For creatures that might move 10 feet every six months or so, these are world travelers.
On Wednesday, officials from agencies in Ohio, Illinois, and West Virginia working in partnership with PennDOT, the Pennsylvania Fish and Boat Commission, and the U.S. Fish and Wildlife Service, gathered about 3,700 endangered northern riffleshell mussels from the Allegheny River in Forest County for relocation.
With the 1,051-foot-long, structurally deficient, steel truss Hunter Station Bridge in Tionesta to be replaced in 2018, agencies are doing their best to find new homes for the endangered mussels that are in the project area.
Photo courtesy of Jim Carroll, PennDOT
Flexing some mussels
Divers with various organizations from four states sort mussels collected Wednesday in the Allegheny River near Tionesta. Agencies working with PennDOT and the Pennsylvania Fish and Boat Commission on a mussel relocation project include: United States Fish and Wildlife Service’s Pennsylvania, Ohio, and West Virginia Field Offices and Ohio River Islands National Wildlife Refuge; the Columbus Zoo and Aquarium’s Freshwater Mussel Conservation Facility; Illinois Natural History Survey; Illinois Department of Natural Resources; and West Virginia Department of Natural Resources.
When the bridge replacement project is under way, coffer dams and causeways - temporary structures built on the river bed during construction - would kill mussels living there. Also, the old bridge, which carries a daily average of 1,235 vehicles across the river on Route 62, will be dropped, creating a good chance that any mussels beneath it would be killed.
"We're trying to remove the mussels from the bridge area," Jordan Allison, Pennsylvania Fish and Boat Commission fisheries biologist, said.
According to PennDOT Spokesman Jim Carroll, there were several agencies willing to help out. "There are groups from these and other states working with the U.S. Fish and Wildlife Service on an ongoing basis to try to strengthen populations of endangered mussels and establish new populations in areas where they once existed, but are no longer there," Carroll said. "These groups have collected mussels from the Allegheny before and will continue to do so."
Those officials, wearing scuba gear, swam through the impact area identifying northern riffleshells. They put the mussels in mesh bags. Back on shore, they transferred them to coolers filled with aerated water for transport to their new homes.
"We may have healthy populations of mussels in the Allegheny and French Creek, but we are one of the few places that have any of some species," Carroll said. "Some endangered mussel species no longer exist in about 90 percent of their original range."
"One group I talked to was the Columbus Zoo, which is working on mussel reintroduction in conjunction with Ohio State University," Carroll said.
Projects in Ohio had received about 3,200 mussels earlier this year and another 3,000 in years past.
"One of the volunteers from Illinois told me they will try to introduce the mussels in a waterway where they have not existed for 100 years," Carroll said.
Agencies can't just sign up to collect mussels and drop them in a river somewhere to see if they live.
Instead, in areas where the mussels used to live, if conditions are appropriate, agents can be approved from a test group.
"We don't want to do a large-scale relocation without knowing whether they're going to survive or not," Allison said.
Pilot programs involving perhaps 50 mussels go first.
"If they find that they're able to have those individuals live, they're able to take a larger population," Allison said.
Spreading out the mussels is a way to make sure one catastrophic event in a particular location doesn't lead to the extinction of any species, Allison said.
Each endangered species has a species recovery plan, he said. A major part of the program is relocation.
Saving mussels isn't just a matter of making sure a species doesn't disappear. "They're important because they're like the canary in the coal mine. They're extremely good indicators of water quality," he said. "They provide us with an early warning detection system."
"Some of these are capable of filtering several gallons of water per day," Allison said.
The northern riffleshell is the primary subject of the current mission, but there are several other endangered or threatened species in the area including clubshell, snuffbox, sheepnose, and rayed bean.
"Illinois took 200 clubshell to start their pilot study," Allison said. Those mussels are headed for the Vermillion River.
The section of the Allegheny to be impacted by the bridge replacement job is teeming with mussels.
"We estimate there are about 25,000 northern riffleshell mussels and about 58,000 threatened and endangered mussels of all species in the area that would be most impacted by a bridge replacement project," Carroll said. "If you go upstream and downstream from the bridge a bit farther, there are probably a half million mussels of various species."
That estimate comes from studies conducted in the area in which divers count the mussels in sample areas and use those numbers to approximate the number in a whole stretch of river.
"This population in the Allegheny River is the most extensive population known in the world," Allison said. "The densities here are very high."
In other places, however, mussel numbers have dwindled. "States and provinces in which the northern riffleshell can be found include: Illinois, Indiana, Kentucky, Michigan, Ohio, Pennsylvania, West Virginia, and Ontario," according to a release from the Fish and Boat Commission. "However, in recent years, the number of northern riffleshell populations outside of Pennsylvania has decreased significantly."