Ecological Studies on the Clam, Tapes japonica (REEVE)-II
On the Setting Season and the Growth in Early Young Stage
1957 Volume 22 Issue 12 Pages 736-741
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1957 Volume 22 Issue 12 Pages 736-741
In order to know the setting season and the growth of Tapes japonica in their young stage, the author has collected this species over the period 1952 to 1955, at four localities in the Sea of Ariake (Table 1, Fig. 1). The results obtained are summarized as follows :
1) The major periods of the setting are twice a year. One is in May and the other is from the end of November to early December, but the setting in the former season is unstable (Table 2, Fig. 2).
2) The density of setting in December reaches above half a million per one square meter. The young clams set in this season maintain the resources of this species, though those deposited in spring seem to be extinct (Table 2).
3) The growth curve of the young clam which sets in November and December has several changing points in its growth rate. The shell length on the coast of Saga Prefecture in the Sea of Ariake, reaches 1mm. four months after setting (early April), 10mm. after six months, and 27mm. after a year (Figs. 3, 4).
