Atlantic salmon welfare during winter in cold water sea cages has specific characteristics as metabolism slows and management challenges change.
Atlantic salmon winter welfare is characterised by metabolic slowing that reduces growth, feeding, and immune activity. This creates both challenges and benefits. The welfare benefit of reduced sea lice activity in winter allows a respite from treatment stress. The welfare challenge is managing fish in cold water where any additional stressor has more impact on reduced physiological reserves. Over-feeding in cold water causes digestive welfare problems. Handling during winter should be minimised as stress responses are more severe relative to physiological capacity. Welfare monitoring adapted to winter conditions provides appropriate assessment for this distinct seasonal state.