Growth and survival in the shirasu larval and juvenile stages

团头鱼、团头鱼的虾幼鱼的特征是身体拉长，黑色素基团发育不良。这些鱼类是主要的鱼类资源，其数量通常波动很大。幼虫和幼虫阶段的生长历史被认为是控制种群波动的主要因素。耳石每日生长年轮现在被用来分析个体鱼的生长历史。在扫描电子显微镜下观察到，在人参天牛体内，环间有宽度小于1微米的细小生长环。黑腹沙丁鱼耳石区有细小的环状结构，在光镜下看不到明显的日轮，因此，耳石的锶/钙比值是一种有效的工具，可以用来重建高山滑舌鱼的迁徙历史，以区分两栖和非两栖种群。然而，在黑腹沙丁鱼中，耳石的sr：ca不随温度或盐度的变化而变化，不能作为生活史分析的工具。基于耳石每日生长年轮的生长史分析表明，从西北太平洋索库附近的沿海到近海，日本龙虾的体细胞增长率呈下降趋势。在黑腹沙丁鱼中，向北迁徙到黑潮-大洋洲过渡水域的种群在生长历史上相对一致，而在迁移到日本中部附近太平洋沿岸水域的种群中发现了不同的生长历史。向北迁移的群体可能会受到黑潮-奥亚西奥过渡水域环境变化的统一影响，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.