Farmed Salmon Welfare 2025

The welfare crisis in the world's most valuable aquaculture species and pathways to reform

Overview: Atlantic salmon aquaculture produces approximately 2.7 million tonnes annually, making it the world's most economically significant farmed fish. Norway dominates production, followed by Chile, Scotland, Canada, and Australia. Despite its commercial importance, farmed salmon welfare is severely compromised by sea lice infestations, crowding, handling stress, infectious disease, and inadequate slaughter methods. In 2025, welfare science and consumer pressure are driving significant — but still insufficient — industry reform.

Scale of Production

Global Salmon Production (2025):
• Norway: ~1.5 million tonnes (55% of global production)
• Chile: ~600,000 tonnes (22%)
• Scotland: ~180,000 tonnes (7%)
• Canada: ~130,000 tonnes (5%)
• Australia, Faroe Islands, Iceland: remainder
• Total fish: approximately 500–600 million salmon slaughtered annually

Key Welfare Issues

Sea Lice

Sea lice (Lepeophtheirus salmonis, Caligus spp.) are ectoparasitic copepods that attach to and feed on salmon skin and tissue. Heavy infestations cause open wounds, hemorrhaging, secondary infections, and death. Sea lice are the most significant welfare and production challenge in global salmon farming.

Critical Welfare Concern: Sea lice treatments themselves cause significant welfare harm. Thermal treatments (bathing fish in 34°C water) cause scale loss, fin damage, and mortality. Mechanical treatments (water jets, lasers) cause physical trauma. Chemical treatments stress fish. No treatment is welfare-neutral — welfare is compromised both by lice and by treatment.

Crowding and Density

Commercial net pens typically hold 25–30 kg of fish per cubic meter. At high densities, dominance hierarchies break down, aggressive interactions increase, and subordinate fish are unable to access food effectively. Crowding also increases disease transmission and reduces water quality around fish.

Handling Stress

Salmon are repeatedly handled throughout their production cycle — grading, treatment, transfer, and harvest. Each handling event causes acute stress responses: elevated cortisol, fin damage from crowding, and immune suppression following stress.

Infectious Pancreatic Necrosis (IPN) and ISA

Viral diseases including IPN and Infectious Salmon Anaemia (ISA) cause mass mortality events and chronic suffering in affected fish. Gill disease, Heart and Skeletal Muscle Inflammation (HSMI), and amoebic gill disease (AGD) also cause significant welfare impacts globally.

Slaughter Methods

Progress in 2025

Norwegian Industry Reforms: Norwegian salmon sector has adopted mandatory sea lice counting and threshold-based treatment triggers. Several major producers have invested in snorkel cages (reducing surface lice exposure), in-pen vaccination delivery systems, and cleaner fish (wrasse and lumpfish) as biological lice control. Mortality reporting transparency has improved significantly.

Scottish Standards: RSPCA Assured salmon certification requires effective stunning, lower stocking densities, and sea lice action thresholds. Several major Scottish producers are RSPCA Assured certified. Mandatory mortality reporting introduced by Marine Scotland provides welfare monitoring data.

Welfare Indicators: The OptiWel and FishWel projects have developed standardized salmon welfare indicator protocols now adopted by major producers in Norway and Scotland. These include eye condition, fin damage, cataracts, gill scoring, and swimming behavior assessment.

Recirculating Aquaculture Systems (RAS)

Land-based recirculating aquaculture systems eliminate sea lice, disease transmission, and escapement risks. However, RAS salmon welfare concerns include high fish density in tanks, limited ability to express natural behavior, chronic crowding, and the significant energy cost that may limit scaling. RAS welfare can be excellent or poor depending on management.