In his cramped basement office, Don Pereira stares at a computer screen covered with numerals and obscure mathematical symbols. Buried in these complex equations is information that could help improve walleye fishing on Lake Vermilion, Cass or any of Minnesota's other major walleye waters.
Pereira, a DNR fisheries research scientist, must find that information and make sense of it. He and the DNR's other 22 fisheries research scientists spend their days figuring out how to make fish management more effective and more efficient. They're like guides who assist fisheries managers through the obstacles of scientific unknowns.
Without research, managing the state's fisheries would be like jogging with your eyes closed: Eventually you might get where you want to do, but not without a lot of unnecessary bumps and bruises along the way.
Researchers conduct experiments that answer specific questions posed by managers and anglers, such as:
-- Why aren't there more big bluegills in Minnesota lakes?
-- Where do muskies spawn?
-- How does removing lake vegetation affect fish populations?
-- How would various regulation changes alter a fish population?
Fisheries researchers' work is closely related to that done by corporate research scientists. Companies rely on research to produce the most effective products for the lowest possible cost. For example, product and marketing research are responsible for graphite fishing rods, depth finders and hundreds of other items
available to make fishing easier and more productive.
"No company can be competitive without an effective R and D department," Pereira said. "The same holds true in the fisheries management business."
Muskie anglers are one group reaping the benefits of fisheries research, said Jack Wingate, DNR Fisheries Research Program supervisor. According to Wingate, Minnesota muskie anglers now have a far greater chance of catching a trophy-sized muskie than before the DNR switched to stocking a larger-growing genetic strain in the mid-1980s.
"The muskie is a classic example of the role of applied research to improve fishing opportunities," Wingate said. "Here we had all the pieces-studies of spawning habitat, fish movement, growth, genetics-that we put together to find the best strain to stock and the best lakes to stock them in."
In the late 1970s, Bob Strand began studying various strains of muskies used for stocking. The recently retired northwest regional fisheries supervisor learned that the Leech Lake-strain of muskie survived better and grew larger than other strains.
Previously, Strand had learned from studies that muskies do best in large lakes that contain relatively few northern pike, lots of forage fish such as tullibees (ciscos), and suitable spawning habitat. In the 1980s, Strand used all of this information to
direct new stockings of Leech Lake-strain muskies to waters where the fish had the best chance of thriving. As a result, big muskies prowl more lakes than ever.
Want bigger walleyes?
In a given year, the DNR's fisheries research scientists work on roughly 20 to 25 projects throughout the state. Pereira and researcher Melissa Drake most recently have been analyzing information related to Lake Vermilion's slow-growing
"Vermilion is a major walleye producer, but the average length of harvested walleyes is only about 14 inches," said Joe Geis, Ely area fisheries supervisor.
Geis said members of the Sportsman's Club of Lake Vermilion and the local resort association read reports of experimental regulations producing a walleye boom on Rainy Lake, 50 miles to the north.
"They came to us last year and asked if such a regulation could help Vermilion's walleyes," he said.
A truism of fishing regulations is: no pain, no gain. If anglers don't release fish they'd prefer to keep, then the fish population won't improve.
But how much pain is required to boost the size or number of fish that anglers catch? And how much gain will result? Geis turned to Pereira and Drake for answers.
Researchers examine a range of factors organized in three main categories:
-- Year class strength. This is the number of new walleyes born each year. Researchers compare the relative strength of various year classes of game fish and forage fish from one year to the next.
-- Rate of growth. This is how fast fish grow from year to year or from lake to lake. For example, walleyes grow quickly in relatively warm, fertile waters of Lake Winnibigoshish but more slowly in the less fertile waters of Lake Vermilion and other Canadian Shield lakes.
-- Rate of death: Fish either die naturally or are killed by anglers. How quickly they leave the population is an essential element of the equations research scientists analyze.
Fisheries managers regularly gather information about fish populations in spring and fall surveys. On Vermilion, Duane Williams, the DNR's large-lake specialist there, uses gill nets, trawls, electrofishing gear, and shoreline seining to sample walleye and forage fish year classes. This tells him how well particular year classes are faring. Williams also tallies species abundance, size, and health, a range of ecological conditions and the results of angler harvest.
Last winter, Pereira and Drake took this mountain of information to their St. Paul office, entered it into a computer and analyzed the data to come up with regulation scenarios for Vermilion. In April, they returned to Ely and presented their results to members of the sportsman's club and resort association.
"We explained to the group that because only 1 percent of Vermilion's walleye harvest is in the 17- to 25-inch range, that a regulation like Rainy's wouldn't do them any good," Drake said.
Yet most of the walleyes anglers now catch on Vermilion now are under 15 inches. "So that regulation would mean anglers giving up a huge share of their walleye harvest for a few years," Pereira explains.
Moreover, because Vermilion walleyes grow slowly and have high mortality, computer modeling showed the regulation would boost numbers of 15-plus-inch walleyes only 25 to 35 percent. And even then, Drake explains, it could be 20 years before she could tell whether the increase was due to the 15-inch minimum size limit or to natural factors.
"That's because you could get a big year class and then for a few years everyone is catching all those fish," she said. "It takes a few generations of fish moving through the lake's walleye population before you can determine what's causing what."
Sensing that the proposed plan's pain would far outweigh the possible gain, the club and association members decided not to pursue the 15-inch minimum regulation on Vermilion.
Not always welcome
When fisheries researchers analyze information and suggest how a fishery can be improved, they don't always get a good reception from anglers. Recent analysis of information from Lake Winnibigoshish showed that anglers there were overharvesting perch. The regulation with the best chance of restoring Winni's
perch population, Pereira told local anglers and resort owners, was to lower the possession limit from 100 to 25 or 30. "That wasn't well accepted," he said.
What happens when researchers report bad news?
"Our job is to crunch the management data and then help present the information to the public," Pereira said. "After that it's up to anglers and fisheries managers to figure out which option would be appropriate."
Brainerd Dispatch ©2013. All Rights Reserved.