Smokies living fossil disappearing: what can be done?

By Ben Cathey (WVLT 8) and Priyanka Runwal (Climate Central)

This story was produced through a partnership between Climate Central and WVLT in Knoxville.

Clad in wet suits and snorkel masks, Michael Freake and Jeronimo Silva wade through the cold waters of the Doe River flowing through Roan Mountain State Park. They’re in search of America’s largest salamander that spends its entire life in water, a creature found mostly under large flat rocks.

“You’ve really got to know how to look for them,” says Freake, a biology professor at Lee University in Cleveland, Tennessee, who is lifting large rocks and peering under them to find the eastern hellbender. “They’re not easily visible.”

Stout-bodied and growing up to two feet in length, this odd-looking and elusive amphibian is designated as endangered in Tennessee. Once abundant through much of their range in the Appalachian Mountains, hellbender populations have drastically declined over the last three decades.

For nearly 20 years, Freake has been surveying Tennessee’s rivers and creeks to find where hellbenders still survive and to understand how their populations are doing. “There’s still nothing quite like lifting a rock and seeing a giant enormous salamander just sitting there, staring back at you,” he says.Scientists don’t know for sure why these big salamanders are disappearing. Their main suspects include habitat destruction, water pollution, damming of streams and rivers, and harvest of hellbenders for sale as pets or to bait large game fish. But they’re also growing concerned by the heavier rains and increased river flooding, which are driven by heat-trapping pollution from fossil fuel emissions.

Amid these growing threats, many states, including Tennessee, are trying to revive hellbender numbers. Freake is also involved in these efforts, and is working to assess if the interventions are working.

“My collaborators and I are just determined they’re not going to disappear on our watch,” he says. “We will do everything we can to make sure they’ll be here for many generations to come.”

In search of the elusive hellbenders

Between 2012 and 2016, Silva, a graduate student at the University of Tennessee, and his colleagues found evidence of hellbenders in streams flowing through Roan Mountain State Park, among 64 places across the state. The proof arrived in hellbender genetic material lurking in water samples they collected at 284 locations across Tennessee.

The technique, called eDNA sampling, uses DNA in the water that had been shed from animals’ skin or poop. It’s an emerging tool to detect rare and elusive species for conservation.

Otherwise, it takes six- to eight-hour surveys to find one hellbender, Silva says.

“This (eDNA sampling) costs a lot less and saves a lot more time,” he adds. But the DNA doesn’t tell you how many hellbenders are in the area, how old they are, and if their population is healthy.

So Freake and his colleagues have been tagging hellbenders with implanted microchips to track their movement, growth, and survival. It could help the researchers identify the threats the local populations might be facing, whether it’s water pollution or habitat degradation or destruction. It may also help them understand why many young hellbenders aren’t making it to adulthood.

Declining numbers

A recent study found that male hellbenders may be increasingly cannibalizing their own young in areas with less forest cover. The scientists suspect that such degraded sites may have problems with water quality or chemistry or increased silt.

Anything going into the river—either covering up the rocks that shelter hellbenders and their eggs or diminishing water quality—could mess up some part of the giant salamanders’ lifecycle, Freake says, such as reducing the survival of hellbenders as eggs or in their larval stage.

Another concern is increasing instances of extreme rainfall. These deluges have grown more common with the rise in carbon pollution in the atmosphere from fossil fuels. The heavy rains can cause flash floods.

“We’ve had extraordinary rain events that scour rivers and move massive rocks and our feeling is we’ve had some significant [hellbender] mortality events during these crazy flood events,” Freake says. “They also tend to erode banks and put more sediments into the river.”

Increased sediment loads can suffocate eggs or fill up spaces where hellbenders live.

Other changes caused by carbon emissions, such as rising water temperatures, may also harm hellbender populations. For example, in one small experiment, researchers observed that hellbenders stopped eating for three months in the summer when exposed to higher temperatures.

“That means they’re going into breeding with poor body conditions and hungry,” says Brian Gratwicke, a conservation biologist at the Smithsonian Conservation Biology Institute who led the study. “If you’re starving, you want to eat your own eggs.”

Reviving populations

Hellbenders’ future survival may depend on research into each of these threats. Until then, several states, including Tennessee, are running head-start programs to restore hellbender populations.

The process involves collecting eggs or recently-hatched hellbenders in the wild and rearing them in zoos. Once the young ones mature to a size less vulnerable to predation by fish and other animals, they’re released back into the streams.

In Tennessee, the program commenced in 2015. Nashville Zoo staff have released head-start hellbenders into the wild every year since 2021. The Chattanooga Zoo released its first 30 captive-reared hellbenders earlier this year.

These salamanders’ survival and the overall success of the program remains to be seen. Other states had mixed results with similar efforts, says Eric Chapman, a hellbender expert and director of aquatic science at Western Pennsylvania Conservancy. “In some places it works well, not everywhere,” he says.

Over the next 10 to 20 years scientists in Tennessee will continue to monitor if the introduced hellbenders not only survive but are able to grow and reproduce. “If we get it right, there’s no reason why hellbender populations shouldn’t recover and do well in the future,” Freake says.