Age and growth of the smooth hammerhead shark, Sphyrna zygaena, in the Eastern Equatorial Atlantic Ocean, using vertebral sections

Detalhes bibliográficos
Autor(a) principal: Coelho, Rui
Data de Publicação: 2011
Outros Autores: Fernandez-Carvalho, Joana, Amorim, Sérgio, Santos, Miguel N.
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
Texto Completo: http://hdl.handle.net/10400.1/8931
Resumo: The smooth hammerhead shark Sphyrna zygaena (Sphyrnidae) is regularly caught as bycatch in pelagic longline fisheries, but is one of the least studied of all pelagic sharks. Recently, ICCAT (International Commission for the Conservation of Atlantic Tunas) issued recommendations underlining the need for more studies on the life history parameters of this and other pelagic shark species. To this end, the age and growth of S. zygaena were studied in the Eastern Equatorial Atlantic Ocean, in an area where growth parameters were not yet available for this species. Data from 139 specimens, caught between June and September 2009, ranging in size from 136 to 233 cm fork length (FL), were analysed. Preliminary trials were carried out to assess the most efficient growth band enhancement technique. These indicated that sectioning the vertebrae into 500 μm sections followed by staining with crystal violet produced the best results. Growth models were fitted using the traditional von Bertalanffy growth equation and a modification of this equation using a known size at birth. Growth models were compared using the Akaike information criterion (AIC). The von Bertalanffy growth equation seemed to be the most adequate model to describe growth in this species, with resulting growth parameters of L inf = 272 cm FL, k = 0.06 year for males and L inf = 285 cm FL, k = 0.07 year for females. In the first four years of life, S. zygaena grows 25 cm per year on average, but its growth slows down in later life. Future stock assessment models should incorporate these age and growth parameters for species management and conservation.
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spelling Age and growth of the smooth hammerhead shark, Sphyrna zygaena, in the Eastern Equatorial Atlantic Ocean, using vertebral sectionsAge and growthPelagic longline fisheriesLife historyCarcharhiniformesVertebral band countsAtlantic OceanThe smooth hammerhead shark Sphyrna zygaena (Sphyrnidae) is regularly caught as bycatch in pelagic longline fisheries, but is one of the least studied of all pelagic sharks. Recently, ICCAT (International Commission for the Conservation of Atlantic Tunas) issued recommendations underlining the need for more studies on the life history parameters of this and other pelagic shark species. To this end, the age and growth of S. zygaena were studied in the Eastern Equatorial Atlantic Ocean, in an area where growth parameters were not yet available for this species. Data from 139 specimens, caught between June and September 2009, ranging in size from 136 to 233 cm fork length (FL), were analysed. Preliminary trials were carried out to assess the most efficient growth band enhancement technique. These indicated that sectioning the vertebrae into 500 μm sections followed by staining with crystal violet produced the best results. Growth models were fitted using the traditional von Bertalanffy growth equation and a modification of this equation using a known size at birth. Growth models were compared using the Akaike information criterion (AIC). The von Bertalanffy growth equation seemed to be the most adequate model to describe growth in this species, with resulting growth parameters of L inf = 272 cm FL, k = 0.06 year for males and L inf = 285 cm FL, k = 0.07 year for females. In the first four years of life, S. zygaena grows 25 cm per year on average, but its growth slows down in later life. Future stock assessment models should incorporate these age and growth parameters for species management and conservation.EDP SciencesSapientiaCoelho, RuiFernandez-Carvalho, JoanaAmorim, SérgioSantos, Miguel N.2017-01-13T16:14:13Z20112011-01-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfhttp://hdl.handle.net/10400.1/8931engAUT: RMS01092;10.1051/alr/2011145info:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2023-07-24T10:20:17Zoai:sapientia.ualg.pt:10400.1/8931Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-19T20:00:59.048052Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse
