Wild Atlantic salmon populations have declined dramatically due to habitat degradation, with river restoration programmes aiming to improve conditions and welfare of surviving fish.
Wild Atlantic salmon welfare is affected by the cumulative degradation of the freshwater and marine environments they depend upon. Individual fish welfare during upstream migration is directly compromised by barriers that require repeated leaping attempts, exhausting reserves; by low oxygen levels in warm river stretches; and by overcrowding at bottlenecks in degraded systems. River restoration — removing barriers, restoring riparian vegetation to cool river temperatures, improving gravel beds — addresses welfare and conservation simultaneously. For each individual salmon, a shorter migration through higher-quality habitat means lower physiological stress and higher breeding success.