Despite good walleye fishing on Lake Mille Lacs this summer, the population there of Minnesota's state fish has dipped to its second-lowest level since monitoring began in 1983. Possibly to blame: Sport anglers and Chippewa netters, both of whom target the lake's smaller male walleyes.
The decline could trigger more restrictive walleye-harvest regulations -- upsetting Lake Mille Lacs business owners, who long have sought regulation consistency, and further straining relations between the Chippewa and sport anglers.
At best, it's yet another Mille Lacs controversy, which could overshadow the hot bite that many anglers experienced this season on the huge lake.
"There is frustration,'' said Steve Johnson, owner of Johnson's Portside Bait & Liquor in Isle, Minn., and a member of the Mille Lacs Fisheries Input Group, made up of anglers and local businesses. "This was a very good year.''
Department of Natural Resources officials will meet with the group Dec. 12 to review its findings and discuss options. Agency officials will follow up with the bands in January, and a 2012 safe walleye harvest level and regulations will follow.
Johnson questions the accuracy of recent DNR gill net assessments, which documented the walleye decline. The walleye index dropped from 22.9 pounds per net in 2010 to 16 pounds per net in 2011. The lowest index was 12.8 pounds in 2007.
"They either were wrong last year, or they are completely wrong now,'' Johnson said. "It's an inexact science.''
Pat Schmalz, a DNR fisheries research scientist in Aitkin, said the trend has been unmistakable: The population of mature male walleyes -- fish generally 13 to 20 inches long -- has been declining while the female walleye population has been stable. That seems to indicate that other possible factors for the walleye decline, including a growing zebra mussel infestation, aren't to blame.
Sport fishing regulations and band net-size restrictions have prompted anglers and tribal netters to target Mille Lacs male walleyes for more than a decade, Schmalz said.
"We've had a pretty strong harvest of males ever since we started size-based regulations,'' he said.
Those regulations, including this year's 18- to 28-inch protected slot, tend to protect larger female walleyes, because anglers can keep fish less than 18 inches long.
"Then you add the tribal harvest, which has been 80 to 90 percent males as well,'' Schmalz said.
Officials aren't certain what percentage of the non-band angler harvest has been male walleyes, but data from 2006-07 indicated about 35 percent, Schmalz said.
However, non-band anglers generally are taking far more fish than the Chippewa. In 2007, angler harvest was 463,000 pounds, of which, based on those percentages, 162,000 pounds were males. That year, the band harvest was about 87,000 pounds; 74,000 pounds would have been male.
Both are significant amounts, Schmalz said.
"We expected to see a change in the male-female ratio, so this is not unexpected,'' he said. "The thing that is unexpected is to see the decline [of male walleyes] continue.''
Officials don't know the longterm effect of the sex ratio disparity on the lake's walleye population.
"We still see excellent natural reproduction on Mille Lacs,'' Schmalz said.
And it appears that 2011 was a good "year class'' of walleyes.
Still, the DNR's poor walleye survey results means the state can no longer exceed the harvest quota, as it has five times since 1997. The change may or may not affect anglers in 2012.
This year, the "safe harvest'' was set at 540,000 pounds, with the state allocated 397,500 pounds and the bands getting 142,500 pounds. But neither came close to taking those amounts. Anglers harvested 230,000 pounds (down from 270,000 pounds in 2010). Due to the late spring and ice-out, the bands harvested 61,000 pounds (down from 124,000 in 2010).
The latest walleye survey also could force officials to lower the safe harvest level for 2012.
"I would find it hard to believe the safe harvest level could be as high as it was this year, but I don't think it would be ridiculously lower,'' Schmalz said.
And because the state won't have any leeway once the harvest quota is set, the DNR might have to impose more restrictive walleye regulations from the start of the 2012 season, or it could maintain existing regulations but tighten them later if angler harvest appears heavy.
The Legislature gave the DNR authority last session to more quickly make mid-season regulation adjustments on Mille Lacs.
Doug Smith • firstname.lastname@example.org