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News / Life / Pets & Wildlife

Aiming to save turtles in Columbia River Gorge

Endangered northwestern pond turtles, native to Washington, focus of collaborative rescue efforts

By John Harrison, Columbia Insight
Published: May 2, 2023, 6:03am
3 Photos
Restoring northwestern pond turtle populations will take time.
Restoring northwestern pond turtle populations will take time. (Photos by Columbia Insight) Photo Gallery

It’s February in the Columbia River Gorge. Cold and windy, with a hint of snow in the air.

About 50 miles east of Portland, on the Washington side of the river, the chill has brought a sense of winter quiet and serenity to a 64-acre property called Turtle Haven.

Here, a series of ponds provide habitat for northwestern pond turtles, a native species in Washington.

The property was acquired by Friends of the Columbia Gorge in 2018 and is closed to the public to protect the approximately 162 turtles that live here.

Northwestern pond turtles are much smaller than their marine cousins — 3.5 to 7.5 inches shell length and up to 2.2 pounds compared with shell lengths measured in feet for oceangoing turtles, which can weigh more than 200 pounds.

A candidate for listing under the federal Endangered Species Act, northwestern pond turtles currently are protected under state law, listed as endangered in Washington, “sensitive/critical” in Oregon and as a “species of special concern” in California

While many partners are involved in rescue and recovery efforts for northwestern pond turtles in the region, including the Woodland Park Zoo in Seattle, Oregon Zoo in Portland and Washington State Parks, at Turtle Haven it’s only the Washington Department of Fish and Wildlife, Friends of the Columbia Gorge and a contractor who removes bullfrogs, which prey on juvenile turtles.

The Turtle Haven partners, like their counterparts working in the Puget Sound area, are determined to reverse the turtles’ decline through rescue, recovery and intervention, including the use of turtle “hatcheries.”

It’s a daunting effort that highlights the fragile state of biodiversity in the Gorge as pressures from climate change, development and other human encroachment on native habitat mount.

Struggling species

Habitat loss, disease, overharvest, introduction of non-native plants and fish, and predation by bullfrogs have steadily driven northwestern pond turtles toward extinction.

Washington listed the species as endangered in 1993.

By 1994, only about 150 turtles remained in the wild at two sites in the Columbia River Gorge. In 1999, WDFW estimated that the total population of western pond turtles in Washington was just 250-350 — probably far fewer than it was historically.

“We believe that they once had been abundant along the Columbia as well the Puget Sound area, but it is difficult to know exactly,” says Stefanie Bergh, WDFW district wildlife biologist in White Salmon.

Thanks to various recovery actions, including a joint effort by WDFW and the Oregon Zoo, the population increased to about 800 to 1,000 by 2015, according to the 2017 Periodic Status Review for the Western Pond Turtle in Washington published by WDFW. (Northwestern pond turtles and western pond turtles are the same turtle, but recently two western species were recognized — the other, the southwestern pond turtle, is found in the southern half of California.)

“Recovering this species is challenging because of the turtles’ slow rate of growth, delayed sexual maturity, limited ability to disperse, complex habitat requirements and the high mortality of eggs and hatchlings,” according to the report.

While there’s been progress, Washington recovery plan goals that would allow a listing downgrade to “threatened” haven’t been met.

As of 2017, the statewide turtle population was too small to warrant re-listing. It was also considered reliant on continuing supplementation with hatchery-raised turtles. Hatching success in the wild remains low.

While the state hasn’t yet updated its report, the U.S. Fish and Wildlife Service plans to issue a species status report later this year that will be used to inform that agency’s federal listing decision.

Handling eggs, hatchlings

In Columbia River Gorge recovery efforts such as those undertaken at Turtle Haven, eggs aren’t collected from nests as soon as they’re laid, as is the practice in South Puget Sound.

“In the Gorge, we typically collect hatchlings from the ponds in the spring and bring them to the Oregon Zoo to over-winter and grow large enough to escape bullfrog predation,” says Bergh. “We release them a year after they are collected.”

There are four release sites in the Columbia River Gorge, all on the Washington side — Turtle Haven, another near the town of Lyle and two near Beacon Rock.

Many of the released turtles are fitted with passive integrated transponders (PIT tags) so they can be monitored over time, says Carly Wickhem, assistant district biologist for WDFW in Clark, Skamania and Klickitat counties.

In the Gorge, Washington Department of Fish and Wildlife biologists sample one of the four release sites each year. Given that pond turtles can live 30 years or longer, over time this monitoring provides a valuable history of the turtles’ survival rate in the wild.

At the South Puget Sound site, volunteers assist with tracking female turtles to their nests. Eggs removed from nests are taken the Woodland Park Zoo for incubation, hatching and rearing.

Shell disease

Recovery efforts for northwestern pond turtles in the Columbia River Gorge hit a speed bump in recent years in the form of pond turtle shell disease, an infectious fungal disease that weakens turtle shells.

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The disease likely doesn’t kill turtles outright. But by weakening shells it exposes them to deadly infections and impedes organ function.

WDFW biologists began noticing shell degradation in freshwater turtles in the Gorge in 2012.

“The disease is quite serious, and the fungus associated with shell disease in our turtles is being found in more turtle populations every year, including endangered Blanding’s turtles in the Midwest,” says Bergh. “We still do not know the exact impacts but are trying to learn more.

“Recently completed research we did found that even adult female turtles with severe shell disease laid eggs, so we think that the disease does not severely impact reproduction. Severe disease certainly causes some turtles to die, but we do not know the mortality rate. We have the disease in all six of the pond turtle populations in Washington.”

Before the shell disease emerged, experts were optimistic about turtle recovery. Now they’ve scaled back expectations.

“Because shell disease is novel, we have started from square one and have had to learn everything about it,” says Bergh. “The disease has definitely set back recovery, but we are still moving forward with the other things on our list while we learn more about the disease.”

Conservationists and government agencies may be fighting an uphill battle to protect and rebuild the northwestern pond turtle population in the Columbia River Gorge — Friends of the Gorge eventually intends to turn over Turtle Haven to the U.S. Forest Service — but rescue efforts remain infused with optimism.

As Bergh puts it: “We have a very challenging road ahead of us but we will continue our efforts.”

Columbia Insight’s reporting on biodiversity in the Columbia River Gorge is supported by the Autzen Foundation and Pacific Power Foundation.