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Rusty crawfish found in Colorado

Vernal — News from Colorado is capturing the attention of biologists, anglers and water managers in Utah.

Rusty crawfish
Rusty crayfish have been found in Colorado.

Photo courtesy of the United States Geological Survey

The Colorado Division of Wildlife (CDOW) recently reported finding rusty crayfish in the Yampa River Basin.

The Yampa flows into the Green River in northeastern Utah.

In response to their discovery, the CDOW has issued an order prohibiting the removal of live crayfish from the Yampa River and any streams, lakes, canals or rivers that adjoin it.

Utah already has a similar rule for the crayfish species found in the state.

In Utah, live crayfish are on the state's prohibited list. Live crayfish cannot be collected, imported or transported anywhere without a valid Certificate of Registration from the Utah Division of Wildlife Resources.

Anglers may use crayfish as bait, but only at the same water where the anglers collected them. Crayfish caught for human consumption must be dead before they're removed from the water where they were harvested.

A major threat

The rusty crayfish is an invasive species native to the Ohio River drainage. It's had negative effects on fisheries and aquatic ecosystems in the Great Lakes region, in at least 17 other states and in southern Canada.

Elizabeth Brown, invasive species coordinator for the CDOW, says the discovery of rusty crayfish in the Yampa Basin is the first time the species has been found in Colorado.

Rusty crayfish are large and aggressive. They can affect a fishery or an aquatic ecosystem two major ways:

  • They consume a wide variety of forage that fish depend on. This forage includes small fish, fish eggs, vegetation and aquatic invertebrates—including many insects and other forage species that are highly desired by fish. By consuming aquatic plants and plant beds, they remove critical forage and cover needed by the fish and the invertebrates on which the fish feed.
  • Their aggressive nature will also displace native crayfish and other aquatic species from their hiding places—making them more susceptible to predation by fish. This won't affect the fish much at first because their usual prey will be easier to catch. Later, however, they'll have to deal with the rusty crayfish, which can rotate its large claws over its back to defend itself.

Why rusty crayfish are spreading

People have moved the rusty crayfish well outside its native range.

No one has found the rusty crayfish in Utah. But Colorado's recent discovery indicates the crayfish is moving westward. Crayfish are moved several ways:

  • as bait transported by anglers from one water to another or bought by anglers commercially and then introduced to a water,
  • through school supply houses by teachers who raise the crayfish in class and then give them to students or release them into a nearby water,
  • dumping from home aquariums,
  • intentional releases by misguided anglers wanting to increase forage for their favorite fish, and
  • intentional releases by commercial harvesters who want more waters in which to catch crayfish that the harvesters can later sell

What you can do

Everyone in Utah has a responsibility to keep rusty crayfish and other invasive mussels, fish, snails, wildlife and plants from spreading into Utah's waters and wild areas. Doing so is easy. It comes down to two simple things:

  • Never move any species or species parts—plant or animal—from one body of water to another body of water, or from one wild area to a different wild area.
  • Make sure you clean, drain and dry your boat and any recreational or fishing equipment that's come in contact with the water before placing it in the water again.

This simple clean, drain and dry process is available at wildlife.utah.gov/mussels/decontaminate.php

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