Felix Eissenhauer, Tommi Linnansaari, Thomas C. Pratt, R. Allen Curry, Philip M. Harrison
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引用次数: 0
Abstract
Young American eels (
Anguilla rostrata
) undergo a remarkable migration from oceanic spawning grounds to continental growth habitats. Impaired river connectivity can prevent facultatively catadromous eels from completing their upstream migration. The effects of barriers on the upstream migration dynamics of this endangered species remain poorly understood. This study evaluated the timing of juvenile eel migration and the spatial distribution and size/age structure of migrating eels within the tidal and hydropower-regulated Wolastoq | Saint John River in Canada. Upstream eel migration in this river is restricted by the Mactaquac Dam and Generating Station, located 150 km upstream of the sea. Approximately 36,000 eels were caught with fyke nets at various locations between the river mouth and the Mactaquac Dam, measured for length, and a subsample (n = 401) was aged via sagittal otolith readings. While glass eels (not fully pigmented juvenile eels) were observed up to 90 km upstream, approximately 20 km beyond the point of saltwater intrusion, eels arriving at the Mactaquac Dam were exclusively fully pigmented, with 80% being continental age 1+ or 2+. The mean length of juvenile eels increased with distance upstream. These results indicate that upstream eel migration in the Wolastoq | Saint John River can take multiple years and involves phases of juvenile residency. Our study provides important insights into juvenile eel migration in large rivers and implications for effective management of passage success at barriers such as hydropower dams.
年轻的美洲鳗鲡（Anguilla rostrata）经历了从海洋产卵地到大陆生长栖息地的惊人迁徙。河流连通性受损可能会阻止间歇地鳗完成其上游迁移。障碍对这种濒危物种上游迁移动态的影响仍然知之甚少。本研究评估了加拿大沃拉斯托克河（Wolastoq | Saint John River）潮汐和水力调节河道内幼鳗洄游的时间、洄游鳗鱼的空间分布和大小/年龄结构。这条河上游的鳗鱼迁徙受到位于海面上游150公里处的麦克塔夸克大坝和发电站的限制。在河口和麦克塔夸克大坝之间的不同地点，用网捕获了大约36,000条鳗鱼，测量了长度，并通过矢状耳石读数对子样本（n = 401）进行了年龄测定。在上游90公里处，也就是海水入侵点以外约20公里处，观察到玻璃鳗鱼（未完全着色的幼鳗），而到达Mactaquac大坝的鳗鱼完全是完全着色的，其中80%是大陆年龄1+或2+。幼鳗平均体长随上游距离的增加而增加。这些结果表明，鳗鱼在圣约翰河的上游迁徙可能需要数年时间，包括幼鳗居住的阶段。我们的研究为研究大型河流中幼鳗的迁徙提供了重要的见解，并对有效管理水电大坝等障碍的通行成功具有重要意义。
期刊介绍：
Ecology of Freshwater Fish publishes original contributions on all aspects of fish ecology in freshwater environments, including lakes, reservoirs, rivers, and streams. Manuscripts involving ecologically-oriented studies of behavior, conservation, development, genetics, life history, physiology, and host-parasite interactions are welcomed. Studies involving population ecology and community ecology are also of interest, as are evolutionary approaches including studies of population biology, evolutionary ecology, behavioral ecology, and historical ecology. Papers addressing the life stages of anadromous and catadromous species in estuaries and inshore coastal zones are considered if they contribute to the general understanding of freshwater fish ecology. Theoretical and modeling studies are suitable if they generate testable hypotheses, as are those with implications for fisheries. Manuscripts presenting analyses of published data are considered if they produce novel conclusions or syntheses. The journal publishes articles, fresh perspectives, and reviews and, occasionally, the proceedings of conferences and symposia.
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