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Biodiversity Blog


Social Media Leads Researchers to New Eel Discoveries in Texas

 American eels

This was written by Nicole Elmer, Melissa Casarez, and Dean Hendrickson

Citizen-science and social networking outreach efforts often yield benefits for researchers. This is no more evident than here in the University of Texas’ Hendrickson Lab (home of the Fishes of Texas project) with a recent surprising discovery of American Eels, Anguilla rostrata, in Texas.

Eels were found by workers at a wastewater treatment plant in Port Lavaca, TX to be living in an effluent box near the discharge end of the plant in an area where water is disinfected with UV light before being discharged into Lynn Bayou. In the past, when plant workers have discovered eels there, they simply tossed them back into the bayou. However, this time a flier asking people to report eel sightings to the Hendrickson Lab’s American Eel Project caught the eye of an employee. He did an online search which quickly lead him to the project and called right away to report his findings. The project is a collaboration with Texas Parks and Wildlife’s River Studies Program that seeks observations of eels such as this one in hopes of better assessing the conservation status of the species and learning more about its natural history in Texas, where very little is currently known about them. Soon after, a Victoria Advocate newspaper article profiling the discovery, and a follow up post on Facebook from the City of Port Lavaca, sparked several more reports of eel occurrences in the state.

The American Eel is remarkable, and somewhat enigmatic. They begin their lives in the Sargasso Sea, migrate far inland to rivers of North and Central America and the Caribbean, then back to the Sargasso to spawn.


Stephen Curtis from TPWD retrieving an eel at the plant.

While timing of their arrival is well known and studied on the Atlantic seaboard, it is unknown when they enter Texas rivers and in what numbers. In addition, we know nothing about age structure and genetics of these eels that make it into Texas. Some of the goals of the Hendrickson Lab American Eel project aims to answer these unknowns and that requires specimens such as these found in Port Lavaca’s wastewater plant.

If you have ever seen an American Eel in Texas or other Gulf of Mexico state, please visit this link to assist us by reporting it: https://sites.cns.utexas.edu/hendricksonlab/contribute-data-and-specimens.

Fun facts:

1. American Eels have six life history stages. Eggs hatch into a translucent, leaf-like larval stage, called a leptocephalus, and drift around in ocean currents. As they approach coasts, they transform into tiny, transparent glass eels and swim into estuaries and begin moving upstream in large groups. While upstream movement continues, they become pigmented and grow into elvers. Next, they enter the yellow eel stage, living for many years in freshwater, some far upstream (e.g. Minnesota in the Mississippi), though some may return to estuaries, spending time in both fresh and saltwater. Last, there is the transformation into silver eels as they fatten up and otherwise prepare for the long and treacherous journey back to the Sargasso to spawn and die.

2. The American Eel lives across a wide range of latitudes, perhaps more than any other freshwater fish species in the Americas.

 Researchers at work...

3. American Eels produce a large amount of mucous when captured, making it very difficult to handle them.

4. As glass eels and elvers, they have the ability to climb vertical walls and barriers most would guess would impede them from moving upstream.

5. Despite their intriguing snake-like appearance, American Eels have long played a big role in the diet of humans. They can fetch a high price in the Asian market and are also harvested in the United States.

6. Females can grow to be five feet, where males grow to be around 2 feet.





Hendrickson, Dean A. 2017. “American Eels in Texas – a review of what is known, what is being done to learn more, and how you can help.” Texas Commission for Environmental Quality's Annual Surface Water Quality Monitoring (SWQM) workshop. Bandera, Texas, USA.
doi: https://repositories.lib.utexas.edu/handle/2152/62549

Priest, Jessica. “Eels swim to Port Lavaca wastewater treatment plant,” February 17, 2018. Victoria Advocate.

“American eel.” Texas Parks and Wildlife. Accessed online at https://tpwd.texas.gov/huntwild/wild/species/ameel/

“American eel.” US Fish and Wildlife Service. Accessed online at


anguilla rostrata small 
 Illustration by Joseph Tomelleri
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