If someone told you there was a slimy, slithery creature living in the Chesapeake that is considered an international delicacy, but also used as fish bait, would you know they were talking about the American eel? Interestingly enough, this resident has an extraordinary life story that begins in the warm waters of the Caribbean.

American eels (Anguilla rostrata) are the only catadromous fish in the Chesapeake Bay, which means they live in freshwater but migrate to salt water to spawn. Eels begin and end their life in the Sargasso Sea, near the Bahamas. Using the Gulf Stream to disperse larvae, female eels deposit millions of eggs into the ocean. After the eggs hatch, the 2 inch larvae (called Leptocephalus) drift in the ocean currents for 9 to 12 months until they reach the coastal waters along the Atlantic coast, including the Chesapeake Bay. Here, the eel larvae transform into clear, “glass” eels. When their color darkens and they complete metamorphosis, they are called elvers.

In the Chesapeake Bay, elvers are most frequently seen in April, until they stop migrating and go through another growth stage. After eels enter their yellow phase, they move into the freshwater rivers and streams of the Bay to feed on insects, mollusks, crustaceans, worms, and fish. Eels will use the ample resources of the Bay watershed for 5-20 years, before they begin their journey back to the Sargasso Sea to spawn and then die.

American eels are an important component of the Bay, both ecologically and economically. Eels are a significant source of food for fish, mammals, turtles, and birds. Most eels caught in the Chesapeake Bay are exported to support the large demand as a favorite food for people in Europe and Asia. However, Chesapeake eels are also used as bait for crabbing and fishing activities.

And although the demand from the eel industry is increasing, the commercial eel catch is decreasing. The current status of eel populations around the Bay is unknown. In the Potomac River, a tributary to the Bay, eels once comprised 25% of all the fish in the river. Today, dams and other barriers on the Potomac River have slowed down and even prevented eels from entering the tributaries of the Bay as they attempt to reach their traditional spawning grounds. Unable to pass through or swim around these blockages, eels stocks have declined.

Biologists with the US Fish & Wildlife Service Chesapeake Bay Field Office (CBFO) and Maryland Department of Natural Resources are determining if and how eels pass a barrier at Great Falls Dam. Are they swimming around the Great Falls dam or going through the C&O canal at the National Historic Park?
In the spring of 2003, biologists used eel pots baited with razor clams to catch eels. Researchers caught, weighed, and measured 122 eels; injected them with a microchip used for tracking; and then released them back into the Potomac. The preliminary results show that approximately 15-30% of the eels caught were captured a second time during the study, which will help CBFO personnel determine which site is the most efficient passage route. An additional 40 eels will be tagged in the summer of 2004.

Chesapeake Bay Field Office biologist Dave Sutherland states, “Not only will this study help determine the degree to which eels are passing the C&O Canal and Great Falls Dam, but it will assist state and federal agencies identify management actions to ensure long term sustainability of this culturally and ecologically important fish in the Chesapeake Bay.”

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Link to the Chesapeake Bay Field Office

For additional information on American eels:
Chesapeake Bay Program:
http://www.chesapeakebay.net/baybio.htm

Maryland Department of Natural Resources
http://www.dnr.state.md.us/fisheries/education/eel/eel.html
Washington Post article: Slithering from Science's Grasp (07/22/2004)