A Model of Trophic Interactions in the North Sea in 1981, the Year of the Stomach*

This paper gives an overview of the trophic interactions in the North Sea in 1981 when 55,000 fish stomachs were sampled and analyzed. The study is based on the data base of the ICES Multispecies Assessment Working Group (MS WG), and published information. A balanced, steady state model of interactions and biomasses at all trophic levels is constructed using the ECOPATH II software. The results indicate that the food consumption rates used by the MS WG for three of the important gadoid species are unrealistically low, whereas other parameters appear very reasonable. Results from mixed trophic impact analysis, trophic aggregation, and other network analyses are presented, and the results are compared with earlier studies of the North Sea food web. Summaries are given to illustrate the distribution of flows between demersal and pelagic components, and between large ecological groupings Dedicated to the memory of the late Rodney Jones, whose pioneering work on the energy flow structure in the North Sea was of major importance for our understanding of the North Sea as an ecosystem. ICLARM Contribution No. 855.