Morphometric Assessment of Golden Mahseer Populations in the Ganga River Basin, India

River fragmentation has adverse effects on fish populations due to restricted migratory pattern, resulting in risk of population extinction. It has been hypothesized that river fragmentation has led to changes in fish population structure. To test the hypothesis, 149 Golden Mahseer Tor putitora were collected from seven locations, including the Ganga River and upstream and downstream of two impounded headwater tributaries: the Bhagirathi and the Alaknanda rivers. Landmark-based "Truss" and "Geometric" morphometric differentiation was investigated to determine if variations in Golden Mahseer populations exist due to river impoundments. Truss network modeling yielded 90 size-corrected distance variables from 14 landmarks, following which analysis of variance (ANOVA), principal component analysis (PCA) and discriminant function analysis (DFA) were performed. Geometric morphometric modeling included relative warps, PCA, and canonical variate analysis (CVA). Both DFA and CVA plot illustrated overlapping, with DFA suggesting low percentage of classification between populations. Mahalanobis and Procrustes distances extracted from CVA were non-significant (P > 0.001) among populations. Results indicated the existence of single homogenous population of Golden Mahseer in the Ganga River. This study provides a basis for stock identification useful in developing a suitable plan towards conservation and restoration of Golden Mahseer populations in the fragmented Ganga River.