THE FLORIDA EVERGLADES — Many people might recognize them on a sushi plate with a side of sweet and salty sauce. But Asian swamp eels have become a problematic invasive species in the delicate ecosystem of the Florida Everglades.
The dark brown, muscular, three-foot-long air-breathing species of fish, also known as a rice eel, sucks up everything in its path - miniature fish, shellfish, frogs and turtle eggs. The eels have been spotted in certain Everglades areas for decades, but now researchers have data showing enormous proliferation.
“MOST CHALLENGING” INVASION
A recently published report in Science of the Total Environment documented enormous drops in the population of tiny native creatures since the eels were introduced. For example, flagfish and crayfish levels plummeted 99 percent, marsh killifish dropped 91 percent and the eastern mosquitofish – the fish that literally eats mosquitoes and aids in pest control – diminished by 66 percent.
“You can’t say 100 percent because there were like two crayfish,” said Matthew Pintar, lead author of the paper and former researcher at Florida International University.
Pintar suggests in the paper that due to the rapid decline of tiny creatures that make up the primary food source for wading birds and other wildlife, the Asian swamp eel may soon displace the Burmese python as the most challenging invasive species in the Everglades.
“In Taylor Slough, they’re the number one species in terms of the threat they pose to the ecosystem,” he said. “It’s potentially the worst species we’ve had yet.”
SLIPPERY CREATURES WITH LUNGS AND GILLS
In the late 1990s, the eels were first spotted in a canal near Hard Rock Stadium, likely released as unwanted pets, according to researchers. Eventually, the eels slithered into the Everglades just outside Taylor Slough, a river flowing into Florida Bay.
The slippery creatures were first found inside Taylor Slough in 2009. The report also shows populations increasing in Peace River, Myakka River, and both Tampa and Sarasota Bays.
“Since 2015, their distribution just exploded,” Pintar said. “We have no idea how many there are now.”
Although swamp eels are native to Asia, the peculiar eel-like fish survive in flood and drought conditions like the Florida Everglades. Unlike snakes or fish, swamp eels have both lungs for breathing air and gills for breathing underwater.
The bizarre invasive species are spreading unabated throughout the Everglades. Pintar said predators such as large birds and alligators eat the swamp eel occasionally, but they’re not making much of a dent in the rapidly expanding population.