Leatherback Turtles

The leatherback turtle, the world's largest marine reptile, migrates thousands of miles each year.

by Samantha Chavez

From June to October, giant ancient reptiles swim en masse from Indonesia to Monterey Bay. They can be described as "living fossils" because relatively little about them has changed since the beginning of their lineage 70 million years ago. They’re leatherback sea turtles, our state marine reptile.

Leatherbacks, the largest living turtles, are found all over the world. The West Coast has its own distinct population that nests in Indonesia and crosses the Pacific to feed on jellyfish. They spend June through mid-October along the coast of California before heading to Hawaii and then back to Indonesia.

As their name implies, they lack the hard shell that other turtles have. Instead, their backs are tough, leathery and flexible, with ridges that run the length of the carapace and make it easier for water to flow by as they swim. Their large flippers and teardrop-shaped body make them even more hydrodynamic (think aerodynamic, but in the water). These adaptations help them cross the Pacific within a few months at speeds of up to 6 miles per hour.

These turtles can reach weights of 1,000 pounds and measure anywhere between 4 and 8 feet long from head to tail. Since a jellyfish is only about 5 calories (about as much as a stalk of celery), leatherbacks must eat some 200 pounds of jellyfish a day to fuel their arduous journey.

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The Pacific leatherback population has dropped by 95 percent since the 1980s. This dramatic plummet is puzzling, since the Atlantic leatherback population is stable. There is no one reason for this population drop. Instead it is a combination of factors that has led to the decline of the Pacific populations.

Leatherbacks return to the same beaches year after year to lay their eggs, making them easy targets for egg poaching. While there are efforts to protect the turtles and their eggs, poaching is still rampant, and sometimes it’s not humans. Feral pigs and dogs dig up nests and feast on the eggs. If the eggs survive incubation, the hatchlings are in danger from foxes, birds, or any other predator capable of snatching a tasty turtle snack as they make their awkward way to sea.

Once a turtle hits the open sea, it faces even more challenges. If you ever played Oregon Trail on a computer, you know how difficult it is to complete a 1,000-mile journey with so many obstacles in the way. Adult leatherbacks can be hit by ships, caught by fishing nets, or even choke on plastic bags or balloons they mistake for jellyfish. Since leatherbacks cross so many fishing zones, it’s probable that fishing nets entangle them or boats strike them often on their trip across the ocean. It’s hard for scientists to keep track of fatal boat strikes or fishing by-catch since so much of it occurs across the expanse of the Pacific Ocean. The turtles are difficult to protect because they require international conservation efforts, since they cross from country to country and out into the open sea.

If you want a chance to see the California state marine reptile, your best bet is to go out on a whale watching ship. You have a better chance of seeing the turtles off shore in the Monterey Bay as they swim in search of jellies to snack on. Don’t forget to celebrate Pacific Leatherback Sea Turtle Conservation Day on Oct. 15!

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