Swimming to Oblivion
To survive, the endangered ridley sea turtle will have to overcome pollution, shrimpers, and its own instincts.
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Once the turtles came by the tens of thousands, water sluicing off their shells as they heaved themselves from the surf and lurched across the dunes. Somewhere above the high-tide mark, the beach looked and felt right. Sand flying, each animal dug a nest, laid her eggs, covered them, and turned once again toward the ocean. Among nature’s spectacular mass movements—the peregrination of the wildebeests, the migration of the monarch butterflies, the quixotic suicide of the lemmings—the arribada, or arrival, of the Kemp’s ridley sea turtles on Gulf of Mexico beaches could hold its own.
Today, though, the arribadas of the ridleys are history. Decimated by decades of nest robbing and threatened by shrimp nets and pollution, Lepidochelys kempii is the most endangered sea turtle in the world. Only five hundred to six hundred nesting females and an unknown number of males and juveniles remain. One ill-timed natural or man-made disaster—a hurricane, an oil spill—and the epitaph of the ridley can be posted beside those of the passenger pigeon and the woolly mammoth.
Efforts to save the ridley have been ongoing for more than two decades, beginning in 1966, when Mexico made it illegal for anyone to disturb the animals’ primary nesting beach. Every year after that, scientists have hoped and waited for the ridleys to rebound. It hasn’t happened. Though no one realized it at the time, the arribada of 1968 proved to be the last of any real size, and its gathering of two thousand animals was a ghost of the grand aggregations of years past. In 1977, prompted by the feeling that time was running out, representatives from Mexico, the United States, and Texas met to collaborate on an unusual project. The first imperative, they decided, was to redouble efforts to protect the eggs in Mexico. The more radical part of the plan was to launch an experimental program to plant a satellite nesting colony of ridleys on Texas’ Padre Island National Seashore. The theory of imprinting, upon which this plan was based, was unproven in turtles. But the three governments felt they had to act.
The ten years allotted for the colonization attempt will be up at the end of 1988. On the one hand, the overall project is a success. Hatching in Mexico has improved tremendously; 40,000 to 70,000 baby turtles a year are released at the species’ nesting site. On the other hand, the project is a continuing frustration. Every year the number of nesting females has declined 3 to 4 percent, and no brave new colony of ridleys has yet claimed Padre Island. Unless the imprinting part of the program is renewed, the transfer of turtle eggs to Texas this summer will be the last in an unprecedented effort to change the ways of a sea turtle.
Two hundred miles south of Brownsville, in the Mexican state of Tamaulipas, lies the sole mass nesting beach of the Kemp’s ridleys. With its fine sand and low dunes, it looks like any South Texas shore. Flat rocks lie here and there, washed up by the tide. A few spiny shrubs punctuate the low tropical vegetation, and behind shallow lagoons, mangrove trees cast a dappled shade. Half the year villagers from nearby Rancho Nuevo swim and fish here. But every spring and summer the beach is declared off limits as a small number of armed Mexican marines and biologists and bureaucrats from both sides of the border await the arrival of the turtles.
Scientists, students, and soldiers arrive at Rancho Nuevo in April, prepared to stay through July or later if necessary. In the days of the vast arribadas (pronounced “ar-ri-bah-das”), the nesting animals would come in two or three enormous waves in April and May. Now whatever force summoned the turtles has weakened, and the females straggle in over a period of weeks. The Mexican group (under the fisheries department) has erected a permanent bivouac. The United States contingent (coordinated by Brownsville’s Gladys Porter Zoo for the U.S. Fish and Wildlife Service) has a barracks. There is also a building to hold the turtle eggs destined to be raised for a year in Texas and then released off Padre Island. Usually two thousand eggs are transferred; this year it will be one thousand each of eggs and hatchlings. About fifteen people are usually on hand. Normal dress runs to cutoffs and flip-flops, and amenities are minimal. Jack Woody, 51, national sea-turtle coordinator for the Fish and Wildlife Service, recalls that at one low point rains closed the road to town and everyone was reduced to eating cactus and armadillo.
Each day begins at dawn with a reconnaissance by three-wheeled vehicle up and down the beach to look for tracks or perhaps a beak-faced female turtle—Mexicans call the ridley la lora, or “parrot”—already flailing away at the sand. A strangely atypical sea turtle, the ridley is compact and hyper. Fishermen had a legend that if captured, ridleys died from fear and frenzy. One man told the late sea-turtle expert Archie Carr, “You can’t keep a ridley on its back. Only a few hours. They’re crazy. They break their hearts.”
