Where’s Walleye? Mille Lacs population takes an unexpected dip

Gone fishing?: Where have the walleye's gone on Minnesota's Lake Mille Lacs? Fall surveys this year show about half the number of fish in the state's "walleye factory" than typically are found. (Photo courtesy of the U.S. Fish and Wildlife Service)
Gone fishing?: Where have the walleye's gone on Minnesota's Lake Mille Lacs? Fall surveys this year show about half the number of fish in the state's "walleye factory" than typically are found. (Photo courtesy of the U.S. Fish and Wildlife Service)
The walleye is Minnesota’s state fish. And the No. 1 lake to catch walleyes in the state is generally considered to be Lake Mille Lacs. But fish population censuses conducted this summer on Minnesota’s walleye factory have fisheries managers scratching their heads.

You may have read or heard some of the headlines about this in recent days. Some of those reports sensationalized the situation. While the walleye numbers are down on the lake, they’re by no means at critical conditions, the Minnesota Department of Natural Resources (DNR) reports.

Routine testing done on the lake this summer corralled only about half the usual number of walleyes as the average number collected between 193 and 2006, the DNR says. The tests, conducted near shorelines are done annually to monitor fish populations and size.

“We expected some decline in walleye numbers based on a number of factors, including a weak 2004-year class of walleye,” said DNR Fisheries Chief Ron Payer. But the magnitude of this year’s decline was unanticipated.”

This year’s net catches averaged 7.2 walleyes per net compared to the 15.4 average from the previous 14-year average of 15.4 walleyes per net. Similar sampling done last year collected 20.4 walleyes per net.

So why the big drop?

Payer said that warm lake water, particularly in June, may have played a significant role in the drop. Warmer water temps stress fish and hooking mortality rate goes up as water temperatures go up, as well.

Is the situation critical?

Not yet, Payer said. But the reason the DNR does the annual walleye population survey is to gather data on setting limits for the coming fishing season. And there’s no doubt, he said, that those regulations will likely be tightened in 2008.

But he added that Mille Lacs still has a strong number of spawning-sized fish.

Payer said anglers should know Mille Lacs continues to hold good numbers of spawning-sized fish. Still, the new data means the DNR will need to revisit regulations to ensure the lake’s walleye harvest stays within the safe harvest level and the state’s allocation. No walleye harvest overage will be allowed in 2008 due to the lower than anticipated number of walleye in recent population assessments.

Because of several factors, Mille Lacs’ walleye population is regulated differently than other Minnesota lakes. Through a treaty with the Chippewa Indian bands negotiated in 1837, those bands have significant fishing rights on the lake. Those rights are taken into account with sport fishing limits each year in managing Mille Lacs’ walleye population.

This past year, sport anglers could only take four walleyes a day. They had to be between 14 and 16 inches in length, with the exception made for one walleye longer than 28 inches long. Earlier in the season, the limits were actually less restrictive, but heavy fishing success in the early part of the summer required tightening the Mille Lacs limits.

Regulations for the 2008 open water season will be established in February 2008 and go into effect with the walleye opener on May 12.

So do you have a theory on what's happened to the walleyes? Share your thoughts here with other Science Buzz readers.

Minnesota DNR press release on Mille Lacs walleye numbers

Your Comments, Thoughts, Questions, Ideas

Anonymous's picture
Anonymous says:

Hey I think walleye are sweet

posted on Wed, 10/31/2007 - 10:27am
Anonymous's picture
Anonymous says:

I think the fish are just getting smarter. With all the netting going on at Mille Lacs it makes sense to me they see the net coming and swim away from it. Same reason why we use planner boards; because they swim away from the boat. They may only have a brain the size of pea, but that doesn't mean they can't learn.

posted on Mon, 11/19/2007 - 1:40pm

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