カキ種苗生産場における生態学的研究-I : 仙台湾における母貝群の性状
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概要
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Sendai Bay of northern Japan is one of the well-known sources of seed oysters for supplies to both foreign as well as domestic markets. Production of seed oysters are dependent upon meteorological, hydrographical and topographical features of the fishing grounds on the one hand and, on the other, upon ecological characteristics of the oyster population, such as the breeding of mother oysters and dispersal or accumulation of their larvae. In this paper, the authors report the role played by mother oyster populations in the production on seed oysters in this area. Cultured oysters were sampled at Kobuchi in Ojika Peninsula, Mangoku-ura in Ishinomaki Bay and Tona in Matsushima Bay, all within the larger Sendai Bay area. Growth, sexual maturity and breeding season of the oysters and the amount of spawned eggs were determined both morphologically and histologically. The oysters from the relatively oligotrophic waters of Mangoku-ura in Ishinomaki Bay and those from Kobuchi in Ojika Peninsula, where the effects of oceanic conditions are apparent, were characterized by smaller growth rates and lesser amounts of spawned eggs than the oysters from the more eutrophic Matsushima Bay. The Matsushima Bay group, together with the Mangoku-ura oysters, also showed an earlier incidence of spawning. Results of a survey on oyster larvae which was carried out in Sendai Bay during the period 1965-1968 strongly suggest that the Matsushima Bay population of mother oysters contribute to the larger part of the production of eggs and, through the larval stages, setting of oyster spats in Sendai Bay. Based on these results, the authors have discussed the possibility of improving seed collecting techniques, including the prediction of periods and areas of oyster spat setting in this Bay.
- 公益社団法人 日本水産学会の論文