NOAATRNMFSSSRF-675 A UNITED STATES DEPAPTMENT OP COMMERCE PUBLiCATION NOAA Technical Report NMFSSSRF' 675 V T U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Marine Fisheries Service Marine Biological Laboratory LIBRARY OCT 14 1992 Woods Hole, Mass. 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 industr.- 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 fisher>' 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 not«d) from D83. Technical Information Division. Environmental Science Information Center, NOAA. Washington, D.C. 20235. Recent SSRF's are: 619. Macrozooplankton and small nekton in the coastal waters off Vancouver Island (Canada) and Washington, spring and fall of 1963. By Donald S. Day, January 1971, iii + 94 pp., 19 figs., 13 tables. 635. A bibliography of the blackfln tuna, Thunnus atlanticus (Lesson). By Grant L. Beardsley and David C. Simmons. August 1971, 10 pp. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402. 620. The Trade Wind Zone Oceanography Pilot Study. Part IX: The sea-level wind field and wind stress values. .July 1963 to June 1965. By Gunter R. Seckel. June 1970, iii + 66 pp., 5 figs. 636. Oil pollution on Wake Island from the tanker R- C. Stoner. By Reginald M. Gooding. May 1971. iii + 12 pp.. 8 figs., 2 tables. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington. D.C. 20402. 621. Predation by sculpins on fall chinook salmon. Oncorhynchus tshawytscha. fry of hatchery origin. By Benjamin G. Patten. February 1971. iii + 14 pp., 6 figs.. 9 tables. 622. Number and lengths, by season, of fishes caught with an otter trawl near Woods Hole, Massachusetts. September 1961 to December 1962. By F. E. Lux and F. E. Nichy. February 1971. iii + 15 pp., 3 figs., 19 tables. 623. Apparent abundance, distribution, and migrations of albacore, Thunnus 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 bav scallop meats. By N. B. Webb and F. B. Thomas. April 1971. iii + II 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, Macrobrachtum, 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 Laborator>'. 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 -f 25 pp.. 14 figs., 21 tables. For sale by the Superintendent of Documents, U.S. Government Printing Of- fice. 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 hy 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.. 16 figs.. 6 tables, 10 appendix A tables. For sale by the Superintendent of Documents. U.S. Government Printing Office, Washington. D.C. 20402. 639. A hydrographicsurvey 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 industr>' and biology of the blue crab. CallinecCes sapidus. By Marlin E- Tagatz and Ann Bowman Hall. August 1971. 94 pp. For sale by the Superintendent of Documents. U.S. Government Printing Office, Washington. D.C. 20402. 641. Use of threadfin shad, Dorosoma petenense, as live bait during experimental pole- and-Iine fishing for skipjack tuna, Katsuwonus pelamis. in Hawaii. By Robert T. B. Iversen. .August 1971, iii -t- 10 pp., 3 figs., 7 tables. 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 decline. By Kenneth A. Henry. August 1971, v ■*- 32 pp., 40 figs., 5 appendix figs.. 3 tables, 2 appendix tables. For sale by the Superintendent of Documents, U.S. Government Printing Office. Washington, D.C. 20402. 643. Surface winds of the southeastern tropical .-Vtlantic Ocean. By John M. Steignerand Merton C'. Ingham. October 1971. iii + 20 pp., 17 figs. For sale by the Superintendent of Documents. U.S. Government Printing Office. Washington. D.C. 20402. 630. Blue crab meat. I. Preser\'ation by freezing. July 1971. iii + 13 pp., 5 figs., 2 tables. II- Effect of chemical treatments on acceptability. By Jurgen H. Strasser. JeanS. 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 U table. For sale by the Superintendent of Documents. U.S. Government Printing Office. Washington. D.C. 20402. 633. Blueing of processed crab meat. U. Identification of some factors involved in the blue discoloration of canned crab meat Callinectes sapidus. By Meivin E. Waters. May 1971. iii + 7 pp.. 1 fig.. 3 tables. 634. Age composition, weight, length, and sex of herring, Clupea patlasii. used for reduc- tion in Alaska. 1929-66. By Gerald M. Reid. July 1971, iii + 25 pp.. 4 figs.. 18 Ubles. 644. Inhibition of flesh browning and skin color fading in frozen fillets of yelloweye snapper (Lutzanwi uivanus). By Harold C. Thompson. Jr., and Mary H. Thompson. Februarv' 1972, iii -♦• 6 pp., 3 tables. For sale by the Superintendent of Documents. U.S. Government Printing Office, Washington. D.C. 20402. 645. Traveling screen for removal of debris from rivers. By Daniel W. Bates, Ernest W. Murphey. and Martin G. Beam. October 1971. iii ■*- 6 pp., 6 figs.. 1 table. For sale by the Superintendent of Documents. U.S. Government Printing Office. Washington, D.C. 20402. 646. Dissolved nitrogen concentrations in the Columbia and Snake Rivers in 1970 and their effect on chinook salmon and steelhead trout. By Wesley J. Ebel. August 1971, iii + 7 pp., 2 figs., 6 tables. For sale by the Superintendent of Documents, U.S. Government Printing Office. Washington, D.C. 20402. 647. Revised annotated list of parasites from sea mammals caught oH'the west coast of North America. By L. Margolis and M. D. Dailey. March 1972, iii + 23 pp. For sale by the Superintendent of Documents. U.S. Government Printing Office, Washington, D.C. 20402. Continued on inside back cover. ,^0 ftTMOSp^^ Nonn '^ME/v/t of U.S. DEPARTMENT OF COMMERCE Frederick B. Dent, Secretary NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION Robert M. White, Administrator NATIONAL MARINE FISHERIES SERVICE 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) iVlarine Biological Laboratory LIBRARY OCT 14 1992 Woods Hole, Mass. Seattle, Wa July 1974 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 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 Page UEYANAGI, SHOJI. A review of the world commercial fisheries for billfishes 1 DE SYLVA, DONALD P. A review of the world sport fishery for billfishes (Istiophoridae and Xiphiidae) 12 CONTRIBUTED PAPERS Section 1. Species Identification. FIERSTINE, HARRY L. The paleontology of billfish — The state of the art 34 NAKAMURA, IZUMI. Some aspects of the systematics and distribution of billfishes . . 45 ROBINS, C. RICHARD. The validity and status of the roundscale spearfish, Tetrapturus georgei 54 RICHARDS, WILLIAM J. Evaluation of identification methods for young billfishes ... 62 UEYANAGI, SHOJI. On an additional diagnostic character for the identification of bill- fish larvae with some notes on the variations in pigmentation 73 DE SYLVA, DONALD P., and SHOJI UEYANAGI. Comparative development of At- lantic and Mediterranean billfishes (Istiophoridae) 79 Section 2. Life History. 80 DE SYLVA, DONALD P. Life history of the Atlantic blue marlin, Makaira nigricans, with special reference to Jamaican waters 80 JOLLEY, JOHN W., JR. On the biology of Florida east coast Atlantic sailfish (/5//op/2on<5 platypterus) 81 ELDRIDGE, MAXWELL B., and PAUL G. WARES. Some biological observations of billfishes taken in the eastern Pacific Ocean, 1967-1970 89 MATHER, CHARLES O. Scientific billfish investigation: present and future; Australia, New Zealand, Africa 102 BECKETT, JAMES S. Biology of swordfish, Xiphias gladius L., in the Northwest Atlan- tic Ocean 103 WARES, PAUL G., and GARY T. SAKAGAWA. Some morphometries of billfishes from the Eastern Pacific Ocean 107 LENARZ, WILLIAM H., and EUGENE L. NAKAMURA. Analysis of length and weight data on three species of billfish from the Western Atlantic Ocean 121 SKILLMAN, ROBERT A., and MARIAN Y. Y. YONG. Length-weight relationships for six species of billfishes in the Central Pacific Ocean 126 SCOTT, W. B., and S. N. TIBBO. Food and feeding habits of swordfish, {Xiphias gladius Linnaeus) in the Northwest Atlantic Ocean 138 UCHIYAMA. JAMES H.,and RICHARDS. SHOMURA. Maturation and fecundity of swordfish {Xiphias gladius) from Hawaiian waters 142 IVERSEN, ROBERT T. B., and RICHARD R. KELLEY. Occurrence, morphology, and parasitism of gastric ulcers in blue marlin. Makaira nigricans, and black marlin, Makaira indica, from Hawaii 149 BECKETT, JAMES S., and H. C. FREEMAN. Mercury in swordfish and other pelagic species from the Western Atlantic Ocean 154 SHOMURA, RICHARD S., and WILLIAM L. CRAIG. Mercury in several species of billfishes taken off Hawaii and southern California 160 III Section 3. Distribution. ROBINS, C. RICHARD. Summer concentration of white marlin, Tetrapturus albidus, west of the Strait of Gibraltar 164 PENRITH. MICHAEL J., and DAVID L. CRAM. The Cape of Good Hope: A hidden barrier to billfishes 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. Ill, DURBIN C. TABB, JOHN M. MASON, JR., and H. LAWRENCE CLARK. Results of sailfish tagging in the Western North Atlantic Ocean 194 MATHER, FRANK J. Ill, JOHN M. MASON, JR., and H. LAWRENCE CLARK. Migrations of white marlin and blue marlin in the Western North Atlantic Ocean — tagging results since May, 1970 211 SQUIRE, JAMES L., JR. Migration patterns of Istiophoridae in the Pacific Ocean as determined by cooperative tagging programs 226 MATSUMOTO, WALTER M., and THOMAS K. KAZAMA. Occurrence of young bill- fishes in the Central Pacific Ocean 238 MARKLE, GRETCHEN E. Distribution of larval swordfish in the Northwest Atlantic Ocean 252 NISHIKAWA, YASUO, and SHOJI UEYANAGI. The distribution of the larvae of swordfish, Xiphias gladius, in the Indian and Pacific Oceans 261 YUEN, HEENYS. H, ANDREW E. DIZON, and JAMES H. UCHIYAMA. Notes on the tracking of the Pacific blue marlin, Makaira nigricans 265 Section 4. Fisheries. NAKAMURA, EUGENE L., and LUIS R. RIVAS. An analysis of the sportfishery for billfishes in the Northeastern Gulf of Mexico during 1971 269 SQUIRE, JAMES L., JR. Angler catch rates of billfishes in the Pacific Ocean 290 TIBBO, S. N. , and A. SREEDHARAN. The Canadian swordfish fishery 296 YOSHIDA, HOWARD O. Landings of billfishes in the Hawaiian longline fishery 297 HANAMOTO, EUI. Fishery-oceanographic studies of striped marlin, Tetrapturus audax, in waters off Baja California. I. Fishing conditions in relation to the thermocline 302 JOSEPH, JAMES, WITOLD L. KLAWE, and CRAIG J. ORANGE. A review of the longline fishery for billfishes in the Eastern Pacific Ocean 309 HUANG, H. C. Billfish fishery of Taiwan 332 IV REVIEW PAPERS A Review Of The World Commercial Fisheries For Billfishes SHOJl UEYANAGI ABSTRACT This report gives a general "overview" of the commercial fisheries for bilirishes. The present world production of billfishes is approximately 100,000 tons 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 consumer nation of these fish. Although billfishes account for only about 18% of the longline catches, they are presently of consider- able importance, especially among the fishery products utilized in Japan. This report discusses the value and utilization of billfishes in Japan, and describes how billfishes have gained status as a quality fish, commanding prices comparable to the tunas. In addition, the expansion of the longline fishery is described, showing that by 1965 the fishery had covered the entire distributional range of the billfishes. Catch and effort data for billfishes indicate that I ) swordfish is the only species which has show n an increase in landings in recent years, 2) blue marlin landings have decreased in recent years in the South Pacific, Atlantic, and to a slightly lesser degree, also in the Indian Ocean, and 3) the catch of the striped marlin has fluctuated greatly from year to year. Billfishes^ have been known to man since ancient times. Bones of billfishes — fragments of vertebrae and spears of sailfish, striped marlin, and swordfish — have been found among relics discov- ered in a shoreside cave at the tip of the peninsula bordering Tokyo Bay (Kaneko et al., 1958). These remains date back to the Jomon Era, some 3,000 to 4,000 years ago. Since such ancient times billfishes have been taken in Japanese coastal waters, albeit in small numbers, by harpoon fishing. It was with the de- velopment of the tuna longline fishery that these fish have emerged as an important world resource of today's magnitude. The present world production of billfishes, ac- cording to FAO statistics (FAO, 1971), is approxi- mately 100,000 metric tons per year, of which more than 90% is taken by the tuna longline fishery. Japan produces about 70% of the world's catch of billfishes and is the principal consumer nation for these fish. 'Far Seas Fisheries Research Laboratory, Shimizu, Japan. -No distinction is made in this report between the difterent species which may exist in the various oceans, as for example between the Atlantic blue marlin and the Indo-Pacific blue marlin. Only the generally applied common names are used throughout this report. Japan's average annual total catch of billfishes during 1968-70 amounted to 69,000 tons (Ministry of Agriculture and Forestry, Japan, 1972). Combining the longline catches of tunas and billfishes, the bill- fish catch comprised 18% of the total landings (Fig- ure 1 ). The proportion contributed by billfishes is about the same as that of the albacore {Thunnus alalunga) and both fall below the catches of yellow- fin tunafT. alhacares) and bigeye tunafT. obesus). These statistics suggest that billfishes are only an incidental by-product of the longline fishery, and to a certain extent, this is true. Nevertheless, billfishes are presently of considerable importance among the fishery products utilized in Japan. Among the billfishes, the striped marlin and swordfish predominate, each accounting for approx- imately 30% of the total catch (Figure 2). Blue marlin and black marlin together make up 25% of the land- ings, and the sailfish, 14%. VALUE AND UTILIZATION OF BILLFISHES IN JAPAN Figure 3 shows the average annual prices for bill- fishes for the 10-year period from 1961 to 1970. Figure 1 . — Average species composition of Japanese tuna fishery catches 1968-70. Figure 2. — Species composition of billfish landings in the Japanese tuna fishery, 1968-70. These are prices at the Tokyo Fish Market where about one-third of ail billfishes in Japan are landed. Three classes are evident: the highest priced striped marlin, the intermediate priced blue marlin, black marlin, and swordfish, and the lowest priced sailfish 1961 62 63 64 65 66 67 68 69 70 Figure ?>. — The average prices of billfishes at the Tokyo fish market. 1961-70. and shortbill spearfish. Billfish prices have generally increased over the years, but the increases were much more rapid after 1966, particularly for striped marlin and, to a slightly lesser degree, for blue mar- lin, black marlin, and swordfish. The prices for tunas are not shown but for comparative purposes, bluefin tunafT". thynnns) and southern bluefin tunafT. mac- coyii) are even more expensive than the striped mar- lin: bigeye tuna are somewhere between the striped marlin and the intermediate priced group of bill- fishes, and yellowfin tuna and albacore are between the intermediate and lowest priced groups. In recent years the billfish prices have become comparable with those of tunas because of the way they have come to be used in Japan. Although the billfishes are not used in canning as are some of the tunas, their uses are very similar to the highly valued tunas: as sashimi,^ sushi, ^ fish steaks, and as ingredients for tisfi sausages and hams. Because they are taken along with the tunas in the longline fishery and are utilized in much the same way as the tunas, these fish are frequently referred to in Japan as the "kajiki-maguro" or "billfish tuna." The billfishes gained status as quality fish in Japan following the 1954 Bikini bomb test. After the test 'Thin slices of tuna, billfish or other seafood eaten raw. ^Ball of rice marinated in a weak solution of vinegar, salt and sugar; often topped by small amounts of seafood. the tunas were found to be contaminated with radioactivity. When this became widely known the market for tunas was seriously affected. In order to avoid a drastic drop in tuna prices, the processors discovered new uses for the fish, including their use in manufacturing tuna sausages and hams. These products gained wide popularity over the next de- cade. Along with tunas, the blue marlin and black marlin were also utilized in this manner. The price of blue marlin and black marlin increased steadily through 1965 when the production of fish sausage and ham reached its peak. The price then leveled off between 1965 and 1967, but began increasing again after 1967. The latter increase was related to new developments in the tuna longline fishery. Beginning around 1967, Japanese tuna longliners fishing for southern bluefin tuna were equipped with refrigeration facilities which permitted fish to be fro- zen rapidly to temperatures of -55°C or lower, and also with fishholds capable of holding fish at temper- atures below -40°C. Fish could then be brought back to Japan from distant grounds in excellent con- dition. Billfishes brought back under such refrigera- tion were acceptable as sashimi and fish steaks. This new use gained wide popularity and presently is the common form of utilization in Japan. The striped marlin is particularly valued as sashimi and, like the southern bluefin tuna, commands very high prices. In general, billfishes larger than about 30 kg are used as sashimi. One of the advantages of billfish flesh is that it does not undergo as much color change as that of tunas. It can thus withstand longer periods of transportation and possesses a longer market shelf-life than tuna. The principal ufilization of billfishes, by species, is as follows: Striped marlin — virtually all used as sashimi; remainder in sushi. Blue and black marlins — virtually all as sashimi. Swordfish — steak, sashimi. Sailfish — those over 30 kg as sashimi: others in sausages and hams. Shortbill spearfish — fillets for use as steak; broiled or baked. Of all the billfishes landed at the Tokyo Fish Mar- ket, roughly one-half are consumed in the city of Tokyo; the remainder is distributed throughout Japan from Hokkaido to Kyushu.^ information on value and utilization of billfishes was provided by Mr. Hiroyo Koamiof IheTsukiji Fish Market Co. Ltd., Tokyo. DEVELOPMENT OF THE LONGLINE FISHERY As described earlier, virtually all of the commer- cial catches of billfishes are made by the longline method; only a negligible amount of surface- swimming billfish is taken by the harpoon fishery. The longline gear seem most effective in capturing the deep-swimming billfishes. The regular longline operation involves a set of gear whose mainline extends over a distance of 25-75 km at the surface of the ocean. Branch lines with baited hooks, numbering about 2,000 per set, hang vertically from the mainline, which is suspended at the surface by float lines and buoys. The baited hooks usually hang at depths of 100-150 m. The gear is set very early in the morning and its retrieval, which begins around noon, takes many hours, with completion frequently well past midnight. There is a special type of "night longlining" which is aimed principally at catching swordfish. This is, as the name implies, an operation in which the gear is set at night. Compared to the typical tuna longline, the night longline gear is set to fish much shallower by the use of additional floats and shorter gear ele- ments. Another difference is in the use of squid as bait rather than the saury, Cololabis saira, which is preferred for regular longlining. Longlining has the advantage of not having to rely on live bait. This gives the fishery a great deal of mobility. The tuna longliners can roam the world's oceans, fishing distant waters in pursuit of the de- sired species offish. Another advantage is that there is a minimum amount of gear selectivity, in that small to large fish of various species can be taken by this method. The longline fishing grounds have rapidly ex- panded over the years. Although the longline fishery was aimed principally at the various species of tunas, with the expansion of the grounds, more and more billfishes came within range of the fishery. The fish- ing ground expansion is shown in Figures 4, 5, and 6. Pacific Ocean Before 1955 the fishery v. as centered in the central and western Pacific Ocean (Fig. 4), where it ex- ploited the striped marlin of the northwestern Pacific and the blue marlin in the equatorial region. This fishery also began to catch striped marlin of the southwestern Pacific and the black marlin in the Figure 4. — The expansion of Japanese iongiine fishing grounds in the Pacific Ocean shown at J-year intervals (from Kume, in press). Figure 5. — The expansion of Japanese Iongiine fishinj grounds in the Indian Ocean (adapted from Kikawa et ai. 1969). Coral Sea. In the next 5-year period, 1956-60, the fishing grounds expanded eastward along the equator to near the Central American coast, with yellowfin tuna and bigeye tuna as the principal species being taken. The fishery also extended the bigeye tuna fishing grounds in waters noilheast of lo-w Tir* ■ crE »rE ' Figure 6. — The expansion of Japanese Iongiine fishing grounds in the Atlantic Ocean. Hawaii and at this time began taking striped martin of the northeastern Pacific. Between 1961 and 1965, the fishing grounds moved farther eastward into the American coastal waters. There was also an expansion in the north- eastern and southern directions. This expansion re- sulted in complete coverage of the distribution of striped marlin in the Pacific Ocean. The blue marlin of tne southeastern Pacific, along lat. 20°S and be- tween long. 130° and 150°W also began to be taken. The expansion of grounds after 1965 was largely for southern bluefin tuna in the higher latitudes of the South Pacific. As for future developments in the Pacific, we may be able to look forward to further developments of the swordfish resources along the coasts of South America and Australia. Incdian Ocean The expansion of the Iongiine fishing grounds in the Indian Ocean is shown by 2-year intervals (Fig. 5). In 1952 the yellowfin tuna grounds around the Lesser Sunda Islands began to expand westward and by 1956 had reached the African coast. By 1958 the Indian Ocean to the north of lat. 20°S was virtually covered. Since then, the grounds have spread southward, with albacore in waters off Madagascar as the primary objective. In the eastern Indian Ocean the fishery spread southward in pursuit of the southern bluefin tuna, and by 1964, reached lat. 40°S. The distributional range of the several species of billfishes was completely covered at this time. Southerly movements since 1964 were related to southern bluefin tuna exclusively, and not to bill- fishes. Atlantic Ocean The longline fishery in the Atlantic Ocean began in 1956 (Fig. 6) in waters north of Brazil for yellowfin tuna. Within 2 or 3 years it expanded in equatorial waters to the African coast. Since 1958 the fishery has spread both to the north and south in pursuit of albacore, and by 1965, had covered the area between lat. 45°N and 45°S. It then became continuous with the Indian Ocean grounds by moving around the southern tip of Africa. In the Atlantic, as in the Pacific and Indian Oceans, the fishing grounds cover the entire distributional range of the billfishes. In summary, it is seen that by 1965 virtually the entire distributional range of billfishes in the Pacific, Indian, and Atlantic Oceans had been covered by the Japanese longline fishery. In this regard, it can be said that with this coverage it has become possible to view the entire distributional picture of the billfishes through the activities of the longline vessels. THE DISTRIBUTION OF FISHING EFFORT AND THE CATCH OF BILLFISHES BY THE JAPANESE LONGLINE FISHERY6 The distribution of fishing effort of the Japanese longline fishery, in terms of numbers of hooks fished, has been plotted for 1970 by 5° quadrangles (Fig. 7). It is seen that fishing effort was particularly large in such areas as the northwestern Pacific, equatorial Pacific, and certain areas around lat. 40°S, especially south of Australia and around New Zealand. If fishing effort of the vessels from Taiwan and South Korea is included, it will show considera- "Datu source from Fisheries Agency (of Japan). 1972. ble effort in all oceans, particularly in the equatorial regions. Although the fishing effort is aimed principally at the tuna resources, there are areas where the effort is primarily for certain species of billfishes. Fishing effort for albacore. bigeye tuna, striped marlin and swordfish is concentrated in the north- western Pacific, that for bigeye tuna and striped marlin in the northeastern Pacific. In the central equatorial Pacific region effort is concentrated on yellowfin tuna and bigeye tuna as well as the blue marlin. Bigeye tuna and striped marlin are the prin- cipal species sought in the eastern equatorial region. In Mexican waters the effort is exclusively for striped marlin, and such exclusive fishing effort for billfish is seen nowhere else, except for sailfish in the coastal waters of Central America. In waters south of Australia fishing effort is con- centrated on the southern bluefin tuna. The 1970 catch of striped marlin (Fig. 8), and blue marlin (Fig. 9), in numbers, is shown by 5° quad- rangles. The striped marlin catches are relatively high in the central North Pacific and in the eastern Pacific. Other areas of good catches are in the wa- ters east of Australia, northwest of Australia, Bay of Bengal, and the Arabian Sea. There are also some good catches in the western North Pacific. As for the blue mariin (Fig. 9), the areas of good catches range from the western equatorial to the central equatorial Pacific Ocean. THE HARPOON FISHERY Although the harpoon fishery primarily seeks bill- fishes, the catch is very small compared to that made by the longline fishery. The catch of Japan's harpoon fishery in 1970 was approximately 3,000 tons of bill- fishes, or less than 5% of the total Japanese billfish landings. The vessels of the harpoon fishery are of wooden construction and range in size from about 10 to 40 tons. All catches made by these vessels are iced for delivery to the markets. Because of shorter trips, the fish are relatively fresh when landed and thus com- mand good prices at the market. The fish are suitable for use as sashimi. The harpoon fishery operates in coastal waters, and in Japan, takes largely the striped marlin and swordfish. The fishing grounds are located in waters off Sanriku (northeastern Honshu), around Izu Is- land, and in the East China Sea. The seasons are from July through October in the Sanriku grounds. uni, i(y H~,k. A (]. J-T \ ^) M LP ra/ £& .100-lW ^^ESSS --0 ^.SjoSoooo"— P,^ "* 'i^— •200 ^oooooooo.„ooo?f • \\ TV, n^ ,^?:oooo...ooooo..oo....ooooH .J^o a^oooooooooo f ■ \ id^\ i'^ 'JSo.oo.ooooooooooooSocooooool^^&iogS'oooo ooooo J « ^^^ o o '\-[- '='-WJ, ooB,o»»oo«««««i»«»«o»ooo o ooooa^ ilola £^ooooo»ooA |C .. " : Mj, -. D_^r "«*= o.oo««t«.l.o... »«»««. .ooootoo itj^^V^^^o o ooooook « ■-• u o o ., . . 1 . -. . o o . 6HaCL a Vl* ■'"■, o......o.ooo5 o'o o ooooL , 1 'c;^000„0|^,.0„OOOogg«-VK, 'o ■ , , o O O O . . • . O O V /o O OOol ' ^ooooooooooooooo m]^ ^^ooo' w o qooooooooooooooooo^ ooo oob "^ 3cqo6ooooooojooa*b Voobo oooooooooooooooooooo o^ o o o o o J ' ^ouooooooooooooid J.oooooooooooooooooooooooo ^0 ooo oooo _*ooooooooouooooooo o^^WTOv , ii«ooooooooooo OO o ooooo rfooooooo oo o o\ ..oooo„ o ooo.,.oo oo_^oooo3-oo oooo o oo J, .oooooooooo oo ^ • n o , , , M o n O O O O O O #• o n O O O • # O O O oW • O OO • O O O O O O O O O O • O O • • • Figure 7. — The estimated total fishing effort (number of hooks per unit area) in the Japanese longline fishery during 1970 (from Fisheries Agency of Japan, 1972). ZiiyY I , j^-_ K' Hjj -\i:\.^ 'ix U" Unit 10* fiih irt \u -M' : n 4 ■a T\F*^ - tA^^ • JO-*-' ^ /n B*"".""! 1 ■' i >,0 00 0000 rTN^j ■'fVt 1 In e,< j^f;oo.'. o„i ■; r.-^ " V ao.,ooooooo L^ J ,-aj:i • iO- CV?i'oo..o_jO_.^oo„,.,.,,.„oo\ j^oooooooo o' ?'^^. Y^ ^j^ ^OOO. . ooooo;,,. .., o,..,,u ^00-3^X^000000000 P \\ 5 >1 1^ ,^tooo 0.0.0,00. ...„...,. oooJii^\i.LXooooooooo y ^K^oo ^^ _/g'^'^--Ci,.'o~o ?~~ T^T^---- ' ' .' ' '.-oUTg»y *y;o o o-o-'ISo \ • oo., oooooooooo "f-^^J y ^ \Sr^^ ».p o'oo,,' I^JOOOOC^ oo O OOOf 1 J^OOOOQOOOOOOOO oToLJ^ [AI |^ ^° ^ ^ '^ ' ''l^i^.^.o\ ^OO 000|, • ^o'ooooooooooooo ti^I ^\|o oo^ rfo oo^o, -,-,-.0 00^0000 .^ ooo f •■ 05,50 oTJo ooooq^ >^.J«o ooo ojoooooo ooooo o n oV.o oo^y ■■ ^ /ooJo ^JoooooojooS J,.o|oooooooooooo oooooo o 7 f„ oo"o ooooo ..^ oooo^nio o f^jj'oooo ooo o ■« -o-o' '3 o 'i^J 1 J 1 °° ° " t M t"^ t 4""T . 1^ :»;>-..-- Figure 8. — The catch of striped marlin shown as numbers offish taken per unit area during 1970 (from Fisheries Agency of Japan. 1972). unit lo' (iih ^ V -s-.' "I'S Ql J" ^IV^ c ° ^' yt:x:::::::::::::::_' ^s f , ■• J-^ i •vo->.» -fT p:?o oooo =^-r>%) ■^Vi •ijO - ^j^^oooooo ooo \ oooooooooo ^.ift^ ■ - , ,.A ^? -:-.•- ;- -no o5\\io"^o.ooooooo / • ^ ^o"\ .-S^ ^ *« .' ■ ' * * ^,.oo^UWlo5S->oaoooooo j \:^f[olo.^^o^\^^^ ••••••••••..., , , ' U .'^-l o5sjo..^o^o-oooo3|^oi UJo . .iVj, u ,.,A,^ i">v^' ■ ' ••i« ••■•••• ••.••;••;•.!. o o ,.|. ,. utJ^g^T^^oo oooo Qov.^^ • /ijo 'o! o ...|>vl,.j ,. >.,,..'■.: •\'!J-^ liVjUI'J'jij -^ 1, .^.....,^-.. .,-,,, 0|.^.^HJi^v, \ ^Q Q OOO^ ' - * ofo o o o|o o o o o o o o'o o •U' ^^^|o <• o " * o ooool oooou o\--, oooo s Doo ob .a'g'QDotooo ooojo^ \oob o o o o o o c o o o o o o o «. o ^°° ~ 4 . / DOOO ■ ooooo (OOOOOOOOOOOOOOCOOUO jo O, •yo ooooo ;! oooooo ^-s, 2o„ooo ooo oo /ooo 1 \' .o oo *.-.ooo„l / Toooo 1 ' c i° ! ' ■ r ^ \ ( •"' p i :!,,:.! 1 1 '' 1 f 3 i i . '■ ■ Ml i-'I'i 1 H-'- ' t -Ji'Ji'Ji'j,U,'.,^i.ijJ.JJ,,U,lJ.J.^JJ.J.Lii.lJJ,LUJ,J.iJJ,JJ,JJ.JJ,.LUJJ.LlLi.LlUJJJi.'j.'..L^ ' '.J Lh Figure 9. — The catch of blue marlin shown as numbers offish taken per unit area during 1970 (from Fisheries Agency of Japan, 1972). 6 February through April off Izu Island, and from December to February in the East China Sea. Fish- ing conditions seem to be greatly affected by the position of the Kuroshio Current in coastal waters. RECENT STATUS OF BILLFISH PRODUCTION The average annual world catch of billfishes dur- ing 1968-70 amounted to approximately 103,000 tons (FAO, 1971). Of this total, swordfish comprised roughly 30%, striped marlin 25%, and blue and black marlins, combined, 25% (Fig. 10). BLUE & BLACK MARLIN SWORDFISH STRIPED MARLIN 1 1.0 WHITE MARLIN SAILFISH Figure 10. — Average percentage composition of world billfish catch, by species and by ocean, 1968-70. (I — Indian Ocean, P — Pacific Ocean, and A — Atlantic Ocean.) Japan produced approximately 55% (about 20,000 tons) of the total swordfish landings. Canada, Spain, Taiwan, Peru, and Italy each landed from 1,000 to 5,000 tons, and together with Japan accounted for more than 90% of the total catch. Excluding swordfish, the combined longline fisheries of Japan and Taiwan produced 94% of the total landings. The Japanese longline fishery alone was responsible for about 75% of the total world catch of these several species. The 1961-70 world catches of billfishes (all species combined) and of swordfish alone, are shown in Figure 1 1. With the expansion of the Japanese long- line fishing grounds, the total catch of billfishes in- creased from about 80,000 tons in 1961 to a peak of about 110,000 tons in 1964-65. This peak corres- ponded to the time when the fishery first covered the entire distributional range of the billfishes in the Pacific, Indian, and Atlantic Oceans. Total annual landings have slightly decreased 1M no- 100 «o S 80 1961 62 63 64 6S 66 67 68 69 70 Figure 11. — Annual world catch of billfishes (all species combined) and of swordfish (exclusively). 1961-70. since 1966, leveling off at around 100,000 to 105,000 tons. The swordfish, which makes up about 30% of the billfish catches, did not show a similar decrease after 1966. Rather, the catches tended to increase gradually. « 110 i *- 100 <" 60 480 Y° 160 Figure 12. — Annual world production and Japanese pro- duction of billfishes, 1961-70. In Figure 12 is shown Japan's catch of billfishes in relation to the world catch for the years 1961-70. Japan's catch began increasing in 1961 and reached a peak of 90,000 tons in 1965. Thereafter, the catches decreased yearly. This decrease was reflected in the trend in world catch. However, the decrease after 1967 in the Japanese catch was partially offset by an increase in landings of the longliners from Taiwan. The decrease in billfish landings by the Japanese vessels after 1967 was caused by a combination of reduced fishing effort in the Atlantic Ocean and the shifting of vessels into the Indian Ocean. Here a large part of the effort went to fishing southern 500 00*) 400- 5 300 200 100- PACIFIC Japanese longline fishery from 1962 to 1970 is shown in Figures 14, 15, and 16. 1962 Figure 13. — Annual fishing effort (number of hooks), by ocean, of the Japanese tuna longhne fishery, 1962-70. bluefin tuna in the higher latitudinal waters where billfishes are generally not found. The general leveling of the yield of billfishes fol- lowing the full coverage of the billfish distributional range by the longline fishery may be indicative, as in the case of the larger tunas, that some of these species are already being fished near the level of maximum sustainable yield. The relationship between catch and effort for the various species, based on Japanese longline data (Fisheries Agency of Japan, 1972), is next examined. The annual Japanese longline fishing effort in terms of numbers of hooks fished, for the years 1962-70, is shown in Figure 13. The total fishing effort for all oceans remained relatively stable at around 450 mil- lion hooks. This is the result of the Japanese fishery policy (in effect since 1963) of controlling fleet size in order to effect the rational utilization of the tuna resources and to maintain the tuna fishing industry on a sound foundation. Of the total 450 million hooks, roughly two-thirds of the effort, or 300 million hooks, was expended in the Pacific Ocean. This level of effort has remained relatively steady in the Pacific since 1964. The fishing effort was about the same in the Indian and Atlantic Oceans in 1963, but became slightly greater in the Atlantic in 1964-65. Since 1965 it has been considerably greater in the Indian Ocean. This shift in effort was due to a decrease in catch in the Atlantic Ocean and the subsequent movement of vessels into the southern bluefin tuna grounds of the Indian Ocean. Since 1968 there appeared to be a trend toward decreasing effort in the Indian Ocean and increasing effort in the Atlantic Ocean. The catch of billfishes, by species, by the (lO'l 200 100 500 400 300 200 100 300 200 100 SOO 400 300 200 100 9S(%«««««iaXK>'y-yySi^.^//y>».r>x<-x>'yy! 1962 63 64 65 66 67 68 69 70 Yeor Figure 14. — Annual catch, in numbers, of the four major billfish species in the Pacific Ocean. 1962-70 (from Kume, in press). EPR. SPR, and NPR denote eastern Pacific region (east of long. 1 30°W), South Pacific region (south of lat. 5°N, west of long. I30°W), respectively. Pacific Ocean The Pacific Ocean was subdivided into the follow- ing three regions (Fig. 14): the eastern Pacific region (east of long. 130°W), the North Pacific region (north of lat. 5°N, west of long. 130°W), and the South Pacific region (south of lat. 5°N, west of long. 130°W). Swordfish — ^The yearly catches of swordfish var- ied little, numbering about 200,000 per year on a Pacific-wide basis. However, taken by regions, a slight decrease was noted in the North Pacific re- gion, particularly after 1967. The catch in the eastern Pacific region increased after 1968 as a result of fishing in swordfish waters of Baja California and Ecuador. Striped marlin — Since 1963 the eastern Pacific re- gion has been the most productive of striped marlin fishing grounds, followed by the North Pacific re- gion. The catch in the North Pacific region has fluc- tuated from year to year and the 1970 catch in that region was particularly high. Blue inurlin — There has been a trend toward de- creased landings of blue marlin between 1963 and 1968. This trend was particularly marked in the South Pacific region. The increased catches in the North Pacific region in 1969 and 1970 were responsi- ble for reversing the downward trend. Sailfish — A negligible amount of shortbill spear- fish is included in the catch statistics for this cate- gory. Since 1965, the catches of sailfish have largely been made in the eastern Pacific region. The land- ings have been marked with considerable fluctua- tions from year to year. INDIAN OCEAN (10*) SjO'OO so 100 (10^) too X u. 100 o § 100 100 SWORDFISH STRIPED MARLIN BLUE MARLIN BLACK MARLIN SAILFISH Figure 15. — Annual total longline fishing effort (upper panel) and annual catch of billfishes (lower panel) from the Indian Ocean. 1962-70. In(dian Ocean The catch and effort data of billfishes from the Indian Ocean are shown in Figure 15. Swordfish — The slight increase in swordfish land- ings afler 1966 seems to reflect increased fishing effort. Striped marlin — The catches have varied consid- erably but were relatively high during 1965-67. Blue marlin — The catch of blue marlin tended to correspond with the amount of fishing effort ex- pended until about 1966. Beginning in 1967, the catch decreased in spite of increased fishing effort. Black marlin — The average annual catch was ap- proximately 36,000 fish. The catches remained rela- tively steady from year to year. Sailfish — The catch of sailfish varied considerably from year to year and resembled the catch trend for the striped marlin. Atlantic Ocean The catch and effort data of billfishes from the Atlantic Ocean are shown in Figure 16. Swordfish — The catches generally corresponded with fishing effort through 1968 but increased in 1969 ATLANTIC OCEAN (lOf*) et^ 100 00 o 100 (10^) 200 M 100 o Ul oo i 100 100 SWORDFISH WHITE MARLIN Q,CPUE BLUE MARLIN SAILFISH Figure 16. — Annual total longline fishing effort (upper panel) and annual catch of billfishes (lower panel) from the Atlantic Ocean, 1962-70. Catch per unit effort (CPUE) is shown for white marlin only. and 1970 in spite of relatively low effort. This in- crease was due to good catches made in higher latitudinal waters off the South American coast. White marlin — The catch of white marlin de- creased markedly after 1964. The average density, shown by the catch per unit effort, also decreased over the years. Blue marlin — The blue marlin showed a clearly downward trend since 1962. The average density of this species after 1965 fell to about one-fourth the level in 1962 (Ueyanagi et al., 1970). Sailfish — The catch statistics also included some longbill spearfish in this category. The yearly fluctu- ations in catches have generally corresponded to the Atlantic Ocean fishing effort. Some significant observations from the above are: I) swordfish is the only species which has shown an increase in the landings in recent years, 2) blue mar- lin landings have decreased annually in the South Pacific, Atlantic, and to a slightly lesser degree, also in the Indian Ocean, and 3) the catch of the striped marlin has fluctuated greatly from year to year. FUTURE PROBLEMS IN BILLFISH RESEARCH The above-mentioned views on the trends of catch for billfish species in relation to effort are based on total hooks and not on the standardized fishing ef- forts for the species. For this reason, the status of billfish resources might not be reflected accurately. Nevertheless, the catch trends suggest that some species or stocks of billfishes are being rather heav- ily fished. It is imperative that stock assessment studies be pursued vigorously on these species. Other than in the eastern Pacific striped marlin fishing grounds, the billfishes are being taken by the longline fishery incidental to the major tuna species. The fishery shifts according to the distribution of the tunas, and for this reason, it is difficult to compile adequate data on billfishes for analysis of the rela- tionship between catch and effort. Since the longline fisheries of Taiwan and Korea are becoming in- creasingly significant, it is necessary that catch and effort data from these countries be used along with Japanese data for reliable stock assessment studies. In other words, it is important to compile adequate data on catch and effort for these fish, and also, along with these studies, to clarify the population structure of the various species. At this point, we might emphasize the importance of studying the population structure of the striped marlin, not only because of its dominance in the commercial landings, but also because of its impor- tance in the sport fishery (FAO, 1972). Further- more, from the biological point of view, several characteristics encourage further study of this species: 1 . The large fluctuations in striped marlin landings in the Pacific and Indian Oceans are believed to be due to certain biological characteristics of the species. For example, from studies of the striped marlin in the northwestern Pacific it was found that the average density tended to undergo biennial fluc- tuations, probably caused by variations in recruit- ment. A detailed study of such fluctuations can be expected to contribute towards the understanding of the population structure of the species. 2. The distribution of the striped marlin in the Pacific takes on a horseshoe-shaped pattern, cir- cumscribing the tropical areas. This species, how- ever, is distributed both in the tropical and subtropi- cal waters of the Indian Ocean. Thus, while most species of tuna and billfishes are distributed in the same pattern in the major oceans, the striped marlin seems to be an exception. The spawning areas are centered in subtropical waters of both the North and South Pacific while in the Indian Ocean, spawning seems to be centered in tropical waters (Fig. 17). 3. The differences in the distribution of the adult striped marlin and in their spawning areas in the Pacific and Indian Oceans may be indicative of a process of speciation. This presents an interesting problem in relation to studies on the billfish phylogeny and hierarchy. For population identification, various approaches such as tagging, morphometries, genetics, and parasitology may be necessary. It is also important to consider different and new approaches to this problem. I discuss in greater detail in a separate paper at this symposium (Ueyanagi, 1974) the possi- bility that studies in larval morphology can contrib- ute towards population identification. Because of the importance of the tuna fishery, scientists have devoted their attention to the studies of tunas in the past 10 years. Consequently, research on billfishes is lagging considerably behind the tunas. This International Billfish Symposium, how- ever, may well be the turning point and we may be able to look forward to increased effort towards the study of billfishes. The billfishes, needless to say, are important both to the commercial and sport fisheries. We must ac- 10 Figure 17. — Larval distribution and fishing grounds for striped mariin 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. ACKNOWLEDGMENT 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 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. In 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. UEYANAGL 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., (3): 15-55. 11 REVIEW PAPERS A Review of the World Sport Fishery for Billfishes (Istiophoridae and Xiphiidae)^ DONALD P. DE SYLVA^ ABSTRACT Sport fishing is conducted for bilirishes (Istiophoridae and Xiphiidae) in nearly all warm oceans, primarily in tropica! and subtropical seas. In probable order of descending catch rate, the principal species caught by anglers are sailfish, white marlin, blue marlln, striped marlin, black marUn, 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 anghng 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 inelTiciency 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 Atmospheric Science. ^ Associate Professorof Marine Science. University of Miami. Rosenstiel School of Marine and Atmospheric Science, Miami, Fl. 33149. 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 12 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 catch a 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 bi'lfish 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. 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 II, 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 Lemer, 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- 13 cause it took more than mines, torpedoes, and gas rationing to deter a true billtlsh 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 $ 1 00 a day to be reasonably assured of at least seeini; 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 platypteriis*\ white marlin, ■* For the purposes of this discussion. I follow Morrow and Harbo (1%9) in recognizing a single, worldwide species. Simi- larly, for the purposes of this review, 1 concur with our earlier Tetraptiinis albidiis: blue marlin, Makaira nigri- cans; striped marlin, Tetraptiinis audax; black marlin, Makaira indica; swordfish, Xiphias gladiiis; and longbill spearfish, Tetraptiinis pfhie- geri (see Robins and de Sylva, 1961 and 1963, for a discussion of recent nomenclature). The shortbill spearfish, Tetraptiinis angtistirostris, 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, 20% pounds; 20 miles southwest of North Coronado Island, 31 August 1968, 4% pounds; 20 miles south of Pyramid Head, San Clemente Island, 28 August 1969, 45 pounds. The Mediterranean spearfish, Tet- raptiinis 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 afire 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 J. georgei has extensive mark- ings on the dorsal tin; 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. 14 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. 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 spoil fishing centers for the various species, as well as to those which are already known to be good for billfishing. DISTRIBUTION OF SPORT FISHING EFFORT FOR BILLFISH Billfish Species and their Distribution 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 is 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- 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 indi\ iduals have traversed great distances. They reach a weight of over 100 kg, and arc 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 l\)und onlv 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, 15 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 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 (sensn slrictii) 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 T. 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 is 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. 16 Figure I. — Principal areas of sport fishing for bilifishes . Middle Atlantic Bight. — This region from Mon- taui< to Hatteras, North CaroHna. 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 bilifishes 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 bilifishes 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 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 bilifishes 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 17 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 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); 18 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 Mantaand 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 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 fishingjust 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 shelfof 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 19 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; Ueyanagi etal., 1970), but their occurrence is rare. Kenyaand 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- em 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, 20 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 EUice 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 difficuh 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 (20-1- 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. 21 Royce (1957) and Strasburg (1970) have discussed the distribution and size composition of billfishes taken by longline vessels in Hawaiian 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-mcome 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 helpful 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 OH njNA TOWEB 3 TOWER OR TUNA TOWER 4 FITING BRIDCE 3 COCKPIT OR lOWERCONTROl STATION 6 OUTRIGGER 7 OUTRIGGER a FIGHTING CHAIR 9 TRANSOM DOOR 10 BOW RAILS 11 BAIT BOX I? LADDER Figure 2. — Schematic diagram of a Sportfisherman (from Rybovich, 1965). 