Farmed Salmon Infectious Disease Management and Welfare

Infectious diseases in farmed salmon cause enormous welfare burden through mass mortality events, treatment stress, and chronic subclinical infections affecting millions of fish annually.

Key Facts

Infectious salmon anaemia (ISA), pancreas disease (PD), and heart and skeletal muscle inflammation (HSMI) are major welfare threats
Sea cage conditions — high density, poor water circulation — facilitate rapid disease transmission within and between farms
Treatment of bacterial diseases with antibiotics causes stress through handling, reduced feeding, and medication side effects
Vaccination programmes have dramatically reduced antibiotic use in Norwegian salmon farming compared to the 1990s
Mass mortality events from disease outbreaks affect millions of individual fish, causing suffering at enormous scale
Early detection through water sampling and fish health monitoring can enable intervention before disease spreads
Closed containment systems (RAS) substantially reduce disease introduction risk by excluding wild vectors

Welfare Considerations

Infectious disease in farmed salmon represents welfare harm at a scale that is difficult to comprehend — mass mortality events killing millions of individual animals in a single outbreak. The suffering involved spans the full spectrum from chronic subclinical infection causing impaired function to acute disease with high mortality. Disease management creates its own welfare costs through handling stress during treatments, the physiological effects of therapeutic interventions, and the trauma of sampling and monitoring procedures. Prevention through vaccination, biosecurity, and management systems that reduce transmission risk is far more welfare-positive than treatment. The long-term path to reduced disease burden in salmon farming combines better farm siting, reduced stocking densities, closed containment systems, and continued vaccine development.

What You Can Do

Choose salmon from producers with strong vaccination programmes and low antibiotic use records
Support legislation mandating disease reporting and biosecurity standards in salmon farming
Advocate for reduced stocking densities that limit disease transmission in sea cage systems
Fund research into salmon disease prevention and welfare-positive treatment methods
Support the transition to land-based RAS farming that reduces disease introduction from wild vectors
Ask salmon producers about their disease monitoring protocols and outbreak history