Scientists have made a shocking discovery about an invasive species threatening the Great Lakes. Electricity is an effective weapon in the fight against the blood-sucking sea lamprey, researchers with the Great Lakes Fishery Commission say.

Working with lamprey swimming upstream during spawning season in the Chocolay River near Lake Superior in Michigan's Upper Peninsula, researchers used electrical currents to guide the lampreys into specially-made traps at night.

"It works similar to a dog collar or invisible fence you'd have in your yard. The lamprey would sense the electricity as it gets closer, just like a dog with a collar," explained Marc Gaden, the communications director with Great Lakes Fishery Commission.

"As the lamprey feels the electricity, it'd be guided toward that trap," he said. 

With that electrical current set up, the chances of catching a lamprey in the trap jumped to 75 per cent, up from 50 per cent without the electricity, according to the research published by the journal Nature and funded by the Great Lakes Fishery Commission. 

hi-wdr-sea lamprey experiment-August 22, 2016

Using electric currents, researchers are able to successfully divert more sea lampreys into traps, helping to control the population. (N. Johnson/USGS)

The sea lamprey has long been a menace to fish in the Great Lakes. Gaden said at one time lampreys would eat 45.3-million kg of fish throughout the Great Lakes. But that number has been reduced to fewer than 4.5 million kg today through control efforts.

Those programs involve lampricide, physical barriers and traps, Gaden said.

"If you can trap a lamprey you have a chance to remove it from the system before it gets a chance to spawn and produce the next generation," Gaden said. "We want to do everything possible to increase the effectiveness of our trapping operations."

Using electricity as a control measure isn't exactly new though. Early research into killing sea lampreys involved electrical currents. Gaden said that was later abandoned because those electrical currents "may have fried anything that came in contact with it."  

wdr-sea lamprey electricity-August 22, 2016

Streams and rivers that feed into the Great Lakes can be spanned with metal rods, when an electric current flows through this apparatus, sea lampreys can be diverted into traps. (N. Johnson/USGS)

Today, the electrical current is not strong enough to hurt other fish that come in contact with it.

Since most fish do not fit into the lamprey traps and smaller fish that do swim into the traps are released, the electrical currents don't pose a threat to the wider ecosystem of the Great Lakes basin, Gaden said.

"In a way, we've come full-circle with lamprey control," Gaden said. "In the 1940s and 1950s when we were scratching our heads wondering how to deal with this beast, some of the earliest lamprey control techniques involved crude electric devices."