Taxonomy, distribution, biology and conservation of vulnerable snow trout Schizothorax richardsonii (Actinopterygii: Cyprinidae: Schizothoracinae) in the Himalayan and sub-Himalayan region: A review

Fish are a significant component of the aquatic environment and are crucial in supporting and maintaining the entire ecological system, thereby making freshwater systems more resilient and sustainable. The structure of a fish community is influenced by biotic interactions and abiotic variables. In recent years, spanning from the last 5 to 10 years, conservationists and commercial fishermen have reported a significant decline in freshwater fisheries. The decline can be attributed to several factors, including the introduction of exotic species, construction of dams, anthropogenic activities, illegal fishing, and overfishing. Schizothorax richardsonii, is a highly valued freshwater fish, inhabiting the foothills of the Himalayan regions. The declines of S. richardsonii in the Himalayan region are more than 90% in some areas and the predicted overall reduction is inferred to be around 50% with similar rates. Withstanding all the variations in biotic and abiotic factors, the species is expanding its range of altitude and evolving according to the climate-driven shifts in the Himalayas and apparently, its current distributional range would be lost over time. In Indo-Himalayan ranges, there is a lack of conservative measures and as a result, despite its ecological importance, snow trout has been given a vulnerable status by IUCN 2020. This review aims to provide descriptive biology and discuss the anthropogenic impact on the population structure of snow trout and its conservation.