Immigration Patterns to Uranouchi Bay as a Nursery Ground of Fish Larvae in Summer

Abstract

To clarify the immigration pattern of fish larvae and juveniles into bay areas, discrete depth tows with a larva net were conduced on flood and ebb tides in the mouth part of Uranouchi Bay, Japan in June and August 2000. A total of 11,904 fishes (mean density: 855 ind. 1000m^-3) of more than 100 species from 48 families were collected on flood tides and 5,004 fishes (398 ind. 1000 m^-3f木村保) of more than 61 species from 32 families on ebb tides. Number of species and mean densities were significantly greater on the flood tide than on ebb tide. Among dominant species, Engraulis japonicus and Sardinella zunasi were denser on flood tides, immigrating through the surface into the inlet, and being inlet-dependent species as nurseries. No significant difference in mean densities were found between flood and ebb tides in Spratelloides gracilis, Apogon niger and four blenniid species, which tended to enter into and leave the bay at middle and/or bottom layers. They seemed to be inlet-independent species.