assessing the status of demersal elasmobranchs in uk waters: a review

Abstract

elasmobranch fish are susceptible to over-exploitation by commercial and recreational fisheries and an increasing focus of conservation initiatives. the lack of accurate species-specific landings data in many european fisheries and the paucity of biological data have restricted the types of stock assessment that can be undertaken. hence, other methods of determining the overall status of elasmobranch fish are required. for demersal elasmobranchs around the british isles, the most widely available biological data describe life histories and abundance from fishery-independent surveys. here, we examine the length-distribution of demersal elasmobranchs caught during groundfish surveys, to determine which life history stages are sampled effectively. for these stages, we report trends in abundance and relate the trends to knowledge of the species' biology and fisheries, and to the decline criteria that are used to assess species' status by nature conservation agencies. the analyses show that many large demersal elasmobranchs have been severely depleted in uk waters but that groundfish surveys still provide a good source of data for monitoring changes in status of the more abundant species. for rare and highly depleted species, groundfish surveys often provide good retrospective descriptions of declines, but the surveys have limited power to detect recent changes in status.