Food habits of Japanese achovy in the Shirasu fishing ground within Sagami Bay.

In order to clarity food habits of Japanese anchovy in the Shirasu (anchovy larvae) fishing ground within Sagami Bay, gut contents were analysed during the period of July through October, 1984. This period was the major fishing season for Shirasu. The prey organisms in the guts consisted of 7 kinds of zooplankton. Copepoda were the most dominant prey items, Among others, Oithona comprised 67 numerical percentage of total prey organisms detected in the guts. Food preference of larval and juvenile anchovies was found to change with increase in lengths: TL 20-25mm size-class chiefly fed on O. davisae and Evadne, 26-30mm size-class on Paracalanidae and Penilia in addition to the former two items, and anchovy over 31mm fed on Oncaea, Microsetella, Bivalvia larvae and so on. Seasonal abundance of O. davisae in anchovy guts changed with the density of O. davisae in the bottom layer of the fishing ground. According to change of food preference with growth, anchovy probably moved from one region, where O. davisae was abundant, to the other region where another zooplankton was distribut-ed, so that the school seemed to be composed of almost the same size of anchovy.