Tenth Workshop on the Development of Quantitative Assessment Methodologies based on LIFE-history traits, exploitation characteristics, and other relevant parameters for data-limited stocks (WKLIFE X)

The Workshop on the Development of Quantitative Assessment Methodologies based on Lifehistory traits, exploitation characteristics, and other relevant parameters for data-limited stocks (WKLIFE X), chaired by Carl O'Brien (UK) and Manuela Azevedo (Portugal) met virtually 5–9 October 2020, to further develop methods for stock assessment and catch advice for stocks in Categories 3 and 4, focusing on the provision of sound advice rules that are within the ICES MSY framework.

This tenth workshop was convened to further address the challenges to the evidence base for the provision of ICES advice with specific reference to data-limited stocks. There is an increasing number of fish stocks in Categories 3 and 4 for which assessment of status relative to MSY proxy reference points is available but for which short-term forecasts and MSY-based advice are not available.

For assessments using the stochastic surplus production model in continuous time (SPiCT), WKLIFE X developed and evaluated ‘fractile rules’ that account for uncertainty and allow to consider any percentile and demonstrated that ‘fractile rules’ are more effective and precautionary than the median rule (50th percentile) and the ‘2 over-3’ rule.

Additional work on advice rules for stocks in Category 3 based on life-history traits (k), tested through simulation and management strategy evaluation (MSE), showed that the addition of specific multipliers based on the stock’s life-history characteristics decreases the risk of the control rule´s performance.

Annex 3 to this report contains the revised technical guidance on methods and advice rules for stocks in Category 3. The revision of the accumulated decade of ICES documentation on methods and advice for data-limited stocks into a stand-alone technical guidance document requires significant effort and dedicated work beyond the time available at the WKLIFE X meeting.

It is proposed that a dedicated workshop be established to undertake and complete the updating and revision into a single reference document.