22 the fish the impression that it has killed its prey. In any event, the biilfish 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 biilfish. 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 biilfish 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 biilfish 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-huU (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 ioran; 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 biilfish baits in the United States are the mullets (Miigil), possibly because of their availability. Bonefish (Alhula 23 spp.) are popular, as are balao, or ballyhoo {Hemiicunphus and relatives). mackerel (Scomberoinonis), barracudas (Sphyrciena). dol- phin (Coiyphaena), rainbow runner {Elagatis hipinniilatus). jacks (Caranx spp.), tunas and bonitos (Thiinnns, Katsiiwonus. Eiithyniiiis. Sardaj. 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 commeicial 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. 24 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 Grouncis 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- 25 feet 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 offish (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 tsiike 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 26 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 cunent 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 (NMFS) 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- 27 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, sauteed, 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 28 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 /ee/i 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 aesthefic 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 whv 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 win a tournament . While the competi- tive sport of winning is important, it perhaps should 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 offish 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 biUfishing 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- 29 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 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 (i.e., those with a potentially longer life span ahead of them) concomitant with genetic and morphometric studies of subpopulations. By studying catch rates fiom 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 30 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. 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 I4-16-0008-775/DI-14-16-0008-957, and the Maytag Chair of Ichthyology, University of Miami. The key words are cooperation and advice which will benefit all parties without damaging the billfish resources. A first step is to determine //'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. LITERATURE CITED CORDEIRA, A. 1958. Espadartes do Sesimbra. Pedidos a Edigoes •'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. 31 1973. Family Istiophoridae, pp. 477-481. In 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 atbidus. 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. 1%8. 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, 1956-1%5. SeaGrantTech. 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. In press. HOWARD. J. K.. and S. UEYANAGI. 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. 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. 57-4:12 p. MATHER, F. J., III. 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. II favoloso marlin blu nel mari italiani. Mondo Sommerso, 10(1 l):i. MORROW, J. E., and S. J. HARBO. 1969. A revision of the sailfish genus Istiophorus. 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. NANKAl 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.) OVCHINNIKOV, V. V. 1966. [Marlin — new object of a fishery). Ryb. Khoz. 1:11-12. [In Russian.] PENRITH. M. J., and M. L. WAPENAAR. 1%2. 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. 1%I. 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 helone. 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. 32 RYBOVICH, J. 1965. Sportfisherman [boat]. In 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. UEYANAGl, S., S. KIKAWA, M. UTO, and Y. 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.] 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. 1%9. The Japanese Atlantic long-line fishery, 1956-1963. Proc. Sympos. Oceanogr. Fish. Res. Trop. Atlantic — review paper and contribution, UNESCO/FAO, p. 317-347. 33 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 billflshes. 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: Lstiophoridae, Xiphiidae, and Xiphiorhynchidae. A new undescribed xiphiid from Mississippi shows that the billflsh lineages mast have diverged prior to the Eocene. Areas of research are suggested that will help place the paieontological 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 ine only ones to summarize the paieon- 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 paieontological and phylogenetic discussion on a firm foundation, I have summarized some of the major osteological features. In addition, 1 have pointed out some areas of research that will aid fu- ture paieontological 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 lstiophoridae (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. less ossified in the Xiphiidae than in the ls- 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 lstiophoridae. Tetniptiinis and Istiophonts have 12 -I- 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. 34 Figure 2. — Striped mariin (Tetrapturus audax) skull. A. Dorsal view. B. Lateral view. i/)/>0^ Figure 1. — Swordfish (A'/p/iia.j 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 Xiphi05 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. 35 ''"■ l5tiophoru5 Figure 4. — Caudal skeletons of billfish. (From Gregory and Conrad, 1937.) Tr The Blochiidae contains two distinct fossil forms, Blochiiis longirostris and what 1 call the "Cylin- dracanthits 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 5. — Two successive caudal vertebrae from a black marlin {Makaira indica) showing the transverse flanges (Tr) that project from each centrum. Figure 6. — A. Reconstruction of Paleorhynchus glarisianiis. B. Reconstruction of Blochius longirostris. (From Gregory and Conrad, 1 937; after Woodward, 1901.) The"Cylindracanthus group'' (Aglyptorhynchus, Congorhynchiis. Cylindracanthus, Glyptorhyn- chus, Heinirhabdorhynchus, etc.) are all known by small, cylindrical, elongate structures (Fig. 7) that are thought to be rostral fragments of a Blochius -\\ke 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 affmities avoids the responsibility of making a precise taxonomic decision, it emphasizes our lack of knowledge of its members. The Istiophoridae contains the living genera /*- 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, easier (1966) feh that these crania be- longed to a billfish, but he also noted the similarity to the extinct scombrid, Scomhrinus. The cranial fragments of Acestrus are quite small, only 50-60 mm 36 m # Figure 7.— Rostra of the "Cylliulracanthn.s group"" A, B. CyHiulrciciinthus rectus. C, D, E. Aglyptorhyiichns venablesi F. Aglypl(>rliyi}chiis siilcaiiis. (From Casier. 1966.) in length. It is possible that these small skulls belong to one of the small spearfishes. Three species of Brachyrhynchiis have been described from rostra found in the Eocene of Belgium and the Pliocene of Italy. Woodward (1901) thought that Brachyrhyn- chiis was probably identical with Istiophonis. Based upon the figures that I have seen, I agree that Brachyrhynchiis 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 (Istiophonis or Tetraptiirtis) 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 Tetraptiirns. Figure 8. — Diagrams of the occipital region of several scombroids and xiphioids. A. WethereUus. B. Scom- brinus. C. Acestriis sp. D. Acestrus ornatus. E. Xiphiorhynchiis. (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.) 37 I .*1.' ."i'".i".'JLi."'il..iM°l!ux,!'JnMi,'J,,,,i,,ML,i,,ul,,,,i,MJ,,,,i.,'i mI J 'J,,,, 1. -^_ Vt. r "■ i ,'**^ , 38 The Paleorhynchidae (Fig. 6) comprises five gen- era (Ert«/jA77/e'«M5, Homorhynchus, Hemirhynchus, Paleorhynchus, ana Pseudotetrapturus) that are found from the Eocene to the Oligocene of Europe. One species, Pseudotetrapturus luteus, reaches up to 4 m in length (Danil'chenko, 1960), although other species usually are no longer than 1 m in length. Their vertebral count varies from 45 to 60. Accord- ing to Danirchenko (1960), P. luteus resembles Te- trapturus in dimensions and body form and in the structure of the elongated snout, but it differs from Tetrcipturus 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 (Woodward, 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 ^ ' \.¥ [Ill|llli|lillhlll{lililllil|llll|llllllllllllll|lil tiii|iiii|ini|iiii{iiii|iiii|iiii|iiiiiiiii|iiii|iiii|uiii Figure 10. — Semidiagrammatic reconstruction of Xiphiorhynchus prise us. A. Dorsal view of skull. B. Lateral view of opercular region. (From Casier, 1966.) Figure 11. — Rostrum oi 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. 39 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. 1 1) 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 Xiphiorliynchus 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 asXiphias riipelensis and it is similar to the hypural plate of Xiphias gladius. Most references to fossil Xiphiidae refer to the "Cylindracantluis 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 a cross 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 CI Acestrus, Brachyrhynchus. Istiophorus, Makaira, Tet- rapturiis) FAMILY XIPHIORHYNCHIDAE (Xiphiorhxnchits) FAMILY XIPHIIDAEfA-Zp/j/Vw, and unde- scribed Eocene genus) XIPHIOIDEI INCERTAE SEDIS FAMILY PALEORHYNCHIDAE {En- niskillenus, Hemirhynchus. Homorhynchus, Paleorhynchus, Pseudotetruptiirus) FAMILY BLOCHIIDAE (Blochius, ? "Cylindracanthus group") Figure 12. — Two vertebrae of Xiphiorliynchus 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. 40 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. 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). Figure 13. — Two other examples offish 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 Brachyrhynchusl 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'l 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). 41 ^ 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 "Cylindmcanthus 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 theCylindracan- tliiis 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. I I t I I I I I M I I I i I I 1 1 I I I I I ( T 1 I I I M I I I I Figure 15. — Rostrum of Glyptorhynchus sp. from the Miocene of California. A. Lateral view. B. Ventral view showing two alveolar grooves. 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 buih 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. DANILCHENKO, P.G. 1%0. 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 SP. 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. Xiphiorhynchiis kimhhilocki. 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. 1%8. The suborders of perciform fishes. Proc. U.S. Natl. Mus. 124(36471:1-78. 1971. Functional morphology and classification of teleostean fishes. U. Hawaii Press. Honolulu. 208 p. GREENWOOD, PH.D. E. ROSEN, S.H. WEITZMAN. and G.S. MYERS. 1%6. 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 (A'/p/ii'ai) and the sailfish (Istiopliorus). Am. Mus. Novitates, 952:1-25. 43 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 speaifishesof Formo- san waters. Reports of the Taiwan Government-General Fishery E.\periment 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, 1.. T. IWAI, and K. MATSUBARA. 1968. A review of the sailfish, spearfish. marlinand 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. II. 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. 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, AS. 1966. Vertebrate paleontology. 3rd ed. Univ. Chicago Press, Chicago, 468 p. TIBBO, S.N., L.R. DAY, and W.F. DOUCET. 1961. The swordfish (.V/p/im.v ^laJiiis 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. 44 Some Aspects of the Systematics and Distribution of Billfishes IZUMI NAKAMURA' ABSTRACT Until recently the classification of billfishes (Xiphiidae and Istiophoridae) was confused. Recent worl^ers 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 1 1 species. Makaira mazara is considered distinct from M. nigricans because of consistent differences in the pattern of the lateral line system. Tetrapterus platyplerus 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 LaMonteand 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 re visional 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 1 1 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 fm (Xiphiidae, Xiphias) Swordfish, Xiphias gladius Linneaus, Figure 1 A 'Fisheries Research Station. Kyoto University, Kyoto 625, Japan. Maizuru, 45 o :: ^ fa C o 'o 'yj 3 ^ .ji c > „„ K c« C O Q <^ s: w V5 =§ s si u i . o U j: c/l >J c/) S .a *^ (U 1 trt c £ "5. CJ « •-^ 3 >> c r •a ^ 3 -^ 1) ■ o c 2 u a. a. 15 . E c:~X':: E G H •Y-~ — .^..-.^„.---. ,.7;« •■••\" .1- J.. Figure 4. — Variations with growth of the lateral line sys- tems of the Indo-Pacific blue marlin (A-G) and the Atlantic bluemarlin(H-J). Body length: A. 17.7 cm, B. 81.0 cm, C. 84.3 cm, D. 1 12.9 cm, E. 1 19.5 cm, F. ca. 185 cm, G. ca. 260 cm, H. ca. 140 cm, I. 188.0 cm. J. ca. 205 cm. 49 Figure 5. — Distribution of swordfish, Xiphias gladius, based on catcii 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. 50°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 cunent 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 coa ;tal 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 50 Figure 6.— Distribution of fishes of genus Isiiophonis based on catch data from Japanese longline fishery during 1 964-69. 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. Figure 7.— Distribution of fishes of genus Telraptunis 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. alhidus. 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 spearfish have been caught off the east coast of the United States and in the Central and South Atlantic Oceans (Fig. 7). Tetrapturus albidus This species is distributed in the tropical and 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 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. 52 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 DESYLVA, D.P. 1972. Check-list of the fishes of the North-East Atlantic and of the 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. 196.5. Distribution and relative abundance of Billfishes lls- tiophoridae) of the Pacific Ocean. Univ. Miami Inst. Mar. Sci.. Stud. Trop. Oceanogr. No. 2. 134p.. 38 maps in atlas. JORDAN, D.S., and B.W. EVERMANN. 1926. A review of the giant mackerel-like fishes, tunnies. 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 Istiophorus. 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, I., T. IWAI, and K. MATSUBARA. 1%8. A review of the 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 DP. DE SYLVA. 1960. Description and relationships of the longbiU spearfish Telrapturus belone. based on western North Atlantic specimens. Bull. Mar. Sci. Gulf Caribb. 10:383-413. 1%3. A new western Atlantic spearfish, Telrapturus pfleu- geri, with a redescription of the Mediterranean spearfish Telrapturus helone. 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 Wild!. Serv.. Fish. Bull. 57:497-554. UEYANAGI, 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, Istiophorus albicans, in the northern Gulf of Mexico, with notes on other G ulf Istiophorids. Texas A. & M. Univ.. Res. Found. Proj. 286D:1-41. 53 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 196 1 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 T. belone in Sicily and T. 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 authortraveled 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, Telrap-' turns 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 alhidus, 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 on a 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. TETRAPTURUS GEORGEI 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 T. belone by Valenciennes, in Cuvier and Valenciennes (1831), and that its body was "clothed with large scales ofa 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 T. 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 54 appear during the summer. The white mariin, T. albidus, is Hkely 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 mariin. (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 7". belone (Robins and de Sylva, 1%3, 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 T. belone and thus there is no solid basis forjudging 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 LciinontelUi before Robins and de Sylva (I960) returned it to Tetrap- tunis. If it is judged that T. f>eor^ei is most likely the white mariin, 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 T. idbidiis Poey for this important game and food fish. The roundscale spearfish as noted below occurs in the eastern Atlantic, not far from Madeira, as well as in the Mediterranean. No doubt it reaches Madeira and many, if not all, of the eastern North Atlantic records of T. 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) 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, Is- 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 mariin (Makaira nigricans) is rare in the eastern North Atlantic but does occur at Madeira. G.E. Maul, inaletter(24 February 1961)toJohn K. Howard, refers to istiophorids in excess of 1,000 lb. These could be nothing else but blue mariin. 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 7. 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. Anteriorlobe 55 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-I. 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-EAtl-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-EAtl-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-EAtl-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 T. belone and the reference in the key to T. belone in fact refers to T. pfluegeri. Table 1 contrasts the four Atlantic species of Tetrapturus. Ta.xonomic 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 ofits 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, 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 oi 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, neilher belone nor pfluegeri is barred. In istiophorids the pectoral fin usually is allomet- ric in growth, sometimes, as in pfluegeri and auda.x, 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 oi 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). 56 o c £3 o E c o U f- c to E o U X) « 5 E cx -a c Si 2 a i c ^ o (^ -J — u c C D. o 3 O Xi 6 m a "3j r*-t -o IS o E O ■5 c c i> rt !> ^ jr c a> rt ^ >> O aJ T3 Xi O u Xi . Ob c c ■§ X c OJ rtJ OJ C3 c/) c LI -o a a> c c 3 Id [>n c ^5t 4 3 cd o c o6 E -o c :d u Id J= J= O c c "Set X u c o QJ OJ OJ o QJ ^ o "« o s. t o 3 u "3 3 ■a c o — n o a s -J Si = C "O u. c*-. u o u £ c .-d 1 in [I . platypterus], < 1 in [M. nuiztirci], and = 1 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 [T . angtistirostris], [I. platypterus]. and [T. audax], and the short snout group with [M. mazura] and [M. indica]. In the former, the snout length ex- ceeds V.i of their body length, while in the latter, it does not. For the specific separation of the former group. Table [2] applies: [T. ani>ti.stirostris] is dis- tinguishable by black chromatophores on bran- chiostegal membrane, while [/. platypterus] is separated from [T . auda.\] by the difference of their head profile: Unlike [7". 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 at al. (1968) and Merrett (1971). First Dorsal Second Dorsal First Anal Second Anal Pectoral Pelvic Vertebrae Pre- Species Rays Rays Rays Rays Rays Rays caudal Caudal Total /. platypterus Atlantic 42-47 6-7 11-15 6-7 17-20 3 12 12 24 Pacific 42-48 6-7 12-15 6-7 17-20 3 12 12 24 T. betone 39-46 5-7 11-16 6-7 16-20 3 12 12 24 T. pfluegeri 44-50 6-7 13-17 6-7 17-21 3 12 12 24 T. a Ibid us 38-46 5-6 12-17 5-6 18-21 3 12 12 24 T. iiuiltix 37-42 5-7 13-18 5-6 18-23 3 12 12 24 T. angustirostris 47-51 6-7 12-15 6-7 18-19 3 12 12 24 M. nigricans 41-43 6-7 13-15 6-7 18-21 3 11 13 24 M. mazara 40-44 6 12-15 6-7 21-23 3 11 13 24 M. indica 37-42 6-7 12-14 6-7 19-20 3 11 13 24 X. gladius 38-49 4-5 12-16 3-4 17-19 10-11 15-16 26 65 of the location of snout in terms of the center of eyes. In [/. platyptenis], the center of eyes is above the tip of snout, while in [T. aiiclax]. they are on a nearly same level. "Separation of [M. indica] from [M. mazcira] 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. niazara. T . pjliiegeri will resemble T. angiistiros- tris, and T. albidiis 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 Telrupturus 1 stiophorus Tetraplurus Makaira Makaira characters angiistirosnis plalypienis audax niarara indica Profile of head Tip of snout is Same as T. Tip of snout Tip of snout is Same as M. lower in level angiislirostris and center of lower in level inazara than center of eye are on a than center of eye. nearly equal level. eye. Anterior edge Same as T. Same as T. Anterior edge Anterior edge of orbit does angiislirostris angiislirostris of orbit of orbit does not project projects not project forward. forward. forward. Presence or Present .■\bsent 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 7". Fins stand out along the lateral 1 angiislirostris angiislirostris angiislirostris from the lateral side of the bod> side of the body and can be at a right angle readily folded and cannot be against the side folded against of the body. the body without breaking the joint. 66 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). Species Tetraplurus Istiophoriis Telraplurus Makaira Makaira characters angustirostris platypterus audax mazara indica Number of first More than 48 dorsal fin rays 43-47* Less than 45 Less than 45 Less than 45 Shape of first Anterior-high Poterior-high Anterior-high Anterior-high Anterior-high dorsal fin type type type type type(presumed) Lateral line Single Single Single Complex-having Not single (?) branches (obscure)** *This range is estimated from a small number of specimens. **Lateral line pattern not yet ascertained. 67 making the measurement difficult to make witii 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 '/3. Vi. %, or Ys 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 Ramus of lower jaw Gular membrane Branchiostegal ray and membrane Chromatophore on tip of lower jaw Chromatophore on midline of gular membrane Chromatophore on branchi- ostegal membrane Figure I. — 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 '/i 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 % 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 7ti of the length on the right rami and along Vi 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 if they 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 68 200- 180- o • BLUE MARLIN 160- -~ UNKNOWN SPECrES - 140- X 5 z •^ :3 120- 5 ^X" o S '00- "■^o . • •^ "^^ o° • • i 80- °o^^„ • • • *• • S OD^O a ° 0^ 8 o -« 60- cP o "^ oo JS '/2 <'/2 up intermediate level below level above 1 9 3.3-20.2 9 9 9 3 6 7 2 2 2 5.9-11.5 -> 1 1 -> -> 3 6 4.7-10.0 6 6 -> 4 3 3 5 1 4 4 4.5- 7.6 4 4 T T 1 t 1 4 5 21 3.7-10.9 21 21 9 12 5 8 8 16 5 6 14 4.4-14.5 14 14 6 8 3 -y 9 12 1 1 7 9 2.8- 9.3 9 9 2 7 -> -) 5 7 2 8 8 5.3-11.3 8 8 3 5 3 T 3 5 2 1 Blue 13 3.7-20.8 ") 11 13 13 4 4 5 11 2 marlin when young may be expected. Now that we have the ability to rear pelagic fishes from the egg. a concentrated effort directed at billtlsh 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 swordflsh, Xiphias gladius Linnaeus, from the South Atlantic coast of the United States and the Gulf of Me.xico. Bull, Mar. Sci. Gulf Caribb. 4:183-243. ARNOLD, E.L., JR. 1955. Notes on the capture of young sailfish and swordfish in the Gulf of Mexico. Copeia 1955:150-151. BARTLETT. M.R.. and R.L. HAEDRICH. 1968. Neuston nets and South Atlantic larval blue marlin (Makaini iiif;ric(ins). Copeia 1968:469-474. BAUGHMAN, J.L. 1941. Notes on the sailfish, Isliophorus ainericanus (Lacepede) in the western Gulf of Me.xico. Copeia 1941:33-37. BEEBE, W. 1941. Eastern Pacific Expeditions of the New York Zoologi- cal Society. XXVII. A study of young sailfish {Isilopluirus). Zoologica (N.Y.) 26:209-227. CALDWELL, D.K. 1962. Post larvae of the blue marlin, Makaira nigricans, from off Jamaica. Los Ang. Cty. Mus.. Contrib. Sci., 11 p. CUVIER, G.. and A. VALENCIENNES. 1831. Histoire natural des poissons. Paris 8:505-507. DERANIYAGALA. PEP. 1936. Two xiphiiform fishes from Ceylon. Ceylon J. Sci., Ser. B, I9(3):21 1-218. 1952. A colored atlas of some vertebrates from Ceylon. Ceylon Natl. Mus. Publ. 1:106-107. DE SYLVA, DP. 1958. Juvenile blue marlin, Makaira uinpla (Poey), from Miami, Florida, and West End. Bahamas. Bull. Am. Mus. Nat. Hist. 114(5):412-415. 1963. Postlarva of the white marlin. Telrapturiis albidus, from the Florida Current off the Carolinas. Bull. Mar. Sci. Gulf Caribb. 13:123-132. ESCHMEYER, W.N., and H.R. BULLIS, JR. 1968. Four advanced larval specimens of the blue marlin, Makaira nigricans, from the western Atlantic Ocean. Copeia 1968:414-417. FLORIDA BOARD OF CONSERVATION. 1%8. Relentless sea relinquishes rarity to resourceful re- searchers. Fla. Conserv. News 3(111:5. FOWLER, H.W. 1928. The fishes of Oceania. Mem. Bemice P. Bishop Mus. 10, 540 p. GEHRINGER, J.W. 1956. Observations on the development of the Atlantic sail- fish Istiophorus americanus (Cuvier) with notes on an unidentified species of istiophorid. U.S. Fish Wildl. Serv., Fish. Bull. 57:139-171. 1970. Young of the Atlantic ^ax\fisYi,Istiophurus platypterus . Fish Bull., U.S. 68:177-189. GOODE. G.B. 1883. Materials for a history of the sword-fish. Rep. U.S. Comm. Fish. (1880). Part 8:289-394. GORBUNOVA, N.N. 1969a. Raiony razmnozheniia i pitanie Lichinok mech-ryby 70 [Xiphias gladius Linne (Pisces. Xiphiidae)]. [In Russ.]. Vopr. Ikhtiol. 9(56):474-488. 1969b. Breeding grounds and food of the larvae of the sword- fish [Xiphias gladius Linne (Pisces. Xiphilidae)]. Probl. Ichthyol. 9:375-387. GUNTHER. A. 1873-74. Erster ichthyologischer Beitrage nach Exemplaren ausdem Museum Godeffroy. [InGer.] J. Mus. Godeffroy. Hamburg 1(2): 169-173. 1880. An introduction to the study of fishes. Adam and Charles Black. Edinb., 720 p. HOWARD. J.K.. and S. UEYANAGI. 196.'5. Distribution and relative abundance of billfishes (/.s- liophoridae) of the Pacific Ocean. Stud. Trop. Oceanogr. (Miami) 2. 134 p., 38 maps in atlas. JONES, S. 1958. Notes on eggs, larvae and juveniles of fishes from Indian waters. \. Xiphias gladius Linnaeus. Indian J. Fish. 5:357-361. 1959. Notes on eggs, larvae and juveniles of fishes from Indian waters. II. Istiophonis gladius (Broussonet). In- dian J. Fish. 6:204-210. JONES. S., and M. KUMARAN. 1964. Eggs, larvae and juveniles of Indian scombroid fishes. Mar. Biol. Assoc. India. Proc. Symp. Scombroid Fish. Mandapam Camp. Part 1:343-378. LA MONTE. F.R. 1955. A review and revision of the marlins, genus Makaira. Bull. Am. Mus. Nat. Hist. 107:323-358. LA MONTE. F.. and D.E. MARCY. 1941. Swordfish, sailfish, marlin, and spearfish. Ichthyol. Contrib. Int. Game Fish Assoc. l(2):l-24. LAURS, R.M.. and R.N. NISHIMOTO. 1970. Fivejuvenile sa\\r\sh. I sliophorus platyplenis , from the eastern tropical Pacific. Copeia 1970:590-594. LO BIANCO. S. 1903. Le pesche abissali eseguite da F.A. Krupp col Yacht Puritan nelle adiacenze di Capri ed in altre localita del Mediterraneo. [In Ital.j Mitt. ausderZoologischen Station zu Neapel 16:109-279. 1909. Notizie biologiche riguardanti specialmente il periodo di matiruta sessuale degli animali del golfo di Napoli. [In Ital.] Mitt, aus der Zoologischen Station zu Neapel 19:513, 760, 761. LOWE, R.T. 1840. On new species of fishes from Madeira. Proc. Zool. Soc. Lond. 8:36-39. LUTKEN, C.F. 1880. Spoilia Atlantica. Bidrag til kundskab om formforan- dringer hos fiske under deres vaext og udvikling, saerligt hos nogle af Atlanter havets hojsjofiske. [In Dan., Fr. summ.] K.. Danske Vidensk. Selsk. Skr. 5 ser. 12:441-447. 592-593. English translation of the French summary pub- lished as: LiJtken.C.F. 1881. Spoilia Atlantica: Contribu- tions to the knowledge of the changes of form in fishes during their growth and development, especially in the pelagic fishes of the Atlantic. Ann. Mag. Nat. Hist. Ser. 5, 7:1-14, 107-123. English translation of the Danish in Goode (1883). MERRETT, N R. 1971. Aspects of the biology of billfish (Istiophoridae) from the equatorial western Indian Ocean. J. Zool. 163:351-395. MITO, S. 1966. Nihon Kaiyo Plankton Zukan — Dai 7 Kan — Gyoran — Chigyo. (Japanese Marine Plankton Picture Book — Volume 7 — Fish eggs — Larvae). [In Jap.] Soyosha, Tokyo, 75 p. 1%7. Some ecological notes on the planktonic fish larvae. [In Jap., Engl, abstr.] Inform. Bull. Planktol. Japan (141:33-49. MORROW, J. E. 1964. Marlins, sailfish and spearfish of the Indian Ocean. Mar. Biol. Assoc. India, Proc. Symp. Scombroid Fish. Mandapam Camp, Part 1:429-440. MORROW, J.E., and S.J. HARBO. 1969. A revision of the sailfish genus Istiophonis. Copeia 1969:34-44. NAJCAMURA, H. 1932. The ripe eggs of the sailfish, Istiophorus 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. 1942. Habits of fishes of the family Istiophoridae in For- mosan waters. [In Jap.] Suisan Gakkwai Ho 9:45-51. 1949. The tunas and their fisheries. (In Jap.. Engl, transla- tion by W.G. Van Campen) U.S. Fish Wildl. Serv., Spec. Sci. Rep. Fish. 82, 115 p. NAKAMURA, H., T. KAMIMURA. Y. YABUTA, A. SUDA, S. UEYANAGI, S. KIK.AWA, M. HONMA, M. YUKINAWA. and S. MORIKAWA. 1951. Notes on the life-history of the swordfish, Xiphias gladius Linnaeus. Jap. J. Ichthyol. 1:264-271. NAKAMURA, I. 1968. Juveniles of the striped marlin. Tetrapturus audax (Phillipi). Mem. Coll. Agric. Kyoto Univ. 94:17-29. NAKAMURA. I.. T. IWAI. and K. MATSUBARA. 1%8. A review of the sailfish. spearfish, marlin and sword- fish of the wodd. [In Jap] Misaki Mar. Biol. Inst., Kyoto Univ. Spec. Rep. (4): 1-95. NICHOLS. J.T. 1923. Two new fishes from the Pacific Ocean. Am. Mus. Novit. 94:1-3. PADOA. E. 1956. Monografia: Uova. larve e stadi giovanili di Teleos- tei. Divisione: Scombriformes (Famiglie Scombridae, Thunnidae, Gempylidae, Trichiuridae, Istiophoridae, Xiphiidae) (Eggs, larvae and juvenile stages of the Scombriformes (in part) of the Gulf of Naples). [In Ital.] Fauna Flora Golfo Napoli 38:471-521. [Translated by John P. 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 DP. DE SYLVA. 1%0. 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 71 Teliapturus helone. Bull. Mar. Sci. Gulf Caribb. 13:84-122. RUPPELL, M.E. 1835a. Memoire sur une nouvelle espece de poisson du genre Hisliophore. de la Mer Rouge. Trans. Zool. Soc. Lond. 2:71-74. plus 1 plate. 1835b. Memoire sur une nouvelle espece de poisson du genre Histiophore. de la Mar Rouge. Proc. Zool. Soc. Lond. 3:187. 1835c. Memoire sur une nouvelle espece de ixiisson du genre Hisliophore, de la Mer Rouge. L"Institut 4:290. SANZO. L. 1909. Uova e larve di Auxis bisus. Monitore Zool. Ital. 20:79-80. [In Ital.] (Translated by W.G. Van Campen: avail. Natl. Mar. Fish. Serv., Honolulu, 3 p.) 1910. Uovo e larva di pesce-soada iXiphias i;!udii -'^ a H.-l 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. ' Reference to trade names does not imply endorsement by the National Marine Fisheries Service, NOAA. ,MMIdl|nMIJI|nT]l^]l|TlTjTp[lfTJ 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 ju . Slides were stained with Papanicolaou Haematoxylin (Harris) and Eosine Y, and with another stain developed by the 83 histology laboratory. These slides are presently available for microscooic 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 1 m plank- ton nets (mesh size 602 jj. for body section and 295 M 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. Al- 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 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, v = 47.600 + 9.881.V, 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). E n E N: 132 y- 4 7.600 + 9.881" '0.903 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 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 d.f. squares square F Spine width 1 42,426.8363 42,426.8363 ■576.807 Residual 130 9,562.0936 73.5546 Total 131 51,988.9299 V = 47.600 + 9.881 .V S-h 0.169 % variation = 81.607 r = 0.903 ■ Sig. at P = 0.05. 84 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 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 Frequency II 15 III 21 IV 12 V 5 VI vn 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 17.0 0.5-39.5 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 34 32 h. 30 / \^ 28 / ^ 26 / 1 I 1 24 \ o-.-o Female N=230 \% 22 ' t \ * \ \ 20 t { \ % \ \ IB 1 \ ^ 16 1 1 1 \ \ 14 f f \ 12 r \ % 10 / * \ % 8 \ * 6 ^ '* \ ^> 4 2 : '-^'-y On Weight (kg) •.n Figure 8. — Percent frequency distribution of 412 male and female sailfish by weight. 85 72 h . . Male N- 177 69 o- — o Female N- 221 /°l / 1 66 0.^ O ' t 63 A / * -\ / • 60 1 1 ' V '. A 57 ' * ' ■ / \ 54 v/\'' '■ ''^ '/ ^ 51 -'X \ t^ 1 48 ' " -A r\ 11 v\ / N /o 45 \ / \ 42 W \ A 1 ' v 39 v \ 1 \ J 36 \ ^ \ / 33 ^ \ / 30 ^ LOG,„TRUNK LENGTH J J A S O N D J 19 70 Months M A M J J 197 1 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 coirelations 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 (/.05=3.121, d.f. 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 1 1.7 ' 1 ' I ' i ' r 1.8 1.9 2.0 2.1 ' i 2.2 ' 1 2.3 _ d" LOGj^WT 3.342 LOGj Tkt.-5.7e4 (N 182 ) y 1.6 - ? LOG WT: 2.9 50 LOGj|,TkL-4.941 ( N*230) y 1.4- 1.2- 1.0- aa- 0.6- 30 «''/ y / / QA- 02- 25 ^ / OX)- 20 tj if 15 / / // // iO 1.645 « o't»l"" i // ? WT= t.145 1 1 ff'TkL"" _5 *? " <;r70 80 90 100 no 120 i30 ^ 1 , 1 . 1 , 1 , 1 1 1 , 1 , 140 150 160 1 1 1 1 1 . 1 1 TRUNK LENGTH (cm) Figure 10. — Relationship of trunk length to weight for 412 Atlantic sailfish. press) noticed a similar condition in young king xms:.- kere\, Scomberomoruscavalla. 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, 12 to 1.4 mm in diameter, from ovaries 8.1 to 12.7% (.r= 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. 86 Table 4. — Results of fecundity studies for eight Atlantic sailfish ranging from 17.2 to 27.4 kg (38.0-62.5 lb). Total Ovary Body Ova/gram Est. Specimen wt' wt' wt' wt fecundity (kg) (kg) (%) VI-14' 18.1 2.3 12.7 467 819.412 VI-LV 17.2 2.0 11.6 555 750.000 Not recorded 28.4 ca2.4 8.5 457 1,075.321 VllI-1' 28.1 ca2.6 9.3 498 1.148,918 VII-14- 19.1 2.0 10.5 890 1,557,574 IX-8 28.4 ca2.3 8.1 616 1,297,850 V1II-.V 23.1 1.9 8.2 580 919.300 Vl-17' 22.2 2.3 10.4 462 891,270 'Fresh weights recorded during field examination. Initial observations from plankton collections con- firni 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 ofova 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 60 55 50 45 40 35 30 25 20 15 10 5 N-227 J J A S O N D 1970 M A M J J I 971 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 offish production in fresh waters, p. 159-181. Blackwell Sci Publ., Oxford. BEAUMARIAGE. D. S. In press. Age. growth and reproduction of king mackerel, Scomberomonis cavalUi. in Florida. Fla. Mar. Res. Publ. CHRISTENSEN, J. M. 1964. Burning of otoliths, a technique forage 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 amerkanus (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 offish 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, 87 1970. Gonad development in billfish (Istiophoridae)froni the Indian Ocean. J. Zool. 160:355-370. MOE. M. A., JR. 1969. Biology of the red grouper. Epinepheliis niorio ( 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 Me.xico 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. In Some problems for biological fishery survey and tech- niques for their solution, p. 151-178. A symposium held at 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, Xiphidael. Bull. Mar. Sci. Gulf Caribb. 6:18-27. VOSS, G. L. 1953. A contribution to the life history and biology of the sailfish. Isliophurus lunericaniis 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, NMFSTech. 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, morphometries, meristics, and gonad data were gathered on a total of 2,056 striped mariin, 821 sailfish, 61 blue marlin, and 1 black mariin. 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 mariin 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 mariin 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 1 1 to 29 million eggs for three striped mariin. It appears tnat striped mariin 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 mar\in(Tetrapturus aiidax) and sailfish ( I stiopliorus 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 mariin, 821 sailfish, 61 blue mariin (Makaira nigricans) and 1 black mariin (M . indica) were sampled. This paper is one of a series of publi- cations describing the results of these studies. Evans 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 u. S. A. A s \>- r-^ s \ \ ^ -t. ibof 'NOAA, National Marine Fisheries Service, Tiburon Fisheries Laboratory. Tiburon CA 94920. Figure 1. — Location of the three billfish sampling sites. 89 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- em 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 10- — JFMAMJJASOND 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). STRIPED MARLIN . - fAlMAS BAT MAIAItAN ■ - - - V _ - / - 1 • • ■ ■ . . 1 "~- — .-i Figure 3. — Catch per unit effort (number per boat-day) and fiercent 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 ancd Processing of Sannples 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 90 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 Vi 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 30x 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 OVA DIAMETER (mm) 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. SM \ — > V ::: 'z:. .101 • 10) ^ >. -^ -• \ \ \' \ OVA DIAMETER (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 biUfishes were published by Merrett (1970) and La Monte (1958). In our studies we found strong evidence ofgonadalassymetry (Table 1). For striped marlin, the left gonad averaged larger than 91 Table I. — 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 A' Striped Marlin Male 80 53.1 53.7 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 (GI) computed as Gl = (WIL^) ■ W 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, h = slope, a = y axis inter- cept.) /; /■ h (/ 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 O.OI 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 is 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 anJ 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 GI), however, they did collect a mature specimen in the 148-cm class. 93 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 Gl = 1.0 as the other criterion based on our data (Fig. 7 and 8) which show 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 — 1 r — 1 1 1 1 1 1 1 1 r T" QUARTER + 4- + tt + i- li lllllfl^ [[:j\\\:i \\\M'^ ~n — I — r — 1 — 1 — I — I — I — I — I — I — r — I — I — I — r~ •t + -" -^" ;;;:if LENGTH GROUPS (cm) LENGTH GROUPS Icm) 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. Figure 8. — Sailfish gonad indices versus eye-fork length groups presented in quarters of the year. Numbers of sailfish 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 1 50 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 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. 1 1). We found no indication of multiple spawn- ing. 94 "T 1 1 r W + ^ (121 101 QUARTER H . + ^ + Bii mo\ ari u» TTTT m D| isi oi LEHQTH ODOUP* (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. i'^ -1 1 r- aUARTER I . . \ ■ II) «_ I + tW l*« + LENGTH GROUPS (cn> "is 4b- Figure 10. — Sailfish ova diameters versus eye-fork length groups presented in quarters of the year. Numbers of sailfish 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. OVA DIAMETCfl (mm) 95 ovaries encountered in this study. The fecundity estimates (Table 3) ranged from 1 1.3 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 \m 2359 1.2 1.8 5.5 163 2359 0.9 2.4 7.0 176 3810 1.3 3.0 8.9 187 5760 1.3 5.1 Striped Marlin 4.42 180 2580 0.6 11.3 8.17 150 2760 0.6 17.2 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 antd 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 FEB MAR APfl MAY MP 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 STRIPED MARLIN - MAXIMUM • 95t»l CENTILE • • -i I * 1'— •» r ^ — > - . a g- it- h . JAN FEB MAR APR MAY JUN JUL 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. 96 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 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. Hand 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. MP OCT NOV OtC Figure 14. — Mean gonad index distribution and the number of sailfish sampled by month from Buena Vista and Mazatlan. 97 - 1 1 SAILFISH 1 1 I o* 9 1 1 1 1 ■ MAXIMUM *'95**' CENTILE 1.0 - a • - 0.5 - • ■ II 1 ■: • . o ^. . o I n 1 1 1 1 1 .... J . JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Figure 15. — Distribution of sailfish ma.ximum ova diameters and 95th centiles by month from Buena Vista and Mazatlan. B » Figure 16. — X-ray photos of preopercular bones of striped mariin from Buena Vista showing (A) cavities caused by Pliilichthys 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. 98 The major departures from the results found in the previous study were the low importance of an- chovies in San Diego striped martin and of squid in Buena Vista sailfish stomachs. Table 4. — Sample sizes and condition of billfish stomachs sampled during 1970. Blue Striped Marlin SD BV Maz Marlin Sailfish BV BV No. Stomachs Total 37 59 8 15 33 With Food Empty Regurgitated Total Vol. of Food (I) 20 37 4 16 5 1 1 17 3 7.35 8.25 0.97 8 -) s 1.86 22 -> 9 6.83 ACKNOWLEDGMENTS We are indebted to representatives of resorts and 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 Lie. Ricardo Garcia Soto, Director of the Departamento de Tourismo de Baja California Sur for making available the reported catch data of sportfishing re- 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, Hotel Palmilla, Hotel Cabo San Lucas and Hacienda Cabo San Lucas. Several fleets at Mazatlan kept records of catch and effort for us and special thanks are due Bill Heimpel for his efforts. 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 (9f Occurrence/'^f 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 cabaltus — 3.0/0.8 — — 2.0/0.6 Decapods — 3.0/0.2 — — — Decapteriis hypodus — 3.0/1.7 — — 2.0/4.4 Cephalopoda Hemicaranx sp. — 5.0/1.0 — — — Argomiiita sp. — — 50/6.2 — — Trachurus Squid 5.0/0.4 62/24 25/1.2 13/1.1 12/3.1 syinmetriciis 38/62 — — — — FISHES Unidentified sp. — 3.0/1.2 — — 8.2/1.0 Elasmobranchs 2.5/T — — — — Coryphaenidae — — — — 2.0/10 Clupeidae Scorpidae Eirumeus teres — 43/39 — — 18/24 Medialuna Sardinops sagax 5.0/3.1 — — — — culiforniensis 5.0/2.4 — — Opisthonema sp. — — — — 2.0/0.3 Chaetodontidae — — 75/12 — — Engraulidae Mugilidae EngraiiUs mordax 2.5/2.2 — — — — Mugil cephalus _ _ 25/79 — — 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 Eulhynnus linealus — 5.1/17 — 12/19 8.2/13 culiforniensis 2.5/16 — — — — Sarda chiliensis 2.5/0.8 — — — — Exocoetidae Scomber sp. — 3.0/2.1 — — 4.1/2.3 Cypsehinis Unidentified sp. — — — 25/39 — californicus 2.5/0.2 — — — — Balistidae Unidentified sp. — — — 13/0.4 — Batistes sp. — 3.0/0.1 — — 6.1/0.4 Fistularidae Tetraodontidae Fislutaria sp. — — — — 8.2/21 Sphoeroides sp. — 3.0/2.2 — — — Syngnathidae — — 25/0.4 — — Lagocephalus Echeneidae lagocephatus — 19/6.4 — — 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 1. n = 116 Engraulis n = 20 Trachurus mordax 60 62 symmetricus -> Trachurus A therinopsis symmelricus 27 16 catiforniensis 3. Cololabis Cololabis saira 5 8 suira Buena Vista n = 303 n = 37 1. Squid 49 39 Etrumeus teres ■> Elrumeus 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 ") Argonauta sp. 7 12 Chaetodon sp. 3. Batistes sp. 7 6 Argonauta sp. 4. Fistulariu sp. 5 SAILFISH Buena Vista n = 14 n=22 1. Squid 35 24 Etrumeus teres -> Etrumeus teres 29 21 Fistularia sp. 3. Fistularia sp. TT 14 Euthynnus lineatus 4. Naucrates ductor 7 13 A uxis ihazard BLUE MARLIN Buena Vista No Data n =8 1. 39 Scombrids (unidentified) 2. 36 Auxis ihazard 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, Katsuwonus 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 %me\t.Atherinop- 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. FishWildl. 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. Nankai Reg. 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 se.xual 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 MB. 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 IndianOcean. J. Zool. 163:351-395. MOSER. H.G. 1967. Seasonal histological changes in the gonads ofSebas- todes puucispinis. Ayres. an ovoviviparous teleost (Fam- ily Scorpaenidae). J. Morphol. 123:329-353. NAKAMURA, H. 1932. The ripe eggs of the sailfish, Istiophorus orientalis, (Temminck and Schlegel). [In Jap.] Zool. Mag. 44:244-245. 100 1940. On the spawning habits of sailfish. [In Jap.] Zool. Mag. 52:296-297. 1949. The tunas and their fisheries. Takeuchi Shobo, Tokyo, 1 18 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. 59:287-305. SCHAEFER, M.B.. and C.J. ORANGE. 1956. Studies on the sexual development and spawning of yellowfin tuna (Neolhunnus macropteriis) and skipjack (Kal.smvoniis pelamisl'm three areas of the eastern Pacific 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 iTelraplurus ciitdax) caught off San Diego, California. In Richard S. Shomura and Francis Williams (editors). Proceedings of the Imemational 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. 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-675. p. 226-237. SUDA. A., and MB. SCHAEFER. 1965. General review ofthe Japanese tuna long-line fishery in the eastern tropical Pacific Ocean 1956- 1%2. [In Span, and Engl.] Bull. Inter-Am. Trop. Tuna Comm. 9:307-462. UEYANAGI. 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 morphometries of eastern Pacific billfishes. In 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. In 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 hersecond 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 ofdeveloping 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. 101 Scientific Billfish Investigation: Present and Future Australia, New Zealand, Africa^ CHARLES O. MATHER2 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 billtish and better methods of catching billfish is discussed. U. 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. m. 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: ( I ) breeding of black martin 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 billiish in relation to sight, smell, and pain (Africa). ' 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., m 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 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 under90 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 Canada ' Fisheries Research Board of Canada, St. Andrews, Brunswick. Canada. New Figure 1. — Canadian commercial swordfish fishing areas. 103 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 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 v.'as 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 = I4089) 963 (N=7732) 200 300 Drosed Weight ( Pounds! ' ' I ' 400 "" t T ( ' I 1-" 900 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 lb (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, 104 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 1 10 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. ACKNOWLEDGMENTS 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 BECKETT. J. S. I%8. A harpoon adapter for tagging large free-swimming fish at the surface. J. Fish. Res. Board Can. 2.';: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. In Richard S. Shomura and Francis Williams Table 1. — Swordfish tag returns. Min. Size Released Size Recovery Size Months distance change date Area (lb) Date Area (lb) out miles (lb) 9/9/1964 Georges 90 est. 12/ 7/1966 Georges 188 est. 21 60 + 98 7/6/1966 Gulf Stream 70 est. 10/ 7/1969 Georges 156 37 128 + 86 3/7/1968 Georges 160 est. -3/ 9/1970 Stellwagon 212 26 178 + 52 27/7/ 1%8 Sable 400 est. 11/11/1969 Sable 400+ 16 7 27/7/1968 Sable 350 est. 2/10/1969 Sable 590 15 6 -1-240 29/7/1968 Browns 160 est. 4/10/1968 Browns 150 est. 3 28 - 10 13/7/1970 Georges 120 est. 20/ 9/1970 Georges 140 est. 1 59 + 20 13/7/1970 Georges 140 est. 14/ 9/1970 Georges n/a 5 n/a 13/7/1970 Georges 170 est. 19/ 7/1970 Georges 172 38 -u 2 13/7/1970 Georges L'iO est. 11/ 9/1970 Georges 185 ■y 83 + 35 13/7/1970 Georges 100 est. 13/10/1970 Georges 75 est. 3 92 - 25 13/7/1970 Georges 180 est. 27/ 7/1970 Georges 228 31 + 48 4/8/1968 Georges 225 est. 30/ 8/1970 Georges 234 24 30 + 9 105 (editors). Proceedings of the international Billfish International Billfish Symposium, Kailua-Kona, Hawaii, Symosium, Kailua-Kona, Hawaii, 9-12 August 1972, Part 9-12 August 1972, Part 2. Review and Contributed Papers. 