Minimizing the mortality and migration time of juvenile salmon (smolts) that pass through dams is a long-standing objective in the pursuit of salmon recovery in the Columbia River basin. We compiled and analyzed 40 acoustic tag studies of juvenile salmonid that were performed between 2010 and 2018 at seven of the eight hydroelectric projects in the Federal Columbia River Power System. We found that the use of nonturbine routes decreased monotonically moving downstream from the Snake River to the main-stem Columbia River dams and associated mortality differed substantially between the dams in the two rivers. Spillways were the predominant passage route at the main-stem Columbia River dams. In contrast, passage was more common through the surface weirs and juvenile bypass systems at the dams in the Snake River, which generally provided higher survival. The observed stocks exhibited variable passage behaviors and mortalities, and the estimated probability that an individual would pass through all eight dams in the system without using a turbine route was 0.31, 0.47, and 0.60 for subyearling Chinook Salmon Oncorhynchus tshawytscha, yearling Chinook Salmon, and steelhead O. mykiss, respectively. Although subyearling Chinook Salmon were generally more likely to pass through a turbine route, they also experienced less turbine-associated mortality than did the other stocks, especially steelhead. Notably, the proportion of smolts that passed through the spillway relative to the proportion of water through the spillway was lowest at Bonneville Dam, the largest and lowermost dam in the system. Bonneville Dam also stood out as having the highest proportion of smolts passing through turbines, but it was among the locations with the lowest rates of turbine-associated mortality.

中文翻译：

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2010-2018 年通过哥伦比亚和蛇河大坝的小鲑鱼幼鱼的通过和存活

最大限度地减少通过大坝的幼鲑（小鲑鱼）的死亡率和迁徙时间是哥伦比亚河流域鲑鱼恢复的长期目标。我们汇编并分析了 2010 年至 2018 年期间在联邦哥伦比亚河电力系统八个水电项目中的七个项目中对幼年鲑鱼进行的 40 项声学标签研究。我们发现，从蛇河下游到哥伦比亚河主干水坝的非涡轮路线的使用单调减少，并且两条河流中的水坝之间的相关死亡率差异很大。溢洪道是哥伦比亚河主干水坝的主要通道。相比之下，通过蛇河大坝的地表堰和幼年旁路系统更为常见，这通常提供更高的生存率。观察到的种群表现出不同的通过行为和死亡率，一个个体在不使用涡轮机路线的情况下通过系统中所有八个大坝的估计概率为 0.31、0.47 和 0.60。分别是 Oncorhynchus tshawytscha、一岁的奇努克鲑鱼和 Steelhead O. mykiss。尽管低于一岁的奇努克鲑鱼通常更有可能通过涡轮机路线，但与其他种群相比，它们与涡轮机相关的死亡率也更低，尤其是钢头。值得注意的是，相对于通过溢洪道的水的比例，通过溢洪道的小鲑鱼的比例在邦纳维尔大坝是最低的，这是系统中最大和最低的大坝。邦纳维尔大坝也因通过涡轮机的小鲑鱼比例最高而脱颖而出，但它是涡轮机相关死亡率最低的地方之一。