Genetic and environmental variances on growth and reproductive traits of silver crucian carp Carassius langsdorfii using communal and separate rearing systems

Five clonal lines of silver crucian carp Carassius langsdorfii were produce d from natural maternal fish to estimate the variance and heritability of t otal length, bodyweight and gonadosomatic index (GSI). The larvae on the 10 th day after hatching were reared together in a common rearing system with five duplicate systems. Another system was prepared using a separate system with two replications in each family. Estimation of variance and heritabil ity were done in the first, third, fifth and 10th month for total length an d bodyweight. Microsatellite DNA markers were used to identify the clonal l ines in each communal rearing tank. Average heritabilities in the first mon th were 0.105 for total length (ranging from 0.21 to 0.03) and 0.127 for bo dyweight (ranging from 0.22 to 0.06) then decreased in the third, fifth and 10th month. In contrast, intermediate levels of heritability from separate systems were observed. Likewise, relative heritability of GSI in the 10th month presented a high level in both rearing systems. Those heritabilities indicated that growth, total length, bodyweight and reproductive performanc es of silver crucian carp were affected by genetic influence. The results s uggest that clonal lines of silver crucian carp are suitable as experimenta l animals for evaluations of environmental change and various pollutants th rough quantitative traits such as growth, reproductive and other physiologi cal traits.