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The Grand Sea Turtle Experiment on Padre Island

Discussion in 'Sea turtles' started by Cowboy_Ken, Jul 30, 2016.

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  1. Cowboy_Ken

    Cowboy_Ken Well-Known Member 5 Year Member

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    The Grand Sea Turtle Experiment on Padre Island

    By Steph Yin, 7/28/16, New York Times

    Seventy years ago, a Mexican engineer named Andrés Herrera came across a beach in Northeastern Mexico that was teeming with 40,000 nesting Kemp’s ridley sea turtles. He shot some footage and put the film in a drawer, where it sat for more than a decade before he told marine biologists of its existence.

    By the time scientists saw the footage in the early 1960s, the number of Kemp’s ridleys — the smallest and rarest species of sea turtle — had plummeted, mostly as a result of poaching of their eggs, which are prized as aphrodisiacs. Between 1978 and 1991, only about 200 turtles were nesting worldwide each year.

    Mr. Herrera’s film ignited an international movement to save the Kemp’s ridley. Last year, beach patrollers found more than 14,000 Kemp’s ridley nests along the turtle’s nesting range in the Gulf of Mexico, corresponding to about 5,600 mothers.

    Part of the turtle’s recovery can be attributed to conservation efforts at the National Park Service’s Padre Island National Seashore, the largest nesting site for Kemp’s ridleys in the United States. Through spring and summer, park workers collect and incubate eggs, then release newborn hatchlings into the ocean. Those near South Texas might be able to catch a public hatchling release in the next few days, or later in August, by checking the nesting program’s Facebook page, or calling its Hatchling Hotline. Here’s a look at some of what goes on behind the scenes before those turtles get released.

    A Nesting Colony’s Revival

    The Kemp’s ridley nesting program at Padre Island National Seashore began in 1978, when the Kemp’s ridley population had slumped to its lowest point. It was a grand experiment based on a hunch that hatchlings would return to their place of birth.

    Over the next decade, more than 20,000 eggs were transported from the turtle’s main nesting beach in Mexico to be released on Padre Island. In 1996, the first turtle from the project returned to nest on Padre Island. She would be the first of many. In recent years, beach patrollers in Texas have found up to 209 nests in a season, belonging to an estimated 83 females.

    “The numbers have climbed and we’re excited about that,” said Donna Shaver, chief of the sea turtle science and recovery program at Padre Island National Seashore, “but the Kemp’s ridley is still the most endangered of sea turtles. There’s more work to be done.”


    Poaching From the Poachers

    Kemp’s ridleys nest in mass synchronized events, each of which is called an arribada, the Spanish word for “arrival.” From April to August, the turtles climb ashore, dig holes with their strong rear flippers and bury their eggs deep in the sand, each female laying 100 eggs on average. They finish within 45 minutes, and then crawl back to sea, never returning to check on their eggs.

    At Padre Island National Seashore, patrollers use a method learned from former poachers to locate the turtles during nesting season. If they find a mother turtle, they measure her shell and tag her for future identification. Adult turtles typically weigh 80 to 100 pounds, and measure about two feet long.


    Ladies First in the Incubator

    When patrollers find a nest, they count and collect the eggs inside. The eggs are then transported to either an incubation facility or a large screened enclosure on the beach. This protects them from vehicles, flooding and predators like fire ants, ghost crabs, skunks, badgers and coyotes.

    Conditions like sand moisture and temperature are tightly controlled. About a third of the way through incubation, Dr. Shaver’s team turns the thermostat up for some conservation-motivated social engineering. Kemp’s ridleys undergo a process called “temperature-dependent sex determination,” which means higher temperatures favor female hatchlings, while lower temperatures favor males.

    “We aim to produce more females, because they’re the egg layers,” Dr. Shaver said.


    Sleep With a Timer

    After about 50 days in incubation, the babies start to pierce through their eggshells with their beaks. Heads emerge first, followed by front flippers. Having been curled up in their eggs, the hatchlings flatten out their bodies. By the time they’ve unfurled, they’ve absorbed the yolk sacs that were protruding from their undersides, stocking up on nutrition so they can swim away from shore.

    The hatching process is slow, sometimes taking up to four days, but once the turtles are out, they are in a high-energy “frenzy” state and ready to scurry down the beach and swim out through the surf.

    Hatchling releases happen at any hour of the night or early morning. If they aren’t released immediately, the hatchlings can “use up all their energy and become too weak to crawl into the currents,” Dr. Shaver said.

    She and other workers monitor incubating eggs around the clock, waking up every hour to check for the sound of frenzied newborns. As soon as they hear turtles scratching vigorously in their boxes, the workers are off to the beach.

    Obey the Frenzy

    Each summer, Dr. Shaver’s team attempts early morning public releases, so people can see the hatchlings in action. Public releases are planned for when multiple clutches — or several hundred hatchlings — are expected to hatch at once. However, it can be difficult to predict exactly when the clutches will hatch, and public releases are sometimes cancelled last-minute if the hatchlings get into frenzy mode before the morning.

    “It’s all on the turtles’ schedule,” Dr. Shaver said.

    And They’re Off

    It typically takes hatchlings between 20 and 45 minutes to scamper across the beach. As they scurry, they take in the sights, sounds, smells and feels of the beach. Scientists think the hatchlings file away this sensory information through a complicated process called “imprinting.” Eventually, imprinting enables adult females to return to their home beach to nest, even from thousands of miles away.

    While the turtles crawl, Dr. Shaver’s team stands by to deter predators like ghost crabs and sea gulls, as well as to check that each hatchling is alert and moving in the right direction. Usually, navigating from their nests into the ocean is a perilous trek for hatchlings. With help from Dr. Shaver’s team, however, an average of 17,000 hatchlings make it to sea each year from Padre Island.

    “We do everything we can to protect the hatchlings when they’re on the beach,” Dr. Shaver said. “Virtually every one we release gets into the surf.”

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