Environmental change and sockeye salmon life histories across space and time

Animals with complex life cycles migrate to exploit resources from different environments, but are exposed to multiple stressors and challenges. Here I investigated stressors across ontogenetic shifts in sockeye salmon. First, I examined migration and condition of juvenile sockeye salmon fry as they migrate from the Babine River, British Columbia, to upstream lake rearing habitat. High water velocities increased challenges to successful upstream migration to the lake, but lake rearing habitat was associated with larger fry (30% longer, 150% heavier). Second, I examined how multiple ocean stressors impact freshwater fecundity using a nearly 7-decade dataset from Fraser and Skeena sockeye salmon. Good ocean conditions and low biomass of salmon competitors were associated with younger, larger, more fecund sockeye. Spawning channel enhancement was associated with a small additional increase in fecundity. Collectively, my thesis highlights intricacies in the effects of multiple stressors on sockeye salmon across their complex life cycle.