Annual variation in the prey utilization of juvenile Japanese flounder in southwestern Hiuchi-Nada, Seto Inland Sea, Japan

Abstract

Past studies indicated that newly settled juvenile Japanese flounder Paralichthys olivaceus depend on mysids as their main prey source, but little is known about the prey of juveniles in nursery grounds with a low density of mysids. This study aimed to reveal the annual variation in the main prey items of juvenile Japanese flounder in relation to their growth in southwestern Hiuchi-Nada, the Seto Inland Sea, Japan. Juvenile flounder consumed chiefly larval anchovy in 1995 and 1999, while small crangonid shrimp Crangon uritai were the main prey items in 1998, 2003, and 2004. The growth rates of juvenile flounder ranged from 0.82–1.33 mm d−1 during the five years of this study. Mysids were almost absent and small crangonid shrimp were abundant in the study area. Our results indicate that juvenile Japanese flounder prefer larval anchovy, but small crangonid shrimp function as the alternative prey when larval anchovy and mysids are not available in the study area.