Turbot Welfare in Aquaculture

Key Welfare Considerations

• Turbot are benthic flatfish requiring specific tank design with large floor area relative to volume.
• Horizontal surface area is the critical dimension for turbot welfare — vertical depth is less important.
• Optimal welfare temperatures for turbot range from 16-20°C; thermal stress occurs at extremes.
• Stocking density must account for floor area occupation rather than volumetric density calculations.
• Turbot are solitary and territorial in nature, and high densities cause aggression and fin damage.
• Circular or square tanks with smooth floors and recirculation systems achieve best welfare outcomes.
• Cannibalism in juvenile turbot is a significant welfare concern during early rearing stages.
• Grading by size reduces cannibalism and competition, improving group welfare in juvenile tanks.
• Sea lice affect turbot but with lower prevalence than in Atlantic salmon aquaculture.
• Vaccination programmes reduce bacterial disease welfare impacts in intensive turbot systems.
• Feed transition from live prey to pellets can cause welfare-related feeding stress in juveniles.
• Handling stress during grading activates measurable cortisol stress responses detectable for 24 hours.
• Water quality monitoring — dissolved oxygen, ammonia, pH — is critical to welfare in RAS systems.
• Pre-slaughter stunning using electrical or percussion methods is important for turbot welfare.
• Turbot welfare standards are less developed than for salmon, representing a research and policy gap.