MARQUETTE - It's one of those creations of nature that if kept in its original habitat might be unique and valuable in the ecosystem. But in the Great Lakes region, the sea lamprey is considered a scourge.
According to the Great Lakes Fishery Commission, sea lampreys entered the Great Lakes through man-made shipping canals and were first seen in Lake Ontario in the 1830s, although Niagara Falls acted as a natural barrier to lakes Superior, Michigan, Huron and Erie. With the 1919 deepening of the Welland Canal, built to bypass the falls, lampreys made it to the other lakes. Lampreys now are found in streams throughout the Great Lakes basin.
The U.S. Fish and Wildlife Service's Marquette Biological Station on Wright Street in Marquette Township focuses on controlling these invaders.
Michael Twohey, adult unit supervisor at the U.S. Fish and Wildlife Service’s Marquette Biological Station, shows how an electrofisher works to aid in sea lamprey control. (Journal photo by Christie Bleck)
Lampreys are parasites that feed on fish like lake trout and whitefish, attaching themselves to the larger fish and feeding on their body fluids, mostly blood. That leaves the fish open to infection and eventually mortality.
Lampreys are controlled through various methods, including lampricides (primarily TFM), barriers and trapping.
Michael Twohey, supervising fish biologist and adult unit supervisor at the station, said the entire lamprey program for the United States and Canada costs $20 million per year to run.
Considering the potential damage to valuable fisheries, that might be worth it.
"Many of the species of the fish that currently inhabit our lakes would be extirpated, especially the larger, economically important fish," Twohey said.
A lamprey will kill about 40 pounds of lake trout during the 18-month period when it's in the parasitic stage, he said.
Anatomically speaking, the sea lamprey is unusual as far as typical fish go. Resembling an eel, it has a suction cup-like mouth with teeth that allow it to hold on to a fish and prey on it.
"The tongue is what makes the hole in the fish," Twohey said.
Like salmon, sea lampreys can survive in saltwater and freshwater, although they grow three times as large in the ocean, he noted.
"I've been out East," Twohey said. "They're very scary."
Twohey said controlling the lamprey poses special challenges that he doesn't believe are insurmountable.
"They're an ancient fish, which is their key to survival but opens up some keys to control them," Twohey said.
A lamprey, he explained, is not as evolved as a trout, which would excrete lampricides that in the lamprey's case interfere with its metabolism and kill it.
Electrical barriers, Twohey noted, were used in the 1950s to control lampreys.
"But they were not entirely effective," he said. "They were dangerous."
Other barriers, however, have worked. The Manistique Papers dam, which is more than 100 years old, is deteriorating, meaning lampreys can breach the dam and spawn upstream, Twohey said. The Upper Manistique River now is infested, although Manistique Papers, he pointed out, is working with the Army Corps of Engineers to rebuild the dam to control lampreys.
At the Marquette Biological Station, almost half the staff is seasonal, with work in the field lasting about six months, he said.
"During the peak of our season, we have about 90 people working here," Twohey said.
A smaller sister USFWS station in Ludington and Fisheries and Oceans Canada's Sea Lamprey Control Centre in Sault Sainte Marie, Ontario, are two other lamprey control agents.
The Marquette station houses lots of equipment to aid staff in lamprey control. For example, Twohey said microscopes are used to study the effect of lampricides on insects. Electrofishers irritate lamprey larvae in water, after which they are scooped up and brought back to the lab where they are examined. Information then is entered into a database to estimate the population size in that body of water.
Lamprey control has been successful in bringing back the once-decimated lake trout fishery, with the Great Lakes Fishery Commission saying ongoing efforts have resulted in a 90 percent reduction of lamprey populations in most areas.
Locally, lampreys are prevalent, according to Twohey, in the Chocolay River, the Carp River and Harlow Creek. Unfortunately, they are found elsewhere, he said.
So, are sea lampreys permanent residents in the Great Lakes basin? There is no means to eradicate the sea lamprey from the Great Lakes, at least for now. However, research is under way to provide a means to accomplish that in future decades, Twohey said.
"I think research will result in new technologies, particularly genetics, that will provide opportunities to eradicate in the future," he said.
Christie Bleck can be reached at 906-228-2500, ext. 250.