No abstracts are to be cited without prior reference to the author.Ecopath with Ecosim methodology is a widely used tool for the quantification of food webs and analysis of ecosystem dynamics (Pauly et al. 2000). The approach is founded on a static description of the ecosystem represented by biomasses aggregated into ecologically functional groups. Predators and prey are linked through consumption defined by the diet composition matrix and consumption rate parameters. At present, 3 published Ecopath models exist for the North Sea. Based on 1981 year of the stomach data Christensen (1995) constructed two models representing the 1981 period; a 24 box model and 29 box model including more detailed, size based plankton groups. Mackinson (2002a), constructed a detailed historical representation of the North Sea in the 1880s which includes 49 boxes, with catch data for five different fishing fleets, and has been used in an examination of the utility of Ecosim’s harvest policy analysis routine (Mackinson 2002b). The Ecopath approach provides a common platform for model development that will enable us to make comparisons of the North Sea with other marine ecosystems, particularly those surrounding the UK coast and North Atlantic.