Atlantic Halibut Welfare in Aquaculture

Key Welfare Considerations

• Atlantic halibut are the largest flatfish in the world, requiring specific welfare management as they grow.
• Juvenile halibut metamorphosis from pelagic to benthic lifestyle is a welfare-critical developmental period.
• Eye migration failure during metamorphosis causes permanently malformed juveniles with welfare and commercial implications.
• Light management during metamorphosis is critical — inappropriate lighting causes incomplete eye migration welfare problems.
• Optimal welfare temperatures are 12-14°C — thermal stress outside this range causes immune and metabolic impacts.
• Halibut require high protein, high fat diets with specific DHA/EPA ratios for welfare-optimal growth.
• Feeding behaviour is aggressive in juvenile halibut — size grading to reduce welfare impacts from cannibalism is essential.
• Adult halibut can reach 200kg+ — tank design must accommodate welfare-appropriate movement for large individuals.
• Sea lice infestation causes welfare impacts similar to salmon but with species-specific treatment considerations.
• Vaccination programmes against Vibrio and Aeromonas pathogens reduce disease welfare burden.
• Handling stress during weighing and grading requires minimisation — halibut are stress-sensitive at all life stages.
• Pre-slaughter welfare includes starvation timing and appropriate stunning — percussion or electrical methods.
• Welfare assessment frameworks for halibut are less developed than for salmon — research is ongoing.
• Genetic programmes selecting for disease resistance and stress tolerance improve welfare alongside production.
• Halibut aquaculture expansion makes proactive welfare standard development important for this growing sector.