MULTISPEC - a multi-species model for fish and marine mammals in the Barents Sea

Abstract

A detailed description is given of MULTISPEC, which is an area, age and length structured multispecies simulation model for the species capelin (Mallotus villosus), herring (Clupea harengus), cod (Gadus morhua), harp seal (Phoca groenlandica) and minke whale (Balaenoptera acutorostrata) in the Barents Sea. In the model, both harp seals and minke whale, and cod, prey on capelin, herring and cod, and in addition, herring prey on capelin larvae. Cod is the most important predator. Information on food preferences and food requirements obtained from the Norwegian research program on marine mammals is used to quantify the predation by marine mammals on fish. The sensitivity of the model to the stock sizes and food preferences of harp seals and minke whales is investigated, together with the sensitivity to the food preferences of cod. A tentative conclusion on likely effects of an increasing whale stock is that the herring stock will be most heavily affected. An increasing harp seal stock will most heavily affect the capelin and cod stock. The model is more sensitive to changes in the food preferences of cod than to changes in food preferences or stock sizes of marine mammals.