Asian Swamp Eels: Slimy, Slippery and a Massive Problem for the Everglades

There’s another invader wreaking havoc on the Everglades ecosystem, and it’s a slimy fish with a voracious, indiscriminate appetite. 

Like so many other invasive species, such as iguanas and pythons, the Asian swamp eel likely arrived in South Florida through the pet trade or the food industry. Scientists have known the eels were living in canals since the 1990s, but recently, they started moving into the wetlands of Everglades National Park, and now, researchers say, we have a problem.

“These are just some of the examples we brought back to the lab. We’re gonna work on the diet analysis, this is a fairly large adult,” said researcher Dt. Nathan Dorn as he showed NBC6 dead eels which had been frozen in his lab at Florida International University. “This species is native to southeast Asia but also China.”

Harmless in the lab, but they’re a devastating force in the eastern part of Everglades National Park. The Asian swamp eels are living in the same areas most visitors see, such as Anhinga Trail and Shark Valley. The eels are having a drastic impact on the food web.

“This is just one of the species that’s been decimated in Taylor Slough by the eel,” Dorn said as he showed us native crayfish in an aquarium.

The eels are vacuuming up the crayfish and other small fish, the primary food source of wading birds.

“The problem is we have 90% loss of the crayfish, 90% loss of two native fish, and 60% loss of one of the most abundant fish for food for the birds,” Dorn explained.

FIU researchers were shocked to discover the scope of the problem. They’ve been studying the eel population for years, while it was mostly confined to the canals.

“Took us a long time to recognize just what a problem this animal could be,” Dorn acknowledged.

Now Dorn’s team believes the Asian swamp eel could be just as harmful to the Everglades animal population as the Burmese python has been. Pythons are decimating the small mammal population, and Dorn says the eels could have a similar impact on the wading birds.

“They’re moving west and north, and there’s really no easy way to stop it," Dorn said. "Hopefully some of the predators in the system will pick it up as food and start to slow down the growth of the animal, but we see no signs at this point that the species will drastically diminish."