Salmon Welfare in Recirculating Aquaculture Systems

Recirculating aquaculture systems (RAS) offer potential welfare improvements for farmed salmon but introduce new challenges around water quality and chronic stress.

Key Facts

RAS recycles 95-99% of water, allowing salmon farming in land-locked locations
Water quality parameters including dissolved oxygen, CO2, and pH require precise control
High CO2 from fish respiration in RAS causes narcosis and chronic stress if poorly managed
RAS eliminates sea lice and reduces antibiotic use compared to sea-cage systems
Stocking densities in RAS can still be high, limiting movement and increasing aggression
Norway and Scotland are investing heavily in RAS as a sustainable salmon farming alternative

Welfare Considerations

Recirculating aquaculture systems represent a significant technological shift in salmon farming that brings genuine welfare opportunities alongside new risks. By eliminating sea lice infestations and reducing disease transmission, RAS can improve fish health. However, elevated CO2 accumulation in recirculated water causes chronic respiratory distress if not carefully managed. Space limitations, sensory monotony, and high stocking densities remain concerns. Welfare monitoring in RAS requires real-time water quality tracking and behavioral observation to identify problems early.

What You Can Do

Support RAS certification schemes that include fish welfare monitoring criteria
Choose salmon products certified under high-welfare aquaculture standards
Advocate for mandatory water quality thresholds and welfare audits in RAS operations
Reduce farmed salmon consumption until welfare standards in the industry improve
Support research into optimal RAS parameters for minimizing salmon stress