Atlantic salmon (Salmo salar) smolt migration through standing waters is generally known to be associated with slow migration speed and low success. Most previous studies have however been conducted on impounded waters. The bathymetry and specifically the flow dynamics around the outlets differ markedly between impounded lakes and naturally draining lakes. To date no study has attempted to disentangle the effects of the impoundment from that of standing water itself. This question was tested in a single naturally draining standing water and two impounded standing waters within a single catchment using fish tagged with acoustic and PIT tags (in three and two lakes, respectively). Overall migration success (river to estuary) was very low (10%); migration success through the lakes was also very low (total loss rates range: 31 to 55%; 16 to 53%.km⁻¹) compared with migration in the river downstream of the lakes (range: 3.9 to 10.8%.km⁻¹). Migration success was no lower in impounded lakes compared with the naturally draining lake. 49% of directional movements were in a direction opposite to the migration pathway, indicating that a lack of navigational cues may be in-part responsible for low migration success. We tentatively conclude that successful migration through standing waters without strong directional cues may be more stochastic than previously thought. We suggest that at least for some impoundments (as shown here), the impoundment per se may not reduce migration success, its greater effect being the creation of the standing water through which smolts are required to migrate. However, any impoundment effect is likely to be dependent upon a combination of lake basin shape, the exit route from the lake and the navigational cues available to smolts.

大西洋鲑（Salmo salar众所周知，通过静水迁移的小软体动物与缓慢的迁移速度和较低的成功率有关。但是，以前的大多数研究都是在蓄水区进行的。在蓄积的湖泊和自然排水的湖泊之间，测深法，尤其是出口周围的水流动力学明显不同。迄今为止，还没有研究试图将蓄水池的影响与死水本身的影响区分开。这个问题是在单个流域内的一个自然排水的静水和两个蓄水的静水中进行测试的，该鱼使用标有声学标签和PIT标签的鱼（分别在三个和两个湖泊中）。总体迁移成功率（从河口到河口）非常低（10％）；通过湖泊的迁移成功率也非常低（总损失率范围：31％至55％； 16％至53％.km ^-1）与湖泊下游河流中的迁移相比（范围：3.9至10.8％.km ^-1）。与自然排水的湖泊相比，蓄水湖泊的迁移成功率并不低。49％的方向性运动是与迁移路径相反的方向，这表明缺乏导航提示可能是造成迁移成功率低的部分原因。我们初步得出结论，在没有强烈方向性提示的情况下，通过死水成功地迁移可能比以前认为的更为随机。我们建议至少对于某些蓄水池（如此处所示），蓄水池本身可能不会降低迁移成功率，其更大的效果是产生了需要移栖的through水的死水。但是，任何蓄水效果都可能取决于湖盆形状，从湖中出来的路线以及可用于鲑鱼的航行线索的综合。