抄録
Intraspecific relationships for food in righteye flounders Limanda herzensteini and L. yokohamae in Mutsu Bay, Aomori Prefecture, were studied. In both species, body length distributions did not differ very much among sea areas. In spring (May), the size (by wet weight) of prey in L. her-zensteini stomachs was independent of fish length. But in summer, the prey size ingested by L. herzensteini became larger sequentially with increase of fish length, indicating the existence of strong size selection for prey. The same was apparent for L. yokohamae. Intensity of size selection of both species was closely related to the food availability and the intensity of food requirement in relation to their annual life period. Namely, the size selection was found as high abundance of food and inactive feeding of fish. These results suggested that the intraspecific competition for food in L. herzensteini may possibly occur in spring but in summer it becomes weak because they ingested prey of different size with fish length. On the other hand, for L. yokohamae, considering that in spring the kind of prey ingested by them depended on fish length, it seems probable that there is less likelihood of intraspecific competition for food at least during spring and summer.
