Some comments on recovery on the Manila clam resource and present state of inshore ecosystem
2005
Kikuchi, T.(Kyushu Lutheran Coll., Kumamoto (Japan))
The annual yield of the Manila clam in Japan decreased in recent years but the cause of mortality is unclear. To analyze the long time decrease of the clam, both studies on habitat conditions for both juvenile and adult clam, and studies on settlement of pelagic larvae in adequate habitats, and recruitment of benthic stage were made. To estimate the size of stock population and stability of recruitment and young immature shells, the author proposed establishment of Marina reserve. In sand flat of the Ariake Sea, the smallest legal fishing size of the clam is nearly with the minimal size reproduction, and most them were caught before or just after the first reproduction. It seems important to guarantee the seed source adult population. The importance of filter-feeding bivalves to the purification mechanism of eutrophicated inshore ecosystem was pointed out, and recovery of Manila clam resource from the aspect was expected.
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