Ridleys have not made life easy on themselves. A few iconoclasts do crawl ashore sporadically to lay eggs on beaches around the Gulf, including Mustang and Padre islands, but the rest of the species stubbornly nests nowhere but Rancho Nuevo. Perhaps once there were other arribadas, but today there is only one—or what is left of it. By preference and unlike all other sea turtles, ridleys nest in daylight with a stiff north breeze blowing. No one knows why, but possibly the wind erases their tracks. “They have to have a crappy day,” says National Marine Fisheries Service biologist Tim Fontaine, 49. “If it’s nice, you’ll see the turtles offshore, waiting.”
Ridleys are the smallest of the seven or eight species of sea turtles. Fully grown, they weigh about ninety to one hundred pounds, and their shells measure 25 to 29 inches long. Perhaps because they are too small to warrant the effort, their meat and skin have never been commercially valuable. (The turtles are, however, good eating. One fisherman told a scientist he had been so moved by stories of the ridleys’ decline that the next time he caught three, he kept only one.) Another apparent advantage of their small size is the animals’ relative speed and dexterity. Compared with the huge green turtle, which may be vulnerable for several hours while nesting, a ridley can land, nest, and be gone in 45 minutes.
When the reconnaissance team is lucky, a female turtle is spotted heading toward the tunes. Before she stars digging, she’s easy to spook, so they stand motionless until she crawls up past the high-tide mark and begins to dig. Slapping away at the sand with her front flippers and rocking from side to side, she first wallows out a shallow body pit. Then, with her hind flippers, she carefully excavates the nest cavity. Again and again, she stretches as far as she can reach into the hole and scoops out one flipperful of sand at a time. Her appendages are almost as flexible as hands.
A turtle is mute, and the only sounds the female makes are rhythmic sighs as she beings to expel her clutch of eggs. Her myopic eyes weep with the flow from salt-excreting glands situated beside her tear ducts. Her head dodders slightly, and she seems to go into a trance. Leathery-shelled eggs the color of parchment and the size of ping-pong balls drop rapidly into the damp sand of the eighteen-inch-deep nest, filling its flask-shaped chamber. She lays just slightly more than one hundred eggs at a time and may return once or twice to lay again a few weeks later. Somewhat over half of the Kemp’s females nest at Rancho Nuevo annually, but others apparently lack the strength to make the arduous journey every year.
When one considers how prolific Kemp’s ridleys are, it’s a bit ironic that for years they were thought to be sterile. No one knew of a ridley nesting beach, and captured female ridleys never had eggs in them. Fisherman thought they were infertile hybrids of green and loggerhead turtles. One man told Archie Carr, “This yer [sic] ridley don’t have no young’uns. He’s at the end of the line, like a mule.” It wasn’t until 1961, when Corpus Christi biologist Henry Hildebrand brought to light a shaky, faded 1947 home movie of a Kemp’s ridley arribada of an estimated 40,000 clambering, jostling, milling animals, that scientists had the slightest proof that the turtle was in fact a spectacularly fecund species and that it nested in Mexico.
In the years since, information about the arribadas has remained elusive. Their trigger may be the water-borne secretions from eight or ten special glands, called Rathke’s glands, that empty through pores in the ridleys’ lower shells. Scientists don’t know for sure. Neither are they positive when the turtles mate, although they believe that it happens under water, days to weeks before the arribada forms. In the early sixties Brownsville shrimper Julius Collins encountered a flotilla of hundreds of ridleys off Ranch Nuevo. “Some of them were coupled,” he recalls, “male and female together, floating by. It was a wonder to see.”
On the beach, members of the reconnaissance team have quietly moved closer. Most of the time they wait till the turtle has finished and then rebury her eggs to hatch in a fenced area protected from predators. If they have the good luck to arrive before the turtle has laid, they can collect the cache for transfer to Padre Island. One person crouches behind the animal and begins to dig with her, lengthening the hole in between each stroke of her hind flippers. When the turtle positions herself to lay, he pulls on a pair of surgical gloves and stretches out on his stomach behind her. Under her shell he holds a sterile plastic bag (the kind used to carry organs for transplants). According to the theory of imprinting, certain animals—salmon for one—“memorize” the smell of their birthplace and use the memory like a radio signal to return to the site years later. For the turtle-imprinting experiment to work, the eggs to be hatched at Padre Island must not touch Ranch Nuevo sand; the odor of the beach might be transmitted to the embryo even through the shell of the egg.
