Western Pacific leatherback turtle population dwindling

Numbers of those that feed in Central California waters declined by 80% in past two decades

SANTA CRUZ >> The number of leatherback turtles that feed in Central California waters has declined by 80% during the last two decades, according to new research out of the National Oceanic and Atmospheric Administration and the Moss Landing Marine Laboratories.

“They’re at risk of extinction in the Pacific Ocean,” said Scott Benson, lead study author and marine ecologist with NOAA.

Benson and his coauthors tracked Pacific leatherback turtles using video cameras, satellite and aerial survey data from 1990 through 2017.

The marine reptiles make an extraordinary migration, every three to five years swimming more than 6,000 miles from their Pacific foraging grounds in Oregon, Washington and California to Western Papa New Guinea. There, leatherbacks nest and lay eggs.

Researchers have long known that on Indonesian shores Pacific leatherback turtle populations are sinking.

But Benson and colleagues wanted to investigate if the same was happening at Central California coast feeding grounds.

Pacific leatherbacks swim to California to forage a common jellyfish — brown sea nettles — from the Monterey Bay area, north to Point Reyes. Those jellies are what sustain the turtles, who can weigh up to 1,300 pounds and measure up to 6 feet in length, Benson said.

“This is a species that has been on the planet for 70 to 80 million years in its present form. … It was around when the dinosaurs were around, it survived the ice ages, meteor strikes … it’s not a poorly adapted animal,” Benson said.

But in the last 40 years, its numbers have rapidly declined.

Benson and colleagues documented annually around 128 leatherback turtles feeding off the Central California coast from 1990 to 2003.

From 2004 to 2017, only 55 leatherbacks came to forage annually here.

The turtle is protected in U. S.

waters under the Endangered Species Act. Leatherbacks are also provided safeguards from accidental fishery bycatch through various regulations.

Benson said currently, entanglement and bycatch of leatherbacks occurring in U.S. waters is somewhat rare. And nowadays, those interactions are usually not fatal.

“I’ve often said the safest place for a leatherback turtle in the Pacific is in the Exclusive Economic Zone in the United States,” Benson said.

That’s an open expanse of ocean stretching 200 miles out from the coastline, where turtles are afforded protections under the Endangered Species Act.

But leatherbacks have complex and lengthy migration patterns that take them through international waters. And the regulations that protect them in the U.S. don’t apply there.

“Because leatherbacks are a transboundary species you have to have this level of international cooperation that we don’t have right now to ensure the recovery of the animal,” Benson said, comparing the challenge to the worldwide issue of climate change.

Other issues impacting the species are poor conditions on Indonesian nesting beaches and poachers.

There are some things Santa Cruz residents can do, though.

For one, Benson said, if deciding to eat swordfish, make sure it’s certified caught in the U.S. Secondly, limiting your plastic footprint can help too, as Pacific leatherback turtles can sometimes mistake plastic items as prey.