by Sarah Coomber
MADISON, Wis. (Oct. 6, 1997) -- Young Lake Michigan yellow perch are taking twice as long as three other strains to advance from one food level to the next, according to UW Sea Grant fisheries scientist Fred Binkowski.
"It is probably related to the size of the mouth," Binkowski said. "But it also could be related to behavior characteristics."
His observations are the result of 42 days he and his colleagues spent last summer observing tanks filled with different strains of young yellow perch. They compared Lake Michigan perch, caught off the Milwaukee shore, with perch from presumed healthy populations in Green Bay, Lake Ontario and Lake Mendota.
The study’s goal is to find what is ailing the Lake Michigan population of yellow perch. This UW Sea Grant-funded research -- which is taking place at the UW System/UW-Milwaukee Great Lakes Wisconsin Aquatic Technology Environmental Research (WATER) Institute (formerly known as UW-Milwaukee Center for Great Lakes Studies) -- will result in early life history profiles of the different strains and, possibly, insight into the causes of Lake Michigan’s perch population crash. The Lake Michigan population has had seven years of weak year classes, and the states surrounding the lake have banned commercial perch fishing and restricted sport fishing.
Now researchers are examining more than 10,000 preserved perch specimens from the 42-day early life history study. They are recording and comparing fertility rates, estimated hatching success and sac fry survival, swim bladder inflation, food acceptance, daily mortality and growth among the different strains.
About 4,800 perch remain in tanks and are entering the second phase of the study. For the next three years, WATER Institute staff will document sex ratios, growth rates, behaviors and daily mortality rates.
Meanwhile, Wisconsin Department of Natural Resources fish technician Matt Coffaro has been looking for yellow perch in Lake Michigan. He said that in the 1980s, it was possible to capture as many as a couple thousand young perch with a single haul of a seine net. But after 58 hauls this year, they have found only two.
"If there was a tremendous number of fish out there, we would have caught more than two of them," Coffaro said.
More Wisconsin Sea Grant yellow perch stories:
UW Sea Grant Researchers Tackle Perch Problem (Aug. 20, 1997)
Where Have All the Yellow Perch Gone? (Jan. 17, 1997)
Precarious Perch -- Earthwatch Radio script (Jan. 15, 1997)
Created in 1966, Sea Grant is a national network of 29 university-based programs of research, outreach and education dedicated to the protection and sustainable use of the United States' coastal, ocean and Great Lakes resources. The National Sea Grant Network is a partnership of participating coastal states, private industry and the National Sea Grant College Program , National Oceanic & Atmospheric Administration , U.S. Department of Commerce . The University of Wisconsin Sea Grant College Program is administered by the Sea Grant Institute on the UW-Madison campus in Madison, Wisconsin.
7 October 1997 Coomber
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