Distribution patterns and population structure of the blue shark (Prionace glauca) in the Atlantic and Indian Oceans |
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| Authors: | Rui Coelho Jaime Mejuto Andrés Domingo Kotaro Yokawa Kwang‐Ming Liu Enric Cortés Evgeny V Romanov Charlene da Silva Fábio Hazin Freddy Arocha Aldrin Masawbi Mwilima Pascal Bach Victoria Ortiz de Zárate William Roche Pedro G Lino Blanca García‐Cortés Ana M Ramos‐Cartelle Rodrigo Forselledo Federico Mas Seiji Ohshimo Dean Courtney Philippe S Sabarros Bernardo Perez Ciara Wogerbauer Wen‐Pei Tsai Felipe Carvalho Miguel N Santos |
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| Affiliation: | 1. Portuguese Institute for the Ocean and Atmosphere (IPMA), Olh?o, Portugal;2. Instituto Espa?ol de Oceanografía (IEO), C.O. A Coru?a, A Coru?a, Spain;3. Dirección Nacional de Recursos Acuáticos (DINARA), Laboratorio de Recursos Pelágicos, Montevideo, Uruguay;4. National Research Institute of Far Seas Fisheries (NRIFSF), Shizuoka‐City, Shizuoka, Japan;5. Institute of Marine Affairs and Resource Management, National Taiwan Ocean University, Keelung, Taiwan;6. National Oceanographic and Atmospheric Administration, National Marine Fisheries Service (NOAA‐NMFS), Southeast Fisheries Science Center, Panama City Laboratory, Panama City, FL, USA;7. Centre Technique d'Appui à la Pêche Réunionnaise (CAP RUN – Hydr? Réunion), Le Port, ?le de la Réunion;8. Department of Agriculture, Forestry and Fisheries;9. Branch: Fisheries Research and Development, Inshore Research, Cape Town, South Africa;10. Departamento de Pesca e Aquicultura, Universidade Federal Rural de Pernambuco (UFRPE), Recife, Brasil;11. Instituto Oceanográfico de Venezuela, Universidad de Oriente, Estado Sucre, Venezuela;12. Ministry of Fisheries and Marine Resources, National Marine Information Resource Center, Windhoek, Namibia;13. Institut de Recherche pour le Développement (IRD), UMR 248 MARBEC, Sète Cedex, France;14. Instituto Espa?ol de Oceanografía (IEO), C.O. Santander, Santander, Spain;15. Inland Fisheries Ireland, Dublin 24, Ireland;16. Department of Fisheries Production and Management, National Kaohsiung Marine University, Kaohsiung, Taiwan |
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| Abstract: | The blue shark (Prionace glauca) is the most frequently captured shark in pelagic oceanic fisheries, especially pelagic longlines targeting swordfish and/or tunas. As part of cooperative scientific efforts for fisheries and biological data collection, information from fishery observers, scientific projects and surveys, and from recreational fisheries from several nations in the Atlantic and Indian Oceans was compiled. Data sets included information on location, size and sex, in a total of 478,220 blue shark records collected between 1966 and 2014. Sizes ranged from 36 to 394 cm fork length. Considerable variability was observed in the size distribution by region and season in both oceans. Larger blue sharks tend to occur in equatorial and tropical regions, and smaller specimens in higher latitudes in temperate waters. Differences in sex ratios were also detected spatially and seasonally. Nursery areas in the Atlantic seem to occur in the temperate south‐east off South Africa and Namibia, in the south‐west off southern Brazil and Uruguay, and in the north‐east off the Iberian Peninsula and the Azores. Parturition may occur in the tropical north‐east off West Africa. In the Indian Ocean, nursery areas also seem to occur in temperate waters, especially in the south‐west Indian Ocean off South Africa, and in the south‐east off south‐western Australia. The distributional patterns presented in this study provide a better understanding of how blue sharks segregate by size and sex, spatially and temporally, and improve the scientific advice to help adopt more informed and efficient management and conservation measures for this cosmopolitan species. |
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| Keywords: | Atlantic Ocean fishery observer programmes Indian Ocean pelagic fisheries size distribution spatial distribution |
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