Reviews in Fish Biology and Fisheries

, Volume 8, Issue 1, pp 1–34

An ecological view of the tuna--dolphin problem: impacts and trade-offs

  • Martin A. Hall
Article

Abstract

After a brief description of purse seining and the other methods used to catch yellowfin tuna in the eastern Pacific Ocean, some consideration s are made on the tuna--dolphin association and the solution of the problem of dolphin mortality in the eastern Pacific. The association has been observed in other ocenas, but the frequency of setting in the eastern Pacific is much greater. The mortalities of dolphins through fishing have declined from about 133 000 in 1986 to around 2600 in 1996. The impact of recent levels of mortality on the dolphin populations is not significant from the population point of view. The mortality levels for all the stocks are less than 0.1%, much lower than the 2% value used as a conservative (low) estimate of net recruitment. All dolphin stocks have population sizes between 400 000 and 2 200 000, and most have remained stable for a decade or more. Fishing operations can cause ecological impacts of different types: bycatches, damage to the habitat, mortality caused by lost or discarded gear, pollution, generation of marine debris, etc. A brief discussion follows, with a more detailed look at the bycatches. For convenience we can separate the effects of the fishery on the target species, and on other species. Of the different ways of purse seining for tunas, sets on dolphins catch tuna close to the optimum size to maximize yields and to allow for reproduction, and result in discards of tunas of less than 1% of the catch. Sets on logs catch small tunas, and result in the highest tuna discards (20--25%). School sets fall in the middle from the point of view of the sizes caught. Obviously, from the ecological point of view, sets on dolphins are the best way to harvest yellowfin tuna. After a discussion of the different ecological impacts a fishery can cause to other species on the habitat, a comparison is made of the bycatches generated by the different types of purse seine sets. Billfishes, sharks, mahi-mahi, wahoo and sea turtles are taken as incidental catches by purse seiners. Log sets produce, by far, the largest bycatches, followed by school sets and dolphin sets in that order. The bycatch levels in log sets are usually tens to hundreds of times those in dolphin sets. The difference can be attributed to the selection caused by the speed of movement of the tuna--dolphin group (slow-moving species or individuals cannot keep up with the group), an effect that may be magnified by the chase that precedes the dolphin sets. Log sets, on the other hand, are made on a drifting community. The alternatives left to the fishers if they were forced to switch from the current fishing methods to others are briefly discussed, considering their feasibility, and comparing their ecological costs. From the ecological point of view, and considering that the dolphin mortality is clearly sustainable, the impacts caused by the other types of sets, especially log sets, could be more significant than those caused by the dolphin sets. Some of the species taken in log sets are endangered (e.g. sea turtles), others have unknown status and potential vulnerability because of their low reproductive and juvenile survival rates (e.g. sharks). Overall, the biodiversity of the eastern Pacific appears to be better preserved by a fishery directed to dolphin sets than the other alternatives proposed for the purse seine and for other gears.

