A closer look at perch: next up on the research platter?

Glenwood, Minn. — Mention yellow perch, and some may think of that pesky fish that bites off worm fragments meant for walleyes. Others will envision the jumbos dragged through the ice and destined for the frying pan. Still others will conjure images of bite-sized fish that help keep walleyes, northern pike, and other lake inhabitants fat and healthy.

DNR Fisheries officials often will think about a fish that’s vital to the ecosystems of many state lakes, and the fact that in many places, there just aren’t as many perch as there used to be.

That likelihood has gotten the attention of DNR researchers, who hope soon to narrow the focus of future research to determine what might be not only holding back yellow perch, but also potentially dragging them down.

Leading the way will be DNR research biologists  Jeff Reed, of Glenwood, and Bethany Bethke, of Duluth. Related research conducted by Bethke during the past couple of years pointed to a likely decline in perch numbers; in more than 900 lakes studied, perch numbers had dropped on average, from about 10 fish per gill net to around five fish per gill net during DNR surveys.

“When you see something going in half over a 25-year period, it’s something you want to look at,” Reed said.

Yellow perch, infrequent headline grabbers, are nonetheless central figures in many Minnesota lakes. 

“They have a wide ecological role in lakes,” Reed said. They’re predators, prey, and hold value to anglers, he said.

Examination of netting data yields some clues regarding why perch might be declining in some places. High water levels have created fertile breeding grounds for northern pike, and a corresponding increase in the pike population could be putting a bigger dent in the perch population, Reed said. Also, invasives – such as zebra and quagga mussels, and spiny water fleas, where they exist – could be reducing the foods available – like zooplankton – for very small perch.

One other factor could be in play, too. Reed, a fisheries researcher of more than two decades and currently co-coordinator of the “sentinel lakes” project, said longer growing seasons in lakes are helping species like bluegills, which compete with yellow perch.

In the recent past, he said, “It wasn’t uncommon to have total bluegill year-class failures across the northern part of the state.” More recently, such busts aren’t as frequent.

Bethke, who looked at a range of fish species and changes in survey results over a period from the 1970s to the present, said the finding regarding yellow perch could lead to “one or more field projects.”

The decline in some of the lakes where her research focused was “significant,” she said.

While other species were included in the finding of that research (see Joe Fellegy’s Page 26 story for more on that), it was actually yellow perch that led Bethke to conducting the research, she said. The topic came up at a “large lakes” meeting, she said.

“We had a suspicion … what’s going on?” she said.
 

Bethke adds yet another item to the list of possible culprits for perch decline: the loss of near-shore habitat, which could be lakeshore property owners removing woody debris or bulrush, or high water drowing out said bulrush.

Researchers have presented data to area fisheries supervisors to get their thoughts on the matter. Once the focus is narrowed, research proposals are presented to research supervisor within DNR Fisheries.

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