瀬戸内海におけるシャコ幼生の出現と垂直分布

概要

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Though many biological works have been made on Japanese common squilla, there are few studies on the seasonal abundance, the vertical distribution and the diurnal migration of its alima larvae. The present author studied on this subject in the Seto Inland Sea (Fig. 1) by the year round survey with a fish larval net, 71.5cm in diameter, and obtained the follow-ing results. The larvae occurred during the period from June to October, especially abundantly from June to September (Fig. 2). No larvae larger than 2mm in carapace length were seen in June, while most of the larvae caught in October were 6-10mm (Table 2). The seasonal variation in abundance and in size composition of larvae, with due regard to their incubation period, suggest that the spawning season of squilla in this sea extends from the middle of May to the end of August. Alima larvae exhibit a distinct diurnal migration, rising to the sea surface by night (Table 1). Although this nature is recognized in every developmental stage of the pelagic larva, it seems that the nature is stronger in larger larvae. It may be possible that a larger part of the alima population is distributed just above, or on the sea bottom in the daytime.
公益社団法人日本水産学会の論文