TRAVERSE CITY -- A sea lamprey's toothy, suction cup of a mouth rasps a hole in a fish's side and feeds off its fluids.
The invasive species came from the Atlantic Ocean into the Great Lakes in the 1920s and decimated native fish populations. Efforts to reduce the number of sea lampreys in the Great Lakes began in 1958 and pushed the lamprey population to about 10 percent of that of its heyday.
Crews from the U.S. Fish and Wildlife Service will continue that effort and survey the mouth of the Boardman River and Boardman Lake for the destructive sea lampreys. Crews are expected to work from June 4-12.
“The Boardman River is a regular producer of sea lampreys," said Michael Twohey, the acting station supervisor for the FWS Ludington Biological Station.
FWS crews survey the area every three or four years and use lampricide to target the lamprey's larvae population. Data is collected during the summer and analyzed over the winter.
Crews search for lamprey in their larval state before they become parasitic. Crew members send an electric pulse or a toxicant through water, which stimulates or irritates the lampreys so they emerge from river or lake beds.
Lampreys are most commonly found attached to fish in the springtime, said Scott Alpers, owner of Big Kahuna Charters in Traverse City.
"We catch one probably at least every other charter, up until about when the water starts getting warmer the third week of June, then it slows down to one a week," Alpers said.
They mostly attack lake trout, and whenever Alpers pulls up a lamprey he kills it. Lamprey also attack salmon and steelhead.
The Boardman River is a great habitat for sea lamprey larva because of its water quality, spawning gravel and soft, silty substrate, Twohey said.
It would be a larger lamprey habitat if not for the Union Street Dam, which keeps lampreys from moving upstream, Twohey said.