A crisis is facing the fish biodiversity present in major tributaries of the Ganga river in the Himalayan region. In four decades, nearly 15 fish species have reached the brink of disappearance from certain segments of Bhagirathi river and it an almost same situation is being experienced in the rivers Bhilangna, Alaknanda and Mandakini. These results were disclosed in the research report presented by zoologist of the Swami Ramtirth Campus of HNB Garhwal Central University of Uttarakhand. The scientists are indicating that climate change is the cause for such a crisis along with fragmentation and degradation of riverine habitat, hindering the free flow of the rivers due to hydro electric dams on the rivers and unscientific exploitation.
According to professor NK Agarwal, the scientist from Swami Ramteerth campus it has been found during the research that around 43 fish species were present during the 80’s which have reduced to only 28 presently in upper Ganga and its tributaries namely Bhagirathi, Bhilangana, Alaknanda, Mandakani and Nandakini among others are also facing similar crisis.
The research done on the subject has indicated that in the area of nearly110 kilometre length of Bhagirathi from Maneri to Koteshwar, one after another, reservoirs have been created for the Maneri Bhali, Tehri, Koteshwar hydroelectric projects due to which the free flow of the river has been hindered and the deep reservoirs have affected the rich fish diversity of the region adversely as they are unable to adapt to these lakes with deep waters.
These rivers before the dam construction were abundant with several species of snow trout, Garra Crossocheilus, Glyptothorax, Pseudecheneis, Barilius etc but these species were adapted to free flowing river and can survived by feeding on algae and microscopic organisms caught in between the stones at the bottom of the free flowing river. However, after lake formation the shallow habitat became extinct and lake bed is sandy and muddy while being devoid of food organisms for fishes. Instead the population of exotic Common Carp species and other deep water, column feeding fish has increased considerably. However, it is a matter of satisfaction that the Mahseer fish native to the area is still thriving in the new environment and is found in abundance. The stocking of the roes of common carp in the reservoirs should be avoided for the propagation and development of Golden Mahseer designated as State fish of Uttarakhand.
Professor Agarwal has the view that it is imperative that the state government should promote the area for Mahseer fish culture. The areas for the natural breeding sites of Mahseer should be identified and protected as critical habitat for the fish. Tehri lake should be promoted as major tourist attraction for the tourists for angling of famous game fish- the Golden Mahseer. With the development of Mahseer conservation center it would lead to employment generation for the unemployed youth and fulfill the demand for the fish protein along with tourism promotion and state income.
Friday, 20 November 2020 | Vinod Chamoli | New Tehri
