Elasmobranch bycatch in a trammel net fishery in the Portuguese west coast

摘要

Elasmobranchs are an important bycatch component in Portuguese artisanal fisheries, but there are no management or monitoring programs in place yet. This study analysed elasmobranch catches in a Portuguese west coast trammel net fishery. Thirty-seven sampling surveys were conducted aboard commercial fishing vessels on a seasonal basis between October 2004 and August 2005. A total of 11 elasmobranch species were caught (seven Rajiformes, two Torpediniformes and two Carchariniformes), representing 4% of total catches and 15% of total weight. Raja clavata was the most important species in number (7.4 ind 10,000 m(-1) of net) and Raja undulata the most important in weight (8512.4 g 10.000 m(-1) of net). Discards represented 7.8% of total catch in weight, but 24.8% in number of specimens caught. Seven elasmobranch species were commonly discarded. There was a marked seasonality in elasmobranch catches, with lowest species richness registered in spring (four species) and highest in autumn (11 species). For the most abundant species depth range preferences were assessed.