Currently on the endangered species list, leatherback sea turtles have slowly been increasing in number along the Florida shoreline, according to a recent Duke study.
The study—published in the current issue of Ecological Applications—found that turtle nestings have increased steadily by 10.2 percent each year since 1979.
“We did not know a lot about the leatherback population in Florida and they are critically endangered worldwide,” said Kelly Stewart, who received her Ph.D. from Duke in 2007 and is the lead author of the study. “One of the government’s functions is to make sure [Florida has] a recovery plan in place for endangered species so the topic I picked to study tried to answer some of the questions in that recovery plan.... The answers could contribute to future management of turtles.”
Stewart said data was collected every day of the nesting season, the period when turtles lay their eggs, from about 100 different sites on Florida beaches, adding that she drew her conclusions from a compilation of all the nest counts.
One of the primary challenges for the study was the variability of historical data for all the different survey areas.
“Some beaches had been surveyed for ten or fifteen years, some had been surveyed for only five, and some had been surveyed for 30 years,” Stewart said. “We had to figure out a way to incorporate beaches that had only been surveyed for a few years as well as those beaches that had been surveyed for a long time.”
Over the last several years, there had been an influx of unofficial reports saying that the leatherback turtles were returning to the Sunshine State.
“People were seeing [leatherback turtles] more and more, but nobody had done the analysis to say, ‘are they are coming back?’” said Larry Crowder, director of the Duke Center for Marine Conservation.
These results also show that conservation efforts over the years, especially those initiated by the Florida Fish and Wildlife Conservation Commission, have been effective. The commission strictly monitored direct contact and habitats for the marine turtles.
Conservation efforts have also had positive effects on other species of turtles besides the leatherback. Stewart said green turtles, another endangered sea turtle known to nest on Florida’s beaches, are also growing in number.
The increase in leatherback turtles serves as encouraging news for marine conservationists, considering there are already a large number of animals on the endangered species list.
“It is good news [to hear that] not all of the endangered species [and] not all of the endangered turtles are plummeting to extinction,” Crowder said. “Some of them are actually coming back.”
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