| Budget Amount *help |
¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1995: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1994: ¥800,000 (Direct Cost: ¥800,000)
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| Research Abstract |
Monthly larval fish collection using a triangular midwater larval net was operated in Ago Bay (2 stations) and at out of the bay (1 station) during the period from July 1993 to August 1995. A total of 53739 eggs and a total of 18710 fish larvae and juveniles were collected by the net. The former could be classified into 9 orders, 29 families and 43 species (lowest taxon), and the latter 18 orders, 69 families and 178 species. The fish larvae lacking in taxonomical data were described in detail.
Eggs were abundant in both number and number of taxa at out of the bay. During the winter season, eggs were very few in the bay.
Larval fish community was generally more various in summer and autumn, and more numerous in spring and summer. Number of taxa was plentiful at out of the bay. A lot of yolk-sac and preflection larvae were collected, but the flexion and postflexion larvae and juveniles were very few in the bay. This phenomenon suggested that some larvae hatched in the bay may go out during their early life stages.
The larval fish community at out of the bay showed higher diversity than that in the bay. On the other hands, the diversity increased in summer and decreased in winter. The larval fish community in the bay was divided seasonally into summer-autumn phase represented by Callionimidae, Gobiidae gen.sp.6 and Rudarius ercodes, and winter-spring phases represented by Sebastiscus marmoratus. Those at out of the bay being more complicated were also divided into spring-summer phase represented by Engraulis japonicus, summer-autumn phase represented by various perciform larvae, and winter-spring phase represented by S.marmoratus and S.spp.
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