About 50,000 threatened and endangered mussels are in the kill zone for the Hunter Station Bridge replacement project slated for 2016.
They have to be moved before the project can begin.
PennDOT has teamed up with the Pennsylvania Fish and Boat Commission, the Western Pennsylvania Conservancy, and conservation agencies from Ohio, West Virginia, Kentucky, and Illinois to give the mussels new homes.
On Monday, officials collected hundreds of northern riffleshell and clubshell mussels from the project site.
On Tuesday, 180 of those mussels – 90 of each species – were deposited in the bed of the Conewango Creek in Russell.
PFBC Fisheries biologists Jordan Allison and Nevin Welte, Ryan Miller of WPC, and Joe Snavely from URS Corp. waded into the creek and set up a rope grid blocked out into 12 square-meter boxes. Allison and Snavely, wearing snorkeling gear, placed five clubshell mussels in each of three squares, 10 in three others, and 15 in three more. Three of the squares were left empty as control locations. The second grid, for northern riffleshells, was placed about 10 meters downstream of the first.
GPS coordinates of the leading corner of each species-specific grid were taken and recorded to allow the officials to return to check on the animals.
“If all goes well over the next two years of monitoring, hopefully we can put 8,000 more mussels here,” PennDOT District Environmental Manager Autumn Kelley said.
Each mussel was marked with a transponder held in place by an epoxy. Before they were placed in the creek, Allison logged sex and size information for each mussel.
PFBC officials are able to track the mussels, from short range, using a device that looks like a metal detector. “We come back and monitor every year for recovery and survival,” Allison said.
The recovery rate is how many of the tagged mussels are found on return trips. Survival is how many of those are alive.
To be a suitable relocation site, a waterway has to have a high recovery rate and, among those, a high survival rate. Northern riffleshells and clubshells live for about 12 to 15 years, according to Allison.
Typically, mussels are relocated upstream, not into different bodies of water.
But moving 8,000 mussels is a big deal. In fact, it’s the biggest ever such move for District 1-0. “Seven thousand is the most we’ve ever moved,” Kelley said. “The populations are so big we can’t move them upstream without risking overpopulation.”
Mussels are filter feeders. Streams can only support a certain density of the animals.
The other states are also getting the mussels because northern riffleshell and clubshell have disappeared – extirpated – from those areas and they are hoping to reintroduce them.
PFBC found 10 possible sites within PennDOT District 1-0, the northwestern part of the state, to relocate mussels, according to Allison. Five of those locations were approved by the U.S. Fish and Wildlife Service.
If the test relocations, like the one Tuesday in Russell, are successful, almost all of the 50,000 mussels will be able to move to either Conewango Creek in Warren County or Shenango Creek in Mercer County.
If those sites are unable to handle 8,000 to 12,000 each, the other states’ agencies will be happy to take thousands back with them.
A second round of mussel relocations into the Conewango will take place in about two weeks.