Feeding ecology of dominant demersal fish species Favonigobius gymnauchen, Repomucenus spp. and Tarphops oligolepis at a sandy beach where larval Japanese flounder settle in the Seto Inland Sea, Japan

摘要

Feeding habits of Favonigobius gymnauchen, Repomucenus spp. and Tarphops oligolepis were examined during the period from May to August in 1999, 2000 and 2001 at a sandy beach in the central Seto Inland Sea, Japan. The three species of fish accounted for more than 60% of all fish collected in terms of number of individuals. All three species mainly consumed small crustaceans. However, the major prey of F. gymnauchen and Repomucenus spp. differed from that of T. oligolepis. F. gymnauchen and Repomucenus spp. mainly consumed mysids and small crangonid shrimp (<12 mm in body length), which predominated in the study area. T. oligolepis actively selected only epifaunal mysids Nipponomysis ornata and avoided crangonid shrimp and gammarids. The frequencies of occurrence of fish in the guts of the three dominant species were very low, and larval and juvenile Japanese flounder were not observed in any of the three fish species. The diet of juvenile Japanese flounder was similar to that of the three species. From these results, it appears that these three fish are competing species for the flounder.