Lake of the Woods Survey Yields High Walleye Catches
Article written by Brad Dokken of the Grand Forks Herald
As a longtime fisheries biologist on Lake of the Woods, Tom Heinrich has learned to expect the unexpected when it comes to fish population surveys.
Take last year, for example. Heinrich, large lake specialist for the Department of Natural Resources in Baudette, Minn., said walleye catches during the annual September survey on Lake of the Woods averaged about 14 fish per net, lagging behind the long-term average of 15 to 15½ walleyes per net.
This year, by comparison, the annual September survey yielded a whopping 22 walleyes per lift along with about 21 saugers, which is higher than the long-term sauger average of 13.9 but on par with the 10-year average.
On paper, at least, results from this year’s survey are good news for anglers itching to hit the big lake when the ice is safe enough to access sometime in the next couple of weeks.
That being said, Heinrich said the results are open to interpretation, and anglers should resist reading too much into the findings.
“The fish were more vulnerable to the nets this year for whatever reason,” he said. “We can’t address why—it just seems they were high.
“Even sizes I expected to be below average, everything was high, and you just don’t see that normally,” he said. “But the deal is, we’re still looking at a pretty good, robust walleye population—even with that interpretation thrown in there.”
As part of the September survey—which targets juvenile fish but also samples walleyes up to about 25 inches—DNR crews set four, 250-foot nets at each of 16 sites along the Minnesota side of Lake of the Woods from the south shore to the Northwest Angle. The nets are left overnight, and crews pull them the next day.
The survey begins the Monday after Labor Day and continues for about three weeks.
Keeper-size walleyes in the 12- to 16-inch range were more abundant than normal, Heinrich said, and 17- to 20-inch walleyes were on par with normal levels.
The survey doesn’t sample larger walleyes very efficiently, “But they appear to be at least at normal levels of abundance,” he said.
Saugers look good
Saugers numbers also look good, Heinrich said, and fish from 12 inches to about 15 inches are relatively abundant.
“We’re looking at fairly good size distribution there,” Heinrich said. “That’s of interest to people fishing this winter.”
Saugers, which bite throughout the day, are the flagship of Lake of the Woods’ booming winter fishery, which in recent years has drawn more than 1 million hours of ice fishing pressure. Walleyes, by comparison, tend to bite best during low-light periods.
Sauger abundance in the September survey has trended above long-term averages for the past decade or so, Heinrich said, with fewer peaks and valleys than managers used to see.
“It seems sauger reproduction has really stabilized,” Heinrich said. “It’s much more stable than it used to be. I can’t tell you why that is, but it does seem there’s been some change in the recruitment of sauger. It has been much more stable.”
Recruitment refers to new fish added to the population.
Perch and plankton
Perch catches were higher than recent years, Heinrich said, and the survey tallied about 15 perch per net. That’s slightly higher than the long-term average of 14½ and well above the past 10 years, he said.
Heinrich said Lake of the Wodos’ perch population has undergone several changes since the discovery a decade ago of spiny waterfleas, an invasive species that outcompetes native zooplankton eaten by smaller fish.
Fewer perch have been recruited to the population, he said, but the ones that survive to a size large enough to eat spiny waterfleas are growing fast.
“They really seem to take off,” he said. “Even though abundance is down, our growth rates are way up. Fish that are 5 or 6 years old are hitting 12 inches long, whereas in the past, those were 9- to 10-year-old fish.
“It’s kind of a good news/bad news thing. We’re seeing good growth, but poor recruitment.”
Fisheries crews collect water samples to monitor zooplankton, and spiny water flea numbers this year on Lake of the Woods were down from previous years, Heinrich said. Tullibees from banner hatches in 2014 and 2015 seem to be cropping off the invasive spiny waterfleas, he said.
That’s having a positive impact on native zooplankton.
“We’re seeing zooplankton species in our sampling we haven’t seen for several years,” Heinrich said. “We’ll have to see how these tullibees hang in there. It would be nice if they’d learn to take advantage of (spiny waterfleas) and control them a bit, but I’m not convinced that’s going to happen yet.”
Heinrich said walleyes sampled in the September survey were distributed fairly evenly across the lake, unlike 2014, when nets set near Driftwood Point closer to the Northwest Angle produced as many as 130 walleyes while south shore catches lagged.
“Driftwood is historically a good site for us, but it didn’t stand out like it did that one year,” Heinrich said. “That was the year catches were really unusual toward fish in the northern end of the lake.”
Fishing along the south shore and Rainy River late this fall was excellent, Heinrich said, which bodes well for winter fishing prospects.
“If I had to guess, when we get ice, I’m thinking the fishing on the south shore is going to be very good, just because of how good the fishing was this fall,” he said.
Lake of the Woods notes
• Anglers logged about 640,000 hours of fishing pressure this past summer on Lake of the Woods, Heinrich said, based on results from a summer creel survey. Bad weather in June, which traditionally is a busy month for fishing, likely kept anglers off the water. Anglers harvested about 180,000 pounds of walleyes and 58,000 pounds of saugers this summer, the survey showed.
• The DNR will launch a winter creel survey on Lake of the Woods as soon as the ice is safe, Heinrich said, probably sometime between Christmas and New Year’s. Another summer creel survey planned for 2017 has been canceled because of budget shortfalls.
• A Baudette fisherman made news in November when he reeled in a 32-inch walleye weighing more than 14 pounds on the Rainy River. Heinrich said Baudette fisheries crews sampled a 15-pound walleye last April during the annual spring electrofishing survey on the Rainy River near Birchdale, Minn. “That’s the biggest walleye I’ve seen in 25 years,” he said.