Feeding Habits and Distribution Pattern of Two Forms of Flatfishes (Genus Pleuronichthys) in Kiisuido Channel Waters off the Pacific Coast of Central Japan

Abstract

Feeding habits of two forms of flounder belonging to the genus Pleuronichthys, form A (Japanese local name: Honmeita) and form B (Bakemeita), gathering around Kiisuido Channel waters were investigated. Both forms of flounder feed chiefly on Polychaeta. The former also feed partly on Amphipoda, Gastropoda, Anthozoa, and Bivalvia, and the latter on Am-phipoda. Of Polychaeta, Eunice indica, Kinbergonuphis enoshimaensis, Paraprionospio sp. (Cl), Lygdamis giardi, Ampharete sp., and Amphicteis sp., which inhabit a wide depth range, appearedin the stomachs of both flounders. But form A often predated on polychaetes which occurred in shallower water, such as Diopatra sugokai and Owenia fusiformis, while form B fed on polychaetes in deeger water, such as Eunice fauchaldi and Onuphis spp. Based on these re-sults, together with the pattern of occurrence of their eggs, it was concluded that form A inhabits waters shallower than 80m, while form B occupies waters deeper than 60m. Their distribution overlaps mainly in the area between 60 and 80m depths where the two forms are thought to compete for food.