Lake of the Woods: Annual fall population survey a September marathon
WARROAD, Minn. -- It's a gray Monday morning, and there's enough wind to put a chop on Lake of the Woods, which stretches toward the horizon in an imposing shade of steely-blue.
The chatter on the marine band radio hints the fishing might be better than the catching so far this chilly morning, but that won't be the case everywhere.
Not in this boat, at least.
Tom Heinrich is out here again, just as he's been every day for the past two weeks. Ditto for Nate Hodgins and Seth Herbst.
Windy days, calm days, in-between days, they've been on the water.
They might not have seen all of the 344,000 acres that make up the Minnesota side of the big lake, this trio, but they've seen enough to get a pretty good idea of what's going on below the surface.
And what they see, ultimately, has a direct impact on marine band chatter such as the conversation unfolding from an unseen portion of the lake somewhere beyond the horizon.
In the very simplest of terms, it's all about the fish.
Large lake specialist for the Department of Natural Resources in Baudette, Minn., Heinrich oversees the DNR's annual fall population survey on Lake of the Woods. A veteran of the annual effort, Heinrich steers the DNR's 25-foot Boston Whaler toward four nets they've set the previous day between Warroad and Willow Creek.
While Heinrich keeps the boat on course, Hodgins and Herbst pull the nets, carefully lifting the gear and its fishy contents into plastic crates. They'll remove, sort and analyze the catch later back on shore.
Unlike Heinrich, Hodgins and Herbst are newcomers to the survey. Hodgins is a fisheries specialist for the DNR's Baudette office and has been on the job about two weeks. A fisheries technician, Herbst has been here since June.
So far, they say, the wind and big waves that sometimes go with the territory on Lake of the Woods haven't been too much problem.
Not that they'll admit, at least.
As part of the fall survey, Heinrich says, the DNR crew sets four nets at 13 near-shore stations and three offshore sites along the Minnesota portion of the lake from Warroad to the Northwest Angle.
The nets are 250 feet long and consist of 50-foot panels of different-sized mesh ranging from ¾ inches to 2 inches. The nets are designed to capture walleyes up to about 22 inches long.
They set the near-shore nets in 6, 10, 15 and 20 feet of water, Heinrich says, the offshore sites in about 30 feet of water. Thanks to GPS technology, they can sample the exact same locations every year.
For consistency, they also set the nets facing the same direction.
Part of the DNR's large lake program that targets Minnesota's 10 biggest, most prolific walleye lakes, the fall survey has been an annual event on Lake of the Woods since 1981, Heinrich said. The DNR also conducted three surveys in 1968, 1969 and 1970.
"Back then, it was a combination creel survey, commercial fishing and population assessment," he said. "There were some issues with fish populations, so they did the survey to see what was going on."
There's a lot of water to cover, and the 16-day marathon gets rolling every year beginning the Tuesday after Labor Day. They're on the water every day the weather allows, including weekends, in a race against the clock -- and Mother Nature, who can be a temperamental sort this time of year.
"It's just more efficient," Heinrich said. "It's kind of a grueling stretch, but in the long run, it's probably easier on us."
They set the nets one day and pull them the next. This year hasn't been bad, Heinrich says, but there've been days, over the years, when big waves made the job a challenge. And if they've set nets, he says, they always try to return the next day.
Otherwise, he says, they can't use the data they collect from that particular site and have to start over.
Everyone knows their job, and the morning's work goes quickly. With Heinrich at the helm, Hodgins and Herbst pull the four nets and set four new ones at different sites farther down the shore in a couple of hours.
The slow work begins back on shore, where the crew uses hand picks to remove the fish from the nets. They sort the catch by mesh size. This, too, helps maintain survey consistency.
The catch reveals a little bit of everything: walleyes, saugers, northern pike, white suckers, tullibee, perch, a single crappie, crayfish galore and, in one net, a humongous quillback carpsucker -- a native rough fish that resembles a cross between a sucker and an angel fish.
The quillback tips the scales at more than 7 pounds, which would have broken the state record of 6 pounds, 14.4 ounces set in 1991.
Once the sorting's complete, Heinrich and Hodgins head for the fish-cleaning house. Hodgins arranges the fish on a cleaning table and cuts them open to determine their gender. He measures and weighs each fish, calling out the tallies in millimeters and grams while Heinrich enters the data on a touch-screen computer.
For the past three years, the Baudette fisheries office has been a pilot site for the touch-screen, which allows Heinrich to enter data right on site and send it to a database at DNR headquarters in St. Paul. Heinrich says he backs up the data to St. Paul nightly.
That saves him about two weeks of number crunching, Heinrich says. Before, he'd have to write down the information on each fish and enter it into a computer later back in the office.
They also age a subsample of fish based on length. That takes longer, because it requires counting growth rings in certain bones of the fish. Heinrich says he ages about 1,000 fish out of the survey and typically has results by Christmas.
Based on preliminary results, Heinrich says, saugers are the big news in this year's survey. That's good news for the area's ice fishing industry, where saugers are a staple.
The first day of the survey, for example, they sampled 250 saugers in the first four nets, Heinrich says. That works out to more than 60 saugers per lift.
Overall, Heinrich said, the sauger catch was 26 per lift at the near-shore sites and 52 per lift offshore, which is significantly higher than the long-term catch of 11.8 from 1981 to 2007. He attributes this year's sauger catch to strong hatches in 2005, 2006 and 2007. The 2008 hatch also appears strong, he says.
"There's just sauger everywhere," he said.
By comparison, he says, the highest walleye catch they ever tallied in a survey was about 22 per lift, and the long-term average since 1981 is about 15 walleyes per lift.
Preliminary findings show walleyes are down this year. When all the numbers are crunched, Heinrich says, this year's survey likely will produce about 10 walleyes per lift.
That's below the long-term average, but not necessarily cause for concern. For several consecutive years from 1995 through 1999, walleyes pulled off strong hatches. The trend more recently, Heinrich says, is strong hatches in odd years and weaker hatches in even years.
Time will tell if this year's decline means anything. That's what makes the September survey such an important tool for managing the lake, Heinrich says.
"When you get those long data trends, it's really nice," he said. "You can see when things start to fall out of the range of normal variability."
Dokken reports on outdoors. Reach him at (701) 780-1148; (800) 477-6572, ext. 148; or send e-mail to email@example.com.