bycatch dolphin tuna 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Alegría Hernandez, V. (1990) The tuna fishery in the eastern Adriatic. ICCAT, Coll. Vol. Sci. Pap. 33, 101–107.Google Scholar
  2. Alverson, F.G. (1960) Distribution of fishing effort and resulting tuna catches from the eastern tropical Pacific by quarters of the year, 1951–1958. Inter-Am. Trop. Comm. Bull. 4, 321–446.Google Scholar
  3. Anganuzzi, A.A. and Buckland, S. (1994) Relative abundance of dolphins associated with tuna in the eastern Pacific Ocean: analysis of 1992 data. Rep. Int. Whal. Comm. 44, 361–366.Google Scholar
  4. Anonymous (1991) Inter-Am. Trop. Tuna Comm. Ann. Rpt for 1989. 270 pp.Google Scholar
  5. Anonymous (1993a) Inter-Am. Trop. Tuna Comm. Ann. Rpt for 1992. 315 pp.Google Scholar
  6. Anonymous (1993b) Inter-Am. Trop. Tuna Comm. Quart. Rpt for April-June 1993. 58 pp.Google Scholar
  7. Anonymous (1994) Report of the P.B.R. (Potential Biological Removal) Workshop. June 27-29. (Southwest Fisheries Science Center, La Jolla, California.). 22 pp.Google Scholar
  8. Anonymous (1995) Inter-Am. Trop. Tuna Comm. Ann. Rpt for 1994. 296 pp.Google Scholar
  9. Anonymous (1997) Inter-Am. Trop. Tuna Comm. Ann. Rpt for 1995. 334 pp.Google Scholar
  10. Armstrong, W.A. and Oliver, C.W. (1995) Recent use of fish aggregating devices in the eastern tropical Pacific purse-seine fishery. La Jolla, CA: Southwest Fisheries Science Center. Admin Rept. LJ-95-14.Google Scholar
  11. Bailey, K., Williams, P.G. and Itano, D. (1996) By-catch and discards in western Pacific tuna fisheries: a review of SPC data holdings and literature. Noumea, New Caledonia: Oceanic Fisheries Programme, South Pacific Commission, Tech. Rept 34.Google Scholar
  12. Bane, G.W., Jr (1961) The distribution and abundance of tunas and tuna bait fishes in the Gulf of Guinea. MS thesis, Cornell Univ. 119 pp.Google Scholar
  13. Barlow, J. (1995a) The abundance of cetaceans in California waters. Part I: ship surveys in summer and fall of 1991. Fish. Bull., U.S. 93, 1–14.Google Scholar
  14. Barlow, J. (1995b) The abundance of cetaceans in California waters. Part II: aerial surveys in winter and spring of 1991 and 1992. Fish. Bull., U.S. 93, 15–26.Google Scholar
  15. Barlow, J., Swartz, S.L., Eagle, T.C. and Wade, P.R. (1995) U.S. marine mammal stock assessments: guidelines for preparation, background, and a summary of the 1995 assessments. U.S. Dept of Commerce, NOAA Tech. Memo. NMFS-OPR-6, 73 pp.Google Scholar
  16. Ben-Yami, M. (1994) Purse Seining Manual. Oxford: Fishing News Books. 406 pp.Google Scholar
  17. Boggs, C.H. (1992) Depth, capture time, and hooked longevity of longline-caught pelagic fish: timing bites of fish with chips. Fish. Bull., U.S. 90, 642–658.Google Scholar
  18. Britton, J.C. and Morton, B. (1994) Marine carrion and scavengers. Oceanogr. Mar. Biol. Ann. Rev. 32, 369–434.Google Scholar
  19. Broadhead, G.C. (1962) Recent changes in the efficiency of vessels fishing for yellowfin tuna in the eastern Pacific Ocean. Inter-Am. Trop. Tuna Comm. Bull. 6, 283–332.Google Scholar
  20. Brothers, N. (1991) Albatross mortality and associated bait loss in the Japanese longline fishery in the Southern Ocean. Biol. Conserv. 55, 255–268.Google Scholar
  21. Caldwell, D.K. and Caldwell, M.C. (1971) Porpoise fisheries in the southern Caribbean — present utilizations and future potentials. Rosenstiel Sch. Mar. and Atmostph. Sci., Proc. 23rd Ann. Session, Gulf and Caribbean Fish. Inst.: 195–205.Google Scholar
