Recirculating aquaculture systems (RAS) offer significant welfare advantages over sea cage farming for salmon and other species through controlled environment management.
RAS welfare advantages are substantial compared to open sea cage systems - elimination of sea lice and their treatment, controlled water quality preventing the welfare costs of algal blooms and harmful temperature events, and the ability to monitor and respond to fish health more quickly. However, RAS is not welfare-problem-free: high density management remains common, equipment failures can cause rapid water quality deterioration, and acoustic environments in recirculating systems may differ from natural habitats. The welfare improvement potential of RAS compared to sea cage systems depends on how the controlled environment is used - a high-density, poorly managed RAS may not improve on a well-managed sea cage. The technology enables better welfare; it does not guarantee it.