LEATHERBACK SEA TURTLE-Dermochelys coriacea
The leatherback sea turtle was listed as endangered throughout its range on June 2, 1970. Nesting populations of leatherback sea turtles are especially difficult to discern because the females frequently change beaches. However, current estimates are that 20,000-30,000 female leatherbacks exist worldwide.
Unlike other turtles, leatherback flesh has a peculiar oily taste, keeping them off most humans' dinner plates. However, leatherbacks have a fatal tendency to gorge on floating plastic bags mistaken for jellyfish, and poachers illegally dig up eggs to sell or eat. But the major threat is thought to be entanglement in high seas fishing lines.
What does it look like?
The leatherback is the largest sea turtle. It can grow up to 6.5 feet (2 m) long and weigh 1,400 pounds (636 kg). The leatherback gets its name from its shell, which is like a thick leathery skin, with the texture of hard rubber.
Where does it live?
The leatherback can range throughout almost all the oceans of the world and nests on tropical beaches in the Atlantic, Indian, and Pacific Oceans. Once abundant throughout the world's oceans, all eight species of sea turtles are now threatened or endangered.
Leatherback populations have plummeted in recent years. In the 1980s the worldwide population was estimated at nearly 100,000. Breeding populations are distinct, however, and many are highly endangered. On one important nesting beach in Mexico, there were 6,500 nests recorded in 1986, but only 50 by 1993.
They are also remarkable among reptiles in that they can survive in cold waters; they have been reported as far north as Norway and south off the coasts of Chile and New Zealand. This range is possible because leatherbacks can keep their body temperature warmer than the water surrounding them, due to a thick, oily, fat layer under their skin and their ability to shunt (turn off) blood flow away from cold flippers. All other sea turtles are confined to the warmer regions of the world's oceans.
What does it eat?
Leatherbacks are unique among sea turtles in that their primary food is jellyfish. They also will eat fish, mollusks, squid, sea urchins, and other marine creatures. Adult leatherbacks ply the seas alone, except on occasion gathering to feed in areas with large numbers of jellyfish. Sea turtles swim with grace and speed and have been clocked at an amazing 22 miles per hour.
How do they get it on?
Once a male leatherback sea turtle struggles from its egg and makes its way to the sea as a 4-inch (10 cm) hatchling, it may never again return to land during its 80-year lifetime. Although they are air-breathing animals born on land, leatherbacks, like all sea turtles, spend their lives in the ocean. Females return to land only to lay their eggs.
After mating with a male just off shore, the female waits for nightfall to clamber up the beach, dig a shallow pit in the sand, and deposit her eggs. The female then buries the eggs with her hind flippers and compacts the sand with the weight of her body before crawling back to the sea.
Although a female may lay as many as 100 to 150 eggs at time, only a few will survive to grow to adulthood and breed. Life is perilous for a tiny hatchling sea turtle. They are a favorite food for natural predators such as raccoons, seabirds, sharks, and large fishes. If it can survive to adulthood, spending as long as 10 to 15 years at sea, a turtle will return to breed at the same beach where it hatched.
Threats to Survival
Sea turtle eggs are a prized food for humans and animals alike. They are easy prey, simply waiting to be dug up once the female turtle returns to the sea.Turtle eggs are used in traditional Asian medicines, and in most parts of the tropical world the eggs are an important part of local diets. Latin Americans covet sea turtle eggs as an aphrodisiac and energizing protein.
As a natural defense, sea turtles lay a large number of eggs. But this defense is breaking down under the pressure of increased human harvesting and disturbance of nesting beaches. In some areas people harvest nearly 100 percent of eggs immediately after they are laid.Domestic dogs and pigs, which accompany human settlement, also are lethal predators of turtle eggs and hatchlings.
