Shark Depredation and Unwanted Bycatch in Pelagic Longline

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Shark Depredation and Unwanted Bycatch in Pelagic Longline Fisheries A7.5. Shark Bycatch Composition and Catch Rates A7.5.1. Catch composition Blue Sharks were the most common species caught (average 69% of shark catch, range over time period 63–79%), then Mako Sharks 17% (8–20%) with the remaining 14% (5–29%) being made up of primarily Bronze Whaler, Cookie Cutter, Crocodile, Dusky, Oceanic Whitetip, Porbeagle, Thresher, Bigeye Thresher, hammerheads and Zambezi Sharks (Table A7.2). Blue Sharks were retained in 72% of cases, released alive in 18% of cases, finned and discarded (dead) in 5% and unknown for the remaining 4%. The discarded animals were often finned. Observers reported 30% and 25% of Blue Shark catches were finned in 2000 and 2001, respectively. Mako Sharks were also frequently caught and most commonly the whole shark was retained (86%). 10% were released alive and 2% discarded after finning. Thresher Sharks were infrequently caught and equally discarded/ released and retained. The Bronze Whaler was infrequently caught, but when it was caught it was usually retained. Crocodile, Cookie Cutter, Dusky (likely to include misidentified Silky Sharks (C. falciformis), Oceanic Whitetip, Dog Tooth, Bigeye Thresher, hammerhead spp. and Porbeagle sharks were infrequently caught, but almost always discarded/released. Even though the Crocodile Shark was caught infrequently, there were some occasions when they were caught in large numbers (e.g. a maximum of 81 was caught in a single set). The Zambezi Shark was rarely caught and in both cases it was discarded or released. Observers did not record whether sharks were hauled onboard dead or alive. The catch rate of sharks averaged 6.0 sharks per 1000 hooks and ranged between 4 and 19.8 during 1998-2005 (Table A7.3). Blue sharks were caught on average at a rate of 4.2 blue sharks per 1000 hooks and Short-fin Makos at a rate of 1.0 per 1000 hooks (1998-2005) (Table A7.3). Seasonal differences in catch rates were found for all species caught in substantial numbers (BlueX 2 = 1026.2, Mako X 2 = 190.8, Crocodile X 2 = 525.5, Brozne Whaler X 2 = 78.5, Dusky X 2 = 101.5, Hammerhead X 2 = 54.7, Oceanic Whitetip X 2 = 29.8, Porbeagle X 2 = 105.7, p
South Africa Pelagic Longline Tuna and Swordfish Fishery Table A7.3. Shark catches, effort and catch rates 1998 - 2005 1998 1999 2000 2001 2002 2003 2004 2005 Total Total hooks 472,104 516,919 1,476,807 1,637,358 2,658,127 2,440,069 5,098,196 7,538,265 21,837,845 Observed hooks 73,859 27,385 73,859 281,206 301,831 188,542 139,430 3,230,257 4,316,369 % observed of total 16% 5% 5% 17% 11% 8% 3% 43% 20% Swordfish 493 608 493 2343 2944 1836 319 3064 12100 Tuna 1746 380 1746 4067 3891 3179 2250 84928 102187 Total Catch 3472 1606 3472 11102 12141 8473 5192 114478 159936 Blue shark 611 443 611 1914 2080 1546 1722 9014 17941 Short-fin Mako shark 180 66 180 478 238 236 142 2944 4464 Crocodile shark 18 9 18 57 619 59 190 117 1087 Bronze Whaler shark 3 20 3 377 139 61 35 27 665 Thresher shark 8 1 8 19 90 20 15 422 583 Shark unidentified Oceanic white tip shark 0 0 0 1 103 75 137 141 457 125 0 125 4 19 27 12 9 321 Dusky shark 3 0 3 0 42 26 31 28 133 Thresher Big eye shark 10 3 10 0 0 18 0 33 74 Porbeagle 1 0 1 4 44 18 0 4 72 Hammerhead sharks Cookie cutter shark 0 0 0 3 44 0 0 0 47 0 0 0 0 1 18 0 0 19 Zambezi shark 0 0 0 1 1 0 4 1 7 Bigeye Sixgill shark 0 0 0 0 0 0 0 3 3 Soupfin shark 0 0 0 0 3 0 0 0 3 Lanternshark 0 0 0 0 0 0 0 2 2 Hardnose houndshark Houndshark Unidentified 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 1 1 Tiger shark 0 0 0 0 0 0 0 1 1 Total Sharks 959 542 959 2858 3423 2116 2289 12785 25931 Number sharks catch per 1000 hooks 13.0 19.8 13.0 10.2 11.3 11.2 16.4 4.0 6.0 Table A7.4. Shark bycatch as a proportion of total catch. Year Hooks Swordfish Tuna Tuna & Swordfish Total Sharks % sharks of Tuna % of T & S 1998 27385 608 380 988 959 252% 55% 1999 184864 1225 4628 5853 542 31% 25% 2000 73859 493 1746 2239 959 55% 43% 2001 281206 2343 4067 6410 2858 70% 45% 2002 301831 2944 3891 6835 3423 88% 50% 2003 188542 1836 3179 5015 2116 67% 42% 2004 139430 319 2250 2569 2289 102% 89% 2005 4316369 3064 84928 114478 12785 15% 15% Total 5513486 12832 105069 144387 25931 25% 18% 117
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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 99 and 100: Appendix 5 Japan Pelagic Longline F
Page 101 and 102: Japan Pelagic Longline Fisheries Fi
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Page 105 and 106: Japan Pelagic Longline Fisheries Ta
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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: South Africa Pelagic Longline Tuna
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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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Shark Depredation and Unwanted Bycatch in Pelagic Longline

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