MARQUETTE - Next time you're swimming in Lake Superior, try not to think about the beady-eyed, slithering, blood-sucking, sharp-toothed predator lurking in the deep. There's no need to worry, it won't attack humans.
This Great Lakes invader, the sea lamprey, is a relentless invasive species that preys on our lake trout, salmon, whitefish and a lot of other types of fish. It doesn't discriminate.
With its round, tooth-studded mouth, the lamprey attaches itself to a fish and drills a hole with its razor-sharp teeth to feed on the fish's blood and fluids, usually killing it. They don't just strike once, either.
Rachael Guth of the U.S. Fish and Wildlife service lays out sea lamprey on an examination tray that were found in the Dead River last week. (Journal photo by Danielle Pemble)
A close up of the species, which arrived in the Great Lakes in the 1800s, is seen. (Journal photo by Danielle Pemble)
"One lamprey can kill 40 pounds of fish," said Joseph Genovese of the U.S. Fish and Wildlife Service.
The Great Lakes fishery is worth $7 billion a year, and the U.S. and Canada believe it is worth protecting. In the 1800s, sea lampreys invaded the Great Lakes via manmade canals and shipping locks and have been there ever since. Together both countries formed the Great Lakes Fishery Commission in 1954 and have been working tirelessly to control the lamprey that threatens the fishing industry.
A U.S. Fish and Wildlife Service assessment crew conducted surveys in and around the mouth of the Dead River near Presque Isle last week to estimate the populations of lampreys in those areas.
First, a Larval Assessment Team established how far the larvae were up the Dead River. Using backpack electro-fishing gear, the team stimulated larval sea lampreys out of their burrows to measure their abundance.
The Dead River has been treated a total of three times in past years with a lampricide called 3-trifluoromethyl-4-nitrophenol, or TFM, which rids streams of larvae before they transform into parasitic adults that can migrate into Lake Superior.
The lampricide is used every four years, timed with the life cycles of the lamprey. TFM is selective in that it can remove sea lamprey larvae but generally not harm other fish and organisms.
It has been deemed safe for humans by the Environmental Protection Agency as well as Health Canada. The team rounded up quite a few specimens ranging in size from an inch to about 6 or 8 inches.
Around the mouth of the Dead River, the assessment teams, in aluminum motor boats, measured out 508 square feet with buoys to mark the area they would be surveying.
They used something called Bayluscide, which is a time-released lampricide that coats grains of sand.
"It sinks to the bottom, and irritates them," said Genovese, "then they come up out of the sand."
The lamprey come close to the surface where the crew can then scoop them up and survey the population.
The data they found during the surveys of the week will be used to determine the need for our local sea lamprey control and will answer questions like, when, how often, and how much our water will be treated.
Other methods are used to control the lamprey besides stream treatments, like building barriers to keep the lamprey from spawning while still allowing the passage of most other fish species. They also use a sterile-male-release technique that tricks females into mating sterile males, which helps reduce the population of fertile eggs. The males are too old in their life cycle to feed on fish, so they don't post a threat when released back into the lakes.
In all, the program used to drastically reduce the sea lamprey population has been a success. It is now under control, but will remain to be a continuing battle with these vamipires of the water.
Danielle Pemble can be contacted at 906-228-2500, ext. 256.