An olive ridley turtle, found mainly in the warm and tropical waters of the deep sea, was spotted on the banks of the Rupnarayan river in a pocket of Howrah on Friday afternoon.
The turtle, weighing nearly 40kg, was on Sunday afternoon released into the Bay of Bengal at a virgin beach in East Midnapore.
Foresters and a researcher said it was rare for an olive ridley turtle (Lepidochelys olivacea) to undertake such a long upstream journey to a freshwater site.
Olive ridley turtles, found mainly in the warm and tropical waters of the Indian, Pacific and Atlantic oceans, are among the smallest of sea turtles and have been named after the greenish colour of their shell and skin. "The coast of Odisha in India is the largest mass nesting site for the olive ridley, followed by the coasts of Mexico and Costa Rica," says the website of WWF-India.
"There is no prior record of an olive ridley turtle in Howrah," said a forest official who has served in Howrah for years.
The turtle was found on the banks of Rupnarayan near a village called Mankur, part of Bagnan I block in Howrah, over 55km from the heart of Calcutta.
"Two local youths spotted the turtle. They could not identify the animal. The area is not far from a fishermen's settlement. The two brought a scale from a fisherman and weighed the turtle. It weighed around 38kg, The two men carried the turtle to their village (Mankur)," said Chitrak Pramanik of the Howrah Jela Joutho Paribesh Mancha, a local NGO.
Pramanik was informed about the turtle by the Bagnan police station. He reached the village around 7pm on Friday with three associates. He identified the animal as an olive ridley turtle and informed the forest department. A team from the department reached the village around 9.30pm and took the turtle to the Garchumuk Mini Zoo, around 20km away.
"The turtle had an injury in one of its flippers. It was treated by a team of vets," said a range officer in Howrah.
The turtle's condition improved on Saturday. On Sunday, a forest department team carried the turtle to Junput, a virgin beach near Contai in East Midnapore. The team travelled in a car. "The turtle was kept over a wet sack on the back seat," said Pramanik who accompanied the team.
As the turtle was brought near the water, it walked briskly into the sea and disappeared into the blue.
This newspaper shared the pictures of the turtle with Upamanyu Chakraborty, wildlife biologist and consultant with Turtle Survival Alliance, a global conservation organisation that works to create a planet where tortoises and freshwater turtles can thrive in the wild.
He confirmed that it was an olive ridley turtle. "I have spotted olive ridley turtles in some pockets of Sunderbans. They had moved upstream but were still in brackish water. But travelling upstream and reaching a freshwater habitat like Rupnarayan in Howrah is extremely rare," said Chakraborty.
He also spoke of another possibility. "Someone carrying the turtle might have dumped it there."