Olive Ridley Sea Turtle

One of the species of magnificent sea turtles that nests along the Riviera Nayarit coast is the Olive Ridley.  While it is the smallest of the marine turtles, weighing up to 100 pounds (45 kilograms) and reaching only about 2 feet (65 centimeters) in shell length, it is never the less a sizeable critter.  The photo shows its distinctive heart shaped shell. The Olive Ridley turtle is named for the generally greenish color of its skin and shell, or carapace. It is closely related to the Kemp’s Ridley, with the primary distinction being that Olive Ridleys are found only in warmer waters, including the southern Atlantic, Pacific and Indian Oceans.

Sadly, these gentle sea creatures were once slaughtered in the hundreds of thousands for meat and leather. Olive Ridleys have yet to recover from centuries of over-exploitation. While the species has a wide range, the number of important breeding sites is very restricted, including those in Mexico. Due to the dwindling nests, efforts to protect their major beaches are vital. On the map, the yellow indicates this specie’s nesting range. The illegal harvest of Olive Ridley eggs in the Mexican and Central American region continues because the indigenous people believe the eggs are an aphrodisiac. There is also a high mortality of adult turtles due to coastal fisheries that do not yet use Turtle Excluder Devices (TEDs) in their nets.

These turtles are solitary, preferring the open ocean. They migrate hundreds or even thousands of miles (kilometers) every year, and come together as a group only once a year for the arribada, (Spanish for ‘arrival’,) when females return to the beaches where they hatched, lumber onshore, sometimes in the thousands, to nest. Arribadas can contain thousands of egg-bearing females that come ashore at the same time to lay eggs. A wonderful adaptation is that the marine turtle’s eggs are ping pong ball shaped, soft-shelled, and are papery to leathery in texture. These features ensure that the eggs do not break when they fall into the egg cavity in the sand.  Conversely, it means many predatory animals can easily rip them open to eat the embryos.

Olive Ridleys have nesting sites all over the world, on tropical and subtropical beaches. During nesting, they use the wind and the tide to help them reach the beach. Females lay about 100 eggs, but may nest up to three times a year. The nesting season is from June to December.

The Olive Ridley is mostly carnivorous, feeding on such creatures as jellyfish, snails, crabs, and shrimp. They will occasionally eat algae and seaweed as well. Hatchlings, most of which perish before reaching the ocean, are preyed on by crabs, raccoons, pigs, snakes, and birds, among others. One of the saddest events I ever witnessed (in the 1980s) was seeing a nest of sea turtles hatch and scurry towards the ocean only to have the sea birds swoop down to eat them.  I know this is the natural order of things, but it was tragic to see only about a dozen reach the surf and swim away. And that was only those eggs that survived being plundered in the nest that were able to hatch!  This is why present conservation practices include digging up and relocating eggs to a guarded site, and releasing the turtle babies under protection. The adult Olive Ridley are often eaten by sharks or drowned in long line and commercial net fishing. It’s not easy being a sea turtle.

Though the Olive Ridley is widely considered the most abundant of the marine turtles, by all estimates, it is in trouble. In 2005, the Caribbean Conservation Sea Turtle group tabulated the worldwide population of nesting females at about 800,000, but its numbers, particularly in the western Atlantic, have declined precipitously. The United States lists the western Atlantic population of Olive Ridleys as endangered and all other populations as threatened. The Mexican Ministry of the Environment and the Mexican Navy has taken steps in recent years to protect the species.