Seasonal dynamics of the catch per unit effort of Brazilian mackerel, Scomberomorus brasiliensis, caught with gill nets off Pará State, Brazil

Abstract

The gill net is the most frequently used fishing gear for fish-catching on the continental shelf off the norhtern Brazil and, and in each one of the fishsing communities a particular type of net is developed which is amenable to constant improvement according to the fishermen’s experience. Given the relevance of Brazilian mackerel, Scomberomorus brasiliensis, to the marine fisheries of Pará State, invesstigation is requeired on the main features of its fisheries biology such as spatial coverage by the fishing fleet, estimation of their respective indices of catch per unit effoert (CPUE) and its seasonal variations, so that the scarcity of relevant information for the above-mentioned region must be accounted for. In this paper, the analysis was based on data retrieved from scatter sheets on landings and fishing effort gathered over the period 2000 - 2003 through the Statpesca Project run by CEPNOR/IBAMA. The boat was considered as the sampling unit, so that all boats were sorted out in homogeneous groups according to their characteristics. The CPUE values measured in kg per 1,000 meters of net converted to score post so as to be made amenable to analysis between the rainy and dry seasons of a year by the Kruskal-Wallis’ H statistic. CPUE for Brazilian mackerel, irrespective of the type of boat, was found to be higher during the rainy season, with a value of 21.8 kg pee 1,000 meters of gill net.