若狭湾に出現する子魚の食性に関する研究 ＩＶ ササウシノシタ子魚の分布と食性

Abstract

This paper describes the vertical and horizontal distributions, and feeding habits of a sole Heteromycteris japonicus (TEMMINCK et SCHLEGEL) larvae, collected in the western Wakasa Bay, Japan Sea, from June to September 1981. The larvae H. japonicus distributed mainly in the waters between 25m and 50m depth. Small size larvae of less than 3.0mm BL commonly appeared at Sts. A, B and C, and large size larvae of more than 4.0mm BL abundantly at St. A. It is suggested that the larvae shift the habitual area from “offshore-coastal area” to “coastal area” as growth of the larvae proceeded. The larvae of less than 4.0mm BL fed mostly on Microsetella norvegica and copepod nauplii. Most of the same size larvae caught at St. A ate M. norvegica, but at St. C. larvae fed on M. norvegica and copepod nauplii. Percentage of larvae carrying food in their alimentary canal was high in those collected at St. A and low at St. C. The larvae of more than 5.0mm BL consumed mainly Penilia avirostris, Podon sp. and M. norvegica. According to these findings on feeding habits of the larvae of H. japonicus it is estimated that the offshore area is umsatisfactory for survival of the larvae, compared with the coastal area.