Aquaculture

Farmed Trout Crowding and Welfare

Rainbow trout are highly sensitive to crowding stress, which impairs immune function, increases aggression and causes measurable suffering in intensive systems.

Key Facts

Rainbow trout are territorial and show agonistic behaviour when crowded
Crowding increases cortisol, reduces growth and suppresses immune function
Optimal stocking density for welfare is significantly lower than maximum commercial density
Fin erosion and injury rates increase linearly with stocking density
Dissolved oxygen management is critical as trout require high O2 at high density

Welfare Considerations

Trout welfare is strongly linked to stocking density management. Reducing density to welfare-optimal levels improves both animal wellbeing and production efficiency.

What You Can Do

Choose trout certified under welfare schemes with stocking density limits
Support research into optimal trout welfare indicators at different densities
Ask producers about their monitoring protocols for crowding-related welfare measures