For an animal that’s been managed as an endangered species for more than three decades, the loggerhead is one mysterious sea turtle.
Researchers can’t really say how many are out there — the hatched turtles spend their lives at sea and only females come ashore to nest. The only known numbers have been the nest counts, and nobody has a solid explanation why nesting numbers can vary so widely year to year — literally by the thousands. Both are critical data for managers trying to judge decline or improvement. The only real data comes from the nest counts.
That’s how important the turtles’ “fingerprints” are, and that’s why the unprecedented genetics DNA fingerprinting study underway at the University of Georgia just won a $1.3 million grant to keep going.
Researchers Joe Nairn and Brian Shamblin are taking DNA testing samples from nest egg shells in South Carolina, Georgia and North Carolina. So far, the three-year-old study has taken samples from more than 8,000 nests, working with state wildlife biologists and volunteer turtle groups.
With the next three years of funding, the researchers hope to identify virtually every nesting female in the region, Nairn said.
The turtles, which were thought to lay multiple nests every two or three years, have been shown to be widely more individual. Some nest every year but lay only one nest. Some nest as rarely as every four or five years. A few have been shown to lay nests in each of the three states in a single year.
“We’re starting to learn all these things we didn’t know, when it comes to individual turtles,” Nairn said.
With a full inventory of females, the research would have the baseline to identify new nesting females — the first real population restoration data.
The study is of tremendous importance to S.C. Department of Natural Resources conservation of the turtles, said Michelle Pate, marine turtle conservation program coordinator. It “will help us to better understand population dynamics,” she said.
Since the turtles were put on the federal endangered species list in the 1970s, the numbers of Atlantic nesting turtles generally were thought to be in severe decline in Florida, where the overwhelming bulk of nests are laid, and a more gradual decline in South Carolina, where the most nests outside Florida are laid. The states are the two largest-by-numbers nesting grounds in the world for loggerhead turtles.
Nesting in South Carolina has appeared to be on the increase, but researchers pay closer attention to key “index” beaches, where the monitoring has been consistent for a longer period of time.
Those numbers have been spottier, but also appear to be increasing in recent years.
Reach Bo Petersen at 937-5744, @bopete on twitter or Bo Petersen Reporting on Facebook.
A loggerhead sea turtle makes her way back to the ocean early morning on July 17. Photo by Betty Tarnowski×
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