Using UWTS to assess and advise on <i>Nephrops</i> stocks

Norway lobster (Nephrops norvegicus) is a commercially important species in the Northeast Atlantic, and in relatively recent years, fisheries in many countries in this region have expanded rapidly to exploit this valuable market. In the last 20 years, underwater television (UWTV) surveys have played a significant and ever increasing role in gathering data for use within ICES stock assessment process. Management advice on Nephrops stocks is derived from these data and, with several countries now undertaking such surveys, standardized approaches and technologies have been agreed and adopted as best as practically possible. This report describes the use of UWTV surveys in the assessment and provision of management advice for Nephrops stocks. This includes (i) the history of underwater photography and the development of Nephrops-specific surveys; (ii) the equipment used and the utilization of various survey designs; (iii) Nephrops burrow identification and quality control; (iv) caveats and uncertainties associated with the methodologies; (v) the statistical analyses used and the incorporation of survey results into the assessment process; and (vi) the further utilization of the survey data beyond the primary task. This report was compiled by various members of ICES Working Group on Nephrops Surveys (WGNEPS) and we thank Ian Tuck, University of Auckland, for his review.