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
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
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.