Department of Fish and Wildlife Sciences, College of Natural Resources, University of Idaho, Moscow, Idaho, United States of America.
PLoS One. 2021 Sep 2;16(9):e0256805. doi: 10.1371/journal.pone.0256805. eCollection 2021.
Fishways have been widely used for upstream passage around human-built structures, but 'success' has varied dramatically. Evaluation of fishway success has typically been conducted at local scales using metrics such as fish passage efficiency and passage time, but evaluations are increasingly used in broader assessments of whether passage facilities meet population-specific conservation and management objectives. Over 15 years, we monitored passage effectiveness at eight dams on the Columbia and Snake rivers for 26,886 radio-tagged spring-summer and fall Chinook Salmon O. tshwaytscha, Sockeye Salmon O. nerka, and summer steelhead O. mykiss during their migrations to spawning sites. Almost all fish that entered dam tailraces eventually approached and entered fishways. Tailrace-to-forebay passage efficiency estimates at individual dams were consistently high, averaging 0.966 (SD = 0.035) across 245 run×year×dam combinations. These estimates are among the highest recorded for any migratory species, which we attribute to the scale of evaluation, salmonid life history traits (e.g., philopatry), and a sustained adaptive management approach to fishway design, maintenance, and improvement. Full-dam fish passage times were considerably more variable, with run×year×dam medians ranging from 5-65 h. Evaluation at larger scales provided evidence that fishways were biologically effective, e.g., we observed rapid migration rates (medians = 28-40 km/d) through river reaches with multiple dams and estimated fisheries-adjusted upstream migration survival of 67-69%. However, there were substantive uncertainties regarding effectiveness. Uncertainty about natal origins confounded estimation of population-specific survival and interpretation of apparent dam passage 'failure', while lack of post-migration reproductive data precluded analyses of delayed or cumulative effects of passing the impounded system on fish fitness. Although the technical fishways are effective for salmonids in the Columbia-Snake River system, other co-migrating species have lower passage rates, highlighting the need for species-specific design and evaluation wherever passage facilities impact fish management and conservation goals.
鱼道被广泛用于人类建筑物上游的洄游通道，但“成功”的情况差异很大。鱼道成功的评估通常在局部尺度上进行，使用鱼类通过效率和通过时间等指标，但评估越来越多地用于更广泛地评估通道设施是否符合特定种群的保护和管理目标。在过去的 15 年中，我们在哥伦比亚河和蛇河流域的 8 座大坝上监测了 26886 条标记有无线电的春季-夏季和秋季奇努克鲑鱼 O. tshwaytscha、红大麻哈鱼 O. nerka 和夏季钢头鱼 O. mykiss 的洄游通道有效性，这些鱼类在洄游到产卵地的过程中通过大坝尾水渠。几乎所有进入大坝尾水渠的鱼类最终都接近并进入了鱼道。个别大坝的尾水渠-前池通过效率估计值一直很高，在 245 个运行年大坝组合中平均为 0.966（SD=0.035）。这些估计值是任何洄游物种中记录最高的，我们将其归因于评估规模、鲑鱼生活史特征（如恋地性）以及对鱼道设计、维护和改进的持续适应性管理方法。大坝全通道的鱼类通过时间则变化较大，运行年大坝中位数范围为 5-65 小时。在较大规模上的评估提供了证据表明鱼道具有生物有效性，例如，我们观察到通过有多个大坝的河段的快速迁移率（中位数=28-40 公里/天），并估计了渔业调整后的上游迁移存活率为 67-69%。然而，有效性方面存在实质性的不确定性。关于出生地的不确定性混淆了特定种群的生存估计和对明显的大坝通过“失败”的解释，而缺乏迁移后繁殖数据则妨碍了对通过蓄水系统对鱼类适应性的延迟或累积影响的分析。尽管技术鱼道对哥伦比亚-蛇河流域的鲑鱼是有效的，但其他共同洄游的物种通过的比例较低，这突出表明，只要通道设施影响鱼类管理和保护目标，就需要进行特定物种的设计和评估。
