熊野灘におけるイサキの食性

抄録

The present report deals with the feeding habit of Parapristipoma trilineatum, Pomadasyidae, based on 1208 individuals taken from coastal areas of Kumano-nada (Kii peninsula, central Japan) from March 1978 to September 1980.
Empty stomachs occurred more frequently in the samples collected by hook and line than in the samples collected by set net. Feeding activity was intense during the period from May to September, and declined after October. The main food of the immatures and adults, larger than 100mm in fork length, was clupeoid fishes, but crustaceans were fed on abundantly in March, June, November and December. Clupeoid fishes appeared as prey amimal in almost all seasons. Copepods chiefly appeared in spring and autumn, while amphipods in summer. The main food of juveniles, smaller than 50mm, were copepodid larvae and bivalve larvae. Those of young, 50-100mm, were Iucalanus spp., copepodid larvae, mysis larvae, zoea larvae and clupeoid larve. Maximum value of amax(=PLmax|L;L, length of predator; PLmax, mzximum size of prey) was 58% in the fish 50-100mm in fork length. The value of amax declined with growth for the fish larger than 100mm.