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American Eel Conservation

Population Threats

In their early stages of life, eels are ribbon-like and almost transparent. Known as “glass eels,” these young fish are popular on the Asian market and are also frequently harvested in the U.S. These juvenile eels typically gather seasonally during migration, making them easy targets. Yellow eels (the following life stage) are also a primary target for commercial harvesting. American eels mature slowly—it can take anywhere from eight to 24+ years for them to reach sexual maturity. Removing them from the wild before they’re able to reproduce hinders eel populations.

In addition to over-harvesting, eels face other population pressures. A large part of the American eel’s life cycle is spent traveling to spawn in the Sargasso Sea. For some, that’s a voyage of thousands of miles. Dams create obstacles during this trek, limiting the American eel’s access to migration corridors.

Dams also diminish the amount of watershed habitat that eels have access to, which can affect the livelihood of other species in the ecosystem—like the eastern elliptio, a freshwater mussel. Part of a mussel’s life cycle requires a host, and for the eastern elliptio, American eels are a favorite. You’re unlikely to find these mussels in a system that lacks American eels.

Federal and State Protection

In 2007, the status of the American eel was reviewed by the U.S. Fish and Wildlife Service (FWS) and the National Marine Fisheries Service (NMFS). Population declines were identified in certain areas, but they were not enough to warrant protection under the Endangered Species Act (ESA).

It was determined that the overall American eel population—which ranges from Greenland, down the North American coast and as far south as Brazil—was not in danger of extinction. Fluctuations in American eel populations over time suggest they are a fairly resilient species, so an instance of decline may not indicate an irrevocable decrease in their numbers. New evidence was presented in a 2010 petition to have the species listed under the ESA, and it was determined that the eel’s status (and its potential protection under federal law) may warrant a closer look. At this time, the American eel remains unlisted.

Despite a lack of protection under federal law, some states have taken individual measures to help preserve American eel populations. Maine, for example, has a quota on its glass eel fishery and additional measures in place to reduce the illegal harvest of eels.

Citizen Science

In addition to advocating for legal protection for the American eel, there are some grassroots efforts underway in areas where populations are noticeably in decline. In the Hudson River area, for example, scientists, students and volunteers track the American eel population by monitoring the number and size of juveniles found in the river’s tributaries each spring.

In some areas, these citizen scientists are even installing “eel ladders” to overcome the fragmentation of habitat that dams have caused. These ladders allow eels to pass upstream of a dam, continuing their journey unobstructed by manmade obstacles. One such ladder was installed at Daniels Dam on the Patapsco River this past June.


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