LAUSR

Abstract Turbot ( Scophthalmus maximus , Linnaeus, 1758) is an important aquaculture species in China, however, selective turbot breeding is restricted because there is no reliable pedigree data. The objective of this study was to evaluate the performance of a molecular relatedness method to estimate genetic parameters for growth traits in turbot. The experimental population consisted of 843 15-month-old turbot from 79 full-sib families produced via fertilization involving 50 sires and 34 dams. Twenty unlinked microsatellite loci in this population were genotyped to calculate their molecular relatedness. Both molecular relatedness and pedigree were used to construct an additive genetic matrix to apply to the same animal model and estimate genetic parameters and breeding value. Thereafter, we compared the accuracy of two estimators by cross validation. Heritability for body weight and length were 0.33 ± 0.15 and 0.24 ± 0.14, respectively, based on pedigree and both were 0.23 ± 0.04 based on molecular relatedness. Genetic correlation and phenotypic correlation were 0.96 ± 0.02 and 0.87 ± 0.01, respectively, based on molecular relatedness and 0.99 ± 0.02 and 0.89 ± 0.01, respectively, based on pedigree. Cross validation revealed that the accuracy of estimated breeding values was 0.85 with pedigree and 0.92 with molecular relatedness. These results suggest that molecular relatedness is a feasible approach to genetic parameter estimation when pedigree information is either inaccurate or absent. Statement of relevance The authors have declared that no commercial aquaculture exists.