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Early life history of Japanese eel inferred by otolith microstructure

通过耳石微结构推断日本鳗鱼的早期生活史

基本信息

批准号：
05454092
负责人：
TSUKAMOTO Katsumi
金额：
$ 2.94万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

项目摘要

To determine the early life history of the Japanese eel, otolith microstructure and microchemistry were investigated. Results obtained are follows :1.Birthdate of the Japanese eel leptocephali sampled near the spawning area (15ﾟN,137ﾟE) in the Philippine Sea 1991 showed a bimodal distribution with 2 weeks interval suggesting that this species spawn periodically.2.Hatch check of artificially obtained larvae was smaller (9mum) in diameter than that of wild specimen (12mum), which suggested that the wild had a longer incubation time than the reared fish (40hrs). The wild also had some embryonic rings (1-6), while the reared had no ring.3.Observation of otolith microelements by ICP method detected Ca, Sr, Zn, Fe, Mg, Mn, Al in sagitae of the eel. Ca content was highest (40%), and Sr was the next (0.1-0.3%) contents of Sr varyed among species corresponding to their migratory pattern ; freshwater fishes was about 0.1%, marine fishes 0.2%, and their intermediate values in diadromous fishes.4.Fluorescent X ray Imaging by syncrotoron showed that the eel otolith generally had a hight concentration of Sr at otolith core. On the other hand, the eels sampled at Danjyo Gunto Is. in the East China Sea showed a high Sr concentration at not only central part but also whole area of the otolith. Based on the difference in Sr content this suggested that these specimens of ambient water between seawater and freshwater, did not show an ordinary migratory patterns, but remained continuously in the sea water after hatching.

为了确定日本鳗鱼的早期生活史，对其耳石显微结构和显微化学进行了研究。结果表明：1.1991年在菲律宾海域产卵区(15ﾟN，137ﾟE)附近采集的日本鳗的出生年龄呈双峰分布，间隔2周，表明该物种具有周期性产卵。2.人工获取的仔鱼孵化检查直径(9um)小于野生标本(12um)，这表明野生鳗鱼的孵化时间(40h)长于养殖鱼(40h)。3.用电感耦合等离子体发射光谱法对鳗鱼耳石中的微量元素进行观察，检测出鳗鱼矢状肌中的钙、锶、锌、铁、镁、锰、铝等元素。Ca含量最高(40%)，锶次之(0.1%-0.3%)，淡水鱼约为0.1%，海水鱼约为0.2%，水栖鱼居中。4.同步龙荧光X射线成像显示，鳗鱼耳石的耳石核心通常有较高的锶含量。另一方面，在Danjyo Gto is采集的鳗鱼样本。在东中国海区，不仅耳石中部有很高的锶含量，而且整个耳石区域都有较高的锶含量。根据锶含量的差异，这表明这些样品在海水和淡水之间，不表现出普通的迁徙模式，而是在孵化后继续留在海水中。