Elasmobranch species richness,fisheries, abundance and size composition in the Azores archipelago (NE Atlantic)

ABSTRACT

Elasmobranchs are a vulnerable resource, more susceptible to overfishing than most teleosts, and their assessment is complicated due to a general lack of information about their fisheries, biology and ecology. This study aimed to analyse all fishery and survey data available for elasmobranchs caught over the past c. 25 years around the Azores (NE Atlantic) to provide a baseline information, which can be used to inform stock assessment and management strategies. Elasmobranch species covered pelagic, benthopelagic and demersal habitats, from shallow to deep-water strata in areas around the islands and seamounts. These species are taken accidentally as by-catch of three main fisheries: swordfish fishery, black scabbardfish fishery and demersal bottom longline fishery. The latter represents one of the most important fishing activities in the Azores, and frequent elasmobranch by-catches include Raja clavata, Galeorhinus galeus, Deania calcea, D. profundorum, Etmopterus pusillus and E. spinax. A slight reduction in the abundance indices of these species was observed, despite the implemented technical measures (e.g. minimum size, zero catch). Little is known about resource dynamics for the Azorean region and no analytical assessments have been conducted. This study highlights the vulnerability to overfishing of these resources and the urgent need to develop management strategies.