Farmed Salmon Recirculating Aquaculture Systems

Recirculating aquaculture systems offer welfare benefits over sea cage salmon farming but introduce new challenges requiring careful management to achieve good fish welfare.

Key Facts

Recirculating aquaculture systems (RAS) filter and recycle water, enabling land-based salmon farming.
RAS eliminates sea lice infestations and reduces antibiotic use compared to sea cage systems.
Water quality parameters including oxygen, CO2, pH, and ammonia require continuous monitoring.
High CO2 accumulation in poorly managed RAS causes respiratory distress and reduced welfare.
RAS allows year-round production with full environmental control, reducing predation risk.

Welfare Considerations

RAS salmon farming offers significant welfare improvements by eliminating sea lice and reducing disease exposure. However, poor water quality management, particularly elevated CO2, can cause chronic welfare compromise. High stocking densities, inadequate lighting regimes, and handling stress during grading remain concerns. Well-managed RAS with appropriate stocking densities, optimal water chemistry, and enriched environments can achieve substantially better welfare outcomes than conventional sea cage systems.

What You Can Do

Ask salmon retailers whether products come from RAS or sea cage systems and the welfare standards applied.
Support certification schemes that verify RAS water quality and stocking density standards.
Advocate for mandatory welfare monitoring requirements in RAS aquaculture licensing.
Reduce farmed salmon consumption or choose certified welfare-friendly sources.
Support research into RAS water quality optimisation for fish welfare outcomes.