“…fisheries … without ice on the lakes during the winter and without
walleye, musky or trout fisheries,” Lyons said.
“There will be dramatic changes, though there are a lot of uncertainties,”
Capital Times (Madison, Wisconsin) madison.com
August 29, 2007
How much warmer will it get?
Special to The Capital Times
Wisconsin anglers may want to trade in their trout flies for catfish
bait if climate change is indeed for real.
John Lyons, a scientist in the fish and habitat research section of
the Wisconsin Department of Natural Resources, no longer wonders if
global warming is for real.
Due to the gasses already put into the atmosphere, Lyons believes a
warmer climate is a given.
Now, the important questions are: How much warmer will it get, and
what will the effects be?
The result, Lyons believes, is that Wisconsin anglers could be looking
at a future fishery that is similar to that of present-day
“The big uncertainty,” Lyons said, “is how much warmer will it get? It
is difficult to estimate, but the general range is that temperature
could increase from a low of 5 degrees to a high of 16 degrees
What this means is that if the temperature only goes up an average of
5 degrees, or the best-case scenario, Wisconsin’s climate could be a
lot like Illinois’.
In the worst case, if temperatures increase by an average of 16
degrees, Wisconsin would be more similar to the state of Mississippi.
“This would mean that the fisheries would be very different, without
ice on the lakes during the winter and without walleye, musky or trout
fisheries,” Lyons said. “There are, however, largemouth bass, catfish
and crappies in Mississippi waters.”
It is also likely that extreme weather events will increase. Flooding
will be more frequent and more severe, as will drought.
The question of how precipitation would change depends on several
assumptions, and if it gets wetter that could offset some of the
negative impact, for instance for trout. But if it gets drier, the
impacts will be worsened.
Lyons gave several scenarios recently in a talk to the Wisconsin
Outdoor Communicators Association for different waters, including:
Trout require cold water and the best-case scenario (with only a 5
degree warming and more precipitation) could increase the ground water
going into streams and more groundwater will help moderate the
temperature impact on trout. But the worst-case scenario (if it were
to become 16 degrees warmer and drier) could substantially reduce
trout fishing opportunities.
Currently, the state has an estimated 13,000 miles of trout stream
habitat and in the best-case scenario the state could lose about 3,000
miles of streams, or a 17 percent decline. But in the worst-case
scenario, 99 percent of the trout streams will not support trout.
“There will be losses to trout no matter what we do, but impacts will
be most dramatic with the worst-case scenario,” he said.
Warm water rivers
With a slight warming, bass and muskies may have a longer growing
season and could spawn earlier, which may not be bad. However,
negative consequences could include summer thermal stress, a decline
in water quality, and with enough warming muskies and walleyes could
Although catfish and largemouth bass could thrive, the walleye fishery
below the locks and dams on the Mississippi River could disappear,
along with muskies in the Wisconsin, Chippewa and St. Croix rivers.
Lyons said that some species need water temperatures to be below 50
degrees for a month or so to complete the development of the
The longer growing season and warmer spring weather could benefit
bass, but negative influences include worse water quality, waters that
are more hospitable to exotic species, and probably no ice fishing
during the winter.
“As reported by John Magnuson, of the UW-Madison Limnology Center,
there is a very strong decline worldwide in the length of time lakes
are ice-covered and it could be that they will not freeze,” he said.
Their large size buffers them somewhat from impacts, but they will
still see changes. The negatives include lower water levels (the
warmer it gets the more evaporation there will be), and more chance of
additional exotic species surviving.
“There will be dramatic changes, though there are a lot of
uncertainties,” Lyons said. “There is a much longer list of negatives
than positives. Some level of global warming is inevitable, but what
we do will determine how severe it will be.”
Lyons believes that reducing greenhouse gases and developing new
technologies could move the outcomes toward the best-case scenarios.
“It is not hopeless, but for people who like to hunt and fish and use
water-based recreation, the effects will be felt,” Lyons said.
He adds that if society waits another 10 years to make changes it may
be too late to make an impact.
Tim Eisele is a full-time freelance outdoor writer and photographer.
He is a founding member and past president of the Wisconsin Outdoor
Communicators Association and active member of the Outdoor Writers
Association of America.
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