September 29, 2020
By Cory Schmidt
Poor perch. Forever, they’ve been the subject of nature’s merciless cycle—populations surging forward followed by precipitous declines. The perch’s plight has also been one of deliciousness, their fillets and flesh providing a yum-factor off the charts. For those gregarious tiger-striped denizens of northern freshwaters, survival is a double-edged sword.
When perch first hatch and grow to a few inches long, they’re quickly hunted by cannibals of their own kind. At around three inches or more, walleyes and pike pluck them up like M&Ms. And then, having finally escaped the fangs of larger fish and grown to about 8 or 9 inches, anglers hound and harvest them in assembly-line numbers. Safe to say, the concepts of catch-and-release and selective harvest have yet to trickle down to these vital fish.
Perch are further subjected to the insatiability of invasive species. Before switching to a diet of larger invertebrates and baitfish, baby perch rely on zooplankton during their first year of free-swimming. Evidence is mounting that invasive mussels rob baby perch of key sustenance by filtering millions of gallons of freshwater, strip-mining the phytoplankton that forms the foundation of food webs and serves the dietary needs of zooplankton. No phytoplankton, no zooplankton. And then, no two-year-old perch, either, and eventually, very skinny pike and walleyes, too.
Great Lakes Canaries
On the front lines of the North American perch scene, Lake Michigan populations have been studied for decades. It was sometime around 1986 when invasive zebra mussels were believed to have been released by transatlantic freighters arriving from Europe jettisoning ballast water, releasing aquatic havoc that quickly spread in the Great Lakes and beyond. By 1988, research by the Wisconsin Department of Natural Resources and other state agencies began to reveal a continuing trend toward declining perch numbers.
In 1997, Lake Michigan research divers searched for perch nests for nearly 32 hours, discovering just 9 egg masses. The following year, the divers failed to find a single egg mass during a nearly 13-hour search. A slight uptick occurred between 2001 and 2007, as females from a solid 1998 year-class matured and reproduced. In 2017 and 2018, divers found 4 egg masses over an 11,000-square-meter search area and 1 egg mass across 13,376 square meters, respectively.
Following a similar pattern, Minnesota DNR biologists have recently observed a startling trend on the state’s inland lakes. Research biologists Beth Holbrook and Bethany Bethke analyzed data collected from 1970 to 2013 and found that average yellow perch catch rates had declined in both gill nets and trap nets, statewide.
When I recently spoke with Holbrook and Bethke, the two scientists admitted they weren’t yet certain if overall perch abundance was declining, or if size structure was shifting toward smaller fish. “Our pilot work has shown that perch in some lakes mature so early and at such a small size that they could potentially live out their entire life cycle without being detected by standard DNR sampling (netting) gear,” Holbrook says.
Moreover, due to a surprising lack of research on perch, little is currently known about the life history and feeding and spawning habits of these once-ubiquitous, under-the-radar species. To get a clearer picture of population trends and other habits of yellow perch, Holbrook and Bethke have initiated a multi-year statewide study involving 24 regional Minnesota DNR offices and dozens of lakes where experimental sampling methods such as shallow fall electrofishing and fine-mesh gill nets will be utilized. They’ll further be identifying fish ages using otoliths, as well as sex and age of maturity of individual perch.
Initial findings suggest that males reached sexual maturity at age-1 in 14 of the 20 study lakes. The smallest mature fish was a 2-inch male from Green Lake near Spicer, Minnesota. Bethke notes that most of the perch run 5 to 6 years old, but cites evidence of perch well over 10 years old, particularly in remote far-northern lakes. A 17-year-old fish was the oldest they sampled. The results also showed proportionately more females than males in every length group, but this is likely a result of smaller males eluding gill-net capture, the researchers say. Also posited by biologists is the possibility perch have adapted to shifting populations by maturing at earlier ages. When large, mature members of pike and bluegills vanish from populations, both species have been shown to adapt by maturing at earlier ages.
Additional research has shown that in summer, females tended to use deeper water than males. Another study showed than smaller male perch tended to use offshore locations in fall, while larger females roamed shallower water. Bethke also reports a pattern of proportionately more female yellow perch captured with fall electrofishing in near-shore locations, but says that most of the lakes surveyed lack perch over 8 inches. A bit later, I outline a solid late-summer, early-fall pattern for big perch.
