Conserving the Nature of America

The American Eel

American eel (Anguilla rostrata). Credit: USFWS
American eel (Anguilla rostrata). Credit: USFWS

The American eel undergoes many biological changes—known as metamorphoses—throughout its complex life history. They begin their lives as eggs hatching in the Sargasso Sea, two million square miles of warm water in the North Atlantic between the West Indies and the Azores. The eggs hatch into larvae that drift with the Gulf Stream and take years to reach their U.S. freshwater streams and estuarine habitats. In these habitats, the eels mature, changing color over time, and then finally return to their Sargasso Sea birth waters to spawn and die.

People have fished and farmed eels for thousands of years, but until recent years, little was known about the eel's complex life history. Eels have played a major role in the human diet in Europe and Asia, and in many European countries, European eel populations have decreased as much as 99 percent. Glass eels cyclically fetch a high price on the Asian market, and this young life phase of American eels has also been harvested in the United States.

The American eel, found in freshwater, estuarine and marine habitats from Greenland to South America, has been extirpated from portions of its historical freshwater habitat during the last 100 years, mostly resulting from dams built through the 1960s. Eels lose habitat and migration corridors when waters are obstructed by dams and other mechanisms. Localized population declines are also attributed to mortality in hydropower plant turbines, degradation of current habitat, and overharvest.

The eel's unique life cycle continues to present challenges to understanding and assessing biological and environmental processes that influence eels. The U.S. Fish and Wildlife Service and its partners continue to research American eels to better understand and conserve this remarkable species.

An American eel in the leptocephalus larval stage, during which it still lives in the ocean. This stage is similar to that of the glass eel, in that the eel is transparent in both stages. Credit: USFWS
Glass eel, an early stage in the life cycle of the American eel. Credit: USFWS

Considering Endangered Species Act Protection

The U.S. Fish and Wildlife Service and the National Marine Fisheries Service reviewed the status of the American eel in 2007 and found at that time that Endangered Species Act protection for the American eel was not warranted. This review followed a series of workshops and actions initiated by a 2004 petition seeking to list the American eel.

After examining all available information about the eel population from Greenland south along the North American coast to Brazil in South America and as far inland as the Great Lakes and the Mississippi River drainage, the Service found in 2007 that declines of eel populations in some areas had not put the overall population in danger of extinction.

The Service received another petition in 2010 seeking to extend federal protection to the American eel. The Service found that this petition, from the Council for Endangered Species Act Reliability, presents substantial information that warrants the initiation of a more extensive status review of the species.

Petition, 2010: Council for Endangered Species Act Reliability seeks to list the American eel as a threatened species under the Endangered Species Act (PDF-1.38MB)
News release, 2011: American Eel May Warrant Protection Under the Endangered Species Act
Questions and answers on the 2011 90-day finding
Federal Register notice on 2011 90-day finding

Resources related to the 2007 review

News release, 2007: Endangered Species Act protection for American eel not needed

News release, December 2005: Eel experts home in on threats

News release, July 2005: Wildlife agencies to initiate status review of the American eel

More information

The American eel in localities along the East Coast

Links to non-Fish and Wildlife Service sites  

Back to Issues in Depth


Last updated: April 29, 2014