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American Eel

Factors Affecting Eel Populations


The long life span of American eel, combined with their vast migration route, makes them susceptible to a wide range of factors. While no one factor has been identified as the single cause of the American eel decline, the factors below appear to be having a cumulative impact on American eel. These factors generally occur globally and include:

  • Turbines at hydro electric facilities: eels can be killed as they migrate downstream through the turbines on their way to spawn in the Sargasso Sea. In the St. Lawrence River system, 40 per cent of mature eels that pass through turbines are killed
  • Physical barriers such as hydro dams can block eels from migrating upstream to their freshwater habitats. A large portion of the eels' freshwater habitat in Canada and the United States has been made inaccessible due to such physical barriers
  • Harvesting: American eel are harvested throughout their global range and during all of their life stages
  • Deteriorating habitat quality: contaminants such as PCBs may affect eel fertility and survival
  • Habitat loss in marine waters due to the over-harvest of seaweed in the Sargasso Sea
  • Changing ocean conditions may influence the ability of eel to drift and migrate to and from the Sargasso Sea
  • An exotic, parasitic worm that affects the health and survival of eels. (While this worm has been introduced into United States waters, it has not been found in Canadian waters).


American eels might be confused with sea lamprey. The eel has a snake-like body and a dorsal fin that extends from half-way down the length of its back to the underside of its body. At maturity, eel range from 75 to 100 centimetres (cm) in length and weigh one to three kilograms.

Sea lamprey grow up to roughly 85 cm in length. A major difference between sea lamprey and the American eel is that, unlike eels, sea lamprey has a circular, suction-cup like mouth with numerous teeth used to attach themselves to fish.

Eel Management


Ensuring the long-term sustainability of the American eel population is highly complex and requires significant coordination across many international jurisdictions. Ontario is working closely with federal, provincial, and United States governments and industry partners to facilitate the recovery of the American eel. Some of the measures include:



  • In October 2006, the Ontario Ministry of Natural Resources, in partnership with Ontario Power Generation, the Ontario Federation of Anglers and Hunters and the Ontario Commercial Fisheries' Association released over 144,000 eels into the St. Lawrence River.
  • Quebec has also started stocking eels into Lake Champlain.



Cancelling American Eel Harvests:

  • Ontario cancelled the commercial and recreational harvest of American eels in 2004.
  • The Quebec government has also reduced the commercial harvest of eels.



Reducing Migration Barriers:

  • The Ontario Ministry of Natural Resources and Ontario Power Generation are working to improve the safety of eels as they pass through hydroelectric turbines in Ontario waters.
  • An eel ladder was installed in 1974 at the R.H. Saunders Hydroelectric Dam near Cornwall, Ontario, to help eels climb over the dam as they migrate into Ontario from the Sargasso Sea. By counting the number of eels that pass through these ladders, biologists are able to monitor changes in the size of local eel populations over time.
  • Quebec Hydro and New York Power Authority, in association with provincial and United States state authorities, have also established eel ladders at their dams in the St. Lawrence River.


Management Plans:

  • In September 2004, the Department of Fisheries and Oceans Canada with the Quebec and Ontario governments agreed to develop a coordinated management plan for American eel in Canada. Update: consultation period has ended.  (
  • While there is no North American management plan for American eel, efforts are under way to ensure the coordination of management actions between Canada and the United States. Ontario is working with Fisheries and Oceans Canada, other provincial governments, the Great Lakes Fishery Commission, and United States federal and state governments to develop inter-jurisdictional management plans for American eel.


Status Designation:

 American Eel are listed as an endangered species in Ontario and are protected under Ontario’s Endangered Species Act.