg wt eat N u 7 >, i .) ite f} ) \ 1 u ) eaten wD v A) > U ' \ 2 N ) i ty rr) x I t i f 4 \ wD - S =3 ee > IOS 26°00! My _ (7 a a9 7 J # le i bd 4 ) V s > or 1A ul Be te) 10 if Q L$ Nautical Miles \ 2 Figure 4.—Chart of southeast Florida showing area where most sailfish were obtained (almost the entire catch was taken between 10 and 100 fathoms). X’s indicate station locations of monthly plankton and night-light collections. Aperiodic daylight collecting trips were conducted 5 to 15 nautical miles north and south of Palm Beach. Arrows indicate axis of Florida current; soundings in fathoms. IO EOC alae Figure 5.—Dorsal spine base, shaft and two sections after cutting. preserved with Zenker’s fixative. Tissue was rinsed with tap water and stored in Lugol’s solution 18 to 36 h after collection. It was necessary to thoroughly leach out all fixative before final storage. At the St. Petersburg laboratory, gonadal tissue was imbedded in paraffin and sectioned at 6 z . Slides were stained with Papanicolaou Haematoxylin (Harris) and Eosine Y, and with another stain developed by the histology laboratory. These slides are presently available for microscopic examination. During the spawning season, whole ‘‘ripe’’ ovar- ies from fish weighing 15.9 to 38.0 kg (35.0 to 84.0 lb) were removed, weighed to the nearest 10 grams, and injected with 10% Formalin for fecundity esti- mates. These ovaries were usually ‘‘running ripe,” i.e., large ova had ruptured from follicles and were flowing into the center of the lumen. Fecundity esti- mates were obtained by the subsampling by weight method described by Bagenal and Braum (1968) and Moe (1969). Techniques for determining distribu- tion of mature ova within various sections of the ovary followed Otsu and Uchida (1959). Ova were successfully disassociated from ovarian tissue with microdissecting needle and forceps. Monthly plankton and night-light collections were conducted from June 1970 through October 1971. Surface and oblique tows were made with | m plank- ton nets (mesh size 602 for body section and 295 for cod end). Supplemental daylight collecting trips were conducted aperiodically. RESULTS AND DISCUSSION Age and Growth De Sylva (1957) reported that sailfish grow rapidly, attaining a weight of 9.1 kg (20 lb) within a year. Using the Petersen method, he estimated the average life span as 2-3 yr, but suggested that these results be checked by the more conventional as- sessment method of utilizing annular marks. AI- though Koto and Kodama (1962) indicated that cir- culi in scales, otoliths, centra, and fin rays of ‘*Mar- lin’? could not be recognized as annular, considera- ble effort is being expended to develop a technique to age individual sailfish. Sailfish pectoral and dorsal fin spines, branchiostegal rays, operculi, and ver- tebral centra were examined for growth marks; scales and statoliths were considered too small to be used. Two structures, vertebral centra and dorsal fin spines, showed distinct circuli which appeared to increase in number with fish length. However, each sailfish centrum is fused to part of the adjacent neural arch, and it is extremely difficult to remove the centra without damaging a specimen destined for trophy mounting. Therefore, dorsal fin spines III, IV, and V were selected as the aging structure since each of these spines has a relatively large base and is easily extracted. Spine removal poses no problem 84 for the taxidermist because dorsal fins are not used in trophy preparation. Increase in trunk length was compared with in- crease in width of the fourth (IV) spine for 132 specimens (Fig. 6). The linear equation, y = 47.600 + 9.881x, describes a line fitting the regression. An analysis of variance (Table 1) attests to the goodness of fit, thus satisfying the proportional growth re- quirement for use of a bony structure in aging (Par- rish, 1958; Watson, 1967). N=132 y* 47.600+9.881x r=0.903 TRUNK LENGTH (mm:10’) 3.0 4.0 5.0 6.0 7.0 8.0 90 100 11.0 12.0 SPINAL WIDTH (mm) Figure 6.—Relationship of trunk length and fourth dorsal spine width. Spinal width was measured at 0.5 mm above the dorsalmost portion of each condyle. Table 1.—ANOVA regression of trunk length on fourth spine width. Sum of Mean Source df. squares square F Spine width 1 42,426.8363 42,426.8363 1576.807 Residual 130 9,562.0936 73.5546 Total 131 51,988.9299 y = 47.600 + 9.881 x S*b 0.169 % variation = 81.607 r = 0.903 "Sig: at P’='0:05: Spinal sections from 193 specimens were read once. Initial results indicated that about 64 of the sections were clearly legible. These readings ranged from age groups 0 through VII (Table 2). Age group III was most numerous. Narrow translucent (dark) and wider opaque (white) zones can be easily distinguished in a spinal section from one specimen (Fig. 7). The radius of the first circulus is greater than each successive radius. The central portion of all spines is vascular, and in large specimens this area often obscures the first and second circuli. Consequently, determination of the placement of these first circuli will depend upon careful examination of their positions in younger specimens. Several additional methods have been tried to facilitate readings. A ‘‘burning technique’’ used by Christensen (1964) to emphasize annular marks on otoliths of the North Sea sole, Solea solea, was not effective on sailfish spinal sections. Staining with various concentrations of methylene blue was likewise ineffective. A magnified image produced by projection with a Bausch and Lomb overhead pro- jector was not sufficiently clear to enumerate all Table 2.—Age readings of Atlantic sailfish using best sec- tions from fourth dorsal fin spines. No. circuli 0 I Ty LIT IV WAI WAL WALL Frequency 3 4 15 21 12 5 2 2 N = 64/193 Figure 7.—Section from the fourth dorsal fin spine of a fe- male in at least age group VI, wt=19.958kg, Dec. #10 - 1970. circuli. Several spinal sections have been decalcified and stained with varying degrees of success. Some progress is now being made using these techniques. Results thus far available from this study express the need for growth equations based upon accurate methods of aging. Females were found to be consis- tently larger than males (Table 3 and Fig. 8), and the sex ratio changed appreciably during the season; 65% of the sailfish examined from December through May were females (Fig. 9). Nakamura and Rivas (1972) also noted that female sailfish from the Gulf of Mexico sport fishery were typically larger and more numerous than males. Considerable variation in sailfish weight at a given Table 3.—Weight and trunk length of Atlantic sailfish examined May 1970 through September 1971. Mean Weight Trunk Number individuals weight range length range (kg) (kg) (cm) Total = 412 17: Os 025-3955 Males 182 14.9 2.3-27.4 70.0-144.0 Females 230 18.7 0.5-39.5. 42.5-151.5 Total >18.1 kg = 177 Males 50 20.6 Females 127 23.6 — Male N= 182 o-=-0 Female N=: 230 Percent Frequency Welght (kg) Figure 8.—Percent frequency distribution of 412 male and female sailfish by weight. 72 —— Male N=177 69 oe--0 Female N=221 A 66 \ 1 63 H o 1 jay (60 4 E 1 oO 57 p o 1 = 54 1 ° C) 51 Seessil: 5 45 o ‘S 42 a 39 36 33 30 Hoo) FeoMSAG NE Wired A 1971 AYS=O}ZN ADS 1970 Months Figure 9.—Sex ratio of 398 sailfish expressed as a percent of each monthly sample. age has been observed by de Sylva (1957) and Wil- liams (1970), but no specific correlations have yet been made with regard to sex. Perhaps a difference in growth rate would account for the size disparity between sexes. A significant difference was observed between the length-weight relationships by sex (¢t.05=3.121, df. 410). Females smaller than 137 cm trunk length were notably heavier than males of comparable length (Fig. 10). Merrett (1968:165) found no sexual distinc- tion in the length-weight relationship of 120 Indian Ocean sailfish 126-194 cm ‘‘eye to fork length’’ (11.3 to 47.6 kg). Many of the fish he examined were considerably larger than those I weighed and mea- sured (see Table 3). However, Williams (1970) ac- knowledged that a sexual difference in the length- weight relationship may exist, as is the case in mar- lins. Reproduction Gonadal tissues have not yet been fully evaluated microscopically. However, in assessing reproduc- tive development from slides of Indian Ocean bill- fish gonadal tissue, Merrett (1970) reported that ovu- lation was probably not an all-or-none process, and that many resting oocytes were ‘‘reabsorbed.”’ Simi- larly, Moe (1969) found that not all developing oo- cytes reached maturity in red grouper, Epinephelus morio. Many ‘‘rejuvenilized’’ during a resting stage subsequent to the spawning period. Beaumariage (in 86 LOG, TRUNK LENGTH 1.8 1.9 2.0 24 SLOG, , WT =3.342 LOG, TkL-5.784 (w=182) Q LOG, , WT = 2.950 LOG, ,TkL-4.941 ( N-230) LOG, ,WEIGHT WEIGHT (kg) SO wr= 1.645 x10 TK? PB wr= 1.145 x 105 TKL?95° TRUNK LENGTH (cm) Figure 10.—Relationship of trunk length to weight for 412 Atlantic sailfish. press) noticed a similar condition in young king mac- kerel, Scomberomorus cavalla. Such developmental characteristics will be considered when sailfish slides are examined. Fecundity was estimated for eight sailfish varying in size from 17.2 to 27.4 kg (38.0 to 62.5 lb) (Table 4). Counts of “‘ripe’’ oocytes yielded fecundity esti- mates varying from 0.8 to 1.6 million ova. These oocytes constituted fewer than half the total number in the ovary. Voss (1953) estimated total fecundity of sailfish to be 2.3 to 4.7 million ova, probably an exceedingly high number of “‘ripe’’ oocytes. His counts were made from an ovary only 4.2% of specimen weight (Voss, 1953:227). Although he gave no size range for oocytes counted, I suspect they were not fully developed. I counted only the largest ova, 1.2 to 1.4 mm in diameter, from ovaries 8.1 to 12.7% (x = 9.9%) of specimen weight. Correlation of gonadal tissue evaluations, larval sailfish abundance, and age estimates will allow def- inition of spawning frequency and age at maturity. Table 4.—Results of fecundity studies for eight Atlantic sailfish ranging from 17.2 to 27.4 kg (38.0-62.5 Ib). Total Ovary Body Ova/gram Est. Specimen wt! wt! wt! wt fecundity (kg) (kg) (%) VL-14 18.1 2.3 12.7 467 819,412 VIS 17.2 2.0 11.6 555 750,000 Not recorded 28.4 ca 2.4 8.5 457 = 1,075,321 VIL 28.1 ca 2.6 9.3 498 1,148,918 VIL-14 19.1 2.0 10.5 890 —:1,557,574 IX-8 28.4 ca 2.3 8.1 616 1,297,850 VIlI-3° 23.1 1.9 8.2 580 919,300 VL-I7’ 22.2 2.3 10.4 462 891,270 1Fresh weights recorded during field examination. Initial observations from plankton collections con- firm that sailfish spawn throughout summer. Larval and juvenile istiophorids 3 to 105 mm total length were collected during April through October. ‘‘Ripe’’ females were also prominent among adults sampled during May through September (Fig. 11). Spawning appears to be intense in mid-May through September. Two peaks were apparent during the spawning seasons (Fig. 11). A preliminary micro- scopic examination of gonadal tissue from ‘‘ripe”’ specimens and variation in the ovaries’ percent of total body weight and number of ova per gram weight of ovary suggest multiple spawning. ACKNOWLEDGMENTS Special appreciation is expressed to John Rybovich, Jr., who helped organize and establish a field laboratory in West Palm Beach. Mr. Rybovich has been a constant source of help and enthusiasm during the entire project. Frances Doucet and staff of the West Palm Beach Fishing Club provided pro- fessional and secretarial services. The Phipps Foundation and Don J. S. Merten (Tournament of Champions winner, 1972) have provided financial assistance through cooperation with Game Fish Re- search Association, Inc. of West Palm Beach. Ap- preciation is extended to all anglers, sport fishing captains, and other local interests who directly or indirectly contributed to the project’s success but who are too numerous to mention by name. I am indebted to Al Pflueger, Jr. and James D. Smith of Pflueger Taxidermy for providing fresh specimens. Walter C. Jaap provided photographs of spines and spinal sections and Henry Kamiya 87 60 fF o 55 ¢ N=227 oe 3 50 | E ie 45 uw 40 |- o Qa iz 35 5 30 | a 25 c ® 20 + — o 15)7|; a 10 |- 5 fF thee: 4 Hoh 4 4 x : Je Mis ifelrAp Sian Oe NEIDICe) Res rom MinrAaiMnee lh s}iaerA 1970 1971 Months Figure 11.—‘‘Ripe”’ sailfish expressed as a percentage of total females examined monthly. drafted figures. Robert M. Ingle, Edwin A. Joyce, Jr., Robert W. Topp, Charles R. Futch, and espe- cially Dale S. Beaumariage provided guidance and editorial review. LITERATURE CITED BAGENAL, T. B., and E. BRAUM. 1968. Eggs and early life history. In W. E. Ricker (editor), Methods for assessment of fish production in fresh waters, p. 159-181. Blackwell Sci. Publ., Oxford. BEAUMARIAGE, D. S. In press. Age, growth and reproduction of king mackerel, Scomberomorus cavalla, in Florida. Fla. Mar. Res. Publ. CHRISTENSEN, J. M. 1964. Burning of otoliths, a technique for age determination of soles and other fish. J. Cons. 29:73-81. DE SYLVA, D. P. 1957. Studies on the age and growth of the Atlantic sailfish, Istiophorus americanus (Cuvier), using length-frequency curves. Bull. Mar. Sci. Gulf Caribb. 7:1-20. 1969. Trends in marine sport fisheries research. Trans. Am. Fish. Soc. 98:151-169. ELLIS, R. W. 1957. Catches of fish by charter boats on Florida’s east coast. Univ. Miami Mar. Lab., Spec. Serv. Bull. 14, 6 p. KOTO, T., and K. KODAMA. 1962. Some considerations on the growth of marlins, using size-frequencies in commercial catches. I. Attempts to estimate the growth of sailfish. [In Jap., Engl. summ.] Rep. Nankai Reg. Fish. Res. Lab. 15:97-108. McCLANE, A. J. 1965. McClane’s standard fishing encyclopedia. Holt, Rinehart and Winston, Inc., N. Y., 295 p. MERRETT,N. R. 1968. Weight-length relationships for certain scombroid fishes from the equatorial western Indian Ocean. East Afr. Agric. For. J. 34:165-169. 1970. Gonad development in billfish (Istiophoridae) from the Indian Ocean. J. Zool. 160:355-370. MOE, M. A., JR. 1969. Biology of the red grouper, Epinephelus morio (Valenciennes) from the eastern Gulf of Mexico. Fla. Dep. Nat. Resour. Mar. Res. Lab., Prof. Pap. Ser. 10, 91 p. NAKAMURA, E. L. 1971. An analysis of the catches and biology of big game fishes caught by the New Orleans Big Game Fishing Club, 1966-1970. East Gulf Sport Fish. Mar. Lab. Rep., 38 p. NAKAMURA, E. L., and L. R. RIVAS. 1972. Big game fishing in the northeastern Gulf of Mexico during 1971. Natl. Mar. Fish. Serv., 20 p. (mimeo). OTSU, T., and R. N. UCHIDA. 1959. Sexual maturity and spawning of albacore in the Pacific Ocean. U.S. Fish Wildl. Serv., Fish. Bull. 59:287-305. PARRISH, B. B. 1958. Some notes on methods used in fishery research. /n Some problems for biological fishery survey and tech- niques for their solution, p. 151-178. A symposium held at 88 Biarritz, France, March 1-10, 1956. Int. Comm. North- west Atl. Fish., Spec. Publ. 1. RIVAS, L. R. 1956. Definitions and methods of measuring and counting in the billfishes (Istiophoridae, Xiphidae). Bull. Mar. Sci. Gulf Caribb. 6:18-27. VOSS, G. L. 1953. A contribution to the life history and biology of the sailfish, /stiophorus americanus Cuv. and Val., in Florida waters. Bull. Mar. Sci. Gulf Caribb. 3:206-240. 1956. Solving life secrets of the sailfish. Natl. Geogr. Mag. 109:859-872. WATSON, J. E. 1967. Age and growth of fishes. Am. Biol. Teach. 29:435-438. WILLIAMS, F. 1970. The sport fishery for sailfish at Malindi, Kenya, 1958-1968, with some biological notes. Bull. Mar. Sci. 20:830-852. WISE, J. P., and C. W. DAVIS. 1973. Seasonal distribution of tunas and billfishes in the At- lantic. U.S. Dep. Commer., NOAA, NMFS Tech. Rep. SSRF-662, 24 p. Some Biological Observations of Billfishes Taken in the Eastern Pacific Ocean, 1967-1970 MAXWELL B. ELDRIDGE and PAUL G. WARES’ ABSTRACT From 1967 through 1970 sport-caught billfishes were sampled at Mazatlan, Sinaloa; and Buena Vista, Baja California, and at San Diego, California. Lengths, weights, morphometrics, meristics, and gonad data were gathered on a total of 2,056 striped marlin, 821 sailfish, 61 blue marlin, and 1 black marlin. This paper presents information on reproduction, average length and condition factor, food habits for 1970, and notes on parasites. Developing gonads were found only in the Mexican fish. Our data on reproduction indicated that both striped marlin and sailfish spawn once per year with peak spawning activity probably in June and July. There is also the possibility that sailfish spawn in other months. First maturity in striped marlin and sailfish occurred in the 155-165 cm eye-fork length class. Fecundity estimates ranged from 2 to 5 million eggs for four sailfish and from 11 to 29 million eggs for three striped marlin. It appears tnat striped marlin move offshore from the Mexican coastline to spawn while sailfish remain closer to shore. Much of the interest in billfishes in the eastern Pacific Ocean stems from their popularity among sport fishermen. Commercial fishermen have also been interested in the billfish resources as indicated by their extensive and continuous operation in this area since 1956 (Suda and Schaefer, 1965). Since 1963 this fishery has concentrated off Mexico where it is directed primarily at striped marlin (Tetrapturus audax) and sailfish (Istiophorus platypterus) (Kume and Schaefer, 1966; Kume and Joseph, 1969a). Throughout the history of the billfish fishery in the eastern Pacific no attempt has been made to manage these resources; this is partly due to the lack of information on the life history and population dynamics of these fishes. This report provides data gathered from billfishes landed at sportfishing sites in southern California and Mexico from 1967 to 1970. Specimens were examined at San Diego, California; Buena Vista, Baja California; and Mazatlan, Sinaloa, Mexico (Fig. 1). A total of 2,056 striped marlin, 821 sailfish, 61 blue marlin (Vakaira nigricans) and 1 black marlin (M. indica) were sampled. This paper is one of a series of publi- cations describing the results of these studies. Evans XNOAA, National Marine Fisheries Service, Tiburon Fisheries Laboratory, Tiburon CA 94920. 89 and Wares (1972) published information of the food habits of fish collected in 1967-1969, and another paper (Wares and Sakagawa, 1973) has been pre- pared to present meristic and morphometric analyses. The purpose of this paper is primarily to present 120° SAM DIEGO tral 30} 126 ne 100" Figure 1.—Location of the three billfish sampling sites. data relating to sexual maturation and to make infer- ences on the reproductive biology of striped marlin and sailfish. The numbers of blue and black marlin were insufficient to add significantly to the knowl- edge of these species. We also present notes on food habits as observed from data collected in 1970, sea- sonal abundance, and parasites. Because of the long established fishery for bill- fishes in the western and central Pacific, most bill- fish reproduction information has been derived from that area (Nakamura, 1932, 1940, 1949; Ueyanagi, 1959; Yabe, 1953; Honma and Kamimura, 1958). Merrett (1970, 1971) and Williams (1963, 1964, and 1970) reported on the Indian Ocean billfishes and concluded they are closely related to those in the western Pacific. We have encountered only two major publications (Kume and Joseph, 1969b; Yurov and Gonzales, 1972) dealing with reproduction of billfishes east of long. 130°W. SEASONALITY All four of the species studied occur regularly at Mazatlan and Buena Vista where they exhibit sea- sonal cycles of abundance. San Diego is near the northern extreme of istiophorid ranges on the east- ern Pacific coast and except possibly in the warmest years, striped marlin is the only species captured there. The occurrence of striped marlin is highly seasonal. Based on records kept by several resorts (1963-69) in the Palmas Bay area of Baja California (the area surrounding Buena Vista) and at Mazatlan (1967-69), sailfish and striped marlin show distinct patterns of seasonal abundance. Though these data are probably not highly accurate, the trends (Fig. 2 and 3) agree with our personal observations and with data provided by the Departamento de Tourismo, Terr. Baja California Sur. Seasonalities for blue and black marlin are not presented because of the low numbers in the catch records and because of persistent confusion in the identification of the two species. It appeared, however, that blue marlin were most abundant from late summer through winter, at least in the Palmas Bay area. Peak abundance of both striped marlin and sailfish tended to occur later in the year at Palmas Bay than Mazatlan. At each location, the time of maximum abundance of sailfish occurred later than that of striped marlin. The seasonal occurrence of striped marlin is much more restricted at San Diego than in Mexico with no fish being caught before July 1 or 90 PALMAS BAY ----- MAZATLAN C/E T E(%) i} T Figure 2.—Catch per unit effort (number per boat-day) and percent effort for sailfish sport fishery from Palmas Bay (1963-1969) and Mazatlan (1967-1969). 2 T T T T T T T T = T STRIPED MARLIN 4 —— PALMAS Bar --—-- MAZATLAN Figure 3.—Catch per unit effort (number per boat-day) and percent effort for striped marlin sport fishery from Palmas Bay (1963-1969) and Mazatlan (1967-1969). after December 1. Records of striped marlin landed at three sportfishing clubs in San Diego from 1963 to 1970 show the peak catch to vary between late Au- gust and early October. The timing of the apparent abundance of striped marlin off San Diego is be- lieved to be correlated with surface water tempera- tures (Squire, 1974a). REPRODUCTION Collection and Processing of Samples Gonad weights and fish length and weight were measured and sex noted of each fish examined. Dur- ing 1969 and 1970 core samples of ovaries were also taken. Also in 1970, Japanese longliners provided us with gonads and detailed information of six addi- tional mature striped marlin caught near the Revil- lagigedo Islands (lat. 19°N, long. 111°W). Field sampling of specimens involved examina- tion of fishes during the same day in which they were caught. Each fish was weighed and measured (eye- fork length). The body cavity was then opened and the gonads excised. Adhering fascia were removed and the gonads weighed. In 1970 the length and volume of each gonad was measured. During 1969 and 1970 ovarian tissue was sampled with a cork borer following a method used by Yuen (1955) wherein two transverse borings through the ovary are made at approximately '% the distance from each end. These two samples from each fish were pre- served in Gilson’s fluid (Simpson, 1951), which ren- dered the ova much easier to measure and handle. This treatment appears to have no obvious differen- tial effect on the ova diameters or shape (Schaefer and Orange, 1956). The samples were kept in Gilson’s fluid from 2 to 18 mo during which time the ova became separated from the ovarian tissue. Each sample was then gently stirred and a random sample of ova was mea- sured with an ocular micrometer at 30 magnifica- tion. Ova diameter measurements were taken on whatever axis fell parallel to the micrometer gradua- tions. Several authors (Clark, 1925, 1934; June, 1953; Otsu and Uchida, 1959; and Yuen, 1955) have concluded that random measurements regardless of the axis produced reliable results. Because differential maturation of ova was found in bigeye tuna (Yuen, 1955) we took integrated sam- ples with the cork borer. Later examination of ma- ture striped marlin and sailfish ovaries, however, showed no evidence of either cross-sectional or lon- gitudinal variation in ova size within ovaries. We tested for cross-sectional variation by taking radial subsamples from a 10 mm thick transverse section near the middle of one of the largest, most mature striped marlin ovaries. The ova diameter frequency distributions (Fig. 4) of three samples radiating from the center were similar. Likewise, anterior, middle, and posterior subsamples from two striped marlin and one sailfish ovaries showed no evidence of lon- gitudinal variation (Fig. 5). The 95th centile egg diameter was determined from the size frequency distribution of 300 eggs measured at random as described by Schaefer and Orange (1956). ‘‘Maximum ova diameter’’ as used by us was the largest size class interval (0.066 mm 91 100, ——— = ——————————————————— ae 1 § NUMBER OF OVA a= a OVA DIAMETER (mm) on 0.3 Figure 4.—Ova diameter frequency polygons of subsam- ples taken near the middle of a mature striped marlin ovary; a—central, b—intermediate, c—peripheral. Ant n=306 a a~308 Post n=303 Mia 1-304 Post 2-303 Paes OVA OIAMETER (mm) Figure 5.—Ova diameter frequency polygons from one mature sailfish and two striped marlin. Samples were taken from the anterior, middle, and posterior areas of the left ovary. increments) containing ova from a sample of 50 ova measured at random. Description of Gonads Detailed description of the gonads and spawning products of billfishes were published by Merrett (1970) and La Monte (1958). In our studies we found strong evidence of gonadal assymetry (Table 1). For striped marlin, the left gonad averaged larger than Table 1.—Percent frequency of specimens in which the left gonad was larger in weight than the right; left gonad expressed as average percentage of combined gonad weight and length. Left gonad as percent of Freq. combined L>R (%) Weight Length WN Striped Marlin Male 80 S321 535i 40 Female 95 60.5 54.5 44 Sailfish Male 73 48.5 53.3 11 Female 79 55.5 52.9 24 the right in both sexes. The left ovary of sailfish also averaged larger but the left testis averaged smaller in weight. Females exhibited the greatest gonadal asymmetry and the difference in size between right and left ovaries was often obvious without meas- urement. Williams (1963) observed similar differ- ences in Indian Ocean striped marlin with the left gonad always larger in both length and displacement volume. Several noteworthy gonadal abnormalities were also seen. In ten striped marlin, five sailfish, and one blue marlin, one ovary was lacking; in two striped marlin and one sailfish one testis was lacking. This phenomenon can result from the fusion of the two gonad primordia during development, or simply from the failure of one gonad to develop (Hoar and Randall, 1969). In one striped marlin the ovary had proliferated into many different sized lobes filling much of the coelomic cavity (Fig. 6). It was filled with large eggs which were visibly misshapen. Another striped marlin was noted to have a testis which had divided into separate anterior and pos- terior lobes. Four ovaries were tumorous, brown- red in color, consisting of dense, odiferous tissue. Penellid copepods were found encysted in the gonads of three striped marlin and one sailfish. Measures of Sexual Maturity The general problem of finding an accurate and efficient means of measuring sexual maturity in fishes has resulted in the development of many tech- niques. Testes have not been found to be suitable because of problems encountered in measuring ac- curately their sex products (June, 1953). In addition, Merrett (1970) has shown by histological examina- tion that unlike the case in most teleosts, there is differential maturation of spermatozoa in the testicu- lar lobules of billfishes. There is thus only a small Figure 6.—Illustration of an abnormal striped marlin ovary with different sized lobes throughout the coelomic cavity. 92 overall seasonal increase in size of the testes, and some milt is usually present throughout the year. On the other hand, the ovary as an indicator of maturity has been well documented (Clark, 1925, 1929, 1934; Hickling and Rutenberg, 1936). As oogenesis proceeds, characteristic changes occur which can be easily detected macroscopically or microscopically. We therefore chose to use ovarian characteristics to represent maturity of billfishes in this study. The most precise method of determining the stage of ovarian maturity is to histologically examine the tissues as performed by Merrett (1970) or Moser (1967). This procedure, however, is lengthy and time-consuming. Another reliable technique is to measure a large number of ova from the same ovary, a method used for many species (Clark, 1929, 1934; June, 1953; and Brock, 1954). This method is based on the assumption that as the spawning season pro- gresses, the group or groups of maturing ova will be distinguished as advancing modes in size-frequency distributions. This method is also time-consuming and laborious, but has a definite advantage in charac- terizing the frequency of spawning when a fully ma- ture specimen is examined. When many fish are examined over a time interval, the progression of the modes of developing ova may provide information on the rate of maturation, time of spawning, and size at maturity. Two variations of this process which require the measurement of fewer ova are the use of ““maximum ova diameter’ (Otsu and Uchida, 1959) and the position of the 95th centile (Schaefer and Orange, 1956). The latter is particularly useful when the exact position of the developing mode is difficult to distinguish, as in early maturation stages. Indirect methods to measure sexual maturity in- volve the relationship between some measure of the fish’s size (either length or weight) and gonad weight. The use of fish length assumes that fish weight is nearly proportional to the cube of the length, a true situation with regard to the billfishes in this study as determined by length-weight analyses for eastern Pacific billfish. It is also assumed that fecundity is proportional to size. Kume and Joseph (1969b) have plotted ovary weight versus eye-fork length and also utilized the gonad index (G/) computed as GI = (W/L?) - 10* where W = total weight of gonads in grams, and L = eye-fork length in cm. Table 2.—Regression of maximum ova diameter and 95th centile of ova diameter on gonad index (n = sample size, r = coefficient of correlation, b = slope, a = y axis inter- cept.) Striped Marlin 95th centile on GI 31 0.936* 3.02 1.46 Max. ova diameter on GI 269 0.797* 3.78 1.48 Sailfish 95th centile on GI 21 0.913* 3.91 2.47 Max. ova diameter on GI 184 0.859* 4.78 3.43 *Significant at 0.01 level. Merrett (1971) used another type of gonad matura- tion index which related the macroscopic appear- ance (color, yolk presence, egg diameter, and gen- eral appearance) of the gonad to recognizable stages in its histology. To evaluate these different measures of maturity and to determine the degree of correlation between them, we applied regression analyses to our data (Table 2). As can be seen, the gonad index ts highly correlated. In each of the four regressions, the corre- lation coefficients exceeded the 0.01 significance levels when tested against a Student’s ¢-distribution. The lower r values for regression of maximum ova diameter on gonad index can be explained by the fact that maximum egg diameters do not always repre- sent the size of the advanced mode. For example, the presence of a few residual eggs in an ovary which is in the resting or early maturation stages will not reflect the true stage of development of the ovary. We have included both direct and indirect methods to analyze the spawning of striped marlin and sailfish. But, based on the above comparison and considering the time and manpower costs and the degree of accuracy desired, we conclude that the gonad index represents the most practical indicator of the stage of sexual maturity for a study of this type. Size at First Spawning The reported size at which striped marlin attain sexual maturity varies little among previous studies. Merrett (1971) reported first maturity at 140-160 cm eye-fork length. This agrees with the conclusion of Williams (1963). Kume and Joseph (1969b) stated that individuals greater than 160 cm from the eastern Pacific regularly occur in the spawning group (3.0 G1), however, they did collect a mature specimen in the 148-cm class. - Our criteria for evidence of sexual maturity were based on a minimum egg diameter and a minimum gonad index. Fish with maximum ova diameters equal to or greater than 0.3 mm were considered mature based on the work of Merrett (1970) who considered eggs of this size as maturing, having completed yolk and chorion formation. We some- what conservatively chose GJ = 1.0 as the other criterion based on our data (Fig. 7 and 8) which show Li QUARTER 1 ah Eh Lp Lina aa aL LRU ae LS ef 2.00+ mw ow a w muy oe Ha aw om @ INDEX eo < 3 oO o ul 3.00;- 4 | | ) 2.00} 4 ; ' | Looh a 4 | t t t + eet fe] oof 4 v | | 200+ | | 0h 2) | Jk ol 1 Je en Oo or ee ee ee 10 120- 130- 40- 150- i60- 170- 680 90- 200- 210- iS 123 3s “5 35 165 7S 1s 9! 205 as LENGTH GROUPS (cm) Figure 7.—Striped marlin gonad indices versus eye-fork length groups presented in quarters of the year. Numbers of striped marlin sampled are given in parentheses. that no gonad index exceeded 1.0 in Quarter I and, further, the gonad indices for immature fish below 145-150 cm in Quarter II were remarkably consistent and did not exceed 0.3.-The increase in average gonad index with increasing fish lengths between 150 and 190 cm in Quarter II suggests that larger fish either mature earlier or have larger gonad index val- ues at given maturity stages than smaller fish. The presence of higher gonad indices for large fish in Quarter I than those of small fish in both Quarters I 94 and II suggests that the latter is the case. Based on these criteria first maturity of striped marlin oc- curred in the 155-165 cm length classes and in the 160-165 cm length classes of sailfish (Fig. 7, 8,9, 10). Frequency of Spawning Simultaneous presence of both mature, non- atretic ova in the lumen and developing ova in the Ua ow w Toma lecenl naan! anc Gee oan aa ee ec ee oo @ 0 Loof- Y : QUARTER : 5 SO +. a.0o} 5 a i oie ———_ + — GONAD- INDEX a z ————— wor Vv LENGTH GROUPS (cm) Figure 8.—Sailfish gonad indices versus eye-fork length groups presented in quarters of the year. Numbers of sailfish sampled are given in parentheses. follicles is possible evidence of multiple spawning. However, lack of these conditions does not neces- sarily rule out multiple spawning. We plotted ova diameter frequency polygons of 300 ova from speci- mens with the highest gonad indices in each 2-wk period throughout 1969 and 1970. In addition, larger numbers of eggs were measured for one striped mar- lin and two sailfish, which had high gonad indices (Fig. 11). We found no indication of multiple spawn- ing. OVA DIAMETER (mm) 120 BO 40 180 190 200 50 [=] 7 LENGTH GROUPS (cm) Figure 9.—Striped marlin ova diameters versus eye-fork length groups presented in quarters of the year. Numbers of striped marlin sampled are given in parentheses. Fecundity Little information is available on the fecundity of striped marlin or sailfish. Nakamura (1949) conser- vatively stated for billfishes in general that fecundity ranges from 1.0 to 1.2 million eggs depending on size and species. Merrett (1971) estimated a fecundity of 12 million eggs for an Indian Ocean striped marlin of 182 cm eye-fork length, with an ovary weight of 1.53 kg and a mean maximum egg diameter of 0.470 mm. In the central Pacific, Gosline and Brock (1960) estimated 13.8 million eggs for one striped marlin Ovary. We estimated the fecundities of four fully mature sailfish and three striped marlin by subsampling by weight. All specimens had high gonad indices and the striped marlin were specimens with the largest Figure 11.—Size frequency polygons for two mature sail- fish (righthand curves) and one mature striped marlin. oat QUARTER | | DIAMETER (mm) OVA QUARTER IV {20 Bo 50 160 170 LENGTH GROUPS (cm) Figure 10.—Sailfish ova diameters versus eye-fork length groups presented in quarters of the year. Numbers of sailfish sampled are given in parentheses. NUMBER OF OVA | § | ee Se ee ey een eee Oe. 9305 1.0 fg 1.1.2 3 eA. LOL SLO LOM. 1 ct ay eh elec) pee OVA DIAMETER (mm) 95 ovaries encountered in this study. The fecundity estimates (Table 3) ranged from 11.3 to 28.6 million Table 3.—Fecundity and related information on sailfish and striped marlin from the eastern North Pacific collected in 1969 and 1970. Fecundity Maximum Estimate Gonad Eye-Fork Ovary Ova Diam. (million Index Length (cm) Weight (gm) (mm) eggs) Sailfish 3.7 185 2359 12 1.8 5.5 163 2359 0.9 2.4 7.0 176 3810 1.3 8.9 187 5760 13 5.1 Striped Marlin 4.42 180 2580 0.6 11.3 8.17 150 2760 0.6 172 9.53 155 3550 0.6 28.6 eggs for striped marlin and from 1.8 to 5.1 million eggs for sailfish. Spawning Season and Locality We are aware of only two publications that deal with spawning seasons of striped marlin and sailfish in the eastern Pacific (Kume and Joseph, 1969b and Yurov and Gonzales, 1972). Kume and Joseph GOWAD INDEX e atl — yp d n n — C “ = ° x0 \ az Waal au 7 - z —~ SS = = \ La ol 4 n = 4 JAN FEB MAR APR may JUN JUL AUG SEP oct NOV DEC Figure 12.—Mean gonad index distribution and the number of striped marlin sampled by month from Buena Vista and Mazatlan. (1969b) found that the highest frequency of striped marlin in spawning condition occurred in Quarter IV in the southern hemisphere and in Quarter II in the northern. Some were also in spawning condition in Quarter III in the northern hemisphere. These au- thors concluded that two spawning seasons existed at opposite times of the year in the northern and southern latitudes. This spawning pattern was also noticed in the western Pacific (Ueyanagi, 1959; Honma and Kamimura, 1958) and in the Indian Ocean (Williams, 1963: Merrett, 1971). Our data (Fig. 12 and 13) show a gradual increase =, Sa ee a ee STRIPED MARLIN 1.0-—- = & ce wi e L w = = i=) <= > ° 0.5-- L : m0 ° : -* ° go co ° 5, NO SiPrew eg = nr Se Om bere dd Be ORD KE om Le meen <4 pw we: o eee ° =n i Latest JAN FEB MAR APR MAY JUN —- SEP OcT NOV DEC Figure 13.—Maximum ova diameter and 95th centile distributions by month from striped marlin ovaries sampled by Buena Vista and Mazatlan. in maturation through June and July, at which time our sampling stopped. Several factors suggest that striped marlin move away from our sampling area at this time. Migration patterns indicated by Kume and Joseph (1969a) and Squire (1974b) showed that striped marlin move west-southwesterly from the coastal areas as the year progresses. Also, the data from the sport fishery (Fig. 2) show concentrations of striped marlin decreasing after March at Mazatlan and after July at Buena Vista. During July, Japanese longline fishermen have noted fully mature striped marlin in increased concentrations around the Revil- lagigedo Islands (G. Adachi, pers. comm.). The fish appeared in pairs and when one was hooked the other would remain alongside until the fish was hauled aboard. This behavior was not noticed in other areas of the eastern North Pacific or during other times of the year. Ovaries provided to us by the longliners from that area were all ripe and ranged in gonad index from 4.42 to 9.53 and the ova diameters were all in excess of 1.25 mm. Sex ratio for striped marlin showed a slight but not significant predominance of males at Mazatlan from late February to July. In the larger and seasonally later catches at Buena Vista, males tended towards 60% from April through early June. The ratio then remained close to 50% into August. The October- early November ratios were also near 50%. Off San Diego, male striped marlin averaged only about 30% up to late September but rose to almost 50% for the rest of the season. From these data it is logical to suggest that striped marlin migrate away from the coastal areas near the Gulf of California to spawn during July and possibly August. Females sampled at San Diego in August were in a post spawning condition and all had gonad indices less than 1.0. Available evidence suggests that sailfish spawn nearshore in the eastern North Pacific with a north- ward progression of spawning activity during the year. Kume and Joseph (1969b) noted that some sailfish from Costa Rica coastal waters were in spawning condition from February to March. At the same time sailfish from offshore waters from lat. 0° to 15° were immature. Yurov and Gonzales (1972) reported spawning in the Gulf of Tehuantepec ex- tending from February to April. We measured 36 larval and juvenile sailfish collected by Scripps In- stitution of Oceanography and the National Marine Fisheries Service along the Central American coast. Estimated spawning dates for these specimens based on back calculations using the growth rates of de Sif, Sylva (1957) indicated spawning of Costa Rican specimens from December through March, Guatemalan specimens mostly from January through April (with two in August), and Mexican specimens from April through November. Our data conform to this pattern. Sailfish began to mature in late May and reached spawning condition in June and July (Fig. 14 and 15). The average gonad index showed a rapid decline in July, but this may be an artifact of a sharply reduced sample size. The ova remained large. From April through July the sex ratio of Mazatlan sailfish remained close to 50%. Slightly more females than males were found until early June, after which time the ratio tended towards males. The smaller numbers of sailfish caught in Palmas Bay were predominantly female with males never ex- ceeding 50%. PARASITES Among the incidental observations of parasites perhaps the most significant was the discovery of Philichthys xiphiae Steenstrup in the opercular bone in several striped marlin at Buena Vista and Mazatlan. Previously this species had been reported from the mucous canals of swordfish (Xiphias gladius) but not from any of the istiophorids and not from the eastern Pacific. The parasites were embed- ded in the preopercle just beneath the skin. The differences between parasitized and normal bones are readily seen in the x-ray photos in Figure 16. Other possible infection sites (bones) were not checked for this parasite nor were other billfish species. 200}— 7 vu ] ae 4N | 5 8b 8 ~\ 2 == eal Go NUMBER OF FISH oct NOY DEC Figure 14.—Mean gonad index distribution and the number of sailfish sampled by month from Buena Vista and Mazatlan. ar a cl FL cL Una ias aeI = pr 6 = + MAXIMUM egs5th CENTILE SAILFISH 3 tee ° E E - | w - w =z < a $ r ° 0.5/- 1 : ° CEA ° : J iF tes 2 Bid Jae . on “a0 tre: . -- C - comm: Oftine - og: ot as os oD te wee =fike go ° ou 1 = 1 1 1 1 1 = 1 Ih 1 JAN FEB MAR APR MAY JUN JUL AUG SEP oct NOV DEC Figure 15.—Distribution of sailfish maximum ova diameters and 95th centiles by month from Buena Vista and Mazatlan. Figure 16.—X-ray photos of preopercular bones of striped marlin from Buena Vista showing (A) cavities caused by Philichthys xiphiae (B) a non-parasitized bone. Caligoid copepods (some identified as Pandarus sp.) were common on the body surface and often very numerous, particularly in the ventral region just anterior to the anal fin. Large concentrations of these parasites appeared to irritate the skin, causing redness. White capsalid trematodes were commonly seen on the body surface. A different species of capsalid was found commonly in the nasal cavities. Isopods (some identified as Nercila sp.) were quite common on the body surface (usually on the fins) of sailfish at Mazatlan. Up to 57 isopods were recov- ered from a single sailfish. Nematodes were present, often numerous, in most of the billfish stomachs examined. FOOD HABITS Evans and Wares (1972) presented the data for 1967-1969. The contents of additional stomachs ex- amined in 1970 (Table 4) are analyzed below. Table 5 presents the new data as percent occurrence and percent of total food volume. Table 6 compares the top ranked food items based on volume from the two studies. Except at San Diego, where the sampling dates were similar (August-October) in both studies, the comparison is between seasons as well as be- tween years. The 1970 sampling in Mexico was from October through December whereas most of the earlier data was gathered from April through July. The major departures from the results found in the ACKNOWLEDGMENTS previous study were the low importance of an- chovies in San Diego striped marlin and of squid in We are indebted to representatives of resorts and Buena Vista sailfish stomachs. Table 4.—Sample sizes and condition of billfish stomachs | sampled during 1970. Striped Marlin Blue Marlin Sailfish clubs who permitted us to examine specimens of billfishes: Col. Eugene Walters, proprietor of Ran- cho Buena Vista; Bill Heimpel, proprietor of the Star Fleet at Mazatlan; Lois Ibey, Secretary of the San Diego Marlin Club. We are grateful to Lic. Ricardo Garcia Soto, Director of the Departamento de Tourismo de Baja California Sur for making available the reported catch data of sportfishing re- SD BV Maz BV BV sorts in Baja California. We are also grateful to the managers of the following Baja California resorts for effort data: Bahia de Palmas, Rancho Buena Vista, No. Stomachs Hotel Palmilla, Hotel Cabo San Lucas and Total 3759 8 15 33 Hacienda Cabo San Lucas. Several fleets at With Food 20 37—C 4 8 22 Mazatlan kept records of catch and effort for us and Suey 1G to Sichior, 2 2 special thanks are due Bill Heimpel for his efforts. Regurgitated 1 17 3 5 9 Total Vol. of Food (0) 735 825 0.97 1.86 6.83 Other members of our staff who helped us collect and analyze the data were: Larry Coe, Dan Eilers, Table 5.—Food species of billfishes observed in 1970 (% Occurrence/% Volume). Blue Blue Striped Marlin Marlin Sailfish Striped Marlin Marlin Sailfish SD BV Maz BV BV SD BV Maz BV BV ALGAE 7.5/0.5 — — — — _ INVERTEBRATES Carangidae Crustacea Caranx caballus — 3.0/0.8 — — 2.0/0.6 Decapods — 3.0/0.2 — — — Decapterus hypodus — 3.0/1.7 — — 2.0/4.4 Cephalopoda Hemicaranx sp. — 5.0/1.0 — _— — Argonauta sp. — — 50/6.2 — — Trachurus Squid 5.0/0.4 62/24 25/1.2 13/1.1 12/3.1 symmetricus 38/62 — _— _— — _ FISHES Unidentified sp. — 3.0/1.2 — — 8.2/1.0 Elasmobranchs 2.5/T — — _— — Coryphaenidae — — — — 2.0/10 Clupeidae Scorpidae Etrumeus teres — 43/39 — — 18/24 Medialuna Sardinops sagax 5.0/3.1 — _ a= — californiensis 5.0/2.4 — — — — Opisthonema sp. — —- — — 2.0/0.3 Chaetodontidae = — W122 — a Engraulidae Mugilidae Engraulis mordax 2.5/2.2 — _ — — Mugil cephalus — — 25/99 — — Myctophidae — 3.0/0.7 — — 2.0/0.5 Sphyraenidae Scomberesocidae Sphyraena sp. — 3.0/2.3 — — — Cololabis saira 7.5/23.8 — — — — Scombridae Atherinidae Auxis thazard — 3.0/0.4 — 37/36 6.1/13 Atherinopsis Euthynnus lineatus — S.AW/17 — 12/19 8.2/13 californiensis 2.5/16 — _— — — Sarda chiliensis 2.5/0.8 — — — _- Exocoetidae Scomber sp. — 3.0/2.1 — — 4.1/2.3 Cypselurus Unidentified sp. — _— — 25/39 — californicus 2.5/0.2 — — — — Balistidae Unidentified sp. _— _ — 13/0.4 — Balistes sp. — 3.0/0.1 — — 6.1/0.4 Fistularidae Tetraodontidae Fistularia sp. a — — — 8.2/21 Sphoeroides sp. — 3.0/2.2 — — _ Syngnathidae — — 25/04 — — Lagocephalus Echeneidae lagocephalus — 19/64 — — 10/4.0 Remora brachyptera — — — 12/1.6 — Unidentified Fish 20/3.9 8/1.4 50/1.4 38/2.2 6.1/1.4 99 Table 6.—Comparison of major billfish foods in 1970 with those for 1967-1969 (n = no. of stomachs with food). STRIPED MARLIN 1967-1969 1970 Rank Species %Vol. % Vol. Species San Diego n= 116 n= 20 1. Engraulis Trachurus mordax 60 62 = symmetricus 2. Trachurus Atherinopsis symmetricus 27 16 californiensis 3. Cololabis Cololabis saira 5 8 saira Buena Vista n = 303 n = 37- 1. Squid 49 39 Etrumeus teres 2. Etrumeus teres 30 24 Squid 3. Scomber Euthynnus japonicus 7 17 ~~ lineatus 4. 6 Lagocephalus lagocephalus Mazatlan n= 14 n=4 1. Squid 63 79 Mugil cephalus 2. Argonauta sp. 7 12 Chaetodon sp. 3. Balistes sp. 7 6 Argonauta sp. 4. Fistularia sp. 5 SAILFISH Buena Vista n= 14 n=22 1. Squid 35. 24 Etrumeus teres 2. Etrumeus teres 29 21 Fistularia sp. 3. Fistularia sp. 22. 14 Euthynnus lineatus 4. Naucrates 7 13 Auxis ductor thazard BLUE MARLIN Buena Vista No Data n=8 1. 39 Scombrids (unidentified) 2. 36 Auxis thazard 3 19 Euthynnus lineatus Douglas Evans, Stewart Luttich, Howard Ness, and David Tolhurst. Roger Cressey identified Phil- ichthys xiphii and Ernest Iversen identified the parasites Pandarus sp. and Nercila sp. LITERATURE CITED BROCK, V.E. 1954. Some aspects of the biology of the aku, Katswwonus pelamis, in the Hawaiian Islands. Pac. Sci. 8:94-104. CLARK, F.N. 1925. The life history of Leuresthes tenuis, an atherine fish with tide controlled spawning habits. Calif. Dep. Fish Game, Fish Bull. 10, 51 p. 1929. The life history of the California jack smelt, A therinop- 100 sis californienis. Calif. Dep. Fish. Game, Fish Bull. 16, 23 p. 1934. Maturity of the California sardine, (Sardina caerulea), determined by ova diameter measurements. Calif. Dep. Fish Game, Fish Bull. 42, 52 p. DE SYLVA, D.P. 1957. Studies on the age and growth of the Atlantic sailfish, Istiophorus americanus (Cuvier), using length-frequency curves. Bull. Mar. Sci. Gulf Caribb. 7:1-20. EVANS, D.H., and P.G. WARES. 1972. Food habits of striped marlin and sailfish off Mexico and southern California. U.S. Fish Wildl. Serv., Res. Rep. 76:1-10. GOSLINE, W.A., and V.E. BROCK. 1960. Handbook of Hawaiian fishes. Univ. Hawaii Press, Honolulu, Hawaii, 372 p. HICKLING, C.F., and E. RUTENBERG. 1936. The ovary as an indicator of the spawning period in fishes. J. Mar. Biol. Assoc. U.K., N.S. 21:311-317. HOAR, W.S., and D.J. RANDALL. 1969. Fish physiology. Vol. III. Reproduction and growth, bioluminescence, pigments, and poisons. Academic Press, N.Y., 485 p. HONMA, M., and T. KAMIMURA. 1958. A population study on the so-called Makajiki (striped marlin) of both Northern and Southern Hemispheres of the Pacific. II. Fishing conditions in the Southern Hemis- phere. [In Jap., Engl. summ.] Rep. NankaiReg. Fish. Res. Lab. 8:12-21. JUNE, F.C. 1953. Spawning of yellowfin tuna in Hawaiian waters. U.S. Fish Wildl. Serv., Fish. Bull. 54:47-64. KUME, S., and J. JOSEPH. 1969a. The Japanese longline fishery for tunas and billfishes in the eastern Pacific Ocean east of 130°W, 1964-1966 [In Span. and Engl.] Bull. Inter-Am. Trop. Tuna Comm. 13:277-418. 1969b. Size composition and sexual maturity of billfish caught by the Japanese longline fishery in the Pacific Ocean east of 130°W. [In Engl.] Bull. Far Seas Fish. Res. Lab. (Shimizu) 2:115-162. KUME, S., and M.B. SCHAEFER. 1966. Studies on the Japanese long-line fishery for tuna and marlin in the eastern tropical Pacific Ocean during 1963. [In Span. and Engl.) Bull. Inter-Am. Trop. Tuna Comm. 11:103-170. LA MONTE, F.R. 1958. Notes on the alimentary, excretory, and reproductive organs of Atlantic Makaira. Bull. Am. Mus. Nat. Hist. 114(5):396-401. MERRETT, N.R. 1970. Gonad development in billfish (Istiophoridae) from the Indian Ocean. J. Zool. 160:355-370. 1971. Aspects of the biology of billfish (Istiophoridae) from the equatorial western Indian Ocean. J. Zool. 163:351-395. MOSER, H.G. 1967. Seasonal histological changes in the gonads of Sebas- todes paucispinis. Ayres. an Ovoviviparous teleost (Fam- ily Scorpaenidae). J. Morphol. 123:329-353. NAKAMURA, H. 1932. The ripe eggs of the sailfish, Jstiophorus orientalis, (Temminck and Schlegel). [In Jap.] Zool. Mag. 44:244-245. 1940. On the spawning habits of sailfish. [In Jap.] Zool. Mag. 52:296-297. 1949. The tunas and their fisheries. Takeuchi Shobo, Tokyo, 118 p. (Translated from Jap. by W.G. Van Campen, 1952) U.S. Fish Wildl. Serv.. Spec. Sci. Rep. Fish. 82:115 p. OTSU, T., and R.N. UCHIDA. 1959. Sexual maturity and spawning of albacore in the Pacific Ocean. U.S. Fish Wildl. Serv., Fish Bull. 59:287-305S. SCHAEFER, M.B., and C.J. ORANGE. 1956. Studies on the sexual development and spawning of yellowfin tuna (Neothunnus macropterus) and skipjack (Katsuwonus pelamis) in three areas of the eastern Pacitic Ocean, by examination of gonads. [In Span. and Engl.] Bull. Inter-Am. Trop. Tuna Comm. 1:281-349. SIMPSON, A.C. 1951. Fecundity of the plaice. G.B. Minist. Agric. Fish., Fish. Invest., Ser. 2, 17(5):1-27. SQUIRE, J.L., JR. 1974a. Catch distribution and related sea surface temperature for striped marlin (Tetrapturus audax) caught off San Diego, California. Jn Richard S. Shomura and Francis Williams (editors), Proceedings of the International Bill- fish Symposium, Kailua-Kona, Hawaii, 9-12 August 1972, Part 2. Review and Contributed Papers. U.S. Dep. Comm., NOAA Tech. Rep. NMFS SSRF-675, p. 188-193. 1974b. Migration patterns of Istiophoridae in the Pacific Ocean as determined by cooperative tagging programs. Jn Richard S. Shomura and Francis Williams (editors), Pro- ceedings of the International Billfish Symposium, Kailua-Kona, Hawaii, 9-12 August 1972, Part 2. Review and Contributed Papers. U.S. Dep. Comm., NOAA Tech. Rep. NMFS SSRF-675, p. 226-237. SUDA, A., and M.B. SCHAEFER. 1965. General review of the Japanese tuna long-line fishery in 101 the eastern tropical Pacific Ocean 1956-1962. [In Span. and Engl.] Bull. Inter-Am. Trop. Tuna Comm. 9:307-462. UEYANAGEL, S. 1959. Larvae of the striped marlin, Makaira mitsukurii, (Jordon et Snyder). [In Jap., Engl. summ.] Rep. Nankai Fish. Res. Lab. 11:130-146. WARES, P.G., and G.T. SAKAGAWA. 1974. Some morphometrics of eastern Pacific billfishes. /n Richard S. Shomura and Francis Williams (editors), Pro- ceedings of the International Billfish Symposium, Kailua-Kona, Hawaii, 8-12 August 1972, Part 2. Review and Contributed Papers. U.S. Dep. Comm., NOAA Tech. Rep. NMFS SSRF-675, p. 107-120. WILLIAMS, F. 1963. Longline fishing for tuna off the coast of East Africa 1958-1960. Indian J. Fish., Sect. A, 10:233-390. 1964. The scombroid fishes of East Africa. Jn Symposium on scombroid fishes. Part I, p. 107-164. Mar. Biol. Assoc. India, Mandapam Camp, S. India. 1970. The sport fishery for sailfish at Malinda, Kenya, 1958-1968, with some biological notes. Bull. Mar. Sci. 20:830-852. YABE, H. 1953. Juveniles collected from south seas by Tenyo Maru at her second tuna research voyage. (Preliminary report). [In Jap.] Contrib. Nankai Fish. Res. Lab. 1(25):1-14. YUEN, H.S.H. 1955. Maturity and fecundity of bigeye tuna in the Pacific. U.S. Fish. Wildl. Serv., Spec. Sci. Rep. Fish. 150, 30 p. YUROV, V.G., and J.C. GONZALES. 1971. Possibility of developing a sailfish fishery in the eastern Pacific Ocean. In Sovetsko-Kubinskie Rybokhoziaist- vennye Issledovaniya. [In Russ., Span. summ.] Vol. 3, p. 104-110. Pishchevaya Promyshlennost, Moscow. Scientific Billfish Investigation: Present and Future Australia, New Zealand, Africa’ CHARLES O. MATHER? ABSTRACT I. Scientists, anglers, skippers, and mates investigate and apply the scientific method. The importance of knowledge, organization, and skills required of the scientist, angler, skipper, and mate in order to bring about a better understanding of the billfish and better methods of catching billfish is discussed. II. The need for more observations and recording of data. The following data should be given important consideration: temperature, depth, time, winds, currents, strike-catch ratio, bait, and the ship’s log; these topics are reviewed. III. Scientific research projects for consideration in the future. Potential research projects in Australia, New Zealand, and Africa are presented. Some projects worthy of consideration include: (1) breeding of black marlin at the Great Barrier Reef, Australia; (2) transplanting of small black marlin to a natural salt water lake for study and observation of growth and development (Australia); (3) migration studies by tracking (Australia, New Zealand, Africa); (4) general blood cell surveys (New Zealand); (5) general chromosome surveys (New Zealand); and (6) sensory and motor responses of billfish in relation to sight, smell, and pain (Africa). 1 This paper was presented orally, but only title and abstract were submitted for publication. ? Los Angeles City College, Los Angeles, CA 90029. 102 Biology of Swordfish, Xiphias gladius L., in the Northwest Atlantic Ocean JAMES S. BECKETT?! ABSTRACT The present knowledge of the biology of swordfish in the northwest Atlantic ocean is summarized. Distribution of swordfish is bounded by 13°C surface isotherms with smaller (under 160 cm) fish in water above 18°C. Males are smaller (under 200 cm) than females and are more frequent in warmer, southern areas. Large fish make feeding excursions to the bottom, to depths of 500 m or more and temperatures 5-10°C. Females attain sizes of 550 kg and males 120 kg, but average size was 54 kg in 1970 commercial landings. Growth is thought to be rapid with weights of 4, 15, 40, 70, and 110 kg attained at annual intervals. Spawning is confined to warmer (over 24°C) southern waters. Tagging data (13 recoveries) suggest fish spend the summer in one locality and return there in subsequent years. High recoveries (18.3%) have been made of fish tagged while swimming free. The biology and distribution of swordfish has been investigated by the staff of the Fisheries Research Board of Canada’s Biological Station at St. An- drews, N. B. since 1958. This report summarizes the information obtained during this period from a large number of research cruises, from extensive shore sampling of the commercial catch, and from the available literature. DISTRIBUTION The geographical distribution of swordfish, Xiphias gladius L., in the northwest Atlantic Ocean varies considerably due to the marked seasonal vari- ation in environmental conditions. In winter, the species is confined to the waters associated with the Gulf Stream (Fig. 1), where the surface tempera- ture exceeds 18°C. However, in summer, as the edge of the Gulf Stream moves north and the temperature of the surface waters over the continental shelf in- creases, the fish are found over a much wider area. The summer range extends along the edge of the continental shelf from Cape Cod to the Grand Banks, with fish moving over the shelf in the western part, and, near the mouth of the Gulf of St. Law- rence, along the Cape Breton shore. Occasionally fish are found in the Gulf of St. Lawrence as far * Fisheries Research Board of Canada, St. Andrews, New Brunswick, Canada. 103 north as the Miramichi River, while the most north- erly record on the west coast of Newfoundland ap- pears to be Bonne Bay (Wulff, 1943). The summer distribution is generally limited by the 13°C isotherm, with few fish encountered below 15°C. Distribution by size shows that there is a size differential in that larger fish are found in cooler water, with few fish under 90 kg round weight seen in water of less than 18°C. Sex ratios also differ with temperature, as few males are found in the colder (under 18°C) water. In warmer water, males comprise some 25-30% of the catch. This difference in sex ratios may be partially explained by the smaller size of males since few Newfoundland Canada Passomagoddy Grand Banks Baonquerequ Soble 1s. Bt Browns Bk U.S.A. f fe Figure 1.—Canadian commercial swordfish fishing areas. Cod Georges Bank am Hydrographer sire Canyon = = gulf =i exceed 200 cm fork length (about 120 kg), and are, therefore, less likely to be found in cold water. How- ever, the males may tend to remain in even warmer water as they predominate (67-100%) in catches farther south, particularly in the Caribbean and ad- jacent regions. The variation in distribution by size in the north- ern regions is apparently due to differences in feed- ing habits coupled with temperature tolerances. Swordfish over deep water feed largely on surface animals (flying fish, etc.), local near-surface school- ing species (herring, mackerel, etc.), mid-water, but usually vertically migrating species (lanternfish, barracudinas, etc.), and upon squids. In shallower water, large swordfish, whilst also taking near- surface species, make feeding excursions to the bot- tom where the temperature may be as low as 5-10°C, and feed upon redfish, hake, butterfish, and other benthic species. These fish then apparently return to the upper mixed layer while digesting their meal, presumably to obtain a higher body temperature, since there is no evidence of homoiothermy, or ele- vated values, in this species. It is at this time that fish may be seen near the surface on calm sunny days, conditions that result in water temperatures that are higher right at the surface. Swordfish harpooned at the surface either have full stomachs or empty ones. These latter are completely empty without even the normal complement of nematodes or fish and squid hard parts, a fact suggesting voiding of the contents while the fish struggled against the harpoon line. Swordfish have been observed from submersibles, at depths of 500 m or more, and even to have been apparently resting at, or near, the bottom. It is im- possible to determine whether these fish were on temporary excursions into these depths and low temperatures, or whether they regularly remain in this environment. SPAWNING The reproductive cycle of swordfish in the north- west Atlantic appears to involve spawning to the south, in the Caribbean and adjacent areas, where the temperature exceeds 24°C. The vast majority of gonads from fish captured north of lat. 35°N (Cape Hatteras) have been in the quiescent stage, with ova diameters less than 0.18 mm. Maturing ova may exceed 1.0 mm. Occasional fish have been reported with ripening ovaries (Fish, 1926; FRB unpublished) but these are rare, numbering one or two a year, at most. Similarly some milt has been noted in a few 104 males, but this is not necessarily a sign of imminent spawning. Fish (1926) estimated that a mature female contained 16 million eggs, while another specimen was calculated to contain 5 million. SIZE The largest swordfish, the size of which can be verified, was a fish of 915 lb. dressed weight (ap- proximately 550 kg live weight) landed in Cape Bre- ton. The average weight taken by the commercial fishery, however, was much less than this, being close to 120 kg (round) for harpooned fish, and in 1970, as low as 54 kg for all fishing methods. The average size had fallen considerably since the intro- duction of longlining in 1962 (Tibbo and Sreedha- ran, 1974). The size distribution of commercial land- ings during 1970 (Fig. 2) shows a peak frequency in - Commercial Swordfish Landings 1970 (N=14089) 1963 ‘, (N=7732) Frequency Percent ani 100 200 300 Dressed Weight ( Pounds) Figure 2.