A perilous situation: Lake Michigan perch population continues its decline

By Paul Smith

Friday, April 9, 2004 12:00 AM CDT

The Lake Michigan yellow perch population, already decimated by a decade-long decline, has dwindled further and made any chance for a recovery of the popular sport fish extremely remote.

As it has for the last three years, the future of the perch hinges on the reproductive success of a single year class of fish, making any comeback more tenuous and leading to increased frustration on the part of anglers, fisheries managers and biologists.

According to data recently released by the Department of Natural Resources from its annual Graded Mesh Assessment (GMA), the 1998 year class of perch dominates the fishery but may be too small to pull the population out of its tailspin.

"We are seeing a small fraction of the fish out there today than what we used to see," said Brad Eggold, supervisor of the DNR's Southern Lake Michigan Work Unit. "And, unfortunately that's also the case with all the other agencies looking at Lake Michigan perch."

The 2003-04 GMA produced the fewest fish in the history of the test, according to a DNR status report.

A report from a researcher at Michigan State University estimated perch have declined in the Wisconsin waters of Lake Michigan from 25 million in 1986 to 1 million in 2002. In the waters of Green Bay, the DNR estimates perch have declined by 90 percent in recent years.

Scientists have yet to provide a definitive explanation for the perch crash. Many of the same theories that have been discussed for the last 10 years are being considered today, including nutritional problems caused by lack of food, primarily because of the presence of zebra mussels, as well as a predation on young perch by alewives and other fish.

Most biologists believe no single factor is responsible for the decline and continue to study synergistic effects.

The Yellow Perch Task Group, a multi-state, multi-agency work group that is investigating the perch decline, continues to study the issue.

"I fish with a lot of guys locally and we're all frustrated," said Ed Bloom of Racine. "We've been waiting for answers for 10 years now, and nothing."

Compounding his frustration, Bloom said, was the "unlevel playing field" in Lake Michigan in which Wisconsin anglers have a five fish per day limit on perch while just a few miles south, anglers in Illinois waters of Lake Michigan can keep 15 perch per day.

A group called Wisconsin's Lake Michigan Yellow Perch Conservation Group is calling for perch stocking in Lake Michigan. According to state records, the DNR stocked perch in Lake Michigan in 1978, 1981 and 1984. One stocking was in Kenosha, 10 others were in Milwaukee. A total of 200,000 fry, 80,400 fingerling, 49,780 yearling and 54,560 adult fish were stocked during that time.

Coincidence or not, the perch population rebounded in the mid-1980s, and the group's chairman, Carlton Alt of Milwaukee, would like the DNR to seriously consider stocking as a management option. Fred Binkowski, a researcher with the WATER Institute in Milwaukee, estimates it costs $0.16 to raise a single 1-2 inch perch and $0.30 to raise a 4-inch perch.

Alt has petitioned for a hearing before the Natural Resources Board and may get one during the May meeting. Extremely poor recruitment, or survival of young fish, has been noted by DNR biologists since the early 1990s. Last summer only six young-of-the-year perch were found in testing from Kenosha to Sheboygan. The same test would find hundreds of young perch in a single seine haul along the Racine shoreline in the late 1980s.

To help protect the shrinking population, the commercial fishery was closed in 1996 and stringent sport fishing regulations have been imposed. The daily bag limit is five fish per angler, and to help provide protection to adult fish before and during their typical spawning period, the sport fishing season for yellow perch on Lake Michigan is closed from May 1 through June 15.

DNR biologists use a variety of tests each year to monitor the lake's perch population, including the GMA, spawning and young-of-the-year assessments.

The GMA provides the best overall look at the health of the population, according to DNR fisheries biologists, because the fish are well mixed in terms of age and sex at this time of year. The test is conducted in December and January by setting out gill nets with graduated mesh sizes, ranging from 1 to 3 inches in �-inch increments. The nets are set in water east of Milwaukee.

DNR crews this year did a total of five lifts in "good territory," Eggold said. This year's results paint what is arguably the bleakest picture of the perch population since the testing began. The 1998 year class, now six years old, is the backbone of the population, with other year classes virtually nonexistent.

And the 1998 year class, with a catch per effort of 27 fish per 1000 feet per night, is extremely small in historical terms. To put it in perspective, in 1989, a time of relative perch abundance in Lake Michigan, there were 1,880 age 6 fish caught in the same test.

As expected, the 1998 year class has dwindled over time, yielding 323, 243, 118, 33 and now 27 fish in the GMA in the years between 2000 and 2004.

Typical of a low density population, the perch that remain in the lake are showing fast growth rates. Many of the perch from the 1998 year class exceed 12 inches in length, Eggold said. The GMA showed the perch are now at a 60 to 40 ratio of male to female.

The sport catch in the Wisconsin waters of Lake Michigan has declined from 134,000 perch in 2001, to 98,000 in 2002 to 89,000 in 2003, according to DNR creel surveys. Of the perch caught by sport anglers in 2003, 92 percent were from the 1998 year class.

For its part, DNR fisheries managers are staying the course and expect no changes in bag limits or season closures. They will conduct dives on spawning reefs this year to observe and count perch egg masses, as well as look for signs of a new year class in the late summer young-of-the-year assessment.

"The lake has changed big time," said Pradeep Hirethota, DNR fisheries biologist. "We have seen more change in the last 15 years than anyone would have predicted. The one thing that is clear is the need to protect the remaining fish to give them a chance to pull off a decent year class."

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