Pacific salmon die after spawning as part of their life cycle, but pre-spawn mortality from stress and disease cuts this final phase short, wasting their reproductive effort.
Pre-spawn salmon mortality represents a welfare problem embedded within a natural life cycle. Salmon that complete freshwater migration but die before spawning have expended enormous energy on a journey that serves no reproductive purpose. The individual welfare cost — an animal dying from infections and starvation in warm, oxygen-depleted water rather than completing its evolved function — is real. Watershed temperature management, disease monitoring, and flow protection during critical spawning periods reduce pre-spawn mortality and the associated welfare costs.