Aquaculture

Farmed Salmon Crowding Stress Assessment

Crowding is an unavoidable feature of salmon farming during harvest and health treatments, requiring standardised stress assessment to minimise welfare impact.

Key Facts

Salmon are crowded for health checks, lice counting, treatment, and harvest
Crowding densities can reach 200kg per cubic metre during treatment
Cortisol responses peak within minutes and may persist for hours
Mortality during crowding events can reach 0.5% or more in some operations
Standardised crowding protocols with time limits reduce welfare impact

Welfare Considerations

Crowding causes acute physiological stress through hypoxia, physical contact, and restriction of movement. Standardising crowding duration, density, and monitoring is a welfare imperative. The least number of crowding events, with the shortest possible duration, minimises lifetime welfare impact on individual fish.

What You Can Do

Support aquaculture certifications that limit crowding frequency and duration
Choose certified salmon from farms with transparent welfare protocols
Advocate for crowding stress assessment as a mandatory aquaculture welfare measure