Superior lamprey numbers increase
The Mining Journal
Published August 28, 2005
DULUTH, Minn. (AP) - Lake Superior's population of bloodsucking,
fish-killing sea lamprey is exploding, and scientists
are trying to determine if it's a temporary spike or a
The numbers of the eel-like creature, which feed by attaching
their teeth-filled mouth to lake trout and other fish,
has nearly doubled in western Lake Superior in the last
year, according to state and federal biologists, who are
taking new measures to battle the lamprey.
The numbers are even worse in the Wisconsin Department
of Natural Resources' lamprey trap in Brule River, which
feeds into Lake Superior. Mike Seider, a fish biologist
for the agency, said crews trapped 9,478 lamprey this
year, three times last year's catch and the most ever
in the barrier's 20-year history.
Scientists are also finding more wounded fish. In the
lake's western area, the number of lamprey scars on big
lake trout is up more than 400 percent - 26.9 scars per
100 trout, compared to just 6.4 per 100 trout last year.
So far, it hasn't significantly reduced the number of
lake trout, according to scientists. But they say that
could change quickly if they can't stem the increasing
"We're also finding lamprey marks on other species
- like suckers, whitefish and herring - and that's a clear
sign there are a lot of lamprey out there,'' Seider said.
It's got scientists battling lamprey larvae in new locations,
including in the lake itself, and not just streams.
The problem isn't confined to western Superior. The U.S.
Fish and Wildlife Service said the lake's overall lamprey
population jumped 23 percent from 2004 to 2005, according
to Jessica Richards, a Michigan-based marine biologist
for the agency.
"It's a significant increase, especially in the
west,'' Richards said. She said lamprey numbers in western
areas of the lake jumped from 35,000 last year to more
than 62,000 this year.
Superior is the only one of the Great Lakes with a major
lamprey increase, Richards said. While Lake Erie had a
minor increase this year, the other Great Lakes saw a
decrease, with Lake Michigan showing about half as many
lamprey this year as last.
Scientists have identified several hot spots they believe
are mostly responsible. One is a series of Ontario streams
near Thunder Bay that previously didn't hold lampreys.