Species Spotlight: American Eel

Get to know some of the species at risk in the Lac Deschenes Ottawa River IBA with the Species Spotlight, aka “Sp-Spot.” Today meet the: American Eel

Leptocephalus Photo Credit: Academic dictionaries and encylopedias

Newly hatched eel called Leptocephalus
Photo Credit: Academic dictionaries and encylopedias

Scientific Name: Anguilla rostrata
SARA Status: Not listed; Ontario: Endangered; Quebec: Likely to be designated
Taxonomic group: Fishes
Size: Adult females can grow up to 1 m in length; while males are smaller growing up to 0.4 m.

The American Eel has a long and serpentine body, with a single fin that extends around the tail to the belly, known technically as the ventral side, and has deeply embedded rudimentary scales. Their lips are thick and the lower jaw it is slightly longer than the upper jaw giving them the appearance that they are pouting. Juvenile American Eel, also called yellow eels, are yellow to green or brown color on the belly and dark on the back. The adults, commonly called silver eels, are grey with a white or cream belly.
Yellow eels eat at night and prey on small fishes, mollusks, insects and crustaceans. But they stop eating for the spawning migration.

American eel have a complex life cycle. They spawn only in the Sargaso Sea in the Atlantic Ocean. Females can lay from 0.5 to 4.0 million eggs. When the willow-leaf shaped eel larva hatches, called leptocephalus, it starts drifting with ocean currents. When the leptocephalus approaches the coast, it changes to a more elongated and transparent form that is now called glass eel. Then the glass eel migrates into streams, rivers and lakes to grow into a smaller version of an eel adult with more or less pigment, called elver. Once in fresh water, elvers grow as larger yellow eels seeking for better habitat. Yellow eels may stay in fresh water from 5 to 20 years before they begin to mature and change to silver eels, and then they are ready to start migrating downstream to the Sargaso Sea to spawn, some of them travelling up to 6,000 km.

Yellow Eel  Photo credit: Parks Canada

Yellow Eel
Photo credit: Parks Canada

In Canada, American eel has being highly valued as food resource for aboriginal people, particularly the St. Lawrence Iroquois, and it has existed in commercial fisheries since colonial times. Currently, the American eel’s population has shown a substantial decrease. The low numbers of eel migrating into the upper St. Lawrence River and Lake Ontario in recent years suggest that the eel populations will remain low and will not provide a commercial resource for at least the next decade. In 2004, Ontario cancelled commercial and recreational harvest of American eels, and Quebec has also reduced the commercial harvest.

The numerous threats the American eel is facing are changes to ocean conditions that could interfere with larval move to coastal areas; habitat loss due to the construction of dams and other barriers contribute to reduced or delayed migration. Hydroelectric turbines may also contribute to increase mortality or injury.  Contaminants, parasites and commercial fishing are also threats in some regions.

Where Else Can You See This Species?
The American Eel can be found in all fresh water, estuaries and coastal waters that are accessible to the Atlantic Ocean, from Niagara Falls in the Great Lakes up to the mid- Labrador coast in Canada.
In Ontario, the distribution goes as far as Niagara Falls and the headwaters of the Ottawa River. Though eels have vanished in many inland waters of Ontario, there are have been some observations of young eels during their upstream migration in the lower Ottawa River and its tributaries, the lower Trent River, the upper St. Lawrence River and in Lake Ontario. Currently, eel presence in the Ottawa River is severely restricted by a series of hydroelectric facilities.

Silver Eel Photo credit: Parks Canada

Silver Eel
Photo credit: Parks Canada

Did you know?
•    In Canada, more than 95% of eels are females.
•    American eels can change their color in response to changes in light in their environment.
•    In Ontario, American eels can grow up to 1.3 m in length.
•    Also in Ontario, it is more common to see the yellow eel, while the silver eel is rarely seen.
•    As predators, American eels have an important role as ecosystem indicators, helping to keep other fish species in balance, including invasive species such as the goby.
•    Historical accounts from the mid-1600s record a fisherman spearing as many as 1,000 eel in a single night.
•    During winter, the American eel will dig a hole in the mud to hibernate.

Check back every week to read about a different species at risk that can be found in Lac Deschênes.
You can report sightings of this and other rare species to the Canadian Wildlife Service at (819) 997-2800 or on the MNR Natural Heritage Information Centre website. A photo and the location of your sighting are also very helpful!

We would like to thank our guest blogger Monica Reyes for this post. Monica is a conservation volunteer for Nature Canada.She is a biologist from Mexico interested in wildlife conservation and environmental education.

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