Upstream and Cornered: How Invasive Brown Trout Are Displacing Himalayan Snow Trout
A study published in the Journal of Applied Ecology, co-authored by Dr. Aashna Sharma and researchers from the Wildlife Institute of India and Panjab University, reveals the alarming impact of exotic brown trout on native Himalayan snow trout populations. Introduced during British rule and widely promoted for sport fishing and culinary value, brown trout have become highly invasive, forcing snow trout into sub-optimal headwaters.
The study uses intensive field surveys and geostatistical network models across the Asiganga (Uttarakhand) and Tirthan (Himachal Pradesh) watersheds. Results show that snow trout, which prefer mainstem river habitats, are now spatially fragmented and pushed upstream—where habitat conditions are inadequate for their full lifecycle. The outcome: increased competition, declining distribution, and possible local extinctions.
Researchers urge a halt on damming Himalayan headwaters, which serve as critical last refuges for native fish. Snow trout—already a keystone species due to lack of data on other natives—must be prioritized for conservation to protect the entire Himalayan aquatic ecosystem from cascading biodiversity loss.