Multivariate morphometric study for species differentiation in two congeneric schizothoracids, Schizothorax niger Heckel 1838 and Schizothorax esocinus Heckel 1838 from River Jhelum Kashmir

Abstract

Principal component and discriminant analyses were used to investigate morphological differences between Schizothorax
niger Heckel 1838 and Schizothorax esocinus Heckel 1838 from River Jhelum, Kashmir, India. The purpose of this study
was to identify the two species correctly and assign them into distinct genetic groups. Seven morphometric measurements
(body weight, standard length, total length, head length, body depth, pre-dorsal length and caudal fin length) were studied
in 100 fish specimens. All the studied morphometric characters reported higher mean values (p<0.01) in S. niger. The use
of multivariant techniques such as principal component analysis, showed that the differences between the species resulted
mainly from body weight, standard length, pre-dorsal length, head length, total length and caudal fin length. The stepwise
discriminant analysis revealed that morphometric traits namely, standard length, pre-dorsal length and caudal fin length
were the three most important variables to clearly distinguish the two species. Cross validation test using leave-one-out
procedure indicated that 89% original grouped cases correctly classified into their groups, whereas 89% of cross validated
grouped cases were correctly classified.
Keywords: Fish stocks, Morphology, Schizothorax, Snow trout, Variation