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Atlantic Bluefin Tuna: A Novel Multistock Spatial Model for Assessing Population Biomass

Atlantic bluefin tuna (Thunnus thynnus) is considered to be overfished, but the status of its populations has been debated, partly because of uncertainties regarding the effects of mixing on fishing grounds. A better understanding of spatial structure and mixing may help fisheries managers to succes...

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Autores principales: Taylor, Nathan G., McAllister, Murdoch K., Lawson, Gareth L., Carruthers, Tom, Block, Barbara A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2011
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3235089/
https://www.ncbi.nlm.nih.gov/pubmed/22174745
http://dx.doi.org/10.1371/journal.pone.0027693
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author Taylor, Nathan G.
McAllister, Murdoch K.
Lawson, Gareth L.
Carruthers, Tom
Block, Barbara A.
author_facet Taylor, Nathan G.
McAllister, Murdoch K.
Lawson, Gareth L.
Carruthers, Tom
Block, Barbara A.
author_sort Taylor, Nathan G.
collection PubMed
description Atlantic bluefin tuna (Thunnus thynnus) is considered to be overfished, but the status of its populations has been debated, partly because of uncertainties regarding the effects of mixing on fishing grounds. A better understanding of spatial structure and mixing may help fisheries managers to successfully rebuild populations to sustainable levels while maximizing catches. We formulate a new seasonally and spatially explicit fisheries model that is fitted to conventional and electronic tag data, historic catch-at-age reconstructions, and otolith microchemistry stock-composition data to improve the capacity to assess past, current, and future population sizes of Atlantic bluefin tuna. We apply the model to estimate spatial and temporal mixing of the eastern (Mediterranean) and western (Gulf of Mexico) populations, and to reconstruct abundances from 1950 to 2008. We show that western and eastern populations have been reduced to 17% and 33%, respectively, of 1950 spawning stock biomass levels. Overfishing to below the biomass that produces maximum sustainable yield occurred in the 1960s and the late 1990s for western and eastern populations, respectively. The model predicts that mixing depends on season, ontogeny, and location, and is highest in the western Atlantic. Assuming that future catches are zero, western and eastern populations are predicted to recover to levels at maximum sustainable yield by 2025 and 2015, respectively. However, the western population will not recover with catches of 1750 and 12,900 tonnes (the “rebuilding quotas”) in the western and eastern Atlantic, respectively, with or without closures in the Gulf of Mexico. If future catches are double the rebuilding quotas, then rebuilding of both populations will be compromised. If fishing were to continue in the eastern Atlantic at the unregulated levels of 2007, both stocks would continue to decline. Since populations mix on North Atlantic foraging grounds, successful rebuilding policies will benefit from trans-Atlantic cooperation.
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spelling pubmed-32350892011-12-15 Atlantic Bluefin Tuna: A Novel Multistock Spatial Model for Assessing Population Biomass Taylor, Nathan G. McAllister, Murdoch K. Lawson, Gareth L. Carruthers, Tom Block, Barbara A. PLoS One Research Article Atlantic bluefin tuna (Thunnus thynnus) is considered to be overfished, but the status of its populations has been debated, partly because of uncertainties regarding the effects of mixing on fishing grounds. A better understanding of spatial structure and mixing may help fisheries managers to successfully rebuild populations to sustainable levels while maximizing catches. We formulate a new seasonally and spatially explicit fisheries model that is fitted to conventional and electronic tag data, historic catch-at-age reconstructions, and otolith microchemistry stock-composition data to improve the capacity to assess past, current, and future population sizes of Atlantic bluefin tuna. We apply the model to estimate spatial and temporal mixing of the eastern (Mediterranean) and western (Gulf of Mexico) populations, and to reconstruct abundances from 1950 to 2008. We show that western and eastern populations have been reduced to 17% and 33%, respectively, of 1950 spawning stock biomass levels. Overfishing to below the biomass that produces maximum sustainable yield occurred in the 1960s and the late 1990s for western and eastern populations, respectively. The model predicts that mixing depends on season, ontogeny, and location, and is highest in the western Atlantic. Assuming that future catches are zero, western and eastern populations are predicted to recover to levels at maximum sustainable yield by 2025 and 2015, respectively. However, the western population will not recover with catches of 1750 and 12,900 tonnes (the “rebuilding quotas”) in the western and eastern Atlantic, respectively, with or without closures in the Gulf of Mexico. If future catches are double the rebuilding quotas, then rebuilding of both populations will be compromised. If fishing were to continue in the eastern Atlantic at the unregulated levels of 2007, both stocks would continue to decline. Since populations mix on North Atlantic foraging grounds, successful rebuilding policies will benefit from trans-Atlantic cooperation. Public Library of Science 2011-12-09 /pmc/articles/PMC3235089/ /pubmed/22174745 http://dx.doi.org/10.1371/journal.pone.0027693 Text en Taylor et al. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Taylor, Nathan G.
McAllister, Murdoch K.
Lawson, Gareth L.
Carruthers, Tom
Block, Barbara A.
Atlantic Bluefin Tuna: A Novel Multistock Spatial Model for Assessing Population Biomass
title Atlantic Bluefin Tuna: A Novel Multistock Spatial Model for Assessing Population Biomass
title_full Atlantic Bluefin Tuna: A Novel Multistock Spatial Model for Assessing Population Biomass
title_fullStr Atlantic Bluefin Tuna: A Novel Multistock Spatial Model for Assessing Population Biomass
title_full_unstemmed Atlantic Bluefin Tuna: A Novel Multistock Spatial Model for Assessing Population Biomass
title_short Atlantic Bluefin Tuna: A Novel Multistock Spatial Model for Assessing Population Biomass
title_sort atlantic bluefin tuna: a novel multistock spatial model for assessing population biomass
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3235089/
https://www.ncbi.nlm.nih.gov/pubmed/22174745
http://dx.doi.org/10.1371/journal.pone.0027693
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