There are eels in every major river basin in Texas, but most people do not know about them, said Dean Hendrickson, curator of ichthyology at the Biodiversity Center. 

Researchers in the center’s ichthyology collection are studying the abundance and migration patterns of American eels throughout the state to learn how the species can be conserved. 

“They’re part of the natural system, the natural heritage of Texas, and they’re indicators of changes in those systems,” Hendrickson said.

Eels have been overfished in Japan, Europe and parts of North America, Hendrickson said. He said the unagi business, which is Japanese for eel, is based on harvesting eel larvae from the Sargasso Sea and raising them in culture in China to use in sushi.

“I think the way the global fishery has been going, they clearly will be listed as endangered sooner or later,” Hendrickson said.

The Texas Parks and Wildlife Department funds and works with the collection, Hendrickson said. He said nearly three years ago, the collection received funding from the program to study eels in Texas.

“Basically, this proposal was, ‘Let’s go out and try to catch some eels however we can catch them,’” Hendrickson said. 

Eels are difficult to research because they are both nocturnal and covered in a layer of slime that makes them hard to catch, said Melissa Casarez, assistant ichthyology collection manager. 

“I remember learning about eels as one of the holy grails of mysteries of fish biology,” ichthyology collection manager Adam Cohen said. 

Although eels have been found in Lady Bird Lake and Barton Springs, evidence suggests eels were more abundant in Texas rivers in the past but have been impacted by dams and agriculture, Hendrickson said. 

He said eels are unique because they can live for a long time and have a long migration route to Texas from the Sargasso Sea, located within the Atlantic ocean, where there are spawned.

Researchers have tracked eel larvae within the current that moves along the eastern seaboard and across the ocean to Europe, Hendrickson said. Researchers presume they travel along currents, but because few eel larvae have been found in the Gulf of Mexico, no one knows exactly how eels get to Texas, Cohen said. 

“There’s potentially something very different … going on with the gulf occurrences than anywhere along the Atlantic seaboard,” Casarez said.