The estimated population of the saltwater crocodile in the Sundarbans is between 220 and 242, according to the 2025 census.
This is an assessment of the population trend, not the exact number, a forest department official said.
The 2024 count had put the number between 204 and 234. The 2024 survey took place 12 years after the previous one. The previous one, in 2012, had estimated around 140 crocodiles, the forest official said.
The report of the Population Assessment and Habitat Ecology Study of Saltwater Crocodiles in Sundarbans 2025 was published on Monday.
The largest and heaviest living reptile in the world, the saltwater crocodile (Crocodylus porosus), is an apex predator and key indicator of the health of the mangrove ecosystem.
The census was conducted over three months, from December to February. Three days from each month were devoted to the exercise, said officials. Teams on boats scanned the delta for direct sightings and indirect signs. Trap cameras were installed inside the mangroves, and several photographs of the crocodiles were captured.
“Of the 1,800km of length of creeks in Sundarban Biosphere Reserve, the exercise covered around 1,168km, which is more than 64 per cent of the total creek length of significance (high tide width till 200m) in the forested areas,” the report said.
The biosphere reserve includes the Sundarban Tiger Reserve and the South 24-Parganas Forest Division.
“Total direct sighting along the transect length of 1,168 kilometres was 213 for the whole of Sundarban Biosphere Reserve (SBR). The estimated number of saltwater crocodiles in the Indian Sundarbans is between a minimum of 220 up to 242,” said the report.
The encounter rate of saltwater crocodiles in the Sundarbans is around 0.18 per kilometre, or around one saltwater crocodile per 5.5km.
Apart from direct and indirect sightings, the exercise captured data on salinity, surface water and ambient temperature that the crocodiles preferred for basking; creek widths and other parameters.
The crocodiles preferred high tide creek width between 10 and 130 metre and a salinity range between 10-23 PPT (parts per thousand), the report said. The preferred ambient temperature for basking was between 20-30 degrees Celsius in winter.
The survey took into account adults and juveniles. Hatchlings were sighted but were not counted. There is little chance of a crocodile being counted twice because, like tigers, crocodiles are territorial, said a forest official.
Climate change is a major threat to the apex predator, the report said.
The head of forest force in Bengal, Debal Roy, and the director of Sundarban Tiger Reserve, Rajendra Jakher, were present at the launch.