While the turtle is methodically filling the hole and tamping the sand with her hind flippers, members of the team take the opportunity to measure her shell. They also use a large punch to attach a metal identification tag, like a cattle ear tag, to one of her front flippers, a procedure supposedly no more painful than having an ear pierced. As Tim Fontaine points out, however, “A turtle can’t fuss or scream, but you can feel its muscles quiver” when the punch pierces its flesh.
At beach headquarters the person who collected the eggs goes to the egg house and transfers his cargo to a special plastic-foam box (it looks a lot like a beer cooler) filled with moistened sand from Padre Island. Each clutch of eggs is piled up the way it would be in a natural nest. Unlike bird eggs, which must be rotated regularly to remain viable, turtle eggs cannot be jostled. The embryo attaches by a thin membrane to the top of the shell after the first 24 hours, and for two and a half weeks any movement or shock can dislodge and kill it. The eggs then may be carefully moved, and 45 to 55 days after they were laid they will hatch.
Turtle nesting time at Rancho Nuevo today is a model of order and care, but in the days of the huge arribadas, it was chaos. Even before the turtles had left, coyotes, village dogs, coatimundis, and skunks would descend upon the beach, dig up the nests, and gulp down as many eggs as they could find. Even when the eggs weren’t eaten they were ruined for hatching. But the loss of eggs to animals, heavy as it was, was minor compared with the damage done by human predation. Dearl Adams, 72, a Brownsville man who in the sixties personally saved thousands of ridley eggs by transporting them to South Padre, says, “Back then, when the arribadas would come in, everybody from the villages would have him a turtle, waiting for her to lay.”
If the only pressure on the ridleys had been the coyotes and the local people, the turtles probably could have lasted. But ultimately they received a devastating blow: the outside world got wind of the arribadas. Before then, the problem was just men on horseback riding out with saddlebags full of turtle eggs to sell. By the early sixties, buyers were coming in carryall trucks, lumbering down the mud-clogged road at nesting season to buy every egg they could get. At 1,000 pesos (about $80) a hundred, the eggs represented valuable seasonal income. And—for a time—there were millions of them.
Where did all the turtle eggs go? For the most part, they ended up in cantinas, where their imagined aphrodisiac qualities placed them in high demand. The accepted macho procedure for consuming one—they were always eaten raw—was to tear a small hole in the shell, apply liberal quantities of salt, pepper, and lime juice, suck out the contents, and chase it all with a beer. Adams recalls once seeing a three-foot-high pyramid of turtle eggs on a table in a bar. The eggs were also sold in markets, right alongside the chicken eggs, and those not used right away were pickled to be eaten later.
Considering the mythic quality of turtle eggs in Mexico, one has to wonder if they are worth eating. “Turtle eggs are terrible,” says Jack Woody. “They’re fishy when they’re raw, and the taste would gag a maggot.” Dearl Adams is of two minds. The eggs of one other species he tried were pretty bad, but ridley eggs, he says ruefully, “are some of the best there are.” One rather strange aspect of turtle eggs is that the white does not solidify when boiled, which means it is always runny. Although that feature is not particularly desirable in most cooking, it’s perfect for baking. Before the Endangered Species Act was passed in 1973, bakeries in Florida proudly advertised that their extra-moist cakes were made with turtle eggs.
Today in Mexico it is illegal to sell the eggs of any species of sea turtle, but that hasn’t stopped the black-market trade. In certain Mexico City markets you can buy a turtle egg, shelled, in a Dixie cup, for 1,000 pesos—50 cents.
When approximately two thousand turtle eggs have accumulated in the shed at Rancho Nuevo, Pat Burchfield, 45, curator of the Gladys Porter Zoo and field coordinator at Rancho Nuevo, prepares for the biggest headache of his job: getting the eggs to the United States all in one piece. As often as not on egg-export day, the dirt landing strip is under water from recent rains, so the plane has to land on the beach. Says Burchfield dryly, “We’ve had a couple of landings that weren’t exactly thrilling.” After seven years he has mastered the juggling act of getting all the permits in order and bringing in officials from the Mexican government to make the presentation of the eggs to the United States. “I don’t want to sound like the postman,” he says, “but rain or sleet or snow—we fly those eggs.” The worst year he can remember was 1983, when Mexican customs officials confiscated the plane—with the eggs in it—for three days, leaving it to bake on the runway in Matamoros while zoo employees ran frantically back and forth across the border, trying to keep the sand in the boxes moist. Finally the plane was allowed to proceed, and miraculously, the eggs were unharmed.
