Shark Depredation and Unwanted Bycatch in Pelagic Longline

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Shark Depredation and Unwanted Bycatch in Pelagic Longline Fisheries volume); > 70% of total shark catch by number for Japan longline fisheries (Clarke, this volume); 57% for the Peru artisanal mahi mahi and shark longline fishery (Pro Delphinus, unpublished data); 69% for the South Africa longline tuna and swordfish fishery (Petersen and Goren, this volume); and 82% and 92% for the U.S.A. Hawaii longline tuna and swordfish longline fisheries, respectively (Gilman, this volume). Identifying effective and commercially viable methods to reduce unwanted shark bycatch in longline fisheries would contributes to reducing shark fishing mortality. Increasing discards of blue sharks in pelagic longline fisheries would likely reduce fishing mortality of this species, as blue sharks are usually alive when hauled to the vessel (Beerkircher et al., 2002; Gilman, this volume; Mangel and Alfaro-Shigueto, this volume; Thomson, this volume). Beerkircher et al. (2002) found that the condition of sharks caught in pelagic longline gear (dead versus alive when hauled to the vessel) varied widely by species, where for example, blue sharks had a relatively low 12.2% mortality, while silky sharks (the most dominant species of shark by number caught in the observed southeastern U.S. pelagic longline swordfish and tuna fisheries, 31.4% of elasmobranch catch) had a 66.3% mortality. Gilman (this volume) found that over 89% of sharks caught in the Hawaii-based longline swordfish fishery and over 93% of sharks caught in the Hawaii-based longline tuna fishery are alive when the gear is retrieved. Mangel and Alfaro-Shigueto (this volume) found that 87% of sharks caught in the Peru artisanal mahi mahi and shark longline fishery were alive when gear was retrieved. Thomson (this volume) analyzes Secretariat of the Pacific Community observer program data from 2002-2005 for the Fiji longline tuna fishery and found that over 94% of blue sharks and over 84% of combined species of sharks were alive when hauled to the vessel. 14
Chapter 4 National and International Measures 4.1. Summary and Effects of National/EC Legislation on Shark Interactions Table 4.1 summarizes legally binding measures that influence longline industry practices and attitudes towards shark bycatch and depredation in pelagic longline fisheries. The two Chile longline fisheries, Fiji longline fishery, and three Japan longline tuna fisheries are not subject to legally binding measures that manage shark interactions, and are not included in Table 4.1. However, Japan and Fiji distant water longline tuna vessels may comply with voluntary measures adopted by Regional Fishery Management Organizations, and vessels operating in EEZs of other nations through foreign license access agreements may be required to comply with restrictions on shark catch, retention and use under these access agreements. Legislation prohibiting the removal of shark fins and tail and discarding the remainder of the shark at sea in pelagic longline fisheries exists in four of the eight countries included in this study (Australia, Italy, South Africa, and U.S.A.) (Commonwealth of Australia, 1991; South Africa Marine Living Resource Act of 1998; U.S. Congress, 2000; Council of the European Union, 2003). In the Australia longline tuna and billfish fishery, a rule that disallows possession, carrying and landing of shark fins unless attached to the trunk of the shark has likely substantially reduced shark fishing mortality, as finning was a widespread practice before this measure was instituted, while about 75% of caught sharks are now released alive (Rose and McLaughlin, 2001; Hobday et al., 2004). In the Hawaii longline tuna and swordfish fisheries, observer data indicate that the restriction on shark finning, which requires the retention of shark carcasses for corresponding retained fins, has likewise substantially reduced shark fishing mortality. As many as 76% and 64% of caught sharks were finned in the Hawaii tuna and swordfish fisheries, respectively, prior to this rule being in effect, while in 2006 91% and 93% of caught sharks were released alive in the tuna and swordfish fisheries, respectively. In the South Africa longline tuna and swordfish fishery, all interviewed fishers stated that prior to the finning restriction, they would fin and discard the carcass of all caught sharks excluding makos, which were retained for the sale of both their fins and meat. Thus, as in the case in the Hawaii and Australia longline fisheries, the restriction on finning in South Africa has substantially reduced shark retention and increased discards. In these fisheries, shark finning restrictions have caused substantial reductions in revenue to industry. For instance, revenue from shark fins had comprised 10-11% of Hawaii longline crew salaries (McCoy and Ishihara, 1999). Italy is subject to European Union Council Regulation No. 1185 (Council of the European Union, 2003), which prohibits the practice of shark finning. However, all 17 interviewed owner-operators from the Italy Mediterranean industrial longline swordfish fishery were unaware of the prohibition and thus the legislation does not affect their practices. However, no shark finning is reported to occur in the fishery due to the lack of a local market for the fins. Japan does not have legislation restricting shark finning practices, however, the distant-water fleet fish in EEZs of nations that do have finning restrictions (e.g., South Africa, Brazil, Costa Rica). Vessels in the Japan distant-water longline tuna fishery will likely fin caught sharks and discard the carcass unless they are fishing in the EEZ of a nation that prohibits this practice, in which case the vessel may choose to retain the whole shark carcass and land the carcass in ports where there are markets for shark meat. Thus, Japanese longline fishermen have adapted to finning regulations applicable in some areas by landing sharks in recently developed local markets rather than by attempting to avoid shark interactions. In waters without finning regulations, including Japanese waters and the North Pacific, sharks are either finned or landed whole, and in either case the ability to sell shark products has contributed to a lack of interest in reducing shark bycatch. A 20 shark carcass per trip limit for the retention of sharks in the Australia East coast longline tuna and billfish fishery has not altered the number of sharks retained by fishers, as fewer than 20 sharks are typically caught during an average length trip, and only a small proportion of the sharks caught on a trip are of species (makos 15
Page 3 and 4: Shark Depredation and Unwanted Byca
Page 5: Shark Depredation and Unwanted Byca
Page 9 and 10: Contents Summary and Conclusions 1
Page 11 and 12: Contents Appendix 3. Fiji Pelagic L
Page 13: Contents Appendix 8. USA Hawaii Lon
Page 19 and 20: Chapter 1 Introduction and Methods
Page 21 and 22: Introduction and Methods 1.2. Metho
Page 23 and 24: Fishing Gear and Operational Charac
Page 25 and 26: Fishing Gear and Operational Charac
Page 27: Shark Catch Rates and Disposition T
Page 31 and 32: National and International Measures
Page 33 and 34: Economic, Practical, Ecological and
Page 35 and 36: Economic, Practical, Ecological and
Page 37 and 38: Chapter 6 Industry Attitudes and Pr
Page 39 and 40: Industry Attitudes and Practices Lo
Page 41 and 42: Industry Attitudes and Practices Fi
Page 43 and 44: Chapter 7 Potential of Deterrents,
Page 45 and 46: Potential of Deterrents, Hotspot Av
Page 47 and 48: References Campana, S.E., L. Marks,
Page 49: References Neves dos Santos, M., Ga
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Appendix 5 Japan Pelagic Longline F
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Japan Pelagic Longline Fisheries Fi
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Japan Pelagic Longline Fisheries mo
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Japan Pelagic Longline Fisheries Ta
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Appendix 6 Peru Artisanal Mahimahi
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Peru Artisanal Mahimahi And Shark L
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Appendix 7 South Africa Pelagic Lon
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South Africa Pelagic Longline Tuna
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Appendix 8 USA Hawaii-based Pelagic
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USA Hawaii-based Pelagic Longline S
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Appendix 9 USA Atlantic, Gulf of Me
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USA Atlantic, Gulf of Mexico and Ca
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Shark Depredation and Unwanted Bycatch in Pelagic Longline

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