The U.S. may be worried about the election, coronavirus and murder hornets, but Belgium is already beyond all of those and is now dealing with a new threat … female mutant self-cloning crayfish in a cemetery! Too long for a movie title but plenty scary for a Halloween headline across Belgium, with many media sources adding “American” to the description because that makes it scarier … and it’s true.
“The crayfish is similar to the slough crayfish found in Florida in the US, with one important difference: it is parthenogenetic, which means it is able to reproduce without mating, and all offspring are female and genetically identical. That characteristic makes it easy for a large population to spring up quickly, which is what appears to have happened in Antwerp.”
The Brussels Times reports that marbled self-cloning crayfish (Procambarus virginalis) have taken over pools in the historic Schoonselhof cemetery in Antwerp where the bodies of 1577 British commonwealth soldiers killed in World War II are buried. They were investigated by Kevin Scheers from the Flemish Institute for Nature and Woodland Research, who immediately let everyone know he wasn’t there with a net and bucket to get rid of them.
“It's impossible to round up all of them. It's like trying to empty the ocean with a thimble."
These freshwater mutants were discovered somewhere around 1995, possibly in the Everglades, when people who kept crayfish as pets (have they tasted etouffee?) noticed that some female slough crayfish (Procambarus fallax) were reproducing with no male in the aquarium. Researchers confirmed that these were indeed an unexplained mutation – crayfish are not known to be parthenogenetic (reproduce without a mate and all offspring are genetically identical females) – and dubbed them the marbled crayfish (Procambarus virginalis).
Unfortunately, unscrupulous pet vendors seized upon this and made them popular. That was inevitably followed by unscrupulous pet owners tired of an overflowing aquarium (and not fans of etouffee) dumping them into local ponds. Marbled crayfish can live outside of the water, so the 10 cm (4 inch) crawled and ate their way across Europe after being introduced there in 1995. In 2014, the European Union instituted "a total ban on the possession, trade, transport, production and release” of marbled crayfish, but it was too late for the continent. They’ve also taken over Madagascar, which noticed them in 2018. They’re also banned in Idaho, Missouri, Tennessee, Michigan and the Canadian province of Saskatchewan.
“In Spain they tried some experiments with poison, but that is not permitted in Belgium.”
If poison isn’t an option and they’re reproducing too fast to capture, what can worried Belgium cemetery owners do? While all crayfish look alike, the Louisiana farmers who supply 95% of the crayfish consumed in the U.S. stick to Procambarus clarkii (red swamp crawfish – the most popular) and Procambarus zonangulus (white river crawfish). Could Belgian be persuaded to try marbled crawfish soups, bisques, boils and étouffées? They also are used for fishing bait (bass like them). It’s possible that nature could take care of them (with assistance from humans) with the deadly crayfish plague caused by the North American water mold Aphanomyces astaci. The plague doesn’t affect all species of crayfish, so it may have to be genetically modified for marbled crayfish – and that opens a whole new can of “What could possibly go wrong?” worms.
Should Belgians learn to live with the mutant self-cloning marble crayfish and hope they stay contentedly in cemetery ponds? Or should they be prepared for the scary movie “Cloning Crayfish Consume a Cemetery!” to go from fiction to documentary?