Farmed Salmon Welfare at Harvest: Stress and Slaughter

The harvest period is a critical welfare moment for farmed salmon, with significant variation in practice and welfare outcome.

Key Facts

Salmon crowding during harvest causes extreme stress — cortisol spikes are among the highest measured in aquaculture
Food withdrawal before harvest is required to clear gut content but causes hunger stress
Electrical or percussive stunning before killing is considered the most humane slaughter approach
CO2 narcosis is aversive and causes distress before insensibility in salmon
Transport of live salmon to onshore slaughter facilities involves handling stress and possible injury
Well Boat harvest transport — pumping fish between nets and vessels — is a significant stress event

Welfare Considerations

Salmon harvest welfare encompasses a sequence of stressors: food withdrawal, crowding, pumping, stunning, and killing. Each element can be managed to minimise welfare cost or can cause significant suffering if conducted poorly. Electrical stunning before killing — when performed correctly — renders fish insensible within milliseconds and is the most welfare-positive slaughter method. Crowding stress during harvest can be reduced through careful management of pen density during harvest operations. Well Boat transport adds handling events that each carry welfare costs. Welfare-forward producers invest in harvest protocols that minimise stressor accumulation through the entire harvest sequence, not just the final slaughter moment.

What You Can Do

Choose salmon from producers committed to electrical stunning at slaughter
Ask retailers what slaughter standards their salmon suppliers are required to meet
Support regulatory requirements for pre-slaughter stunning for all farmed salmon
Advocate for harvest welfare protocols to be included in aquaculture certification standards
Support research into lower-stress harvest methods including anaesthetic approaches