Aquaculture

Farmed Salmon Crowding Stress: Science and Solutions

Crowding stress during routine management operations causes acute suffering in farmed salmon, with new approaches reducing exposure and severity.

Key Facts

Crowding for lice treatment, grading, and harvest is a significant source of acute stress in salmon farming
Cortisol responses to crowding can persist for days, affecting immune function and growth
Sensor-guided crowding systems can reduce crowding density while maintaining operational efficiency
Avoidance of crowding during high temperature periods reduces combined stress responses

Welfare Considerations

Crowding stress is one of the most significant acute welfare costs in salmon farming, occurring multiple times in an animal's life during routine management. Operational practices that minimise crowding density, duration, and temperature conditions during crowding events represent achievable welfare improvements.

What You Can Do

Support salmon producers demonstrating crowding stress reduction protocols
Advocate for crowding stress minimisation to be a welfare certification requirement
Engage with research on stress-free management alternatives to crowding for routine operations