Shark Depredation and Unwanted Bycatch in Pelagic Longline

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Shark Depredation and Unwanted Bycatch in Pelagic Longline Fisheries A7.5.2. Perception of interviewees Skippers interviewed were of the opinion that they catch 10 to 20 sharks or between 100 and 300 kg of sharks per set. Most felt the blue shark was the most commonly caught at a rate of up to 15 blue sharks (or 200 kg) per set. They usually retain most blue sharks (within the regulations). They report that blue sharks are usually hauled aboard alive, but die if they become badly entangled in their gear. Most felt that this capture had no effect on the species, however one skipper felt that the capture of blue sharks was dramatically threatening the species. The second most common species caught in their opinion was the short-fin mako shark. Up to 10 makos are caught per set and this comprises approximately 20 to 100 kg. They usually retain all makos (again within the regulations). The economic value of makos is higher than for blue sharks and thus retained more frequently. Most makos are alive on capture, but a portion of them are dead. Most felt that this capture had no effect on the species, however the same skipper as above felt that the capture of makos was dramatically threatening the species. Two of the skippers interviewed felt that shark bycatch was not causing any economic loss to the fishery. Three felt it was causing economic loss due to loss of bait and time. The remaining did not know. Only half said that they submitted their shark catches in their logbook records. A7.6. Management Framework Relevant to Shark Interactions At present there are no accepted mitigation measures for reducing shark bycatch and this requires investigation. South Africa has a draft NPOA-sharks, but this has not yet been adopted. However, in order to address mounting international concern for high levels of shark bycatch, Marine and Coastal Management, Department of Environmental Affairs and Tourism, South African Government, have planned to close the pelagic sector of the shark-directed longline fishery and place a 10% shark bycatch limit on the tuna and swordfish fishery. Since 2005 this fishery has been divided into those targeting swordfish and those targeting tunas. Individuals with a swordfish permit may only land sharks up to a maximum of 10% of their swordfish and tuna catch. Individuals with a tuna permit may only land sharks up to a maximum of 10% of their tuna catch. Currently shark bycatch accounts for approximately 18% or 25% of the directed catch (Table A7.4). This is substantially larger than the suggested 10%, thus many of these shark species will be released or discarded. Since we have no estimate of post-release survival nor adequate information on the percentage of species hauled alive, this may not be sufficient to address mounting concerns. Shark finning regulations came into effect in South Africa in 1998 under the Marine Living Resource Act of 1998 (MLRA, 1998). Regulations formed under this act banned finning. The South African experimental pelagic longline fishery only commenced in 1997 and thus very little information exists on finning practices in this fishery. Under this regulation sharks were supposed to be landed whole, which would mean that no finning was allowed. However, fishers complained that it was impractical to land sharks whole. Marine & Coastal Management gave concession for fishers to land the fins with the corresponding trunks, but this was not enforced as result sharks were definitely finned during this time. A 5% fin to carcass ratio was introduced last year (2005) in an attempt to stop finning Further regulations prohibit the use of a wire trace to limit the retention of shark catches in this fishery. A7.7. Economic, Social and Ecological Effects, Including Effects on Fishing Practices, from Regulations Governing Shark Interactions The total amount and condition of sharks landed is limited by the regulations discussed above. Most of the fishers that were interviewed felt that the 10% regulation was hard to comply with because it doesn’t reflect the reality. In many cases they catch more than their 10% and are thus forced to dump or discard dead sharks (Table 4). They felt it is also problematic because it results in the underreporting of shark catches. Three interviewees said that this regulation had minimal economic impact on them, two said that it caused great economic loss, but was unable to quantify and the remaining didn’t know. When revenue is acquired from finning this typically goes to the crew and/or skipper. In some cases these vessels are owner-operator and thus revenue is accrued to the company. One skipper reported that they don’t fin at all on his vessel because he doesn’t approve of the practice. The crew occasionally will retain the jaw of large makos. This will be dried and sold for their own revenue. Most felt that finning regulations were effective. 