Conservationists have expressed alarm over the low number of turtles arriving on the coast of east India and Bangladesh for the nesting season, blaming overfishing and climate change for the decline.
Between November and March, several species of sea turtle, including the Olive Ridley, travel thousands of miles to nest on the sandy shores of Sundarbans, the world's largest mangrove forest.
"Just a few have so far been spotted. The long, wide beaches of the Bay of Bengal in the Sundarbans look empty," Pradip Vyas, director of the Indian government's Sundarbans Biosphere project, told AFP on Thursday.
"We are monitoring the six islands where sea turtles lay their eggs but we fear they are not coming in such numbers due to degradation of the sea, pollution and climate change."
Straddling Bangladesh and India, the 10,000 square kilometre (3,900 square mile) Sundarbans is famous for being the largest wildlife home for endangered Bengal tigers, but it is also a habitat for many rare marine species.
In Bangladesh, which is home to 60 percent of the forest, wildlife experts said the number of turtles arriving on the pristine coastline dropped by at least 50 percent in the past 10 years.
"It's a very grim picture," said S.M. Rashid, head of the Dhaka-based Centre for Advanced Research in Natural Resources and Management.
"In the 1990s we could spot 50-60 turtles nesting in our beaches in a night.
"But now the number has come down to a maximum 10," said Rashid, whose team in June successfully bred a critically endangered turtle using an artificial beach habitat.
Environmentalists blame a spike in fishing and climate change causing sea levels to rise and more cyclones for the alarming drop in turtle population, and they say that humans stealing eggs is another major problem.
"Overfishing has emerged as a threat to sea turtles coming to beaches of the Sundarbans," said Subrata Mukherjee, India's senior Sundarbans official, adding up to 1,500 boats now catch fish along the coast.
"A large number of sea turtles die after they are caught in fishing nets."
In the last five years, the Sundarbans were hit by two devastating cyclones, killing more than 5,000 people living in the villages along the forest.
"The nesting grounds of the marine turtle are being destroyed due to erosion and deposition of fresh sands. This is happening largely because of climate change," said Anurag Danda, an Indian WWF wildlife expert.
"Sea turtles are also avoiding the Sundarbans because of fierce winds during cyclones."