—Size distribution of swordfish landed in Canada in 1970. (Dressed weight to live weight conversion factor 1.326.) the 41-50 lb (18.6-22.8 kg) dressed weight class. This is equivalent (x 1.326) to 55-66 Ib (24.9-30.0 kg) round weight. SIZE/WEIGHT AND GROWTH Analysis of the relationship between fork length (cm) and live weight (lb) ratio by the least squares method, indicates slope coefficients of 2.6-3.1 for different samples at different seasons, with correla- tion coefficients higher than 0.9 The rate of growth has been investigated in a number of ways but no firm figures are available. There are no scales in adults, the otoliths are minute, and, while the bony parts (vertebrae, operculae, fin rays) show rings, these do not appear to be consis- tently interpretable. Estimates from modal size fre- quencies, vertebral rings, and tagging data suggest a rapid growth rate with weights of 4, 15, 40, 70, and 110 kg after successive years for females. There are insufficient data to determine whether the smaller size obtained by males, relative to females, is due to a slower growth rate, or to a considerably shorter life span. The average size of 31 males for which detailed morphometric data were available was 147.2 cm and that of 134 females was 176.9 cm (fork length). TAGGING High recoveries (11 tags, 18.3%) have been made of the 60 swordfish marked by modified harpoon (Beckett, 1968). These fish were tagged while swimming free at the surface. In contrast, of the 146 fish taken on longline and then released, only 2 (1.4%) have been recaptured. Migrations and Stock Identification The spawning data, as judged from the occurrence of larvae, indicate considerable migration of sword- fish between the northern feeding areas and southern reproductive zones (Markle, 1974). However, the separate nature of the actual areas where larvae have been found (Virgin Islands, Windward Islands, Windward Passage, Northwest Caribbean, Florida Straits, and Western Gulf of Mexico) suggests the possibility of some stock separation between these areas. In the north, the tagging data (Table 1) for the 13 fish recaptured suggests that swordfish return to the same part of the summer feeding area in subsequent years. No tagged fish have changed the general local- ity either within, or between years, the maximum displacement being 179 miles and the recovery posi- tion for that fish is suspect. Furthermore, mor- phometric data suggests some heterogeneity be- tween the fish on Georges Bank (Fig. 1) and those on the Grand Banks, during the summer. Additional studies that were being undertaken on this matter, particularly tagging, have been frustrated by the mercury-inspired cessation of commercial long- lining. ACKNOWLEDG MENTS Many people have worked in the Large Pelagic Fish programme, and I particularly acknowledge S. N. Tibbo, Programme Head, and my many compan- ions On sea cruises. LITERATURE CITED BECKER INS: 1968. A harpoon adapter for tagging large free-swimming fish at the surface. J. Fish. Res. Board Can. 25:177-179. FISH, M. P. 1926. Swordfish eggs. Bull. N. Y. Zool. Soc. 29:206-207. MARKLE, G. E. 1974. Distribution of larval swordfish in the northwest Atlan- tic Ocean. Jn Richard S. Shomura and Francis Williams Table 1.—Swordfish tag returns. Min. Size Released Size Recovery Size Months distance change date Area (Ib) Date (Ib) out miles (Ib) 9/9/1964 Georges 90 est. 12/ 7/1966 Georges 188 est. 21 60 + 98 7/6/1966 Gulf Stream70 est. 10/ 7/1969 Georges 156 37 128 + 86 3/7/1968 Georges 160 est. 3/ 9/1970 Stellwagon 212 26 178 ap oe 27/7/1968 Sable 400 est. 11/11/1969 Sable 400+ 16 7 0 27/7/1968 Sable 350 est. 2/10/1969 Sable 590 15 6 +240 29/7/1968 Browns 160 est. 4/10/1968 Browns 150 est. 3 28 sh) 13/7/1970 Georges 120est. 20/ 9/1970 Georges 140 est. 2 59 + 20 13/7/1970 Georges 140est. 14/ 9/1970 Georges Wa 0 5 na 13/7/1970 Georges 170est. 19/ 7/1970 Georges 172 0 38 SB 22 13/7/1970 Georges 150est. 11/ 9/1970 Georges 185 2 83 + 35 13/7/1970 Georges 100 est. 13/10/1970 Georges 75 est. 3 92 = i755) 13/7/1970 Georges 180est. 27/ 7/1970 Georges 228 0 31 + 48 4/8/1968 Georges 225 est. 30/ 8/1970 Georges 234 24 30 + 9 (editors), Proceedings of the international Billfish Symosium, Kailua-Kona, Hawaii, 9-12 August 1972, Part 2. Review and Contributed Papers. U.S. Dep. Comm. U.S. Dep. Comm. NOAA Tech. Rep. NMFS NOAA Tech. Rep. NMFS SSRF-675, p. 252-260. SSRF-675, p. 296. TIBBO, S. N., and A. SREEDHARAN. WULFF, L. 1974. The Canadian swordfish fishery. Jn Richard S. Sho- mura and Francis Williams (editors), Proceedings of the International Billfish Symposium, Kailua-Kona, Hawaii, 9-12 August 1972, Part 2. Review and Contributed Papers. 1943. Marine fishing in Newfoundland. Int. Game Fish Assoc. Yearb. 1943:65-66. 106 Some Morphometrics of Billfishes From the Eastern Pacific Ocean PAUL G. WARES! and GARY T. SAKAGAWA? | ABSTRACT Length-weight and morphometric data collected over 4 yr (1967-70) from sport fisheries at three eastern Pacific locations are presented for striped marlin (Tetrapturus audax), sailfish (Istiophorus platypterus), and blue marlin (Makaira nigricans). The data were gathered from San Diego, California (U.S.A.), Buena Vista, Baja California Sur (Mexico), and Mazatlan, Sinaloa (Mexico). Regression of eye-fork length and covariance analysis were used to compare maximum body depth, depth at vent, pectoral fin length, dorsal fin height, maxillary length, snout to mandible and snout to posterior orbit lengths between sexes and areas for each species. Regression equations are given for converting fork length and mandible-fork length to eye-fork length. Based on these conversions our Pacific Ocean data on sailfish are compared with data from the Atlantic Ocean. Length-weight regressions using both eye-fork length and fork length are given for each species by The eastern Pacific off Mexico and southern California is probably one of the world’s most pro- ductive regions for billfishes. Specimens from this region, however, have too often been underrepre- ' sented in comparative studies on billfish morphol- ogy. It is the purpose of this paper to (1) present some basic data on morphometric and meristic characters of striped marlin (Tetrapturus audax), blue marlin (Makaira nigricans), and sailfish (/s- tiophorus platypterus) from the eastern North _ Pacific Ocean, and (2) discuss some sources of varia- tion in morphometric characters. SAMPLING Source of Data The data were gathered by the staff of the Tiburon _ Fisheries Laboratory during 1967 through 1970. The _ sole source of data was the sampling of sport land- ings at three locations. These locations were: (1) the | San Diego Marlin Club at San Diego, California; (2) Rancho Buena Vista in the territory of Baja Califor- ‘U.S. Fish and Wildlife Service, Northwest Fisheries Pro- gram, 495 Tyee Dr., Tumwater, WA 98502. *National Marine Fisheries Service, Southwest Fisheries Center, P.O. Box 271, La Jolla, CA 92037. 107 nia Sur, Mexico; and (3) the Star Fleet at Mazatlan, Sinaloa, Mexico. Sampling at these locations each year was conducted primarily during the months when billfish catches were highest. The monthly distribution of samples is shown in Table 1. The specimens examined were almost totally fish caught on one-day trips in small boats ranging from about 6 to 12 min length. For this reason most of the samples at each location represent fishes caught in a radius of less than about 100 km from the landing site. All of the fish were kept fresh, unfrozen, and at San Diego and Buena Vista, usually moist. The bill- fish landed at Mazatlan tended to be in a more dried-out condition. This made full erection of the dorsal fin difficult. Many fish were, therefore, meas- ured when the dorsal fin was only half erect, but we feel that this did not affect the results significantly. The effect of dryness on body measurements is un- known, but we feel that it was not significant. Body length measurements were made with a steel tape. Nearly all of the fish at San Diego and a few of the fish at Mazatlan were measured while hanging by the tail. Otherwise, measurements were made while fish were lying on their side on a flat surface with heads and tails raised to horizontal. We tested the effect of hanging on eye-fork lengths of 10 fish at San Diego by measuring each one while hanging Table 1.—Number of blue marlin, sailfish, and striped marlin sampled in 1967-70 at Buena Vista, Mazatlan, and San Diego. Months Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Total Blue marlin Buena Vista Female 1967 1 - -—- —|- = -—- = 1 1969 —- —- — = 2 7 —- =—- = 5 = 14 1970 —_- — — 15 > =) 20 Total ee 3 7 = = 5 10. — 35 Mazatlan Female 1969 — = 4 or" 410 2 ee S22 Sailfish Buena Vista Male 1967 ee 2 - - =| | =| S| = 2 1968 —- —- — = 3 3 1969 - -—- — — I 3 —- —- — 5 — 9 1970 - - = =) 6) = 4 Total — — — 2 4 3 —_ — 8 11 — 28 Female 1967 —- —- — 2 4 6 1968 — _ | 3} a, 7 = _— —_ = = 18 1969 —- —- — 10 | 9 —- -—- —- = G AG 1970 7 1. ey | Total —- — l 15 12 16 - —- — i 20 71 Mazatlan Male 1967 —— 4 5 o-—- FS ee a a 9 1968 os — Gi} 44 1S — oe — — _— 2 68 1969 1 1 25 7g 142? 22 —- —- —- — — 264 Total 1 1 36; 1225 Si) 22 —- -—- —- — 2 341 Female 1967 —- — 17 MWoo— Se Se eS ee 28 1968 —- a 14 64 26 — — — — —_— 3 107 1969 4 iq ipl Ol 93 14 — — — — — 236 Total 4 al 435 1/6) 9: 14.5 35 3 Striped marlin Buena Vista Male 1967 —- —- — 53 30 os —- Sr Se SS 83 1968 — = 49) 64 74 3a i = er 1969 — 17 86 113 39° 18 = 78 1970 —- =—- —- — 6 33 1 40 Total — 17 1350 250 43a? —- — 6 33 i 7 Female 1967 —- =—- = 46 9 — —- =—- =—- => — 65 1968 —- = 37, 48 » (60) 25 - —- — — — 170 1969 — 22 51 54 422 29 — — — 9 — 207 1970 Se SOS SS ee SS 6 32 6 44 Total —— 9 22. 88 9148. 121 54 — 6 4] 6 486 108 Table 1.—Number of blue marlin, sailfish, and striped marlin sampled in 1967-70 at Buena Vista, Mazatlan, and San Diego.—Continued Months Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Total Mazatlan Male 1967 —- — 21 q 28 1968 —- — 50 = 26 —- -—- —- —- — 1 78 1969 13 42 30-30 1 121 1970 - -—- —- =— 2 2 Total 13 42 101 63 1 —- =—- => = 39,229 Female 1967 —- = 1S 1] - - -|- =| | = 26 1968 —- = 31 18 4 53 1969 16 48 36) 529) 3 Sy a ee TT 1970 - —- — 6 6 Total 16 48 82 58 3 Ye 10), 226 San Diego Male 1967 a — 22 50. — ee 72 1968 —- —- — = — 1 353 —- = 69 1970 — 6 —- — — 6 Total — 23 Ol es3 — — 147 Female 1967 35 1260 — — — 161 1968 6 85) 932 — — 123 1970 3 26 2 —- = 31 Total —- —- —- = — 44 237 34 — — 315 and then again after lying flat. The fish while hang- ing ranged from 1 mm shorter to 7 mm longer, the average being 3 mm longer than when lying flat. The mean difference was not significant. Definitions of Counts and Measurements The counts and measurements used in this study are defined below. Though the terminology is not identical, many of these are the same as those rec- ommended by Rivas (1956). Dorsal rays—number ofrays in second dorsal fin. Anal rays—number of rays in second anal fin. Fork length—tip of snout to posterior margin of middle caudal rays. Mandible-fork length—tip of mandible with mouth closed to posterior margin of middle caudal rays. Eye-fork length—posterior margin of orbit to posterior margin of middle caudal rays. Snout to mandible—tip of snout to tip of mandi- ble with mouth closed. Table 2.—Frequency of dorsal and anal fin ray counts for blue marlin, sailfish and striped marlin from the eastern Pacific. Number of rays 5 6 7 8) alotall) -X% s Dorsal fin rays Blue marlin — 13 20 _— 33 6.61 0.496 Sailfish — 24 56 — 80 6.70 0.461 Striped marlin 10 223 14 — 247 6.02 0.312 Anal fin rays Blue marlin — 5 27 1 33 6.88 0.415 Sailfish 1 29 «48 1 79 6.62 0.538 Striped marlin 40 195 7 — 242 5.86 0.420 Snout to eye—tip of snout to anterior margin of orbit. Length of maxillary—tip of mandible to posterior end of maxillary bone. Maximum body depth—base of dorsal groove to edge of pelvic groove, in the transverse plane where this measurement is maximum (usually near base of pectorals). Depth at vent—depth of body as described above except in the transverse plane through vent. Length of pectoral fin—from base of first pectoral fin ray to tip of longest ray with fin folded against body. Length of pelvic fin—from base of fin rays to tip when fin is held at slight angle from body. Dorsal fin height—from base of first dorsal fin spine to tip of anterior lobe of first dorsal fin with fin held as nearly erect as possible (see previous sec- tion). METHODS OF ANALYSIS Meristic Characters Counts of second dorsal and second anal fin rays were the only meristic characters used. It was quite evident early in the study that the number of fin rays did not vary significantly with fish size, at least for sizes of fish we examined, and that the number for a species varied within a narrow range of two to four rays (Table 2). The meristic characters were there- fore eliminated from any further analyses. BLUE MARLIN Buena Vista FREQUENCY ere eet ere ee en 150 160 170 180 190 200 210 220 230 240 250 260 155 165 175 185 195 205 215 225 235 245 255 265 EYE-FORK LENGTH (cm) Figure 1.—Length frequency of blue marlin sampled in this study. Morphometric Characters Linear regression and analysis of covariance were the procedures used to analyze the data. Except for Table 3.—Equations for converting fork and mandible-fork lengths to eye-fork length. Equations are based on Y =a + bX. Range of X Relation a b N r (cm) Blue marlin Eye-fork length on fork length —15.785 0.810 21 0.997 221.1-347.3 Eye-fork length on mandible-fork length —5.105 0.893 22 0.979 194.0-297.6 Sailfish Eye-fork length on fork length 6.802 0.714 35 0.926 183.0-260.0 Eye-fork length on mandible-fork length 2.637 0.852 35 0.940 155.5-225.0 Fork length on eye-fork length 24.677 1.200 35 0.926 Striped marlin Eye-fork length on fork length —1.319 0.745 127 0.745 178.5-268.8 Eye-fork length on mandible-fork length 1.306 0.840 125 0.985 151.6-238.2 110 Table 4.—Coefficients of the weight-length relation for blue marlin, sailfish, and striped marlin from the eastern Pacific. (log weight = a + b (log length)). Measurement Range of Species Length (cm) Weight a b length (cm) N ip Blue marlin Female Eye-fork kg —5.690 3.318 154.0-265.1 57 0.948 Eye-fork Ib —5.347 3.318 154.0-265.1 57 0.948 Snout-fork kg =12543 3.905 221.1-347.3 20 0.954 Snout-fork Ib —7.199 3.905 221.1-347.3 20 0.954 Sailfish Male Eye-fork kg —4.396 2.643 115.1-196.5 367 0.867 Eye-fork Ib —4.057 2.643 115.1-196.5 367 0.867 Snout-fork kg —5.286 2.873 183.0-260.2 24 0.910 Snout-fork Ib —4.946 2.873 183.0-260.2 24 0.910 Female Eye-fork kg —4.084 2.507 123.1-221.7 435 0.812 Eye-fork Ib —3.739 2.507 123.1-221.7 435 0.812 Snout-fork kg —4.059 2.356 201.7-271.0 47 0.835 Snout-fork Ib —3.714 2.356 201.7-271.0 47 0.835 Combined sexes Eye-fork kg —4.360 2.628 115.1-221.7 802 0.846 Eye-fork Ib —4.017 2.628 115.1-221.7 802 0.846 Snout-fork kg —4.788 2.662 183.0-271.0 71 0.890 Snout-fork Ib —4.446 2.662 183.0-271.0 71 0.890 Striped marlin Male Eye-fork kg —5.005 2.999 119.6-202.6 975 0.877 Eye-fork Ib —4.664 2.999 119.6-202.6 975 0.877 Snout-fork kg —5.166 2.903 172.0-261.0 220 0.780 Snout-fork Ib —4.857 2.903 172.0-261.0 220 0.780 Female Eye-fork kg —§.243 3.113 110.0-215.1 1,007 0.854 Eye-fork Ib —4.900 3.113 110.0-215.1 1,007 0.854 Snout-fork kg 5.267, 2.950 153.0-271.0 315 0.778 Snout-fork Ib —4.914 2.950 153.0-271.0 6) 5) 0.778 Combined sexes Eye-fork kg —5.157 3.071 110.0-215.1 1,982 0.864 Eye-fork Ib —4.816 3.071 110.0-215.1 1,982 0.864 Snout-fork kg —5.340 2.982 153.0-271.0 535 0.784 Snout-fork Ib —5.007 2.982 153.0-271.0 535 0.784 weight-length relations, transformations of the data were not necessary because plots of the data on eye-fork length indicated that they were reasonably linear. Equations for converting fork length and mandible-fork length are given in Table 3. The equation used in the analyses, except that for weight, was Y = a + bX, where Y = morphometric character measured in centimeters, and a and hb = constants that are determined by least-squares pro- cedures. For weights, the equation log Y = a + blogX, where Y = weight, X = body length, and a and b = constants, was used. Weight-length rela- tions based on weight in kilograms and pounds and body length as eye-fork length and snout-fork 111 length are summarized in Table 4 for blue marlin, sailfish, and striped marlin. Statistical tests were performed to test the hypotheses that the intercept of the regression, a, is zero and that the slope of the regression, b, is zero for all regressions except those for weight-length. All plots of the data were based on averages of 5-cm groupings of eye-fork length. BLUE MARLIN A total of 57 blue marlin was sampled at Buena Vista and Mazatlan. The average length was 206 cm at Buena Vista and 209 cm at Mazatlan (Fig. 1). Table 5.—Regression of morphometric character on eye-fork length (cm) for blue marlin from the eastern Pacific. Weight-length relation is based on log transformed data (log Y = a + blogX); all other relations are based on untransformed data (Y = a + bX). Data are for females. (* = 5% significance level; ** 1% significance level). Range Character a b x Y N Buena Vista Weight (kg) —5.960 3.433 154.0-265.1 40.9-244.9 35 Maximum body depth (cm) —5.887 0.245** 154.0-239.8 32.2- 53.6 14 Length ot pectoral fin (cm) 18.594** 0.163** 154.0-265.1 40.7- 62.0 35 Length of pelvic fin (cm) 37.244** 0.003 154.0-239.8 32.1- 45.3 14 Dorsal fin height (cm) 20.966** 0.084** 154.0-265.1 31.0- 49.4 34 Length of maxillary (cm) 15:2362* 0.090** 154.0-265.1 25.9- 40.2 34 Number of dorsal fin rays 6.468** 0.001 154.0-265.1 6-7 33 Number of anal fin rays 5.286 0.008** 154.0-265.1 6-8 33 Mazatlan Weight (kg) —4.972 3.011 171.4-242.2 46.7-171.5 22 Length of pelvic fin (cm) 57.859** 0.096* 171.4-242.2 30.1- 45.3 22 Dorsal fin height (cm) 7.560 O2150%% 171.4-242.2 32.2- 45.9 22 Length of maxillary (cm) 4.014 0.140** 171.4-242.2 26.5- 40.2 21 SAILFISH ee 60 L FEMALES (e) .~ 90 as N=~434 o| 7 e — Nisree WEIGHT 80 A EL ye a ae ° ° Mazatlan ee E | Brot a 70 a es 1 r AN as N X L aoe MALES (0) » \——M 341 171.2 60 Rta F 3711754 4 eS a aa ea ee ee ee Pe en 50 L = 60 = a — male | al Wane oe al © DORSAL HEIGHT Ss Se ee FEMALES (e) ve | : L aoe N=274 > niall MALES (0) Ww = N=285 > 20 4 = E x 1 L 1 1 1 il 4 1 it 1 1 1 {Lf 1 uw l0 = 100 120 140 160 180 200 220 240 260 = EYE-FORK LENGTH (cm) =F Figure 3.—Weight and dorsal height as a function of eye- Ani z| fork length of sailfish from the eastern North Pacific. Buena Vista Si » le ee oe mee coo : 9 [ Samples from both locations consisted of only waite | females. We have no adequate explanation for this phenomenon; however, we note that in the central st al Pacific, which is west of our sampling area, more ON: males than females are generally caught in the sport Neen pegs peasy = i 100 NO 120 130 140 150 160 170 ; aa 190 200 5 fishery (Strasburg, 1969). In the longline fishery, See 105 5 125 135 145 155 165 175 185 195 205 215 ratios vary greatly both temporally and spatially EYE-FORK LENGTH (cm) (Kume and Joseph, 1969). Figure 2.—Length frequency of sailfish sampled in this Regressions of each of the characters as a func- study. 112 tion of eye-fork length are shown in Table 5. Ex- Table 6.—Results of analysis of covariance of morphometric character as a function of eye-fork length. The statistical test is whether the relation is significantly different among areas. (n.s. = not significant; * = 5% significance level; ** = 1% significance level). Blue marlin Sailfish Striped marlin Character Female Male Female Male Female Weight n.s n.s. n.s nah * Maximum body depth — n.s. sai Fe Depth at vent = n.s. n.s # He Length of pectoral fin — n.s n.s cal i? Length of pelvic fin n.s n.s n.s n.s. + Snout to mandible length — n.s n.s aoe nhs Snout to eye length ats pee * * ok Dorsal fin height n.s n.s * * ok Length of maxillary n.s n.s n.s n.s n.s cluding results for weight-length relations, results of the statistical test of a = 0 indicate that most of the a’s are significantly different from zero. This sug- gests that growth of the body parts is allometric, or the parts do not grow as a constant proportion to body size, which is characteristic for most body parts of fishes (Martin. 1949). Analysis of covariance was performed to test whether the regressions differed between sampling locations. No significant differences were found (Table 6). Samples from Buena Vista and Mazatlan were therefore pooled and the regressions were re- calculated (Table 7). SAILFISH A total of 811 sailfish was sampled at Buena Vista and Mazatlan. Sampling at Buena Vista was in 1967-70 and at Mazatlan, only in 1967-69. More fish, however, were sampled at Mazatlan than at Table 7.—Regression of morphometric character on eye-fork length (cm) for pooled (loca- tions and sexes) samples of blue marlin and sailfish from the eastern Pacific. Weight-length relation is based on log transformed data (log Y = a + blog X); all other relations are based on untransformed data (Y =a + bX). Character a b Range of length N Blue marlin Weight (kg) —5.690 3.318 154.0-265.1 57 Maximum body depth (cm) —5.887 0.245 154.0-239.8 14 Length of pectoral fin (cm) 18.594 0.163 154.0-265.1 35 Length of pelvic fin (cm) 49.263 —0.056 154.0-242.2 36 Dorsal fin height (cm) 17.129 0.103 154.0-265.1 56 Length of maxillary (cm) 12.366 0.103 154.0-265.1 55 Sailfish Weight (kg) —4.360 2.628 115.1-221.7 802 Maximum body depth (cm) 2.824 0.150 121.5-221.7 239 Depth at vent (cm) 10.160 0.073 121.5-221.7 239 Length of pectoral fin (cm) 0.703 0.211 121.5-221.7 279 Length of pelvic fin (cm) 12.171 0.274 115.1-203.0 $29 Snout to mandible length (cm) 16.382 0.099 133.2-203.0 196 Snout to eye length (cm) 24.707 0.207 156.0-203.0 34 Dorsal fin height (cm) 8.292 0.202 115.1-203.0 559 Length of maxillary (cm) 9.910 0.110 115.1-203.0 553 II Ls py l6l-l cr r10'0 Op cl L-9 9181-7 6b sl0'0 £80°P SAvi uly [BUR JO JaquINN I L-9 v'16l-I Chl 610°0 SLV€ al L-9 9181-7 6b £00°0 ¥tbTL Swi UY [eSIOp JO JaquINN 977 €Ce-8 OC = 8 S6I-1 ETI ++L60°0 ++961 71 097 V6e-11t Se6l-Istl +9 110 + 9DL'8 (wo) Areypixew Jo yydua] 877 879-167 = 8 S6I-T' eZ +4810 ++596 11 £97 pTS-SST CS COI-ISTI +4#L170 6£S'S (wd) 1ys1ay Uy [es1og (a6 O'IL-0°9S I °L8T-0'9ST *««097'0 ScelLI 8 £'79-S 6b =p P8l-E LOT O81°0 $90°L7 (Wd) ya] aA2 0} JnOUS 601 Tlp-pst =P p6l-7 ee +9900 ** OP 77 t9 TIppv ie 0061-9'SEI +0110 £90'PT (Wd) Yyydus] e[qipukw oO} JnoUg ve? 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(YY + YP = A) PIvP pauoOjsuRAjUN UO paseg aiP SUONLIat 19YyI0 [PR ICY Bo] g + VY = 4 BO}) BBP pawsoOysuPd) BO] UO pase SI UONP[Al YISUI|-]YSI9M “DOV UDISRI IYI WOIY YSIS 1OJ (LUD) YIBUa| y.AOJ-9A9 UO Ad]DPARYD IAJaWOYdIOW JO UOISSATIY—'g I/GPL 114 DEPTH (cm) 40 w oO PECTORAL FIN E g 60 | =I c wu 80 + 4 ae San Diego Soe Nn xX | ; .—M 147 1649 40 + # <=F 315 1702 ee ery ho NET 1 i) 1 it 7" Veet 1 1 100 NO 120 130 140 150 160 170 180 190 200 210 105 15 125 135 «145 «#4155 165 175 185 195 205 215 EYE-FORK LENGTH (cm) Figure 5.—Length frequency of striped marlin sampled in this study. 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YIBUI|-IYSIOAA “YlOVq WISP dy] WOAY UNPAVLU PIdLs OJ (LUD) YITUI] YAOJ-2A9 UO AIIIVAPYI INIUWOYdIOW JO UOISSABIY—"6 9/GP_L 116 BV, females PENSI OF PECTORAL FIN (cm) 100 120 140 160 180 200 220 240 EYE-FORK LENGTH (cm) Figure 6.—Plotted regressions of pectoral fin length on eye-fork length of striped marlin by sex and locality. BV=Buena Vista, M= Mazatlan, SD=San Diego. than was available to them (they had data on nine specimens from the coast of Peru). Body length for the Atlantic specimens was measured as fork length. In order to have the data comparable to our data, it was necessary to convert eye-fork length of our samples to fork length with the appropriate equation in Table 3. Maximum body depth, length of pectoral fin, length of pelvic fin, and dorsal fin height were ex- amined (Fig. 4). Analysis of covariance was not used to test for significant differences in these characters between Atlantic and eastern Pacific sailfish because of the complication of one set of data being based on converted lengths. However, we feel from visual inspection that there is sufficient separation between the regressions (especially the first three) to suggest that eastern Pacific sailfish differ significantly from Atlantic sailfish in mor- phometric measurements. More information based on a wide range of sizes of fish from the Atlantic and Pacific is needed for a more complete compari- sion. STRIPED MARLIN The eastern Pacific is apparently a center of high concentration of striped marlin. Considerable num- bers of fish are annually caught by the commercial longline fleet and by sportsmen. In 1967-70 we sampled 2,020 specimens from the sport landings at Buena Vista, Mazatlan, and San Diego. Length frequencies of the samples are shown in Figure 5. Location and Sex Differences Regressions of each meristic and morphometric character as a function of eye-fork length are shown in Table 9. Analysis of covariance was performed on the data, sexes separate, to determine whether the regressions were significantly different among locations. The results (Table 6) indicated that the regressions were different. Analysis of covariance was also used to determine whether the relations were significantly different between sexes, within location. The results (Table 10) for this series of tests showed either no differences or inconsistency from one location to another, except for the relation of length of pectoral fin on eye-fork length. For this relation, significant differences between sexes were found at all three locations. The regressions are shown in Figure 6. On the basis of these results, except for pectoral fin length, it was assumed that there is no significant difference between sexes, but a significant difference among locations. The data were pooled accordingly and regressions recalcu- lated (Table 11). A plot of weight on eye-fork length for striped marlin from each location (Fig. 7) shows that for a given length, striped marlin from San Diego were heavier than fish from Buena Vista or Mazatlan. Table 10.—Results of covariance analysis of morphomet- ric character of striped marlin as a function of eye-fork length to test whether the relations are significantly dif- ferent between sexes. (n.s. = not significant; * = 5% significance level; ** = 1% significance level). Buena San Character Vista Mazatlan Diego Weight ns. ns. nS. Maximum body depth Ee n.s. a Depth at vent ns. n.s. * Length of pectoral fin ae * os Length of pelvic fin BFS n.s. —_— Snout to mandible length n.s. n.s. ae Snout to eye length n.s. n.s. n.s. Dorsal fin height be n.s. N.S. Length of maxillary n.s. N.S. * A, a BUENA 2 WA VISTA (0) — ne Ys N=1073 Ero SAN DIEGO(*)—»»” .% Fc} N=460 ° w fe Fi E 40 Ay 4 ee MAZATLAN (0) a * N=449 20 as 4 —e | | ! | l =| ! ! | | 100 120 140 160 180 200 220 240 EYE-FORK LENGTH (cm) Figure 7.—Weight as a function of eye-fork length of striped marlin from the eastern North Pacific. 60 Sa a a ad Ly SSL Gel ee | MAXIMUM BODY DEPTH =o SAN DIEGO (x) (aig 4 S | Bane pac Ee, \ | L \ Leer BUENA VISTA (e) 2 Zt] te fo | San ei N=567 | © ok 5 ty 20- 4 Qa | f+ MAZATLAN (0) 4 | N=180 CEES ey me Lp | Py MAH S| ee ve a vee sy Se ie =! = MAZATLAN (0 E gol 2 LENGTH OF 3% \ BREED Se aka x PELVIC FIN =i] = L See = wae 25 i | o | atone . Br BUENA VIST, 7 Ave eae i N=475 |S | Se np pp ty Se ee es et eer aot BUENA VISTA‘ | N=487 = | SAN DIEGO(« 1 a E N=397 pee = 30/- Vee es SNOUT TO - 5 pee eo ° . MANDIBLE LENGTH a ereie. MAZATLAN (0 7 4 Ms N=124 eee eee oes eee 1 1 1 I 1 1 4 1 4 4 4 ho MAZATLAN © DORSAL HEIGHT N=111 o 40 \ pres Pe = = ae pees SAN DIEGO (x 4 \ N=34 BUENA VISTA (e N=562 HEIGHT (cm) eS ESS SES ae Ee ea =a ER] 1 =| 100 120 14 160 180 200 220 240 260 280 EYE-FORK LENGTH (cm) Figure 8.—Morphometric characters as a function of eye-fork length of striped marlin from the eastern North Pacific. 223 343 264 106 1.0 182 121 CONDITION FACTOR o BUENA VISTA e MAZATLAN A SAN DIEGO 9 uw Feb. Mar. Apr. May June July Aug.Sept.Oct. Nov. Dec. MONTH Figure 9.—Average condition factor by month for striped marlin from the eastern North Pacific. One standard de- viation on each side of the mean and the sample size shown. Condition factor=W x 10°/L? where W=whole fish weight in kg and L=eye-fork length in cm. This difference is also evident in the relation of maximum body depth on eye-fork length (Fig. 8); body depth is larger in San Diego fish. It was uncer- tain whether this difference was a seasonal phenomenon since San Diego samples were ob- tained only from August to October, months of the year when there were almost no samples from Buena Vista or Mazatlan (Table 1). Plots of condi- tion factors by month for the three areas (Fig. 9), however, show that seasonal variation is unlikely to be the cause. Some other relations are shown in Figure 8. They indicate that there is much overlap in the data. It thus appears that characters, other than perhaps weight, maximum body depth, and pectoral fin length, are not different enough to be useful as single diagnostic characters for separating striped marlin into location of capture. Comparison with Other Studies Kamimura and Honma (1958) examined five morphometric characters of striped marlin caught in the Pacific by the Japanese longline fleet. They dis- Table 11.—Regression of morphometric character on eye-fork length (cm) for pooled (sexes) samples of striped marlin from the eastern Pacific. Weight-length relation is based on log transformed data (log Y = a + b log X); all other relations are based on untrans- formed data (Y =a + bX). Range of Character a b length N (cm) Buena Vista Weight (kg) —5.356 3.154 119.6-215.1 1073 Maximum body depth (cm) 1.578 0.184 123.1-215.1 567 Depth at vent (cm) —=2'669 0.170 123.1-215.1 533 Length of pectoral fin (cm) —0.333 0.261 123.1-215.1 671 Length of pelvic fin (cm) 38.797 —0.020 119.6-201.4 475 Snout to mandible length (cm) 13.656 0.098 123.1-215.1 487 Snout to eye length (cm) 15.750 0.264 125.0-197.5 145 Dorsal fin height (cm) 9.171 0.178 119.6-201.4 562 Length of maxillary (cm) 5.234 0.169 119.6-201.4 559 Mazatlan Weight (kg) —5.143 3.045 110.0-204.5 449 Maximum body depth (cm) —3.642 0.207 116.8-204.5 180 Depth at vent (cm) —0.038 0.148 118.8-204.5 180 Length of pectoral fin (cm) —3.225 0.274 116.8-204.5 189 Length of pelvic fin (cm) 33.018 0.021 110.0-202.6 254 Snout to mandible length (cm) 14.556 0.088 116.8-197.0 124 Snout to eye length (cm) 19.061 0.236 124.0-204.5 51 Dorsal fin height (cm) 10.526 0.169 118.9-202.6 111 Length of maxillary (cm) 7.840 0.152 118.9-202.6 234 San Diego Weight (kg) —4.439 2.781 127.0-203.3 460 Maximum body depth (cm) 8.400 0.152 129.4-201.5 425 Depth at vent (cm) 2.245 0.152 129.4-201.5 424 Length of pectoral fin (cm) 8.262 0.204 127.0-203.3 461 Snout to mandible length (cm) 14.363 0.097 133.7-201.5 397 Snout to eye length (cm) 21.302 0.238 133.7-192.5 218 Dorsal fin height (cm) 2.534 0.203 127.0-203.3 34 Length of maxillary (cm) 10.017 0.144 127.0-203.3 33 covered that the length of the pectoral fin was sig- nificantly longer in fish caught in the South Pacific (lat. 18°-25°S) than in the North Pacific (lat. 30°-35°N). In Figure 10, we have superimposed Kamimura and Honma’s equations on a band that represents the equations calculated from our data on pectoral fin lengths. The North Pacific sample is most similar to ours, which is from about lat. 20°-35°N. The South Pacific fish, on the other hand, _ have definitely longer pectoral fins than our samples, but only for fish less than about 210 cm long. Data on length of pectoral fin for nine striped marlin (for which eye-fork length was available) re- ported by Royce (1957) from the central and eastern 119 equatorial Pacific are also plotted in Figure 10. The plots indicate that either there is mixing in the cen- tral Pacific of the presumed South and North Pacific stocks of striped marlin or Kamimura and Honma’s samples did not adequately reflect the de- gree of variability in length of pectoral fin of fish from the North and South Pacific. SUMMARY AND CONCLUDING REMARKS Morphometric data for 57 female blue marlin are presented; comparisons with fish from other areas were omitted due to the small sample size. For sail- fish it appears that characters such as maximum SOUTH _-« PACIFIC ° (18°-25°S) CENTRAL PACIFIC(o) a, ,» (cm) 3 PACIFIC LENGTH OF PECTORAL FIN 120 140 160 180 260 200 EYE-FORK LENGTH (cm) 220 240 280 Figure 10.—Comparison of pectoral fin of striped marlin stocks in the Pacific Ocean. The shaded band represents the area in which our data for the relations of eastern Pacific fish fall. Data for South and North Pacific fish are from Kamimura and Honma (1958). Data for central Pacific fish are from Royce (1957). body depth, length of pectoral fin, length of pelvic fin, and dorsal fin height are considerably shorter on the average in fish from the eastern Pacific than in fish of identical size from the Atlantic Ocean. For striped marlin, our results indicated that weight and maximum body depth can be used to separate striped marlin stocks within our study area. For example, a 180 cm long striped marlin landed off San Diego is, on the average, about 19% heavier and has a maximum body depth 3% greater than a striped marlin of identical size landed off Buena Vista or Mazatlan. Also, striped marlin from the northeastern Pacific (lat. 20°-35°N) and South Pacific (lat. 18°-25°S), apparently can be separated on the basis of length of pectoral fin. We conclude, therefore, that there are mor- phometric characters that can be used to separate, 120 with some degree of accuracy, sailfish and striped marlin stocks. We suggest, however, that more powerful techniques, such as multivariate analyses, be used in future attempts of stock identification of eastern Pacific billfishes. ACKNOWLEDGMENT We are grateful for the generous cooperation of the staff and sportsmen at Rancho Buena Vista, the Star Fleet in Mazatlan, and the San Diego Marlin Club for permitting us to measure specimens. Larry Coe, Dan Eilers. Douglas Evans, Maxwell EI- dridge, and David Tolhurst helped collect the data and Brad Cowell assisted with data processing. LITERATURE CITED KAMIMURA, T., and M. HONMA. 1958. A population study of the so-called Makajiki (striped marlin) of both northern and southern hemispheres of the Pacific. 1. Comparison of external characters.[In Jap., Engl. summ.] Rep. Nankai Fish. Res. Lab. 8:1-11. KUME, S., and J. JOSEPH. 1969. Size composition and sexual maturity of billfish caught by the Japanese longline fishery in the Pacific Ocean east of 130°W. Japan. [In Engl.] Bull. Far Seas Fish. Res. Lab. (Shimizu) 2:115-162. MARTIN, W. R. 1949. The mechanics of environmental control of body form in fishes. Univ. Toronto Stud., Biol. Ser. 58, 91 p. MORROW, J. E., and S. J. HARBO. 1969. A revision of the sailfish genus /stiophorus. Copeia 1969:34-44. RIVAS, L. R. 1956. Definitions and methods of measuring and counting in the billfishes (Istiophoridae, Xiphiidae). Bull. Mar. Sci. Gulf Caribb. 6:18-27. ROYCE WE: 1957. Observations on the spearfishes of the central Pacific. U.S. Fish Wildl. Serv., Fish. Bull. 57:497-554. STRASBURG, D. W. 1969. Billfishes of the central Pacific Ocean. U.S. Fish Wildl. Serv., Circ. 311, 11 p. Analysis of Length and Weight Data On Three Species of Billfish From the Western Atlantic Ocean WILLIAM H. LENARZ! and EUGENE L. NAKAMURA? ABSTRACT Estimates of parameters of relations among weight, girth, total length, fork length, body length, trunk length, and caudal spread were made for blue marlin, white marlin, and sailfish captured in the western Atlantic. Some sexual differences were found. Estimates of relations between length and weight of fish are important, because weight is often the desired measure when only length measurements are practical. For example, obtaining accurate weights on vessels at sea is difficult, especially when speci- mens may weigh hundreds of pounds, as is often the case for billfish. Both sport and commercial fisher- men are more interested in weight than in length, for game fish records are listed by weight and commer- cial fishermen are paid by the weight of their catch. Although length measurements of billfish have been taken in numerous ways (Rivas, 1956; Royce, 1957), we chose eye-fork length as the most mean- ingful, because it involves parts of the body that are least apt to be damaged. In this study we estimated relations between eye- fork length and weight for blue marlin (Makaira nigricans), white marlin (Tetrapturus albidus), and sailfish (Istiophorus platypterus) in the western At- lantic Ocean. The relations between girth, eye-fork length, and weight were also estimated, for weight can be more accurately estimated from eye-fork length and girth than from eye-fork length alone. The relations between total length, fork length, body length, caudal spread, and eye-fork length were es- timated so that measurements of the first four types could be converted to eye-fork length for compara- tive purposes. We also examined sexual, spatial, and temporal differences among some of the relations. ‘Southwest Fisheries Center, National Marine Fisheries Ser- vice, NOAA, La Jolla, CA 92037. *Panama City Laboratory, National Marine Fisheries Service, NOAA, Panama City, FL 32401. 121 SOURCES OF DATA AND TYPES OF MEASUREMENTS Most of the data were obtained by personnel of the Panama City Laboratory, Gulf Coastal Fisheries Center, National Marine Fisheries Service, from sportfishermen’s catches in the northeastern Gulf of Mexico during 1971. Weights, lengths, girths, and sex were determined for billfishes landed at Port Eads, Louisiana, and at three ports in northwest Florida: Pensacola, Destin, and Panama City. Data were also obtained from cooperative scien- tists for catches made in various years off the coasts of New Jersey, North Carolina, and Florida, around the Bahama Islands, in the Caribbean Sea, and off Rio de Janeiro. Most measurements were made in English units, a few in metric units. All weights were recorded in pounds. Lengths were recorded in inches or in cen- timeters. Metric measurements were converted to inches for the analyses, since sportsmen and com- mercial fishermen use inches and pounds. Four kinds of length measurements plus the girth and caudal spread were made by personnel of the Panama City Laboratory, except when conditions did not permit (e.g., broken bill or shark bites). Data from the cooperating scientists consisted of one or two kinds of length plus weight. Measurements and their criteria are listed below. Criteria for body length, girth, and caudal spread are the same as those of Rivas (1956). All, except girth, consisted of horizontal, straight-line measurements. (1) Total length: tip of bill to line joining tips of caudal lobes. (2) Fork length: tip of bill to tips of mid-caudal rays. Body length: tip of lower jaw (with jaws closed) to tips of mid-caudal rays. Eye-fork length: posterior margin of eye to tips of mid-caudal rays. Caudal spread: dorsal tip to ventral tip of lobes of caudal fin. Girth: twice the curved distance along one side of the body from the pelvic groove to the dorsal edge of the dorsal groove. (3) (4) (5) (6) METHODS OF ANALYSIS Three equations were used in the study. The rela- tion between logio (weight) and logio (eye-fork length) is given by Y=A+Bi Xi (1) where Y = logio (weight), A = intercept, B: = coefficient, X1 = logio (eye-fork length). The equation can be transformed to the familiar form weight = 4’ (eye-fork length)» where 104 A'= by taking antilogs of both sides of (1). The relation between logio (weight), logio (eye-fork length), and logio (girth) is given by Y =A +BiX1+ B2X2 (2) where Y =logio (weight), A = intercept, B.iand Be = coefficients, X1 = logio (eye-fork length), X2 = logio (girth). The equation can be transformed to weight = 4’ (eye-fork length) Bi (girth) Be by taking the antilogs of both sides. The relations between eye-fork length and other measures of length are given by Y=A +BixX1 (3) where Y =eye-fork length, A = intercept, B. = coefficient, X1 = other measure of length. Equation (1) was not used for the relation between the various measures of length because estimates of B were very close to 1, indicating that linear rela- tions among the variables were appropriate. Equa- tion (3) was used instead. The parameters of (1), (2), and (3) were estimated by use of linear regressions. Analysis of covariance was used to examine sexual differences. Mul- tivariate analysis was used to determine if white marlin could be sexed or allocated to either Florida or Louisiana given measures of length and weight. RESULTS AND DISCUSSION Estimates of the parameters of (1), (2), and (3) are shown in Table 1. All estimates of the parameters are significantly different from 0 at the 0.01 level of significance. Analyses of covariance revealed no significant differences between sexes in the relations between weight and eye-fork length, between eye-fork length and the three other measures of length, and between eye-fork length and caudal spread for blue marlin. However, sexual differences were found in the relations between weight and eye-fork length and between eye-fork length and caudal spread for white marlin (Fig. 1 and 2). Female white marlin tend to weigh more at a given length than male white marlin, but this difference tends to disappear at larger sizes. Further examination of the data in- dicates that the difference is partially the result of females tending to have deeper bodies than males. Male white marlin tend to have a wider caudal spread than females and the difference tends to in- crease with size. A sexual difference in caudal spread was also found for sailfish (Fig. 3), but the difference decreases with increased size. Sexual differences were not found in the length-weight re- lation for sailfish. Deviations from the length-weight relation of the Table 1.—Estimates of parameters of equations (1), (2), and (3). Sample Standard Range of X1 Species Y! X11 X12 A Bi Bo size error (inches) Min- Max- imum imum Blue marlin W LL4 — _ -3.84620 3.28222 — 78 0.0566 50.8 103.5 Blue marlinW LL4 G -3.15120 1.80496 1.27853 78 0.0390 50.8 103.5 Blue marlin L4 Ll — 1.68522 0.66670 — 80 1.9740 73.0 149.0 Blue marlin L4 L2 — 3.07821 0.72374 — 80 1.6853 64.0 134.0 Blue marlin L4 L3 — ~ -0.74597 0.88352 — 83 2.1451 58.0 117.0 Blue marlin L4 TT — 4.33691 1.93860 — 75 5.1410 24.0 48.0 White marlin W LL4 — _~ -2.41011 2.37515 — 182 0.0593 47.5 70.0 White marlinW LL4 G -2.20239 1.24968 1.25290 177 0.0472 47.5 70.0 White marlin L4 LI — -0.71780 0.66084 — 196 1.8680 TDS: 99.0 White marlinL4 L2 — _—~ -0.59179 0.73942 — 193 1.5571 65.5 91.0 White marlin L4 L3 _— 1.17904 0.83010 — 192 1.1205 56.0 79.0 White marlin L4 TT — 40.38790 0.64258 — 185 3.0604 11.0 27.0 Sailfish W LL4 — ~— -3.89480 3.15757 — 244 0.0532 15.8 62.5 Sailfish W LL4 G -3.36702 2.27782 0.73757 242 0.0480 15.8 62.5 Sailfish L4 LI] — -1.96822 0.68216 a 260 1.5403 26.0 93.0 Sailfish L4 L2 — _— -1.09314 0.75088 = 260 1.2235 23.0 85.0 Sailfish L4 L3 — — -0.78628 0.87262 —_ 267 0.9175 19.2 TPS) Sailfish L4 TT — _— 11.66889 1.87509 — 256 4.0575 4.0 28.0 ™W = logio (weight) LL4 = logio(eye-fork length) L4 =eye-fork length L1 = total length L2 = fork length L3 = body length TT = caudal spread G =girth three species were plotted against month of capture weight, caudal spread, and the measures of length. to examine the possibility of seasonal patterns in the Approximately 75% of the specimens could be prop- relations. None was found. erly sexed. Although this procedure produced better Multivariate analysis was used in an attempt to results than pure guesswork, the results are not satis- develop a method of sexing white marlin given factory for scientific purposes. 123 —— FEMALE +++ ++MALE 40}- WEIGHT (pounds) uo is} 7 20;-— 10 1 1 ! 1 it 10 20 30 40 50 60 EYE- FORK LENGTH (inches) Lit 70 80 90 100 Figure 1.—Relationship of weight and eye-fork length of white marlin (Tetrapturus albidus) by sex. Multivariate analysis was also used to determine if white marlin could be allocated to Florida or Louisiana given weight, caudal spread, and the measures of length. White marlin could not be so allocated. A review of the literature revealed that very little had been done on length-weight relations of bill- fishes in the western Atlantic Ocean. De Sylva and Davis (1963) estimated the relation between body length and weight for white marlin and noted the same sexual difference found in this study. De Sylva (1957) plotted weight and total lengths of sailfish but did not estimate the parameters of the relation. The results of our analyses will permit conver- sions from one type of length to another and also will provide better estimates of weight from length plus girth measurements. ACKNOWLEDGMENTS Many people aided in establishing our sampling stations in the Gulf of Mexico and in obtaining the data. These include G. Maddox, L. Ogren, J. Yurt, R. Metcalfe, J. Ogle, J. Lockfaw, and R. Schwartz. Cooperative scientists who provided data from their files were D. Erdman, L. Rivas, J. Casey, and F. Mather, III. Officers and members of the New Or- 124 — FEMALE ao a uo np A EYE-FORK LENGTH (inches) {e} 16 18 20 22 24 26 28 30 32 CAUDAL SPREAD (inches) 10 12 14 5 Figure 2.—Relationship of eye-fork length and caudal spread of white marlin (Tetrapturus albidus) by sex. leans Big Game Fishing Club, Mobile Big Game Fishing Club, Pensacola Big Game Fishing Club, Destin Charter Boat Association, and the Panama City Charter Boat Association were extremely cooperative. To all of these people, we owe a debt of gratitude. And finally, we thank all the cooperative boat captains and anglers for allowing us to examine their catches. LITERATURE CITED DE SYLVA, D.P. 1957. Studies on the age and growth of the Atlantic sailfish, EYE-FORK LENGTH (inches) CAUDAL SPREAD (inches) Figure 3.—Relationship of eye-fork length and caudal spread of sailfish (Istiophorus platypterus) by sex. Istiophorus americanus (Cuvier), using length-frequency curves. Bull. Mar. Sci. Gulf Caribb. 7:1-20. DE SYLVA, D.P., and W.P. DAVIS. 1963. White marlin, Tetrapturus albidus, inthe middle Atlan- tic bight, with observations on the hydrography of the fishing grounds. Copeia 1963:81-99. 125 RIVAS, L.R. 1956. Definitions and methods of measuring and counting in the billfishes (Istiophoridae, Xiphiidae). Bull. Mar. Sci. Gulf Caribb. 6:18-27. ROYCE, W.F. 1957. Observations on the spearfishes of the central Pacific. U.S. Fish Wildl. Serv., Fish. Bull. 57:497-554. Length-Weight Relationships for Six Species of Billfishes in the Central Pacific Ocean ROBERT A. SKILLMAN and MARIAN Y.Y. YONG! ABSTRACT Weight-length relationships for six species of billfishes in the central Pacific Ocean were developed by analyzing 20 yr of data. Log-linear and nonlinear statistical models were fitted to the data by regression analysis, and residuals from the models were tested. Blue marlin, Makaira nigricans Lacepede, (50-135 cm FL), male blue marlin (~135 cm FL) and sailfish, /stiophorus platypterus (Shaw and Nodder), apparently have coefficients of allometry less than 3.0. Black marlin, M. indica (Cuvier) and female blue marlin (2135 cm FL) apparently have coefficients equal to 3.0. Shortbill spearfish, Tetrapturus angustirostris Tanaka, striped marlin, 7. audax (Philippi), and swordfish, Xiphias gladius Linnaeus, apparently have coefficients greater than 3.0. As with most studies on the length-weight rela- tionship, this study is not an end in itself. It was initiated to provide length-weight conversion rela- tionships (Equation 1) for use in a growth paper on blue and striped marlins (Skillman and Yong’), as well as to provide conversion charts for the sport fishermen at the Hawalian International Billfish Tournament. There are few published papers on the weight-length relationship of billfishes* (de Sylva, 1957; Royce, 1957; Kume and Joseph, 1969); hence, we decided to calculate this relationship for all six species of billfishes on which data had been collected by the Honolulu Laboratory of the Southwest Fisheries Center, National Marine Fisheries Ser- vice. These six species were the black marlin, Makaira indica (Cuvier), blue marlin, M. nigricans Lacépéde, sailfish, /stiophorus platypterus (Shaw and Nodder), shortbill spearfish, Tetrapturus an- gustirostris Tanaka, striped marlin, T. audax (Philippi), and swordfish, Xiphias gladius Linnaeus. Although all of the length-weight data collected on billfishes from 1950 to 1971 by the Honolulu Laboratory were used, this study should not be con- sidered exhaustive or definitive. Even in the best represented species, there were too few data to sepa- ‘Southwest Fisheries Center, Honolulu Laboratory, National Marine Fisheries Service, NOAA, Honolulu, HI 96812. *Skillman, R.A., and M.Y.Y. Yong. Growth of blue marlin, Makaira nigricans Lacépéde, and striped marlin, Tetrapturus audax (Philippi) in the north central Pacific Ocean by the progres- sion of modes method. Manuscript. National Marine Fisheries Service, Southwest Fisheries Center, Honolulu, HI 96812. ’The term billfishes, as used in this paper, includes swordfish. 126 rate the data according to sex, maturity, and season as suggested by Le Cren (1951) and Tesch (1968). Thus, it was impossible to perform a detailed analysis of covariance similar to that performed re- cently by Brown and Hennemuth (1971) on haddock, Melanogrammus aeglefinus (Linnaeus). Some species were so poorly represented that the length- weight relationships should be considered as tenta- tive relationships. In general, fishery biologists have accepted the appropriateness of the allometric growth equation (Huxley and Teissier, 1936) or its mathematical equivalent, the power function, as a descriptor of growth in weight to growth in length. We accepted the general form of the relationship (Equation 1) and applied both the log-linear and the nonlinear statisti- cal (1) models of the relationship. Each model is discussed, and statistical procedures for evaluating the good- ness of fit are presented. Papers by Glass (1969), Pienaar and Thomson (1969), and Hafley (1969) are particularly relevant to this discussion. W; = b, L;% MATERIALS AND METHODS Collection of Data The data used in this report came from three sources. In nearly all of them fork length (FL) mea- surements were taken to the nearest centimeter from the tip of the snout to the fork of the tail. Where naris or eye-orbit fork length measures were given, conversion to FL was performed with equa- tions given by Royce (1957). All weight measure- ments were taken to the nearest pound and were converted to kilograms before analysis. Two of the data sets were derived from longline catch records taken by research vessels of the Ho- nolulu Laboratory while fishing in central Pacific waters, mostly near the equator. The first of these data sets (deck 1) was obtained from a morphometric study of billfishes by Royce (1957) that was carried out on a series of longline cruises in 1950 to 1953. The second data set (deck 2) was obtained from routine information collected from longline-caught fishes for the years 1950 to 1971. These two longline data sets were combined in the subsequent analyses because they represent the same type of data, though they were collected for different reasons and, in general, do not overlap in time. The last set of data (deck 3) was collected by personnel of the Honolulu Laboratory from fish caught by trolling between 1962 and 1971, in June (once), July, or August during the Hawaiian International Billfish Tournament held in Kailua-Kona, Hawaii (Table 1). Since the five species other than blue marlin were represented in such small numbers in the sample, they were pooled with the longline data. For blue marlin, the trolling-derived data were analyzed separately from the longline-derived data. The longline data repre- sent a pooling over all seasons of oceanic-caught fish while the trolling data represent only inshore catches during the summer months. All three data sets for most species contained some determinations of sex and maturity, but only the trolling data (deck 3) for blue marlin contained enough information to allow an examination of the sexes separately. All other species and pooled data sets were examined without regard to the sex of the individuals. Analysis The goal of this paper was to obtain length-weight relationships for each species by using a statistical model that fitted the data best. To accomplish this goal, the steps listed below were followed: 1. The data were checked for different growth stanzas by plotting the natural logarithms of weight against the natural logarithms of length. 127 . Length-weight relationships using log-linear regression for weight on length were ob- tained for all species. . The normality of the error terms was tested for those species that had enough data to perform the tests. . The log-linear relationships were tested for their significance. . Length-weight relationships using nonlinear regression of weight on length were ob- tained for blue and striped marlins. . Statistical tests were performed to deter- mine whether the log-linear or the nonlinear model was more appropriate. . The coefficients of allometry were tested to see if they were different from 3.0. In subsequent paragraphs, brief discussions will be given regarding adjustments made for the amount of data available for each species, the statistical models themselves, the criteria used to determine best fit, and certain test statistics employed in the analysis. As can be seen from Table 1, the amount of data available for most of the species for any data deck was very small. Even after pooling all of the data for the black marlin, sailfish, shortbill spearfish, and swordfish, there were too few data to evaluate the fit of the statistical models. Hence, the most commonly used statistical model, the log-linear, was fitted to these species. Only the significance of the relation- ships was tested. For striped marlin after pooling all data, there were enough data to evaluate the fit of the statistical models. In the analysis of blue marlin, the data were not pooled because we believed that the longline- and troll-derived data represented different biological situations. The longline data were ob- tained from a sampling program that neglected any seasonally varying and sexually different length- weight relationships, whereas the troll data were obtained in the summer season for each sex. To aid in the interpretation of the striped marlin data, the blue marlin data were pooled for comparative pur- poses only. There were enough data to evaluate the fit of the models for all blue marlin data categories. As mentioned in the introduction of this paper, fishery biologists, in general, have accepted the ap- propriateness of the allometric growth equation as a descriptor of the growth in weight to the growth in length of fish. As expressed by Equation 1, this equation is mathematically a functional relationship (Madansky, 1959) where weight is known exactly Gis GE =I6 ~~ WP @ Vo ES G See aa oe eer te b Gp OG IG I RIOL fi ee eee) One ea ee a eS De p2]00d = = = = = = = a = = = = = = = i = os = = = = = € 499d iB =.) See eet) ah, ae Ge ee in oe ee oe ee eee ee ee ee = SS Zz 499d = = = = = — = = = = =a = = = = — = = is = = = = 1 xooq YSYPLOMS (Pea eee Sate SG SS OS ee at Se eS eee I a ee 9S oe ol € ‘ ‘I pajood II = aac auery I c = I I See eae SS ap eg Ee a ee. CS ee € 399d See eee Cl ite ee ed eS ol ae a ee Se F I (=. sae al 7 499 ial I a SS ae Sa ee i a re © z S = 1 xed ure pads 91 I eet al ee ae aoe es ee Ee a eee, I = = € Sa € “7 “1 patood I I perunthos (Pepe en a ee Me coy oe ee ee BE es eee Se ee ae SS a ee Soe Leo € 499d Vee eo moe a Sire Se co tS ho 2 a ae eee. ee a mac ee z 9C iS Sea elie aee ee reey ee cae Nes ee ae oe ee pa es ee ae eee ae E (4 =e > 1 9d ysyevads |[1qi1oys So Coe a a a ee ee eS Ae L z = = € ‘ZT ‘1 pajood c = c a => =o = = = = = oa an = = = a =e 7 =F = = = £ 499d €l SS lS ee a ae oe I =. >} oS Sa I € L I a z 499d € Be a ee ay et ee eee eo oe Oe ee ae i il! =n ae 1 y99q ysi[les OL et pe Se ew ae Re eS Say Be, ae 8 a ee eee UC re Ce a as. Z ‘1 pajood GE YB = “BD = SIG Tt ae Se ea 8 a ee I i oc ee eee ee) Ol ee we € 499q SE =) eee — wa a S - — S S ma gy oe ae een) LSS, = a z 99 Se Se ra gc a a ae eS ) = kee 1 99d ulLRW ong 1X6 =a a I G = € = re c I = = a = = t (6 9 14 = — — € ‘7 ‘IT pajood 8 = = I c a c = = c I = am == = = mr = ma £ 499d 6 oe eee ew o> ae es a ee ee es ce € ea me Z 499d L Soe ah ee a ae ae a ee oe Se ng ae ee LS ee ¢ == Ss 1 x99 uljleu YOR _ PI0L IL6l OL6l 6961 8961 L96I 9961 S96I P96I £961 C96I 1961 O96I 6S6I 8S6I LS6I 9561 SS6Il PS6l ES6I TS6I IS6I OS6I saisadg 1e9 A “WUOWeUINO | YSY[[IG [PUONBUIIIUT UBIRMEH oy] WO. St g Yap puLY ‘yap ped yound aurjsuo] s Arojyesoge] njynjouoH ay} st Z 49a ‘(L661 POY WO St | Yap as9yM ‘ydap vivp Aq ‘Awad Aq ‘saidads Aq suONRAsasgo Jo aqUINN—"| aqr yp 128 from a given length; this is not a biologically reason- able model. Traditionally, length has been viewed as the independent variable that is measured with no error and weight as the random dependent variable that is measured with error. The validity of these assumptions is beyond the scope of this paper and will not be discussed. We have concerned ourselves with the appropriateness of two statistical models, the log-linear and nonlinear models. The log-linear model, with log-additive error, was written as In W; = Inb, + a, InL; + In€,;- ( The arithmetic equivalent of this model can be writ- ten as but this equation should not be construed to be the model. The nonlinear model, with additive error, was written as W; = byl; 93 + € 5° (3) The evaluation of the goodness of fit of regres- sion lines can be divided into distinct tests of preci- sion (or significance) of the regression and of the appropriateness of the model. The appropriateness of a model (Equation 2 or 3) was tentatively ac- cepted, and the model was fitted to the data. The precision of this fit can then be measured by the “F’’ test and the ‘‘r’’ test, both of which test HV: a 0 and Ha: a # 0, or the “‘R®’’ siatistic, the ‘‘proportion of total variation about the mean Y [W] explained by regression’’ (Draper and Smith, 1966). All of these tests are equivalent and basically mea- sure the usefulness of the regression as a predictor. To be able to perform any of these tests, the ran- dom error term must be normally distributed. The distribution of€’,, = In€,; was tested for the log- linear model by calculating R.A. Fisher’s statistics for skewness (G1) and kurtosis (G2, measuring the amount of peakness or bimodality). A model can fail in the significance tests because the model is incorrect or because the sample size is small rela- tive to the amount of variability in the data. In addi- tion, if a model is nonlinear in its parameters, it is not possible to test for significance because the var- iance estimates are biased, making it superfluous to test the distribution of the error term, €,; Moreover, the residual sums of squares for linear and nonlinear least squares fitting routines cannot 129 be compared because they are minimal estimates in their respective sample spaces. We chose to present the ‘‘R?’’ and ‘‘F’’ statistics for the log-linear model as an indication of precision, but did not use the statistics in deciding best fit, since they cannot be compared to those obtained for the nonlinear model. Our criteria for best fit of the models were based on measures of appropriateness, namely, whether the error terms have the following properties: "E[€3;] = 0 or E[€;\] 0 Var(€,;) = 03 or Var(€3;) = J) = 93, (4) that is, the error terms have a mean equal to zero and a constant variance. The error terms for the log-linear model must have a mean equal to zero, since an intercept term was included in the model (Draper and Smith, 1966, p. 87). For the nonlinear model, it is not readily apparent that the error term must be equal to zero; hence, the mean was calcu- lated. The residuals were plotted against the depen- dent and independent variables to check for con- stant variance. If variance is constant, the residuals appear as a horizontal band along the variable axes (Draper and Smith, 1966, p. 86). The final regression coefficients, or eocincionts of allometry, were tested using the hypothesis scheme Hy: a = 3.0, HA: a # 3.0 (Steel and Tor- rie, 1960, p. 171). In reporting the results of the various statistical tests, the following convention was used: ‘‘NS”’ in- dicates not significant at the 0.05 level, ‘‘*, **, ***” indicate significance at the 0.05, 0.01, 0.001 levels, respectively; and ‘‘d.f.’’ stands for degrees of freedom. RESULTS Growth Stanzas The weight-length data for each species were first plotted with logarithms of weight versus logarithms of fork length in order to subjectively check for more than one growth stanza (Tesch, 1968). Blue marlin ‘From this statement, the estimated value of the log- -error term, €3;, may be taken as zero which in turn indicates that € ,; in the arithmetic equivalent to the log-linear model (Equation 2) may be taken as equal to one. If the arithmetic equivalent to the log-linear model were designated as a separate model, it does not follow that E [€,;] = 1 or that Var(€,;) =@22. “WNiep JURIIAge a]TuIs awWes 94} IpNjoul sjas eIep asay]z *[9A3] CO'0 ay} IB BOUBdIFIUTIS SAIVIIPUL . “JIAI] CO"() BY) IV IULIYIUTIS JOU SAWIIPUL SN ‘AAI [()'Y AYIIV BdUPIIPLUTIS SAIBIIPUL x4 [AAI] 100'O FYI W IUBIPIUTIS SAIVIIPUT 4 x 41 xa E SED a or 10r8'0 9870'0 6910°0 6°86 SOEs 2-01 X96 'T L Pp2]90d YS POMS == = #aP TT tcLr'0 9910'0 9t£0°0 1't6 OSLtE’ 2-01 X9TIL'S €s Pp2]00d ure padiyg x&LO 9T = S6Le'rl 96SS'0 zet0'0 T'S9 8EEB' 8-01 X £800°S OI p2]00d ysyvods |[Iquoys **4P0'68 oa = OLLIV'T 79L0'0 87700 8'P8 pS09'T s-OI X6£L0°7 8l p2]00d Yysy[les xealLS Ppl SN 670- SNTI0O- +1670 6800°0 L710'0 CT t6 IL81°¢ 9-OL XSPr6' 1 S8 (ayeway) SuTOrL, zz *S6 1 xetL'0- IZI¢°0 9600°0 £S10'0 0°76 1190°¢ 9-01 X0786'£ 98; (a]ewaz) Surpory, = «C97 *x*CL'0— 6 LT0 LS00°0 81100 L78 SOPL'T c-OI X6767 7 9LT (a]euw) Surpfosy, = «#881 «48P'0— p0P0'0 £100°0 T1100 6 +6 OLP0'' 9-01 X8967 PF P8t Suryfor], =a +**60°T 489° 0— 90600 £100°0 91100 Lv6 S9l0'' 9-O1 XT180°S S8tz Buryfory, xx%LT LL9‘T a SN CTO TLOT'O SS00'°0 7L10°0 7'96 TrPO'E 9-Ol X97TL'P 89 aul[suo'] TH Wo c¢l= = *4LL'T #60 0— 1100°0 97£0'0 97100 0'S6 PIcO'’ 9-01 X8P00'S £Shz p2]00d ule on} TA W9 sel-0s ¥£6°TS = ae Ps9l0 -800'0 cL00'0 96 8L99'0 1-01 XL781°S i aulsuo] uljielu on[ #%%9E99OL = = relr'0 Ic10°0 6900'0 t'L6 PS9l'e 9-OI XL8LE°7 PC p2]00d uljielu yor ae) ZOD nS) q D Jul‘mul — juaoiad D q (N) jas BING saroadg ul azis JOURLIE A zu ajdiueg “‘PAUILWIDJ9p JOU SPM XAS YOIYM JOJ BJP PIALIIp-SUI[[O1] SAPN[SUI UlpABWW aN{q 10} KIBP pajood ay_fp “aiviidoidde yOu dam $isa) ;RONSHRIS TY) aedIpul sayseG “elepP Bul[[O.] pu suljsuo] Jo Sul[Ood sajevdIpul SuIpeay Jas BIep dy) JapuN ALOBaAIVS pajood ay] (7 UONRNbA) japow sPdaut]-ToO] ay) Suisn saysy|fig 40J sdiysuoneyjas yIus]-1YysIaM—'7Z 9[qQv_fpe 130 (—.