Atlantic Salmon Welfare: Industry Standards and Challenges

Key Welfare Considerations

• Atlantic salmon farming produces approximately 2.5 million tonnes annually — welfare standards affect billions of individual fish.
• Sea lice (Lepeophtheirus salmonis and Caligus) are the most significant welfare challenge in open-net pen systems.
• Sea lice welfare control methods include biological (cleaner fish), thermal, and mechanical approaches.
• Cleaner fish including wrasse and lumpsucker reduce sea lice welfare burden in integrated systems.
• Thermal delousing causes welfare thermal shock — refinement of temperature and duration reduces welfare impacts.
• Gill health is a major welfare concern — amoebic gill disease (AGD) causes respiratory welfare impairment.
• Crowding stress during treatments, grading, and harvesting activates measurable welfare stress responses.
• Welfare indicators in salmon include fin erosion, cataract prevalence, wound healing, and behaviour.
• ASC (Aquaculture Stewardship Council) salmon standard includes welfare criteria for certification.
• Better practices like Aquaculture Stewardship are improving welfare outcomes across certified farms.
• Pre-slaughter welfare requires appropriate crowding management and effective stunning before killing.
• Percussive stunning, electrical stunning, and CO2 narcosis are used — efficacy varies by method and conditions.
• Welfare science research is transforming salmon aquaculture — pain recognition, stress measurement, and indicators are advancing.
• Consumer demand for higher welfare salmon is driving retail commitments to improved farm standards.
• Open-net pens vs. RAS welfare comparison depends on management quality — neither system inherently provides better welfare.