This story is part of our series, Wild Pennsylvania. Check out all of our stories here.
North American river otters, known as cute and playful swimmers, once lived in every major river system in Pennsylvania. But because of development, agriculture and industrialization, otters had largely disappeared from the state by the early 1900s. The success of their reintroduction in recent decades is considered an indicator of improved water quality.
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Scouting for evidence of river otters
The long, slender bodies and webbed feet of river otters help make them excellent swimmers, which is needed to catch fish, their main food source.
For people who want to see them, their habits can make it difficult. River otters are mostly nocturnal and can be hard to find in the daytime.
That’s why otter researcher Tom Serfass is training his two-year-old yellow Labrador retriever Merlin to find them.
“Merlin, find otter! Find otter!” Serfass called to the dog, who then ran ahead, toward the point where Tom’s Run joins the Conemaugh River in Blairsville, Indiana County.
Merlin started digging around a small pile of white-colored droppings and fish scales, evidence that the site was being used as an otter latrine, which is kind of what it sounds like: a bathroom.
“The vegetation tends to be knocked down,” Serfass said. “Because of the activity of the otters scratching, grooming, and peeing and defecating.”
The otter latrine where Tom Run meets the Conemaugh River. Photo: Julie Grant / The Allegheny Front
Serfass, who’s a professor of wildlife ecology at Frostburg State University in Maryland, has been charmed by otters since childhood.
“I’ve always liked otters, probably influenced by early Walt Disney shows that included the otter, or early National Geographic specials occasionally on TV when I was growing up,” he said
His mission to bring otters back to Pennsylvania began in the early 1980s when he was a graduate student. Now he works with his own graduate students. Over the past 20 years, they’ve set up cameras along waterways in Pennsylvania and nearby states to monitor otters and other wildlife at latrine sites.
“The animals gather there,” he said. “We have some really interesting footage of otters with remote cameras at these spots, sliding in the snow. It’s a fun place to have a remote camera.”
Nighttime video of a raccoon and otter by the Chesapeake and Ohio Canal, along the Potomac River in Maryland. Credit: Tom Serfass and Erin Geibel
Serfass had seen evidence of otters at this spot along the Conemaugh River before, and recently placed a camera to monitor their other activities.
“They’re also putting other scents down there,” he said. “And it’s a way for them to communicate with other otters through scent, through smell. So these areas get used fairly frequently, but they’re widely dispersed along the shoreline.”
What happened to Pennsylvania’s otters?
Otters once existed in every major river system in the state. According to the non-profit group American Rivers, otters are considered an indicator species; their presence is a sign of good water quality. River otters are reliant on a healthy fish population for food.
Otter remains have been found in the state’s Indigenous settlements, and the otter’s bravery is told in their traditional stories, according to Tom Keller, furbearer biologist at the Pennsylvania Game Commission.
River otters, with their torpedo-shaped bodies and strong jaws, are the largest member of the weasel family. Even coyotes, the state’s largest canine, leave them alone, said Keller. “They show very little fear, they defend themselves and they’re young very ferociously, and then of course they also will target prey that is much larger than them,” he said.
But, like many states, Pennsylvania lost most of its otter population as European trappers killed many otters for fur and westward development destroyed their habitat.
“We went from a primarily forested state to an agricultural state,” Keller said. “And then we start to see a lot of our water sources start to be dammed up for a variety of different mills and tanneries.”
Those tanneries, which processed animal hides into leather, polluted the rivers. So did the tin (plate) industry and the steel industry. And before 1977, it was legal for coal companies to abandon mines after taking what they wanted, which led to pollution draining into waterways, degrading more than 5,000 miles of rivers and streams in Pennsylvania.
That meant “very poor water quality over several centuries. We really lose what we would consider good otter habitat,” he said. “And of course we’re losing otters in general through some of that unregulated trapping. So with that came the fall of the otter.”
The only river otters left in the state were in the Pocono Mountains.
In 1952, the state Game Commission legally protected river otters.
Cleaning up the Conemaugh
Water quality was a major issue in the Conemaugh River watershed.
Upstream, the Stonycreek and the Little Conemaugh rivers were considered effectively dead due to acidic mine pollution: “the strength of vinegar,” according to a website dedicated to the Stonycreek. Old underground mine pools also leached iron, aluminum and manganese that “coated stream bottoms, choking the aquatic insects upon which life is based within mountain streams,” according to the website.
Watershed groups, along with the state and industry, built more than 24 mine drainage treatment systems to treat some of the 270 abandoned coal mine discharges in the Stoneycreek drainage.
“About 1.6 billion gallons of clean water comes out of those treatment systems every year. That’s a real contribution,” said John Wenzel, executive director of the Conemaugh
According to the Conservancy, more than 28 fish species can be found in the watershed, including the 2017 discovery of the Bluebreast Darter and the Tippecanoe Darter, considered threatened fish species in Pennsylvania.
“This is entirely due to the efforts to restore the upstream waters,” Wenzel said.
Reintroducing river otters in PA
The improved water quality, restored fish populations and state protections have meant otters could have a chance at a comeback.
In the 1990s and early 2000s, Serfass and a team released more than 150 otters across Pennsylvania, including 28 into the Youghiogheny River. Some of those are believed to have made their way to the Conemaugh.
“The success of the reintroduction populations is encouraging,” Serfass said.
It’s not known exactly how many otters live in the state today. The Game Commission receives reports from people who see otters along the rivers, from trappers, who are now allowed to capture one per year in the state, and Serfass’ cameras that monitor their populations near latrine sites.
“It feels very good for me and other conservationists who are interested in our native wildlife,” Serfass said. “So it’s a great environmental success story.”
Serfass credits the Clean Water Act and action taken to clean up waterways for the successful reintroduction of otters in Pennsylvania, which is similar to efforts in 22 other states that have reintroduced river otters.
He’s currently working with the Conemaugh Valley Conservancy to make otters a flagship species: a familiar, friendly, if sometimes ferocious face, to promote clean water initiatives.
