DNA microsatellite-based evaluation of early growth performance among strains of freshwater prawn Macrobrachium rosenbergii de Man

Microsatellite DNA markers were used to assess early growth performance among different strains of freshwater prawn under separate and communal rearing conditions. Two-hundred-and-twenty broodstock individuals from three prawn strains were collected and used as baseline populations for assignment tests. The exclusion-simulation approach was performed on different sets of one to seven microsatellite loci to determine the power of the assignment test. High accuracy of the test was obtained by using seven loci, with 90% correct assignment of individuals (P < 0.05). Simulations suggested that the use of four loci would substantially reduce the number of genotypes needed and the associated cost of genotyping while maintaining high assignment scores (88%, P < 0.05). The power of the assignment test was highly dependent on the degree of population differentiation (FST). Results of this study demonstrated that an assignment score of 100% was obtained when FST > 0.1. Post-larvae of the three baseline populations - including a commercial strain of foreign origin, a local hatchery strain and a wild population - were stocked in separate and communal tanks and cultured for 120 days. Significant differences in growth were observed among strains in both separate and communal rearing, with the commercial strain outperforming the hatchery populations. While communal rearing was proven an effective technique for comparing the growth of juvenile fishes, the approach may not be applicable for comparing the survival of juvenile prawns due to their cannibalistic nature.