The diversity, distribution and status of deep-water elasmobranchs in the Rockall Trough, north-east Atlantic Ocean

Data from a scientific deep-water trawl fisheries survey in the north-east Atlantic were analysed to determine the spatial and bathymetric distribution of elasmobranch species and assess the change in relative abundance over the period 1998-2013. During this period, commercial fisheries for deep-water sharks went from being entirely unregulated, to being briefly managed, to being completely prohibited. A total of 22 species of shark and 10 species of skate were recorded between depths of 300 and 2030 m. All showed strong species-specific depth-related trends in abundance. Out of the 11 more common species, five showed no change in relative abundance over time, two (Centrophorus squamosus and Centroselachus crepidater) declined significantly and four increased in relative abundance (Apristurus aphyodes, Apristurus microps, Galeus melastomus and Deania calcea). Assuming these populations were depleted by fisheries in the past, the current data do not suggest there has been an overall recovery. Positive signs for some species in the most recent years suggest movement or recruitment back into the area; however, it is of concern that two species continued to decline. There is a continued need to have precautionary management of these elasmobranch species, and the current ban on landing these species in European waters remains appropriate.