Wild salmon undergo extraordinary physiological changes during spawning runs. Human activities that impede migration or degrade spawning habitat cause welfare harm at population scale.
Wild salmon face extraordinary physiological demands during their spawning runs: fasting, fighting currents, navigating obstacles, and undergoing dramatic body changes as their metabolism shifts from marine to freshwater mode. Human obstacles including dams, warm water from climate change, and degraded spawning habitat add additional physiological burdens. These are welfare impacts at scale: tens of thousands of individual fish experiencing heat stress, exhaustion, and injury that preventable human impacts cause. River restoration and dam removal provide the most impactful welfare and conservation interventions.