Sea Trout Welfare in Aquaculture

Key Welfare Considerations

• Sea trout are anadromous forms of brown trout, requiring specific environmental conditions linked to their migratory biology.
• Welfare challenges in sea trout aquaculture include sea lice infestation, crowding stress, and water quality management.
• Sea lice (Lepeophtheirus salmonis and Caligus spp.) cause significant welfare impacts through skin damage and osmoregulatory disruption.
• Sea trout are particularly susceptible to sea lice compared to Atlantic salmon, requiring careful co-culture management.
• Optimal water temperature ranges for sea trout welfare are 8-16°C, with thermal stress above 20°C.
• Dissolved oxygen management is critical — sea trout require ≥7 mg/L for normal welfare.
• Stocking density significantly affects sea trout welfare, with crowding causing chronic stress responses.
• Feed conversion efficiency and growth rates serve as indirect welfare indicators in commercial production.
• Handling stress during grading and harvesting activates cortisol stress responses detectable for hours.
• Percussion stunning before slaughter is welfare-positive but requires proper calibration for sea trout.
• Fin erosion from crowding and substrate absence indicates poor welfare in intensive systems.
• Genetic selection for sea trout traits must consider welfare alongside production performance.
• Welfare assessment frameworks adapted from salmon aquaculture are being applied to sea trout production.
• Environmental enrichment through water current and structural complexity reduces stereotypic behaviour.
• Integrated pest management approaches reduce sea lice welfare impacts while minimising chemical treatments.