Aggressive crayfish invades Yampa |

Aggressive crayfish invades Yampa

summit daily news
Special to the Daily The rusty crayfish

The Colorado Division of Wildlife is urging extra caution from all those fond of a good old-fashioned crayfish boil, after discovering a particularly aggressive variety of the small crustacean in northwest Colorado.

Division officials have identified rusty crayfish (Orconectes rusticus) in the headwaters of the Yampa River, prompting an immediate closure to the take of live crayfish from the waters in the Yampa River basin.

Crayfish, also known as “crawdads,” are a popular bait and food item. It is not uncommon to find people collecting the animals from Colorado waters.

Rusty crayfish are an aggressive species native to the Ohio River basin in the upper Midwest, but human activity has moved them throughout the northeast and into southern Canada. The discovery of rusty crayfish in the Yampa basin is a first in Colorado. Because of their large size and aggressive nature, rusty crayfish can impact fish populations by consuming small fish and fish eggs. The species can also negatively impact fish and spread unwanted aquatic plants by aggressively harvesting underwater plant beds.

“They’re not selective in their feeding, so they’ll eat whatever fish eggs are there and whatever plants are there,” said Elizabeth Brown, Division of Wildlife aquatic nuisance species coordinator. “Any native species is at risk for food-web disruption from these critters.”

Identification of rusty crayfish is extremely difficult and generally requires analysis of mature males. Because of the identification challenge, it’s unlikely anglers will be able to identify rusty crayfish from other crayfish found in the Yampa River basin.

To prevent the spread of rusty crayfish within and beyond the Yampa, the Division of Wildlife has issued an immediate order that prevents the removal of any live crayfish from the Yampa River and from any adjoining streams, lakes, canals or rivers.

According to Brown, there is considerable concern that use of the rusty crayfish as bait may facilitate its spread into other Colorado river basins.

Anglers gathering crayfish in the Yampa system must either immediately return the live crayfish to the water where it was captured or immediately kill the crayfish by separating the edible tail portion from the body of the crayfish. Once killed by separating the tail from the body, dead crayfish may then be transported for consumption.

Division of Wildlife aquatic biologists and specialists in aquatic nuisance species are mapping the distribution of rusty crayfish within the Yampa Basin and investigating whether they have spread to other waters in the state.

Anyone with questions or comments about rusty crayfish or the Yampa closure may contact Elizabeth Brown at (303) 291-7362.

Julie Sutor can be reached at (970) 668-4630 or

Support Local Journalism

Support Local Journalism

As a Summit Daily News reader, you make our work possible.

Now more than ever, your financial support is critical to help us keep our communities informed about the evolving coronavirus pandemic and the impact it is having on our residents and businesses. Every contribution, no matter the size, will make a difference.

Your donation will be used exclusively to support quality, local journalism.

For tax deductible donations, click here.

Start a dialogue, stay on topic and be civil.
If you don't follow the rules, your comment may be deleted.

User Legend: iconModerator iconTrusted User


See more