Wild Atlantic salmon and sea trout face welfare challenges including passage barriers, warming water temperatures, predation pressure, and parasite loads that interact to affect individual fish condition and survival.
Wild salmon welfare is affected by multiple stressors simultaneously, making attribution of welfare harm to specific causes difficult. Thermal stress from warming rivers compromises immune function and increases susceptibility to disease. Passage barriers prevent spawning migrations that wild salmon are biologically driven to complete, holding them in thermal and predation stress below barriers. Sea lice from nearby salmon farms impose a disproportionate welfare burden on juvenile wild salmon during their vulnerable smolt migration. River restoration, barrier removal, and aquaculture management reforms simultaneously improve conservation outcomes and individual fish welfare.