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August 4, 2010

Mid-season marine turtle survey reported along South Carolina coast

So far in 2010, 2,798 loggerhead, three leatherback, and three green sea turtle nests have been reported on project beaches along the South Carolina coast. The preliminary 2010 statewide estimate for South Carolina this year is 4,175 turtle nests, which includes nests laid on beaches that do not have daily monitoring.

See video of a recent loggerhead nesting.

The major nesting area for the loggerhead in the western Atlantic is the southeastern United States. Loggerhead nesting in South Carolina has been well documented and has averaged 3,378 nests per year over the last 10 years. The nesting season runs from mid-May to mid-August. The average clutch size in South Carolina is 120 eggs. Each female will nest during the night, about four times per season with two week intervals between each nesting event.

The average nest incubation duration for a loggerhead sea turtle is 55-60 days. Nests begin to hatch around mid- to late-July and hatchlings continue to emerge through October. After a turtle nest has hatched, S.C. Department of Natural Resources (DNR) staff and volunteers evaluate the remaining contents of the hatched nest to determine the success of each nest. So far in 2010, 21,435 hatchlings have emerged. To keep up in real time with the number of nests laid and hatchlings that have emerged, visit the South Carolina Online Nest Monitoring System.

Four of the seven species of marine turtle have been known to nest on the South Carolina coast. Although most nests laid in South Carolina are from loggerhead (Caretta caretta) turtles, leatherback (Dermochelys coriacea), green (Chelonia mydas), and Kemp’s ridley (Lepidochelys kempii) turtles have also nested on the South Carolina coast.

The DNR Marine Turtle Conservation Program is responsible for managing and protecting sea turtles in the state of South Carolina. This program has several all-encompassing components: management, monitoring, research, and education. More specifically, this program implements management techniques to mitigate activities that may impact sea turtles and provides training and support to more than 1,100 volunteers across the coast who protect nests and document sea turtles that wash ashore (strandings). DNR staff members also perform necropsies on fresh dead strandings and respond to live strandings in need of care.

The loggerhead, South Carolina’s state reptile, has a rich reddish-brown carapace (shell) and yellow plastron (underside). The loggerhead’s large skull provides for the attachment of strong jaw muscles for crushing whelks and crabs. Loggerheads leave the cold coastal waters of South Carolina in the winter and are often seen along the western edge of the Gulf Stream. Adult loggerheads can weigh as much 300 pounds and reach up to four feet in shell length. 
           
As the peak of hatching season approaches, the support of South Carolina coastal residents and visitors is needed to raise awareness and educate visitors to Keep Light’s Out for Loggerheads. When hatchlings emerge from the nest, they are attracted to the blue and green wavelengths of light naturally reflected off the ocean through celestial light. They use this natural light cue to navigate from the nest towards the ocean. If an artificial light source on the beach is brighter than the natural light, hatchlings will head towards this artificial source. This is known as disorientation and occurs when artificial beach lighting is brighter than the natural ocean horizon. In these instances, hatchings will crawl away from the ocean toward bright, artificial lights, causing them to be more susceptible to predators and exhaustion.

You can also help by turning out all lights in your house that are visible from the beach, dusk to dawn, from May through October. Closing blinds and drapes on windows that face the ocean also reduces the light pollution on the beach. If a sea turtle hatchling is disoriented by artificial light, federal fines for harming a threatened or endangered species can reach $25,000. County and local lighting ordinances exist to protect sea turtles. Violating local or county lighting ordinances carry fines up to $500.
           
Sea turtle stranding response and necropsies (post-mortem examinations) are an important aspect of South Carolina Marine Turtle Conservation Program. There have been 106 sea turtle strandings in South Carolina in 2010 and 11 of these stranded alive. Strandings have averaged 125 sea turtles per year over the last 10 years. Sick or injured live turtles that strand along the coast are retrieved for rehabilitation. Dead turtles are necropsied to assess possible cause of death (disease or injury) and to collect information on food habits and gender. Nineteen necropsies have been performed by the DNR staff (eight loggerheads, five Kemp’s ridleys, three greens and three leatherbacks). To keep up with strandings in South Carolina, visit the online stranding database.

What you can do to help sea turtles in South Carolina


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