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. In Richard S. Sho- 1943. Marine fishing in Newfoundland. Int. Game Fish mura and Francis Williams (editors). Proceedings of the Assoc. Yearb. 1943:65-66. 106 Some Morphometries 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 (Tetraplurui audax), sailfish (Istiophorus platyplerus) , 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 sex. 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 il\- tiophorus plalypterus) 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. 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 L The specimens examined were almost totally fish caught on one-day trips in small boats ranging from about 6 to 12 m in 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 107 Table 1. — Number of bkie 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 1969 — — — — 2 7— — — 5 — 14 1970 ________ 15 5 _ 20 Total _ _ _ _ 3 7 _ _ 15 10 _ 35 Mazatlan Female 1969 — — 4 6 in 2 — __ — _22 Sailfish Buena Vista Male 1967 ___ 2 — — — — ___ 2 1968 ____ 3 ______ 3 1969 ____ I 3___ 5_ 9 1970 ________ s 6 — 14 Total ___ 2 4 3__ 811 — 28 Female 1967 ___ 2 4______ 6 1968 — — 1 3 7 7 — — — — — 18 1969 — — — 10 I 9____ 6 26 1970 _________ 7 14 21 Total — _ 1 15 12 16 _ _ _ 7 20 71 Mazatlan Male 1967 __4 5 — — — — — — — 9 1968 — — 7 44 15— — — — _ 2 68 1969 I I 25 73 142 22 — — — _ _ 264 Total 1 1 36 122 157 22 — — _ — 2 34! Female 1967 — — 17 II — _ — — ___ 28 1968 _ _ 14 64 26 — _ _ _ _ 3 107 1969 4 7 17 101 93 14 — — — — — 236 Total 4 7 48 176 119 14 — — — — 3 371 Striped marlin Buena Vista Male 1967 _ _ _ 53 30 _____ _ 83 1968 — _ 49 64 74 34 _ — — — — 221 1969 — 17 86 113 39 18 — — _ — — --73 1970 ---_____ 6 33 1 40 Total _ 17 135 230 143 52 _ _ 6 33 I 617 Female 1967 — _ _ 46 19 _____ _ 65 1968 _ _ 37 48 60 25 — — — _ — 170 1969 — 22 51 54 42 29 — — — 9 — 207 1970 — _______6 32 6 44 Total _ 22 88 148 121 54 — — 6 41 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 1968 1969 1970 Total Female 1967 1968 1969 1970 Total San Diego Male 1967 1968 1970 Total Female 1967 1968 1970 Total __21 7— — — — — — — 28 — — .SO 26 !_____ 1 78 13 42 30 30 5 )_____ |21 -) 1 13 42 101 63 6 I _ _ — — 3 229 — — IS II ____ — — — J6 _ _ 31 18 — — — — — — 4 53 16 48 36 29 9 3 — — — — — 141 — — — — — — — — — — 6 6 16 48 82 58 9 3 — — — — 10 226 — — — — — — 22 50 — — — 72 — — — — — — 1 35 33 — — 69 __ — —'_ — — 6___ 6 — — — — — — 23 91 33 — — 147 — — — — — — 35 126 — — — 161 — — — — — — 6 85 32 — — 123 — — — — — — 3 26 2 — — 31 — — — — — — 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 of ray s 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 X 5 6 7 8 Total 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 Anii\ 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. 109 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 offish 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 >- u Z 7 111 3 O 6 - c -T — I — I — r — I — I — 1 — I — I — I — I — 1 — r — I — I — I — I — I — I — I — I — I — r Mazatlan _l I I 1l_1 I I I V I L. F 22 209.0 _l I I I I 1 I I L. Buena Vista 1 •F 35 205.7 I I I I \-' J I I I I « --'• I -I ISO 160 170 IM 1*0 200 110 110 110 140 ISO 160 ISS I6S I7S lis IfS lOS IIS lis 1]S 14S ISS 16S EYE-FORK LENGTH (cm) Figure I. — 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 = ci + bX. Range of A" 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 + h (log length)). Measurement a b Range of length (cm) N Species Length (cm) Weight r Blue marlin Female Eye-fork kg -5.690 3.318 154.0-265.1 57 0.948 Eye-fork lb -5.347 3.318 154.0-265.1 57 0.948 Snout-fork kg -7.543 3.905 221.1-347.3 20 0.954 Snout-fork lb -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 lb -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 lb -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 lb -3.739 2.507 123.1-221.7 435 0.812 Snoul-fork kg -4.059 2.356 201.7-271.0 47 0.835 Snout-fork lb -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 lb -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 lb -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 lb -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 lb -4.857 2.903 172.0-261.0 220 0.780 Female Eye-fork kg -5.243 3.113 110.0-215.1 1 ,007 0.854 Eye-fork lb -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 lb -4.914 2.950 153.0-271.0 315 0.778 Combined sexes Eye-fork kg -5.157 3.071 110.0-215.1 1.982 0.864 Eye-fork lb -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 lb -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 + hX, where Y = morphometric character measured in centimeters, and a and b = constants that are determined by least-squares pro- cedures. For weights, the equation log Y = a + b\ogX , 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 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). Ill 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). a b Range Character .V 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 of 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 fm height (cm) 20.966** 0.084** 154.0-265.1 31.0- 49.4 34 Length of maxillary (cm) 15.236** 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 fm 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 0.150** 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 >- 30 O z UJ 3 20 O 111 IE 10 -rn — I — n — i — n — i — rn — i — i — n — i i i — i n i r Mazatlan N X — M 341 171.2 F 371 175.4 •f->-i Buena Vista -M 28 168.0 •F 71 1794 _] I I L ^'T^^j . 100 110 no 130 140 ISO 160 170 ISO 190 200 210 105 115 125 135 145 155 165 175 185 195 205 215 EYE-FORK LENGTH (cm) Figure 2. — Length frequency of sailfish sampled in this study. -1 1 1 1 1 1 1 1 1 1 1 1 I I I I r- FEMALES(»)^'' _l I I L. _l I I 1_ .jM-»-»^ DORSAL HEIGHT FEMALES (•) N.274 J I I I L_ _l I \ I I 1- 100 130 140 160 ISO 200 220 240 260 EYE-FORK LENGTH (cm) Figure 3. — Weight and dorsal height as a function of eye- fork length of sailfish from the eastern North Pacific. Samples from both locations consisted of only females. We have no adequate explanation for this phenomenon; however, we note that in the central Pacific, which is west of our sampling area, more males than females are generally caught in the sport fishery (Strasburg, 1969). In the longline fishery sex ratios vary greatly both temporally and spatially (Kume and Joseph, 1969). Regressions of each of the characters as a func- tion of eye- fork length are shown in Table 5. Ex- 112 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). Character Weight Ma.ximum body depth Depth at vent Length of pectoral fin Length of pelvic fin Snout to mandible length Snout to eye length Dorsal fin height Length of maxillary Blue marlin Sailfish Striped Male marlin Female Male Female Female n.s. n.s. n.s. ** ++ — n.s. * ** ** n.s. n.s. ** ** — n.s. n.s. * + +* n.s. n.s. n.s. n.s. ** — n.s. n.s. ** ** — — * * *♦ n.s. n.s. * * *♦ n.s. n.s. n.s. n.s. n.s. eluding results for weight-length relations, results of the statistical test of ci =0 indicate that most of the fl'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 81 1 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 + h]ogX): all other relations are based on untransformed data {Y = a + hX). Character a h 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 0.274 115.1-203.0 529 Snout to mandible length (cm) 16.382 0.099 133.2-203.0 196 Snout to eve 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 0.110 115.1-203.0 553 113 so u - CO X) ^ r- ri r4 "rr ri — rj- -^O^^Of^O^ Tj->Or<-, 00OO*/'tr*-i00^sD o O O O o o o O O -^ •^ § r J d n ri d O r ) O 0^ r^i »/"i •/". f*-. ri O »/", r'-i r*-. r*~j r*-. ^ 3 s £ ^ ^ ^ § — n r*-. — (^ o d d t^ rj — ^ 00 — , ,_ . . ^Ci ON >/-; — O O o — n — \D— — OO o o o o r*-i -H — — rj ^ n ri b^. ?>^ Jn y t^ ^ r^ ">9 "T- 'V "V cfv TT cr\ oo ON -4 d ^ °^ ^ ""' ONdr-^^^'^'i^^^ ri — I r-i -^ <^J "^' f^' '^' _;_:_;_; o--'. rr r-^ «r^i l:^. —■ •— ri rJ ri ri OS O^ 00 OS ON Ov Ov ri ri rj n — — — -^ "7 "7 T" — r'l r'j n — • n O -^ ~ " " rr; rn rn r«-l n-l f^ sD rn j;^ ^ D! 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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 fm, 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 Mazadan Diego Weight n.s. n.s. n.s. Maximum body depth * n.s. ** Depth at vent n.s. n.s. * Length of pectoral fm ** * ** Length of pelvic fin ♦* n.s. — Snout to mandible length n.s. n.s. +* Snout to eye length n.s. n.s. n.s. Dorsal fin height ** n.s. n.s. Length of maxillary n.s. n.s. * 117 a m "1 r SAN DIEGO(*) ht=460 MAZATLAN (o) N=449 140 160 180 }00 EYE-FORK LENGTH (cm) Figure 7. — Weight as a function of eye-fork length of striped marlin from the eastern North Pacific. 1.5 o I- u 12 1.0 O o 0.5 66 327 223 343 j^ \ t 'I ' fir. ,o^ '21 106 67 1 12 29 90 182 IS oBUENA VISTA • MAZATLAN A SAN DIEGO _L JL _L _L _L 79 L _L _L Feb. Mar. Apr. May June Jtriy Aug.Sept.Oct. Nov. Dec. MONTH '20|- X "T ! T" SAN DIEGO I*) N-405 MAZATLAN I o, N>180 -J I I I 1 -J I I 1 1_ BUENA V(STA|«) N-567 r I I I I I MAZATLAN o N=254 LENGTH OF PELVIC FIN BUENA vista; •) N-475 SAN DIEGO N-3g7 BUENA VISTA' •) N-4B7 V SNOUT TO MANDIBLE LENGTH MAZATLAN o N=124 MAZATLAN o N-111 DORSAL HEIGHT \»^- BUENA VISTA • N = &62 SAN DIEGO * N = 34 -J 1 I I I I I L _J 1 I I _l I I I I I 200 220 EYE-FORK LENGTH (cm) Figure 8. — Morphometric characters as a function of eye-fork length of striped marlin from the eastern North Pacific. 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=Wx 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 marUn 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- 118 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 A); all other relations are based on untrans- formed data (Y = a + bX). Range of Character a b length (cm) N 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 1 16.8-204.5 189 Length of pelvic fin (cm) 33.018 0.021 1 10.0-202.6 254 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 tin 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 equatorial Pacific are also plotted in Figure 10. The plots indicate that either theie 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 119 CENTRAL PACIFIC(O) ~1 I I P SOUTH , ..PACIFIC ° 08°-2S°S) EVE-FORK LENGTH |cm) Figure 10. — Comparison of pectoral fin of striped marlin stocics in tiie 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. 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 Filers. Douglas Evans, Maxwell El- 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 PacMtlc. I. 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 1.^0°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 Istiophorus. Copeia 1969:34-44. RIVAS. L. R. 1956. Definitions and methods of measuring and counting in the billfishes (Istiophoridae. Xiphiidae). Bull. Mar. Sci. GulfCaribb. 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. STRASBURG. D. W. 1969. Billfishes of the central Pacific Ocean. U.S. Fish Wildl. Serv.. Circ. 311, 11 p. 120 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 martin, 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 (Makaim nigricans), white marVm (Tetrapturus albidus). and sailfish (Isliophorus plutyptenis) 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. 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. 121 (2) Fork length: tip of bill to tips of mid-caudal rays. (3) Body length; tip of lower jaw (with jaws closed) to tips of mid-caudal rays. (4) Eye-fork length: posterior margin of eye to tips of mid-caudal rays. (5) Caudal spread: dorsal tip to ventral tip of lobes of caudal fm. (6) Girth: twice the curved distance along one side of the body from the pelvic groove to the dorsal edge of the dorsal groove. 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 + BiXi (1) where Y = logio (weight), A = intercept, Bi = coefficient, Xi = logio (eye-fork length). The equation can be transformed to the familiar form weight =A' (eye-fork length) ' where A' = 10^ 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 + BiXi + B2X2 (2) where Y = logio (weight), A = intercept, BiandB2 = coefficients, Xi = logio (eye-fork length), X2 = logio (girth). The equation can be transformed to weight = A' (eye-fork length)^' (girth) ^^ by taking the antilogs of both sides. The relations between eye-fork length and other measures of length are given by Y = A +BiXi (3) where Y = eye-fork length, A = intercept, Bi = coefficient, Xi = 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 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 122 Table 1. — Estimates of parameters of equations (1), (2). and (3). Sample Standard Range ofXi Species y X', X'2 A B, Bi size error (inches) Min- Max- imum imum Blue marlin W LL4 — -3.84620 3.28222 — 78 0.0566 50.8 103.5 Blue marlin W LL4 G -3.15120 1.80496 1.27853 78 0.0390 50.8 103.5 Blue marlin L4 LI — 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 marlin W 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 72.5 99.0 White marlin L4 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 Il.O 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 — 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 72.5 Saiffish L4 TT — 1 1 .66889 1.87509 — 256 4.0575 4.0 28.0 ' W = log, 10 (weight) LL4 = log, 10 (eye-fork li sngth) L4 = eye -fork length LI = total length L2 = fork length L3 = body length TT = caudal spread G = girth three species were plotted against month of capture to examine the possibility of seasonal patterns in the relations. None was found. Multivariate analysis was used in an attempt to develop a method of sexing white marlin given weight, caudal spread, and the measures of length. Approximately 75% of the specimens could be propr erly sexed. Although this procedure produced better results than pure guesswork, the results are not satis- factory for scientific purposes. 123 I 30 9 - FEMALE ■MALE 30 «0 : EYE- FORK LENGTH tinchesl 70 80 90 100 Figure 1. — Relationship of weight and eye-fork length of white marhn (Tetraptunis athidus) 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- 62 60 • 58 c - 56 X o 54 z UJ -"521- O 50 li- ^ 48 UJ 46 44 ,:^^:^...-;o.*o^* 8 10 12 14 16 18 20 22 24 26 28 30 32 CAUDAL SPREAD (inches) 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. DP. 1957. Studies on ttie age and growtti of the Atlantic sailfish. 65 *" ^ 60 - FEMALE / 1 55 o c - 60 - •MALE .^ ^ /.' I o 45 z -" 40 - <- y ■ • y 2£ / • x q: Ay £ 35 sj; 30 UJ 25 20 ~ 1 1 1 1 1 1 D 5 10 15 20 25 30 CAUDAL SPREAD (inches) Figure 3. — Relationship of eye-fork length and caudal spread of sailfish (Istiophorus platyplerus) by sex. 124 Isliophonis americaniis (Cuvier), using length-frequency RIVAS. L.R. curves. Bull. Mar. Sci. GulfCaribb. 7; 1-20. 1956. Definitions and methods of measuring and counting in r-vc cvi \/A n> n j ii, n r->Ai/ic ^^^ billfishes ( Istiophoridae. Xiphiidae). Bull. Mar. Sci. DE SYLVA, D.P., and W.P. DAVIS. „ ,, „ ... , ,„ 41, Gulf Canbb. 6:18-27. 1963. White marlin, Tetrapturus albidus. in the middle Atlan- ROYCE. W. F. tic bight, with observations on the hydrography of the 1957. Observations on the spearfishes of the central Pacific. fishing grounds. Copeia 1963:81-99. U.S. Fish Wildl. Serv., Fish. Bull. 57:497-554. 125 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 $L\ species of billflshes 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 (52 135 cm FL) and saiirish, Istiophorus platypterus (Shaw and Nodder), apparently have coefficients of allometry less than 3.0. Black marlin,. M. indica (Cuvier) and female blue marlin (S!l35 cm FL) apparently have coefficients equal to 3.0. Shortbill spearfish, Tetrapturus angustirostris Tanaka, striped marlin, T. audax (Phihppi), 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 Hawaiian 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 Lacepede, sailfish, Istiophorus platypterus (Shaw and Nodder), shortbill spearfish, Tetrapturus an- gustirostris Tanaka, striped marlin, T. audax (Philippi), and swordfish, A'/p/;/ai 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.'V.. and M.Y.Y. Yong. Growth of blue marlin, Makaini nigricans Lacepede. 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. 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( 197 Don haddock, Melanograminus aeglefiniis (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 Wi = b, L,". (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. 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 126 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 oflongline 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, inJune (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. 2. Length-weight relationships using log-linear regression for weight on length were ob- tained for all species. 3. The normality of the error terms was tested for those species that had enough data to perform the tests. 4. The log-linear relationships were tested for their significance. 5. Length-weight relationships using nonlinear regression of weight on length were ob- tained for blue and striped marlins. 6. Statistical tests were performed to deter- mine whether the log-linear or the nonlinear model was more appropriate. 7. 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 speaifish, 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 127 JZ D. c o o Si 30 C3 »o -J CN 3 _2 o c £ o X lo (U — 2 .c c <- 1) •- g V, >o ri 2 Ov c .^^ I- U 3 u o 2; •^ h- i^'-S 2 = 2 ;;'=° ^1 o ^ o\ u : = . •■ , ~ •yi O U U U^ D. c: >< " X) c o 3 Z o f- o vO >. Ov r- ON 00 -f ri 00 u", o — 'C — ri r*^ I I I I I I I I I I I I I I I I I I I "-' I -' ^ I I -=t 2; !:: I ^ I I I I I S I Xi -rt MM MM Ml MM _* C ^ E o r- r*-, rA -a u c •a at! c c -o 0) 2 1_ 3 o c E 0. 5J 5 SI) y (T c/l c 05 o Q TJ a rr. C a a F C 60 C u B ■a ^ p o J= ^^ c ei) -n C/) «j c ■S r! =: 1 ID C X r^j on <1> c J= n o !_> o ^ o o ce .n a. V ^ a V5 I I I I o I ^ tT — — so o o o o o o — o o p o o o n ^ o MM £/) * 1 vO z ri r4 ri o 1 en * * * # Z o o o o o o I I I I I MM E I — O O — r*"! r-l — r*-, Tj- 00 oooooorirroo W-, — — I/-, OQC^CijN^OC c: o o o o o o o o o f-^ _ __ _ ^/-, rj ri r*-, r". sO oooooooooo oooooooooo n r- cj\ r- o *"i oo n — (7; sD -^ TT ri ri r^l 'T w"^ r*-I 00 ri ir, O »/". — — ■^ 00 so •'"' -rf— 'rrTt\C0CO<^r-r^ 000r~-0— ^OOr^w-, r*^ r*", r*^ ri r*"i r«-i ri r*". ^'^ c^ o o o o o o o o o ( X X X X X X X X X X X X - r^ vn oc ITS o V"i o fy-, vO sD D r 1 Tf ri vO ri r^t T 00 rj ON o n fx-. o- r^ OC 'i- r^ ri -; ~~[ o 1^ o rj ri Ov ov o q r^. ■^ I/-. ^ ri r*-i — rJ «r^i w-i rs 00i/"i'^>»D^ ^b U "oi o c c o o o o o o o o u ul ll U l- Qm J a. -1 f- H H H H ti- c E c> ■Tt E fi D O 3 ^r. _1 a. -3 T3 -a T3 jj _Qj _a> ^ o o o o o o o c cl a. 0. CL _ E ^ ■o ■n tz: o a o a # in (/5 C/5 (/5 C/1 Z - ^ o ■ d Cy5 i/1 130 45 50 LN LENGTH (CM) Figure I. — 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. I ) and then only for the longiine-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" testsforblack 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 "/?-" 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) pooled category indicates pooling of longline and trolling data. The data sets Sample R- in Species Data set size [N) h a percent € Gl' G2> Blue marlin Pooled 453 6.3087x10-" 2.9827 93.1 -0.5717 SI 35 cm FL Longline 68 3.9290x10-" 3.0821 94.4 -1.1889 — — Trolling 385 8. 5 300 X lO-« 2.9265 92.2 -0.6549 _~t ^99** 36.691** Trolling 384 1.9421x10-" 3.1895 98.9 0.3003 -0.266* 3.723** Trolling (male) 276 18.9972x10-" 2.7756 83.1 0.1438 0.121 NS 2.894** Trolling (female) 86 4.8246x10-" 3.0249 90.8 0.4055 -2.991** 20.499** Trolling 85 1.7082x10-" 3.2111 91.9 -0.1341 -0.067 NS 0.577 NS Striped marlin Pooled 53 1.0978x10-" 3.2589 90.7 -0.1553 — — '** 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 - FEMALE BLUE MARLIN (N'86) '.'"■" - - K - " - 1 1 1 1 1 1 1 1 1 1 1 1 1 i.^.J 1 K _-« ■ ^ ^ « . 3.00 3.40 3.80 4.20 4.60 5.00 5.40 5.80 6.20 5.30 5.40 5.50 5.60 570 5.80 5.90 &00 6.10 0.24 1 1 1 1 , , 1 1 1 1 1 1 , 1 , , FEMALE BLUE MARLIN (N = 85) < 0.17 n \ r- ,a\ I I I I ■ I 1 1 1 1 1 1 i — 1 — 1 1 1 1 I 1 1 — i — I 1 1 1 1 1 1 1 ' 1 ' ' ■— 3.00 3.40 3.80 4.20 4.60 5.00 5.40 5.80 6.20 530 5.38 546 5.54 5.62 5.70 5.78 5.86 5.94 STRIPED MARLIN (N-53) ... 1 1 t I I I I r I I t r t t I 1 1 I I I I I I 1 1 1 1 1 1 1 i 1 1 1 1 — 2.00 240 2.80 3.20 3.60 4.00 4.40 4.80 5.20 4.90 5.00 5.10 5.20 530 5.40 5.50 5.60 5.70 LOG. WEIGHT (KG) LOG, FORK LENGTH (CM) 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- 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 132 FEMALE BLUE MARLIN (N-86J 1 :-.f" =.''." " "/ ■ r\':<{j-\'- - XK - - 1 1 1 1 1 ' 1 ; 1 1 1 1 1 1 1 40 80 120 160 200 240 280 320 360 200 240 280 320 360 400 440 480 520 FEMALE BLUE MARLIN (N = 85>. 40 80 120 160 200 240 280 320 360 200 240 280 320 360 400 440 480 520 STRIPED MARLIN (N = 53) _j t i_ 25 41 57 73 89 105 121 137 142 162 182 202 222 242 262 282 302 WEIGHT (KG) FORK LENGTH (CM) 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 ofo^^is biased in nonlinear regression 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 133 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 H^: a = 3.0 and H^: « / 3.0 (a two-sided "t" 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 SWORDFISH W^ 2,3296 X 10"' FU^"°* 100 i 20 1- X o S 10 ^ 25 BLACK MARLIN 150 200 250 300 350 400 200 225 250 275 300 325 350 375 400 SHORTBILL SPEARFISH W= 5 0083 X 10'^ FL 8 cr. 38136 oi — 130 150 1 1 1 \ 1 r I I 1 1 . STRIPED MARLIN W^ 5 7126 xiQ-'Fl'-^'^* N =53 ,y. : 100 ' .^ 50 • -.^^2^^ - . •;.v^'^^ 140 150 160 170 180 190 125 150 175 200 225 250 275 300 325 LENGTH (CM) SAILFISH W= 2.0739 X IO'fl^^'* V^ -J ^ L- 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 -o c/) c a> c^ j= lA T3 Q (/) ^ W ■^ \D .S£ OS '^ 1) " — s: ^ Q. g , O ^ -^ — T3 3 C C « x: E "^ D :^ a E ,y o •5 i c -a Z c I '5 £ ;/i o O so — _ .S /-i r'i V-. r- o r-- "^ -^ "^ C>0 Z C/5 C/l C/) Z Z Z n o i/"i — -^ 00 vo »o ■^ r-- Q r~- */■! r*". W-, o o o r~- ^ ^' oo r*-. »/-, r*~, m r-j r^i ri r*-. f^ r*-i oooooooo xxxxxxxx ^iOO\»/^0\r*~iv£i\0 ri ^ rJ -q- rr 1 1 ' \ W 1 j Till {| ! ir u k V illklji. '--"" 961 ' IS 162 ■ ~ 1 S6J ' 964 965 Jf MAMJ JASONO 1966 -^ ■ SOND,JFMAWJJ«50ND,JFUAUJJASON0JFy*MJJ«S0HD,JI S0NDJrM*MJJ4&0N0 ' Southwest Fisheries Center. Honolulu Laboratory, National Marine Fisheries Service, NOAA, Honolulu, HI 96812. Figure 1.— Monthly landings of swordfish (upper panel) and average size offish (lower panel) from 1961 to 1966. 142 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, Tetiapterus aiulax, 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 I. — Summary of swordfish data used in maturation and fecundity study. Paired Most Date Fish ovary weights advanced mode Mean Number Fecundity Fresh Preserved In Sample of size 10% Formalin Maturity' diameter measured i (millions Gonad^ number landing (kg) (g) (g) (mm) of ova) Index BB-1 6/24/64 187.2 11.566 10.033 ER. R,S 1.019 153 2.24 6.18 BB-2 6/2.')/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 11 3/64 156.5 9.389 ( 8,267)3 ER 0.986 228 4.80 6.00 BB-5 11 3/64 142.4 8.373 ( 7.332)3 ER 0.923 403 9.38 5.88 BB-6 11 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 1 1/26/65 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-IO 1/25/67 90.3 390 415 ED 0.154 100 — 0.43 BB-Il 2/24/67 46.7 (Damaged) BB-12 4/ 5/67 .54.4 172 174 ED 0.107 100 — 0.32 BB-B 4/13/67 76.6 163 176 IM (pooriy preserved) 0.21 BB-I4 4/21/61 121.5 8,164 ( 7,187)» RP 1.438-" 113 3.73 6.72 BB-I5 5/22/67 83.0 4.327 4,200 ER 0.990 306 3.21 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. ^ 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 I 23456789 IP II 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: 1 . 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. 3. 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. 5. 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. 6. Ripe Ova (Figure 3D) Ova are transparent and with oil globules. Diameters range from 0.80 to 1.66 mm. 7. 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. 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 144 Figure 3.— Developmental stages of swordfish ova. A. Developing. B. Advanced developing. C. Early ripe. D. Ripe. sample RMO {P = 0.01) and samples RMC and RPO {P = 0.05). An analysis 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 numberof 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, 191 1 ), 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(Nakamuraetal.,1951). Yabeet 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. Yabeetal. (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 145 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. Table 3. — Ratio of numbers of ripe to early ripe ova. 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 68.4L500 7.4417.S0 1 4025 RMC 200 67.5L'i00 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 LPC 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 Between groups Within groups Total Sum of squares d.f. 4072.5925 17 162458.1074 3582 166530.6992 3599 Mean square F ratio 239.5643 5.2821 45.3540 ' 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 occuired 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- Number of eariy Number of Sample' ripe ova ripe ova Ratio index RAC RAM RAO RMC RMM RMO RPC RPM RPO 170 195 220 303 319 477 194 280 106 212 291 256 269 212 266 172 248 284 1.2470 1.4923 1.1636 .8877 .6645 .5576 .8865 .8857 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 Yabe, 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 wasjudged ripe, also had residual ova. It is interesting to note that Sella (191 1) 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 146 X X, X " 120 140 160 FISH SIZE (kg) 200 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. 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 Pise. 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. In 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-67S, 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. Contribute alia conoscenza della riproduzione e dello sviluppo del pesca-spada (Xiphias gladius L.) Mem. R. Com. Talassografia Italiano 2:1-16. UEYANAGI, S. 1974. A review of the world commercial fisheries for bill- fishes. In 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. l-Il. 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. In 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. 147 APPENDIX: Table 1. — Frequency distribution of ripe ova diameters from selected parts of a swordfish ovary (sample BB-3). Subsamples' Ocular micrometer Milli- 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 -) -> _ 1 _ _ _ _ _ 86 1.7630 — — — — — — 1 — — — — — — — — — — — 85 1.7425 — ■> — — — — 1 — — — — 1 — — — 1 — — 84 1.7220 1 — — — — -f 1 1 ■> — 1 — — — 1 — -> — 83 1.7015 — — 1 1 — 1 3 2 5 1 1 — 1 — — 1 1 82 1.6810 — 3 1 — 2 4 3 2 4 1 4 1 — 2 — 1 1 81 1.6605 2 -) 1 3 2 3 -> 4 -) 3 "7 3 -) 1 1 1 -) 80 1.6400 5 -) 4 4 4 4 3 7 10 4 6 5 -) T 4 1 1 79 1.6195 4 4 6 3 4 3 2 2 7 — -) 2 4 4 3 8 3 78 1.5990 4 6 6 6 3 7 10 11 9 7 8 5 ■> 3 5 5 3 77 1.5785 4 6 9 1 8 2 13 14 12 5 8 8 10 4 8 II 9 11 76 1.5580 10 14 8 8 5 12 9 3 14 7 9 10 7 10 11 3 5 10 75 1.5375 4 11 8 12 8 10 5 13 7 11 6 3 10 5 12 9 13 12 74 1.5170 7 11 11 7 5 4 7 11 8 7 17 12 17 10 12 7 9 8 73 1 .4965 11 13 7 10 12 7 10 13 20 16 20 15 13 11 13 14 14 11 72 1.4760 21 13 II 11 13 10 10 10 15 11 14 17 10 18 19 13 14 11 71 1.4555 18 16 6 4 7 8 9 6 7 16 16 18 11 9 11 14 18 16 70 1 .4350 14 15 10 8 15 10 7 11 12 12 15 16 16 13 13 21 11 18 69 1.4145 10 5 11 6 7 7 8 8 10 7 11 4 9 14 8 13 6 12 68 1.3940 20 11 9 15 16 7 12 11 12 17 8 10 20 12 10 16 12 10 67 1.3735 14 11 19 11 8 13 11 8 14 12 5 12 12 10 16 10 11 21 66 1.3530 6 9 10 13 11 9 17 8 3 10 8 4 8 9 5 10 8 13 65 1.3325 7 6 12 11 10 16 6 7 3 5 7 12 9 8 6 5 5 6 64 1.3120 4 8 5 7 -> 5 7 9 4 8 2 6 3 12 11 9 9 6 63 1.2915 10 4 8 13 6 9 4 9 4 6 7 6 4 9 5 7 5 6 62 1.2710 3 9 5 4 6 5 6 7 1 12 8 5 4 10 4 8 7 4 61 1.2505 3 3 3 3 6 8 9 2 -> 4 5 4 4 3 -> 4 9 2 60 1,2300 5 4 1 5 7 4 6 4 3 5 4 ■> 9 6 6 1 5 59 1 .2095 2 3 -> 4 5 3 f 5 2 1 — 1 1 1 3 2 1 58 1.1890 2 — 4 5 6 3 3 4 — 3 — 6 3 1 3 4 6 4 57 1.1685 1 T 6 6 5 9 2 2 1 -> 1 — — 4 2 1 1 56 L1480 1 1 ") 2 3 — — -) 1 1 2 — — 1 — 1 — 55 1.1275 2 1 1 T 6 4 1 1 1 1 — 1 -> T T — — 54 1.1070 — 1 4 5 3 — 1 — 1 1 1 3 1 1 -» 1 — — 53 1.0865 -) 2 -> 1 1 1 I — 1 1 — — 1 1 1 — 52 1 .0660 1 1 3 3 1 3 3 — 1 — — — — 1 — 1 — 51 1 .0455 — 1 — 1 — 2 1 — 2 2 2 1 — 1 1 — — — 50 1.0250 — 2 — — — 1 — — 1 2 — — 1 1 — — — 49 1.0045 — — — — — — — — — 1 — — — — — — 1 48 .9840 1 — 1 1 — — 1 — — — — 1 2 — — — — 47 .9635 — — — 1 1 — 1 — — — — — — — — 1 — 46 .9430 — 1 1 1 -> — — — — — — — — — — 2 — 45 .9225 — — — — 1 1 — — — — — — — — — — — 44 .9020 — 1 — — — — — — — — — — — — — — — ' 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 ayer 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 outs r layer LPO - Left posterior region outer layer 148 Occurrence, Morphology, and Parasitism of Gastric Ulcers in Blue Marlin, Makaira nigricans, and Black Marlin, Mal^aira 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 Bilinsh 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, Queens Medical Center, Hon- olulu. HI 96813. 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 1 14 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, Contracaeciim 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 nematodes. 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. 149 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 ka cm h 4 July. 1967 Makaira nii>ricans F 151.5 303.4 5.5 6 July, 1967 M 141.0 290.0 3.5 29 July. 1968 M 67.6 224.9 6.5 29 July. 1968 Makaira indica F 83.9 240.9 7.5 31 July, 1968 F 86.2 256. 1 1.5 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 F 189.1 315.7 6.5 2 Aug.. 1968 F 102.0 270.3 7.5 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 Tip of snout to center of distal edge of caudal tin. throughout the stomach (Fig. 1). They were noncan- cerous. Edges were indurated and raised sHghtly 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 I. — 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 Figure 2. — Closeup view of same black marlin stomach showing nematodes burrowing in base of ulcer. •ere-- ^ ^^^ ^' 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. 25 x). 151 Figure 4. — Microscopic section of base of ulcer from same black mariin showing ex- tensive fibrosis laminated around old nematodal debris (H & E stain, 25 x). 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 mariin captured during a billfish tournament. Other examples are the spiny puffers, Diodontidae, which sometimes occur in mariin 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 multiple ulcers in some of the mariin stomachs. For example, the black mariin 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 mariin, 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 mariin stomachs without citing the presence of ulcers. Wal- lace and Wallace (1942) found Contracaecum incur- vum in 60 of 86 stomachs of white mariin, T. albidus, captured off Ocean City, Maryland. Morrow (1952) reported finding C. incurvum in each of 53 stomachs of striped mariin, 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- 152 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 tniiuatiis. 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, Squaliis acan- thias, perfusion of isolated gastric mucosa with his- tamine resulted in an increased secretion of acid 1 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:! 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- 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. FishWildl. 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 mdrWn (Makairu nigricans) and black marlin iMukaini indica) in Hawaiian waters. (Abstr.) Proc. Hawaiian Acad. Sci., 44th Annu. Meet., 1968-1969. MORROW. J. E. 1952. Food of the striped marlin, Makaira mitsiikiirii. from New Zealand. Copeia 1952:14.3-145. STRASBURG, D. W. 1970. A report on 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, Telrapliims utbiJiis Poey. Publ. Chesapeake Biol. Lab., Board Nat. Resour., Dep. Res. Educ, Solomons Island, Md. 50:3-10. 153 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 IS 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 3'/2/0 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 liaren- 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. 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 ft-om 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 bluefm tuna, Thiinnus thynnus; 1 white marlin, Tetrapturus albidus: 1 escolar, Lepidocybium flavobrunneum; 3 dolphin. 154 Table I. — Longiine cruises yielding swordfish for mercury analysis. Designation Date Number of Area Number of sets swordfish sampled 5 Georges 14 8 Banquereau and Grand Banks 63 6 Browns to Banquereau 73 6 Georges to Cape Charles 43 8 Bahamas and Caribbean 17 12 Cape Hatteras to Sable 17 10 Cape Hatteras and Georges 16 14 South of Browns to Banquereau 4 13 South of Grand Banks 3 10 East of Grand Banks 4 HS 104 DG 1 23-27 July 1971 23-31 Aug 1971 DG 2 DG 3 BIO 72-004 FG6 FG7 09-17 Sept 1971 14-27 Oct 1971 01-22 Mar 1971 27-IVIay-8 June 1972 17-28 June 1972 FG 8 6-19 July 1972 FG 9 FG 10 26 July-9 Aug 1972 14-31 Aug 1972 Coryphaena hippunis; 1 long nose lancetfish, Alepisauntsferox; 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, Lamiui nasus: and 4 unspecified 1am- 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 carcluirias) obtained in an otter trawl, and two basking sharks {Cetorhiniis ma.ximiis) 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 offish taken from swordfish stomachs (Table 3). DISCUSSION The areas of capture can be divided into five parts; four divisions of the longiine 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 longiine fishery are shown in Figure 1 , while the dates of fishing are given in Table 1. Mercury levels found in swordfish tissue (dorsal muscle) were tabulated (Table 4) by localities and months. Variation With Size The slopes, correlation coefficients and "/" val- ues obtained by application of the least squares fit for linear relation between fork length (x) and mer- cury content ly) 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 sampled Fork length (range) Total mercury 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 T 137-236 0.83 0.68-0.98 Scalloped hammerhead shark -> 147-177 3.64 2.40-4.89 Mako shark 1 151-159 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 ") 382 0.08 0.03-0.14 155 Table 3. — Total mercury (ppm) in food species taken from stomachs of swordfish. Specimens Number Total mercury content Dietary importance sampled (ppm) Stromateidae (Butterfrshes) Cenlrolophus niger (Black Ruff) Stomiatidae (Scaled dragonfishes) Slomias boa (Boa dragonfish) Myctophidae (Lantemfishes) Paralepididae (Barracudinas) Alepisauridae (Lancetfishes) Alepisaums ferox (Longnose lancetfish) Nemichthyidae (Snipe eels) Nemichthys scolopiiceus (Slender snipe eels) Gadidae (Cods) Merliiccius bilinearis (Silver hake) Carangidae (Jacks) Scombridae (Mackerels) Scomber scombrus (Atlantic mackerel) Scorpaenidae (Scorpionfishes) Sebustes mariniis (Redfish) Monacanthidiae (Filefishes) Cephalopoda (Squids) Ilex illecebrosiis (Shortfinned squids) 2 0.14 Occasional 1 0.17 Occasional 15 0.24 Important 36 0.20 Important 2 0.41 Occasional 4 0.24 Occasional 9 0.17 Locally important 2 0.13 Occasional 73 0.17 Bait 14 0.34 Locally important 14 0.21 Occasional 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 offish 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 Conoda Includes CofitibMn Figure 1. — Map of Northwest Atlantic Ocean showing areas of capture of swordfish used for mercury analysis. 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 offish fi-om 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 156 Table 4. — Comparison of total mercury content (ppm) of dorsal muscle tissue with size of swordfish caught in different areas. Size Total mercury content *Significant at 0.90 level. ♦♦Significant at 0.95 level. 7" for 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 4.732** Banks D.Sable- Sept 94 145 ( 74-2471 1.07 (0.05-2.72) 0.006816 0.406 4.305** Banquereau C. Georges Oct 25 142 ( 99-18.^) 0.88 (0.19-1.88) 0.005626 0.368 1.937* B. Cape Oct 31 129 ( 78-188) 0.57 (0.05-1.35) 0.009671 0.823 6.315** Hatteras- Hydrographer Canyon 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 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 157 Table 5. — Comparison of total mercury content (ppm) of dorsal muscle tissue from swordfish by sex and by area. Area Month Number and Fork length Mean Range Total mercury content Mean Range Slope Correlation "/" for testing sex (cm) (cm) (ppm) (ppm) coefficient slope E. Grand Banks Aug 7 Males 152 (136-178) 1.39 (0.7-1.9) 0.02.398 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- Banquereau Sable- Sept Sept 9 Males 65 Females 148 144 (127-170) ( 74-247) 1.09 1.07 (0.7-1.4) (0.1-1.8) 0.007265 0.007269 0.543 0.417 1.713 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 mercL iry content Tissue samples .Average Range (ppm) (ppm) Dorsal muscle 210 1.15 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 It 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 C D E Tissue Caribbean- Bahamas Cape Hatteras- Hudson Canyon George: s Browns to Banquereau Grand Banks July Oct. 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) 1I7( 3) Brain 62 (1.) 58(3) — — — — 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. 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 Dausoii 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 i;lad'iiis L. in the Northwest .Atlantic Ocean. In 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 nUuliiis Linnaeus) in the Northwest Atlantic Ocean. //; 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. 159 Mercury in Several Species of Billfishes Taken Off Hawaii and Southern California RICHARD S. SHOMLRA' and WILLIAM L. CRAIG" ABSTRACT The results of analjses of the mercur> content of 37 blue marlin. Makaira nigricans. 56 striped marlin. Tetrapiurus audax. and 3 SHordfish. Xiphias gladius. are presented. The le\els of total me^cu^^ found in white muscle of blue marUn caught in Hawaiian waters ranged from 0.19 ppm to 7.86 ppm; fish specimens ranged in total weight from % pounds (43.5 kg) to 906 pounds (410.9 kg). A tr^nd of increasing mercun. level with increasing size of fish was noted. The mercurj content in the li»ers of 26 blue marlin specimens examined ranged from 0.13 ppm to 29.55 ppm; there was no apparent trend noted between mercur> content in the liver and size of fish. Striped marlin from Hawaii and southern California showed a range of mercurv 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 kgi for the Hawaii and California samples, respectivelv. From the wide spread of mercurv levels encountered in striped marlin. a trend of mercurv level v» ith size of fish could not be easilv detected. Livers of nine specimens from the Hawaii catch were analyzed: mercurv levels ranged from 0.05 ppm to 1.53 ppm. Three swordfish weighing 6 pounds (2.7 kg), 100 poimds (45.4 kgi, and an estimated 5(X) poimds (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 stunnecJ the nation, particularly the fishing industry, with the release of stories that some canned tuna and swordfish steaks contained mercur\ in excess of the Food and Drug Administration (FDA) interim guideline of 0.5 ppm (Bernstein. 1970: Fleming. 1970: Los Angeles Times. 1970: Coffey, 197 U. Prior to State University of New York Professor Bruce McDuffie's discoven, that mercurv levels in two cans of tuna exceeded the FDA guideline, the problem of mercur\ in fishes was thought to be localized and confined to freshwater fish species. The high levels of mercurv 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. NOA.\. Tiburon. C.\ 94920. -California Department of Fish and Game. Long Beach. C.\ 90802: present address: Southwest Region. National Marine Fisheries Service. NO.Jl-\. Terminal Island. C.\ 90731. 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 mercur\ 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. Thunniis alalunga. for mercur\ analysis during the summer of 1971. Our purpose in this paper is to provide the results of anah sis for total mercurv 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 160 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 offish 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 Vi 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. 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 fi"om 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 offish. 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. - 1 1 1 1 r 1 1 1 - o SOUTHERN CALIFORNIA SAMPLES ■ HAWAII SAMPLES " ' HWMII SAWLES (N'M) ^.-05O45+0.0l0762X Y - « o y o ALL SAMPLES IN"56) / 9»o.a*4+o.oo34esx _ oo o y o o ^^^.^-^^ /t ..^""l^-^^-^^^' — - ■ ^^^^1^ ""^""^ \ _ _-— — i^^5^^^^^^- S CALIF SAMPLESIN<42r -"-"'■'y^ •* '' '" 9.O.393 + 0.O0253K _ - / ' 6 - / ' ' - L r- , ' , , .•. 1 \ 1 125 ISO 179 ZOO 225 POUNDS W GO TO 60 90 100 1 10 kg FISH SIZE ^Reference to trade names does not imply endorsement by the National Marine Fisheries Service. NOAA. Figure 1. — Relationship between total mercury (ppin) in white muscle tissue and size offish of striped marlin from southern California and Hawaiian waters. 161 Table 1. — Comparison of mercury levels in striped marlin tissues analyzed by two laboratories. Laboratory no. 1 Laboratory no. 2 Mean HG Standard deviation >0.5 ppm <0.5 ppm High value Low value 0.77 ppm 0.35 15 fish 2 fish 1.0 0.4 0.84 ppm 0.50 12 fish 5 fish 2.1 0.1 Some of this variability may be due to analytical techtiique 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 from fish taken in Hawaiian levels of white muscle tissue from 0.7 ppm to 7.86 ppm in 96 and 906 pounds (43.5 and are presented in Figure 2. striped marlin, the mercury were much higher. Only 7 the blue marlin were waters. Total mercury in this species ranged fish weighing between 410.9 kg). The results , When compared to levels in blue marlin 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 21 1 pounds (95.7 kg). As with striped marlin, the range in mercury level for blue martin 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 'r ■■„ 500 eoo TOO 800 900 POUWS zoo 250 300 350 400 kg 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.) 162 30 - I 1 1 -1 - » ' ■ z X S2 UJ » 10 UJ » 9 _ * I K a a 8 > cr D u (T 3 6 - < o i= 5 a. UJ > 4 J , - I 3 - 2 X > - 400 300 600 TOO 800 900 POUNDS 200 250 XX) 150 400 kg FISH SIZE Figure 3. — Relationship between total mercury (ppm) in liver tissue and size offish 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. LB. 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 CD. 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 MP. 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 w hite marlin elsew here 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 helone 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. 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 (Perez 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. 164 STATUS OF THE WHITE MARLIN IN THE EASTERN ATLANTIC Robins and de Sylva (1963: 89-90) reviewed the synonymy of Tetmpturns 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 Tetiaptiirus 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. Tetraptunis lessonae. This description, in fact, postdates Poey's (I860) de- scription of Tetraptunis alhidiis from Cuba, by on- ly one year. Since then Eastern Atlantic records of alhidiis occur under A/«A(//;-o nigricans, Tetraptunis belone, T. lessonae in various combinations. Rob- ins and de Sylva (1961: 97) referred the record of T. belone by Legendre ( 1928) to albidiis and discuss other probable records. Gonpalves (1942: 54-55) was perhaps the first to suggest that albidiis occurred in Portugal's waters. La Monte (1955: 331-332 first referred lessonae to the synonymy of albidiis and from this date albidiis 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. albidiis and other "istiophorids'" in the eastern At- lantic is being prepared by Donald P. de Sylva. MATERIAL EXAMINED The 57 specimens identified as Tetraptunis al- bidiis 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- lure of numbers 39-57 were noted by Rodriguez- Roda and Howard ( 1961 : table 1 ) and these data are not repeated here. 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. 3L 35, 37; 10 Aug.: EATL-5; 12 Aug.: EATL-17: 17 Aug.: EATL-6, 7, 10, 11; 21 Aug.: EATL-25, 26, 28: 22 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; I 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. Di = spinous or first dorsal fin D2 = second dorsal fin C = caudal fin A I = first anal fin A2 = second anal fin Pi = pectoral fin P2 = pelvic fin * orig. = origin (in reference to fins) CD. = 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, 1 1, 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- 165 Rio - ? 4- 2 - 50 60 70 80 90 SIZE CLASS (LBJ 100 Figure I. — Weight-frequency histogram of white marlin, Tetraptiirus alhidiis, from the eastern North Atlantic Ocean. Sohd color = females, cross-hatching = m^es. 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 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 lb (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 lb (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 166 along the eastern coast of Brazil from Pemambuco 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 Tclruplurus. Arch. Zool. Anal. Fisiol. 1(11:259-261. pi. 17. DE SYLVA. D. P.. and W. P. DAVIS, 1963. While marlin. Tcliapliini\ iilbuliis. in the Middle American Bighl. with observations on the hydrography of the fishing grounds. Copeia 1963:81-99. Table I. — Fin-ray counts of western' and eastern Atlantic white marlin. Tetraptunis at- hidus. Dorsal Spines D2 Rays Anal Spines A2 Rays Pi Rays - W. All. E. All. 38 39 40 41 42 43 44 45 5 6 7 13 14 15 16 17 \i 1 3 8 1(1 II 9 20 21 1 4 18 18 5 5 6 7 17 18 19 20 21 22 2 41 - 1 2 6 23 9 _ 1 7 16 19 8 5 1 26 30 9 28 12 3 2 5 50 1 2 10 30 13 I Data from Robins and de Sylva (1961: Table I) Only the left pectoral fin was counted. 167 GIBBS. R. H. JR. 1957. Preliminary analysis of the distribution of white mar- lin, Makaiia n/hiila (Poey). in the Gulf of Mexico. Bull. Mar. Sci. Gulf Caribb. 7:360-369. GONC.^LVES, B. C. 1942. Collecgao oceanografica de D. Carlos I. Catalogo dos Peixes. Trav. Stn. Biol. Mar. Lisbonne 46. 108 p. LAMONTE. F. R. 1955. A review and revision of the marlins. genus Makaim. Bull. .\m. Mus. Nat. Hist. 107:323-358. LEGENDRE, R. 1928. Presence du Tclraptiinis hcloiic au large de la Bre- tagne. Bull. Soc. Zool. Fr. 53:391-392. MATHER. F. J.. III. 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.. 111. A. C. JONES, and G. L. BEARDSI FY. JR. 1972. Migration and distribution of white marlin and blue marlin in the .^tlantic 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. RIVAS. L. R. 1956. Definitions and methods of measuring and counting in the billfishesdstiophoridae. 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- flsh. Ti'lriiptiinis hclone. based on western North Atlan- tic specimens. Bull. Mar. Sci. Gulf Caribb. 10:383-413. 1963. A new western Atlantic spearfish, Tcliaptnnis pjhiegeri, with a redescription of the Mediterranean spearfish Tetraptiinis In-liiiw. 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. 1st. Bologna, ser. 2, 6:386-.396. TORTONESE. E. 1961. Mediterranean fishes of the family Istiophoridae. Nature (Fond.) 192:80. UEYANAGI. S.. S. KIKAWA. M. UTO, and Y. NISHIKAWA. 1970. 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On ON W-. ^ O :i I g TOsCocr^Ori^O^ ^>D CO T3 E o x: n. O O "'i 0-. oc s ?; s s f, g r- oc r- I— 1 O "■ ri Tj- I ?, <^-C-^Xrifv X 5fi X J J -J c o 3 C < S 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.YipAws, 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 in a 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 'Stale Museum, Windhoek. South West Africa. -Division of Sea Fisheries. Beach Road, Sea Point. Republic of South Africa. 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, orupwelled 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 /"errap- 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. 