Heritability estimation of silver carp (Hypophthalmichthys molitrix) harvest traits using microsatellite based parentage assignment

Silver carp accounts for the largest biomass production of any finfish aquaculture species in the world. In spite of its great importance as an aquacultural species, very little is known about the genetic parameters of its commercially important traits. As an initial step towards developing a selective breeding programme, heritability of harvest weight and length was estimated for a silver carp stock maintained in the NFRDMP (North West Fisheries Resource Development and Management Project) hatchery in Bangladesh. Three sets of partial factorial matings were performed (12 sires and 12 dams in each set) to produce full- and half-sib families for this study. Offspring from all families produced in a set were reared communally for six months and then weighed and measured upon harvesting. Ten silver carp microsatellite markers were included in two multiplex PCR systems and were used to assign parentage to the individuals. Out of 331 offspring, 96.3% could be assigned to a single family. Statistical analyses to partition the variance components for weight and length data were carried out by the REML (Restricted Maximum Likelihood) method. Heritability for harvest weight was estimated to be 0.67 (confidence interval: 0.42–0.93) and for harvest length 0.51 (confidence interval: 0.29–0.78). Despite the limited sample size, the moderate to high heritability estimates suggest that this population should respond rapidly to selective breeding for increased harvest size. In addition to this first report of quantitative genetic parameters in silver carp, this paper also describes two novel multiplexes of silver carp microsatellite markers for parentage assignment and discusses the effects of the partial factorial mating design in maintaining effective population size in this species.