They eat anything that fits in their mouths. They reproduce copiously and adapt effortlessly. And they have become as ubiquitous and pesky as rats — only prettier and more conniving.
Nearly three decades after a lone venomous lionfish was spotted in the ocean off Broward County — posing as a bit of eye candy back then and nothing more — the species has invaded the Southern seaboard, staking a particular claim on Florida, as well as the Gulf Coast, the Caribbean, and even parts of South America. Spreading gradually at first, and then frenetically from 2005 onward, lionfish have become the most numerous marine nonnative invasive species in the world, scientists said. Along the way, the predators, which hail from the other side of the world and can grow here to 20 inches long, are wreaking havoc on delicate reefs and probably further depleting precious snapper and grouper stocks.
There is no stopping them now, salt-water experts said. But hoping to at least slow them down, marine biologists and government agencies have been intensifying efforts recently to spearfish them out of certain areas that harbor fragile reefs and figure out how they became a threat so quickly and so successfully in the Atlantic Ocean.
Most recently, the Florida Fish and Wildlife Conservation Commissionvoted in June to ban as of Aug. 1 the importation of lionfish, and this month to prohibit the breeding of the fish in the state, steps that marine experts said will serve to focus attention on the severity of the problem. The commission had already lifted fishing licensing requirements to hunt lionfish and even started an app so that people can report lionfish sightings.
“Eradication is not on the table, but local control has proven to be very effective,” said Lad Akins, special projects director for the Reef Environmental Education Foundation, a grass-roots organization helping to curb the proliferation of lionfish. “They are what many people call a near-perfect invader.”
Figuring out how to combat them —what works, what does not — has been an exercise in both imagination and frustration. The lionfish derbies, or rodeos, seem to have the best success rate. Groups of divers gather for a day of spearfishing; last week, 22 divers, some from as far away as Texas, strapped on tanks in the Florida Keys and speared 573 lionfish in one day. There is talk of offering bounties, as one university in Mississippi did to create incentives, but money is scarce.
Then there is the gourmet approach. Some Florida restaurants are now buying lionfish, which are light and flaky when cooked, not unlike snapper, and serving them to diners. Once there is a large enough market for them, scientists said, fishermen will pay attention and help haul them out of the sea.
But there are problems there, too.
“The tricky part is catching them — traditional fisheries use hook and line and that doesn’t seem to be effective with lionfish,” said Maia McGuire, a marine biologist at the University of Florida. “Divers with spear guns, they catch and catch and catch; it’s labor intensive and requires divers, gear and boats.”
Being as wily as they are, lionfish do not typically swim in schools, making them difficult to sweep up with traditional fishing nets. And they have somehow adapted to deep waters — a submarine found some of them 1,000 feet below the surface of the sea, which is too deep for divers.
Traps offer some hope, scientists said; lobster fishermen in the Keys have noticed lionfish in their traps. Work is underway to build traps just for lionfish, which would make it easier for fishermen to catch and sell them.
Scientists are also finding some comfort in the fact that merely limiting the number of lionfish on a reef — as opposed to culling them all — will allow the reef and its fish to recover, said Stephanie Green, a marine ecologist at Oregon State University who is conducting a study of such efforts.
Lionfish do not belong in the Atlantic Ocean. They wound up there when people bought them to glam up their aquariums and eventually freed them in the ocean, probably thinking they were doing a good deed, scientists said. Their true home is the Pacific and Indian Oceans, where they do not pose a problem, most likely because they are eaten by more powerful predators that keep the population in check. Here, the predators seemed befuddled by them. They either steer clear or are enticed a little too close by their orange-stripe colors and Lady Gaga-like appearance.
“Our native species don’t know who they are,” said Matthew Johnston, a research scientist at Nova Southeastern University in Florida. “I’ve seen pictures of juvenile fish trying to hide within their tentacles. They think they are shelters — and then they just eat them. It’s a pretty bad deal.”
And eat they do. Mr. Johnston described lionfish as gluttonous, because studies have shown that they can stuff 50 or 60 baby fish into their stomachs. They even have big layers of stomach fat, the result of so much overindulgence, he added. But, as committed survivalists, they also can make do without food for long spells.
There is little likelihood of extinction. When one dies, gazillions more take their place. Female lionfish are built for spawning; they each release two million eggs a year. By the time scientists here sorted all this out, their numbers were headed toward infinity.
“They can spawn as frequently as every four days, which is really crazy,” Ms. McGuire said, then wondered, “Are we going to end up with reefs just covered with lionfish?”
