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Meeting documentStandarized CPUE for juveniles yellowfin, skipjack and bigeye tuna from the European purse seine fleet in the Indian Ocean from 1981 to 2011 2013
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No results found.In this document three abundance indices are obtained for the juveniles of tropical tus (yellowfin (≤10Kg), skipjack and bigeye (≤10Kg) of European purse seine fishery in the Indian ocean from 1981 to 2011 using generalized linear models. Catch and effort data come from detailed daily logbooks. Catch rates are modelled using the delta lognormal model. The method estimates a combined cpue of the three species from aggregated catches, and the proportion of catches for each species, so the fil indi vidual abundance indices are calculated multiplying both estimators for each species. Explatory factors used in the alysis are: year, zone, quarter, holding capacity, country and starting date of the vessel. Year is the most explatory factor of variability in cpue and, depending on the species, the fishing area and the quarter are significant. Vessel characteristics have a significant explatory effect in observed aggregated catch rates. -
Meeting documentStatistics of the European Union and associated flags purse seine fishing fleet targeting tropical tunas in the Indian Ocean (1981-2013) 2014
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Meeting documentStatistics of the European Union and associated flags purse seine fishing fleet targeting tropical tunas in the Indian Ocean 1981-2012 2013
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No results found.In 2012, the European Union and associated flags purse seine fishing fleet of the Indian Ocean was composed of 37 vessels of individual carrying capacity >800 t, which all represented a total carrying capacity of more than 45,000 t. The total cumulated nomil effort was about 9,500 and 7,800 fishing and searching days, respectively. The total number of fishing sets was about 9,000, with about 5,600 realised on FAD-associated schools (i.e. >60%). Overall, the capacity and nomil effort of the fleet have remained stable during the recent years while the total catches have significantly dropped from more than 260,000 t during 2009-2011 to less than 230,000 t in 2012. The decline in catch is mainly explained by a combition of a major decrease in the number of sets per day and catch rates of skipjack on FAD-associated schools, the catch of skipjack per positive set being the lowest observed since 1984, i.e. 15 t set−1. Catch rates of skipjack on free-swimming schools also strongly decreased, which resulted in an overall decrease of skipjack catch by more than 40% between 2009-2011 and 2012. Meanwhile, catch rates of yellowfin on both FAD-associated and free-swimming schools increased in the recent years, resulting in a total catch of yellowfin that increased in 2012 to 130,000 t. The strong reduction in the number of FAD sets resulted in a total catch of bigeye that reached 16,500 t in 2012.
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