Shark Depredation and Unwanted Bycatch in Pelagic Longline

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Shark Depredation and Unwanted Bycatch in Pelagic Longline Fisheries 5.3. Social Concerns Shark finning, where fins from caught sharks are retained and the remainder of the carcass is discarded, raises the social issue of waste. This has received recent international and national (Commonwealth of Australia, 1991; South Africa Government, 1998; Diario Oficial El Peruano, 2001; Council of the European Union, 2003; U.S. National Marine Fisheries Service, 2002, 2005) attention. Concern has also been raised that finning practices are cruel to sharks based on the presumption that fishers remove fins and discard sharks alive. However, results from this study document that, in all fisheries where shark finning occurs, to avoid injury and increase efficiency, crew first kill the fish before removing fins, and do not remove fins from live sharks . Also, discarded bycatch in general raises the social issue of waste (Alverson et al., 1994; Hall et al., 2000; FAO, 1999c), however, in the case of shark discards, available information suggests that in pelagic longline fisheries, shark post release survival prospects are high (U.S. National Marine Fisheries Service, 2005) and most sharks caught in pelagic longline fisheries are alive when hauled to the vessel (Williams, 1997). 22
Chapter 6 Industry Attitudes and Practices 6.1. Industry Attitudes Table 6.1 summarizes predominant attitudes related to shark depredation and bycatch possessed by fishers of 12 pelagic longline fisheries. The existence of restrictions on shark finning and shark retention limits (Table 4.1) has a large influence on industry attitudes towards shark interactions in the Australia, South Africa, and Hawaii, U.S.A. longline fisheries, where legal constraints have caused shark interactions to be an economic disadvantage. In these fisheries, fishers have a large incentive to avoid shark interactions. In the Italy longline fishery, despite a lack of market for shark products, low shark interaction rates result in low incentive to reduce shark interactions. The Fiji longline fishery attitudes towards shark interactions is unexpected. In this fishery, where almost all caught sharks are finned and carcasses discarded, fishers perceive that costs from shark interactions exceed the economic benefit. In the Chile, Japan and Peru longline fisheries, where restrictions on shark finning and retention are lacking, there is no incentive to reduce shark interactions, as revenue from sharks exceeds costs. There were some unique and interesting longline industry attitudes towards shark bycatch and depredation that were held by a minority of respondents. One fisherman in the Hawaii-based longline tuna fishery stated his view that sharks are a renewable natural resource, which should be managed for optimal yield as are other commercial marine resources, and that managers should institute a sustainable shark management framework. Likewise, some Australian fishermen questioned why regulations restrict the retention and disposition of sharks but not other bycatch species. Some fishers in the Chile and Peru artisanal mahi mahi and shark longline fisheries explained that during the mahi mahi season, they would prefer to catch fewer sharks and more mahi mahi because the latter species is more valuable. 6.2. Industry Practices Table 6.2 identifies practices that are in use by longline fishers to address shark interactions with longline gear. A practice is checked for a fishery only when the practice is employed predominantly for the purpose of reducing shark interactions, and not if the practice is primarily employed as a normal part of fishing operations to maximize catch rates of non-shark target species. Following subsections discuss the results of Table 6.2. Fishermen identified numerous fishing methods and gear characteristics that they employ to maximize catch rates of non-shark target species, which may contribute to reducing shark catch rates. For instance, the depth of baited hooks; timing of gear setting, soak and hauling; location of fishing grounds in relation to topographic and oceanographic features as well as sea surface temperature; type and size of bait and hook; selection of material for the leader on branch lines; non-use of lightsticks; and other fishing methods and gear designs selected by fishermen to maximize their non-shark target species catch rates may be effective shark avoidance strategies. More research is needed to improve the understanding of the shark avoidance efficacy of many of these practices. 6.2.1 Avoid peak areas and periods of shark abundance In fisheries where there is an incentive to avoid shark interactions, avoiding areas known to have high shark abundance and moving position when shark interaction rates are high are predominant shark avoidance practices. At the simplest level, individual fishing vessels can avoid setting in an area known to have high shark capture and depredation rates, which might occur seasonally. This is a practice identified by some members of the longline fisheries in Australia, Fiji, South Africa, Japan and Hawaii. Additionally, many fishers 23
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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
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Page 27 and 28: Shark Catch Rates and Disposition T
Page 29 and 30: Chapter 4 National and Internationa
Page 31 and 32: National and International Measures
Page 33 and 34: Economic, Practical, Ecological and
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Page 43 and 44: Chapter 7 Potential of Deterrents,
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Appendix 5 Japan Pelagic Longline F
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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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Appendix 9 USA Atlantic, Gulf of Me
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Shark Depredation and Unwanted Bycatch in Pelagic Longline

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