At present, there exists a conceptual model of the effects of the physical and seasonal environment in the Norwegian Sea on the feeding behaviour, vertical and horizontal migrations, growth and life cycle of Calanus finmarchicus and herring, and also of t he effects of these two population upon each other. ADAPT aims at exploring this model in detail, and move from a conceptual to a numerical model of the adaptation of these two populations to the environment and each other. ADAPT will also challenge the c onceptual model by analysis of field data for the hydrography-phytoplankton-Calanus and the Calanus-herring interactions. The quality of the numerical model will be studied by comparison with the field data. An adaptive model of several trophic levels in a large-scale ecosystem has not been attempted before. A numerical simulation model of hydrodynamics, phytoplankton, zooplankton and fish will be valuable for later studies of the impact on environmental variation and change. The project is a co-operation between the Institute of Marine Research (Bergen), University of Oslo, and University of Bergen.