"Sea turtles have been around about 100 million years and survived the extinction of the dinosaurs but are struggling to survive the impact of humans," said reproductive biologist Thane Wibbels of the University of Alabama at Birmingham (UAB), a member of a research team studying the fate of these reptiles.

The leatherback — the world's largest turtle — can grow to six feet long and weigh as much as 2,000 pounds.

A study published this week in the Ecological Society of America's scientific journal Ecosphere estimates that only about 500 leatherbacks now nest at their last large nesting site in the Pacific, down from thousands previously. The study tracked the turtle's ongoing population decline since the 1980s.

"If the decline continues, leatherback turtles will become extinct in the Pacific Ocean within 20 years," Wibbels said.