  22. Cayré, P., Kothias, J.B.A., Diouf, T. and Stretta, J.M. (1988) Biologie des thons. In Fonteneau, A. and Marcille, J. eds. Ressources, pêche et biologie des thonidés tropicaux de l'Atlantique Centre-Est. FAO, Doc. Tech. sur les Pêches No. 292, 157–268.Google Scholar
  23. Coan, A.L. and Sakagawa, G.T. (1982) An examination of single set data for the US tropical tuna purse seine fleet. ICCAT, Coll. Vol. Sci. Pap. 18, 83–94.Google Scholar
  24. Coe, J.M., Holts, D.B. and Butler, R.W. (1984) The “tuna-porpoise” problem: National Marine Fisheries Service dolphin mortality reduction research, 1970–1981. Mar. Fish. Rev. 46, 18–33.Google Scholar
  25. Cole, J.S. (1980) Synopsis of biological data on the yellowfin tuna, Thunnus albacares (Bonnaterre, 1788) in the Pacific Ocean. Inter-Am. Trop. Tuna Comm. Special Rep. 2, 71–150.Google Scholar
  26. Couperus, A.S. (1994) Killer whales (Orcinus orca) scavenging on discards of freezer trawlers north east of the Sheltand islands. Aquatic Mammals 20, 47–51.Google Scholar
  27. Dayaratne, P. and Joseph, L. (1993) A study on dolphin catches in Sri Lanka. Madras, India: Bay of Bengal Program, 47 pp.Google Scholar
  28. DeMaster, D.P. (1992) Strategic plan to develop and evaluate “dolphin-safe” methods of fishing for yellowfin tuna in the eastern tropical Pacific. La Jolla, CA: Southwest Fisheries Science Center, Admin. Rept LJ-92-16, 21 pp.Google Scholar
  29. De Silva, J. and Boniface, B. (1991) The study of the handline fishery on the west coast of Sri Lanka with special reference to the use of dolphin for locating yellowfin tuna (Thunnus albacares). IPTP (FAO), Coll. Vol. Work. Doc., 4. TWS/90/18, pp. 314–324.Google Scholar
  30. De Silva, J. and Dayaratne, P. (1991) Observations on the recently developed offshore fisheries for skipjack and yellowfin tunas in Sri Lanka. IPTP (FAO), Coll. Vol. Work. Doc., 4. TWS/90/17, pp. 304–313.Google Scholar
  31. Di Natale, A. (1990) Marine mammal interactions in Scombridae fishery activities: the Mediterranean case. ICCAT, Coll. Vol. Sci. Pap. 33, 140–142.Google Scholar
  32. Dizon, A.E., Perrin, W.F. and Akin, P.A. (1994) Stocks of dolphins (Stenella spp. and Delphinus delphis) in the eastern tropical Pacific: a phylogeographic classification. NOAA Tech. Rep. NMFS No. 119. 20 pp.Google Scholar
  33. Dolar, M.L. (1994) Incidental takes of small cetaceans in fisheries in Palawan, Central Visayas and Northern Mindanao in the Philippines. In Perrin, W.F., Donovan, G.P. and Barlow, J., eds. Gillnets and Cetaceans. Rept. Int. Whal. Comm. Special Issue, No. 15, pp. 355–363. Cambridge, UK.Google Scholar
  34. Donahue, M.A. and Edwards, E.F. (1996) An annotated bibliography of available literature regarding cetacean interactions with tuna purse-seine fisheries outside of the eastern tropical Pacific Ocean. La Jolla, CA: NMFS, Southwest Fisheries Science Center, Admin. Rept LJ-96-20. 46 pp.Google Scholar
  35. Edwards, E.F. (1992) Energetics of associated tunas and dolphins in the eastern tropical Pacific Ocean: a basis for the bond. Fish. Bull. U.S. 90, 678–690.Google Scholar
  36. Edwards, E.F. (1996) Separation/attraction research on the tuna-dolphin bond: review and criteria for future proposals. La Jolla, CA: NMFS, Southwest Fisheries Science Center, Admin. Rept LJ-96-17. 25 pp.Google Scholar
