Population genetics of Indian giant river-catfish, Sperata seenghala (Sykes, 1839) using microsatellite markers.

Abstract

The giant river-catfish Sperata seenghala is one of the commercially important freshwatercatfishes of India with wide distribution in all major rivers and reservoirs. This fish has huge demand indomestic market due to high nutritional value and low number of intramuscular bones. Conversely, theculture practices for this fish have not yet been standardized and capture fisheries is the only source to meetthe demand. This may lead to over exploitation of resources and subsequent population reduction.Knowledge on genetic structure of populations is prerequisite to formulate sustainable management andconservation measures. In the present study, 15 microsatellites were used to characterize populationgenetics of S. seenghala collected from river Brahmaputra, Ganga, Godavari, Mahanadi and Narmada.Locus-wise, the number of alleles varied from 8 to 19 with an average of 12 alleles per locus. The meanobserved and expected heterozygosity values varied from 0.622 to 0.699 and 0.733 to 0.774, respectively.Several loci have shown deviation from Hardy–Weinberg equilibrium and no significant linkagedisequilibrium between pairs of loci was detected. Pair-wise FSTvalues between populations ranged from0.135 (Brahmaputra–Ganga) to 0.173 (Brahmaputra–Narmada) and confirmed the moderate to highgenetic differentiation among the populations. AMOVA, Structure and Principal Co-ordinate analysesshowed significant genetic differentiation among the sampled populations of S. seenghala. A total of65 private alleles were recorded across populations. This study confirmed the distinctiveness of eachpopulation of S. seenghala from five major rivers of India. These populations could be treated as distinctmanagement units (MUs) for assessment and management purpose