This thesis focuses on the processes determining the dynamic of predator-prey interactions inside the North Sea food web. As further focus the predation impact on the recruitment of North Sea fish stocks is evaluated. In the course of the thesis the performance of currently used diet selection models in multi species fish stock assessment is investigated. The structural uncertainties due to critical assumptions on involved processes are quantified. The often ignored role of changes in spatial predator-prey overlap for the diet selection behavior of fish predator populations is highlighted. The thesis gives new insights in the mechanisms of predator-prey interactions on population level and guides the way for further improvements of currently used diet selection models. Finally, the obtained knowledge on predation processes and the diet selection of North Sea fish predators is utilized to demonstrate the role of predation in determining recruitment success of selected North Sea fish stocks.