‘Fish ladders’ planned at Yamuna to revive native species

The Upper Yamuna River Board (UYRB) has asked Delhi, Haryana and Uttar Pradesh to develop “fish ladders” at the Wazirabad, Okhla and Hathnikund barrages to facilitate the migration of native fish species, during a meeting on Tuesday, a senior official said on Wednesday

The Upper Yamuna River Board (UYRB) has asked Delhi, Haryana and Uttar Pradesh to develop “fish ladders” at the Wazirabad, Okhla and Hathnikund barrages to facilitate the migration of native fish species, during a meeting on Tuesday, a senior official said on Wednesday.

According to a Central government survey conducted between 2020 and 2024, a total of 126 fish species were recorded along the Yamuna from Yamunotri to Prayagraj. (RAJ K RAJ /HT PHOTO)

A fish ladder is a stepped water structure that helps fish bypass obstacles such as dams and barrages during their upstream migration. “All basin states have been asked to develop fish ladders on barrages under their control. This is likely to help movement of fishes especially during the monsoon when the river is less polluted,” said the official, who did not wish to be named.

Three different states oversee all three barrages located in Delhi. “Delhi only manages the Wazirabad barrage, ITO comes under Haryana and Okhla is managed by the Uttar Pradesh government,” the official said.

According to a Central government survey conducted between 2020 and 2024, a total of 126 fish species were recorded along the Yamuna from Yamunotri to Prayagraj.

Following the survey, the National Green Tribunal (NGT) ordered Delhi and other states along the Yamuna to restore native fish populations and control the presence of exotic species in the river as a priority.

Last July, the fisheries department under the Centre reported that a mix of factors, including competition for water, dams, habitat alteration, and water pollution, is likely behind a decrease in native fish species and a rise in exotic species.

“Dam construction, in particular, fragments major rivers and blocks essential fish migration routes, preventing species from reaching spawning grounds and leading to local extinctions. Poor water quality, due to pollution and other contaminants, poses a major threat to aquatic life. Additionally, overexploitation, indiscriminate harvesting, and the use of illegal fishing gear contribute to the decline of fish stocks. The encroachment of riverine land and climate change also exacerbate the challenges faced by native fish species,” the report said.

The report said exotic species have likely been introduced into the river through aquaculture escapes or pet releases.

A national committee to oversee and regulate the introduction of exotic aquatic species in Indian waters was first constituted in July 1996 by the Centre. Subsequently, the cultivation of exotic magur (Clarias gariepinus) and Bighead Carp (Hypophtalmichthys nobilis) was prohibited in the country from 1997.

The Yamuna stretch between Wazirabad and Okhla is highly polluted, especially during the non-monsoon season, when the areas between these barrages resemble sewage pools due to a lack of freshwater inflow. “There are a series of schemes being pushed by the Central government to improve the e-flow and improve quality of treated water being released in the river. Once the river is relatively cleaner over the next 2-3 years, the water will also be able to support the fish population,” a second official said.

Other measures mandated by the NGT include banning juvenile fishing and illegal gear such as mosquito drag nets, strengthening monitoring during fishing ban periods, maintaining proper records of fish catch data, and strategic ranching of native species -- Mahasheer in upper stretches, Indian Major Carps and other commercially important species in middle and lower stretches, and air-breathing fish in designated sections of the Delhi stretch.