Spawning success of Atlantic Salmon Salmo salar is challenged when migratory routes to natal streams are obstructed by hydropower generation stations and reservoirs that lack directional cues, potentially causing migratory delay. This study used 74 acoustic‐tagged adult Atlantic Salmon during their spawning migrations to quantify migratory success, rates, and delay through the Mactaquac Reservoir in the Saint John River, New Brunswick, during three migration seasons in 2014–2016. Tag loss or mortality was considerable, reducing the effective sample size to 34 successfully tracked adults. Of these, 41% experienced fallback over the dam, 12% were unsuccessful in exiting the reservoir, and 47% were successful in exiting the reservoir on the way to the spawning grounds. Migration rates were significantly slower in the reservoir (median ± SE = 9.3 ± 1.9 km/d) than upriver (39.0 ± 4.1 km/d), and the tagged Atlantic Salmon spent 31–53% of their time reversing direction and thus travelled longer distances (73 ± 58 km) than the minimum 37‐km midline route through the reservoir. Traveling the distance of the reservoir at the upriver migration rate could have shortened their journey by a median of 3.8 d. Sensor tags indicated that individual Atlantic Salmon experienced temperatures of 10–20°C (median ± SE = 16.0 ± 0.03°C) and migrated at depths of 5–35 m (23.4 ± 0.1 m) within the reservoir. Given that some of the energy needed for reproductive development and activities was likely appropriated by migratory delay and that a moderate proportion (47%) of adults emigrated from the reservoir, volitional passage may not be a successful management strategy in the studied reservoir. However, a substantially reduced sample size negates conclusive remarks about which management strategy would maximize survival and spawning success, and further study is needed.

中文翻译：

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大型水库的大西洋鲑鱼上游迁移延迟

大西洋鲑鱼Salmo salar的产卵成功当缺少定向指示的水力发电站和水库阻碍了通往新生河的迁徙路线时，将面临挑战。这项研究在2014-2016年的三个迁徙季节中，使用74个带有声音标签的成年大西洋鲑鱼进行产卵迁徙，以量化在新不伦瑞克省圣约翰河Mactaquac水库的迁徙成功率，迁徙率和迁徙延迟。标签丢失或死亡率相当大，有效样本量减少到34位成功跟踪的成年人。其中，有41％的人在大坝上经历过后退，有12％的人未成功退出水库，有47％的人成功地从水库中撤出，直至产卵。储层中的迁移速率（中位±SE = 9.3±1.9 km / d）显着慢于上游（39.0±4.1 km / d），带有标签的大西洋鲑鱼沿时间方向花费了31-53％，因此比通过水库的最小37公里中线路线走了更长的距离（73±58公里）。以上游的迁移率行进到水库的距离本可以使中位时间缩短3.8 d。传感器标签表明，单个大西洋鲑鱼的温度为10–20°C（中值±SE = 16.0±0.03°C），并在水库内迁移至5–35 m（23.4±0.1 m）的深度。考虑到生殖发育和活动所需的某些能量很可能由于迁徙延迟而被挪用，并且有中等比例（47％）的成年人从水库中移出，自愿通行可能不是研究水库中成功的管理策略。然而，