Highway to the Turtle Zone

(Note: This was an internal pitch for National Geographic. Each month, roughly 20 department pages are published in NGM print. Story pitches are submitted predominantly by staff. I wrote a large number of similar pitches proposing a variety of NGM-related topics, from declining turtle populations and new leopard species, to memory restoration and preservation using implanted silicon chips.)

Long line bycatch. Sea entanglement. Egg harvesting. Debris ingestion. High mortality rates among the newly hatched.

All contributed to the leatherback turtle’s 90+ percent population decline over the last two decades. But there’s promise for the endangered Dermochelys. A study done by George Shillinger, a biology doctoral candidate at Stanford University's Hopkins Marine Station, and a team of researchers that tracked leatherbacks indicates that turtles departing from Costa Rica follow a very distinct, narrow route to the South Pacific Gyre. The group monitored the turtles’ whereabouts through the Tagging of Pacific Predators program. This same method has been used to chart the trails of “white shark, bluefin tuna, black-footed albatross and elephant seal.”

Why the animals travel to this region is relatively unknown. It’s likely for deeper feeding beyond the 25-foot depth reachable by satellite imagery. A story by the Stanford News Service claims “the only data available are satellite images showing the color of the sea. Researchers interpret greener water to be richer in chlorophyll, which is considered the foundation for the ocean food chain. Thus, the relative abundance of chlorophyll is inferred to indicate the relative richness of a fishery. Satellite images show very little green in the South Pacific Gyre.” If the leatherbacks are going there to dine, the restaurant isn’t at the surface. And at six-feet, 2,000 pounds, the turtles have an evident appetite.

The authors argue that determining exactly where and when the turtles migrate, then suspending fishing in the ocean highways they travel, may help correct the loss. This seems more reasonable than trying to ban fishing in these parts completely. In Costa Rica—at Playa Grande National Park, one of the last vestiges of these turtles—villagers are paid to protect egg batches. An ecotourism market has emerged as a result. "Turtle tourism has emerged as an alternative economy and now there is a real focus on protecting this beach," says Shillinger. (Jellyfish, however, are hoping for an end to the leatherbacks’ 100 million year reign of terror over them.)

The driving factor in the leatherbacks’ life survival crusade is human involvement. Since the pools of the Pacific where the turtles operate cross international boundaries, a political will must exist to facilitate an agreement that will actually be enforced. If not, in the next 20 years, Dermochelys coriacea could experience a 100 percent slide.