  37. Fiedler, P.C. and Reilly, S.B. (1994) Interannual variability of dolphin habitats in the eastern tropical Pacific. II: Effects on abundances estimated from tuna vessel sightings, 1975–1990. Fish. Bull. U.S. 92, 451–463.Google Scholar
  38. Forsbergh, E.D. (1989) The influence of some environmental variables on the apparent abundance of skipjack tuna, Katsuwonus pelamis, in the eastern Pacific Ocean. Inter-Am. Trop. Tuna Comm. Bull. 19, 433–569.Google Scholar
  39. Francis, R.C., Awbrey, F.T., Goudey, C.A., Hall, M.A., King, D.M., Medina, H., Norris, K.S., Orbach, M.K. Payne, R. and Pikitch, E. (1992) Dolphins and the Tuna Industry. Washington, DC: National Academy Press, 176 pp.Google Scholar
  40. Garthe, S. and Hüppop, O. (1994) Distribution of ship-following seabirds and their utilization of discards in the North Sea in summer. Mar. Ecol. Prog. Ser. 106, 1–9.Google Scholar
  41. Gerrior, P., Williams, A.S. and Christensen, D.J. (1994) Observations of the U.S. pelagic pair trawl fishery in the Northwest Atlantic. Mar. Fish. Rev. 56(3), 24–27.Google Scholar
  42. Gerrodette, T. (1987) A power analysis for detecting trends. Ecology 68, 1364–1372.Google Scholar
  43. Godsil, H.C. (1938) The high seas tuna fishery of California. Calif. Dept Fish Game, Fish Bull. 51, 41 pp.Google Scholar
  44. Goudey, C.A. (1995) The 1994 experimental pair trawl fishery for tuna in the Northwest Atlantic. Cambridge, MA: MIT-Sea Grant 95–6.Google Scholar
  45. Goudey, C.A. (1996) The 1995 experimental pair trawl fishery for tuna in the Northwest Atlantic. Final Rept. MIT-Sea Grant Coll. Prog. NOAA Grant NA46RG0434, 12 pp.Google Scholar
  46. Green, R.E., Perrin, W.F. and Petrich, B.P. (1971) The American tuna purse-seine fishery. In Kristjonsson, H., ed. Modern Fishing Gear of the World: 3. London: Fishing News (Books) Ltd, pp. 182–194.Google Scholar
  47. Hall, M.A. and Lennert, C. (1994) Incidental mortality of dolphins in the eastern Pacific Ocean tuna fishery in 1992. Rep. Int. Whal. Comm 44, 349–351.Google Scholar
  48. Hennemuth, R.C. (1961) Size and year class composition of catch, age and growth of yellowfin tuna in the eastern tropical Pacific Ocean for the years 1954–1958. Inter-Am. Trop. Tuna Comm., Bull. 5, 1–112.Google Scholar
  49. Heyning, J. and Perrin, W.F. (1994) Evidence for two species of common dolphins (Genus Delphinus) from the eastern North Pacific. Nat. Hist. Mus. Los Angeles County Contrib. Science No. 442. 1–35.Google Scholar
  50. Hoey, J.J. (1992) Bycatch in U.S. Atlantic longline fisheries for swordfish and tuna. In Schoning, R.W., Jacobson, R.W., Alverson, D.L., Gentle, T.H. and Auyong, J., eds. Proceedings of the National Industry Bycatch Workshop held at Newport, Oregon, Feb. 4–6, 1992, pp. 61–70. Natural Resources Consultants, 4055 21st W., Seattle, WA, USA.Google Scholar
  51. International Whaling Commission (1982) Report of the Scientific Committee. Annex H. Ann. Rept Int. Whal. Comm. 32.Google Scholar
  52. Joseph, J. (1994) The tuna-dolphin controversy in the eastern Pacific Ocean: biological, economic, and political impacts. Ocean Develop. Inter. Law 25(1), 1–30.Google Scholar
  53. Kanasashi, Y. (1960) Longline fishing: deck design and equipment. In Traung, J.-O., ed. Fishing Boats of the World: 2. London: Fishing News (Books) Ltd. pp. 73–83.Google Scholar
  54. Kasuya, T. (1976) Reconsideration of life history parameters of the spotted and striped dolphin based on cemental layers. Sci. Rep. Whales Res. Inst., Tokyo 28, 73–106.Google Scholar
