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Tiny lobsters of doom: Why this invasive crayfish is bad news

Jul 27, 2017

A couple weeks ago, this guy in Kalamazoo County sees something a little odd: what looks like a tiny lobster, trying to cross the road.

He takes a picture of it, and sends it to the man who’s been dreading this moment: Seth Herbst, the aquatic invasive species coordinator for the fisheries division at the Department of Natural Resources.

“And as soon as I saw that photo, it was a clear as day that that was a red swamp crayfish,” Herbst sighs. But his day was only going to get worse. Later that very morning, he heard from another person in that same area – Sunset Lake in Vicksburg – who saw a red swamp crayfish walking around in their yard.

This was bad news.

“This is a species that we’ve really tried to actively keep out of the state,” Herbst says. “And when you see something like that, it’s typically going to be an infestation.”

Red swamp crayfish – which are delicious, by the way; they’re the same you kind boil and eat in Louisiana – look like mini lobsters. They’re bright red, with raised bumps.

But they’re not supposed to be in Michigan.

And when they do get here, they build deep burrows into lakes and rivers. And eventually, if you get enough of them, it can actually cause some pretty serious erosion.

“That’s the last thing you want to have happen, right, is your backyard wash away in the lake,” Herbst says.

“When these get to be abundant, there get to be quite a few burrows. And there’s studies out there that have shown that the burrowing capacity of these species has caused pretty significant shoreline erosion issues, as well as some infrastructure issues. In a couple cases, it’s actually caused some dam failures, because of the burrowing gets into some of that infrastructure and break it down.”

On top of that, red swamp crayfish can really mess up the food chain: they’re aggressive, and out-compete native crayfish, which means there are fewer of the native guys for predators to munch on. Plus, red swamp crayfish prey on small fish and fish eggs.  

We’re going to need more traps

Right around the time Herbst was hearing about red swamp crayfish in Kalamazoo County, Jim Francis was getting similar news. As the Lake Erie basin coordinator for the DNR, Francis’ team started getting reports about red swamp crayfish in a little retention pond right off the highway in Novi.

It’s really small, less than an acre. So for the last week or so, they’ve been setting traps. And boy, did they find red swamp crayfish.

“They caught 154 [red swamp crayfish] today,” Francis says of his team. “So that brings our grand total – and you know, we’ve only being doing it a week and a half – we’re up to 699.”

From one little retention pond.

Francis says since they’ve put the word, they’ve been getting more reports, with people sending in pictures of red swamp crayfish from all over the place – even on land.

“A golf course in Livonia,” Francis says, rattling off the recent list. “A fitness center in Novi, about a mile and half away from this [retention pond] site. Farmington Hills.”

Clearly, red swamp crayfish can spread fast, laying as many as 600 eggs.

We don’t know how they got to Michigan, exactly, though the DNR has some theories: fisherman using them as live bait (which is illegal now, Herbst says; you can be fined for possessing a live red swamp crayfish in Michigan.) Pets released into the wild. Even crayfish boils, where one stray guy wanders off.

What we do know is, because they’re so aggressive and because they’re able to burrow down so deep, they’re really hard to kill.

“Yeah, it’s a struggle,” Francis says.

It may not be possible to completely eradicate red swamp crayfish from Sunset Lake and other spots, DNR officials say. Right now, they’re just trying to control the population.

So if you see what looks like a tiny lobster, maybe at a lake, or just trying to cross the road, take a picture. Trap it, if possible, so it doesn’t spread to new water bodies (but be careful: like most crayfish, they do pinch. “Yeah, it does have the strong pinchers,” Herbst says. “We were out there last week and I was pinched by a few, and I can tell you first hand it’s not a pleasant experience.”)

If you do trap one, Herbst recommends putting them in your freezer, saying that’s a “humane” way to send them to the great Crayfish Pond in the Sky.

And report it to the DNR. There are a number of ways to do that: you can download an app, use an online reporting tool, or just take a picture and call or email Herbst. All those options are listed here.

Want to be sure if it’s really a red swamp crayfish? The DNR put up some good guidelines here.