Hydrodynamics in dam tailraces can influence the swimming behavior and survival of fish, and yet there have been few studies that have linked the movement patterns of fish to encountered flow patterns. In this study, we examined the flow field downstream of Seton Dam in British Columbia, Canada using acoustic Doppler current profilers (ADCPs), and computational fluid dynamic (CFD) modeling of two dam water release scenarios to understand their impacts on the swim speed and behavior of upriver-migrating adult sockeye salmon (Oncorhynchus nerka). Forty-five sockeye salmon were tagged with acoustic transmitters and tracked to understand their movement patterns, swim speed, residence time in the dam tailrace, and postdam passage survival. The water release scenarios produced contrasting tailrace hydrodynamics and altered the behavior of migrating sockeye salmon. Tagged fish avoided areas of high velocity (>2.4 m/s or four body lengths/s, twice their critical swim speed), high Reynolds shear stress (>21 Pa), and high turbulence kinetic energy (>0.12 m² s⁻²) in the dam tailrace. Excessive use of anaerobic metabolism, together with high water shear stress adjacent to and downstream of the fishway entrance, were thought to be the main cause for low postdam passage survival of sockeye salmon. Additional dam water release strategies were assessed with the CFD model to target releases that improve the migration conditions for sockeye salmon. Our study highlights the importance of pairing hydraulic and ecological information to better understand and improve the migration conditions for wild fish.

中文翻译：

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使用计算流体动力学模型和生物遥测技术评估大坝放水策略以迁移成年鲑鱼

大坝尾水道中的流体动力学会影响鱼类的游泳行为和生存，但很少有研究将鱼类的运动模式与遇到的流动模式联系起来。在这项研究中，我们使用声学多普勒电流剖面仪 (ADCP) 和计算流体动力学 (CFD) 对两个大坝泄水场景进行了建模，研究了加拿大不列颠哥伦比亚省 Seton 大坝下游的流场，以了解它们对游泳速度和上游迁徙的成年红鲑（Oncorhynchus nerka）的行为）。45 条红鲑鱼被贴上了声波发射器的标签，并被追踪以了解它们的运动模式、游泳速度、在大坝尾流中的停留时间以及坝后通过的存活率。放水情景产生了对比鲜明的尾水动力学，并改变了迁徙红鲑鱼的行为。标记鱼避开高速区域（>2.4 m/s 或四个体长/s，两倍于临界游泳速度）、高雷诺剪切应力 (>21 Pa) 和高湍流动能 (>0.12 m ²  s ^-2) 在大坝尾水道。过度使用厌氧代谢，加上鱼道入口附近和下游的高水剪切应力，被认为是红鲑鱼在坝后通过存活率低的主要原因。使用 CFD 模型评估了额外的大坝水释放策略，以改善红鲑鱼迁移条件的释放为目标。我们的研究强调了将水力和生态信息配对以更好地了解和改善野生鱼类洄游条件的重要性。