Fish assemblage structures on artificial sandy beaches in inner Tokyo Bay, central Japan

Abstract

Daytime seine net sampling was conducted on three artificial sandy beaches（Inage, Kemigawa and Makuhari）formed on reclaimed land at Mihama, Chiba Prefecture, central Ja- pan, in September and November 2017, and May and July 2018. A total of 1091 individual fishes, representing 19 families and 23 species, were collected throughout the study period. Five species （Lateolabrax japonicus, Platichthys bicoloratus, Konosirus punctatus, Hypoatherina valenciennei and Plecoglossus altivelis altivelis）were dominant, accounting for 87. 4% of all individuals. Al- most all of the species collected were represented only by juveniles, suggesting that the artificial sandy beaches were used as an important juvenile habitat by a variety of fishes. Although no differences in total numbers of fish species and individuals, and species composition were found among the three beaches, the mean standard length of fish pooled for each species tended to be smaller on Kemigawa Beach than the other two beaches. This difference may be due to the pro- tected aspect of the former beach, resulting in relatively low wave activity, due to the construction of inwardly-curved groins on either side of the beach.