Lake Winnibigoshish and zebra mussels were the main topics of a public meeting held by the Minnesota DNR in Grand Rapids this week. Lake Winnibigoshish large lake fisheries specialist Gerry Albert was there to lead the discussion with over 100 individuals in attendance. People wanted to know how zebra mussels got into Lake Winnie, what impact they have on the lake, and what the future impacts might be.
Winnibigoshish is more commonly called Lake Winnie. It's a destination lake for both walleye and perch. As Gerry Albert says, "People from all over the nation come to fish it. It sits in a really productive sand plain that makes its base productivity higher than many of the other lakes in this area - so it can hold more pounds of fish per acre of water. Fortunately it's fish people like to catch - walleye and perch - so if they can catch more, they like that, and they come to a lake where they can catch a lot."
The infestation of zebra mussels seemed to happen fast. In a sampling the DNR found just 2 immature ones (called veligers) in 2012. None were found in 2013. They were back in 2014. "Then," Gerry says, "we put divers in the lake to look for adults. They looked in all the classic habitats - rock from near shore to the middle of the lake - and we couldn't find any... We had an angler report early in 2016, of catching a piece of driftwood with zebra mussels on it. ..so we checked it out and every piece of driftwood we picked up in 3-4' of water had some zebra mussels on it. "
One of the primary changes in the lake brought on by the mussels will be to the location of fish, especially walleyes. "One of the things that's consistent [on lakes infested by zebra mussels] is the water clarity," Gerry Albert explains. "The water clarity leads to angling challenges with walleyes because walleyes have those really large eyes. They're very sensitive to light, and if the area they used to be in that was dark because of plankton in the water is now clear, they aren't going to be in those areas. So the fish aren't where the anglers expect them to be which causes more difficult conditions. They wonder what's going on because they used to catch walleyes and now they don't. That's part of the reason we had the meeting."
No changes to the fishing regulations are being contemplated due to the presence of the mussels. "Right now there are less small walleyes in Winnie than we've had in the past and we're trying to figure out why that is," said Albert. "But it doesn't appear that a regulation can fix it."
There is currently no way to rid a large lake of zebra mussels. "Winnie is such a large system and it's fed by several other systems, and one of those other systems [Cass Lake, upstream] is infested with zebra mussels. That's how they got in to Winnie. It's not likely we can control zebra mussels - it hasn't worked anyplace else. But there's a lot of genetic work being done to try to find a cure. "
Waters flowing out of Winnie pose a risk of zebra mussel infestation downstream. "Anything that's downstream will likely have zebra mussels sometime in the future," Gerry Albert said. "Research has tracked the genetic makeup of the zebra mussels that got into Cass and now in Winnie. This distinct population originated in Brainerd. So these critters are kind of going home. They started in Brainerd, came up to Cass to Winnie, down the Mississippi, back to Brainerd."
Zebra mussels have been found in lakes in the eastern US for decades. That's where Gerry Albert looks to see possible long-term impacts. "Initially you see changes in walleye recruitment where you have longer distances between strong year classes, but then it seems to moderate. Not that the lakes go back to what they were...on a lake as a whole, what the zebra mussel does is it pulls energy from the middle of the water column which is where many of the fish that a walleye would feed on live, and it takes that energy and converts it down to the bottom. So it takes it down to where bottom living organisms benefit. And that's probably part of the reason why you see changes in walleye reproduction recruitment initially. It's because that energy that they need in the middle of the water column is now down on the bottom...
"That energy flow going to the bottom should benefit organisms like crayfish - perch love to eat crayfish and grow fat and sassy on 'em. Potentially in Winnie movement of energy from that mid-water column to the bottom could help perch, which anglers really like to catch and eat."
So far the Northern Pike don't seem very affected. Gerry Albert says, "Northern Pike in Winnie are abundant and of really good average size. They fight great, they eat great. They're not as popular as walleye but they fight just as good and they taste just as good. The population continues to increase over time so there doesn't seem to be any negative impact."
Lake Winnie has also been affected by another aquatic invasive species, starry stonewort (more about it in the interview below). Anglers can do a lot to help prevent the spread of invasives to more lakes:
- Take care when moving equipment from lake to lake
- Don't move any water, or the animals themselves, or plants
- Use a hose to flush live wells
- Drain water from boats. Tip boats up at the bow during storage
- Clean all vegetation off trailers
- Dry all equipment thoroughly
There is more information about the Lake Winnibigoshish fishery and the invasive species that are affecting it from Gerry Albert in the full interview below: