Pre-slaughter handling is a critical welfare period for farmed salmon. Crowding, air exposure and inadequate stunning are significant welfare concerns that practical improvements can substantially address.
Pre-slaughter welfare for farmed salmon has historically been poorly managed despite the scale of the industry (over 2 million tonnes produced annually). The aversive nature of CO2 narcosis - widely used because it is cheap and practical - has been clearly demonstrated: salmon actively avoid CO2-enriched water and show acute stress responses when exposed. Transition to electrical stunning or AQUI-S (isoeugenol) anaesthesia significantly reduces pre-slaughter suffering. The commercial incentive for improvement is modest where welfare costs are not priced into product value; certification standards that require effective stunning create the market mechanism for welfare improvement.