Community Ecology of Fish Eggs, larvae, and Juveniles in Ago Bay, Mie Prefecture

1993年7月至1995年8月期间，在阿戈湾(2个站)和湾外(1个站)进行了每月使用三角形中水幼网收集幼鱼的工作。共收集鱼卵53739枚，鱼苗18710尾。前者为9目29科43种(最低分类单元)，后者为18目69科178种。对缺乏分类学资料的鱼苗进行了详细的描述。在湾外，虫卵数量和数量都很丰富。冬季湾内鱼卵稀少，幼鱼群落一般在夏、秋两季较多，春、夏较多。海湾外有大量的分类群。湾内采集了大量的卵黄囊和前屈幼虫，但屈曲和后屈的仔鱼和仔鱼很少。这一现象表明，一些在湾内孵化的仔鱼可能在其早期生活阶段就离开了海湾，湾外的仔鱼群落表现出比湾内更高的多样性。另一方面，物种多样性夏季增加，冬季减少。按季节划分，湾仔鱼群落分为夏秋季阶段和冬春季阶段，夏秋季阶段以Callionimidae、Gobiidae gen.sp.sp.6和Rudarius ercodes为代表。较复杂的外湾还可划分为以日本鳗为代表的春夏期、以各种贻贝幼虫为代表的夏秋季、以海鞘和沙门氏菌为代表的冬春相。

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.