Commercial‐scale Validation of Temperature‐step Rearing on Growth Physiology in Turbot,Scophthalmus maximus

The aim of this study was to investigate the possible benefit of “temperature‐steps” (T‐steps) rearing for juvenile turbot (initial weight 15.1 g) under realistic production scale and to determine whether initial growth advantage is maintained throughout the rearing period to market size. One group (called T‐step 22‐19‐16) of juvenile turbot was reared at three different temperatures, that is, 22 C (from 17 to 60 g) followed by 19 C (from 60 to 100 g) and 16 C (>100 g); another group (called T‐step 19‐16) at two temperatures, that is, 19 C (from 17 to 100 g) and lowered to 16 C (>100 g); and the third group (called C16) at one constant temperature, that is, 16 C. Relative growth was significantly higher in the two T‐step groups, with the T‐step 19‐16 showing the highest overall growth. Feed conversion efficiency was highest in the 19‐16 group. Only minor effects of the experimental rearing on blood physiology were found, with one notable exception of inverse relationship between plasma glucose and growth. Overall, these findings indicate that a short interval of rearing fish at high temperature during the early juvenile phase may have a long‐term effect on biomass increment in turbot. This is an important finding for the turbot industry.