Aquaculture

Farmed Salmon CO2 Stunning Welfare Debate

Carbon dioxide stunning of farmed salmon remains controversial, with evidence that it is aversive before inducing insensibility.

Key Facts

CO2 is used to anaesthetise salmon before slaughter in some farms
Fish show avoidance behaviour and agitation on contact with CO2-saturated water
CO2 causes acidification of blood that may be painful before anaesthesia
Electrical stunning is considered more humane as it induces rapid insensibility
Some certification schemes are moving away from CO2 as a primary stunning method

Welfare Considerations

If salmon experience distress during the period of CO2 exposure before losing consciousness - and the evidence suggests they may - then CO2 stunning involves a period of preventable suffering. Transitioning to electrical stunning systems that induce rapid insensibility would eliminate this welfare risk and should be a priority for the industry.

What You Can Do

Support aquaculture standards requiring rapid-induction stunning methods for salmon
Choose salmon products certified with electrical or percussion stunning
Advocate for phasing out CO2 as a primary salmon stunning method