Food habits of domestic introduced fish Coreoperca kawamebari in Gokase River System, Miyazaki Prefecture, Kyushu, Japan: examination of predation on diadromous shrimps

The present study surveyed stomach contents of Coreoperca kawamebari which domestically introduced into the Gokase River System (northern Miyazaki Prefecture, Kyushu, Japan) to understand the predation impacts on native diadromous shrimps. The stomach contents comparison before/after season of dia-dromous shrimp migration revealed that percent volume and frequency of a diadromous shrimp (Paratya compressa) in the stomachs of larger C. kawamebari (> 50 mm in standard length) tended to increase after migration season. Furthermore, shrimp and fish individuals were found in the stomachs of smaller C. kawamebari specimens than previously reported. According to these results, C. kawamebari should be considered as a domestic invasive species that might have an impact on diadromous animal populations, and strict caution is required regarding the introduction and occurrence of this species in waters connected to the sea.