Aquaculture Disease Management: Welfare During Outbreaks

Disease outbreaks in aquaculture cause major welfare and economic losses. Prevention through biosecurity, early detection and treatment decisions all have significant welfare implications.

Key Facts

Infectious Salmon Anaemia (ISA), Pancreatic Disease (PD) and Heart and Skeletal Muscle Inflammation (HSMI) are major Atlantic salmon diseases
Amoebic Gill Disease (AGD) caused by Neoparamoeba perurans requires repeated freshwater treatments
Disease outbreaks in sea cages can affect 100,000+ fish simultaneously
Treatment decisions involve trade-offs: treatments (freshwater, CO2 sedation) cause acute stress
Early culling of severely affected fish is a welfare improvement over allowing disease to progress to death
Biosecurity between sea cages (disinfection, fallowing, stocking age separation) reduces transmission risk
Vaccination has transformed some aquaculture disease management - reducing antibiotic use substantially

Welfare Considerations

Aquaculture disease welfare operates at the intersection of individual fish suffering and herd-level management imperatives. Individual fish experiencing AGD suffer from gill damage that impairs respiration - a fish with gill disease is perpetually breathless. Treatment (freshwater bathing) causes acute stress that must be weighed against the relief of reducing the gill parasite burden. Mass treatment decisions for 100,000+ fish require protocols that prioritise minimising overall suffering rather than optimising for individual fish welfare, which would be impractical at scale. Early detection of disease - through monitoring, behaviour observation and sampling - enables earlier intervention that reduces both individual suffering duration and population-level welfare cost.

What You Can Do

Support aquaculture certification that includes disease management welfare standards
Choose salmon from farms with documented low disease incidence and early intervention protocols
Advocate for mandatory disease reporting and welfare standards in aquaculture legislation
Support research into disease-resistant salmon breeding and vaccine development
Reduce farmed salmon consumption to reduce demand pressure on farms with high disease risk
Ask retailers about disease incident rates and management approaches in their salmon supply chains