60% felt that if there were no regulation regarding finning then the practise would threaten the status of shark populations. Since the 10% regulation has been adopted they now only retain 10%, whereas before they would possibly have retained more depending on space availability, current prices etc. They all said that they have altered their fishing practices since the regulations have been adopted. Before the adoption of the finning regulations they would fin and dump most carcasses with the exception of makos which were retained for their flesh. A7.8. Practices to Deal with Caught Sharks Most skippers interviewed try to bring the shark alongside the vessel, then cut the line as short as possible and release the shark with the hook in its mouth. Many however will go to great lengths to retrieve their hook often at the expense of the shark. If the shark is small enough then they will land it, de-hook and release or discard. A dehooker is never used mainly because they don’t have one onboard and thus have never tried to use one. The decision as to whether they will retain or discard is usually based on the following: a) its size i.e. if it is too small they will usually discard, b) if their target catch is good they will discard (i.e. limited space availability) and c) regulations restricting them to 10% of their target catch. One interviewee was concerned about the safety of his crew and thus did not land large, live sharks. Product contamination was also a concern for half of the skippers interviewed. 118
South Africa Pelagic Longline Tuna and Swordfish Fishery Fig. A7.5: Distribution of sets on which Blue Sharks were caught, 2000-2003. Fig. A7.4: Seasonal distribution of shark bycatch catch rates (note different scales on y-axis). Fig. A7.6. Distribution of sets on which Mako Sharks were caught, 2000-2003. A7.9. Methods for Onboard Processing of Retained Sharks There are two common methods for onboard processing of retained sharks by vessels in the domestic South Africa longline fishery: (i) Retaining the body, fin the shark and discard the rest; and (ii) retaining the whole body. Foreign licensed vessels generally retain fins and trunks, and discard heads and guts of sharks. A7.10. Shark Depredation and Gear Damage For most, shark damage to their gear is a concern and estimated about at R5000 (approximately 750 US$) per set ranging from R100 to R10 000 (150-1500 US$) per set. This cost is mainly a combination of time loss and gear costs. Some of the skippers refer to the high cost of bait that is taken by sharks and some refer to the time of handling the shark on board to retain the hooks. They typically loose between 10 to 30 hooks or branchlines per set. Although this varies greatly from set to set. Approximately 2 to 5 (one skipper reported up to 15 per set) fish are typically damaged or lost to sharks on a typical set. They feel that they can tell shark damage from cetacean damage by the following: killer whales usually leaves the head and the bite mark is jaggered whereas sharks bites the tail and the bite is clean. Blue and short-fin makos are the most destructive sharks, but they are also the most commonly species caught. Most (one disagreed) felt that high shark catches reduced the catch rate of the target species. Some felt that they wanted to decrease their shark capture because they damage their gear and waste their time, others are interested in catching anything as long as it increases their profit. They would all like to decrease shark depredation although they feel cetacean depredation is a far bigger problem. A7.11. Practices Employed to Reduce Shark Capture All skippers interviewed say that they would avoid shark capture altogether if they could as a result of the current regulations. However, if they were free to fin or retain as many sharks as they like, half said that they would not avoid catching sharks. Under this scenario shark capture would be an economic advantage. Two felt that the economic value of their shark catches is so low that it wouldn’t make a difference. One skipper said that he would prefer to avoid catching sharks as their target catch was more economically advantageous. Most felt that regulations did not give them a greater incentive to avoid shark capture. When asked how they would avoid shark capture 119
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Shark Depredation and Unwanted Byca
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Contents Summary and Conclusions 1
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Contents Appendix 3. Fiji Pelagic L
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Contents Appendix 8. USA Hawaii Lon
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Chapter 1 Introduction and Methods
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Introduction and Methods 1.2. Metho
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Fishing Gear and Operational Charac
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Fishing Gear and Operational Charac
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Shark Catch Rates and Disposition T
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Chapter 4 National and Internationa
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National and International Measures
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Economic, Practical, Ecological and
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Economic, Practical, Ecological and
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Chapter 6 Industry Attitudes and Pr
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Industry Attitudes and Practices Lo
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Industry Attitudes and Practices Fi
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Chapter 7 Potential of Deterrents,
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Potential of Deterrents, Hotspot Av
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References Campana, S.E., L. Marks,
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References Neves dos Santos, M., Ga
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Shark Depredation and Unwanted Bycatch in Pelagic Longline

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