Rising river temperatures driven by climate change are pushing juvenile salmon beyond their thermal tolerance limits, reducing survival and welfare of wild populations.
Thermal stress in juvenile salmon represents welfare suffering occurring at population scale as climate change progresses. Fish experiencing temperatures near their upper thermal limits show behavioral avoidance, immune suppression, and elevated stress hormones. The welfare implications of warming rivers extend beyond individual fish to the long-term viability of populations. Stream restoration, riparian reforestation, and support for cold-water refugia are among the most tractable interventions to reduce this suffering.