Unreported discards of internationally protected pelagic sharks in a global fishing hotspot are potentially large
Unreported discards of internationally protected pelagic sharks in a global fishing hotspot are potentially large
Global abundances of oceanic pelagic sharks have declined due to overfishing. Internationally protected shark species remain at risk due to indiscriminate bycatch in longline fisheries with under-reported catches affecting reliability of population assessments for management. However, the scale of under-reporting remains poorly understood. Here we use detailed shark species catch data in a global fishing hotspot to show that the discards of three globally or regionally ‘Endangered’ or ‘Critically Endangered’ species (bigeye thresher Alopias superciliosus; oceanic whitetip Carcharhinus longimanus; smooth hammerhead Sphyrna zygaena) are potentially under-reported on a large scale: the total discards made by a single observed vessel in April–June 2018 in the eastern tropical Atlantic exceeded by 1.3–11.0 times the discards reported officially for these species Atlantic-wide for all of 2018. Scaling up observed catches (discards) of a single vessel to potential discards made by a single nation's fleet in the region, we estimate a mean annual total of 1526.2 t (±1 S.D. range: 415.3–2637.0 t), which exceeds by 89.2 times (±1 S.D. range: 24.3–154.2 times) the official reported discards for these three species. Without reducing bycatch mortality, which at present appears obscured by substantial under-reporting, Atlantic populations remain at serious risk.
Bycatch, Discard mortality, Longline fisheries, Protected sharks, Under-reporting
Mucientes, Gonzalo
f6d6424b-ff1e-486e-acad-ced610301624
Vedor, Marisa
f08e3974-ad4b-4843-9a48-4973d94c57a6
Sims, David W.
7234b444-25e2-4bd5-8348-a1c142d0cf81
Queiroz, Nuno
1b1b741e-a2ee-49c2-bbcc-2864044ba8e3
1 May 2022
Mucientes, Gonzalo
f6d6424b-ff1e-486e-acad-ced610301624
Vedor, Marisa
f08e3974-ad4b-4843-9a48-4973d94c57a6
Sims, David W.
7234b444-25e2-4bd5-8348-a1c142d0cf81
Queiroz, Nuno
1b1b741e-a2ee-49c2-bbcc-2864044ba8e3
Mucientes, Gonzalo, Vedor, Marisa, Sims, David W. and Queiroz, Nuno
(2022)
Unreported discards of internationally protected pelagic sharks in a global fishing hotspot are potentially large.
Biological Conservation, 269 (5), [109534].
(doi:10.1016/j.biocon.2022.109534).
Abstract
Global abundances of oceanic pelagic sharks have declined due to overfishing. Internationally protected shark species remain at risk due to indiscriminate bycatch in longline fisheries with under-reported catches affecting reliability of population assessments for management. However, the scale of under-reporting remains poorly understood. Here we use detailed shark species catch data in a global fishing hotspot to show that the discards of three globally or regionally ‘Endangered’ or ‘Critically Endangered’ species (bigeye thresher Alopias superciliosus; oceanic whitetip Carcharhinus longimanus; smooth hammerhead Sphyrna zygaena) are potentially under-reported on a large scale: the total discards made by a single observed vessel in April–June 2018 in the eastern tropical Atlantic exceeded by 1.3–11.0 times the discards reported officially for these species Atlantic-wide for all of 2018. Scaling up observed catches (discards) of a single vessel to potential discards made by a single nation's fleet in the region, we estimate a mean annual total of 1526.2 t (±1 S.D. range: 415.3–2637.0 t), which exceeds by 89.2 times (±1 S.D. range: 24.3–154.2 times) the official reported discards for these three species. Without reducing bycatch mortality, which at present appears obscured by substantial under-reporting, Atlantic populations remain at serious risk.
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More information
Accepted/In Press date: 30 March 2022
Published date: 1 May 2022
Additional Information:
Funding Information:
Funding was provided by the Save Our Seas Foundation (DWS, NQ), Fundação para a Ciência e a Tecnologia (FCT) under the grant PTDC/BIA-COM/28855/2017 and COMPETE POCI-01–0145-FEDER-028855 (NQ, DWS) and PTDC/ASP-PES/2503/2020 (MV, NQ), the UK Natural Environment Research Council (NERC) ( NE/R00997/X/1 ), European Research Council ( ERC-AdG-2019 883583 OCEAN DEOXYFISH ), NERC Oceans 2025 Strategic Programme (DWS) and Xunta de Galicia Spain under the Isabel Barreto Program 2009–2012 (GM). FCT supported NQ ( CEECIND/02857/2018 ), and MV ( PTDC/BIA-COM/28855/2017 and PTDC/ASP-PES/2503/2020 ). DWS was supported by a Marine Biological Association Senior Research Fellowship.
Funding Information:
Funding was provided by the Save Our Seas Foundation (DWS, NQ), Funda??o para a Ci?ncia e a Tecnologia (FCT) under the grant PTDC/BIA-COM/28855/2017 and COMPETE POCI-01?0145-FEDER-028855 (NQ, DWS) and PTDC/ASP-PES/2503/2020 (MV, NQ), the UK Natural Environment Research Council (NERC) (NE/R00997/X/1), European Research Council (ERC-AdG-2019 883583 OCEAN DEOXYFISH), NERC Oceans 2025 Strategic Programme (DWS) and Xunta de Galicia Spain under the Isabel Barreto Program 2009?2012 (GM). FCT supported NQ (CEECIND/02857/2018), and MV (PTDC/BIA-COM/28855/2017 and PTDC/ASP-PES/2503/2020). DWS was supported by a Marine Biological Association Senior Research Fellowship.
Publisher Copyright:
© 2022
Keywords:
Bycatch, Discard mortality, Longline fisheries, Protected sharks, Under-reporting
Identifiers
Local EPrints ID: 472709
URI: http://eprints.soton.ac.uk/id/eprint/472709
ISSN: 0006-3207
PURE UUID: 51220c0f-9da2-4f2d-bc7d-956e4309e6f9
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Date deposited: 15 Dec 2022 17:36
Last modified: 19 Jun 2024 01:45
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Contributors
Author:
Gonzalo Mucientes
Author:
Marisa Vedor
Author:
Nuno Queiroz
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