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Species at Risk

The American Eel

Anguilla rostrata

What is it? | Where is it? | Why is it in danger? | What is Parks Canada doing? | Links

Why is it in danger?

In recent years, the American eel population has declined by 99% in Lake Ontario and the upper St. Lawrence River. Hydroelectric dams are considered the primary threat to the American eel as they prevent many elvers from entering the Great Lakes, while largely preventing silver eels from migrating to their spawning grounds. Other threats may include overfishing, habitat loss, and an invasive swim bladder parasite. As larvae, American eels have many aquatic predators; however as adults, their predators are fewer and may include avian predators, such as osprey and gulls.

The swim bladder parasite, Anguillicoloides crassus, is a relatively new threat for American eels in Atlantic Canada. This invasive parasite has been steadily expanding its range northward from Texas, and it has been known to spread very easily from one eel to another. A. crassus infects the swim bladder of host eels, causing potential irritation and/or inflammation to the swim bladder and resultant problems with buoyancy. The ultimate effects of A. crassus on its host are unknown, and the parasite is currently being investigated to determine its role in the decline of eel populations.

What is Parks Canada doing?

As the American eel is part of one large spawning population, there is mounting concern in Atlantic Canada that the dramatic declines in American eel populations seen in Lake Ontario may signal decreases throughout their entire range of distribution. However, to date, such declines have not been observed in Atlantic Canada. Given that there is little baseline data on the abundance of eels across Atlantic Canada at any life stage, it is becoming necessary that we begin to collect this data across the region in order to properly assess their status.

The American eel is found in seven national parks in Atlantic Canada, from the west coast of Newfoundland to southern Nova Scotia, and in the Gulf of St. Lawrence and the Bay of Fundy. This presents an excellent opportunity for collaboration. Parks Canada is working with multiple partners, including Aboriginal communities, other federal departments and universities to assess the population status of the American eel in Atlantic Canada. Along with its partners, Parks Canada has initiated a multi-park, multi-partner project to:

  • gain a better understanding of the biology of eels in our rivers — including habitat, distribution and life history—through a combination of Aboriginal Traditional Knowledge (ATK) and scientific study, thereby providing much needed baseline data;
  • strengthen partnerships with First Nations communities and enable them to aid in both ATK and scientific data collection; and
  • increase Canadians' knowledge of this extraordinary species, using its fascinating life history to encourage Canadians to take an interest in protecting American eels and working with us to collect scientific data.


What is it? | Where is it? | Why is it in danger? | What is Parks Canada doing? | Links