We collated smolt‐to‐adult return rate (SAR) data for Chinook salmon from all available regions of the Pacific coast of North America to examine the large‐scale patterns of salmon survival. For consistency, our analyses primarily used coded wire tag‐based (CWT) SAR estimates. Survival collapsed over the past half century by roughly a factor of three to ca. 1% for many regions. Within the Columbia River, the SARs of Snake River populations, often singled out as exemplars of poor survival, are unexceptional and in fact higher than estimates reported from many other regions of the west coast lacking dams. Given the seemingly congruent decline in SARs to similar levels, the notion that contemporary survival is driven primarily by broader oceanic factors rather than local factors should be considered. Ambitious Columbia River rebuilding targets may be unachievable because other regions with nearly pristine freshwater conditions, such as SE Alaska and northern BC, also largely fail to reach these levels. Passive integrated transponder (PIT) tag‐based SAR estimates available for Columbia River Basin populations are generally consistent with CWT findings; however, PIT tag‐based SARs are not adjusted for harvest which compromises their intended use because harvest rates are large and variable. More attention is needed on how SARs should be quantified and how rebuilding targets are defined. We call for a systematic review by funding agencies to assess consistency and comparability of the SAR data generated and to further assess the implications of survival falling to similar levels in most regions of the west coast.

中文翻译：

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西海岸奇努克鲑鱼（Oncorhynchus tshawytscha，Salmonidae）的沿海生存下降的综合报告

我们整理了北美太平洋沿岸所有可用地区的奇努克鲑鱼的成年至成年返还率（SAR）数据，以研究鲑鱼生存的大规模模式。为了保持一致性，我们的分析主要使用基于编码电线标签（CWT）的SAR估算值。在过去的半个世纪中，生存率下降了大约三分之二。许多地区为1％。在哥伦比亚河内，蛇河种群的SAR通常被认为是生存能力较差的典范，它们无与伦比，实际上比西海岸许多其他没有水坝的地区的估计数高。鉴于SAR似乎下降到了相似的水平，应该考虑这样一种观念，即当代生存主要是由更广泛的海洋因素而非地方因素驱动的。雄心勃勃的哥伦比亚河重建目标可能无法实现，因为其他淡水状况接近原始的地区，例如阿拉斯加东南部和卑诗省北部，也基本上没有达到这些水平。可用于哥伦比亚河流域人口的基于被动集成应答器（PIT）标签的SAR估算值通常与CWT的发现相符；但是，基于PIT标签的SAR并未针对收获进行调整，这会损害其预期用途，因为收获率很大且变化很大。需要更多关注如何量化SAR和如何定义重建目标。我们要求资助机构进行系统的审查，以评估生成的SAR数据的一致性和可比性，并进一步评估西海岸大多数地区的生存率下降到相似水平的影响。