While we await the results of Holbrook and Bethke’s perch research within the next few years, it’s insightful to examine the observations of anglers, too. I’ve long thought that an analysis of a fish population not only must include research from biologists, but also benefits greatly by the observations of guides who work the waters in question every day and closely follow what’s happening in the environment.
Beyond the aforementioned perch problems, two longtime guide friends, Brian Brosdahl and Tony Roach, have identified another reason for the perceived declines in populations. First, however, Brosdahl outlines ideal jumbo perch conditions: “Jumbo perch don’t happen everywhere,” he says. “Big water certainly offers a lot of what large perch require. But even on smaller lakes, perch thrive best across acres of grazing land—shallow hard flats with chara (sandgrass) and a wealth of invertebrates—bloodworms, scuds, and crayfish are key. Lakes that also have expansive deeper flats with soft bottoms add grazing territory and even more food sources to the big perch equation.
“On Lake Winnibigoshish in Minnesota, back when the lake was full of eater walleyes, it was also loaded with big perch over 11 inches. Then, after protective walleye slot limits were put in place, things changed fast,” he says. “We now have loads of 22- to 26-inch walleyes—lots of big fish and multiple year-classes of pike. These are the two most dominant perch predators. And when you have an over-abundance of larger predators, I’m not surprised the jumbo perch fishery on Winni fell apart. Recently, the DNR shifted the walleye slot to allow more harvest of larger fish (18- to 23-inch slot with one over 23 inches allowed in possession). So we’ll see how that affects things. But it seems perch are already spawning at earlier ages. And the impact of zebra mussels is also beginning to perhaps take a toll.”
On another large lake, Roach has observed a similar perch plight. “Mille Lacs has always cycled through major ups and downs in its perch population,” he says. “Prior to the arrival of invasive mussels, the cycles were largely parallel to walleye populations. That’s certainly the case now, as regulations stemming from co-tribal/state management have limited angler harvest to very few fish of any size, for the past several years. As a result, we have so many walleyes—including big walleyes—in the lake now that perch numbers have fallen off a cliff. Certainly, mussels might play a role in eating the plankton needed for the survival of young perch. But I suspect the perch decline is largely a factor of walleye predation.”
I’ll take Roach’s observations another step, suggesting we last experienced excellent fishing for large perch at Mille Lacs at least eight years ago. That’s a long time between naturally occurring population cycles, particularly for a classic perch lake. Unquestionably, something is happening in the environment, and perch are likely feeling the double-edged sword of survival, once again.
Big Lake Temperature Patterns
On Lake Michigan, signs of a perch revival are on the horizon. Evidence from an excellent 2019 season indicates a positive trend for Lake Michigan perch. A high-quality spawn occurred in 2015, producing abundant 8- and 9-inchers for anglers during 2019 and 2020.
Dave Rose, a guide and lifelong resident of the lake, says the key to finding near-shore perch points is water temperature. “In recent seasons, we’ve seen good perch bites, particularly as near-shore water temps have dropped into the 60s in the fall,” he says. “Stable weather helps, but winds that blow warmer surface waters offshore move perch outside the reach of most small-boat anglers. So, it’s sort of a factor of which shore you’re on—the eastern shore from Holland to Traverse City, or Chicago and Michigan City on the south end—and local prevailing winds."
One great tool for locating perch is a water temperature gauge like a Fish Hawk TD. The gauge provides a profile of the water column, revealing water temps every 5 feet. Finding that key zone with prevailing 65°F water can tell you a lot about the depth of perch.
“Another good sign pointing to good fishing in the future is when you get hordes of small perch following your bait back to the boat,” Rose says. “We’ve seen these little perch a lot the past few years and it’s got anglers in good spirits about upcoming year-classes.”