Humans have long hunted adult sea turtles for food and for their shells and other parts. In Indonesia, for example, shops are full of turtle souvenirs, turtle-skin bags, jewelry made from shells, and stuffed turtles, all of which are marketed to tourists.Sea turtles have suffered from the growing taste for turtle soup, considered a delicacy in Europe. Leatherbacks are killed to be rendered into oil for caulking boats in the Persian Gulf, for use in oil lamps in Papua New Guinea, and for medicinal use in the Caribbean. In the Solomon Islands, hunting sea turtles, including leatherbacks, is considered an important cultural event. Japan historically has been the largest importer of sea turtle products in the world. Between 1970 and 1989, Japan imported 1.5 million pounds (680 metric tons) of shell, which represents about 700,000 dead turtles.
Sea turtles have used the same nesting beaches for thousands of years. The nesting beaches turtles prefer are now very often the same beaches most heavily used by people, and noise and bright lights easily disturb nesting turtles. All over the world, hotels, restaurants, and homes have encroached on turtle nesting beaches. Female turtles are frightened away and eggs are crushed by humans sunbathing, playing, and driving on the beaches. Upon hatching, the baby turtles often get confused by the lights of buildings near the beach; they are supposed to be drawn to the bright white light of the surf. When they get confused, they can go the wrong way and die.
Because sea turtles make lengthy migrations from hatching beaches to feeding grounds and back, they are exposed to a wide variety of threats. Pacific loggerhead sea turtles, for example, hatch on Japanese beaches and then swim 7,500 miles (12,000 km) to favored feeding grounds off Baja California.
Already declining due to heavy hunting of eggs and adults, large numbers of sea turtles are killed each year in fishing nets. Driftnets, huge floating nets as much as 30 miles long, kill untold numbers of sea turtles, along with dolphins and seabirds. Caught in a net and unable to surface for air, sea turtles can drown in 40 minutes.
Until recently an estimated 55,000 sea turtles died from shrimp trawling in United States waters each year. Shrimp trawl boats drag nets that scoop up shrimp as well as every other living thing in their paths. It is a wasteful fishing method, with unwanted animals making up as much as 80 percent of the weight of the total catch. That means 5 pounds of dead fish, clams, and other marine animals are thrown overboard for every pound of shrimp!
The long-line fishing industry is now suspected to be the primary danger to sea turtle survival. Long liner ships set out fishing lines up to 75 miles long, hung with thousands of hooks. Tens of thousands of sea turtles are snagged and drown on long lines yearly. Leatherback sea turtles in particular may be attracted to long-lines by the chemical light sticks attached to the lines, which may resemble the jellyfish that constitute their primary food.
Their preference for jellyfish makes leatherbacks susceptible to another threat: floating plastic garbage in the oceans. Nearly 50 percent of leatherbacks recently studied had plastic bags or cellophane lodged in their stomachs or intestines. Dead sea turtles have been reported containing everything from pieces of plastic milk jugs to bits of balloons, items likely ingested when mistaken for jellyfish.
What are we doing to save them?!
The United States and 115 other countries have banned the import or export of sea turtle products. However, the pressures on sea turtles are not abating and some illegal trade in turtle products continues. Although attempts are being made to control international trade, localized exploitation of turtles and eggs at the nesting beaches is still a problem.
Efforts to protect these species need to focus on the nesting beaches. Law in most countries where nesting occurs only nominally protects sea turtles. For example, local peoples still heavily exploit the extremely endangered Malaysian leatherbacks. On one nesting beach, 1500 leatherbacks were counted in the 1950s, yet by the early 1990s fewer than 50 came ashore.
Another beach in Malaysia is the site of a creative "managed exploitation" effort aimed at saving the species while allowing some human use of turtle eggs. Adult sea turtles are now strictly protected, but egg collection by licensed collectors is allowed. The government issues permits and then buys back a percentage of the collected eggs for captive incubation, hatching, and release of turtles to the wild. The permit fees paid by egg collectors contribute to the cost of running the hatchery. This combination of species conservation and local utilitization may be a model for other places.
Carr, Archie. The Sea Turtle--So Excellent A Fishe. University of Texas Press, 1986.
Rudloe, Jack. Time of the Turtle. Truman Talley Books--E.P. Dutton, 1989.
Fosdick, Peggy and Sam. Last Chance Lost? Irvin S. Naylor 1994.
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