Saving America’s Most Endangered Animals by WKSU’s Jeff St. Clair
The eastern U.S. has more freshwater mussel species than anywhere else in the world, and more than half of them are facing extinction
Ohio is the last home of one of the rarest animals in the world. It’s a formerly widespread freshwater mussel called the purple cat’s paw. Only about 20 of the mollusks are known to exist.
In this week’s Exploradio, WKSU’s Jeff St.Clair examines a species on the brink and how protecting it could help save Ohio’s waterways.
A species last stand
U.S. Fish and Wildlife Service biologist Angela Boyer is wearing a thick wet-suit, but she still goes heavy on the bug spray as mosquitoes swarm around us on an isolated stretch of Killbuck Creek in Coshocton County.
Boyer’s here to try and save one of the most endangered animals on the planet; it’s called the purple cat’s paw. She holds one in her hand. The size, shape, and bumps sort of look like cat toes, but inside the golf-ball-sized bumpy brown shell, the mother-of-pearl interior glistens with a luminous purple.
A wire cage sitting nearby in the water contains all the known living purple cat’s paws, each bearing a bright ID number painted on its shell.
Millions of years of evolution and specialization have come down to this, as Boyer counts eight females and 11 males, the sole survivors of its kind. This is a remnant population of a once widespread species. Boyer says there’s something special about this location, “and they’ve been able to survive here when we didn’t even know they were here.”
Outfitted with snorkels and wet suits, Boyer and two other malacologistsm, or mussel specialists, Greg Zimmerman and Steve Ahlstedt — steadily crawl along the creek, inspecting each crevice for the last of the elusive cat’s paws.
The rebirth of an extinct species
Mussel expert Michael Hoggarth teaches biology at Otterbein College near Columbus. Back in 1991, in the nearby Walhonding River, he found the first purple cat’s paw shell seen in Ohio since the Civil War.
“We thought it was an extinct thing and we found it!” he says.
But three years of searching for living animals came up dry until a random trip up Killbuck Creek led Hoggarth to a tiny population of purple cat’s paws clinging to life. Hoggarth says the fact that we have 20 animals of a species that we thought was extinct is good reason for hope. A captive breeding program is underway, but he laments, “We’re not out of the woods yet.”
Hoggarth says the eastern U.S. is a hotbed of mussel diversity, home to more species than anywhere else in the world. But two centuries of damming rivers, exploitation and pollution have sent dozens of the 300 mussel species here to extinction. More than half of the remaining species are threatened.
The once mighty mussel industry
Freshwater mussels used to be big business. Native Americans and settlers ate them. Mountains of discarded shells lined the banks of the Ohio River 100 years ago. Each was punched with holes that became pearl buttons.
In 1905, producers sold more than 130 million mussel-shell pearl buttons. But soon the mussel population crashed, and finally plastic replaced pearl-shell.
More recently, $50 million-a-year’s worth of freshwater mussels were ground into seeds to supply Asia’s cultured pearl industry.
Enforcing the endangered species act
Greg Zimmerman is vice president of EnviroScience in Stow. He uses heavy diving equipment to find and move rare mussels before work can begin on expensive construction projects. He says the Endangered Species Act, “can stop a bridge in its tracks; it can stop a … billion-dollar project in its tracks.”
That’s because nearly all bridge projects in the U.S. now require a mussel survey.Zimmerman says about one-in-10 involves relocating threatened species.
But that, he says, also helps preserve Ohio’s waterways because clean streams are needed as stable habitats when relocating threatened populations.
He says ultimately, “the state should want to get these things off the list so they don’t have to do so many mussel surveys.”
For the love of mussels
Meanwhile, back at Killbuck Creek, Zimmerman, Boyer and malacologist Steve Ahlstedt are still searching for more purple cat’s paws. Ahlstedt says larger mussels in Ohio can live 80 years or more, filtering the river and telling scientists like Ahlstedt how healthy the system is. He says, “there’s no better monitor out there.”
Ahlstedt says his passion for mussels hasn’t faded in nearly half a century of study. He says even recent federal funding cuts won’t stop him and fellow mussel lovers from spending hours face down in Ohio streams searching for hidden treasure.
Most of his and Zimmerman’s time spent searching for the purple cat’s paw is unpaid. He notes that they’re volunteering to, “try to save a species.”
Attempts at captive breeding of the purple cat’s paw have had mixed results. The 20 adults left will spend the winter, and hopefully breed, in Killbuck Creek. Scientists will return in the spring to continue efforts to bring them back from the brink.