Land-based recirculating aquaculture systems for salmon eliminate sea lice and reduce escape risk, but create unique welfare challenges related to high density, water quality, and artificial conditions.
Land-based RAS salmon farming represents an environmental improvement over open-net pen aquaculture but does not automatically produce better animal welfare. The welfare picture in RAS is complex: elimination of sea lice removes a significant welfare burden, but extreme stocking densities enabled by precise water quality control create crowding stress that may equal or exceed that in open pens. The artificial environment — concrete tanks, artificial light cycles, controlled water flow — differs markedly from any natural environment and may create behavioral welfare deficits not captured by purely physiological welfare measures. Power failure risk is a unique welfare hazard: an interruption to aeration in a high-density RAS tank can render fish unconscious within minutes and kill them within hours. Best welfare practice in RAS combines lower stocking densities, appropriate light management, behavioral monitoring, and robust emergency power systems.