Removal of a forage fish has consequences for both predators and prey of forage fish. As everything is connected, every management action has a price which goes beyond the apparent, direct effect on the target species. The fishery on forage fish can therefore not be seen in isolation, as the immediate gain in profit from the fishery has to be discounted by the lowered potential for production of large piscivorous fish. Management actions on other species also influences forage fish, i.e. conservation efforts on marine mammals or sea birds have direct consequences for the predation pressure on forage fish. The objective of the project is to provide insight and quantitative advice on the ecosystem wide consequences of management actions directly or indirectly related to forage fish. The two overarching questions are: 1. What are the consequences of forage fish fisheries on (a) predator growth and abundance, (b) economic output of fisheries on piscivorous species, and (c) ecosystem stability and the risk for regime shifts? 2. What are the consequences of changes in predator populations on forage fish populations and fisheries? The methods is a combination of ecosystem models, of process studies aimed at feeding into the models, of economical models, and of data-analysis of existing data sources. The project covers four ecosystems in detail; Norwegian-Barents Sea, Baltic Sea, North Sea and Bay of Biscay. FACTS bring together leading European fisheries and university institutes working on creating the tools for ecosystem based management. The active involvement of the institutes in the current management provides a means for the results of the project to feed into management. The project furthermore includes a network component which ensures a wider dissemination of methods and results within the marine scientific community.