  55. Leatherwood, S. (1994) Re-estimation of incidental cetacean catches in Sri Lanka. Rep. Int. Whal. Comm. Special Issue 15, Annex D, 64–65.Google Scholar
  56. Leatherwood, S. and Reeves, R.R. (eds) (1991) Marine mammal research and conservation in Sri Lanka, 1985–1986. Nairobi, Kenya: United Nations Environment Programme, Marine Mammal Tech. Rept No. 1, 2nd edn. 138 pp.Google Scholar
  57. Levenez, J., Fonteneau, A. and Regalado, R. (1980) Resultats d'une enquete sur l'importance des dauphins dans la pecherie thoniere FISM. ICCAT, Coll. Vol. Sci. Pap. 9, 176–179.Google Scholar
  58. Living Marine Resources, Inc. (1982) Gulf Coast tuna resource survey, April 1 to August 12, 1982, F/V Providence. Silva Fishing Co., Grant-in-aid award No. NA82-GA-D-005 15, 37 pp.Google Scholar
  59. Lo, N.C.H. and Smith, T.D. (1986) Incidental mortality of dolphins in the eastern tropical Pacific, 1959–1972. Fish. Bull. U.S. 84, 27–34.Google Scholar
  60. Longhurst, A.R. (1971) The clupeoid resources of tropical seas. Oceanog. Mar. Biol., Ann. Rev. 9, 349–385.Google Scholar
  61. Maigret, J. (1981a) Rapports entre les cétacés et la pêche thonière dans l'Atlantique tropical oriental. Notes Afr. 171, 77–84.Google Scholar
  62. Maigret, J. (1981b) Groupe d'étude des mammifères marins dans l'Atlantique tropical Africain. Gemmata/N.I. No. 3, Jan. 1981. 8 pp.Google Scholar
  63. Maigret, J. (1981c) Introduction à l'étude des rapports entre Cétacés et la Pêche thonière dans l'Atlantique tropical. Bull. Centre Natn Recherches Océanogr. Pêches Moaudhibou 10, 89–101.Google Scholar
  64. Mearns, A.J., Young, D.R., Olson, R.J. and Schafer, H.A. (1981) Trophic structure and the cesium-potassium ratio in pelagic ecosystems. Calif. Coop. Oceanic Fish. Invest. Rep. 22, 99–110.Google Scholar
  65. Mitchell, E. (1975) Porpoise, Dolphin and Small Whale Fisheries of the World. Status and Problems (IUCN Monograph No. 3). Gland, Switzerland and Cambridge, UK: International Union for the Conservation of Nature and Natural Resources. 129 pp.Google Scholar
  66. Montaudouin, X. de, Hallier, J.P. and Hassani, S. (1990) Analyse des données collectées lors des embarquements a bord des senneurs basés aux Seychelles (1986–1989). Seychelles Fishing Authority, Tech. Rep. 34 pp.Google Scholar
  67. Myrick, A.C. and Perkins, P.C. (1995) Adrenocortical color darkness and correlates as indicators of continuous acute premortem stress in chased and purse-seined captured male dolphins. Pathophysiology 2, 191–204.Google Scholar
  68. Nakano, H. and Bayliff, W.H. (1992) A review of the Japanese longline fishery for tunas and billfishes in the eastern Pacific Ocean, 1981–1987. Inter-Am. Trop. Tuna Comm. Bull. 20, 185–355.Google Scholar
  69. Natural Resources Consultants, Inc. (1990) Survey and evaluation of fishing gear loss in marine and Great Lakes fisheries of the United States. Final Report for National Marine Fisheries Service, Contract 50ABNF-9-00144, 141 pp.Google Scholar
  70. Nitta, E.T. and Henderson, J.R. (1993) A review of interactions between Hawaii's fisheries and protected species. Mar. Fish. Rev. 55, 83–92.Google Scholar
  71. Northridge, S.P. (1984) World review of interactions between marine mammals and fisheries. F.A.O. Fish. Tech. Paper No. 251. 190 pp.Google Scholar
  72. Northridge, S.P. (1991) An updated world review of interactions between marine mammals and fisheries. F.A.O. Fish. Tech. Paper No. 251, Suppl. 1. 58 pp.Google Scholar
