Recirculating aquaculture systems offer potential welfare improvements through controlled environments but face specific welfare challenges from water quality management and high stocking densities.
RAS welfare management is double-edged. The controlled environment of RAS removes many open-water welfare threats and enables optimised feeding, health monitoring and disease management. However, the high stocking densities that make RAS economically viable create challenges for welfare - crowding stress, competition and behavioural restriction. System reliability is a critical welfare consideration - any failure in aeration or filtration can kill thousands of fish in hours. Continuous monitoring systems with alarm capabilities are welfare-essential in RAS facilities. The welfare potential of RAS relative to sea cage farming depends entirely on operational standards and management quality.