dc.title.none.fl_str_mv Age and growth of the smooth hammerhead shark, Sphyrna zygaena, in the Eastern Equatorial Atlantic Ocean, using vertebral sections
title Age and growth of the smooth hammerhead shark, Sphyrna zygaena, in the Eastern Equatorial Atlantic Ocean, using vertebral sections
spellingShingle Age and growth of the smooth hammerhead shark, Sphyrna zygaena, in the Eastern Equatorial Atlantic Ocean, using vertebral sections
Coelho, Rui
Age and growth
Pelagic longline fisheries
Life history
Carcharhiniformes
Vertebral band counts
Atlantic Ocean
title_short Age and growth of the smooth hammerhead shark, Sphyrna zygaena, in the Eastern Equatorial Atlantic Ocean, using vertebral sections
title_full Age and growth of the smooth hammerhead shark, Sphyrna zygaena, in the Eastern Equatorial Atlantic Ocean, using vertebral sections
title_fullStr Age and growth of the smooth hammerhead shark, Sphyrna zygaena, in the Eastern Equatorial Atlantic Ocean, using vertebral sections
title_full_unstemmed Age and growth of the smooth hammerhead shark, Sphyrna zygaena, in the Eastern Equatorial Atlantic Ocean, using vertebral sections
title_sort Age and growth of the smooth hammerhead shark, Sphyrna zygaena, in the Eastern Equatorial Atlantic Ocean, using vertebral sections
author Coelho, Rui
author_facet Coelho, Rui
Fernandez-Carvalho, Joana
Amorim, Sérgio
Santos, Miguel N.
author_role author
author2 Fernandez-Carvalho, Joana
Amorim, Sérgio
Santos, Miguel N.
author2_role author
author
author
dc.contributor.none.fl_str_mv Sapientia
dc.contributor.author.fl_str_mv Coelho, Rui
Fernandez-Carvalho, Joana
Amorim, Sérgio
Santos, Miguel N.
dc.subject.por.fl_str_mv Age and growth
Pelagic longline fisheries
Life history
Carcharhiniformes
Vertebral band counts
Atlantic Ocean
topic Age and growth
Pelagic longline fisheries
Life history
Carcharhiniformes
Vertebral band counts
Atlantic Ocean
description The smooth hammerhead shark Sphyrna zygaena (Sphyrnidae) is regularly caught as bycatch in pelagic longline fisheries, but is one of the least studied of all pelagic sharks. Recently, ICCAT (International Commission for the Conservation of Atlantic Tunas) issued recommendations underlining the need for more studies on the life history parameters of this and other pelagic shark species. To this end, the age and growth of S. zygaena were studied in the Eastern Equatorial Atlantic Ocean, in an area where growth parameters were not yet available for this species. Data from 139 specimens, caught between June and September 2009, ranging in size from 136 to 233 cm fork length (FL), were analysed. Preliminary trials were carried out to assess the most efficient growth band enhancement technique. These indicated that sectioning the vertebrae into 500 μm sections followed by staining with crystal violet produced the best results. Growth models were fitted using the traditional von Bertalanffy growth equation and a modification of this equation using a known size at birth. Growth models were compared using the Akaike information criterion (AIC). The von Bertalanffy growth equation seemed to be the most adequate model to describe growth in this species, with resulting growth parameters of L inf = 272 cm FL, k = 0.06 year for males and L inf = 285 cm FL, k = 0.07 year for females. In the first four years of life, S. zygaena grows 25 cm per year on average, but its growth slows down in later life. Future stock assessment models should incorporate these age and growth parameters for species management and conservation.
publishDate 2011
dc.date.none.fl_str_mv 2011
2011-01-01T00:00:00Z
2017-01-13T16:14:13Z
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dc.identifier.uri.fl_str_mv http://hdl.handle.net/10400.1/8931
url http://hdl.handle.net/10400.1/8931
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10.1051/alr/2011145
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dc.publisher.none.fl_str_mv EDP Sciences
publisher.none.fl_str_mv EDP Sciences
dc.source.none.fl_str_mv reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
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collection Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
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