Benchmark Workshop on Celtic Sea Stocks (WKCELTIC)

A Benchmark Workshop on Celtic Sea Stocks (WKCELTIC) to evaluate the appropriateness ofdata and assessment parameterization of three stocks: Cod in divisions 7.e–k (cod.27.7e–k), Whitingin divisions 7.b–c and 7.e–k (whg.27.7b–ce–k) and Haddock in divisions 7.b–k (had.27.7b–k).The procedure to calculate catch in number and weight-at-age were revised in a data-compilationworkshop. The approach was standardized and streamlined across countries and stocks asmuch as possible using a common R-script, ensuring transparency and reproducibility. Naturalmortality and maturity-at-age were updated.For all stocks survey indices were calculated based on the VAST software in attempt to addressissues of missing survey coverage in some years. As before the indices were based on the IGFSWIBTS-Q4 and EVHOE-WIBTS-Q4 surveys. This resulted in the new indices having a higherinternal consistencies among stocks compared with the conventional calculation that had beenin use previously.The assessment framework for all stocks was based on SAM (https://www.stockassessment.org)because of availability, reproducibility, statistical handling of discard estimates where neededand familiarity of the external reviewers with the method and software. The approach consistedof gradual introduction of new data to identify the influence on stock dynamics and configurationof the model setup based on diagnostic comparisons. The reference points were updatedbased on the final results using ICES standard procedures. Forecast is produced internally withinSAM to ensure consistency.