Sockeye salmon that spawn downstream of rearing lakes are an important example of the challenges faced by organisms with complex life histories requiring connectivity in aquatic habitat complexes. Specifically, newly emerged juvenile sockeye salmon must migrate upstream, against the flow of water, if they are to reach lake rearing habitat. Here, we examine the spatial and temporal dynamics of the water velocity landscape and juvenile sockeye salmon movement and condition at increasing distances downstream from the lake outlet of an important sockeye salmon system, the Babine Lake of British Columbia, one of Canada’s largest and most important sockeye salmon rearing lakes. The results of this study indicate that (i) there were seasonal and spatial patterns of water velocities that exceed the ability of juveniles to swim upstream to lake rearing habitat, (ii) higher water discharge was associated with more velocity barriers and potentially with less upstream movement of juveniles, and (iii) juveniles rearing in the lake obtained larger sizes (30% longer and 150% heavier) than those in downstream river habitats. Multiple processes that may be influencing these patterns could include more abundant food resources, lower metabolic demands, or size-selective immigration, emigration, or mortality among habitats. Years and seasons with high discharge may temporarily create one-way, downstream transport routes at lake outlets. Long-term changes in hydrology, perhaps driven by climate variability or land-use change, may control the degree to which lake outlets function as bidirectional travel corridors or one-way travel routes for young sockeye salmon.

在饲养湖泊下游产卵的红鲑鱼是具有复杂生活史的生物所面临挑战的重要例子，这些生物需要在水生生境复合体中建立连通性。具体而言，新近出现的红鲑鲑必须到达上游，才能逆流而上，如果它们要到达湖泊养育的栖息地。在这里，我们研究了水速景观和幼体鲑鲑运动和状况的时空变化，该距离是从鲑鱼重要鲑鱼系统的湖出口下游不远处增加的距离，英属哥伦比亚的巴宾湖是加拿大最大，最重要的鲑鱼之一大马哈鱼饲养湖泊。这项研究的结果表明：（i）水速度的季节性和空间格局超过了幼体向上游游至湖泊养育栖息地的能力；（ii）较高的排水量与更多的速度障碍相关，而潜在的与更少的上游相关（iii）在湖中饲养的幼鱼比下游河流栖息地的幼鱼更大（长30％，重150％）。可能影响这些模式的多个过程可能包括更丰富的食物资源，更低的新陈代谢需求或生境之间大小选择性的迁徙，迁徙或死亡。排放量高的年份和季节可能会暂时在湖泊出口处形成单向下游运输路线。水文学的长期变化，可能是由于气候多变性或土地利用变化所致，