Officials hope to stave off crayfish invasion

May 20—ASHLAND — A nonnative crayfish species that has the potential of over-powering native species in the Rogue River Basin has been found in an Ashland irrigation canal, and biologists hope they can stave off their initial invasion into Oregon.

About two dozen nonnative northern crayfish were found last summer in a Talent Irrigation District canal in Lithia Park, threatening the basin's native signal crayfish as well as the Rogue's native salmon and steelhead.

Northern crayfish are omnivores and can prey on signal crayfish as well as the eggs of salmon and steelhead laid in the mainstem Rogue and many of its tributaries.

The Oregon Department of Fish and Wildlife in the coming weeks hopes to find landowners to allow agency biologists to survey the TID's Ashland Canal for the unwanted crayfish.

Surveys are planned in the canal starting above Emigrant Lake and running to Lithia Park.

The department also plans to trap and kill as many northern crayfish as it can, but it won't consider poisoning the canal because it flows into Bear Creek, where native salmon, steelhead and crayfish reside, said Rick Boatner, ODFW's invasive species coordinator.

"If we can't get rid of them, we want to make sure we put a big dent in them," Boatner said.

Northern crayfish have been found in California and Washington, but this discovery is the first in Oregon.

Boatner said he suspects the crayfish were dumped into the canal by a school group studying them as part of a science curriculum.

That's what happened 42 years ago with rusty crayfish in the John Day River near Mitchell. Now rusty crayfish have overtaken signal crayfish in that basin and are predicted to reach the Columbia River by 2025.

Though Boatner has yet to discover a school group to point the finger at, "that's my best guess," in part because angling is banned in the canal and that makes their introduction as bait unlikely, he said.

Nonnative crayfish cannot be transported in Oregon without a permit.

The Rogue Basin already is home to two nonnative crayfish species. Ring crayfish already have out-competed signal crayfish for food and space throughout most of the signal crayfish's range here.

Also, red-swamp crayfish have been discovered in White City's Denman Wildlife Area.

Contact Oregon Outdoors columnist Mark Freeman at 541-840-9477 or email him at mfreeman@rosebudmedia.com.