WARNING! Invasive crayfish should not be used as bait

Crayfish sold alive in pet shops, grocery stores, and live food markets are not intended for use as bait or release into lakes and rivers. Many are red swamp crayfish – an aggressive invasive species that is nearly impossible to eradicate.

In the Deep South, crawfish boils have long been popular at social gatherings. The crawfish, or crayfish as we tend to call them in the upper Midwest, are cooked alive in much the same way Red swamp crayfish description image.lobsters are with one exception—the crawfish are cooked with cayenne pepper, other spices, corn, and potatoes to provide a spicy one-pot feast.

Crawfish boils, and to a lesser extent other Cajun dishes like crawfish etouffee, have become so popular that an aquaculture industry has grown to meet the demand. The species of choice is the red swamp crayfish, which is native to Gulf Coast states and the lower Mississippi River north to the southern tip of Illinois. 

Live crayfish can be found at grocery stores and gas stations in most any small southern town, and they are also becoming more available in northern states. This might be encouraging for those of us who love spicy seafood, but there is one downside—red swamp crayfish is not native to the Great Lakes basin.

The red swamp crayfish is also highly aggressive and large relative to many native crayfish, which explains why this species quickly became more abundant than native crayfish in places like Pine Lake in Washington. It can also carry crayfish fungus plague and burrow into river banks, de-stabilizing shorelines and smothering in-stream habitat with sediment.

This is why the Michigan Department of Natural Resources officials were concerned when anglers were found using red swamp crayfish as bait off a west Michigan pier this summer. It is illegal to import any crayfish into Michigan for use as bait; however, red swamp crayfish remain available for sale. While it remains legal to buy live red swamp crayfish to eat, to study, or to display in an aquarium, this species could be a real threat to the environment if released into the wild. It could also cost taxpayers a small fortune to control.

In Wisconsin, red swamp crayfish were found in two ponds in residential neighborhoods a matter of miles from Lake Michigan. It seemed like a best-case scenario in terms of potential to eradicate the pests before they spread. The ponds were small and the crayfish apparently had not spread, so eradication was, at least theoretically, possible.

Unfortunately, the red swamp crayfish proved exceedingly difficult to combat. Over the course of two years, managers spent $250,000 in attempts to eliminate the crayfish from two ponds. Bleach was used in one pond to kill all aquatic life, but some red swamp crayfish were able to ride out the treatment in burrows. Another pond was drained and treated with an insecticide, and when that failed to eliminate crayfish, the pond was filled in.

Michigan anglers, and others, need to do their part to prevent red swamp crayfish from ever becoming established in Michigan waters. Red swamp crayfish may taste great, but they could be the next addition to the long list of destructive Great Lakes invaders if prevention efforts fail.

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