Wild Atlantic salmon face a cascade of threats across their complex life cycle, from river pollution and barriers to marine survival decline, with welfare implications for millions of individual fish.
Wild Atlantic salmon experience welfare-relevant suffering at multiple life stages. Migrating adults face exhaustion navigating rivers with reduced flow and elevated temperatures. Fish passage facilities at dams often fail to pass fish efficiently, causing prolonged and repeated attempts against currents. Sea lice infestations cause skin damage, osmotic stress, and weakened immune function. Pollution reduces oxygen availability and harms gill function. Returning adults that cannot reach spawning grounds after crossing the ocean to find them face a particularly frustrating biological drive thwarted by human-made barriers. Population-level collapse also reduces the social facilitation of spawning aggregations that may be behaviourally important for the species.