Nippon Suisan Gakkaishi 79 (6), 977-986 (2013)

Settlement period and growth of juvenile Fulvia mutica in Tokyo Bay

SATOSHI OHATA,1* MITSUHIRO ISHII2 AND MAKOTO KAJIYAMA1

1Chiba Prefectural Fisheries Research Center, Tokyo Bay Fisheries Laboratory, Futtsu, Chiba 293-0042, 2Chiba Prefectural Fisheries Research Center, Minamiboso, Chiba 295-0024, Japan

To examine the settlement period of juvenile Fulvia mutica and their growth, monthly dredge sampling was conducted at 24 sampling sites in Tokyo Bay from 2006 to 2010. According to shell length frequency analysis, the sampling sites were divided into two areas: northern and southern sea areas. In the northern sea area, many of the juveniles that had settled in autumn appeared from early winter, and disappeared the next summer probably due to the hypoxic water. On the other hand, in the southern sea area, while many of the juveniles that had settled in spring were caught even in summer, their growth was not observed until early autumn. A possible cause of the growth stagnation is hypoxic water, which develops during the summer. The growth of juveniles started in early winter in both sea areas, and the time taken to grow from 20 mm to 60 mm in shell length was shorter in the northern sea area than in the southern sea area.


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