In early spring, somewhere deep in the Atlantic Ocean, an amazing fish begins a journey that may bring it to a river or stream near you within a few short years. Each spring American eels hatch from eggs laid deep in the Sargasso Sea, a broad area of the Atlantic east of the Bahamas and south of Bermuda. From there they drift on ocean currents, eventually finding their way into rivers that empty into the Gulf and East coasts of the United States.
Along the way their bodies transform from something shaped like a flat, colorless willow leaf into the yellowish-brown and creamy white snake-like fish we recognize as an American eel. While many eels choose to stay near the coast, others swim hundreds of miles upstream—even into mountain streams—where they will live for a decade or more until they return to the Sargasso Sea to reproduce and die.
American eels that enter the James River in the Chesapeake Bay watershed of Virginia and choose to venture far upstream may eventually encounter U. S. Forest Service Southern Research Station scientist Andy Dolloff, who has been studying eels in mountain streams on the George Washington National Forest in Virginia since 1999.
Each summer Dolloff assembles a team of “eel wranglers” from the Forest Service, Virginia Department of Game and Inland Fisheries, and an ever-growing list of volunteers to capture eels from a tumbling mountain stream popular with local trout anglers. Each eel they collect is checked for a tag with a hand-held scanner, then measured and weighed. Eels without tags are injected with a small chip similar to the those used to identify livestock and pets at your vet’s office. Each tag is unique, so when a tagged eel is collected Dolloff knows exactly how far it has moved and how much it has grown since its last encounter with his team.
Since 2000, Dolloff’s team has tagged over 1,500 eels and has re-captured over 40 percent of them at least once. What has he learned? Dolloff notes that most of the eels are collected within several hundred feet of where they were originally captured and tagged, and eels tagged as early as 2000 are still being collected today, suggesting that after their long trip from the Sargasso Sea eels can settle into their mountain homes for periods of 10 to 20 or more years.
Eel growth rates are similar to those found in coastal streams, indicating that there’s abundant food—mostly crayfish and insects—for them to feed on in mountain streams. Furthermore, radio-telemetry studies have shown that eels are staying in the streams year-round, using small spaces between rocks and beneath stream banks to ride out the winter months.
Most people are not even aware that eels live in these streams, a sad commentary on their decline in numbers over the last century. At one time eels were so common in mountain streams that people collected them for food, spearing them at night when they’re most active.
Today American eels are absent from many streams altogether, victims of dams that prevent their upstream movement. In other streams eel numbers are greatly reduced due to factors ranging from the estuarine harvest of young “glass eels” for the aquaculture industry to water pollution. The decrease in American eel numbers has caught the attention of both the fishing industry and government agencies, and twice over the past decade the American eel has been studied for listing as a federally threatened fish.
Dolloff hopes his work will help to shed light on the importance of headwater streams to the overall American eel population. In addition, recent dam removals on Atlantic coast rivers and streams have helped American eels reoccupy streams where they have been absent for decades.
For more information, email Andy Dolloff at firstname.lastname@example.org.