— T T T Tae Doce T T ee a t a | al * Ye & B IT: a | x = 4h * i x= 9 L i 4 = 3h a | * b et Al ee | —— 1 aS 1 1 1 1 1 3.0 3.5 40 45 5.0 5.5 6.0 6.5 LN LENGTH (CM) Figure 1.—Blue marlin data from longline data are plotted on a log-log scale to show the existence of two growth stanzas. The straight lines were fitted by eye. was the only species exhibiting such a trend (Fig. 1) and then only for the longline-caught fish. Although it was quite evident that two growth stanzas existed, there were too few data to determine exactly where the two stanzas met or overlapped. We arbitrarily took the two data points at 135 cm FL (4.9 in natural logarithms) as the overlap area, with the assumption that the length-weight relationship for the older, well-represented stanza should be accurately pre- dicted even if it actually began at a smaller size while that for the younger stanza is provisional. The younger growth stanza was treated separately in the subsequent analyses. Log-Linear Model The log-linear model (Equation 2) was fitted to the data for all species (Table 2). The ‘‘F’”’ tests for black marlin, sailfish, shortbill spearfish, and swordfish were highly significant. Though the idea that a log- linear relationship between weight and fork length might not exist was rejected, this was a provisional conclusion because the validity of the statistical tests could not be checked. The proportion of the total variation accounted for by the regression, R*, was high for all species except for the shortbill spearfish, where the usefulness of the relationship as a predic- tor was not great. For striped marlin, although the “‘R?”’ value was high, the distribution of the error term was not normal. The sample size was too small to evaluate kurtosis, but since the more critical con- dition of skewness was highly significant, tests of significance could not be performed. For compara- tive purposes, the log-linear model was fitted to the pooled data for the blue marlin, and, as was the case for striped marlin, the error term was not normally distributed. For the blue marlin longline data, the error term was not skewed, and there were too few data to test for kurtosis. Tentatively accepting the error term as being normally distributed, the ‘‘F’’ test showed that the regression was highly signifi- cant. For the trolling data, the error term was not normally distributed; hence, tests of significance could not be performed. Examination of the error terms showed that there was one aberrant datum; Table 3.—Weight-length relationships for blue and striped marlins using the nonlinear model (Equation 3). The data sets pooled category indicates pooling of longline and trolling data. Sample R? in Species Data set size (N) b a percent € Git G2} Blue marlin Pooled 453 6.3087 x 10-° 2.9827 93.1 —0.5717 — — 2135 cm FL Longline 68 3.9290 x 10-6 3.0821 94.4 —1.1889 — a Trolling 385 8.5300 107° 2.9265 92.2 —0.6549 —2.299** 36.691** Trolling 384 1.9421 10-6 3.1895 98.9 0.3003 —0.266* 387/235 Trolling (male) 276 18.9972 x 10-° 2.7756 83.1 0.1438 0.121 NS 2.894** Trolling (female) 86 4.8246 10-° 3.0249 90.8 0.4055 —2.991** 20.499** Trolling 85 1.7082 x 10-® 3.2111 91.9 —0.1341 -0.067 NS 0.577 NS Striped marlin Pooled 53 1.0978 10-6 3.2589 90.7 —0.1553 — — 1k indicates significance at the 0.01 level, * indicates significance at the 0.05 level, and NS indicates not significant at the 0.05 level. 131 0.00 RESIDUALS -0.44 3.00 0.24 3.40 3.80 4.20 4.60 5.00 5.40 5.80 FEMALE BLUE MARLIN (N=85) ; xx 0.08 0,00 6.20 RESIDUALS 4 eo 4 + 4 4 4 3.80 4.20 4.60 5.00 5.40 5.80 6.20 T T —— =——S— STRIPED MARLIN (N=53) 0.33 RESIDUALS 0.00 -0.17 1 2.80 1 4 3.60 4.00 LOGe WEIGHT (KG) = — 1 0-33 50 2.40 3.20 440 480 5.20 4.90 5.40 LOG. FORK LENGTH (CM) 5,00 5.10 5.20 5.30 550 5.60 5.70 Figure 2.—Plot of residuals from the log-linear model for female blue marlin with 86 and 85 samples and for striped marlin with 53 samples. Weight was recorded in kilograms and fork length in centimeters. however, the elimination of this datum did not alter the results significantly. When the trolling data were divided into males and females, the error terms were still not normally distributed. However, when the above mentioned aberrant datum for the female data was dropped from the calculations, the error terms were normally distributed. The ‘‘F’’ test showed that the relationship was highly significant, and the relationship accounted for 93% of the variation in the data. For large blue marlin (five relationships) and striped marlin, the residuals about the regression line were plotted against the dependent (weight) and in- 132 dependent (fork length) variables in order to evaluate the fit of the log-linear model. In every case, the distribution of the residuals appeared as a band along the axes; hence, the model appeared to fit the data. The results for striped marlin and blue marlin (trolling data for females with all data points and with the one aberrant datum point dropped) were representative of all the species plots. These results are presented in Figure 2. The two plots for the blue marlin indicated the effect of the aberrant datum that was discussed earlier when the normality of the residuals was tested. In spite of the residuals not being normally distributed for all except two of LL LL LAP LT FEMALE BLUE MARLIN (N=86) - x x * x x x ye g Ok Shee EE SOS Se ore EE Ceara oe > {Le x x =) ra -60.5>- x = al 18135 80 120 160 200 (ia PSL Lia af T T T 38.0 FEMALE BLUE MARLIN(N=85). 19.0 o F se we z eee ies 2 Of =r As ee a o L . x Site ~ 4 in xa all z Sl 7 -38.0- | fe 4 ath J] -57.0— L L ee eet ft $a tt 4 n 4 4 1 A pk 1 1 1 1 Tl | i 80 120 160 200 240 280 320 360 200 240 280 320 360 400 440 480 520 a Teel ote ner ee a ell a eT 27.0 .* 4 x 4 STRIPED MARLIN (N=53) [ * r 18.0 Fr ~ x xpax o if x [ x a 20F a ally a x x 5) =) i. mx mr a 1s ieee x x b x *n x “* pee ye hy pe n [ip es jy ! fetal to 1 73 121 WEIGHT (KG) 89 137 i 1 142 162 182 202 222 242 282 302 FORK LENGTH (CM) 262 Figure 3.—Plot of residuals from the nonlinear model for female blue marlin with 86 and 85 samples and for striped marlin with 53 samples. the cases (Table 2), the plotting of the residuals indicated that there was no reason to reject the as- sumption of constant variance. Hence, the log-linear model seemed to be appropriate. Nonlinear Model The nonlinear model (Equation 3) was fitted to the data for the large blue marlin (five relationships) and the striped marlin (Table 3) in order to compare the fit of this model to that for the log-linear model. Since the estimate of 0? is biased in nonlinear regression 133 and therefore tests of significance cannot be made, the distribution of the error terms was not tested. The estimates of ‘‘R?’’ (a biased estimator in this nonlinear case) indicated that the nonlinear model does not in general account for as much of the varia- tion in the data and is, therefore, not as good a predictor as the log-linear model. When the residuals from the nonlinear regression lines were plotted against the dependent and independent variables, it was found in every case that the amount of error was small for small values of the variables and large for large values of the variables. Hence, the assumption of constant variance of the error term must be re- jected for all cases. The results for blue marlin, trol- ling data for females with 86 and 85 data points, and for striped marlin presented in Figure 3 were rep- resentative of all species plots. Comparing these plots with those in Figure 2 showed that the non- linear model did not fit the data as well as did the log-linear model. Since both assumptions regarding the properties of the error terms were rejected, it must be concluded that the nonlinear model is not appropriate for these sets of data. Coefficients of Allometry The coefficients of allometry that will be dis- cussed in this section were obtained from the fitting of the log-linear model. For those species and data sets in Table 2 where the assumption of normality of the residuals was rejected, the coefficients of al- lometry were not tested. The hypotheses tested were Hy: a = 3.0 and Ha: a ¥ 3.0 (a two-sided “?’’ test), and the results of these tests are pre- sented in Table 4. For small blue marlin and sword- fish, the null hypothesis that a = 3.0 was rejected on the basis of the data available. For black marlin, large blue marlin (longline data), female blue mar- lin, sailfish, and shortbill spearfish, the alternate hypothesis that a # 3.0 was rejected on the basis of the data available. DISCUSSION Weight-length relationships were fitted success- fully for all six species of billfishes appearing in the Honolulu Laboratory’s collections (Figs. 4 and 5). The log-linear relationships (Table 2) were found to be more appropriate than the nonlinear relation- ships (Table 3) for every species and data set. The significance of all the relationships was not testable since many of the error terms were not normally distributed; however, the ‘‘R?’’ values indicated that all of the relationships, except for the shortbill spearfish, account for a high percentage of the var- iance in the data. Hence, on the basis of fit and amount of variance accounted for, these relation- ships should be good predictors. However, the usefulness of the relationships as predictors also varies according to the amount of 400 100 oats T = ap UF Gal Cee oie T ears secs SWORDFISH 4 | BLACK MARLIN W = 2.3296 x 10-7 FL3-5305 W= 2.3787 x 10-6 FL 3.1654 * 300 N=7 + 3001 N=24 R - 200} ° + 200 4 28 9 | > 3 ad 100 + ze 100 ° Oe fal — iad Se ar aor re fe) be ary Se ee 100 150 200 250 300 350 400 200 225 250 275 300 325 350 375 400 T T a 30 SHORTBILL SPEARFISH 150+ STRIPED MARLIN 4 W = 5.0083 x 1078 FL3.8338 W= 5.7126 X 10-7 FL>-3756 N=16 L N=53 4 © < 204+ 100 + 4 = a b “ a ro) - w 10 so} Ent : r RS 7 fe) — 4 L 4 fo) L Ls fee aot 130 140 150 160 170 180 190 $125 150 175 200 225 250 275 300 325 75 r LENGTH (CM) | SAILFISH = W= 2.0739 X 10°> FL2-6054 g 50 N=18 3 [= + Ir . co) = WwW 25+ = ee IL — (e) 4 4 — 150 175 200 225 250 275 300 LENGTH (CM) Figure 4.—Weight-length relationships using the log-linear model for swordfish, shortbill spearfish, sailfish, black marlin, and striped marlin. 134 [PAI] CO'O AY) 1B JuULdIUTIS JOU SAIVSIPUL SN Pur “]ara] sO" yd Ww aduKdylusIs saywoIpul « “[PA2] [0° 24) 1B BoUBdIPIUTIS sayedIpUT ,.4; 0°677-0' TET 196° sOLXSTIT7 S'PTE-C SHI #SE1€ SOES'E 2-01 X967E'7 L p2[00d YSYPIOMS O'TTC-0°801 680°€ 901 XP9Ss's VOle-c' Chl s OSLE'E 2-O1 X97ZIL'S €¢ p2[00d ulpiew pedis 0°9S1-0°87Z1 pele L01 xOces'T 0°081-0°0rI SN SIT 8EesE s-O1 X€80u'S 91 P2]00d Ysyteads [f1quo0Ys 0°S0C-0'rET [9p sOI X96ST'T O'18c-0'LL1 SN 62b°1 — pS09°T s-Ol X6£L0°C 81 p2[ood YsyTes me a =< CT LBE-T SOC SN 986'1 IL8I°€ 9-01 XSbr6'l s8 (ayeway) SurorL rs = a O'TT€-S9LT = SOPL'C s-OI X667'Z 9L7 (ayew) surorL as = = C'68E-0'9S1 = OLPO'E 9-01 X8967'P bse SurTOIL 0°0L7-0°L91 CC8°T sOI XSgs'e C10b-0'SET SN $6S°0 crb0'e 9-OI X9CCL'P 89 aul[suoT Td W9 cele e= a =r 6°9Sb-0'SET a PICO’ 9-01 X8h00'°S tsp p2[00d ulpeur ong Td W9 Set-0s a = a O'SET-0'0S «x 01P ST— 8L99°0 1-O1 XZ781°S v aul[su0] OT TeUen = 4 ae O'ELE-S PIT SN Lpp'l psol'e 9-OLXL8LE°T be P2]00d uyreu youd aduel 9Z1S$ D q aduel 9ZIS oe = 0 :NyY D q (N) 9zIs jas eed saroadg aloe [edidoly, wiaj}seq 1OJ J, ajdwies “YIBuUa] YAOJ S.AIIWNUID UL BIN SITURA IZIG “PIWAoOjsad aq A|piea JOU P[NOd 389} ay) JY) aWworpul soysed “(6961) Ydasor puke aWNy WO paulE}go d19M JOB [PIIdO.N) ULIISkd ay) 10} LILP AYE “CE 4 22VH UaY] seM SisayJodAY ayeusayyE SurAuedwosor oy) pur ‘pajsa} sisayjodAy [[Nu ay} sayesipur Ny ‘sjas eyep payesipul ay) 104 * 5 pid = M [apow raur-do] ay) Tursn sdiysuonvjas yIug|-yysiam [eul{—'p IQR 135 data used in the analysis, the range of the data, and whether sexes were analyzed separately. Consider- ing the sample size (4) and the method of selecting the points of overlap, the relationship for small blue marlin (50-135 cm FL) was provisional. The rela- tionship for shortbill spearfish was also provisional since there were 16 data points ranging from 140.0 to 180.0 cm FL. Although the sample sizes for black marlin, sailfish, and swordfish were small (24, 18, and 7, respectively), the ranges were wide, and the relationships should be taken as valid estimates. For striped marlin and for blue marlin, considering all data sets, there were enough data to obtain valid relationships. The importance of the results for the various blue marlin data sets will be discussed in connection with the coefficients of allometry. Concrete interpretations of the coefficients of al- lometry are precluded by a statistical inability to test the significance of all the coefficients as well as to test between coefficients of different species or data sets. The coefficient for swordfish was the only one tested that was apparently greater than 3.0. For the other species tested, black marlin, blue marlin (longline data), female blue marlin (trolling data), sailfish, and shortbill spearfish, the hypothesis that the coefficient was equal to 3.0 could not be rejected. That is, the growth in weight to length was isometric for these species. Intui- tively, we doubt these results for sailfish and short- bill spearfish and suspect that additional data would show the coefficient for sailfish to be less than isometry and for shortbill spearfish to be greater than isometry. For blue marlin, the interpretation of the results was complicated by an inability to perform statisti- cal tests of hypotheses. The coefficient of allometry for the small blue marlin indicated that the small fish maintain a very different weight to length growth relationship than do the larger, adult fish. Part of this difference may have been due to differ- ential growth of the bill in the younger fish. It was apparent from Table 4 that there was not a real difference between longline- and troll-caught blue marlin; the coefficients of allometry as well as the intercept ‘‘b’’ were extremely similar. This does not necessarily imply that there are no seasonal dif- ferences in the weight-length relationship of blue marlin but does indicate that no such effect could be shown with 68 data points from longline catches made over all seasons. When the trolling data were divided according to sex, it was found that the coef- ficient for females did not differ significantly from 136 BLUE MARLIN 50-135 CM FL W=0.5183 FLO-6678 2135 CM FL W= 4.7226 x 10-6 FL3.0442 oO N=68 Ss bE x= ° w = MALES AND FEMALES W= 4.2968 x 10 6FL 304970 N=384 eo x b x ©) w = SO es Ve aoa FEMALES W= 1.9445 x 1076 FL3-/87! 300+ N=85 © L 4 EE 200+ x= ro) - WwW : | 100 oh 11 _i 300 = W= 2.2929 X 1079 FL2.7405 200 N= 276 l= L m5 OAS ° . w 100} ‘i = a ein 50 100 150 200 250 300 350 400 450 LENGTH (CM) Figure 5.—Weight-length relationships using the log- linear model for blue marlin. The upper chart represents the relationships found for small and large fish using long- line data. The remaining three charts represent relation- ships for sexes combined (including sex undetermined), females, and males using trolling data. The aberrant datum appearing in the sexes combined and female charts for the trolling data was not used in the calculation of the relationships. isometry while that for males was probably less than isometry. The male and female curves (Fig. 5) could not be distinguished where the data over- lapped. Hence, the increased weight to length growth shown by the females occurs primarily at lengths greater than those attained by males in this data set. The sexual dimorphism in length that has been noted by many workers (e.g., Strasburg, 1970) apparently extends to the weight-length relationship also. That is, females not only grow to a greater length than males, but are proportionally heavier at the same length. For striped marlin, analysis of the pooled data produced an estimate of the coefficient of allometry that appears to be greater than isometry. Inability to divide the data by sex was unfortunate since it is not known whether sexually dimorphic growth characteristics exist for the striped marlin. If such an effect does exist, it is believed to be less marked than in the blue marlin. Hence, the largeness of the striped marlin coefficient relative to that for the blue marlin, for both pooled and female data alone, probably was not due to sexual dimorphism. There are only two papers in the literature giving weight-length relationships that may be compared to ours, since the data used by Royce (1957) were included in this analysis. De Sylva (1957) presented a length-weight plot for sailfish from the Atlantic Ocean, but a model was not fitted to the data. A fish approximately 250 cm FL would weigh 34 kg whereas our study predicts 37 kg. Kume and Joseph (1969) fitted the log-linear model to blue marlin, sailfish, shortbill spearfish, striped marlin, and swordfish data. The coefficients of allometry and the intercept points from their calculations are pre- sented in Table 4 for direct comparison to those from this study. For all species, the coefficients of allometry for fish from the central Pacific were greater than those from the eastern tropical Pacific. If the coefficients were shown to be statistically different, there would be little point in comparing the intercept values since the relationships would already have been shown to be different. However, since the intercept value is related to the coefficient of condition, it should be noted that all of the inter- cept values for the central Pacific fish were smaller than those for the eastern tropical Pacific fish by a factor of 10. These differences may not be real be- cause the samples for the central Pacific contained larger individuals than did the samples for the east- ern tropical Pacific. 137 LITERATURE CITED BROWN, B.E., and R.C. HENNEMUTH. 1971. Length-weight relations of haddock from commercial landings in New England, 1931-55. U.S. Dep. Commer., NOAA Tech. Rep. NMFS SSRF-638, 13 p. DE SYLVA, D. P. 1957. Studies on the age and growth of the Atlantic sailfish, Istiophorus americanus (Cuvier), using length-frequency curves. Bull. Mar. Sci. Gulf Caribb. 7:1-20. DRAPER, N.R., and H. SMITH. 1966. Applied regression analysis. John Wiley Sons, N.Y., 407 p. GLASS, N.R. 1969. Discussion of calculation of power function with spe- cial reference to respiratory metabolism in fish. J. Fish. Res. Board Can. 26:2643-2650. HAFLEY, W.L. 1969. Calculation and miscalculation of the allometric equa- tion reconsidered. BioScience 19:974-975, 983. HUXLEY, J.S., and G. TEISSIER. 1936. Terminology of relative growth. Nature (Lond.) 137:780-781. KUME, S., and J. JOSEPH. 1969. Size composition and sexual maturity of billfish caught by the Japanese longline fishery in the Pacific Ocean east of 130°W. [In Engl.] Bull. Far Seas Fish. Res. Lab. (Shimizu), 2:115-162. LE CREN, E.D. 1951. The length-weight relationship and seasonal cycle in gonad weight and condition in the perch (Perca fluviatilis). J. Anim. Ecol. 20:201-219. MADANSKY, A. 1959. The fitting of straight lines when both variables are subject to error. J. Am. Stat. Assoc. 54:173-205. PIENAAR, L.V., and J.A. THOMSON. 1969. Allometric weight-length regression model. J. Fish. Res. Board Can. 26:123-131. ROYCE, W.F. 1957. Observations on the spearfishes of the central Pacific. U.S. Fish Wildl. Serv., Fish. Bull. 57:497-554. STEEL, R.G.D., and J.H. TORRIE. 1960. Principles and procedures of statistics with special reference to the biological sciences. McGraw-Hill, N.Y., 481 p. STRASBURG, D.W. 1970. A report on the billfishes of the central Pacific Ocean. Bull. Mar. Sci. 20:575-604. TESCH, F.W. 1968. Age and growth. Jn W.E. Ricker (editor), Methods for assessment of fish production in fresh waters, p. 93-123. International Biological Programme Handbook 3. Black- well Sci. Publ., Oxford. Food and Feeding Habits of Swordfish, Xiphias gladius Linnaeus, in the Northwest Atlantic Ocean W.B. SCOTT! and S.N. TIBBO? ABSTRACT Food and feeding habits of swordfish were studied by examining stomachs of 141 individuals captured from July to October 1971 between the Grand Bank and the southeast part of Georges Bank in the Northwest Atlantic Ocean. A wide variety of fish species made up about 80% of the diet; the remainder was squid. Species and size composition of food fishes depended on the feeding area. Large redfish (Sebastes marinus) were the most important food item in the Western Bank and Grand Bank areas, whereas silver hake (Merluccius bilinearis) made the greatest contribution in the Georges Bank area. Barracudinas, family Paralepididae, occurred mest frequently and constituted about 20 percent of the fish diet for all areas. Sabertoothed fishes, family Evermannellidae, also occurred in samples from all areas. The fact that swordfish are caught commercially on baited hooks gives special significance to knowl- edge of their food and feeding habits. Scott and Tibbo (1968) reported on stomach con- tents of about 500 swordfish taken in the Northwest Atlantic Ocean and noted that fish and squid (Illex illecebrosus) constituted the principal food. Fish outnumbered squid about 3:1 volumetrically. The most important fish species were mackerel (Scomber scombrus), white barracudina (Notolepis rissoi), silver hake (Merluccius bilinearis), redfish (Sebastes marinus), and the herring (Clupea haren- gus). A total of 31 taxa (species and families) was represented. In 1971, an additional 141 stomachs were analyzed and, although the results were more or less in basic agreement with the 1968 findings, sufficient devia- tion occurred to warrant additional comments. The 1971 study also included analysis of musculature of ingested species (fishes and squid) for mercury con- tent, in an attempt to learn more about the source of mercury in swordfish flesh. MATERIALS AND METHODS Study material consisted of 141 swordfish stomachs collected during four cruises in the sum- ‘Royal Ontario Museum, Toronto, Ontario, Canada. *Biological Station, St. Andrews, New Brunswick, Canada. 138 mer and autumn of 1971 (Figure 1). All fish were caught on longlines, using mackerel as bait. Stomach contents were preserved at sea, and identifications and volumetric analyses made later in the labora- tory. Every effort was made to identify fishes to species. Amounts of fish and squid in stomachs were measured separately, and then summed to provide a figure of total volume of stomach contents for each swordfish. After identification, samples of all ingested 4s 14 ed Allontic Ocean Figure 1.—Map showing locations of 1971 swordfish catches. species were retained for determination of mercury content. RESULTS Stomach analyses Sixteen families of fishes and the short-finned squid (I. illecebrosus) were identified from 141 swordfish stomachs. One stomach contained the remains of two octopi. Percentages by volume of fish (all species) versus squid in stomachs ranged from 78.7 to 94.0% (Table 1). These results are consistent with our earlier find- ings of 68.4 to 86.2% (Scott and Tibbo, 1968) and confirm the importance of fish in the diet of sword- fish in the Northwest Atlantic. However, the species of fishes and the amount of squid in stomachs varied with feeding areas. In the Grand Bank and Banquereau regions, twice as much squid (121.5 cc average per stomach) occurred in stomachs as in samples from Emerald Bank (62.9 cc average per stomach) (Table 1). Also, in the Grand Bank region, the volume of redfish eaten was greater than for any other species, whereas the silver hake (M. bilinearis) was absent from the diet. The sample from Emerald Bank region, however, contained a greater volume of silver hake than any other fish except the bait, mackerel. Total and average volumes of all food in swordfish stomachs for the different size groups are given in Table 2. The figures for average volume within each size group show that volumes increase with increase in size of swordfish, as might be expected. The aver- age volume of food within each size group was simi- lar for both the 1964-65 and 1971 samples. In general swordfish feed on fewer fish species and on more squid in the Grand Bank and Ban- quereau regions than in those areas to the south and west. The number of fish species increases and the Table 1.—Volumes (cc) of fish and squid in swordfish stomachs from 1971 samples. No. of Stomachs Fish Squid Total Per- Examined Fish and cent Total Average Total Average Squid Fish 50 24,126 482.5 6,073 121.5 30,199 79.9 45 14,524 322.7 2.833 62.9 17,357 83.7 37 10,052 271.7 2,717 73.4 12,769 78.7 9 1,764 196.0 112 12.4 1,876 94.0 139 Table 2.—Average volumes of all food in swordfish stomachs arranged by length groups of swordfish for 1964-65 and 1971 samples. Size Group 1964-65 1971 (fork length) Stomachs Average Stomachs Average Examined Volume Examined Volume (cm) (number) (cc) (number) (cc) 60- 79 1 20.0 3 68.3 80- 99 4 300.0 7 146.3 100-119 16 165.3 12 261.4 120-139 27 329.3 30 328.4 140-159 31 680.7 52 410.3 160-179 32 665.3 25 632.6 180-199 20 882.9 9 850.1 200-219 4 957.5 1 675.0 220-239 — _— 1 1,715.0 240-259 a= — 1 792.0 amount of squid in the stomachs decreases in regions to the south and west, particularly Browns and Georges banks and offshore canyons such as Lydonia, Hydrographer, and Washington. Fishes The 16 families of fishes eaten are listed in Table 3. The first five food items are of primary importance and constitute 84.7% by volume of the total fish ingested. The remaining 11 families are of secondary importance (6.9%) and, indeed, some of these, such as the pearlsides (Maurolicus muelleri), may be rare in the diet, since this is our first report of the species from a swordfish stomach. Unidentified fishes con- stituted 8.4% of the total. Mackerel (S. scombrus) deserves special mention because it was used as bait. Also, there is evidence of ‘‘bait robbing’’; that is, two or more mackerel, bearing evidence of hook marks, were found in a single stomach, suggesting that swordfish success- fully remove bait from hooks. The usual condition was one mackerel, presumably bait, per stomach. Occasionally, the remains of two mackerel were present. On two occasions three occurred in a single stomach and on one occasion five mackerel were eaten by one swordfish. However, the state of diges- tion often obscures hook marks. Special marking of bait would be most helpful in determining the role of mackerel in the natural diet of swordfish. Undoubt- edly, the large volume of mackerel in the diet, rep- resenting 36% of the total, is an unnatural condition. Barracudinas, family Paralepididae, were the Table 3.—List of fish species and families identified in swordfish stomachs, showing total volume (cc) of each for 1971 samples. Fish Total volume Scombridae (Mackerels) Scomber scombrus (Atlantic mackerel) 18,110 Paralepididae (Barracudinas) 10,017 Scorpaenidae (Scorpionfishes) Sebastes marinus (Redfish) 7,355 Myctophidae (Lanternfishes) 3,802 Gadidae (Cods) Merluccius bilinearis (Silver hake) 3,485 Alepisauridae (Lancetfishes) Alepisaurus ferox (Longnose lancetfish) 1,365 Stromateidae (Butterfishes) Centrolophus niger (Black ruff) 1,005 Balistidae (Triggerfishes and Filefishes) 455 Evermannellidae (Saber-toothed fishes) 198 Malacosteidae (Loosejaws) Malacosteus niger (Loosejaw) 160 Carangidae (Jacks and Pompanos) 100 Nemichthyidae (Snipe eels) Nemichthys scolopaceous (Slender snipe eel) 97 Stomiatidae (Scaled dragonfishes) Stomias boa ferox (Boa dragonfish) 40 Gempylidae (Snake mackerels) Nealotus tripes 40 Scomberesocidae (Sauries) Scomberesox saurus (Atlantic saury) 16 Gonostomatidae (Anglemouths) Maurolicus muelleri (Miller's pearlsides) 2 Unidentified fishes Total most important single fish group recorded, except mackerel, and made up 20% of the fish diet. They occurred in samples from three stations, to as many as 78 individuals in a single stomach. More bar- racudinas (781) were eaten by swordfish of all sizes than any other fish species. Many were slashed. White barracudina (Notolepis rissoi) was the princi- pal species involved but the short barracudina (Paralepis atlantica) was also identified. However, identification to species is exceedingly difficult with mutilated remains. Redfish (S$. marinus) was second in importance in terms of total volume eaten but was obviously of local or regional significance since it occurred only in Grand Bank and Western Bank samples. Also, red- fish appear to be eaten mainly by larger (over 160 cm total length) swordfish. Lanternfishes, family Myctophidae, were next in importance, occurring in three of four samples, and were represented by at least three species, Myc- 140 tophum punctatum, Notoscopelus kroyeri, and Benthosema glaciale. A total of 441 individual myc- tophids was eaten by swordfish of all sizes and as many as 80 taken from a single stomach. Silver hake (M. bilinearis) occurred in three of four samples and is considered to be the fifth of the five groups of primary importance. As noted previ- ously, it did not appear in the Grand Bank sample but did occur in samples from the Scotian Banks, where silver hake is more common. The remaining 11 families of fishes (Table 3) found occasionally in the stomachs are of unknown impor- tance in the swordfish diet. One of these, the saber- toothed fishes, family Evermannellidae, is of in- terest because it occurred in all four samples, a total of 17 individuals, yet the family has not previously been reported from the area. The black ruff, Cen- trolophus niger, family Stromateidae, although re- ported from this region of the Northwest Atlantic (Templeman and Haedrich, 1966), has not previ- ously been found in swordfish stomachs. ; Squid The short-finned squid (J. illecebrosus), like the barracudinas and myctophids, is eaten by swordfish of all sizes. As many as 27 pairs of squid beaks were found in single stomachs. On the average, more squid were found in stomachs of swordfish caught on Grand Bank and Banquereau than to the west and south. SUMMARY Species of primary importance in the swordfish diet were squid (J. illecebrosus), mackerel (S. scom- brus), barracudinas (family Paralepididae), redfish (S. marinus), lanternfishes (family Myctophidae), and silver hake (M. bilinearis). Fishes contributed greater volume to the diet than squid, the percentage contribution ranging from 78.7% to 94.0%. The vol- ume of squid in stomachs was higher in samples from the Grand Bank region than elsewhere. The total volume of food in stomachs increased with increase in size of swordfish. The species of fishes eaten varied with the feeding area but the number of species increased south- westward. Barracudinas were the most important fish group, except mackerel, in all areas. The role of mackerel in the natural diet is obscure because it was used as bait. Specimens of the saber-toothed fishes, family Evermannellidae, were found in stomachs from all four areas. ACKNOWLEDGMENTS Many people were involved in the gathering of the data in the field and laboratory. We are pleased to acknowledge the help of the staff of the Biological Station, St. Andrews, New Brunswick, and of the Royal Ontario Museum, Toronto, Ontario. 141 REFERENCES SCOTT, W.B., and S.N. TIBBO. 1968. Food and feeding habits of swordfish, Xiphias gladius, in the western North Atlantic. J. Fish. Res. Board Can. 25:903-919. TEMPLEMAN, W., and R.L. HAEDRICH. 1966. Distributions and comparisons of Centrolophus niger (Gmelin) and Centrolophus britannicus Giinther (Cen- trolophidae) from the North Atlantic. J. Fish. Res. Board Can. 23:1161-1185. Maturation and Fecundity of Swordfish, Xiphias gladius, from Hawaiian Waters JAMES H. UCHIYAMA and RICHARD S. SHOMURA! ABSTRACT Sixteen swordfish, Xiphias gladius, ovaries ranging in weight from 39 to 20,000 g were examined. Fish size ranged from 47 to 246 kg. Based on the occurrence of ripe ovaries, spawning in Hawaiian waters was estimated to extend from April through July. The developmental stages of ova are described; the most advanced ova examined averaged 1.6 mm in diameter. The distribution of ova diameters within an ovary was found to be heterogeneous. Fecundity was estimated for eight swordfish. Some variability in fecundity was noted; a positive curvilinear relationship of increase in fecundity with increase in fish size was evident. Best estimates suggest that an 80 kg swordfish has 3.0 million ova (early ripe or ripe stages) and a 200 kg swordfish has 6.2 million ova. The occurrence in Hawaiian waters of mature swordfish, Xiphias gladius, with ovaries in ad- vanced stages of maturation has been observed in the past by longline fishermen and other members of the fishing industry. However, precise informa- tion of the spawning period and the fecundity of swordfish from the Hawaiian Islands area is lack- ing. Although swordfish are not taken in large num- bers by the longline fishery (Fig. 1), the absence of studies on swordfish has been due principally to difficulty in obtaining adequate data. The large ovaries of swordfish along with ovaries of other bill- fishes and tunas are commercially valuable and considered as a food delicacy in Hawaii. Thus, in order to prevent damage to the gonads, the auction firms handling the sale of swordfish do not permit the fish to be cut open prior to sale. Since fish are often butchered outside of the auction area, we were unable to obtain the needed information on sex and maturity. Although very little data on swordfish were available during our six years of sampling (1961-66), we were able to collect 16 Ovaries covering all seasons of the year. These samples and related data on swordfish were consid- ered adequate to permit us to make a preliminary assessment of spawning and fecundity of swordfish; the results are presented in this paper. ‘ Southwest Fisheries Center, Honolulu Laboratory, National Marine Fisheries Service, NOAA, Honolulu, HI 96812. 142 OCCURRENCE OF SWORDFISH IN HAWAIIAN WATERS Swordfish are taken exclusively with longline fishing gear in Hawaiian waters. The swordfish catch landed by the Hawaiian fishery is very small; the total annual catch did not exceed 120 fish during the six years of sampling (Fig. 1). Since fishing for NUMBER A - ~ a r HH dH JFMAMJJASOND J FMAMJJASONOJFMAMJJASONOJFMAMJJASONOJFMAMJJASOND JFMAMJJASOND, ——1961- —1962 —1963— 1964 1965, 1966- 200 SaEEREREnEREREREREEEOnaen| 3S = = x= 2 z <= w = JFMAMJJASOND JFMAMJJASOND JFMAMJJASOND JFMAMJJASOND JFMAMJJASOND JFMAMJJASOND SSS SSS = 1963 - 1964 1965 1966: Figure 1.—Monthly landings of swordfish (upper panel) and average size of fish (lower panel) from 1961 to 1966. swordfish with longline gear is more successful dur- ing the night than day (Ueyanagi, 1974), the low catches may only be reflecting the fact that the Hawaiian fishery operates principally during day- light hours. Day fishing is carried out to maximize the catch of tunas and species of billfishes other than swordfish. Figure 1 shows the monthly landings of swordfish for the period 1961-66. Although catches are small, there is a pronounced increase in landings during the summer months with the peak occurring in July. The increase is due to an increase in availability and not to an increase in fishing effort, since Yoshida (1974) showed that the catch rates (catch per trip) for blue marlin, Makaira nigricans, and striped mar- lin, Tetrapterus audax, in the Hawaiian longline fishery parallel the monthly landings, thus suggest- ing that the monthly catch data could be used as a general measure of availability. The average size of swordfish also shows a peak during the summer period. As it will be discussed later, the increase in average size accompanied by the appearance of females in late stages of matura- tion may be related to a spawning migration. MATERIALS AND METHODS The 16 swordfish ovaries were collected at the Honolulu fish markets between June 1964 and May 1967 (Table 1). Since longline-caught fish are kept refrigerated with crushed ice, the ovaries were kept in an unfrozen condition until collected. In the laboratory, excess connective tissue was removed from the external surfaces of the ovaries. The ovaries were weighed to the nearest gram and preserved in 10% Formalin. Detailed microscopic examination of the ovaries was undertaken only after the ovarian material had been thoroughly pre- served, and shrinkage had stabilized. Generally, ova diameter measurements were taken after preserva- tion had exceeded 6 mo. For the maturation study, a small sample was extracted from the ovary with a cork borer and 100 randomly selected ova were measured to obtain mean diameter values for the most developed ova size group. Individual ova diameters obtained were not necessarily the maximum diameters. We fol- lowed the method developed by Yuen (1955) for measuring bigeye tuna ova and used by Otsu and Table 1.—Summary of swordfish data used in maturation and fecundity study. Paired ovary weights Most advanced mode Date Fish Fresh Preserved in Mean Number Fecundity Sample of size 10% Formalin Maturity! diameter measured (millions Gonad? number landing (kg) (g) (g) (mm) of ova) index BB-1 6/24/64 187.2 11,566 10,033 ER, RS _— 1.019 153 2.24 6.18 BB-2 6/25/64 121.5 10,205 6,805 RP 1.205 257 3.84 8.40 BB-3 6/25/64 204.1 19,958 19,609 RP, RS 1.364 172 6.18 9.78 BB-4 7/ 3/64 156.5 9,389 ( 8,267)8 ER 0.986 228 4.80 6.00 BB-5 7/ 3/64 142.4 8,373 (_ 7,332)8 ER 0.923 403 9.38 5.88 BB-6 7/ 6/64 246.3 1,542 1,430 ED, RS_ 0.101 100 —_— 0.63 BB-7 7/17/64 86.6 184 169 IM 0.060 100 — 0.22 BB-8 11/26/65 _—-:17.7 39 39 IM 0.057 100 — 0.22 BB-9 1/ 2/66 68.0 508 490 ED 0.141 100 — 0.75 BB-10 = 1/25/67 —- 90.3 390 415 ED 0.154 100 — 0.43 BB-11 2/24/67 46.7 (Damaged) BB-12 4/ 5/67 54.4 172 174 ED 0.107 100 — 0.32 BB-13 4/13/67 76.6 163 176 IM (poorly preserved) 0.21 BB-14 4/27/67 121.5 8,164 (_7,187)8 RP 1.438* 113 3.73 6.72 BB-15 5/22/67 83.0 4,327 4,200 ER 0.990 306 il 5.21 BB-16 5/28/67 202.7 = 8,255 8.197 ER, RS __ 1.033 296 6.54 4.07 ' Key: IM - Immature ED - Early developing ER - Early ripe RP - Ripe RS - Residual eggs present ? Gonad index is percentage of fresh ovary weight to fish size. 3 Weight estimated from fresh-preserved con- version given in Figure 2. 4 Ova diameters of fresh (non-preserved) sam- ples placed in sea water averaged 1.571 mm. 143 Uchida (1959) for albacore. The measurement was the random diameter located parallel to the ruled lines marked on the measuring dish. For ovaries in the early ripe or ripe stages, ova diameters were taken to obtain the mean diameter of the most advanced mode. A small sample of the ovarian tissue was extracted with a cork borer from the area near the lumen of the posterior region of the right ovary. Excess liquid was first blotted out and the sample weighed on an analytical balance. All ova in the most advanced stage were measured and counted, the latter to obtain fecundity estimates. Weights of preserved ovaries from four fish were not recorded (Table 1). Since three of these samples were in the early ripe or ripe stages of maturity and could be used for fecundity estimates, we computed a conversion factor to correct for shrinkage due to preservation. Figure 2 shows the regression of fresh whole ovary weight on preserved (10% Formalin) ovary weight. The regression computed on the trans- formed data (log ,) shows a very good fit for the 12 sets of data. The equation was used to estimate the preserved weights of the three samples (Table 1). Sample BB-3 (Table 1) was used to test for homogeneity of ova diameters within a pair of ovaries. A cork borer (14.29 mm diameter) was used to obtain a core sample which extended from the outer surface of the ovary to the centrally-located lumen. The core was divided into an outer layer, a central layer located next to the lumen, and a middle rr) DN «s, —— ={| fo ¥ = 0.155 +0.969 Ln x LOGe PRESERVED (10% FORMALIN) WHOLE OVARY WEIGHT (gms) fe) ! 2 3 4 5 6 7 8 9 10 i LOGe FRESH WHOLE OVARY WEIGHT (gms) Figure 2.—Relationship of fresh ovary weight to pre- served (10% Formalin) ovary weight for swordfish. layer. Separate cores were taken from the anterior, middle, and posterior region of both ovaries, thus providing a total of 18 subsamples. Ripe ova were teased from each sample and 200 randomly-selected ova were measured DEVELOPMENTAL STAGES OF OVA An examination of the physical appearance of ova from swordfish showed that the ova could be clas- sified easily into several developmental stages which were not dependent on ova diameters. The stages are described as follows: . Primordial Ova Ova are transparent, ovoid in shape, and diame- ters range from 0.01 to 0.05 mm. Primordial ova are present in all ovaries. 2. Early Developing Ova Ova are still transparent and ovoid in shape; diameters range from approximately 0.06 to 0.24 mm. A chorion membrane has developed around the ovum and an opaque yolk-like material has begun to be deposited within the ovum. . Developing Ova (Figure 3A) Ova are completely opaque, more wedge-shaped than ovoid, and diameters range between 0.16 to 0.96 mm. The chorion is stretched and not visible in this stage. 4. Advanced Developing Ova (Figure 3B) Ova are ovoid and diameters range from 0.47 to 1.20 mm. Ova have a translucent margin, a fertil- ization membrane, and a round yolk. . Early Ripe Ova (Figure 3C) Ova diameters range from 0.60 to 1.20 mm. The yolk material is translucent and oil globules have begun to form. . Ripe Ova (Figure 3D) Ova are transparent and with oil globules. Diameters range from 0.80 to 1.66 mm. . Residual Ova Ova in this stage show signs of degeneration. Ova are thin-walled and translucent and have shrunken and measure approximately 0.80 mm in diameter. — Ww n ON ~) HETEROGENEITY OF OVA DIAMETERS The distribution of ova diameters in sample BB-3 was examined critically to test for heterogeneity. A chi-square test of the normality of the size frequency distribution of ova diameters for the 18 samples (Ap- pendix Table 1) showed significant differences for | : | ‘ : Figure 3.—Developmental stages of swordfish ova. A. Developing. B. Advanced developing. C. Early ripe. D. Ripe. 145 sample RMO (P = 0.01) and samples RMC and RPO (P =0.05). Ananalysis of variance for one-way design was used to test for homogeneity (Table 2). The null hypothesis that the distribution of ripe ova was homogeneous throughout the ovaries was re- jected (P<0.05; F ratio of 5.2821; d.f. 17 and 3,582). An examination of the means showed no general trends with the different sections of each ovary and locations within each section. The lack of homo- geneity in ova has also been demonstrated for bigeye tuna (Yuen, 1955) and albacore (Otsu and Uchida, 1959). A further evidence of heterogeneity was indicated in a comparison of ripe and early ripe ova. Table 3 shows the number of ripe and early ripe ova from the nine locations sampled from the right ovary. The ratio of ripe to early ripe ova ranged from 0.5576 to 2.6792. Three samples, RPC, RPM, and RMC, had almost identical ratios; but no consistent pattern was evident. SPAWNING Swordfish with ovaries in a ripe condition have been reported in the Mediterranean Sea off Sicily (Sella, 1911), in the Gulf Stream off Cuba (LaMonte, 1944) and in the western Pacific Ocean in the seas adjacent to Minami Tori Shima located at long. 156°E, lat. 25°17’N (Nakamura et al., 1951). Yabe et al. (1959) reported the occurrence of swordfish with ripe ovaries in the North Pacific Ocean in waters extending from the Subtropical Convergence to the equator and in the South Pacific in the Coral Sea and near the Fiji Islands. Yabe et al. (1959) also reported on the occurrence of seven ripe ovaries taken from swordfish caught in the Indian Ocean. The appearance in April through July (Table 1) of large swordfish in the late stages of maturity suggests that the movement into coastal waters of the Hawaiian archipelago may be part of a spawning migration. Matsumoto and Kazama (1974) identified swordfish larvae from plankton hauls taken in Hawaiian waters, thus confirming the indirect evi- dence based on our ovary maturation study. Cavaliere (1962) reported that embryos start to form in eggs with diameters between 1.60 and 1.80 mm. In our samples the mean ova diameters of the most advanced modes of the preserved material were 1.20 mm for sample BB-2, 1.36 mm for BB-3, and 1.44 mm for BB-14. Ova from sample BB-14, which had been immersed in seawater prior to preservation, had a mean diameter of 1.57 mm. Since the gonad Table 2.—Test of ova diameters from selected locations from right and left ovary of sample BB-3; analysis of vari- ance for one-way design. Mean micrometer Standard Mean Treatment! Sample size units deviation (mm) RAC 200 69.38500 6.133913 1.4223 RAM 200 69.93500 6.480799 1.4336 RAO 200 68.41500 7.441750 1.4025 RMC 200 67.51500 7.646705 1.3840 RMM 200 67.51000 7.418561 1.3839 RMO 200 67.93500 8.098684 1.3926 RPC 200 69.44500 7.664900 1.4236 RPM 200 69.94000 7.077913 1.4337 RPO 200 72.00000 6.587639 1.4760 LAC 200 68.96500 6.347853 1.4137 LAM 200 69.97000 6.592144 1.4343 LAO 200 70.19000 6.296197 1.4388 LMC 200 69.86000 5.928416 1.4229 LMM 200 68.19500 6.523783 1.3979 LMO 200 69.48500 6.331683 1.4244 1ePE 200 69.41000 5.725012 1.4229 LPM 200 69.40500 6.811972 1.4336 LPO 200 69.80000 5.445941 1.4309 Analysis of Variance Sum of squares d.f. Mean square F ratio Between groups 4072.5925 17 = 239.5643 5.2821 Within groups 162458.1074 3582 45.3540 Total 166530.6992 3599 ' RAC ~- Right anterior center RAM - Right anterior mid-layer RAO ~- Right anterior outer layer RMC ~- Right middle region center RMM - Right middle region mid-layer RMO ~- Right middle region outer layer RPC - Right posterior region center RPM - Right posterior region mid-layer RPO ~- Right posterior region outer layer LAC - Left anterior center LAM ~- Left anterior mid-layer LAO - Left anterior outer layer LMC - Left middle region center LMM - Left middle region mid-layer LMO - Left middle region outer layer LPC - Left posterior region center LPM -- Left posterior region mid-layer LPO ~- Left posterior region outer layer index measures gonad size relative to fish size, it is not surprising to find that the highest gonad indices occurred during the apparent spawning period April to July (Table 1). Since residual ova are remains from previous spawning (Yuen and June, 1957), all ovaries from our collection were examined for these ova. Re- 146 Table 3.—Ratio of numbers of ripe to early ripe ova. Number of early Number of Sample? ripe ova Tipe ova Ratio index RAC 170 212 1.2470 RAM 195 291 1.4923 RAO 220 256 1.1636 RMC 303 269 -8877 RMM 319 212 -6645 RMO 477 266 -5576 RPC 194 172 -8865 RPM 280 248 8857 RPO 106 284 2.6792 ' RAC - Right anterior center RAM - Right anterior mid-layer RAO - Right anterior outer layer RMC - Right middle region center RMM - Right middle region mid-layer RMO - Right middle region outer layer RPC - Right posterior region center RPM - Right posterior region mid-layer RPO - Right posterior region outer layer sidual ova were only evident in some of the samples collected in May, June, and July (Table 1). Although Y abe, et al. (1959), assumed that the ripe ova (modal diameter 1.2 mm to 1.6 mm) were spawned at one time, partial spawning of swordfish cannot be dis- counted as sample BB-3, which was judged ripe, also had residual ova. It is interesting to note that Sella (1911) reported that the swordfish ovary contracts after spawning and remains compact and firm. This differs from tunas, which tend to be noticeably flaccid (Yuen, 1955). Sample BB-6, which was collected in July, appeared to confirm the general condition described for swordfish. Although this ovary was in an early stage of maturity and was firm and compact, it also contained residual ova, suggesting recent spawning. No early ripe or ripe ovaries were collected from August to April. To some extent this feature may only reflect absence of mature fish, since nearly all of the swordfish taken during this period were small in size (Table 1) and indicative of immature fish. FECUNDITY Fecundity estimates are presented in Table 1 and shown in Figure 4. Since homogeneity tests showed significant differences in the distribution of ova diameters within a single pair of ovaries, the esti- mates should be considered only as rough approxi- mations of the true fecundity of the swordfish. It FECUNDITY (MILLIONS OF OVA ) 140 180 FISH SIZE (kg) 120 160 Figure 4.—Fecundity estimates for swordfish from Hawai- ian waters. should be pointed out, however, that while nonran- dom distribution of ova diameters within an ovary may contribute to errors in fecundity estimates, other factors are equally important in making the current methods of measuring fecundity difficult. Other factors include inaccurate estimates of the true ovary weight due to varying amounts of connec- tive tissue left on the ovary surface, and more impor- tant, the varying amount of excess fluids (primarily the preservative) removed from the ovary during the “‘draining’’ period. Possibly the most important error factor may be related to the point in maturation when the fecundity estimates are made. In species with multimodal frequency distributions of ova diameters (Yuen, 1955; Otsu and Uchida, 1959), the most advanced modal size group has fewer ova than the modal groups to the left (smaller ova). This sug- gests that resorption of some ova is taking place. Thus, the final number of ova extruded during spawning is less than the number with which the modal group started when the mode first differen- tiated from the primordial ova stock. Fecundity estimates of the eight swordfish with early ripe or ripe ova are shown in Figure 4. As indicated in an earlier section, fecundity estimates from three of the fish were based on preserved ovary weights which were estimated from fresh-preserved ovary weight relationship. In Figure 4 two of the eight points appear to be displaced a considerable distance from the general curvilinear relationship of increasing fecundity with increasing fish size. Sam- ple BB-5 with an estimated 914 million ova is consid- erably higher than the general trend, while sample BB-1 with 2.2 million ova is on the lower side. 147 From our limited fecundity data, and considering the error factors described above, we estimate the fecundity of swordfish to range from 3.0 million ova for a fish weighing 80 kg to 6.2 million ova for a fish weighing 200 kg. Yabe et al. (1959) estimated the fecundity of a 186 cm (orbit to fork) swordfish to be between 3 and 4 million ripe ova. LITERATURE CITED CAVALIERE, A. 1962. Studi sulla biologica e pesca di Xiphias gladius L. Nota I. Boll. Pesca Pisc. Idrobiol. 17, 11:123-143. LAMONTE, F. 1944. Note on breeding grounds of blue marlin and sword- fish off Cuba. Copeia 1944:258. NAKAMURA, H., T. KAMIMURA, Y. YABUTA, A. SUDA, S. UEYANAGI, S. KIKAWA, M. HONMA, M. YUKINAWA, and S. MORIKAWA. 1951. Notes on the life-history of the sword-fish, Xiphias gladius Linnaeus. [In Engl.] Jap. J. Ichthyol. 1:264-271. MATSUMOTO, W. M., and T. K. KAZAMA. 1974. Occurrence of young billfishes in the central Pacific Ocean. Jn R. S. Shomura and F. Williams (editors), Pro- ceedings of the International Billfish Symposium, Kailua-Kona, Hawaii, 9-12 August 1972, Part 2. Review and Contributed Papers. U.S. Dep. Commer., NOAA Tech. Rep. NMFS SSRF-675, p. 238-251. OTSU, T., and R. N. UCHIDA. 1959. Sexual maturity and spawning of albacore in the Pacific Ocean. U.S. Fish Wildl. Serv., Fish. Bull. 59:287-305. SELLA, M. 1911. Contributo alla conoscenza della riproduzione e dello sviluppo del pesca-spada (Xiphias gladius L.) Mem. R. Com. Talassografia Italiano 2:1-16. UEYANAGL, S. 1974. A review of the world commercial fisheries for bill- fishes. Jn R. S. Shomura and F. Williams (editors), Pro- ceedings of the International Billfish Symposium, Kailua-Kona, Hawaii, 9-12 August 1972, Part 2. Review and Contributed Papers. U.S. Dep. Commer., NOAA Tech. Rep. NMFS SSRF-675, p. 1-11. YABE, H., S. UEYANAGI, S. KIKAWA, and H. WATANABE. 1959. Study on the life-history of the sword-fish, Xiphias gladius Linnaeus. [In Jap., Engl. summ.] Rep. Nankai Reg. Fish. Res. Lab. 10:107-150. YOSHIDA, H. O. 1974. Landings of billfishes in the Hawaiian longline fishery. Jn R. S. Shomura and F. Williams (editors), Pro- ceedings of the International Billfish Symposium, Kailua-Kona, Hawaii, 9-12 August 1972, Part 2. Review and Contributed Papers. U.S. Dep. Commer., NOAA Tech. Rep. NMFS SSRF-675, p. 297-301. YUEN, H. S. H. 1955. Maturity and fecundity of bigeye tuna in the Pacific. U.S. Wildl. Serv., Spec. Sci. Rep. Fish. 150, 30 p. YUEN, H. S. H., and F. C. JUNE. 1957. Yellowfin tuna spawning in the central equatorial Pacific. U.S. Fish. Wildl. Serv., Fish. Bull. 57:251-264. APPENDIX: Table 1.—Frequency distribution of ripe ova diameters from selected parts of a swordfish ovary (sample BB-3). Ocular micrometer Milli- Subsamples! units meters RAC RAM RAO RMC RMM RMO RPC RPM RPO LAC LAM LAO LMC LMM LMO LPC LPM LPO 87 1.7835 1 — 1 2 0— — 2 — - = = =—- = 86 1.7630 — —_— —_— —_— — _— 1 —_— —_— —- — — — 85 1.7425 — 20 — ~— = — 1 -—-— ~~ ~~ = 1 — = 84 1.7220 - -—- — = 2 1 1 2 — 1 —- ~ = 83 1.7018 — — 1 1 — 2 3 2 5 1 1 1 — 82 1.6810 — 3 1 —_— 2 4 3 2 4 1 1 4 1 —_ 81 1.6605 2 2 1 z) 2 3 2 4 2 3 3 2 3 2} 80 1.6400 5 2 4 4 4 4 3 7 10 4 3 6 5 2 79 1.6195 4 4 6 3 4 3 2 2 7 _ 5) 2 2 4 78 1.5990 4 6 6 6 3 Zi 1Ob Mit 9 fT 5 8 5 2 77 1.5785 4 6 9 1 8 2 13 14 12 5 8 8 10 4 76 1.5580 10 14 8 8 5 12 9 3 14 7 9 10 7 10 75 1.5375 Cul Syaie 2 8 10 5 13 a 1] 6 3 10 5 74 1.5170 7 11 11 7 5 4 7 11 8 7 17 12 17 10 73 1.4965 11 13 7 10 12 7 10 13 20 16 20 15 13 11 72 1.4760 21 13 11 1] 13 10 10 10 15 11 14 17 10 18 71 1.4555 18 16 6 4 7 8 9 6 7 16 16 18 11 9 70 1.4350 14 15 10 8 15 10 ih 11 12 12 15 16 16 13 69 1.4145 10 5 11 6 i U 8 8 10 Ul 11 4 9 14 68 1.3940 20 11 9 15 16 q] 12 11 12 17 8 10 20 12 67 1.3735 14 11 19 11 8 13 1] 8 14 12 5 12 12 10 66 1.3530 6 9 10 13 11 9 17 8 3 10 8 4 8 9 65 1.3325 7 6 12 11 10 16 6 q/ 3 5 a 12 9 8 64 1.3120 4 8 5 7 2 5 7 9 4 8 2 6 3 12 63 1229.15 10 4 8 13 6 9 4 9 4 6 7 6 4 9 62 1.2710 3 9 5 4 6 5 6 7 I 12 8 5 4 10 61 1.2505 3 3 3 3 6 8 9 2 2 4 5 4 4 3 60 1.2300 5 4 1 5 I} 4 6 4 3 5 4 2 9 6 59 1.2095 2 3 2 4 5 3 2 5) 2 1 —_— 1 1 1 58 1.1890 2 — 4 5 6 3 3 4 — 3 0 = 6 3 1 57 1.1685 1 2 6 6 5 9 2 2 1 2 2 _— —_ 4 56 1.1480 1 1 2 2 3 — — 2 1 1 2 — — 1 55 1.1275 2 l 1 2 6 4 1 i 1 1 _— 1 2 2 54 1.1070 — 1 4 5 3 _ 1 — 1 1 1 3 1 1 53 1.0865 2, _ 2 2 1 1 1 l — 1 1 — — 1 52 1.0660 1 l 3 3 1 3 3 — 1 —-— —- — = 1 51 1.0455 —_ 1 — 1 — 2 1 —_— 2 2 2 I — 1 50 1.0250 — — 2 — a — 1 -- = 1 2 — — 1 49 1.0045 — — — — — — a — i — 1 — —_— _— 48 -9840 1 —_— — 1 1 — i 1 —_— — —_— — 1 y) 47 9635 — — _— — 1 1 — 1 _ _ — — — = 46 9430 — — 1 1 1 2 _— — — — — — _— _— 45 9225 — _ — — _— 1 1 _ _— — _ —_ _ —_ 44 9020 — 1 = SS —- - =| =| S| FE Fe eS ' RAC - Right anterior center LAC - Left anterior center RAM - Right anterior mid-layer LAM - Left anterior mid-layer RAO - Right anterior outer layer LAO - Left anterior outer layer RMC - Right middle region center LMC - Left middle region center RMM .- Right middle region mid-layer LMM - Left middle region mid-layer RMO - Right middle region outer layer LMO - Left middle region outer layer RPC - Right posterior region center LPC - Left posterior region center RPM - Right posterior region mid-layer LPM ~- Left posterior region mid-layer RPO - Right posterior region outer layer LPO ~- Left posterior region outer layer Ew wow || _ _ Sesto | NMWWWaAN KN _ NOWeK NW fe _ OWNON DOR Re Ree Ye —a— a aor f — = | ss aS: | SSeS De eK OWMOMNDAeE NAD lw | Occurrence, Morphology, and Parasitism of Gastric Ulcers in Blue Marlin, Makaira nigricans, and Black Marlin, Makaira indica, from Hawaii ROBERT T. B. IVERSEN! and RICHARD R. KELLEY? ABSTRACT Gastric ulcers were found in 10 of 114 blue marlin, Makaira nigricans, and 2 of 3 black marlin, M. indica, examined from 1967 to 1969 at the Hawaiian International Billfish Tournament. Parasitic nematodes were found imbedded in the base of ulcers in one blue marlin and two black marlin. The gross and microscopic morphology of the ulcers is given and possible causes are discussed. The most likely cause is either mechanical injury or parasites, or the effect of both in the same stomach. The existence of gastric ulcers in man and other mammals, including marine mammals (Geraci and Gerstmann, 1966) is well known. The existence of gastric ulcers in fish was first noted by Aliverdiev and Radzhabov (1968), Evans and Wares (1972), and Iversen and Kelley (in press). We here report addi- tional details on the occurrence, morphology, parasitism, and possible causes of gastric ulcers in blue marlin, Makaira nigricans, and black marlin, M. indica, landed from 1967 to 1969 during the an- nual Hawaiian International Billfish Tournament. METHODS One hundred seventeen marlin were captured dur- ing daytime trolling in surface or near surface waters just off the west coast of the Island of Hawaii. Each billfish tournament included 5 fishing days during either July or August. Fishing commenced each day at 0800, but the catch was usually not brought to the weighing station until after 1700 when fishing ended, so there often was a lengthy interval between cap- ture and examination of the stomach. After being weighed by tournament officials, each fish was measured, sexed, and examined for stomach con- tents. Specimens were not refrigerated prior to ex- amination. The estimated maximum interval be- * Southwest Region, National Marine Fisheries Service, NOAA, c/o Southwest Fisheries Center, Honolulu Laboratory, National Marine Fisheries Service, Honolulu, HI 96812. * Department ot Pathology, Queen’s Medical Center, Hon- olulu, HI 96813. 149 tween capture and examination of marlin contain- ing ulcers was 7.5 h. Histological preparations were by standard paraffin imbedding with hematoxylin and eosin stain. RESULTS Ten of 114 blue marlin and 2 of 3 black marlin contained ulcers, for a combined occurrence of 10.3%. Sex, weight, and length for each marlin with ulcers are given in Table 1. Two black marlin and seven blue marlin stomachs with ulcers were pre- served in 10% Formalin® for laboratory examina- tion. Two of the black marlin and one of the blue marlin stomachs examined in the laboratory con- tained ulcers invaded by small parasitic nematodes, Contracaecum sp.?, a roundworm which has been reported in billfish stomachs from widely separated localities (Wallace and Wallace, 1942; Morrow, 1952). The following brief comments on gross and mi- croscopic morphology are based upon examination of one of the black marlin stomachs which contained numerous ulcers, both with and without nematedes. The comments are also descriptive of ulcers in blue marlin. Gross Findings The ulcers were either separate or in clusters * Reference to commercial products does not imply endorse- ment by the National Marine Fisheries Service. Table 1.—Record of marlins with gastric ulcers captured at the Hawaiian International Billfish Tournament, 1967-69. Estimated elapsed time, Fork capture to Date captured Species Sex Wt. length’ examination® kg cm h 4 July, 1967 Makaira nigricans F 151.5 303.4 S25 6 July, 1967 M 141.0 290.0 385 29 July, 1968 M 67.6 224.9 6.5 29 July, 1968 Makaira indica F 83.9 240.9 kes 31 July, 1968 F 86.2 256.1 15 1 Aug., 1968 Makaira nigricans M 92.5 256.8 5.0 2 Aug., 1968 M 67.6 230.3 3.0 2 Aug., 1968 Ee 18951931557 6.5 2 Aug., 1968 F 102.0 270.3 TES 21 Aug., 1969 M 102.0 268.2 6.5 21 Aug., 1969 M 66.7 236.4 6.5 22 Aug., 1969 M 68.5 235.3 7.0 1 Tip of snout to center of distal edge of caudal fin. throughout the stomach (Fig. 1). They were noncan- cerous. Edges were indurated and raised slightly from the surrounding surface. Ulcer margins were rather sharply demarcated. The bases were covered with a dark brown shaggy material and had an indu- rated feel. Light gray nematodes 5-7 mm in length and less than 0.5 mm in diameter were imbedded in the bases of four ulcers in this stomach (Fig. 2). The bases of the ulcers were very indurated and the indu- ration extended through the wall of the specimen. Microscopic Findings The base of this ulcer was covered by granulation tissue with a dense proliferation of fibroblasts and an infiltration of acute and chronic inflammatory cells (Fig. 3). The fibrous proliferation extended through the entire wall and obliterated the usual muscular layers. Remnants of the nematodes were identified throughout the ulcer base. Generally, there was an intense granulomatosis inflammatory reaction sur- rounding the parasite. This consisted of inflamma- tory cells and histiocytes. In some instances the in- flammatory reaction had subsided and only laminar layers of fibrous tissue remained (Fig. 4). Figure 1.