  73. Oliver, C.W., Armstrong, W.A. and Young, J.A. (1994) Development of an airborne LIDAR system to detect tunas in the eastern tropical Pacific purse-seine fishery. U.S. Dept Commerce, NOAA Tech. Memo. NOAA-TM-NMFS-SWFSC-204, 67 pp.Google Scholar
  74. Olson, R.J. and Boggs, C.H. (1986) Apex predation by yellowfin tuna (Thunnus albacares): independent estimates from gastric evacuation and stomach contents, bioenergetics, and cesium concentrations. Can. J. Fish. Aquat. Sci. 43, 1760–1775.Google Scholar
  75. Pacific Tuna Development Foundation (1977) Final report tuna purse-seine charter to the Western Pacific. July–November 1976. 14 pp.Google Scholar
  76. Pereira, J. (1985) Composition specifique des bancs des thonides pêches à la senne, aux Acores. ICCAT Coll. Vol. Sci. Pap. 25, 395–400.Google Scholar
  77. Perrin, W.F. (1968) The porpoise and the tuna. Sea Frontiers 14, 166–174.Google Scholar
  78. Perrin, W.F. (1969) Using porpoise to catch tuna. World Fishing 18, 42–45.Google Scholar
  79. Perrin, W.F. and Reilly, S.B. (1984) Reproductive parameters of dolphins and small whales of the family Delphinidae. Rep. Int. Whal. Comm., Special Issue 6, 97–133.Google Scholar
  80. Perrin, W.F., Warner, R.W., Fiscus, C.L. and Holts, D.B. (1973) Stomach contents of porpoise, Stenella spp., and yellowfin tuna Thunnus albacares, in mixed species aggregation. Fish. Bull. 71, 1077–1092.Google Scholar
  81. Perrin, W.F., Scott, M.D., Walker, G.J. and Cass, V.L. (1985) Review of geographical stocks of tropical dolphins (Stenella spp. and Delphinus delphis) in the eastern Pacific. US Dept Commerce, NOAA Tech. Rept NMFS 28, 68 pp.Google Scholar
  82. Perrin, W.F., Donovan, G.P. and Barlow, J. (eds) (1994) Gillnets and Cetaceans. Cambridge, UK: Rep. Int. Whal. Comm., Special Issue 15. 629 pp.Google Scholar
  83. Potier, M. and Marsac, F. (1984) La pêche thonière dans l'Ocean Indien: campagne exploratoire d'une flottille de senneurs (1982–1983). Mission ORSTOM Seychelles, Rapp. Sci. No. 4. 73 pp.Google Scholar
  84. Prado, J. (1988) Trawling for albacore. INFOFISH International, 4/88, 50.Google Scholar
  85. Punsly, R.G., Tomlinson, P.K. and Mullen, A.J. (1994) Potential tuna catches in the eastern Pacific Ocean from schools not associated with dolphins. Fish. Bull. U.S. 92, 132–143.Google Scholar
  86. Rey, J.C. and Muñoz-Chapuli, R. (1991) Relation between hook depth and fishing efficiency in surface longline gear. Fish. Bull. U.S. 89, 729–732.Google Scholar
  87. Sainsbury, J.C. (1996) Commercial Fishing Methods: an Introduction to Vessels and Gears. Oxford, UK: Fishing News Books. 359 pp.Google Scholar
  88. Santana, J.C., Ariz, J., Pallares, P. and Delgado de Molina, A. (1991) Nota sobre la presencia de mamíferos marinos en la pesquería de túnidos al cerco en el Atlántico Este intertropical. ICCAT Coll. Vol. Sci. Pap. 35, 196–198.Google Scholar
  89. Scott, M.D. (1996) The tuna-dolphin controversy. Whalewatcher 30(1), 16–20.Google Scholar
  90. Shimada, B.M. and Schaefer, M.B. (1956) A study of changes in fishing effort, abundance, and yield for yellowfin and skipjack tuna in the eastern tropical Pacific Ocean. Inter-Am. Trop. Tuna Comm. Bull. 1, 347–469.Google Scholar
  91. Shomura, R.S. (1963) Monofilament gillnet fishing in skipjack tuna in Hawaiian waters, 1961–1962. U.S. Fish. Wildl. Serv., Circ., 170. 21 pp.Google Scholar
  92. Simmons, D.C. (1968) Purse seining off Africa's West coast. Comm. Fish. Rev. 30(3), 21–22.Google Scholar
