Small Crayfish Can Cause Big Problems

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COLUMBIA - Crayfish, also know as crawfish or crawdads, are vital to natural water habitats across Missouri due to their versatility in the food web. But state wildlife officials say moving some of those crayfish to other parts of the state where they are not native can upset the balance in those areas.  The Missouri Department of Conservation is working to inform the public about the risk of dumping live bait and other methods that introduce the crustacean to off-limits areas.


In Missouri, the crayfish is one of the most predominant invasive species. There are 35 different species in the state, according to the Missouri Department of Conservation. However, there are also 20 documented cases of invasion, and that is causing some problems.

"We have been able to document, in many cases, declines in species, native crayfish species," said Bob DiStefano, a resource scientist for the Missouri Department of Conservation. "But if you look to other parts of the country that have investigated these problems, they have found that these invasive crayfish, again, eliminate native amphibians, reptiles, they prey on fish eggs and eat native fish, and they destroy fish habitat."

Each of the 20 cases of crayfish invasion was caused by people taking crayfish from their natural habitat and using them as bait in another part of Missouri. And often times, the fishers will dump the unused live bait into the waterway. That, however, is a mistake.

"People believe it's the right thing to do because they're releasing the animal to live, but it actually causes significant problems," said DiStefano.

It is illegal to dump live bait in Missouri, but DiStefano said 40 percent of anglers said they have dumped live bait at least once before.

While dumping bait is not legal, the use of crayfish as bait is. But with the issues of it being invasive, most tackle stores don't carry crayfish.

"It was illegal for a time, and then it was fine, but since it causes so many problems we don't carry it anymore," said Tombstone Tackle manager Adam Wolf.

Wolf also said most live bait people use is now shipped in from Arkansas.

DiStefano said once invasive crayfish are introduced into a habitat, it is almost impossible to eliminate them.

"Really, the key to battling crayfish invasion is prevention," DiStefano said. "And for that reason, our agency and other agencies across the country are gearing up public information and education campaigns to inform people about the dangers of releasing these organisms into the wild."