Turbot Welfare in Intensive Recirculating Aquaculture Systems

Turbot are a premium flatfish species farmed in recirculating systems in Europe, with welfare challenges shaped by their benthic lifestyle and competitive feeding behaviour.

Key Facts

Turbot (Scophthalmus maximus) are farmed in Spain, Portugal, France and China in intensive RAS systems, with Spain the dominant European producer
As benthic flatfish, turbot require tank substrate and adequate bottom area — stacking cages increase density but may compromise welfare
Dominance hierarchies at feeding cause significant size variation — smaller individuals in the cohort are consistently underfed in competitive feeding systems
Water temperature management between 16-20 degrees Celsius optimises turbot welfare and growth in RAS production

Welfare Considerations

Turbot welfare in intensive RAS faces the classic benthic species challenge — systems optimised for production throughput often compromise the environmental requirements of animals evolved for a benthic lifestyle. High stocking density on tank bottoms creates territorial competition and reduces access to substrate for subordinate individuals. Demand feeding systems reduce but do not eliminate feeding competition. Regular size-grading creates size-uniform cohorts with lower aggression and more equitable welfare across the group. Temperature management is critical — welfare outside the 16-20 degree range declines rapidly in this thermally sensitive species.

What You Can Do

Maintain stocking density within welfare-based limits — 40-50 kg/m2 of bottom area is a commonly cited welfare threshold
Implement demand feeding systems to reduce competition and allow individual feeding at self-selected rates
Grade turbot by size every 6-8 weeks to maintain size-uniform cohorts with reduced aggression
Monitor water temperature continuously in RAS systems and maintain 16-20 degrees Celsius for optimal welfare