Standarized CPUE for juveniles yellowfin, skipjack and bigeye tuna from the European purse seine fleet in the Indian Ocean from 1981 to 2011

In this document three abundance indices are obtained for the juveniles of tropical tunas (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 final individual abundance indices are calculated multiplying both estimators for each species. Explanatory factors used in the analysis are: year, zone, quarter, holding capacity, country and starting date of the vessel. Year is the most explanatory factor of variability in cpue and, depending on the species, the fishing area and the quarter are significant. Vessel characteristics have a significant explanatory effect in observed aggregated catch rates.