University of Georgia researchers have been using DNA analysis to track the reproduction of individual female loggerhead turtles for nearly two decades. And their numbers seem to have stabilized, after the state listed them as endangered in 2006.
But the picture for males is less obvious.
“We have a large database of the females, but we just don’t have good baseline data on the males at all,” UGA senior research scientist Brian Shamblin said.
Nests of many reptiles like sea turtles will produce hatchlings of all the same sex. That’s because temperature determines sex. The warmer the sand or soil, the more likely it is that females will hatch.
But as global warming heats up beaches, this could be a problem. From Australia to Florida, some studies have suggested that almost all hatchlings are female.
“There basically are no male hatchlings being produced anymore at all,” Shamblin said. “Otherwise, in a lot of areas, we really don’t know.”
Beginning this year, Shamblin’s team and the Georgia Department of Natural Resources will visit the state’s barrier islands to count loggerhead males in Georgia, sampling sperm trapped in the yolk of an egg from each nest.
“We’re using those sperm DNA to figure out, you know, who all the dads are that are contributing to these nests,” Shamblin said.
A team from DNR began sampling two weeks ago on Ossabaw Island. The effort will extend along the Georgia coast north to the Carolinas.
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