Floodplains provide multiple benefits to both resident and migratory fish species, including juvenile Chinook Salmon Oncorhynchus tshawytscha, but direct comparisons of survival during migration through a floodplain versus riverine routes are scarce. The Yolo Bypass is a broad floodplain of the Sacramento River that floods in about 30% of years in response to large, uncontrolled runoff events. We analyzed data from an acoustic telemetry study conducted in winter 2016 to estimate the proportion of tagged juvenile Chinook Salmon entrained from the Sacramento River into the Yolo Bypass and their spatial distribution within the Yolo Bypass. In addition, we compared survival and travel time of Chinook Salmon that migrated through the Yolo Bypass to those migrating via alternative non‐floodplain migration routes at varying stages of a flood event that activated the Yolo Bypass. We found that entrainment into the Yolo Bypass ranged from 1% to 80% among different release groups, with the highest entrainment coinciding with the peak of the March 2016 flooding event. Survival for Chinook Salmon migrating through the Yolo Bypass was similar to survival of those migrating through main‐stem migration routes. At the relatively high flows necessary to enable flooding of the Yolo Bypass, survival estimates varied little among release groups and migration routes. Furthermore, mean daily survival rates for Chinook Salmon migrating through the flooded Yolo Bypass were comparable to those of fish migrating through the other non‐floodplain routes. Median travel times remained relatively constant during various stages of flooding in the Yolo Bypass. This research should help managers to better understand the potential costs and benefits to floodplain restoration and routing of migrating Chinook Salmon into off‐channel habitat.

中文翻译：

---

与萨克拉曼多-圣华金河三角洲的河道有关的奇努克鲑幼鱼的生存，旅行时间和洪泛区使用

洪泛区为居民鱼类和迁徙鱼类提供了多种好处，包括奇努克鲑鱼Oncorhynchus tshawytscha，但缺乏通过洪泛区和河流路线迁移期间生存率的直接比较。Yolo绕道是萨克拉曼多河的广阔洪泛区，响应大型，不受控制的径流事件，洪水在大约30％的年内泛滥。我们分析了2016年冬季进行的声学遥测研究的数据，以估计从萨克拉曼多河夹带到Yolo旁路中的带标签的奇努克鲑鱼的比例及其在Yolo旁路中的空间分布。此外，我们比较了通过Yolo旁路迁移的奇努克鲑鱼的生存和旅行时间与在激活Yolo旁路的洪水事件的不同阶段通过替代性非洪泛平原迁移途径迁移的鲑鱼的生存和旅行时间。我们发现在不同的发行组中，进入Yolo旁路的比例为1％至80％，最高的夹带量与2016年3月洪水事件的高峰相吻合。通过Yolo旁路迁移的奇努克鲑鱼的生存与通过主茎迁移途径迁移的鲑鱼的生存相似。在使Yolo旁路泛滥所需的相对较高的流量下，生存估计在释放组和迁移路线之间几乎没有变化。此外，通过洪水淹没的Yolo旁路迁移的奇努克鲑鱼的平均日生存率与通过其他非洪泛平原途径迁移的鱼的日均生存率相当。在Yolo绕过洪水的各个阶段，中位旅行时间保持相对恒定。这项研究应帮助管理人员更好地了解洪泛平原的恢复以及将奇努克鲑鱼迁移到河外栖息地的路线的潜在成本和收益。