Fish Lake Reservoir north of Duluth has tilted more toward a largemouth bass lake than a walleye lake over the past decade, and the Minnesota Department of Natural Resources is trying to figure out what, if anything, it can do about it.
On Monday night about 40 people attended a DNR-sponsored meeting outlining the issue, with the agency asking concerned cabin and lake home owners, anglers and others to get involved in the effort.
They are forming a committee of interested people to meet over the next 15 months, define the issue, explore likely causes and then develop a mix of actions the DNR can take to help.
Randy Docauer, who has lived on the lake for 20 years, said he has seen more weeds and boat traffic and fewer walleyes in recent years, and he wants the lake's landowners to play a key roll on the committee.
"We really have a vested interest here. We really want to see it succeed," he said.
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But it's not clear there is any one cause or one easy fix, said Don Pereira, DNR fisheries research manager who suggested it may be a combination of factors.
"Everyone, even scientists, fall into the trap of thinking there's one problem and one solution. ... But it could well be a combination of factors all hitting at the same time,'' Pereira said.
Fish Lake is one of 14 lakes in the Duluth area that has seen a much longer growing season and higher temperatures in recent decades, with a sharp increase in largemouth bass and pan fish. At the same time, walleyes, which favor lower temperatures, have declined.
Fish Lake also has seen a marked increase in lake weeds.
Pereira said bass, crappie and bluegill could be eating small walleyes. Then again, walleyes often thrive in lakes with healthy bass and bluegill populations, "so maybe that isn't it. We don't know yet," Pereira said.
Instead, Pereira said more stable water levels under federal dam regulations imposed in 1996 may be the culprit, allowing walleye spawning beds to silt-over deeper under water rather than being scrubbed by wave action.
Ongoing lake monitoring results lead DNR researchers to believe that overfishing -- anglers keeping too many fish -- is not an issue in the walleye decline. They also say that levels of phosphorus, which can harm lakes, have not increased over the past 50 years. The lake's watershed remains relatively undisturbed and water clarity readings have r*emained stable.
"We don't think water quality is the issue. It's in pretty good shape,'' said Deserae Hendrickson, Duluth area fisheries supervisor.
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But Linda Ross Sellner, who described herself as a fan of clean water more than an angler, said she'd like to see the state conduct more water-quality research.
"You only have two measures there. What about dissolved oxygen levels and conductivity?'' she asked.
The DNR asked for volunteers to serve on the lake management committee and to help define how the committee should move forward. Information on the effort will be available on the DNR's website at www.dnr.state.mn.us and clicking on fisheries, then click on Duluth Area. Or call Hendrickson at (218) 525-0853, ext. 201.
