Canadian Journal of Fisheries and Aquatic Sciences, Ahead of Print.
American eel (Anguilla rostrata) often pass hydropower dams during adult spawning migrations. We conducted a 4-year acoustic telemetry study that characterized passage risks through two dams (West Enfield and Milford) in the Penobscot River, Maine, USA. We released tagged fish (n = 355) at two sites, estimated survival and delay under variable river conditions, and compared performance among dammed and free-flowing river sections. Survival rates (standardized per river kilometre, rkm) were lower at West Enfield (Φrkm = 0.984 ± 0.006 SE) and Milford (Φrkm = 0.966 ± 0.007 SE) compared with undammed River sections (Φrkm = 0.998 ± 0.0003 SE). Cumulative mortality was 8.7% (4.4 km) and 14.2% (5.5 km) through dammed sections and 8.7% throughout the rest of the river (58.1 km). Fish that already passed an upstream dam incurred higher downstream mortality compared with individuals without passage experience. Additionally, fish endured long delays at dams, and >10% of fish were delayed >24 h. Low flows exacerbated the risk of mortality and delay. These results offer evidence for direct, latent, and sublethal consequences of dam passage for migrating eels.

中文翻译：

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缅因州佩诺布斯科特河下游美洲鳗鱼通过大坝的后果

加拿大渔业和水产科学杂志，提前印刷。
美洲鳗（Anguilla rostrata）在成年产卵迁徙期间经常经过水电站大坝。我们进行了一项为期 4 年的声学遥测研究，该研究描述了通过美国缅因州佩诺布斯科特河的两个大坝（西恩菲尔德和米尔福德）的通行风险。我们在两个地点释放了带标签的鱼 (n = 355)，估计了不同河流条件下的存活率和延迟，并比较了有坝和自由流动的河段的性能。与未筑坝的河段 (Φrkm = 0.998 ± 0.0003 SE) 相比，西恩菲尔德 (Φrkm = 0.984 ± 0.006 SE) 和米尔福德 (Φrkm = 0.966 ± 0.007 SE) 的存活率（每河流公里标准化，rkm）较低。堤坝段的累积死亡率为 8.7%（4.4 公里）和 14.2%（5.5 公里），河流其余部分（58.1 公里）的累积死亡率为 8.7%。与没有通过经验的个体相比，已经通过上游大坝的鱼在下游死亡率更高。此外，鱼在大坝忍受了长时间的延误，> 10% 的鱼被延误 > 24 小时。低流量加剧了死亡和延误的风险。这些结果为迁徙鳗鱼通过大坝的直接、潜在和亚致死后果提供了证据。