  93. Smith, T.D. (1983) Changes in the size of three dolphin (Stenella spp.) populations in the eastern tropical Pacific. Fish. Bull. U.S. 81, 1–13.Google Scholar
  94. Smith, T.D. and Lo, N.C.H. (1983) Some data on dolphin mortality in the eastern tropical Pacific tuna purse seine fishery prior to 1970. US Dept Commerce, NOAA Tech. Memo. NOAA-TM-NMFS-SWFC-34.Google Scholar
  95. Stevens, J.D. (1992) Blue and mako shark bycatch in the Japanese longline fishery off South-eastern Australia. Aust. J. Mar. Freshwater Res. 43, 227–236.Google Scholar
  96. Stretta, J.M. and Slepoukha, M. (1986) Analysis of biotic and abiotic factors associated with schools of tunas. In Symons, P.E.K., Miyake, P.M. and Sakagawa, G.T., eds. Proc. ICCAT Conf. International Skipjack Year Program. Barcelona: Imprenta Juvenil, pp. 161–165.Google Scholar
  97. Stuntz, W.E. (1981) The tuna-dolphin bond: a discussion of current hypotheses. Southwest Fisheries Center, National Marine Fisheries Service, Admin. Rept No. LJ-81-19, August, 1981.Google Scholar
  98. Tomlinson, P.K., Tsuji, S. and Calkins, T.P. (1992) Length-frequency estimation for yellowfin tuna (Thunnus albacares) caught by commercial fishing gear in the eastern Pacific Ocean. Inter-Am. Trop. Tuna Comm. Bull. 20, 359–398.Google Scholar
  99. U.S. Public Law 103-238 — Apr. 30, (1994) Marine Mammal Protection Act, Amendments of 1994.Google Scholar
  100. Vilicic, A. (1985) Povjesni Razvoj Suvremenog Tunolova. VI. nakl., Univ. of Split. 199 pp.Google Scholar
  101. Wade, P.R. (1993) Estimates of historical population size of the eastern spinner dolphin (Stenella longirostris orientalis). Fish Bull. U.S. 91, 775–787.Google Scholar
  102. Wade, P.R. (1994a) Abundance and population dynamics of two eastern Pacific dolphins, Stenella attenuata and Stenella longirostris orientalis. PhD dissertation. Univ. California, San Diego. 255 pp.Google Scholar
  103. Wade, P.R. (1994b) Managing populations under the Marine Mammal Protection Act of 1994: a strategy for selecting values for Nmin, the minimum abundance estimate, and FR, the recovery factor. Background document. Report of the P.B.R. (potential biological removal) Workshop. June 27–29, 1994. (Southwest Fisheries Science Center, La Jolla, California.)Google Scholar
  104. Wade, P.R. (1995) Revised estimates of incidental kill of dolphins (Delphinidae) by the purse-seine tuna fishery in the eastern tropical Pacific, 1959–1972. Fish. Bull. U.S. 93, 345–354.Google Scholar
  105. Wade, P.R. and Gerrodette, T. (1993) Estimates of cetacean abundance and distribution in the eastern tropical Pacific. Rep. Int. Whal. Comm. 43, 477–493.Google Scholar
  106. Wahlen, B.E. and Smith, T.D. (1985) Observer effect on incidental dolphin mortality in the eastern tropical Pacific tuna fishery. Fish. Bull. U.S. 83, 521–530.Google Scholar
  107. Witzell, W.N. (1984) The incidental capture of sea turtles in the Atlantic U.S. Fishery Conservation Zone by the Japanese tuna longline fleet, 1978–1981. Mar. Fish. Rev. 46(3), 56–58.Google Scholar
  108. Yoshida, H. (1966) Tuna fishing vessels, gear, and techniques in the Pacific Ocean. In Manar, T.A., ed. Proceedings, Hawaii Governor's Conference of Central Pacific Fishery Resources. Honolulu: Bur. Comm. Fish., Biol. Lab., pp. 67–89.Google Scholar

Copyright information

© Chapman and Hall 1998

Authors and Affiliations

  • Martin A. Hall
    • 1
  1. 1.Inter-American Tropical Tuna Commission La JollaUSA

Personalised recommendations