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For endangered Batagur Baska turtles, Sundarban conservation project is reason for hope

The decline of their habitat, threats from predators and the demand for turtle meat have, over the decades, led to dwindling numbers of the Batagur baska, also known as the Northern River Terrapin, in South Asia. A ten-year-long multi-pronged conservation programme in the Sundarbans however, is showing promise.

Written by Neha Banka | Kolkata |
Updated: January 31, 2022 11:41:19 am

Just before Kali and her companions were released into the wild last week by forest officials and conservationists, the ten sub-adult turtles were first taken to a small shrine on the edge of the mangrove forests to be blessed by Bonbini, the guardian deity of the Sundarbans. While turtles are common in this ecosystem in Gangetic West Bengal, this group was special—they were the Batagur baska, also known as the Northern River Terrapin, a critically endangered species that has been saved from going extinct thanks to an extensive ten-year-long conservation programme in the Sundarban Tiger Reserve. 

Some 15 years ago, there was little concern about the conservation status of this species. That changed when Australian zoologist Peter Praschag published a paper indicating that the Batagur baska, or the Northern River Terrapin, found in South Asia were entirely different from the species found in parts of Southeast Asia, which was identified as the Southern River Terrapin. The suggestions in this paper meant that there were no accurate numbers available for the Batagur baska and neither was there any information about their habitat in the India-Bangladesh region.

The Batagur baska is a large river turtle with a carapace or hard upper shell that can grow up to 60 cm in length. This is a photograph of one of the ten sub-adults that were rewilded this past week, tagged with a transmitter. Photo credit: Dr. Shailendra Singh

“Since it was doing okay in Malaysia, Thailand and other parts, it was believed that there was no need to rush to understand the species. But once it was very restricted to certain parts of India and Bangladesh, it was imperative to understand the threats it was facing, the status etc.,” said Dr. Shailendra Singh, aquatic wildlife biologist and programme director of Turtle Survival Alliance in India. 

The Batagur baska is a large river turtle with a carapace or hard upper shell that can grow up to 60 cm in length. In 2007, after Praschag’s paper was published, the Turtle Survival Alliance, a global organisation that engages in captive conservation of freshwater turtles and tortoises, began surveys of the Batagur baska in West Bengal, Orissa and other areas where the species was last recorded. That search led Singh to the offices of the West Bengal Forest Department in Canning, where he found anecdotal reference of this species in documents related to a decades-old breeding programme of the olive ridley turtle that had been conducted by the Sundarban Tiger Reserve in the early 1990s.

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“It said that certain nests of Batagur baska had been found, but it did not say whether they had accidently found those nests and babies or where they were released. Then the entire focus shifted to the Sundarban Tiger Reserve,” said Singh. In all likelihood, these turtles had been released into local freshwater ponds, because they weren’t relevant to the olive ridley breeding programme.

They are a stunning species, Singh said, because they use a variety of ecosystems within the Sundarban tidal region, one that is reminiscent of the hilsa, that does something similar. “They nest near the sea and then come to forage in less saline areas and freshwater. So they use a really large area during their lifecycle— the entire mangrove. They go all the way to the river mouth to nest and then come back to the freshwater area to forage.”

Almost a century ago, their habitat was even larger. The Batagur baska came all the way up to the present expanse of the Kolkata metropolitan area to forage and then travelled back down to the Sundarbans to nest. But a decimation of their habitat and poaching of the species led to a rapid decline in their numbers in the wild.

The Batagur baska in the Sundarbans. Photo credit: Dr. Shailendra Singh

Singh vividly remembers that July day in 2008 when he first found the Batagur baska in the marshy islands of the Sajnekhali Wildlife Sanctuary in the Sundarbans. Standing on an observation tower next to the ranger’s station in Sajnekhali, Singh waited for hours in the afternoon rains for a sighting of the elusive animal. Suddenly, heads began popping up in the water. 

It wasn’t difficult for Singh’s trained eye to quickly identify that the delicate, upturned black snouts that had been surfacing and dipping back into the water belonged to the Batgur baska, but he still wanted to be certain.  

