1Akkeshi Station of Japan Sea-Farming Association, Akkeshi, Hokkaido 088-1108 and 2Japan Sea National Fisheries Research Institute, Niigata, Niigata 951-8121 Japan
Hatchery-reared barfin flounder Verasper moseri were released and recaptured in Akkeshi Bay, and their stomach contents were examined. Food organisms were classified into Mysidacea, Flabellifera, Crangonidae, other Decapoda, Pisces, and others. Five indices were applied to analyze the stomach contents: frequency of occurrence, percentage of number and weight, index of relative importance and trophic level index. Dominant prey items changed with size, Mysidacea (size≤150mmTL), Mysidacea and Crangonidae (150-250mmTL), Crangonidae and Flabellifera (250-300mmTL), Crangonidae (300-400mmTL) and Crangonidae and Pisces (>400mmTL). Trophic level index also increased with size, indicating a higher food niche of larger barfin flounder. The food niche of the barfin flounder was low in spring and increased in summer and autumn.