Lake Winnie Zebra Mussels Impacts-2018-Public Forum

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• published: 22 Mar 2018
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Winnibigoshish Water Clarity Doubles due to Zebra Mussels. Minnesota Department of Natural Resources Public Forum-Grand Rapids Mn-March 20th 2018. Zebra mussels double water clarity in Lake Winnibigoshish By John Myers on Mar 11,2018 Duluth News Tribune The first zebra mussel babies, called veligers, were confirmed in Lake Winnibigoshish in 2012. By 2016 the first adult mussels were spotted. By 2018 the invasive filter-feeders are everywhere in the lake, located west of Grand Rapids. "They've just exploded in number in just a couple years. It's amazing. They're on every smooth substrate down there," said Gerry Albert, Lake Winnibigoshish large-lakes fisheries specialist for the Minnesota Department of Natural Resources. It's one of the fastest infestations of the thumbnail-size mussels from Eurasia, known for their zebra-striped shells, that are marching across Minnesota, mostly spread by anglers and other boaters from lake to lake. The mussels filter algae and other particles out of the lake wherever they go, and that in turn makes the water more clear. For Big Winnie, the water clarity increase has been rapid and astounding — more than doubling, from 6-7 feet before the mussels arrived to 14 feet and more now. Doug Jensen, aquatic invasive species expert for Minnesota Sea Grant, said the Winnibigoshish zebra mussel explosion happened faster than in most lakes they have invaded but was "not unheard of." And he warned people to get used to the ever clearer water. "Each of those little mussels can filter between one and four liters of water every day," Jensen noted. "They're taking a lot of good food out of the water column and leaving a lot less on the plate for the rest of the food web." Fewer fish? What impact the mussels will have on Winnibigoshish's storied reputation as a walleye fishing legend is unknown. But the big change in the lake's ecosystem, along with other issues in walleye reproduction, was enough for DNR officials to call a special public meeting for March 20 in Grand Rapids. So far, no fishing regulation changes are proposed. And there's no known way to get rid of the zebra mussels. "I don't want to blame zebra mussels for the (walleye) recruitment issue. They are two different things going on once, or maybe multiple things," he said. Big walleyes are doing well, growing fat and fast on an abundance of perch and shiners. "We're just not seeing the small fish moving up into the" size anglers want to catch. There have also been fewer male fish showing up in spring to spawn. Not only are there fewer catchable walleyes, but the newly clear water is apparently making them harder to catch. Walleyes are notorious dark-water feeders, avoiding bright light when possible as they seek their prey. As water clarity increases, so does light penetration, and that makes walleyes scatter to deeper waters, or water with more weeds, where anglers aren't used to fishing "I think I only fished (Winnibigoshish) four times last year and all we caught were big fish. There's something wrong there where we aren't seeing small fish at all,'' Neustrom said. Neustrom said it's not yet clear if Winnie's problems are similar to Mille Lacs Lake where an explosion of zebra mussels was accompanied by a declined in walleye fishing — too soon to say what role the mussels may be having on the fish. But because giant Lake Winnibigoshish also is connected to the Mississippi River, DNR officials say they are also checking to see if the invader has moved downstream. Clean, drain, dry Zebra mussels can't move on their own, but they move with currents or are moved — usually accidentally — by people. They attach themselves to any smooth surface under water and feed by filtering nutrients out of the water. Zebra mussels are believed to have moved from their native Eurasia into the Great Lakes in the ballast of oceangoing ships. They first were found in Minnesota in the Duluth harbor in 1989 and then began to explode in numbers in the Twin Ports harbor by 1998. They also have moved north into Minnesota through the Mississippi River system and have been moved by humans into several lakes. But experts say it's not inevitable they will invade every lake. While more lakes and rivers are seeing invasions of aquatic invasive species, efforts continue to keep the invaders from spreading. So far, the effort appears to be working to at least slow the spread. Jensen noted only about 1 percent of Minnesota's 11,000 lakes are infested with zebra mussels, just a fraction of what would be infested if people weren't taking precautions. Boaters, anglers, divers, waterfowl hunters and others who visit infested lakes are urged, and required by law, to prevent moving any water from one lake or river to another. It's also mandatory to empty bilges and livewells and remove any weeds from boat trailers. The rules mean draining, cleaning and drying all parts of boats that are trailered to different lakes. It also means not moving bait between lakes.