The welfare of Atlantic salmon in sea cage aquaculture is determined by a complex of stocking density, sea lice burden, water quality, and handling practices across a 2-3 year production cycle.
Sea pen welfare is challenging to manage because the marine environment creates stressors outside farm operator control: jellyfish blooms cause physical damage; warm water above threshold temperatures causes thermal stress; algal blooms deplete oxygen. Within operator control, stocking density, lice burden management, and handling protocols offer the most impactful welfare levers. The combination of environmental unpredictability and the welfare needs of millions of individual fish makes salmon aquaculture welfare one of the most complex challenges in food animal production.