Morphological Divergence of Snow Trout (Schizothorax Richardsonii, Gray 1932) from Rivers of Nepal with Insights from a Morphometric Analysis

Abstract

Asala or snow trout (Schizothorax richardsonii, Cyprinidae), one of highly valued freshwater fish of Transhimalayan regions, is distributed in upper reaches of all major river systems of Nepal. Morphometric diversification between six river populations of S. richardsonii was examined to identify intraspecific unit for enabling better management of the resources. Significant differences were observed in 17 measured morphometric characters of 207 specimens among the six river populations. Multivariate analysis of variance (Wilks' test) indicated a significant difference for mean vectors of mophometric measurements (? =0.012, F85, 731 = 19.999, P<0.0001) among populations. Principal component and discriminant functions (DFs) analysis of morphometric measurements revealed high seperation of the stocks. The analysis showed that most of the shape and size variation among these populations occurs in the head region, body depth and fin length. Apparent morphometric divergence among S. richardsonii samples showed the existence of three differentiated groups viz., the Indrawati and Khudi populations, the Melamchi and Phalaku Rivers, and the Sabha and Tadi River populations of Nepal. The results of this study may be useful in fisheries management and potential exploitation of this species in coldwater aquaculture.Int J Appl Sci Biotechnol, Vol 3(3): 464-473

Integrative approach for validation of six important fish species inhabiting River Poonch of north-west Himalayan region (India)

“…Only slight differences in the shape and size of the ceratohyal and epihyal were noted, with the epihyal of S. richardsonii being smaller than S. plagiostomus. Other similar observations regarding the morphological variations were noted by Wagle et al (2015) , who reported that for S. richardsonii , all the parameters were undoubtedly interrelated with total length and head length; the current study also obtained similar results ( Figures 5A,B ). Thus, it is concluded that the anal fin length and lips resolve the phenotypic problem of differentiating between these two species.…”

“…The number of inferior pharyngeal teeth in both species was the same (4, 3, 2/2, 3, 4). A lot of work has been reported favoring the current results (Misra et al, 1980;Negi and Negi, 2010;Mir et al, 2013a;Wagle et al, 2015;Wani et al, 2018;Kamboj and Kamboj, 2019). Misra et al (1980) revealed that both S. richardsonii and S. plagiostomus had the same number of teeth.…”

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

“…also reported significant differences (p<0.05 or <0.001) in four (Maximum Body Height, Pre-orbital Length, Peduncle Length and Maxillary Barbel Length) of 9 morphometric variations in Labeo calbasu populations collected from the Jamuna, the Halda and a hatchery in Bangladesh. Many other authors have also reported similar results like Parvej et al (2014) in Eutropiichthys vacha; Siddik et al (2016) in Sillaginopsis panijus; Wagle et al (2015) in Schizothorax richarsonii and Esmaeili et al (2011) in Alburnoides qanati. Fagbuaro et al (2015) reported significant differences in Clarius gariepinus from Nigeria; differences were attributed to food, environmental conditions and type of habitat.…”

Rheotaxis Response Based on Sexual Dimorphism in the Green Swordtail Fish, Xiphophorus hellerii

“…Morphological adaptation of stream fish is mostly on the locomotion part, consisting of a variation on the abdominal shape, caudal regions, and fins (Shuai et al, 2018;Hanif et al, 2019). The slender body of stream fish is crucial to enhance the ability to swim against the stream (Mu et al, 2019;Wagle et al, 2015). Dunn et al (2020) reported population morphological variations of Galaxias brevipinnis, Galaxias gollumoides, and Galaxias Vulgaris in lotic habitats have a slender body to their lentic-habitats counterparts.…”