The invaders weren’t traveling so much by the dark of night as under the cover of ice. Packed inside coolers, the wily interlopers would soon infiltrate graduation parties, charity fundraisers, and backyard picnics across the Centennial State. At least, that’s what would’ve happened if Ty Petersburg hadn’t flashed his badge and ruined all the delicious fun.

As assistant chief of law enforcement for Colorado Parks and Wildlife (CPW), Petersburg was tipped off in February 2023 about a person who was moving banned wildlife into Colorado. When CPW stopped this person—who had been yo-yo-ing back and forth from Louisiana—to issue a ticket for transporting pounds of red swamp crawfish and selling them pop-up-shop style, the state wildlife management agency had no idea its investigation would uncover not just one lawbreaker but dozens of them scattered across the state. The smugglers were restaurateurs, seafood distribution company owners, and regular Coloradans, all of whom were merely looking to laissez les bons temps rouler.

That Louisiana French phrase translates into English as “let the good times roll,” and it can be heard most often in New Orleans during Mardi Gras. But the calque is also voiced during the spring and early summer when Southerners typically throw crawfish boils, casual patio parties where copious amounts of the red shellfish are liberally seasoned, cooked alive alongside corn on the cob, red potatoes, and sausage, and then dumped out on paper-covered tables for an eat-with-your-hands feast.

It turns out, though, the good times have, over the years, been rolling out of the Deep South all across the country, including to Colorado, where, since 1991, red swamp crawfish and white river crawfish have been illegal due to ecological concerns. Since then, importing, transporting, or possessing live crawfish—sometimes called crawdads or mudbugs in places south of the Mason-Dixon Line—in Colorado has been punishable by a fine of up to $5,000 for importation and $35 per animal for possession. The bill for any ecological damage incurred by releasing the live shellfish into local waterways could conceivably reach six digits.

A Colorado native, 44-year-old Petersburg didn’t even know crawfish boils existed until early last year. After following up on that February 2023 tip, however, Petersburg realized how pervasive these fishy fetes really were. Local restaurants were ordering large shipments, with a single Denver-based distributor importing between 8,000 and 11,000 pounds every week for about half of the year. People were mail-ordering them to be delivered overnight to their doorsteps in Hilltop and Washington Park for backyard boils. A few entrepreneurial individuals, like the one CPW law enforcement stopped, were even buying crawfish from farms in the Southeast, road-tripping them to Colorado, and selling them at makeshift stands or out of trunks full of ice until they ran out or the crawfish spoiled. Every one of them was breaking the law. The thing was: Most of them had no idea.

The connoisseur’s choice for a killer boil is the Louisiana red swamp crawfish, which are slightly smaller than the average adult hand and dark red with raised red spots. They’re native to the rivers, lakes, swamps, and marshes of Southern states such as Alabama, Louisiana, and Texas, but they’ve been found squatting in waterways across the country and even on other continents. They’re remarkably well-adapted to handle temperature fluctuations and swings in salt content.

Once they’ve relocated, the crustaceans harass local fish, eating their eggs and young and stealing their insect meals off the veritable floating dinner table. They are also voracious consumers of aquatic plants, snails, and young amphibians. Their extensive burrows—single- or double-occupant domiciles, often with a chimney and the equivalent of an indoor pool—can damage dams and irrigation systems and even collapse shorelines.

In 2009, for instance, Wisconsin’s Department of Natural Resources was alerted to a six-acre pond ringed by a few dozen houses where people were reporting “giant red lobsters” wandering around on the lawns. In two ponds in that neighborhood and a third closer to the Illinois state line, the Department of Natural Resources found thousands of red swamp crawfish. Because the area’s watershed drains into Lake Michigan, the department was concerned about the aquatic life in all of the Great Lakes. The mudbugs had to go.

Over three months, state biologists and other personnel trapped and removed 2,143 crawfish from the biggest pond. Trapping got many, but not all of them, so state workers donned hazmat gear and tried bleach and insecticides—repeatedly. They didn’t work.

