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Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

April 2003

Readers Write

Nice mice
City forests
Lots of CWD questions
On managing muskies

Nice Mice

© John C. Yost

Thanks for The Midnight Marauder, the December 2002 story about deer mice. When I was a schoolboy of about 10 or 11 in 1930, my brother Art and I had the task of re-setting the caps on shocks of bundled grain in the fields.

The standing ripe grain had been cut and bound with sisal twine into bundles tied by "the knotter" – an invention of a Mazomanie farm boy for whom an historical marker was erected along Highway 14 just before the Highway K turnoff on the way to our farm. The grain binder (pulled by four horses) cut the stalks close to the ground, pushed them together in a bunch about a foot in diameter, tied them and tossed them. The hired man picked up the bundles and shocked them. Eight bundles were shocked up against each other and a ninth was spread over the top to shed rain off the grain until the threshing machine came. Windstorms often blew the caps off some of the shocks, and one hot August day, Art and I were sent out to repair the storm damage.

Toward the end of the afternoon, I came to a shock where a field mouse had made a nest. She stayed close to her babies, which were just beginning to get fur and could walk around slowly. We easily caught the ma mouse and I stuck her in my pocket. We scooped up the nest with all four or five babies and calculated that we had an excuse to quit work for the day.

At home we had a little cage made of fly-screen and one side had a swinging door. We put the nest and babies in one corner and released ma mouse, who immediately rushed over to the nest, piled in among her babies and started to nurse them. We were amazed how tame she had quickly become.

We filled a fruit jar cover with water and provided some bits of bread. Ma mouse soon came to drink and nibble. The next day we found some sunflower seed. To my amazed pleasure, ma mouse crept right up to my hand, grabbed the seed, shucked it and gobbled it up. She never showed any inclination to bite us.

Within a few days, the babies were running around the cage, falling in and out of the tiny water tank and lining up for lunch as ma mouse laid down on her side. Her family endeared themselves to us – two usually bloodthirsty little boys – and we pondered their future. We decided we could not give them a secure or good life.

About a week later we carried the cage back to the very same shock and restored them to liberty. The threshing machine was a couple of weeks away and we knew by that time the mice would all be grown up enough to run away.

When my wife, Martha, I and two-year-old son Eric lived in a cottage near Chippewa Falls, we would hear deer mice (the "city" cousins) rolling acorns and hazelnuts across the linoleum floor in our living room while we tried to sleep in the adjacent bedroom. I never held it against them.

I remain fond of both Peromyscus families to this day.

Robert G. Lewis
Washington, DC

City Forests

I was delighted to see the articles in The forest where we live: a guide to caring for trees in the October 2002 issue. As a tree farmer in northern Wisconsin and an advocate for urban trees, I found the articles well done and easy to understand. Forestry management is so important to a healthy Wisconsin and its citizens. I applaud you for providing this kind of information for readers and hope to see more forest management related issues in the future.

Michael Gehrke, Director
Wisconsin Woodland Owners Association, Inc.

Lots of CWD Questions

I've been an avid reader of the magazine for many years and have always found it helpful and filled with good solid information. However the August 2002 article CWD update left some thought-provoking questions in my mind and I hope in the minds of most Wisconsin deer hunters.

I am concerned with the statement made regarding the DNR's monitoring of the state deer herd since 1999 for Chronic Wasting Disease and the testing of 1,000 deer in 72 of the 130 deer management units, indicating that other than deer monitored in the Dane and Iowa county areas, no cases of CWD or tuberculosis have been detected.

It is my understanding that this year approximately 500 deer from each deer management unit will be tested for signs of CWD or TB. This brings up two questions:

1. Can we eat the animals and what are our chances of getting any kind of disease that affects them? The jury is still out on this, but some recent findings are alarming.

2. Inasmuch as there is no practical way of testing a hunter's animal other than divesting it of its head, one can only visualize the tremendous turmoil that will exist at the registration stations when a hunter is asked to give up a 10-point buck's head. The results of testing will not be known for weeks, maybe months. In many warmer years, venison cannot be kept unprocessed or hung while someone awaits results from a laboratory. You can certainly bet that no antlers will ever be returned to any hunter abandoning the head of his trophy...

Certainly we need to be told more, we need to be told often and we need to be told by area papers, magazines and TV. This (CWD) needs more understanding than you have been willing to put out and I am certain that it will mean the loss of revenue in the form of licenses not purchased.

