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

Queiroz, N; Humphries, NE; Mucientes, G; Hammerschlag, N; Lima, FP; Scales, KL; Miller, PI; Sousa, LL; Seabra, R; Sims, DW. 2016 Ocean-wide tracking of pelagic sharks reveals extent of overlap with longline fishing hotspots. Proceedings of the National Academy of Sciences of the United States of America, 113 (6). 10.1073/pnas.1510090113

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Official URL: http://dx.doi.org/10.1073/pnas.1510090113

Abstract/Summary

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 modelling showed sharks preferred habitats characterised 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 south-west of the Azores. In these main regions, and sub-areas 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.

Item Type: Publication - Article
Additional Keywords: Sharks, ocean fronts
Subjects: Conservation
Fisheries
Marine Sciences
Divisions: Plymouth Marine Laboratory > Science Areas > Earth Observation Science and Applications
Depositing User: Dr Peter I Miller
Date made live: 28 Jan 2016 17:01
Last Modified: 06 Jun 2017 16:14
URI: http://plymsea.ac.uk/id/eprint/6759

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