Fishery biology of the swordfish (Xiphias gladius, Linnaeus 1758) caught by surface longliners based in Itajaí, southern Brazil
The Xiphias gladius (Linnaeus, 1758) data used in the present study were obtained from commercial fishing cruises of the pelagic longline fleet based in Itajaí, operating in the Southwest Atlantic. For the Covariance models, fishing effort (number of hooks) and catches (kg) were pooled and categoriz...
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doaj-f4b318062ea94f1f9c989efdda84e5e12020-11-24T22:46:59ZengUniversidade de São PauloBrazilian Journal of Oceanography 1679-87591982-436X2011-06-0159217118410.1590/S1679-87592011000200006Fishery biology of the swordfish (Xiphias gladius, Linnaeus 1758) caught by surface longliners based in Itajaí, southern BrazilAna Lia Campos QuaggioRosângela P. T. LessaJorge Eduardo KotasCelson F. LinThe Xiphias gladius (Linnaeus, 1758) data used in the present study were obtained from commercial fishing cruises of the pelagic longline fleet based in Itajaí, operating in the Southwest Atlantic. For the Covariance models, fishing effort (number of hooks) and catches (kg) were pooled and categorized into the following groups: (1) year (1997, 1998, 2001, 2002 and 2007); (2) lunar phase; and (3) seasons, fishing effort being the covariate. The highest mean swordfish catch (kg) occurred during the waxing crescent moon and during wintertime. The Mantel-Haenszel procedure was applied to compare the efficiency of the two hooks tested, and showed that the "J" hook type (J 9/0 10º offset), traditionally used by the fleet, catches 1.2-fold more Xiphias gladius than the circle hook (18/0 10º offset), used as an optional device to reduce sea turtle bycatch. The conversion of individual dressed weight (kg) into total length (cm) from 2000 to 2002, showed that sub-adults represented 66% of the total catch.<br>No presente estudo foram analisados os dados obtidos para Xiphias gladius (Linnaeus, 1758) através de observadores, mapas de bordo e fichas de desembarque de carcaças, coletadas pela frota de espinhel-de-superfície sediada em Itajaí (SC). Modelos de análise de covariância (ANCOVA) foram aplicados aos dados de captura (peso em kg) do espadarte, tendo como efeitos: (1) anos de 1997, 1998, 2001, 2002 e 2007 (2) fases lunares e (3) épocas do ano. A covariável foi o esforço de pesca (n° de anzóis). As maiores médias de captura ocorreram durante as fases de lua crescente e no inverno. O procedimento estatístico de Mantel-Haenszel foi utilizado para comparar as capturas do espadarte no anzol tipo "Jota" (J 9/0 10º offset), comumente utilizado pela frota, com o anzol tipo "circular" (18/0 10º offset), este último oferecido como alternativa mitigadora à captura de tartarugas marinhas. O teste M-H mostrou que o anzol "Jota" apresentou 1,2 mais chances de capturar Xiphias gladius que no "circular". A conversão dos pesos individuais das carcaças (kg) em comprimentos totais (cm), referentes aos anos de 2000 a 2002, indicou que 66% das capturas foram de sub-adultos ao longo de todo o ano.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-87592011000200006Teste de Mantel-HaenszelAnálise de covariânciaComposição de tamanhoMantel-Haenszel testCovariance modelsLength composition |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Ana Lia Campos Quaggio Rosângela P. T. Lessa Jorge Eduardo Kotas Celson F. Lin |
spellingShingle |
Ana Lia Campos Quaggio Rosângela P. T. Lessa Jorge Eduardo Kotas Celson F. Lin Fishery biology of the swordfish (Xiphias gladius, Linnaeus 1758) caught by surface longliners based in Itajaí, southern Brazil Brazilian Journal of Oceanography Teste de Mantel-Haenszel Análise de covariância Composição de tamanho Mantel-Haenszel test Covariance models Length composition |
author_facet |
Ana Lia Campos Quaggio Rosângela P. T. Lessa Jorge Eduardo Kotas Celson F. Lin |
author_sort |
Ana Lia Campos Quaggio |
title |
Fishery biology of the swordfish (Xiphias gladius, Linnaeus 1758) caught by surface longliners based in Itajaí, southern Brazil |
title_short |
Fishery biology of the swordfish (Xiphias gladius, Linnaeus 1758) caught by surface longliners based in Itajaí, southern Brazil |
title_full |
Fishery biology of the swordfish (Xiphias gladius, Linnaeus 1758) caught by surface longliners based in Itajaí, southern Brazil |
title_fullStr |
Fishery biology of the swordfish (Xiphias gladius, Linnaeus 1758) caught by surface longliners based in Itajaí, southern Brazil |
title_full_unstemmed |
Fishery biology of the swordfish (Xiphias gladius, Linnaeus 1758) caught by surface longliners based in Itajaí, southern Brazil |
title_sort |
fishery biology of the swordfish (xiphias gladius, linnaeus 1758) caught by surface longliners based in itajaí, southern brazil |
publisher |
Universidade de São Paulo |
series |
Brazilian Journal of Oceanography |
issn |
1679-8759 1982-436X |
publishDate |
2011-06-01 |
description |
The Xiphias gladius (Linnaeus, 1758) data used in the present study were obtained from commercial fishing cruises of the pelagic longline fleet based in Itajaí, operating in the Southwest Atlantic. For the Covariance models, fishing effort (number of hooks) and catches (kg) were pooled and categorized into the following groups: (1) year (1997, 1998, 2001, 2002 and 2007); (2) lunar phase; and (3) seasons, fishing effort being the covariate. The highest mean swordfish catch (kg) occurred during the waxing crescent moon and during wintertime. The Mantel-Haenszel procedure was applied to compare the efficiency of the two hooks tested, and showed that the "J" hook type (J 9/0 10º offset), traditionally used by the fleet, catches 1.2-fold more Xiphias gladius than the circle hook (18/0 10º offset), used as an optional device to reduce sea turtle bycatch. The conversion of individual dressed weight (kg) into total length (cm) from 2000 to 2002, showed that sub-adults represented 66% of the total catch.<br>No presente estudo foram analisados os dados obtidos para Xiphias gladius (Linnaeus, 1758) através de observadores, mapas de bordo e fichas de desembarque de carcaças, coletadas pela frota de espinhel-de-superfície sediada em Itajaí (SC). Modelos de análise de covariância (ANCOVA) foram aplicados aos dados de captura (peso em kg) do espadarte, tendo como efeitos: (1) anos de 1997, 1998, 2001, 2002 e 2007 (2) fases lunares e (3) épocas do ano. A covariável foi o esforço de pesca (n° de anzóis). As maiores médias de captura ocorreram durante as fases de lua crescente e no inverno. O procedimento estatístico de Mantel-Haenszel foi utilizado para comparar as capturas do espadarte no anzol tipo "Jota" (J 9/0 10º offset), comumente utilizado pela frota, com o anzol tipo "circular" (18/0 10º offset), este último oferecido como alternativa mitigadora à captura de tartarugas marinhas. O teste M-H mostrou que o anzol "Jota" apresentou 1,2 mais chances de capturar Xiphias gladius que no "circular". A conversão dos pesos individuais das carcaças (kg) em comprimentos totais (cm), referentes aos anos de 2000 a 2002, indicou que 66% das capturas foram de sub-adultos ao longo de todo o ano. |
topic |
Teste de Mantel-Haenszel Análise de covariância Composição de tamanho Mantel-Haenszel test Covariance models Length composition |
url |
http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-87592011000200006 |
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