Farmed Animals

Farmed Salmon Welfare: Crowding and Aggression

High stocking densities in salmon net pens increase aggression, injury, and stress; density reduction and structural enrichment improve welfare outcomes measurably.

Key Facts

Commercial Atlantic salmon are typically stocked at 15-25 kg per cubic meter in net pens
Social hierarchies in high-density conditions lead to fin biting, injury, and unequal resource access
Submissive salmon show chronic cortisol elevation and altered immune function
Structural complexity in pens using center structures reduces aggressive interactions
Norwegian regulations set maximum stocking densities but welfare science suggests lower thresholds are needed

Welfare Considerations

Salmon in high-density pens experience chronic social stress from competitive hierarchies that harm subordinate individuals through reduced feeding access, persistent aggression, and immune suppression. Research has shown that even modest reductions in stocking density significantly reduce fin damage and cortisol levels. Structural enrichment providing shelter and visual breaks allows subordinate fish to avoid dominant individuals.

What You Can Do

Choose salmon from farms with documented low stocking density commitments
Support welfare certification schemes that specify maximum salmon stocking densities below regulatory maxima
Advocate for density limits based on welfare science rather than production economics
Reduce salmon consumption or choose plant-based omega-3 sources