Some comments on the variatios of the catchhability coefficient in the longline fisheries with hooks

Abstract

When CPUE is used as an index of relative abundance, the standardization of fishing effort is necessary to keep constant the catchability coefficient, aiming to determine the variation of effective fishing time, fishing power, fleet distribution, etc. Although passive fishing gears have, at first sight, an easier fishing effort standardization, their CPUE depends more on fish behavior regarding to bait attraction. Therefore, its catchability coefficient will be affected by a number of factors, with a more complex standardization effort process than that used for active fishing gears. This paper discusses four factors affecting longline catchability coefficient: baits, natural factors, technological factors and crew, showing that different fishing operations probably do not have compatible efforts, even when carried out by the same boat, due to variations in the analyzed factors. Consequently, the obtained CPUE by commercial fleet catch and effort informations does not represent a realistic value of the relative abundance of captured species.