Crayfish Corps Battle Invading Species In Valley Forge

There is sun coming through the forest along the banks of Valley Creek, glistening orange on the glassy surface and laying bare the harried comings and goings of the critters beneath.

Sunfish, minnows, larvae, crayfish moil between rocks and moss and small stands of vegetation, darting over the green creek bottom, no single critter visible for more than a passing flash, leaving the observer standing with but a memory before a clone comes to take its place.

But what may appear to be a clone is not always so. Take the rusty crayfish, for example.

This invasive incarnation of the species looks like the native crayfish, but has rust colored spots on its sides and has black bands on its claws. And the proliferation of critters with those spots could make all the difference for the health of Valley Creek and the surrounding ecosystem.

“The rusty crayfish is bigger, more aggressive, and eats up to twice as much as native crayfish in Valley Creek,” according to the National Park Service. “They are able to eliminate all other crayfish species through direct competition for food and shelter and increasing the susceptibility of native crayfish to predators. Rusty crayfish also may reduce the amount of aquatic vegetation, reduce aquatic insect populations and ultimately negatively effect large predators such as trout.”

Rusty crayfish are originally from the Ohio River Basin. Today they pose a threat to aquatic ecosystem across Pennsylvania.

They were brought to the region by bait fishermen, biological supply houses, aquaculture, and the pond and aquarium trade, the Park Service said.

Valley Creek runs through the heart of Valley Forge National Park, which has created a special task force to address the invading creatures.

The Crayfish Corps perform weekly crayfish removal from Valley Creek. To join them or to learn more, visit volunteer.gov, or email their Natural Resources staff.

Photos courtesy of the National Park Service.