Gazette Sea Foam: Turtles come back, still need our help

August 16, 2010 

Thanks to Sally R. Murphy of Sheldon for sharing her insight into recent news coverage about the sea turtle nesting season.


By Sally R. Murphy

When I was made the Sea Turtle Coordinator for the S.C. Department of Natural Resources in the summer of 1977, it was my job to conduct research, implement management, monitor sea turtle populations and educate and engage the public in these efforts.

There was no management on any nesting beaches and turtles were being drowned in the sturgeon and shrimp trawl fishery. There was no baseline data on nest numbers, hatchling production, mortality levels or coastal habitat use.

Although some beaches north of Charleston were protected, such as Cape Romain National Wildlife Refuge, many beaches south of Charleston were destined for development.

The first research I undertook was to determine hatching success on the major nesting beaches north of Charleston. The results were not encouraging. Less than 10 percent of the nests were surviving to hatch.

The second step was to determine what management could be implemented to save more nests. Predator control and screening and nest relocation from eroded areas increased hatching rates on the same beaches to more than 80 percent.

Telemetry research showed that nesting females were using the same coastal habitat as the shrimping grounds. And the newly formed stranding network recorded high numbers of strandings (dead turtles washing ashore) and showed the clear relationship between the surge in dead turtles and the opening of the shrimping season.

The "monitoring" part of the job included aerial surveys of the beaches in summer from Murrells Inlet to the Savannah River to gain a statewide estimate of the loggerhead nesting effort by counting tracks on the beach. These surveys started in 1980 and revealed that nest numbers were in decline.

It was not possible for one or two people in DNR to monitor the whole coast daily or to implement management on all the beaches. When asked, scores of volunteers stepped forward to help. They recorded data on dead stranded turtles (not a pleasant job), surveyed the beaches daily for nests, screened and relocated nests (if necessary) and even developed their own educational materials to give out to visitors. Today, more than 1,100 volunteers are engaged in sea turtle conservation along the South Carolina coast. The great strides that have been made would not have been possible without their contributions.

So the Beaufort Gazette story, "Year of the turtles: Record number of nests coat area beaches" (July 28), is indeed good news.

But what really worked? We need to understand some loggerhead natural history to have a better understanding of these results.

There are natural fluctuations in loggerhead nesting with high, medium and low years. This is because the same turtle does not nest every year. Some nest on two-year, three-year or longer cycles, depending on how much of their fat reserves they can restore in the off years in order to breed again. They need to produce about 500 eggs, which are divided among about four nests a season. As the graph of Hilton Head Island data showed, two "good" years are often followed by a low one. This year is special because 2008 and 2009 were both good years and this year is surpassing them.

Loggerheads do not come back to the exact beach where they were hatched. Genetics research indicates they come back to the "region" where they were hatched, which could be anywhere in Georgia, South Carolina or North Carolina.

Researchers in Queensland, Australia have determined that their loggerheads (marked as hatchlings) take about 30 years to mature. Whether ours would have a similar life cycle is not known, but probably so.

Nest-protection projects along the coast were begun in the early 1980s and over the years, more beaches were included so that now, about 70 percent of the nesting effort in South Carolina is under management, mostly by volunteers. Because of this, the number of hatchlings reaching the ocean has increased tenfold and we are at that 30-year landmark from when the first nest-protection efforts started.

South Carolina was the first state to require Turtle Excluder Devices (TEDs) in shrimp trawls in 1988. These are grids sewn into the nets at a 45-degree angle and resemble a barbecue grill. They allow shrimp to go through the bars, but deflect sea turtles and other large objects (sharks, rays, old tires, etc.) out through an opening in the net that is covered with a flap of webbing. The federal regulations came on line in 1990, but the exit openings were too small to allow adult females to escape. So while drowning deaths were down overall, the ratio of juvenile to adult turtles changed, with a higher percentage of adults dying. The federal government finally rectified this in 2003. Again from Queensland, researchers are seeing a rise in loggerhead nest numbers about eight years after their government required TEDs. Noting the timeline, we've had really effective TEDs for eight years, especially for nesting turtles.

If a loggerhead continually comes ashore and does not find suitable nesting habitat, she will move elsewhere, even to other islands, to lay her eggs. Hilton Head Island has maintained a stable, sandy beach with periodic renourishment projects. Daufuskie Island's beach is larger and more stable thanks to a recent renourishment project. A dry, stable beach is good for tourism and for sea turtles. "Build it and they will come," looks to be true for the loggerheads in Beaufort County.

The decline in loggerhead nesting statewide has been estimated at 1.3 percent a year since 1980. Over a 30-year period, that comes to almost 40 percent. But even during this decline, the southern coast did not decline as sharply as the northern part of the state.

This encouraging trend in Beaufort County is the result of: 1. TEDs saving large juveniles and nesting turtles; 2. the availability of good nesting habitat, and 3. the protection of those nests once they are laid.

Let's hope it continues ... and by the way, lights out!


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