The Rusty crayfish can be identified by the dark brown spot on its side, orange and black pinchers and narrow thorax plate.
Invasive Northern crayfish were recently discovered in the Ashland Canal, marking the first documented existence of the non-native species in Oregon.
Following the discovery this spring, an Oregon Department of Fish and Wildlife survey found the crayfish established in Bear Creek, a tributary of the Rogue River, according to Rick Boatner, ODFW’s Invasive Species coordinator.
Once established, invasive crayfish are very difficult, if not impossible, to remove.
Boatner said Northern crayfish have the potential to duplicate in the Rogue River what the Rusty crayfish has done in the John Day River Basin. “Both the Rusty and the Northern crayfish are more aggressive than the native signal crayfish and soon become the dominant species in the area,” Boatner told the Columbia Gorge News.
Native to the Midwest, invasive populations of Northern crayfish already exist in California and Washington.
Oregon is the only state west of the Rocky Mountains that has a population of Rusty crayfish — it is believed Rusty crayfish were released in the John Day River near Mitchell by a school group about 42 years ago. “These crayfish have since taken over most of the river from native Signal crayfish. Signal crayfish are now displaced and rarely seen today,” Boatner said.
Although early predictions estimated the Rusty crayfish would reach the Columbia River in 2025, “I would not be surprised if they are already in Columbia River around the month of the John Day River,” he said.
In the future, the Rusty crayfish most likely will expand quicker downstream and slower upstream. “It will be interesting to see how long it will take the Rusty enter the lower Deschutes River,” he said.
Both the Northern and rusty crayfish are much more aggressive then the native signal crayfish.
As omnivores, the invasive crayfish can prey on signal crayfish, the eggs of salmon and steelhead, and consume native vegetation as well.
The Northern crayfish can survive low water levels by burrowing in mud and waiting for higher water, and can also travel over land to other water bodies.
The source of Northern crayfish in the Ashland canal is unknown. Anyone with knowledge of a crayfish release in the Ashland area is encouraged to contact Boatner at 503-947-6308.
Schools are reminded that classroom specimens cannot be released into the wild; a permit is required to import non-native crayfish into Oregon. Aquarium fish and other pets are also not allowed to be released. These actions can cause significant harm to Oregon’s native fish and wildlife species.
Native Signal crayfish can be found in freshwater throughout the Gorge.
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