May/June 2016DNR Biosphere: The Sea Turtle CruiseText and photos by Erin Weeks
The DNR's sea turtle program plays a crucial role in restoring this endangered species in the Southeastern states.
On a muggy June day in 2015, the crew aboard the R/V Lady Lisa pulled a sluggish sea turtle onto the ship's deck. The loggerhead looked like it'd seen a streak of bad luck; a partially missing front flipper hinted at a run-in with a shark, and a barnacle-covered shell and marine leeches suggested its health had been in decline for some time. The crew grew concerned about the turtle's prospects if they returned it to the Atlantic.
Despite its unusual state, the turtle was not an unexpected guest. In fact, it was the thirteenth sea turtle the crew had pulled aboard that week. Twelve weeks out of the year, S.C. Department of Natural Resources biologists embark on research expeditions to study sea turtles just off the southeastern coast.
By catching turtles in open waters, researchers get a glimpse of something rarely seen: juveniles and males, the little-studied members of sea turtle populations that rarely come ashore. Together with decades of research on female nesting turtles, their findings give wildlife officials a more complete understanding of how sea turtles, particularly loggerheads, are faring in South Carolina and beyond. And for the first time since loggerheads were declared federally threatened, biologists are expressing cautious optimism about the future of these ancient reptiles.
Every spring, sea turtles trundle ashore under the protective cover of night, dig cavities a couple feet deep in the sand and lay a hundred-odd leathery, white eggs.
It's a familiar and iconic story for many who live along the coast, one that's played out for millions of years. Sea turtles have inhabited the earth's oceans since the age of the dinosaurs, surviving the mass extinction that killed off Tyrannosaurus rex. Habitat loss, overharvesting and entanglement in fishing gear led to drastic population drops in the 20th century, and the planet's seven surviving species are all considered federally endangered or threatened in the United States.
Today, residents and visitors look forward to the return of nesting sea turtles to South Carolina beaches each year. The moments in which these animals come ashore captivate us, but they represent a fleeting snapshot of a sea turtle's life story. Only mature females come aground to nest, limiting land-based studies and genetic research to a portion of the sea turtle population. That's why DNR biologists tackle sea turtle conservation from both land and water.
As breeding season begins, DNR biologists and thousands of dedicated volunteers cover the coastline to count, relocate and monitor sea turtle nests laid on South Carolina beaches. By managing the many threats to nesting females and hatchlings on land - predators, human disturbance, washed-out nests - they improve the numbers and odds of young sea turtles reaching the ocean each year.
"Our goal is to protect sea turtle nesting areas along the beach," said biologist Michelle Pate, who coordinates the DNR's sea turtle program, "but we also have to make sure human activities in the water are not negatively affecting the populations."
A parallel operation thus unfolds each year to capture and study sea turtles where they live out most of their days: in shallow coastal waters. For fifteen years, this DNR project has generated a wealth of data that researchers all over the country have used to answer questions about sea turtle numbers, movements and health.
"Loggerhead sea turtles take thirty years, roughly, to reach maturity," said DNR biologist Mike Arendt, who currently leads the offshore survey. Previously, those decades of life remained a mystery for biologists, who could only speculate how threats in the ocean affected sea turtles. "We're trying to understand more about turtle life at sea, where they spend 99 percent of their life," Arendt said.
To better understand this blind spot in sea turtle conservation, DNR's R/V Lady Lisa and the University of Georgia's R/V Georgia Bulldog (operated by the Marine Extension Service in Brunswick, Georgia) trawl the coastal waters of South Carolina, Georgia and Florida each summer, manned by a crew of captains, deckhands, a cook, a head scientist and several other biologists and volunteers.
On the June morning they captured the sick loggerhead, the Lady Lisa's crew set out from Charleston Harbor, where they'd anchored the night before. The Lady Lisa, a shrimp-trawler-turned-research-vessel, headed north along the coast as the sun rose orange over the Atlantic. Crew members trailed into the kitchen for a hearty breakfast of biscuits and gravy, bacon and eggs to order, and plenty of fruit. Spending a full workweek at sea can mean long, exhausting hours in harsh weather and with little personal space, but at least on this ship, the crew always eats well.
On this trip at randomly selected sites within view of the coastline, the crew lowered the ship's outriggers, which jut out like arms over the water. Two green trawl nets, one attached to each arm, dropped into the water. The ship picked up speed, and the nets trailed into the depths. After half an hour, deckhands began to pull in the nets to see what they'd caught.
For minutes, nothing was visible as the winches clanked and turned, reeling in the nets. Then the team members started craning their necks in anticipation. Success looks like a brown hump - just a dark, domed swelling in the net. But the sun and water often play tricks on the eyes, so everyone scans for a flash of yellow flipper as confirmation of a sea turtle.
