ENDANGERED: American eel numbers in the St. Lawrence River are plummeting

Published on July 29, 2014
St. Lawrence River Institute scientist Matt Windle gets up close and personal with an American eel.

CORNWALL, Ontario - They may look snake-like and come complete with a revoltingly slimy exterior - but biology experts are working to save the American eel.

The eel was once a staple part of the St. Lawrence River ecosystem, but experts are now worried the animal could be in danger of seeing its numbers plummet beyond the staggering statistics suggested to date.

“Now it’s rare to meet someone that has seen a wild eel in Ontario, and the public is losing the important connection that First Nations and European settlers once had with this species," said St. Lawrence River Institute research scientist Matt Windle. "Eel populations in the Great Lakes system declined severely in the 1990s, likely as a cumulative result of habitat loss, overfishing, and climate change."

Experts like Windle are expected to meet next month in Quebec City to discuss the declining eel population at a science symposium.

In the meantime biologists are still trying to get their heads around the drop in eel numbers.

Because of steeply declining populations, American eels are classified as endangered in Ontario. The U.S. Fish and Wildlife is considering American eels for listing under the U.S. Endangered Species Act.

The average number of eels migrating up the St. Lawrence River near Cornwall decreased to roughly 40,000 per year in 2013 from one milion in the 1980s.

Windle said American eels used to be kings of the St. Lawrence River, helping to shape the habitat stretching well west of Cornwall.

"Historically, eels would have had a stabilizing effect on Great Lakes ecosystems, through their super-abundance, long life spans, and role at the top of the food chain," he said.

The American eel spawns in seawater but spends most of its life in freshwater lakes and streams. Its spawning zone is the Sargasso Sea east of the Bahamas and southwest of Bermuda in the North Atlantic Ocean at reported depths of up to 1,400 feet.

Each female lays up to 20 million eggs during her lifetime. When they hatch, the transparent leaf-like larval eels spread to great distances, moving with the ocean currents. They assume the shape of the adults as they reach the mouths of freshwater streams after about a year at sea.

Females found in the Great Lakes watershed can remain in freshwater for upwards of 20 years, growing to more than 40 inches and seven pounds before returning to the Sargasso Sea to spawn and die.

Males are considerably smaller and seldom exceed 24 inches in length.

Only female American eels are found in the Great Lakes and St. Lawrence River. It’s a mystery where the males go because they are present in numbers equal to females at the mouth of the St. Lawrence.

American eels have been found far inland as the Grand River near Lake Michigan, and in Ashland County on Lake Superior in Wisconsin.

Eel flesh is considered a delicacy in many parts of the world, especially among Europeans and the Japanese. The global sushi market is driving exploitation of the American and other eels.  Although commercial fishing of American eels is now banned in the Great Lakes states and Ontario; a limited fishery remains in Quebec.

Dams also undermine the species, thwarting migration upstream in the St. Lawrence River. Hydroelectric facility operators are making adjustments to allow passage. Ontario Hydro and the New York Power Authority have installed eel laddersthat have the potential to restore healthy populations.

The river instituteis currently studying the habitat usage of eels in the St. Lawrence River as part of a research project funded by the Ontario Ministry of Natural Resources in collaboration with Ontario Power Generation, the Mohawk Council of Akwesasne, and the Department of Fisheries and Oceans.

The goal of the project is to fill in critical knowledge gaps regarding the preferred habitat conditions of eels at various life stages. Eels are considered habitat generalists and have the widest habitat range of any freshwater species in North America.