Farmed Salmon Pre-Slaughter Welfare: Fasting, Transport, and Crowding

The pre-slaughter phase of salmon farming involves fasting, crowding, and transport that cause significant acute welfare harms to millions of fish.

Key Facts

Salmon are fasted for 24-72 hours before slaughter to empty gut contents and maintain flesh quality
Pre-slaughter crowding concentrates fish into very high densities, causing hypoxia, scale loss, and aggression
Live fish are often transported in wellboats from sea cages to processing facilities, causing stress and injury
Water temperature and oxygen levels during pre-slaughter handling critically affect stress responses
Overcrowded pre-slaughter pens show loss of equilibrium in fish — a key welfare distress indicator
The period from pen crowding to slaughter may span several hours of increasingly stressful conditions

Welfare Considerations

Pre-slaughter handling represents one of the most acute welfare challenges in salmon farming. Crowding and crowning during net concentration cause hypoxia, scale damage, and equilibrium loss. Extended fasting, while reducing gut-derived flesh contamination, creates hunger stress in physiologically active fish. Wellboat transport subjects fish to novel water conditions, vibration, and crowding for extended periods. The cumulative stress of pre-slaughter handling elevates cortisol levels and can impair flesh quality as well as causing significant welfare harm. Welfare-conscious operations minimise crowding duration, oxygenate crowded water, minimise transport distances, and proceed to slaughter as rapidly as possible after crowding.

What You Can Do

Choose salmon from RSPCA Assured or equivalent schemes with pre-slaughter welfare requirements
Support research into on-site slaughter systems that eliminate transport stress
Advocate for maximum crowding duration and density standards in salmon pre-slaughter regulations
Reduce farmed salmon consumption or choose plant-based alternatives