An international team led by the University of Alabama at Birmingham (UAB) has documented a 78 percent decline in the number of nests of the critically endangered leatherback sea turtle in the Pacific Ocean. The experts fear, if the trend continues, the turtles may become extinct in the next 20 years.
In a study published on Feb 26 in the Ecological Society of America’s scientific online journal Ecosphere, scientists noted the decrease in number of nests of the endangered turtle.
The researchers observed the nests in Jamursba Medi Beach in Papua Barat, Indonesia — which accounts for 75 percent of the total leatherback nesting in the western Pacific. They found that compared to 14,455 in 1984 the numbers had plummeted to just 1532 in 2011. Less than 500 leatherback turtles now nest at this site.
The researcher team included members of UAB, State University of Papua (UNIPA), the National Oceanic and Atmospheric Administration (NOAA), National Marine Fisheries Service and the World Wildlife Fund (WWF) Indonesia.
Thane Wibbels, Ph.D., a professor of reproductive biology at UAB and member of a research team said,
“If the decline continues, within 20 years it will be difficult if not impossible for the leatherback to avoid extinction. That means the number of turtles would be so low that the species could not make a comeback.”
“The leatherback is one of the most intriguing animals in nature, and we are watching it head towards extinction in front of our eyes,” added Wibbels.
Leatherback turtles can grow to six feet long and weigh as much as 2,000 pounds. They are able to dive to depths of nearly 4,000 feet and can make trans-Pacific migrations from Indonesia to the U.S. Pacific coast and back again.
Ricardo Tapilatu, the research team’s lead scientist says the reason for the extinction threat of such a large turtle is the trans-pacific migration where they are frequently captured and killed during fishing.
“They can migrate more than 7,000 miles and travel through the territory of at least 20 countries, so this is a complex international problem,” Tapilatu said. “It is extremely difficult to comprehensively enforce fishing regulations throughout the Pacific.”
The team discovered thousands of nests laid during the boreal winter just a few kilometers away from the known nesting sites, but their excitement was short-lived.
“We were optimistic for this population when year round nesting was discovered in Wermon Beach, but we now have found out that nesting on that beach appears to be declining at a similar rate as Jamursba Medi,” said Dutton, co author of the study.
The extensive research was carried out from 2005 till 2011 and the team found four major problems the turtles were facing – nesting beach predators, such as pigs and dogs that were introduced to the island and eat the turtle eggs; rising sand temperatures that can kill the eggs or prevent the production of male hatchlings; the danger of being caught by fisheries during migrations; and harvesting of adults and eggs for food by islanders.
Tapilatu, a native of Papua Indonesia has worked to educate the locals about stopping egg harvesting. His primary goal now is to save the females, protect the nests and the eggs.
A leatherback lays up to 10 nests each season, more than any other turtle species.
The conservationist has planned an extensive beach management program that would reduce exposure of the egg to heat and predators.
“If we relocate the nests from the warmest portion of the beach to our egg hatcheries, and build shades for nests in other warm areas, then we will increase hatching success to 80 percent or more,” said Tapilatu.
“The international effort has attempted to develop a science-based nesting beach management plan by evaluating and addressing the factors that affect hatching success such as high sand temperatures, erosion, feral pig predation and relocating nests to maximize hatchling output,” said Manjula Tiwari, a researcher at NOAA’s Southwest Fisheries Science Center in La Jolla, Calif.
Wibbels says that optimising the number of hatchlings emerging out of the eggs is a good survival idea, especially considering the limited number of hatchlings who survive to adulthood.
“Only one hatchling out of 1,000 makes it to adulthood, so taking out an adult makes a significant difference on the population,” Wibbels said. “It is essentially the same as killing 1,000 hatchlings.”
The team also believes that good beach management will reduce the decline in their nest numbers in the coming years. They hope that along with this, the slautering of the turtles trans pacific is also stopped so that these giant sea-faring animals can have a safer future.