Burchfield’s nerves don’t unfrazzle until he as cleared American customs in Brownsville and delivered the eggs to their foster home, the Padre Island National Seashore headquarters. There turtle-egg nannies Jennifer Bjork, 39, chief of environmental services, and Donna Shaver, 28, natural resources specialists, place each box inside a second plastic-foam box. This protects them from insects and increases hatching success, which has averaged 76 percent overall. Equally important, the boxes modulate temperature fluctuations. The sex of a turtle embryo is, like that of all reptiles, determined by temperature. At about 84 degrees Fahrenheit, the sexes are equally mixed. Above that temperature, more hatchlings tend to be females. Below, more are males. The two sexes look exactly alike until turtle puberty, when the male’s tail suddenly grows very long and stout.
The vigil begins. In a natural nest, hatching takes about four days, as first one and then another turtle tears and struggles its way out of the shell. That sends a drizzle of sand around the remaining eggs, raising the bottom of the nest like an elevator, until the entire squirming mass of baby turtles is carried up and into the open air. Of course, a box in the turtle shed at Padre Island doesn’t bear much resemblance to a natural nest, so the turtles get some help.
As each one begins to emerge from its egg, it is solicitously dug out of the sand and brushed off. Freshly hatched, a ridley turtle is about the size of a silver dollar. Its upper shell is black, with multiple peaks, or keels, that will smooth out as the animal matures. At this point, it looks like most baby turtles, but when it is a few months old, the underside and the edge of the upper shell will begin to turn creamy white, and eventually the upper shell will change to a uniform gray. At about a year, the ridley’s flat, broad shell looks like a fat pancake.
Turtles almost always hatch at night, and within 24 hours they are usually ready for their baptismal swim. Around six in the morning someone drives the tiny animals to the beach and puts them on the sand. As the sun rises in the sky the turtles turn instinctively toward the light over the ocean. Then, says Bjork, “they run off toward the water like windup toys.” Plowing along with their noses and chins, the hatchlings look as if they could be sniffing the sand or perhaps checking the grain size, much as their mothers do when they land at Rancho Nuevo. The turtles are allowed to paddle in the surf and dive a couple of times. Then, their taste of freedom over, they are netted like guppies, counted, measured, and weighed. Finally they are placed on moist foam pads for the five-hour drive to the place where they will spend the next year of their so-far very unnatural lives, the National Marine Fisheries Laboratory in Galveston.
The ridley’s new home at the Sea Turtle Head Start Project consists of three 96-foot-long Quonset huts covered with heavy plastic sheeting. Each animal has private quarters in a plastic-gridwork container placed in one of numerous long fiberglass tanks of water pumped in from the nearby Gulf. The moisture-laden air and tropical temperature are heaven for turtles but hard on humans, and in the summer, says Head Start supervisor Tim Fontaine, “it smells to high heaven.” Keeping the turtle nursery going costs $400,000 to $500,000 a year, funded partly through the federal Endangered Species Act. The return of tags from Kemp’s ridleys that have been caught indicate that a year in a tank doesn’t seem to give them any difficulty in adapting to the rigors of life in the ocean. Over ten years, more than 12,000 turtles have been raised here.
The routine is much like that of a zoo—feed the animals, clean the cages—but getting it down wasn’t easy. “The first year, no one knew anything about raising ridley hatchlings” says Charles Caillouet, Jr., 50, the chief of the lab’s life studies division. So workers put all of the tiny turtles together. The three-ounce ridleys lit into each other with murderous intent. Says Fontaine, “We had animals with their flippers chewed off and their eyes eaten out—the ridley is a vicious, mean, antagonistic, pit bull of a sea turtle.” The horrified workers had to resort to isolating the injured turtles in buckets (not red buckets—that really riles them), but injuries coupled with infections eventually did in a third of the original group. The overall survival rate today is 89 percent, and in 1987 it was 99 percent.
