How to Hold a Musky (and other info)

Tuesday, February 20, 2007

Balance In Muskellunge Populations

Dave NeuswangerPublished January 26, 2007

I supervise fishery management in the six-county Upper Chippewa Basin for the Wisconsin DNR. One of the fine senior biologists on my team is Mr. Thomas (Skip) Sommerfeldt. Skip has the daunting challenge of managing the fisheries of hundreds of small lakes throughout the Chequamegon-Nicolet National Forest, under contract with the U.S. Forest Service. Minnesota anglers and other lake users should know that Skip's management evaluations and ideas on the impact of muskellunge on other fish in small Wisconsin lakes have not been published in any peer-reviewed scientific journal or agency-endorsed report. But for almost 20 years he has sampled fish populations in small northern Wisconsin lakes; and he has observed that lakes with exceedingly high numbers of adult muskellunge often have problems with other species that may be related to the overabundance of muskies. Conversely, lakes with too few large predators have problems too. Generally speaking, we seek a state of balance.

Our colleagues with the Minnesota Department of Natural Resources are in the best position to judge exactly where that 'state of balance' exists in the waters they manage. Water chemistry is different in Minnesota and Wisconsin. Many Minnesota lakes are more productive than Wisconsin lakes in many respects, and therefore can accommodate a greater number and variety of fish. Minnesota DNR and Wisconsin DNR biologists focus on different things to measure, too. For example, Minnesota DNR does a good job obtaining information about prey (food fish) populations with their standardized gill net sampling program; whereas Wisconsin DNR knows very little about the type and abundance of prey species (yellow perch, ciscoes, white suckers, etc.) in its waters. On the other hand, Wisconsin DNR does a good job estimating the actual density (number per acre) of adult muskellunge in Wisconsin waters, something Minnesota DNR biologists have not done routinely. So Minnesota knows more about the prey, and Wisconsin knows more about the predators. What we both need is better information about entire aquatic ecosystems before any firm conclusions can be reached about the role and impact of muskellunge. Staffing is an obvious limitation to obtaining all the information we need.

Skip and I feel that some of the statements in his unpublished management reports and draft manuscripts have been taken out of context and used to promote the agenda of a few folks in Minnesota who have expressed the unfounded fear that any number of muskellunge in a lake are bad for the rest of the fish community. That is a misuse of Skip's data and a misrepresentation of his opinions. Skip may have evidence of adverse impacts of extremely high numbers of adult muskellunge (over 1 adult per acre) in several lakes where he has actually estimated the density of adult fish. But nobody can legitimately assume that stocked muskellunge would become a problem in any given lake in Minnesota, especially if there is no information on the number of adult fish there. It is quite possible that some of the more productive lakes in Minnesota could support more adult muskies than most lakes in Wisconsin, simply because those Minnesota lakes probably produce more prey. Other fish populations (northern pike, yellow perch, etc.) might even benefit from the introduction of muskellunge into certain Minnesota waters.My recommendation to anyone concerned about stocking muskellunge in their favorite Minnesota lake is to contact the local Minnesota DNR biologist and ask for his or her professional opinion on the number of muskies that lake could support given the level of productivity and prey availability. Trust in their professional judgment. They know their home waters better than we do.

Please do not use concerns expressed under different circumstances in Wisconsin to force your biologists to abide by strategies that may not work in Minnesota. You have good biologists there. They deserve your respect and support.I have no interest in becoming involved in this controversy. But I feel this letter is a necessary attempt to prevent a small group of Minnesota residents from misusing Wisconsin DNR data by pulling it out of context and using it to support an agenda that few, if any, professional fishery biologists in North America would support.David J. NeuswangerFisheries Team Leader Upper Chippewa BasinWisconsin DNR, Hayward715-634-9658x3521


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