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Studies on the reproduction mechanism in the Japanese eel inferred by DNA analysis and otolith microchemistry.

通过DNA分析和耳石微化学推断日本鳗鱼繁殖机制的研究。

基本信息

批准号：
10460081
负责人：
TSUKAMOTO Katsumi
金额：
$ 8.7万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-10460081/
关键词：
eel glass eel inshore migration reproduction mtDNA otolith daily ring otolith microchemistry metamorphosis ミトコンドリアDNA

项目摘要

1. Analysis of population structure : Population structure analysis through examination of nucleotide sequences (nearly 6O0bp) of the control region in the mitochondrial DNA from a total of 200 glass eels collected in the same year at Taiwan, China, Tanegashima, and Miyagi Prefecture provided no evidence for genetic differentiation among populations. The same was the case for leptocephali samples, which might much reflect genetic characteristics of spawning aggregates. In order to examine genetic structure of glass eels much in detail in the nuclear DNA level, amplified fragment length polymorphism (AFLP) analysis was made for 30 glass eels collected from Miyagi, Kanagawa, and Tanegashima, and also showed no clear geographic differentiation. Altogether, the present DNA analyses of glass eels and leptocephali did not provide any evidence for genetic subdivision of Japanese eel population.2. Analysis of otolith microstructure : Otolith analysis of 150 glass eel collected from five localities in Japan at the beginning, mid and end of fishing season revealed a recruitment mechanism of glass eel : the individuals born earlier in the spawning season tended to recruit earlier to the East Asian estuaries in the lower latitude with the younger age and the larger growth rate than those born later. From EPMA analysis of otolith Sr, about 75% of silver eel collected in the coastal waters of Japan and East China Sea was estimated as sea eel that had never migrated into freshwater, suggesting that reproduction of the Japanese eel might be supported mostly by such sea eel.3. Conclusion : A possible large panmictic population of the Japanese eel suggested a international management of glass eel fishery among four countries in Ease Asia. Furthermore, the importance of estuaries as an eel habitat suggested the protection of the environment of this area and the adult eel to conserve the eel resources.

1. 群体结构分析：对同年在中国台湾、种子岛、宫城县采集的200尾玻璃鳗线粒体DNA控制区核苷酸序列（近600bp）进行群体结构分析，未发现群体间存在遗传分化的证据。细头鲸样本的情况也是如此，这可能在很大程度上反映了产卵聚集体的遗传特征。为了在核DNA水平上更详细地研究玻璃鳗的遗传结构，对宫城、神奈川和种子岛采集的30条玻璃鳗进行了扩增片段长度多态性（AFLP）分析，也没有发现明显的地理分化。总之，目前对玻璃鳗和细头鳗的DNA分析并没有为日本鳗种群的遗传细分提供任何证据。耳石微观结构分析：对日本5个地点采集的150只玻璃鳗在渔期开始、中期和结束时的耳石分析揭示了玻璃鳗的招募机制：产卵季节出生较早的个体比出生较晚的个体更早招募到东亚低纬度河口，年龄更小，生长速度更快。根据耳石Sr的EPMA分析，估计在日本和东海沿海水域采集的银鳗中约有75%是从未迁移到淡水中的海鳗，这表明日本鳗鱼的繁殖可能主要是由这些海鳗支持的。结论：日本鳗鲡可能存在大规模流行种群，建议在东亚四国间对玻璃鳗渔业进行国际管理。此外，河口作为鳗鱼栖息地的重要性建议保护该地区的环境和成年鳗鱼，以保护鳗鱼资源。