NORFISK - an ecosystem simulation model for studies of the fish stocks off the coast of Norway

A biomass based ecosystem simulation model has been fitted to a restricted area of the Norwegian coastal waters. The model uses a holistic ecosystem approach and data on biomasses and their interaction with each other have been taken from the Møre region, western Norway. The main objective was to study interactions beetween cod, haddock saithe and herring and their prey in this area. lnitial estimation of the biomasses was based partly on acoustic methods and partly on data from the literature. Sampling of stomach contents was conducted to provide data for food composition tables. The calculations in the model were based on biomasses only, but in the analysis each species was treated as eggs and larvae, juveniles and adults to give biomasses with relative homogeneous structure and behaviour. The problems of intergroup recruitment and migration have been discussed. The results indicate that using such a model as a tool to treat data can give a better understanding of the ecosystem