Aug 30 2018

Why Our Leatherback Eggs Did Not Hatch

By Mary Pringle for The Island Eye News

Photos by Barb Bergwerf

The Leatherback inventory. The smaller eggs are called spacer eggs and would not have yielded hatchlings no one really knows why they exist. A loggerhead egg is about the size of a plate no pong ball while the Leatherback eggs are about the size of a small peach.

Many people have asked how the Leatherback nest laid in Wild Dunes did.

Unfortunately the inventory conducted on August 10 when it was 73 days old and overdue showed that none of the 95 large eggs showed any sign of embryonic development. While this was a disappointment, it was not a surprise. This same turtle laid her first nest on Lighthouse Island in Cape Romain National Wildlife Refuge eleven days earlier on May 18 with the same results – no hatchlings produced.

Loggerhead tracks are about 24-26 inches wide these tracks were nearly 70 inches.

We sought advice and information from two experts, Michelle Pate the Sea Turtle Coordinator for the state of South Carolina at the Department of Natural Resources and Dr. Brian Shamblin at the University of Georgia who conducts the genetics research project all along the southeast coast and is familiar with every aspect of nesting. Their opinion was that the eggs were infertile in both nests.

The reason has to do with something called “site fidelity.”

Sea turtles, including loggerheads and leatherbacks normally spend most of the season foraging and nesting in specific areas along the coast. Leatherbacks do not normally nest on South Carolina beaches. We assumed earlier that this nest was laid by a female who was beginning her migration up the Atlantic coast toward the Arctic Circle following the drifting population of jellyfish, their preferred diet, which they do every season.

However, from the DNA samples taken from her nests we now know that she was not doing this but instead her nests progressed in a southward direction with her two May nests laid on Lighthouse Island and the Isle of Palms. Her third and final recorded nest was on June 11 on Morris Island near Folly beach. How scary is it to think of her swimming around Charleston Harbor for several weeks where she could have been struck by a boat or a large ship coming into port? So she was not headed north.

Why does this matter? It shows that instead of being in Florida near Juno Beach or even farther south in the Caribbean that perhaps she stayed around the South Carolina lowcountry beaches and did not mate with any of the male leatherbacks in Florida. Just as chickens do, these reptiles are going to lay eggs regardless of whether they are fertilized or not. The experts believe that the Morris Island nest would not produce any hatchlings either.

Dr. Shamblin said that the only leatherback nests in our state that have produced hatchlings are from turtles that had been at their normal nesting beaches farther south and come north after mating there, stopping off here to lay later nests. This is what we had first assumed happened, but now we know it did not.

So because she showed site fidelity to South Carolina, she did not find a mate and could not get the eggs from this season fertilized. We did enjoy the experience of seeing her 6-foot wide tracks and finding her cue ball sized eggs for relocation and hope that maybe it will happen again and we will get to see leatherback hatchlings.

Mary Pringle has been the Project Leader for the Isle of Palms/Sullivan’s Island Turtle Team since 2000. It is one of about thirty nest protection projects under the South Carolina Department of Natural Resources. She is also on the Sea Turtle Stranding and Salvage Network.

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