Faulkner et al. (2019) presents data and analyses to support a hypothesis that bypass encounters by juvenile Chinook Salmon and steelhead at hydropower dams are not harmful (e.g., “Our results suggest that after fish leave the hydropower system, bypass passage history has little effect on mortality”), and any difference in life‐cycle survival among bypassed and non‐bypassed fish is largely an artifact of variation in body size, where smaller fish that are inherently less likely to survive are bypassed at rates disproportionately greater than their larger counterparts. Under this hypothesis, it may be reasonably interpreted that poor ocean survival–and consequently depressed rates of adult return–is not due to deleterious outmigration conditions (that can be indexed by bypass histories), but results rather from the size of individuals upon ocean entry. We take issue with their conclusions, finding substantive flaws in the basis for this hypothesis related to both the data and methods of analysis. Faulkner et al. (2019) has been publicized widely throughout the region (e.g., NOAA Fisheries West Coast Region, 25 November 2019), with reference at times pointing to the article as a matter of fact. Yet, little attention has focused on the approach or the data underlying their basic conclusions. Given the relevance of this topic to management objectives, both regionally and, for that matter, wherever impounded rivers exist, we believe it is essential to illustrate where the data and methods have led to erroneous conclusions; we are concerned indiscriminant acceptance of Faulkner et al. (2019) may mislead important decisions surrounding management and conservation.

中文翻译：

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评论：在两种高风险的太平洋鲑鱼中，鱼的长度，水坝通过的历史以及成年后的存活率之间存在关联。

福克纳等。（2019年）提出了数据和分析，以支持以下假设：幼年的奇努克鲑鱼和硬头蛇在水力发电大坝上遇到的旁路无害（例如，“我们的结果表明，鱼离开水电系统后，旁路通过的历史对死亡率几乎没有影响”） ），而绕过的和未绕过的鱼在生命周期中的任何差异在很大程度上都是体型变化的产物，其中本来就不太可能生存的较小的鱼被绕过的比率要比较大的鱼大得多。在这种假设下，可以合理地解释，海洋生存能力差（进而成人成活率下降）不是由于有害的移民条件（可以通过绕行历史来确定），而是来自入海人数的规模。我们对他们的结论持怀疑态度，在与数据和分析方法有关的这一假设的基础上发现了实质性的缺陷。福克纳等。（2019）已在整个地区广泛发布（例如，NOAA渔业西海岸地区，2019年11月25日），有时引用该文章是事实。但是，很少有人关注其基本结论所基于的方法或数据。鉴于本专题与区域和各方面的管理目标的相关性，无论在何处存在蓄水的河流，我们认为至关重要的是说明数据和方法在何处导致错误的结论；我们担心对福克纳等人的不分青红皂白的接受。