Rusty crayfish invades Colorado
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LYONS, Colo. — Jonathan Scupin and his wife had just finished a hike to Button Rock Mountain in September 2022 when they decided to dip their toes in a creek near the trailhead.
Scupin immediately noticed what looked like “a miniature lobster” staring up at him. He snapped a picture and uploaded it to iNaturalist, a site for identifying plants and animals.
Two and a half years later, Sophiane Nacer, an aquatic invasive species expert, saw Scupin’s post on iNaturalist and told him the crustacean looked like the rusty crayfish, a notorious species of crayfish native to the Ohio River basin that has colonized habitat throughout the central and northern United States.
Scupin shared his observation with Colorado Parks and Wildlife. A team sampled the stream and confirmed the presence of rusty crayfish.
Rusty crayfish can outcompete native species, destroy aquatic habitats and disrupt food webs.
Robert Walters, the invasive species program manager for Colorado Parks and Wildlife said that the agency doesn’t know how rusty crayfish were introduced to the Little Thompson.
Researchers point to anglers who release crayfish used as bait and the release of pets into the environment as likely means of introduction in other parts of the United States.
In Colorado, it is illegal to possess the rusty crayfish species.
Rocky Mountain PBS spoke with Robert Walters , the invasive species program manager for Colorado Parks and Wildlife to learn more about rusties and how the agency manages invasive species.
This conversation has been edited for clarity.
Rocky Mountain PBS: Tell me about the rusty crayfish
Robert Walters: The rusty crayfish is a crayfish species native to the Ohio River basin. It was first discovered outside of its native range in the 1960s and has had some pretty catastrophic impacts.
They typically have a black band around the tips of the claws, and more characteristically, they typically have a rusty patch on either side of the abdomen, which our native crayfish species do not have.
RMPBS: Why is the rusty crayfish an aquatic nuisance species?
RW: They're a much more aggressive crayfish species than our native crayfish species which means they are not nearly as good of a prey for some of our sport fish species as our native crayfish are. They eat small fish, insects and fish eggs, which are part of our aquatic food web. They eat aquatic vegetation beds that are critical for fish spawning prey, fish cover and for wildlife food.
RMPBS: Haven’t species been colonizing new habitats in this way forever?
RW: Species have been being moved around from location to location forever, but it's really in the last, let's say, 50 to 60 years that humans have become much more mobile than they ever were in the history of the world.
And as people become more mobile, they are also inadvertently moving more of these species along with them. So the rate at which they are being moved from one location to a new location far exceeds what it has ever been in the past. It's not a slow movement of these species, like you might see over the last several thousand years.
When all of a sudden there's a new species that is introduced into this environment and it starts mowing down all that aquatic vegetation that all of these other species are dependent upon, then they don't have an alternative, to be able to move into, to continue their life cycle.
RMPBS: Why should people care about the rusty crayfish?
RW: The impacts of the rusty crayfish are less obvious and more ecological. In a worst case scenario, it could have very significant impacts to our native and our sport fish, which does impact people's recreational opportunities
But less visible, these are out-competing our native crayfish species. And, maybe people don't think about our crayfish very much, but, once they're eliminated from a particular body of water, it is very unlikely that they are going to come back. And that's not something that we can easily reverse.
RMPBS: What’s next in the fight against the rusty crayfish?
RW: At this time, I don't believe we really have any intent to try to eradicate them from the West Fork of the Little Thompson River.
Our intent at this point is to first get out there and do some more surveys to better understand the current extent of this population and then really work at this from an educational perspective, to let people know that these things are out there and that they should be taking their own actions to help us stop the spread of these species, things like cleaning and drying all their equipment in between each and every use, and make sure that people are collecting, wildlife and moving it from one location to another, or releasing pets into the environment.
RMPBS: What can people do to stop the spread of aquatic nuisances?
RW: A big challenge in regards to this and many issues and natural resources is just getting people to understand that they, as an individual, can really take responsible action that's going to make a much larger impact than themselves.
One person may think, cleaning off my shoes isn't that big of a deal, but if every single person thinks that way, then nobody takes that action.
Type of story: Q&A
An interview to provide a single perspective, edited for clarity and obvious falsehoods.
An interview to provide a single perspective, edited for clarity and obvious falsehoods.
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