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Great Lakes Article:

Finding sea lampreys a shocking experience
By Brian Mulherin
The Associated Press
Published May 31, 2004


LUDINGTON, Mich. (AP) The most impressive thing to Jeff Slade is just how much life there is under the silt.

"There's an amazing amount of biomass that nobody ever sees," Slade said.

Nobody except Slade and his crews. Slade is the Lamprey Assessment Program team leader with the U.S. Fish and Wildlife Service's Ludington Biological Station.

Every year, the USFWS surveys dozens of streams that flow into the Great Lakes for sea lampreys.

Adult sea lampreys attach themselves to fish and drain their blood. The invasive species is blamed for decimating Great Lakes lake trout populations. But in their larval stage, sea lampreys are harmless and hidden.

How do you find something that burrows into the soil of creekbeds and feeds only on decaying matter and bacteria? You mix electricity and water.

Slade straps a backpack powered by a gel-cell battery on his back all summer long and wades the state's streams waving three-foot-long electrodes. The pack, designed at the University of Wisconsin, provides either 30 or 300 pulses of 125 volts of electricity per second to the electrodes. The water between the electrodes conducts that electricity to make a field that shocks any lifeforms nearby.

Slade first shocks the water with a slow pulse, which makes the lampreys uncomfortable, forcing them to swim from their burrows in the silt.

Once they appear, he shocks them with a faster pulse which makes them wiggle wildly, then immobilizes them. On the end of the electrodes are mesh scoops. Slade scoops up the lampreys and places them in a bucket.

Recently, it was Gurney Creek's turn to be surveyed. Slade shocked for about five minutes at a site off Old Free Soil Road. He found 10 sea lampreys ranging in size from 44 millimeters to 125 millimeters. He also found six American brook lampreys, which are native to the state.

The presence of a sea lamprey about 120 millimeters long generally means that some of the lampreys in the stream could metamorphose into adult lampreys the following year.

When lampreys of that size are found, Slade's teams plan to come back for a second survey called a quantitative analysis. They measure plots of prime habitat and shock them for set amounts of time, picking up any lampreys they find.

By measuring the amount of prime habitat in a given area and shocking that area, biologists can calculate the abundance of lampreys in the entire stream. The surveyed streams are put on a list with other streams where sea lampreys are present. Those with the most potential to produce adult lampreys are at the top of the list and are treated with the lampricide TFM first.

Crews treat the streams on the list until their budget is expended for the year. Some streams with the potential to produce adult lampreys don't get treated.

"It's not an eradication program," Slade said. "It's a management program. Our real goal is to manage sea lampreys into balance with our other biological objectives."

Sea lampreys still have an open avenue into the Great Lakes from the Atlantic Ocean, Slade noted.

 

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