The importance of intertidal sand-burrowing peracarid crustaceans as prey for fish in the surf-zone of a sandy beach in Otsuchi Bay, Northeastern Japan

Abstract

Predation on intertidal sand-burrowing peracarid crustaceans by fish was investigated in a diel regime in the spring and summer of 1994 and 1995 in the surf-zone of a sandy beach in Otsuchi Bay, northeastern Japan. The mysid Archaeomysis kokuboi, the amphipod Haustorioides japonicus, and the isopod Excirolana chiltoni were the main peracarids preyed on by the surf-zone fish. The importance of each prey species was evaluated using indices of stomach fullness and the relative importance of each food item. The fish in the surf-zone exploited A. kokuboi predominately, and it was found in 60 and 71% of all the stomachs examined during the spring and summer, respectively. The mysid was preyed upon by Schlegel's black rockfish, the Japanese anchovy, the Japanese flounder, Ransonnet's surfperch and the Japanese opaleye, and this predation occurred exclusively at night. H. japonicus was found in 33 and 39% of the stomachs examined during the spring and summer, respectively. The amphipod was preyed upon by the green puffer, Ransonnet's surfperch, and the kite-fin dragonet. In contrast to the mysid, it was more important as prey during the daytime than at night. This study showed that a major part of the diet of surf-zone fishes consists of intertidal sand-burrowing peracarid crustaceans, suggesting that the surf-zone is a productive feeding ground for these fish.