Structures for guiding fish around migration barriers are frequently used for maintaining connectivity in regulated riverine systems. However, for non-physical barriers, experimental studies providing direct and detailed observations of fish–barrier interactions in rivers are largely lacking. In this study, we quantify the efficiency of bubble barriers (alone or in combination with light stimuli, and in both daylight and darkness) for diverting downstream migrating Atlantic salmon (Salmo salar). Both a laboratory-based migration experiment and a large-scale field experiment in a regulated river were used to evaluate efficiency of bubble barriers. In the latter, we used acoustic telemetry to provide in situ measurements of how downstream migrating Atlantic salmon smolts interact with bubble barriers. We show that bubbles divert smolts with high efficiency in both a laboratory flume (95%) and in natural settings (90%). This latter efficiency is higher compared to an already present physical barrier (46%) covering the upper two meters of the water column in the large river. The bubble barrier did not affect flume migration in darkness, suggesting that visual cues are crucial for the observed repelling effect of bubbles. We conclude that bubble barriers can be effective, largely maintenance free and low-cost alternatives to physical structures currently used to divert salmon away from high-mortality passages.

用来引导鱼类绕过迁移壁垒的结构经常用于维持受管制河流系统的连通性。但是，对于非物理性屏障，很大程度上缺乏对河流中鱼类与屏障相互作用的直接和详细观察的实验研究。在这项研究中，我们量化了气泡屏障（单独或与光刺激结合，以及在日光和黑暗条件下）用于转移下游迁移大西洋鲑鱼（Salmo salar）的效率）。基于实验室的迁移实验和在调节河中的大规模野外实验均用于评估泡沫屏障的效率。在后者中，我们使用声学遥测技术来提供原位测量，以了解下游迁移的大西洋鲑鱼鲑鱼如何与气泡屏障相互作用。我们显示，在实验室水槽（95％）和自然环境（90％）中，气泡均能有效地转移香气。与覆盖大河水柱上部两米的物理屏障（46％）相比，后者的效率更高。气泡屏障不会影响黑暗中的水槽迁移，这表明视觉提示对于观察到的气泡排斥效果至关重要。我们得出结论，泡沫壁垒是有效的，