SUMMARY
Relative abundance indices by number of swordfish (Xiphias gladius) caught by the Brazilian tuna longline fishery in the South Atlantic Ocean were estimated by analyzing catch and effort data from individual sets (~60,000) collected for the period 1978-2006. A Generalized Linear Model was used to st...
| Main Authors: | , , |
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| Format: | Text |
| Language: | English |
| Subjects: | |
| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.544.7397 http://www.iccat.int/Documents/CVSP/CV062_2008/no_4/CV062041167.pdf |
| Summary: | Relative abundance indices by number of swordfish (Xiphias gladius) caught by the Brazilian tuna longline fishery in the South Atlantic Ocean were estimated by analyzing catch and effort data from individual sets (~60,000) collected for the period 1978-2006. A Generalized Linear Model was used to standardize the CPUE series (fish / 1000hooks), assuming two different error distributions: delta log-normal and quasi-Poisson (link = log and variance = µ,). For the delta-lognormal distribution, the model explained 40.6 % of the variance for the positive catches and about 77.8 % of the proportion of positives. The quasi-Poisson model explained 57.9 % of the variance. For both models the “Target ” and “Year ” variables explained most of the deviance. The results obtained seem to confirm the optimistic scenario of a continuing trend of CPUE increase for the species, in the southwestern Atlantic, in recent years. RÉSUMÉ Les indices d’abondance relative en nombre d’espadons (Xiphias gladius) capturés par la pêcherie palangrière brésilienne ciblant les thonidés dans l’Océan Atlantique Sud ont été estimés en analysant les données de prise et d’effort d’opérations individuelles (~60.000), collectées pour la période 1978-2006. Un Modèle Linéaire Généralisé a été utilisé pour standardiser la série de CPUE (poissons/1.000 |
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