title: Ocean-wide tracking of pelagic sharks reveals extent of overlap with longline fishing hotspots.
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.
authors.affiliation: Marine Biological Association of the United Kingdom, The Laboratory, Plymouth PL1 2PB, United Kingdom; Centro de Investigação em Biodiversidade e Recursos Genéticos/Research Network in Biodiversity and Evolutionary Biology, Campus Agrário de Vairão, Universidade do Porto, 4485-668 Vairão, Portugal;
authors.forename: Nuno
authors.initials: N
authors.lastname: Queiroz
authors.affiliation: Marine Biological Association of the United Kingdom, The Laboratory, Plymouth PL1 2PB, United Kingdom;
authors.forename: Nicolas E
authors.initials: NE
authors.lastname: Humphries
authors.affiliation: Centro de Investigação em Biodiversidade e Recursos Genéticos/Research Network in Biodiversity and Evolutionary Biology, Campus Agrário de Vairão, Universidade do Porto, 4485-668 Vairão, Portugal; Centro Tecnológico del Mar, 36208, Vigo, Spain;
authors.forename: Gonzalo
authors.identifier: http://orcid.org/0000-0001-6650-3020
authors.initials: G
authors.lastname: Mucientes
authors.affiliation: Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, FL 33149;
authors.forename: Neil
authors.initials: N
authors.lastname: Hammerschlag
authors.affiliation: Centro de Investigação em Biodiversidade e Recursos Genéticos/Research Network in Biodiversity and Evolutionary Biology, Campus Agrário de Vairão, Universidade do Porto, 4485-668 Vairão, Portugal;
authors.forename: Fernando P
authors.identifier: http://orcid.org/0000-0001-9575-9834
authors.initials: FP
authors.lastname: Lima
authors.affiliation: Plymouth Marine Laboratory, Plymouth PL1 3DH, United Kingdom; Institute of Marine Sciences, University of California, Santa Cruz, CA 95064; Environmental Research Division, Southwest Fisheries Science Center, National Oceanic and Atmospheric Administration, Monterey, CA 93940;
authors.forename: Kylie L
authors.identifier: http://orcid.org/0000-0003-0843-0956
authors.initials: KL
authors.lastname: Scales
authors.affiliation: Plymouth Marine Laboratory, Plymouth PL1 3DH, United Kingdom;
authors.forename: Peter I
authors.initials: PI
authors.lastname: Miller
authors.affiliation: Marine Biological Association of the United Kingdom, The Laboratory, Plymouth PL1 2PB, United Kingdom; Centro de Investigação em Biodiversidade e Recursos Genéticos/Research Network in Biodiversity and Evolutionary Biology, Campus Agrário de Vairão, Universidade do Porto, 4485-668 Vairão, Portugal; Ocean and Earth Science, National Oceanography Centre Southampton, Waterfront Campus, University of Southampton, Southampton SO14 3ZH, United Kingdom;
authors.forename: Lara L
authors.initials: LL
authors.lastname: Sousa
authors.affiliation: Centro de Investigação em Biodiversidade e Recursos Genéticos/Research Network in Biodiversity and Evolutionary Biology, Campus Agrário de Vairão, Universidade do Porto, 4485-668 Vairão, Portugal; Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, 4169-007 Porto, Portugal;
authors.forename: Rui
authors.initials: R
authors.lastname: Seabra
authors.affiliation: Marine Biological Association of the United Kingdom, The Laboratory, Plymouth PL1 2PB, United Kingdom; Ocean and Earth Science, National Oceanography Centre Southampton, Waterfront Campus, University of Southampton, Southampton SO14 3ZH, United Kingdom; Centre for Biological Sciences, Highfield Campus, University of Southampton, Southampton SO17 1BJ, United Kingdom dws@mba.ac.uk.
authors.forename: David W
authors.initials: DW
authors.lastname: Sims
mesh_terms: D000818:Animals; D017753:Ecosystem; D005398:Fisheries; D005843:Geography; D009792:Oceans and Seas; D017215:Satellite Communications; D012621:Seasons; D012754:Sharks / Q000502:physiology*; D012767:Ships; D013997:Time Factors
keywords: animal telemetry; conservation; distribution; fisheries; predator–prey
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