Dr. Armin C. Block

Dr. Block wrote us last August in the midst of the summer special shoots. Our agency practices remain to inform people as promptly as CWD test results are confirmed, to set up emergency response units at Dodgeville with accessible collection stations in the CWD Eradication Zone, to hold public meetings, to issue statements through newspapers and broadcast media, to seek help from landowners, to set up a system for issuing shooting permits, to set emergency practices for efficiently collecting deer samples and sharing results, to devise a way to preserve trophies, to encourage our ability to analyze deer for the presence of CWD in the state, and to explain as best we can the nature of the disease.

CWD testing started in 1999 when national trends showed CWD was moving eastward from Colorado and Wyoming where it has been endemic for decades. In 1999-2001, DNR's wildlife health team chose to sample deer at those registration stations where we believed CWD might first appear in Wisconsin – sites near large captive herds, sites in management units where we knew deer yarded, and sites in units where deer densities were higher. That testing was announced statewide each year, including in this magazine in October 2001.

The risk of a person contracting CWD or a prion-related disease from eating venison is very small given that: a.) To date, only 68 deer of more than 30,000 deer samples analyzed statewide have been found to carry CWD, b.) No researcher has documented prions in edible portions of deer, c.) No researcher has documented that CWD can be transmitted from deer or elk to people. Nevertheless, given recent history in explaining the risks of mad cow disease and other bovine spongiform encephalopathies, the State of Wisconsin is trying to give people the best information we can so they can make their own decisions about consuming venison. Our sampling strategy is designed to help people gauge the risks of CWD exposure in the areas where they hunt. We surely share your resolve and concerns about how CWD may affect hunting in the near future.

On Managing Muskies

© Terry Margenau

I have a couple of comments about the December 2002 article on managing muskies, Long live the kings. First, the article states that anglers are releasing 98 percent of the muskies they catch to grow bigger and fight another day. This may be true, but it insinuates anglers are "voluntarily" releasing 98 percent of the muskies. They are releasing them because some of the fish are not of legal length. I'd like to know the number of "legal" fish that are voluntarily released.

Second, the article states costs run to $70 per stocked fingerling that survives for 18 months in the wild. How much would it cost to raise fish to 18 months in the hatchery? I realize this would tie up hatchery ponds for two spawning seasons, but wouldn't this still be cheaper than $70 per fish?

Finally, you cite creel surveys as a measure of the harvest. I still have little faith in these surveys for providing accurate harvest projections and numbers. Let me say that I feel musky fishing in Wisconsin has never been better in terms of the numbers of fish caught, but in measuring the numbers of larger fish, we're still working at it. Progress will be hard given the small size of most of our lakes and increased fishing pressure from more anglers who are both knowledgeable and better equipped to catch muskies.

John Aschenbrenner

Fisheries biologist Tim Simonson responds: You are correct. The 98 percent release rate is for all fish, not just legal fish. We don't directly measure the release rate for legal fish because we don't ask anglers during creel surveys for the size of fish they released since we can't actually measure them. The creel surveys may or may not be "accurate" (meaning close to the true value for the harvest), but the surveys are "precise" (predictably repeatable from year to year), so we are comfortable using them to track trends. Harvests may well be higher than we estimate, but there is little doubt that the musky harvest has dropped considerably over the last 30 years. In relative terms, the actual harvest is 92 percent lower than it was in the late 1970s.

DNR fisheries researcher Terry Margenau conducted a mail survey of anglers that indicated 98 percent of the musky anglers and 90 percent of the general license holders "generally" release legal sized muskellunge. Clearly, the harvest numbers are reduced and catch-and-release fishing has been a major contributing factor. Further harvest reductions will result in population increases, but relatively smaller increases considering the size of our waters and the fishing pressure they receive. Higher size limits should also improve the size-structure on many of our musky waters.

To answer the hatchery question, the costs of raising fish increase exponentially as they get larger. They eat more and convert their food to muscle less efficiently. Hatchery Supervisor Al Kaas estimates it would cost $14 per fish to raise a musky to be a fall yearling not including the costs of tying up propagation ponds for two summers. At a survival rate of 20 percent, these muskies would still cost about $70 per survivor after one year at large. If survival were 40 percent, these muskies would only cost about $35 per survivor. However, we could only produce about 300 muskies per acre as opposed to the 8,000 fall fingerlings per acre that we now raise. Given space limitations, we would probably end up with about half as many survivors after considering mortality after stocking. The sheer numbers of fall fingerlings that we can produce, even given smaller survival rates end up contributing more adult fish to the population than we would get from raising a limited number of fall yearlings.