Salmon Crowding and Pre-Slaughter Welfare

The crowding of salmon immediately before slaughter for density reduction and ease of harvest causes acute stress and welfare harm that pre-slaughter stunning can partially address.

Key Facts

Pre-harvest crowding concentrates salmon into increasingly small volumes to facilitate transfer to slaughter
Crowding activates stress responses including cortisol elevation, scale loss, and hypoxia at high densities
The crowding period before slaughter may last from minutes to hours depending on operational practice
Effective stunning before slaughter prevents conscious experience of the killing process
Electrical stunning in water followed by gill cut is considered an effective humane slaughter method
Percussion stunning and use of carbon dioxide are also used, with varying welfare outcomes

Welfare Considerations

Pre-slaughter crowding causes acute and significant welfare harm through oxygen depletion, physical crushing, scale damage, and the physiological stress of extreme confinement. Fish in crowded pre-slaughter tanks show clear behavioural and physiological distress responses. Effective stunning immediately before slaughter can render fish insensible before they experience the killing process itself, but does not address the welfare harm of the crowding period. Minimising the duration and density of pre-slaughter crowding, combined with mandatory effective stunning, would substantially reduce the welfare harm associated with salmon slaughter.

What You Can Do

Support aquaculture welfare campaigns that specifically target pre-slaughter handling and stunning standards
Choose salmon from producers certified to standards requiring effective stunning before slaughter
Advocate for regulatory requirements mandating effective stunning in fish slaughter operations
Support research into improved slaughter methods that minimise pre-slaughter crowding duration
Reduce farmed salmon consumption to reduce the scale of pre-slaughter welfare harm in the industry