175 Table 1. — Billfishes recorded from the Cape of Good Hope. Date Locality 'Method -Size Date Locality 'Method -'Size Xiphias gladius Maikaira indica 15.2.56 Dassen Isl. B 1 ,060 mm 30.3.62 W. Slangkop L ± 150 kg 20.7.56 40 miles W. Slangkop B 2,620 mm 31.3.62 W. Slangkop L ± 370 kg 19.8.56 40 miles W. Slangkop B 32 kg. 31.3.62 W. Slangkop L ± 80 kg 25.3.58 False Bay X 558 mm 20.5.62 N.W. Cape Columbine L — 7.3.58 W. Slangkop B 875 mm 24.1.63 40 miles S. Cape Point L 3,648 mm 8.3.58 15 miles S.W. Cape Point T 875 mm 20.2.63 40 miles S. Cape Point L 645 kg 14.4.59 30 miles W. Slangkop B 86 kg 22.2.63 W. Peninsula L 2,936 mm 8.10.60 60 miles W. Slangkop L 170 kg 22.2.63 W. Peninsula L 2,570 mm 12.1.61 20 miles W. Slangkop B 106 kg 2.3.63 W. Peninsula L 3,025 mm 3.4.61 W. Danger Point B ± 3 kg 4.3.63 W. Peninsula L 2,753 mm 1.II.6I S.W. Slangkop L ± 190 kg 29.3.63 Camps Bay beach X 2,151 mm 22.2.62 W. Slangkop ^L ± 4 kg 22.2.62 30 miles W. Cape Point L ± 55 kg Makaira nigricans 1.3.62 W. Peninsula L ± 60 kg 1838 Table Bay X 30.3.62 W. Peninsula L ± 1 kg 7.6.58 Hout Bay X ± 225 kg 31.3.62 W. Peninsula Makairu indica L ± 1 kg 23.6.61 16.4.64 45 miles N.W. Dassen Isl. 30 miles S.W. Cape Point L 2,959 mm 3,385 mm 16.1.61 W. Peninsula L 3,527 mm Tetraptunis audax 27.1.61 W. Peninsula L 3,334 mm 25.2.61 W. Slangkop L 1 ,746 mm 21.2.61 30 miles W. Slangkop L 3,559 mm 25.2.61 W. Slangkop L 2,182 mm 2.3.61 35 miles W. Slangkop L 3,558 mm 15.3.61 W. Cape Point L ± 70 kg 3.3.61 W. Slangkop L 2,850 mm 26.1.62 40 miles S.W. Cape Point L 2,285 mm 13.3.61 W. Slangkop L ± 340 kg 1.2.62 W. Peninsula L 2,120 mm 13.3.61 W. Slangkop L ± 370 kg 8.2.62 W. Peninsula L 2,011 mm 14.3.61 W. Cape Point L 3,180 mm 17.2.62 W. Peninsula L ± 70 kg 15.3.61 W. Danger Point L 3,000 mm 22.2.62 30 miles W. Cape Point ^L 2,131 20.3.61 W. Cape Point L ± 370 kg 22.2.62 30 miles W. Cape Pomt L 2,132 9.1.62 W. Dassen Isl. L 2,959 mm 22.2.62 30 miles W. Cape Point L 2,112 11.1.62 W. Peninsula L 3,487 mm 7.3.62 W. Peninsula L — 15.1,62 W. Cape Town L ± 370 kg 7.3.62 W. Peninsula L — 28.1.62 40 miles S.W. Cape Point L 2,545 mm 17.4.62 S.W. Cape Point L ± 50 kg 28.1.62 40 miles S.W. Cape Point L 3,210 mm 30.1.6: 30 miles W. Cape Point L 2,935 mm Telraplunis alhidiis 30.1.62 30 miles W. Cape Point L 3,100 mm 2.3.61 '35 miles W. Slangkop L 1,918 30.1.62 30 miles W. Cape Point L 2,935 mm 11.2.62 W. Cape Point L ± 45 kg 30.1.62 30 miles W. Cape Point L ± 280 kg 10.5.62 35 miles W. Slangkop L ± 40 kg 25.2.62 30 miles W. Cape Point T 210 kg 26.2.62 W. Peninsula L ± 300 kg Tetraplurus pfluegeri 7.3.62 W Peninsula L ± 300 kg 24.6.63 125 miles N.W. Caoe Columbine I 1,795 mm 7.3.62 75 miles W. Cape Point L 3,460 mm 13.7.64 33''09'S 16°07'E ^X 588 mm 'B = bottom trawling, L = longline, T=trolling. X=other (usually standing). -Given as weight or body size (tip of mandible to fork). ^X. gladius found in stomach of T. audax. *M. indica and T. albidiis 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 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 on a large scale only during the years 1 96 1 - 1 964. The boats fished for a company under contract to supply tuna; all other fish landed could be disposed 176 of by the skipper as he wished. There was little or no demand for mariin and skippers were only too pleased to inform the South African Museum when they landed mariin 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. gladiiis) four species of mariin, the black (M. indica), the blue {M. nigricans), the striped (T. aiidax) and the white (T. alhidus), and one species of spearfish (T.pfliiegeri) 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 offish examined were not taken by longlines but by bottom trawlers fishing in water over 100 fathoms deep. It is presumed that the swordfish were feeding on the bottom; in one case a number of semidigested coryphaenoid fishes were found in the gut. Makaira indica Black mariin 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 mariin were not as common as black; only 1 3 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 mariin, the exceptions were fish caught in 1962. All striped mar- iin examined were taken by longline. Tetrapturus albidus White mariin 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 33 •CAPE TOWN y+HOUT BAY /FALSE BAY /// CAPE POINT '^/// ■^ MOSSEL BAY^__^^^ y^ ST SEBASTIAN BAYv,,^ .,— — — \^ 31 :a^ CAPE AGULHUS ^s^ ^ 3S S _ 18- 19' 20- 22" 23" E Figure 1. — The Cape of Good Hope. 177 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 T. pfliiegeri) ratfier 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 ajuvenile, 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 H istiophorus grainilifer from St. Sebastian Bay, to the east of Cape Agulhas, only just outside the area 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 Istiophorus. The skull is broad and heavy with a 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 178 SUMMER ( /I ^'■ \ ■• \ • • • • • • \ / • • • • • • • • • • • • • • • • • • • • • • • j • • \ T* * • • • J • • •ji • • • • \y^^,j-JLY-* • • • • • • • I • • • • • • • • • • • * ■■ * * '■ * ■* , L • / • • • 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 ceilain 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. 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 offish away from the Cape, and diffusely distributed fish then resolve into two populations, an Atlantic one and an Indo-Pacific one, although a 179 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 T. 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 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 * * \ * V * • • • • • • • • • • « • • • • ■\ / * * • • • \ / • • • # • • \ » » « fA • •• • • s • • • • • • • • • • •• • • • • • • V V**^ L «/ • • • \ y • • m \ / T • • ^^^ • • • • • • • • • • • • « SPRING ■ • • • \ M f. \ \ /: • • • • • • • • • •• \ / • • • i:-. — : • • • • Figure 3. — Distribution of W. 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). 180 SUMMER 1 • • • • • • • • f • • ^■ • • "1 )•■■•■ # • K /• • • • • • •I • • • • • # « • • • • • • • • • • 20° 30* s 20* WINTER 30*E 1 — ''~\ • • • { *y* #/• t • • • • \ y* * • • • 1 • • \ • • / • • • • \ / • • • • * • • • • • 10* 20* 30* E Figure 4, — Distribution of 7. alhidalT. aiidax around the southern tip of Africa, summer and winter. Catch rates (per 100 hooks) represented by number of dots in each 5° square (one— <0.00l, 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 close to the Cape of Good Hope certainly refer to spearfishes. In jority of fish close to land can sailfish and those offshore to be been noted above the sailfish corded from the Cape of Good the area, although the statistics almost other areas the ma- be assumed to be spearfishes. As has has never been re- 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 oi the Benguela Cuirent System (9-16°C and 34.8-35.0%o); the Agulhas Bank mixing water zone of varying composition (16-2rC 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 (I6-21°C and 35.5-35.8%o) (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° 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 suppoils 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 2rC 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 181 30' 33' 36- 39- 42' 12' E 1^ 1^ ~v: 28' 32 Figure 5.— Surface temperatures off South Africa, March 1969 ffrom 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. With 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) 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%o), 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- 182 Figure 6.— Surface temperatures and salinities off South Africa, January 1961 (from Shannon, 1966). A. Temperature. B. 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°Eanduptolat. 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''/oo 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*'/oo). The continuous low temperature and salin- ity area (15°C and 34.9%o), extending around the 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%o, and South East Atlantic Surface water, 19°C and 35.6"/o(i, can be observed. At 100 m the isopleths tend to follow the coastlme. 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 183 38 I . ' 14"E 15' itf 17 IS 19 20 21 Figure 7.— Surface temperatures and salinities off South Africa, April 1961. A. Temperature. B. Salinity. 38 t r 1 1 1 1 ■ • ■ ■ ■ 1 T ■ ' ' u'E t^' 16* 17' 18* 19 70 21 2? u'E is \€ 17' 18" 19* 20* 21* 22* Figures. — Surface temperatLues and salinities off South \li ic.i. .liiK \9h\ . A. lemperalLMe. B- S.ilinilv. upwelled component of the Benguela Cuirent sys- tem (<14°C and <35.r'/nu) 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 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 184 Figure 9. — Surface temperatures and salinities off South Afi-ica, 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''/oo) 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%o) 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 of both Atlantic and Indian Ocean forms being pres- ent, but with more chance of Atlantic species. Summer, January 1962 (Fig. lOa.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. ZTE, 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"/on) 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 185 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 at a 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. pfliiegeri, 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. li E 15° 16° 17° I ■ 19 20 21° 22° ■ E 15° 16° 17° 16° I.' ■ ■ ■ ■ I 20 21 22 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. helotw. ACKNOWLEDG MENTS 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. I LITERATURE CITED ANDREWS. W. R. H., and D. L. CRAM. I%9. Combined aerial and shipboard upwelling study in the Benguela Cunent. Nature (Lend.) 224:902-904. BANG, N. D. 1970a. Major eddies and frontal structures in the Agulhas Current retrofle.xion urea in March 1969. Proc. Symp. Oceanogr. S. Afr.. 1970. C.S.I.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. .'^2;67-7f). 1971. The southern Benguela Current region in February, 1966: Part II. 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. DECASTELNAU. M. F. 1861. Memoire surles poissons de r.Afrique Australe. Paris: Bailliere. 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 Telmptiinis from the Cape of Good Hope. Ann. Mag. Nat. Hist., Ser. I, 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 Isiiophonis. Copeia 1969:34-44. NAKAMURA. I.. T. IWAI. and K. MATSUBARA. 1968. A review of the sailfish. speartlsh. 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. PENFJITH. M.J. 1964. A marked extension of the known range ofTelrapterus angusliroslris in the Indian Ocean. Copeia 1964:231-232. 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 martins of South Africa. Nature (Lond.) 193:558-559. 1968. The tunas of the genus Thinuuis 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- em 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. 187 Catch Distribution and Related Sea Surface Temperature For Striped Marl in (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 lime-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. TO 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 rish were caught; between 68° (20.0°C) and 70° F (21. TO the catch was 1,886 fish; and a further increase to 70° F (21.10 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. TO 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 flsh. 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 Catahna 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. 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 iSarda chiliensis), yellowtail (Seriola dorsalis), and Pacific barracuda (Spliyraena 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 188 Season No fe...3...'. Day No (.4 Date .l!...*...^..-! P..T - .. Member y\ - . Non-Member Oob NtwwA^ro SeL.v< Ov « 0S.O ^oroHt^li. V Fish /TVIARl.T, Angler Address Boat Boat Captain >r. »>»'Tll!6, . ' V I*. | e w Uication J 7 ^ " » Pf r«>«»l+ W*>y»,» - !0>> 5> htt. Hooli Up Time .V.P. '...l.P....A.W.Time To Boat ,..'^.P J CWrijfc ~bvi|e. 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 offish 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. Tackle Used: 3 Thread 3/6 . . Light , Medium . Heavy Special Bait Used: D D Flying Fish . □ Live Bait . , . (^^ 5 Other D D D 1^1 \ 'ft Weigh m/s Weigli Mister 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- 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 I. — Striped marlin catch landed at the San Diego Marlin Club during half-month periods, July-November, 1963-1967 Month 1st half 2nd half Monthly total July 31 31 August 163 841 1,004 September 1,279 612 1,891 October 450 250 700 November 297 297 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' 189 woo 33°30 33°00 32°30 32°00' 34W 33»30 33°00 sy-so II8''30' I7°00 32'00 V '-] 1 \ l_0« AAinn PC I K1 h SANTA CATALINA V ^ 5 y \ ' \ N 4 \ SAN Q.EMENTE 10 7 5 1 \ DO. MAR 1 ^ 1 4 13 32 56 /la JOLLA 1 8 28 102 129 i7 SAN .OCGO 1 1 ' 1 2 8 131 123 5\ 1 1 1 68 10 143 ^■- yisLANCB 1 1 9 10 \ r\ 7 1 2 1 3 V 1 18°30 I I8°0tf 1 1 7°30' II7°00' 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 Figure 3. — Catch distribution for August 1963 through 1967. 33°00 32°00 ^ LO \ S AN<^^' ^^ } r\ 'f SANT CATAI A \ N ^ 9 ' 2 N J 7 \ SAN cum — SsJ :ntc e 20 6 12 \ DEL MAR ^ k 2 8 9 4< no 19 h .xn\ A 3 16 21 130 116 53 \ SAN OCGO ' 33 49 232 253 z> JJQCRONADOS 3 7 10 89 4«l ^ -^ISLANDS 1 6 93 6 pN 2 ' V II8°30 1 18°00 II7°30 Figure 4. — Catch distribution for September 1963 through 1967. 190 33°30 33=00 32° 30' 32°00' ^. .-^ LC N [\ \ S ANG^i f ^ ANOS 2 4 6 l\ r\ V. IIS-SO IIS-OO' II7»30' 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 71.2°F(21.8°C) 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 1%7 69.1°F(20.8°C) 354 October 1963 72.2° F (22.5°C) 73 1964 66.5°F(19.1°C) 339 1%5 65.2° F {18.4°C) 147 1966 69.0° F (20.8°C) 98 1967 67.9°F(19.9°C) 43 TCMPERATURC ("Fl Figure 6. — Distribution of striped marlin catch by sea surt'ace temperature showing the mean (.r), standard de- viation (5), 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 - 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. 191 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. Table 3. — Comparison of catch and catch rates during periods of continuous and discontinuous 68° (20.0°C) and 70° F (2 l.rC) isotherms. (20.0°C) 70°F 21, rc) 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 Av. catch/period 101.7 205.3 146.1 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. BuU. 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. 192 HOWARD, J. K., and S. UEYANAGI. 1965. Distribution and relative abundance of billfish (Is- 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. SQUIRE, J. L. JR. 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. In 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 (Paraltihnix dalhriHiis) and its fishery, 1947-1958. Calif. Dep. Fish Game, Fish. Bull. 122, 67 p. 193 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 saiinsh, Istiophorus 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 sailflsh 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 flndings that the sailfish Ls a short-lived species. Tag returns give no indication of heavy commercial fishing pressure on the stocks under study. Sailfish have been taggecJ 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 'Contribution No. 2938. Woods Hole Oceanographic Institu- tion, Woods Hole. MA 02543. -Contribution No. 1615, Rosenstiel School of Marine and At- mospheric Science, University of Miami, Miami, FL 33149. 'Woods Hole Oceanographic Institution, Woods Hole, MA (12543. ■•Dept. of Natural Resources, Cornell University, Ithaca, NY 14850. ■■■Rosenstiel 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 (WHOl), 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. 194 Four different tag designs were tried during the course of the program. These were: 1. A monei 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. B "-=^ X^^ M H WH N Figure I. — Types of tags used for saiitlsh in the Coopera- tive Game Fish Tagging Program of WHOI. The type B tag was also one of those used in the Cooperative Saiifish Tagging Program of RSMAS. PARR members marked 395 saiifish 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 saiifish since 1954 with various types of dart tags (Mather, 1963) (Fig. I). The majority of the tagging was concentrated along the southeast coast of Florida and the Florida Keys, but impor- tant numbers offish 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 saiifish 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 saiifish 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). 195 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 Gu ilf of Mexico Haiti & Caribbean Caribbean Area Delaware Florida Florida Bahamas Fla. & La Texas Virgin Is.' SE NW Program WHO! 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 5/1,023 1961 0/1 0/1 5/949 0/9 0/5 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 O/IO 9/1.162 1964 0/2 6/925 0/73 0/9 0/60 0/5 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 1%8 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 I/I 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 ' Haiti-1960-1%2, Virgin Islands 1964-1%7. ^ Through May. The releases in this area were inainly (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 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, 196 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 (339f). 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 (;V) for each area. — indicates less than {).5'f. Table 3. — Releases for sailfish in the western North Atlan- tic Ocean by years, and returns from these by months at liberty. Area Percent of Releases, by Months JaFeMa Ap MyJu Jl AuSeOcNoDe N Southeastern Florida 24 10 3 8 6 4 3 3 3 5 10 21 9.455 Northwestern Bahamas — 2 4 22 26 18 14 8 2 3 1 — 479 Northwestern GulfofMexico — 63433 25 2 1.827 North Central & Northeastern GulfofMexico 2 5 10 49 34 — 429 Virgin Islands 31 14 14 1 1 6 19 13 433 Southeastern Caribbean 8 — 1 5 9 27 18 21 10 — 438 Northwestern Caribbean 22 46 16 10 3 2 1 574 Haiti 6 5 6 17 44 22 18 Northeastern Florida & Georgia 27 60 13 15 Cape Hatteras — Delaware 1 7 41 33 16 2 80 Releases Months at Liberty 0- 1- 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 1951 112 1 1952 102 -> 1953 140 1954 402 1955 261 1 1956 201 1957 179 1 1958 81 1 1959 162 1960 1 023 2 1 1 1961 1 221 1 ■> ■y 1962 1 287 -> 1 1 5 1963 1 162 3 1 4 1 1964 1 080 ■> 2 1 1 1965 1 093 1 1 2 3 1966 1 139 5 4 4 1967 828 1 2 7 1 1968 775 3 1 1 3 1969 763 I 1 2 1970 621 1 1971 1.080 -t 1972 508 1 Unknown 1 All ^ea^^ 14 .299 23 12 28 25 2 1 2 2 1 5 7 10 9 6 9 17 13 10 5 1 2 1 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 197 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 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. Spoil Bahamas Rod and Reel 1 United States Rod and Reel 86 Venezuela Rod and Reel 2 Sport total Commercial 89 British West Indies Handline 1 Cuba Longline 4 "Criollo"' line 5 Dominican Republic Handline 1 Haiti Deepline 1 Japan Longline 1 Venezuela "Professional Fishermen" 6 Longline 1 Commercial total All Methods 20 Grand total 109 Migrations Although tag returns have produced much infor- mation on migrations (Fig. 2) and local movements 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. 198 199 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 mariins (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, blit 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 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 I, 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 200 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 Foil LaLiderdale 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 II 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 (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 809? 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 ot 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- 201 tie 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 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 tTsh 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 sailtlsh. 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 1417-0007-272, -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 202 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 ofthe participants in the RSMASand 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. LITERATURE CITED DE SYLVA, D. P. 1957. Studies on the age and growth ofthe Atlantic sailfish, Isliophonis amcricaiuis (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 E.xpert 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 ofthe distribution of white mar- lin. Makaira alhida (Poey). in the Gulf of Mexico. Bull. Mar. Sci. Gulf Caribb. 7:360-369. MATHER. F. J., III. 1963. Tags and tagging techniques for large pelagic fishes. Int. Comm. Northwest Atl. Fish.. Spec. Publ. 4:288- 293. MATHER. F.J.. III. AC. 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.. III. J.M. MASON. JR. .and H.L. CLARK. 1474. Migration of white marlin and blue marlin in the west- ern North .Atlantic Ocean — lagging results since May 1970. //; 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. NCAA Tech. Rep. NMFS SSRF-675. p. 21 1-225 . 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. 203 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. The returns are grouped by area of release, except that the large group from releases of southeastern Florida is further divided according to recapture areas. In each group, the returns are listed in order of date of recapture. Lengths and weights which were reported in inches and pounds have been converted to centimeters and kilograms. Data in parentheses are extuaated or approximate. APPENDIX TABLE 1[ Sailfish tagged off southeast Florida and the Florida Keys and recaptured in other areas. Release data Locality Estimated size Lat N Long W Length Weight Recapture data Locality Gear Flag Liberty Long W Length Weight ^9 ^9 Feb. 10 1960 (26"45' 79"55') (210) May 22, 1960 27"40' 83°45' (180) May 10. 1963 (26°45' 79°55'J C220) July 25. 1963 34°19' 76°17' 201 Apr. 13 1964 (26°32' 80°00') (210) (18.2) Aug. 2, 1964 27°28' 92°27' Nov. 20 1964 (27°04' 80°03') (220) (19.1) Dec. 4, 1964 26°54' 79°07' Jan. 28 1966 (26°45' 79°S5') May 8. 1966 23°10' 82°25' 192 Jan. 19, 1966 C26°56' 80°00i) (200) Aug. 5, 1966 (23°10' 82°25') Dec. 8, 1966 (26°45' 79°S5') (9.1) Aug. 1, 1967 29°55' 85°52' 203 RR USA RR USA LL Jap RR Bah 18.2 LL Cub 14.1 LL Cub RR USA 3.4 2.5 3.6 0.5 3.3 6.6 RA, rod and reel; LL, longline 204 APPENDIX TABLE 2: Sailfish tagged off from the release site. Release data Locality Haro — — - ' southeast Florida and the Florida Keys and recaptured less than 20 miles or an undeterminable distance Estimated size Long W Length Weight cm Hg Oct. 1, 1957 (26"32 80"00 ) Unknovm Feb. 6, 1960 (27°04 80°00 ) (200) Dec. 23, 1960 (26°45 79°55 ) (190) Apr. 3, 1962 (26°32 80°00 ) (ISO) (9.1) Mar. 1963 (26°32 80°00 Mar. 1963 C26°15 80°00 Nov. 1963 (26°13 80°03 ) (210) Sept . 27. 1963 C26°20 80°02 (18.2) Dec. 28, 1964 (26°56 80°00 ) 228 Dec. 10, 1965 (26°4S 80°00 ) (200) Nov. 27, 1965 (26°S4 80°00 ) (220) (21.8) Nov. 30, 1965 (26°15 80°00 ) (210) Dec. 1, 1965 (26°45 79°55 ) (210) (18.2) Dec. 12, 1965 C26°32 80°00 ) (190) (13.6) Dec. 28, 1966 (26°56 80°00 (18.2) Apr. 29, 1967 (26°0S 80°05 (27.2) Jan. 17, 1967 27°01 80°02 Feb. 11, 1967 (26°45 79°55 Jan. 2. 1967 (27°03 80°04 Feb. 4, 1966 (26°21 80°03 ) (200) Unknovm (26°45 79°55 Feb. 2, 1968 27°23 80°02 Dec. 8, 1967 (26°21 80°03 ) (200) Jan. 3, 1968 (26°4S 79°55 (20.4) Recapture data Locality Flag Long W Length Weight TT Oct. 1, 1957 C26°32 80°00'1 Nov. 5, 1957 (26°15 80°00') Jan. 18, 1961 (27°10 80°00') Jan. 23, 1961 (26°45 79°55') Sept 8, 1962 (26°15 80°00 ' ) Mar. 1963 (26°32 80°00') June 1963 (26°32 80°00') Nov. 28, 1963 (26°05 80°05 ' 1 June 30, 1964 f26°0S 80°05') Dec. 28, 1964 26°57 80°02' Dec. 1965 26°45 79°58' Dec. 1965 (26°32 80°00') Jan. 1966 (26°31 80°00 ' ) Nov. 1966 (26°32 80°00') Nov. 1966 (26°20 80°02') Jan. 1967 (27''lO 80°00') June 5, 1967 25°4S 80°06' Unknown Unknown Unknown Dec. 7. 1967 (26°21 80°03') Feb. 10 1968 (26°54 80°00') Feb. 18 1968 27°09 80°0J' Apr. 18 1968 26°38 80°00' Jan. 3, 1969 (26°35 80°00') RR RK (230) (21.6) RR 214 20.4 RR 188 12.5 RR 221 RR RR 216 21.8 RR 211 14.5 RR RR 211 27.2 RR 224 22.8 RR 214 24.6 RR 202 17.7 RR 173 9.1 RR 214 (21.6) RR 27.2 RR RR (210) (17) RR (210) (17) RR 208 RR 214 RR 201 15.7 RR 218 RR 221 25.4 RR USA USA USA USA USA USA USA USA USA USA USA USA USA USA USA USA USA USA USA USA USA USA USA USA USA Months at Liberty u 4 1 5 2 3 12 9 3 8 1 6 11 4 11 2 1 2 0.5 4.4 12.0 '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 Locality Estimated size Locality Flag Long W Length Weight Long W Length Weight Months at Liberty ^r TT Apr. 4, 1952 24"5r 80 36' July 16 1957 25''45' 80°06' (200) Jan. 28 1958 [26°45' 79°55') (220) Feb. 19, 1956 24°51. 80°36' (200) Mar. 2, 1961 (26°13' 80°00') (210) Mar. 16 1962 (24°38' 81°06') (170) Dec. 24 1962 (26°13' 80°03') (200) Dec. 6, 1963 (26°45' 79°55') (190) Nov. 27 1964 (26°13' 80°03') (200) Apr. 25, 1966 (24°40' 81°0S') Mar. 12, 1968 25°12' 80°14' Jan. 21 1969 (26°4S' 79°55') Nov. 15, 1968 C24°40' 81°05') (180) Oct. 26, 1969 (24°40' 81°05') (190) Oct. 12, 1969 25°33' 80°05 • Oct. 25, 1971 (24°30' 81°45') (210) (9 1) (18) (13 6) (14 5) (16) (18.2) (11.4) (18.2) (22.8) (18.2) July 12 1952 (25°45' 80"00') Sept . IS , 1958 27°10' 80°03' Jan. 14 1959 C27°10' 80°00') Feb. 12 1959 (26°28' 80°02') Jan. 19 1962 (27°27' 80°05') Dec. 15 1962 (26°32' 80°00') Feb. 22 1963 (26°45' 79°5S') Dec. 7, 1963 27°13' 80°03' Dec. 29. 1964 (26°S6' 80°00') Jan. 3, 1967 27°12' 80°05' Apr. 29, 1968 2S°53' 80°05' Jan. 24, 1969 27°28' 79°59' May 18, 1969 (26°45' 79°55') Dec. 1, 1969 (25°45' 80°00') Dec. 23, 1969 26°57' 8a°03' July 1972 (26°45' 80 00') 216 219 216 213 (180) 206 185 (230) (224) (180) 173 216 224 206 RR USA RR USA 18.2 RR USA 21.8 RR USA RR USA (12.5) RR USA 14.1 RR USA 13.6 RR USA RR USA (22.8) RR USA RR USA (13.6) RR USA RR USA 24.6 RR USA 24.1 RR USA RR USA 3.3 14.0 11.5 35.8 10.6 9.1 2.0 1.0 8.3 1.6 0.1 6.0 1.2 2.3 8.3 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 sajne area more than 20 miles southward from the release site. Release data ted size Recapture data Date Locality Estima Dat Locality Size Gear^ Flag Months at ® Liberty Ut N Long W Length Weight Ut N Long « Length Weight •Jan. 28, 1951 C27°10 80°00') cm •V Mar. 15, 1951 (26°45 79''55 cm kg RR USA 1.8 •Dec. 26, 1950 [27°10 80°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°S5 RR USA 3.1 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 80°00') 191 13.6 Feb. 20, 1956 (26°32 80°00 ) 221 22.8 RR USA 25.8 Feb. 5, 1958 (26°45 79°5S') (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°05 80°05 ) 198 15.5 RR USA 1.9 Feb. 5, 1961 (27°04 80°00') (200) Feb. 26, 1961 (26°32 80°0(r 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 3.2 Jan 29, 1961 (26°56 80°00') (210) Jan. 31, 1962 (26°05 80°05 ) 155 (15.9) RR USA 0.1 Dec. 15, 1962 C26''lS 80°00') (230) Dec. 29, 1962 (25°45 80°00 ) 218 23.8 RR USA 0.5 Jan. 20, 1962 C27°27 80°05 ' ) 198 15.9 Jan. 9, 1963 (26°45 79°55 ) 206 (13.6) RR USA 11.8 Dec. 31, 1961 C26°56 80°00') 198 (11.4) Jan. 9, 1963 (26°28 80°02 ) 198 15 KR USA 12.3 Jan. 3, 1963 (26°56 80°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 8O.°0O 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 C26°45 79°55') (230) Mar. 14, 1963 (25°45 80°00 ) 218 23.6 RR USA 2.2 May 11, 1963 (26°20 80°02 ' ) (120) (9.1) May 12, 1963 25°45 80°07 175 11.8 RR USA Jan. 10, 1963 (26°56 80°00') (150) May 17, 1963 (26°32 80°00 RR USA 4.2 Dec. 26, 1961 (26°45 79°55') (200) June 24, 1963 (2S°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 80°00') (220) Feb. 27. 1964 (26°47 80°00 RR USA 1.8 Apr. 2, 1964 (26°45 80°00') (180) Mar. 17, 1965 24°33 Sl^O? 218 RR USA 11.5 Nov. 14, 1965 UnknowT 183 13.6 Apr. 1966 (2S°4S 80°00 ) 188 15.9 RR USA 5. H8T. 2, 1966 27°05 80°05 198 July 12, 1966 24°30 81°50 200 14.5 RR USA 4.3 Nov. 11,1966 (26°54 80°00') (210) (18.2) Nov. 19, 1966 25°3B 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) C20.4) Nov. 24. 1967 t25''45 80''00 ) 228 23.2 RR USA 0.1 (Feb. 26. 1966) (26°45 79°S5') 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°05' 91 9.1 Nov. 26, 1970 24°26 81°52 6.4 RR USA 0.3 1 RR, rod and reel • Fish tagged under pro jram sponsored by RSMAS 207 APPENDIX TABLE 5: Sailfish tagged of the northwestern Bahamas. Release data Locality Estimated size Long W Length Weight ^r Recapture data Locality Long W ength Weight "^T Flag Months at Liberty Oct. 21, 1965 May 2, 1967 Mar 21, 1968 25"45' 25°25' 25°25' Aug. 28, 1968 25 45' 79"19' 77°55' 77°55' 79°19' (210) (230) (18.2) (18.9) (22.8) Mar. 17, 1966 19 45' May 4, 1968 (23°10' July 20, 1968 23°14' May 31, 1969 24°47' 77"43' 82°2S') 82°30' 80°32' 20.4 LL Cuba 4.8 20.9 LL Cuba 12.1 18 LL Cuba 4.0 18.2 RR USA 9.0 ^ RR, rod and reel; LL, longline; CL, criollo line APPENDIX TABLE 6: Sailfish tagged in the Gulf of Mexico. Release data Recapture data Locality Estimated size Long W Length Weight 'June 8, 1955 (27''35' 96°45') (210) 'Sept. 15, 1959 (27°35' 96°4S') 'July 4, 1961 t27°35' 96°4S') (210) Aug. 3, 1967 30°18' 86°36 ' 213 Oct. 7, 1967 30°07' 86°50' (210) Sept. , 12, 1968 30°05' 86°52' (200) Sept. 30, 1969 30°05' 87°00 228 July 20, 1968 27°30' 96°40' (200) >!r (17.3) Local ity Size ■ Gear' Flag Months at Liberty Ut N Long W Length Weight cm JCS Mar. 9, 19S7 C25°00' 80°30') RR USA 21.0 Aug. 14, 1961 (27°35' 96°45') (220) RR USA 23.0 Dec. 22, 1961 (26°32' 80°00') 186 17 RR USA 5.6 Oct. 17, 1967 23°16' 82°08' 198 LL Cuba 2.5 (Jan. 1968) 21°03' 75°30' CL Cuba C3.) Sept. 23, 1968 30°05' 86°53' 216 RR USA 0.4 Jan. 6, 1970 12°08' 61°49' 20.9 HL BWl 3.2 May 20, 1970 22°09' 77°40' (180) CL Cuba 22.0 ^ 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 d size Recapture data Locality Estimate Date Local ity Size Gear^ Flag Months at Liberty Lat N Long W Length Weight Ut N Long W Length Weight am kg cm kg Dec. 26. 1965 18°30' 64°45' Dec. 11 1966 18°32' 64°40' 216 18.2 RR USA 11.5 Mar. U, 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°J8' (18.2) Mar. 19 1967 I8°22' 68°35' 15.5 HL Don. R. 2.1 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 RR, rod and reel; CL, criollo line; HL handline APPENDIX TABLE 8: Sailfish tagged off Venezuela Release data Locality Recapture data Estimated size Locality Long W Length Weight June 19 1966 (10 50' 67 00') June 4, 1966 (10°50' 67°00') Apri 1 6 1966 (10°50' 67''oa ' ) Sept 4 1966 (10°50' 67°00') Aug. 6, 1966 10°46' 66°55' Aug. 2, 19-6 (10°50' 67°00') Feb. 26 1966 lO^SO' 68°0S' kT (16) (22.8) (18) Long W June 20, 1966 10 50' 67 00' July 3, 1966 (10°S0' 67°00') Aug. 7, 1966 (10°50' 67°00') Sept. 9, 1966 (10°50' 67°00') Jan. 2, 1967 10°5r 66°57' May 1968 (10°50' 67°00') Sept. 20, 1970 11°25' 67°00' Flag Length Weight ~W Months at Liberty 20' PF Venez . 20 RR Venez. 1.0 (28.2) RR Venez . 4.0 28.2 PF Venez . 0.2 LL Venez. 4.9 29.6 PF Venez. 21. 27.3 PF Venez. 54.8 RR, rod and reel; LL, Longline; PF, professional fishermen * Gutted weight 209 APPENDIX TABLE 9: Sailfish tagged off other areas. Release data Recapture data Locality Estimated size Locality Flag Months at Liberty Long W Length Weight Long W Length Weight kg HL Haiti 8.1 n.i RR USA 4.0 (13) PF Venez . 16.5 PF Venez 7.6 TT May 20, 1961 (18°3S' 72°45') (12.7) June 17, 1967 30°10' 81°00' (170) (11.4) Oct. 18, 1969 34°57' 75°19' (18.2) Apr. 28, 1971 20°35' 87°05' 214 34.1 Jan. 21, 1962 (18 35' 72 45') Oct. 16, 1967 (26°05' 80°05') Mar. 3, 1971 09°0S' 55°10' Dec. 14, 1971 10°47' 63°09' 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, Telrapturus 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 armual 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 (iulf 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. ^Dept. of Natural Resources, Cornell University, Ithaca, NY 14850. 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; Akyiiz, 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. 211 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 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 — 0/1 11 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 1 1/272 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 — 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 — 0/56 0/20 0/18 0/95 0/4 12/1,016 M972 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 0/9 135/8.630 'AH releases after 1961 were off the Virgin Islands. -Through 20 July. From May 1970 through May 1972, 2.039 white marlin and 216 blue marlin were tagged in the west- ern North Atlantic. From these and earlier re- 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 1 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 repoited, 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. WHITE MARLIN Migrations 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 212 Table 2.— Returns 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 22 46 Commercial fishery Canada 1 2 3 (Japanese and Cuba 14 5 19 modified France 1 1 longlines. Japan 13 30 43 handlines) Norway ~i 1 South Korea -} 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 southern 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. (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 offish within this area, and also of the regular seasonal return offish 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 213 1 .j^ir^ '_.-- -1 »000 F 1 a thorns ^ /^ooo/" ~ --- NSIDE OUTSIDE 40° A J UN 3 1 JUL 4 1 :^P-"«.' . AUG 2i \*t • • SEP 12 6 M*" OCT 1 1 1 Jy^ * 4 1 19 .:/i .' 3V _• /^'^ * - ii^-*tit:^ ■ ( ■' * • B 30° ~ ^^-/^i^"i-^St3 ^-■toti-sl,^ '^' \ '•' • JAN - f ,000/::- *''*'"■-, \\ ^ MAR APR f ' * - . - - ,--^ "mS^"^ .* MAY JUN JUL AUG 13 1 1 2 20° 'r ^y.-i /r ''f ' . ,;;;!;^;.^-,ij^ ,2 38 ^^1^?^' :':fj- - _ __,^'^^^,,^i^--^,_i8: _ _ — — ^ "^^^''%- r <- ^ *^ , ■'' ' • I, ' »s C OCT 1 ^^*«i« •v^f' NOV 4 DEC JAN 6 3 10° %^W^ -r - ,v;.>.-^|. •°o FEB MAR APR MAY 3 1 1 ~ ^- ■ . ■' TN-v \.o 7 1 ... . .. -..,.. .Jf. ■'TTl -*■ . . V - ^y J-- % 1. ^, 20 0° 1 / k_ ^v 1 100° 90° 80° 70° 60° 50° 40° Figure I. — 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 \. by the adjacent number. 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. -k.' CAP CSPE' HATTERAS 76° 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. 214 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 offish tagged in Area A had been about 20° farther south, in Area C, and the 21 other Au- gust recoveries offish 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. Fiji Hanamoto (pers. comm.) has informed us that an unusually large number ot'Japanese longline vessels fished in the Gulf of Mexico in the summer of 1971. 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 — 1 in January, 1 in March, 2 in May, and 2 in June. The earlier returns in the area included 1 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, 1 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, 1 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. 215 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. 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 6(X) 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), 42° 40° 38° 36° 34° llll/l' RELEASE AREAS RECAPTURES WITHIN 5 MONTHS OF RELEASE RECAPTURES >5 MONTHS OSEP OOCT OCT OCT.^^liU^ I 1 1— 76° 74° 72° 70° 68° 66° 64° 62° Figure 3.— Recaptures outside the 1,000 fathom contour and north oflat. 33°N of white marlin tagged in summer between Cape Hatteras and Cape Cod. 216 Figure 4. — Locations of releases and recaptures of white marlin tagged in the western North Atlantic Ocean south of lat. 33°N. The months and years of release and recapture are shown in that order for each return. both concluded that the white marlin of the North Atlantic and those of the South Atlantic constituted separate spawning populations. The migration from off southeastern Florida in November to north of Jamaica in April likewise bears no apparent relationship to our other results. Much more tagging in southern waters is needed to solve the complex problems of stock identification and migratory patterns of the white marlin which occur there. Growth and Life Span Reliable growth data cannot be obtained from our tagging results since the sizes offish when released are estimated, and it is even difficult to assess ine quality of the size data accompanying returned tags. Nevertheless, some general conclusions may be drawn. White marlin usually recruit to the fishery, at least in the Maryland-New Jersey area where most of the tagging was done, at sizes of about 15 kg (de Sylva and Davis, 1963). It can thus be assumed that most of the white marlin tagged were of this size, or larger. Eleven tagged white marlin have been recaptured after periods of 3-6 yr at liberty. and none of their reported weights at recapture ex- ceeded 30 kg. The maximum weight recorded for white marlin is 73 kg (International Game Fish As- sociation, 1972). It thus appears that white marlin do not grow very rapidly after recruitment into the sport fishery. Despite the increased volume of returns, which perhaps indicates increased fishing pressure, times at liberty have continued to be very long (Table 3). Eleven of the new returns were from fish which had been at liberty for more than 30 mo. The times at liberty for two of these, 55.2 and 58.7 mo, are the longest of which we have positive knowledge for any tagged istiophorid fish. A much greater time at liberty, nowever, may have been enjoyed by a white marlin which was recaptured off Montauk, Long Island, New York, in July 1959. A red plastic ring which was found on the bill of this fish was returned to us. We recently found reference to the use of such rings to mark white marlin at Ocean City. Maryland, in 1939 (Earle, 1940). We checked with various captains who were involved in this program and Captain Louis S. Parsons reported that he had used some of these rings in the seasons of 1947 and 1948. Unfortunately, the ring carried no 217 serial number by which the release data could be established with certainty. Thus the new returns strongly support the opinion of Mather et al. ( 1972) that the white marlin is much longer lived that was supposed before the work of de Sylva and Davis (1963) and our tagging results were available. It is still impossible, however, to estimate the total life span of the species. Mortality Since numerous new tag returns have been ob- tained, the indicated mortality rate and the coeffi- cient of instantaneous mortality for recaptured white marlin which had been calculated by Mather et al. (1972) from recaptures in groups A-C from releases in 1961-1965 have been calculated from re- captures in the same groups from releases in 1961-1967. The same procedures were followed (Table 3, Fig. 5). The new indicated mortality rate is 30% per year, an increase of 3% over the earlier result, with 95% confidence limits of 23% and 36%. The new coefficient of instantaneous total mortal- ity, Z, is 0.35±0. 10, as against the earlier figures of 0.32 ±0.17. The addition of the new data has not changed the indicated mortality rate significantly, but has narrowed the confidence limits (14% and Table 3. — Summary of recaptures of tagged white mariin, to 15 July 1972, by years of release and months at liberty. Numbers of returns outside of parentheses are for Groups A-C; numbers in parentheses are of Group D. Dashed lines enclose data used for mortality estimates. Number Ni tagged rec: umber Months at large Year aptured 0- 12 12- ■24 24-36 36-48 48-60 unknown 1954 4 1955 145 1 1 1956 413 1 1 1957 143 1958 41 1959 202 1960 111 1961 262 1 I 1962 387 4 2 2 1963 660 4 -) 1 1 1964 526 12(1) 6(1) "> 3 1 1965 385 6(2) 3(1) 2(1) 1 1966 508 11(3) 4(2) 3 1 1(1) 2 1967 521 6(1) 1 1(1) -) 2 1968 884 18(1) 7 5(1) 5 1 1969 1.401 20(6) 8(2) 7(3) 5(1) 1970 947 16(2) 9 7(2) 1971 1,016 12 12 '1972 65 Unknown - 6 8.629 5(1) 118(17) 5(1) Total 53(6) 30(8) 19(1) 6(1) 5 5(1) Total 3,249 45(7) 16(4) 11(2) 9 5(1) 4 (1961-67 only) 'Through 20 July. 218 Table 4. — Releases (after slash) and returns (before slash) for blue marlin tagged in the western North Atlantic Ocean by year and area of release. Oceanic Hatteras- Delaware North Atlantic SE Florida Bahamas Virgin Islands Gulf of Mexico Fla.&La. Texas Yucatan Caribbean Year NW SE Totals 1954 1955 O/I 0/6 0/7 1956 0/1 0/2 0/3 0/3 0/9 1957 0/1 0/1 1958 0/1 0/1 1959 0/1 0/1 1960 0/1 0/2 0/2 0/5 1961 0/3 0/3 1962 0/8 0/1 0/4 0/1 0/14 1963 0/62 0/3 0/21 0/2 0/2 0/90 1964 0/15 0/1 0/5 0/34 0/1 0/2 0/58 1965 0/2 O/I 0/1 0/30 0/10 0/1 0/2 0/47 1966 0/1 0/1 0/24 0/6 0/3 1/9 1/44 1967 0/1 0/29 0/8 0/5 0/1 0/44 1968 0/1 1/40 0/23 0/5 0/1 1/70 1969 0/8 0/2 1/38 0/45 1/1 0/5 2/99 1970 0/18 0/21 0/24 0/2 0/2 0/1 0/68 1971 0/37 0/30 0/44 0/3 0/1 0/115 1972 0/5 0/160 0/17 2/296 0/3 0/164 0/1 1/28 0/26 Totals 0/3 0/12 0/11 0/6 0/9 1/13 4/702 'Through 20 July. 39% in the earlier calculation). These results sup- port our belief that the returns do have biological significance. These relatively low mortality rates are further indications of the longevity of the species. They also show that released white marlin have a fair chance of continued reproduction, and of being available to fisheries for an appreciable period. BLUE MARLIN New information on migrations of blue marlin is limited to one valid return^ and one for which the release data are uncertain (Table 4, Fig. 6, Appen- dix Table 5). The valid return shows a migration from the northwestern Bahamas in February 1969, to the central Gulf of Mexico in August 1971. Simi- lar migrations have been noted in this report and by Mather et ai. (1972) for white martin, and by Mather, Tabb, Mason, and Clark (1974) for sailfish. 'Another tag from a blue marim was returned after this man- uscript was completed. This fish was released near Walkers Cay (northern tip of the Bahamas) in July 1971, and recaptured off Elbow Cay. Cay Sal Bank, Straits of Florida, in July 1972. Its weight was estimated at 68 kg when released, and it weighed 86 kg when recaptured. to i o to tt til I 0-12 12-24 24-36 36-48 48-60 MONTHS AT LIBERTY Figure 5. — Number of returns from white marlin tagged in 1961-67 in waters north of lat. 33°N, plotted by time at liberty. 219 Istiophonis phitypteriis. The data for this return support the opinion of Mather et al. (1972) that the concentrations of blue marlin in the western North Atlantic from June through October, and in the western and central South Atlantic in February, March, and April, represent separate populations. This return also gives the first available indication of the growth rate of Atlantic blue marlin. The fish's weight when released was estimated at 200 pounds (90 kg), and it weighed 163 kg (eviscerated) when recaptured after 30 mo at liberty. Since esti- mates of the weight of fish when tagged have usu- ally proved to be high, it seems probable that this fish doubled its weight in two and a half years. The other return was from a 165 pound (75 kg) blue mar- lin recaptured at Cape Hatteras, North Carolina, in August 1970. Unfortunately, the serial number on the streamer was illegible and the dart, which also carried the serial number, was not returned. To our knowledge, only 14 blue marlin in this size range or smaller had been marked prior to this recapture with the type tag returned from this fish. Six of these were released off the Viigin Islands, June- November 1969, and 8 off the northwestern Bahamas and southeastern Florida, April- December 1969. It is highly probable that the recap- tured fish was one of these, but there is also a pos- sibility that the sportsman who tagged it neglected to report the data. Tag return rates for blue marlin in recent years have been about 1%. This low rate and the small number (usually less than 100) tagged each year have made the accumulation of tag return data for this species extremely slow. Future tagging efforts would be most effective if concentrated on marking as many small individuals as possible. SUMMARY White Marlin A. Fish which summer between Cape Hatteras and Cape Cod. 1. These fish move offshore, mainly in east- erly to southerly directions, in late summer and early fall. 2. Most of these fish winter off northern South America and ^ome may remain there 40° • RELEASE O RECAPTURE LESS THAN i YEAR AT LIBERTY / MORE THAN 1 YEAR UNCERTAIN 40° Figure 6. — Locations of releases and recaptures for blue marlin tagged in the western North Atlantic Ocean. The months and years of release and recapture are shown in that Older for each return. 220 into May instead of only into February. 3. Some of these fish winter as far north as off the Carolinas. 4. These fish migrate northward in spring through the Yucatan Channel and the Straits of Florida and through the Atlantic waters off the West Indies and the Bahamas. 5. Some of them migrate northward through the Mona Passage. 6. Some of them were recaptured in the Gulf of Mexico in the spring and summer of 1971 for the first time. It is uncertain whether this represents an unusual migration, or unusu- ally heavy fishing effort. 7. Most of the white marlin in this group re- turn to the summering area repeatedly, but some do not. 8. Two fish tagged off the northwestern Bahamas in spring have followed the migra- tory pattern of this group to its summering area. B. Fish of other groups. 1. Many white marlin summer in the Gulf of Mexico and winter in the Straits of Florida or among the northwestern Bahamas. 2. Some of the fish which concentrate off Venezuela in late summer and early fall move to off the Guianas in late fall; others may merely move northward to deeper water. 3. The longest migration recorded for a white marlin was from off the northwestern Bahamas to about 600 miles east-northeast of the mouth of the Amazon, a distance of about 2,700 nautical miles. This migration has no apparent relation to the others re- corded by tag returns and is the closest ap- proach to the South Atlantic by a white mar- lin tagged in the North Atlantic. C. General. 1. The longevity of the species has been further demonstrated by record times at lib- erty for tagged fish of 55.2 and 58.7 mo. 2. A new calculation using more tag return data shows an estimated mortality rate of 30%. 3. The white marlin in the North Atlantic are separate from those of the South Atlantic. Blue Marlin 1 . A group of blue marlin may spend the warm season in the Gulf of Mexico and the cold sea- son among the northwestern Bahamas. 2. A tagged blue marlin weighing about 90 kg when released approximately doubled its weight in 30 mo at liberty. ACKNOWLEDGMENTS The authors are most grateful to all the organiza- tions and individuals who have assisted this re- search. The principal financial support of this work since 1956 has been from the National Science Founda- tion (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) (Contracts 14-17-0007-272, -547. -870, -975. and -1 1 10). 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 Tourna- ment; the Associates of the Woods Hole Oceano- graphic Institution; and many other sportsmen's or- ganizations 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. In particular, Albert C. Jones contributed the mortality estimates for white marlin. 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 acknowledgments here; the major participants are listed in the informal progress re- ports which are issued periodically by the Woods 221 Hole Oceanographic Institution. The press and the broadcasting media have also done much to en- courage tagging and the return of tags. LITERATURE CITED AKYUZ. E.F. 1970. A guide to marks used for tunas and an inventory of tuna marking projects. FAO (Food Agric. Organ. U.N.) Fish. Circ. 101, rev. 1, 119 p. de SYLVA, D.P., and W.P. DAVIS. 1963. White marlin, Tetrapturus albidiis. in the middle At- lantic bight, with observations on the hydrography of the fishing grounds. Copeia 1963:81-99. EARLE, S. 1940. The white marlin fishery of Ocean City. Maryland. U.S. Bur. Fish. Dep. Int.. Spec. Sci. Rep. 6. 15 p. INTERNATIONAL GAME FISH ASSOCIATION. 1972. World record marine fishes. I.G.F.A., Fort Lauder- dale. Florida, 20 p. LEIM. A.H., and W.B. SCOTT. 1966. Fishes of the Atlantic Coast of Canada. Fish. Res. Board Can. Bull. 155, 485 p. MATHER, F.J., 111. 1963. Tags and tagging techniques for large pelagic fishes. Int. Comm. Northwest Atl. Fish.. Spec. Publ. 4:288-293. MATHER, F.J., III. AC. JONES, and G.L. BEARDSLEY, JR. 1972. Migration and distribution of while marlin and blue marlin in the Atlantic Ocean. Fish, Bull., U.S. 70:283-298. MATHER, F.J., 111, D.C. TABB, J.M. MASON, JR., and H.L. CLARK. 1974. Results of sailfish tagging in the western North Atlan- tic Ocean. 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. Commer. NOAA Tech. Rep. NMFS SSRF-675 p. 194-210. UEVANAGI. S.. S. KIK.AWA. 