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Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

October 2003

Readers Write

House Designs
The Mystery of Missing Perch
A Fan of the Old Tonics

House Designs

We visited the Spring Green Art Fair this July and met wildlife photographer Stephen Lang, whose photos have appeared in your pages. He gave us a copy of the magazine with the bluebird feature (Thinking out of the box April 2001). Are the plans for building bluebird boxes still available?

Jeanne Fuhs

Absolutely. Plans for bluebird houses incorporating newer designs for shallower boxes were printed in our August 2001 issue. Copies of the plan are still available through our offices. Enclose a stamped self-addressed envelope and forward those requests to: Bluebird Plans, Wisconsin Natural Resources magazine – CE/6, P.O. Box 7921, Madison, WI 53707.

The Mystery of Missing Perch

I read with great interest the explanations of the declining yellow perch populations in Lake Michigan (Adrift on the sea of life June 2003). Apparently all the perch research is biological and neither predators nor economic effects of lower perch populations have been addressed.

I believe predator stocking of trout, walleye and muskellunge in Lake Michigan are contributing factors to low perch populations. Predators are opportunistic feeders. After alewife populations went down, predators changed to smelt and when smelt populations went down, they changed to perch.

Obviously the small economic impact of no perch for the few commercial and pleasure fishermen in Lake Michigan is a back burner issue and is given lip service in 20 years of study. Perch contribute few tax dollars while trout, walleye and muskellunge bring in millions.

Hopefully all biological, predator and economic issues will be addressed and possibly save the Poor Man's Pleasure of perch fishing in Lake Michigan.

Thomas Heindel

Southern Lake Michigan Fisheries Team Leader Brad Eggold and Lake Michigan Fisheries Biologist Bill Horns responded:

"We certainly investigated these issues as part of trying to understand and explain the decline of the Lake Michigan perch population. We don't believe game fish predation of perch is a major factor because we have examined what game fish are eating. Bloater chubs made up 80 percent of the biomass available to trout and salmon but their stomach contents by weight were almost exclusively alewife. These fish are easier to swallow because they don't have the bony structure of perch and they live in different parts of the habitat where game fish are more prevalent. Other fish like bass, walleye and pike are found in the lake in relatively small numbers and in harbors and bays. Perch are generally out in the lake and don't come into contact with many game fish.

"Of course the diets of salmon predators vary seasonally, and yellow perch do show up in their stomachs, especially in spring. One circumstantial argument against the hypothesis that salmon prey heavily on perch is that yellow perch remained abundant and reproduced well through the 1980s despite high levels of salmon and trout stocking.

"Biologists in Wisconsin and elsewhere believe that the problem for yellow perch has been in early mortality of offspring, so, if predation is the problem, we need to identify predators that target yellow perch during their first summer of life. For the most part salmon, and especially lake trout, occupy deeper colder water than young yellow perch during the summer. Walleye and musky are not stocked in southern Lake Michigan, so they are not the problem there. One predator that has received a fair amount of attention is the alewife, which can eat very young yellow perch and is often present when the yellow perch are hatching.

"Combined with transport issues, alewives may be more of a factor, but environmental factors may have proven to be more important. Prevailing winds before late June were all out of the east and northeast. The situation may be different in Green Bay, where white perch may be more of a factor with other predators, but that is a tough cause and effect to pin down. There is tremendous competition for food for one species over another. Green Bay is a more complicated system and the potential for interaction with other species, stocked and unstocked, are greater."

A Fan of the Old Tonics

Thank you for information on witch hazel (A charming fall bloomer October 1997). I've used it for more than 50 years to ease swelling and help recover from bruising such as sprained ankles. I also use it as a facial tonic and think it is much better than the expensive cosmetic ones. I have used witch hazel all these years and really had no idea what it was. It was just one of those things passed on by Mother in the 1940s having been passed on by her mother in the 1920s. Witch hazel must be OK because it is still in use and I see no ill effects. The story on your web page was nice and clear, not too technical. Thanks.

Margaret Hawkins
United Kingdom