Passage of downstream‐migrating fishes through hydropower dams poses a management issue in rivers throughout the world. As such, regulations have been enacted at many locales to understand and limit fish losses by requiring dam passage survival estimation. However, limiting estimates of survival to the dam and immediate tailrace presents a challenge to researchers. In this study, two alternative release–recapture methods were used to estimate dam passage survival of juvenile salmonids through Lower Granite Dam on the Snake River, Washington, in 2018. One approach, the virtual/paired‐release (ViPRe) model, was extensively used in the Columbia–Snake River basin at federally operated hydroelectric dams during 2010–2014. This existing approach uses three releases of tagged smolts to isolate dam passage survival, defined as survival from the upstream dam face to the tailrace mixing zone 1–2 km downstream of the dam. An alternative approach, the virtual release/dead‐fish correction (ViRDCt) model, uses one live‐release group paired with a release of dead tagged fish at the dam to estimate the same survival parameter. The alternative estimation approaches were tested on two spring out‐migrating stocks, yearling Chinook Salmon Oncorhynchus tshawytscha and steelhead Oncorhynchus mykiss, and on a summer out‐migrating stock of subyearling Chinook Salmon. The alternative estimates for these stocks were all within 1 SE. However, the ViRDCt model produced survival estimates with SEs that were 59% smaller than those of the existing ViPRe model and did so using 42% fewer tagged fish and one less downstream acoustic detection array. Because of the reduced sample size, nearly US$540,000 less in tag costs and 4,000 fewer labor‐hours were required to implement the ViRDCt model compared to the ViPRe model. As such, the ViRDCt model represents a cost‐effective and precise approach to characterizing dam passage survival.

中文翻译：

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寻找一种经济有效的方法来估算大坝过水存活率

下游迁移鱼类通过水电大坝构成了世界河流中的管理问题。因此，已经在许多地方制定了法规，以通过要求大坝通过生存估算来了解和限制鱼类损失。但是，将生存估计数限制在水坝和立即尾水对研究人员提出了挑战。在这项研究中，使用了两种替代的释放捕获方法来估算2018年在华盛顿蛇河通过下花岗岩大坝的幼体鲑鱼的大坝存活率。一种方法是虚拟/成对释放（ViPRe）模型在2010-2014年间，哥伦比亚-蛇河流域在联邦政府运营的水电大坝上使用。这种现有方法使用三种释放的带标签的软体动物来隔离大坝通道的生存，定义为从上游水坝面到下游1-2 km的尾水混合区的生存时间。一种替代方法是虚拟释放/死鱼校正（ViRDCt）模型，该方法使用一个活释放组与在大坝处死去的带标记鱼的释放配对来估计相同的生存参数。在两只春季迁出种群一岁的奇努克鲑鱼上测试了替代估计方法Oncorhynchus tshawytscha和steelhead Oncorhynchus mykiss，以及夏季迁徙的奇努克鲑鱼一岁种群。这些股票的替代估算都在1 SE之内。但是，ViRDCt模型的SE生存估计比现有ViPRe模型的生存估计小59％，因此使用的标签鱼减少了42％，下游声学检测阵列减少了SE。由于样本量的减少，与ViPRe模型相比，实施ViRDCt模型所需的标签成本减少了近540,000美元，并且减少了4,000工时。因此，ViRDCt模型代表了一种经济有效且精确的方法来表征大坝通过的生存时间。