Shark Depredation and Unwanted Bycatch in Pelagic Longline

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Shark Depredation and Unwanted Bycatch in Pelagic Longline Fisheries A5.5.2. Kinkai fleet handling and disposition The kinkai fleet displayed the widest range of targeting strategies, including different gear and fishing ground variations by season, and thus showed the greatest diversity in shark handling and disposition. Despite this variation, fishermen could generally be divided into two groups with regard to their interactions with sharks: a) bycatch fisheries outside of Kesennuma, which fin sharks and discard the carcass; b) bycatch or shark targeting fisheries in Kesennuma which utilize both fins and meat. The one fishermen from a bycatch fishery located outside of Kesennuma who was interviewed usually fins sharks and discards the carcass. He reported using both wire and monofilament leaders, sometimes in the same set or even the same basket. The lack of a local market was cited as the reason for not utilizing shark meat. Sharks are handled by gaffing and then cutting off the head and fins. The only sharks which are sometimes retained whole are the thresher sharks which were claimed to have lower urea content than other sharks. Other sharks including shortfin mako sharks are reportedly finned and discarded. Extremely large sharks may be cut off the line to avoid endangering the crew. This fishermen explained that he provides an incentive to his crew, which are mostly Filipino, to fin sharks by offering each of them a bonus of 5,000-10,000 yen (roughly 50 -100 USD) per cruise if they fin hauled sharks. Interviews were also conducted with representatives of fisheries utilizing the whole shark mainly based in or around Kesennuma (n=13), where there is a stable market for shark products. These vessels are usually targeting billfish with shallow sets 6 or tuna, such as bigeye, with deep sets, but some vessels also explicitly targeted sharks during some times of the year. Shallow set operations for billfish are believed to catch more sharks, and especially when billfish numbers are expected to be low, wire leaders are often used to maximize retention of hooked sharks. One respondent claimed that catching 10 blue sharks would be equivalent in value to catching 1 billfish. The price for blue shark meat in Kesennuma at the time of the interview (April 2006) was $1.70 to $2.10 US per kg. A variety of practices were employed to handle the estimated 80-90% of sharks which are still alive when brought to the boat. These included: • Gaff the shark, pull the shark with the wire leader so that it is pinned against a large object and using 3-4 crew to immobilize it, cut the vertebrae 7 ; • Hit the shark with a long handled wooden mallet to immobilize it before cutting; • Drag the shark by means of the leader into a clamping device bolted to the deck (flat on one side, convex on the other, dimensions of 50 cm length, 44 cm width, 16.5 cm height with a 1.1m closing handle pole (Fig. A5.8)); close the clamp and kill the shark with a steel pike. Fig. A5.8. Clamping device designed and used by one kinkai fisherman based in Kesennuma for immobilizing sharks. (Photo courtesy of T. Miyamoto.) When cutting the head, as much as possible of the vertebrae near the dorsal surface is retained but the gills, located at the same anterior distance from the snout on the ventral surface, are removed. This is achieved by means of an S-shaped cut through the vertical axis of the shark. After removing the head, the shark is gutted but the fins are left intact. According to interviews with Kesennuma-based fishermen, there is no shark that is too big to be landed and all sharks which do not bite off the hook and escape will be brought on deck. A few respondents said they would release small sharks if they are still alive after hauling. A5.5.3. Engan fleet handling and disposition With some minor exceptions, shark handling and disposition practices in the engan fleet were similar to those in the kinkai fleet. Among the interview participants, several of the fishermen out of Kii-Katsuura (n=4) used an electric “shocker” device to stun sharks in the water before they are brought on deck. This device changes handling practices but did not seem to influence overall shark disposition (i.e. whether or not the carcass is retained). Another major difference was found in engan fishermen in Kii-Katsuura: while the market for shark products was deemed too small to warrant shark carcass retention by the Kii-Katsuura based kinkai fisherman (see above), the Kii-Katsuura engan fishermen usually retain shark carcasses. 8 There is a small shark products factory in Kii-Katsuura which processes shark meat, including blue and thresher shark meat, into semi-dried filets (tareboshi), processes a small number of fins, and sells the remaining fins to a dealer in Kobe for export to China (Fig. A5.9). On the smallest of the engan vessels, captains fish alone, i.e. without crew. Three of the four respondents in this category use nylon monofilament leaders to target tuna and billfish. The other respondent usually targets tuna with monofilament leaders but during the summer months he targets sharks using wire for the last 1 m of the branch line. 9 Due to crew limitations, these fishermen were forced to 6 One respondent mentioned that the Kesennuma style of fishing for billfish is similar to that used in the Hawaii longline fishery. 