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

The objective of the Twelfth Workshop on the Development of Quantitative Assessment Methodologies based on Life-history traits, exploitation characteristics, and other relevant parameters for data-limited stocks (WKLIFE XII) was to further develop methods for stock assessment, stock status, and catch advice for stocks in ICES Categories 2–6, focusing on the provision of sound advice rules adhering to the ICES advisory framework and principles for fisheries management. This report addresses (i) questions from different ICES assessment working groups and stakeholders regarding the applicability of the data-limited technical guidelines, (ii) the prioritisation of future tasks regarding the ICES data-limited framework, (iii) further development and testing of data-limited methodologies with specific focus on the review of the current ICES advice framework for stock Categories 4-6, spatial indicators, and reference points for surplus production models, and (iv) other relevant data-limited topics. A survey of participants resulted in a high prioritisation score of four topics of the ICES data-limited roadmap: (1) risk equivalence, best available science, guidelines and communication of data-limited methods, (2) value of information of different data-types and data preparation, (3) better advice for slow-growing species, and (4) observation and parameter uncertainty in empirical harvest control rules and length-based approaches. The current ICES approach for Category 5 and 6 stocks, with an advice for constant annual catch and a periodic reduction with a precautionary buffer, is a form of non-adaptive management and an initial review revealed that it may not be precautionary if a stock is overfished but also overly precautionary in other situations. An exploration of spatial indicators showed that these have the potential to inform on stock status. A stochastic definition of MSY B_trigger for surplus production models takes uncertainty into account and leads to higher reference values than the current definition for stocks with low and intermediate biomass variability.