Recirculating aquaculture systems (RAS) offer improved biosecurity and reduced environmental impact, but their welfare implications for fish require careful consideration.
RAS technology represents both an opportunity and a challenge for fish welfare. The controlled environment allows precise management of water quality and feeding, potentially benefiting welfare compared to open-net pen systems. However, the typically high stocking densities, artificial lighting regimes, and mechanical noise and vibration may cause chronic stress. Fish in high-density systems show elevated cortisol levels and increased aggressive behavior. Welfare-conscious RAS design incorporates appropriate stocking density limits, enrichment, natural light cycles, and careful monitoring of behavioral indicators. The industry is still developing evidence-based welfare standards specific to closed-containment systems.