The black scabbardfish (<i>Aphanopus carbo</i> Lowe, 1839) fisheries from the Portuguese mainland and Madeira Island

Abstract

For several decades, the black scabbardfish ( Aphanopus carbo , Lowe 1839) has been a valuable resource for fishing communities in Madeira and more recently for those in mainland Portugal. The evaluation of the species’ exploitation status was conducted only in the late 20th century and separated for the two areas of the Portuguese Exclusive Economic Zone (EEZ). Nowadays, species stock assessment studies are usually conducted in the framework of scientific working groups from regional fisheries organizations: ICES analyses data from the fishery operating in continental waters, whereas CECAF deals with the data pertaining to the Madeiran fishery. This paper presents the first attempt to combine the information available from the two longline fisheries targeting black scabbardfish in Portuguese waters in one single analysis. A description of the two fleets’ technical characteristics was conducted and a unique model was developed for the standardization of the fishing effort aimed at the species in the Portuguese EEZ. From this model, weekly landings-per-unit-effort time series were estimated by region for the period 2005-2007 and compared using a non-parametric statistical test. Percentages of discarded species, in number and weight, were calculated and reveal consistently low figures. These discards seem to depend on the number of hooks, soaking time and depth.