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Ocean-wide tracking of pelagic sharks reveals extent of overlap with longline fishing hotspots

Ocean-wide tracking of pelagic sharks reveals extent of overlap with longline fishing hotspots
Ocean-wide tracking of pelagic sharks reveals extent of overlap with longline fishing hotspots
Overfishing is arguably the greatest ecological threat facing the oceans, yet catches of many highly migratory fishes including oceanic sharks remain largely unregulated with poor monitoring and data reporting. Oceanic shark conservation is hampered by basic knowledge gaps about where sharks aggregate across population ranges and precisely where they overlap with fishers. Using satellite tracking data from six shark species across the North Atlantic, we show that pelagic sharks occupy predictable habitat hotspots of high space use. Movement modeling showed sharks preferred habitats characterized by strong sea surface-temperature gradients (fronts) over other available habitats. However, simultaneous Global Positioning System (GPS) tracking of the entire Spanish and Portuguese longline-vessel fishing fleets show an 80% overlap of fished areas with hotspots, potentially increasing shark susceptibility to fishing exploitation. Regions of high overlap between oceanic tagged sharks and longliners included the North Atlantic Current/Labrador Current convergence zone and the Mid-Atlantic Ridge southwest of the Azores. In these main regions, and subareas within them, shark/vessel co-occurrence was spatially and temporally persistent between years, highlighting how broadly the fishing exploitation efficiently “tracks” oceanic sharks within their space-use hotspots year-round. Given this intense focus of longliners on shark hotspots, our study argues the need for international catch limits for pelagic sharks and identifies a future role of combining fine-scale fish and vessel telemetry to inform the ocean-scale management of fisheries.
animal telemetry, distribution, n conservation, fisheries, predator–prey
0027-8424
1582-1587
Queiroz, Nuno
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Humphries, Nicolas E.
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Mucientes, Gonzalo
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Hammerschlag, Neil
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Lima, Fernando P.
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Scales, Kylie L.
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Miller, Peter I.
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Sousa, Lara L.
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Seabra, Rui
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Sims, David W.
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Queiroz, Nuno
1b1b741e-a2ee-49c2-bbcc-2864044ba8e3
Humphries, Nicolas E.
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Mucientes, Gonzalo
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Hammerschlag, Neil
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Lima, Fernando P.
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Scales, Kylie L.
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Miller, Peter I.
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Sousa, Lara L.
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Seabra, Rui
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Sims, David W.
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Queiroz, Nuno, Humphries, Nicolas E., Mucientes, Gonzalo, Hammerschlag, Neil, Lima, Fernando P., Scales, Kylie L., Miller, Peter I., Sousa, Lara L., Seabra, Rui and Sims, David W. (2016) Ocean-wide tracking of pelagic sharks reveals extent of overlap with longline fishing hotspots. Proceedings of the National Academy of Sciences, 113 (6), 1582-1587. (doi:10.1073/pnas.1510090113).

Record type: Article

Abstract

Overfishing is arguably the greatest ecological threat facing the oceans, yet catches of many highly migratory fishes including oceanic sharks remain largely unregulated with poor monitoring and data reporting. Oceanic shark conservation is hampered by basic knowledge gaps about where sharks aggregate across population ranges and precisely where they overlap with fishers. Using satellite tracking data from six shark species across the North Atlantic, we show that pelagic sharks occupy predictable habitat hotspots of high space use. Movement modeling showed sharks preferred habitats characterized by strong sea surface-temperature gradients (fronts) over other available habitats. However, simultaneous Global Positioning System (GPS) tracking of the entire Spanish and Portuguese longline-vessel fishing fleets show an 80% overlap of fished areas with hotspots, potentially increasing shark susceptibility to fishing exploitation. Regions of high overlap between oceanic tagged sharks and longliners included the North Atlantic Current/Labrador Current convergence zone and the Mid-Atlantic Ridge southwest of the Azores. In these main regions, and subareas within them, shark/vessel co-occurrence was spatially and temporally persistent between years, highlighting how broadly the fishing exploitation efficiently “tracks” oceanic sharks within their space-use hotspots year-round. Given this intense focus of longliners on shark hotspots, our study argues the need for international catch limits for pelagic sharks and identifies a future role of combining fine-scale fish and vessel telemetry to inform the ocean-scale management of fisheries.

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More information

Accepted/In Press date: 18 December 2015
e-pub ahead of print date: 25 January 2016
Published date: 9 February 2016
Keywords: animal telemetry, distribution, n conservation, fisheries, predator–prey
Organisations: Ocean and Earth Science

Identifiers

Local EPrints ID: 390080
URI: http://eprints.soton.ac.uk/id/eprint/390080
ISSN: 0027-8424
PURE UUID: 587d6ab3-c2c0-45d8-8116-ab750f88e2ec

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Date deposited: 17 Mar 2016 17:25
Last modified: 27 Apr 2022 11:02

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Contributors

Author: Nuno Queiroz
Author: Nicolas E. Humphries
Author: Gonzalo Mucientes
Author: Neil Hammerschlag
Author: Fernando P. Lima
Author: Kylie L. Scales
Author: Peter I. Miller
Author: Lara L. Sousa
Author: Rui Seabra
Author: David W. Sims

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