STANDARDIZED CATCH RATE OF SAILFISH (ISTIOPHORUS PLATYPTERUS) CAUGHT BY BRAZILIAN LONGLINERS IN THE ATLANTIC OCEAN (1978-2008)

1SUMMARY In this paper generalized linear models were used to generate two standardized sailfish CPUE series from the Brazilian longline fishery between 1978 and 2008. The first standardized series included year, quarter and area as explanatory variables, while the second series included all those factors plus a cluster variable, as an indicative of the targeting strategy. A delta lognormal error distribution was assumed in both cases, due to the high proportion of sets with zero catches (close to 80%). In both models the variable “Year” was the one which accounted for the greatest part of the explained variance, followed by its interactions with Target and Quarter, for the positive catches of the model with the Target factor, and followed by Year interactions with Quarter and Area in the model without the target factor.It was not clear, though, which of the standardized CPUE series reflected more accurately the actual abundance of the stock. RESUME