Aquaculture

Farmed Fish Crowding and Aggression

Crowding stress in farmed fish drives aggression, injury, and chronic physiological stress that compromises welfare throughout production.

Key Facts

High stocking density increases cortisol and reduces immune function in most farmed fish
Aggressive species including salmon develop wound lesions from conspecific attack
Fin erosion is a marker of chronic aggression and welfare compromise
Density reductions improve welfare without proportional production losses

Welfare Considerations

Farmed fish at high stocking densities experience interference competition for food, oxygen, and space. Dominant individuals suppress subordinates through aggression causing chronic stress and wound lesions. Physiological changes from chronic crowding stress include immune suppression, cortisol elevation, and reduced stress resilience. Moderate density reductions with improved management achieve welfare gains compatible with sustainable production.

What You Can Do

Support salmon certified to welfare standards with density limits
Advocate for maximum density regulations in aquaculture welfare standards
Choose certified fish from lower-density operations
Back research into density management optimizing welfare and production