The clarified cohort model for the Barents Sea cod stock assessment
2020
Vasilyev, D.A. | Kovalev, Yu.A. | Chetyrkin, A.A.
The SAM model is used for North-East Arctic cod stock assessment since 2017. The configuration for the model was agreed at the ICES special benchmark group. This configuration assumes the same properties of errors for all age groups within the same kind of surveys and in catch-at-age data. The results of the analysis show that for North-East arctic cod this assumption is not valid and for correct stock assessment a more detailed specification of variances is required. This is caused by significant change in age structure of the cod stock in recent years towards higher portion of elder age groups. The clarified model options described here had resulted in significant improvement of assessment diagnostics and more precise results of North-East Arctic cod stock assessment
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