“I was very excited. I came down and told a forest department guard, ‘have you seen the turtle? And he said, ‘no, those must be fishes. I am not aware of any turtles in these ponds’,” recalled Singh. But Singh was certain that the search for the Batagur baska had ended in the ponds of Sajnekhali. “That day, there was no one whom I could share that feeling with; that some of these animals were still surviving.”  

Dr. Shailendra Singh monitors the Batagur baska after the release of the terrapins in the Sundarbans. Photo credit: Dr. Shailendra Singh

Not only were they surviving, but doing so in relatively good numbers in the wild, with eight males, three females and one juvenile—surviving since the 1990s when they had been released into these ponds. Categorised as critically endangered by IUCN’s red list, these Batagur baska formed the start of the conservation programme jointly conducted by Sundarban Tiger Reserve and the Turtle Survival Alliance. 

The discovery of the Batagur baska in the wild was a remarkable one and the state’s chief wildlife warden immediately signed off to initiate a conservation programme for these unique species. “We started breeding the Batagur baska in 2012 and since then we have had 370 of them,” said Justin Jones, deputy field director, Sundarban Tiger Reserve. 

The Batagur baska being released into the wild as part of a conservation programme jointly conducted by the Sundarban Tiger Reserve and the Turtle Survival Alliance. Photo credit: Dr. Shailendra Singh

The programme is spread across a large swathe of the Sundarbans, with the team having dug out freshwater ponds across seven camps of the Sundarban Tiger Reserve for the species to grow and thrive. The Northern River Terrapin in the Sundarbans represent one of the largest colonies of the species in the wild. The release of the ten sub-adults this past week, tagged with transmitters that can last for 18 months, has been a cautious attempt to release them into the wild to measure how well the species is able to cope on its own. 

“Releasing ten would not mean that you are rewilding the whole area with the Batagur baska. This is just an initial release to study their habitat preference, their mating patterns, their range, their preferred salinity levels, their food etc. We have very little data on them. These will be our pioneers from whom we collect data so that we can plan conservation efforts,” explained Jones. 

In addition to predators, human interference is also a threat to these endangered turtles.  One of those threats include the demand for turtle meat, considered to be a delicacy, especially across the border in Bangladesh, a large amount of which is transported from India. “The population has been declining for years and by the 2000s, the decline was so significant that we realised that the species needed support through conservation, breeding and repopulating so that they can survive in the wild,” said Jones. 

Hence last week, when the first batch of turtles were brought to the local Bonbibi temple, hundreds of villagers gathered to watch the priest pray for the turtles’ well-being. That was also a part of the conservation efforts, Singh explained. Engaging the community ensures that accidental or intentional capture of protected species can be avoided, because of work by officials in spreading awareness of the importance of that particular animal. “Once Bonbibi blesses an animal, even locals try to protect it. It is indirect conservation. So if anything gets trapped in the nets, the fishermen know it is a blessed turtle and it needs to be released,” said Singh. 

batagur baska Fishermen in the Sundarbans help release the Batagur baska into the wild as part of the conservation programme. Photo credit: Dr. Shailendra Singh

This rewilding of the turtles is a crucial conservation project for the ecosystem at large. “Turtles play an important role because they are the vultures of the water ecosystem. They remove the dead material, detritus and keep the environment clean,” explained Jones. The Northern River Terrapin also play an important role for the Sundarbans ecosystem at large, because they also function as an indicator of the health of the mangrove system. “They are the best indicators of whether any fluctuations are occurring in the environment. They are definitely a unique freshwater species,” explained Singh.

This ambitious project would involve research over the next 10 to 15 years, with more numbers of the Batagur baska being released in the wild. The team also hopes to expand the programme to become one that would involve transboundary conservation. “The Sundarbans are the last hope for this species. When you see the variety of habitat that this turtle uses, there are very few. So we are also collaborating with Bangladesh,” said Singh. 

“We are trying to understand if international borders can be used for conservation since they are the best protected areas. The Raimangal River between India and Bangladesh is the only freshwater source between these two countries going into the sea,” said Singh, describing the tidal estuarine river in the region. “It might be the last available habitat for this species.” 

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