Growth and survival in the shirasu larval and juvenile stages

白鲑仔鱼在鲱科、鳀科、多舌科、多齿科鱼类中以身体细长、黑色素细胞发育不良为特征。这些鱼类是主要的鱼类资源，其数量通常波动很大。幼虫期和稚幼期的生长史被认为是控制种群波动的主要因素。耳石日生长轮现在用于分析个体鱼类的生长历史。在Ammodytes personatus中，在扫描电子显微镜下发现相邻环之间宽度小于1 μ m的细小生长环。黑眶沙甸鱼耳石区存在细小的年轮，但在光镜下观察不到明显的日年轮，因此，耳石Sr：Ca比值可以作为重建香鱼迁徙历史的有效工具，用于区分无转性种群和非无转性种群。黑眶沙丁鱼（Sardinops melanostictus）耳石Sr：Ca的变化与温度或盐度的变化不一致，不能作为生活史分析的工具。根据耳石年轮的生长历史分析，发现在西北太平洋Thhoku地区附近的Engraulis sedimentary生长速率从沿海到近海沃茨呈下降趋势。在黑眶沙丁鱼，向北迁移到黑潮-俄亥俄过渡沃茨的队列的生长历史比较一致，而在迁移到日本中部太平洋沿岸沃茨的队列中发现了可变的生长历史。向北迁移的群体可能会受到黑潮-俄亥俄过渡沃茨中多变环境的一致影响，并遭受招募的巨大波动。

Shirasu larvae in clupeid, engraulid, plecoglossid, ammodytid fishes are characterized by elongated body and poor melanophore development. These fished constitute major fish resources whose population usually fluctuate greatly. Growth history in the larval and juvenile stages is considered to be a major factor controlling population fluctuation. Otolith daily growth rings are now used for analyzing growth history of individual fish. in Ammodytes personatus, fine growth rings less than 1 mum in width between neighboring rings were found under scanning electron microscope. In Sardinops melanostictus, fine rings were found in otolith area where distinct daily rings were not visible under a light microscope.Sr : Ca ratio of otolith were found to be a effective tool for reconstructing migration history in Plecoglossus altivelis to discriminate amphidromous population from non-amphidromous one. In Sardinops melanostictus, however, otoith Sr : Ca did not change in parallel with temperature or salinity fluctuation and cannot be used as a tool of life history analysis.Growth history analyses based on otolith daily growth rings revealed that somatic growth rates in Engraulis japonicus declined from the coastal to offshore waters off the Thhoku region in the northwestern Pacific. In Sardinops melanostictus, the cohorts migrated north to the Kuroshio-Oyashio transition waters were comparatively uniform in growth history, while variable growth histories were found in the cohorts migrated to the Pacific coastal waters off central Japan. The cohorts migrating north may be uniformly affected by variable environments in the Kuroshio-Oyashio transition waters and suffer from great fluctuations in recruitment.