Open water net pen salmon farming is the dominant production method globally. Understanding its welfare implications helps consumers and advocates push for meaningful improvements.
Net pen salmon farming creates welfare challenges at every stage of production. Sea lice cause chronic pain and tissue damage in millions of fish simultaneously. Lice treatments — bath treatments, laser systems, and cleaner fish deployment — all cause additional acute stress. Crowding limits normal behaviour and increases aggressive interactions. Environmental events like algal blooms cause mass suffering before death. The welfare problems of net pen salmon are structural rather than incidental — they arise from the fundamental exposure of high-density fish populations to a pathogen-rich marine environment. Addressing them comprehensively requires either dramatic production system changes or substantial density reductions.