Food of anadromous brown trout at sea

The food of migratory Salmo trutta in coastal marine waters along the Norwe gian Skagerrak coast varied significantly with age, season and habitat of t he fish. The main prey categories in terms of frequency of occurrence were fishes followed by crustaceans, surface insects and polychaetes. Seasonal v ariation in diet and within habitats was found, supporting the view that br own trout is an opportunistic feeder. An ontogenetic niche shift was observ ed with post-smolts feeding on inshore and shallow water prey communities, while larger brown trout fed mainly on pelagic fishes. (C) 2001 The Fisheri es Society of the British Isles.