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. 222 APPENDIX Release and recapture data for marllns tagged in the western North Atlantic Ocean are presented in five Appendix Tables. Data for White marlin re- captured between May, 1970, and July 15, 1972, are grouped in four tables according to release and recapture areas. Corrected data for one white marlin return listed by Mather et al_. (1972) are included. The fifth table shows all the blue marlin returns obtained to date. In each table, the returns are listed in order of date of recapture. Although anglers estimated lengths in inches and weights in pounds, we have converted them to metric units. Data in parentheses are estimated or approximate. Release data APPENDIX TABLE 1. --Group A: White marlin tagged and recaptured north of lat 33 N Recapture data Locality Estimated size Locality Long W Length Weight Long W Length Weight Months at Flag liberty July 24, July S, July 4, July 12, Sept. 9, July 3, Unknown Aug. 15, Sept. 16, Aug. 3 Aug. 10, Aug. 4, Aug. 29, July 23, Aug. 31, (Sept. 9, July 25, Unknown July 23, July 21, July 13, Aug. 29, July 26, Sept. 21. July 18, July 16, July 17, Aug. 20, Aug. 16, July 3, July 9, Sept. 4 , Sept. 17, Sept. 14, Aug. 31, Aug. 6, 1968 1969 1969 1968 1967 1969 1970 1970 1969 1968 1966 1970 1970 1969 1968) 1969 1970 1971 1971 1971 1968 1970 1970 1971 1971 1970 1969 1971 1970 1971 , 1971 , 1970 , 1969 1967 38"13' 36°15' 36°24' 38°08 ' 37''48' 38°13' (36°00' (36°20' (36°00' 37°51' 37°43' 38°03' 38°30' 38°15' (38°20' (38°10' 38°10' 38°1S' 35°43' 38°15' 37°44' 39°45' 35°46' 35°50' 38°15' 38°15' 37°50' 38''lS' 38''l2' 36°15' 38°15' 37°45' 37''43' 38°15' 37°53' 73 51 75°00 74°43 74°00 74''o8 73°51' 75°00') 7S°D6') 75°00') 74°12' 74°04' 74°52' 73°30' 73'"50' 74°30T 74°30') 74°05' 73°50 75°10 73°50 74°20 71°53 75°10 74°45 73°50 73°50 74°15 73°50 74°00 74°48 73°50 74°10 74°20 73°85 74°05 (210) (220) C210) (200) (200) (200) C200) (200) (16) (27) (25) (20) (36) (23) (18) (16) (18) (27) (23) (16) (20) (23) C23) (20) (20) (32) (25) (25) (20) (19) (23) (23) (23) (18) June 16, July 13, July 14, Aug. 5, Aug. 19, Sept. 15, Sept. 15, Sept. 15, Sept. 16, Sept. 18, Sept. 26, Oct. 25, June 19, July 10, Aug. 20, Aug. 22, Sept. 10, Sept. 14, Sept. 14, Sept. 15, Sept. IS, Sept. 19, Sept. 21, Sept. 25, Oct. 3, Oct. 4. Oct. Oct, Oct Oct Oct Oct Oct Oct June 19 June 25 1970 1970 1970 1970 1970 1970 1970 1970 1970 1970 1970 1970 1971 1971 1971 1971 1971 , 1971 , 1971 , 1971 , 1971 , 1971 , 1971 , 1971 1971 1971 1971 1971 1971 1971 , 1971 , 1971 , 1971 , 1971 , 1972 , 1972 38"50 35°47 38°02 42°46 37''48 37°40 37°29 (36°00 35°53 37°32 39°40 37°53 38°15 41°23 38°15 (38°15' 38''51 38° 00 36°05 38°15 35°52 37°00 37°10 3S°23 37°27 40°08 40°00 36°15 36''l5 37°50 35°50 36°56 34°48 37°50 3S°48 35°45 am kg 71°50' 220 (43) LL Can. 22.8 74''54' (20) RR U.S. 0.3 74°07' 220 RR U.S. 12.3 64°15' 190 (25) LL Can. 24.8 74°08' 230 27 RR U.S. 35.4 74°10' 234 39 RR U.S. 14.4 74°30' (200) (20) RR U.S. 75°00') RR U.S. 1.0 74°43' (200) (16) RR U.S. 74°30' (213) 39.8 RR U.S. 13.5 72°32' 203 20 RR U.S. 25.6 68°05' 160 14 LL Jap. 50.8 73°50' 203 25.4 RR U.S. 9.7 61°18' 19.5 LL Jap. 11.6 73°S0' 203 20.4 RR U.S. 23.7 73°S0') (220) (29.5) RR U.S. 35.5 73°14' 218 RR U.S. 25.6 70°40' 160 (22) LL Jap. 72°35' LL Jap. 13.8 74°02' RR U.S. 1.8 72°35' LL Jap. 2.1 70°30' 145 26 LL Jap. .7 75°25' 29.5 RR U.S. 37.9 74°08' 140 24" LL Jap. 12.1 74°1S' 150 27 LL Jap. 14.5 65°35' 160 (24) LL Jap. 2.6 66°00' (18) LL Jap. 2.6 73%0' 23 LL Jap. 13.6 72°15' 25 LL Jap. 25.7 70°05' 20 LL Jap. 3.2 74°20' 25 LL Jap. 15 64V' 200 25 LL Jap. .1 7S°03' 140 19* LL Jap. 1.0 70°05' 19 LL Jap. 13. S 7S°00' (2 2) RR U.S. 33.6 74°53' 203 RR U.S. 58. 7 ^ RR, rod and reel; LL, * Gutted weight longline; CL, crillo line 223 APPENDIX TABLE 2. Release data -Group B; White marlin tagged north of lat 33'^N and recaptured between ITN and lat 33 N. Recapture data Locality Lat N Long W + Sept, 17, 1967 58°15' 73°50 July 15, 1968 38°13' 73°51 Summer 1965 38°10' 74°30 Aug. 16, 1969 SS^OO' 74°11 Aug. 2, 1969 36°06' 75°05 Sept. 14, 1968 36°28' 74°50 July 5, 1968 38°15' 73°50 July 21, 1968 38°13' 73°51 Aug. 26, 1969 35°48' 75°15 July 25, 1970 38°30' 73°30 Sept. 11, 1969 38°1S' 75°00 Sept. 16, 1970 36°00' 75°00 Sept. 18, 1970 38°05' 74°03 July 26, 1969 38°15' 73°50 July 11, 1971 3eV' 73°57 Aug. 9. 1971 38°30' 73°30 July 13, 1971 38°15' 73°50 Estimated size Locality Site Length Weight Long K Length Weight May 15, 1968 (20) May 4, 1969 April 16, 1970 (20) May 7. 1970 C160) June 1, 1970 June 13, 1970 (25) Jan. 26, 1971 C20) March 26, 1971 (20) May 15, 1971 (23) June 5, 1971 (22) June 11, 1971 (180) (23) June 19, 1971 (17) Aug. 10, 1971 (20) Aug. 13, 1971 (150) (16) April 8, 1972 (23) May 28, 1972 (200) (25) May 30, 1972 28 06' 20°25' 23°14' 30°30' 2S°08' 21°38' 32°37' 2S''l6' (23°20' 25°S1' (2S°20' 26°36' 27°00' 28°10' 25°45' 18°22' 23°10' kg Months at Flag Liberty 77°16' IS LL Cuba 7.9 67°00' 150 (10) LL Jap. 9.6 82°46' CL Cuba 70°30' 195 25 LL Kor. 8.7 74°01' 18.3 LL 10 69°45' 195 20. S LL Jap. 21.0 73°59' 180 48 LL Jap. 30.8 68''47' 183.6 19.8 LL Kor. 32.2 82°20') LL Cuba 20.6 79''56' (20) RR U.S. 10.4 82°20') LL Cuba 21 95°10' LL Jap. 9.1 90°40' 16* LL Jap. 10.7 88°02' 150 LL Jap. 24.6 79°20' 185 24 RR U.S. 8.9 68''l2' 19.5 RR U.S. 9.6 e2°23' 225 32 HL Cuba 10 RR, rod and reel; LL longline; CL, crioUo line; HL, hand line * Gutted weight + Correction - previously recorded (flather et al, 1972) as recaptured (May 15, 1969) APPENDIX TABLE 3. --Group C: White marlin tagged north of lat 33 N and recaptured south of lat 18 N. Release data Recapture data Locality Estimated size Locality Flag Long W Length Weight Long W Length Weight Months at Liberty Aug. 31, 1969 36°25' 74"44' July 16, 1966 39°00' 74°10' Sept. 9, 1970 36°20' 75°00' Aug 4, 1969 36°06' 74''57' Sept. 2, 1970 (36°50' 75°00') July 3, 1971 35°48' 74°42' July 24, 1969 36°00' 75°00' Sept. 10, 1967 (38°15' 74°50') 'll, Longline % kg (14) (May 30, 1970) 12''20' 66 10' (30) Venez (20) Dec. 2, 1970 14°10' 65''44' 15 Kor. (200) (24) Dec. 20, 1970 16^48' 6S''25' 175 26.5 Jap. (17) Jan. 27, 1971 14°11' 70°04' (140) Jap. 206 (23) (Dec. 1971) (12°50' 66°00') Venez (180) (31) Jan. 7, 1972 09°03' 57°37' 28 Kor. (24) (Feb. 3, 1972) (12°00' 66°30') Venez (16) April, 1972 (11°43' 70°S1') (30) Venez (8.9) 52.6 3.4 17.8 6.2 (30.5) 55.2 224 Release data Locality Long W APPENDIX TABLE 4. --Group D: White marlin tagged south of lat 53 N, Recapture data Estimated size Length Weight Locality Lat N Long W Length Weight Flag Months at Liberty ^ ><3 Nov. 2, 1968 25 40' 80 07' July 10, 1969 29°50' 87°00' Aug, 13, 1966 10°50' 66°50' April 23 . 1969 25°43' 79°20' Sept. 11 . 1969 (10°50' 66''S5') Aug. 17, 1969 (10°50' 66''55') March 4, 1970 25°26' 78°06' Unknown (28°4a' 88°50') April 19 , 1969 2S°26' 78°06' May 16, 1970 25°26' 78°06' (210) (16) April 16, 1970 18 32' 76 53' 203 20.9 RR Jamaica 17.4 (25) June 14, 1970 23°1S' 82°08' 20 CL Cuba 11.2 (20) Aug. 8, 1970 10°50' 66°50' (25) RR Venez . 47.9 (16) Sept. 21, 1970 03°57' 40°20' 185 24 LL Jap. 17.0 Nov. 11, 1970 09°00' S9°0C' 139.5 13.5' LL Venez. 14 (28) Jan. 2, 1971 11°50' 67°00 ' 27.2 LL Venez. 16.5 (15) June 14, 1971 22°10' 94°12' 145 22.7 LL Jap. 15.4 Aug. 11, 1971 28°15' 89°05' LL Jap. (30) Sept. 19, 1971 37°00' 70°30' 148 27 LL Jap. 29.0 (36) Sept. 20, 1971 37°54' 73°32' 140 18 LL Jap. 16.2 RR, rod and reel; LL, longline; CL, crioUo line; * Gutted weight Release data Long W APPENDIX TABLE 5. --Blue marlin. Estimated size Length Weight Recapture data Local ity Size Lat N Long W Length Weight Flag Months at Liberty Aug. 20, 1966 (10 50' 66 55') Aug. 14. 1968 (25°20' 77°S8') June 26, 1969 29''40'N 8a°30' Unknown (19°00' 65°00') or (26°00' 79°00') Feb. 13, 1969 25°25' 78°05' (165) (270) (83) Oct. 27. 1968 10 35' 67 05 (23) Dec. 22. 1968 24°45' 77°40 (91) Nov. 27, 1969 29°22' 93°26 Aug. 29, 1970 35''20' 75°3S 91 Aug. 13. 1971 26°30' 91°00 •v 98 RR Venez. 26.2 45.5 RR U.S. 4.3 97 ST U.S. 4 75 RR U.S. Jap. RR, rod and reel; LL, longline; ST, shrimp trawl, * Gutted weight 225 Migration Patterns of Istiophoridae in the Pacific Ocean as Determined by Cooperative Tagging Programs JAMES L. SQUIRE, JR.' ABSTRACT Since 1954, billtish have been tagged by cooperative marine game fish tagging programs in many of the major sportfishing areas of the Pacific. Major locations of tagging have been off southern Cahfornia, U.S.A., Baja California Sur and mainland Mexico, Panama, and Australia. Two cooperative marine game fish tagging programs have operated in the Pacific, 1) the Cooperative Marine Game Fish Tagging Program, sponsored jointly by the Woods Hole Oceanographic Institution and the National Oceanic and Atmospheric Administration, National Marine Fisheries Service, and 2) a cooperative program conducted by the California Department of Fish and Game. During 1954-1971, 15,540 billt'ish were tagged. Records show 9,849 striped marlin (Telraplurus audax), 4,821 sailfish (Istiophorus platypterusi, 622 black marlin (Makaira indica). and 248 blue marlin (Makaira nigricans) were tagged during this period. Ninety-seven tag recoveries have been made; these include 85 striped marlin, 10 sailfish, and 2 black marlin. Eighty-one percent of these recoveries were by longline fishing vessels, the remainder by marine sport fishermen. The tag recovery rates were 0.88'7r for striped marlin, 0.32% for black marlin, and 0.24% for sailfish. Four types of tags were used in the two programs. Two types of metal tip dart tags were used by the Woods Hole Oceanographic Institution; metal tipped single- and double-barbed plastic dart tags were used by the National Marine Fisheries Service; and a single-barb plastic dart tag was used by the California Department of Fish and Game. Tag types giving the best recovery rate for striped marlin and sailfish were the plastic single- and double-barbed dart tags. Recovery data for striped marlin tagged in the eastern Pacific show a movement away from the tip of Baja California in a south to southwest direction in late spring and early summer. Some recoveries were made of fish tagged near the lip of Baja California and recaptured northwest of the tip of Baja California, Mexico. The migration pattern to the south and southwest at this time of the year may be related to spawning. Striped marlin tagged off southern California show a migration to the south in late summer and early fall. Recoveries of striped marlin in the eastern Pacific were generally short-term (average of 89 days) and covered short distances, averaging 281 nautical miles. Only three of 85 tagged striped marlin, and one of two tagged black marlin, were recovered 1,000 nautical miles or more from the site of tagging. The few recoveries of tagged black marlin (2) and sailfish (10) did not provide sufficient data to determine migration patterns for these species. The tagging or marking of fish is an established Ocean was in 1954 when tagging equipment was method in the study of fish growth, migration, dis- furnished by Mather to anglers fishing for billfishes tribution and population structure (Schaefer, Chat- and tunas. Interest in the tagging and releasing of win, and Broadhead, 1961; Beckett, 1970). The billfishes in the Pacific increased and in 1961 ar- conceptof utilizing the services of marine anglers in rangements were made with Mather for the then the tagging of large marine game fishes, such as U.S. Fish and Wildlife Service's Tiburon Marine tunas and billfishes, was developed by Frank J. Laboratory to assume responsibility for the Mather III of the Woods Hole Oceanographic In- cooperative Marine Game Fish Tagging Program in stitution. Woods Hole, Massachusetts. The first the Pacific area. This program has recently been cooperative tagging of billfishes in the Pacific transferred to the Department of Commerce, Na- tional Marine Fisheries Service, Southwest 'NCAA. National Marine Fisheries Service, Southwest Fisheries Center, La JoUa Laboratory, La Jolla, Fisheries Center. La Jolla.c A 92037. California. The Pacific phase of the Cooperative 226 Game Fish Tagging Program was assisted by the International Game Fish Association and the De- partment of Fisheries, Mexico. The State of California, Department of Fish and Game also participated in a cooperative tagging program for billfishes (striped marlin and sailfish) from 1965 through 1970 with the assistance of ang- lers representing the Oceanic Research Institute, San Diego, California. The importance of the istiophorid billfishes, such as striped marlin (Tetrapturus audax) and sailfish {Istiophonis platyptenis) in the eastern Pacific, blue marlin fM«Afl/ra nigricans) about the Hawaiian Islands (Strasburg, 1969). and black marlin (Mcikdira indica) off Queensland, Australia and throughout the Pacific, as species on which valu- able sport fisheries are based upon, is well known. In addition to an extensive sportfishery. these species also assist in supporting an extensive com- mercial longline fishery throughout the subtropical and tropical Pacific. The cooperative billfish tagging programs in the Pacific were developed to obtain an adequate un- derstanding of the migratory patterns of billfishes so that ultimately the stocks can be properly managed. The migratory patterns of billfishes in the Pacific are little known. These fishes are caught in quantity primarily with hook and line, either by longlining or by rod and reel. Use of the more efficient longline gear from a research vessel for the purpose of tag- ging and releasing of billfishes would be costly, and in excess of any funds now available for billfish migration studies. The aid of the marine game fish angler was requested and to date the cooperative tagging programs have accounted for nearly all the billfishes tagged in the Pacific. BaylifF reported tagging of billfishes by research agencies such as the National Marine Fisheries Service, Honolulu Laboratory and the Kanagawa Prefectural Fisheries Research Station in Japan. In 1968 the Honolulu Laboratory tagged 44 striped marlin, 1 blue marlin, and 10 shortbill spearfish. The Japanese Research Station reported tagging 33 striped marlin, 3 blue marlin, and 73 broadbill swordfish (Xiphias gladius). No returns were re- ported from any of these taggings. By furnishing tagging equipment to marine game fish anglers who have an interest in the rational conservation of the billfish resources, substantial -Bayliff, William H.. et al. 1972. Second interim report of the Working Party on Tuna and Billfish Tagging in the Pacific and Indian Oceans. FAO. unpublished. numbers of billfishes can be tagged in areas of in- tensive sportfishing for a relatively modest cost. Marine game fishermen have been encouraged to tag and release billfishes through information in the form of written requests, talks before billfishing clubs, posters, and brochures. In addition, posters requesting both sport and commercial fisheries to return tags and advising of a reward are distributed in both the Spanish and Japanese languages. The major geographical locations of cooperative tagging have been about the tip of Baja California, Mexico; Mazatlan, Mexico; and Cairns, Australia. Other locations where lesser numbers of tagged fish have been released are off southern California and the Hawaiian Islands, U.S.A.: Manzanillo and Acapuico, Mexico; Pifias Bay, Panama; Salinas, Ecuador; Tahiti; and New Zealand. MATERIALS AND METHODS The large size and active nature of billfishes re- quire a tag that can be applied while the fish remains in the water. Dart tags were selected because they could be used effectively by billfish anglers inex- perienced in tagging fish. All tagging, with the ex- ception of a few striped marlin and swordfish, have been on hook and line caught fish. Some surface- swimming billfishes have been free-tagged by har- pooning with a dart tag. Four types of tags were used by the cooperative programs. The California Department of Fish and Game used the single nylon barb tag with yellow polyvinylchloride tubing bearing the legend, type FT-1 (Fig. lA). The National Marine Fisheries Service's cooperative program used four types of dart tags: (i) In 1963 a number of type "C"" tags (Fig. IC) were issued. These tags had a stainless steel tip with yellow polyvinyl tubing for the legend and were similar to the type of tags used by the Woods Hole Oceanographic Institution program in the late 1950"s and early 1960's. (ii) The FT-1 (Fig. 1 A) with a slightly enlarged base on the dart head to prevent the tagging applicator tube from shearing the barb when pressure is applied to insert the tag into the billfish. This tag was recommended for tag- ging sailfish. (iii) A larger double barbed nylon tag FM-67 (Fig. IB) with yellow polyvinyl tubing for information was used from 1963 to 1971. (iv) In mid- 1971, the stainless steel dart tag, type "H" (Fig. ID) was introduced. This tag has a nylon, monofilament line extending from the stainless steel barb with a yellow polyvinyl tubing sleeve over the 227 ^ A Figure 1. — Types of dart tags used by the cooperative tagging programs. monofilament for printed information. All tags used by the National Marine Fisheries Service and the California Department of Fish and Game were manufactured by the Floy Tag Manufacturing Company, Seattle, Washington.^ On all the tags, a serial number and a message are heat-embossed in black. The legend gives an address for return, to- gether with a notice that a reward will be given. In the early years of the cooperative program the Woods Hole Oceanographic program used the type "C" tags (Fig. IC) in the Pacific. In later years tags of an "H" type were used (Fig. ID). Upon bringing the billfish close to the boat the angler was instructed to insert the tag beside the dorsal fin, just posterior of the first dorsal ray, and at an angle so the tubing points in the general direc- tion of the tail. This was done to provide a stream- lining effect of the water flow over the tubing. After insertion, the leader was to be cut, thereby releas- ing the fish and leaving the hook and a portion of the leader attached. If necessary, it was recommended that the billfish be towed forward slowly before re- cuse of a trade name does not imply endorsement by the Na- tional Marine Fisheries Service. lease to provide an additional supply of oxygen to assist in reviving the fish. Tags were attached to a postcard having the se- rial number of the tag. After tagging the angler was requested to complete the information on tagging date, location, species, estimate of weight, tagger's name and address, and return it to the organization issuing the tag. TAGGING RESULTS In the early 1960's, the Japanese longline fleet began fishing near the coasts of North, Central, and South America. The advent of this fishery has pro- vided an invaluable source of billfish tag recoveries. Prior to 1963. a good source of recovery for billfish tags had not existed in the eastern Pacific. Cooperating marine game fish anglers have tagged 15,540 billfishes in the Pacific since 1954. Woods Hole Oceanographic Institution records for the period 1954 through 1971, show 3,618 tagged billfish releases (Mather. 1972). The Na- tional Marine Fisheries Service program resulted in the tagging and release of 10,964 billfishes. The distribution of tagging effort for the 14.582 billfish tagged by the Woods Hole Oceanographic Institution/National Marine Fisheries Service Cooperative Marine Game Fish Tagging Program included 8,953 striped marlin, 248 blue marlin, 622 black marlin, and 4,759 sailfish. The State of California Department of Fish and Game con- ducted a cooperative tagging program with selected billfish anglers and this program functioned during the period 1965-1970. Of a total of 958 billfishes tagged, 896 were striped marlin and 62 sailfish. A total of 9,849 striped marlin, 622 black marlin, 248 blue marlin, and 4,821 sailfish was tagged by the cooperative programs. The totals and numbers of the four species of billfishes tagged per year and the number of recoveries (for each year's tagging) are listed by tagging organization in Table 1 . Recoveries Between 1954 and 1963. no returns were reported in the Pacific for the 945 billfishes tagged and re- leased. From 1963 through 1971 a total of 97 tagged billfishes was recaptured. Foreign longliners re- corded 79 recoveries or 81% of the total. One of these was by a Taiwanese longliner; the others were recovered by Japanese longliners. Marine game fishermen have accounted for 18 recoveries or 19% 228 Table 1. — Billfishes tagged and recaptured in the Pacific by cooperative marine game fish tagging programs. Species Striped Black Blue Year Organization marlin marlin marlin Sailfish Totals Species Striped Black Blue Year Organization marlin marlin marlin Sailfish Totals 1954 Ai — — — 0/3 0/3 1955 A, — — — 0/9 0/9 1956 A, — — — — — 1957 A, 0/17 — — 0/35 0/52 1958 A, 0/13 — — 0/8 0/21 1959 A, 0/10 — — 0/124 0/134 1960 A, 0/2 — — 0/104 0/106 1961 A 0/87 0/8 — 0/188 0/283 1962 A, 0/76 0/4 — 0/257 0/337 1963 A, 1/942 0/37 0/30 0/266 0/1,275 A2 0/532 0/1 0/18 0/26 0/577 B 0/18 — — — 0/18 1964 A, 1/113 0/36 0/12 0/241 1/402 A2 4/281 — 0/3 0/268 4/552 B 4/329 — — 0/7 4/336 1965 A, 1/52 0/26 0/4 0/233 1/315 A2 6/431 0/6 0/7 2/167 8/611 B 0/253 — — 0/18 0/271 1966 1967 1968 1969 1970 1971 Ai 0/9 — 0/12 0/12 0/33 A2 2/1.401 1/235 0/73 0/409 3/2.118 Also 1 shortbill spearfish (Telraplurus angustiroslris) tagged B _____ A, 0/47 0/19 0/1 0/124 0/191 A2 10/735 — — 2/283 12/1,018 B 2/186 — — 0/31 2/217 A, 0/31 0/27 0/62 0/120 A2 19/1.279 0/3 0/23 1/480 20/1.785 B 0/107 — — 0/1 0/108 A, 1/29 0/31 0/98 1/158 A2 a 13/1.119 0/13 0/32 2/432 15/1.596 Ai 0/5 0/36 0/78 0/119 A2 4/747 1/39 0/31 0/318 5/1.135 B 1/1 — — — 1/1 Ai 0/6 0/19 0/2 0/33 0/60 A2 16/989 0/82 — 2/501 18/1,572 B 0/2 — — 1/5 1/7 Totals 85/9.849 2/622 0/24810/4.821 97/15.540 NOTE: Releases (right of slash), returns (left of slash) by organization conducting the tagging. Returns are listed by year of recapture forWHOI. NMFS and CF&G lists recapture by year of tagging. A. Cooperative Marine Game Fish Tagging Program. Ai Woods Hole Oceanographic Institution, from 1954. A2 National Marine Fisheries Service, from 1963. B. California Department of Fish and Game. of the total. The FM-67 and FT-1 tags are buoyant and a number of these have been returned after being picked up on the beach after being used to tag a billfish. These tags may have been lost overboard during the tagging process or may have been shed after tagging. Recoveries were considered valid only when the tag was taken from a recently caught fish. The Cooperative Marine Game Fish Tagging program (National Marine Fisheries Service — Pacific) issued a conservation certificate to both the tagger and recoverer. A cash reward was paid to the tag recoverer by all three programs. Table 2 gives the percentage rate of recovery by program, by year, and total recovery rate for each species and for all billfish tagged. Table 3 gives a summation of the rate of return for each of the three cooperative tagging programs. Tag Performance For the four types of tags used by the cooperative programs (FT-1, FM-67, C. and H) a comparison of tag performance can be made for the types FT-1 used by the California Department of Fish and Game, and the National Marine Fisheries Service and the Woods Hole Oceanographic Institution. Recovery data for 10,777 tags used by the Na- tional Marine Fisheries Service Cooperative Tag- ging program and 958 tags used by the California 229 Department of Fish and Game to tag striped mar- lin, black marlin, and sailfish were analyzed for the Table 2. — Rate of recovery of tagged billfishes. Species 1 Overall % Striped Black Blue recovery Year O rganization marlin marlin marlin Sailfish rate 1963 Ai 0.11% 0.00% 0.00%. 0.00% 0.08% A2 0.00 0.00 0.00 0.00 0.00 B 0.00 — Annual Overall 0.00 0.05% 1964 A, 0.88 0.00 0.00 0.00 0.25 A. 1.42 — 0.(K) 0.00 0.72 B 1.21 — — 0.00 .'\nnual Overall 1.20 0.70% 1965 A, 1.92 0.00 0.00 0.00 0.32 A2 1.40 0.00 0.00 1.20 1.31 B 0.00 — — 0.00 Annual Overall 0.00 0.75% 1966 A, 0.00 0.00 0.00 0.00 0.00 Al. 1.40 — — 0.71 1.08 B 1.07 — — 0.00 Annual Overall 0.92 0.91% 1967 A, 0.00 0.00 — 0.00 0.00 A2 1.50 0.00 0.00 0.21 1.12 B 0.00 — — 0.00 Annual Overall 0.00 0.99% 1968 A, 3.44 0.00 — 0.00 0.63 A2 B 1.16 0.00 0.00 0.46 0.94 Annual Overall 0.91% 1969 A, 0.00 0.00 — 0.00 0.00 A2 0.53 2.56 0.00 0.00 0.35 B 100.00 — Annual Overall 100.00 0.40% 1970 A, 0.00 0.00 0.00 0.00 0.00 A2 1.62 0.00 — 0.40 1.15 B 0.00 — — 20.00 Annual Overall 14.28 1.16% 1971 A, 0.00 — 0.00 0.00 0.00 A2 0.14 0.43 0.00 0.00 0.14 B — — Annual Overall 0.13% Totals 1954-71 0.86% 0.32% . 0.00% 0.21% 0.62% 1963-71 0.88% 0.32% : 0.00% 0.24% 0.66% Ai = Cooperative Marine Game Fish Tagging. Woods Hole Oceanographic Institution. A2 = Cooperative Marine Game Fish Tagging, National Marine Fisheries Service. B = Cooperative Billfish Tagging. California Department of Fish and Game. — = no billfish tagged. 1954 through 1962 no recoveries reported. purpose of giving some indication of tag perfor- mance. Eighty-two percent of the billfishes were tagged with FM-67 tags, 13.8% with FT-1 tags, 3.4% with the "H" tags, and 0.8% with the "C" tag. There were no recoveries of the "C" tag, and the "H" tag has been used only since mid-1971. The percentage recovery rate by tag type and tag- ging organization is listed in Table 4. Hooking mortality undoubtedly accounts for a high tag loss, in addition to unknown losses that occur through tag shedding. The percentage of tag loss for the several types of tags is not known. MIGRATORY PATTERNS Eastern Pacific Figures 2, 3, 4, and 5 show the tagging and recov- ery points by quarters for both striped marlin and sailfish in the eastern Pacific. The recovery data from the longline fleet have not been adjusted for fishing effort in the various geographical areas. The commercial longline fishery has expanded to the limits of the fishery in the eastern Pacific and the seasonal distribution of fishing effort is assumed to Table 3. — Rate of recovery (left figure refers to number of tag recoveries; right figure refers to number of fish tagged and released). Year Striped Black Blue marlin marlin marlin Sailfish Total Program ,\, — Woods Hole Oceanographic Institution 1954-1971 4/1,439 0/243 0/61 0/1,875 4/3,618 = 0.28% = — % = — % = — % = 0.11% Since 1963 4/1.234 0/231 0/61 0/1,147 4/2.673 = 0.32% = — % = — % = — % = 0.15% Program A2 — National Marine Fisheries Service 1963-1971 74/7,514 2/379 0/187 9/2,884 85/10,964 = 0.98% = 0.53% = — % = 0.31% = 0.78% Program B — California Department of Fish and Game 1963-1970 7/896 —/— = 0.78% = — % 1/62 8/958 -% = 1.6% = 0.84% Rales of recovery for striped marlin and sailfish combined. 1963-1971: Program A, 4/2,673 = 0.15% As 85/10,964 = 0.78% B 8/958 = 0.84% 230 Table 4. — Percentage recovery rates for tag types used by the California Department of Fish and Game (CF&G), and National Marine Fisheries Service (NMFS), fish tagged through 1971. Species Agency Type tag % recovery Striped marlin NMFS FM67 1.06% NMFS FT-1 0.42 CF&G FT-1 0.80 NMFS H 0.40 Black marlin NMFS FM67 0.32% NMFS H 1.20 SaUfish NMFS FM67 0.30% NMFS FT-1 0.60 CF&G FT-1 1.60 >0.66% >0.86% be located in areas of greatest concentration and maximum yield. January, February, March. — During this period striped marlin are commonly taken by the sport- fishery off Mazatlan, Mexico, and in lesser num- bers off Cabo San Lucas, the southern tip of Baja California Sur, Mexico. Sailfish are not common in the area about the mouth of the Gulf of California during the winter and early spring. The longest dis- tance recovery of a striped marlin was for a fish tagged near the tip of Baja California Sur, Mexico, and recovered 200 nautical miles southwest of the Hawaiian Islands, a distance of 3,120 nautical miles in a period of 3 mo (2/67-5/67). Recoveries of striped marlin tagged off Mazatlan, Mexico, show a west to southwest movement towards the tip of Baja California Sur, and the Revillagigedo Islands, Mex- ico, respectively. Recoveries of striped marlin tag- ged about the tip of Baja California Sur, Mexico, show some movement toward the northwest and northeast; however the direction of the movement as indicated by tag recoveries from this area is south through southeast (reference. Fig. 2). April, May, June. — During late spring and early summer the sportfishery striped marlin catch de- creases off Mazatlan and increases about the tip of Baja California Sur, Mexico. Sailfish becomes the dominant species off Mazatlan during this season. A pattern of striped marlin movement, indicated by recoveries, is from about the tip of Baja California southward toward Las Tres Marias and Revil- lagigedo Islands, Mexico. Striped marlin tagged Revilla Gigedo Is. Clarion I. Socofro PACIFIC OCEAN II5» 110° 105° 100° Figure 2.— Movements of billfishes from tagging conducted during the months of January, February, and March. Striped marlin unless otherwise noted as SF (sailfish) 231 Figure 3. — Movements of striped marliri from tagging conducted during the months of April. May. and June. Figure 4.— Movements of billfishes from tagging conducted during the months of July, August, and September. Striped marlin unless otherwise noted as SF (sailfish). 232 Figure 5. — Movements ofbillfishes from taggmg conducted during the months of October, November, and December. Striped marlin unless otherwise noted as SF (sailfish). along the east side of the tip of Baja California have shown some movement about the tip to the west and noilhwest. The longest southward migration of any tagged striped marlin was recorded during this period; the marlin' s total straight line migration was 1,153 nautical miles from near the tip of Baja California to near Clipperton Island in 71 days (re- ference. Fig. 3). July, August, September. — A reduction in tag- ging effort due to fewer sportfishermen traveling to the tip of Baja California and the west coast of Mex- ico during the warm season is reflected in the num- bers ofbillfishes tagged and later recovered. Short distance sailfish recoveries were made near Mazatlan. A sailfish, tagged during this period off Mazatlan, was recovered northwest of the tip of Baja California, a distance of 250 nautical miles, after 457 days. This sailfish recovery was the greatest in distance and time (reference. Fig. 4). Striped marlin fishing becomes productive off southern California in late August and two re- coveries were made off the southern west coast of Baja California of striped marlin tagged off southern California in September. One recovery was made of a striped marlin tagged off Guaymas, Mexico, which is located on the east coast in the upper Gulf of California, and recaptured south of the tip of Baja California 17 days later. October, November, December. — This is a period of reduced tagging throughout all eastern Pacific sportfishing areas. A limited amount of tag- ging off southern California has yielded returns, one being the second longest return recorded, 2,090 nautical miles to the southwest in 179 days. Three recoveries of striped marlin tagged off southern California were recovered northwest of the tip of Baja California 1 to 4 months later (reference. Fig. 5). As in any conventional tagging or marking pro- gram only two points in the migration are known — the location of tagging and the tag recovery point. The geographical migratory course of the billfish between these two points is unknown. Southwestern Pacific Through the cooperation of anglers fishing for black marlin near Cairns, Queensland, Australia, recoveries of two tagged black marlin have been recorded (Fig. 6). One was recovered by a Japanese 233 10° I0< 20< 30° J 140° 150° 160° 170° 180° o 80 doys AUSTRALIA 0° 10° ■ 20° I- 30° 140° 150° 160° 170° 180° Figure 6. — Movements of black marlin tagged off Queensland, Australia. longliner 364 days after tagging about 90 nautical miles north from the point of tagging near Hope Reef, Queensland, Australia. The second was re- covered 180 days after tagging by a Taiwanese long- liner 1,440 nautical miles northeast of the tagging site at Escape Reef, Queensland, Australia. MIGRATION RATES AND TIMES The speed of migration of striped marlin, ex- pressed in nautical miles per day projected on a straight line/time basis, varies considerably be- tween local and distant water recoveries (Fig. 7). For billfishes tagged off the Baja California/ Mazatlan area the average time at liberty was 94 days. An average distance of 176 nautical miles traveled equals 1.9 nautical miles per day. Striped marlin tagged off southern California recovered near the tip of Baja California had an average re- lease time of 52 days and a migration rate of 12.3 nautical miles per day. Other long distance migra- tion rates are as follows; southern California to southwest of the Hawaiian Islands, 26.0 nautical Figure 7. — General migration patterns of striped marlin tagged off southern California and Mexico. 234 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 1 13, 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 ot tne 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 the total tags used by the National Marine Fisheries Service program during 1971. The recovery rate from FM-67 and FT-1 tags 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 (Tetraptunis alhidus) 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- em 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 ^Wise.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.). 235 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, 1.229f 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 Lahoratorv. P.O. Box 98, Tiburon. CA 94920. 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. CoHma, Mexico. 236 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, Acapuico, 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 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 billHsh. 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. //; 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. 309-33 1 . 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:ll.'5-162. MATHER. F.J.. III. 1972. Cooperative Game Fish Tagging Program. Summary of results, prepared for NOA.VNMFS 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. 237 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, htiophorus 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 ui 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 longhne 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 hfe 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: Istiophorus platypterus, sailfish; Tetrapturus angustirostris, shortbill spearfish; T. audax, striped marlin; Makaira nigricans, blue marlin; and M. indica, black marlin. The Xiphiidae 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 'Southwest Fisheries Center, National Marine Fisheries Ser- vice, NOAA, Honolulu. HI 96812. (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 238 < o O X 6 7 8 9 10 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 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 1- 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 239 around Hawaii, in equatorial waters along long. I45°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 1-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 1-m ofwater 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 resuhs 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 Gear Type of tow Number Blue tows marlin Short- bill spear- fish Sail- fish Damaged un- Sword- identi- fish fied Total Per- cent 1-m plankton 30-min. surface 1.320 142 68 2 16 22 250 73.1 net 1-m plankton 30-min. 40- 200m 2.850 25 14 4 7 50 14.6 net oblique Cobb pelagic 6-h. 20-lOOm 92 18 18 5.3 trawl horizontal 1 X 2 m 30-min. surface 17 24 24 7.0 neuston net Totals Percent 4,279 209 82 2 20 29 342 100.0 61.1 24.0 0.6 5.8 8.5 100.0 240 Table 2. — Catch rates (catch per 100 tows) ofbillfish larvae in I -m plankton net and 1- x 2-m neuston net. Species Short- bill Blue marlln spearfish Sailfish No. of tows .-Ml species including Swordfish unidentified larvae Type of tow Day Night Day Night Day Night Day Night Day Night Day Night Surface Oblique Neuston 201 1.119 50.0 3.7 14.8 3.5 1.0 0.0 2.0 1.1 74.2 8.9 1.280 1.570 0.7 1.0 0.4 0.5 0.0 0.0 0.2 0.1 1.5 2.1 15 160.0 — 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 I-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 I-m net. The higher catch rate of the neuston net thus suggests that bill- fish larvae could be concentrated not only in the upper 1-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 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 Marlln 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 occuired 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 241 - r ' «r ■ i I" QUARTER IDCC -FEB) . • * . \ • h t\ • f^ [^ . . ii:. H bi ,^ ••P :..:* |t^ ^ ^ » '."■^ ~i^- :'.. ■-^c. "^ >. ;■ • ■cr mr «■ »■ ^ ~ 1 2" OUWTER IMNt-WTI ' . \ K ^ ^ h ^ — ' ~Vn, i^^ r^ .; " ^ . r: • •■\^. . ^ ., ■r- r' : : — «<-c - ' . ' ' ■ j 3> QUARTER „ •s^ px. V -x. . \ h p • « ...a. ■'*••," ■ ^ •• • i' •s??. • m-c ^ • * : ;== .!;_ ; : " ■n r- : ' " " T- 4'" QUARTER i " \ ^ r\ r\ • ^ -^ -~> 1 OyN [>. -. • k : V ^^ ^ h • * \ ■' - - ^ • ""..: :.••"■"" ■arc . •r- M » *' ' .: °v -.. J ■:. i ^.^ : ' ^ L_^ :dl. 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 \\° 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. 242 by the discontinuous north-south distribution of lar- vae in the western Pacific, compared with the con- tinuous distribution across the equator of blue marhn 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 TC 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; Nakamuraet 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. • s s; = —■ ., . 1 1" QUARTER • \ . ; A C\ .: * • ■ • ^ \ , ^^ ^ D- ., '--«:-'; riu! rn^ ^ ^ ^ ' V" -.-i-* :^k;.. r — :: "^ • •> : • L_ Lli_: -4p^ ^^ ■^ ^ 1. • ? — S [ ( Z" OUAHTEB I' : : 1 • ::" ~\ . L V • * ■^^ k-l: )^. •■ ":?f :: S ^ „. ••• '■ i— I, - ' , f • ■ " _ . n .: ; S« (MMRTER K \. :i - v Sv. N ■--. \ ^ r-. - *""!" %; • i^-t: — ' ^ ^ _^ t= _; _; 1_ _ _ j_j ■ '^^ ^~~ — *~~ \ r\ A k\ ■^"^ ^ r->, ^ \ • ^ \ '• ::.•? -.^ ::>l; • • Vi \^f *re a I^^SS .^.^ ■JL. lii L_ 7^ id ^».'e ^=a IJ- 243 1954; Yabe, 1951 ; and Yabe et a!., 1959). The sword- fish larvae are easily recognized by their long snouts and heavily pigmented elongate bodies. They have a 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 Table 3. — Summary of young swordfish (Xiphias gladius) taken in plankton net tows in the Atlantic and Pacific Oceans. .■r C an- JO- .«■ «- HCP ■>D- .».- -- *.' ^ ir io- a- • act A r ■ i 1 't* c ^ VIA 4 )l : V \ > 1 1 \. .' us M ' Rl ^1 _ -^V _ 1 1 4 ' L n t II "^ " _, •• },^'JZ n * ]" u/tAi ■ * » h' 'i^ -'Z'm^ iXt U L- .. ... 'M^.. J 1 :TT-J^A — . 1 ; — , 1 o' , « ■ \ 1 r ■*' r K -II " 1 "t 1 i . T \zr 1 ) » vinru J ' 1 ■^-.^ E- KU — E i 3 N k L ^ r r-=. r- ^ s- ,— .T-.- s- No. of larvae No. of juveniles Source' <10 mm 10-80 mm Total Yabe (1951) 1 1 Arata (1954) 4 19 23 Yabe et al. (1959) 5 15 20 Sun Tsi-Gen (1960) 17 17 Honolulu Laboratory 14 6 20 Total 23 58 81 Percent 28.4 71.6 100 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.) •Taning (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 1 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 244 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(I955). 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 offish 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 -Conversion of weight (lb) to estimated length (cm) through courtesy of R.A. Skillman. Honolulu Laboratory. 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 iiUidhis 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. UEYANAGL 1965. Distribution and relative abundance of billfishes {Is- lioplioridae) 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. In 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. 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. 245 ROYCE, W.F. 1957. Observations on the spearfishes of the central Pacific. U.S. Fish Wildl. Serv.. Fish. Bull. 57:497-5.M. SUN.T.G. I960. 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. Makiiiia initsiikiirii (Jordan et Snyder). [In Jap., Engl, summ.] Rep. Nankai Reg. Fish. Res. Lab. 11:130-146. 1962. On the larvae of the shortnosed spearfish. Telrapturus angiistirostris 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. 1964. Description and distribution of larvae of five is- tiophorid species in the Indo-Pacific. In Mar. Biol. Assoc. India. Proc. Symp. Scombroid Fish.. Part 1:499-528. UEYANAGl, S.. and H. YABE 1959. Larva of the black marlin I 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. YABE. H. 1951. Larvae of the swordfish. Xiphias gUuliiis. [In Jap., Engl, summ.] Jap. J. Ichthyol. 1:260-263. 1953. On the larvae of sailfish, l.siiophonis orienlalis collected in the South-western Sea of Japan. Contrib. Nankai Reg. Fish. Res. Lab. 6:1-10. YABE. H.. S. UEYANAGl. S. KIKAWA. and H. WATANABE. 1959. Study on the life-history of the sword-fish. Xiphias glailiiis Linnaeus. [In Jap.. Engl, summ.] Rep. Nankai Reg. Fish. Res. Lab. 10:107-150. 246 —• r^ an ir> -C — ■ — (N ■ u-> r-1 O t CO O r^ 1^ O O . 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I 11(11 ilill lliir I t ^ <3 \D nD'.D^iCN CMIIIt II iiJUJUJUJtjJ 33:t]33 33333 33333 3333UJ iij3uJUJU [JLtl I -J CM •£> fo O U-» U-i vD -3- -J- O O 00 00 >£) ^ sO 00 C 00 m CO — O -• — O ^ o^ CM ^^ cr^ o m o — ■ r-ifn I ^o '-< CO c 1 -J ^ -a- f 'a^o^J^CO OCMCin iTiiOi-^-^-j' r^-^CT^c-t( ^Hf^tMr^-- (NCMr-J(M-^ -^-^(MfMCM -^^^tMCM — ,• CT'-j'sDco^ a^o^r--■r^o^ a^CT*^o >C -J ^ -^ CM ^ UUOOC! 'OUOuiVl o o o o o o o o o o r- 4) 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 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. 256 35 Current Directions Seasonal — ^ / K/ -15" ti^.' 460° 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 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 257 catches in February. It is possible that more inten- sive sampling from July to September would show this time to be equally productive, since Tuning (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"/i)(i 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"/iHi. At all other larval stations, the salinity was 35.46"/ijij or more. Thus, while the lower salinity limit remains indef- inite, it must be around 35.5"/(i(i. 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 P/2 to 2-m ring net towed in the upper 30 m. Rivers (1966) reports 1 13 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. 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 Vi-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 1 19 swordfish larvae from 6.5 to 1 10.6 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"/oi) 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. •258 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 i^Uuliii.s Linnaeus, from the South Atlantic coast of the United States and the Gulf of Mexico. Bull. Mar. Sci. Gulf Caribb, 4:183-243. ARNOLD, EL, JR. 195.5. Notes on the capture of young sailfish and swordfish in the Gulf of Maine. Copeia 1955:1.50-151. BARTLETT, M.R.. and R.L. HAEDRICH. 1968. Neuston nets and South Atlantic larval blue marlin (Mcikaira nigricunsl. 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 [Xi/ihias filaJiiis Linne (Pisces, Xiphilidae)]. Probl. Ichthyol. 9:375-387. KONDRITSKAYA. S.L 1970. The larvae of the swordfish [Xiphias fjliiJiiis (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. LA MONTE, F., and D.E. MARCY. 1941. Swordfish, sailfish. marlin, and spearfish. Ichthyol. Contrib. Int. Game Fish Assoc. 1(2): 1-24. LEE, RE. 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. Vova e larve di Xiphias tiUiditis 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 (.V(/>/»(;.v). Pap. Mar. Biol. Oceanogr. Deep Sea Res., suppl. to vol. 3:438-4.s0. TIBBO, S.N.. and L.M. LAUZIER. 1969. On the origin and distribution of larval swordfish Xiphias i>hiJiiis 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. APPENDIX: SWORDFISH DESCRIPTIONS OF (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 Manne Fisheries Service, NOAA. 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- 259 32.5 mm- 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. -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 rmich 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 . min 9 . 5 mm 16. 5 mm .:^^^^^^^ ^> . j^j^: 32 . 5 mm 62 . 5 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 UEYANAGF ABSTRACT The distribution of larval swordflsh, 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. No *0 -L >■ 10 z 3 r'o 10 40 60 K) 100 iotai length 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 caughl x 100 Total number of simultaneous tows on which larvae were caught Subsurface Number of subsurface tows on which larvae were caught x 100 Total number of simultaneous tows on which larvae were caught Far Seas Fisheries Research Laboratory. Shimizu, Japan. As seen in Figure 2, the density of larvae was greater at the surface both during the day and night. 261 PERCENTAGE OF OCCURRENCE 20 40 60 80 100 % s 1 y/////////////////////A Sb 1 1 / D : 43 N Vn: A1) V//////////////A 1 1 DAY V///A 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 suiface and subsurface catches was quite marked during the day but not as much during the night. This difference probably represents diumal vertical movements among larval swordfish. GEOGRAPHICAL DISTRIBUTION The occurrence of larvae was plotted by unit areas of 1° squares (Fig. 3). Also included in the 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. (Ail 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 occuiTence in the western Pacific was at lat. 3rN, 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. ]0°S in the central 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 sampUng 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- em Pacific. If it is true that 24°C is the limiting temperature, then it also follows that if there is any u z o 50 JAN.-MAR. 50 APR.-JUN. ■ (62) 50 JUL- SEP. (17) 50 " ■ OCT.- DEC. B (71) 1 11 21 31 41 51 71 91 101 131 151 5 15 25 35 45 60 80 TOTAL LENGTH 100 110 mm 140 160 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-laUtude, 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. 263 LITERATURE CITED ueyanagi. s. 1969. Observations on the distribution of tuna larvae in the Indo-Pacific Ocean with emphasis on the delineation of GORBUNOVA, N. N. the spawning areas of albacore, Thunnus ulahingci. (In 1969. Breeding grounds and food of the larvae of the Jap.. Engl, summ.) Bull. Far Seas Fish. Res. Lab. swordfish (Xipliitis gladiiis Linne (Pisces, Xiphilidae)). (Shimizu) 2:177-256. Probl. Ichthyol. 9:375-387. YABE, H., S. UEYANAGI. S. KIKAWA, and H. tAning. a. v. watanabe. 1955. On the breeding areas of the swordfish (Xiphicts). 1959. Study on the life-history of the sword-fish. Xiphias Pap. Mar. Biol. Oceanogr.. Deep Sea Res., suppl. to vol. gladiiis Linnaeus. (In Jap.. Engl, summ.) Rep. Nankai 3:438-450. Reg. Fish. Res. Lab. 10:107-150. 264 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 V2 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 TlVi 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 cmlongand 1.8 cm in diameter (Fig. la). Itproduces a 50 kHz carrier signal with a pulse rate that is a function of the surrounding water temperature. Es- timation of depth offish 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. 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 2Vi m pole (Fig. Ic) 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 oi 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 ' NOAA, National Marine Fisheries Service, Southwest Fisheries Center, Honolulu Laboratory, Honolulu, HI 96812. ' Reference to trade names in this publication does not imply endorsement of commercial products by the National Marine Fisheries Service. 265 ANCHOR PLATE RUBBER BAND 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 inseiled 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. As a result several fishermen offered to donate their mar- lins. Upon receiving radio communication that a fisherman was willing to donate a hooked marlin, Cliristel 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 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 266 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 4 h to obtain temperature-depth profiles. These profiles and the temperature-dependent pulse rates of the tags enabled estimation of swimming depth of the marl in. RESULTS Five blue marlin were tagged and tracked, one on 14-15 July 1971 and four between 25 and 28 July 1972. Dates, size offish, 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 a northerly direction. North of Keahole Point there is only one instance where the Table I. — Data on blue marlin tagged. Marlin Estimated Duration No. weight Date tagged tracked Remarks kg (lb) h 1 270 (600) 7/14/71 22!