Loss of genetic diversity among pirarucu broodstocks in fish farms: a pilot study

Molecular markers can be used to monitor genetic variability in cultivated fish stocks with the aim of developing better aquaculture techniques and increasing productivity. Our objective was to evaluate genetic variability in pirarucu broodstocks in fish farms in the southeast and northeast of Pará state, Brazil. The samples were genotyped using four microsatellite markers, and genetic diversity indices were calculated for each broodstock. A total of 16 alleles were identified from the four loci tested in the 33 pirarucu samples, with means of 3.00, 2.75, and 2.25 alleles per locus in broodstocks from Tucumã, Parauapebas, and Moju municipalities, respectively. The Parauapebas broodstock had the highest mean observed heterozygosity. In the broodstocks from Tucumã and Parauapebas, the markers AgCAm16 and AgCAm18 were not at Hardy-Weinberg equilibrium. We can suggest that there were considerable losses of genetic variability in the pirarucu breeding centers of the municipalities of Tucumã, Parauapebas and Moju, compared to natural populations.