Evaluation of altitudinal distribution and population dynamics of introduced Brown trout (Salmo trutta) and native Snow trout (Schizothorax richardsonii) in river Asiganga, Uttarakhand (India)

• Published in: Environment conservation journal 2016-06, Vol.17 (1&2), p.161-177
• Main Authors: Thapliyal, Madhu, Bartwal, Madhu, Thapliyal, Ashish
• Format: Article
• Language: English
• Subjects: altitudinal gradient; biodiversity; ecosystem differentiation; Freshwater; Salmo; Salmo trutta; Schizothorax; Schizothorax richardsonii; taxonomical groups
• ISSN: 0972-3099; 2278-5124
• DOI: 10.36953/ECJ.2016.171218

Mountains of Himalaya, with unique topology and geographical regions, are hotspots of biodiversity. Their flora and fauna have been investigated for abundance in species composition and interactions. One of the most important driving forces of ecosystem differentiation is altitudinal gradients that results in changes in species composition. Sometimes, an introduced species can also have a major impact on endemic species if the introduced species can survive in entire altitudinal gradient zone. Our study focuses on this aspect and defines the pattern of altitudinal variation and distribution of Salmo trutta(Brown trout) and native Schizothorax sp.(Snow trout) in river Asiganga (a tributary of Ganges) that originates from Dodital (4400 m). We analyzed population dynamics of both species along altitudinal gradients (2200m to 1100m approximately). The physicochemical parameters of water showed significant variation along the altitudinal gradient. Our study suggests that the population groups of Brown trout are establishing in the lower altitudinal regions of the river Asiganga, and even into the river Ganges, due to their ability to survive in wider range of temperature and availability of food. Usually it is believed that species inhabiting higher elevations are superior competitors at lower temperature while species inhabiting lower altitude are better competitors at warmer temperature. Our study suggests that although altitudinal variations are powerful for species distribution but prey-predator effect and availability of preferred food is also pro-lasting and can have a wider role in distribution of predator fish species.