Stomach content analysis of North Sea cephalopods: often-overlooked predators with direct impact on commercially used fish species?

The study of marine food web models has increased during the last years, but input data of important groups such as cephalopods are missing sometimes which restricts the quality of the model results. Cephalopods feed on a variety of preys, ranging from small crustaceans to large commercially important fish species. In turn, they are taken by larger invertebrates, fish, cephalopods, marine mammals and seabirds, which emphasizes their important role in various marine food webs. Our study presents stomach content analyses of various cephalopod species from the North Sea and describes their general feeding trends. The results further support the inclusion of cephalopods as predators into food web models to increase our knowledge of the North Sea ecosystem and to improve its management. Our data in combination with observed increasing biomasses of North Sea cephalopods suggest that the impact of cephalopods in the North Sea food web has increased and that large-sized cephalopods have become more important as predators for commercially exploited fish species during recent years.