AMA Mexico

Leatherback Sea Turtles are in grave danger of extinction on the Pacific Coast of Mexico.  Though once commonly found on the Nuevo Vallarta beach,  only four Leatherback nests were recorded here in 2009.

Geographic Distribution

The Leatherback Sea Turtle is a species with a cosmopolitan global range. Of all the existing sea turtle species, it has the widest distribution, reaching as far north as Alaska and Norway and as far south as the Cape of Good Hope in Africa and the southernmost tip of New Zealand. The Leatherback is found in all tropical and subtropical oceans, and its range has been known to extend well into the Arctic Circle.

Physical Features, Size, and Biological Classification

The Leatherback is the largest of all living sea turtles.  Adults can weight from 700 to 2,000 pounds and measure 4 to 8 feet in length. The largest ever found was over nine feet from head to tail. That particular specimen was found on a beach on the west coast of Wales in the North Atlantic.

All other sea turtles have bony hard plates on their shells (carapace). The Leatherback’s carapace is slightly flexible, has a leathery texture and is covered by skin and oily flesh. No sharp angle is formed between the carapace and the under-belly (plastron) so a Leatherback is somewhat barrel-shaped. Their front flippers are longer than those of other marine turtles. They can reach 270 cm in adult leatherbacks.  Its back flippers are paddle shaped. Instead of teeth the Leatherback turtle has points on its upper lip. It also has backwards spines in its throat to help it swallow food.

It is the only living species in the genus Dermochelys. Globally, there are three major, genetically distinct populations. The Atlantic Dermochelys population is separate from the ones in the Eastern and Western Pacific, which are also distinct from each other.

Life History and Ocean Behavior Facts

Research on captive turtles indicates that leatherbacks grow faster than any other sea turtle. Leatherbacks feed mainly on pelagic (open ocean) soft-bodied invertebrates such as jellyfish and tunicates. Highest concentrations of these prey animals are often found in areas where deep water comes to the surface (upwelling areas) and where ocean currents converge. Leatherbacks can dive to depths as great as 4200 feet.

The Leatherback prefers the open ocean and moves into coastal waters only during the reproductive season. Although small groups may move into coastal waters following concentrations of jellyfish, these turtles seldom travel in large groups.

Age

These giant turtles have been said to live anywhere from 40 to 150 years!  Adults are believed to reach sexual maturity between 5 and 21 years!  (WWW admits they don’t know!)

Nesting

Unlike most sea turtles, which nest in the spring and summer, Leatherbacks usually nest in fall and winter and appear to nest once every two or three years. Females may lay four to five times per season at 8-12 day intervals. They lay their eggs on sandy, tropical beaches and do not appear to be as loyal in their return to their birthing beach as other sea turtles.

Eggs and Incubation

The female deposits 60 to 100 eggs, about a third of which are too small to develop successfully, or lack yolk. The eggs incubate in the sand for 60-65 days. The hatchlings emerge from the nest with white striping along the ridges of their backs and on the margins of their flippers. Leatherback hatchlings are approximately 2-3 inches in length, with fore flippers as long as their bodies, and weigh approximately 1.4-1.8 ounces.

Threats

Leatherbacks are the most pelagic of turtles, feeding in the open ocean rather than near shore as other sea turtles do. Incidental capture primarily occurs in gillnets, but also in trawls, traps and pots, long lines, and dredges can result in injury and drowning. They can also become entangled in buoy anchor lines and other ropes and cables with the same results.

Leatherbacks mistake floating plastic bags or sheets for their favorite food, jellyfish. When swallowed, plastics can clog a turtle’s throat, esophagus, and intestines causing death. Ingesting any debris can obstruct the gut, lead to absorption of toxins and reduce the absorption of nutrients from their real food.

Predators such as cats, raccoons, skunks, opossums, coatis, and dogs eat the eggs. Hatchlings are preyed upon by mammals, sea birds, crabs, and large fish.  Sharks are a formidable predator throughout the life cycle of the Leatherback.

Although the flesh of this sea turtle is not eaten, the population has been threatened by egg- harvesting in Malaysia, Surinam, the Guianas, the west coast of Mexico, Costa Rica, and in several Caribbean islands. Leatherbacks were killed in the past for the abundant oil they yield, which was used for oil lamps and for caulking wooden boats.

Endangered Status

The Leatherback is considered endangered throughout its worldwide range. It is listed in CITES (Convention on International Trade in Endangered Species) as one of the most highly endangered animals worldwide as well as critically endangered (facing an extremely high risk of extinction in the wild in the immediate future) by the International Union for Conservation of Nature and Natural Resources.