Cold water refugia in stream systems provide thermal shelter for salmon during increasingly warm summers, and protecting these features is critical for both welfare and conservation.
Cold water refugia represent the thermal welfare safety net for Pacific salmon during increasingly warm summers. Fish aggregated in refugia are cool enough to maintain physiological function but face concentrated predation and disease risk. The welfare significance of refugia extends beyond individual fish survival: fish that successfully navigate summer thermal stress return to spawning condition while fish that cannot access adequate thermal refuge die before spawning. Protecting existing refugia through riparian vegetation management and reducing impervious surface runoff that warms water, while actively restoring refugia through beaver reintroduction and stream channel improvement, directly addresses the thermal welfare needs of wild salmon at landscape scale.