Farmed Salmon Pre-Slaughter Welfare: CO2 Stunning and Alternatives

Pre-slaughter welfare in salmon farming is critical. CO2 stunning is widely used but evidence suggests it is aversive. More humane alternatives are being adopted.

Key Facts

Atlantic salmon is the most farmed finfish species globally by value, with Norway leading production
CO2 immersion for stunning causes carbon dioxide narcosis but is preceded by active aversion responses
Percussive stunning delivers a physical blow to the head causing rapid unconsciousness
Electrical stunning when correctly applied achieves rapid unconsciousness with less aversion
The RSPCA and other welfare bodies recommend against CO2 as the sole stunning method for salmon

Welfare Considerations

Pre-slaughter welfare in farmed salmon is a major issue given the billions of fish processed annually. CO2 immersion, the most common method, causes observable aversion behaviour before loss of consciousness, suggesting it is unpleasant or painful. Percussive stunning (spiking) causes rapid unconsciousness but is labour-intensive and variable in effectiveness. Electrical water bath stunning, when properly calibrated for salmon, achieves rapid unconsciousness before any further processing. Some Norwegian producers have adopted electrical stunning at scale. Consumer pressure and welfare certification standards are driving improvement in this area.

What You Can Do

Choose salmon bearing RSPCA Assured, ASC, or equivalent welfare certification
Support producers investing in electrical or percussive stunning technology
Advocate for welfare standards requiring humane slaughter methods for farmed fish
Reduce farmed salmon consumption until welfare standards improve across the industry