Anaesthesia and Welfare During Handling in European Sea Bass Aquaculture

Anaesthesia is increasingly used in sea bass aquaculture to reduce handling stress during grading, vaccination and transport, improving welfare outcomes.

Key Facts

MS-222 (tricaine), clove oil (eugenol) and AQUI-S are the most common anaesthetics used in commercial sea bass operations
Anaesthetised sea bass show significantly lower cortisol responses and fewer scale losses during grading compared to unanaesthetised fish
Recovery time and post-anaesthesia welfare are as important as induction time in anaesthetic protocol design
EU regulations on veterinary medicines affect anaesthetic availability, creating welfare gaps in some member states

Welfare Considerations

Handling without anaesthesia causes acute stress responses in sea bass measurable for up to 24 hours post-procedure. Scale loss, physical injury and immune suppression follow stressful handling events. While anaesthesia adds time and cost, welfare and production benefits justify its use for procedures lasting more than a few minutes or involving large numbers of fish. Optimising anaesthetic concentration, temperature and recovery conditions are all critical welfare considerations.

What You Can Do

Adopt anaesthesia protocols for all procedures lasting more than 2-3 minutes
Train farm staff in correct anaesthetic concentration measurement and recovery assessment
Monitor recovery tank oxygen levels continuously — anaesthesia increases oxygen demand
Work with regulatory bodies to ensure welfare-improving anaesthetics remain available to producers