Hemoglobin genotypes of turbot (Scophthalmus maximus): consequences for growth and variations in optimal temperature for growth

We studied the growth properties of three different hemoglobin genotypes of juvenile turbot (Scophthalmus maximus) reared at 10, 14, 18 and 22 degrees C. The genotype Hb-I(2/2) displayed the overall highest growth rate in the temperature range 14-22 degreesC, whereas no differences were found at sub- optimal temperature (10 degreesC). The differences in growth were largest a t optimal temperatures where the Hb-I(2/2) genotype displayed 13% higher gr owth than the two other genotypes. Optimal temperature for growth (T-opt.G) varied between the genotypes with the genotype Hb-I(2/2) displaying the hi ghest T-opt.G (23.0 degreesC) and Hb-I(1/1) the lowest (19.0 degreesC). The biological significance of this link between biochemical genetic variation and physiological properties might be influences on growth pattern, ultima te size and age at first maturity. This is the first reported quantitative trait locus (QTL) for this species.