When my children were young, they used to like to go to the DuPage River and catch crayfish. My recollection is that these critters were small. The kids had a good time getting their feet wet, plucking the tiny lobster-like crawlers from the water, examining them and the throwing them right back in the river. I thought they were ugly (the crayfish, not the kids) but never really thought much of them otherwise.
Today I read in the local newspaper that a non-native species of crayfish has gotten into one of the ponds in a nearby nature preserve. The Wisconsin DNR is planning to treat the pond with a toxic bleach-like chemical, which will destroy the creepy critters as well as anything else in the water. WDNR wants to rid the pond of these invaders, which are not hazardous to people but have the potential to destroy other native plants and animals.
The newspaper article said that this small pond is one of the first places in Wisconsin that the species has been found and that it may have gotten there because someone who had it as a pet dumped it there. In southern states, they are farmed as seafood, and they are also sold as pets or for educational purposes.
I did some snooping around and learned that the invaders, officially called a red swamp crayfish, were first discovered and then confirmed here in Wisconsin last summer. They are native to the Southeastern U.S, can grow to about 8 inches long, and like to eat plants, snails, and especially the eggs and young of fish and amphibians. If they move from ponds to streams and rivers, they could then get into Lake Michigan, and although I did not find much about what that would mean, they like to eat fish eggs and young fish so it cannot be good news.
Asian carp may get all the press and be the superstars of invasive species, but they are by no means the only invasive species we have to worry about. Now in addition to various mussel species and carp, we can add crayfish to the list of horrible things that can get into the lakes. Methods to contain unwelcome visitors range from electric barriers to poisoning the waters. Which is worse – the invaders or the methods to prevent the invasions? Somebody help me out here. I don’t know the answer, and although I am not suggesting we don’t try as hard as possible to maintain the ecosystem of our freshwater, it seems like there is always some creature that is smarter than we are.
Aggressive eight-inch crayfish that like to eat fish eggs probably like to eat the toes of little children, too. Why do I think we are going to hear more about them is in the future? (I mean the crayfish, but maybe the children, too.)