Studies on fish migration history using otolith stable isotope ratios

利用耳石稳定同位素比值（^<87> Sr/^<86 >sr,δ^<13 >o）研究了阿育鱼（Plecoglossus altivelis）、琵琶鳟鱼（Oncorhynchus masou rhodurus）、日本鳗鲡（Anguilla japonica）的洄游史，包括产卵区。耳石Sr ^<87> / Sr ^<86>分析表明阿玉幼鱼没有向孵出的河流迁移。分析还确定琵琶鳟鱼返回孵化后的河流产卵，但返回的迁徙模糊，进入孵化后的河流附近。在马里亚纳海沟以西产卵区收集的成年鳗鱼的耳石^<87> Sr/^<86> Sr，显示日本太平洋沿岸部分成年鳗鱼的生长区域为河流或河口，表明日本鳗鱼对该物种的繁殖有贡献。玻璃鳗耳石中部的δ^<13> O测定了日本鳗鲡的产卵温度为26℃，产卵深度为150 ~ 170 m，为2009年和2011年白湖丸科考船在日本鳗鲡产卵区采集鳗鱼卵提供了重要信息。

Migration history including spawning area of Ayu(Plecoglossus altivelis), Biwa trout(Oncorhynchus masou rhodurus), Japanese eel(Anguilla japonica) was studied using otolith stable isotope ratios(^<87> Sr/^<86> Sr,δ^<13> O). Otolith^<87> Sr/^<86> Sr analysis showed that ayu juvenile did not migrate to the hatched river. The analysis also determined that Biwa trout returned to hatched river and spawned, but the returning migration being vague with entering into neighboring rivers of hatched one. Otolith^<87> Sr/^<86> Sr of spawning adult eels collected in the spawning area west of Mariana Trench revealed the growth area of some adult eels to be rivers or estuaries in the Pacific coast of Japan, suggesting that eels in Japan contribute to the reproduction of the species.δ^<13> O of the central portion of glass eel otoliths determined the spawning temperature and depth of the Japanese eel to be 26℃and 150-170 m deep, respectively, which provided important information for collecting eel eggs in spawning area of the Japanese eel in 2009 and 2011 by Hakuho-Maru research cruises.