The only solution was to fill in the ponds. Two of the three were filled with clay and stone and other materials. At the third, trees and brush were pruned away, the bank was scraped to bare mud, and a layer of heavy fabric and stone buried the remaining aquatic residents while they overwintered in their burrows. After more insecticide, the department finally detected no crawfish. In total, Heidi Bunk, a lakes biologist with the Wisconsin Department of Natural Resources, says the 11-year effort cost at least $800,000.

Spending more than three-quarters of a million dollars gave state game wardens good reason to investigate how the invasive crawfish ended up in the ponds in the first place. They interviewed area residents and found out the six-acre pond had been stocked by people hoping to have endless boils. The pond closest to Illinois suffered what Bunk calls the “free Nemo syndrome”: A teacher released the shellfish after a science project because she couldn’t bear to kill them. But crawfish boils are a problem, too, Bunk says, adding that people seem to leave live crawfish to hang out in a wading pool and then return to find dinner has crawled away. Says Bunk: “We’ve had a lot of close calls.”

Petersburg and other CPW staff were aware native fish species in Colorado were already outnumbered by newcomers. The last thing they needed was some snappy intruder eating their eggs or fry while they were barely out of the gravel. Petersburg realized better enforcement of the existing law was likely necessary, but he wanted more information.

In trying to understand how big the local crawfish market had become and how important it was to Coloradans, he poked around on social media. That cued a game of ecological whack-a-mole. He’d spot a post—“We’ll be in Pueblo tomorrow selling crawfish!”—and then CPW staff would drive to Pueblo. The conversations they had with alleged lawbreakers were mostly educational and, in part, served as listening sessions for law enforcement staff, who got lessons in Southern culture and cuisine. The only fine issued last year, Petersburg says, went to that first renegade.

Still, the increased policing was met with public outcry. Coloradans, it seemed, had no idea their mudbug-related business matters had been illegal for more than 30 years. In comments collected by CPW through an online portal, roughly two out of three favored tossing out the statute and legalizing imports. “I don’t understand what the issue is! Does Colorado feel the need to get their hands in everything?” one commenter asked. Another wrote: “We love the live crawfish.… It seems silly to ruin people’s businesses and family traditions.”

Colin Larson, director of government affairs for the Colorado Restaurant Association, which lobbies for restaurant-friendly regulations with the state, got a call when a restaurant faced off with CPW law enforcement staff. The importer had some questions for the restaurant association, starting with: Had its years-old business really been breaking the law the whole time? Larson explained (after reading up on the rules himself) that, yes, it likely had.

But Larson also likes to say the disconnect was explainable. Restaurant regulators and wildlife law enforcement, he says, rarely attend the same mixers, so to speak. As such, no one had realized Coloradans’ dinner choices and illegal wildlife smuggling were commingling. It was a rare crossover. “There are very few animals that are imported alive to the state that are meant for consumption,” Larson says. “Most of the time, you’re importing steak, you’re not bringing in a live cow.”

Coloradans weren’t the only ones voicing their frustrations: The CPW phone also rang with calls from Louisiana, where fish farmers were displeased at being cut off from customers. Louisiana Department of Agriculture and Forestry commissioner Mike Strain called, too. “In Louisiana, it’s a quarter-billion-dollar industry,” Strain says. Most crawfish are consumed near where they’re raised in Louisiana, but distributors ship all over the country. “It’s huge,” he says. “For us, it’s one of the mainstays of our culture. Crawfish is about as Cajun as it gets.”

Crawfish are not a Colorado mainstay—culturally or ecologically speaking—though. (In fact, no native crawfish live west of the Continental Divide.) And local experts were hesitant to say the 1991 statute was entirely off-base. “I’d just like to err on the side of caution,” says Josh Homer, manager for the Leadville National Fish Hatchery. Whether crawfish could survive in Colorado’s cold waters remains unclear, he says, but if the shellfish got a clawhold here, they likely wouldn’t have trouble surviving anywhere downriver. “We’ve seen a good number of circumstances around the world where a species was introduced for one purpose—in a lot of cases, a good purpose—but they ended up causing an entire cascading effect of bad results,” Homer says.