—Multiple ulcerations varying from 3 to 13 mm scattered over the mucosal surface of a stomach from a female black marlin. Weight of marlin 86.2 kg; fork length 256.1 cm. 150 ne Se ee Figure 2.—Closeup view of same black marlin stomach showing nematodes burrowing in base of ulcer. td DA ’ Figure 3.—Microscopic section of base of ulcer from same black marlin showing extensive fibrosis and subacute inflammatory response surrounding portions of nematode sectioned in two areas (H & E stain, 25x). 151 Figure 4.—Microscopic section of base of ulcer from same black marlin showing ex- tenSive fibrosis laminated around old nematodal debris (H & E stain, 25x). DISCUSSION Several possible causes of the ulcers may be con- sidered. They are (1) mechanical injury to the stomach lining from sharply pointed food items, (2) parasites, (3) digestive processes due to gastric se- cretions between the time of death and time of exam- ination, and (4) excess gastric secretions. The most likely cause is either mechanical injury or parasites, or the effect of both in the same stomach. Blue and black marlins feed heavily on fish, many having sharply pointed projections. Ex- amples are the dorsal spines of skipjack tuna, Kat- suwonus pelamis, and yellowfin tuna, Thunnus al- bacares. Both of these tunas are commonly eaten by marlins. We have recovered a sliver of bonelike ma- terial from beneath the epithelium of the stomach of a marlin captured during a billfish tournament. Other examples are the spiny puffers, Diodontidae, which sometimes occur in marlin stomachs. Spiny puffer remains were found in one of the stomachs contain- ing an ulcer, and it is possible that multiple punctures of the stomach lining could occur after engulfment of such food. Multiple punctures could also be caused by engulfment of prey items with sharp spines during successive feedings. This could explain instances of 152 multiple ulcers in some of the marlin stomachs. For example, the black marlin stomach shown in Figure 1 had six ulcers wider than 10 mm and over 50 smal- ler ulcers less than 10 mm wide. Evans and Wares (1972) reported finding gastric ulcers in 14% of 563 striped marlin, Tetrapturus audax, and 22% of 151 sailfish, Istiophorus platypterus, examined in Mexican and southern California waters in 1968. They did not, however, cite the presence of nematodes, either in stomachs with or without ulcers. They also suggest spines of prey species may have caused the ulcers. In those ulcers containing nematodes, it is uncer- tain if the ulcers were caused by the nematodes, or if the nematodes took advantage of the ulcer and bur- rowed inward. Other workers have found a high percentage occurrence of nematodes in marlin stomachs without citing the presence of ulcers. Wal- lace and Wallace (1942) found Contracaecum incur- vum in 60 of 86 stomachs of white marlin, T. albidus, captured off Ocean City, Maryland. Morrow (1952) reported finding C. incurvum in each of 53 stomachs of striped marlin, M. mitsukurii ( = T. audax), from New Zealand. If this nematode causes ulcers, its association with ulcers should be common, which is not the case, according to pub- lished reports. This implies mechanical injury is the most likely cause, with the ulcers being further ag- gravated in those stomachs containing parasitic nematodes. Digestive action by gastric secretions after death is another possibility, but it seems highly unlikely the large size of some ulcers could develop even during the lengthy interval between capture and preserva- tion of the stomach. For example, the 83.9 kg black marlin captured in 1968 had one ulcer that was 40 mm long, 27 mm wide, and 10 mm deep (measurements after preservation in Formalin). In addition, 30 nematodes and necrotic tissue were present in the pit of this ulcer. High concentrations of free circulating histamine might possibly cause ulcers by increasing gastric acid secretions. It is known that histamine has an ulcerogenic effect on warm-blooded animals (Hay et al., 1942). Geraci and Gerstmann (1966) have sug- gested that histamine from a diet of inadequately preserved fish caused gastric ulcers in a captive bottle-nosed dolphin, Tursiops truncatus. Fresh fish contain negligible amounts of histamine, but under conditions of inadequate preservation, decarboxyla- tion results in the formation of histamine from his- tidine (Geraci and Gerstmann, 1966). Since marlin feed on fresh fish, it seems unlikely much of the prey’s histidine may find its way into the marlin’s blood stream as histamine. Further, the effect of histamine on gastric secretions in teleosts is un- known. In the spiny dogfish shark, Squalus acan- thias, perfusion of isolated gastric mucosa with his- tamine resulted in an increased secretion of acid | to 1.5 times the amount secreted by isolated dogfish gastric mucosa not perfused with histamine, but high concentrations of histamine were required (Hogben, 1967). Increased gastric secretion from behaviorally in- duced stress conceivably might have an ulcerogenic effect on marlin. The average sex ratio of blue marlin landed during Hawaiian International Billfish Tour- naments from 1962 to 1972 has been 3.3 males:1 female, while blue marlin caught by commercial fish- ing in subsurface waters in Hawaii have an almost 1:1 sex ratio (Strasburg, 1970). It has been suggested the unequal sex ratio of blue marlin caught during the tournaments may indicate a spawning aggregation. Such an aggregation conceivably might be stress- 153 inducing but this is highly speculative and probably unrelated to ulcer occurrence. Adequate data on the sex ratio of black marlin are not available. ACKNOWLEDGMENTS We gratefully acknowledge the cooperation of anglers and officials of the annual Hawaiian Interna- tional Billfish Tournament in making these speci- mens available for examination. We thank Ross F. Nigrelli, Donald W. Strasburg, and Heeny S. H. Yuen for reading the manuscript and for offering advice. LITERATURE CITED ALIVERDIEV, A. A., and M. R. RADZHABOV. 1968. K voprosu etiologii iazvennoi bolezin sudaka (Pre- dvarit. soobshchenie) (The etiology of ulcers of the stomach of the pike-perch: Preliminary communication.) Sb. naukn. rabot. Dagestansk. n.-i. vet. in-t. 2:114-117. (Abstr. 71180, Ref. ZH. Biol. 1969.) [Not seen.] EVANS, D. H., and P. G. WARES. 1972. Food habits of striped marlin and sailfish off Mexico and southern California. U.S. Fish Wildl. Serv., Res. Rep. 76, 10 p. GERACI, J. R., and K. E. GERSTMANN. 1966. Relationship of dietary histamine to gastric ulcers in the dolphin. J. Am. Vet. Med. Assoc. 149:884-890. HAY, L. J., R. L. VARCO, C. F. CODE, and O. H. WAGENSTEEN. 1942. The experimental production of gastric and duodenal ulcers in laboratory animals by the intramuscular injection of histamine in beeswax. Surg. Gynecol. Obst. 75:170-182. HOGBEN, C. A. M. 1967. Response of the isolated dogfish gastric mucosa to histamine. Proc. Soc. Exp. Biol. Med. 124:890-893. IVERSEN, R. T. B., and R. R. KELLEY. In press. Stomach ulcers in blue marlin (Makaira nigricans) and black marlin (Makaira indica) in Hawaiian waters. (Abstr.) Proc. Hawaiian Acad. Sci., 44th Annu. Meet., 1968-1969. MORROW, J. E. 1952. Food of the striped marlin, Makaira mitsukurii, from New Zealand. Copeia 1952:143-145. STRASBURG, D. W. 1970. Areporton the billfishes of the central Pacific Ocean. Bull. Mar. Sci. 20:575-604. WALLACE, D. H., and E. M. WALLACE. 1942. Observations on the feeding habits of the white mar- lin, Tetrapturus albidus Poey. Publ. Chesapeake Biol. Lab., Board Nat. Resour., Dep. Res. Educ., Solomons Island, Md. 50:3-10. Mercury in Swordfish and Other Pelagic Species from the Western Atlantic Ocean JAMES S. BECKETT! and H. C. FREEMAN? ABSTRACT Total mercury determinations have been carried out on at least one tissue from each of 210 swordfish, 40 specimens of 15 other pelagic species, and 235 individuals of 12 species taken from swordfish stomachs. Total mercury levels of swordfish white muscle tissue ranged from 0.05 to 4.90 parts per million (ppm) (mean 1.15 ppm) total mercury. Mercury levels were broadly related to fish size with the larger fish having higher levels but the relationship varied with time and area of capture. Males tended to have higher levels than females. The mercury levels of different tissues (red muscle, liver, kidney, heart, brain, gill, vertebral disc, and stomach) are given. The differences in the levels in certain tissues from fish taken in different areas suggest greater physiological activity of mercury in fish from the southern area. The significance of mercury in swordfish prey species is discussed. As a result of the sudden awareness of the pres- ence of mercury in swordfish (Xiphias gladius) and the almost immediate cessation of the fishery in early 1971, there were very few specimens with good biological and capture data available for analysis. In order to investigate heavy metal contamination in fishes, the Fisheries Research Board of Canada conducted a series of longlining cruises (Table 1) in the area extending from the southern Caribbean to the Grand Banks. The results of the first five cruises from 1 August 1971 to March 1972 are presented here. METHODS Regular swordfish longlines were used, the gen- eral gear configuration being Mustad 3142/0 hooks? on 3-fathom gangings, attached to the mainline at 20-fathom intervals. The mainline was held near the surface by buoys, on 5-fathom lines, attached to it every 100 fathoms. The gear was set in the evening and hauled back after dawn. Mackerel (Scomber scombrus) and occasional herring (Clupea haren- gus) were used as bait. ‘Fisheries Research Board of Canada, Biological Station, St. Andrews, New Brunswick, Canada. *Fisheries Research Board of Canada, Halifax Laboratory, Halifax, Nova Scotia, Canada. ’Reference to trade names does not imply endorsement by the National Marine Fisheries Service, NOAA. 154 Sex, state of maturity, morphometric and stomach content data were recorded for each swordfish boated. Representative food items were retained for mercury analysis. A number of tissue samples were removed from the swordfish and frozen for future analysis; tissue included: dorsal muscle (posterior), red muscle, abdominal wall muscle, heart, kidney, liver, gill, stomach, and vertebrae. Not all tissues were obtained for each fish. Other pelagic species landed were treated in vari- ous ways, some being sampled in detail, as for swordfish, while only dorsal muscle tissue was re- tained from others. Total mercury content was de- termined, in duplicate, on homogenates of each tis- sue by the semiautomated flameless atomic absorp- tion method of Armstrong and Uthe (1971) using a Perkin-Elmer model 403 atomic absorption spec- trophotometer equipped with a Perkin-Elmer model 56 recorder. Sampling was performed by a Techni- con Sampler II with a timer cam (30 samples per hour), sample wash ratio of 1:2, and a Technicon proportioning pump. RESULTS At least one tissue type has been analyzed from 210 swordfish (X. gladius), and from 37 individuals of 13 other pelagic species (1 bluefin tuna, Thunnus thynnus; 1 white marlin, Tetrapturus albidus; | escolar, Lepidocybium flavobrunneum; 3 dolphin, Table 1.—Longline cruises yielding swordfish for mercury analysis. Designation Date Number of Area Number of sets swordfish sampled HS 104 23-27 July 1971 5 Georges 14 DG 1 23-31 Aug 1971 8 Banquereau and 63 Grand Banks DG 2 09-17 Sept 1971 6 Browns to Banquereau 73 DG 3 14-27 Oct 1971 6 Georges to Cape Charles 43 BIO 72-004 01-22 Mar 1971 8 Bahamas and Caribbean 17 FG 6 27-May-8 June 1972 12 Cape Hatteras to Sable 17 RG 17-28 June 1972 10 Cape Hatteras and Georges 16 FG 8 6-19 July 1972 14 South of Browns to Banquereau 4 FG 9 26 July-9 Aug 1972 13 South of Grand Banks 3 FG 10 14-31 Aug 1972 10 East of Grand Banks 4 Coryphaena hippurus; 1 long nose lancetfish, Alepisaurus ferox; 14 blue sharks, Prionace glauca; 4 sickle sharks, Carcharhinus falciformis; 1 dusky shark, C. obscurus; 2 tiger sharks, Galeocerdo cuvieri; 2 scalloped hammerhead sharks, Sphyrna lewini; 2 mako sharks, Isurus oxyrinchus; 1 por- beagle shark, Lamna nasus; and 4 unspecified lam- nid sharks). The size range of the organisms and total mercury content of the dorsal muscle are shown in Table 2. Similar data for a single white shark (Carcharodon carcharias) obtained in an otter trawl, and two basking sharks (Cetorhinus maximus) taken from herring weirs in Passamaquoddy Bay, are also included in Table 2. In addition, mercury determina- tions were completed on 235 specimens of 12 species of fish taken from swordfish stomachs (Table 3). DISCUSSION The areas of capture can be divided into five parts; four divisions of the longline fishery and a fifth area to the south; the latter includes the Bahamas and eastern Caribbean. The captures in the northern di- visions were made during four cruises in the period July-October 1971. Captures from the southern area were made in February and March 1972. The divi- sions of the swordfish longline fishery are shown in Figure 1, while the dates of fishing are given in Table bi: Mercury levels found in swordfish tissue (dorsal muscle) were tabulated (Table 4) by localities and months. 155 Variation With Size The slopes, correlation coefficients and ‘‘t’’ val- ues obtained by application of the least squares fit for linear relation between fork length (x) and mer- cury content (y) are included in Table 4. It is appar- ent that there is a relationship, although considera- ble scatter exists. ” Table 2.—Total mercury level (ppm) of dorsal muscle tissue of selected pelagic species. Species Number Fork length Total mercury sampled (range) Mean Range (cm) (ppm) (ppm) Swordfish 210 74-247 1.15 0.05-4.90 Bluefin tuna 1 172 0.80 — White marlin 1 187 1.34 — Escolar 1 89 0.62 = Dolphin 3 88-115 0.86 0.32-1.22 Lancet fish 1 122 0.08 — Blue shark 14 69-190 0.70 0.40-1.17 Sickle shark 4 101-199 1.43 0.75-3.28 Dusky shark 1 120.1 2.08 — Tiger shark 2 137-236 0.83 0.68-0.98 Scalloped hammerhead shark 2 147-177 3.64 2.40-4.89 Mako shark 2 151-159 1.16 1.02-1.30 Porbeagle shark 1 116 0.55 — Mackerel shark 4 78-234 2.08 0.62-5.43 White shark 1 449 18.85 — Basking shark 2 382 0.08 0.03-0.14 Table 3.—Total mercury (ppm) in food species taken from stomachs of swordfish. Specimens Number Total mercury content Dietary importance sampled (ppm) Stromateidae (Butterfishes) Centrolophus niger (Black Ruff) 2 0.14 Occasional Stomiatidae (Scaled dragonfishes) Stomias boa (Boa dragonfish) 1 0.17 Occasional Myctophidae (Lanternfishes) 15 0.24 Important Paralepididae (Barracudinas) 36 0.20 Important Alepisauridae (Lancetfishes) Alepisaurus ferox (Longnose lancetfish) 2 0.41 Occasional Nemichthyidae (Snipe eels) Nemichthys scolopaceus (Slender snipe eels) 4 0.24 Occasional Gadidae (Cods) Merluccius bilinearis (Silver hake) 9 0.17 Locally important Carangidae (Jacks) 2 0.13 Occasional Scombridae (Mackerels) Scomber scombrus (Atlantic mackerel) 73 0.17 Bait Scorpaenidae (Scorpionfishes) Sebastes marinus (Redfish) 14 0.34 Locally important Monacanthidiae (Filefishes) 14 0.21 Occasional Cephalopoda (Squids) Ilex illecebrosus (Shortfinned squids) 63 0.31 Important Variation Between Sexes Female swordfish predominated in all catches from the northern parts of the range in the northwest Atlantic; only 21 of the 193 fish caught in areas B, C, D, and E were males. Mercury levels of fish of the same size from the same area may differ between the sexes. The data for areas A, D, and E, which were the areas where most of the males were caught, are given in Table 5. The results are conflicting: In area aes % Galt of a g S Lewresce —® Newfoundland L y f ( Ya a t Canada 4, Pod AS Grand Bants Sable ts. Bk UISHAME MAAS D t\V/ Hydrogropher WS 2 4 B C Hatteros A-- includes Caribbean me Figure 1.—Map of Northwest Atlantic Ocean showing areas of capture of swordfish used for mercury analysis. 156 A, males, on the average, contained higher levels than females of the same size; in area D, similar levels were found in both sexes for fish of the same average size; and in area E, similar levels were found but the males, on average, were smaller. Should the tendency for higher levels in males be confirmed, this may be due to a slower growth rate, and hence greater age at a given size. Owing to the small sample sizes and the low rela- tive numbers of males except in area A, the sexes were combined for subsequent discussion. Variation with Time and Area The localities sampled are listed chronologically in Table 4, with area C (Georges Bank) repeated since it was fished twice (July and October). Gener- ally, the average total mercury content of the dorsal muscle decreased with time. The only exception was the average for fish from area E (Grand Banks), which was higher (1.42 ppm) than the average in any other northern area (B, C, or D) either earlier or later. The average size of fish from area E, at 167 cm fork length, was, however, considerably larger than that of fish from these other areas (Table 4). Evi- dence that the decrease in average mercury content was a result of time rather than locality (decreasing to the westward) is suggested by the reduction of the Table 4.—Comparison of total mercury content (ppm) of dorsal muscle tissue with size of swordfish caught in different areas. Size Total mercury content “2 SOY, Number of Average Range Average Range Correlation testing Fishing area Month swordfish (cm) (cm) (ppm) (ppm) Slope coefficient slope A. Caribbean- Feb- 17 159 = (109-240) 2.02 (0.36-4.90) 0.00215 0.568 2.580* Bahamas March C. Georges July 14 147, (_ 85-188) 1.17 (0.16-2.08) 0.001312 0.777 4.275** Bank E. Grand Aug 39 167. — (128-212) 1.42 (0.71-2.10) 0.007412 0.599 4 /32t2 Banks D. Sable- Sept 94 145 ( 74-247) 1.07 (0.05-2.72) 0.006816 0.406 4.305** Banquereau C. Georges Oct 25 142. ( 99-183) 0.88 (0.19-1.88) 0.005626 0.368 129377, B. Cape Oct 21 129 ( 78-188) 0.57 (0.05-1.35) 0.009671 0.823 6231544 Hatteras- Hydrographer Canyon *Significant at 0.90 level. **Significant at 0.95 level. average mercury level in area C between the July and October samples for fish of essentially the same size. Swordfish from area B (Cape Hatteras to Hy- drographer Canyon) were considerably smaller (av- erage 129 cm) than fish taken in other areas. This size difference may also account, at least in part, for the lowest average mercury level (0.57 ppm) being encountered in area B. Variation of Mercury Content Between Tissues The total mercury content of the various tissues sampled from swordfish is shown in Table 6. Gener- ally red muscle, liver, kidney, and heart contained higher levels of total mercury than dorsal muscle while other tissues contained less. The mercury content of the various tissues was examined by area and time of capture in the same manner as for the dorsal muscle samples. When these data were expressed (Table 7) as proportion (percentages) of the dorsal muscle values, most tis- sues showed relatively little variation, with the ex- ception of the liver and kidney values. The mercury content of the latter two tissues ranged from about the same as that of the dorsal muscle (areas C and D) to approximately twice that level (areas A, B, and E). The elevated average levels in kidney and liver from area E were due to one large fish which had a mercury content in these tissues of over three times 157 that of the dorsal muscle. The elevated levels for areas A and B are shown by all specimens, however, and appear to be characteristic. These elevated levels suggest that mercury was either being more rapidly eliminated from the body in areas A and B, or likely was being taken up in greater quantities from the environment. The average mercury level (Table 4) in dorsal muscle from area A was considerably higher (2.02 ppm) than from any other area, but that from area B was the lowest (0.857 ppm). However, it has already been noted that area B fish were much smaller than fish from other areas and Table 4 also indicates that the relation between size and mercury content (slope of regression line 0.009671) in area B was steeper than elsewhere, so that larger fish would presumably have shown high levels similar to those from area A. Mercury Levels in Food Items Food organisms collected from swordfish stomachs and analyzed for the total mercury content (Table 3) all show fairly high values (average 0.14-0.3 ppm for each species); although the possible con- tribution of mercury from the digestive juices of the predator cannot be ignored. The relatively high mer- cury content of redfish (0.34 ppm) may be of signifi- cance in considering the high values in the liver and kidney obtained from one large swordfish (212 cm) caught in area E (Grand Banks). Redfish form a Table 5.—Comparison of total mercury content (ppm) of dorsal muscle tissue from swordfish by sex and by area. Fork length Total mercury content “t” for Area Month Numberand Mean Range Mean Range Slope Correlation testing sex (cm) (cm) (ppm) (ppm) coefficient slope E. Grand Banks Aug 7 Males 152. (136-178) 1.39 (0.7-1.9) 0.02398 0.757 2.589* Grand Banks Aug 32 Females 170 = (128-212) 1.42 (0.9-2.1) 0.006749 0.637 4.604** D. Sable- Sept 9 Males 148 = (127-170) 1.09 (0.7-1.4) 0.007265 0.543 1.713 Banquereau Sable- Sept 65 Females 144 (74-247) 1.07 (0.1-1.8) 0.007269 0.417 3.649** Banquereau A. Bahamas- Feb- 9 Males 149 (109-163) 2.21 (0.36-4.90) 0.094809 0.543 1.709 Caribbean Mar Bahamas- Feb- 5 Females 146 =(110-224) 1.58 (0.41-4.36) 0.03370 0.990 12.136** Caribbean Mar *Significant at 0.90 level. **Significant at 0.95 level. major proportion of the diet of swordfish in that particular area (Scott and Tibbo, 1974). This is espe- cially true for fish larger than 160 cm, possibly be- cause such fish feed deeper (Beckett, 1973). Squid, the other relatively mercury-rich food species, also appear to be more important in the diet of swordfish from area E than from elsewhere, with the exception of the adjacent part of area D (Scott and Tibbo, 1974). Mercury analyses are currently not available for stomach contents of swordfish taken from area A, while for area B data are insufficient for comment. Other Species The mercury content of the dorsal muscle of 12 other pelagic species (Table 2) was all high with the Table 6.—Total mercury content (ppm) of selected sword- fish tissues. Number of Total mercury content Tissue samples Average Range (ppm) (ppm) Dorsal muscle 210 NGS) 0.05-4.90 Red muscle 32 1.59 0.12-5.36 Abdominal muscle 80 1.10 0.05-4.85 Liver 33 3.00 0.07-15.10 Kidney 33 1.91 0.09-8.63 Heart 33 1.64 0.17-5.38 Brain 22 0.90 0.11-1.54 Gill 43 0.43 0.11-1.54 Vertebral disc 43 0.20 0.03-0.57 Stomach 107 0.50 0.06-1.23 Table 7.—Total mercury content (ppm) of selected tissues as percentage of total mercury content of the dorsal muscle tissues. (Number of samples given in parentheses.) A B (e D E Tissue Caribbean- Cape Hatteras- Georges Browns to Grand Banks Bahamas Hudson Canyon July Oct. Banquereau Red muscle 117 (14) 139 (3) 117 ( 3) 104 (2) 112 ( 7) 106 ( 3) Abdominal muscle 87 (15) 87 (3) 94 ( 4) 96 (3) 77 (25) 74 (30) Liver 263 (15) 240 (2) 105 ( 3) 86 (2) 106 ( 7) 175 ( 3) Kidney 145 (15) 148 (3) 82 ( 3) 58 (2) 98 ( 7) 208 ( 3) Heart 116 (15) 154 (3) 114 ( 3) 97 (2) 130 ( 7) 117 ( 3) Brain 62 (IL) 58 (3) _ a — — Gill 33 (15) 58 (1) 29 (15) 20 (2) 30 ( 7) 28 ( 3) Vertebral disc 14 (15) 15 (2) 18 (14) 5 (2) 14 ( 7) 12 ( 3) Stomach — — 52 (10) — 43 (64) 40 (34) 158 maximum 18.85 ppm for a white shark. The only exceptions were a lancet fish (0.08 ppm) and two basking sharks (0.03 and 0.14 ppm). The data are too few for any deductions other than that the general tendency is for higher levels to occur in species that eat large fish, although, on this basis, the dusky and scalloped hammerhead sharks may be excessively high. These shark specimens were captured in area A, however, and may be showing elevated levels similar to swordfish from that area. CONCLUSIONS The decrease in mercury content of dorsal muscle with time for swordfish in the northern part of their range, and the high levels in excretory tissues from fish in the southern warmer areas, suggest that the uptake of mercury may change during the annual migratory cycle. Further data on food species, how- ever, are necessary to confirm whether swordfish are ingesting higher levels of mercury in their prey during the winter when they occur in the Caribbean and southern Gulf Stream, and losing the mercury when they migrate to the north during the summer. The high mercury levels in the kidney and liver tis- sues of one fish taken from area E (Grand Banks), which contrast with the general trend in the northern areas, may indicate heavy feeding on redfish, a species with a high mercury content. SUMMARY Total mercury contents were determined for at least one tissue from each of 210 swordfish, 40 indi- viduals of 15 other pelagic species and for the body musculature of 235 individuals of 12 prey species. Dorsal muscle mercury levels for swordfish of 74-247 cm fork length ranged from 0.05 to 4.90 ppm (mean 1.15 ppm). Mercury content of the dorsal muscle of swordfish showed a linear relationship with size. The mercury content of the dorsal muscle may vary with sex, males having a higher level, possibly being correlated with the older age for a given fish size. 159 The mercury content appeared to decrease with time for fish in the northern part of the range. Mercury levels in red muscle, liver, kidney, and heart exceeded those of the dorsal musculature, while those in other tissues were less. Mercury uptake and/or excretion was higher in the Caribbean and Gulf Stream, south of Cape Hat- teras, than to the north and east. Some increase in mercury levels may occur near the Grand Banks where major food items (redfish and squid) were relatively rich in this element. The mercury content of other pelagic species ex- amined ranged from 0.03 ppm for a basking shark to 18.85 ppm in a white shark. ACKNOWLEDGMENTS Thanks are due to members of the Fish Contami- nants Division of the Halifax Laboratory for carrying out the mercury analyses, and to the staff at the Biological Station, St. Andrews, especially to those members of the Pelagic Programme who collected much of the material, and to members of the Statisti- cal Group for their assistance in examining the data. Grateful acknowledgement is made of the use of the Canadian Hydrographic vessel Dawson for the Caribbean cruise. LITERATURE CITED ARMSTRONG, F. A. J., and J. F. UTHE. 1971. Semiautomated determination of mercury in animal tissue. At. Absorpt. Newsl. 10:101-103. BECKETT, J. S. 1974. Biology of swordfish, Xiphias gladius L. in the Northwest Atlantic Ocean. Jn Richard S. Shomura and Francis Williams (editors), Proceedings of the Interna- tional Billfish Symposium, Kailua-Kona, Hawaii, 9-12 August 1972, Part 2. Review and Contributed Papers. U.S. Dep. Commer. NOAA Tech. Rep. NMFS SSRF-675, p. 103-106. SCOTT, W. B., and S. N. TIBBO. 1974. Food and feeding habits of swordfish (Xiphias gladius Linnaeus) in the Northwest Atlantic Ocean. Jn Richard S. Shomura and Francis Williams (editors), Proceedings of the International Billfish Symposium, Kailua-Kona, Hawaii, 9-12 August 1972, Part 2. Review and Contrib- uted Papers. U.S. Dep. Commer. NOAA Tech. Rep. NMFS SSRF-675, p. 138-141. Mercury in Several Species of Billfishes Taken Off Hawaii and Southern California RICHARD S. SHOMURA! and WILLIAM L. CRAIG? ABSTRACT The results of analyses of the mercury content of 37 blue marlin, Makaira nigricans, 56 striped marlin, Tetrapturus audax, and 3 swordfish, Xiphias gladius, are presented. The levels of total mercury found in white muscle of blue marlin caught in Hawaiian waters ranged from 0.19 ppm to 7.86 ppm; fish specimens ranged in total weight from 96 pounds (43.5 kg) to 906 pounds (410.9 kg). A trend of increasing mercury level with increasing size of fish was noted. The mercury content in the livers of 26 blue marlin specimens examined ranged from 0.13 ppm to 29.55 ppm; there was no apparent trend noted between mercury content in the liver and size of fish. Striped marlin from Hawaii and southern California showed a range of mercury levels in white muscle of 0.09-1.09 ppm for the 14 Hawaii samples examined and 0.03-2.1 ppm for the 42 California samples examined. The range in size of fish was 56-139 pounds (25.4-63.0 kg) and 109-231 pounds (49.4-104.8 kg) for the Hawaii and California samples, respectively. From the wide spread of mercury levels encountered in striped marlin, a trend of mercury level with size of fish could not be easily detected. Livers of nine specimens from the Hawaii catch were analyzed; mercury levels ranged from 0.05 ppm to 1.53 ppm. Three swordfish weighing 6 pounds (2.7 kg), 100 pounds (45.4 kg), and an estimated 500 pounds (226.8 kg) contained mercury levels in white muscle of 0.04, 1.71, and 2.10 ppm, respectively. In early December 1970 the news media stunned the nation, particularly the fishing industry, with the release of stories that some canned tuna and swordfish steaks contained mercury in excess of the Food and Drug Administration (FDA) interim guideline of 0.5 ppm (Bernstein, 1970; Fleming, 1970; Los Angeles Times, 1970; Coffey, 1971). Prior to State University of New York Professor Bruce McDuffie’s discovery that mercury levels in two cans of tuna exceeded the FDA guideline, the problem of mercury in fishes was thought to be localized and confined to freshwater fish species. The high levels of mercury in freshwater fishes were attributed to dumping of waste products into waterways. A review of the literature undertaken at the time of the announcement of mercury in tuna and sword- ‘Tiburon Fisheries Laboratory, National Marine Fisheries Service, NOAA, Tiburon, CA 94920. *California Department of Fish and Game, Long Beach, CA 90802; present address: Southwest Region, National Marine Fisheries Service, NOAA, Terminal Island, CA 90731. 160 fish revealed a wealth of information related to mercury and its toxic properties; references were primarily of incidents occurring in Japan and Swe- den. Despite the wide range of available informa- tion, there was a conspicuous lack of data related to mercury levels in living organisms in the marine biosphere. For this reason the National Marine Fisheries Service embarked upon an extensive program early in 1971 to collect tissue samples of marine and estuarine fishes and invertebrates for analysis of mercury and other heavy metals (Com- mercial Fisheries Review, 1971). Primarily because of their recreational value, the California Department of Fish and Game collected samples of striped marlin, Tetrapturus audax, and albacore, Thunnus alalunga, for mercury analysis during the summer of 1971. Our purpose in this paper is to provide the results of analysis for total mercury content in samples of striped marlin, blue marlin, Makaira nigricans, and swordfish, Xiphias gladius. We will simply present these data with some brief comments of the more notable features. It is not our intention to review the instances of mercury poisoning, the legal as- pects of the mercury guideline, nor the issue of natural versus pollution-caused heavy metal con- tamination. MATERIALS AND METHODS Of the 56 striped marlin sampled, 42 were caught off southern California, while the remaining 14 were from Hawaiian waters. All of the 37 blue marlin and 2 of the 3 swordfish were from Hawaiian waters. One small (2.7 kg) swordfish was caught with long- line gear in the central equatorial Pacific. The rec- reational fishery provided all the California sam- ples; data and tissues were collected either at the weighing facilities of the Balboa Angling Club or the Marlin Club of San Diego. The Hawaii samples consisted of fish caught by the commercial longline fleet and by the troll sport fishery. The commercial catch was sampled at the Honolulu fish auction, while the sport catch was from fish caught during the 1971 Hawaiian International Billfish Tourna- ment held at Kailua-Kona, Hawaii. With the exception of the small swordfish which was preserved in Formalin,* all of the samples were collected from fresh, unfrozen specimens. From % to 1 pound (0.23 to 0.45 kg) of white muscle tissue was excised from each fish. In the California striped marlin samples, the tissue was removed from the dorsal loin above the left pectoral fin. Nearly all the Hawaii samples came from near the caudal area because this portion is usually dis- carded after a buyer has purchased the fish from the auction market. In all cases the tissue sample was cleaned of skin and bone, wrapped in inert aluminum foil, labeled, and then frozen as soon as possible. After the samples had been collected they were packed in Dry Ice and shipped to the analyti- cal laboratories by air. Liver tissue from 4 Hawaiian striped marlin and 26 blue marlin also were collected for comparative analysis. The Hawaii samples were analyzed at a National Marine Fisheries Service Laboratory while those from California were done by a Department of Fish and Game Laboratory. In 17 of the California striped marlin sampled, muscle tissues were sent to each of the analytical laboratories. *Reference to trade names does not imply endorsement by the National Marine Fisheries Service, NOAA. Similar laboratory procedures were followed in all cases; this consisting basically of the semiautomatic, cold vapor, atomic absorption technique (Uthe, Armstrong, and Stainton, 1970). This technique requires a lengthy process of ho- mogenizing, digesting, etc., prior to obtaining a total mercury value from the atomic absorption ap- paratus. RESULTS Striped Marlin Our study covered a relatively wide size range for this species; the smallest weighed 56 pounds (25.4 kg) and the largest 231.5 pounds (105.0 kg). Gener- ally, the larger striped marlin were from southern California while the smaller fish were from Hawaii. Total mercury values averaged 0.8 ppm and ranged from a low of 0.03 ppm in a 135-pound (61.2 kg) fish to 2.1 ppm in a 231.5 pound (105.0 kg) fish, the largest sampled (Fig. 1). Seventy percent or 42 fish exceeded the FDA guideline of 0.5 ppm. A trend line calculated for these data indicates a general in- crease in total mercury with increasing size of fish. However, as Figure 1 indicates, the increase Is er- ratic and impossible to predict. While the largest fish resulted in the highest mercury content, it is well to note that the second largest, a 218 pounder (99.0 kg), was tested at 0.29 ppm, a figure well below the FDA guideline. 24 T T T ae TELE T T Sali 22b 4 e og © SOUTHERN CALIFORNIA SAMPLES + 3 x HAWAI| SAMPLES w heb HAWAI! SAMPLES (N=14) 4 = é 9=-0.5045 + 0.010762 a ° Pn 4 = i Lae 4 = o ALL (n=56) & $=0.244 +0.003485x 5 hee ° 4 oO ima ¥ 1.0 4 a = x J & sr w ° 8 Ao re $. CALIF. SAMPLES (N=42)} - $=0.393 + 0.00253 x wu 4 4 i | =} = 2 4 ° (a 1 sp fe Sei n \ ° 25 50 75 100 125 150 175 200225 POUNDS i ' 1 1 I I ! t I t ° 10 20 30 40 50 60 70 80 90 10010 kg FISH SIZE Figure 1.—Relationship between total mercury (ppm) in white muscle tissue and size of fish of striped marlin from southern California and Hawaiian waters. Table 1.—Comparison of mercury levels in striped marlin tissues analyzed by two laboratories. Laboratory Laboratory no. | no. 2 Mean HG 0.77 ppm 0.84 ppm Standard deviation 0.35 0.50 >0.5 ppm 15 fish 12 fish <0.5 ppm 2 fish 5 fish High value 1.0 24 Low value 0.4 0.1 Some of this variability may be due to analytical technique for it should be remembered that differ- ent laboratories provided the analytical data. While analytical methods were being developed there ap- peared to be considerable variability between laboratories, although the reproducibility within a given laboratory was very high. Our data from the 17 samples that were run by two of the laboratories tend to bear out this feature. Extreme values were repeatable within both laboratories, but there were differences between the laboratories. These differ- ences are illustrated best in tabular form (Table 1). Looking at individual samples, one laboratory was not consistently high or low and no two values for a particular fish were identical. In several in- stances one laboratory reported mercury values over the FDA guideline while the other was below. Again, neither laboratory was consistent in this re- spect. The livers from four Hawaiian fish also were analyzed for total mercury. Mercury levels of the three small fish (81, 83, and 96 pounds—36.7, 37.6, and 43.5 kg, respectively) were all less than 0.2 ppm, but the single large fish of 139 pounds (63.0 kg) had a value of 1.54 ppm. Blue Marlin The mercury data for all the blue marlin were from fish taken in Hawaiian waters. Total mercury levels of white muscle tissue in this species ranged from 0.7 ppm to 7.86 ppm in fish weighing between 96 and 906 pounds (43.5 and 410.9 kg). The results are presented in Figure 2. When compared to striped marlin, the mercury levels in blue marlin were much higher. Only 7 of the 37 blue marlin tested had levels less than 1.0 ppm, while for striped marlin 45 of the 56 fish tested were below that level. The highest value recorded for blue marlin was 7.86 ppm which, surprisingly, was not from the largest specimen, but from a fish weighing 211 pounds (95.7 kg). As with striped marlin, the range in mercury level for blue marlin is large. However, there appeared to be an indication of a positive relationship between mercury level and fish size when a regression was fitted to the data (Fig. 2). Again, this relationship shows a wide variation around the regression. We would find it difficult to use these data for predict- ing mercury content in a given specimen. For comparative purposes we have plotted the linear regression presented by Rivers, Pearson, and Schultz (1972) for blue marlin samples from Hawaiian waters. Since many of the same fish tested by Rivers et al. (1972) were included in our study, we can only conclude that the marked differ- ence in regressions is due to differences in analyti- cal technique. There is agreement, however, that the levels of mercury in blue marlin are consider- ably higher than the FDA guideline. The livers of 26 blue marlin also were analyzed for total mercury. The values ranged from 0.13 ppm RIVERS, et ol (1972) %= 1.43374 + 0.0128 x \ HAWAII! SAMPLES (N=37) = 1.1097 + 0.005805 x WHITE MUSCLE TISSUE TOTAL MERCURY (PPM, WET- WEIGHT ) ™ x ' 2 e Ms xy °. § l 1 u i 1 ° 400 200 300 400 500 600 700 1 I i i I 1 i ° 50 100 150 200 250 300 FISH SIZE Figure 2.—Relationship between total mercury (ppm) in white muscle tissue and size of fish of blue marlin from Hawaiian waters. (o denotes Rivers et al. (1972) samples, x denotes our samples.) = T T T Fie T lane == 3oL . 1 al 4 f Z = Lt ==4 So wu x = it 5 | : x - Lo 4 = x a a ~ sr = 3 | By x 2 xx 4 6 4 5 = SE 4 c S = She z 4 [ x 3 xx rx | x 2 x 4 x x x 1 gx 4 lp ered: x ° x 1 1 L —————— le 1 L ° 100 200 300 400 500 600 700 800 900 POUNDS ' ! ! I 1 t 1 i] 1 1 ° 50 100 150 200 250 300 350 400 kg FISH SIZE Figure 3.—Relationship between total mercury (ppm) in liver tissue and size of fish of blue marlin from Hawaiian waters. to a phenomenal 29.55 ppm (Fig. 3). Based upon published literature the latter may be the highest level of total mercury reported for any fish. Coinci- dentally, this high value was from the same 211-pound (95.7-kg) fish whose white muscle tissue contained the extremely high level of 7.86 ppm total mercury. There does not, however, appear to be a consistent relationship between total mercury con- tent in livers and the content in white muscle tis- sues. Swordfish Only the muscle tissue from three swordfish was analyzed for total mercury. The mercury level in a juvenile swordfish weighing 6 pounds (2.7 kg), which had been preserved in Formalin, measured 0.04 ppm. The analyses from two other fresh specimens from Hawaiian waters weighing 100 pounds (45.4 kg) and 500 pounds (226.8 kg), were 1.7 and 2.1 ppm total mercury, respectively. DISCUSSION Results of this investigation may be considered a contribution to the fund of information pertaining to this controversial subject. Confirmation of high mercury levels in billfishes and the relationship of mercury to size, sex, or other variables will require further study. LITERATURE CITED BERNSTEIN, H. 1970. Tuna firms facing crisis on mercury. Excessive levels cripple sales in U.S. Los Angeles Times, December 18, Vol. XC, Part I, p. 1, 30, columns 3-8. COFFEY, B.T. 1971. Mercury posing major crisis; swordfish industry har- dest hit. Natl. Fisherman, March, p. 3A, 13A, 19A. COMMERCIAL FISHERIES REVIEW. 1971. NMFS studies heavy-metal contamination of fish. Commer. Fish. Rev. 33(6):3-4. FLEMING, L.B. 1970. Unsafe mercury level reported in swordfish. Found in frozen food sold in U.S., says scientist who detected tainted tuna. Los Angeles Times, December 18, Vol. XC, Part I,.p. 30, column 1. LOS ANGELES TIMES. 1970. High mercury level found in canned tuna. Los Angeles Times, December 13, Vol. XC, Sec. C, p. 8. RIVERS, J.B., J.E. PEARSON, and C.D. SHULTZ. 1972. Total and organic mercury in marine fish. Bull. Envi- ron. Contam. Toxicol. 8:257-266. UTHE, J.F., F.A.J. ARMSTRONG, and M.P. STAINTON. 1970. Mercury determination in fish samples by wet diges- tion and flameless atomic absorption spectrophotometry. J. Fish. Res. Board Can. 27:805-811. 163 Section 3. Distribution . Summer Concentration of White Marlin, Tetrapturus albidus, West of the Strait of Gibraltar’ C. RICHARD ROBINS? ABSTRACT Examination of fish catches landed in August 1961 at various ports in southern Portugal and the adjacent coast of Spain demonstrated that the white marlin, Tetrapturus albidus, concentrated in these waters during this month. The coincident absence of white marlin in landings at Sicily make it likely that the species does not enter the Mediterranean in any numbers at least at this season. August concentrations of white marlin elsewhere in the Atlantic are discussed along with the implica- tions of the coincident timing of them on population structure of the species. Morphometric data are presented on 57 specimens from this eastern Atlantic population to facilitate future comparison with specimens from elsewhere in the range of the species. In 1961, the writer visited Italy, Spain, and Por- tugal to study 95 istiophorid fishes that had been purchased from fishermen and stored in large freez- ers for that purpose. Arrangements for the purchase and storage of the fish had been made by the late John K. Howard during his travels through the re- gion in the summers of 1960 and 1961. The main goal of the project was to determine the status of the Mediterranean spearfish, Tetrapturus belone Rafinesque, and that result was published by Robins and de Sylva (1963) based on thirty-five specimens, all from Sicily. Equal attention, how- ever, was devoted to other istiophorids. Of the re- maining 60 specimens, 57 were white marlin, Tet- rapturus albidus Poey, an amphi-Atlantic species whose biology remains poorly known. Except for three specimens, one caught 14 Sep- tember, and two on 5 October, all specimens were collected between 31 July and 24 August 1961 off the southern coasts of Portugal and Spain and off northwestern Morocco. The 1961 season was said to be especially good off Olhao, Portugal. The species is said to be especially common in this re- gion in August, which coincides with the time of ! Contribution No. 1710 from the Rosenstiel School of Marine and Atmospheric Science. University of Miami. > Rosenstiel School of Marine and Atmospheric Science. University of Miami, Miami, FL 33149. 164 postspawning feeding concentrations elsewhere. Between Ocean City, Maryland and Atlantic City, New Jersey, the peak season extends from the end of the second week of July to about the last week in August (de Sylva and Davis, 1963: tables 2 and 3); off the Mississippi Delta, in the Gulf of Mexico a large concentration occurs in July and August (Gibbs, 1958: Figure 1); and off La Guaira, Ven- ezuela, the peak is also in August but large numbers occur through September and into October (Pérez de Armas, 1959, and unpublished data courtesy of Donald P. de Sylva). With four, nearly simultaneous, postspawning concentrations known to occur in distant parts of the Atlantic Ocean, the population structure of this giant pelagic predator obviously is complex. Mather (1968) discusses the results of a tagging program in the western Atlantic which had then yielded 34 returns out of nearly 4,000 tagged fish. He comments on the three western Atlantic popula- tions which he terms the northwestern Atlantic stock, Gulf stock, and Venezuelan stock. To facili- tate morphometric comparison of the populations, and because these large fishes are not preserved and thus are unavailable to future researchers, the data obtained from the eastern Atlantic specimens are presented here following the format of Robins and de Sylva (1961, 1963). Certain aspects of the biology are discussed. STATUS OF THE WHITE MARLIN IN THE EASTERN ATLANTIC Robins and de Sylva (1963: 89-90) reviewed the synonymy of Tetrapturus belone and (p. 97) noted that all literature records of that species from out- side the Mediterranean Sea either apply to other species or are without a verifiable basis. Sassi (1846) recorded the first white marlin from the east- ern Atlantic (from the Mediterranean Sea) under the name Tetrapturus belone. Canestrini (1861) recognized that Sassi’s specimen in Genoa was not belone and made it the type of his well described and illustrated species, Tetrapturus lessonae. This description, in fact, postdates Poey’s (1860) de- scription of Tetrapturus albidus from Cuba, by on- ly one year. Since then Eastern Atlantic records of albidus occur under Makaira nigricans, Tetrapturus belone, T. lessonae in various combinations. Rob- ins and de Sylva (1961: 97) referred the record of T. belone by Legendre (1928) to albidus and discuss other probable records. Gongalves (1942: 54-55) was perhaps the first to suggest that albidus occurred in Portugal’s waters. La Monte (1955: 331-332 first referred /essonae to the synonymy of albidus and from this date albidus begins to appear in records of Eastern Atlantic and Mediterranean specimens (Robins and de Sylva, 1961; Tortonese, 1961; Rodriguez-Roda and Howard, 1962). Ueyanagi et al. (1970) summarize longline catches of white marlin throughout the tropical and temper- ate Atlantic. A review of the literature relative to T. albidus and other ‘‘istiophorids’’ in the eastern At- lantic is being prepared by Donald P. de Sylva. MATERIAL EXAMINED The 57 specimens identified as Tetrapturus al- bidus were given field numbers coded EATL-1 to 57. Those numbered EATL-1 to 38 were studied at Olhao, Portugal, the remaining 19 at Cadiz, Spain. Most of the Cadiz specimens were caught on fishing lines operated by swordfish fishermen in the Strait of Gibraltar and to the west along the southern coast of Portugal and Spain and the northern coast of Morocco. Six were caught in tuna traps (almad- rabas) near Huelva, Spain (west of Gibraltar) and La Linea, Spain (immediately east of Gibraltar in the Alboran Sea). The locations and dates of cap- ture of numbers 39-57 were noted by Rodriguez- Roda and Howard (1961: table 1) and these dataare . not repeated here. 165 The 38 specimens examined at Olhao, Portugal, were mostly captured in traps (including Liv- ramento, Medo dos Cascas, and Barril) off Tavira, Portugal as follows (all dates in 1961): 6 Aug.: EATL-1, 4, 8, 13, 14, 15, 16, 19, 31, 35, 37; 10 Aug.: EATL-S; 12 Aug.: EATL-17; 17 Aug.: EATL-6, 7, 10; ll; 2ivAugt BAM -25 5926228522 Aug.: EATL-22, 36, 38; 23 Aug.: EATL-21, 23, 24, 29, 32, 34. The remaining eight fish were hooked as follows: off Tavira, Portugal; 31 July: EATL-3, 33; 1 Aug.: EATL-9; 16 Aug.: EATL-2. Off Olhao, Portugal: 9 Aug.: EATL-18; 10 Aug.: EATL-20. Off Fuzeta (near Olhao), Portugal: 21 Aug.: EATL-30; 23 Aug.: EATL-27. Frank J. Mather, III has brought to my attention two white marlin, 2,000 cm and 1,725 cm body length, which were caught 6 October 1969, by long- line off Cadiz, Spain. Sex was not determined. The larger was estimated to weigh 65-70 kg. Although not examined by the present writer, these records are included here for sake of completeness of in- formation on the subject. Explanation of the Tables The format of Appendix Tables 1 and 2 follows that of Robins and de Sylva (1961, 1963). Numbers in parentheses (first column) refer to the numbered definitions of Rivas (1956). Field numbers are as noted above. Specimens are arranged by increasing body length and the field numbers therefore are not in sequence. The following abbreviations are used. D: = spinous or first dorsal fin D2 = second dorsal fin C = caudal fin A: = first anal fin Az = second anal fin Pi = pectoral fin Pz = pelvic fin orig. = origin (in reference to fins) c.p. = caudal peduncle Sex Sex was determined and recorded for all speci- mens except EATL-37. Only five of the 57 speci- mens were males (Fig. 1). They are EATL-7, 10, 11, 33, 34, all caught in the Tavira-Olhao area, four of them in traps (three on 17 August, one on 23 August), one on hook and line (31 July). All are small, their weights being 35, 25, 27, 25, 25 kilo- FE R !0 € Q 8 U Ee 6 N c 4 Ye2 50 60 70 80 =e) 100 SIZE CLASS (LB) Figure 1.—Weight-frequency histogram of white marlin, Tetrapturus albidus, from the eastern North Atlantic Ocean. Solid color = females, cross-hatching = males. grams respectively. None was in ripe or near ripe condition. All females were in a refractory state with no developed eggs except that EATL-6 had relatively large ovaries with very small eggs. How- ever, it, too, was nowhere near reproductive state. These data agree with the suggestion that the white marlin concentrations are postspawning af- fairs. Also, Ueyanagi et al. (1970) demonstrate convincingly that white marlin spawn early in the summer and they further suggest that the post- spawning feeding migration to temperate waters then occurs. The Japanese have done little work in the eastern Atlantic north of lat. 30°N and east of long. 30°W. Why there should be a preponderance of females is unknown but de Sylva and Davis (1963: 87) also noted a significantly large percentage of female marlins in the Middle American Bight in 1959 though not in 1960. There is nothing in our limited data nor in the much larger samples of de Sylva and Davis to suggest a time difference in the peak abundance of males and females. Food All stomachs were examined but the stomach acid of marlins is strong and the time from trap to freezer uncertain. Also marlins taken on hooks fre- quently void the contents of their stomach. In any event only well digested remains, some of it fish in origin, were found. Weight Weight in pounds is given for each specimen in Appendix Tables 1 and 2 with equivalent weights in 166 kilograms in Appendix Table 1. These weights are of the frozen or partly thawed fish but they proba- bly do not vary in any meaningful way from the original weights. To facilitate comparison with the data of de Sylva and Davis (1963: Figures 4 and 5) a histogram of weights in 5-lb (2.27-kg) units is pre- sented in Figure 1. Although data are few the first peak in the 55-59 Ib (24.9-26.8-kg) range agrees remarkably with the weight frequency data for American Bight speci- mens. There are more large fish off Gibraltar and the lower peaks at 75-79 (34.0-35.8-kg) and 95-99 Ib (43.1-44.9-kg) probably represent successive year classes. If so, the data suggest that older year clas- ses of white marlin along the Atlantic coast of the United States do not participate in the migration or that they are fished out in that population. A wider range in weights is seen in white marlins in southern Florida (personal observations) which might sup- port the first of these suggestions but more likely indicates that the large Florida and Bahamas fishes are not part of the population that congregates in the Middle American Bight. Mather’s (1968) chart of migration trends based on 34 tag returns shows the pivotal nature of the Florida-Bahama region rel- ative to the three stocks and that at least some marlin from this area participate in the summer concentration off the Mississippi Delta. Possibly fishes of the Gulf and northwestern Atlantic stocks pass through the Straits of Florida. Determination of minor morphometric differences between these stocks would be invaluable in analyzing the catch in the Straits of Florida but data available are inade- quate and no such study has yet been undertaken. The Venezuela stock may be confined to northern South America. Population Structure No clear picture yet emerges with regard to the population structure of the white marlin. Specimens from the eastern and western Atlantic are not meristically distinct (Table 1). The detailed analysis of the Atlantic longline operations of the Japanese fishing fleet by Ueyanagi et al. (1970) shows a summer peak in the western Atlantic consistent with the late summer concentrations off Louisiana and Maryland-New Jersey. Their data however give no real indication of a Venezuelan concentra- tion and they have virtually no data on the species from the eastern Atlantic north of lat. 25° or 30°N. Their data definitely indicate a dense population along the eastern coast of Brazil from Pernambuco to Sao Paulo in southern spring and summer (Sep- tember to March). No doubt it is the Japanese data on which Mather (1971) bases his remarks about Brazilian and mid-ocean concentrations. Japanese fishing effort is far from consistent (Ueyanagi et al. 1970, fig. 17) and the hook rate data are difficult to evaluate. The tendency to set many hooks in good fishing areas obscures the density by lowering the hook rate index. Similarly the grouping of data on maturity by quarters obscures the early summer spawning peak since it is divided between two quar- ters. Actually it is unclear how widespread is the early summer spawning peak. In the western Atlan- tic, data based on gonad examination and appear- ance of larvae (de Sylva, pers. comm.) indicate that spawning is largely complete by May at which time migration is already under way. Mather et al. (1972) review the Japanese data in greater detail and summarize information gained from the Cooperative Game Fish Tagging Program in the western Atlantic. They note that one North Atlantic population concentrates along the middle Atlantic coast of the United States in the summer and moves to the north coast of South America in winter. They also record the separate summer con- centration in the Northern Gulf of Mexico but be- cause it shares a northern South American winter- ing ground the relationships of the two was said to be uncertain. So too was the origin of the popula- tion that occurs in summer off Venezuela. The white marlin in the South Atlantic was clearly rec- ognized by these authors as separate from those in the north. No information was given for the north- eastern Atlantic.. The migratory path of the white marlin to and from the approaches to Gibraltar is unknown but data published by Ueyanagi et al. (1970 appendix, figs. 2 j, k, 1) suggest progressive movement south along Africa to about lat. 5° N. Clearly an intensive program of research is needed on this important food and game species. ACKNOWLEDGMENTS Many persons have aided the billfish research program at the School of Marine and Atmospheric Science. Those previously acknowledged by Rob- ins and de Sylva (1961: 384-384) and Rodriguez- Roda and Howard (1963) are omitted here. The late John K. Howard made all the arrangements for the Mediterranean work and subsidized much of its cost. The writer’s travel to Europe and the pur- chase of some of the material was supported by the Maytag Chair of Ichthyology. Analysis of the data and preparation of the paper is part of a program on oceanic fishes supported by the National Science Foundation (NSF-GB-7015x, C. Richard Robins, principal investigator). Shari Lou Buxton processed the data for the tables. Donald P. de Sylva re- viewed the manuscript and made available data on the white marlin in the western Atlantic. Finally, I especially thank Rui Monteiro and Julio Rodriguez-Roda, Laboratorio del Instituto de In- vestigaciones Pesqueras, Cadiz, Spain, for aiding the writer in many ways during his work at Olhao, Portugal and Cadiz, Spain. LITERATURE CITED CANESTRINI, G. 1861. Sopra una nuova species di Tetrapturus. Arch. Zool. Anat. Fisiol. 1(1):259-261, pl. 17. DE SYLVA, D. P., and W. P. DAVIS. 1963. White marlin, Tetrapturus albidus, in the Middle American Bight, with observations on the hydrography of the fishing grounds. Copeia 1963:81-99. Table 1.—Fin-ray counts of western! and eastern Atlantic white marlin. Tetrapturus al- bidus. Dorsal Spines Dez Rays Anal Spines Ag Rays Pi Rays ? . 38 39 40 41 42 43 44 45 SHG 7 S13 145) 16m 18 SPO li Sa 9r 20 2122 Atl PB II) TUG) 5 hod I 41818 5 — — Al — elle? 16)23) 9 Atl. = TNS IO BS AG) Sas CPOE jp 2). Sy Olena 2m OFS OmIs eer * Data from Robins and de Sylva (1961: Table 1) * Only the left pectoral fin was counted. 167 GIBBS, R. H., JR. 1957. Preliminary analysis of the distribution of white mar- lin, Makaira albida (Poey), in the Gulf of Mexico. Bull. Mar. Sci. Gulf Caribb. 7:360-369. GONCALVES, B. C. 1942. Collecgao oceanografica de D. Carlos 1. Catalogo dos Peixes. Trav. Stn. Biol. Mar. Lisbonne 46, 108 p. LAMONTE, F. R. 1955. A review and revision of the marlins, genus Makaira. Bull. Am. Mus. Nat. Hist. 107:323-358. LEGENDRE, R. 1928. Présence du Tetrapturus belone au large de la Bre- tagne. Bull. Soc. Zool. Fr. 53:391-392. MATHER, F. J., Il. 1968. The trail of the tail-walker. Proc. Int. Game Fish Conf. 12:20-24. 1971. White marlin in the Atlantic Ocean. Proc. Tuna Conf. 22:19-21. MATHER, F. J., Ill, A.C. JONES, and G. L. BEARDSLEY. JR. 1972. Migration and distribution of white marlin and blue marlin in the Atlantic Ocean. Fish. Bull., U.S. 70:283-298. PEREZ DE ARMAS, C. J. 1959. A los pescadores de Agujas. Revista Pesca y Nautica, Sept. 33-43, 2 figs. 168 RIVAS, L. R. 1956. Definitions and methods of measuring and counting in the billfishes (Istiophoridae, Xiphiidae). Bull. Mar. Sci. Gulf Caribb. 6:18-27. ROBINS, C. R., and D. P. DE SYLVA. 1960. Description and relationships of the longbill spear- fish, Tetrapturus belone, based on western North Atlan- tic specimens. Bull. Mar. Sci. Gulf Caribb. 10:383-413. 1963. A new western Atlantic spearfish, Tetrapturus pfluegeri, with a redescription of the Mediterranean spearfish Tetrapturus belone. Bull. Mar. Sci. Gulf Caribb. 13:84-122. RODRIGUEZ-RODA, J., and J. K. HOWARD. 1962. Presence of Istiophoridae along the South Atlantic and Mediterranean coasts of Spain. Nature (Lond.) 196:495-496. SASSI, A. 1846. De pesci del mare di Genova. Nuovi Ann. Sci. Nat. Rend. Sess. Soc. Agr. Accad. Sci. Ist. Bologna, ser. 2, 6:386-396. TORTONESE, E. 1961. Mediterranean fishes of the family Istiophoridae. Nature (Lond.) 192:80. UEYANAGI, S., S. KIKAWA, M. UTO, and Y. NISHIKAWA. 1970. 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= OzO'Z_—isSBH'T =~ (OLE'I S961 76‘ ze6'l = ZE6'I 826'| 026'I so6'| 006" S68" I P68" 1 788 sca] 098 098"! (ww) ({) yuo] Apog bh 97 s ra Le bs 0€ CG ss 9 SP tp 8P Lt of 6 oI 9s S1oqUNN UaUtoadgs *(panunuod -yysua| Apog jo adequadiad ul passaidxa onuRYy YWON UWsaysea ay) Woly sipig/) sninidD4jaf JO suauMidads g¢ 10J Pep SeWoYdIoW—"Z aqQe] xIpuaddy 174 The Cape of Good Hope: A Hidden Barrier to Billfishes M. J. PENRITH! and D. L. CRAM? ABSTRACT Since 1838 there have been isolated reports of billfishes from the southern tip of Africa, but only during the years 1961-64, when a number of Cape Town based boats fished commercially for tuna using longlines, were billfishes found to occur in considerable numbers. The waters to the west and south of the Cape of Good Hope were found to be unique in their billfish fauna, no less than six species being represented, comprising Xiphias, Makaira (2 species) and Tetrapturus (3 species). Only two wide-ranging species have not been found. Istiophorus is commonly listed from the area on the basis of Histiophorus granulifer, but a reexamination of de Castelnau’s type shows it to be a Makaira, while T. angustirostris could occur as it is known from off Durban. The billfishes are probably attracted to this limited geographic area by the rich feeding grounds which are the result of the upwelling of nutrient-rich water along the Cape’s west coast. It is difficult, however, to suggest reasons why there is an apparent barrier to movement between the Atlantic and Indo-Pacific Oceans for certain species. Hydrographic conditions in the area are discussed, but there are no obvious physical barriers preventing black and striped marlins from entering the Atlantic nor white marlin and longbill spearfish from moving into the Indo-Pacific. The African landmass is unique, since of all the major landmasses it alone does not project suffi- ciently polewards to form a complete barrier to the east-west movement of all the larger mobile warm- water oceanic fish. All the same, it has traditionally been considered a barrier to the movement of bill- fishes between the Atlantic and Indo-Pacific Oceans. This concept of a barrier has to a large extent been strengthened by the very marked differ- ences in the inshore marine fauna of the two sides of the southern African coast (Ekman, 1953). The term Cape of Good Hope can be used for any of three areas. In the strict cartographic sense it is a minor land projection to the west of Cape Point on the southern end of the Cape Peninsula. Historically it embraced the area from about Cape Columbine to the region of Cape Agulhas; this was the area where the early East-Indiamen made their first landfall when rounding the tip of Africa. Finally, the 19th century biologists used the Cape of Good Hope ina very wide sense to include the whole southern tip of Africa and its adjacent seas. In this paper the Cape of Good Hope is used in the same sense as the early navigators used it, that is to include the land and 'State Museum, Windhoek, South West Africa. *Division of Sea Fisheries, Beach Road, Sea Point, Republic of South Africa. 