Farmed Atlantic Salmon RAS Welfare

Recirculating aquaculture systems for Atlantic salmon offer potential welfare advantages through controlled conditions but introduce new welfare challenges from water chemistry management.

Key Facts

RAS recirculate and treat water continuously, allowing precise control of temperature, oxygen, and pH
CO2 accumulation in RAS water is a significant welfare concern if not managed through adequate degassing
RAS facilities eliminate sea lice pressure and reduce disease risk from wild fish contact
Stocking densities in RAS can be higher than sea cages due to controlled oxygen supplementation
Chronic high CO2 exposure causes aversion responses and impairs neurological function in salmon
RAS allows production in inland locations near consumer markets, reducing transport stress and carbon footprint

Welfare Considerations

RAS salmon welfare presents a mixed picture. Elimination of sea lice, disease from wild contacts, and predator stress are genuine welfare advantages. However, RAS introduces the specific welfare challenge of CO2 accumulation, which causes aversion, impaired behaviour, and physiological stress at levels that can occur in poorly managed systems. Stocking densities in RAS may be pushed beyond welfare-optimal levels justified by the controlled oxygen environment. RAS welfare requires rigorous monitoring of dissolved CO2 alongside dissolved oxygen, and appropriate degassing infrastructure to maintain fish welfare throughout production.

What You Can Do

Support aquaculture welfare research specifically addressing RAS-specific welfare challenges including CO2 management
Advocate for welfare certification schemes that include RAS-specific water quality standards beyond oxygen
Choose salmon from RAS producers with documented water quality monitoring protocols
Support research into optimal stocking densities for RAS production that balance productivity and welfare
Engage with aquaculture innovation bodies to prioritise welfare alongside sustainability in RAS development