Wild Atlantic salmon have declined dramatically across their range, with welfare implications for individual fish and ecological consequences for freshwater and marine ecosystems.
Wild salmon welfare encompasses the full life history of a species that undergoes extraordinary physiological transformation and long-distance migration. Salmon blocked from reaching spawning grounds by barriers experience frustrated migration drive — a behavioral motivation so strong that fish throw themselves repeatedly at impassable obstacles, exhausting themselves and sometimes causing injury. Sea lice infestations on migrating juvenile salmon cause tissue damage, increased osmoregulatory stress, and predation vulnerability. Climate warming increasingly pushes river temperatures above salmon tolerance in southern range areas, causing thermal stress and mortality. Dam removal — one of the most welfare-positive interventions available for salmon — immediately creates access to habitat that removes barriers to natural behavior expression. The recovery of salmon in rivers like the Thames, Clyde, and Rhine demonstrates that these welfare harms are reversible with sustained investment.