175 adjacent seas to the south and west of the Cape Peninsula (Fig. 1). Following the conventional divi- sions of the oceans this area is within the Atlantic Ocean, but is in reality a very confused area for the oceanographer. Water from at least four sources can occur as surface water in the area, being either sur- face water of South Atlantic or Indian Ocean (Agulhas Current) origin, mixed Agulhas Bank water, or upwelled water of probably South Atlantic Central water origin (Shannon, 1966; Visser, 1969). The exact position of these water masses in relation to each other is dependent on a number of factors, but the direction and strength of the winds, both local and as far removed as the monsoons of the northern Indian Ocean, are the dominant factors. The hydrography will be described more fully below, but in general there is an east-west oscilla- tion of Atlantic and Indian (Agulhas Current) sur- face waters with southerly and westerly movements of upwelled water. The first record of a billfish from the Cape of Good Hope was the description by Gray (1838) of Tetrap- turus herschelii (= Makaira nigricans). Thereafter there were very few records of billfishes indeed (Table 1), with the exception of a number of catches of Xiphias gladius since 1956 by deep-water trawl- ers. Table 1.—Billfishes recorded from the Cape of Good Hope. Date Locality ‘Method *Size Xiphias gladius 15.2.56 Dassen Isl. B 1,060 mm 20.7.56 40 miles W. Slangkop B 2,620 mm 19.8.56 40 miles W. Slangkop B 32 kg. 25.3.58 False Bay xX 558 mm WE3=58 W. Slangkop B 875 mm 8.3.58 15 miles S.W. Cape Point Ap 875 mm 14.4.59 30 miles W. Slangkop B 86 kg 8.10.60 60 miles W. Slangkop L 170 kg 12.1.61 20 miles W. Slangkop B 106 kg 3.4.61 W. Danger Point B =e) Sikes 1.11.61 S.W. Slangkop 1 + 190 kg 22.2.62 W. Slangkop SH be + Akg 22.2.62 30 miles W. Cape Point L + 55kg 1.3.62 W. Peninsula L + 60 kg 30.3.62 W. Peninsula 15 sp melee: 31.3.62 W. Peninsula L See like Makaira indica 16.1.61 W. Peninsula L 3,527 mm 27.1.61 W. Peninsula L 3,334 mm 21.2.61 30 miles W. Slangkop L 3,559 mm 2.3.61 35 miles W. Slangkop L 3,558 mm 3.3.61 W. Slangkop L 2,850 mm 13.3.61 W. Slangkop ie, + 340 ke 13.3.61 W. Slangkop L + 370 kg 14.3.61 W. Cape Point bs 3,180 mm 15.3.61 W. Danger Point L 3,000 mm 20.3.61 W. Cape Point ie + 370 kg 9.1.62 W. Dassen Isl. L 2,959 mm 11.1.62 W. Peninsula L 3,487 mm 15.1.62 W. Cape Town Ib + 370 kg 28.1.62 40 miles S.W. Cape Point L 2,545 mm 28.1.62 40 miles S.W. Cape Point L 3,210 mm 30.1.62 30 miles W. Cape Point L 2,935 mm 30.1.62 30 miles, W. Cape Point i 3,100 mm 30.1.62 30 miles W. Cape Point LE 2,935 mm 30.1.62 30 miles W. Cape Point L + 280 kg 25.2.62 30 miles W. Cape Point gn 210 kg 26.2.62 W. Peninsula 16: + 300 kg 7.3.62 W. Peninsula L + 300 kg 7.3.62 75 miles W. Cape Point &, 3,460 mm 1B=bottom trawling, L=longline, T=trolling, X=other (usually *Given as weight or body size (tip of mandible to fork). 8X. gladius found in stomach of T. audax. 4M. indica and T. albidus taken on same set of longline. >Collected with scoopnet at light station. Subsequent to experimental longlining for tunas in the waters to the west of Cape Town by the South African Museum (Talbot and Penrith, 1962, 1968) and the Division of Sea Fisheries (Nepgen, 1970) at the beginning of 1960, a number of commercial fish- ing vessels were equipped for longlining. It was Date Locality ‘Method *Size Maikaira indica 30.3.62 W. Slangkop ib, + 150 kg 31.3.62 W. Slangkop L + 370 kg 31.3.62 W. Slangkop L + 80kg 20.5.62 N.W. Cape Columbine IL, — 24.1.63 40 miles S. Cape Point L 3,648 mm 20.2.63 40 miles S. Cape Point I: 645 kg 22.2.63 W. Peninsula IL 2,936 mm 22.2.63 W. Peninsula L 2,570 mm 2.3.63 W. Peninsula IL, 3,025 mm 4.3.63 W. Peninsula L 2,753 mm 29.3.63 Camps Bay beach xX 2,151 mm Makaira nigricans 1838 Table Bay xX _— 7.6.58 Hout Bay x + 225 kg 23.6.61 45 miles N.W. Dassen Isl. L 2,959 mm 16.4.64 30 miles S.W. Cape Point 3,385 mm Tetrapturus audax 25.2.61 W. Slangkop L 1,746 mm 25.2.61 W. Slangkop L 2,182 mm 15.3.6] W. Cape Point L + 70 kg 26.1.62 40 miles S.W. Cape Point IL, 2,285 mm 1.2.62 W. Peninsula L 2,120 mm 8.2.62 W. Peninsula IL, 2,011 mm 17.2.62 W. Peninsula IL, + 70 kg 22.2.62 30 miles W. Cape Point S18 2,131 22.2.62 30 miles W. Cape Point L 2,132 22.2.62 30 miles W. Cape Point L 2,112 7.3.62 W. Peninsula Ik — 7.3.62 W. Peninsula L — 17.4.62 S.W. Cape Point L + 50 kg Tetrapturus albidus 2.3.61 435 miles W. Slangkop L 1,918 11.2.62 W. Cape Point IL, + 45 kg 10.5.62 35 miles W. Slangkop L + 40 kg Tetrapturus pfluegeri 24.6.63 125 miles N.W. Cape Columbine I. 1,795 mm 13.7.64 33°09'S 16°07’E XG 588 mm standing). hoped that this would provide useful employment during the fishing offseasons. For a number of reasons this experiment was not a success and was tried ona large scale only during the years 1961-1964. The boats fished for a company under contract to supply tuna; all other fish landed could be disposed of by the skipper as he wished. There was little or no demand for marlin and skippers were only too pleased to inform the South African Museum when they landed marlin in return for a small commission. There was, however, a strong market demand for broadbill swordfish with the result that these fish were immediately sold on docking to fish dealers and seafood restaurants. The collection of billfishes examined was not large but was interesting in the number of species that were found to occur in this limited area of water. Apart from the swordfish (X. gladius) four species of marlin, the black (M. indica), the blue (M. nigricans), the striped (T. audax) and the white (T. albidus), and one species of spearfish (7. pfluegeri) were obtained from the area during that period. BILLFISHES RECORDED FROM THE CAPE OF GOOD HOPE Xiphias gladius The data for the broadbill swordfish are scanty, especially with regard to longline-caught fish, since it was the only marketable billfish landed. The species does not appear to have any seasonal pattern of appearance off the Cape, occurring at any time of the year. It was caught in a very wide range of sizes and in a number of ways, from a juvenile collected alive in a tidal pool to large specimens taken by longlining. The majority of fish examined were not taken by longlines but by bottom trawlers fishing in water over 100 fathoms deep. It is presumed that the C. COLUMBINE Yioe TOWN y HOUT BAY Yaa. / Wi, A a, / y, y / FALSE BAY CAPE POINT A MOSSEL BAY. ST. SEBASTIAN BANS —~ CAPE AGULHUS \ swordfish were feeding on the bottom; in one case a number of semidigested coryphaenoid fishes were found in the gut. Makaira indica Black marlin were the most common of the is- tiophorids off the Cape. They apparently had a very limited season, being found only between the middle of January and the end of March (with one excep- tion). All fish examined were unripe females and of a large size (up to 645 kg). All but one of the fish were taken by longliners. Tetrapturus audax Striped marlin were not as common as black; only 13 fish were seen. They appeared to be present in the area at the same time as the black, and also were found only between the middle of January and the end of March. Again there was one exception to this pattern; for this species, and the black marlin, the exceptions were fish caught in 1962. All striped mar- lin examined were taken by longline. Tetrapturus albidus White marlin were rare and only three were taken in the 4 yr under consideration. There is a suggestion that they may appear a little later than the other two species so far discussed, being found from February to May. However, the May specimen was taken in 1962, when the water conditions off the Cape possi- bly remained suitable for billfishes until later than in AN Figure 1.—The Cape of Good Hope. INE the other years. All fish were taken by longline west of Cape Point; Smith’s (1964) record ‘‘off Cape Agulhas”’ is an obvious error. Makaira nigricans Blue marlin, although known from very few specimens, appear to enter the fishery off the Cape at a different time of the year from the other three species. Of the three specimens for which any data are available, one was taken in April, one in June, and one in July. It is extremely interesting to note that the blue marlin did not appear during the sum- mer fishery. This could suggest an Atlantic origin (compare 7. pfluegeri) rather than an Indo-Pacific origin. It is also interesting that the blue marlin, the only circumtropical istiophorid, was one of the scar- cest in the area. This may suggest that there is only limited genetic exchange between the two popula- tions. Smith (1964) has suggested an Indo-Pacific origin for the blue marlins taken off Cape Town on the basis of one fish taken in the same area as a striped marlin. The fish referred to is apparently the fish taken on 23 June 1961 by one of us (M.J.P.); in other words, in the same geographic area as striped marlin (as stated by Smith), but at a different time of year and probably from a different water mass. From temperature and salinity records taken during the tuna cruise on which this fish was landed, it is be- lieved that the fish was taken in water of Atlantic surface origin. Tetrapturus pfluegeri The longbill spearfish was the rarest of the is- tiophorids found during the longline fishery. Only two were seen, an adult and a juvenile, both in mid- winter. BILLFISHES NOT RECORDED FROM THE AREA Istiophorus No specimens of the sailfish have been obtained during the Cape longline fishery. There are, how- ever, certain old records. Most can be discarded owing to the wider geographical area covered by the term Cape of Good Hope in 19th century biological reports. De Castelnau (1861), however, described Histiophorus granulifer from St. Sebastian Bay, to the east of Cape Agulhas, only just outside the area 178 discussed in this paper. This species has generally been considered to represent a sailfish (Jones and Silas, 1964; Smith, 1964; Nakamura, Iwai, and Mat- subara, 1968; Morrow and Harbo, 1969). Reexami- nation of the type (a rather battered skull and mandi- ble), however, has shown it to be the skull of a Makaira rather than an /stiophorus. The skull is broad and heavy witha short stout bill. The bill is 799 mm in length, with a circumference of 169 mm at a point level with the anterior tip of the mandible. It is possibly M. nigricans but insufficient comparative material was available for us to be certain. Tetrapturus angustirostris Although not found at the Cape there is little reason why this species should not occur in the area, at least in some years. It is probably common in the southern Indian Ocean (Japanese fishery records), and has been recorded off Durban (Penrith, 1964). RECORDS OF BILLFISHES BASED ON JAPANESE CATCHES IN THE AREA A detailed analysis of the Japanese commercial longline catches of billfishes in the Atlantic has re- cently been completed (Wise and Davis, 1973). The data given here are based on a shorter period, but include data from the southwest Indian Ocean in addition to the southeast Atlantic. There are prob- lems in using these data, since the catches of spear- fish and sailfish are not differentiated and likewise the small marlins, white and striped, are also not distinguished. It is only in the region here discussed, where both small marlins can occur, that their non- separation will cause any difficulty. The catch in the waters off southern Africa has been plotted for the common istiophorids by 5° squares On a quarterly basis for the years 1965-69. The results are shown graphically in Figures 2-4. In these figures the catch rates per 100 hooks have been shown for each square by the conventional markings as used on dice and are as following: 1=<0.001 2= 0.001—0.004 3= 0.005—0.009 4= 0.01—0.04 5= 0.04-0.1 6=>0.1 The distribution pattern of black marlin based on these catches is shown in Figure 2. Several features SUMMER AUTUMN WINTER 30°E SPRING Figure 2.—Distribution of M. indica around the southern tip of Africa by quarter of the year. Catch rates (per 100 hooks) represented by number of dots in each 5° square (one—<0.001, two—0.001-0.004, three—0.005-0.009, four—0.01-0.04, five—0.04-0.1, six—>0.1). are noteworthy. Judging from the catch rates there is always a fair black marlin population present in the southwest Indian Ocean. At all times of the year, except midwinter, a certain number of the fish move into the sea area west and south of the Cape of Good Hope, but are apparently most numerous there in the summer period, January to March. At various times records of the black marlin are found well into the Atlantic within the area covered by the present report. Wise and Davis (1973) have recorded catches of this species over a wide area of the Atlantic, but in all cases the records are based on Japanese catch statistics. Apparently none of the fish have been examined by an ichthyologist. On the other hand the skippers of the Japanese boats can be assumed to be familiar with the different marlins and their distribution and will presumably check any identification as unexpected as this. It has become almost a theorem that the black marlin does not occur in the Atlantic, and there is the resultant _ danger that any large marlins found in the Atlantic will be identified as blues without adequate examina- tion. 179 Catch rates west of long. 20°E are never as high as those east of this meridian, but there is a suggestion of a northwesterly movement of the stocks from the southern tip of Africa as summer advances and a withdrawal with the onset of winter. It is suggested that the black marlins present in the Atlantic are fish that have entered the Atlantic in eddies of warm Agulhas water at this time and are then trapped by cold water, preventing their return to the Indian Ocean. Similar catch statistics have been plotted for the blue marlin. These are shown in Figure 3. On the basis of the very few catches made off the Cape by local vessels, it was thought that the blues were of Atlantic origin. The more widespread catches of the Japanese fishing industry, however, suggests that at least some of the blues may actually be of Indo- Pacific origin. Between January and June there is a widespread but low catch round the southern tip of Africa, but as winter progresses there is apparently a movement of fish away from the Cape, and diffusely distributed fish then resolve into two populations, an Atlantic one and an Indo-Pacific one, although a subpopulation of the Atlantic fish may remain at the Cape during winter on account of the rich food avail- able. The pattern of distribution in summer, how- ever, suggests that there is limited scope for genetic interchange between the two populations. This adds support to the concept of only one worldwide species of blue marlin, but with certain features of a clinal nature. The possibility that the length of the pectoral fin in 7. angustirostris varies as a cline across the Indo-Pacific has been advanced (Penrith, 1964; Merrett, 1971). It is possible that the degree of development of the lateral line system in the blue marlin is similar, but more marked, since the geo- graphic range is greater, and the Cape of Good Hope, while not a barrier to this species, probably tends to minimize the degree of genetic interchange, and thereby accentuates the development of minor differences. The catch rates for the category white/striped mar- lin for summer and winter are shown in Figure 4. From the catch statistics the two species cannot be separated. In view of the records from the same source of black marlin in the Atlantic it must be SUMMER WINTER assumed that occasional striped marlin will also occur in the Atlantic. In summer it can be seen that the Atlantic fish (white marlin) are present all down the west coast, and in the southwest Indian Ocean (striped marlin) high catch rates are general. In winter there are still fish east of long. 20°E but the catch rates have dropped, whereas west of this point the fish have disappeared and are present only in small numbers north of lat. 30°S. Although the dis- tribution for autumn is not shown, it is essentially the same as winter. This confirms the results of the much more limited local South African fishing, namely that these species are present in the Cape of Good Hope area only in summer. Broadbill swordfish were taken by the Japanese boats at all times of the year in the area. This species was also common farther south than the other species, being taken occasionally south of lat. 40°S. Catch rates for this species were in general higher than for the other species, but were apparently lim- ited by the subtropical convergence. In the Japanese statistics the spearfishes are not differentiated from the sailfish. It is not possible to AUTUMN SPRING Figure 3.—Distribution of M. nigricans around the southern tip of Africa by quarter of the year. Catch rates (per 100 hooks) represented by number of dots in each 5° square (one—<0.001, two—0.001-0.004, three—0.005-0.009, four—0.01-0.04, five—0.04-0.1, six—>0.1). SUMMER WINTER Figure 4.—Distribution of T. albida/T. audax around the southern tip of Africa, summer and winter. Catch rates (per 100 hooks) represented by number of dots in each 5° square (one—<0.001, two—0.001-0.004, three—0.005- 0.009, four—0.01-0.04, five—0.04-0.1, six—>0.1). attempt any differentiation in the area, although close to the Cape of Good Hope the statistics almost certainly refer to spearfishes. In other areas the ma- jority of fish close to land can be assumed to be sailfish and those offshore to be spearfishes. As has been noted above the sailfish has never been re- corded from the Cape of Good Hope area. HYDROGRAPHY OF THE AREA Four distinct water masses can be discerned off the southern African coast (see Fig. 10a): the up- welled component or the Benguela Current System (9-16°C and 34.8-35.0°/oo); the Agulhas Bank mixing water zone of varying composition (16-21°C and 35.2-35.5°/oo); the Agulhas Current water (22-27°C and 35.4-35.5°/oo); and the South East Atlantic Sur- face water (16-21°C and 35.5-35.8°/oo) (Shannon, 1966). The upwelled component of the Benguela Current system is a clearly marked coastal low temperature zone originating near the Cape of Good Hope and separated from offshore oceanic water by a steeply gradiented oceanic front (Shannon, 1966; Andrews and Cram, 1969). The frontal system is most strongly defined in summer, during the period of intense local southeasterly winds. The continuous presence of the _ front is clearly demonstrated as far north as lat. 22° 181 S, near Walvis Bay (Bang, 1971). The nutrient en- richment of surface waters coastward of the front produces rapid production and a high standing crop of phytoplankton which supports the large pelagic fish industry of South Africa. The Agulhas Bank mixing zone is characterized by systems of eddies, and the structure is very vari- able (Shannon, 1966). The Agulhas Bank water is the product of mixing by South East Atlantic Surface water and Agulhas Current water. Thus the temper- ature of this region varies considerably with the sea- sons between 16° and 21°C depending upon the ex- tent of the contributions of its major sources. The Agulhas Bank water frequently extends to the northwest as a warm current extending around the Cape of Good Hope intensifying the gradients with the upwelled water. Bang (1970a, 1970b) found that the Agulhas Cur- rent movements to the south of Cape Agulhas were dominated by two systems, the Return Agulhas Current and the Westward Extension of the Agulhas Current into the southeast Atlantic (Fig. 5). At about long. 22° E most of the Agulhas Current re- curves as the Return Agulhas Current, but a portion is unaffected by this deflection and continues west as tongues of warmer water thrusting into the Atlantic. Shannon (1966) deduced that the northward branch- ing intrusion is likely to move northwards in isolated patches as an anomalous part of the Benguela Cur- rent system. Such patches have not been detected north of lat. 32°S and it must be assumed that the patches lose their dynamic integrity and are dissi- pated by mixing. Darbyshire (1964) and Shannon (1966) agree that the maximum flow of the Agulhas Current is in April (late summer) and the minimum in August (spring). Thus the maximum westward , 20° MARCH 1969 T°C at Om 24° 28° 32 Figure 5.—Surface temperatures off South Africa, March 1969 (from Bang, 1970b). penetration is in late summer, the minimum in spring, although such penetration could occur at any time of the year. The South East Atlantic Surface water frequently extends across the Agulhas Bank under the influ- ence of the westerlies in winter. Surface currents then are frequently southerly along the west coast and easterly over the Agulhas Bank. During sum- mer, the South East Atlantic Surface water can fre- quently be observed as an intrusion between the upwelled component of the Benguela Current Sys- tem and an Agulhas extension. Figure 10a shows a large intrusion of South East Atlantic Surface water extending over the Agulhas Bank, while Figure 5 shows a thin lens of such water along the edge of the Bank, being outflanked by a northwesterly arm of the Agulhas Current. Wrth the seasonal interplay of northwesterly and southeasterly winds the penetra- tion of South East Atlantic Surface water will vary to a greater or lesser extent. Duncan and Nell (1969) 182 report that between Cape Agulhas and the Cape of Good Hope the summer flow is strongly east to west, and in winter the flow is reversed and weaker. DESCRIPTION OF OCEAN CONDITIONS DURING THE SURVEY PERIOD Summer, January 1961 (Shannon, 1966; Fig. 6a,b) The Agulhas Current (>22°C and 35.4-35.5°/oo), extends over a considerable portion of the Agulhas Bank, reaching close inshore in the Cape Agulhas region. In addition, the Current extends around the Agulhas Bank and penetrates to the northwest up to about 32°S, the core of the warm-water extension being 150 nautical miles offshore. An isolated eddy of northward travelling Agulhas water is notable at lat. 36°S. South Atlantic Surface water is confined to the west of long. 15°E, that is greater than 200 nauti- T*C at Om 27 Figure 6.—Surface temperatures and salinities off South Africa, January 1961 (from Shannon, 1966). A. Temperature. Salinity. cal miles west of the Cape of Good Hope. Typical Agulhas Bank mixed water is present as a small patch of high salinity water (35.5°/oo). The upwelling component of the Benguela Current system is pres- ent to shoreward of a well-defined front. As westward penetration of the Agulhas Current is pronounced, Indo-Pacific billfishes could be en- countered as far west as long. 15°E and up to lat. 32°S. Close inshore, on the west and south Cape coast, the abundance of pelagic fish in the 14-16°C upwelled- origin water may be some inducement to feeding. No South East Atlantic Surface water approaches the coast. Autumn, April 1961 (Fig. 7a,b) The Agulhas Current Extension is well marked, extending as an intrusion of 22-24°C and 34.4°/o0 water to lat. 36°S, in a northerly direction. The Agulhas Bank mixed water is continuous from east of the Bank, round the Cape of Good Hope and into the South East Atlantic. The South East Atlantic Surface water is, for the most part, west of long. 17°E. The frontal system between the ocean and the upwelling area is not well defined, although the low tempera- tures indicate that upwelling is occurring (13°C and 34.8°/o0). The continuous low temperature and salin- ity area (15°C and 34.9°/oo), extending around the 183 Cape of Good Hope eastwards towards Cape Agulhas, indicates that either upwelling has been occurring or a southeasterly drift has occurred. At 20 m the isopleths tend to follow the coastline, except that the influence of the Agulhas intrusion, 21°C and 34.45°/oo, and South East Atlantic Surface water, 19°C and 35.6°/o0, can be observed. At 100 m the isopleths tend to follow the coastline. The possibility of billfishes approaching the coast at this time is not high. The extension of the Agulhas Current exists 120 nautical miles south of the Cape of Good Hope and the South East Atlantic Surface water about 100 nautical miles west of the Cape. If Indo-Pacific billfishes have moved into the Agulhas mixed water, the continuous westward extending area offers a route to the west passing close along the south and west Cape coasts, although the tempera- ture and salinity of this area may be uncomfortably low, and therefore unsuitable for billfishes. As in high summer, little opportunity is extended for the movement of southeast Atlantic billfishes eastwards around the Cape. Winter, July 1961 (Fig. 8a,b) The survey area is dominated by the South East Atlantic Surface water, which extends to the east of Cape Agulhas. There is only slight evidence of the IGE is 16 17 18 1s 20° at 22 Figure 8.—Surface temperatures and salinities off South Atrica, July 1961. A. Temperature. B. Salinity. upwelled component of the Benguela Current sys- tem (<14°C and <35.1°/o0) and the Agulhas Bank mixed water is absent. A similar pattern exists at both 20 and 100 m. At this time, southeast Atlantic billfishes could extend their range to the east of Cape Agulhas and could also be located close inshore on the Cape coast. Owing to the absence of any identifiable 184 Agulhas Current water it is unlikely that any Indo- Pacific billfishes would be resident in the survey area. Late spring, October 1961 (Fig. 9a,b) The winter eastward penetration of the South East OCTOBER ®61 TC at Om 38" Wwe rik Figure 9.—Surface temperatures and salinities off South Africa, October 1961. A. Temperature. B. Salinity. Atlantic Surface water is being reduced by the reas- sertion of the Agulhas Current’s westerly extension (>}20°C and 35.4°/o0) and the formation of a distinct Agulhas Bank mixed water zone. The Agulhas ex- tension is mild and extends only to lat. 37°S, some 140 nautical miles from the coast. However, the Bank water is well marked (<16°C and >35.4°/o0) on the Bank itself, and also shows an interesting high salinity intrusion (>35.4°/oo) round the Cape of Good Hope up to lat. 34°S. The South East Atlantic Sur- face water is present at long. 18°E although remain- ing more than 40 nautical miles offshore. At 100 m, the presence of the South East Atlantic Surface water is more strongly felt and it extends eastward to nearly long 20°E. A portion of the Agulhas Return Current is present on the eastern edge of the Bank as part of a powerful eddy, similar to ‘‘eddy A’”’ described by Bang (1970b). Despite the reestablishment of the Agulhas Cur- rent in the survey area, the contribution of the Indo-Pacific fauna is likely to be small. The tongue of Agulhas Bank mixed water which extends around the Cape of Good Hope may allow Indo-Pacific billfish to move west, but the limited westward penetration of the Agulhas Current itself makes this occurrence less likely. The South East Atlantic Sur- face water dominates the remainder of the survey area, bringing with it the strong likelihood of Atlantic billfish occurrence farther offshore than 40 nautical miles. Thus in this period there is a strong possibility 185 of both Atlantic and Indian Ocean forms being pres- ent, but with more chance of Atlantic species. Summer, January 1962 (Fig. 10a,b) Surface conditions at this time give an excellent example of the interplay between the four water masses off southern Africa. The Agulhas Current is present as a coastal tongue east of long. 21°E, con- tributing to the Agulhas Bank mixed water, and as a strong westward extension south of lat. 36°S. The Agulhas Bank water is clearly defined (<20°C and <35.5°/oo) and extends from the coastward portion of the Bank westwards around the Cape of Good Hope, where it creates a dramatically steep gradient with the upwelled water. Between the Agulhas Bank water and the Agulhas Current Extension is a large intrusion of South East Atlantic water which ex- tends across the southern portion of the Agulhas Bank. At 20 m the continuity of the Agulhas Bank mixed water around the Cape of Good Hope is very clearly marked. Thus an interesting situation prevails: Indo- Pacific billfishes could be present either close in- shore between the Agulhas Bank and around the Cape of Good Hope to lat. 33°S or south of lat. 36°S, in the Agulhas Extension. Between these areas the likelihood of Atlantic billfish occurrence is high, with particular interest in the fact that the South East Atlantic water occurs within 20 nautical miles of the coast at the Cape, ‘“‘compressing”’ the Agulhas Bank water against the upwelled water. In this particular summer season, therefore, one would expect all species of billfishes to occur within the survey area in reasonable numbers in the well-defined interwo- ven oceanic areas. SUMMARY OF POTENTIAL BILLFISH MOVEMENT East-west movement is possible by two methods. Firstly, billfishes could be present in the Agulhas Extension which curves northeastward into the South East Trade Wind drift, west of the Benguela Current system. This extension could become iso- lated and move farther north as an eddy until its identity is lost through mixing. Secondly, billfishes could become involved with the Agulhas Bank mixed water when its temperature is suitable and move westward in the nearshore current around the Cape of Good Hope, to seawards of the front be- tween the ocean and the upwelling area. East-west movements would be assisted in late summer by the maximal westward penetration of the Agulhas Cur- rent (Fig. 2 suggests that this may occur), and in- hibited in winter when the Agulhas penetration is ata minimum. Movement from west to east could also be en- couraged in two ways: firstly, with the assistance of the eastward intrusion of South East Atlantic Sur- face water extending onto or near the Agulhas Bank; secondly, by the close inshore movements of water in a southerly or easterly direction round the Cape of Good Hope and along the south coast. Both these water movements are considerably enhanced during winter and correspondingly diminished or absent during summer. In winter, however, billfishes ap- pear to be rare in the southeast Atlantic. Thus two patterns emerge: the possibility of a long-term or a short-term residence in alien water. The long-term residence could be caused by a west- ward movement in the Agulhas Extension or inshore current during summer followed by a period of resi- dence in the southeast Atlantic, possibly feeding on pelagic fish at the edge of the upwelling area. Later, in winter, an eastward movement would commence in the South East Atlantic Surface water as it pushes towards the Agulhas Bank. The short-term resi- dence is possible by a similar mechanism, but ac- cepts no delay before the fish take advantage of the common South East Atlantic Surface water intru- sion to return eastwards. Naturally, the inverse ap- plies to Atlantic billfishes extending into the Agulhas region, but appears unlikely to take place; the wider coverage of the Japanese fishery suggests that the blue marlin and the longbill spearfish, T. pfluegeri, caught off the Cape at this time are attracted by the rich feeding and will not move further east. This much can be deduced from available data. Figure 10.—Surface temperatures and salinities off South Africa, January 1962. A. Temperature. B. Salinity. 186 Speculation suggests that the bulk of the Agulhas fauna is carried into the Return Agulhas Current; thus the number of billfishes following a northwest- ward extension would be relatively few, and then with a maximum occurrence in late summer. Cor- respondingly, the bulk of the southeast Atlantic bill- fish would follow the South Atlantic gyre. A few could find their way into the intrusion off South Africa, but this would occur in winter when they are rare in the area. Why this possible movement between the two ocean systems has been so little utilized by billfishes (and other large oceanic fishes such as the tunas) is not known. That it has been little used is certain; until very recently it was not known to occur at all in istiophorids (with the exception of the blue marlin). We can only suggest, in the light of present knowl- edge, that some innate behavior pattern, possibly as a result of hydrographic conditions in the earlier history of the area, is responsible, since there is no obvious physical barrier. The Cape of Good Hope is not unique in acting as an inexplicable barrier; the Straits of Gibraltar are apparently not a marked zoogeographical barrier (Ekman, 1953), but as far as present knowledge goes, appear to act as a similar barrier to the Mediterranean spearfish, T. belone. ACKNOWLEDGMENTS We owe a debt of gratitude to many persons for their help: to C.R. Robins, R.S. Shomura, F.H. Talbot, and J.P. Wise, we are grateful for their prompt and patient answers to our queries; to S. Bruins, B.J. Pretorius and C.S. de V. Nepgen for help in obtaining literature and to T. Blamire, who was responsible for the extraction and plotting of the hydrographic data from the log sheets. Our grateful thanks are due to F. Williams, not only for agreeing to read the paper at the interna- tional Billfish Symposium on our behalf, but also for his help in providing information relating to the large pelagic fishes to one of us (M.J.P.) over many years, with little in return. This paper is published with the permission of the Secretary for National Education and the Director of Sea Fisheries. LITERATURE CITED ANDREWS, W. R. H., and D. L. CRAM. 1969. Combined aerial and shipboard upwelling study in the Benguela Current. Nature (Lond.) 224:902-904. BANG, N. D. 1970a. Major eddies and frontal structures in the Agulhas 187 Current retroflexion area in March 1969. Proc. Symp. Oceanogr. S. Afr., 1970, C.S.1.R., Durban, 1-15 p. 1970b. Dynamic interpretations of a detailed surface temper- ature chart of the Agulhas Current retroflexion and frag- mentation area. S. Afr. Geogr. J. 52:67-76. 1971. The southern Benguela Current region in February, 1966: Part I]. Bathythermography and air-sea interactions. Deep-Sea Res. 18:209-224. DARBYSHIRE, J. 1964. A hydrological investigation of the Agulhas Current area. Deep-Sea Res. 11:781-815. DE CASTELNAU, M. F. 1861. Mémoire sur les poissons de |’ Afrique Australe. Paris: Bailliére. DUNCAN, C. P., and J. H. NELL. 1969. Surface currents off the Cape coast. S. Afr. Div. Sea Fish. Invest. Rep. 76, 19 p. EKMAN, S. 1953. Zoogeography of the sea. Sidgwick and Jackson, Lond., 417 p. GRAY, J. E. 1838. Description of a new species of Tetrapturus from the Cape of Good Hope. Ann. Mag. Nat. Hist., Ser. 1, 1:313. JONES, S., and E. G. SILAS. 1964. A systematic review of the scombroid fishes of India. Mar. Biol. Assoc. India, Proc. Symp. Scombroid Fish. Part 1:1-107. MERRETT,N. R. 1971. Aspects of the biology of billfish (Istiophoridae) from the equatorial western Indian Ocean. J. Zool. 163:351-395. MORROW, J. E., and S. J. HARBO. 1969. A revision of the sailfish genus /stiophorus. Copeia 1969:34-44. NAKAMURA, I., T. IWAI, and K. MATSUBARA. 1968. A review of the sailfish, spearfish, marlin and swordfish of the world. [In Jap.] Kyoto Univ., Misaki Mar. Biol. Inst., Spec. Rep. 4, 95 p. NEPGEN, C.S. DE V. 1970. Exploratory fishing for tuna off the South African west coast. S. Afr. Div. Sea Fish., Invest. Rep. 87, 26 p. PENRITH, M. J. 1964. A marked extension of the known range of Tetrapterus angustirostris in the Indian Ocean. Copeia 1964:23 1-232. SHANNON, L. V. 1966. Hydrology of the south and west coasts of South Af- rica. S. Afr. Div. Sea Fish., Invest. Rep. 58:1-22. SMITH, J. L. B. 1964. Scombroid fishes of South Africa. Mar. Biol. Assoc. India, Proc. Symp. Scombroid Fish. Part 1:165-184. TALBOT, F. H., and M. J. PENRITH. 1962. Tunnies and marlins of South Africa. Nature (Lond.) 193:558-559. 1968. The tunas of the genus Thunnus in South African waters. Part 1. Introduction, systematics, distribution and migrations. Ann. S. Afr. Mus. 52:1-41. VISSER, G. A. 1969. Analysis of Atlantic waters off the west coast of south- ern Africa. S. Afr. Div. Sea Fish., Invest. Rep. 75, 26 p. WISE, J. P., and C. W. DAVIS. ; 1973. Seasonal distribution of tunas and billfishes in the At- lantic. U.S. Dep. Commer., NOAA, NMFS Tech. Rep. SSRF-662, 24 p. Catch Distribution and Related Sea Surface Temperature For Striped Marlin (Tetrapturus audax) Caught off San Diego, California JAMES L. SQUIRE, JR.! ABSTRACT Records for 4,535 marlin landed at San Diego, California, and related sea surface temperature data were examined for the period 1963 through 1970 to determine time-space distribution and the relationship of catch and sea surface temperatures. For the period 1963 through 1970 the catch of 4,535 marlin was compared to sea surface temperature conditions relative to increased catches. Catch distribution based on 1963 to 1967 data showed that 76.4% were caught within a 35- by 40-nautical-mile area off San Diego, with the maximum catch being made from mid-August to mid- September. Catch temperatures off southern California calculated for this area from airborne infrared sea surface temperature survey data ranged from 61° F (16.1°C) to 73° F (22.8°C); the mean catch temperature was 67.8° F (19.9°C). Sea surface temperature conditions based on 2-week average temperature charts issued by the National Marine Fisheries Service indicate that an initial warming of water to an average temperature of 68° F (20.0°C) or above is related to an increase in catch. When average temperatures were below 68° F (20.0°C), 931 fish were caught; between 68° (20.0°C) and 70° F (21.1°C) the catch was 1,886 fish; and a further increase to 70° F (21.1°C) or above resulted in a catch of 1,718 fish. Catch data and isotherm charts, 1963 through 1970, indicate that the continuity of the 68° F (20.0°C) and 70° F (21.1°C) isotherms from off central Baja California to off southern California is associated with improved fishing. When these isotherms were discontinuous the average catch per biweekly period was 82.0 fish; when these isotherms were continuous the average catch was 146.1 fish. The highest average catch per biweekly period (205.3 fish) was recorded when the 70° F (21.1°C) isotherm was continuous. The striped marlin (Tetrapturus audax) is the ob- ject of a sport fishery in southern California waters during late summer and early fall. Sport fishing for striped marlin in these waters has been conducted since about 1903 (Howard and Ueyanagi, 1965) and striped marlin were caught commercially up to 1937. Since 1937 it has been illegal to land the species commercially in California. The early sport and commercial fishery was centered near Catalina Island and between the island and the mainland. In recent times the area off San Diego has experienced increased angling effort, and presently this area yields the largest number of sportcaught striped marlin. Most of the marlin are landed at three points in southern California: the Avalon Tuna Club, Av- * National Marine Fisheries Service, Southwest Fisheries Center, La Jolla Laboratory, NOAA, La Jolla, CA 92037. 188 alon, Catalina Island; the Balboa Angling Club, Newport Beach; and the San Diego Marlin Club, San Diego. At these clubs each fish is weighed and information is recorded on a weight slip (Fig. 1). Changes in sea surface temperature affect the dis- tribution of many pelagic marine fishes commonly caught off southern California. During periods of high temperatures, greater numbers of the more im- portant marine game species, such as Pacific bonito (Sarda chiliensis), yellowtail (Seriola dorsalis), and Pacific barracuda (Sphyraena argentea), which are common to the lower west coast of Baja California, Mexico, migrate northward into higher latitides (Hubbs, 1916, 1948; Walford, 1931). Fishing suc- cess for albacore (Thunnus alalunga) off this area has been related to changes in sea surface tempera- ture (Hester, 1961; Clemens and Craig, 1965). Radovich (1961, 1963) has also described the effects Season No. eel eee ear whe eS) eho Member xX .. Non-Memter .... Daye Nome ee (aan Meanie ie Date Angler Address... Ses 2 D e Ne. Boat Dore D Fish CHAR... See Boat Captain CS havle a Dedley ene MOCACION Ge seat eon ane Hook Up Time _ANO:1O Anime To Boat Ao Vitter... Tackle Used: Bait Used: Smsnread! he fen | EI Flying Fish . . 5 Gas or ae ae oO Live Bait . . .(DS§ Light ; @?) Other ae see Medium oO Heavyies eee oO Special Oo ) rb Figure 1.—Weight slip used by the San Diego Marlin Club, San Diego, California. of water temperature on the distribution of scom- brid fishes common to the water off southern California and Baja California. There are many physical and biological factors that can affect the distribution of fishes. Tempera- ture, salinity, turbidity, and food supply (plankton and forage species) are but a few of these factors. However, knowledge of the precise degree to which one or a combination of factors affect distribution is not known. Temperature as one of the easily mea- sured factors has been shown in some instances to affect distribution of organisms. Observations of sea surface temperature prior to and immediately after the start of good fishing might give us some clues as to thermal conditions that may be contributing to successful striped marlin fishing. In this paper the temporal and geographical distribution of striped marlin catches off San Diego from 1963 to 1967 are described, and the relation of surface water temperature to fishing success during the period 1963 to 1970 is examined. Since more striped marlin were landed at the San Diego Marlin Club than at any other location, I used their catch records to determine the geo- 189 graphical distribution of the catch for each month of the fishing season. These records provided catch location for 3,923 fish, but the fishing effort ex- pended in catching this amount of fish is not known. These catch distribution data and sea surface tem- perature data derived from airborne temperature surveys were used in the calculation of the average or mean catch temperature off San Diego for all striped marlin caught during the major months of fishing for the years 1963 through 1967. The cooperation of the San Diego Marlin Club in allowing use of its catch records is appreciated. CATCH DISTRIBUTION The temporal catch distribution for the 1963 to 1967 period is shown in Table 1. Catch records in- dicate that August, September, and October are the months having the major catches of striped marlin. Few are caught in July, and usually the November catch is minor. Most fish are caught between mid- August and mid-October, with fishing during the first half of September yielding more catch than any other half-month period. Peak annual catches were recorded for every biweekly period, 16-31 August through 1-15 October, for the years 1963 to 1967. Table 1.—Striped marlin catch landed at the San Diego Marlin Club during half-month periods, July-November, 1963-1967 Monthly total Month Ist half 2nd half July 0 31 31 August 163 841 1,004 September 1,279 612 1,891 October 450 250 700 November 297 0 29 Total 3,923 For the months of August, September, and Oc- tober, catch locations of striped marlin were plotted on a chart divided into block areas of 10-minute latitude by longitude dimension. These areas are identical to the block area system used by the California Department of Fish and Game for de- termining catch locations for commercial and party boat catches (Young, 1963). The total catch over the 5-yr period by block area is shown in Figure 2, and the catch for each month is shown in Figures 3-5. Figure 2 shows that the major fishing area off San Diego outlined by a dark border can be de- scribed as being within the boundaries of lat. 32°20’ SAN vec AS NESE BBE Fee aca f lea) Figure 2.—Catch distribution of striped marlin landed at San Diego, California; August, September, and October 1963 through 1967. and lat. 33°00’ N, long. 117°50' W, and the coast from near Del Mar, California, to Rosarita Beach, Baja California, Mexico. This area accounted for 76.4% of all fish landed in these months at the San Diego Marlin Club. = CATCH AND TEMPERATURE RELATIONSHIP Since August 1963, the National Marine Fisheries Service, Tiburon Coastal Fisheries Re- search Laboratory, Tiburon, California, has con- ducted once each month sea surface temperature survey flights off southern California in cooperation with the U.S. Coast Guard. These surveys are conducted from an aircraft using an infrared radia- tion thermometer (ART) to measure sea surface temperatures (Squire, 1972), and data are published in the form of isotherm charts. Comparison of 146 simultaneous sea surface temperature observations between the airborne instrument and a sea surface bucket cast showed an average difference of 0.35° F (0.2° C) (ART lower), a range of —1.9° F (1.1° C) to 1.2° F (0.7°C), and a standard deviation of 0.65° F 190 1967. 118°30' 118°00' 117°30' 117°00' Figure 4.—Catch distribution for September 1963 through 1967. 33°30'F 33°00! 32°30! 32°00 118°O0' 118°30° 117930" 117°00' Figure 5.—Catch distribution for October 1963 through 1967. Table 2.—Mean catch temperatures and numbers of striped marlin landed at the San Diego Marlin Club; Au- gust, September, October 1963 through 1967. Mean temperatures calculated from subjective temperature data and catch data for each 10-minute longitude by latitude block area. Month Year Mean temp/month # fish August 1963 67.7° F (19.8°C) 605 1964 68.0° F (20.0°C) 78 1965 64.1° F (17.8°C) 25 1966 M27 E. (21-826) 102 1967 66.3° F (19.0°C) 194 September 1963 67.8° F (19.0°C) 717 1964 69.3° F (20.7°C) 361 1965 65.0° F (18.3°C) 124 1966 67.0° F (19.4°C) 335 1967 69.1° F (20.8°C) 354 October 1963 TZ (22526) 7B 1964 66.5° F (19.1°C) 339 1965 65.2° F (18.4°C) 147 1966 69.0° F (20.8°C) 98 1967 67.9° F (19.9°C) 43 191 Ss 66 67 68 TEMPERATURE (°F) Figure 6.—Distribution of striped marlin catch by sea surtace temperature showing the mean (x), standard de- viation (S), and range (R) of temperatures for all catches landed at the San Diego Marlin Club, California (1963-1967). (0.36° C). From these isotherm charts a sea surface temperature value was estimated for each 10-minute block area where fish were caught as shown in Figures 3-5. Using these temperature data and the catch distribution data for the 10-minute block area, mean catch-temperature? figures were computed for striped marlin landed in August, Sep- tember, and October for the period 1963-1967 (Table 2). Mean catch-temperatures by month for all fish landed were: August, 67.8° F (19.9° C); Sep- tember, 68.0° F (20.0°C); and October, 67.3° F (19.6°C). Temperatures at which striped marlin were caught ranged from 61.0° F (16.1° C) to 73.0° F (22.8° C) with a mean overall catch temperature of 67.8° F (19.9° C) and a standard deviation of 0.5° F (0.9° C). The distribution of the catch relative to temperature for all catches is shown in Figure 6. OBSERVATIONS OF TEMPERATURE ISOTHERMS OFF SAN DIEGO AND BAJA CALIFORNIA RELATIVE TO FISHING SUCCESS For comparison of marlin catch to sea surface temperature for the period 1963 to 1970, tempera- ture data for the area from southern California to off 2 Each striped marlin had a temperature value associated with it; the mean catch-temperature was computed by summing the temperature values and dividing by the total number of entries. the central west coast of Baja California were ob- tained from half-month average sea surface isotherm charts published by the National Marine Fisheries Service (U. S. Bureau of Commercial Fisheries, 1961). These isotherm charts are com- puted from sea surface temperatures reported by ships in the eastern Pacific. From examination of these isotherm charts temperatures off San Diego and to the south toward central Baja California were highest during the fishing seasons of 1963 and 1967, and lowest during the 1965 season (catches of 1,410, 602, and 296 respectively). Of particular interest to fishermen is the time of the beginning of the fishing season. Early in the fishing season off San Diego during the period prior to an increase in sea surface temperature to 68° F (20.0°C) the total number of marlin caught was 115, 2.5% of the total catch of 4,535 fishes (1963-1970), whereas for the first half-month period of each year showing the 68° F (20.0° C) isotherm off San Diego. the catch totaled 824 fish, representing an increase to 18.2% of the total catch. During the half-month periods, data show that temperatures were below 68°F (20.0° C) for 23 periods, and during this time a total of 931 fish, or an average of 40.5 fish/period, were caught. Tem- peratures were between 68° F (20.0° C) and 69.9° F (21.0° C) during 15 periods, and 1,886 fish were caught, resulting in an average catch of 99.2 fish/period. Temperatures of 70° F (21.0° C) or above for 14 periods resulted in a catch of 1,718 fish or an average catch of 122.7/period. The numbers of marlin caught during the half- month periods when the 68° F (20.0° C) and 70° F (21.0° C) isotherms were continuous from off Baja California northward to off southern California were compared to the catch when these isotherms were discontinuous (Table 3). For examples of con- tinuous and discontinuous isotherms in the area of study, see Figure 7. Data show that during periods when the 68° F (20.0° C) or 70° F (21.1° C) average isotherms were continuous from off central Baja California north- ward to off southern California, a total of 2,046 fish was caught for an average catch/period of 146.1 fish, whereas a total of 1,599 fish was caught for an average catch of 82.0/period when these isotherms were discontinuous. During periods when the 70° F (21.1° C) average isotherm was continuous the largest catch per any period (570 fish) and the high- est average catch rate/period (205.3 fish) was re- corded. 192 Table 3.—Comparison of catch and catch rates during periods of continuous and discontinuous 68° (20.0°C) and 70° F (21.1°C) isotherms. 68°F 70°F (20.0°C) = (21.1°C) Totals Discontinuous Isotherms Catch 1,072 486 1,559 No. of periods 11 8 19 Av. catch/period 97.4 61.7 82.0 Continuous Isotherms Catch 814 1,232 2,046 No. of periods 8 6 14 101.7 205.3 146-1 Av. catch/period 5 Figure 7.—Examples of discontinuous isotherms (7a) and continuous isotherms (7b) in the area of study. From examination of the temperature structure of the waters off northern Baja California and southern California based on half-month average temperature charts it appears that 1) initial warming of the waters to an average temperature of 68° F (20.0° C) is related to an increase in catch, 2) con- tinuity of the 68° F (20.0° C) or 70° F (21.1° C) average isotherms from off central Baja California northward to off southern California was associated with higher catches compared to catches when these isotherms were discontinuous. LITERATURE CITED CLEMENS, H. B., and W. L. CRAIG. 1965. An analysis of California’s albacore fishery. Calif. Dep. Fish Game, Fish. Bull. 128, 301 p. HESTER, F. J. 1961. A method of predicting tuna catch by using coastal sea-surface temperatures. Calif. Fish Game 47:313-326. HOWARD, J. K., and S. UEYANAGI. 1965. Distribution and relative abundance of billfish (Js- tiophoridae) of the Pacific Ocean. Stud. Trop. Oceanogr. (Miami), 2, 134 p. HUBBS, C. L. 1916. Notes on the marine fishes of California. Univ. Calif. Publ. Zool. 16:153-169. 1948. Changes in the fish fauna of western North America correlated with changes in ocean temperature. J. Mar. Res. 7:459-482. RADOVICH, J. 1961. Relationships of some marine organisms of the northeast Pacific to water temperatures, particularly dur- ing 1957 through 1959. Calif. Dep. Fish Game, Fish. Bull. 112, 62 p. 1963. Effects of water temperature on the distribution of some scombrid fishes along the Pacific coast of North America. FAO (Food Agric. Organ. U.N.) Fish. Rep. 6(3) Exp. Pap. 27:1459-1475. 193 SQUIRES. Ee7IR: 1972. Measurements of sea surface temperature on the eastern Pacific continental shelf using airborne infrared radiometry August 1963-July 1968. U.S. Coast Guard Ocean. Rep. 47, 229 p. U.S. BUREAU OF COMMERCIAL FISHERIES. 1961. Sea surface temperature charts, eastern Pacific Ocean. Jn California Fishery Market News Monthly Summary, Pt. 2 Fishing Information, January through December. U.S. Bur. Comm. Fish. Biol. Lab., San Diego, Calif. WALFORD, L. A. 1931. Northward occurrence of southern fish off San Pedro in 1931. Calif. Fish Game. 17:401-405. YOUNG, P. H. 1963. The kelp bass (Paralabrax clathratus) and its fishery, 1947-1958. Calif. Dep. Fish Game, Fish. Bull. 122, 67 p. Results of Sailfish Tagging in the Western North Atlantic Ocean’? FRANK J. MATHER III,? DURBIN C. TABB,° JOHN M. MASON, JR..,? and H. LAWRENCE CLARK* ABSTRACT Migrations of sailfish, /stiophorus platypterus (Shaw and Nodder), in the western North Atlantic Ocean are discussed on the basis of results of three cooperative tagging programs. The Rosenstiel School of Marine and Atmospheric Sciences (formerly Institute of Marine Science, and Marine Laboratory) of the University of Miami marked and released 1,259 sailfish between 1950 and 1958 and nine tags were returned. Members of the Port Aransas (Texas) Rod and Reel Club marked and released 515 sailfish between 1954 and 1962 and obtained three returns. The Cooperative Game Fish Tagging Program of the Woods Hole Oceanographic Institution has marked and released 12,525 sailfish between 1954 and May 1972, with 97 tags being returned. The majority of the returns showed limited movements; most were between localities along the southeast coast of Florida and the Florida Keys. The longer migrations did not follow a distinct pattern, but many of them showed a tendency toward movements between tropical waters (northeast coast of South America, the Lesser Antilles, and the Straits of Florida) in the cold season and temperate waters (the Gulf of Mexico and the United States coast between Jacksonville, Florida and Cape Hatteras, North Carolina) in the warm season. Times at liberty, which ranged from less than 1 day to over 4 yr, with only nine exceeding 18 mo, are generally consistent with earlier findings that the sailfish is a short-lived species. Tag returns give no indication of heavy commercial fishing pressure on the stocks under study. Sailfish have been tagged and released in the western North Atlantic Ocean more or less con- tinuously since 1950 through the cooperation of sport fishermen. Tagging was undertaken in order to study sailfish migrations and populations, as well as their mortality and growth rates. Another objec- tive was to learn whether enough sailfish survive capture to justify releasing them for purposes of conservation. Earliest efforts were designed to de- termine the feasibility of tagging, and the best methods and equipment for the purpose. The fish were tagged by cooperating sport fishermen with equipment supplied by three 1Contribution No. 2938, Woods Hole Oceanographic Institu- tion, Woods Hole, MA 02543. 2Contribution No. 1615, Rosenstiel School of Marine and At- mospheric Science, University of Miami, Miami, FL 33149. 3Woods Hole Oceanographic Institution, Woods Hole, MA 02543. *Dept. of Natural Resources, Comell University, Ithaca, NY 14850. 5Rosenstiel School of Marine and Atmospheric Science, Uni- versity of Miami, Miami, FL 33149. agencies—the Rosenstiel School of Marine and Atmospheric Science (RSMAS) (formerly the Insti- tute of Marine Science, and also the Marine Laboratory) of the University of Miami, Florida; the Port Aransas (Texas) Rod and Reel Club (PARR); and the Woods Hole Oceanographic In- stitution (WHOIT), Massachusetts. METHODS AND MATERIALS The RSMAS program began in 1950 and con- tinued through 1958. During that time tagging kits were distributed to 353 charter and private boat owners; 5,500 tags were distributed. Many of the participating anglers were members of fishing clubs or fishing guide associations who took responsibil- ity of local tag distribution in their area. Of the 353 anglers receiving tagging equipment, 83 tagged 1,262 sailfish. Of these 83 anglers, 25 tagged 83.8% of the total, or 1,058 fish. The tagged fish were re- leased in various areas off southeast Florida from Fort Pierce to Lower Matecumbe Key. Four different tag designs were tried during the course of the program. These were: 1. A monel metal “‘disc tag’’ fastened to the fish’s bill by two strands of silver wire. 2. A neoprene rubber ring with metal strip at- tached that was applied over the fish’s bill. 3. Clamp-on monel and stainless steel tags used to mark the ears of cattle (cattle tags), which were applied to the leading edge of the dorsal or pectoral fin. 4. The Woods Hole Oceanographic Institution ““Type B”’ (Fig. 1) dart tag inserted in the fish’s back muscles. A cera, ae N i ee ~ ERs Figure 1.—Types of tags used for sailfish in the Coopera- tive Game Fish Tagging Program of WHOI. The type B tag was also one of those used in the Cooperative Sailfish Tagging Program of RSMAS. PARR members marked 395 sailfish with monel cattle tags (similar to number 3 in the list of tags used by RSMAS), supplied by the club, in the years 1954-1962. The members of PARR began cooperat- ing actively with the WHOI program, using WHOI tags, in 1957, and gradually phased out the use of PARR monel ear tags. The tagging was carried out in the immediate vicinity of Port Aransas. Sportsmen cooperating with WHOI have tagged over 12,000 sailfish since 1954 with various types of dart tags (Mather, 1963) (Fig. 1). The majority of the tagging was concentrated along the southeast coast of Florida and the Florida Keys, but impor- tant numbers of fish were also tagged in the Gulf of Mexico, off the Bahamas, off the Virgin Islands, off Venezuela, and off the Yucatan Peninsula. Lesser numbers were tagged off northeastern Florida, North Carolina, Maryland, and Delaware. RESULTS From March 1950 through 15 July 1972, 14,299 sailfish have been tagged and released; 109 returns have resulted. The releases and returns are sum- marized by year, area of release, and program in Table 1. The release and recapture data for the re- turns, grouped according to release area and, for the southeast Florida area which comprises most of the returns, by recapture area also, are listed in the Appendix. The monthly distribution of tagging ef- fort in each release area is shown in Table 2. The times at liberty for the recaptured sailfish are sum- marized in Table 3. The fishing methods by which they were recaptured, and the nationalities of the recapturing vessels, are shown in Table 4. Tag Returns The majority (9,710) of the releases were off the southeastern coast of Florida and the Florida Keys (between Fort Pierce and Key West). The majority (80) of the returns were from these releases (Table 1). Most of these recaptures (73) were in this same area, but two were near Havana, three in the Gulf of Mexico, one off North Carolina, and one off the Bahamas (Fig. 2; Appendix Table 1). Among the returns from the release area, the net distance traveled was undeterminable for four and less than 20 miles for 21 (Appendix Table 2), more than 20 miles northward from the release site for 16 (Ap- pendix Table 3), and more than 20 miles southward from the release site for 32 (Appendix Table 4). Table 1.—Releases (after slash) and returns (before slash) for sailfish, by years, areas, and programs. Returns are listed by year and area of release. Hatteras- NE SE Gulf of Mexico Haiti & Caribbean Caribbean Area Delaware Florda Florida Bahamas Fla. & La. Texas Virgin Is.? SE NW Program WHOI WHOI WHOI RSMAS WHOI WHOI WHOI PARR WHOI WHOI WHOI Totals Year 1950 1/78 1/78 1951 1/112 1/112 1952 2/102 2/102 1953 1/140 1/140 1954 0/27 0/299 0/76 0/402 1955 1/15 0/201 0/1 1/44 2/261 1956 1/167 0/34 1/201 1957 0/17 2/142 0/7 0/13 2/179 1958 2/7 0/17 0/21 0/36 2/81 1959 0/72 0/1 0/33 1/49 0/7 1/162 1960 0/2 5/746 0/4 0/3 0/22 0/196 0/5 0/44 0/1 §/1,023 1961 0/1 0/1 5/949 0/9 0/S 0/182 1/64 1/3 0/7 7/1,221 1962 0/2 0/4 10/1,141 0/32 0/3 0/93 0/3 0/9 10/1,287 1963 0/4 9/1,000 0/45 0/1 0/102 0/10 9/1,162 1964 0/2 6/925 0/73 0/9 0/60 0/S 0/6 6/1,080 1965 0/1 0/3 7/928 1/34 0/95 1/17 0/15 9/1,093 1966 0/2 0/1 9/565 0/57 0/4 0/152 1/150 7/186 0/22 17/1,139 1967 0/1 1/2 6/385 1/34 2/52 0/188 3/67 0/53 0/46 13/828 1968 6/420 2/43 1/220 1/54 0/20 0/3 0/15 10/775 1969 1/15 3/339 0/71 1/24 0/154 0/53 0/60 0/47 5/763 1970 0/28 0/2 1/254 0/38 0/71 0/73 0/47 0/32 0/76 1/621 1971 0/22 0/2 1/449 0/39 0/35 0/76 0/75 0/31 1/351 2/1,080 1972? 