This story broke after Outdoor News went to
press on Monday July 1.
Warm water, unprecedented pressure narrows Mille
Aitkin, Minn – Hungry walleyes, warmer water, and more than 1
million angling hours have tipped the scales past allocation
projections at Lake Mille Lacs in 2007. Given that, state anglers
can expect the first mid-season slot limit change on the big lake
The higher-than-predicted walleye kill on Lake Mille Lacs will
trigger a 14- to 16-inch slot limit with one fish over 28 inches
allowed. The four-fish bag limit will remain in place, but the new
slot limit goes into effect on July 9, according to a press release
the Minnesota DNR issued on Tuesday.
‘Our options were limited,’ said DNR Commissioner Mark Holsten
in the release. ‘We are only 15,000 pounds below our allocation and
114,000 pounds below an agreed-upon maximum allowable kill that
would close walleye fishing. As such, we need to stretch the
harvest out over the next five months of open water fishing or risk
closing the fishery.’
As of June 30, the estimated harvest was just under 384,000
pounds. State game and fish rules called for the tighter slot if
harvest exceeded 365,000 pounds at the end of June.
Night harvest and winter and summer tournament mortality are
counted separately. They add an estimated 50,000 pounds to that
total, according to the DNR, which notes the addition puts the
total kill at about 434,000 pounds – within 15,000 pounds of the
state’s 449,000-pound allocation.
Historically, fishing pressure begins to drop after mid-June,
according to Pat Schmalz, DNR 1837 Treaty biologist in Aitkin.
However, levels remained steady throughout the month and anglers
spent a record 371,564 hours on the big lake during the second half
That is 100,000 hours more than anglers spent on the lake during
the same time period last year, according to Schmalz.
From June 16 to June 30, an average water temperature of 72
degrees – the highest recorded for that time period – accounted for
high rates of hooking mortality.
Of the roughly 90,000 pounds of hooking mortality included in
the total harvest estimate, 48,500 pounds were added in late June,
Mortality exceeded the actual angler harvest of 43,000 pounds
during the two-week survey period.
‘The extremes are usually bound by what we have observed in the
past,’ Schmalz said.’I’ve been told that the water temperature for
the last two weeks of June have been two degrees higher than last
summer, and last summer was a hot year.’
By comparison, anglers in 2006 harvested 49,400 pounds of
walleyes during the last two weeks of June, and hooking mortality
was estimated at 23,400 pounds.
Hooking mortality accelerates when water temperatures reach 70
degrees, according to Keith Reeves, a DNR fisheries biologist in
Aitkin. By the time water temperatures reach 75 degrees, mortality
in walleyes longer than 26 inches can be 25 percent – two times the
amount observed in 68-degree water.
‘We still have the hot part of summer left, and that will have
an impact on the larger walleyes,’ Reeves said.
So far this season, the bulk of the harvest has come from 16- to
17-inch fish, according to Schmalz. Predominant year-classes
include the 2002 and 2003 fish, which range from 14 to 24
With the tighter slot, Schmalz said anglers still can catch fish
in the 14- to 16-inch size class, though they appear to be less
In 2001, a low forage base led to a sustained bite, continued
angler effort, and high hooking mortality as water temperatures
rose through late June and early July. To prevent harvest overage,
the limit was reduced to a 16- to 18-inch slot that year.
Following the change, angler pressure hours dropped from 149,000
hours during the first two weeks of July to 92,000 hours during the
second half, Reeves said.
The health of the forage base will dictate how well the bite
continues through July and August, but – according to Reeves –
recent reports have indicated that the bite has dropped off
Ron Payer, DNR Fisheries section chief in St. Paul encouraged
people to keep Mille Lacs in their fishing plans, but urged anglers
to exercise voluntary restraint, noting that even catch-and-release
fishing has consequences, given the concerns over hooking
As required by state rule, the DNR said it would post the new
Mille Lacs regulation on its web site Tuesday. It will become
effective at 12:01 a.m., July 9.