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| Fromentin, Jean-marc; Restrepo, Victor. |
| At the ICCAT symposium on bluefin tuna that held in Santander in April 2008, Tangen et al.(2009) presented a first quantification of the fishing effort deployed by the Norwegian fishery targeting bluefin tuna in the North Sea and Norwegian Sea. Using a year-class curve analysis on the Norwegian CPUE, this document presents the first estimates of mortality rates of Atlantic bluefin tuna that migrated north from the mid-1950s to the late 1970s. The results indicate that bluefin tuna would have experienced a total mortality rate (Z) of 0.2 to 0.4 yr-1 (i.e. F at around 0.3 yr-1) during the late 1950s, 0.2 yr-1 during the 1960s and 0.1 yr-1 afterwards (assuming M=0.1 yr-1). These results appear to be rather robust and consistent with the VPA estimates from the... |
| Tipo: Text |
Palavras-chave: Thunnus thynnus; Fishing and natural mortalities; Year-class curves; Stock assessment. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00192/30294/28783.pdf |
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| Fromentin, Jean-marc; Arrizabalaga, Haritz; Restrepo, Victor R; Ortiz De Urbina, J. |
| The 2004 data exploratory meeting concluded that it was no longer defensible to assess the East Atlantic and Mediterranean population using methods that assume that the catch-atsize/age is known exactly, until extensive improvements in fisheries statistics are made. For these reasons, we here investigated the potential benefits of the year-class curve analysis. The robustness and consistency of our results tend to advocate that this method is, in the present situation, a good alternative to ADAPT (among others). As a whole, the estimates of Z from the year-class curve analyses applied on the Spanish trap and Japanese long line fishery data appear indeed to be in good or excellent agreement with ADAPT outputs for the same period and same age-classes. This... |
| Tipo: Text |
Palavras-chave: Fishing and natural mortalities; Year-class curves; Stock assessment. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/00192/30325/28799.pdf |
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