Dams fragment salmon river systems, block migration, cause disorientation and injury at fish ladders, and alter water temperature and flow regimes that salmon require.
Wild salmon passing through dam-fragmented river systems experience a welfare gauntlet — exhausting ladder ascents, disorienting holding pools, altered water chemistry, and elevated predation risk at unnatural bottlenecks. Salmon are physiologically and behaviorally driven to complete their migration, and the frustration of that drive by poorly designed or inadequate fish passage causes significant distress. Dam removal where feasible, and high-quality fish passage where dams must remain, are the most direct welfare interventions available.