0/212 0/29 0/2 1/95 0/1 0/169 1/508 Unknown 1/1 1/1 Totals 1/80 1/15 71/8,451 9/1,259 4/508 4/429 1/1,314 3/515 7/546 7/439 1/743 109/14,299 1 Haiti-1960-1962, Virgin Islands 1964-1967. ° Through May. The releases in. this area were mainly (64.7%) in the period November-February, with a secondary period (14.1%) in April-May. The returns within the release area followed a similar pattern, with major- ity (44) in the period November-February, but March was the most productive among the other months, with seven returns (Appendix Tables 2-4). The recapture off North Carolina was in July; the one off the Bahamas in December; the two off Havana in May and August; and the three in the Gulf of Mexico also in May (one) and August (two) (Ap- pendix Table 1). Five hundred and eight sailfish were tagged off the northwestern Bahamas, and four of these tags have been returned (Table 1, Fig. 2, Appendix Table 5). One of these was recaptured off the Florida Keys, one off Cabo Cruz on the southeastern coast of Cuba, two off Havana. Unfortunately there is some doubt about the identity of the last two fish, since the fisherman who recaptured them reported 196 that they were sailfish, but the taggers had listed them as white marlin. The releases off the northwestern Bahamas are concentrated in April-July (80%) with a good number (8%) in August (Table 2). The two recap- tures off Havana were in May and July, the one off southeastern Cuba in March, and the one in the Florida Keys in May (Appendix Table 5). Fishermen have released 2,358 sailfish in the Gulf of Mexico (1,829 near Port Aransas, Texas, and 429 in the north central and northeastern Gulf) and eight returns have resulted, including four from each area (Table 1, Fig. 2, Appendix Table 6). Two of the recaptures (one in each area) were local. The other three returns from sailfish tagged off Port Aransas showed migrations to the Florida Keys, the vicinity of Palm Beach, Florida, and off the north central coast of Cuba. The remaining three sailfish tagged in the northeastern Gulf were recap- tured near Havana, off the northeast coast of Cuba, and west of Grenada in the Lesser Antilles. The releases off Texas were virtually all in sum- mer, with the majority in July (34%) and August (33%). Those off the Mississippi delta and western Florida were somewhat later, with the maximum in September (49%) and October (34%), and a good number in August (10%) (Table 2). The local re- coveries corresponded with the peak of tagging, oc- curring in August off Port Aransas and in Sep- tember off Pensacola, Florida. The distant re- coveries were scattered in time and location—off Havana in October, near Palm Beach in December, off northeastern Cuba and off Grenada in January, off the Florida Keys in March, and off north central Cuba in May (Appendix Table 6). Five hundred and twenty-nine sailfish have been tagged off the Virgin Islands, mostly in the period November-March, and six of these tags have been returned (Tables 1 and 2, Appendix Table 7). Two of the returns were local, and in the peak tagging season (December and February). The other recap- tures were widely scattered geographically (Fig. 2), but all occurred between mid-March and the end of June. One was in the Mona Passage (off the Dominican Republic) in March, one off Fort Lauderdale, Florida, in May, and the other two Table 2.—Monthly distribution of releases of sailfish in the western North Atlantic Ocean, by tagging areas. Releases are tabulated in percent of the total number (NV) for each area. — indicates less than 0.5%. Percent of Releases, by Months Area Ja Fe Ma Ap My Ju Jl AuSe OcNoDe WN Southeastern Flonda 24102535 (Sie 6p 435 378) Sa100 2199455 Northwestern Bahamas —e2u tA DEG eLSil4wo 72-93) ee 47/9 Northwestern Gulf of Mexico — 6343325 2 1,827 North Central & Northeastern Gulf of Mexico 2 510 49 34 — 429 Virgin Islands 3114 14 1 1 56) 119) 1354433 Southeastern Canbbean 8 el 559127 18521 10) — 22438 Northwestern Caribbean 22 46 1610 3 PWN SH! Haiti 65 6 17 44 22 18 Northeastem Florida & Georgia 27 60 13 15 Cape Hatteras —Delaware y/241033 nl 6m? 80 _ Table 3.—Releases for sailfish in the western North Atlan- tic Ocean by years, and returns from these by months at liberty. Releases Months at Liberty O- I- 2- 6 12- 18- 24 36- 48- Year Number .9 1.9 5.9 11.9 17.9 23.9 35.9 47.9 59.9 Total 1950 78 1 1 195] 112 I ] 1952 102 2 2 1953 140 1 1 1954 402 1955 261 1 1 ) 1956 201 1 1 1957 179 1 1 2 1958 81 1 2 1959 162 1 1 1960 1,023 2 a) 1 1 5 1961 14221) 21 2 yh Dated 1] 1962 128 Jie 2a lel 1 10 1963 S162: Scent 4s eal 9 1964 IKOS0) 2 Pe a) 1 6 1965 12093) nie2) eel 2 0 3 1 9 1966 1139 5 4 4 2 1 1 17 1967 CPA) pe eg tI 1 13 1968 TE 3 MW Al VB 1 1 10 1969 GCS WA 2 1 5 1970 62i1aal 1 197] 1,080 2 2 1972 508 1 1 Unknown 1 1 All Years) 145299 23 12 28 25 11 5 3 1 109 were in June—one off the northeastern tip of the Yucatan Peninsula, and the other off Charleston, South Carolina. Fishermen have released 438 sailfish in the southeastern Caribbean, nearly all of them in the vicinity of La Guaira, Venezuela (Fig. 2), and seven of these tags have been returned (Table 1, Appendix Table 8). Most of the tagging (66%) was in the period July-October, with 8 to 10% in each of the months of July, November, and February (Table 2). Six of the recaptured fish had been tagged near La Guaira; the other was released about 60 miles west of there. All were recaptured in the vi- cinity of La Guaira. The recaptures were spread over much of the year, with one in each of the months of January, May, June, July, and August, and two in September. Five hundred and seventy-four sailfish have been tagged in the northwestern Caribbean, nearly all of them along the Yucatan coast opposite Cozumel Island, Mexico, but only one of these tags has been returned (Table 1, Appendix Table 9). The tagging was concentrated in April-June (84%), with 10% in August (Table 2). The single recapture was near the easternmost end of the Caribbean coast of Ven- ezuela in December (Fig. 2). Eighty sailfish have been tagged off the U.S. coast from Cape Hatteras to Delaware Bay, nearly all in summer, and one of these has been recaptured (Tables 1 and 2, Appendix Table 9). This tag was recovered in March off the Guianas (Fig. 2), about 1,920 miles (3,070 km) from the release point, rep- resenting the longest migration yet recorded for a sailfish. One return was obtained from only 15 releases off northeastern Florida and Georgia, most of them in the vicinity of Jacksonville, Florida, in June and July (Tables 1 and 2, Appendix Table 9). This fish was recaptured off Fort Lauderdale, Florida, in Oc- tober (Fig. 2). Another small group of releases, 18, off Haiti likewise produced a single return (Table 1, Appen- dix Table 3). Most of the releases were in October-December (Table 2), but the recaptured fish was tagged in May. It was recaptured in the release area, off Port-au-Prince, in January (Fig. 2). The times at liberty which are available for tagged and recaptured sailfish are summarized in Ta- ble 3. Although the maximum was over 4.5 years, the majority of the times at liberty were of very short duration. Fifty-eight percent were less than 6 mo, and 90% were less than 18 mo. The methods of recapture, and the nationality of recapturing vessels, are shown in Table 4. Eighty- two percent of the known recaptures were by sport fishermen, nearly all of whom were from the United States. Eighteen percent were by commercial fishermen using various types of hook-and-line gear. Most of these were by Cuban fishermen (nine re- turns) and Venezuelan fishermen (seven returns). Japanese longline vessels produced only one valid return, but also returned a dart found in a sailfish recaptured in the Gulf of Mexico in August 1971. Since the streamer, which carried the serial number, had been lost, the release data were unavailable. DISCUSSION Migrations Although tag returns have produced much infor- mation on migrations (Fig. 2) and local movements of sailfish, it is difficult to detect regular patterns on a geographical basis. If one considers water tem- peratures, however, some general tendencies be- come discernible. Eight sailfish tagged in temperate areas (six in the northern Gulf of Mexico, one off Jacksonville, and one off Cape Hatteras) mainly during the warm season (releases between 8 June and 18 October) were recaptured in tropical waters (three off the north coast of Cuba, three off south- eastern Florida and the Florida Keys, and two near the northeastern coasts of South America) mainly in the cool season (recaptures between 10 October and 20 May) (Appendix Tables 6, 9). Five sailfish tagged in tropical areas (four near Palm Beach, Florida, and one off the Virgin Islands) mainly dur- ing the cool season (releases between 8 December and 10 May) were recaptured in temperate areas (three in the Gulf of Mexico and two off the Carolinas) mainly during the warm season (recap- tures from 22 May through 2 August) (Appendix Tables 1,7). ° Some movements within tropical waters may have been parts of similar migrations. Three sailfish tagged off the Virgin Islands in January and Feb- ruary were recaptured as follows: in the Mona Pas- sage (off the Dominican Republic) in March (2.1 mo at liberty); in the Yucatan Channel (northeast of Table 4.—Tag returns from sailfish released in the west- ern North Atlantic Ocean, by methods of recapture and nationality of recapturing vessel. Sport Bahamas Rod and Reel 1 United States Rod and Reel 86 Venezuela Rod and Reel 2 Sport total 89 Commercial British West Indies Handline 1 Cuba Longline 4 ““Criollo”’ line 5 Dominican Republic Handline 1 Haiti Deepline 1 Japan Longline 1 Venezuela **Professional 6 Fishermen” Longline 1 Commercial total 20 All Methods Grand total 109 Figure 2.—Longer migrations shown by returns from sail- fish tagged in the western North Atlantic Ocean. Migra- tions entirely within the Straits of Florida are not shown. 239 Od 1 — pep — pp — pet — er =d3s- xian Bay das-d3s Nur -9ny| nr - nner . Nar-Nor Ske SVOVEVQ, INV-Ud 6 AVW- NUE onv-Nvr oungsua.ad c, nh \ KITA 190 Bq -NOSNdur E ALIO VNVNYd SeeeiTg = SNd¥od hy: Of "8@jNO4 UO|OsGIW jUesesdes A\l408S090U JOU OP pud d1;0WWOUBOIP e410 seunjdod s -04 PUD SesD9}0J BulUIo! seul ‘UMOYs jou GUD OpIi0) 4 H NOLS3TYVHO WJ9{SO94INOS 4DOU 10 Jj0 POsNJdODe1 PUD PesDe}e1 YBIy :S3LON | I HLNOW JO 39N3YNNDIO HIsIs = HINOW 30 3ON3YYNDIO GNOD3SS ay @N19 133y 8 GOY SYSNVYV LY0d ALID QV3H3NON Se [e) 3yuNLdVO3y V e 3Sv313y v svi IOHM sovl yuuvd HSISTIVS OLLNV OLY 199 the Yucatan Peninsula) in June (4.1 mo at liberty); and off Fort Lauderdale, Florida, in May (4.0 mo at liberty) (Appendix Table 7). The first two fish might have been on their way to the northern Gulf of Mex- ico, or, as the third could also have been, to the Jacksonville-Cape Hatteras area. A sailfish released off Palm Beach in January and recaptured off Havana in May (3.3 mo at liberty) (Appendix Table 1) might well have been en route to the northern Gulf of Mexico. Thus the majority (eight) of the 13 recorded sail- fish migrations between temperate and tropical waters were between the northern Gulf of Mexico in the warmer season and the waters off southeast- ern Florida and the north coast of Cuba in the cooler season. Similar migrations have been re- corded for tagged white and blue marlins (Mather, Jones, and Beardsley, 1972; Mather, Mason, and Clark, 1974), although several of these originated off the northwestern Bahamas. There seems to be a strong tendency for sailfish, as well as other bill- fishes, to spend the warm-water season in the northern Gulf of Mexico, and the season when the waters there are cool, in the Straits of Florida and adjacent waters. Gibbs (1957) showed the white marlin distribution in the Gulf of Mexico was closely related to the seasonal movements of the 75°F (23.9°C) isotherm. Since the range of the sail- fish does not extend into waters as cool as that of the white marlin (Ueyanagi et al., 1970) it seems probable that the position of the 25°C isotherm might control their distribution. Similar, but less frequent, seasonal changes of habitat by tagged sailfish have been between the Straits of Florida and the Virgin Islands in the cool season and the Jacksonville-Cape Hatteras area in the warm season (two northward migrations and one southward); and between the latter area and the Gulf of Mexico in the warm season, and waters near northeastern South America in the cool season (two southward migrations) (Fig. 2, Appendix Ta- bles 1, 6, 7, 9). Like the more numerous seasonal migrations between the Gulf of Mexico and the Straits of Florida area, these migrations may be re- lated to the seasonal temperature changes in the summering areas. The data are insufficient to de- termine whether different stocks occupy the two summering areas (Gulf of Mexico, Jacksonville- Cape Hatteras) or not. It seems highly probable, however, that fish from these two summer habitats mingle with each other in three wintering areas —Straits of Florida, Virgin Islands, and off South 200 America. Since the recovery of tags is probable in only a few relatively small areas of intensive fish- ing, the picture obtained from tag returns may be misleading. It is quite likely that the seasonal habitats of sailfish are considerably larger than is indicated here. Possibly the wintering area is con- tinuous from the Straits of Florida and the north- western Bahamas to northeastern South America. In contrast to the long migrations recorded from other areas where numerous sailfish have been tagged, all seven returns from the 439 releases off Venezuela have been local even though times at liberty have ranged up to 54.8 mo (Table 2, Appendix Table 8). This is a strong indication that most of the sailfish there are of a local stock, or one which does not enter other areas of intensive fish- ing. Tag returns (Fig. 2) suggest, however, that sail- fish from the northern Gulf of Mexico, the Jacksonville-Cape Hatteras area, and off the north- eastern coast of the Yucatan Peninsula may mingle with those off Venezuela. The extremely low return rates for sailfish tagged off Yucatan and in the northwestern Gulf of Mex- ico (Table 2) suggest that these fish may also be of stocks which do not often enter other areas of in- tensive fishing. It is also surprising that, with 9,710 sailfish tagged off southeastern Florida and 508 tagged off the northwestern Bahamas, only two migrations (one in each direction) between these areas have been re- corded (Appendix Tables 1, 5). This small amount of mixing again raises the possibility of separate stocks. In view of the present low rate of return from sailfish tagging, it seems especially important to conduct genetic studies of sailfish in the respective areas to identify the stocks or populations. Perhaps the tagging results could assist in the selection of sampling periods and areas when mixing of fish from different areas is least probable. The numerous local movement records within the Fort Pierce-Key West area (southeastern Florida) are very difficult to analyze (Appendix Tables 2, 3, 4). More southward (32) than northward (16) migrations were recorded, but this may only reflect the fact that the majority of the tagging occurred in the northernmost part of this area (Palm Beach- Fort Pierce). Fishing effort from Palm Beach southward to Key West is intense, whereas it is relatively light north of Fort Pierce. Most of the tagged sailfish which migrated northward in the area were released in October-April and recaptured in December-February; most of those which mi- grated southward were released in November- February and recaptured in November-March. Most of those recaptured within 20 miles (32 km) of the release point were released in November- January and June, and recaptured in November- December and February-April. The longer north- ward migrations (Key West-Marathon to Palm Beach-Stuart) were by four fish, released in March, April, October, and November and recaptured in December, January, May, and July. The longest southward migrations (Palm Beach-Stuart to Key West-Islamorada) were by four fish, released in January, March, and April, and recaptured in January, February, March, and July. There seems to be little consistency in these data. Two rather rapid southward migrations along the Florida coast have been recorded; from off Jupiter to off Fort Lauderdale in 2 days, and from off Hills- boro Inlet to off Miami in the same period. It might be of interest to check such migrations against historical weather data. Fishermen in the area often observe sailfish riding the downwind face of waves with the upper lobe of their caudal fin’ showing (‘‘tailing’’), particularly during the brisk northerly winds which herald cold weather. Growth and Survival Since sizes at release are estimated, and the qual- ity of recapture data is difficult to evaluate, espe- cially in regard to length measurements, no valid growth data are available. In the WHOI program in- structions, the cooperating taggers are asked to mea- sure the length of the head of each billfish tagged, which would permit a close estimate of the body length of the fish. No taggers have done this. Besides the extra time and trouble involved, this procedure might well increase the risk of injury to both fish and tagger. Several sailfish were recap- tured after from 1 to 4 yr at liberty. These do not appear to have been especially small when tagged, or especially large when recaptured. This may be an indication that the species does not grow very fast after reaching the age of recruitment to the fishery. Eighty-eight of the 108 recaptured sailfish for which time at liberty was known, at least approxi- mately, were recaptured less than a year after being tagged. Only 11 more had been at liberty for 12-18 mo, and an additional five for 18-24 mo. Thus only four were recaptured after from 2 to 5 yr at liberty. These results are in good agreement with de Sylva’s 201 (1957) work, which indicated that the life span of the species was short. The question of the survival of released fish re- mains unanswered. The low return rate for tagged sailfish could be an indication of high tagging mor- tality. Return rates also depend on the percent of the stock which is caught, as well as on natural mortality, tag shedding, and other factors. Return rates for white marlin and small bluefin tuna were even lower than those for sailfish in the years 1954-1961, but, with the increased fishing effort for these species, the rates for white marlin have risen appreciably, and those for small bluefin have be- come alarming (FAO, 1968; Mather, Jones, and Beardsley, 1972; Mather et al., 1974). Only two rather small and localized commercial fisheries have returned significant numbers of sailfish tags; over 80% of the tags have been returned by sport fishermen. In the absence of an effective commer- cial fishery, a high return rate from such a short- lived and widely ranging species can hardly be ex- pected. Experiments to study the survival of tagged fish, possibly through the use of acoustic tags, are needed to settle this important question. Comparison of Tag Types Data from the early years provide indications of the practicality and effectiveness of the various types of tags. In the RSMAS program, the disc tag was soon discarded because of the difficulty en- countered by the fishermen in twisting the wires to assure a snug fit on the bill without keeping the fish out of water too long. The neoprene rubber ring was discarded after a single recapture showed that the pressure of the rubber on the bill was actually sever- ing the bill. The cattle tags were popular with the anglers; they could be applied quickly. However, they were often knocked from the special pliers by the struggling fish and the pliers used to apply them were expensive. The ‘‘Type B’’ Woods Hole dart tag was the most popular with anglers since the fish could be tagged without handling them (Mather, 1963). On the basis of recoveries, the cattle tag and the Woods Hole Type B dart tag were about equally effective. There is reason to believe that some tags may have been overlooked by anglers since some of those that were recovered had goose barnacles and algae attached to them and could not be recognized easily. In the tagging off Port Aransas, however, the cat- tle ear tags used in the PARR program produced a much higher return rate (0.7%) than the dart tags used in the WHOI program (0.1%). The results with the various types of dart tags used in the WHOI program (Fig. 1) have not been completely analyzed. Experience has shown, how- ever, that the dart tags with plastic heads (types D and E) are not as practical for tagging under the conditions of this program. The applicators are mounted on the end of a pole 1.0-1.5 m long, and the fish are tagged without removing them from the water, and preferably without handling them (Mather, 1963). Under these circumstances, the plastic heads of the type D and E darts are fre- quently broken. The broken tags often jam in the tubular applicators which are used for these tags, and the applicators themselves are easily damaged and difficult to repair or replace. The tags with stainless steel darts (types A, B, C, H, M, N and WH), which are used with slotted, solid stainless steel applicators, are much more rugged and trouble free, and do not jam in the applicators. The ap- plicators themselves are also more rugged than the tubular ones, and are much more easily repaired or replaced when damaged. There has been no evi- dence that the stainless steel dart is more injurious to the fish than the plastic one, as was feared. There was some evidence that the streamers sometimes separated from both types of darts, be- cause of glue failure, defective assembly, or insuffi- cient basic mechanical strength. The WH tag, with the serial number on the dart as well as the streamer, was developed with financial assistance from P.A.B. Widener in hopes that valid returns could be obtained even if the streamer had been lost. Perhaps due to insufficient publicity, or perhaps because this separation did not occur as often as was supposed, these tags have not pro- duced any significant increase in return rates. Re- cent improvements in the construction of type H, N, and WH tags, however, have so increased their uniformity and mechanical strength that we do not believe that tag separation will be a significant fac- tor. SUMMARY 1. The data suggest seasonal migrations between summering areas in temperate waters (Gulf of Mex- ico, U.S. coast from northern Florida to North Carolina) and wintering areas in tropical waters (Straits of Florida, West Indies, north coast of bo South America). These migrations may be related to the location of the 25°C isotherm. 2. The extremely localized nature of the intensive southeast Florida sport fishery makes the local movements within that area difficult to interpret. More tagging in other areas might produce more significant results. 3. There are some indications of separate stocks, but, if they are indeed separate, many of them probably mingle with others. 4. No reliable growth data were obtained. The results suggest, however, that the growth rate of sailfish decreases rather rapidly with increasing size of fish. 5. Times at liberty for recaptured sailfish ranged up to 5 yr, but 95% were less than 1 yr. These results indicate that the life span of the species is short. 6. Over 80% of the returned tags were recaptured by the sport fishery. This indicates that commercial fishing pressure on the stocks under study is slight. 7. Tag return rates of less than 1% do not suggest a high survival rate for released sailfish. 8. This low return rate may be caused by low fishing mortality and the short life span of the species. Direct studies of the survival of released fish are required. 9. The cattle ear tag and the dart tag proved to be the most practical of the types which were used for tagging sailfish. The former produced higher return rates than the latter, but the dart tag equipment is less costly and easier to use. The dart tags with metal heads were generally more satisfactory than the ones with plastic heads. ACKNOWLEDGMENTS The authors are most grateful to all the organiza- tions and individuals who have assisted this re- search. Funding for the RSMAS program was pro- vided by the Florida State Board of Conservation. The principal financial support of the WHOI program since 1956 has been from the National Science Foundation (Grants G-861, G-2102, G-8339, G-6172, G-19601, GB-3464 and GH-82), the Bureau of Commercial Fisheries (now National Marine Fisheries Service) (Con- tracts 14-17-0007-272, -547, -870. -975, and -1110), and the Office of Sea Grant, National Oceanic and Atmospheric Administration, U.S. Department of Commerce (Grant GH-82). Important additional support has been received from the Sport Fishing Institute; the Charles W. Brown, Jr. Memorial Foundation; the Tournament of Champions (through Mrs. R.C. Kunkel and E.D. Martin); A. Minis, Jr.; the Joseph A. Teti, Jr. Foundation; the Port Aransas Rod and Reel Club; P.A.B. Widener; the Jersey Cape Fishing Tournament; the As- sociates of the Woods Hole Oceanographic Institu- tion; and many other sportsmen’s organizations and individual sportsmen. The National Marine Fisheries Service and its predecessor, the Bureau of Commercial Fisheries, the Inter-American Tropical Tuna Commission, the Fisheries Research Board of Canada, the Food and Agriculture Organization of the United Na- tions, and many other national and private research organizations have assisted in the promoting of the tagging of fishes, the collection and processing of data, and the dissemination of information on the program and its results. The contributions of Donald P. de Sylva and Gilbert L. Voss are espe- cially appreciated. The tagging results were made possible by the thousands of anglers, captains, and mates who have tagged, and released many of their catches, and the clubs, committees and individuals who have en- couraged tagging. We regret that space does not permit individual acknowledgements here; the major participants are listed in the informal pro- gress reports which are issued periodically by WHOI. Most of the participants in the RSMAS and PARR programs have also participated in the WHOI program. The press and the broadcasting media have also done much to encourage tagging and the return of tags. 203 LITERATURE CITED DE SYLVA, D. P. 1957. Studies on the age and growth of the Atlantic sailfish, Istiophorus americanus (Cuvier), using length-frequency. curves. Bull. Mar. Sci. Gulf Caribb. 7:1-20. FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS. 1968. Report of the meeting of a group of experts on tuna stock assessment (under the FAO Expert Panel for the Facilitation of Tuna Research). Miami, U.S.A., 12-16 August 1968. FAO Fish. Rep. 61, 45 p. GIBBS, R. H., JR. 1957. Preliminary analysis of the distribution of white mar- lin, Makaira albida (Poey), in the Gulf of Mexico. Bull. Mar. Sci. Gulf Caribb. 7:360-369. MATHER, F. J., Ill. 1963. Tags and tagging techniques for large pelagic fishes. Int. Comm. Northwest Atl. Fish., Spec. Publ. 4:288- 293. MATHER, F.J., III, A.C. JONES, and G.L. BEARDSLEY, JR. 1972. Migration and distribution of white marlin and blue marlin in the Atlantic Ocean. Fish. Bull., U.S. 70:283-298. MATHER, F.J., Il], JM. MASON, JR.,and H.L. CLARK. 1974. Migration of white marlin and blue marlin in the west- ern North Atlantic Ocean—tagging results since May 1970. In Richard S. Shomura and Francis Williams (editors), Proceedings of the International Billfish Sym- posium, Kailua-Kona, Hawaii, 9-12 August 1972, Part 2. Review and Contributed Papers. U.S. Dep. Comm. NOAA Tech. Rep. NMFS SSRF-675, p. 211-225. UEYANAGI, S., S. KIKAWA, M. UTO, NISHIKAWA. 1970. Distribution, spawning, and relative abundance of bill- fishes in the Atlantic Ocean. Bull. Far Seas Fish. Res. Lab. (Shimizu) 3:15-55. and Y. APPENDIX Release and recapture data for returns from sailfish tagged in the western North Atlantic Ocean, March 1950-May, 1972, are given in nine Appendix Tables. divided according to recapture areas. reported in inches and pounds have been converted to centimeters and kilograms. Release data Date Feb. 10, 1960 May 10, 1963 Apr. 13, 1964 Nov. 20, 1964 Jan. 28, 1966 Jan. 19, 1966 Dec. 8, 1966 1 The returns are grouped by area of release, except that the large group from releases of southeastern Florida is further In each group, the returns are listed in order of date of recapture. Data in parentheses are extimated or approximate. APPENDIX TABLE 1: Locality Estimated size Lat N Long W Length Weight om kg (26°45! 79°55") (210) (26°45! 79°55") (220) (26°32! 80°00') (210) (18.2) (27°04' 80°03") (220) (19.1) (26°45! 79°55") (26°56! 80°00') (200) (26°45! 79°55") (9.1) RR, rod and reel; LL, longline Sailfish tagged off southeast Florida and the Florida Keys and recaptured in other areas. Lengths and weights which were Recapture data Date May 22, 1960 July 25, 1963 Aug. 2, 1964 Dec. 4, 1964 May 8, 1966 Aug. 5, 1966 Aug. 1, 1967 aoe Pe Local tyes Gin ease S12 CRE Meee Cane! Lat N Long W Length Weight em kg 27°40" 83°45" (180) RR 34°19! 76°17! 201 RR 27°28! 92°27" LL 26°54" 79°07" RR 23°10! 82°25! 192 18.2 LL (23°10" 82°25") 14.1 LL 29°55! 85°52! 203 RR 204 Flag USA USA Jap. Bah. Cuba Cuba USA Months at Liberty 3.4 2.5) 3.6 0.5 3.3 6.6 7.8 APPENDIX TABLE 2: Sailfish tagged off southeast Florida and the Florida Keys and recaptured less than 20 miles or an undeterminable distance from the release site. Release data Recapture data Months at Date ——___Locality _Estimated size _ Date aaeese Local i tyke es ee en Size seer esl Flag Liberty Lat N Long W Length Weight Lat N Long W Length Weight cm g cm *Oct. 1, 1957 (26°32! 80°00") Oct. 1, 1957 (26°32! 80°00") RR USA 0.0 *Unknown Nov. 5, 1957 (26°15 80°00") RR USA Feb. 6, 1960 (27°04! 80°00') (200) Jan. 18, 1961 (27°10! 80°00") (230) (21.6) RR USA 11.4 Dec. 23, 1960 (26°45! 79°55') (190) Jan. 23, 1961 (26°45' 79°55") 214 20.4 RR USA 1.0 Apr. 3, 1962 (26°32! 80°00') (150) (9.1) Sept. 8, 1962 (26°15' 80°00") 188 12.5 RR USA 5 Mar. 1963 (26°32' 80°00") Mar. 1963 (26°32" 80°00') 221 RR USA Mar. 1963 (26°15" 80°00") June 1963 (26°32! 80°00") RR USA 3 Nov. 1963 (26°13" 80°03') (210) Nov. 28, 1963 (26°05! 80°05") 216 21.8 RR USA 123 Sept. 27, 1963 (26°20' 30°02") (18.2) June 30, 1964 (26°0S' 80°05") 211 14.5 RR USA 9 Dec. 28, 1964 (26°56! 30°00") 228 Dec. 28, 1964 26°57! 80°02! RR USA 0 Dec. 10, 1965 (26°45! 80°00') (200) Dec. 11, 1965 26°45! 79°58! 211 27.2 RR USA Nov. 27, 1965 (26°54! 80°00') (220) (21.8) Dec. 22, 1965 (26°32! 80°00") 224 22.8 RR USA 0.8 Nov. 30, 1965 (26°15' 80°00') (210) Jan. 17, 1966 (26°31! 80°00") 214 24.6 RR USA 1.6 Dec. 1, 1965 (26°45" 79°55") (210) (18.2) Nov. 13, 1966 (26°32! 80°00") 202 17.7 RR USA 11.4 Dec. 12, 1965 (26°32! 80°00') (190) (13.6) Nov. 14, 1966 (26°20! 30°02") 173 9.1 RR USA 11.0 Dec. 28, 1966 (26°56! 80°00") (18.2) Jan. 2, 1967 (27°10! 80°00') 214 (21.6) RR USA 0.2 Apr. 29, 1967 (26°05! 80°0S') (27.2) June 5, 1967 25°45! 80°06' 27.2 RR USA 2 Jan. 17, 1967. 27°01" 80°02" Unknown RR USA Feb. 11, 1967 (26°45! 79°55") Unknown (210) (eu) RR USA Jan. 2, 1967 (27°03! 80°04") Unknown (210) ~=—(17) RR USA Feb. 4, 1966 (26°21! 80°03') (200) Dec. 7, 1967 (26°21! 80°03") 208 RR USA 22.1 Unknown (26°45" 79°55") Feb. 10, 1968 (26°54' 80°00') 214 RR USA Feb. 2, 1968 27°23! 80°02! Feb. 18, 1968 27°09! 80°03! 201 15.7 RR USA Dec. 8, 1967 (26°21 80°03") (200) Apr. 18, 1968 26°38! 80°00! 218 RR USA Jan. 3, 1968 (26°45" 79°55") (20.4) Jan. 3, 1969 (26°35! 80°00") 221 25.4 RR USA 12.0 {Gi Mea lina: Tl. li— > \>) [ae a Se RR, rod and reel *Fish tagged under program sponsored by the Rosenstiel School of Marine and Atmospheric Science (RSMAS) 205 APPENDIX TABLE 3: Sailfish tagged off southeast Florida and the Florida Keys and recaptured in the same area more than 20 miles northward from the release site. Release data Recapture data Date ee LOC Lt Ye Ea LiMaLeGESIZe! Date Local ty ie ears Flag ae Lat N Long W Length Weight Lat N Long W Length Weight TS lL SS nn nnn. | a Onn, a a a EEE i. *apr. 4, 1952 24°51! 80°36! July 12, 1952 (25°45! 80°00") RR USA 3,3 *July 16, 1957 25°45! 30°06" (200) Sept. 15, 1958 27°10! 80°03" 216 RR USA 14.0 Jan. 28, 1958 (26°45' 79°55") (220) Jan. 14, 1959 (27°10! 80°00") 219 18.2 RR USA 11.5 *Feb. 19, 1956 24°51! 30°36! (200) (9.1) Feb. 12, 1959 (26°28! 80°02") 216 21.8 RR USA 35.8 Mar. 2, 1961 (26°13! 80°00") (210) cas) Jan. 19, 1962 (27°27! 80°05") 213 RR USA 10.6 Mar. 16, 1962 (24°38! 81°06") (170) Dec. 15, 1962 (26°32" 80°00') (180) (12.5) RR USA 9.1 Dec. 24, 1962 (26°13' 80°03") (200) (13.6) Feb. 22, 1963 (26°45! 79°55") 206 14.1 RR USA 2.0 Dec. 6, 1963 (26°45' 79°55") (190) (14.5) Dec. 7, 1963 27°13! 80°03" 185 13.6 RR USA Nov. 27, 1964 (26°13' 80°03") — (200) Dec. 29, 1964 (26°56! 80°00") (230) RR USA 1.0 Apr. 25, 1966 (24°40! 81°05") (16) Jan. 3, 1967 27°12! 80°0s' (224) (22.8) RR USA 8.3 Mar. 12, 1968 25°12! 80°14" Apr. 29, 1968 25°53! 0°0s' RR USA 1.6 Jan. 21, 1969 (26°45! 79°55") (18.2) Jan. 24, 1969 27°28! 79°59! (180) (13.6) RR USA 0.1 Nov. 15, 1968 (24°40! 81°05') (180) (11.4) May 18, 1969 (26°45! 79°55") 173 RR USA 6.0 Oct. 26, 1969 (24°40! 81°05') (190) (18.2) Dec. 1, 1969 (25°45! 80°00') 216 24.6 RR USA 1.2 Oct. 12, 1969 25°33! 80°05" (22.8) Dec. 23, 1969 26°57! 80°03! 224 24.1 RR USA 2.3 Oct. 25, 1971 (24°30! 81°45') (210) (18.2) July 1972 (26°45! 8000") 206 RR USA 8.3 Q RR, rod and reel * Fish tagged under the program sponsored by RSMAS 206 APPENDIX TABLE 4: Sailfish tagged off southeast Florida and the Florida Keys and recaptured in the same area more than 20 miles southward from the release site. Release data pl ae eee ree iates Wi cine Recapture! data...) a, : a Mee ee Ue Dste Locality Estimated size Date Locality Size Eee Flag ay Lat N Long W Length Weight Lat N Long W Length Weight om cm sJan. 28, 1951 (27°10! 80°00") Mar. 15, 1951 (26°45' 79°55") RR USA 1.8 *Dec. 26, 1950 (27°10' g0°00') 214 18.2 Feb. 21, 1952 (26°32 80°00') 234 25.4. RR USA 13.9 *Dec. 23, 1952. (27°10! 80°04") Mar. 27, 1953 (26°45' 79°55") RR USA Ben Dec. 1954 or Jan. 1955 (27°10! 80°00") Jan. 12, 1956 (25°00' — 80°30") 206 RR USA 11.8 *Dec. 30, 1953 (27°10' g0°00') 191 13.6 Feb. 20, 1956 (26°32' 80°00") 221 22.8 RR USA 25.8 Feb. 5, 1958 (26°45" 79°55") (210) (21) Apr. 19, 1959 (26°15' = 80°00") 211 23.4 RR USA 14.4 Nov. 11, 1960 (26°45! 79°55") (200) Jan. 7, 1961 (26°0s' g0°0S') 198 15.5 RR USA 1.9 Feb. 5, 1961 (27°04! 30°00") (200) Feb. 26, 1961 (26°32' 80°00") RR USA 0.7 Jan. 28, 1960 — (27°04" 80°00") Mar. 8, 1961 (25°00' —-80°30") 216 (20.4) RR USA 13.2 Feb. 4, 1961 (26°45' 79°55") (220) May 11, 1961 (25°45' = 80°00") 224 20.6 RR USA a2 Jan 29, 1961 (26°s6" 30°00') (210) Jan 31, 1962 (26°05' ~~ 80°05") 155 (15.9) RR USA Bat Dec. 15, 1962 (26°15! 30°00') (230) Dec.29, 1962 (25°45! 80°00') 218 23.8 RR USA 5 Jan. 20, 1962 = (27°27" 80°05') 198 15.9 Jan. 9, 1963 (26°45' = 79°55") 206 (13.6) RR USA 11.8 Dec. 31, 1961 (26°56! s0°00') 198 (11.4) Jan. 9, 1963 (26°28' — 80°02") 198 15 kR USA 12.3 Jan. 3, 1963 (26°S6" g0°00') (210) Feb. 22, 1963 (26°15' 80°00") 203 24.3. RR USA 1.6 Apr. 14, 1962 (26°32! 80°00") Feb. 25, 1963 25°45" 80°00') 23.2. RR USA 10.4 Jan. 31, 1962 (26°56! 80°00') (220) Mar. 9, 1963 (26°15' = 80°00') 211 17.7 RR USA 13.2 Jan. 5, 1963 (26°45! 79°55") (230) Mar. 14, 1963 (25°45' 80°00") 218 23.6 RR USA 2.2 May 11, 1963 (26°20! g0°02') (120) (9.1) May 12, 1963 25°45' 80°07" 175 11.8 RR USA Jan. 10, 1963 (26°56! 30°00') (150) May 17, 1963 (26°32! 30°00") RR USA 4.2 Dec. 26, 1961 (26°45! 79°55") (200) June 24, 1963 (25°45' 80°00") 203 15.5 RR USA 17.8 Oct. 10, 1962 (26°20! 80°02") Aug. 12, 1963 25°45" ~—80°07! 206 20.4 RR USA 10.1 Jan. 4, 1964 (27°10" 30°00") (220) Feb. 27, 1964 (26°47! 80°00') RR USA 18 Apr. 2, 1964 (26°45" 80°00") (180) Mar. 17, 1965 24°33" ~— 81°07! 218 RR USA 11.5 Nov. 14, 1965 Unknown 183 13.6 Apr. 1966 (25°45' 80°00") 188 15.9 RR USA 5. Mar. 2, 1966 27°05" 80°05 198 July 12, 1966 24°30" ~— 81°50 200 14.5 RR USA 3 Nov. 11,1966 (26°54! g0°00') (210) (18.2) Nov. 19, 1966 25°35" 80°06: 203 16.4 RR USA 0.3 Dec. 19, 1965 (26°45! 79°55") (180) Jan. 23, 1967 25°16" ~— 80°10! 180 18,2 RR USA 13.2 Nov. 22, 1967. 26°15" 80°00") (210) (20.4) Noy: 24, 1967 25°45" — 80°00") 228 23.2 RR USA 0.1 (Feb. 26, 1966) (26°45! 79°55") Nov. 19, 1968 (26°05' 80°05") 226 26.4 RR USA (32.8) Jan. 22, 1968 27°23! 80°02" (210) (22.7) Dec. 29, 1968 25°55’ —- 80°04! 216 21.4 RR USA 11.2 Nov. 18, 1970 (24°40! 81°0s' 91 9.1 Nov. 26, 1970 24°26" — 81°52! 6.4 RR USA 0.3 1 RR, rod and reel * Fish tagged under program sponsored by RSMAS 207 APPENDIX TABLE 5: Sailfish tagged of the northwestern Bahamas. Recapture data Release data 4 A 1 Months at Date Locality Estimated size Date Locality Size Gear Flag Liberty Lat N Long W Length Weight Lat N Long W ~ength Weight np i en Re i a aM Cima: “Laiccis..,..°. Oct. 21, 1965 25°45" 79°19" (210) (18.2) Mar. 17, 1966 19°45" 77°43! 20.4 LL Cuba 4.8 May 2, 1967 25°25! 77°55! (18.9) May 4, 1968 (23°10' 82°25") 150 20.9 LL Cuba 12.1 Mar 21, 1968 25°25! 77°55! (230) July 20, 1968 23°14" 82°30! 18 LL Cuba 4.0 Aug. 28, 1968 25°45" 79°19" (22.8) May 31, 1969 24°47! 80°32" 213 18.2 RR USA 9.0 1 RR, rod and reel; LL, longline; CL, criollo line Release data APPENDIX TABLE 6: Sailfish tagged in the Gulf of Mexico. a RecapturendatetS a Months at Date pepe Local it yee Estimated’sizes Date ee LOC LT tye SL CR Gears Flag Liberty Lat N Long W Length Weight Lat N Long W Length Weight ZG Le, i a a *June 8, 1955 (27°35! 96°45") (210) Mar. 9, 1957 (25°00' —-80°30') RR USA 21.0 *Sept. 15, 1959 (27°35! 96°45") Aug. 14, 1961 (27°35! 96°45") (220) RR USA 23.0 *July 4, 1961 27°35" 96°45") (210) Dec. 22, 1961 (26°32' 80°00") 186 17 RR USA 5.6 Aug. 3, 1967 30°18' 86°36! 213 (17.3) Oct. 17, 1967 23°16! 82°08" 198 LL Cuba A.B Oct. 7, 1967 30°07" 86°so (210) (Jan. 1968) 21°03' ~=—-75°30" CL Cuba (3.) Sept. 12, 1968 30°05' 86°52" (200) Sept. 23, 1968 30°05" 86°53! 216 RR USA 0.4 Sept. 30, 1969 30°0S' 87°00 228 Jan. 6, 1970 12°08' ~— 61°49" 20.9 HL BWI 3.2 July 20, 1968 27°30' 96°40" (200) May 20, 1970 22°09' 77°40" (180) CL Cuba 22.0 1 RR, rod and reel; LL, longline; CL, criollo line; HL, handline * Fish tagged under the program sponsored by the Port Aransas Rod and Reel Club. 208 APPENDIX TABLE 7: Sailfish tagged off the Virgin Islands Release data Recapture data s - A nh . Months at Date Localit Estimated size Date Se Locality: - er anteetSize. Gear! Flag Liberty Lat N Long W Length Weight Lat N Long W Length Weight Cus kg cm kg are Dec. 26, 1965 18°30! 64°45! Dec. 11, 1966 18°32! 64°40! 216 18.2 RR USA 11.5 Mar. 11, 1966 18°32! 64°40! (220) Feb. 10, 1967 18°32! 64°40" 219 18.2 RR USA 11.0 Jan. 13, 1967 18°30" 64°38" (18.2) Mar. 19, 1967 18°22! 68°35! 15.5 HL Dom. R 253 Jan. 26, 1967 18°32! 64°37! (9.1) June 18, 1967 32°23! 79°25! 11.6 RR USA 4.7 Feb. 21, 1967 18°28! 64°45" 228 June 28, 1967 21°42! 86°46" cL Cuba 4.1 Jan. 17, 1972 18°30! 64°45! (200) (16) May 16, 1972 26°05! 79°50! 214 20.4 RR USA 4.0 1 RR, rod and reel; CL, criollo line; HL handline APPENDIX TABLE 8: Sailfish tagged off Venezuela Release data Recapture data Localit Estimated si i i Months at Date §———_2<"3ty _/stimated size_ Date ee Shocali tye sizes Gear! Flag Liberty Lat N Long W Length Weight Lat N Long W Length Weight June 19, 1966 (10°50! 67°00") (16) June 20, 1966 10°50! 67°00! 20* PF Venez June 4, 1966 (10°so" 67°00') 200 July 3, 1966 (10°50! 67°00") 20 RR Venez. 1.0 April 6, 1966 10°50" 67°00") (22.8) Aug. 7, 1966 (10°50! 67°00') (28.2) RR Venez. 4.0 Sept. 4, 1966 (10°50! 67°00") cs) Sept. 9, 1966 (10°50! 67°00") 28.2 PF Venez. 0.2 Aug. 6, 1966 10°46' 66°55! Jan. 2, 1967 10°51! 66°57! LL Venez. 4.9 Aug. 2, 19-6 (10°50" 67°00") May 1968 (10°50! 67°00') 29.6 PF Venez. 21. Feb. 26, 1966 10°50! 68°05! 21.4 Sept. 20, 1970 11°25! 67°00" 27.3 PF Venez. 54.8 1 RR, rod and reel; LL, Longline; PF, professional fishermen * Gutted weight 209 APPENDIX TABLE 9: Sailfish tagged off other areas. Release data Recapture data a a A a r Months at Date Locality Estimated size Date Locality Size Gear! Flag Liberty Lat N Long W Length Weight Lat N Long W Length Weight a> So i i i Mi EE aC 2. May 20, 1961 (18°35! 72°45") (12.7) Jan. 21, 1962 18°35" June 17, 1967 30°10" 81°00' ~—-(170) (11.4) Oct. 16, 1967 (26°05! Oct. 18, 1969 34°57! 75°19 (18.2) Mar. 3, 1971 09°0s' Apr. 28, 1971 20935" 87°0S' 214 34.1 Dec. 14, 1971 10°47! 72°45") ce) 80°05") 55°10! 63°09" 224 Haiti 8.1 USA 4.0 Venez. 16.5 Venez 7.6 1 RR, rod and reel; HL, handline; PF, professional fishermen 210 Migrations of White Marlin and Blue Marlin in the Western North Atlantic Ocean— Tagging Results Since May, 1970! FRANK J. MATHER, III, JOHN M. MASON, JR., ? and H. LAWRENCE CLARK? ABSTRACT Migrations of white marlin, Tetrapturus albidus Poey, and blue marlin, Makaira nigricans Lacepede, in the western North Atlantic Ocean are discussed in terms of tag returns obtained since the completion of data collection for the paper by Mather, Jones, and Beardsley (1972) in May 1970. In the period May 1970-May 1972, 2,039 white marlin and 216 blue marlin have been released, and 70 tags from white marlin and 1 from a blue marlin have been returned. The migratory pattern which had been established for the stock of white marlin summering off the middle Atlantic coast of the United States has been further supported by 54 of 60 new returns from fish released in this area. The six others deviated from this pattern geographically or chronologically, or in both respects. The ten remaining returns were from releases south of lat. 33°N. Five of these fitted with previously observed patterns or individual migrations. The other five were local or scattered, but one of them extended the range of recaptures southeastward to lat. 4°N, long. 40°W. As previously, times at liberty have been long, and the record has been increased to 58.7 mo. A new calculation, incorporating much additional data, suggests that the annual mortality rate is between 23% and 36%. The single blue marlin return is the first to show a significant migration—at least 750 nautical miles, from the Bahamas to the Gulf of Mexico—and the dates of release and recapture support the theory of separate populations of blue marlin in the North and South Atlantic. After 30 mo at liberty, this fish weighed twice its estimated weight at release. Considerable new information on migrations of white marlin and blue marlin in the western North Atlantic Ocean has become available through tags returned since the completion of the paper of Mather, Jones, and Beardsley (1972) in May 1970. In this paper we present these new data in detail, and charts and tables summarizing the total ac- cumulation of tag return data. The discussion cov- ers agreements with, and differences from, the pre- vious findings, and our present opinions about the migrations of these fishes. The estimated mortality rate of tagged and recaptured white marlin has also been revised on the basis of the new data. ‘Contribution No. 2937, Woods Hole Oceanographic Institu- tion, Woods Hole, MA 02543. *Woods Hole Oceanographic Institution, Woods Hole, MA 02543. 3Dept. of Natural Resources, Comell University, Ithaca, NY 14850. 211 Little has been published on the tagging and mi- grations of Atlantic marlins since the completion of Mather et al. (1972), but we now refer to Earle (1940) for an early tagging effort at Ocean City, Maryland, which had been overlooked by the above authors. METHODS AND MATERIALS Marlins and other oceanic fishes have been marked with dart tags (Mather, 1963; Akyitiz, 1970) by sport fishermen participating in the Cooperative Game Fish Tagging Program of the Woods Hole Oceanographic Institution (WHOI) since 1954. Tags and tagging equipment are furnished by WHOI, and release data are sent to WHOI. Unfor- tunately, some difficulties in data retrieval have re- sulted from failures of participants to send in re- lease data. Table 1.—Releases (after slash) and returns (before slash) for white marlin tagged in the western North Atlantic Ocean by year and area of release. Cape Hatteras Oceanic SE Florida West Indies Gulf Caribbean to North and and of Year Cape Cod Atlantic | NW Bahamas vicinity! Mexico SE NW Total 1954 0/4 = = aa xe zs = 0/4 1955 1/116 — — 0/8 0/21 — —_— 1/145 1956 1/402 = — 0/3 0/8 — — 1/413 1957 0/144 0/1 — — — — — 0/145 1958 0/41 — — — — — — 0/41 1959 0/200 — — — —_— 0/2 — 0/202 1960 0/98 — 0/4 0/1 0/4 0/4 = 0/111 1961 2/199 _ 0/13 0/9 0/11 0/30 — 2/262 1962 4/342 — 0/41 — 0/4 — — 4/387 1963 4/612 0/3 0/35 — 0/10 -- — 4/660 1964 12/441 0/5 1/67 _ 0/13 — — 13/526 1965 6/278 - 0/67 0/5 0/10 2/25 8/385 1966 11/272 0/6 1/54 0/4 0/23 2/149 14/508 1967 6/277 _ 0/88 0/7 1/46 0/103 — 7/521 1968 18/701 aa 1/95 0/16 0/56 0/16 — 19/884 1969 20/1,216 — 2/86 0/18 2/35 2/46 — 26/1,401 1970 16/838 — 2/49 0/15 0/24 0/17 0/4 18/947 1971 12/823 a 0/56 0/20 0/18 0/95 0/4 12/1,016 21972 0/18 — 0/36 0/6 0/4 0/1 0/1 0/66 Unknown 5/5 — — — 1/1 — — 6/6 Total 118/7,027 0/15 7/691 0/112 4/288 6/488 /9 135/8,630 ‘All releases after 1961 were off the Virgin Islands. *Through 20 July. From May 1970 through May 1972, 2,039 white WHITE MARLIN marlin and 216 blue marlin were tagged in the west- ern North Atlantic. From these and earlier re- | Migrations leases, 70 valid returns from white marlin, and one from a blue marlin, were received between May 1970 and 15 July 1972. These brought the cumula- tive totals to 8,630 releases and 135 valid returns for white marlin and 702 releases and 4 valid returns for blue marlin. In addition, correct recapture data for one earlier white marlin return were obtained and the probable origin of a plastic ring found on the bill of a white marlin caught in July 1959 has been traced. Damaged or incomplete tags or reports of tags recovered but not returned from 2 white marlin and | blue marlin were also received. The release and recapture data for the new white marlin returns, and the corrected data for one of those previously reported, are shown in the Appen- dix, along with the data for the blue marlin returns. The total accumulated data are summarized in ta- bles and charts as noted in the text. 212 The 70 new returns from white marlin added con- siderably to the information obtained from the 65 tags returned in the 16 previous years (Mather et al., 1972). The majority of the releases (1,687) again occurred on the continental shelf between Cape Hatteras and Cape Cod (Table 1). Other release sites were off the northwestern Bahamas and southeastern Florida (140), off Venezuela (114), in the Gulf of Mexico (49), near the West Indies (the Virgin Islands and Puerto Rico) (41), and off the Yucatan Peninsula (9). All of the recaptures were again in the North At- lantic west of long. 35°W, but their range was ex- tended northward nearly to lat. 43°N, and south- eastward to lat. 4°N, long. 40°W. Also, the first three recaptures in the Gulf of Mexico of fish tagged in the Cape Hatteras-Cape Cod area were Table 2.—Returms from tagged white marlin, by fishery and nationality of recapturing vessel. Returns in Column A were listed by Mather et al., 1972; those in column B were received subsequently. Type of fishery Country Number of returns A B Total Sport fishery United States 24 20 44 (rod and reel) Jamaica 1 1 Venezuela 1 1 Total 24 2 46 Commercial fishery Canada 1 2 3 (Japanese and Cuba 14 5 19 modified France 1 1 longlines, Japan 13 30 43 handlines) Norway 2 2 South Korea 2 5 7 United States 1 1 Venezuela 7 6 13 Total 41 48 89 Grand total 65 70 135 recorded. Much new information was gained on the offshore movements of white marlin from the conti- nental shelf in the latter area in September and Oc- tober. Although most of the returns from this group of fish fitted the pattern proposed for it by Mather et al. (1972), the first major deviations from this pattern were noted. Likewise, some of the returns from releases in scuthern waters fitted with previ- ous indications, but a few did not. As in the earlier years, about two-thirds of the recent white marlin returns were from commercial fisheries, and about one-third from sport fisheries (Table 2). In contrast to the earlier period, how- ever, 30 of the commercial returns (over half of the total) were from the Japanese longline fishery, while the Cuban, South Korean, and Venezuelan fisheries each returned 5 or 6 tags. The increase in Japanese returns was due largely to a very heavy concentration of effort in September and October 1971 in the offshore waters between Cape Hatteras and Georges Bank, which produced 17 returns, and to possibly increased effort in the Gulf of Mexico in the late spring and summer of 1971, when 5 tags were recovered. As in Mather et al. (1972), the returns are divided into four groups, according to release and recapture areas. The boundaries of these areas have been changed slightly from those used by Mather et al. 213 (1972) in order to obtain better seasonal separation of returns, but these changes do not alter the group- ing of returns in that paper. The areas (Fig. 1) are as follows: Area A—north of lat. 33°N, Area B—lat. 18°N to lat. 33°N, Area C—south of lat. 18°N. Sixty of the new returns were from releases on the continental shelf between Cape Hatteras and Cape Cod (Area A), bringing the total for this group to 118. Thirty-six of these were recaptured in the warm season (June-October) in Area A (Group A), 16 in Area B (1 in January, 37 in March-August) (Group B), and 8 in Area C (October-May) (Group C) bringing the respective totals to 60, 38, and 20. Ten of the new recaptures were from releases in Areas B and C (south of lat. 33°N) (Group D) bring- ing the total for this group to 17. The recaptures in these four groups are discussed below. Group A.—The new recaptures in Group A (Fig. 1, Appendix Table 1) comprise 19 from inside the 1,000 fathom (1,830 m) contour (June-October) and 17 from outside it (June, July, September, October) bringing the respective totals to 41 and 19 (Appen- dix Table 1). The new recaptures inside the 1,000 fathom con- tour give further evidence of the movements of fish within this area, and also of the regular seasonal return of fish to it, often during several summers. The new recaptures (3 in June, 2 in July, 4 in August, 9 in September, and 1 in October) spread over more of the year than the earlier ones (2 in July, 17 in August, and 3 in September). The new recaptures in June and September were from sport- fishing boats, but the one in October was from a longliner. A new recapture at the edge of the Nova Scotia Banks in August was north and east of any previously recorded on the continental shelf. Like an earlier return from the edge of Georges Bank, this merely reflects the sparsely documented (Leim and Scott, 1966) fact that, whereas the coastal oc- currence of white marlin ends at Cape Cod, the species occurs far to the east and north, along the edges of the banks, during the summer. The recaptures within the year of release (Fig. 2) show that the fish move extensively, and in various directions, within this summer habitat. Those in subsequent years show that fish return to the area seasonally with considerable regularity, and may be 4000 Fathoms INSIDE OUTSIDE 40° 30° 20° 410° oc: B0° 60° 50° Figure 1.—Location of recaptures of white marlin tagged in the western North Atlantic Ocean north of lat. 33°N between Cape Hatteras, N.C., and Cape Cod, Mass., in summer. The frequency of recaptures by months in each area is shown. The number of recaptures at each site is indicated by the size of the dot and, if more than 1, by the adjacent number. 90° 70° 40° available to fishing there during as many as six sea- sons. This was shown by a recapture in June 1972 of a fish which had been released in August 1967. These results suggest that most of the white marlin which occur in summer in this area are of a single (but not necessarily genetically distinct) stock. We will tentatively name this the ‘‘middle Atlantic”’ stock, after its summer habitat off the middle Atlan- tic coast of the United States. Fifteen of the new returns from outside the 1,000 fathom contour in Area A, which were recaptured in September and October, and the two earlier ones which were recaptured in the same period, give considerable information on how the white marlin leave the inshore fishing grounds between Cape Hatteras and Cape Cod in late summer and early fall (Fig. 3). The other two offshore recaptures, in June and July, give indications of how white marlin approach the shallower waters in spring and early summer. The lack of any offshore returns from Area A in August, when inshore returns are at a maximum, indicates a strong tendency for white marlin to concentrate on the continental shelf in that month. 214 4 4 THe? 70° 68° Figure 2.—Local movements of tagged white marlin in- side the 1,000 fathom contour between Cape Hatteras and Georges Bank. Releases were in July (4) and August (2): returns were in August (5) and September (1). Recap- tures in years subsequent to year of release are not shown. A total of 7 recaptures.in September and October show ‘‘direct’’ off-shore migrations (indicated by arrows connecting release area and recapture loca- tion in Fig. 3) by fish which had been tagged during the summer of, or immediately preceding, their re- capture. Eight other offshore recaptures in the same months were of fish which had been tagged in the summers of previous years. These fish presumably had returned to the general release area, and de- parted from it, in the summer of the year in which they were recaptured. The recaptures are widely scattered, but show a general tendency to migrate into deeper water in directions predominantly be- tween east and south. The single offshore recaptures in June and July were probably of fish which were approaching the summering areas on the continental shelf off the middle Atlantic coast and on the edge of the Nova Scotia Banks, respectively. It should be noted, however, that Japanese longline vessels take small catches of white marlin (less than 0.5 fish per 100 hooks) in these offshore waters during the summer months (Mather et al., 1972). Group B.—Twelve of the 16 new recaptures in Group B (released in Area A and recaptured in Area B) (Fig. 1, Appendix Table 2) fitted the pat- tern proposed by Mather et al., 1972, but the other 4 deviated from it considerably. The new recaptures were in January (1), March (1), April (2), May (5), June (5), and August (2). The earlier recaptures had been in April (5), May (8), June (6), and July (3). The recaptures in January and August differ greatly from previous results. The three previous January recaptures of fish tagged in Area A had been about 20° farther south, in Area C, and the 21 other Au- gust recoveries of fish tagged in Area A were in the release area. Three of the new recoveries were in the Gulf of Mexico in 1971, where, with the excep- tion of the immediate vicinity of Havana, no white marlin tagged in northern waters had previously been recaptured. Data on the effort of the Japanese longline fishery in 1971 will help to determine whether these returns from the Gulf of Mexico rep- resent an unusual migration by white marlin from Area A, or merely reflect an unusual amount of fishing effort in the Gulf,? in that year. The fish *Dr. Eiji Hanamoto (pers. comm.) has informed us that an unusually large number of Japanese longline vessels fished in the Gulf of Mexico in the summer of 1971. 215 recaptured in the Gulf in June might possibly have continued its return migration to Area A, but it seems most probable that the two which were re- captured in August had shifted their summer habitat from Area A to the Gulf of Mexico. The three ear- lier July recaptures off Havana of fish which had been tagged in Area A also suggest that not all of the fish which have summered in the Cape Cod- Cape Hatteras area return there in succeeding summers. Six of the new recaptures were in the Straits of Florida in April-June, bringing to 20 the total number of spring and early summer recaptures there of Group B fish. This is further evidence that an important component of the ‘“‘middle Atlantic” white marlin stock passes northward through the Yucatan Channel and the Straits of Florida in spring. There is also further evidence that another size- able component of this stock migrates northward or northwestward in Atlantic waters off the Greater Antilles and east and north of the Bahamas. Six new recoveries of Group B fish occurred in this area—l1 in January, | in March, 2 in May, and 2 in June. The earlier returns in the area included | in April, 3 in May, and 3 in June. The return in March represents a slight, but not surprising, increase in the period of recapture of Group B fish, but, as noted previously, the recapture in January differs radically from all of our previous results. A new recapture in May in the Mona Passage is most interesting since it indicates that components of the northward spring migration of ‘‘middle Atlan- tic’’ white marlin from Area C traverse the pas- sages between the Greater Antilles, as well as the Yucatan Channel and the waters along the Atlantic sides of the islands. Group C.—Two of the 8 new returns in Group C (fish released in Area A and recaptured in Area C) (Fig. 1, Appendix Table 3) extend the period of recoveries for this group well into the spring. The new recaptures include 2 in December, 2 in January, | in February, 1 in April, 1 in May, and 1 at an unknown date. The earlier returns comprised 1 in October, 4 in November, 4 in December, | in January, and 2 in February. Unfortunately, it has been impossible to obtain exact dates for some of the recaptures in this area, and some of the esti- mated dates may be in error. The dates of recap- tures of ‘‘middle Atlantic’’ fish in Area B, however, are not inconsistent with some of them remaining in Area C into April or even May. Group D.—Seven of the 10 new returns in Group D (white marlin tagged in Areas B and C, and recap- tured in any area) (Figs. 1 and 4, Appendix Table 4) were consistent with previous results, but three in- dicated migratory tendencies which had not previ- ously been noted. Two fish tagged off the northwestern Bahamas in spring were recaptured off Virginia in September, fitting well with our pattern for ‘‘middle Atlantic” white marlin. Another tagged in the same area in late winter was recaptured in the western Gulf of Mexico in June and one tagged in the northwestern Gulf in July was recaptured off Havana in June. Both of these support previous indications of sea- sonal migrations between sojourns in the Gulf of Mexico in the warm season and in the Straits of Florida and off the northwestern Bahamas in the cold season. There was also a local recapture in August in the north central Gulf from a release there at an unknown date, but in the warm season. I! / RELEASE AREAS RECAPTURES WITHIN ie) 5S MONTHS OF RELEASE 42° RECAPT URES >5 MONTHS : AFTER RELEASE) ssu.- .54 40° There were three recaptures from releases in Au- gust and September off Venezuela. One of these was local in a subsequent August, and one was off the Guianas in November, closely approximating an August-December migration between these areas which had been recorded previously. The third differed somewhat in that it was recaptured north of the release area in January. Evidently, this fish had merely moved offshore into deeper water in the fall, rather than migrating to the eastward as had the ones recaptured in November and December off the Guianas. The most surprising of the new Group D returns was for a fish released off the northwestern Bahamas in April and recaptured 600 miles ENE of the mouth of the Amazon River in September. This has no apparent resemblance to any of the migra- tory tendencies indicated by other returns. This migration of about 2,700 nautical miles is the longest yet recorded for a white marlin, and is the closest approach to the South Atlantic that has been made by a white marlin tagged in the North Atlan- tic. Ueyanagi et al. (1970) and Mather et al. (1972), Scotia 38° 36° 34° 76° 74° 72° 7o° Sort octe>2 21 Ww. 68° 66° 64° 62° Figure 3.—Recaptures outside the 1,000 fathom contour and north of lat. 33°N of white marlin tagged in summer between Cape Hatteras and Cape Cod. 216 40° JUL67- JUL68 « -/ JUL-AUG6S - 7 30° Mazatlan | Figure 7.—General migration patterns of striped marlin tagged off southern California and Mexico. miles per day; tip of Baja California to % the dis- tance to the Hawaiian Islands, 11.7 nautical miles per day; tip of Baja California to near Clipperton Island, 16.3 nautical miles per day. For all striped marlin recoveries having accurate records, the average days out is 89; the average migration 281 nautical miles, and average distance per day out, 3.16 nautical miles. For the limited number of sailfish recaptured the average number of days out was 113, the migration rate was 0.4 nautical miles per day. The longest distance recorded for any sailfish was 250 nautical miles in 457 days out. This was the longest release- recapture time of any billfish tagged in the Pacific. Two black marlin were recovered, one near the point of tagging in the Coral Sea 364 days after tag- ging, the other 180 days after tagging, 1,440 nautical miles northeast of Queensland, Australia. This bill- fish averaged 8 nautical miles per day. The greatest migration rate in nautical miles per day for any billfish was a short-term recovery of a striped marlin tagged off the tip of Baja California which averaged 31.6 nautical miles per day. DISCUSSION AND SUMMARY The concept of utilizing cooperating marine game fish anglers to tag and release billfishes has proven to be a practical approach to the study of billfish migration patterns. Experience indicates that accurate estimates of weights and lengths of tagged fish cannot be ex- pected. After tagging, the angler is requested to return the tag card. In 1968 a comparison was made of the number of tags returned with a matching tag card on file, with those that did not have a tag card. This indicated that about 17% of the tag cards were not being returned. As a result, an active campaign to have the angler return the cards was begun. The number of billfishes tagged annually in the Pacific has steadily increased since 1954, reaching a total of 2,118 in 1971. The annual rate of billfish recoveries rose to above the 0.90% level from 1966 through 1968, dropped to 0.40% in 1969, increased to a peak of 1.16% in 1970, and dropped to a very low 0.13% in 1971. The reason for the sharp decline in recoveries in 1971 cannot be explained. The only change in operation otf the National Marine Fisheries Service program was the introduction of the ‘“H”’ type tag. During the latter half of 1971, 317 ““H”’ tags were used, which equalled only 14.7% of 235 the total tags used by the National Marine Fisheries Service program during 1971. The recovery rate from FM-67 and FT-1 fags used by the National Marine Fisheries Service and California Department of Fish and Game in the Pacific for striped marlin were comparable. The California Department of Fish and Game program obtained a 0.80% recovery rate using the FT-1 and the National Marine Fisheries Service program ob- tained a 0.42% recovery rate using the same tag, giving an overall average of 0.66%. The California Department of Fish and Game program restricted its tag distribution to a limited number of experi- enced anglers fishing from private boats. On an av- erage these anglers were more experienced in tag- ging billfish than most of the anglers participating in the National Marine Fisheries Service program. The FM-67 tag used for striped marlin shows a greater recovery rate (1.06%) than any of the four types of tags used. The recovery rate of the California Department of Fish and Game FT-1 tag (0.80%) was near that of the FM-67. The National Marine Fisheries Service program changed to the metal-plastic ‘‘H’’ type tag in mid-1971 because of the recovery record (recovery percent and time out) for white marlin (Tetrapturus albidus) and sailfish in the Atlantic Ocean experi- enced by the Woods Hole Oceanographic Institu- tion program. Although many factors such as seasons and areas of fishing and economic value of billfishes influence catch rates in the Atlantic and eastern Pacific, a gross comparison of catch rates between the two oceans can be made. Catch and effort data given by the Japanese for Japanese longline operations in the Atlantic and eastern Pacific Oceans and plotted by Gottschalk (1972), show that the total effort in hooks fished was only slightly greater in the Atlan- tic than in the eastern Pacific for the period 1962 through 1970 (478 x 10° for the Atlantic and 442 x 10° for the eastern Pacific). Charts outlining longlin- ing areas for striped marlin and sailfish in the east- ern Pacific by Joseph et al (1973) and for sailfish and white marlin in the Atlantic by Wise and Davis? show that these areas are near equal in geographical extent. However, the catch-per-unit-effort (catch/hook) for striped marlin in the eastern Pacific has remained about three times greater over the years than the catch-per-unit-effort for white marlin ~ 4Wise, John P. and Charles W. Davis. 