Wisconsin research featured in national fisheries journal
MADISON – Optimal stocking rates for walleye, interactions between walleye and other game fish, and techniques to help conduct fisheries surveys and set fishing regulations are among the Wisconsin research featured in a national journal and being used in the state’s fisheries program.
Department of Natural Resources fish biologists served as the principal or contributing investigators in five of the 40 technical articles appearing in the current volume of the North American Journal of Fisheries Management (Exit DNR), and a sixth study detailed in the journal was funded by the department.
“We base our decisions on the best available science, and when our staff is at the leading edge of science, anglers can be pretty comfortable that Wisconsin has the best management programs possible,” says Mike Staggs, Wisconsin’s fisheries director.
Abstracts of the research are available online in the Journal’s current issue (Exit DNR).
In brief, the research found the following:
 | Stocking small fingerling walleye at 35 fish per acre produced the maximum number of walleyes surviving past their first year. Higher stocking rates resulted in fewer surviving fish, the authors concluded. “One of the key factors in survival through that first winter is condition, so if there is not enough food to go around, very few make it past that few bottleneck,” said DNR fisheries biologist Dr. Andrew Fayram, the study’s primary author. DNR fisheries colleagues Dr. Nancy Nate and University of Wisconsin-Stevens Point professor Dr. Michael J. Hansen were contributing authors. The study, which analyzed stocking data and fall survival surveys for walleye on 39 lakes over a 14-year-time period, also found that fish managers had, through their professional judgment and shared experience, been stocking reasonably close to that optimal number when they arrived at the previous recommended stocking rate of 50 fish per acre. DNR has decreased its walleye stocking to the 35 fish per acre rate statewide, but has given fish managers the opportunity to make the case for a different rate on a particular lake if it warrants it. “It’s a win-win for everybody,” Fayram says. “We’re getting more fish and we’re saving money.” |
| Largemouth bass was the only game fish species that strongly interacted with walleye by preying upon walleye; that interaction can limit the survival of stocked walleyes in the same lake, and walleye stocking may increase largemouth bass populations. Northern pike, muskellunge and smallmouth bass did not have strong interactions. “That’s not to say the other species did not have interactions, but it’s just not nearly as strong as with the largemouth bass,” says Fayram, who again teamed up with Michael Hansen on the study and with Timothy J. Ehlinger, with the University of Wisconsin-Milwaukee Department of Biological Sciences. The research involved using DNR fish population survey results, information demonstrating competition or predation, and pumped the stomachs of game fish on a northern lake to see what species they ate. |
| Because Wisconsin lakes differ in size and inherent productivity, fish growth potential varies among lakes. Working with researchers at Michigan State University, Dr. Nancy Nate completed research that will allow fish managers to classify lakes based on fish growth potential. Using the fish growth index she identified, DNR could classify lakes for a certain regulation and species rather than regulating angling for one lake at a time. |
| Fish body condition or the relative plumpness of individual fish is often used by fisheries biologists as one tool to help fish managers diagnose stunting of fish and prescribe management actions such as reduced stocking or increased harvest limits to bring fish densities in line with available food. Nate, working with Hansen as primary author, examined walleye data from 202 Wisconsin lakes to develop a method for assuring that the body condition index, which has long been a national standard, better reflects fish body condition in Wisconsin. The results of the study, along with other survey information, may be used by Wisconsin fisheries managers to determine the best management strategies for walleye populations. |
| Research has identified the gear and method most effective in collecting three-month-old lake sturgeon in shallow water systems, an important advance as DNR seeks to restore lake sturgeon populations in a number of waters and needs an effective way of gauging whether stocking efforts are working. Without such research, conducted by a team of researchers from Purdue University, the U.S. Fish and Wildlife Service, and Tom Meronek, a DNR fish biologist based in Wausau, accurately assessing stocking efforts would require waiting years until the fish is big enough to be caught during other surveys using methods targeting the older fish. |
FOR MORE INFORMATION CONTACT: Andrew Fayram (608) 266-5250; Nancy Nate (608) 267-9665; Tom Meronek (715) 359-7582; Michael J. Hansen (715) 346-3420
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