fish moves up Fox River
perch threaten Lake Winnebago
For the first time, white perch, an invasive species implicated
in the decline of the yellow perch fishery in the Great
Lakes and the bay of Green Bay, have been found in the Fox
River upstream of the Rapide Croche navigational lock and
dam northeast of Kaukauna.
species are plants or animals that enter an ecosystem
from beyond their native ranges.
Exotics are sometimes called invasive
species because they tend to take over new habitats.
Thats because natural predators arent
present outside the exotics normal range.
Native species arent adapted to exotics, and
lack the ability to compete. The population explosion
that results can upset the ecological balance of
aquatic or terrestrial habitats. Once established,
exotics are nearly impossible to eliminate.
state Department of Natural Resources
The invasion could spell trouble for fisheries in Lake
Winnebago and the Wolf and upper Fox rivers. Both rivers
empty into Lake Winnebago.
nothing that really stops these invasive species,
said Terry Lychwick, a fisheries biologist with the state
Department of Natural Resources. I dont have
any reason to believe they wouldnt just keep going
wherever they could.
Lychwick said the DNR discovered 11 adult white perch
of varying sizes in the pool above the dam in late August.
More sampling in the first two weeks of September turned
up young of the year tiny white perch
that could only have been hatched last spring.
The discovery is certain to add fuel to a debate already
raging between state officials, who have endorsed a plan
to renovate and reopen 16 of the lower Fox Rivers
17 locks to allow unimpeded boat traffic up the river
from the bay of Green Bay, and opposing sportsmens
groups who fear the move will open a Pandoras box
of invasives on Lake Winnebago.
think of the economic impact to the Lake Winnebago system
if all these exotic species get into the system and we
lose half of our fish out here, said Jim Schommer,
a Fond du Lac resident and president of Walleyes for Tomorrow.
That alone is enough to scare a lot of people.
It scares Bill McAloon, a past president of the 1,000-member
Otter Street Fishing Club in Oshkosh who opposes opening
the locks a step he said will make a tough battle
against the invasive species in Lake Michigan and the
bay of Green Bay unwinnable.
sure its just a matter of time before everything
will be up here, McAloon said.
Lychwick said inspection of the five locks upstream of
Rapide Croche offered little hope they will block passage
of white perch upstream to Lake Winnebago.
were in pretty bad shape, Lychwick said, adding
that water coursed through several. As it stands
now, there would be a potential.
Lychwick said biologists believe the lock and sea lamprey
barrier at Rapide Croche is sound, and that white perch
passed the obstacle with human help most likely
unknowing children or fishermen who broke the law against
moving fish between bodies of water.
If fishermen introduced white perch above the dam, they
may have believed they were moving white bass, a species
that closely resembles white perch, Lychwick said.
it be malicious? Yes, those things happen, he said.
The $20 million project that would create the Fox River
Heritage Parkway would open all the lower rivers
locks except Rapide Croche to boat traffic. A lift would
move boats over the dam at Rapide Croche. The Menasha-based
East Central Wisconsin Regional Planning Commission is
charged with creating the plan for the project.
really calls into question what type of management policy
you should have for exotics, said Harlan Kiesow,
commission executive director.
But Kiesow said the white perch problem is no reason not
to move ahead with the project, and pointed out that another
invasive, the zebra mussel, is already in Lake Winnebago
courtesy of fishermen and recreational boaters who moved
their boats from the lake or bay without properly cleaning
Lychwick said scientists have linked an explosion of white
perch in Lake Erie in the 1970s with reduced numbers of
white bass and yellow perch, though theres less
evidence that white perch have hurt walleye populations.
The potential exists for white perch to change the Lake
Winnebago fishery more significantly and faster than Lake
Eries because Lake Winnebago is so much smaller.
will happen, but we cant predict it, Lychwick
said. Ultimately there will be a change. Probably,
it wont be to the better.