Zebra mussels force anglers to adjust on local lakes
(Ed. note: This is part one of a two-part series on zebra mussels and how the invasive species have impacted fishing and the fish communities on area lakes since they were first discovered in Douglas County on the Alexandria Chain of Lakes in 2009.)
Gene Sullivan has fished walleyes on the Alexandria Chain of Lakes for almost 20 years, but he tends to avoid those bodies of water most of the time these days.
Those fish, he says, have become increasingly harder to catch, a product of crystal-clear water conditions and changing habitat after the infestation of zebra mussels in 2009.
"You can't fish it on just any day of the week," Sullivan said. "It has to be windy, cloudy. Your odds go up considerably when you don't have sun. I've decided there's some better fishing out there right now. The fish are there, there's no question, but I just haven't figured out the secret."
The lakes on the Alexandria Chain are part of 42 bodies of water on the Minnesota Department of Natural Resources' 2018 infested waters list for zebra mussels in Douglas County. On Aug. 2, Amelia Lake, just a few miles south of Alexandria in Pope County, was added to the list.
The zebra mussels, which are native to Eastern Europe and Western Russia, were first discovered in the United States in the Great Lakes in 1988 after being unintentionally introduced through the discharge of contaminated water brought over on cargo ships.
Zebra mussels attach to underwater surfaces such as rocks, gravel, plants, docks and swim rafts. They feed primarily on algae, taking the nutrients from the lower levels of the water's ecosystem that other native organisms rely on for feed. One zebra mussel can filter one quart of water per day. They can also reproduce at a rapid pace, with one female able to produce 100,000-500,000 eggs per year.
Zebra mussels were first discovered in the Alexandria area on the Chain of Lakes less than a decade ago. Since then, other popular fisheries in the area have joined the list—Minnewaska in 2012, Miltona and Ida in 2013, Maple and Mary in 2014, Lake Osakis in 2016 and Lake Chippewa in 2017.
Zebra mussels can pose multiple problems for Minnesota waters. Along with their threats to the lower levels of the food chain, they attach themselves to and kill native mussels. They can clog water intakes and encrust equipment, creating some high-cost problems for cities and residents. Swimmers can cut their feet when stepping on the fingernail-sized mussel with their sharp-edged shells.
For anglers, the zebra mussels are creating another set of challenges, not necessarily in overall game fish numbers, but where those fish are found and how they are caught.
Things have changed on many of the local waters that are infested with zebra mussels.
That was the unanimous consensus of four anglers who have fished Douglas County and the surrounding area for decades in Sullivan, Joe Scegura, Mike Frisch and Drake Herd. The latter three have decades worth of guiding experience under their belts.
"Once we got zebras, it definitely cleared stuff up a lot," Herd said. "You could see the rock piles you were fishing at 13, 14, 15 feet. What it did is it changed the fishing. The weeds got thicker. Our cabbage beds, our milfoil beds, now they're really thick."
Clearer water allows sunlight to penetrate and warm the water at greater depths. That means increased weed growth and deeper weed lines.
Scegura pointed to one small body of water as an example.
"On that 1,000 acre lake, there were 20 or 30 areas that we fished little points and inside turns along this weed break," he said. "We used to be able to fish the shoreline all the way around. Now we're fishing little pockets randomly throughout the lake where the rest is kind of choked out due to the clarity. Being it's so weeded, we're down to maybe two, three spots where these fish are pretty congregated."
Fish are following the best available habitat. In many cases, anglers have to move to greater depths to find fish on the deeper weed lines.
"Last year, we could see 20 foot on a lot of lakes where normally we could see eight, nine or something like that," Scegura said. "It definitely changed things."
Frisch pointed to seeing vegetation in 25 feet on Lake Ida as being an eye opener for him. His sonar shows walleyes, a notoriously cool-water fish, in depths of 40-50 feet during the late summer on Ida, where he says he did not see them there in previous years until the fall.
Being on the water at the right time of day has become increasingly important on these lakes.
"Maybe the best example I can give is I've fished Minnewaska a lot the last few years in the fall," Frisch said. "Last year for the first time, I noticed much clearer water and a pronounced early-morning, late-evening bite with lack of a good mid-day bite that we'd had prior years in the falls. On the windy, overcast days, I could still get them good in the middle of the day. When it was flat and sunny, last year I just didn't see those catches."
The fish are still in these waters. Sullivan, Scegura, Frisch and Herd all said that.
Glenwood DNR fisheries manager Dean Beck said two surveys of lakes on the Alexandria Chain since zebra mussels were discovered have not shown enough information to suggest a declining gamefish population.
"People get really worried that they disappeared," Herd said. "They're still there. They might have moved 20 or 30 yards one way or another. You have to pay attention to the weeds around the area. They're going to move a little deeper or a little shallower. They're not necessarily going to be right on your icon you've had for 35 years."
How anglers go about catching fish has changed for many, too.
Like Sullivan, Frisch and Scegura said they will target the many lakes in the area that do not have zebra mussels in them where the water is not as clear.
When fishing the clearer waters due to the mussels, the use of planer boards to get the bait out away from the boat has become a popular strategy. Casting to the fish instead of vertical jigging can also be productive. Herd said his approach on walleyes has been to offer a slow presentation with a slip bobber or to go the opposite route with a faster-than-normal presentation in front of the fish that can trigger a bite.
All four anglers said electronics have become as important as ever when finding and boating walleyes.
"Side imaging is a big help with being able to locate those fish," Scegura said. "You kind of need new tools that way versus just driving over them and seeing them on the 2D and going back and fishing them. You would spook them right off the spot after two or three times over."
Some anglers have gone so far as to say fishing is as good right now as it has ever been in the area for certain fish species. The key, they say, is being able to adjust to find those fish.
Part two of this series will run in the Aug. 15 Outdoor section of the Echo Press. The second part will look deeper into the fisheries around Douglas County that have been infested with zebra mussels and what a yearly study done on Lake Carlos has shown at the lower levels of the system since the mussels were discovered in 2009.