COPPER COUNTRY - The U.S. Fish and Wildlife Service is out patrolling Copper Country waters in search of sea lamprey once again.
The sea lamprey originally got into Great Lakes water nearly a century ago and has been causing damage to Great Lakes fish ever since. The parasite latches on to fish, and often times will cause the fish to die.
The sea lamprey is also found in the ocean, where sharks and other large sea creatures typically play host. Larger creatures can survive as a host because the lamprey typically won't grow any larger than two feet in length.
This week the USFWS began surveys in the Sturgeon River and off the mouth of the Traprock River to estimate the abundance of sea lampreys in those areas.
"The Traprock River was treated earlier this spring and that removed several year-classes of lamprey," supervisory fish biologist Michael Fodale said. "In this case we would have probably removed spawn that came in 2006. We wouldn't have gotten the 2009 year class.
"Now our crews are going to look for a couple things; they're doing electrofishing looking for survivors and they are also going to be looking for sea lampreys off shore of the Traprock River. There may be several different year-classes represented."
To do that, they'll set up buoys around a 500-square-meter plot. They'll then apply a chemical that causes the lampreys that are present to float to the top, where they are scooped up.
Fodale said the chemical causes no damage to the ecosystem, but allows them to remove and research the parasite.
"In the case of the Sturgeon River, they won't be looking off-shore, it has a very deep and slow-moving estuary," Fodale said. "So they would be looking in the lower part of the water for sea lamprey larvae. When we look at the Sturgeon we can look at how many there are and at the size of them, if they're larger than that tells us that our treatment to remove them needs to come relatively soon.
"If we're not finding very many, or we're not finding larger ones, that means we don't need to time our treatment for next year, but maybe two years."
Currently the crews are working between Houghton and Ontonagon on a different river.
"Our lampricide treatment crew is at the West Sleeping River," Fodale said. "The treatment crew arrived on Tuesday and the treatment is being complicated because of low-water conditions, but the West Sleeping River is very interesting because it has never really had sea lamprey in it before, so this is a newly infested stream and we figure it probably got lamprey in 2005 or 2006 and we're treating it this year to remove three or four years of sea lamprey."
The efforts are usually successful.
"Typically we get between 95 and 99 percent of the larvae that was there," Fodale said. "they can go as far down as a few thousand in population or as many as millions, such as in the Ontonagon River."
For additional information about sea lamprey, or to learn more about the tests visit glfc.org.
Michael H. Babcock can be reached at mbabcock@mininggazette. com.