The handling of farmed salmon immediately before slaughter significantly affects welfare, with stunning methods and crowding practices determining the experience of billions of fish.
Pre-slaughter handling of farmed salmon represents a welfare issue affecting billions of individual fish annually. The traditional crowding, pumping, and CO2 stunning approach used in much of the industry causes progressive distress from the point of crowding through loss of consciousness. CO2 causes a period of apparent distress before insensibility that welfare scientists consider comparable to suffocation. The alternatives - percussion stunning and electrical stunning systems - are welfare improvements that industry adoption has been slow because they require capital investment. Consumer and regulatory pressure has begun driving change, particularly in Norwegian and Scottish salmon farming where premium markets create incentives for welfare certification.