Salmon Recirculating Aquaculture Systems: Welfare Assessment

Recirculating aquaculture systems allow salmon farming on land with tighter water quality control. Their welfare implications compared to sea cage farming are complex.

Key Facts

RAS salmon farming uses intensive indoor tanks with water treatment and recirculation
RAS eliminates sea lice infestation and reduces escape risk compared to sea cage farming
High stocking densities in RAS tanks remain a welfare concern
Elevated CO2 levels from respiration must be carefully managed in closed systems
RAS has lower environmental impact but higher energy consumption than sea cage farming

Welfare Considerations

RAS salmon welfare depends critically on water quality management — elevated CO2 causes anaesthesia-like effects and chronic stress at lower concentrations. Dissolved oxygen must be maintained at saturating levels, and ammonia removed efficiently. The advantages of RAS — no sea lice, no parasite treatments, no escapes — represent real welfare gains, but high stocking densities and limited space for natural swimming behaviour remain concerns. RSPCA Assured and equivalent welfare standards are beginning to develop RAS-specific criteria.

What You Can Do

Ask whether RAS-farmed salmon meets any welfare certification scheme requirements
Support development of RAS-specific welfare standards by industry and welfare bodies
Advocate for mandatory welfare assessment of all farmed salmon production systems
Stay informed about innovations in RAS design that improve fish welfare outcomes
Choose welfare-certified salmon regardless of production system when available