^ Lost — equipment failure. 2 225 (500) 7/25/72 1 Lost — no movement. 3 135 (300) 7/25/72 SVi Lost — tactical error. 4 160 (350) 7/27/72 V/i Abandoned — no movement. 5 70(150) 7/28/72 8 Abandoned — no movement after 2 h. Figure 2. — Path of blue marlin tracked in 1971. Numbers along track denote hour of day. Figure 3. — Path of two blue marlin tracked in 1972. Num- bers along track denote hour of day. 267 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 (# I ). estimated at 270 kg (600 lb), 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 lb) remained at depths between II 5 and 185 m throughout the SVi 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 ( # I ) 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 lengthysec. 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 Maximum Average Marlin body- body- body- No. km/h knots length/sec km/h kno'is lengthy'sec km/h knots length/ sec 1 1.1 0.6 0.09 8.2 4.4 0.62 3.0 1.6 0.23 3 0.9 0.5 0.09 3.1 1.7 0.32 -> T 1.2 0.23 5 1.5 0.8 0.19 5.4 2.9 0.68 3.4 1.9 0.45 268 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 (Tetraplurus 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 (Eulhvnnus 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 ^NOAA. National Marine Fisheries Service, Southeast Fisheries Center, Miami, FL (present duty station, Panama City Laboratory. Panama City, FL 32401). 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 269 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 t'lsh is raised, that is, a billfish comes up to a 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 70 o / < / ---.-.■■: to / - o o (VJ . u. ■ '■ o x o / V «• / rrJ^^~^ /^ - — . .i.- - J ( J m (j> a> ul ' < m o a UJ u. o I o oo : 00 a> - col . /■' ir> IT) lO in lO / l[ «i m o . a UJ u. o I o in / I \ A \ * ■i « * ^ «»• - «!• T 1 c\ V- < ■■■■■.■. V ■o ■ ,* ■■.°c ■■ ■ O ". — 'o t\J ^ I <■ m o Q Ul ■ O, u. ,o O 1 I 3 a ca u O c u C4 B 2 o H 3 180' 271 He. LlnM TJMbMA F1j1l1o< Tlao i StJU-t_ Angl« r DAILT BOAT LOO End Streat or P.O. City Zip Cod* Bait l^x^atlon Water color Along ftp, sargaBsum I Ina, in open water, etc. Weight Len^tth Olrth Tine ToUl Bill tip (upper jaw) to fork Lower Jaw to Cork SpacUs EUlaed Bookad Boated Released Sax Keiurlu - 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 ( raise s- 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, IVi 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. 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 macidatus), 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 272 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- em 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 1 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. Table 2. — Billfishes raised (R). hooked (H), and boated (B, includes releases) off northwest Florida, 1971. Uniden- tified Species Blue M; irlin White Marlin Sailfish Billflsh Event R H B R H B R H B R H Apr. 1 1 May 13 9 6 6 -) 2 "* June 32 15 8 18 9 4 4 3 T July 60 31 9 40 17 6 12 7 3 Aug, 68 25 9 86 27 8 32 23 16 5 Sept. 26 12 1 11 4 -> 1 Oct. 4 1 5 T t 1 Total 203 93 34 167 62 18 52 35 21 7 2 %of Raised 45.8 16.7 37.1 10.8 I 67.3 40.4 28.6 %of Hooked 36.6 29.0 60.0 Uniden- tified Species Blue Marlin White Marlin Sailfish BUIfish Event R H B R H B R H B R H May 2 "> 1 4 3 1 2 2 1 June 51 37 18 52 29 13 38 16 11 1 1 July 52 32 8 289 167 104 114 68 49 10 2 Aug. 79 44 23 212 126 84 194 123 81 15 1 Sept. 42 18 2 40 27 20 362 197 123 2 Oct. 63 36 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 273 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 Port Pensacola Destin Panama City All Three Ports Number caught Blue marlin 57 42 72 25 19 34 Number caught White marlin 151 113 95 38 -)T 18 Blue marlin 17 43 5 65 Sailfish 42 46 30 12 20 21 White marlin 41 195 30 266 Total hours fished — 2,339 5,801 4.139 2,603 3,217 Sailfish 18 265 14 297 Catch-per-hour Total hours fished 1,834 5,425 631 7,890 Blue marlin — 0.018 0.012 0.006 0.007 0.01 1 Catch-per-hour White marlin — 0.048 0.016 0.009 0.008 0,006 Blue marlin 0.009 0.008 0.008 0.008 Sailfish — 0.020 0.005 0.003 0.008 0.007 White marlin Sailfish 0.022 0.010 0.036 0.049 0.048 0.022 0.034 0.038 (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 is, hours-to-raise-l-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 (1 1.6 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 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. Area South Pass Northwest 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 9.8 274 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) ( 1 1 .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 51.7 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 offish 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 54.9 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) 275 Hsid I 3Siv« 01 synoH 8 lO ID K^^^t^^ R^^^y:!:^^^y^\\^^^;^v^ tt^V^V^ ^ i::r::'i-::-::\ 1^^ "^s ty:^;^^^^^^^^^^ b;^!^ r-'-r ■'■'> fi^iiifimiii ^ R^yj^^^^^^ ^^^^ ^^^ ^^^^^ "^ ty""v.'1 ^M— ~ R^ E R^^^y:^^^^^!^ ^ ^E^ o -^^S r "^ m^ -^m JS2 "E "^^ d lisWVVVVV^ l^\^ ""^ I CO , o b ^^^^^^ K^^y^^ z Z _J -I s tn 3 UJ Li. 4 (D * (/> SDEJ 3oo s t 5 o o o o o o o o lO o m o o m in o o N — , o c 3 o o o- o o o o o UnOH U3d OaSIVH HSId dO U38wnN ■o Q: r- r- C 1 c« ^ ■Xi ro ^ in a. f\j j= "^[^ o CD 3 on - O r- => =2 7 *^ — 'j-i •a o o ^ lU Q. rO >, CD CM .:^ OJ r- u C\J :S CNJ >, - > Xi O -1 CJ 3 ^ -> IX) o o o o> c "3 -a c 3 r I.. X) a U3 Z .- 3 > If) ■^ .-3 CTl U et 3 00 276 .200 150 .100 c o X F. 050 :; .000 I .200 o o: .150 UJ m S z> z .100 .050 .000 -1 1 1 1 1 1 1 r SOUTH PASS i 06 ' 07 ' 08 ' 09 10 I J 2 ' 13 ' 14 ' 15 ^ 16 17 ■ 18 — \ 1 1 1 1 1 — PENSACOLA, DESTIN, PANAMA CITY y 0=BLUE MARLIN □ = WHITE MARLIN |g=SAILFISH ^ a. 06 07 ' 08 ' 09 ' 10 II 12 13 TIME OF DAY 14 ' 15 ' 16 ^ 17 ' IB 5.0 6.7 10.0 20.0 111 m 5.0 o: 6.7 O 10.0 20.0 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). Area South Pass NW Florida Year 1967 1968 1969 1970 1971 1971 Blue marlin 1:5.6 (5:28) 1:7.7 1:4.8 1:8.0 (6:46) (4:19) (2:16) 1:3.3 (7:23) 1:3.1 (12:37) White marlin 1:2.3 1:3.9 1:6.2 1:4.0 1:4.0 1:4.3 (20:46) (15:59) (4:25) (4:16) (3:12) (28:120) Sailfish 1:2.0 1:3.6 1:8.0 1:1.4 1:2.4 1:2.5 (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 Figure 5. — Relative abundance of billfishes by time of day. South Pass and northwest Florida combined, 1971. 277 o o d Al ■ cn (J) d o d en d o o o o o o d d C3 a. 3 O 1/5 T3 .g 0) u. !5 C3 3 J2 c ■a c 3 XI (S 3 on 278 o o o' ■ m d o in d en d o q d o o o d d 3 .5 1^ 0. 3 o o 3 3 e e >. x> V) S 1 u u B cd •a e 3 ca ja b: I NO u 3 279 VJ v> 'I'l'lrl'l'l*. CS Q. ^ x: rO 3 o ' C/5 O O u: o •T3 O L. u Q. o Ja! o 13 23 28 34 28 13 TT 12 12 4 White marlin 1 8 13 31 26 11 28 ->t 7 1 3 1 Sailfish 1 2 4 5 14 4 12 4 2 1 Unidentified billfish 1 T 2 1 AU billfish 1 4 24 42 66 75 43 53 48 21 13 8 1 Hours trolled 5.00 94.50 282.50 384.25 418.75 434.25 425.25 400.50 341.75 253.75 126.00 52.75 10.00 Table 10. — Numbers of bUlfishes raised and hours trolled by time of day, northwest Florida, 1971. Time of day 0600- 0659 0700- 0759 0800- 0859 0900- 0959 1000- 1100- 1200- 1300- 1059 1159 1259 1359 1400- 1459 1500- 1559 1600- 1659 1700- 1759 1800- 1859 Blue marlin White marlin Sailfish Unidentified billfish All billfish 1 1 1 4 7 16 4 1 28 13 30 51 3 97 31 75 108 3 217 48 60 37 39 125 124 104 82 176 132 84 72 5 5 5 6 354 321 230 199 34 72 117 3 226 12 18 50 3 83 429.25 1 6 7 1 15 111.75 1 1 -> 40.75 1 1 ■) Hours trolled 49.75 140.50 587.50 1,069.75 1,143.00 1.150.75 1.128.00 1,074.50 953.50 11.25 281 CNJ CVJ . z —> 1 • a> z 1 z) \ a UJ , U- X f "r 1 sl f-- (J o UJ \L ■^ :"' O .-■ i ^ 7s o m O o o o g :0 9 o o I 4 CD o CI o UJ u. 0^ I a "r OD < CO . Q CD CO I V d K ■';. r^ |- : - I "r ij to UJ u. to o (0 I K < r s .-a in ill in u. in o in I "f 4 '- ■ ,1 u. o I :A < : a '■■i rO .1 a c <\^\ ^M < 03 ki-l ; u. r A^ \ -. m O ■UJ o .s ■ It :S 5 I 00 z . 3 -5 1 ■ (M >- < ) X a V J " mm a c vm CO o CO x? ^^/i < X r r to < cc i to u. (0 to X > /I in 'J < < .^ in in o in I < I ^ : 1" o I a "r 'M ^ < .1 8' .v, I 1 = m Of-- Q - wl (5, U- X o 2 5 X c\ o o d Al ■ O) UJ 6 o in d a> m d O o d o o o d n Figure 7. — Relative abundance of all billfishes by ten-minute squares for biweekly periods, northwest Florida, 1971. 282 d < 1 6 1 4 / o ^ < (D o ^„ CD O CD IV 'wji < ffi u o ^1 :-;v:-:-:y 1 - IV < ( «> If^ mm 1 V-% 4 ii m u XV i ' ^\i < 4 ^^fe-.dtfE \ * :::%W; iia 1- s 2? bl \ 3 _■ ^ ^ - a Iv < ml Ui u. ft, 1 = 1 • UJ c Z ro 6 ■ < 1 (^ -J ^ ^^JTa cc ft c\ C3 ftl UJ ■■ u. ■■'5J ftJ r CD = W / = ,■ 'i- / - m G s ■ g <2 (J) ffi 01 01 I < '' CD CD >s I 1 < ffi lii t :.„-^ ^ . ■ Ui u. to I 1 s It ' :i 1 in in I- 4 /"i ■ ■--., I 1 4 fO .::i -■.,.„:.;:« fO UJ 10 m X fti ( 1 '3 2 ^Jr/ to] :W> ■ ^ I e ro ■iu lii rf) 10 . . . x CD R ftJ < ftJ ♦, c fVJ u. 8: ftj ftl X •4, •UI >*■ ,0 .0 I PJ o o d Al ■ en (T> d I o «n pO d rO d o o d o o o o n Figure 7. — Relative abundance of all billfishes by ten-minute squares for biweekly periods, northwest Florida, 1971. — continued. 283 1- • o O 0- / ■ CO y' <3 ^JTA CD (J EI2 ro u. X /o / < m u o UJ u. o ■ ■■I O o o o o o O o o o I < 00 o .1 0^ li- 0> CD < 1 . ; ©I CD ■ GO CD O (D I 1-/1 < CD o 1^ li. - I- H ID < •1 ,1 i^i Q UJ to o I- I < if ^'^^^^^1 m I- A1\ 5 .■;;:?' ^ ::ii < fO -...If > o 1 - CM 1- o - o ) / < ^ CD u o ■ cn X CO I CD < CD CD CO oc ■ < CD ^ I Sj ID < to Ul u. I ■ \V- in < iiii 11 If) in Li. IT) O in I 4 < 1 f I < CD ^1 o I CO CM CD - UJ (\J 8: cvj OJ X L CD Of _ n - UJ ,'o X o o d Al ■ cr> en 6 o »n rO d d d o d o o o d D Figure 7.— Relative abundance of all billfishes by ten-minute squares for biweekly periods, northwest Florida, 1971. — continued. 284 Table 11. — Relative abundance of billfishes by water color for South Pass, northwest Florida, and the two areas combined, 1971. (BM=blue marlin, WM=white marlin, SF=sailfish). Water color Blue Water Blue-Green Water Green Water Species BM WM SF BM WM SF BM WM SF South Pass No. of fish raised 72 62 10 80 69 26 36 23 13 No. of hours trolled 877.1 877.1 877.1 1,185.4 1,185.4 1,185.4 653.7 653.7 653.7 Fish raised per hour 0.082 0.071 0.01 1 0.067 0.058 0.022 0.055 0.035 0.020 Hrs. to raise 1 fish 12.2 14.1 90.1 14.9 17.2 45.5 18.2 28.6 50.0 Northwest Florida No. of fish raised 230 489 593 21 58 118 7 6 14 No. of hours trolled 4,554.9 4,554.9 4.554.9 886.5 886.5 886.5 312.5 312.5 312.5 Fish raised per hour 0.050 0.107 0.130 0.024 0.065 0.133 0.022 0.019 0.045 Hrs. to raise 1 fish 20.0 9.3 7.7 41.7 15.4 7.5 45.5 52.6 22.2 Both areas No. of fish raised 302 551 603 101 127 144 43 29 27 No. of hours trolled 5,432.0 5,432.0 5,432.0 2,071.9 2,071.9 2,071.9 966.2 966.2 966.2 Fish raised per hour 0.056 O.IOI 0.111 0.049 0.061 0.070 0.045 0.030 0.028 Hrs. to raise 1 fish 17.9 9.9 9.0 20.4 16.4 14.3 22.2 33.3 35.7 could not be determined from the logs. Therefore, since we could not determine the number of fish raised per hour of trolling, we decided to use the percentage of the total number of fish raised as a measure of relative abundance. The data are pre- sented in Table 12. As the percentages show, the most productive surface condition off South Pass was along lines or rips. Nearly half of each species was raised along lines or rips. Off northwest Florida, open water was the most productive surface condition, the percent- ages ranging from 52% to 67%. Open water was second best off South Pass, while scattered grass was second best off northwest Florida. In the scat- tered grass, grass patches, and others categories, the percentages for blue marlin and white marlin were about equal. Sailfish were twice as abundant along scattered grass off northwest Florida area than off South Pass. When the data for the two areas were combined, open water appeared as the best condition, scat- tered grass second, and lines or rips third. Table 12. — Surface conditions and billfishing off South Pass, northwest Florida, and the two areas combined, 1971. (BM = blue marlin, WM= white marlin, SF = saiirish). Surface condition Open Water Lines or Rips Scattered Grass Grass Patches Others Total No. Raised Species BM WM SF BM WM SF BM WM SF BM WM SF BM WM SF BM WM SF South Pass No. of fish raised Percent of total no. raised 27% 30% 29% 46% 45% 48% 19% 20% 21% 3% 4% 2% 5% 1% — — — 51 45 14 87 67 23 36 30 10 1 189 150 48 Northwest Florida No. of fish raised 168 436 406 20 68 31 65 125 322 7 6 17 6 15 6 Percent of total no. raised 63% 67% 52% 8% 11% 4% 24% 19% 41% 3% 1% 2% 2% 2% 1% 266 650 782 Both areas No. of fish raised 219 481 420 107 135 54 101 155 332 13 12 18 15 17 6 455 800 830 Percent of total no. raised 48% 60% 51% 24% 17% 6% 22% 19% 40% 3% 2% 2% 3% 2% 1% — — — 285 EFFECT OF MOON PHASE Dates of the moon phases were obtained from the 1971 Nautical Almanac. Because the beginning of each quarter phase did not occur at the same hour (for example, new moon in one month would begin at 2255 h and in the next month at 0949 h), data for a 3-day period for each moon phase were compiled, namely, data for the day before, day of, and day after the beginning of each moon phase. For exam- ple, new moon for July began at 0915 h on the 22nd; data for the new moon period for July were ob- tained for the 21st, 22nd, and 23rd. The data for all species were combined, as data for each species were sparse. For the period May through October, the data for South Pass and northwest Florida are presented in Table 13. Full moon appeared to be the best period for South Pass, whereas new moon appeared to be the best for northwest Florida. When the data for the two areas were combined, no particular moon phase appeared to be especially favorable. EFFECT OF BOAT SIZE AND TYPE OF SCREW For this study, boats were categorized into 10-ft lengths, that is, 10-19 ft long. 20-29 ft long, and so on. Then the numbers of hours fished by boats in each category and the numbers of billfish raised by these boats were compiled. Then the average and the reciprocal, the hours-to-raise-one-billfish, were computed for each boat-length category. Preliminary examination of some data obtained at tournaments in Pensacola and South Pass seemed to indicate that larger boats were more successful. When the South Pass data for the entire year were analyzed, the results still indicated that this was so. As shown in Table 14, the raises-per-hour increased with boat size, and conversely, the hours-to-raise- one-billfish decreased with boat size. However, when the data for the three Florida ports were combined, as shown in Table 14, the results were not so clear. Results from combining the data for South Pass and the Florida areas did not allow us to conclude that larger boats were more successful. When the data in Table 14 were broken down by species, no trends were evident. We could not con- clude that boat size had any effect on success in raising fish. Another aspect we examined was the effect of single and twin screws of a boat. For this analysis, the only set of data providing sufficient information was that for the 40-49 ft boats in Destin. The results showed that 40-49 ft boats with twin screws were more successful than 40-49 ft boats with single screw for each species of billfish. The data are summarized in Table 15. More data are needed to corroborate these results, especially with boats of different sizes. BAIT PREFERENCE The number of hours fished with the various kinds of bait could not be determined with our data. Table 13. — Relative abundance of billfishes by moon phase off South Pass, northwest Florida, and the two areas combined, 1971. Moon phase New Moon First Quarter Full Moon Last Quarter South Pass No. hrs. trolled 721.3 99.2 742.9 113.5 No. billfish raised 77 16 153 7 Fish raised per hour 0.107 0.161 0.206 0.062 Hrs. to raise 1 fish 9.3 6.2 4.9 16.1 Northwest Florida No. hrs. trolled 842.6 809.8 620.4 738.0 No. billfish raised 312 212 135 183 Fish raised per hour 0.370 0.262 0.218 0.248 Hrs. to raise 1 fish 2.7 3.8 4.6 4.0 Both areas combined No. hrs. trolled 1,563.9 909.0 1,363.3 851.5 No. billfish raised 389 228 288 190 Fish raised per hour 0.249 0.251 0.211 0.223 Hrs. to raise 1 fish 4.0 4.0 4.7 4.5 286 Table 14.— Relative abundance of billfishes by boat size for South Pass, north- west Florida, and the two areas combined, 1971. Boat length (ft)' 10'-19' 20'-29' 30'-39' 40'-49' 50'-59' 60'-69' South Pass Hours trolled 20.0 No. billflsh raised 1 Fish raised per hour 0.050 Hrs. to raise 1 fish 20.0 296.1 1,046.2 862.2 26 142 127 0.088 0.136 11.4 7.3 0.147 6.8 68.5 14 0.204 4.9 Northwest Florida Hours trolled 42.1 695.3 1,092.8 4,142.5 1,163.8 60.0 No. billfish raised 3 130 182 1,049 278 4 Fish raised per hour 0.071 0.187 0.167 0.253 0.239 0.067 Hrs to raise 1 fish 14.1 5.3 6.0 4.0 4.2 14.9 Both areas Hours trolled 62.1 991.4 2.139.0 5,004.7 1,163.8 128.5 No. billfish raised 4 156 324 1,176 278 18 Fish raised per hour 0.064 0.157 0,152 0.235 0.239 0.140 Hrs. to raise 1 fish 15.6 6.4 6.6 4.3 4.2 7.1 'Meters = ftxO.3048. We were able to determine the days during which various baits were used. Therefore, the only mea- sure of effort we could use was the number of days Table 15. — Comparison of billfishes raised between boats 40'-49' long with single screw and with twin screws, Des- tin, 1971. Type of screw Hours trolled Blue marlin No. raised No. raised per hour Hrs. to raise 1 fish White marlin No. raised No. raised per hour Hrs. to raise 1 fish Sailfish No. raised No. raised per hour Hrs. to raise 1 fish AUbiUfish' No. raised No. raised per hour Hrs. to raise 1 fish Single 686.5 19 0.028 35.7 36 0.052 19.2 96 0.140 7.1 151 0.220 4.5 Twin 2,965.3 108 0.036 27.8 267 0.090 11.1 436 0.147 6.8 821 0.277 3.6 'Includes unidentified billfish. each bait was used. Since the bait to which a billfish was raised was seldom recorded, and since a billfish will often raise to one bait and then go over to another, we decided that the bait the billfish took would be the best data to use for a study of bait preference. Therefore, for this analysis, our unit of measure for bait preference was the number of fish hooked per day with each bait. The results of our analysis are presented in Table 16. Various natural and artificial baits were fished but only the three most frequently used, mullet (Mugil cephalus),ba\lyhoo(Hemiramphus sp.), and bonito {Euthynnus alleteratus) strip, provided sufficient data for analysis. Under the category of "others" are included a wide variety which were used very infrequently and sporadically such as dusters, jigs, spoons, Kona heads, pork rind, ladyfish, strip dolphin, Spanish mackerel, croaker, cigar minnow, squid, needlefish, etc. Because mullet is such a favored bait in the South Pass area, data for ballyhoo and bonito strip are sparse. Although the numbers of billfishes hooked per day using "other" baits are very similar to the rates using mullet as bait, conclusions regarding bait preference can not be made owing to the large assortment of baits lumped together in the "others" category. 287 In the northwest Florida area, the three types of baits were used frequently enough to permit con- clusions. Blue marlin preferred mullet over bal- lyhoo and bonito strip as indicated by the respective hook rates (0.138. 0.090, and 0.080). The three types of baits were about equally effective for hook- ing white marlin (0.290, 0.278, 0.279). But sailfish very decidedly preferred bonito strip over mullet and ballyhoo (0.532 versus 0.226 and 0.228). When the data for the two areas were combined, as shown at the bottom of Table 16, the results reinforced the conclusions reached for the north- west Florida area. CONCLUSIONS To summarize our study for 1971, the following results and conclusions were obtained: 1. A total of 701 billfishes was caught by sportfishermen in offshore waters of the northeastern Gulf of Me.xico during 1971. Of the total, 99 were blue marlin, 284 were white marlin, and 318 were sailfish. To catch these, 11,107 hours of fishing were spent by the anglers. 2. During the same 11.107 hours, 492 blue marlin, 849 white marlin, and 860 sailfish, and 39 unidentified billfish were raised. 3. Off northwest Florida, white marlin were most abundant in July, sailfish were most abundant during the latter half of Sep- tember, while blue marlin did not have an especially abundant period. Off South Pass, the variability of relative abundance from week to week was greater, making de- terminations of periods of abundance very uncertain. 4. Blue marlin were more abundant off South Pass than off northwest Florida. White marlin and sailfish were more abundant off northwest Florida. 5. Hours of greatest relative abundance for all billfishes were between 1000 and 1200 h and again between 1300 and 1500 h. 6. The bluer the water, the greater the relative abundance of billfishes. 7. Off South Pass, billfishes were most abun- dant along tide lines and rips, whereas off northwest Florida, they were most abun- dant in open water. 8. Effect of moon phase on billfishing was not significant. Table 16. — Bait preference of billfishes for South Pass, northwest Florida, and the two areas combined, 1971. Bonito Bait Mullet Ballyhoo Strip Others South Pass No. of days bait used 330 25 3 47 Blue marlin No. hooked 74 1 11 No. hooked per day 0.224 0.040 — 0.234 White marlin No. hooked 44 5 1 6 No. hooked per day 0.133 0.200 0.333 0.128 Sailfish No. hooked 24 4 3 No. hooked per day 0.073 0.160 — 0.064 Northwest Florida No. of days bait used Blue marlin No. hooked No. hooked per day White marlin No. hooked No. hooked per day Sailfish No. hooked No. hooked per day 465 421 376 231 64 38 30 26 0.138 0.090 0.080 0.113 135 117 105 46 0.290 0.278 0.279 0.199 105 96 200 40 0.226 0.228 0.532 0.173 Both areas No. of days bait used Blue marlin No. hooked No. hooked per day White marlin No. hooked No. hooked per day Sailfish No. hooked No. hooked per day 795 138 0.174 179 0.225 129 0.162 446 39 0.087 122 0.274 100 0.224 379 30 0.079 106 0.280 200 0.528 278 37 0.133 52 0.187 43 0.155 9. Effect of lengths of boats on billfishing was not significant. 10. Boats 40 to 49 ft long raised more billfisnes if they had twin screws than single screw. 11. Off northwest Florida, blue marlin pre- ferred mullet as bait, sailfish preferred bonito strip, and white marlin showed no preference. The results from 1971 represent only the begin- ning of this study. In 1972, the area west of the mouth of the Mississippi River to the Mexican bor- der will be included. Thus, future reports will cover the entire U.S. coast of the Gulf of Mexico. As data for the next few years are collected and analyzed, some of the conclusions reached for 1971 may be altered, and where no conclusions were reached in 288 1971. definitive results may be obtained or trends may be discerned. ACKNOWLEDGMENTS We are indebted to many people for helping us obtain the data on which this report is based. First, we very much appreciate the help given us by the officers of the cooperating organizations, namely, the New Orleans Big Game Fishing Club (H. Pra- ger, Jr., President), Mobile Big Game Fishing Club (CM. A. Rogers, III, Past President, and G. Cabanis, Jr., President), Pensacola Big Game Fish- ing Club (F. Neth, President), Destin Charter Boat Association (B. Bacon. President), and the Panama City Charter Boat Association (R. Stone, Presi- dent). We are especially indebted to H. Howcott, who unselfishly spent much time and effort in help- ing us get our program underway and in advising us after the program was started. Some others who were extremely helpful in various ways were L. Ogren. G. Maddox, J. Yurt, R. Metcalfe, J. Ogle, J. Lockfaw, R. Schwartz, R. Brunson, T. East- burn, K. Scales, III, F. Hubbard, C. Hughes, J. Dunlap, K. Reed, L. Freeman, F. Jones, and R. Martin. Finally, we owe much to all boat captains and anglers who provided us with data. LITERATURE CITED BULLIS. H. R. JR. 1955. Preliminary report on exploratory long-line fishing for tuna in the Gulf of Mexico and the Caribbean Sea. Part I. -Exploratory fishing by the Oregon. Commer. Fish. Rev. 17(10):1-15. 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. ERDMAN, D. S. 1962. The sport fishery for blue marlin off Puerto Rico. Trans. Am. 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. KALMAN. P. 1970. South Pass. New Orleans. July issue, p. 16-21, 37. 43-46. 58. LENARZ, W. H.. and E. L. NAKAMURA. 1974. Analysis of length and weight data on three species of billfish from the western Atlantic Ocean. In 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. 121-125. NAKAMURA. E. L. 1971 . An analysis of the catches and the biology of big game fishes caught by the New Orleans Big Game Fishing Club. 1966-70. East Gulf Sport Fish. Mar. Lab., Panama City. Fl., mimeo. rep., 13 p., 33 tables. NAKAMURA. E. L., and L. R. RIVAS. 1972. Big game fishing in the northeastern Gulf of Mexico during 1971. National Marine Fisheries Service. Panama City, Florida, mimeo. rep., 20 p. 37 pages of tables and figures. SIEBENALER. J. B. 1965. A new sport fishery in the northeastern Gulf of Mex- ico. In Proceedings of the Ninth International Game Fish Conference. Runaway Bay, Jamaica. November 20-21. 1964. p. 63-65. Int. Oceanogr. Found.. Miami, Fl. STRASBURG, D. W. 1970. A report on the billfishes of the central Pacific Ocean. Bull. Mar. Sci. 20:575-604. WILLIAMS, F. 1970. The sport fishery for sailfish at Malindi, Kenya. 1958-1968. with some biological notes. Bull. Mar. Sci. 20:830-852. 289 Angler Catch Rates of Billfishes in the Pacific Ocean JAMES L. SQUIRE, JR. ABSTRACT In 1969, 1970, and 1971 marine game fish anglers participating in the Pacific phase of the National Marine Fisheries Service cooperative marine game fish tagging program were asked to complete a postcard form which requested information of the number of days of billfishing the angler engaged in and the catches made. From the 17,876 angler days reported, the catch consisted of 10,234 billfishes. The average for the 3-yr period was 0.57 billfish per angler-day or 1.75 days of fishing per billfish. Analysis of data for the geographical areas in the eastern Pacific and Australia (Queensland) where billfishing is conducted resulted in a wide range of catch per effort for all billfish species combined. Off southern California, U.S.A., the catch was 0.10 fish per angler-day, equaling 10.3 days of fishing per fish. Off Baja California, Mexico, records show 0.82 fish per angler-day equaling 1.22 days fishing per fish, and fishing off Mazatlan yielded 1.21 fish per angler-day and 0.82 days fishing per fish. Off Acapuico, Mexico, the results were 0.95 fish per angler-day and 1.05 days per fish. Fishing off Australia the records show 0.55 fish per angler-day equaling 1.83 days per fish. The measurement of catch rates is of value in evaluating fishing success relative to seasonal changes, specific types of fishing gear or changes in gear, and effects of environmental change. How- ever, its greatest use has been in the determination of the effect of fishing on the stock or stocks of fish being utilized by sport and commercial fisheries. The only comprehensive sources of catch and ef- fort data for billfishes in the Pacific Ocean are the reports of the commercial longline fishery for tunas and billfishes published by the Research Division of the Japanese Fisheries Agency. These data have been used by researchers in the eastern Pacific in determination of commercial catch rates for bill- fishes (Suda and Schaefer, 1965; Kume and Schaefer, 1966; Kume and Joseph, 1969). The billfish sport fishery in the northeastern Pacific off Mexico and the United States is reported to capture at least 10,000 fish each year (Talbot-); however no accurate totals for sport-caught bill- fishes are available. The number of billfishes taken by the sport fishery is a fraction of that landed by the commercial fishery. However, the economic value 'Southwest Fisheries Center, National Marine Fisheries Ser- vice. NOAA, La Jolla. CA 90237. -Talbot, Gerald B., U.S. Bureau of Sport Fisheries and Wild- life, Clemson University, P.O. Box 429, Clemson, S.C. Personal communication. of the sport fishery resulting from the expenditure for goods and services by the thousands of billfish anglers in the pursuit of the sport is assumed to be substantial. The problems in obtaining a measure of catch and effort in marine sport fisheries are many. In contrast to a commercial fishery, where commercial landings and sometimes fishing records are kept and the number of operating units is known, the sport fishery consists of many small and mobile units which may or may not land their billfishes at locations where a record of the landing might be made. A report on the problem of obtaining sport fishery statistics was made by the Institute of Statistics, University of North Carolina (D. W. Hayne, 1964^) and many of the observations in that report are applicable to the design of a statistically accurate billfish angler sur- vey. As part of the cooperative marine game fish tag- ging program, conducted first at the Tiburon Marine Laboratory, Tiburon, California, and later at the Southwest Fisheries Center, La Jolla, California, an annual report describing the progress in billfish tag- ^ Hayne, D. W..The measurement of catch and effort in marine sportfishing. Report to the U.S. Bureau of Sport Fisheries and Wildlife, September 15, 1964. Institute of Statistics, Raleigh Sec- tion, North Carolina State, University of North Carolina, memo, 23 p. 290 ging was mailed to individuals that had participated in the program. This mailing list consisted of names of billfish anglers, most of whom fished in the east- em Pacific or off the east coast of Australia. In the annual reports for 1969, 1970, and 1971, a postcard was enclosed requesting information on the amount of fishing effort and catch. The billfish angler was asked to recall the number of days of billfishing and the number of billfish caught by species. The anglers were requested to give an "honest" answer and told that information on zero catches was important. The technique of postcard survey has been the subject of considerable con- troversy. The California Department of Fish and Game has used this technique and a number of re- searchers have published on the results of this type of survey (Calhoun, 1950, 1951; Clark, 1953; Pelgen, 1955; Abramson, 1963; Jensen, 1964). Hayne reported that it is difficult for a fisherman to remember precisely his catch of the previous year. However, with regard to billfishes, the fre- quency at which the average billfish angler partici- pates in the sport is limited and the annual catch of billfish per angler is small. Billfish are "trophy fish" and the author believes that the average billfish an- gler can recall within close limits the number offish caught during the previous year and the number of days he participated in the fishery. METHODS A sample of the questionnaire used is shown in Figure 1. The form was also used to update the NOAA FORM BB-IO ANGLER SURVEY o.b»o. ..-»«o: We I'i^iuld (Bpfe^ -ot* yoij' 'trnnh.ag rhe loll<^ing .nlonrwi'ior Pitoic '•'um the con^ltted conj by mOil. No postage iS r^qwred. Do fou — ih 'o con»">ue receiv.ng these 'ogg"^ feporfi? Cj Vei O No Pleoie ettimofe r°"' LAST YEAft'S cofch, try meo. m rhe jpocei be/o- AREA NUMBER OF DAYS rOU f ISMED FOR eiLLFIX TOTAL NUMBER CAUGHT llandrd or reJeosedJ | MARLIN SAILFIW So„.h,- Cal.l^rn.o 8°|0 Co'.'s'n.o Moio-Jor. *(0P>,(CD Olhr. .OUB NAwe STREET AOORESS r,T, 1 5T*TE 1 IIP CODE us DEPARTMENT OF COMMERCE W*TiON«L OCEANIC «ND »TMOS<>MEniC ADMI.- H*TiaN*i. MKRiME FISHERIES SERVICE NOAA-Nat iona I Marine Fisheries Service Southwest Fisheries Center P.O. Box 271 La Jol la, Cal ifornia 92037 Figure I. — Angler survey card. mailing list for the Cooperative Marine Game Fish Tagging Program annual report. The postcard form was sent to the billfish anglers in February of 1970, 1971, and 1972, and a prompt return of the card was requested. The number of survey cards sent each Table 1. — Combined catch and effort data for surveys conducted in 1969, 1970, and 1971. Species/catch (numbers) Catch rates Striped Area Angler days marlin Sail fish Black marlin Fish/angler day Days/fish USA Southern California 6.458 593 51 0.10 10.03 Mexico Baja California 8.710 6,168 964 0.82 1.22 Mazatlan 1.316 697 900 1.21 0.82 Acapulco 249 16 221 0.95 1.05 Australia (Queensland) Cairns 1,143 10 172 452 234 (all species) 0.55 Aver. 0.57 1.83 Total 17,876 Aver. 1.75 291 year with the annual tagging report varied from 1 ,900 to 2,600. RESULTS Approximately 50% of the survey cards were re- turned within a 3-mo period and the number of an- gler days in each of the major fishing areas, the number of billfishes caught, and calculations of numbers of fish per angler day and numbers of days of fishing per fish are given in Table 1 . The combined totals for the fishing areas off southern California, U.S.A., about the tip of Baja California, Mazatlan, and Acapulco, Mexico, and 1.0- 0.9- 0.8- , " 0.7- BAJA CALIFORNIA ^^-^ N flsh = 6J68_^ — --'^ >- < o 0.6- ■~--,„.^ q: a^ 05- MAZATLAN^^ N fish =697 ^-\,^ I .^..^ 1- 0.4- 3 ~'~~~^ Q3- 0.2- 01- SOUTHERN CALIFORNIA N fish = 593 0- ACAPULCO N fish = 16 1 1 1 1969 1970 1971 YEAR Figure 2. — Sport fishing catch per day for striped marlin in the eastern Pacific. Cairns, Queensland, Australia, were 17,876 angler days, catching 10.234 biiltlshes for an average of 0.57 fish per day and 1.75 days of fishing for each billfish. A breakdown of the totals given in Table 1 for each year is presented in Table 2. For these selected fishing areas the annual statis- tics from the survey on total catch and effort are as follows: 1969. 6,286 angler days, 3,404 billfishes caught equaling 0.54 fish per day and 1.90 days of fishing per fish; 1970, 6.286 angler days, 3.588 bill- fishes caught equaling 0.58 fish per day and 1.75 days of fishing per fish; 1971, 5,304 angler days. I.O-f 0.9 0.8 0.7- 0.6- 0.5- 0.4- 0.3- 02- 0.1- 0- MAZATLAN N fish = 900 BAJA CALIFORNIA N fish = 964 1970 YEAR Figure 3. — Sport fishing catch per day for sailfish in the eastern Pacific. 3,242 billfishes caught equaling 0.61 fish per day and 1.64 days of fishing per fish. A graphic presentation of the catch per effort data is given for striped mariin Tetroptitnis ciiidax in Figure 2; for sailfish Istiophonis pUiTypterus in Figure 3; and for black marlin Makaira indica in Figure 4. Catch per effort data for combined Figure 4. — Sport fishing catch per day for black marlin off Queensland. Australia. 292 XI •o c C3 o , "5 :s -a ^ u CJ 00 « ^ c O :£ -a Q CJ u o — o — — o o — o o o — ■* — 00 n r- o — ' OS ri Ov r- — (^ I I I I I I I I I I I I I - o o o o r*^ f. — o o o o o o O f"^ CN <^ rj I/-, 00 rj *© r*-i r~- OS r^i rt OS — 00 — n i/~, »/", — 00 — O — r*-i o o — o o fN V-1 OC ■^ ON r*-i — 00 00 SO rj ^C V-, Mill o — o o o s I I I II I I o o o o o V OS — r^ o o o o o — 00 -^ rj vi — n rj ri o o — — — r-i ^ v-1 rj OS '^ O -^ — W-, f*~l I I I li I 1 i:; n — V. ^ O 00 O so o o o O O m o O •/". rj rj n m rj r-- «/-i O 00 r*^ O o o o o rj r*i — rj £ 3 U £ 3 U £ 3 E^ J o CJ < E^ c 8 < t ^ -S CJ w 2 3 -2. c/5 oa N 3 i« c« .E CJ a < O i 3 .2, Mazatl Acapul Cairns Southe Baja C; Mazatli Acapul Cairns 293 1.5 1.4 L3 1.2- 1.1- 1.0- >- < Q 0.9- £ 0.8- 0.7- ^06- < " 0.5H 0.4- 0.3- 0.2- 0.1- BAJA CALIFORNIA N fish= 7,132 SOUTHERN CALIFORNIA N fish = 644 1969 1970 YEAR Mexico's Department of Tourism. Catch and effort data for Mazatlan and Las Palmas Bay (at the tip of Baja California) are shown in Figure o. Statistical data from the field sampling program show a catch rate for sailfish at Mazatlan of 0.74 fish per day and the postcard angler survey shows about 0.70 fish per day. For striped marlin caught about the tip of Baja California, Mexico, the Las Palmas Bay data shows a catch rate of 0.60 fish per day. the angler postcard survey shows about 0.75 fish per day. Comparative catch-per-unit-effort data are not available for southern California waters, but ex- perienced anglers state the figure of 0.10 billfish per day appears reasonable. Marine game fishing for billfishes is an important economic factor in many areas of the world. The monetary expenditure of marine anglers per billfish caught is recognized as substantial. The point Figure 5. — Combined species (striped marlin and sailfish) catch per day in the eastern Pacific. species of billfish at locations in the eastern Pacific are shown in Figure 5. SUMMARY AND DISCUSSION Striped marlin catch and effort data for fishing off southern California show a catch rate of 0.10 fish per day or less, and the catch rate off Acapulco is lower than southern California. The Baja Califor- nia, Mexico, catch rate is highest, ranging between 0.66 and 0.82 fish per day with a slight increase shown in the catch rate in 1971 as compared to 1969. For the fishing area off Mazatlan the catch rate has declined from 0.65 to 0.37 during the sur- vey years. During the 3-yr period catch rates for sailfish ranged about the 0.9 to 1.0 fish-per-day level off Acapulco and the 0.55 to 0.80 fish-per-day level off Mazatlan. The catch rate is much lower off Baja California than off Mazatlan and Acapulco, remain- ing steady at a rate of about 0. 1 fish per day. Black marlin catch rates off Cairns, Australia varied con- siderably from a low of 0.22 to a high in 1971 of 1.48 fish per day. In 1968 and 1969 the Tiburon Marine Laboratory conducted field sampling for billfishes about the tip of Baja California and at Mazatlan, Mexico. Catch and effort data were collected from available sources such as the sportfishing fleet operators and ^10- LlI - ol STRIPED MARLIN - PALMAS BAY - MAZATLAN — 1 1 1 1 1 r J F M A M J J A S N D MONTH ' i ' L- I ■ I SAILFISH -PALMAS BAY -MAZATLAN MONTH Figure 6. — Striped marlin (upper panel) and sailfish (lower panel) catch and effort rates off Las Palmas Bay (tip of Baja California) and Mazatlan, Mexico. 1968-1969. 294 (catch per effort level) at which the majority of an- glers will cease to fish is dependent upon location and accessibility of the fishing grounds. An exam- ple of this is billfishing off southern California, which has by the angler survey records a low catch rate of 0.10 fish per day, or 10.02 days per billfish. The accessibility of the fishing grounds to the large southern California fleet of sportfishing boats makes for a large effort in spite of a low catch. If this same catch rate were common about the tip of Baja California, Mexico, the number of U.S. an- glers traveling to this distant area to fish for bill- fishes might be only a fraction of the present number. The angler survey sampled to a greater degree those individuals who participated in the tagging program, and had fished off southern California, the west coast of Mexico, west coast of Central America, or Australia. The postcard survey method for obtaining billfish catch and effort data has the potential of sampling more billfish anglers than any other method. Selection of a mailing list based on active billfish anglers belonging to the major billfish clubs throughout the United States and in other countries could provide a sampling frame for a reliable worldwide statistical determina- tion of sportfishing catch and effort activity. The postcard method could provide a source of continu- ing information on the status of billfish angling rela- tive to the resource base on which it depends for the least monetary expenditure, when compared with other sampling methods. LITERATURE CITED ABRAMSON. N. J. 1963. Distribution of California angling effort in 1961. Calif. Fish Game 49:174-182. CALHOUN, A.J. 1950. California angling catch records from postal card surveys: 1936-1948; with an evaluation of postal card nonresponse. Calif. Fish Game 36:177-234. 1951. California state-wide angling catch estimates for 1949. Calif. Fish Game 37:69-75. CLARK. F. N 1953. California marine and fresh water sport fishing in- tensity in 1951. Calif. Fish Game 39:115-125. JENSEN, P. T. 1964. Landing estimates of California's marine recrea- tional salmon fishery. Calif. Fish Game 50:48-52. KUME. S.and J. JOSEPH. 1969. The Japanese longline fishery for tunas and billflshes in the eastern Pacific Ocean east of 130°W, 1964-1966. [In Span, and Engl.] Bull. Inter-Am. Trop. TunaComm. 13:277-418. 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. PELGEN, D. E. 1955. Economic values of striped bass, salmon, and steelhead sport fishing in California. Calif. Fish Game 41:5-17. SUDA, A., and M. B. SCHAEFER. 1965. General review of the Japanese tuna long-line fishery in the eastern tropical Pacific Ocean 1956-1962. [In Span, and Engl.] Bull. Inter-Am. Trop. Tuna Comm. 9:307-462. 295 The Canadian Swordfish Fishery'' S. N. TIBBO and A. SREEDHARAN^ ABSTRACT During the early 1960's the traditional harpoon fishery for swordfish off the east coast of Canada was replaced by a longline fisher) . Fishing areas and seasons expanded , landings increased and size composition of the catch decreased. Catch and effort data for the period 1958 to 1970 covering both fishing methods were analyzed and the results are presented. ' Abstract only; this paper was presented orally, but only title and abstract were submitted for publication. - Fisheries Research Board of Canada, Biological Station. St. Andrews, New Brunswick, Canada. 296 Landings of Billfishes in the Hawaiian Longline Fishery HOWARD O. YOSHIDA' ABSTRACT The landings of the Hawaiian longline fishery are dominated by the tunas. During 1964 to 1967, the tunas, by weight, made up an average of 66% of the catch, whereas the marlins and swordfish, Xiphias gladius, comprised about 34%. The catch of billfishes is composed of the striped marlin, Tetrapturus audax, blue marlin, Makaira nigricans, black marlin, M. indica, sailfish, Istiophorus platypterus, shortbill spearHsh, T. angustirostris, and swordfish. The annual landings of blue marlin ranged between 47 and 366 metric tons during 1952 to 1970. The annual landings of striped marUn fluctuated between 93 and 228 metric tons during the same period. The blue marlin dominated the catch from 1952 to 1961. Subsequent to 1963, the billfish catches have been dominated by the striped marlin. The monthly landings and the monthly catch rates of blue marlin and striped marlin showed similar trends. The monthly landings of striped marlin, however, showed greater fluctuations than the monthly catch per unit of effort. This was attributed in part to a change in the size composition of striped marlin in the third quarter. The Hawaiian longline fishery has been described in the past primarily from the viewpoint of a fishery for deep-swimming tunas, usually yellowfin tuna, Tliiinniis alhacares. and bigeye tuna, T. ohesus. June (1950), Otsu (1954), Shomura (1959), and Hida (1966) all have made studies on this fishery as it related to the tunas. One of the exceptions is a paper by Strasburg (1970) on the billfishes of the central Pacific Ocean, in which he briefly discussed the billfishes landed in Hawaii. This report considers the Hawaiian longline fishery as it relates to the bill- fishes, particularly the blue marlin, Makaira nigh- cans, and the striped marlin, Tetrapliirus audax, primarily during the period from 1963 to 1970. The data used for this report came primarily from two sources. The billfish landing data through 1968 were obtained from the Fishery Statistics of the United States. The landing data for 1969 and 1970 and fishing trip data are from the files of NMFS (National Marine Fisheries Service), Hono- lulu, Hawaii. Billfish weight and sex data from 1964 to the middle of 1970 were collected at the Honolulu auction markets by samplers from our Laboratory. ' NOAA, National Marine Fisheries Service, Southwest Fisheries Center, Honolulu Laboratory, Honolulu, Hawaii 96812. DESCRIPTION OF THE FISHERY The Hawaiian longline fishery is the only Ameri- can fishery employing the longline method of fishing (Shomura, 1959). The history and description of the fishery are given by June (1950) and Otsu (1954). Typical Hawaiian longline boats evolved from the Japanese sampan-type, live-bait boat (June, 1950). They are characterized by a narrow bow, angular lines and a low freeboard aft. The overall length of these vessels ranges from 8.53 to 18.90 m (28 to 62 ft). All except one of the vessels in the Hawaiian fishery have wooden hulls. The length of a fishing trip aver- ages 8 or 9 days for a Honolulu-based vessel and the majority of the trips are made within sight of the main Hawaiian Islands (Shomura, 1959). The number of longline boats in the Hawaiian fleet has steadily declined over the years. In 1952 there were 42 boats in the Hawaiian fishery. In 1964 the number was down to 31 and in 1970 to 20. Although the number of boats in the fishery has been declining, one new boat was recently added to the longline fleet. This vessel has a steel hull and a refrigerated fish hold, and has an extended cruising range. The vessel began operations in July 1969 and has fished 297 as far as 1,482 km (800 miles) from the Hawaiian Islands (Kanayama. 1970). Similar to the Japanese longline fisheries, the catches in the Hawaiian longline fishery are made up mostly of large tunas. During the period from 1964 to 1967, considering only the tunas and the bill- fishes, the tunas, by weight, made up about 669^ of the catch, the marlins about 32%, and the sword- fish. A'/p/!(a5^/a^/«i, about l%(Fig. 1). Among the tunas, bigeye tuna dominated the catch followed by yellowfin tuna and albacore, TIudvuis alaliinga. Among the billfishes, striped marlin dominated the catch, followed by blue marlin and swordfish. Small numbers of sailfish, Istiophorus platypterus, and shortbill spearfish, Tetrapturus angustirostris, are also taken. In 1970, the tunas and billfishes landed by the longline fishery were valued to the fishermen at $1,311,471. The billfishes contributed $291,837 (22%) to this amount. Other species taken on the longline, in their order of importance, are dolphin or mahimahi. Cory- phaena hippunis: wahoo, Acanthocybiiim sol- andii; and a few skipjack tuna, Katsiiwonus pelamis. LANDINGS OF STRIPED MARLIN AND BLUE MARLIN The annual landings of blue marlin ranged be- tween 47 and 366 metric tons during the period from 1952 to 1970 (Fig. 2). The landings declined steadily SWORDFISH CATCH COMPOSITION (BY WEIGHT) OF HAWAIIAN LONGLINE FISHERY Figure 1. — Composition of the tuna and billfish landings in the Hawaiian longline fishery. (ft z o O 400 c t- UJ 200 STRIPED MARLIN tfannml r-| BLUE MARLIN 1 i i-i n n' n . rrn^ n;n 1952 1954 I9S6 1956 I960 1962 1964 1966 1968 1970 Figure 2. — Annual landings of blue marlin and striped marlin from 1952 to 1970 in Hawaii. from a high of 366 metric tons in 1954 to a low point of 48 metric tons in 1 968. The landings recovered a little in 1969 and 1970. The annual landings of striped marlin fluctuated between 93 and 228 metric tons during this same period (Fig. 2). No clear trends are evident in the landings although it appears that the landings be- tween 1963 and 1970 were slightly higher than the landings prior to 1963. Of interest is the change in dominance from blue marlin to striped marlin in the landings beginning in 1962. This change was caused primarily by the declining blue marlin catches. Strasburg (1970) presented data on the monthly landings of blue marlin and striped marlin in the Hawaiian fishery from 1950 to 1963. For the period 1950 to 1960, Strasburg noted a complementary na- ture in the landings of the two species in that striped marlin were caught in large numbers when the blue marlin catches were lowest and vice versa. He noted, however, that the landing peaks of the two species tended to coincide in 1 96 1 and 1962 . Monthly landings from 1963 to 1970, however, again showed a displacement in peak landings for striped marlin and blue marlin (Fig. 3). Blue marlin catches were high- est in summer and lowest in winter, whereas striped marlin were more abundant in the winter than in the summer. The striped marlin landings were also characterized by having more than one peak in a year, and by wide fluctuations from month to month. The biggest dip in the landings each year usually occurred in the third quarter. Of interest is a similar complementary nature in the catches of yellowfin tuna and bigeye tuna in the Hawaiian longline fishery. The peak catches of yel- lowfin tuna are made during the summer while good 298 [ 1 BLUE MARLIN A i. - 1 » k ^AkM.