Top Suspects Cleared in Yellow Perch Decline
By John Karl
RACINE, Wis. (6/12/99) — The reasons for the 10-year decline in Lake Michigan’s yellow perch population are still a mystery, but the top three suspected causes have been ruled out in a series of experiments conducted by Fred Binkowski, senior scientist at the University of Wisconsin Great Lakes WATER Institute at Milwaukee.
Binkowski reported the results of his experiments in Racine today at a conference called "The Decline of Yellow Perch in Lake Michigan," sponsored by the SC Johnson Wax Fund. Binkowski’s research was funded by the University of Wisconsin Sea Grant Institute.
"Everyone was concerned about the early life stages," Binkowski said. "But we’ve found that there are no problems with the fertility of adult perch, with the hatching success of the eggs, or with survival of newly-hatched fish. The sex ratio of perch hatched under laboratory conditions is close to 50-50."
This means the low proportion of females observed in the lake is not due to genetic factors, Binkowski said.
"We’ve crossed genetics off the list of likely causes," Binkowski said. "But we’re keeping an open mind. We’re turning over every rock to find the true culprits."
In his UW Sea Grant study, Binkowski compared the early life stages of perch from Lake Michigan to those of Green Bay, Lake Ontario, and Lake Mendota in Madison. Fertility, hatching success, survival of newly-hatched fish, and sex ratios of perch in these other locations, which have not experienced the sharp declines observed in greater Lake Michigan, were comparable to those of Lake Michigan strain yellow perch.
In a cooperative effort with scientists around the lake supported by the Michigan and Illinois-Indiana Sea Grant programs, Binkowski is examining other factors that may be limiting perch "recruitment," or survival to adulthood. These include predation by alewives, shortage of food, and adverse weather effects, Binkowski said.
Fred Binkowski, Senior Scientist, Great Lakes WATER Institute, (414) 382-1700For More Information:
See also:
Anglers Play Vital Role in
Monitoring Advance of Exotic Species (9/2/99)
Yellow
Perch Update (12/98)
Lake Michigan Yellow Perch Remain Scarce
(12/18/98)
Major
Perch Research Effort Launched (03/28/98)
Perch
Research: Phase One Complete (10/6/97)
UW
Sea Grant Researchers Tackle Perch Problem (8/20/97)
Where
Have All the Yellow Perch Gone? (4/16/97)
Conceived in 1966, Sea Grant is a national network of 30 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.
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