On 19 January 2022, the Turtle Survival Alliance and Sundarban Tiger Reserve of West Bengal Forest Department, India, released 10 subadult northern river terrapins Batagur baska into a tidal river in Sundarban Tiger Reserve. This group of terrapins, c. 9 years old and comprising seven females and three males, is the first monitored return of the species to the wild in India. The terrapins are offspring of 12 founder animals discovered in 2008 in a pond at the Sajnekhali Range Station within Sundarban Tiger Reserve.

The northern river terrapin, formerly native to India, Bangladesh, Myanmar and Thailand but now extant only in India and Bangladesh, and with three females in temple ponds in Myanmar, is categorized as Critically Endangered on the IUCN Red List. The Turtle Survival Alliance and its partners estimate that < 20 adult terrapins may survive in the wild across the vast expanse of the Sundarbans spanning south-east India and south-west Bangladesh. As human settlement of the Sundarbans increased, the wild population declined as a result of unsustainable collection of adults and eggs for food.

In 2012, in a joint initiative of Sundarban Tiger Reserve and the Turtle Survival Alliance, the founder animals were entered into a conservation breeding initiative, with the first successful reproduction of 33 hatchlings occurring that year. The 10 subadults released in 2022 were selected from > 370 individuals hatched through this programme. The programme has worked with governmental agencies to obtain permits and engage communities within the Sundarbans in educational initiatives on the importance of the return of this terrapin to the wild. Prior to release, in the presence of hundreds of citizens, the 10 terrapins were ceremoniously blessed by a priest at the temple of Bonbibi, the forest goddess of the Sundarbans, to create a cultural connection for the return of the terrapins.

The Sundarbans is a 10,000 km² mosaic of tidal rivers and mangrove forests. Through knowledge gained from previous releases of B. baska by the Turtle Survival Alliance's partners Zoo Vienna Schönbrunn and Bangladesh Forest Department in Bangladesh, we expect the 10 terrapins to make considerable movements through this ecosystem. The Turtle Survival Alliance's India staff will monitor post-release animal movement and survival via satellite transmitters fixed to the shell of each turtle, as well as through trained, licensed fishers who will report the location and condition of any turtles captured incidentally. Integrating local fishers and riverside communities is a fundamental component of the Turtle Survival Alliance's approach for other at-risk species in India, and the use of satellite transmitters marks the first time this method has been used for a non-marine turtle in the country.