^ ^, ^ A M Figure 3. — Monthly landings of blue marlin and striped marlin from 1963 to 1970 in Hawaii. catches of bigeye tuna are made during the winter and spring (June, 1950; Otsu, 1954; Shomura, 1959). This suggests that striped marlin and bigeye tuna may be responding to a different set of environmen- tal factors from the blue marlin and yeilowfin tuna. Strasburg (1970) has suggested a relation to the food supply to explain the complementary abundance of striped marlin and blue marlin around Hawaii. He noted that blue marlin fed largely on skipjack tuna, which were more abundant in the summer. This may account for the larger numbers of blue marlin during the summer. Further evidence that the blue marlin are indeed responding to the presence of their prey can be seen in the relation between the landings of skipjack tuna and blue marlin in Hawaii (Fig. 4). Generally speak- ing, good catches of blue marlin corresponded to good catches of skipjack tuna. The situation in 1965, «?» icnrn aS4 i I9SI •^ 19 ISM .953 S 4,000 < 5,000 191 •e 1966 S62 •r964 [0 MS 1967 1963 • ".9 I9«( • I95aa . IMS • I9S9 • ^ I.OOO 3 S IC » 1 10 2C X) z. W X » 5. » 40< however, did not conform to the general trend. The reason for this is not known. CATCH PER UNIT OF EFFORT The CPUE (catch per unit of effort) for striped marlin and blue marlin was determined to see if CPUE had any effect on the monthly landings. As Shomura (1959) indicated, measures of effort such as number of hooks or baskets of gear fished, are not readily available for the Hawaiian longline fishery. Thus for his analysis of the abundance of tunas around Hawaii, he used the number of trips as a measure of effort. Following Shomura, the number of trips was used to calculate CPUE. here given as number of fish caught per trip on a monthly basis (Fig. 5). The catch rates for striped marlin and blue marlin showed the same trends as the monthly landings. Similar to the monthly landings blue marlin catch rates usually peaked from July to September. Dur- ing the period from 1961 to 1969, however, the an- nual summer peak in the catch rates has shown a small but steady decline. Similarly, the monthly catch rates of striped mar- lin showed the same trends, although the fluctua- tions were not as pronounced as the monthly land- ings. As did the monthly landings, the monthly catch rates for striped marlin showed two peaks annually, usually one in the spring and the other in the fall. In contrast to the blue marlin, the annual peaks in the monthly catch rates for striped marlin from 1961 to 1969 have increased slightly. SIZE OF FISH The quarterly weight-frequency distribution of striped marlin by sex is shown in Figure 6. The size ITRIPEO MARLIN L n M J -A A J ^M/^l h \t\ A i ^1/ t^^ ^,\/, UN. w y ,„vl E ILUEMA RLIN i i ik i i A A [i ^ i .A BLUE MARLIN LANDINGS (METRtC TONS) Figure 4. — Relation between landings of skipjack tuna and blue marlin in Hawaii. Figure 5. — Monthly catch per trip of blue marlin and striped marlin. 299 STRIPED MARLIN (1961 -70) -MALES l-l 1ST QUARTER - 20 QUARTER p " " J T^ 1 30 QUARTER 11.1047 — u j-| -1 "Ti-h. 4TH QUARTER N . 5,935 -, p -1 rmr! Tu_ 1 WEIGHT CLASS (KILOGRAM) STRIPED MARLIN (1961-70 - FEMALES — ^ -\' 1ST QUARTER ; - ] - ■ - — h — i u 20 QUARTER r -|r "hn _^_^_ 1 30 QUARTER r ■^ "h Tn-v, 4TH QUARTER N-4,9fiO - r H rik . ">>_ WEIGHT CLASS (KILOGRAM) Figure 6. — Weight-frequency distribution of striped marlin. of male and female striped marlin are about identical and the size-frequency distribution of the males and females show almost no difference. They ranged from 3 to 147 kg (7 to 324 lb). It is interesting that during the first, second, and fourth quarters, the size-frequency distribution shows a bimodal dis- tribution while in the third quarter the size distribu- tion only shows one mode. In the first quarter the modes are located between 14 and 18 kg (31 and 40 lb) and 34 and 38 kg (75 and 84 lb), in the second quarter between 18 and 22 kg (31 and 48 lb) and 38 and 46 kg (84 and 101 lb), and in the fourth quarter between 10 and 14 kg (22 and 3 1 lb) and 34 and 38 kg (75 and 84 lb). In the third quarter the single mode is located between 26 and 30 kg (57 and 66 lb). It was noted earlier that the monthly landings showed greater fluctuations than the monthly catch rates and that the biggest dip in the landings was found consistently during the third quarter. This was ap- parently caused by a combination of low catch rates and the presence of only intermediate size fish in the landings in the third quarter. In the third quarter striped marlin represented by the larger of the two modes found in the other three quarters are evidently not present in large numbers in Hawaiian waters. Of interest is the observation that larvae of striped marlin are not found in Hawaiian waters (Mat- sumoto and Kazama, 1974). Matsumoto and Kazama have suggested several reasons for the absence of striped marlin larvae, including the possibility that adult striped marlin leave Hawaiian waters to spawn elsewhere. They cite as evidence the absence of the larger size group of striped marlin in the Hawaiian Islands area starting in about July. As noted above, my data show that the larger striped marlin are not present in the commercial landings in large numbers in the third quarter. In contrast to the striped marlin, the blue marlin show striking differences in size between the sexes and also in their size distribution (Fig. 7). The females grow to be much larger than the males; they ranged from 7 to 444 kg ( 15 to 979 lb). In the first and fourth quarters no clearly defined modes are present in the female weight-frequency distribution. In the second quarter a single mode is evident between 140 and 144 kg (309 and 317 lb). The third quarter dis- tribution shows a mode between 120 and 184 kg (264 and 406 lb). The size distributions of the males, on the other hand, show a pronounced mode between 44 and 80 kg (97 and 176 lb) in all quarters of the year. They ranged from 12 to 140 kg (26 to 309 lb). 300 BLUE MARLIN (1961 -6< }) - MALES 1ST QUARTER . N'60 ^ 1 1 1 rTT>=r ?D OllARTFR 1 N>264 — 1 l— 1 1 . — t 1 \ 30 QUARTER 1 N-626 ___^ ~|— 1 , 1 1 4TH QUARTER — N.377 t— r-|~ -r^ 1 41 91 141 I 1 I 50 100 150 WEIGHT CLASS (KILOGRAM) LITERATURE CITED HIDA, T. S. 1966. Catches of bigeye and yellowfin tunas in the Hawaiian longhne fishery. In T. A. Manar (editor). Pro- ceedings of the Governor's Conference on Central Pacific Fishery Resources, p. 161-167. State of Hawaii, Honolulu. JUNE, F. C. 1950. Preliminary fisheries survey of the Hawaiian-Line Islands area. Part I - The Hawaiian long-line fishery. Commer. Fish. Rev. 12(l):l-23. KANAYAMA, R. K. 1970. The Kilaueci: Hawaii's first modem tuna boat. Aloha Aina (Love of Land), Dep. Land Nat. Resour.. Hawaii l(3):3-5. MATSUMOTO, W. M., and T. K. KAZAMA. 1974. Occurrence of young billfishes in the central Pacific Ocean. In R. S. Shomura and F. Williams (editors). Proceedings of the International Billfish Symposium, Kailua-Kona, Hawaii, 9-12 August 1972. Part 2. Re- view and Contributed Papers. U.S. Dep. Commer., NOAA Tech. Rep. NMFS SSRF-675 p. 238-251. OTSU, T. 1954. Analysis of the Hawaiian long-line fishery, 1948-52. Commer. Fish. Rev. 16(9): 1-17. SHOMURA, R. S. 1959. Changes in tuna landings of the Hawaiian longline fishery, 1948-1956. U.S. Fish Wildl. Serv., Fish. Bull. 60:87-106. STRASBURG, D. W. 1970. A report on the billfishes of the central Pacific Ocean. Bull. Mar. Sci. 20:575-604. BLUE MARLIN (1961 -69) -FEMALES ^i\W T- _ '-1 1 ISTQU kRTER 169 UTt tUti " is 5 20 QUARTER N = 478 TTnTmJ>^^., o (e UJ 5 -TTrkfl Mnf: 30 QUARTER N:66l -fTU^-i-^ Irimllfi m 4TH QUARTER N = 447 91 141 191 241 291 341 391 I I I I I I I I I 10 50 100 150 200 250 300 350 400 WEIGHT CLASS (KILOGRAM) Figure 7. — Weight-frequency distribution of blue marlin. 301 Fishery-Oceanographic Studies of Striped Marlin, Tetrapturus audax, in Waters off Baja California. I. Fishing Conditions in Relation to the Thermocline EIJI HANAMOTO' ABSTRACT In this report, the author analyzed Ashing conditions for striped marUn in waters off Baja California in relation to the thermocline. The results were as follows: 1. In subarea SW, bounded by lat. I5°-25°N and long. 115°-110°W, catch rates begin increasing from about May and reach a peak between July and October. In subarea SE, bounded by lat. 15 -25°N and long. 110°-I05°VV, there appears to be a tendency for catch rates to be highest from July through October. In subarea M, bounded by lat. 10°N to along the coast of Mexico and long. 105°-9S°W, catch rates are highest between May and July. 2. From December through March there is good fishing in relatively narrow areas around the tip of Baja California. In April, a good fishing ground appears off Manzanillo and in May this ground begins to expand seaward. From June, the area of good fishing off the coast from Acapuico to Mazatlan begins to expand seaward and the greatest expansion of grounds occurs off Baja California in September. In October, the ground becomes narrow and is located farther east. 3. The pattern of expansion and contraction of the shallow thermocUne area coincides fairly closely with the pattern of expansion and contraction of good fishing grounds. One of the factors related to this phenomenon is that the formation of good fishing grounds off Baja California is considered to be related to the shallow thermocline areas where there is a more abundant food supply. The waters off Baja California have been tcnown to be a good subsurface fishing ground for striped marhn, Tetrapturus audax, ever since the Japanese tuna longHne fishery began fishing the area in 1963. This same area is also a good surface fishing ground for yellowfin tuna, Thunniis albacares, and skipjack tuna, Katsuwoniis pelamis. Although several studies have been canied out on striped marlin in the eastern tropical Pacific (How- ard and Ueyanagi, 1965; Kume and Joseph, 1969; Shiohama, 1969), there has been relatively little work done on the relationships between the fish and the environment. The main purpose of this study is to describe the formation mechanism of the striped marlin fishing ground in this area through the exami- nation of the monthly distribution of striped marlin, seasonal variations in catch rates and size composi- tions, and the relationship between fishing condi- tions and the thermocline. 'Kanagawa Prefectural Fisheries Experimental Station, Jogashima. Miura-city. Kanagawa-pref., Japan. MATERIALS AND METHODS In order to examine the seasonal variations in catch rates of striped marlin, the data were sum- marized by subareas as shown in Figure 1. These subareas, SW, SE, and M, were designated on the basis of similarities in trends in the monthly distribu- tions of mean relative abundance of striped marlin. The source of data used in examining seasonal variations in relative abundance (Figs. 2, 3, 4) was the "Annual Report of Effort and Catch Statistics by Area on Japanese Tuna Longline Fishery" for 1963-70 (Japan. Fisheries Agency, Research Divi- sion, 1966-72). Numbers of hooks fished and fish caught were summarized by month and by 5° squares, and the monthly catch rate in each subarea was calculated as follows: Catch rate in a subarea = (2C,7SF/) x 100, where C/ = numberoffishcaught in the/th5°square, Fj = number of hooks fished in the /th 5° square. Monthly distributions of mean relative abundance (Fig. 5) were based on averages for the years 1966-70 302 115 110 Figure 1. — Subareas selected for examination of striped marlin catch rates. from data obtained through the courtesy of the Far Seas Fisheries Research Laboratory. Size composi- tion data from the same source were summarized by quarters of the year for 1965 and 1967-70 for two subareas (as shown in Figs. 6 and 7). Monthly ther- mocline topography (Fig. 8) was obtained directly from the atlas of Robinson and Bauer (1971). SEASONAL VARIATIONS RATES IN CATCH Monthly variations in the catch rates for striped marlin in waters off Baja California (subareas SW and SE) and off southern Mexico (subarea M) are shown for the years 1963-70 in Figures 2, 3, and 4. In subarea SW (Fig. 2), the catch rates are lowest from January through April, begin increasing from about May, reach a peak between July and October, and then decrease after November. It is noted that there are relatively small between-year differences in catch rates in this subarea. In subarea SE (east of SW) the catch rates show a marked between-year variation (Fig. 3). The wide fluctuations appear to be especially noticeable in March and April, e.g. the lowest monthly catch rate in 1968 occurred in April, which was also the month showing the highest catch rate for 1970. The between-year variability was least during the July- September period. In subarea M, off southern Mexico, catch rates are generally low between January and March. They begin increasing in April and are highest between May and July (Fig. 4). After August the catch rates tend to become lower, although the year-to-year fluctuation is considerable. SIZE COMPOSITION The average weight-frequency distribution, by quarters of the year, was compiled for the two sub- areas shown in Figure 6. In the waters off Baja California (subarea S'), the modal weight of the larger size group is observed at 3 1 to 35 kg during the first quarter (I-Q), at 35 to 39 kg during the second quarter (I I-Q), and at 39 to 47 kg during the third quarter (IIl-Q) (Fig. 7). The average modal weights tend to increase from the first to the third quarters. There is only one size group during the third and fourth quarters. The modal weight during the fourth quarter ( I V-Q) is 27 to 3 1 kg and is smaller than that of the third quarter. There are two size groups during the first and second quarters, the modal weights being 1 1 to 15 kg and 15 to 19 kg, respectively. Data for subarea M' are available only for the second quarter. During the second quarter two size groups are present — one with a mode at 27 to 31 kg and the other at 43 to 47 kg. The modal group of the smaller-size fish is the more dominant of the two groups. ^.0 2 3.0 o ro U 2.0 Sub- Area SW 1.0 1963 6A 65 66 67 68 69 70 JFMAMJJASOND Figure 2. — Monthly variations in catch rates of striped marlin in subarea SW, 1963-70. 303 7. 3.0 "-2.0 SI u m o 1.0 Sub- Area 5E 1963 6^ 65 66 67 68 69 70 JFMAMJJASOND Figure 3. — Monthly variations in catch rates of striped marlin in subarea SE, 1963-70. SEASONAL SHIFTS IN FISHING GROUNDS Monthly distributions of mean relative abun- dance of striped marlin in waters off Baja California and southern Mexico for the period 1966-70 are shown in Figure 5. Areas of high (more than 1.5%), medium (between 1.4 and 0.5%) and low (less than V. 0.2.0 -C u U 1.0 'Sub-Area M JFMAMJJASOND Figure 4. — Monthly variations in catch rates of striped marlin in subarea M. 1963-70. 0.4%) relative abundance are contoured. From De- cember through March good fishing grounds appear in relatively narrow areas around the tip of Baja California and near the mouth of the Gulf of California. In April, the ground near the Gulf en- trance disappears, and in its place good fishing ap- pears off Manzanillo. In May, good fishing begins to expand seaward as far as long. 1 10°W. At the same time another good fishing ground appears off Salina Cruz. Good fishing off Salina Cruz also ex- pands seaward from June through August. Good fishing on this ground peaks in June and ends after September. 120 110 100 120 110 100 120 110 100 120 110 100 120 110 100 120 110 100 120 110 100 120 110 100 Catch Rate 1.5 •/. - l.A - 0.5 •/. OA'I. Figure 5. — Monthly distributions of mean relative abundance of striped marlin in waters off Baja California and southern Mexico for 1966-70. 304 Figure 6. — Subareas selected for examination of striped marlin size composition. Sub-area S' III N. 39A N. 5,6^0 11 19 27 35 A3 51 59 67,^^ 11 19 27 35 43 51 59 67, From June, the area of good fishing off the coast from Acapulco to Mazatlan begins to expand sea- ward to about long. 115°W. A small, localized area of good fishing is also located at the entrance of the Gulf of California. By July, the area of good fishing has expanded seaward and along the coast and by August the good fishing grounds form a broad and continuous band throughout the waters of Baja California. The seaward expansion of good fishing continues into September and extends as far west as long. 117°W. This shift in good fishing into the offshore waters, however, is accompanied by a de- cline in catch rates in the more coastal waters. In October, the fishing ground becomes narrow and is located farther east. This phenomenon coincides °'° Sub- area M' IIQ N. 1,262 11 19 27 35 43 51 59 67, Figure 7. — Weight-frequency distributions of striped mar- lin in subareas S' and M' shown by quarters of the year. with the decreasing trend in catch rates after Oc- tober in subarea SW as shown in Figure 2. In November, the area of good fishing is narrower than in October and is divided into two areas; one is 100 120 100 120 Longitude 100 120 100 Figure 8. — Monthly thermocline topography for the eastern tropical Pacific Ocean (after Robinson and Bauer 1971). The numbers on the contour lines rep- resent the depth to the top of the thermocline in hundreds of feet. 305 centered off the mouth of the Gulf of California and the other is the offshore area bounded by lat. 15°-20°N and long. 107°-115°W. FISHING CONDITIONS IN RELATION TO THETHERMOCLINE Figure 8 shows the monthly thermocline topog- raphy (depth to the top of the thermocline) for the eastern tropical Pacific as described by Robinson and Bauer (1971). The depth to the top of the ther- mocline is in general relatively shallow in the east- ern tropical Pacific (Cromwell, 1958; Forsbergh and Broenkow, 1965; Sund and Renner, 1959). As shown in Figure 7, the shallow thermocline area begins to extend seaward beginning in June, ex- tends farthest seaward from July through Sep- tember, and begins contracting after October. This pattern of expansion and contraction of the shallow thermocline area coincides fairly closely with the pattern of expansion and contraction of good fishing grounds as shown in Figure 5. It is noted that the areas of good fishing begin expanding after June in correspondence with the expansion of the shallow thermocline area. From July through September, when the shallow thermocline area is most extensive, the areas of good fishing are also most extensive. In November, when the shallow thermocline area is contracted, so is the area of good fishing. Between December and March, when the shallow thermocline area is narrowest and con- fined to the region around the mouth of the Gulf of California, the area of good fishing is also confined to the same small area. For example, the 100-ft con- tour in thermocline topography is recessed shore- ward at about lat. 23°-25°N and long. 1 17°W in Sep- tember and lat. 21°N and long. 112°W in October. In these same general areas good fishing grounds are found in a similar pattern. In November, the 100-ft contour is noticeably recessed shoreward at about lat. 20°-23°N and long. 106°W and a good fish- ing ground is also found with this same shape. In order to clarify this relationship between thermocline depth and good fishing grounds, the areas with depths to the top of thermoclines shal- lower than 100 ft were calculated for subarea S (subareas SE and SW combined) and plotted along with average monthly catch rates in Figure 9. It is seen that the monthly catch rates increase as the index of shallow thermocline area increases. Both the catch rates and index are highest from July through October. The catch rates are also some- what high from December through January when the index of shallow thermocline area is low. This phenomenon is caused by the fact that fishing is conducted around the mouth of the Gulf of Califor- nia where the thermocline is shallow during these months. The relationship between the depth of the ther- mocline and the distribution of tunas has been dis- cussed by several workers (Brandhorst, 1958; Blackburn, 1965; Green, 1967; Suda, Kume, and Shiohama, 1969; and Kawai, 1969). According to Brandhorst ( 1958), an area with a high standing crop of zooplankton is generally also a region with a shal- low thermocline, while an area with poor standing crop would, in general, tend to correspond with a deeper thermocline. Laevastu and Rosa (1963) sug- gested that thermocline ridges seem to be favorable for aggregation of tunas. As one of the factors re- lated to the above, it is considered that a high stand- ing crop of zooplankton would have the effect of attracting small forage organisms which in turn re- sults in aggregating tunas. JFMAMJJASOND Figure 9. — Index of extent of surface areas with thermo- clines shallower than 100 feet plotted against the monthly average catch rates of striped marlin for area S (includes subareas SW and SE in Fig. I ). 306 In the waters off Baja California the thermocUne is generally shallow and there is a correspondingly high standing crop of zooplankton (Brandhorst, 1958). It is likely, therefore, that the seasonal shifts in areas of good fishing for striped marlin would coincide with the expansion and contraction of the shallow thermocline areas. In other words, it seems that the formation of good fishing grounds off Baja California is related to shallow thermocline areas where there is a more abundant food supply. Furthermore, the depth of the thermocline in lower latitudes generally coincides with the depth of the oxycline. Dissolved oxygen decreases rapidly within the thermocline and becomes virtually nonexistent below the bottom of the thermocline. Concerning the relation between fish and dissolved oxygen it was reported, for instance, that the minimum volume required by salmon is about 3 ml per liter (Tamura, 1949). Banse (1968) indicated that though the relation between fish catches and water temperatures in Arabian Sea trawling grounds is not too clear, the catches tend to fluctuate according to levels of dissolved oxygen in the bottom water layer. It is clear that the relationship between the amount of dissolved oxygen and the distribution of striped marlin should be studied as an important aspect of fishery oceanography. ACKNOWLEDGMENT The author is most grateful to Shoji Ueyanagi, Keiji Nasu, and Susumu Kume of the Far Seas Fisheries Research Laboratory, and Masaki Ebizuka of the Kanagawa Prefectural Fisheries Experimental Station for their helpful criticism and advice on this study. He also wishes to thank other staff members of that Laboratory for supplying the background data and for providing valuable sugges- tions. Grateful thanks are also extended to Tamio Otsu, National Marine Fisheries Service, Honolulu Laboratory, who kindly helped in reviewing and editing this report. LITERATURE CITED BANSE, K. 1968. Hydrography of the Arabian sea shelf of India and Pakistan and effects on demersal fishes. Deep-Sea Res, 15:45-79. BLACKBURN, M. 1965. Oceanography and the ecology of tunas. Oceanogr. Mar. Biol. Annu. Rev. 3:299-322. BRANDHORST, W. 1958. Thermocline topography, zooplankton standing crop, and mechanisms of fertilization in the eastern tropical Pacific. J. Cons. 24:16-31. CROMWELL, T. 1958. Thermocline topography, horizontal currents and "ridging" in the eastern tropical Pacific. [In Span, and Engl.] Bull. Inter-Am. Trop. Tuna Comm. 3:135-164. FORSBERGH, ED., and WW. BROENKOW. 1965. Oceanographic observations from the eastern Pacific Ocean collected by the R/V Shoyo Maru, October 1963-March 1964. [In Span, and Engl.] BuU. Inter-Am. Trop. Tuna Comm. 10:85-237. GREEN, RE. 1967. Relationship of the thermocline to success of purse seining for tuna. Trans. Am. Fish. Soc. %: 126-130. HOWARD. J.K., and S. UEYANAGI. 1965. Distribution and relative abundance of billfishes {Is- tiophoridae) of the Pacific Ocean. Stud. Trop. Oceanogr. (Miami), 2. 134 p. JAPAN. FISHERIES AGENCY. RESEARCH DIVISION. 1966. Annual report of effort and catch statistics by area on Japanese tuna longline fishery. 1963, 322 p. 1967a. Annual report of effort and catch statistics by area on Japanese tuna longline fishery. 1964, 379 p. 1967b. Annual report of effort and catch statistics by area on Japanese tuna longline fishery. 1965, 375 p. 1968. Annual report of effort and catch statistics by area on Japanese tuna longline fishery. 1966, 299 p. 1969. Annual report of effort and catch statistics by area on Japanese tuna longline fishery, 1967, 298 p. 1970. Annual report of effort and catch statistics by area on Japanese tuna longline fishery, 1968, 283 p. 1971. Annual report of effort and catch statistics by area on Japanese tuna longline fishery. 1%9, 297 p. 1972. Annual report of effort and catch statistics by area on Japanese tuna longline fishery, 1970, 326 p. KAWAI, H. 1969. On the relationship between thermal structure and distribution of long-line fishing-grounds of tunas in the intertropical Atlantic — I. Analysis based on isotherms on level surfaces, topographies of thermocline, etc. [In Jap., Engl, abstr.l Bull. Far Seas Fish. Res. Lab. (Shimizu), 2:275-303. 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 Jap., Engl, summ.] Bull. Far Seas Fish. Res. Lab. (Shimizu), 2:115-162. LAEVASTU, T., and H. ROSA. JR. 1963. Distribution and relative abundance of tunas in rela- tion to their environment. FAO (Food Agric. Organ. U.N.) Fish. Rep. 6(3):I835-1851. ROBINSON, M.K., and R.A. BAUER. 1971. Atlas of monthly mean surface and subsurface tem- perature and depth of the top of the thermocline North Pacific Ocean. Fleet Numerical Weather Central, Mon- terey, California, 95 p. 307 SHIOHAMA. T. SUND. P.N., and J. A. RENNER. 1969. A note on the marlrns caught by tuna longline fishery 1959. The chaetognatha of the EASTROPIC expedition, in the eastern Pacific Ocean east of 130°W [In Jap., Engl. with notes as to their possible value as indicators of hy- abstr.] Bull. Far Seas Fish. Res. Lab. (Shimizu), 1:5- drographic conditions. [In Span, and Engl.] Bull. Inter- 34. Am. Trop. Tuna Comm. 3:395-436. SUDA, A., S. KUME, and T. SHIOHAMA. TAMURA, T. 1969. An indicative note on a role of permanent thermocline 1949. Gaii no henka ga gyorui ni oyobosu eikyo. No. as a factor controlling the longline fishing ground for 9-Kankyosui no yokaisansoryo ga gyorui no san- bigeye tuna. [In Jap., Engl, abstr.] Bull. Far Seas Fish. soshohiryo ni oyobosu eikyo. [In Jap.] Suisan Gaku zas- Res. Lab. (Shimizu), 1:99-114. shi 54:40-47. 308 A Review of the Longline Fishery for Billfishes in the Eastern Pacific Ocean JAMES JOSEPH, WITOLD L. KLAWE, and CRAIG J. ORANGE' ABSTRACT Catch and effort statistics from the Japanese longline flshery are used to examine the quarterly distribution of each of the six species of billfishes taken in the eastern Pacific Ocean cast of long. 130°W. Striped marlin appear to be the most widely distributed billfish in the eastern Pacific. Blue marlin are confined more to the equatorial high seas regions than the other species. Sailfish are extremely abundant within 600 miles of the shoreline along Mexico and Central America. Shortbill spearfish are relatively sparsely distributed and less abundant in inshore waters than are sailfish. Black marlin are the least widely distributed and least abundant of the billfishes in the eastern Pacific. Swordfish are abundant in waters around Baja California, Mexico and near northern Peru and southern Ecuador. They are also frequently encountered in or near the cool upwelled waters along the equator. Trends in abundance, as reflected by catch/1.000 hooks and total catch, are discussed. On the southern grounds of the striped marlin fishery , apparent abundance of this species has dropped to about a third of its highest level, but fishing success has remained constant on the northern grounds. Catches of striped marhn reached their peak in 1968 (337,000 fish): by 1970 the catch had dropped to 180,000 fish. Apparent abundance and catches of blue marlin also decreased from levels in the early I960's. In 1963, 75,000 blue marlin were taken but the catch decreased to about 22.000 fish by 1966 and has fluctuated about that level since. Because so few black marlin are taken in the eastern Pacific, trends in the abundance of this species are not discussed. The longline fishery for sailfish in the eastern Pacific began in a substantial way in 196? with a catch rate of about 80 fisli/1,000 hooks on the major sailfish grounds but by 1970 this had dropped to about 11 fishyi,000 hooks. Also catches on these grounds dropped from a peak of about 370,000 fish in 1965 to about 2 10,000 fish in 1970. Catches of sw ordfish contined to increase from the beginning of the fishery in the 1950's until 1969, the peak year, when about 112,000 fish were landed. Catches decreased in 1970, although effort decreased also. The apparent abundance of swordfish has shown no general decreasing trends. A general discussion of the needs of scientific research on billfishes is given in the final section of the report. Billfishes are distributed throughout nearly all of the temperate and tropical oceans of the world and are caught by commercial and sport fishermen. Six species of billfish occur in the Pacific Ocean. The nomenclature of billfishes has been a controversial subject for some time. For the purposes of this paper we chose to utilize the scientific nomencla- ture of Nakamura. Iwai, and Matsubara (1968). We also show the common names in English, Spanish, Japanese, Korean, and Chinese. 'Inter-American Tropical Tuna Commission, c/o Scripps In- stitution of Oceanography, La Jolla. California 92037. Xiphias gladius Linnaeus Chinese (People's Republic of China PRC): chien-yij Chinese (Republic of China RC): chien-ch'i-yii English: Swordfish Japanese: mekajiki Korean: whang-sae-chi Spanish: pez espada Tetrapturus angiistirostris Tanaka Chinese (PRC): hsia-wen-ssu-chii-ch'i-yii Chinese (RC): English: Shortbill spearfish Japanese: furajkajiki Korean: 309 Spanish: pez aguja corta Tetraptunts audox (Philippi) Chinese (PRC): ch'i-tso-shih-ch'iang-yii Chinese (RC): hung-jou-ch'i-yii English: Striped marlin Japanese: makajiki Korean: Spanish: marHn rayado Makaira mazara (Jordan and Snyder) Chinese (PRC): lan-ch'iang-yii Chinese (RC): hei-p'i-ch'i-yii English; Blue marlin Japanese: kurokajiki Korean: nog-saeg-chi Spanish: marlin azul Makaira indica (Cuvier) Chinese (PRC): Chinese (RC): pai-p'i-ch"i-yii English: Black marlin Japanese: shirokajiki Korean: Spanish: marlin negro Istiophorus platypterus (Shaw and Nodder) Chinese (PRC): tung-fang-ch'i-yii Chinese (RC): pa-chiao-ch'i-yii English: Sailfish Japanese: bashokajiki Korean: dot-sae-chi Spanish: pez vela The term billfish in this report is meant to include all of the six species listed above. Two of the six species which occur in the eastern Pacific are widespread and rather evenly distrib- uted throughout the Pacific Ocean. Striped marlin occur between approximately lat. 45°N and 40°S with the heaviest concentration in the eastern Pacific east of long. 115°W. The distribution of blue marlin is nearly identical to that of striped marlin; however, it is more restricted in a north-south di- rection, from about lat. 40°N to 35°S. The major concentration of blue marlin in the Pacific is be- tween the equator and lat. 10°N, from long. 130°W to 145°E. The remaining four species, although distributed widely throughout the Pacific Ocean, show a somewhat more patchy distribution. Swordfish, which extend more poleward than the other bill- fishes, occur between about lat. 50°N and 40°S. Black marlin, which are found between about lat. 35°N and 30°S, are most concentrated in the west- em Pacific and occur in high concentration only sporadically in the eastern Pacific. Sailfish and shortbill spearfish are found throughout the Pacific between about lat. 35°N and 25°S. Although there is much confusion in the catch statistics of these two species, the higher concentrations of sailfish appear to be more associated with landmasses than those of shortbill spearfish; the latter seem to be more abundant in warmer waters. Sport fisheries for billfishes have existed in the eastern Pacific Ocean for the last 70 years. Minor commerical fisheries for some of the billfish species have existed for a long time. Striped marlin and swordfish particularly have been harvested com- mercially in waters off California and Mexico since about 1915 (Frey, 1971) and off Peru and Ecuador by subsistence fishermen since long before that. There were no substantial fisheries for billfish in the eastern Pacific until about 1956 when Japanese ves- sels first began taking billfish in large quantities. The Japanese method of fishing called longlining involves the use of long lines of gear, up to 120 km long, from which baited hooks are hung to a depth of about 80 to 200 m. Approximately 2,000 hooks are used in each operadon of the gear. The first longlining for billfish (and tunas) in the eastern Pacific was conducted by the Pacific Oceanic Fishery Investigations (POFI) of the U.S. Fish and Wildlife Service. In 1952 and 1954, 18 longline sets were made from POFI vessels (Royce, 1957). Similar experimental fishing for billfishes was conducted by the California Department of Fish and Game (Wilson and Shimada, 1955; Mais and Jow, 1960). Striped marlin and swordfish were fished commercially unfil 1937 when it became il- legal to land and sell striped marlin; swordfish is still a commercial species. In 1954 and 1955, in connection with underwater nuclear tests conducted on the high seas southwest of California, four longline cruises were undertaken by the U.S. Atomic Energy Commission (AEC). These operations produced unspecified catches of billfish (Shimada, 1962). More details of these cruises are probably contained in the AEC Techni- cal Reports Nos. WT-1013 and WT-1019 printed in 1956 but, although declassified, these reports are difficult to obtain. All of the cruises discussed above were of a non- commercial nature. As already noted the first major commercial operation for billfish in the eastern Pacific started in late 1956 when Japanese longline vessels, which until then had been operaUng in the area west of long. 130°W, commenced to fish east of 310 that meridian. After 1956 the Japanese longline fishery in the eastern Pacific expanded rapidly and at the present this fleet is fishing in all areas of the eastern Pacific in which billfish and tunas are found. In addition to their commercial longline opera- tion, the Japanese used longline gear to investigate the complex oceanic environment during a number of scientific cruises devoted to fishery biology and exploratory fishing. The results of these investiga- tions are well documented in trade as well as scien- tific journals. Some of the latter are: Suda and Schaefer, 1965; Kume and Schaefer, 1966; Kume and Joseph, 1969a and 1969b; Anonymous, 1972. Commercial longline vessels of the Republics of Korea and China also fish for billfish in the eastern Pacific. The vessels of these two countries first began their operations in the eastern Pacific in the mid-1960"s. Documentation of these fisheries is not complete and statistical coverage is low (Anony- mous, 1968a, 1970a, and 1971a). In 1965 the U.S.S.R. conducted two longline cruises in the eastern Pacific, mostly in the Gulf of Tehuantepec, Mexico. Results are given in Chernyi (1967); Novikov and Chernyi (1967); and Yurov and Gonzalez (1971). The latter report also dis- cussed the results of a Cuban longline expedition for billfishes and tunas in the eastern Pacific in 1967 (Bravo and Gonzalez, 1967). During Cruise 14 of the RV Anton Bruiin, oper- ated by the U.S. National Science Foundation, longlining was conducted off Chile and Peru in 1966 (Shomura)^. Experimental longline fishing for swordfish off California and Mexico was conducted by the U.S. Bureau of Commercial Fisheries in 1968. Results of these investigations were given by Kato (1969). Most recently, in 1970, personnel of the Scripps Institution of Oceanography conducted experimen- tal longline fishing for tunas and billfish in the east- em Pacific Ocean to the west of Baja California (Blackburn, Williams, and Lynn)'. In this report the literature mentioned above is ■^Shomura, R. S.. unpublished report. Cruise Report. Re- search Vessel Anion Briiiin. Cruise 14. Special Report No. 4, Marine Laboratory Texas A&M University. Galveston. Texas. 38 pp. (pages 7 through 38 not numbered), 1966. ^Blackburn. M., F. Williams, and R. Lynn, unpublished re- port. The bluefm tuna approach region off Baja California, pp. 17-19 in: Progress Report — Scripps Tuna Oceanography Re- search (STOR) Program — Report for the year July I. 1969 -June 30. 1970. Univ. Calif., Scripps Inst, Oceanogr,, IMR Ref, (71-3), SIO Ref. 70-32:24 pp. 1970. Utilized to discuss the distribution of billfishes in the eastern Pacific Ocean. Data on catch and effort for the Japanese longline fishery, which captures ap- proximately 85% of the billfish taken in the eastern Pacific, are used to study trends in relative abun- dance, effort, and catch. In the final section prob- lems relevant to scientific research on billfish are discussed. THE DATA— SOURCES AND PROCESSING The major source of the information used in this report is from the Japanese longline fleet. These vessels maintain logbook records of their fishing operations which are submitted to the Fisheries Agency, Ministry of Agriculture and Forestry, Japan. The data are printed each year in the Annual Reports of Effort and Catch Statistics of the Re- search Division, Fisheries Agency of Japan (Anonymous 1968b, 1969b. 1970b, 1971b, and 1972). Catches expressed in numbers offish are re- ported by species, areas of 5 geographical degrees on a side, month, type of operation, size of vessel, type of bait utilized, number of sets and number of hooks. Data from 1966 through 1970 (Anonymous. 1968b. 1969b, 1970b, 1971b, and 1972) were taken from the Fisheries Agency's Annual Reports; prior to that time the reports of Suda and Schefer (1965), Kume and Schaefer (1966) and Kume and Joseph (1969a), were used. Details of data collection, han- dling, and logbook coverage are given in these re- ports. All logbook catch and effort data were stored on magnetic tape and then used to generate tabulations of catch and effort in convenient format for analysis. In order to compute total catch for the Japanese longline fishery, the recorded logbook catch was adjusted by the reciprocal of the percent coverage which the logbooks represented of the total catch. These percentages, which vary between 60 and 90, are given in the relevant reports listed above. The saury (Cololabis saira) has been the princi- pal bait used by the Japanese longline fishery but in recent years there has been increased use of other types of bait. Since 1964 some of the vessels operat- ing off the west coast of Baja California, Mexico have used squid (Todarodes pacificus) for bait. At least through 1966 these vessels were fishing mainly for swordfish, usually at night. It is unknown whether this type of fishing was done subsequent to 311 1966. Catch rates of swordfish taken by the mod- ified gear at night are generally different from the catch rates resulting from standard gear; the reader is referred to Kume and Joseph (1969a) for a discus- sion of this difference. In this report no distinction is made between day and night fishing. Data on the longline catches of the Republics of Korea and of China are from the official reports of the respective fisheries agencies of these countries (Anonymous 1968a, 1969a, 1970a, 1971a). These data have not been included in the charts and graphs presented in this report because the amount that they represent of the total catch is extremely low and highly variable. During 1969 the Korean and Chinese catch of billfish in terms of weight amounted to less than 5% of the total longline catch of billfish from the Pacific Ocean. OVERALL TRENDS IN CATCH AND EFFORT When Japanese longline vessels first began fish- ing in the eastern Pacific in 1956, effort was re- stricted to a narrow region on either side of the equator extending eastward only as far as about long. 120°W (Fig. 1). Effort increased rapidly be- tween lat. 10°N and 10°S of the equator, and by 1961 fishing extended eastward to long. 90°W (Suda and Schaefer, 1965). By the end of 1963 it had reached the mainland of South America (Kume and Schaefer, 1966). It then began to expand rapidly poleward and by 1966 fishing was conducted in al- most the entire region bounded by long. 130°W and the continents and lat. 35°N and 40°S (Kume and Joseph, 1969a). Since 1968 the distribution of effort has remained relatively constant. The first fishing effort by the Republic of China east of long. 130°W occurred in the mid-1960's. It has remained rather restricted to the area east of long. 1I5°W and lat. 5°N and 30°S. Korean vessels fish primarily between long. 130°W-110°W and lat. 5°S-40°S. In order to examine trends in catch rates within areas for which there is a continuous time series of catch and effort statistics, we have divided the east- em Pacific into the 18 areas defined by Kume and Joseph (1969a). These areas represent expansions in the distribution of effort generated throughout the fishery (Fig. 1). Annual estimates of total effort for the Japanese longline fishery are shown in Figure 2. These esti- mates, expressed in millions of hooks set per year within the eastern Pacific Ocean east of long. 130°W, have been adjusted to represent complete coverage. From a low level of about 3.5 million hooks set prior to 1960, effort increased rapidly to more than 60 million hooks by 1964. Since 1964, effort has varied around 50 million hooks set per year. Although the number of hooks set is propor- tional to the total fishing effort exerted in the east- ern Pacific it is not proportional to the actual number of longline sets made because there has been an increasing trend in the average number of hooks utilized per set (Fig. 3). Whereas in the mid-1950's about 1,900 hooks were used per set, in recent years about 2,200 hooks per set have been used. For this reason, in the subsequent analysis, catch per hook will be used as an index of apparent abundance rather than catch per set. For such analysis it is assumed that the spacing of hooks on Figure 1. — Expansion of the Japanese longline fishery into the eastern Pacific Ocean and designation of areas for analytical purposes. 312 Figure 2. — Annual estimates of total longline effort for the Japanese longline fishery in terms of millions of hooks set in the eastern Pacific during 1956-1970. the line does not appreciably affect the catchability of a single hook, although we have not tested this. When the Japanese longliners first began fishing in the eastern Pacific their catches were nearly all tuna (Fig. 4) because very high catch rates of tuna were common in the area in which they operated. As effort increased catch rates of tunas began to decrease rather quickly (Fig. 5). At the same time the demand for billfish (except swordfish) increased as a result of the rapid development of the fish sau- sage and fish ham industry in Japan. The most in- portant ingredients for fish ham and sausage were sailfish and marlin. Another important development related to the billfish fishery took place in about 1966; as Ueyanagi (1972) explains, "Raw meat of striped marlin is considered to be the best quality of billfishes and its price equals that paid for the flesh of the more expensive tunas. The meat of billfishes. however, did not always command high prices. It is only since about 1966 that the price has increased remarkably. This can be attributed to the advance- ment in freezing techniques; in 1966 rapid deep freezing facilities became a standard part of new fishing vessels. This processing method had a great influence on the demand for the flesh of billfishes in Japan, which almost overnight began to be con- sumed as 'sashimi' (raw fish) just as are the other tunas." In response to the increased demand and higher prices for billfish as well as the decreasing catch rates for tunas, the fishery expanded during the early I960's rapidly towards the north and northwest where greater concentrations of striped marlin were found. The northward expansion con- tinued through the mid-1960's and increased catches of marlin were made; additionally the fishery expanded shoreward onto the sailfish grounds. From Figure 4 it is clear that after 1965 almost half the total catch was comprised of billfish whereas prior to that time most of it was made up of tunas. The catch of tunas decreased from a peak of about 1.45 million fish to the present average level of about 0.75 million fish. Catch rates for tuna have likewise decreased by about one-half the initial av- erage levels. The total catch of billfish, as noted, began to in- crease at about the time catch rates of tunas dropped off in 1962 and has continued to increase to the present average level of about 0.6 million fish per year. 150 - /A \ -A 125 TUNAS !? TUNAS AND BILLFISH ,/ \ "" BILLFISH // \ o 100 - A z o 1 \ A /\ z X 3 ^ - II f J ^ / vV'^^-!^ /^%^ M V SB » 60 Figure 3. — Annual average number of hooks per set. 1956 S7 56 S9 GO 61 62 63 64 65 66 67 68 69 1970 YEAR Figure 4. — Total annual catch of tuna and billfish, in mil- lions of fish, by Japanese longline vessels in the eastern Pacific. 313 Figure 5. — Annual average catch per 100 hooks of tunas and billfishes by Japanese longline vessels in the eastern Pacific. It is interesting to note in Figure 5 that the total catch rate, which leveled off in about 1964, is com- prised of about half tunas and half billfish. It is pointed out here that both the catch figures and the catch per effort figures are expressed in terms of number of fish rather than weight. If statistics based on weight were available these trends would be somewhat different. It should also be mentioned that Figures 4 and 5 do not include data for the Korean and Chinese catches and effort. However since their catches are rather minor relative to those of the Japanese, this fact should not alter the results very much. The total annual catches of billfish and tuna taken by Japanese longliners in the eastern Pacific are shown by species, in Figure 6. In the billfish cate- gory, sailfish and shortbill spearfish are combined in one histogram for the reasons noted earlier and they represent the greatest catches in terms of numbers. The numbers of striped marlin caught fol- low closely behind sailfish and shortbill spearfish and in terms of weight far exceed them. The catches of the other species, swordfish, blue marlin and black marlin, are much less. All of the species ex- cept swordfish showed a rapid increase to some maximum, followed by a great deal of variability at a somewhat lower average level. With respect to tunas, bigeye was the most abun- dant species in the catch, followed by yellowfin, albacore, skipjack, and bluefin. The catches of skip- jack and bluefin are extremely low and can be con- sidered incidental. Figure 6. — Total annual catch by species of tunas and marlins captured by Japanese longline vessels in the east- ern Pacific. 