Molecular evidence indicates the existence of multiple lineages of Sperata species in Indian Rivers

Sperata seenghala (Giant river-catfish) and Sperata aor (Long-whiskered catfish) are commercially important freshwater catfishes of India, belongs to family Bagridae. Due to high nutritional significance and the low number of intramuscular bones, both fishes have considerable demand in South Asian countries. Both of the Sperata species are morphologically close and well adapted to the same habitat. In this study, we have assessed the level of genetic diversity and differentiation of S. seenghala and S. aor in the Ganga River based on the mitochondrial DNA (mtDNA) control region and compared with the other major Indian rivers. We found high haplotypes diversity for both the species in the Ganga. However, it was comparatively low for S. seenghala in Mahanadi and Brahmaputra populations. The phylogenetic and median-joining network strongly indicated the presence of two distinct maternal lineages of S. seenghala from the Ganga river. Interestingly, the genetic differentiation between S. seenghala of Ganga-Brahmaputra was much higher (~25.3%) than the S. seenghala and S. aor (~17%), whereas it was comparatively low between Ganges-Mahanadi (~8.0%). Our finding provided evidence that all the three rivers: Ganga, Mahanadi, and the Brahmaputra sustain a highly diverse and genetically distinct stock of giant river catfish; therefore, all populations should be considered as a different management unit for the protection of stocks. Our findings indicated that Brahmaputra lineages qualify the species level variations. This study can be further used as a reference database for proper lineage identification of S. seenghala and S. aor that could formulate the appropriate conservation and management plans.