Wild Atlantic and Pacific salmon populations face existential threats from habitat degradation, climate change, and disease from farmed salmon, with welfare implications for declining wild populations.
Wild salmon welfare involves both individual animal welfare and population-level welfare concerns. Individual salmon experience significant physiological stress during upstream migration — a journey that typically causes severe physical deterioration and death after spawning. Sea lice infestation from farmed salmon dramatically increases juvenile salmon mortality through a combination of physiological stress and tissue damage during the critical ocean migration phase. Climate-driven river temperature increases cause chronic thermal stress in spawning fish and impair egg development. The population welfare dimension is significant — declining salmon populations mean reduced ecosystem welfare for the many species dependent on salmon as prey or nutrient sources. Dam removal has proven one of the most effective welfare and conservation interventions, restoring both habitat and the migratory capacity on which salmon population welfare depends.