From the Field

Saving the Pacific’s Most Endangered Leatherback Sea Turtles

A leatherback sea turtle swimming offshore of Raja Ampat, Indonesia. © Jeff Yonover / TNC

Sand crunches beneath bare feet as the rangers walk along the beach. Voices muffled, they scan the tide line with flashlights, looking for the wide tire-tread marks left behind by a female leatherback sea turtle.

The turtles that nest on this narrow beach are some of the most endangered leatherbacks in the world. But with little data about this population, scientists are hard-pressed to understand and mitigate threats to these turtles.

The rangers walking the beach tonight are part of a new monitoring effort, led by The Nature Conservancy, to gather information about the Western Pacific leatherbacks nesting in the Solomon Islands. And, for the first time in the country’s history, female rangers will join the conservation efforts.

Leatherbacks of the Western Pacific

Sasakolo beach looks like any other in the South Pacific; a strip of sand buttressed by coconut palms, low green hill rising in the distance. Located near Kafulapu community, this unassuming patch of land is one of the most important — and perhaps the largest — leatherback nesting beaches in the region.

From October through February each year, a dozen or so turtles emerge from the waves each night, hauling themselves scooch by scooch up the beach. They measure up to 6.5 feet long and weigh up to 1,300 pounds, dwarfing the rangers that look on from a distance.

Leatherbacks, like many other turtles, are long-distance ocean travelers. The same turtles that can be seen by divers off the coast of southern California cross the width of the Pacific Ocean to nest on the narrow, palm-fringed beaches of the Solomon Islands.

Sasakolo beach seen from the air. © Robert Taupongi / TNC

While the species is considered vulnerable at a global level, the subpopulation in the Western Pacific are faring far worse than others. Scientists estimate that this population has declined to just 1,400 breeding adults, leaving them critically endangered.

Without action, it will continue to get worse. By 2040 years, scientists predict that the Western Pacific subpopulation will be whittled down to just 100 nesting pairs each year. “They’re crashing hard, and it’s going to continue unless we arrest the decline,” says Peter Waldie, a fisheries scientist with The Nature Conservancy.

But conservationists can’t protect these turtles without data: where, when, and how often they nest, how many hatchlings clamber from sand to sea, and how many nests are washed away by rising tides.

Potential rangers examine a data collection sheet at the training. © Robert Taupongi / TNC

Collecting Data, One Turtle At a Time

The Nature Conservancy is partnering with the Solomon Islands government to start gathering these data from critical nesting beaches in Isabel Province, with funding from the US National Oceanic and Atmospheric Administration (NOAA).

In late 2021, TNC-trained rangers resumed monitoring at Sasakolo for the first time in more than 10 years. And, in a first for the Solomon Islands, women rangers will now join the monitoring program.

Melanesian culture still has strict gender roles. Women are often limited to domestic duties, while men dominate jobs that require technical expertise and make the majority of the decisions for family and community. But as conservation organizations like TNC build gender equity requirements into their work, the tide is slowly shifting. “There has been a lot of progress with several women’s organizations coming in and talking to communities about getting women into decision making,” says Madlyn Ero, who leads TNC’s gender equity work in the Solomon Islands.

TNC staff lead a ranger training workshop. © Robert Taupongi / TNC

Five women attended TNC’s turtle ranger training in November, and three of those women are now working as rangers at Sasakolo. Ero and her colleagues are consulting with the community to learn what else they can do to facilitate more female rangers to join. The goal is to build the program to a 50/50 gender parity.

Work as a ranger means long nights walking the beach by torchlight, searching for the tell-tale signs of a nesting turtle: tire-like tracks up and down the beach, or a very large, dark lump of heaving, snorting, salt-covered turtle in the dark.

When they find a female, the rangers wait patiently while she digs a hole in the sand and lays her clutch of eggs. If they get the timing right, rangers can count the number of eggs in the nest as they drop from her cloaca. Then they mark the location, before gathering data about the female turtle and attaching a small metal identification tag to her flipper.

Rangers on these patrols also check the older nests, looking for signs of hatching or disturbance. Solomons Islanders can legally harvest turtle eggs for food, and many nests are predated by people.

Rangers patrolling the beach at night. © Robert Taupongi / TNC

The Sasakolo rangers also record data on the number of nests lost to beach erosion and tidal inundation. At Heavo, another monitoring beach in the island’s south-east, rangers are forced to relocate more than 60 percent of turtle nests to protect them from inundation. Early data suggest that a similar problem also occurs at Sasokolo, as climate change increases storm surges and high tides. “If that’s the case, we can build a retaining wall to make an artificially raised beach, and then move vulnerable nests above the high tide mark,” explains Waldie.

Eventually, Waldie and his collaborators at NOAA hope to incorporate satellite tagging at Sasakolo to learn where these turtles travel during their non-breeding years. Similar research from the Arnavon Islands, a significant hawksbill nesting site nearby, discovered that those turtles migrated as far as Australia’s Great Barrier Reef. Another study found a leatherback tagged off the coast of California migrated across the entire Pacific to the Solomon Islands.

Rangers collect data and tag a nesting leatherback. © John Pita / TNC

The Population Perspective

All of this data will feed back to TNC and NOAA, who will use Sasakolo as an “index beach” to better understand what is happening to the Western Pacific subpopulation.

“The tricky thing with turtles is that they are a very long-lived species, so you need long-term data for 9 to 10 years to really understand a population’s nesting trend,” says Irene Kelly, NOAA’s sea turtle recovery coordinator for the Pacific Islands. She says that most of the data on the Western Pacific sub-population comes out of Indonesia, with very little data available from Papua New Guinea and the Solomon Islands.

“The Western Pacific leatherback turtle population is a difficult one to study because nesting areas are so remote and logistically challenging to access,” she says. “But the more we look, the more we learn.”

Having laid her eggs, the female leatherback returns to the sea. © John Pita / TNC

Data on how often females return to nest, the number of nests laid, and hatchling survival rates will all feed into NOAA’s population models and status assessments. Those, in turn, will help the agency better protect leatherbacks by refining management measures to mitigate interactions between turtles and U.S. commercial longline fisheries. They will also inform NOAA’s work with international governments and partners to help conserve the species.

Kelly emphasizes that, at the end of the day, NOAA alone can’t save the Western Pacific leatherbacks. “We need and rely on partnerships,” she says. “We don’t want to just collect the data and leave, that’s not sustainable or realistic. We need to engage with communities and local partners to build capacity so they have ownership over the project, which builds longevity.”

“We’re fighting against extinction at this point” Kelly adds. “But there’s still hope and enough turtles, we believe, that the Western Pacific leatherback population can recover. We haven’t hit the tipping point, yet.”

 

Justine E. Hausheer

Justine E. Hausheer is an award-winning science writer for The Nature Conservancy, covering the innovative research conducted by the Conservancy’s scientists in the Asia Pacific region. She has a degree from Princeton University and a master's in Science, Health, and Environmental Reporting from New York University. Justine's favorite stories take her into pristine forests, desolate deserts, or far-flung islands to report on field research as it's happening. When not writing, you can find her traipsing after birds, attempting to fish, and exploring the wild places around her home in Brisbane, Australia. More from Justine

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