1971. Seasonal distribu- tion of billfish in the Atlantic. Prepared for 22nd Tuna Confer- ence, NMFS, Miami, Fla., 28 p. (mimeo.). in the Atlantic, a species that is similar in many respects to the striped marlin. The catch-per-unit- effort for sailfish in the eastern Pacific has averaged about four times the catch rate for the same species in the Atlantic. These wide variations in catch rates between the Atlantic and eastern Pacific indicate a possibility of a lower density level or of a much smaller white marlin population, or both, in the Atlantic when compared with striped marlin in the eastern Pacific and sailfish in both oceans. If this is true, given approximately the same fishing effort, a greater percentage of tag recoveries of these species could be expected in the Atlantic. The recovery rate of striped marlin tagged in the eastern Pacific using the FM-67 plastic tag was slightly less than for the metal tip tags used by the Woods Hole Oceanographic Institution Atlantic program for white marlin (1.06% eastern Pacific, 1.22% Atlantic). The plastic FT-1 tag gave near equal recovery rate results for sailfish in the Atlan- tic and the eastern Pacific (0.86% eastern Pacific, 0.80% Atlantic). The recovery rate for striped mar- lin tagged with metal tip ‘‘H”’ tags in the eastern Pacific has been 0.40%. From the limited amount of data available, no definite conclusions can be reached. However, it appears that the plastic dart tag is as satisfactory as the metal tip dart tag. When the possible differences in population levels and projected recovery rates are considered, the plastic dart tag actually may prove to be superior. In the northeastern Pacific there have been enough striped marlin tag recoveries to make some observations regarding their migration. Striped mar- lin usually are available during the first 3 months of the year off Mazatlan, Mexico. Movements of tag- ged fish from this area are toward the southwest and west, to and beyond the tip of Baja California. In late spring the principal component of the fishery changes to sailfish dominance. Striped marlin are usually available about the tip of Baja California from late spring through fall. Mi- grations of tagged fish to the south and some to the west and northwest have been recorded. During late spring and early summer the reproductive activ- ity of striped marlin increases in this area (M. El- dridge and P. Wares,° pers. comm.; Kume and Joseph, 1969). Thus the migrations away from the °M. Eldridge and P. Wares, National Marine Fisheries Ser- vice, Tiburon Fisheries Laboratory, P.O. Box 98, Tiburon, CA 94920. 236 tip of Baja California in a southerly direction may be related to spawning activity of striped marlin in the general vicinity of the Revillagigedo Islands. Some spawning activity has been reported in this area by the Japanese longline fleet during the period late June through October (G. Adachi,® pers. comm.). Gonad indices for striped marlin collected in areas of reported spawning have been several times higher than the index found about the tip of Baja California (M. Eldridge, pers. comm.). Since the amount of longline fishing becomes less as one proceeds north of Magdalena Bay, Baja California, Mexico, the number of returns of striped marlin tagged about the tip and migrating northwest of the Magdalena Bay area would be re- duced in proportion to the amount of fishing effort. However, some recoveries have been recorded northwest from the tip of Baja California toward southern California, immediately prior to the movement of striped marlin into the southern California fishery. An increase in catch per effort is noted in this area during the second and third quar- ters of the year. The southern California sport- fishery takes only a small number of striped marlin during late August through October (usually less than 500); the Japanese longline fleet does not oper- ate in this area. Therefore the chance of recovering a striped marlin off southern California is remote. However, from the limited number of striped marlin tagged off southern California and recovered a short time later near the tip of Baja California, indi- cations are that a southerly migration from southern California exists in the fall. The rates of migration for striped marlin about the tip of Baja California-Mazatlan-Revillagigedo Island area was 1.9 nautical miles per day. Two westward records of long distance migrations from the coast of North America toward Hawaii show rates of 12.3 and 26.0 nautical miles per day. From southern California to near the tip of Baja Califor- nia, four records show an average migration of 12.3 nautical miles per day. A southward migration from the tip of Baja California to near Clipperton Island was recorded at 16.3 nautical miles per day. Distant water migrations from southern Califor- nia and about the tip of Baja California show a much higher migration rate in nautical miles per day when compared with those recaptured near the tip of Baja California, Mexico. Sailfish recoveries indicate little movement, the ®G. Adachi, P.O. Box 240, Manzanillo, Colima, Mexico. longest being 250 nautical miles. Figure 7 repre- sents a summation of the major migrations of striped marlin in the eastern Pacific as determined by the cooperative tagging program. In general, recoveries of striped marlin in the eastern Pacific were short- term (89 days average) and the average migration distance was 281 nautical miles. Certain recommendations can be made regarding the future conduct of cooperative tagging programs in the Pacific for billfishes. These are as follows: 1. Encourage and develop billfish tagging (sport and commercial) throughout the entire Pacific for a better understanding of the migration patterns over the entire area for the major commercial and sport species. In the eastern and central Pacific addi- tional tagging should be conducted off the Hawaiian Islands, southern California, Acapulco, Panama/Ecuador/Peru, Galapagos Islands, Tahiti, and Samoa. 2. Attempt to free-tag (harpoon method) or tag billfishes caught by non-injurious fishing techniques in sufficient numbers to determine hooking mortal- ity. 3. Consider development of improved tags and tagging equipment and experimentally test both the metal tipped and plastic dart tags for histological compatibility and differential shedding by double- tagging billfishes or double-tagging large pelagic species in aquaria tests. 4. If additional tagging programs are to be under- taken in the Pacific in the future the programs should be coordinated between countries with re- gards to types of tags used, locations and seasons of tagging, publicity, recovery and reward procedures, to achieve the greatest return of information. ACKNOWLEDGMENTS Firstly, the success of the tagging program results from the interest and cooperation of the several thousands of billfish anglers who have actively par- ticipated by tagging and releasing their billfishes. Secondly, the cooperation of the managers of the 237 various fishing resorts, charter boat skippers, and big game fishing clubs throughout the Pacific and the individuals allied with these organizations for they have been an important factor in the success of the program. Individually, I would like to recognize Frank Mather III, Horace Witherspoon, William Craig, Gerald Talbot, Wally Giguere, Johanna Alban, and M. Eldridge for their interest and hard work on be- half of the cooperative tagging programs in the Pacific. LITERATURE CITED BECKETT, J.S. 1970. Swordfish, shark and tuna tagging 1961-69. Fish. Res. Board Can., Tech. Rep. 193, 13 p. GOTTSCHALK, J.S. 1972. Longlines and billfish. U.S. Dep. Commer., Natl. Mar. Fish. Serv. Presented (at) Outdoor Writers Assoc. Am., Mazatlan, Mexico, 6/26/72, mimeo., 21 p. JOSEPH, J.. W. L. KLAWE, and C. J. ORANGE. 1974. A review of the longline fishery for billfishes in the eastern Pacific Ocean. Jn Richard S. Shomura and Fran- cis Williams (editors), Proceedings of the International Billfish Symposium, Kailua-Kona, Hawaii, 9-12 August 1972, Part 2. Review and Contributed Papers. U.S. Dep. Commer., NOAA Tech. Rep. NMFS SSRF-675, p. 309-331. KUME, S., and J. JOSEPH. 1969. Size composition and sexual maturity of billfish caught by the Japanese longline fishery in the Pacific Ocean east of 130°W. [In Engl.] Bull. Far Seas Fish. Res. Lab. (Shimizu), 2:115-162. MATHER, F.J., III. 1972. Cooperative Game Fish Tagging Program. Summary of results, prepared for NOAA/NMFS Conference on Cooperation with Sport Fishermen, February 7-11, 1972, Washington, D.C. Woods Hole Oceanogr. Inst., 16 p. SCHAEFER, M. B., B. M. CHATWIN, and G. BROAD- HEAD. 1961. Tagging and recovery of tropical tunas, 1955-1959. [In Span. and Engl.]. Bull. Inter-Am. Trop. Tuna Comm. 5:343-455. STRASBURG, D.W. 1969. Billfishes of the central Pacific Ocean. U.S. Fish Wildl. Serv., Circ. 311, 11 p. Occurrence of Young Billfishes in the Central Pacific Ocean WALTER M. MATSUMOTO and THOMAS K. KAZAMA? ABSTRACT Plankton and other net-caught samples collected on past cruises of the National Marine Fisheries Service, Honolulu Laboratory vessels in Hawaiian and central Pacific equatorial waters were examined for billfish larvae and juveniles. Of the 342 billfish young found in 4,279 net tows, 209 were blue marlin, Makaira nigricans, 82 were shortbill spearfish, Tetrapturus angustirostris, 2 were sailfish, Istiophorus platypterus, 20 were swordfish, Xiphias gladius. Twenty-nine larvae were unidentified owing to excessive damage. A preponderance of the catches was obtained from hauls made at the surface during daylight. In the equatorial central and North Pacific larvae of only three of the six billfish species nominally found in the Pacific were taken. The captures of these larvae (blue marlin, shortbill spearfish, and swordfish) fill the gaps in the known distribution of istiophorids and swordfish, and extend their distribu- tion eastward to the Hawaiian Islands in the North Pacific. The two sailfish larvae were taken in New Hebrides waters in the western South Pacific. The absence of striped marlin, Tetrapturus audax, larvae in Hawaiian waters was significant, since this species comprises nearly 82% of all istiophorids taken on the longline in the Hawaiian fishery. Their absence suggested that the striped marlin in Hawaiian waters probably migrate elsewhere to spawn. If this is true, then the spawning habits of this species differ significantly from those of blue marlin. A similar situation could hold for sailfish also. In recent years fishery workers have given more attention to the early life history of billfishes, owing to the increasing importance of these fishes in the commercial and sport fishing catches. The billfishes in the Pacific Ocean are represented by two families: Istiophoridae and Xiphiidae. The Is- tiophoridae includes five species: /stiophorus platypterus, sailfish; Tetrapturus angustirostris, shortbill spearfish; 7. audax, striped marlin; Makaira nigricans, blue marlin; and M. indica, black marlin. The Xiphiudae is represented by a single species, Xiphias gladius, swordfish. Larvae of all these species, mainly from the western Pacific, have been identified and reported by Japanese workers. This study, based on larvae collected on past cruises of the National Marine Fisheries Service, Honolulu Laboratory (HL) vessels in Hawaiian and central Pacific equatorial waters, verifies the iden- tifications reported by Yabe (1953), Yabe et al. (1959), Ueyanagi and Yabe (1959), and Ueyanagi 1Southwest Fishenes Center, National Marine Fisheries Ser- vice, NOAA, Honolulu, HI 96812. 238 (1959, 1962, 1964), and extends the distribution of larvae of certain billfishes eastward through the central Pacific. IDENTIFICATION OF LARVAE The three species of istiophorid larvae in our col- lection, blue marlin, sailfish, and shortbill spearfish, were easily identified on the basis of black pigmen- tation (Ueyanagi, 1963) on more than half the length of the lower jaw (sailfish) and on the branchiostegal membranes (shortbill spearfish). Larvae of blue marlin lacked this pigmentation. Since larvae of striped marlin also lack this pigmentation, the sep- aration of blue from striped marlin is most difficult. Ueyanagi (1963) lists two main characters by which he separates the larvae of these two species: (1) the tip of snout either level or below center of eye (striped marlin), and (2) the ‘‘anterior edge of orbit projects forward”’ (blue marlin). The first character is highly subjective and lacks a clear definition of reference points. Even a slight distortion in the body can effect a change in the position of the eye relative to that of the tip of snout. The second 25 | == x STRIPED MARLIN e¢ BLUE MARLIN SNOUT/ORBIT (HORIZONTAL DIAMETER) 8 &) ite) 20 STANDARD LENGTH (mm) Figure 1.—Snout to orbit (horizontal diameter) ratios of blue and striped marlins. Growth stanzas fitted by Bartlett’s best-fit line. character needs clarification: it is the shape of the orbital crest as well as the extent of protrusion that sets the blue marlin larvae apart from those of striped marlin. In the blue marlin the anterior part of the orbital crest, beginning slightly ahead of the anterior naris, rises sharply and the anteriodorsal part is high and angular. In other istiophorid larvae the orbital crest slopes up and back more gradually (Ueyanagi, 1963, Plate 3). A more useful character by which larvae of these two species can be separated is the snout to orbit ratio. Ueyanagi (1959) has used this character to show the difference between larvae of sailfish and blue marlin, except that his snout measurement in- cluded the distance from the tip of snout to center of eye with the orbit measured vertically. We have used snout length as measured from the tip to the anterior edge of the orbit and the orbit as measured horizontally. Regardless of which snout length or orbit measurement is used, the separation of the curves is similar. Figure 1 shows the snout to orbit ratios of 138 blue marlin larvae from the central Pacific and 10 striped marlin from the western Pacific (seven measurements from Ueyanagi, 1964 and three Measurements from specimens sent to us by Ueyanagi) plotted against standard length. Bartlett’s (1949) best-fit lines were drawn through points representing growth stanzas for each species. Despite the small number of points shown for striped marlin, the separation of the species, at 239 least in the larger size range, appears to be valid. Among the smaller stages (below 6 mm), however, the points approach each other close enough to make separation more difficult. The scatter of points about the curve shown for blue marlin above 6 mm (Fig. 1) and the absence of snout to orbit ratios falling near the curve shown for striped marlin suggest that larvae from the central North Pacific without pigmentation on the posterior half of the lower jaw and branchiostegal membranes are all of blue marlin. COLLECTION OF SAMPLES AND CATCHES The samples of billfish larvae were obtained mainly from 1-m plankton net tows taken from ves- sels of the HL and other organizations from 1950 through 1970, and from I- x 2-m neuston net tows in 1971. The plankton net was usually towed for 30 min, either horizontally at the surface or obliquely to depths ranging from 40 to 200 m. The neuston net, constructed entirely of 1-mm mesh netting, was used only on one cruise to the western Pacific. Owing to operational difficulties, this net was towed at the regular plankton net speed of 3.7-5.5 km/h for 30 min. Catches by the plankton and neus- ton nets included juveniles as large as 20 mm. A 12.2-m mouth diameter Cobb pelagic trawl, made of 19.0-mm stretch mesh netting lined with 6.4-mm netting at the cod end, was used on several cruises around Hawaii, in equatorial waters along long. 145°W, and in waters of the Trust Territory of the Pacific Islands from 1967 through 1971, and caught juveniles as large as 55 mm. The midwater trawl was usually towed at night for 3-6 h (Appendix Table 1). The area sampled with towed nets is ex- tensive, covering nearly one-half of the Pacific Ocean (Fig. 2). A total of 342 billfish larvae and juveniles was obtained from 4,279 net tows of all types. A sum- mary of the catch by type of gear and tow (Table 1} shows that 4,170 tows (97%) were made with the l-m plankton net, and that of this number 2,850 (68%) were oblique tows. Despite the large ratio of oblique to surface tows (2:1), the catch ratio was just the opposite. The surface tows caught five times as many larvae and juveniles as the oblique tows. A closer look at the 1-m net tows by depth and time of day (Table 2) shows that most of the larvae were taken in the upper I-m of water during daylight. The small numbers taken in the oblique tows suggest that these larvae are restricted to the surface, and the small catches in night tows suggest that these larvae migrate downward at night. Both observations are similar to the results obtained by Ueyanagi (1964) in the western Pacific, where he examined 32 day and 31 night plankton net samples from depths of 0, 20, and 40 m. He found that abundance of larvae de- creased with depth during the day, and that the day catches at the surface were greater than those at night. His data point out one other aspect which does not appear in our data: that within the upper 40 m of Figure 2.—Localities of captures of young Istiophoridae in the Pacific Ocean. Area sampled by the Honolulu Laboratory indicated by solid line and capture sites by black dots. Localities of captures by Howard and Ueyanagi (1965) shown as shaded areas. Table 1.—Billfish larvae and juveniles collected by various gear from research vessels of the Southwest Fisheries Center, Honolulu Laboratory in the central Pacific Ocean, 1950-71. Larvae and juvenile catch Short- Damaged bill un- Type Number Blue spear- Sail- Sword- identi- Per- Gear of tow tows marlin fish fish fish fied Total cent l-m plankton 30-min, surface 1,320 142 68 2 16 22 250 Boil net I-m plankton 30-min, 40-200m 2,850 25 14 0 4 7 50 14.6 net oblique Cobb pelagic 6-h, 20-100m 92 18 0 0 0 0 18 By) trawl horizontal 2m 30-min, surface 17 24 0 0 0 0 24 7.0 neuston net Totals 4,279 209 82 2 20 29 342 100.0 Percent 61.1 24.0 0.6 5.8 8.5 100.0 Table 2.—Catch rates (catch per 100 tows) of billfish larvae in 1-m plankton net and 1- x 2-m neuston net. Species ET SOK wae Taal La eee Alllespecies; bill including Blue marlin — spearfish Sailfish Swordfish unidentified No. of tows larvae Type of tow Day Night Day Night Day Night Day Night Day Night Day Night Surface 201 1,119 50.0 3.7 14.8 35) 1.0 0.0 2.0 Hells GEG 8.9 Oblique L280 mes On OS ee Owe SOFAS OSes OLON OO" e025" 08 Sis eZ Neuston 15 0 160.0 — 0.0 — 0.0 — 0.0 — 160.0 — water, the catches at night at the three depths sam- pled were approximately equal. The neuston net catches (Table 2) provide further information on the vertical distribution of these lar- vae. The net was normally towed with part of the net above the surface, so that on an average it only sampled the upper 0.5 m of water. The catch per tow was more than three times that of the 1-m net towed fully submerged at the surface. Since the neuston net strained roughly twice the volume of water as the 1-m net, the catch per unit volume of water strained was about 1.5 times that of the 1-m net. The higher catch rate of the neuston net thus suggests that bill- fish larvae could be concentrated not only in the upper I-m of water but even closer to the surface. DISTRIBUTION OF ISTIOPHORID LARVAE Howard and Ueyanagi (1965) have plotted the occurrence of istiophorid larvae in the Pacific Ocean. Outlines drawn of their plots by species (Fig. 2) show that catches of most species were largely confined to the western Pacific. Our data of larval captures fill the gaps in the distribution given by Howard and Ueyanagi (1965), particularly around the Hawaiian Islands and in the central Pacific south of the equator. The northern limits of distribution of the four species of Istiophoridae in the western North Pacific are notably similar (Fig. 2, panels A and B). The southern limits of distribution for all species cannot be defined, since sampling for the larvae on all cruises east of long. 180° did not extend far enough southward. Judging on the basis of the close relationship between larval distribution and the 24°C surface isotherm (Ueyanagi, 1964; Jones and Kumaran, 1964) and on the configuration of the surface temperature isotherms across the South 241 Pacific (U.S. Hydrographic Office, 1948), it seems that the southern limits of distribution of these larvae should not extend much beyond lat. 25°S. Blue Marlin Blue marlin larvae, which comprised 60.8% of all billfish larvae collected by us, occurred in both the North and South Pacific. In the North Pacific they were distributed heavily around the Hawaiian Is- lands and in waters to the west between lat. 7° and 24°N. This distribution seems to be contiguous with that shown by Howard and Ueyanagi (1965). In the South Pacific the larvae occurred in a band between lat. 0° and 24°S from the New Hebrides through the Tuamotu Archipelago. The western end of this band ties in with the southwestern outline of the distribu- tion of Howard and Ueyanagi (1965). The interven- ing area (lat. 5°-10°N and long. 140°W-180°) appears to be devoid of blue marlin larvae, but this could be due to inadequate sampling; only a few surface day tows were made there. Sampling especially for bill- fish larvae would likely change this distributional picture and provide us with better information in the area east of long. 140°W and in equatorial waters westward to long. 180°. Seasonal Distribution.—Seasonal changes in the distribution of blue marlin larvae were observed only in the Hawaiian Islands area, where enough sea- sonal sampling was done (Fig. 3). The blue marlin, as well as some other billfishes, spawn throughout the year in warm tropical and subtropical waters. At both the northern and southern fringes of distribu- tion, however, spawning occurs only during the warm seasons (Howard and Ueyanagi, 1965). In the Hawaiian Islands area, the northern fringe of larval blue marlin distribution lies roughly parallel to the 242 surface isotherms (Fig. 3) and moves northeastward and southwestward with the seasons. Thus, in the first quarter the larvae were found far south of the island, but in the second quarter they were abreast of the islands. In the third quarter the edge of larval distribution shifted northward a few degrees of latitude past the islands and moved back to just south of the islands in the fourth quarter. The northward shift of the distribution during the four seasons is about 10° to 11° of latitude. Ueyanagi (1964) reports that larvae of istiophorid species occur generally in water that is warmer than 24°C. Jones and Kumaran (1964) also show that none of their larvae were taken in waters colder than 24.5°C. Our data (Appendix Table 1) show that al- though most of the blue marlin larvae were taken in water between 26° and 29°C, the lowest temperature associated with capture was 23.8°C. Shortbill Spearfish Larvae of shortbill spearfish comprised 24.3% of all billfish larvae collected by us. Their distributional pattern in the central Pacific is similar to that of blue marlin larvae (Fig, 2). North of the equator the cap- tures were grouped around the Hawaiian Islands in an area bounded by lat. 10° and 23°N and long. 150° and 174°W. The area between long. 174°W and the eastern limit of Howard and Ueyanagi’s (1965) data should also contain larvae of this species to show a continuous distribution from the western Pacific to the Hawaiian Islands. Because of inadequate sam- pling, only three surface day tows and eight oblique tows, no larvae were taken there. South of the equator, larvae were taken in a band (lat. 0° to approximately 20°S) extending from the New Hebrides Islands through the Tuamotu Ar- chipelago, similar to that for blue marlin. The gap in the distribution along the equator, between lat. 7°N and 5°S, may be interpreted in two ways: first, the gap could be due to insufficient samples of surface day tows; and second, the gap could represent a separation of the shortbill spearfish into northern and southern populations. The latter is supported Figure 3.—Localities of captures of young blue marlin by quarters. Solid lines represent mean surface temperature for last month of quarter. Dashed lines represent surface temperature at time of sampling. Small open circles rep- resent sampling with plankton nets in 1° square area; large solid dots represent capture sites. by the discontinuous north-south distribution of lar- vae in the western Pacific, compared with the con- tinuous distribution across the equator of blue marlin larvae. Seasonal Distribution.—The seasonal occur- rence of shortbill spearfish larvae in the Hawaiian Islands (Fig. 4) resembles that of blue marlin in certain respects, the northern edge of distribution being parallel to the chain of islands and the move- ment across the islands being from southwest to northeast. The differences, though small, are nevertheless evident. In the first quarter shortbill spearfish larvae were found approximately 500 km southwest of the islands, as compared to about 950 km for blue marlin larvae. The northern edge of the larval distribution shifted northeastward to about 320 km past the islands in the second quarter, re- treated to the islands in the third quarter, and con- tinued southwestward past the islands in the fourth quarter. This north-south movement of larval short- bill spearfish distribution seemed to precede that of larval blue marlin distribution by a full quarter. One reason for these differences could be that the shortbill spearfish may be able to spawn in colder water than the blue marlin. The temperature data seem to suggest this. Shortbill spearfish larvae were found in waters with temperatures as low as 22.3°C, with most catches having been made in 25° to 26°C water. Both minimum and best catch temperatures for shortbill spearfish larvae were at least 1°C lower than for blue marlin larvae. DISTRIBUTION OF XIPHIID LARVAE Larvae of the Xiphiidae, the second of two families that make up the billfishes, were taken only occasionally. Only 20 specimens ranging in sizes from 5.8 to 23.0 mm were found in plankton samples taken from 1950 through 1971 (Table 1 and Appendix Table 2). Larval and juvenile stages of swordfish from the Atlantic and Pacific Oceans have been described by a number of workers (Arata, 1954; Nakamura et al., Figure 4.—Localities of captures of young shortbill spearfish by quarters. Solid lines represent mean surface temperature for last month of quarter. Dashed lines rep- resent surface temperature at time of sampling. Small dots represent sampling with plankton nets in 1° square area: large dots represent capture sites. 243 1954; Yabe, 1951; and Yabe et al., 1959). The sword- fish larvae are easily recognized by their long snouts and heavily pigmented elongate bodies. They havea prominent supraorbital crest similar to that of the marlins, but lack the enlarged posttemporal and preopercular spines. Larvae above 8.0 mm are even more distinctive; they have one or more rows of spinous scales on each side of the dorsal and anal fins, with those along the latter continuing forward to the level of the pectoral fin. ; Although the important fishing areas for this species are mainly in temperate waters, the larvae and juveniles are found largely in tropical and sub- tropical waters throughout most of the Pacific. Fig- ure 5 shows the locations of captures of swordfish larvae and juveniles below 80.0 mm recorded to date and those taken by HL ships. A similar plot of cap- tures, exclusive of those taken by HL, was pub- lished by Jones and Kumaran (1964). (One capture site at lat. 23°N, long. 174°W is plotted erroneously. This should have been in the southern hemisphere. ) Our samples extend the distribution of young sword- fish to waters east of the Hawaiian Islands in the North Pacific, and partially fill in the gap between long. 132° and 172°W in the equatorial and South Pacific. The overall distribution, which extends roughly two-thirds the breadth of the Pacific, is simi- lar to that of blue marlin larvae. Although captures were spotty throughout the western and central Pacific, there were enough to show differences in spawning time in the various parts of the Pacific. The probable month of spawning (Fig. 5) was calculated for each individual, using the growth estimate of 0.6 mm per day derived by Arata (1954). According to these calculations spawning Figure 5.—Localities of captures of young swordfish <80 mm SL in the Pacific. (The numerals next to each capture site denote estimated month of spawning.) Table 3.—Summary of young swordfish (Xiphias gladius) taken in plankton net tows in the Atlantic and Pacific Oceans. No. of larvae No. of juveniles Source! <10 mm 10-80 mm Total Yabe (1951) 0 1 1 Arata (1954) 4 19 23 Yabe et al. (1959) 5 15 20 Sun Tsi-Gen (1960) 0 17 17 Honolulu Laboratory 14 6 20 Total 23 58 81 Percent 28.4 71.6 100 1Taning (1955) examined 60 larvae of which 53 were <20 mm; no breakdown of larvae <10 mm available. occurred in spring and summer (March through July) in the central North Pacific and in spring (September through December) in the western South Pacific south of lat. 10°S. In equatorial waters between lat. 10°N and 10°S, spawning occurred in all months of the year. Spawning also seemed to begin and end 1 or 2 mo earlier in the western Pacific in the Philippine- Formosa area, as compared with the Hawaiian Is- lands area. This is understandable when we con- sider: (1) that post-larval swordfish are usually taken in the Atlantic in waters having surface temperatures above 23.5°C (Taning, 1955), (2) that in the western Pacific this isotherm lies between Taiwan and the Philippine Islands as early as February, and (3) that in the central Pacific along the same latitude, the 23.5°C isotherm passes northward through the Hawaiian Islands in March or April, a difference of | to 2 mo. - A unique aspect about the captures of swordfish young is that of the small numbers taken in plankton nets, only 28.4% were larvae smaller than 10 mm (Table 3). Among other pelagic fishes, such as spear- fishes, tunas, mackerels, etc., most of the larvae caught in plankton nets are below 10 mm. Perhaps the proportion of larvae caught is reduced inordi- nately by the disproportionate catches of juveniles. Among other fishes, particularly tunas and mack- erels, juveniles above 10 mm are rarely caught, ex- cept in much larger gear such as midwater trawls. The large percentage of juveniles up to 80-mm long taken in plankton nets suggests that the swordfish young either do not react to the net quickly enough to avoid it or are exceptionally poor swimmers at this stage of development. Also noteworthy is the apparent brevity of the spawning season in the northern and southern edges of distribution. Although spawning is indicated for most months of the year in the vicinity of the equator, it extended for only 4 mo, April to July, in the areas above lat. 20°N. By contrast, blue marlin and shortbill spearfish spawning extended over 5 and 6 mo, May through September and May through October, respectively, in Hawaiian waters. The captures of swordfish larvae off Hawaii also provided new information on the lowest tempera- tures in which this species spawn. Two larvae (9.6 and 9.8 mm) were taken at long. 157°W in 23.3° and 23.6°C water, well below the lowest temperature previously recorded in the Pacific and comparable to the 23.5°C recorded from the southwestern Atlantic by Taning (1955). DISCUSSION A comparison of the species composition of bill- fishes taken on the longline and the young taken in plankton nets in Hawaiian waters leads to interesting speculations concerning the spawning behavior of certain istiophorids. For example, the striped marlin is the predominant species taken commercially, in terms of both number and weight of fish caught. An average of 5,685 striped marlin, which make up 81.6% of all istiophorids caught on the longline, were taken annually from 1966 to 1970. Yet, no larva of this species has been recognized from our samples. Alternatively, blue marlin and shortbill spearfish comprise only 9.8% and 3.4%, respectively, of the istiophorids taken on the longline, but they make up the entire catch of young taken in these waters. Larvae of sailfish and black marlin also have not been recognized in our catches. These two species combined represent only 4.5% of the istiophorids taken on the longline. The absence of striped marlin larvae in Hawaiian waters is probably due to absence of spawners. Length-frequency data (Royce, 1957; Howard and Ueyanagi, 1965) show that very young fish less than 150-cm modal length (11 kg?) first appear in the fishery in the fall and remain there continuously through two successive seasons, by which time they have attained a modal length of 220 cm (45 kg). No 2Conversion of weight (Ib) to estimated length (cm) through courtesy of R.A. Skillman, Honolulu Laboratory. 245 one has yet studied the size of striped marlin at initial spawning but it is suspected that fish in the last modal group may have reached sexual maturity, since fish of similar sizes were found with ripe gonads in the western Pacific between lat. 15° and 30°N (Howard and Ueyanagi, 1965). A more striking phenomenon about the striped marlin fishery in Hawaii is that fish in the last modal group disappear in July and do not reappear as a group in the fishery. To be sure striped marlin larger than this modal size have been taken there but only in small quantities comprising less than 1% of the total monthly catches. On the basis of the discussion above and the oc- currence of both larvae and adults with ripe gonads only in the area between lat. 15° and 30°N, west of long. 170°E (Howard and Ueyanagi, 1965) in the North Pacific, it is logical to assume that the striped marlin in Hawaiian waters leave the islands to spawn, most likely in the western North Pacific. If this is so, the spawning habit of this species differs significantly from that of blue marlin, which spawn almost continuously between lat. 30°N and 25°S in the western and central Pacific. The absence of sailfish larvae in the central Pacific, except in the western South Pacific (New Hebrides Islands), suggests that this species also may spawn in selective areas. LITERATURE CITED ARATA, G.F., JR. 1954. A contribution to the life history of the swordfish, Xiphias gladius Linnaeus, from the South Atlantic coast of the United States and the Gulf of Mexico. Bull. Mar. Sci. Gulf Caribb. 4:183-243. BARTLETT, M.S. 1949. Fitting a straight line when both variables are subject to error. Biometrics 5:207-212. HOWARD, J.K., and S. VEYANAGI. 1965. Distribution and relative abundance of billfishes (/s- tiophoridae) of the Pacific Ocean. Stud. Trop. Oceanogr. (Miami), 2, 134 p. JONES, S., and M. KUMARAN. 1964. Distribution of larval billfishes (Xiphiidae and Is- tiophoridae) in the Indo-Pacific with special reference to the collections made by the Danish Dana Expedition. Jn Mar. Biol. Assoc. India, Proc. Symp. Scombroid Fish., Part 1:483-484. NAKAMURA, H., T. KAMIMURA, Y. YABUTA, A. SUDA, S. UEYANAGI, S. KIKAWA, M. HONMA, M. Y UKINAWA, and S. MORIKAWA. 1951. Notes on the life-history of the sword-fish, Xiphias gladius Linnaeus. [In Engl.] Jap. J. Ichthyol. 1:264-271. ROYCE, W.F. 1957. Observations on the spearfishes of the central Pacific. U.S. Fish Wildl. Serv., Fish. Bull. 57:497-554. SUN, T.G. 1960. Larvae and fry of tuna, sail-fish and sword-fish (Thunnidae, Istiophoridae, Xiphiidae) collected in the western and central Pacific Ocean. Tr. Inst. Okeanol., Akad. Nauk SSSR 41:175-191. TANING, A.V. 1955. On the breeding areas of the swordfish (Xiphias). Pap. Mar. Biol. Oceanogr., Deep Sea Res., suppl. to vol. 3:438-450. UEYANAGL, S. 1959. Larvae of the striped marlin, Makaira mitsukurii (Jordan et Snyder). [In Jap., Engl. summ.] Rep. Nankai Reg. Fish. Res. Lab. 11:130-146. 1962. On the larvae of the shortnosed spearfish, Tetrapturus angustirostris Tanaka. [In Jap., Engl. summ.] Rep. Nan- kai Reg. Fish. Res. Lab. 16:173-189. 1963. Methods for identification and discrimination of the larvae of five istiophorid species distributing in the Indo- Pacific. [In Jap., Engl. summ.] Rep. Nankai Reg. Fish. Res. Lab. 17:137-150. 246 1964. Description and distribution of larvae of five is- tiophorid species in the Indo-Pacific. Jn Mar. Biol. Assoc. India, Proc. Symp. Scombroid Fish., Part 1:499-528. UEYANAGI, S., and H. YABE 1959. Larva of the black marlin (Eumakaira nigra Nakamura). [In Jap., Engl. Summ.] Rep. Nankai Reg. Fish. Res. Lab. 10:151-169. U.S. HYDROGRAPHIC OFFICE. 1948. World atlas of sea surface temperatures, 2d ed. 1944. Hydrogr. Off. 225, 48 p. Y ABE, H. 1951. Larvae of the swordfish, Xiphias gladius. [In Jap., Engl. summ.] Jap. J. Ichthyol. 1:260-263. 1953. On the larvae of sailfish, /stiophorus orientalis collected in the South-western Sea of Japan. Contrib. Nankai Reg. Fish. Res. Lab. 6:1-10. YABE, H., S. UEYANAGI, S. KIKAWA, WATANABE. 1959. Study on the life-history of the sword-fish, Xiphias gladius Linnaeus. [In Jap., Engl. summ.] Rep. Nankai Reg. Fish. Res. Lab. 10:107-150. and H. O“Seo aL Hecmietidon Ss Oe Tene Sep sete! 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ABSTRACT Surface plankton collections, mostly with neuston nets towed at 4-5 knots, during eight cruises (1965-1972) yielded 119 swordfish larvae 6-110 mm total length. Captures were grouped in discrete geographical areas: Virgin Islands, Guiana current, Northwest Caribbean, Windward Passage, and Florida current. All collections were made in January-April, but comparison with other published data suggests that this may not be the peak spawning period. Descriptions of swordfish larvae are appended. In 1965, a program was initiated to study the dis- tribution and early life history of large pelagic fishes in the Northwest Atlantic Ocean. Forty-seven swordfish larvae were captured during the first cruise, which covered the Sargasso Sea, the Virgin Islands, and the Gulf Stream off Florida. Since re- latively little is known of the growth and behavior of young swordfish, subsequent cruises were designed to carry out a more systematic search for specimens and to study the environmental conditions under which they occur. ‘Fisheries Research Board of Canada, Biological Station, St. Andrews, New Brunswick, Canada. Table |1.—Fisheries Research Board The 1965 data have already been reported (Tibbo and Lauzier, 1969). In this report, all of the data are considered. MATERIALS AND METHODS Eight cruises were made during the period 1965-1972 (Table 1). Of these, five were to the Caribbean and adjacent seas, and three were to the Gulf Stream north of lat. 25°N. Most of them were carried out during the months of January, Feb- ruary, and March. Two of the Gulf Stream cruises were in April and May. In all, 280 stations were occupied (Fig. 1). 1 of Canada swordfish cruises, 1965-1972. No. of No. of larvae Cruises Dates Locations stations captured BIO-3 3-24 Feb. 1965 Sargasso Sea, 36 47 Virgin Islands Gulf Stream ATC-11 25 Jan.-11 Feb. 1966 Gulf Stream 31 9 EEP-3 4-18 Apr. 1967 NE of Cape Hatteras 14 2 Hudson-68 24 Mar-2 Apr. 1968 — SE of Barbados 8 CODC-69-003 1 Jan-5 Feb. 1969 Sargasso Sea, 51 10 Lesser Antilles CODC-69-023 28 Apr.-19 May 1969 N of Bermuda — CODC-70-004. 14 Feb-13 Mar 1970 Caribbean, 50 25 Gulf Stream system CODC-72-004 25 Feb.-23 Mar. 1972 Lesser Antilles 68 18 Southern Caribbean, Gulf Stream Total 280 119 252 jam T Fl + ei T WN Densley Sampled Moderately Sampled f= 35° Stations 0m eo Figure |.—Sampling areas and stations for Fisheries Research Board of Canada cruises. At each station, oceanographic data (tempera- tures, salinities, and oxygen content) were col- lected, and plankton tows were made. Three types of surface nets (“‘Lobster,’’ *‘Neuston,’’ and *‘ Her- ring’ nets) were used on the 1965 cruise (Tibbo and Lauzier, 1969). On more recent cruises most of the surface sampling was carried out with the ‘‘Neus- ton’’ net, which consists of an oblate meter ring with a 30 x 100 cm opening (Bartlett and Haedrich, 1968). Several deep tows were made with other nets. ““Neuston’’ nets were towed at 4-6 knots, while other nets were towed at various speeds from 2 to 5 knots. RESULTS During the eight Fisheries Research Board (FRB) cruises a total of 119 swordfish larvae was captured. These larvae, ranging in size from 6.5 mm to 110.6 mm, were found scattered over a large area (Table 2, Fig. 2), but there was no obvious pattern in size distribution with respect to time or location. Two small larvae were found east of Cape Hatteras in March. Many larvae were caught in the Gulf Stream from the Florida Straits to Cape Hatteras 253 during the months of January through March. Specimens were taken in the northeastern Gulf of Mexico (early March) and south of Cuba (late Feb- ruary). The regions west of the Lesser Antilles and southwest of Barbados were sampled in January and in March, yet larvae were found only in late March. Specimens were obtained in the Virgin Island-Leeward Islands area from January to March. Sampling in the following areas produced no lar- vae: Bermuda (January, May); northeast of Cape Hatteras (January, February, April, May); south- ern Caribbean (late February, early March); southwestern and central Sargasso Sea (January, February). Although surface temperatures ranged from 6.6°C to 26.9°C, larvae were found only at stations where temperatures were above 22.4°C. Similarly, within a total salinity range of 33.40°/oo to 37.88°/oo0 larvae were caught only where the salinity was 35.40°/oo or more. All but three of the larvae were taken in surface tows. The exceptions were caught in oblique tows and hence may have been captured as the net neared the surface (Tibbo and Lauzier, 1969). DISCUSSIONS AND CONCLUSIONS Our data alone are insufficient to establish spawning seasons and areas. However, when they are pooled with similar data from other sources (Fig. 3), it can be seen that the greatest densities of swordfish larvae occur in two regions: The Straits of Florida-Cape Hatteras area, and the Virgin Islands-Leeward Islands area. Larvae were also caught in the Gulf Stream northeast of Cape Hat- teras (four specimens), in the Gulf of Mexico, northwest Caribbean, southwest of Barbados, west of Lesser Antilles, and in the southern and eastern regions of the Sargasso Sea. It is believed that some swordfish spawning takes place in the Gulf Stream system from Cuba to Cape Hatteras. Evidence for this is provided by catches of both ripe adults and larvae. Table 2.—Larval swordfish captures by Fisheries Research Board of Canada. Total Temp. length Location Date (°C) Swordfish (mm) Bermuda Jan. 1969 219.0 — —_ May 1969 =20.0 — — Northeast of Jan.-Feb. 1966 _— — — Cape Hatteras Feb. 1970 — — — Apr. 1967 — — — Apr.-May 1969 -- — — East of Cape Mar. 1967 23.6 2 14.8, 29.5 Hatteras 23.5 = mas Gulf Stream, Feb. 1965 23.4 24 x = 66.1 south of Cape Hatteras Jacksonville- Jan. 1966 23-7. I 58.3 Savannah area Feb. 1965 25.0 1 28.7 Florida coast Jan. 1966 =22.4 8 20.8-51.5 Feb. 1965 25.0 7 18.7-38.9 Mar. 1970 24.0 ] 85.5 Mar. 1972 >24.4 5 21.9-110.0 Northeastern early Mar. 1970 24.4 5 13.0-66.3 Gulf of Mexico Northwestern late Feb. 1970 >24.0 12 9.5-41.0 Caribbean, south of Cuba 100 miles NE Feb. 1970 26.6 7 6.0-19.6 of Jamaica Southern late Feb.- =24.0 — as Caribbean, early Mar. 1972 west to Jamaica Southwest of Jan. 1969 =26.4 a — Barbados early Mar. 1972 =26.0 — — late Mar. 1968 >26.1 8 x = 28.1 West of Lesser Jan. 1969 =25.0 = _ Antilles Mar. 1972 >25.0 8 x =37.3 East of Lesser Feb. 1969 =26.0 _— = Antilles Virgin Islands Jan.-Feb. 1969 225.5 10 33.5-43.9 down to Feb. 1965 >24.6 15 36.5-80.2 Guadeloupe Mar. 1972 >24.5 5 17.6-60.6 Southwestern and Jan. 1969 =24 — — Central Sargasso. Feb. 1965 =24 — — Sea Feb. 1972 =24 — — Total 119 Information on the distribution of ripe females is available from both commercial and sportfishing operations. The Georges Bank area has been heav- ily fished, but there are very few reports of ripe females from this region, although some females bearing maturing eggs have been taken off the New England coast (Fish, 1926; Lee, 1942; Rich, 1947). In contrast, there are numerous accounts of ripe females caught off the northern coast of Cuba (Arata, 1954; Lamonte and Marcy, 1941). Accord- ing to Lamonte (1944), fishermen and anglers claim that swordfish bearing huge ovaries, with eggs ready to rupture the ovigerous membranes, are fre- quently found in the Cojimar, Cuba area, often ac- companied by another much smaller fish, presuma- bly the male. Such a distribution of ripe adult swordfish suggests that spawning occurs some- where off the north coast of Cuba, rather than much farther north. The occurrence of small larvae in the Florida Straits of Cape Hatteras region supports this conclusion. However, a single spawning area cannot account for the widespread distribution of larvae. In the Western Atlantic, it is probable that @ oO FRB Larval Captures [392 Length (mm) > oO oO swordfish spawn in widely scattered areas from which the larvae are further dispersed by currents such as the Gulf Stream. This contrasts with Gorbunova’s (1969) conclusion that swordfish spawning in the Pacific is restricted to areas of up- welling, where high productivity provides favorable conditions for both zooplankton and fish feeders such as larval swordfish. Gorbunova (1969) also concluded that young swordfish do not migrate far in the first year and thus are captured quite close to the actual spawning grounds. In the Western Atlantic, Arata (1954) proposed a large spawning area and an extended spawning period. From larval sizes and the growth rate of 0.6 mm/day suggested by Sanzo (1922), Arata esti- mated the approximate ages of his specimens, and deduced that peak spawning occurs at approxi- mately the same time in both the Gulf Stream and in the Gulf of Mexico—from May to June in the Gulf Stream and from late April to July in the Gulf of Mexico. Arata (1954) also suggested that larvae may be carried long distances in the Gulf Stream system. Making back calculations based on fish sizes and current speeds, and assuming passive drift Figure 2.—Numbers, size ranges, and mean lengths of swordfish larvae—Fisheries Re- search Board of Canada collections. 259 ra T ian ir 1 ; : = : Total Larval aor : oo 1 roy ee 67.5 120 80 : @ Ignace 4ol too ° ‘ 0 ; 30.8 e 479 i/o ae 90° Figure 3.—Numbers, size ranges, and mean lengths of swordfish larvae—collections from various sources including Fisheries Research Board of Canada. by even the larger (SO mm) larvae, he estimated an overall spawning period from the end of December to the end of September over a large area—from the lower Caribbean through the Yucatan Channel, the Straits of Florida, and the Gulf Stream system northwards to the South Carolina coast, 1.e. from about lat. 15S°N to about lat. 32°N. The data presented herein for the most part sup- port Arata’s (1954) conclusions, although they cover only the period from January to March. There are, however, a few discrepancies. Arata (1954) suggests that the sizes of his specimens from the northeast Gulf of Mexico further substantiate the theory that spawning occurs in the lower Carib- bean. For example, he concluded that, considering the current structure, one 55.4 mm specimen in the Gulf of Mexico would most likely have been spawned somewhere south of Jamaica around the first of March. However, sampling in the southern half of the Caribbean from November to April pro- duced no larvae (Ueyanagi et al., 1970). In his back calculations, Arata (1954) assumed that the major currents moving north from the Caribbean into the Gulf of Mexico do not swing 256 farther west than long. 88°W. Thus, larvae would be carried directly from the Caribbean into the north- eastern Gulf. The pilot charts of the North Atlantic and Sverdrup, Johnson, and Fleming (1942) show that, while the major currents do flow directly through the Straits of Florida (Fig. 4), the waters of the Gulf of Mexico form independent eddies. It is these secondary currents which flow into the north- eastern Gulf, and which also swing farther west than long. 88°W. The large larvae caught by Arnold (1955) in the southwestern (mean = 38.6 mm) and central (mean = 53.6) areas of the Gulf of Mexico may have been spawned in the southwest part of the Gulf and remained trapped there by the Gulf ed- dies. On the other hand, the presence of these lar- vae may indicate that secondary currents are suffi- ciently strong to transport larvae from the Carib- bean into the western reaches of the Gulf. Thus, larvae from the Caribbean could take a longer route to the northeast, initially via the more westerly cur- rents. Back calculations for the large specimens would then place their spawning areas somewhere in the northwest Caribbean where several small lar- vae have been found. Te T r ! Current Directions aso Seasonal -----> Figure 4.—Surface water circulation in the study area. From data collected on the 1965 cruise, Tibbo and Lauzier (1969) proposed a spawning ground for Gulf Stream larvae west of the Straits of Florida. They assumed that larvae from both the Florida Straits and Cape Hatteras areas came from the same spawning area. From this, they calculated a growth rate of 2mm/day and, using back calcula- tions similar to Arata’s, placed the spawning grounds in the southern Gulf of Mexico, and prob- ably in the Yucatan Channel. However, when other data are considered, it is obvious that this region is not the only spawning ground in the western Carib- bean. Similar calculations show that larvae caught off the coast of South Carolina would have hatched just south of the Florida Keys, while the larger lar- vae could conceivably have come from as far away as the eastern Caribbean. Such back calculations are only approximations since they assume uniform movement of water masses and passive drift by the larvae. However, even very young swordfish are active swimmers and no allowance can be made in the calculations for any active movement by the larvae. There are probably two distinct spawning areas 257 farther east, one southeast of Barbados, and the other in the Virgin Islands-Southern Sargasso Sea region. Spawning probably begins sometime early in the year southeast of Barbados. By March, young lar- vae would have drifted into the Barbados area, and west of the Lesser Antilles. This would account for the sudden occurrence of 30 mm larvae in late March, despite the absence of larvae in these areas earlier in the year. The patchiness of the distribu- tion west of the Antilles could be due to interfer- ence patterns produced by currents flowing be- tween the scattered Windward Islands. Larvae car- ried by these currents would tend to collect at the ‘‘nodes’’ of the pattern. Taning (1955) sampled the Virgin Islands- Sargasso Sea region year round, although his efforts during July to September were minimal. Consider- ing only those months with more than 100 h of fish- ing, he found that the largest catches were in Feb- ruary, March, and April. Although our cruises ac- cumulated only 70 h total fishing in this area during the months of January, February, and March, lar- vae were caught in all of these times, with peak catches in February. It is possible that more inten- sive sampling from July to September would show this time to be equally productive, since Taning (1955) obtained several larvae during these months despite low fishing effort. Temperature and Salinity Relationships On the basis of larval catches, it is believed that swordfish do not spawn in waters less than about 23°C. At one station where swordfish larvae were found, the surface temperature was 22.4°C, but at all other stations it exceeded 23.4°C. Other authors report similar findings (Arata, 1954; Taning, 1955; Kondritskaya, 1970). Spawning also apparently oc- curs only within a narrow range of salinities. Arata (1954) found larvae only in areas with salinities of 35.75°/oo or more. FRB sampled a wider range of salinities than did Arata, and also found larvae at lower salinities. One station had a salinity of 35.40°/oo. At all other larval stations, the salinity was 35.46°/oo or more. Thus, while the lower salinity limit remains indef- inite, it must be around 35.5°/oo. No estimate can be made of the upper salinity limit since both the FRB and Arata (1954) investigations found larvae at the highest salinities sampled. It should be noted that while temperatures and salinities may play an important role in the location of spawning grounds, these cannot be the sole de- termining factors, since very many stations with ‘“‘ideal’’ temperature and salinity conditions pro- duced no larvae. Vertical Distribution of Larvae and Time of Capture Swordfish larvae appear to frequent surface wa- ters. All but three of our specimens were caught in surface nets. Arata (1954) reported that 70-m oblique tows at each station captured only one lar- va. However, when the same equipment was used for one 30-min surface tow, it netted three small specimens. Most other larval captures were made using dipnets (Arata, 1954; Arnold, 1955; Gor- bunova, 1969) or a variety of nets towed horizon- tally at the surface. Taning (1955) used a 11% to 2-m ring net towed in the upper 30 m. Rivers (1966) reports 113 larvae caught in a single cruise with a 1-m nekton ring net. Gorbunova (1969) caught most of her specimens using a pleuston net in the upper 30 cm. 258 Gorbunova (1969) and Parin (1967) consider feed- ing behavior in explaining the predominances of larvae at the surface. They found that larvae were most abundant in the catches in the morning and evening and postulated that these twilight hours coincide with the periods of most intensive feeding. Presumably, at these hours the swordfish rise into the more productive surface layers to feed. At mid- day and at night, they disperse away from the sur- face. In contrast, Arata (1954) obtained his best catches by day (only three specimens were caught at night). Arnold (1955) caught most of his speci- mens at night though he may have attracted the larvae by nightlighting. Our data do not suggest such periodicity of oc- currence at the surface. Catch rates are similar for both the day (0600-1800) and night (1800-0800) hours. Nor is there any apparent increase in catch rate during the twilight hours. Not all surface tows take larvae. Taning (1955) noted that, while larger nets were successful, a 42-m ring net was easily avoided by even small larvae. In general, larvae more than 70-80 mm in length are seldom taken even in large nets towed at high speeds. SUMMARY From 1965 to 1972, eight cruises were made to the Caribbean and adjacent seas and to the Gulf Stream. Plankton nets were towed and oceano- graphic observations were made at 280 stations. Altogether 119 swordfish larvae from 6.5 to 110.6 mm were found in the following areas: Gulf Stream system from Florida to Cape Hatteras, northeast- ern Gulf of Mexico, northwestern Caribbean, west of Lesser Antilles, southwest of Barbados, and Virgin Islands. There appears to be an extensive spawning area in the northwestern Caribbean, Gulf of Mexico, and in the Gulf Stream system north to Cape Hat- teras. Two other spawning areas are proposed: one southeast of Barbados, and one in the Southern Sargasso Sea-Virgin Islands area. Swordfish larvae are seldom found in tempera- tures below 23.5°C. They were found only in waters with a salinity of 35.4°/oo or more. The larvae were caught almost exclusively in sur- face nets. Although other authors have suggested daily periodicity in larval abundance at the surface, catch rates for our collections were comparable for all periods of the day. ACKNOWLEDGMENTS The author wishes to especially thank the staff of the Pelagic Program at St. Andrews (especially James Beckett) for making the data available and for their assistance in the writing of this paper. I would also like to thank the Royal Ontario Museum and the Canadian Hydrographic Service for the part they played in collecting the data. LITERATURE CITED ARATA, G.F., JR. 1954. A contribution to the life history of the swordfish, Xiphias gladius Linnaeus, from the South Atlantic coast of the United States and the Gulf of Mexico. Bull. Mar. Sci. Gulf Canbb. 4:183-243. ARNOLD, E.L., JR. 1955. Notes on the capture of young sailfish and swordfish in the Gulf of Maine. Copeia 1955:150-151. BARTLETT, M.R., and R.L. HAEDRICH. 1968. Neuston nets and South Atlantic larval blue marlin (Makaira nigricans). Copeia 1968:469-474. FISH, M.P. 1926. Swordfish eggs. Bull. N.Y. Zool. Soc. 29:206-207. GORBUNOVA, N.N. 1969. Breeding grounds and food of the larvae of the sword- fish [Xiphias gladius Linné (Pisces, Xiphilidae)]. Probl. Ichthyol. 9:375-387. KONDRITSKAYA, S.I. 1970. The larvae of the swordfish [Xiphias gladius (L.)] from Mozambique Channel. J. Ichthyol. 10:853-854. LA MONTE, F. 1944. Note on breeding grounds of blue marlin and sword- fish off Cuba. Copeia 1944:258. APPENDIX: DESCRIPTIONS OF SWORDFISH (XIPHIAS GLADIUS) LARVAE All specimens were fixed in Formalin,” and then stored in alcohol. Hence, the pigment may have faded or become discolored. 6.0 mm— The larva is opaque white with scattered chromatophores on the snout, head, and body. The mandible is longer than the upper jaw. The teeth are beginning to develop. There are 7-8 supraorbital spines, and 5 preopercular spines—3 small ones at right angles to the lateral surface of the preopercule, and 2 long, *Reference to trade names does not imply endorsement by the National Marine Fisheries Service, NOAA. LA MONTE, F., and D.E. MARCY. 1941. Swordfish, sailfish, marlin, and spearfish. Ichthyol. Contrib. Int. Game Fish Assoc. 1(2):1-24. LEE, R.E. 1942. The occurrence of female sword-fish in southern New England waters, with a description of their reproductive condition. Copeia 1942:117-119. PARIN, N.V. 1967. On diurnal variations in the larval occurrence of some oceanic fishes near the ocean surface. [In Russ., Engl. summ.] Okeanologiia 7:148-156. RICH, W. H. 1947. The swordfish and the swordfishery of New England. Proc. Portland Soc. Nat. Hist. 4(2):1-102. RIVERS, J.B. 1966. Equipment note no. 18—A nekton ring net sampler for use aboard oceanographic research vessels. Commer. Fish. Rev. 28(2):9-12. SANZO, L. 1922. Vovae larve di Xiphias gladius L. Mem. R. Com. Talassografia Italiano No. 77, 17 p. SVERDRUP, H.U., M.W. JOHNSON, and R.H. FLEM- ING. 1942. The Oceans, their physics, chemistry, and general biology. Prentice-Hall, N.J., 1087 p. TANING, A. V. 1955. On the breeding areas of the swordfish (Xiphias). Pap. Mar. Biol. Oceanogr. Deep Sea Res., suppl. to vol. 3:438-450. TIBBO, S.N., and L.M. LAUZIER. 1969. On the origin and distribution of larval swordfish Xiphias gladius L. in the Western Atlantic. Fish. Res. Board Can. Tech. Rep. 136, 20 p. UEYANAGI, S., S. KIKAWA, M. UTO, and Y. NISHIKAWA. 1970. Distribution, spawning, and relative abundance of bill- fishes in the Atlantic Ocean. Bull. Far Seas Fish. Res. Lab. (Shimizu), 3:15-55. thin ones at right angles to the preoper- cular margin. There is evidence of fin rays in the fin folds. The eyeball has a distinct invagination of the lower curva- ture. 9.5 mm— The body is much more heavily pig- mented. The upper jaw has become slightly longer than the mandible. The teeth are better developed. Some spines have become evident on the snout and head and on the body in two longitudinal rows—one dorsolateral and one ven- trolateral. The fin rays have begun to develop in the caudal fin. The dorsal and anal fin rays are well developed. The eyeball is still invaginated. 