When a turtle is spotted, the crew springs into action. The streamlined process returns each animal to the water in as little time as possible, minimizing stress.
"We're really trying to get a good macroscopic picture of what each animal looks like," said Arendt. For most turtles, the process takes only ten to fifteen minutes.
Once a turtle is safely onboard and found in good health, the crew checks it for existing tags. If it has not been caught before, the turtle is given a unique ID. One scientist rushes a blood sample back to the ship's in-house lab. Others begin to document physical details, such as the presence of barnacles, and measurements, such as shell size. Every sea turtle is tagged with metal ID bands on their front flippers, and a select few are fitted with acoustic or satellite tags on their shells, which can help DNR track their movements after release.
Finally, crew members place the sea turtle in a harness to measure its weight. They then lower the turtle, still in harness, over the side of the ship and into the ocean.
"We splash it, yell 'turtle away!' and clean up for the next site," Arendt said. "And that's how you knock out four hundred stations in a year. It's very methodical... but we have fun."
The process changed on the day the crew pulled aboard the sluggish loggerhead. Bloodwork confirmed that the animal was sick, with a low red blood cell count. Rather than release it, head scientist Julia Byrd elected to bring the turtle back to port and transport it to the South Carolina Aquarium's sea turtle hospital in Charleston, where staff administered a regimen of antibiotics, vitamins and fluids - and gave the turtle a good prognosis. Within two months, the rehabilitated loggerhead was healthy enough to return to the ocean.
Fortunately, sick turtles are a rarity aboard the Lady Lisa. "Overall, sea turtles captured in our surveys appear to be in good health," Arendt said. Of approximately 3,000 turtles tagged since 2000, most of which are loggerheads, few show signs of emaciation, injuries or low red blood cell counts.
Even for veterans of the project, though, every trip promises surprises.
A month after the sick loggerhead episode, two sea turtles were recaptured in a single week. Turtles are rarely seen again after being tagged, so two recaptures in a matter of days struck the crew as unusual. When they checked on the history of the sea turtles, both female loggerheads, the biologists were even more surprised to learn that both had been previously captured and tagged in the same year: 2000, when the program first began. The fifteen-year intervals between release and recapture marked a new record for the project.
Aside from the scientific significance of detailing how they'd aged over the years, seeing the loggerheads alive and well after so many years was deeply gratifying for the researchers who work on the project. Arendt was present both in 2000 and 2015, and he noted that the younger of the two females had only grown seven inches in fifteen years.
"They grow up so slowly," he said.
That slow maturity means recovery efforts are unfolding over what can seem like a glacial timescale. But biologists can finally see signs that decades of conservation efforts may be starting to pay off.
In 2015, sea turtle nest numbers broke records along the Atlantic Coast. South Carolina came close to exceeding its previous statewide nest record set in 2013. For the fifth out of six years, Georgia saw the highest number of nests since the state began keeping records. Green sea turtles in Florida also laid a record-breaking number of nests.
An increase in nests alone is not enough - biologists must ensure that the increase is due to a rise in nesting female numbers, rather than a limited number of females laying more nests. A long-term genetic project, started by Brian Shamblin of the University of Georgia, has allowed DNR researchers to answer that question by identifying the individual sea turtle that lays each nest in South Carolina. Data collected from this work suggests that the number of nesting females has also grown slightly over the past decade.
In the water, Arendt's team has also documented an increase in the numbers of turtles they catch, including the small and endangered Kemp's ridley sea turtle. Again, increased catch numbers do not necessarily mean a larger population, Arendt said. The species' range could be shifting, for instance, causing them to spend more time in South Carolina waters. In the coming years, his team will spend more time studying the Kemp's ridley.
"True success will be when we reach what we consider recovery," said Pate, "when the sea turtle populations are large enough that they can reproduce on their own, and they don't need so much human intervention to help them along."
Sea turtle species still face a long and challenging path to recovery. The U.S. Fish and Wildlife Service has calculated target numbers of breeding females and nests for loggerheads, beyond which the species would be considered for delisting. South Carolina's target number for recovery is 9,200 nests; in 2015, loggerheads laid 5,106 nests in our state.
With luck and help from a devoted team of staff and volunteers, the juvenile sea turtles that hatch on South Carolina's coast this year will soon disappear into the vast Atlantic. For the next several decades, they'll fight an uphill battle against the natural and man-made dangers of the sea. Someday, a small fraction will return to South Carolina to breed and lay their own eggs.
Until then, the Lady Lisa and her crew will continue to cruise the coast each summer in search of sea turtles that have beat the odds.