Amoebic gill disease (AGD) is a major welfare and production challenge in salmon farming. Caused by a parasitic amoeba, it causes respiratory distress and requires treatment that itself causes significant stress.
AGD creates a cycle of welfare harm in salmon farming. The disease itself causes respiratory distress as gill function is impaired — fish experience the equivalent of breathing through congested airways. Treatment with freshwater or hydrogen peroxide baths requires handling and crowding that causes additional acute stress. The mechanical de-licing devices increasingly used to treat sea lice — a related challenge — can cause physical injury when fish are already weakened by AGD. Rising sea temperatures extending the AGD season mean affected farms face repeated treatment cycles causing cumulative welfare harm. Closed containment technology that prevents exposure to the marine amoeba is the only complete welfare solution.