IWN Daily Digest — Friday, 23 October 2026

Migratory freshwater fish have declined by 81 per cent worldwide since the 1970s, and a commentary from India’s Himalayan headwaters argues that dams and village rules there will decide whether the survivors still have a river to travel.

As Mongabay India reported in a commentary:

“Migratory freshwater fish populations have dropped 81% globally since the 1970s. Nearly all (97%) of the 58 fish species listed under the convention now face extinction.”

The figures come from the Global Assessment of Migratory Freshwater Fishes, published earlier this year by the UN Convention on the Conservation of Migratory Species of Wild Animals and drafted with the UN Environment Programme-World Conservation Monitoring Centre. The report names the Ganges-Brahmaputra-Meghna river system as a global priority region, and lead author Zeb Hogan, a fish biologist, describes the basin as among South Asia’s greatest migration landscapes.

Writing the commentary, Saurabh Dewan, a freshwater biologist and founder of the Himalayan Conservancy Foundation, says public debate over the basin usually stops at barrages such as Farakka, while the damage is worse far above the plains.

In the Indian Himalayan headwaters, he writes, the Tehri dam complex on the Bhagirathi river and the Srinagar dam on the Alaknanda river are both impassable to fish. The golden mahseer, which can grow to over 50 kilograms, features in his account through radio telemetry research by the Wildlife Institute of India, which he says demonstrated how rapid hydropower development has broken the species’ habitat into fragments and changed its ecology and spawning biology.

Village Rules

Dewan’s examples of what works come from villages. In Meghalaya’s Garo Hills, the Wachi Wari Community Fish Sanctuary on the Simsang river protects deep pools called wari, where fish gather when water levels drop, and he writes that these pools host hundreds of rare chocolate mahseer.

Further east, along the Tepuiki river in Nagaland, residents of Poilwa village mapped eight spawning grounds along a seven-kilometre stretch and protected them. Fishing and extraction were barred in the breeding zones, and Dewan writes that native fish recovered within a few seasons, with household incomes following.

He calls for the remaining free-flowing, undammed Himalayan stretches to be strictly protected as fish conservation zones, and for adequate and seasonally appropriate environmental flows at existing dams to be legally mandated and enforced.

Sources: Mongabay India

India Wildlife News aggregates wildlife stories from across Indian media to bring the latest from the field to enthusiasts, conservationists, and curious readers — all in one place. Full credit and links to original sources are provided. We encourage readers to visit and support the original publishers.