A combined Gadget/FLR model for management strategy evaluations of the Barents Sea fisheries

A biologically sensible age-length structured multispecies Gadget model (incorporating minke whales, cod, herring, and capelin) for the Barents Sea-acting as the operating model-has been linked to Fisheries Library in R-acting as the management procedure-to perform management strategy evaluations. Assessments may be run using either XSA, survey-based methods, or by taking modelled stock numbers directly. Total allowable catches are based on the assessment and harvest control rules (HCRs). The tool can be used for assessing a wide variety of sources of uncertainties within the assessment process. Model structure and linkages are described and a fit to the historical data is presented. A base case of future dynamic (non-steady state) stock trends, based on the existing HCRs, is compared with alternative management and environmental scenarios. The relative differences for each scenario in terms of stock size and catches highlight a number of uncertainties within the biological and fisheries system. The results indicate that the current management rules are robust to the range of scenarios examined so far.