Farmed Salmon Pre-Slaughter Welfare

The final hours before slaughter are a critical welfare period for farmed salmon, with practices varying dramatically in their welfare impact.

Key Facts

Pre-slaughter crowding to facilitate harvest is a major welfare concern — cortisol spikes during crowding are among the highest measured in production
Withholding feed for 1-3 days before slaughter reduces gut content but causes welfare-relevant hunger and stress
Electrical stunning, percussion stunning, and CO2 are the primary stunning methods — electrical stunning has strongest evidence for rapid insensibility
Live chilling in ice slurry without prior stunning causes prolonged distress — banned in Norway but still used globally
The Hap system (high-speed automatic processor) enables stunning and slaughter within seconds of net pen crowding
Post-slaughter bleeding quality improves with effective stunning — aligning welfare and product quality incentives

Welfare Considerations

Pre-slaughter welfare for farmed salmon is one of the highest-impact welfare intervention areas in aquaculture given the enormous production volumes. The traditional harvest method — net pen crowding followed by CO2 immersion or live chilling in ice slurry — causes prolonged stress and potentially painful death for fish that have physiological and neurological evidence of pain capacity. Live chilling without stunning has been shown to cause up to 15 minutes of apparent consciousness as body temperature drops gradually — a significant welfare cost. The shift toward rapid mechanical stunning (percussion captive bolt) or electrical stunning followed by immediate slaughter dramatically reduces the duration and severity of the slaughter welfare event. Norway has regulatory requirements for pre-slaughter stunning; most other major salmon-producing countries do not.

What You Can Do

Choose salmon certified under schemes that specify pre-slaughter stunning methods as a welfare requirement
Advocate for mandatory pre-slaughter stunning requirements for salmon in all major producing countries
Support regulatory harmonisation that adopts Norwegian slaughter welfare standards globally
Engage with aquaculture certification bodies to incorporate pre-slaughter welfare as a central audit criterion
Support research into optimal stunning methods for salmon that maximise effective insensibility rate and product quality