Salmon slaughter welfare is a growing area of aquaculture concern. The method used to render fish insensible before killing significantly affects the welfare experience at harvest.
Salmon slaughter welfare has received increasing scientific and regulatory attention as fish sentience evidence has strengthened. The most common commercial method historically - crowding, then CO2 water exposure to slow fish, then bleeding - involves a prolonged period of aversive experience before death. CO2 exposure causes avoidance behaviour and gill irritation before inducing insensibility, indicating genuine distress. The welfare-superior methods - percussive or electrical stunning before bleeding - provide rapid insensibility, but both require careful calibration to fish size and consistent application at commercial throughputs. The transition from CO2 to stunning-based slaughter represents a significant welfare improvement that some Norwegian producers have already implemented. The Aquatic Animal Welfare Assessment Tool developed by the Aquatic Animal Alliance provides a structured approach to slaughter welfare improvement.