Salmon Welfare in Recirculating Aquaculture Systems

Recirculating aquaculture systems (RAS) allow salmon to be farmed inland with reduced environmental impact. Their welfare implications differ significantly from sea cage farming and require dedicated assessment frameworks.

Key Facts

RAS facilities recycle up to 99% of water and allow complete biosecurity control, reducing sea lice and disease risk
Atlantic salmon in RAS experience high water quality consistency but may lack natural light cycles and spatial complexity
Stocking densities in RAS are typically higher than sea cage systems, raising crowding stress concerns
RAS salmon show less fin damage and sea lice infestation than sea-cage counterparts — a clear welfare benefit
Mortality rates in RAS are generally lower, but abrupt water quality failures can cause acute mass mortality events

Welfare Considerations

RAS salmon farming offers genuine welfare improvements over traditional sea cage systems in some dimensions — reduced sea lice, lower disease incidence, and better water quality control — while introducing new welfare challenges. High stocking densities, artificial lighting, and absence of natural environmental complexity may impair welfare in ways that are less visible than lice or fin damage. Research is developing species-appropriate welfare indicators for RAS salmon, including cortisol markers, fin scoring, and behavioural measures of chronic stress. Consumer demand for certified, high-welfare farmed salmon creates incentives for adopting emerging best practices in RAS management.

What You Can Do

Ask your salmon supplier about their farming system and welfare standards before purchasing
Support research into RAS salmon welfare indicators and the development of certification standards
Choose salmon with recognised welfare or sustainability certification where available
Reduce farmed salmon consumption or substitute with lower-impact certified alternatives