Modelling approach for evaluating of natural mortality variation caused by cannibalism in the Barents Sea cod

No abstracts are to be cited without prior reference to the author.

Cannibalism is an important population mechanism to control cod abundance in response to environment variations. The estimates of the Barents Sea cod cannibalism calculated on the basis of the quantitative analysis of stomach content have been available since 1984. Based on these estimates the quantity of juveniles consumed by cod significantly varies from year to year and depends on abundance and age composition of adult cod, juvenile abundance, as well as the stock size of capelin as a main food item. Using a multispecies STOCOBAR model, an attempt to extend the time-series of data on cod cannibalism on the basis of the accessible historical data on capelin abundance, cod commercial stock, and water temperature since 1972 has been made. The dependence of rate of cod natural mortality through cannibalism on capelin stock size in the Barents Sea under different temperature and cod stock was analysed, applying scenario modelling. The aspect of improvement of cod harvest control rule based on obtained findings is considered.