Vertical distribution of feeding- and mortality rates of Calanus finmarchicus in the Norwegian Sea

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From net-catches and echo-sounder data, we estimate the vertical distribution of environmental parameters and potential food and predators for Calanus finmarchicus at a station in the Norwegian Sea. These profiles are combined with mechanistic models of prey- and predator encounter- and feeding rates to produce vertical profiles of growth- and mortality rates of C. finmarchicus. The mortality rate varied by orders of magnitude through the water column, while modest variation in temperature and food availability led to moderate differences in growth rate between depths. Herring was pointed out as the most important predator, while blue whiting, lanternfish and krill were the main predators below 120 m. We argue that combining mechanistic models of feeding processes with real data of in situ situations is an approach that could increase our understanding of ecosystem functioning.