Post‐release survival of shortfin mako ( Isurus oxyrinchus ) and silky ( Carcharhinus falciformis ) sharks released from pelagic tuna longlines in the Pacific Ocean
| Type | Article | ||||||||||||
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| Date | 2023-04 | ||||||||||||
| Language | English | ||||||||||||
| Author(s) | Francis Malcolm P.1, Lyon Warrick S.2, Clarke Shelley C.3, Finucci Brittany1, Hutchinson Melanie R.4, Campana Steven E.5, Musyl Michael K.6, Schaefer Kurt M.7, Hoyle Simon D.8, 9, Peatman Tom10, Bernal Diego11, Bigelow Keith12, Carlson John13, Coelho Rui14, Heberer Craig15, Itano David16, Jones Emma17, Leroy Bruno10, Liu Kwang‐ming18, Murua Hilario19, Poisson Francois20, Rogers Paul21, Sanchez Caroline10, Semba Yasuko22, Sippel Tim23, Smith Neville10 | ||||||||||||
| Affiliation(s) | 1 : National Institute of Water and Atmospheric Research, Wellington ,New Zealand 2 : Lyon Marine Research Ltd ,Wellington, New Zealand 3 : Sasama Consulting, Shizuoka ,Japan 4 : Joint Institute for Marine and Atmospheric Research University of Hawaii, Pacific Islands Fisheries Science Center Honolulu Hawaii, USA 5 : University of Iceland ,Reykjavik,Iceland 6 : Pelagic Research Group LLC ,Honolulu Hawaii , USA 7 : Inter‐American Tropical Tuna Commission, La Jolla California, USA 8 : National Institute of Water and Atmospheric Research, Nelson ,New Zealand 9 : University of Auckland, Department of Statistics Auckland ,New Zealand 10 : The Pacific Community ,Noumea ,New Caledonia 11 : University of Massachusetts ,Dartmouth Dartmouth MA,USA 12 : NOAA, Fisheries ‐ Pacific Islands Fisheries Science Center Honolulu HI ,USA 13 : NOAA,Fisheries ‐ Southeast Fisheries Science Center Panama City FL,USA 14 : IPMA ,‐ Portuguese Institute for the Ocean and Atmosphere Olhão, Portugal 15 : The Nature Conservancy, Large Scale Fisheries Program San Diego California ,USA 16 : The Nature Conservancy, Large Scale Fisheries Program Honolulu Hawaii ,USA 17 : National Institute of Water and Atmospheric Research, Auckland ,New Zealand 18 : National Taiwan Ocean University ,Keelung ,Taiwan 19 : International Seafood Sustainability Foundation (ISSF), Pittsburgh Pennsylvania, USA 20 : MARBEC ,Université de Montpellier ,Sète,France 21 : Southern Fishery Solutions, South Australia 22 : National Research and Development Agency, Japan Fisheries Research and Education Kanagawa Pref, Japan 23 : Washington Department of Fish and Wildlife ‐ Region 5,Vancouver Washington,USA |
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| Source | Aquatic Conservation-marine And Freshwater Ecosystems (1052-7613) (Wiley), 2023-04 , Vol. 33 , N. 4 , P. 366-378 | ||||||||||||
| DOI | 10.1002/aqc.3920 | ||||||||||||
| WOS© Times Cited | 3 | ||||||||||||
| Keyword(s) | bycatch, fisheries management, fishing mortality best practices, high seas, no retention policy, pelagic shark, RFMO | ||||||||||||
| Abstract | Substantial global population declines in pelagic sharks have led to the introduction of management and conservation measures, including gear restrictions and no-retention policies, to curb declines and encourage stock recovery. As the rate of discarding sharks increases, there is a growing need to understand prognostic factors that influence their post-release survival (PRS) outcomes. PRS was measured with survival pop-up satellite archival tags attached to shortfin mako (Isurus oxyrinchus) and silky sharks (Carcharhinus falciformis) released or discarded from pelagic tuna longline fishing vessels operating in the Western and Central Pacific Fisheries Commission Convention Area. In total, 117 tags were deployed on 60 mako and 57 silky sharks captured as bycatch during commercial pelagic longline fishing trips in New Zealand (n = 35), Fiji (n = 58), New Caledonia (n = 10) and the Republic of the Marshall Islands (n = 14). Mako engaged in long-distance movements between New Zealand, Australia, Fiji and New Caledonia, while silky sharks tagged in the Marshall Islands showed evidence of seasonal movements eastward. PRS was determined for 110 sharks (57 mako, 53 silky sharks). Most tagged sharks of both species were uninjured (89%) at capture and most sharks (88%) survived post-release until tag loss or the programmed pop-up date (60 days). However, when considering a complete fishing interaction (haulback, handling, release), PRS estimates were markedly reduced to 48.6% and 52.3% for mako and silky sharks, respectively. For both species, survivorship was greater in large (>150 cm fork length) uninjured sharks and sharks released with low shark length to trailing branchline ratios. While these findings suggest that retention bans offer sharks an increased chance of survival, continued efforts should be made to improve handling and release practices, reduce trailing gear and minimize pelagic shark bycatch. |
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