Simmons O M, Silva A T, Forseth T, Andreasson P, Müller S, Calles O, Aldvén D
Norwegian Institute for Nature Research, Postbox 5685, 7485 Trondheim, Norway.
Norwegian Institute for Nature Research, Postbox 5685, 7485 Trondheim, Norway.
Sci Total Environ. 2024 Apr 20;922:171304. doi: 10.1016/j.scitotenv.2024.171304. Epub 2024 Feb 27.
Hydropower plants commonly impede the downstream migration of Atlantic salmon (Salmo salar) kelts. Thus, understanding the effects of hydraulic conditions on kelt behaviour and passage performance at dams is crucial for developing effective mitigation measures. In this study, we investigated the influence of hydraulic conditions on kelt passage performance and swimming behaviour at a Norwegian hydropower plant. We combined biological data from 48 kelts collected via acoustic telemetry with hydraulic data modelled using computational fluid dynamics. We assessed kelt passage performance using metrics such as time-to-pass, total number of detections, and total number of detections per day. Additionally, we analysed swimming depths and speeds in relation to the hydraulic conditions created by different dam operating conditions. We found that the dam operation schedule impacted the kelts' ability to find a route past the dam. Though kelts could have passed the dam throughout the study period via a submerged pipe at the dam (which had seemingly sufficient discharge for the kelts to find), 98 % of the kelts instead waited for a spill gate to open partway through the study period. The swimming depth analysis indicated diel variation, with kelts swimming nearer to the water surface during the night. We found that swimming speed increased with increasing kelt body length, particularly under high turbulence kinetic energy and during the day. Furthermore, kelts swam faster as water velocity increased, but slowed down again as turbulence intensity increased. Our findings reveal the effects of hydraulic conditions and dam operations on the migration behaviour of Atlantic salmon kelts. This provides valuable insights for developing strategies to optimise dam operations and improve fish passage performance, including the need to spill enough water to increase passage success and will contribute to sustainable management of Atlantic salmon populations in regulated rivers.
水电站通常会阻碍大西洋鲑（Salmo salar）亲鱼向下游洄游。因此，了解水力条件对亲鱼在大坝处的行为和通过性能的影响，对于制定有效的缓解措施至关重要。在本研究中，我们调查了挪威一家水电站的水力条件对亲鱼通过性能和游泳行为的影响。我们将通过声学遥测收集的48尾亲鱼的生物学数据与使用计算流体动力学建模的水力数据相结合。我们使用诸如通过时间、检测总数和每日检测总数等指标来评估亲鱼的通过性能。此外，我们分析了与不同大坝运行条件所产生的水力条件相关的游泳深度和速度。我们发现，大坝运行时间表影响了亲鱼找到绕过大坝路线的能力。尽管在整个研究期间亲鱼本可以通过大坝处的一根淹没管道（该管道似乎有足够的流量供亲鱼找到）通过大坝，但98%的亲鱼却在研究期间中途等待溢洪道打开。游泳深度分析表明存在昼夜变化，亲鱼在夜间游得更靠近水面。我们发现，游泳速度随着亲鱼体长的增加而增加，特别是在高湍流动能条件下和白天。此外，随着水流速度增加亲鱼游得更快，但随着湍流强度增加又会减慢。我们的研究结果揭示了水力条件和大坝运行对大西洋鲑亲鱼洄游行为的影响。这为制定优化大坝运行和改善鱼类通过性能的策略提供了有价值的见解，包括需要泄放足够的水以提高通过成功率，并将有助于对受管制河流中的大西洋鲑种群进行可持续管理。
