Canadian Rivers Institute, Department of Biology, University of New Brunswick, Fredericton, New Brunswick, Canada.
Department of Civil Engineering, University of New Brunswick, Fredericton, New Brunswick, Canada.
J Fish Biol. 2021 Sep;99(3):856-874. doi: 10.1111/jfb.14768. Epub 2021 Jun 15.
Tracking 47 post-spawned adult Atlantic salmon Salmo salar L. in a hydropower-regulated river through autumn, winter and spring revealed that winter survival was 56% and 75% in two study years, respectively, with higher mortality of males than females (50% vs. 33% and 100% vs. 13%, respectively). Some kelts (n = 7) displayed nondirected movements that were interpreted as a reconditioning period for an average of 9-17 days prior to directed downstream movements indicating the initiation of migration. Survival after the initiation of migration in spring was 83% and 94% to the hydropower dam in the first and second study years, and decreased to 60 and 63%, respectively, after dam passage. There were no further losses in the downriver reach in the second year, with the first year having a cumulative survival estimate of 53% to the river mouth. Kelts approached the dam when the spillway gates were available as a passage option most of the time (64%-75%), but some kelts arrived at the dam or had not yet passed when spillways were closed (n = 6) and the only remaining passage option was restricted to the turbines. However, all but one kelt that must have passed via turbine were successful in reaching the river mouth. Migratory delay presumably due to searching behaviour caused by low water flow was estimated at approximately 6 days as migration rates were significantly slower in the reservoir (median ± s.e. 8.5 ± 2.5 km day ) than up- (29.7 ± 5.0 km day ) or downriver (22.1 ± 3.1 km day ). The proportion of time (median 30%) that kelts spent swimming upstream (searching behaviour) in the reservoir was a significant variable for migration success.
在两个研究年度中，通过对 47 条产卵后成年大西洋鲑（Salmo salar L.）在水力发电调节河流中的追踪，发现冬季的存活率分别为 56%和 75%，雄性的死亡率高于雌性（分别为 50%对 33%和 100%对 13%）。一些幼鱼（n=7）表现出非定向运动，这些运动被解释为在定向向下游运动之前进行的适应期，平均为 9-17 天，这表明迁徙的开始。在春季迁徙开始后的存活率分别为 83%和 94%到达水力发电大坝，在第一个和第二个研究年度分别下降到 60%和 63%，在大坝通过后。在第二年的下游段没有进一步的损失，第一年的累积存活率估计为 53%到达河口。幼鱼在溢洪道闸门可用作为通行选择的大部分时间（64%-75%）接近大坝，但当溢洪道关闭时，一些幼鱼到达大坝或尚未通过（n=6），唯一剩下的通行选择受到限制涡轮机。然而，除了一个必须通过涡轮机的幼鱼外，所有幼鱼都成功到达河口。由于低水流导致的搜索行为造成的迁徙延迟估计约为 6 天，因为在水库中的迁徙速度明显较慢（中位数±标准误差 8.5±2.5km·天）比上游（29.7±5.0km·天）或下游（22.1±3.1km·天）。幼鱼在水库中向上游（搜索行为）游泳的时间比例（中位数 30%）是迁徙成功的一个重要变量。