To wit: Last summer, CPW reported finding a different species, the rusty crawfish, in Lake Granby, the first detection of a different problematic invader in the Upper Colorado River basin. They’re believed to have been illegally introduced by anglers using them as bait. In addition to eating native species’ young and overeating their share of insects, rusty crawfish tend to consume copious amounts of aquatic plants. That strips other species of shelter and nesting sites and increases erosion. Even popular game fish far up the food chain can start to visibly suffer from sharing a waterway with rusty crawfish. CPW typically tries to manually remove rusty crawfish, but as Wisconsin demonstrated, trapping efforts often prove futile.

Still, those who opposed last year’s enforcement efforts had at least one very compelling point: Despite the large shipments that had been coming into the state for years, CPW nets and traps—though only deployed on a small scale—hadn’t turned up even one red swamp crawfish in the wild. So rather than trying to catch every shellfish runner in his van in a parking lot in Pueblo or zeroing in on every overnight order of crawfish coming from a house in Five Points, CPW did something government agencies rarely do: It decided to retool the rules.

Rewriting the rules started with conversations—and questions. Specifically, officials asked if and how they could strike a balance between allowing people to eat what they please and the still-theoretical threat of finding these pests in Colorado’s waters. “It’s weighing all of those things—the culture, the interstate commerce, the small business—against the risk of these becoming established,” says Wayne East, wildlife programs manager with the Colorado Department of Agriculture. To East, that meant considering feedback from, say, a military service member from the Southeast who’s now stationed in Colorado. People, East says, just need a little taste of home sometimes.

With that in mind, a group of law enforcement officials, biologists, and business owners convened and drafted an approach in late spring. The Fish Health Board, the statutory entity that recommends or denies approval of aquatic-related regulations and was established by the same 1991 law that banned red swamp crawfish, approved the changes in July. The Colorado Parks and Wildlife Commission, the citizen board that sets regulations, approved them in November. The rules took effect on January 1.

Perhaps unsurprisingly, on that first day of the new year, Erik Slater, special wildlife license administrator for CPW, received the first application for a permit to import red swamp crawfish. That application took a couple of weeks to process, but the department quickened its pace and began issuing the $91.10 annual licenses—which require the shellfish to be consumed within 72 hours of arrival—typically within a couple of business days. By the end of February, the state had issued licenses to most of the major Louisiana exporters.

Privacy rules prohibit the state from publishing the list of licensed distributors, so savvy shoppers will want to ask about licensure before ordering. Anyone in the process can be licensed—the distributor, a seafood reseller, a restaurant—so long as someone has done the paperwork and, Slater says, “the license follows the crawfish from swamp to table.” Coloradans who mail-order crawfish online or buy them from local seafood distributors should receive copies of the permit—which is stamped in several places with instructions not to release the animals live—with their receipts.

The issue, of course, isn’t the rule followers. Officials remain most concerned about individuals who buy the shellfish in Southern states and then cross into the Centennial State with mudbugs—and no license. “The brick-and-mortar suppliers in Denver are super easy. You can walk in there, you can do your outreach with them. Anytime you want to go inspect, you can,” East says. “It is the fly-by-night people who show up with a trunk full of crawfish—how do we track that?”

Public relations staff with the state agency say business owners, even those self-employed crawfish taxi drivers, are expected to research whether their operations comply with Colorado state law. For the first year or two of the new regulation, agency staff will focus on outreach. Then, CPW officers could begin issuing citations for illegal possession of wildlife for anyone still moving crawfish without a license. Doing so could be a pricey mistake. Some courts are willing to charge on that crime per animal, Petersburg says, so moving a couple thousand crawfish in a 50-pound sack could net someone a couple thousand violations—potentially, tens of thousands of dollars. “It’ll be a new spring for us all,” he says. “We’ll see how this goes.”