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Researchers find invasive, airbreathing, frog-hunting fish along Florida’s Gulf Coast

Scientists say they observed several of the nonnative fish slither out of a pond and snatch some tree frogs during a rainy day in 2020.
 
Researchers recently documented, then killed, a population of invasive, air-breathing goldline snakehead fish living in a pond in Manatee County.
Researchers recently documented, then killed, a population of invasive, air-breathing goldline snakehead fish living in a pond in Manatee County. [ Courtesy of Zachary Randell for the Florida Museum ]
Published Jan. 27, 2023|Updated Jan. 30, 2023

A pond in Manatee County was recently home to nearly 400 invasive fish known for their large size, their ability to survive in harsh environments and their “highly aggressive nature.”

Oh, and they can also hunt on land.

It’s the first time on record researchers documented a population of invasive goldline snakeheads on Florida’s Gulf Coast, according to a study published recently in Aquatic Invasions, an international peer-reviewed journal focused on aquatic invasive species.

Native to Asia, the fish can outlive, outhunt and outcompete Florida’s local wildlife, posing a threat to the native ecology in the waterways where they’re discovered. The only other known population in the United States is more than 150 miles away, in Broward County.

“I found it interesting because it was such a long distance from the other known population here in Florida. So that suggested to us that it was probably a case of somebody bringing it up from South Florida,” said Matthew Neilson, a fishery biologist with the United States Geological Survey and one of the study’s authors.

“They are very large predatory fish, and they consume a wide variety of prey: fish, reptiles and amphibians,” Neilson said in an interview.

This is the pond in Manatee County where researchers studied a population of invasive goldline snakehead fish recently.
This is the pond in Manatee County where researchers studied a population of invasive goldline snakehead fish recently. [ Courtesy of the United States Geological Survey ]

Researchers were first contacted by a resident, described as a fish enthusiast, who made the discovery. From start to finish, the study took about two years, Neilson said.

On one rainy day in 2020, several snakeheads were seen slithering their way onto the pond’s bank after being lured by some nearby green tree frogs. In what’s described as a “rarely seen behavior,” a researcher documented the fish as they quickly twisted their bodies toward the frogs and caught them. A successful out-of-water hunt.

That’s just one reason why the fish pose a threat to Florida wildlife: They are durable.

“It’s an interesting behavior, but it also increases the likelihood that they would survive through import,” Neilson said. “If you have an animal that can gulp up surface air, and then use that for respiration, it could survive transport.”

Snakeheads are a popular species worldwide in the ornamental fish trade, and for anglers, they also put up a good fight. Neilson thinks an angler living on Florida’s west coast wanted some unique sportfishing in their own backyard, and may have brought the animal over from across the state. But that’s just a theory, and the truth on how the fish were introduced into Manatee County may never be unveiled.

Researchers compared the genes of the population in the Manatee County pond to the fish populations found in Broward County. They were “nearly identical” and could be linked to snakeheads in Thailand, according to Neilson. The population in South Florida has thrived for more than two decades.

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The only other documented population of invasive goldline snakehead fish is located in South Florida, in and around Broward County, according to researchers.
The only other documented population of invasive goldline snakehead fish is located in South Florida, in and around Broward County, according to researchers. [ Courtesy of the United States Geological Survey ]

The pond, which is just east of Interstate 75, included other nonnative species, like Asian swamp eels and walking catfish, according to the study. Scientists brought the carcasses of dead fish collected in the pond to a nearby Manatee County landfill.

Florida wildlife biologists with the Florida Fish and Wildlife Conservation Commission helped kill nearly 400 snakeheads found in the pond, and several were even catalogued in the Florida Museum’s ichthyology collection, the museum said.

“It seems that the eradication efforts were successful, so they are no longer present in Manatee County,” Neilson said. But he added a caveat: There’s a chance some individuals are still swimming around out there in nearby waters.

“If any are seen, the public is encouraged to report it.”

You can report sightings of nonnative species to the wildlife commission’s exotic species hotline at 1-888-483-4681, and you can report other nonnative species online at Ivegot1.org