16.5 mm—The dorsal pigment shows some evi- dence of vertical barring and some pig- ment is now present on the dorsal and caudal fins. The upper jaw is noticeably longer than the mandible. The teeth are well developed. The spines on the snout, head, and body have become larger and are more numerous. All the fins have well-developed rays. The eyeball is still invaginated. 32.5 mm—The dorsal barring has become much more pronounced and appears to consist of four or five ‘‘double bars’’. Pigment is much darker in the dorsal and caudal fins and has extended into the anal fin. Spines have developed on the ventral surface of the snout and have become nich more pronounced on the body. The two long preopercular spines have become greatly reduced. The eyeball is no longer invaginated. 62.5 mm—The pigment is more definite in both the ‘*double bars’’ and in all the fins except the pectorals, which still lack pigment. Both jaws, the head, and the body are covered with regular rows of fine spines. 6.0 mm Appendix Figure 1.—Drawings of swordfish larvae of various lengths. 260 The Distribution of the Larvae of Swordfish, Xiphias gladius, in the Indian and Pacific Oceans YASUO NISHIKAWA and SHOJI UEYANAGI' ABSTRACT The distribution of larval swordfish, Xiphias gladius, was determined on the basis of 325 specimens collected from Japanese research vessels operating in the Indian and Pacific Oceans. These larvae, ranging from 3 to 160 mm in total length, were caught by larva-net tows and by dip netting. The larvae are distributed over virtually the entire tropical and subtropical areas of the Pacific Ocean except for the eastern Pacific east of long. 100°W. The northernmost occurrence was at lat. 31°N, long. 132°E, near Kyushu in the western Pacific, and the southernmost was at lat. 22°38’S, long. 105°24'W in the eastern Pacific. Data were insufficient to delineate the distribution in the Indian Ocean. The surface water temperature in the areas of larval swordfish occurrence ranged from 24.1° to 30.7°C. The distribution of larval swordfish, Xiphias gladius, in the Indian and Pacific Oceans was de- termined on the basis of 325 specimens collected from Japanese research vessels. These larvae were collected largely by larva-net tows and included the 26 specimens previously described by Yabe et al. (1959). The results from this study supplement the findings on larval swordfish occurrence in the In- dian and Pacific Oceans by Taning (1955), Yabe et al. (1959), and Gorbunova (1969). The method of collection was as described by Ueyanagi (1969) and included surface tows as well as simultaneous sur- face (0-2 m) and subsurface (20-30 m) horizontal larva-net tows. SIZE OF THE LARVAE The 318 larvae collected by larva-net tows ranged in total length from 3 to 160 mm. Seven specimens taken by dip netting measured 34-80 mm. The length-frequency distribution of 280 larvae taken by net tows is shown in Figure 1. A very large proportion of the larvae was cen- tered around the 5 mm length class. The numbers rapidly decreased between 5 and 10 mm, after which they leveled off to about 30 mm. Very few larvae exceeded 50 mm in total length. * Far Seas Fisheries Research Laboratory, Shimizu, Japan. 261 N= 280 FREQUENCY No. 1s 20 25 30 3) 4) 7) 9 WW 13d 1ST 40 60 80 100 | 140 1 TOTAL LENGTH) mm Figure 1.—Length-frequency distribution of swordfish larvae collected by larva-net tows. VERTICAL DISTRIBUTION The fact that the larvae of swordfish are distri- buted largely at the surface is well known (Taning, 1955; Yabe et al., 1959; Gorbunova, 1969). The ver- tical distribution was further examined for possible day-night differences (Fig. 2). The catches in sur- face (0-2 m) and subsurface (20-30 m) tows were compared through relative densities represented by the percentage of occurrence, as follows: Number of surface tows on which larvae were caught x 100 Total number of simultaneous tows on which larvae were caught Surface = Number of subsurface tows on which larvae were caught x 100 Total number of simultaneous tows on which larvae were caught Subsurface = As seen in Figure 2, the density of larvae was greater at the surface both during the day and night. PERCENTAGE OF OCCURRENCE 20 40 60 80 = SE TUS T all 100 % a > ie Sb ZZ (n: 42) | am CY? NIGHT Figure 2.—Vertical distribution of swordfish larvae as seen from catches in surface (S) and subsurface (Sb) larva-net tows. The numbers of day (D) and night (N) stations at which larvae were caught are shown in parentheses. The difference between the surface and subsurface catches was quite marked during the day but not as much during the night. This difference probably represents diurnal vertical movements among larval swordfish. GEOGRAPHICAL DISTRIBUTION The occurrence of larvae was plotted by unit areas of I° squares (Fig. 3). Also included in the f oe 40 cm 80 100 20 same figure are the areas of relatively high catch rates for adult swordfish. The adult catch rates were based on 1970 data from the Japanese longline fishery, and included unit areas of 5° squares where the annual average catches exceeded 1.0 fish per 1000 hooks fished. (All unit areas where the total fishing effort consisted of less than 20,000 hooks were excluded.) The distribution of the larvae is seen to be con- tinuous in tropical and subtropical waters extending from the central Indian Ocean clear across to the eastern Pacific Ocean in the vicinity of long. 120°W. The apparent absence of larvae in the South China Sea and in the western Indian Ocean is probably attributable to lack of sufficient sampling effort in those waters since Taning (1955) and Gorbunova (1969) have shown the presence of larvae in these areas. The northernmost record of larval occurrence in the western Pacific was at lat. 31°N, long. 132°E, in the vicinity of Kyushu. In the central Pacific it was at lat. 25°N, long. 158°W, just to the north of the Hawaiian Islands, and in the eastern Pacific, at lat. 9°N, long. 120°W. The southernmost occurrence in the southwestern Pacific was at lat. 22°S, long. 170°E, and in the southeastern Pacific at lat. 22°38'S, long. 105°24'W. Although no larvae were caught in waters south of lat. 10°S in the central SWORDFISH © OCCURRENCE OF LARVAE ath : + Gate FISHING GROUNDS Y OOK RATE - 04 Figure 3.—Distribution of swordfish larvae (dots) and adults (hatched) in the Pacific and Indian Oceans. The adult distribution is represented by areas in which longline catches averaged greater than 1.0 fish per 1000 hooks during 1970, and where fishing effort exceeded 20,000 hooks fished. 262 South Pacific Ocean (between long. 120°W and 180°), this again may be due to insufficient sampling effort since Gorbunova (1969) showed the presence of larvae in this general area. On the other hand, the absence of larvae along the equator to the east of long. 140°W, and in the waters south of the equator to the east of long. 100°W is probably due to the effect of low temperature waters of the Equatorial Upwelling, Peru Current and the extension of the Peru Current. It has been shown by Taning (1955) and Gor- bunova (1969) that swordfish larvae occur in waters with surface temperatures higher than 24°C. The present data confirm these reports since larvae have been found in waters with temperatures ranging be- tween 24.1° and 30.7°C. In order to describe accurately the distribution of larval swordfish in the Pacific Ocean, further in- formation is needed from the central South Pacific and the eastern Pacific areas. It can be generalized, however, that the larvae are distributed very broadly in the north-south direction in the western Pacific and distributed more narrowly in the eastern Pacific. This pattern of distribution appears to be governed by the positions of the 24°C surface isotherm. As already mentioned, the absence of larvae from the western Indian Ocean was very probably due to insufficient sampling effort, since Gorbunova (1969) showed larvae occurring in waters east of Madagascar Island. In the Indian Ocean, also, it seems that the southern limit of distribution, at least, is determined by the location of the 24°C sur- face isotherm. SPAWNING OF SWORDFISH To derive some information on the spawning of swordfish, the size composition of larvae collected from the western Pacific in waters between lat. 20°N and 20°S was plotted (Fig. 4). This large area was grouped on the assumption that 24°C is the lower temperature limit for swordfish spawning, and since water temperature remains higher than 24°C throughout the year in this area. Newly hatched larvae, under 10 mm, were taken during all quarters of the year, indicating that spawning is taking place throughout the year in tropical and subtropical waters, at least in the west- er Pacific. If it is true that 24°C is the limiting temperature, then it also follows that if there is any 263 % al 50r JAN—MAR. a (23) 507 APR.—JUN. f (62) JUL.— SEP. (17) FREQUENCY 8 50 OCT.— DEC. (71) = =z = = 1 MN ZAy 25) 5] 7) 91 101 131 151 5 15 25 35 45 60 80 100 110 140 160 TOTAL LENGTH mm Figure 4.—Length-frequency distribution of larval swordfish, by quarters, taken in tropical and subtropical western Pacific Ocean between lat. 20°N and 20°S. (The number of larvae sampled in each quarter is shown in parentheses.) spawning in higher latitudes, it would be highly sea- sonal and limited to periods when temperatures are above 24°C. The areas of relatively high density of adult swordfish are separate and appear to surround the areas of larval distribution (Fig. 3). They are gener- ally located in the high-latitude, low-temperature areas. In the Pacific, these areas can be roughly divided into the northwestern Pacific, eastern Pacific, and the southwestern Pacific. Whether fish of different subpopulations occur in these areas is not now clear. Perhaps a more detailed study of the temporal and areal distribution of larvae will con- tribute toward the understanding of the popula- tion structure of the swordfish. ACKNOWLEDGMENT We especially wish to thank Tamio Otsu of the National Marine Fisheries Service, Honolulu, who read the manuscript and helped us with the English translation. We also wish to thank Kazuko Daito who prepared the illustrations. LITERATURE CITED GORBUNOVA, N.N. 1969. Breeding grounds and food of the larvae of the swordfish (Xiphias gladius Linné (Pisces, Xiphilidae)). Probl. Ichthyol. 9:375-387. TANING, A. V. 1955. On the breeding areas of the swordfish (Xiphias). Pap. Mar. Biol. Oceanogr., Deep Sea Res., suppl. to vol. 3:438-450. 264 UEYANAGI, S. 1969. Observations on the distribution of tuna larvae in the Indo-Pacific Ocean with emphasis on the delineation of the spawning areas of albacore, Thunnus alalunga. (In Jap., Engl. summ.) Bull. Far Seas Fish. Res. Lab. (Shimizu) 2:177-256. YABE, H., S. UEYANAGIT, WATANABE. 1959. Study on the life-history of the sword-fish, Xiphias gladius Linnaeus. (In Jap., Engl. summ.) Rep. Nankai Reg. Fish. Res. Lab. 10:107-150. S. KIKAWA, and H. Notes on the Tracking of the Pacific Blue Marlin, Makaira nigricans HEENY S. H. YUEN, ANDREW E. DIZON, and JAMES H. UCHIYAMA’ ABSTRACT In July of 1971 and 1972 five Pacific blue marlin, Makaira nigricans, were tagged with temperature sensing, ultrasonic transmitters off the west coast of Hawaii. These were tracked for durations up to 22% h. The paths of three showed movement in a northerly direction. The other two showed no movement. Average swimming speed ranged from 2.2 km/h to 3.4 km/h for the three fish tracked. Swimming depths differed considerably among the three. The Pacific blue marlin, Makaira nigricans, found off the Kona coast on the west side of the island of Hawaii has attracted sport fishermen from all over the world. Veteran anglers of that area usu- ally fish where the bottom slopes steeply from 200 to 2,000 m; but movement patterns of this prized fish, if patterns do indeed exist, are unknown. The Honolulu Laboratory of the National Marine Fisheries Service initiated a project in 1971 to study the movements of the blue marlin using a fish tag that transmitted ultrasonic pulses. The research ship, Charles H. Gilbert, tracked one blue marlin during 13-16 July 1971, and four during 24-29 July 1972. Fish were tracked for periods ranging from 1 to 22% h. Path, depth, and speed of swimming are reported. MATERIALS AND METHODS Transmitter and Receiving Equipment The basic unit of the system is the ultrasonic tag. The tag, cylindrical with faired ends, measures 16.5 cm long and 1.8 cm in diameter (Fig. 1a). It produces a 50 kHz carrier signal with a pulse rate that is a function of the surrounding water temperature. Es- timation of depth of fish is then possible. The tags have a temperature range of 7°-27°C, an active life of 10 days, and a reception range of about 1.2 km with the equipment aboard Charles H. Gilbert. * NOAA, National Marine Fisheries Service, Southwest Fisheries Center, Honolulu Laboratory, Honolulu, HI 96812. The tags are attached to the fish with a leader of fine monel wire rope (0.7 mm diameter). The 25-cm leader is embedded at one end of the tag and crimped to an anchor plate of curved, stainless steel (Fig. lb). The plate is 7.4 by 1.8 cm with a sharpened end. A specially tooled rod at the end of 2% m pole (Fig. 1c) is used to force the anchor plate into the back of the marlin. The drag of the tag and the curvature of the plate move the plate into position under the skin. The toughness of the skin holds the plate in place. Ultrasonic signals are received via a hydrophone (Honeywell, model HX-74C?) mounted in a well in the hull of Charles H. Gilbert and a low-frequency receiver (Lawson) mounted on the bridge. Pulse fre- quency is determined by visually displaying output signals on a storage oscilloscope (Tektronix, model 564). Sensitivity of the hydrophone to 50 kHz trans- mission is minus 70 db volt/microbar. The cone- shaped beam of the hydrophone has a width of 25° at the minus 3 db level. The hydrophone can be rotated horizontally 125° on both sides of the bow and verti- cally 90° by electric scan motors controlled by the tracker on the bridge. Capture and Tagging of Blue Marlin Bart Miller and his sport fishing boat, Christel, (Kona, Hawaii) were engaged to catch and tag mar- lins. Fish were caught by trolling. As soon as a marlin struck, the line was pulled in by hand to bring ? Reference to trade names in this publication does not imply endorsement of commercial products by the National Marine Fisheries Service. Figure 1.—Ultrasonic transmitter and tagging apparatus. a. Temperature sensing transmitter. b. Anchor plate. c. Rod for applying anchor plate. d. All items as- sembled. the fish alongside as quickly as possible. When the fish was alongside the boat, its condition was checked and its size was estimated. If the fish ap- peared to be in good condition, the tag was inserted and the fishing line was cut to release the fish. Many of the people of the sportfishing community took an active interest in the tracking project. Asa result several fishermen offered to donate their mar- lins. Upon receiving radio communication that a fisherman was willing to donate a hooked marlin, Christel transferred the tag, harpoon, and sometimes a crew member. Tagging operations on the other boats were similar to those aboard Christel. Tracking Procedures During the catching and tagging operation Charles 266 H. Gilbert was positioned 200-300 m away from the fishing boat. Upon release of the fish, the following data were recorded at 5-min intervals: time, ship’s heading, relative bearing of the hydrophone, tilt angle of the hydrophone, and pulse rate of the tag. Ship’s position was determined and recorded at half-hour intervals. Because of poor signal-to-noise ratios, it was not always possible to measure the pulse rate. Because of a malfunction in the tilt angle indicator during the 1972 operations, the observer was sure of the tilt angle only when the hydrophone was at 0° or 90°. The ship was guided to maintain a distance of approximately 800 m from the estimated position of the tagged marlin. Actual distance between ship and fish continually varied from about 400 to 1,200 m for the following reasons: (1) the minimum forward speed of the ship was 4 knots; (2) the ship was not permitted to go astern because the cavitation bub- bles from the propeller would completely block the tag signals; (3) the distance between tag and ship could only be estimated from the strength of the signals from the tag. A bathythermograph cast was made every 4h to obtain temperature-depth profiles. These profiles and the temperature-dependent pulse rates of the tags enabled estimation of swimming depth of the marlin. RESULTS Five blue marlin were tagged and tracked, one on 14-15 July 1971 and four between 25 and 28 July 1972. Dates, size of fish, duration of tracking and remarks on each fish are listed in Table 1. The first tagged marlin was tracked for 22 h 25 min before an equipment breakdown forced a stop. The second fish was in doubtful condition when released. It was difficult to track and contact with it was lost after an hour. The third marlin was tracked for 5 h 22 min before it was lost because of a tactical error. Marlin #4 was abandoned after 7 h because it remained stationary on the bottom soon after it was tagged. After 2 h of swimming the fifth marlin also went to the bottom. Path The paths of the marlin tracked are shown in Fig- ures 2 and 3. The path of the last marlin is, of course, of questionable value as the fish lived only 2 h after being tagged. A feature that stands out is that all three marlin moved in anortherly direction. Northof Keahole Point there is only one instance where the Table 1.—Data on blue marlin tagged. Marlin Estimated Duration No. weight Date tagged tracked Remarks kg (lb) h 1 270 (600) 7/14/71 224% Lost—equipment failure. 2 225 (500) 7/25/72 1 Lost—no movement. 3 135 (300) 7/25/72 SY’ Lost—tactical error. 4 160 (350) 7/27/72 Tl’ Abandoned—no movement. 5 70 (150) 7/28/72 8 Abandoned—no movement after 2 h. 267 Figure 2.—Path of blue marlin tracked in 1971. Numbers along track denote hour of day. % ° “AY 2 3 4 | 5 % % eet + + + % S ee NAUTICAL MILES | % é é | % i 2g S 2000 £ 50" 1 & | ¢ ; p'900 iy & 4 a] / 41800 if 1 ton 1 ‘ \ Ne Q ‘440 TAGGED & 47/25/72). tad ‘ Sa HAWAII 1135 »_AIT00 S \ 1629 TAGGED KEAHOLE PT. \(7/28/72) e 05 I5e* Figure 3.—Path of two blue marlin tracked in 1972. Num- bers along track denote hour of day. marlin ventured beyond a bottom depth of 2,000 m (Fig. 3). This marlin appeared to be returning to shallower water when contact with it was lost. Swimming Depths The choices of swimming depths were quite dif- ferent among the three marlin tracked. The largest marlin (#1), estimated at 270 kg (600 Ib), spent half of the time within 10 m of the surface, a sixth of the time between 10 and 30 m, and the remaining third of the time deeper than 30 m. The maximum swimming depth, which was 80 m, was reached only on one occasion. The next largest marlin tracked (about 135 kg or 300 Ib) remained at depths between 115 and 185 m throughout the 5% h that it was tracked. The last and smallest blue marlin tracked (about 70 kg or 150 lb) remained in a depth zone of 60-85 m before it went to the bottom after 2 h. The vertical movements of the largest marlin did not show any pattern that could be related to time of day. The other marlin were not tracked long enough to determine if any pattern existed. Swimming Speeds Swimming speeds of the three marlin were calcu- lated based on the distance traveled every half hour. Results are in Table 2. The average swimming speed of the last marlin is high compared with the others especially in terms of body lengths per second. Mar- lin #1 and #3 had an average swimming speed of 0.23 body length/sec. Marlin #5, in contrast, aver- aged 0.45 body length/sec. The higher speed of the last marlin may be a reflection of the distress of a dying marlin. The maximum for the largest (#1) and the smallest fish (#5) were 0.62 and 0.68 body length/sec com- pared with 0.32 body length/sec for marlin #3. The two larger marlin (#1 and #3) both had minimum speeds of 0.09 body length/sec while the minimum speed of the smallest was 0.19 body length/sec. DISCUSSION A counterclockwise eddy west of the northern half of the island of Hawaii persists there most of the time (R. A. Barkley, pers. comm.). The area of our marlin tracking coincides with that part of the eddy which flows northward. The fact that all three marlin tracked exhibited a northerly movement suggests the possibility that the blue marlin orients or drifts with currents. One of the problems in tracking marlin is getting one that will survive the trauma of being caught. Of the five marlin tagged two died and one probably died. Three others were caught and not tagged be- cause of their poor condition. To enhance the prob- abilities of success in marlin tracking, consideration should be given to ways of attaching the tag without catching the fish. ACKNOWLEDGMENT We wish to acknowledge the generosity and coop- eration of anglers Alex Smith and Darrell Turner and skipper Monty Brown and Wes Vannatta for donating their catch for tagging. Special thanks go to Bart Miller and his mate, Murray Mathews, of the boat Christel for their enthusiasm and patience. We also wish to thank Jack Benson and the students of his Marine Technology training course of Leeward Community College. Table 2.—Swimming speeds of blue marlin. Minimum Marlin body- No. km/h knots length/sec km/h knois Maximum Average body- body- length/sec km/h knots length/sec 1.1 0.6 0.09 8.2 0.5 0.09 3: 1.5 0.8 0.19 5 Ji bd S ‘oO 0.62 3.0 1.6 0.23 0.32 2.2 1.2 0.23 0.68 3.4 9 0.45 Section 4. Fisheries. An Analysis of the Sportfishery For Billfishes in the Northeastern Gulf of Mexico During 1971 EUGENE L. NAKAMURA! and LUIS R. RIVAS? ABSTRACT Data were obtained on the sportfishery for billfishes off South Pass, Louisiana, and off northwest Florida in 1971. These data included: dates and times of raises, hookups, and catches by species; locations of raises; areas fished; baits used; water color; surface conditions; boat characteristics. A total of 99 blue marlin (Makaira nigricans), 284 white marlin (Tetrapturus albidus), and 318 sailfish (Istiophorus platypterus) was caught and recorded during 11,107 hours of fishing in the northeastern Gulf of Mexico. White marlin was most abundant in July and August, while sailfish was most abundant in the latter half of September off northwest Florida. Similar periods of abundance for these two species were not evident off South Pass. Blue marlin did not have an especially abundant period in either area. White marlin and sailfish were more abundant off northwest Florida than off South Pass, whereas the reverse was true for blue marlin. The hours of greatest relative abundance for all species of billfishes combined were between 1000 and 1200 and again between 1300 and 1500 off South Pass. A similar pattern was found off northwest Florida (1000-1100 and 1400-1500). Results indicated that the bluer the water, the greater the relative abundance of each of the three species. Off South Pass more billfishes were raised along lines and rips than in any other surface condition, whereas off northwest Florida, more billfishes were raised in open water than in any other surface condition. Moon phase appeared not to have any significant effect on billfishing. Neither did the length of the fishing boats. However, of the boats in the 40 to 49 ft length category, those with twin screws raised more billfishes than those with single screw. Off northwest Florida, blue marlin preferred mullet (Mugil cephalus) over ballyhoo (Hemiramphus sp.) and bonito (Euthynnus alleteratus) strip as bait; white marlin showed no preference; while sailfish preferred bonito strip. Off South Pass, data on bait preference were insufficient to allow conclusions. The sportfishery for billfishes in the northeast- ern Gulf of Mexico began in the mid-1950’s. Al- though sailfish (Istiophorus platypterus) were occa- sionally caught in nearshore waters, the sport- fishery for big game fishes did not get underway until blue marlin (Makaira nigricans) and white marlin (Tetrapturus albidus) were discovered in offshore waters of the Gulf of Mexico by the re- "NOAA, National Marine Fisheries Service, Gulf Coastal Fisheries Center, Panama City Laboratory, Panama City, FL 32401 2NOAA, National Marine Fisheries Service, Southeast Fisheries Center, Miami, FL (present duty station, Panama City Laboratory, Panama City, FL 32401). 269 search vessel Oregon of the U.S. Fish and Wildlife Service (Bullis, 1955). Impressive longline catches of blue marlin and white marlin had been made off South Pass at the mouth of the Mississippi River by the crew of the Oregon. Following this discovery, a sportfishery for big game fishes began off the Mis- sissippi delta. The first catches of white marlin, blue marlin, and yellowfin tuna (Thunnus albacares) by sportfishermen were made off South Pass in June, 1956 (Kalman, 1970). In the years that followed, the sportfishery for billfishes expanded, so that sportboats from Pen- sacola, Destin, and Panama City (all ports in northwest Florida) were also participating in the sportfishery. In Destin, sailfish had been caught as early as 1955, but the first white marlin was landed in 1959 and the first blue marlin in 1962. In 1964, at least 33 marlin (blue and white combined) and 98 sailfish had been caught. The early history and de- velopment of the sportfishery for billfishes in the northeastern Gulf of Mexico was reported by Siebenaler (1965). Boats of various characteristics are used in the sportfishery. Boat lengths vary from less than 20 ft (6.1 m) to over 60 ft (18.3 m). Either gas or diesel engines are used. The number of lines fished from a boat may vary from two to four; however, most boats fish four lines, the two outer lines generally trailing out from outriggers. Most boats also use ‘teasers,’ devices trolled at short distances astern to attract fish. Soft drink bottles, bunched-up strands of colored nylon or other synthetic material, and other devices are used as teasers. Generally, two, one on each side of the stern, are used. Analyses of data on sportfisheries for billfishes are rare, probably owing to lack of record keeping. The best analysis made to date was of the sport- fishery for sailfish off Kenya during 1958-68 by Wil- liams (1970). Data from a sportfishery for billfishes combined with data from the commercial fishery were used by Strasburg (1970) for his analysis of the Hawaiian fishery. A report to anglers by Nakamura (1971) presented the results of an analysis of data kept by the New Orleans Big Game Fishing Club for the area off the Mississippi River Delta during the period 1966-70. A subsequent similar report for anglers for the year 1971 was expanded to include the northwest Florida area (Nakamura and Rivas, 1972). Our report presents the results of studies made on the sportfishery for billfishes in 1971 in the northeastern Gulf of Mexico. This study was initi- ated in 1970 at the Panama City Laboratory (known then as the Eastern Gulf Marine Laboratory) of the National Marine Fisheries Service in Panama City, Florida. Much data were provided to us by sportsmen and boat captains and members of big game fishing clubs and charter boat associations in New Orleans, Mobile, Pensacola, Destin, and Panama City. SOURCE AND TREATMENT OF DATA Two distinct areas were fished (Fig. 1). One was the area off South Pass at the mouth of the Missis- sippi River. This was fished by members of the New Orleans Big Game Fishing Club. The other was the area offshore of northwest Florida. This was fished by boats out of Pensacola (both the Mobile Big Game Fishing Club and the Pensacola Big Game Fishing Club), Destin (Destin Charter Boat Association), and Panama City (Panama City Charter Boat Association). Because these two areas did not overlap, we separated their respective data in our analyses. The data supplied by sportfishermen and boat captains were recorded on logs (Fig. 2). The New Orleans Big Game Fishing Club had a chart of the South Pass area on the reverse side of its logs, while the other clubs and associations had a chart of the northwest Florida area on the reverse side of their logs. The charts of the two areas were divided into 10-minute squares (Fig. 1). Each square was al- phabetically and numerically labeled, so that loca- tions of fish sightings and catches could easily be identified. Bottom contour lines were also drawn on the charts. The New Orleans Big Game Fishing Club also added compass headings on its chart. In most instances, the anglers drew their tracks from the start to the end of fishing on the charts and marked the locations of fish sightings along their tracks. The kinds of data recorded on the logs (Fig. 2) included dates and hours of fishing; areas fished; locations and times of raises, hookups, and catches by species; baits used; water color; surface condi- tions; and boat characteristics. Morphometric and biological data were obtained on specimens after obtaining permission from the angler or boat cap- tain. The only biological data presented in this re- port are sex ratios. The morphometric data are pre- sented in another paper (Lenarz and Nakamura, 1974). Our analyses were made for blue marlin, white marlin, and sailfish. Data for all three plus uniden- tified billfish were combined for billfishes in gen- eral. In some instances, we made analyses only for total billfishes, as data by species involved very small numbers, or zeros. Three distinct events occur while billfishing: first, a fish is raised, that is, a billfish comes up toa bait from below, or comes over to a bait from a lateral zone, and while the fish may investigate one or several of the offered baits, it may or may not take one; second, the fish may be hooked, and it may be fought for varying lengths of time, and sub- sequently, either lost or boated; and third, the fish “OOIX9IA] JO J[NH Usd}svay}A0U dy} Ul seoIe SuIYSsT] OM} VY J—"] 9NTI4 neh Ov 0S 098 _ Ol 02 Of 0b 0S _o28 fel 02 "TeIH] 11H] OlH] GH] OH] ZH] 9H] SH] oH]: GH] cH] 1Hjoe? 5 16 : é ‘ f ; aie gars} _o1at_6518at Zot 99] sal pal ea] e570! , ele | Bee tae as 021 |697 |e za] Wap Ord}. 64s. 84] 23l 93a! Sal bal’ esl eat- 1al°? F i 008 Sel ete % ei Re eee Roe | é : oe y Salen adic zia|__ wal: Ola} . Gal O3| Zal 93] S3| bap cal Zag tal | q OG,..- 2 | jeer E lees slik z10 nat: ola] 6a". So} Za} 90h sa; barca zo) ra}o? | Le : . ; é joer [st Sa uwOl i 1 (Ee 0S ‘4 aa Kt {21 | | eo ; = ae Fs = id . 3 s i Eas | s27- -|p23-| vavava>) Olv] 6vl ev) Zvl owl sul | ae bv] cvl 7ev wo | rf NILS30_-3e et | DAILY BOAT LOG Date Boat Captain Ro. Linss Fished Areas Fished Fishing Time: Start End Angler Phone Address Street or P.O. Bor City State Zip Code Remarks - Line weight, Reel size: Figure 2.—Daily boat log used by big game fishermen in the northeastern Gulf of Mexico. is boated, that is, it is either brought aboard, or brought up to the boat and released. In determining relative abundance, the number- of-fish-RAISED-per-hour-of-fishing (raises- per-hour) was used as an index in most instances rather than the number-of-fish-CAUGHT- per-hour-of-fishing (catch-per-hour). We felt that the former was much less affected by the skill of the angler than the latter. If a fish were hooked and lost, it would not be included in the catch-per-hour, but it would in the raises-per-hour. Use of raises- per-hour offered an additional advantage: much more data were available. The disadvantages were the possibility of the same fish being raised more than once, and the possibility of misidentification of the species. We felt that the advantages outweighed the disadvantages. In determining the number of hours fished, we deducted the time spent fighting a fish. Whenever a fish is hooked, all lines except the one with the hooked fish are reeled in. Thus, if a fish were hooked at 1000 h and boated (or lost, or released) at 1130 h, 1% h were deducted from the total fishing time, which was derived by subtracting the time the lines were put in the water from the time the lines were pulled out preparatory to returning to port. The number of lines trolled was not considered, 272 as we felt that this factor had little influence on whether or not a fish was raised. Most boats trolled four lines, although a few of the small boats trolled only two or three lines. Sailfish were often caught while trolling inshore for king mackerel (Scomberomorus cavalla), Spanish mackerel (Scomberomorus maculatus), and cobia (Rachycentron canadum). Since the fish- ing method for these smaller game fishes is different from big game fishing, all sailfish caught and the effort expended for this type of fishing were disre- garded. : Where data were insufficient or lacking to permit the use of raises-per-hour, other indices of relative abundance were used. Catch-per-hour, hookups- per-day, and percentages were used in some of our analyses. True estimates of abundance could not be obtained. Therefore, the term abundance when used in this paper refers to relative abundance. Data for years prior to 1971 for South Pass are pre- sented for historical comparison in some tables of this paper. These data were taken from Naka- mura’s mimeographed report (1971). We believe that we obtained data from more than 90% of the total effort expended in offshore sport- fishing for billfishes in the eastern half of the Gulf of Mexico (from the mouth of the Mississippi River to the west coast of Florida). The amount of billfishing occurring between Panama City, Florida, and the southern tip of Florida is negligible (less than 5% of the total in the eastern half of the Gulf of Mexico, we believe). Billfishing other than from South Pass and the three ports in northwest Florida (Pen- sacola, Destin, and Panama City) in the northeast- ern gulf coast is also negligible (also less than 5% of the total in the eastern half of the Gulf of Mexico). We do not have any measures of the reliability of the data provided by the sportfishermen. We can report that almost all the sportfishermen appeared to be very sincere and genuinely interested in help- ing and cooperating with us. Data that were obvi- ously erroneous were discarded; data that were questionable were disregarded. Further details of the method of analyses are pre- sented in the following sections of this paper. CATCH, RAISE, AND EFFORT STATISTICS The number of billfishes raised, hooked, and boated by months for both the South Pass and northwest Florida areas are presented in Tables 1 and 2. Although a few trips were taken as early as April, the fishing season essentially lasts from May through October. If the percentages at the bottom of Tables | and 2 may be considered as indices of the proficiency of anglers, an obviously significant difference can be Table 1.—Billfishes raised (R), hooked (H), and boated (B, includes releases) off South Pass, 1971. Uniden- tified Species Blue Marlin White Marlin Sailfish Billfish Event Re Heeb Reeve Be Reor Hes 9B. RG! EH Apr. 0 (1) CU te = 9) OOo OOo a May 13 Syn 6 DORs (Ome "Oe Dir vod June 292" IY aS Gem 9a Ayes) 2h 0e y x0 July 60 31 S40) Sal i7, Ciel 2 a7; 3 0 0 Aug. CL Bi QUA ASB AOS 10) Sep OD a elt 4 Opeh 2 ll 0) OO Oct. 4 ie OMS, BFW OO ee) Motale20350093.— 341676 162" 185235) 21 7 2 % of Raised 45.8 16.7 37.1 10.8 67.3 40.4 28.6 % of Hooked 36.6 29.0 60.0 273 Table 2.—Billfishes raised (R), hooked (H), and boated (B, includes releases) off northwest Florida, 1971. Uniden- tified Species Blue Marlin White Marlin Sailfish Billfish Event Res Ee BS Reese B Ro) JH BB eee R ease May 2 2 i}! ea 3 1 AE 09) ee) 0 June Bh Ih} Sys 7) IE sh ey Ail 1 1 July 52) 32 8 289 167 104 114 68 49 10 2 Aug. 19) vaay 23° 212-126. 84°" 194° 123) 81 15 1 Sept. LU) IB Deed A PIN Sie TPB 2 0 Oct. 6322365) 13.85 64. 44) 98 49." 32 4 2 Total 289 169 65 682 416 266 808 455 297 32 6 % of Raised 58.5 22.5 61.0 39.0 56.3 36.8 18.8 % of Hooked 38.5 63.9 65.3 seen between the two areas for white marlin. In the South Pass area, only 37.1% of the 167 raised white marlin were hooked; of the 167, only 10.8% were boated; and of the 62 hooked white marlin, 29.0% were boated. Comparable percentages for white marlin in the northwest Florida area were 61.0, 39.0, and 63.9. Little difference between areas is seen for the other two species. Although we are unable to provide any factual information to explain the greater percentages of hooked and boated white marlin in the northwest Florida area, we can provide some conjecture. One is that many more boats from northwest Florida are captained by professional fishermen (charter boat captains), whereas most of the boats from South Pass are captained by sportfishermen. Second, white marlin are much more abundant in northwest Florida, thus providing more experience with this species to the fishermen from this area. A comparison of the catch, effort, and catch- per-hour of billfishes in the two areas is presented in Tables 3 and 4. Catch-per-hour is used here, as data on raises were not available prior to 1971. For South Pass, the total number of billfishes (73) caught in 1971 was the second lowest. Fewer white marlin were caught in 1971 than any previous year of record. The catch-per-hour indicated that 1971 was in general a below average year: about average for blue marlin, lowest of any year for white marlin, and below average for sailfish. More than twice as much effort was expended off northwest Florida (7,890 h) than off South Pass Table 3.—Catch, effort, and catch-per-hour of billfishes off South Pass, 1966-71. Table 4.—Catch, effort, and catch-per-hour of billfishes off northwest Florida, 1971. Year 1966 1967 1968 1969 1970 1971 Number caught Blue marlin 57 42 72 25 19 34 White marlin 151 113 95 38 22 18 Sailfish 42 46 30 12 20 21 Total hours fished — 2,339 5,801 4,139 2,603 3,217 Catch-per-hour Blue marlin — 0.018 0.012 0.006 0.007 0.011 White marlin — 0.048 0.016 0.009 0.008 0.006 Sailfish — 0.020 0.005 0.003 0.008 0.007 (3,217 h) in 1971. Of the effort expended in north- west Florida, boats from Destin accounted for 69% of the total. Blue marlin were more abundant off South Pass than off northwest Florida in 1971, as indicated by the catch-per-hour (0.011 versus 0.008), whereas white marlin (0.034 versus 0.006) and sailfish (0.038 versus 0.007) were more abundant off northwest Florida (Tables 3 and 4). When raises-per-hour were compared (Table 5), the same conclusions of relative abundance were reached. The reciprocals of raises-per-hour, that ts, hours-to-raise-1-fish, are also presented in Table 5. Fewer hours were spent trolling off South Pass to raise a blue marlin (15.9 versus 27.0), whereas fewer hours were spent off northwest Florida for white marlin (11.6 versus 19.2) and for sailfish (9.8 versus 62.5). SIZE AND SEX RATIO The range of weights and the average weights for each species for the two areas are presented in Ta- bles 6 and 7. The largest blue marlin, 492.0 lb (223.6 kg), caught in 1971 was off South Pass; the largest white marlin, 86.0 lb (39.1 kg), and the largest sail- fish, 67.0 lb (30.5 kg), were caught off northwest Florida by boats from Destin. For South Pass, the range and average for blue marlin was not unusual; neither was the average for sailfish. However, the largest specimens of white marlin, 84.0 lb (38.2 kg), and of sailfish, 58.5 lb (26.6 kg), were smaller than the largest specimens of each species caught in any previous year of record. And the average weight of white marlin, 61.3 lb (27.9 kg), in 1971 was the high- est ever. Females of all three species of billfishes domi- nated the catches. Sex ratios for the years 1967-71 274 Panama All Three Port Pensacola Destin City Ports Number caught Blue marlin 17 43 5 65 White marlin 4] 195 30 266 Sailfish 18 265 14 297 Total hours fished 1,834 5,425 631 7,890 Catch-per-hour Blue marlin 0.009 0.008 0.008 0.008 White marlin 0.022 0.036 0.048 0.034 Sailfish 0.010 0.049 0.022 0.038 for South Pass and for 1971 for northwest Florida are presented in Table 8. Only those specimens were examined for which permission was granted. The predominance of females in the blue marlin caught off northeastern Gulf of Mexico is contrary to that in blue marlin caught off Puerto Rico and the Virgin Islands (Erdman, 1962, 1968). There, an equal male-female ratio was found during July and August, the months of spawning. In September, the ratio changed to 4.5:1 in favor of males. The annual average for catches of blue marlin from 1950-66 was 4:1 in favor of males. Sex ratios of white marlin caught off New Jersey and Maryland, like those caught in the northeastern Gulf of Mexico, also favored females. In 1959, the male-female ratio was 1:2.4; in 1960, it was 1:1.2 (de Sylva and Davis, 1963). RELATIVE ABUNDANCE BY TIME The number of raises per hour was determined for weekly periods and hourly periods. Each week began on a Wednesday and ended on the following Table 5.—Relative abundance of billfishes in the north- eastern Gulf of Mexico, 1971. Northwest Area South Pass Florida Raises-per-hour Blue marlin 0.063 0.037 White marlin 0.052 0.086 Sailfish 0.016 0.102 Hours-to-raise-1-fish Blue marlin 15.9 27.0 White marlin 19.2 11.6 Sailfish 62.5 9.8 Table 6.—Weights in pounds (kilograms in parentheses) of billfishes caught off South Pass, 1966-71. Year 1966 1967 1968 1969 1970 1971 Blue marlin Range 65.0-565.0 62.0-565.0 77.0-465.0 133.5-686.0 90.5-535.0 83.0-492.0 (29.5-256.8) (28.2-256.8) (35.0-211.4) (60.7-311.8) (41.1-243.2) (37.7-223.6) Average 219.7 299.0 252.0 273.4 273.7 279.4 (99.9) (135.9) (114.5) (124.3) (124.4) (127.0) White marlin Range 29.0-100.0 30.0-134.0 32.0-85.0 39.0-86.0 36.0-85.0 33.0-84.0 (13.2-45.5) (13.6-60.9) (14.5-38.6) (17.7-39.1) (16.4-38.6) (15.0-38.2) Average 48.9 46.5 50.0 59.6 53.3 61.3 (22.2) (21.1) (22.7) (27.1) (24.2) (27.9) Sailfish Range 27.0-80.0 25.0-75.0 36.0-78.0 35.0-66.0 25.0-67.0 37.0-58.5 (12.3-36.4) (11.4-34.1) (16.4-35.5) (15.9-30.0) (11.4-30.5) (16.8-26.6) Average 45.5 46.4 40.1 Syle7/ 40.3 43.1 (20.7) (21.1) (18.2) (23.5) (18.3) (19.6) Tuesday, so that a weekend was not split. Each hour began on the hour and ended 1 min before the next hour. The results of our analyses of raises per hour by weekly periods are presented in Figure 3. For the South Pass area, blue marlin were most abundant in late September; white marlin were most abundant in early August; sailfish did not appear to be espe- cially abundant during any week (only 52 sailfish were raised during the entire year). For the north- west Florida area, the highest peak in relative abundance of blue marlin was the week 29 Sept. to 5 Oct., but the weekly variations were not as great as for the other two species; for white marlin the pro- nounced period of abundance was in mid-July; sail- fish were especially abundant during the latter half of September. Several prominent differences in raises-per-hour by weekly periods are evident between the two areas (Fig. 3). For example, peaks of abundance for white marlin and sailfish in the South Pass area are not as pronounced as in the northwest Florida area. Also, blue marlin are more abundant off South Pass, whereas white marlin and sailfish are more abundant off northwest Florida. The results of our analyses of raises-per-hour by time of day are presented in Figure 4. The numbers of fish raised and numbers of hours trolled are tabu- lated in Tables 9 and 10. The early morning (0600 h) peak for South Pass and late afternoon (1800 h) peak for northwest Florida should be regarded cautiously, as these are based on small amounts of effort. The patterns of abundance by time of day for each species in each area (Fig. 4) show a pre-noon and a post-noon peak, with some showing two pre- noon peaks (blue marlin and white marlin off northwest Florida) and some showing two post- noon peaks (white marlin off northwest Florida, blue marlin and white marlin off South Pass). All show a midday drop in abundance. When data for all three species from both areas are combined (Fig. 5), a multimodal distribution is seen, the most prominent peak at 1000 h and smaller peaks at 1400 and 1800 h. Table 7.—Weights in pounds (kilograms in parentheses) of billfishes caught off northwest Florida, 1971. All Three Port Pensacola Destin Panama City Ports Blue marlin Range 32.0-481.5 46.0-426.0 128.0-253.0 32.0-481.5 (14.5-218.9) (20.9-193.6) (58.2-115.0) (14.5-218.9) Average 266.9 180.7 189.1 207.5 (121.3) (82.1) (86.0) (94.3) White marlin Range 40.5-83.5 31.0-86.0 42.0-80.0 31.0-86.0 (18.4-38.0) (14.1-39.1) (19.1-36.4) (14.1-39.1) Average 56.0 $4.9 52.9 54.8 (25.5) (25.0) (24.0) (24.9) Sailfish Range 30.5-43.0 5.5-67.0 11.0-50.0 5.5-67.0 (13.9-19.5) (2.5-30.5) (5.0-22.7) — (2.5-30.5) Average 36.8 37.9 38.1 37.6 (16.7) (17.2) (17.3) (17.1) HSI3 4 3SIVY OL SYNOH KR Ls ° 3 - = a 8 re) © © S 8 [ ’ I Ts > lagen T rm ete goes KW J AAAS Ea a E oO <6 = S ¢p) 2 & <6 a a — 2 — 5 D = Ww ” (S) SEG G3 ec KW WOmy FG § s a mw i Ry i ey WWE en ae: a eae pie Shere ae Oo SOE ° ° ° ° ° ° ° ° 2 s 2 3° ° rs) ° o 3° = = ° ro} n = = ° ° ° ° ° fo) ro) ° ° fo) fo} YNOH Y3d G3SIVH HSI3 JO Y3SWNN 276 JULY AUGUST SEPTEMBER OCTOBER JUNE Figure 3.—Relative abundance of billfishes by weekly periods for South Pass and northwest Florida, 1971. etre eal aT 5.0 NUMBER OF FISH RAISED PER HOUR SOUTH PASS 10.0 20.0 Z ri Ww Co a x 50S a (=B8LUE MARLIN a CJ= WHITE MARLIN fi FE)= SAILFISH 6:7. S Er 10.0 20.0 oo TIME OF DAY Figure 4.—Relative abundance of billfishes by time of day for South Pass and northwest Florida, 1971. RELATIVE ABUNDANCE BY TEN-MINUTE SQUARES To determine the relative abundance of billfishes by ten-minute squares, the data were analyzed by calculating the number of fish raised per hour of fishing within each square during biweekly periods. For South Pass, the biweekly periods were begun Table 8.—Sex ratios of billfishes caught off South Pass, 1967-71, and off northwest Florida, 1971 (no. of males versus no. of females in parentheses). NW Area South Pass Florida Year 1967 1968 1969 1970 1971 1971 Blue marlin NES ye = IBGE STE. IBY} 1:3.1 (5:28) (6:46) (4:19) (2:16) (7:23) ~——(12:37) White marlin 12231-3291 6:2 eld ON: 4.0 1:4.3 (20:46) (15:59) (4:25) (4:16) (3:12) _ (28: 120) Sailfish HEPA) SRG SR atari yt 12225 (10:20) (5:18) (1:8) (8:11) (5:12) ~~ (63:159) on 26 May and were ended 28 September. Effort before and after this period was very low and sporadic. For northwest Florida, the biweekly periods were begun on 26 May and were ended on 9 November for the same reason. The data for all species combined for the two areas are illustrated in Figures 6 and 7. The data for .300 3.3 200}- Thee 150 =|87 100 7 el 4200 .000 125 ssa IS Ie Te 18 = 06 O7 OB O9 10 W TIME OF DAY NUMBER OF FISH RAISED PER HOUR l fe) °o HOURS TO RAISE | FISH Figure 5.—Relative abundance of billfishes by time of day, South Pass and northwest Florida combined, 1971. —'9 dns II'q [JB JO souepunqe sanrjay “ILO “ss¥d YInog ‘spoliod Ayyaamiq s0y sorenbs aynurw-ua} hq saysyy 6b£'0- 100°0= 669'0 - OSE'0 = ae AN# 41 02 Of Ov 8 NN -92 AVW 02 OF ee NN -6 NN OE 9°1Nt-E2 NAP ‘PonuyUoI—T/6T “Ss¥d YING “sporsod ATYeemIq Joy sasenbs aynurws-us} Aq seysiq [Te Jo souvpunge saje[ay—"9 o1n3Iy 002°0<= 669°0 - OS¢"0 6 ve" - 100°0= 0000 = 40° 180> 180° 279 062 Het 62 14 827 a ie Or TSIM GIT Noi bz. l21_Joz7 volt ,01 ! sae ieee ogffsrn aia |na jon 97 S1 Ob 0S of 8 oy Arcralnlpeys salaly 61 87 41 97 G1 bo 7 27 7 O:] ,0l 02 0€ Ov 0S ol ,01 Oe 21 9NV-b ONY 02 Kelsi € ONV-l2 1Nt ‘ponuljuo0d—]/6] ‘ssed YyINoS ‘sported ATyIamMIq OJ soreNbs 9ynurwW-us} Aq saysi[fiq [Je JO II 0£'6 10°0 17 890°7 BIULOFIES UIYINOS 0L61 t6'1 c$'0 86t OTE Te'0 9€7 99'P 1c'0 c9l => — — SLL (eifensny) sured) SOT 60 ITT — = — SO'l 60 901 OL'OI b0'°0 Ss raul oojndvoy £8°0 IT POL ar = = I8'l cs0 TE cS I $90 TBE £8¢ uepjezeyy LUI 840 1L6‘I = a a 70'S T1 0 pit asa | 990) LS9'l 61S°7 vimoyye| vleg br ol O10 077 = = = = rae = br ol O10 OCT L677 BIWIOFTV) UIYINOG 6961 ysy Aep 19[3ue yoe9 ysyy Aep s9jdue yore ysy Aep sojdue yoea ysy Avp s9[3ue yore) sAep RIV /skeq syed /skeq syed /skeq ee) /skeq syoegd Jajsuy [R101 ulpjBW YR | ysyyples ulpiew pods ‘aie Aq pure sarsads Aq [6] Pur ‘OL6I °696] SIVOA DY) OJ VILP JIOJJa puv YIVO—'T IQVL 293 15 14 13 12 MAZATLAN Il N fish = 1,597 ~ ie = =z ees) ACAPULCO = os N_ fish = 237 > oe BAJA CALIFORNIA x N fish= 7,132 2 06 [ mecooomsmy. om xe alalalal | | @ecccccena | [jel lal TT Jalafafafal yo SOOOOOOONAC as T | lel jel | jalalalajal | [| lel [| rvyvvy lial ts iam lata testa eo al 2) EAU EN ae EA sh De jVeilealea ea bE \ eal Figure 14.—Dominant species of billfish only in the eastern Pacific by quarters, averaged for the years 1956-1970, by 5-degree areas. a. First quarter. b. Second quarter. c. Third quarter. d. Fourth quarter. 324 10°S, blue marlin are generally the dominant species of billfish. Their eastward extension into the east- erm Pacific reaches to about long. 105°W during the first quarter, decreasing to about long 110°W during the second quarter and to long. 120°W by the end of the third quarter. During the fourth quarter, blue marlin appear to become dominant again in a more easterly direction. They are never the dominant species near shore in the eastern Pacific. When compared with tuna, bigeye generally replace the blue marlin as the dominant species in this offshore area. In the intervening area, which is by far the largest, striped marlin are generally the dominant species, although shortbill spearfish occasionally are dominant. Striped marlin therefore appear to separate the inshore sailfish stock from the offshore blue marlin stock. When compared with tuna, striped marlin remain as the dominant species north of about lat. 15°N, but in the central and lower latitudes are generally replaced as the dominant species by bigeye and albacore tuna. In the southeastern, inshore area, swordfish are dominant. From a small area off northern Peru in the first quarter, their dominance appears to extend in a southwesterly direction. By the third quarter they are the dominant species of billfish to as far south as lat. 40°S and west to long. 105°W. This area begins to contract to the northeast during the fourth quarter. When tuna are included with bill- fish, bigeye appear to replace swordfish as the dom- inant species. ; Trends in Relative Apparent Abundance Because of the wide distribution of fishes and the fact that they cannot be observed in the sea it is impossible to estimate their real abundance by counting them. In order to detect relative changes in the abundance of marine fishes, the catch per unit of effort exerted is used as an index of such abun- dance. For billfish the index of abundance used in this analysis is the catch by species per 1,000 hooks set. Two important factors can affect the use of catch per unit as an index of abundance. First it is influenced by changes in the availability of the fish themselves and changes in their vulnerability to capture. Secondly, competition of the fish for the hook can bias estimates of abundance in a multiple-species fishery such as the longline fishery. With respect to the first source of error, if one 325 examines a series of data sufficiently long, the var- iability in availability and vulnerability tends to bal- ance out. We have not attempted to correct for the latter source of error. Catch per effort by quarter, year, and area are discussed below for striped mar- lin, blue marlin, sailfish and swordfish. To facilitate the analysis of catch rates, Kume and Joseph (1969a) divided the eastern Pacific east of 130°W into areas based on the geographical ex- pansion of the fishery. These areas have been re- numbered for the present analysis and are shown in Figure 1. Striped Marlin The overall catch rate for striped marlin in the eastern Pacific trended upward from 1956 to about 1965; it decreased during the following 2 yr, but during 1968 increased to its highest level. During 1969 and 1970 it decreased to slightly below the 1966 and 1967 levels. In order to examine in more detail these trends in the abundance of striped marlin we have grouped data into areas in which effort has been consistently expended for an extended time period. We show trends in catch rates for three such areas (Fig. 15). The lower panel of Figure 15 shows the catch per thousand hooks for the older, equatorial marlin grounds which include areas 9, 11, and 12 of Figure 1. The fishery for striped marlin in this area de- veloped during 1958 and has continued since. Catch rates during the early years were low, less than 2 fish/1,000 hooks. These increased progressively until about 1965 when they reached a high of about 5.5 fish/1,000 hooks. Since then they have exhibited a downward trend to a level of about 2 fish/1,000 hooks during 1969-1970. A great deal of quarterly variability is evident but it does not appear to ex- hibit any consistent pattern. Though effort does vary among quarters, there again does not appear to be any consistent pattern; the same general levels of effort have been exerted during recent years. Catch rates for areas 3, 5, and 6, the northern inshore marlin grounds, are shown in the middle panel of Figure 15. The fishery for striped marlin in this region began during 1963. At that time hook rates were quite high, about 14 fish/1,000 hooks. During 1964-1965 they decreased to about 10.5 fish/1,000 hooks. This was followed by an increase to about 12 fish/1,000 hooks, and catch rate has remained at about that level. The magnitude of var- iability in the quarterly catch of striped marlin in AREAS 14,15, 16,17 18.0 AREAS 3,5,6 \\ FISH PER 1000 HOOKS fe) fo} AREAS 9,11, 12 1958 59 60 61 624F {63 64065, 1669 6768, 690770 Figure 15.—Quarterly hook rates expressed as number of fish per 1,000 hooks for striped marlin for three major fishing areas in the eastern Pacific Ocean. this area is great. In a single year quarterly rates have varied by as much as a factor of 15. This var- iability seems to follow a consistent pattern. Prior to 1969 the first quarter exhibited the lowest abun- dance while the third quarter exhibited the highest. During the last 2 yr, 1969 and 1970, the peak catch rate shifted to the fourth quarter. Areas 14, 15, 16, and 17 of Figure 1 are used to represent conditons on the southern striped marlin grounds. The fishery developed during 1962-1963 and since that time has supported a significant share of the longline catch of marlin from the eastern Pacific. Peak catch rates were experienced in this area during 1965 when about 5.5 fish/1,000 hooks were taken. The index of abundance has declined steadily since that time to the present level of about 1.8 fish/1,000 hooks. These data suggest that the apparent abundance of marlin on the equatorial and southern grounds has decreased to about one-third of its highest level. Apparent abundance on the northern grounds has remained nearly constant since 1965, perhaps in- creasing very slightly. When all areas in the eastern Pacific are pooled, the catch rate of striped marlin reflects no consistent increasing or decreasing trends since about 1965. The total catch of this species from the eastern Pacific increased, with increasing effort, to about 270,000 fish by 1964 (Fig. 6). It decreased to about 225,000 fish during 1965 and remained at that level during 1966 and 1967. In 1968 it increased sharply to an all-time high of about 337,000 fish but decreased thereafter to a level of about 180,000 fish by 1970. It is difficult to interpret these catch statistical data in terms of the effect that fishing may be having upon abundance and productivity because the striped marlin of the eastern Pacific most likely form part of a larger stock in waters to the west. In order to make such a meaningful stock assessment analysis for striped marlin, it would be necessary to examine the dynamics of the stocks over a much wider range of the fishery. Blue Marlin Blue marlin have been taken in the Japanese long- line fishery since it first began operating in the Pacific, east of long. 130°W, in 1956. Catches of this species are primarily centered in the area lying be- tween lat. 10°N and 10°S and west of about long. 100°W. To examine trends in apparent abundance, catch rates from areas 7, 10, 11, and 13 have been pooled and are shown by quarters in Figure 16. These areas were chosen because a time series of effort extending back to the early years of the fishery are available, and such data should provide a useful index of relative abundance. During the late 1950’s, catch rates for blue marlin varied around 3 fish/1,000 hooks. Up to about 1963, the fishery was very seasonal; the first quarter showed the highest abundance, reaching 5 ~ fish/1,000 hooks at times, and the third quarter — showed the lowest abundance dropping to nearly 1 _ fish/1,000 hooks at times. BLUE MARLIN FISH PER 1000 HOOKS o 6 8 1963 64 65 66 67 68 69 70 YEAR Figure 16.—Quarterly hook rate of blue marlin expressed as catch in numbers per 1,000 hooks for areas 7, 10, 11, and 13 combined. Abundance began to decline in about 1960 and continued to do so until 1964-1965 when it reached about 0.8 fish/1,000 hooks. By 1966, abundance had dropped to about 0.5 fish/1,000 hooks and has fluc- tuated about that level since. Since about 1963 the fishery has not exhibited the marked seasonal pattern which it had prior to that time. An examination of the catch statistics in terms of numbers of blue marlin (Fig. 6) shows the catch increasing to approximately 75,000 in 1963 in pro- portion to an increasing effort. By 1966, catches decreased to about 22,000 fish and have continued to fluctuate about that level. From the earlier analysis (p. 317-318) it seems likely that blue marlin of the eastern Pacific repre- sent the eastern portion of a much larger popula- tion whose center lies west of long. 130°W. There- fore it would not be valid to attempt to explain catch- es and catch rates in the eastern Pacific in terms of effort generated in the eastern Pacific only. SAILFISH AND SHORTBILL SPEARFISH AREA 6 20) 1962 70 AREAS 5,6 &9 FISH PER 1000 HOOKS 1962 63 64 65 66 YEAR 67 68 69 70 Figure 17.—Quarterly hook rate of sailfish expressed as number of fish per 1,000 hooks. Upper panel area 6, lower panel areas 5, 6, and 9 pooled. 327 Black Marlin Catches of black marlin are so low in the eastern Pacific that it is of little value to analyze indices of abundance for this species. Catches increased from about 500 fish in 1956-1958 to about 4,000 fish in 1963 (Fig. 6). Since that time, catches have fluc- tuated around 4,000 fish, the highest being 4,200 fish in 1969. Sailfish It has been mentioned previously that sailfish and shortbill spearfish are not differentiated in the catch statistics of the Japanese longline fishery. Data are available, however, from selected cruises which can be utilized to show the relative distribution of the two species (Fig. 12). It can be noted from Fig- ure 12 and Figure 1 that in areas 5, 6, and 9, short- bill spearfish are not taken, only sailfish. Therefore areas 5, 6, and 9 can be used to represent changes in the indices of abundance. In fact, of the total catch of sailfish and shortbill spearfish, about 80% is comprised of sailfish from areas 5, 6, and 9. In Figure 17, the catch of sailfish per 1,000 hooks is shown in two groupings. In the lower panel, quar- terly catch rates are pooled for areas 5, 6, and 9, where most of the sailfish from the eastern Pacific are caught. In the upper panel, catch rates for area 6, the center of highest sailfish abundance, are shown separately. In the pooled area substantial effort was not gen- erated on the sailfish grounds until about 1964. By the first quarter of 1965 the catch rate was at the highest observed level, about 83 fish/1,000 hooks. The annual average abundance for 1965 was also the highest observed for the series:‘of years shown, about 32 fish/1,000 hooks. This decreased to about 20 fish/1,000 hooks during 1966-1968, and during 1969 and 1970 dropped to about 11 fish/1,000 hooks. This latter is about one-third the highest value at the outset of the fishery. The trends in apparent abundance of sailfish in area 6 (upper panel, Figure 17) are similar to the trends for the pooled areas; however, the decline in abundance in recent years has not been as great in area 6. When the fishery first developed on a sub- stantial scale in area 6, the annual catch rate was about 95 fish/1,000 hooks. This decreased rapidly until by 1967 it was about 58 fish/1,000 hooks. Since 1968 it has fluctuated around 53 fish/1,000 hooks. The total catch in numbers of sailfish and short- bill spearfish combined is shown in Figure 6. The catch increased rapidly from 1962 to 1965 when it reached a peak of nearly 425,000 fish. It has fluc- tuated greatly since then but has shown a general decline. Because these catch figures represent two species and are for the entire eastern Pacific they might mask any significant trends in catches of sail- fish on the primary grounds. Therefore we have computed sailfish catches for areas 5, 6, and 9 com- bined, and for area 6 separately. The following table shows catches in thousands of fish: Area 1964 1965 1966 1967 1968 1969 1970 6 28.6 329.9 173.6 131.3 208.9 ouT, 100.5 5+6+9 53.1 366.0 199.7 245.4 359.7 149.8 210.1 Catches from the pooled areas (5, 6, and 9) shown in the table seem to follow rather closely the trend in catches for the entire eastern Pacific. However it appears that in area 6 catches have declined rather sharply. For example the 1970 catch for area 6 is less than a third of what it was in 1965, whereas the 1970 catch for areas 5, 6, and 9 combined is about two-thirds of the 1965 catch from the same areas. 400 - 65 68 300 - nw a z | 67 = o 3 70 = 200 + 2 66 aS 69 f= 4 oO 100 F | ie) ii 4 it 4 1 —_ 1 1 1 J 65 30 - 67 Zoi wy 68 ° Oo 20-F Tr 8 66 70 ° 15 ie « w 2 10F 3 69 hs