Something is lurking beneath the Everglades — and Florida’s frogs and salamanders are at risk
The invasive Asian swamp eel may be reshaping the Everglades’ amphibian community.
FILE: Alligators fight for territory in Florida Everglades as mating season gets underway
Video provided to FOX 35 in Orlando by Captain Wes Bedell, of Naples Inshore & Offshore Fishing Charters, shows an intense battle between two massive alligators in the Florida Everglades as mating season gets underway.
The Everglades’ latest invasive threat isn’t a snake lurking in the grass, it’s an Asian swamp eel moving through the wetlands, as new research links the invasive zoo animal to amphibians in the U.S.'s largest wetland.
The Asian Swamp Eel, Monopterus albus, is a high-risk, invasive species that is eating Florida alive.
First found in Florida in 1997, the drought-tolerant Asian swamp eel spread from canals near Homestead into Everglades National Park’s Taylor Slough by 2007. The invasive fish is now especially abundant there, where it has devastated some crayfish and small-fish populations — key prey for wading birds.
( USFWS/John Galvez )
The introduction of the eel-like creature native to eastern and southeastern Asia has coincided with significant declines in the abundance of native fishes and decapods in the Sunshine State.
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Since its introduction, traced back to live releases from the aquarium trade and from fish markets, the Asian swamp eel has since become a problem that is slipping out of control.
Wading birds, including cranes and herons, may prey on Asian swamp eels, but the invasive fish’s ability to burrow into mud and survive dry spells makes it a difficult target.
(Kevin Sunderland / National Park Service Facebook)
According to a study published in Freshwater Biology, invasive Asian swamp eels are now the leading predictor of lower amphibian abundance and altered wildlife communities across parts of the Everglades.
An adult Asian swamp eel. The species was first imported to the U.S. as a food source and for the aquarium trade before becoming a high-threat invasive species.
(Invasive.org / Photo by Paul Shafland; Florida Fish and Wildlife Conservation)
Researchers from the University of Miami, working with scientists from the South Florida Water Management District and Florida International University, surveyed 30 sites across four major Everglades regions during the summer of 2022, documenting 2,251 amphibians across nine species.
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At first, soil nutrient levels appeared to be the strongest influence on where amphibians were most abundant. But when researchers added data on invasive Asian swamp eels, the eels emerged as the leading predictor of both amphibian abundance and the makeup of the wetland communities — with higher eel numbers linked to fewer amphibians.
One of the most prominent invasive species established in the Everglades' freshwater ecosystems is the Asian swamp eel. It has been reported that they eat significant numbers of small, aquatic organisms important to the native, freshwater food web. This dead swamp eel, found along the Shark Valley tram road, was appropriately colored orange and black, although coloration can vary greatly in this species.
(NPS Photo by Rachel DiPietro.)
The Asian swamp eel has a proven track record, damaging rice fields in the Phillipines and Japan, where its burrowing behavior has resulted in negative economic impacts, according to the U.S. Fish and Wildlife Service, triggering its high risk tag by the agency.
Species that are considered high risk have a well-documented history of invasiveness in at least one location globally and are of establishment concern in the U.S., according to the agency.
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Asian swamp eels are considered a delicacy in parts of Asia, where they are commonly sold live in food markets and used in soups, stir-fries and other traditional dishes.
(Creative Touch Imaging Ltd./NurPhoto via Getty Images / Getty Images)
The Everglades are not alone in confronting the invasive fish, as Asian swamp eels have also established populations in Georgia and New Jersey, and have been present in Hawaii for decades, the USGS said.
Researchers say the next step will be closely tracking amphibian populations while working to limit the eels’ spread, an effort that could help protect frogs, salamanders and the fragile Everglades food web they support.