ICES guidelines for estimating discard survival

Research aimed at determining whether aquatic organisms survive after being caught and subsequently returned to the water has been conducted over many decades. Although there have been reviews of the outputs from this work (e.g. Davis, 2002; Broadhurst et al., 2006; Revill, 2012; Uhlmann and Broadhurst, 2015), there has, to date, been no comprehensive assessment of all the scientific methods and approaches that can be employed in meeting this aim. ICES Workshop on Methods for Estimating Discard Survival (WKMEDS) was established to describe and provide guidance on best practice for methods to quantify the survival of aquatic organisms caught and returned to the water.
Relevant work on discard survival has been conducted in commercial and recreational fisheries around the world, and the content of this report is designed to have global applicability. The catalyst for the formation of WKMEDS was the recent change in European Union fisheries policy, which has meant that there is a particular need for guidance on how to investigate levels of discard survival. Article 15 of the reformed Common Fisheries Policy (CFP) Basic Regulation, which came into force on 1 January 2014, introduced a phased discard ban or landing obligation for regulated species. The policy includes a number of exemptions and flexibility tools. In paragraph 4(b), an exemption from the landing obligation is described for “species for which scientific evidence demonstrates high survival rates, taking into account the characteristics of the gear, of the fishing practices and of the ecosystem”. To support any proposal for an exemption for selected species or fisheries, therefore, clear, defensible, scientific evidence of high discard survival rates are required. This has generated interest from various stakeholders in understanding the methods to generate discard survival estimates and in evaluating the quality and robustness of the results from survival assessments.
There are practical and scientific limitations to all of the methods currently available for estimating discard survival (ICES, 1995, 1997, 2000, 2004, 2005; Revill, 2012; Gilman et al., 2013). Consequently, there is a need for the provision of guidelines and identification of best practice for undertaking discard-survival assessments. In response to a request from the European Commission, through the Scientific, Technical and Economic Committee for Fisheries (STECF, 2014), to address this need for guidance, ICES established a Workshop on Methods for Estimating Discard Survival (WKMEDS) on 1 January 2014.
WKMEDS, chaired by Mike Breen (Norway) and Tom Catchpole (UK), were tasked to:
a) Develop guidelines and, where possible, identify best practice for undertaking discard survival studies (using the framework detailed in the report of STECF Expert Working Group EWG 13-16; ICES WKMEDS, 17–21 February 2014 workshop);
b) Identify approaches for measuring and reducing, or accounting for, the uncertainty associated with mortality estimates;
c) Critically review current estimates of discard mortality, with reference to the guidelines detailed in a and collate existing validated mortality estimates;
d) Conduct a meta-analysis, using the data detailed in c, to improve the understanding of the explanatory variables associated with discard mortality and identifying potential mitigation measures; and
e) Based on ToR a) to d) a Cooperative Research Report (CRR) should be developed for consideration by ICES Advisory (ACOM) and Scientific (SCICOM) committees. Subsequently revised to include ToR a) and b) only to contain the scale of the task.
This group worked by correspondence and a series of workshops were held 2014–2016: 17–21 February 2014, 24–28 November 2014, and 12–16 December 2017, ICES Headquarters, Copenhagen; 20–24 April 2015, London, UK; 30 November–4 December 2016, Ghent, Belgium; and 23–27 May 2017, Lorient, France.