314 As with billfish, catches of tunas increased rapidly to a peak then fluctuate about some sUghtly lower level. ANALYSIS AND RESULTS Geographical Distribution The average quarterly catch rate of billfish is shown by species within 5-degree areas in Figures 7 through 12, for the years 1956-1970. Catch rate is expressed in numbers of fish caught per 1,000 hooks. Such figures provide a useful basis for exam- ining the quarterly average distribution of the longline-caught billfish. If catchability is assumed to be constant, then shifts in centers of billfish abundance^ can be utilized to infer migratory be- havior. Striped Marlin The catch and effort statistics show striped mar- lin to be widely distributed throughout the eastern Pacific Ocean during all seasons of the year, occur- ring from about lat. 35°N to 40°S to the coastline of the Americas (Fig. 7). The areas of high relative density which occur near shore are variable among quarters. During the first quarter highest hook rates are near the Revillagigedo Islands, the tip of Baja California, and in the Gulf of California. These ex- pand southward and westward during the second quarter and third quarter. By the end of the third quarter the area of high relative abundance has ex- tended southward to lat. 10°N and westward to long. 130°W. It is during this period when the high- est densities of striped marlin in the eastern Pacific are encountered, centered in the area bounded by long. 125°-110°W and lat. 15°-25°N. During the fourth quarter the area of high marlin abundance diminishes and the striped marlin appear to be found nearer shore. A slight displacement north- ward of the high hook rates from about lat. 25°N to 30°N is observable during the third and fourth quar- ters, most likely associated with the movement of warmer water northward. In the southern area of the fishery striped marlin are relatively abundant as far south as lat. 35°S dur- ing the first quarter of the year. This period repre- sents the southern summer, when warmer waters are displaced southward. As southern waters begin to cool at the onset of the southern winter, the ^Throughout the report "abundance" refers to "apparent abundance." southern boundary of the distribution is displaced northward. This continues through the third quarter during which relatively few striped marlin are found below lat. 20°S. During the fourth quarter as the southern summer begins, striped marlin commence to move southward and are again found below lat. 30°S. Also during the first quarter of the year striped marlin appear to be abundant around the Galapagos Islands and off Colombia and Ecuador. There also seems to be an area of high concentration in the offshore region bounded by lat. 10°-15°S and long. 85°-100°W. During the second quarter there appears to be a general decrease in abundance. However there is a suggestion of a southerly shift in the high- est concentration offish that continues through the third quarter at which time the highest concentra- tions south of the equator are in the general region of long. 95°-115°W and lat. 15°-25°S. By the fourth quarter the areas of greatest abundance are again around the Galapagos and off South America. This pattern of changes in the distribution of marlin sug- gests a shoreward migration during the southern summer and an offshore migration during the southern winter. In an earlier publication Kume and Joseph {1969a) compared the available data from subsis- tence and sport fisheries with those from the long- line fisheries. They concluded that the seasonal dis- tribution of striped marlin as reflected by sport and subsistence fisheries corresponds well with that in- ferred from commercial longline catches. As already noted, striped marlin are found throughout the Pacific Ocean but their abundance is much greater in the eastern half than in the western half of the Pacific. An area of high abundance also occurs in the region bounded by lat. 15°N to 25°N and long. 130°W to 175°E. Whether more than one subpopulation of striped marlin exists is not known. On the basis of their analysis, Kume and Joseph (1969a) noted that it seemed unlikely that striped marlin in the eastern Pacific are comprised of more than a single stock. They did not comment, how- ever, on the relationship of the stock in the eastern Pacific to those farther west. Blue Marlin Blue marlin are captured by longline vessels in the eastern Pacific between approximately lat. 30°N and 35°S (Fig. 8). In the northern areas the distribu- tion of blue marlin does not appear to fluctuate sea- sonally but in the southern areas there appears to be 315 a slight shift to the south during the southern sum- mer, particularly in the first quarter of the year. Only one general area of high abundance of blue marlin occurs in the eastern Pacific, that is in the south between lat. 15°-25°S and long. 110°-130°W, and during the southern summer. Catches of this species in the rest of the eastern Pacific are quite low except for sporadic good catches in the Panama Bight. Few blue marlin are taken in the sport and subsis- tence fisheries of the eastern Pacific and therefore not much data are available on the distribution of ^ f STRIPED MARLIN / QUARTER 2 J / f ^ A t. . ,^0 /^ 1 1 ^ 12 f Vi 6 3! lj :b^ ■7 7 TP TT 14 '•10,^9'" L , 1 2 T \t T To 12 6^ A' ,-«. 1 1 2 3 4 4 4 2 2 2^ V 1 1 1 2 2 2 3 5 3 2' 1 1 1 1 1 1 TT 'i 1 1 1 2 5 2 3^ 1 1 2 2 4 6 T I \ ' 1 1 2 5 "9" 5 3 / N, 2 1 1 1 1 / / / 1 1 2 1 1 / / / / / 1 1 3 1 1 1 / n .1 V n- dC «■ IT- w / r 1 STRIPED MARLIN QUARTER 4 J \ f 1 ^ Ev ^ (( H A 1 13 r Vi 5 9 14 g a ( ^ T 6 TT 17 72" H! ^, 2^ iJ L 7" TT '' 5 2 5 > 5^ / ,-<. 1 2 1 2 2 3 4 2 5 4Si i 1 2 2 3 2 3 3 5 6 5 14 2 2 2 3 3 2 3 T" SI '[ . 1 3 2 3 3 4 3 4 1^ 1 2 3 5 3 1 ^ 1 1 1 2 2 3 6 1 / 1 N, 3 4 3 4 5 6 2 3 2 4 3 3 4 2 / / / 2 / / / / / j 2 / / / / / / / / A A / / L Figure 7. — Average number of striped marlin caught per 1,000 hooks by Japanese longline vessels in the eastern Pacific by quarters, 1956-1970, by 5-degree areas, a. First quarter, b. Second quarter, c. Third quarter, d. Fourth quarter. 316 this species from those fisheries. Sport catches of blue marlin have been reported by Rivas (1956) from Baja California, Acapulco, Mexico, and Pifias Bay, Panama. Sport catches have also been re- ported off Ecuador (Anonymous, 1955) and off Peru (Morrow, 1957). Blue marlin occur throughout the Pacific Ocean but their abundance is generally greater in the west- ern and west-central Pacific than in the eastern Pacific, apparently the reciprocal of the distribution of striped marlin. During the southern spring there appears to be a shift in the area of highest hook ^ f BLUE MARLIN " OUARTCR 1 FTl, r^ \ [£) 6 "4" 6 "T 2 1 1 / / 2 2 1 1 1 1 1 / [ l_ w ■s— •f— •' «• or ■r „ V BLUE MARLIN IT / QUAHTER 2 / \ / \ t> ,.^t\ / / ^ < \^ 'oS hi / 1 "'T'^ I 1 1 ' \ 1^ [TS ,^ 1 1 1 1 1 1 2^ n 1 1 1 1 1 1 1 0* 2 1 1 °< r 1 1 1 1 1 I ,^ \ 1 / \ 1 1 1 / > 1 1 / / / / / / / j / / g L I -^ f BLUE MARLIN " QUARTER 3 \ \ \ Q ,^.( y / ( \^ / 0* °^ K -7 2 > H> \^ I / 2 2 1 1 1 l" [A / ^<- 2 2 1 1 1 1 1 ^3^ 1 1 1 1 1 1 1 1 1 1 1 °i % 1 I 1 1 0^ ^ / 1 / / / / / / / / / / / / i I— U L " / ^ BLUE MARLIN •*■ / / QUARTER 4 1 r^ \ — / X Cx --V- f ^ /o 1 ^'■ ( i \^ — 0^ °^ ^ h 1 cr>o L / $■ \\\ i -«. 2 1 1 I 1 1 1 ^^ V 1 1 1 1 1 \ 1 1 2* 1 1 1 1 1 °( t 1 1 1 1 0^ \ 1 1 A \ 3 3 3 1 / > 2 1 1 1 1 / 2 1 / / i 1 / / / / / j / / / / / I / / / / u t I ■ Figure 8.— Average number of blue marlin caught per 1,000 hooks by Japanese longline vessels in the eastern Pacific by quarters, 1956-1970, by 5-degree areas, a. First quarter, b. Second quarter, c. Third quarter, d. Fourth quarter. 317 rates from the northwest-central Pacific to the southeast Pacific. Hook rates remain high in the southeast through the southern summer, then shift northward again in the southern fall. It is the south- eastern shift in apparent abundance which contrib- utes to the high catch rates in the eastern Pacific area of lat. 15°-25°S, long. 110°-130°W during the southern summer. On the basis of the distribution data examined in this report it would be impossible to determine whether the blue marlin of the eastern Pacific are from a single stock which is separate from those farther west. However Anraku and Yabuta (1959), who examined more extensive information, consid- ered the blue marlin of the Pacific to be a single population which undergoes widespread intermin- gling. Black Marlin Black marlin are caught in negligible quantities in the eastern Pacific Ocean. Their greatest abun- dance is in the southwestern part of the Pacific Ocean near eastern Australia and New Guinea. Their abundance decreases rapidly toward the east, and is very low east of long. 150°W. Hook rates in the eastern Pacific are consistently less than one fish/ 1,000 hooks. Because of the low catch rates in our area of study quarterly charts are not shown for black mar- lin. However an average annual distribution of hook rates by 5-degree areas for the years 1956-1970 is shown in Figure 9. The area in which black mar- lin are generally captured in the eastern Pacific can be defined as that area lying within a diagonal line extending from about the middle of Baja California southwest to where the 130th meridian intersects the lat. 20°N line of latitude, and a diagonal line extending from the Peruvian shore at about lat. 10°S to where the 130th meridian is intersected by the lat. 35°S line of latitude. Howard and Ueyanagi (1965) discuss the general distribution of black marlin throughout the Pacific and Indian Oceans. For the eastern Pacific they utilize information from subsistence and sports fisheries to describe the nearshore seasonal dis- tribution. They report black marlin to occur as far south as northern Chile and in the north to about Cape San Lucas. In their discussions of the population struc- ture they consider the black marlin of the eastern Pacific to be a separate stock from those farther v A f ANNUAL CATCH RATES BLACK MARLIN V / i rTl....... . r^ / fol < 1 fish/ 1000 hooks 9 1 / r // '^f^ ^ f \ / o\ ( ^ ■o->.o^ ^ ZJ / "^o.r .-<■ T (j'sr ,0 A \ 0^ \ \ K > / / / / / 1 / / / / / / / j / / / / / / /, / I } / / / / / * I ^ Figure 9. — Annual average number of black marlin caught per 1.000 hooks by Japanese longline vessels in the eastern Pacific by 5-degree areas, 1956-1970. west. They also suggest that the fish which occur off southern Peru and northern Chile may be dis- tinct from those taken near shore but farther north. Sailfish and Shortbill Spearfish The quarterly distribution of sailfish and shortbill spearfish is shown in Figure 10, averaged over the years 1956-1970. These two species are not sepa- rated in the figure because most commercial long- line vessels do not differentiate between them in their catch records. Some idea of the relative dis- tribution of the two species can be obtained, how- ever, by examining the results of exploratory and research cruises in the eastern Pacific Ocean. Dur- ing such cruises the two species are differentiated in catch records. In their analysis of the billfish fishery of the eastern Pacific, Kume and Joseph (1969a, 1969b), used the results of nine exploratory cruises to differentiate the geographical distribution of the 318 two species. In Figure 12, we have utilized the data presented by Kume and Joseph (1969a, 1969b) as well as data from Royce (1957), Mais and Jow (1960), Shomura^, and Anonymous (1970c), to plot the distribution of sailfish and shortbill spearfish by 5-degree areas. The sailfish comprise nearly 100% of the catch of the two species shoreward of a line drawn from the intersection of lat. 10°N and long. 1 15°W to the intersection of lat. 5°S and the coast of Peru. As one moves seaward of that diagonal the ~^ r SAILFISH AND SHORTBILL SPEARFISH QUARTER 1 \ [5]<. % — / h / a B .>o 1 ^ / r h 88 M u 1 1 / 1 2 L k 1 1 4 4 M 97 ^8^63 ,^ 1 1 1 3 T^7V w 1 2 1 1 2 6 13 1 i » 1 9 ^ \ 1 1 1 / A 1 1 1 3 3 1 / ^ 1 1 1 2 2 2 3 1 j 2 2 / 1 / / „ / / / 1 i I— — L L M- =^ ^ s= SAILFISH Ar4D "^ &= t / ( QUARTER 2 ^ / \ I / b — fl '^ ^ ^ < \^ 2'^ 4\ ■^ 1 1 1 3 46,59 lT7 1. L, 1 1 1 4 48' 631 g j -^ 1 1 1 3 7 14 5 % 1 1 2 3 1 i 1 1 1 1 3 0^ \ 1 1 1 // \ 1 1 1 1 / N 1 2 4 2 1 / / / / / / / — / / / / „ r '-^ ^ SAILFISH AND vr SHORTBILL SPEARFISH OIlflRTFR ^ r^ \ f \ . ..^(C 1 / ^ t \~ 1 2 1 2" % tttM^ -^ / 1 1 9 "3^4^53 i L, 3 1 1 I 6 42157^21. ^ «-«. 1 1 2 5 8 g 1 1 2 2 5 1 1 - 1 1 1 1 1 °l — 1 1 1 1 1 1 >> 1 1 2 I 1 / / / / / / / / \ / / / / / / i L 1 — 7 p SAILFISH AND fr / SHORTBILL SPEARFISH r-^ ; — / ^ ^ .^fl ^ 47 < ^ 1 / 1 1^ %, -7 1 1 1 18 1 83 jd^-^ L / / 2 4 51 S 46 [62 1 1 1 1 1 1 1 7 7 2V 1 1 2 3 4 1 1 i 1 1 1 1 1 1 1^ 1 1 1 I 1 1 1 2 1 2 2 / 35 \ 1 2 2 2 2 / 1 1 1 1 1 / / 1 / / / / 1 / 1 / / A / / / / f / / / / / z -1 Figure 10. — Average number of sailfish and shortbill spearfish caught per 1,000 hooks by Japanese longline vessels in the eastern Pacific by quarters, 1956-1970, by 5-degree areas, a. First quarter, b. Second quarter, c Third quarter, d. Fourth quarter. 319 species composition changes rapidly to shortbill spearfish. Turning again to Figure 10 it is apparent that sail- fish are encountered all along the coastal waters of the Americas between about lat. 30°N and lat. 30°S. They are extremely abundant along the coast of central and southern Mexico and Central America, reaching their greatest abundance throughout the winter months between lat. 20°N and the equator. There appears to be a movement of fish northward with the displacement of warm waters to the north during the summer and fall. During the southern » ( SWORDFISH »• QUARTER 1 1::' ? / ^ a ^"- -~- ^ ^ / ^ 4 Ea>« 1 \^ 1 7^ h u / Jrv u/ I 1 1 / 1 PN' -«. ^ X 1 1 1 1 1 1 1 1 1 1 / 1 1 1 8 1 rjn 1 \ 1 1 1 1 1 1 1 1 > 2 1 1 / 1 1 [ -J ^ J SWORDFISH n / ] QUARTER 2 1 r^ / ) / A Cv r ^ X / ° ^ 2 r - \1 / I ^ 3\ ( / ^ / / 1 h °1 r,0 I / 1" '2, 1 ^ ^ 1 1 1 1 1 1 1 1 7 1 A 1 s N / / 1 1 / 2 / / / / / 1 / i L L u L r ^ f SWORDFISH ^ QUARTER 3 \ f' / \ &. -'^ / / X \ r < 1^ ^ / ^^ \ 1 .-<■ — 7 7 1 Yi. ' 0- [aI ' 1 1 1 1 1 1 ^o^y" 2 1 1 1 : 1 1 1 2 2 1 o' 1 2 ^ T > — 1 1 / 1 1 I 7 - - 7 \ 1 1 2 - / — xr 1 — 7 r JWOHDFISH " / QUARTER 4 — r Xt. _ ,^ n c — 2 7 i A A A A A • • D O o Nj A A A A A A n o o o ■ A A A A A A D O O o o A A A A A o D A A A A A o O o o D o o A A A A A L Ul J_ J LJ„ ^ f DOMINAN r SPECIES =; ' — ^ F f E= DOMINANT SPrclES "^ = -■ J OUARTER 3 1 r>- • 1 QUARTER 4 1 r^ } — J ^ o ^ b .^C ^ o ^1 ^A Q - — - fl o • % ■ r \^ o • A •l ■ f \} D • • •' ^ / "7 o • • •' *1 hr 1 • • • • • kr^ u I • • • • ■ M u L o o • • D • ■ * m L J r^ • • D • D ■ ■ m n ,-«■ o o o O O O n n 3 m v o o O o D D o a D ito « o o o o oo o o o q i o O o O O o o O o i o o o o o o o o o o o O O O o • O 1 o o o D o o o o n \ o o O o O O o o O o^ \ A A A A A A A A A D D \ A o O o □ O o A D A «l A A • A A A A o O > A A A A D A D D O o ■ N, A A o • A A O A A ^ D A • O D O o A A A A A A o o o / A A A D D D A A O o o / A A A A A A A 1 A A A A O o o I A I A A A A A A ^ i ^ 1 1 L Figure 13. — Dominant species of tuna and billfish in the eastern Pacific by quar- ters, averaged for the years 1956-1970. by 5-degree areas, a. First quarter, b. Second quarter, c. Third quarter, d. Fourth quarter. 322 grow very rapidly, and are highly fecund. They most likely compete for the same kinds of food and, to some extent, living space and the billfishes prey on tuna. Tunas and billfishes are caught in the same areas at the same time; it is not unusual to capture five or six different species of tuna and billfish on the same set of the longline gear. Because of the close relationship of these species it is important to understand their community struc- ture. Such information is a necessary antecedent to the rational utilization of billfish resources. In order to examine the community structure of tunas and billfish in the eastern Pacific, as reflected by long- line catches, in terms of the dominant species in the catch we have prepared Figures 13 and 14. For the purposes of this examination the species exhibiting the highest hook-rate in each time-area stratum is considered the dominant species in the catch. We have prepared two sets of data. The first set (Fig. 13) includes all of the tunas and billfishes as a com- munity, and the dominant species is whichever one, tuna or billfish, exhibits the highest hook rate. The dominant species are shown by quarter of the year and 5-degree area. In the second set of data only the billfishes are considered as members of the community. In this case the dominant species is that species of billfish which exhibits the highest hook rate within a time- area stratum. The dominant species of billfish in the catch is shown by 5-degree area and quarter (Fig. 14). Tunas and Billfishes Of the eight species examined in Figure 13, bigeye tuna appears to dominate throughout all four quarters of the year. In each quarter they are domi- nant between about lat. 10°N and 10°S and eastward to about long. 100°W. East of long. 1(X)°W they are dominant generally between about lat. 5°N and 5°S to the mainland. These limits appear to vary some- what seasonally. During the southern summer, bigeye appear to be displaced farther south along with an associated displacement of warmer water. A pocket of bigeye seems to persist in the area bounded by approximately lat. 15°-30°S and long. 75°-95°W through the year. The next most dominant species in terms of ex- tent of distribution, but not necessarily in terms of catch, is albacore. Except in a few rare instances albacore are taken by longline in the western Pacific only south of about lat. 5°S, probably in waters of the South Equatorial Current. This species is con- sistently dominant in the catch south of lat. 15°S and west of long. 105°W. During the first and fourth quarters of the year, the southern summer, when warm waters extend farther south, the northern edge of the albacore distribution is displaced south- erly to about lat. 15°S. During the southern winter (second and third quarter) their distribution extends more northerly to beyond lat. 10°S. Yellowfin tuna are the next most important dom- inant species of tuna in terms of extent of dis- tribution. This species is the second most important tuna captured in the eastern Pacific in terms of weight landed. The extent of their distribution in terms of dominant species is much more restricted than bigeye and albacore. Yellowfin are dominant in a narrow band throughout the year between lat. 5°N and 15°N. They also appear sporadically as the dominant species in the southern hemisphere off northern Peru. Very small quantities of southern bluefin are cap- tured in the eastern Pacific Ocean, and in only two areas do they appear as the dominant species (Fig. 13d). Their occurence as the dominant species at about lat. 40°S is to the south of all other species of tuna and billfish shown in the figures. The billfishes are generally more dominant in the inshore areas than are the tunas, especially north of the equator. Of the billfishes the striped marlin is the most dominant. During the first and second quarters they are dominant in the north, in the area west of long. 105°W and north of lat. 15°N. This area of domi- nance appears to expand in all directions in the third and fourth quarters. In the southern area they are more dominant during the first and second quarters, occuring in the waters off Ecuador and northern Peru as far as long. 105°W. Their dominance di- minishes remarkably during the third and fourth quarters when their few dominant areas appear generally to be farther offshore. The sailfish show a very consistent pattern as the dominant species during all four quarters within about 500 miles of the coast between lat 20°N and the equator. Swordfish occur as the dominant species in only a single 5-degree area off Baja California during the first and fourth quarters. Generally tunas are the more dominant species of the high seas westward of a line paralleling the coast at about 600-1000 miles offshore whereas billfish are dominant to the east of this line. 323 Billfishes To examine more closely the distribution of dom- inant species of billfish only, we have prepared Fig- ure 14. The distribution of dominant species can be con- veniently broken into four general areas. In the in- shore area, within about 500 miles of the coast, be- tween lat. 20°N and the equator, sailfish are domi- nant throughout the year. Even when included with tunas (Fig. 13) the sailfish remain dominant. In the offshore area between about lat. 10°N and -^ f DOMINANT SPECIES BILLFISH ONLY QUARTER 1 ^. • • STRIPED MABLIN ■ SAILFISH a SHORTBILL \ ^ SPEARfiSH A SWORDFISH • • ^ ^ »„.„.„,. if i '• Ml • • ^ *1 ^ "^ ■ • • I ■ • • ifr m L. -* ^■ ^ • tt¥ ¥ ¥ ¥ if- ■ * ¥ ¥ • •f t ¥ ■*■ ■^ i \ -- -^ ¥ * ^ * ▲ ^ * ¥ r> ¥ ^ * f ■ • / ▲ 1 1 y 1 ^ f DOMINANT SPECIES QUARTER 2 ^ \ f — ^ ft, . ,^fl ^ i • n \) ^ *) 'J "7 M L • A- m i l^ * ^ ■, ■ M ^ * •^ \ • \ ▲ > ^ ▲ ▲ ▲ A 1 1 / n ± ^ f DOMINANT SPECIES »■ BILLFISH ONLY \ f - h c\ — /■ y ^a f \^ S'' ♦l h » W L r ^ R' ^«. ■ * ■ • ■, s • A t • A^ \ - --" • ▲ A \ • ▲ ▲ N, ▲ ▲ A ▲ ▲ ▲ / A A A j A / h I ir »■ a ^ — ; «r , r ■ K 5C N F DOMINSNT SPECIES ' "■ • BILLFISH ONLY \ ! *i h -— ^ ^ i ■ f \^ ^ ^ [ J Ij *f, L r it m --«. * m W • i f^ * A \ ■ «; A ■ > _ ■ A ■ A ■ A if 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- em Pacific reaches to about long. 105°W during the first quarter, decreasing to about long 1 IO°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 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 I. 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, 1 1, 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 fishy 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 quarterty 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 325 8.0 6.0 4.0 2.0 AREAS 14. 15, 16. 17 ■ I ■ . ■ ' ■ ■ ■ I ■ ■ • I ■ ■ ■ ' • AREAS 9, II, 12 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 fishy 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 fishyi,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 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. 326 Abundance began to decline in about 1960 and continued to do so until 1964-1965 when it reached about 0.8 fish/l ,000 hooks. By 1966. abundance had dropped to about 0.5 fishy 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 SBEas 5,6 a 9 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. 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 1 1 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 327 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: SWORDFISH NORTH OF 10° NORTH 5 28.6 5 + 6+9 53.1 1965 329.9 366.0 173.6 199.7 131.3 245.4 208.9 359.7 72.7 149.8 100.5 210.1 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. Figure 18. — Relationship between catch in numbers of fish, catch per 1,000 hooks and effort in millions of hooks for sailfish in areas 5, 6, and 9, 1965-1970. SWORDFISH SOUTH OF 10° NORTH Figure 19. — Quarterly hook rate of swordfish expressed as catch in numbers per 1.000 hooks, for areas north and south of long. 10°N. The relationship between catch, effort, and catch per effort for sailfish taken during 1965-1970 in areas 5, 6. and 9 is shown in Figure 18. In the lower panel of the figure a negative relationship is evident between catch per effort and effort. This figure sug- gests, as is expected, that increasing effort will likely result in reduced catch rates. In the upper panel no clear relationship is apparent between catch and effort. Catch for the years 1956-1970 fluc- tuates about some average which is independent of fishing effort. This would suggest that catches would not be expected to increase on the average as effort is increased. Swordfish For the purposes of examing trends in abundance catches of swordfish (which occur throughout the eastern Pacific but are concentrated in the north in area 2 and in the south in areas 9. 12, and part of 18) have been divided into two groups, one north of lat. 10°N and the other south of lat. 10°N. The catch rate may be somewhat confusing in that the longlin- ers have fished at night, utilizing squid as bait, on the northern swordfish grounds since 1964. Night fishing also most likely takes place on the southern grounds but we have no data on this. This form of fishing increases catch rates by a factor of two on the average. In Figure 19 the number of swordfish caught per 1.000 hooks is shown for the area north of lat. 10°N (upper panel) and for the area south of lat. 10°N 328 (lower panel) by quarters, 1963-1970. Hook rates on the average are lower in the south than in the north, even after allowing for differences in efficiency due to setting time. Catch rates also seem to be more variable in the north than in the south. There is a marked seasonal pattern, with highest hook rates generally during the fourth quarter in the north but such a pattern is not evident in the south. The fourth quarter peaks do not appear to be related to corresponding variations in fishing effort and vessel concentration, but likely represent changes in catchability. Slight upward trends in catch rates are detectable in both the north and the south, probably due to increased efficiency as a result of increased night sets and concentration on the more productive swordfish grounds. The catch of swordfish (Fig. 6) on the average has increased steadily since 1956. The peak year was 1969 when about 1 12.000 swordfish were taken and effort was at a maximum. Both effort and catch decreased in 1970 but catch per effort in the north did not decrease. In the south, a decrease in catch per effort was noted during 1970. Before catch per effort can be used as a very good indicator of swordfish abundance it will be neces- sary to adjust all data for the effect of night sets. It is also essential that the amounts captured by coastal fisheries (which may be substantial) be ac- counted for in the analysis; for example during 1970, nearly one million pounds of swordfish were taken in the California surface fishery. Without the inclusion of such data it is useless to speculate on interpretation of the data represented herein as far as stock assessment analyses are concerned. CONCLUSIONS AND RECOMMENDATIONS The importance of billfishes to man has been abundantly demonstrated and documented. Large and important longline fisheries exist for billfishes throughout the oceans of the world, especially in the eastern Pacific Ocean. Important sport fisheries upon which the economy of local communities de- pend exist for billfishes, not to mention the impor- tant recreational aspects of the fisheries to a large segment of the population. Many subsistence fisheries depend upon billfishes as their sole supply of raw material. To insure rational utilization of this resource (ra- tional in this sense implies some sort of sustained harvests for all categories of use) the effect of man's exploitation on subsequent recruitment and average size of the stock needs to be analyzed. This has not been done for the billfishes of the eastern Pacific Ocean, nor for the billfish of the Pacific Ocean gen- erally, nor for any other ocean to our knowledge. In this paper we were unable to comment, except in a very general way for some species, on the con- dition of the billfish stocks in the eastern Pacific. The reasons for this were primarily due to the fact that the statistical data were limited, the area of study extended to only long. 130°W, and vital statis- tics concerning the population were not available. If it is the desire of mankind to manage the fisheries for billfish so as to insure sustained har- vests, at whatever level is deemed desirable, then certain basic data and studies are needed. Some idea of the relative distribution of the population under study needs to be established. If the popula- tion is divided into distinct units on the basis of biological characteristics and/or distributional characteristics of the fish and fishery, then this must be determined; these units cannot be estab- lished on the basis of jurisdictional limits. For each of the population units, estimates of the total catch are needed; these should include catches from commercial, sport, or any other fishery which might take meaningful quantities of billfish. Some idea of fishing mortality is required; this is generally esti- mated as a function of fishing effort. Therefore es- timates of fishing effort for a major share of the catch are needed as an index. The size composition of the catch by strata of time and area are useful for conducting studies of growth rates and mortality rates, and are a necessary ingredient to the deter- mination of the relationship between stock size and subsequent recruitment. A sampling program to ob- tain such measurements should include samples from all important fisheries. From the discussions presented in this report it is clear that all six of the billfish which occur in the eastern Pacific Ocean are found all the way across the Pacific. The longline fishery which takes these six species exploits nearly every 5-degree square over the range of each species. Evidence from bill- fish tagging demonstrates that some species un- dergo extensive migration in the Pacific Ocean (Mather, 1969; James L. Squire, Jr. pers. comm.). Such migrations have been demonstrated in other oceans as well (Mather, 1969). It is clear that the scope of billfish studies needs to be extended throughout the Pacific Ocean. Such 329 studies must include all important fisheries. At the present time integrated broad-scale studies of bill- fish have not been conducted, nor are they appar- ently underway. This situation may be due in part to the lack of a well-defined set of goals or objectives for billfish research. Such a set of goals would necessarily have to be responsive to the different needs of the various user sectors of the fishery for billfish. To define these objectives and goals there needs to be an international platform for the discussion of these goals and objectives, a platform in which the proper questions can be framed and asked. By asking the proper questions, such goals and objectives, which are responsive to the needs of all individuals, com- munities, and nations, can be formulated. There are a number of platforms which can serve as a mechanism for formulating an integrated ap- proach to billfish studies but it would indeed be unfortunate if we did not take advantage of this Symposium to discuss the subject. ACKNOWLEDGMENTS The authors wish to express their gratitude to the Director of the Far Seas Fisheries Research Laboratory, Osamu Kibesaki, for allowing us to utilize certain of their preliminary data. Special gratitude is also extended to Akira Suda and Susumu Kume of the same laboratory for their as- sistance in preparing the data for analysis. LITERATURE CITED ANONYMOUS. 1955. Lou-Marron-University of Miami Billfish Expedition — Preliminary Report for 1954. Univ. Miami. Mar. Lab., Coral Gables, 65 p. 1968a. Report on survey of production and marketing of Taiwan's tuna longline fishery — 1967. [In Chin, and Engl.] Taiwan Fish. Bur., 157 p. 1968b. Annual report of effort and catch statistics by area on Japanese tuna long line fishery — 1966. [In Jap. and Engl.] Fish Agency Jap.. Res. Div., 299 p. 1969a. Report on survey of production and marketing of Taiwan's tuna long line fishery — 1968. [In Chin, and Engl.] Taiwan Fish. Bur., 271 p. 1969b. Annual report of effort and catch statistics by area on Japanese tuna longline fishery — 1967. [In Jap. and Engl.] Fish. Agency Jap.. Res. Div.. 293 p. 1970a. Report on survey of production and marketing of Taiwan's tuna long line fishery — 1969. [In Chin, and Engl.] Taiwan Fish. Bur., 285 p. 1970b. Annual report of effort and catch statistics by area on Japanese tuna longline fishery — 1968. [In Jap. and Engl.] Fish. Agency Jap., Res. Div., 283 p. 1970c. Report of research boat Shoyo -ma ru, for 1969 fiscal year — eastern Pacific Ocean and western Atlantic Ocean. [In Jap] Suisan-cho, Fish. Agency Jap., 103 p. 1971a. Yearbook of catch and effort statistics on Korean tuna longline fishery — volume I for 1966-1970. [In Korean and Engl.] Off Fish., Seoul, Fish. Prod.. Stat. Div., 332 p. 1971b. Annual reportof effort and catch statistics by area on Japanese tuna longline fishery — 1969. [In Jap. and Engl.] Fish. Agency Jap.. Res. Div., 299 p. 1972. Annual report of effort and catch statistics by area on Japanese tuna longline fishery — 1970. [In Jap. and Engl.] Fish. Agency Jap., Res. Div., 326 p. ANRAKU, N., and Y. YABUTA. 1959. Seasonal migration of black marlin. [In Jap., Engl, summ] Rep. Nankai Reg. Fish. Res. Lab. 10:63-71. BRAVO. I., and J. C. GONZALES. 1967. Una bandera cubana en el Paclfico. [In Span.] Mar Pesca, Inst. Nac. Pesca, Cuba 20:32-39. CHERNYI, E. I. 1967. Ob okeanologicheskikh usloviiakh formirovaniia promyslovykh skoplenii parusnikov (Histiophorus orien- talis) v zalive Teuantepek. [In Russ.] Izv. Tikhookean. Nauchno-Issled. Inst. Ryb. Khoz. Okeanogr. 61:11-20. FREY. H. W. (editor). 1971. California's living marine resources and their utiliza- tion. Calif. Dep. Fish Game [Sacramento] 148 p. HOWARD, J. K., and S. UEYANAGI. 1965. Distribution and relative abundance of billfishes (Isliophoridcie) of the Pacific Ocean. Stud. Trop. Oceanogr. (Miami) 2, 134 p. KATO, S. 1969. Longlining for swordflsh in the eastern Pacific. Com- mer. Fish. Rev. 31(4):30-32. KUME, S.. and J. JOSEPH. 1969a. The Japanese longline fishery for tunas and billfishes in the eastern Pacific Ocean east of I30°W. 1964-1966. [In Engl, and Span] Bull. Inter-Am. Trop. Tuna Comm. 13:277-418. 1969b. Size composition and se.\ual maturity of billfish caught by the Japanese longline fishery in the Pacific Ocean east of 130°W. [In Engl.. Jap. summ] 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 Engl, and Span] Bull. Inter-Am. Trop. Tuna Comm. 11:10.3-170. MAIS, K. F..andT. JOW. 1960. Exploratory longline fishing for tunas in the eastern tropical Pacific, September, 1955 to March. 1956. Calif Fish Game 46:117-150. MATHER. F. J.. III. 1969. Long distance migrations of tunas and marlins. Underwater Nat., Bull. Am. Littoral Soc. 6(1):6-14, 46. MORROW, J. E. 1957. Shore and pelagic fishes from Peru, with new records and the description of new species of Splioeroides. Bull. Bingham Oceanogr. Collect., Yale Univ. 16(2):5-55. NAKAMURA. I.. T. IWAI. and K. MATSUBARA. 1968. A review of the sailfish. spearfish, marlin and swordfish of the world. Misaki Mar. Biol. Inst.. Kyoto Univ., Spec. Rep. 4:95 p. [In Jap., Engl, transl. in press.] 330 NOVIKOV. N. t-.. and E. 1. CHERNYI. 1967. Perspektivy sovetskogo promysla v vostochnoi chasti Tikhogo okeana. [In Russ.] Rybn. Khoz. 43(3);5-7. RIVAS. L. R. 1956. The occurrence and taxonomic relationships of the blue marlin (Makira ampla Poey) in the Pacific Ocean. Bull. Mar. Sci. Gulf Caribb. 6:59-73. ROYCE, W. F. 1957. Observations on the spearfishes of the central Pacific. U.S. Fish Wildl. Serv.. Fish. Bull. 57:497-554. SHIMADA, B. M. 1962. Results of long-line fishing. Limnol. Oceanogr.. Suppl. to Vol. VII, 1962:xlii-xliii. SUDA, A., and M. B. SCHAEFER. 1965. General review of the Japanese tuna long-line fishery in the eastern tropical Pacific Ocean 1956-1962. [In Engl, and Span.] Bull. Inter-Am. Trop. Tuna Comm. 9:307-462. UEYANAGl, S. 1972. Billfishes — status of the resources and some research problems. FAO (Food Agric. Organ. U.N.) Fish. Rep. 118:13-17. WILSON, R. C, and B. M. SHIMADA. 1955. Tuna longlining: results of a cruise to the eastern tropical Pacific Ocean. Calif. Fish Game 41:91-98. YUROV. V. G.. and J. C. GONZALEZ (KH. K. GON- SALES). 1971. O vozmoshnosti promysla parusnika v vostochnoi chasti Tikhogo okeana ( Possibility of developing a sailfish fishery in the eastern Pacific Ocean). In: Sov. Kubin. Ryb Issled.. Pishch. Prom-st".. Mosc, p. 104-110. [In Russ., Span, summ.] (Engl, transl. by W. L. Klawe, 1972, Inter- Am. Trop. Tuna Comm., 11 p.) 331 Billfish Fishery of Taiwan H.C. HUANG' ABSTRACT Billflsh landings made by Taiwan fishing vessels from 1962 to 1971 were analyzed and described briefly. Billfishes are commercially harvested in Taiwan by deep-sea and inshore longline fisheries and the harpoon fishery. The important species caught include swordfish, striped marlin, blue marlin, black marlin, and sailfish. The deep-sea longline fishery has developed rapidly since 1954 and the landings of billfishes have increased accordingly. Fishing operations have covered the major fishing grounds of the Pacific, Indian, and Atlantic Oceans. The inshore longline fishery still confines its activities to waters around Taiwan; billfish landings made by this fishery fluctuate annually. Billfishes are commercially harvested in Taiwan by the deep-sea and inshore fisheries. In the deep- sea fishery, the longline is used exclusively to catch tunas, as well as billfishes. The principal gears used in the inshore fisheries to take tunas, billfishes, and other large pelagic fishes are the longline and har- poon. Gill nets and set nets are also used occasion- ally to capture billfishes that enter the coastal and inshore waters of Taiwan. Longline fishing was in- troduced in Taiwan by Japanese fishermen in 1913. For many years after its introduction longlining was limited to the coastal and offshore waters of Taiwan. From 1913 until 1954, the fleet consisted mostly of vessels of less than 50 tons. Since 1954, the size of the fleet, as well as the average tonnage of vessels, has increased rapidly. Vessels over 50 tons, classified as "deep-sea longliners"" by the Taiwan Fisheries Bureau, have expanded their op- erations from the traditional waters off Taiwan to waters as far distant as the Indian, South Pacific, and Atlantic Oceans. Vessels of less than 50 tons, classified as "inshore longliners," still remain in the offshore waters around Taiwan. In 1962, there were only 42 deep-sea longliners totaling 6,634 gross tons in Taiwan, but by 1971 the fleet had increased to 457 vessels and totaled 99,217 gross tons. In order to meet the practical require- ments of fishing in distant waters, many foreign ports located close to the important fishing grounds 'Taiwan Fisheries Bureau. 8, Isl Section. Chung Hsiao East Road. Taipei. Taiwan. have been used since 1954 as overseas supply bases for the longliners. At these overseas bases the long- liners are able to replenish supplies, effect repairs, and sell the fish catch locally or transship it for export. The tremendous development of this deep- sea fishery is attributed to the growing profit of the industry, as well as the encouragement given by the government. The inshore longline fishery has contained be- tween 600 and 800 vessels since 1962. The vessels range in size from 5 to 50 tons, with the most typical size at about 30 tons. From time to time, the inshore longline fleet shifts from one fishery to another. The harpoon fishery for billfishes was introduced in Kao-hsiung, a southern port of Taiwan, by the Japanese in 1913. Later, the fishery gradually ex- panded from Kao-hsiung along the east coast of Taiwan to Keelung in the north, and the fishery covered the whole of the Kuroshio Current area near Taiwan. The harpoon fishery has been limited to waters about 30 miles from home port and the fleet has kept its size between 150 and 350 vessels from 1962 to 1971. SPECIES OF BILLFISHES The principal species of billfishes exploited by the Taiwan fisheries include: 1. Swordfish, Xiphias gladius. In Chinese the swordfish is called "Chien Ch'i 332 Table 1. — Annual landings (in metric tons) of billfish made by the various fisheries in Taiwan, 1962-1971. Deep-sea Inshore Year Total longline longline Harpooning Other -(metric tons) 1962 9,027 1,501 4,716 2,648 162 1963 10,915 2,088 5,746 2.864 217 1964 9,167 1,973 4,492 2,516 186 1965 8,667 1,655 4,361 2.344 307 1966 10,404 2,654 4,819 2.618 313 1967 11,297 3,698 5,101 1 ,995 503 1968 16,012 6,363 6,961 2,260 428 1969 17,994 8,691 6,998 1 .995 310 1970 15,502 8,060 5,203 1,981 258 1971 16,573 8,760 5,640 1 ,865 308 Yii"; also called "Tinmankhu" or "Ki Hi Khii" by local fishermen. Swordfish are pelagic, circiimtrop- ical fish of worldwide distribution. In Taiwan, swordfish are caught in waters along the east and south coasts, mainly by harpoon and longline gear. Occasionally, swordfish are taken by gill nets dur- ing the northeast monsoon season from October to April. During the fishing season, swordfish often swim and bask near the water surface, exposing the caudal and dorsal fins and sometimes jumping out of the water. These fish are not easily disturbed, and with these habits, swordfish are easily spotted by the harpoon fishermen. The swordfish grows to a size of 4.5 m in length and over 500 kg in weight. Fish weighing 140 to 180 kg are considered large. In Taiwan the swordfish is valued as an excellent food fish and is consumed as raw fish (sashimi) or fried with salt. 2, Striped marlin. Tetraptiirus aiidax. In Chinese the striped marlin is called "Cheng Ch'i Yij"; also called "An-bah Ki Hi"" by local fishermen. Striped marlin are found throughout the tropical Indo-Pacific waters. In Taiwan this species occurs around the island throughout the year and is caught mostly by the harpoon and longline fisheries, principally in the spring and summer months in the Kuroshio Current area located along the east coast of Taiwan, This species usually swims near the surface in small groups with their caudal fins exposed. Fish weighing 100 kg are occa- sionally caught: however, fish of 40 to 60 kg are most common in the Taiwan catch. It is hypothesized that striped marlin of this population spawn in the South China Sea near Taiwan during the month of May. After spawning striped marlin migrate northward. The so-called "Taiwan striped marlin", Makaiia fonnosana (Hirasaka and Nakamura), is consid- ered to be the juvenile of T. aiidax. The flesh of striped marlin is reddish and rich in flavor; the species is considered an excellent food fish by the Chinese people, 3, Blue marlin, Makaira nigricans. In Chinese the blue marlin is called "Hei-pi Ch'i Yii"; also called "O-phe ki Hi"" by local fishermen. The blue marlin is an oceanic species which is widely distributed in the Pacific and Indian Oceans. In Taiwan, fishing for blue marlin by longline and harpoon is carried out year-round: however, effort is concentrated during the months of February, March, and September. It is known that blue marlin spawn in June in waters east of Taiwan, This species reaches 3 m in length and 500 kg in weight. Like the striped marlin, the blue marlin is consid- ered a delicacy by the Chinese people, 4, Black marlin, Makaira indica. In Chinese the black marlin is called "Pai-Pi Ch'i Yii"; also called "Kyau-sh"ih-a" or Peh-phe Ki Hi"" by local fishermen. Black marlin are found throughout the tropical and subtropical waters of Table 2. — Annual landings (in metric tons) of billfishes by species in Taiwan, 1962-1971. Sword- Striped Blue Black Year Total fish marlin marlin marlin Sailfish' 1962 9,027 774 761 1,193 2,567 3.732 1963 10,915 723 1.188 1,379 2,656 4.969 1964 9,167 584 1 ,000 1,808 2,563 3.212 1965 8,667 540 1.001 2,127 2,323 2,676 1966 10,404 885 1,191 2,031 3,163 3,134 1967 11,297 1,258 1,472 2,658 2,390 3,519 1968 16,012 1,950 1,648 4,407 2,869 5,138 1969 17,994 2,643 2,747 4,525 3,409 4,670 1970 15,502 2,369 2,522 4,412 2,675 3,524 1971 16,573 2,543 1,796 4,261 3,616 4,357 'Other unidentified marlins are included under "Sailfish." 333 the Pacific and Indian Oceans. Off Taiwan, blactc marlin are taken along the east coast by the longline and harpoon fisheries. This species is caught year- round; however, best catches are made from Oc- tober to April. Black marlin are reported to spawn in the offshore waters of Taiwan from August to October. It is one of the largest of the marlins caught in Taiwan. The species is also considered a good food fish in Taiwan. 5. Sailfish, Istiophonts platypterus. In Chinese the sailfish is called "Yii San Ch'i Yii"; also called "Ho Soan Ki Hi"" or "Pua Ho Soan-a" by local fishermen. Sailfish enter the Taiwan inshore waters more often than any other species of billfish. In Taiwan sailfish are caught year-round along the entire coast of the island by longline, harpoon, and other fishing gear. From April to July and from October to December, the fishermen catch large numbers of sailfish in the Bashi Channel located near southern Taiwan. Dur- ing the fishing season, sailfish often occur in schools in the Kuroshio Current. Sailfish have been observed to swim with their high dorsal fins exposed and chasing sardine, squid, or other smaller prey. Fishermen find it fairly easy to harpoon sailfish; however, once harpooned the sailfish will leap and twist in an effort to shake loose. Adult sailfish with mature gonads have been re- ported by fishermen in southern Taiwan waters from April through August. This species grows to 2 m in length and 60 kg in weight. In comparison with other species, sailfish are not considered a good food fish by the Chinese people. Table 3. — Annual landings (in metric tons) of billfish by Taiwan deep-sea longiiners by ocean, 1967-1971. Striped Blue Black Other Year Area Total Swordfish marlin marlin marlin Sailfish marlin 1967 Pacific 935 126 63 346 50 94 256 Indian 2.047 275 665 704 236 134 33 Atlantic Subtotal 716 3,698 177 578 155 883 227 1,277 28 314 121 8 349 297 1968 Pacific 854 65 119 594 54 '}'> Indian 3,622 616 783 1 .065 616 542 — Atlantic 1.887 494 206 506 10 671 — Subtotal 6,363 1,175 1,108 2,165 680 1,235 — 1969 Pacific 1,180 108 134 565 191 71 Ill Indian 4,384 801 1,373 1,258 572 190 190 Atlantic 3,127 883 478 846 258 478 184 Subtotal 8,691 1.792 1 .985 2,669 1,021 739 485 1970 Pacific 1,621 188 269 646 143 127 248 Indian 3,920 641 1.140 997 499 213 430 Atlantic 2,519 630 429 687 143 458 172 Subtotal 8.060 1 ,459 1 .838 2,330 785 798 850 1971 Pacific 1,695 247 230 690 300 71 157 Indian 4,614 580 598 1,144 687 283 1,322 Atlantic 2.451 721 383 492 174 301 380 Subtotal 8.760 1 .548 1,211 2,326 1.161 655 1,859 Total 35,572 6,552 7,025 10,767 3,961 3,776 3.491 334 BILLFISH LANDINGS The annual landings of billfishes made by Taiwan fisheries from 1962 to 1971 show an increase cor- responding with the increase of the total Taiwan fisheries production (Tables 1 and 2). The landings showed a steady increase from 9,027 metric tons in 1962 to 16,573 metric tons in 1971 — a 10-year aver- age rate of increase of 8.4%. The billfish landings as a percentage of the total fish production, however, have not changed significantly during this period, the increase ranging from 2.4% to 3.1%. By species, the landings of swordfish ranged from 540 to 2,643 metric tons and peaked in 1969; striped marlin from 761 to 2,747 metric tons and peaked in 1969; blue marlin from 1,193 to 4,525 metric tons and peaked in 1969; black marlin from 2,323 to 3,616 metric tons and peaked in 1971; combined sailfish and other unidentified martins from 2,676 to 5,138 metric tons and peaked in 1968. Among these species, swordfish and blue marlin showed greater fluctuations in annual landings than any other species. Prior to 1965, landings made by the inshore long- liners ranked first followed by harpooning and the deep-sea longliners. After 1965, the landings of the deep-sea longliners increased rapidly, and since 1968 the deep-sea longliners have surpassed the in- shore longliners. The landings of the deep-sea long- line fishery were only 1,501 metric tons in 1962, increased slightly to 2,654 metric tons in 1966, but thereafter the fishery developed rapidly. As a re- sult, the deep-sea fishery landings of billfishes jumped to 6,363 metric tons in 1968 and reached a record high of 8,760 metric tons in 1971. Landings of the harpoon fishery declined slightly from 2.648 metric tons in 1962 to 1,865 metric tons in 1971; the decrease occurred despite an increase in fishing ef- fort. The inshore longline fishery showed a slight increase in annual landings from 4,361 metric tons in 1965 to 6,998 metric tons in 1969. In 1967 the Taiwan Fisheries Bureau initiated a survey of production and marketing in the deep-sea longline fishery, with emphasis placed on the col- lection of the landing statistics of billfishes, tunas, and other species. As a result of the survey, excel- lent data are available for fishing effort and catch by species for Taiwan vessels operating throughout the world's oceans. In a breakdown of billfish landings made by the deep-sea longline fishery from 1967 to 1971, the In- dian Ocean ranked first, followed by the Atlantic Table 4. — Distribution of fishing efforts of Taiwan deep- sea longline fleet, 1967-1971. Number of _ vessels Fishing trips Year Total Pacific Indian Atlantic 1967 254 570 380 169 21 1968 333 1,007 359 467 181 1969 396 1,158 298 576 284 1970 418 1,258 435 5.39 284 1971 457 M,182 495 409 278 'Estimated. and the Pacific Oceans (Table 3). The Indian Ocean catches contributed 55% of the yearly total landings of billfishes made in 1967 57% in 1968, 50% in 1969, 49% in 1970, and 53% in 1971. The annual landings of billfishes from the Atlantic Ocean accounted for 20%, 30%, 36%, 31%, and 28% for the years 1967 to 1971, respectively. The Pacific Ocean catches ac- counted for 25%, 13%, 14%, 21%, and 19% for the years 1967 to 1971, respectively. The percentage of the various species in the annual billfish landings made by the deep-sea longliners in the three ocean waters during 1967-1971 showed rather large annual fluctuations. The blue marlin was dominant in the Pacific and the Indian Oceans, while in the Atlantic the swordfish was the dominant species. Tables 1 and 2 show the annual billfish landings by the various fisheries by species from 1962 to 1971. Table 3 shows annual landings of billfishes by the deep-sea longliners by ocean from 1967 to 1971. 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By James E. Ellis and Charles C. Hoopes. November 1972, iti + 11 pp.. 9 figs. 661. A review of the literature on the development of skipjack tuna fisheries in the cen- tral and western Pacific Ocean. By Frank J. Hester and Taniio OUu. January 1973. iii + 13 pp.. 1 fig. For sale by the Superintendent of Documents, U.S. Government Printing Of- fice. 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 (lulf menhaden and other tishes in a n()rthwestern Florida estuar>'. By Marlin E. Tagatz and E. Peier H. Wilkins. August 1973, iii -f 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 -t- 21 pp.. 9 figs.. 1 table. 7 appendix tables. UNITED STAGES DEPARTMENT OF CO.MMERCE MATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION NATIONAL MARINE FISHERIES SERVICE SCIENTIFIC PUBCICATIONS STAFF f.*OOM 4 50 nor N E 45TH ST SEATTLE WA 98105 FOURTH CLASS POSTAGE AND FEES PAID US DEPARTMENT OF COMMERCE COM 210 OFFICIAL BUSINESS GALV]:;::' mFS, .JO U700 AVI; GALVESTO. 77^50 RECEIVED OCT 2 9 1974 NATLAIAK.flbh.t»feAII^