7 While some respondents claimed this could be achieved by one crew member “riding the shark” while the others assisted, this was considered too dangerous by other respondents due to the possibility of rolling 8 Note that the large shark products market in Kesennuma encourages both kinkai and engan fishermen there to retain shark carcasses but the small size of the market in Kii- Katsuura will support only the engan shark catches. 9 This fishermen claimed he was one of only two fishermen targeting sharks out of Kii-Katsuura in the summer months. Because of the high prices paid for thresher ($250 US per fish) and shortfin mako ($50 US per fish) he is targeting these species but the majority of his catch (20-30 sharks per day) is blue shark. His catch of fins and meat is sold to the small factory in Kii-Katsuura. Aside from this factory there are four other fin dealers in Kii-Katsuura with strong connections to the China market. 94
Japan Pelagic Longline Fisheries take a practical approach to shark handling, therefore they will release sharks by cutting the line: a) when the shark is small and they wish to save time; b) when it is approaching sunset and the haul is still not finished; or c) when fishing for tuna and the shark is any species other than thresher (the seasonal fisherman). When sharks are hauled, the electrical “shocker” is used to send a 100-300V electrical current through a ring with a small opening in it (Fig. A5.10). This ring is slid onto the branch line through the opening and dropped from the gunwhale down the line into the water until it contacts the shark. It is reportedly not dangerous to operate because the electric current is low and is effective only in water. Prior to its availability the crew used to have to try to immobilize the shark using the leader and fishermen complained that this was both dangerous and time consuming. Retained sharks are headed and gutted, and fins are retained on the carcass for cutting in the port. Embryonic sharks are discarded and sometimes swim away. Among the larger engan vessels, one targets sharks in the summer for the Kesennuma market, and several target tuna out of Kii- Katsuura or a variety of other ports in western Japan from Okinawa to Kesennuma. Fig. A5.9. Shark meat and fin to be used for tareboshi and hukahire products at a small factory in Kii-Katsuura. (Photos courtesy of T. Miyamoto.) Fig. A5.10. The ring and electrical cord of the “shocker” device used by engan fishermen based in Kii-Katsuura to immobilize sharks. (Photos courtesy of T. Miyamoto.) • The Kesennuma-based fisherman is targeting salmon sharks (Lamna ditropis) but often catches blue or shortfin mako sharks. He reports catching as many as 200-300 salmon sharks in a single set. This species is apparently docile to handle and it is thrown into the hold, sprayed with cold water and settles down quickly. All processing, including cutting of the valuable heart, is done in Kesennuma. • The more wide-ranging fishermen (n= 2) had differing perspectives on the value of shark meat but both utilized shark fins. t One fisherman realized that the demand for shark meat was expanding and had found markets for such meat in Kii- Katsuura, Choshi (Chiba Prefecture) and Shiogama (Miyagi Prefecture), as well as Kesennuma. For this reason, he retains any hooked shark in whole form (usually about 20 per set) by hauling it onboard, using shears clamped on the shark’s head to immobilize it and head and gut it. Fins are left on the carcass. Profits from shark products are split evenly between company and crew but for other species profits are kept by the company. This respondent claimed that all large sharks would bite through the nylon monofilament leader and escape, but other sharks with the exception of threshers (due to danger from the long caudal fin) would be hauled. t Another wide-ranging fisherman targeting tuna stuns all sharks with an electrical “shocker” before bringing them onboard, cuts the vertebrae as a safety precaution, fins the shark, and discards the carcass. He stated that all sharks will be handled in this manner regardless of size, though he noted most sharks he catches are in the range of 10-50 kg. Profits from shark fins will be split evenly among the crew without the company taking a share unless the catch is very high (e.g. 70 kg of fins worth 40,000-50,000 yen (350-450 USD)) in which case the captain will also take a share. 95
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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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Page 58 and 59: Shark Depredation and Unwanted Byca
Page 99 and 100: Appendix 5 Japan Pelagic Longline F
Page 101 and 102: Japan Pelagic Longline Fisheries Fi
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Page 111 and 112: Japan Pelagic Longline Fisheries In
Page 113 and 114: Japan Pelagic Longline Fisheries A5
Page 115 and 116: Appendix 6 Peru Artisanal Mahimahi
Page 117 and 118: Peru Artisanal Mahimahi And Shark L
Page 127 and 128: Appendix 7 South Africa Pelagic Lon
Page 129 and 130: South Africa Pelagic Longline Tuna
Page 135 and 136: Appendix 8 USA Hawaii-based Pelagic
Page 137 and 138: USA Hawaii-based Pelagic Longline S
Page 147 and 148: Appendix 9 USA Atlantic, Gulf of Me
Page 149 and 150: USA Atlantic, Gulf of Mexico and Ca
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USA Atlantic, Gulf of Mexico and Ca
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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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