Feeding Habit of Larval and Juvenile Ayu, Plecoglossus altivelis in the Surf Zone of Tosa Bay, Japan

Abstract

A total of 7,000 larval and juvenilePlecoglossus altivelis was collected at semimonthly intervals with a small seine in a surf zone of Tei beach facing Tosa Bay during the period of June 1982 to May 1983. They occurred in the surf zone from middle October to middle May. About 500 larvae and juveniles (10.9–59.9 mm TL) were used to examine their feeding habit. The feeding incidences by collection dates fluctuated from 0 to 100%, with 90.6% in total incidence. They fed mainly on copepods (e.g.Paracalanus parvus andOithona spp.) throughout postlarval and juvenile stages, while they first took small benthic animals at 53.0 mm TL. Their food compositions were influenced fundamentally by the planktonic fauna of the surf zone, but larvae under 20 mm TL tended to take relatively larger copepods.