Assessment of genetic diversity in wild and hatchery populations of mrigal Cirrhinus cirrhosus (Hamilton Buchanan) using allozyme markers

Abstract

Allozyme markers were applied to elucidate the genetic structure of three rivers (viz. the Halda, the Jamuna and the Padma) and three hatchery (Brahmaputra, Raipur and Sonali) populations of mrigal (Cirrhinus cirrhosus). Electrophoretic analysis of twelve enzymes revealed a total of 20 loci of which four were polymorphic (P95). Compared to the hatchery populations, the average observed and expected heterozygosity were higher and the inbreeding coefficients were lower in the river populations. Significant deviations from Hardy-Weinberg expectation were observed in 16.67% cases. The population pair-wise FST values were low (0.0095-0.0719) to moderate but mostly significant. The number of families and effective population sizes were higher in the river group compared to the hatchery group. Since the level of inbreeding in the hatchery population is high, it is advisable to make periodic renewal of the hatchery broodstocks with fish from relatively better river sources.