Farmed Salmon Pre-Slaughter CO2 Stunning Welfare

Pre-slaughter methods for farmed salmon significantly affect welfare. CO2 narcosis remains controversial, while percussive and electrical stunning offer better welfare outcomes.

Key Facts

Norway alone produces 1.5 million tonnes of farmed salmon annually
CO2 narcosis is the most widely used pre-slaughter method but causes prolonged aversion
Salmon actively avoid CO2-saturated water, swimming frantically before unconsciousness
Percussive stunning renders fish unconscious within milliseconds
Electrical water bath stunning is rapid but requires careful calibration for efficacy

Welfare Considerations

Fish welfare at slaughter is a rapidly developing area of policy and science. CO2 stunning extends the period of consciousness while fish experience severe respiratory distress - behaviour that clearly indicates aversion. Norway's welfare regulations now restrict CO2 use and mandate percussive or electrical stunning for salmon. The UK is reviewing slaughter requirements following recognition of fish sentience. Transitioning from CO2 to humane methods represents one of the highest-impact welfare improvements available in aquaculture.

What You Can Do

Choose salmon certified under schemes that specify humane pre-slaughter methods
Ask retailers whether their suppliers use CO2 or percussive/electrical stunning
Support policy advocacy requiring humane slaughter methods for farmed fish
Engage with Marine Stewardship Council and Aquaculture Stewardship Council welfare lobbying
Reduce salmon consumption frequency or choose welfare-verified products