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）使用三角形中层幼虫网每月采集幼鱼。渔护署人员共检获鱼卵53739枚及仔稚鱼18710尾。前者隶属于9目29科43种（最低分类单元），后者隶属于18目69科178种。详细描述了缺乏分类学资料的仔稚鱼，湾外产卵量丰富，种类繁多。在冬季，湾内鱼卵很少，仔稚鱼群落一般在夏秋两季多样性较高，春、夏两季数量较多。在海湾外有大量的分类群。在该湾采集到大量的卵黄囊期和前屈期仔鱼，而前屈期和后屈期仔鱼和稚贝很少。这一现象表明，在湾内孵化出的仔鱼在早期生活阶段可能会外出，湾外仔鱼群落的多样性高于湾内。夏季多样性增加，冬季多样性减少。该湾仔稚鱼群落在季节上可分为夏秋和冬春两个阶段，夏秋阶段以丽鱼科（Callionimidae）、虾虎鱼科（Gobiidae gen.sp.6）和Rudarius ercodes为代表，冬春季阶段以褐鲷为代表。湾外的种类也较复杂，可分为以鳀为代表的春夏相、以各种鲈形目幼虫为代表的夏秋相和以花斑海鲶和花斑海鲶为代表的冬春相。

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.