Head Start turtles grow faster than their wild brothers—but they pay a price. In the ocean, ridleys dine on a bouillabaisse of crabs, clams, mussels, snails, jellyfish, barnacles, and the occasional fish. At the Galveston laboratory, they get pellets of sensible, high-protein Purina Sea Turtle Chow. At three months, they’re old enough to start tagging. The first kind of tag they receive is a “living” tag, which consists of a quarter-inch plug of the animal’s white bottom shell grafted to its black upper shell. Later a sliver of magnetized wire is injected into one front flipper. When the turtle has put on a couple of pounds and has grown to Frisbee size, it receives a punch flipper tag. The final type is the experimental “pit” tag, an injected silicon chip. All but the punch flipper tag, which eventually corrodes away, will probably last longer than the turtle does.
Ridley release day usually comes in May or June. “It’s a grand event,” says Fontaine. “Every year I expect interest to diminish, but people keep showing up.” The turtles are packed in large corrugated-cardboard poultry boxes and loaded in rented trucks for the trip to Padre Island. As press cameras and Instamatics click, a University of Texas research vessel filled with boxes of turtles heads out to sea. About twelve miles out, the ridleys’ keepers see the last of them as the animals are dropped, rather unceremoniously, into the murky water of the Gulf. For a few seconds the turtles twist and spin in the frothy wake. Then, regaining their equilibrium, they exit swimming, with quick, strong strokes.
For every thousand turtles that hatch in the wild, maybe one or two survive to adulthood. The first few years of life are perilous, and like any vulnerable young animal, a baby ridley turtle hides. It becomes a turtle-in-residence among the abundant sworls of sargasso and the drift lines of plants and debris that form on the surface of major currents in the Gulf. There it grows until a diet of small marine life no longer suffices, at which point it abandons its safe harbor to dive for crabs in waters closer to shore. No one is sure what happens then. It may stay in the Gulf, or it may travel with the ocean currents up the Atlantic seaboard, but one day—ten or even twenty years later—its hormones awaken. Breeding time has come.
The theory of imprinting may explain how a mature turtle finds its birthplace—now its nesting beach—once within sniffing range. It hardly explains what intelligence guides the creature across the Gulf of Mexico. Maybe, like certain birds, turtles navigate by the sun or stars. Perhaps they pop to the surface en route to scrutinize landmarks or analyze the subtle sound pattern of waves on different shores. Or they could simply fall in with the pack and learn the way from the old turtles. One of the most provocative theories holds that they read the rocks. If the ridley has magnetite in its brain—as do the loggerhead and green turtles—who’s to say that it might not memorize the magnetic fields surrounding underwater rocks and strata? With a handy internal geomagnetic map, it could then find its way to Rancho Nuevo or to Padre Island National Seashore, whichever place felt like home.
Ten years of intensive care of the Kemp’s ridley are concluding with the patient still on life support and no end in sight. So far, no Head Start turtles have been discovered nesting anywhere. Possibly they need more time to mature than the eight to ten years that were previously thought. Maybe the imprinting program, rather than establishing a new migratory pattern, has scrambled the data, so that Head Start turtles will end up nesting who knows where. For the present, protection of the beach will continue, but the egg-imprinting experiment is scheduled to end after 1988. As Jack Woody says, though, “if six or seven turtles stagger up on Padre Island some day, we could always go back and reevaluate.”
People close to the program look at it and see different things. Tim Fontaine wonders if the arribada is not actually extinct already, a geriatric remnant slowly dying year by year. “Until I see the handwriting on the wall, I’ll never give up,” he says, “but if we don’t have an upward trend soon or have some Head Start turtles come back, they’re doomed in five to ten years.” Peter Pritchard, a ridley authority and the vice president of the Florida Audubon Society, takes a more hopeful view. He says, “Perhaps an arribada is not a permanent phenomenon.” The turtles are quite capable of nesting singly, some new females are showing up in Mexico each year, and young ridleys are found in the South Atlantic. Perhaps the Rancho Nuevo arribada was never meant to be forever.
How sad, though, to think that a faded home movie, rainy with scratches, might be the last anyone will ever see of the splendid arribadas of the Kemp’s ridley. One hopes they can be restored—in part to preserve the balance of nature, in part to ensure that another species does not perish at the hand of man. But perhaps the most honest reason to preserve them is for our own delight, because the strange and beguiling ways of this earth’s creatures are a wonder to see.