Pond Management: American Eels

Perhaps no other fish on the east coast of North America is more secretive and mysterious than the American Eel. It is very common to find eels in ponds while electrofishing. Once in the livewell, the pond owner usually says something like “I have lived here for years and had no idea eels were even in my pond.” Although they look and move more like a snake than a fish, they are just as much a fish like largemouth bass. They are found in almost every impoundment along the coast, but not many people know much about them, where they came from, or how they got into their pond.

Let’s start from their beginning. American Eel are catadromous, meaning they are born in saltwater but grow up in freshwater. They are actually born in the Atlantic Ocean, thousands of miles away in the Sargasso Sea. Populations from the east coast of the U.S. actually reproduce at the same time and place as the European Eel, creating a panmictic (truly mixed) population. Sadly, adult eels are assumed to die after spawning, as adults have never been seen returning to the mainland. Baby eels are called leptocephali and look a lot like the leaf of a willow tree. They begin their return journey riding along the Gulf Stream currents. After about a year, they transform into ‘glass eels’ during their transition between the ocean and freshwater. Their skin is actually transparent, and you can even see their gills and heart inside of them!

Once back in freshwater, glass eels begin to turn into yellow eels. These yellow eels are what we typically see when electrofishing or what people catch when fishing. They can also be found anywhere that water flows to the ocean, from the Great Lakes to the Mississippi, and all the way to South Dakota. Imagine swimming from the Sargasso to Minneapolis! Young eels looking for a place to live can actually move over land when it’s wet, following rain runoff around small barriers like dams until they find a place they want to grow up, like in your pond.