The management of Snake River spring/summer Chinook Salmon and Snake River steelhead is a major concern for several federal, state, and tribal agencies. A primary issue is the effect of the Federal Columbia River Power System (FCRPS), composed of eight dams and reservoirs in the Snake and Columbia rivers, on adult return rate. Management decisions have been influenced by the hypothesis that the passage route that juveniles take through dams (i.e., through spillway, turbines, or juvenile bypass system) strongly influences adult return rate. The main hypothesized mechanism for differential survival rates is differences in latent mortality – mortality suffered due to passage through the FCRPS that is expressed outside of the FCRPS. Because this latent mortality is not directly measurable, it must be indirectly inferred. Two patterns have been observed in, or inferred from data analyses in the past, and have become generally accepted during decades of debate: (1) smaller fish are more likely than larger fish to pass dams on the Snake and Columbia Rivers via the juvenile bypass system passage route, and (2) among fish that complete migration through the entire hydropower system, those that passed more dams via juvenile bypass systems return as adults at lower rates. This has led to increased spill to prevent juveniles passing through bypass systems and turbines with a hypothesized decrease in latent mortality. The most important question to address is whether lower survival is caused by increased numbers of bypass‐system encounters, or whether that pattern results because both increased encounters and decreased survival might be explained by another causative factor.

中文翻译：

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太平洋鲑鱼两种危险物种的鱼长，大坝通过史和成年存活率之间的关联：对评论的回应

Snake River春夏奇努克鲑鱼和Snake River硬头鱼的管理是几个联邦，州和部落机构的主要关注点。一个主要问题是由蛇河和哥伦比亚河中的八个水坝和水库组成的联邦哥伦比亚河电力系统（FCRPS）对成年返回率的影响。管理决策受到以下假设的影响：未成年人通过水坝（即通过溢洪道，涡轮机或未成年人旁路系统）的通过路线会严重影响成年返回率。假设的差异生存率的主要机制是潜在死亡率之间的差异-潜在的死亡率是由于通过FCRPS以外的表达而遭受的死亡率。由于该潜在死亡率无法直接测量，因此必须间接推断。过去在数据分析中观察到两种模式，或从中进行推断，并且在数十年的辩论中已被普遍接受：（1）小鱼比大鱼更有可能通过少年绕道在蛇河和哥伦比亚河上通过水坝（2）在整个水电系统中完成迁移的鱼类中，通过幼年旁路系统通过更多水坝的鱼类以较低的成年率返回。这导致溢漏增加，以防止未成年人通过潜在的死亡率降低而绕过旁路系统和涡轮机。要解决的最重要问题是，是否降低生存率？（1）较小的鱼类比较大的鱼类更有可能通过少年旁路系统通过路线在蛇河和哥伦比亚河上通过水坝；（2）在整个水电系统中完成迁移的鱼类中，通过幼年通过更多水坝的鱼类旁路系统以较低的成人价格返回。这导致溢漏增加，以防止未成年人通过潜在的死亡率降低而绕过旁路系统和涡轮机。要解决的最重要问题是，是否降低生存率？（1）较小的鱼类比较大的鱼类更有可能通过少年旁路系统通过路线在蛇河和哥伦比亚河上通过水坝；（2）在整个水电系统中完成迁移的鱼类中，通过幼年通过更多水坝的鱼类旁路系统以较低的成人价格返回。这导致溢漏增加，以防止未成年人通过潜在的死亡率降低而绕过旁路系统和涡轮机。要解决的最重要问题是，是否降低生存率？这导致溢漏增加，以防止未成年人通过潜在的死亡率降低而绕过旁路系统和涡轮机。要解决的最重要问题是，是否降低生存率？这导致溢漏增加，以防止未成年人通过潜在的死亡率降低而绕过旁路系统和涡轮机。要解决的最重要问题是，是否降低生存率？ 是 由旁路系统遭遇次数增加引起的，还是该模式是否由于遭遇次数增加而生存率降低而导致，可能由另一个原因引起。