Growth and survival in the shirasu larval and juvenile stages

小鳞鱼、小鳞鱼、小鳞鱼、小鳞鱼的幼鱼体型细长，黑素细胞发育不良。这些鱼类构成了主要的鱼类资源，其种群数量通常波动很大。幼虫期和幼鱼期的生长历史被认为是控制种群波动的主要因素。耳石日生长环现在被用来分析单个鱼的生长历史。在扫描电子显微镜下，在相邻环之间发现了宽度小于1妈的细小生长环。在黑纹沙丁鱼耳石区发现细小的环，光镜下不可见明显的日环。耳石Sr: Ca比值可作为重建双性居群和非双性居群迁移历史的有效工具。然而，在黑纹沙丁鱼中，耳托与Sr: Ca的变化并不与温度或盐度的波动平行，不能作为生活史分析的工具。基于耳石日生长环的生长历史分析表明，西北太平洋东北地区的日本鳗鲡（Engraulis japonicus）的体生长速率从沿海到近海呈下降趋势。在黑纹沙丁鱼中，向北迁移到黑潮-漂潮过渡水域的种群在生长历史上相对一致，而迁移到日本中部太平洋沿岸水域的种群在生长历史上存在差异。向北迁移的队列可能会受到黑潮-沽潮过渡水域可变环境的统一影响，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.