This project aim at integrating process understanding in operational fisheries management under present day climate and future climate scenarios. The NE Atlantic harbours some of the worlds largest stocks of herring, blue whiting, mackerel, capelin, cod, haddock and saithe. The stocks interact direct or indirect through competition and through predator-prey relationships. Another role is the impact planktivorous fish have on the ecosystem through depletion of plankton. Climate affects recruitment in the s tocks and warm periods are in general linked with high recruitment. We anticipate major changes in our northern ecosystems in the coming years, in particular with regards to changes in biogeography, as observed already. These changes will also affect the trophic flows in the ecosystems and establish new predator-prey relations and modify existing ones. In order to address the anticipated climatic changes we therefore need tools that can integrate the biogeoraphy of the ecosystems with the trophodynamics. When moving outside the observed range of climatic variability, statistical models parameterised for the present climate variability are unsuitable for providing predictions. Instead we propose to develop further an existing 3D biophysical model to includ e the fish stocks listed in addition to the phyto and zooplankton. This model will integrate spatial dynamics of the fish stocks over the entire life cycle and their interactions with the environment including each other. To perform operationally realisti c ecosystem based assessment modelling, a simpler model that can perform multiple simulations in order to address uncertainty will be developed based on an existing operational IMR multispecies model for the Barents Sea. This model will be parameterised u sing the biophysical model both for present day climate and for a future climate change scenario. Eco-harvest control rules for the fish stocks will be developed and evaluated.