Entrainment at hydropower facilities, where fish (volitionally and nonvolitionally) enter hydropower infrastructure such as intake towers, can lead to fish becoming stranded for considerable periods of time rather than being flushed to downstream areas. To reduce fish injury and/or mortality from entrainment stranding events, hydropower operators will salvage stranded fish and release them back into the upstream reservoir. We documented the postrelease movements of salvaged fish to determine their vulnerability to reentrainment at a large hydropower facility. Kokanee Oncorhynchus nerka were collected from the turbine intake towers at the W. A. C. Bennett Dam in northeastern British Columbia, surgically implanted with small acoustic transmitters, and released in the forebay area of the hydropower facility. Fish movements were tracked using an array of hydrophones in the forebay area. While the depths and hydraulics of the forebay resulted in low detection efficiency of the receiver array, detection data for 25 fish revealed that 72% (n = 18) of fish were last detected at hydrophones located >1,000 m from the turbine intakes (considered low risk to restranding or reentrainment), 24% (n = 6) of fish were last detected at hydrophones <500 m to the turbine intakes (considered vulnerable to restranding), and one reentrainment event (n = 1; 4% maximal entrainment rate) was observed. Our results indicate there is a low risk associated with kokanee reentrainment events at this large hydropower facility and that manual salvage appears to be a reasonable approach to mitigate fish loss.

中文翻译：

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从涡轮机进气口基础设施中抢救而来的搁浅的Kokanee处于低度被重新诱捕的风险：水电设施前湾中的遥测研究

在水电设施中，鱼（有意无意地进入水电基础设施，如进水塔）的诱捕可能导致鱼在相当长的一段时间内滞留而不是被冲到下游地区。为了减少夹带搁浅事件对鱼类的伤害和/或死亡率，水电运营商将挽救搁浅的鱼类并将其释放回上游水库。我们记录了打捞鱼的释放后运动，以确定它们在大型水力发电设施中是否容易被重新捕获。Kokanee Oncorhynchus nerka这些气体是从不列颠哥伦比亚省东北部WAC Bennett大坝的涡轮机进气塔收集的，通过外科手术植入小型声发射器，然后释放到水力发电站的前湾区域。在前湾地区使用一系列水听器跟踪鱼的活动。尽管前湾的深度和水力导致接收器阵列的检测效率低下，但对25条鱼的检测数据显示， 最后发现72％（n = 18）条鱼是在距涡轮机进气口> 1,000 m的水听器处被发现的（认为低发生重新安置或重新诱捕的风险）， 最后在涡轮进水口<500 m的水听器处发现24％（n = 6）的鱼（被认为容易遭受重新诱捕），并发生一次重新诱捕事件（n = 1; 观察到最大夹带率为4％。我们的结果表明，在这种大型水力发电设施中，与kokanee夹带事件相关的风险较低，并且人工抢救似乎是减轻鱼类损失的合理方法。