Farmed Atlantic Salmon in RAS: Land-Based Aquaculture and Welfare

Recirculating aquaculture systems (RAS) for Atlantic salmon offer potential welfare advantages over net pen farming but introduce new challenges including water quality management, high stocking density, and light manipulation.

Key Facts

RAS facilities recirculate and filter water, enabling salmon farming in landlocked locations far from the sea.
Land-based RAS eliminates sea lice exposure and reduces disease pressure from wild fish populations.
Water quality in RAS systems is highly controlled but mechanical failures can cause rapid mortality events.
Stocking densities in some RAS facilities are very high, raising concerns about space and behavioural restriction.
RAS operations use continuous light manipulation to control growth and reproduction, which may affect fish welfare.
Carbon dioxide accumulation from fish respiration in recirculating systems can cause narcosis and gill pathology.
Energy consumption in RAS is substantially higher than sea cage farming, raising sustainability questions.

Welfare Considerations

RAS salmon farming presents a mixed welfare picture. Elimination of sea lice and some diseases removes significant sources of chronic suffering. However, the highly controlled environment of RAS systems requires near-perfect management — water quality failures can rapidly become welfare emergencies. Stocking density, continuous light manipulation, and CO2 management are welfare variables that require active oversight. Higher-welfare RAS operations invest in real-time water quality monitoring, lower stocking densities, natural light simulation, and rapid emergency response protocols. Consumer demand for welfare-certified land-based salmon can incentivise better practices across the sector.

What You Can Do

Choose RAS salmon from producers with transparent welfare monitoring and independent certification.
Support research into optimal RAS conditions for salmon welfare including light cycling and density standards.
Advocate for aquaculture welfare regulations that apply equally to RAS and sea cage systems.
Ask retailers about the sourcing and welfare standards of land-based salmon products they stock.