Rose says he prefers to target water less than 60 feet deep, but that’s not always possible. Sometimes, we find the biggest schools of large perch out in 145 feet of water. But one thing we’ve started to notice is that even in these depths, perch schools often disperse when you hover over them. Especially when lots of boats sit on the schools, I think the ping of sonar spooks them. Back when it was more common to anchor in deep water and let the boat swing—as opposed to sitting right on top of them with a trolling motor—we didn’t see this happening. I also think when the anchor dragged bottom, it dredged up bloodworms and created active feeding scenarios. And we’d often catch a lot more fish.”
Despite the apparent adverse effects of sonar, Rose has become a believer in side-imaging to find pods of perch. “Big sandflats are everywhere on Lake Michigan, but finding patches of vegetation in shallower water can really gather perch. Little patches of shells or rock can also attract fish. Side-imaging depicts these bottom anomalies and perch schools as clearly as a flock of geese in the sky and lets you canvass large areas much faster than 2-D sonar.”
Once he locates a pod of perch, he often spot-locks over the school, deploying a double-hook dropper rig anchored by a 1- to 4-ounce bell sinker. Hooks are baited with live minnows or a cluster of larvae—maggots, waxworms, or mousies. In water shallower than 60 feet, a #3 or #5 perch-pattern Jigging Rap or heavy spoon with a dropper, small jig, and bait can score, particularly for video-game style fishing while watching fish react on the sonar display.
Inland Lake Events
In Minnesota, I’ve keyed on a shallow-water pattern that runs from late August through early October on and off for a couple decades. On several big lakes where big perch persist, the pattern has endured. Hungry perch key on crayfish and baby perch as they find solace within stands of hardstem bulrushes rooted in hard bottom. The first time I ran across big bulrush perch, I was tossing spinnerbaits for bass and was met by wolfpacks of 12- to 14-inch perch that had, perhaps, chased the bass off their own hunting grounds. Every time I enter a bulrush bed casting for bass on one of these lakes in August and September, I hope to find big perch. About half the time it happens and I quickly tie on a downsized spinnerbait—something that snakes through the stalks yet fits into the more modest maws of perch. Either a Strike King Mr. Crappie Spin or Z-Man SlingBladeZ Power Finesse spinnerbait, sans skirt, plus a 3-inch curlytail trailer, attracts big bites, retrieved on a 7-foot medium-power spinning rod on 10-pound braid.
Brosdahl takes advantage of a similar pattern when he finds it, but keeps his eyes and side-imaging peeled for perch that work slightly deeper 4- to 6-foot hard-bottom flats adjacent to bulrush fields. He particularly likes hard to soft bottom transitions, rock clusters, and patches of coontail nearby, and searches for perch pods lying in open pockets in between. His favorite method is to anchor with his Talon and pitch 1/16- or 1/32-ounce Fire-Ball or RZ jigheads, double hooking a small to medium fathead minnow. In heavier cover, especially along chara clumps, he slides a slipfloat above the jig and lets it drift into position. “If you’re quiet, you can work the school right beneath your boat and sight-fish for individual big specimens,” he says.
Always on the leading edge, Brosdahl divulges another big perch frontier. “In late summer, baby rusty crayfish, an exotic species, go out into the soft mud where they attract the biggest perch in the lake. They’re capsule-sized crays and big perch pluck them up like jelly beans. I think the rusties make even better forage than freshwater shrimp—they’re bigger, meatier bites of food. Run your 2-D sonar on 8X bottom zoom, and you spot them as little bumps on the bottom. Or, verify with an Aqua-Vu. Then, you can drop an Impulse Crayfish or a jig and tube on them. It doesn’t much matter because big perch chew on everything that enters their strike zone.”
More Ups and Downs
Within and beyond their traditional native haunts—Great Lakes, large inland waters, and fertile prairie lakes—perch populations continue to ebb and flow. Bethke notes that some of the biggest perch she’s encountered in her population sampling have come from small remote waters in Northeast Minnesota. She’s seen a lot of big perch recently in Lake Pepin and surrounding backwaters, as well as Big Stone Lake—another riverine reservoir on the western Minnesota border. By now, both populations are well known.
Many anglers have also seen photos from Idaho’s Lake Cascade, where jaw-dropping perch up to nearly 16 inches and 3 pounds have landed on ice in recent winters. While catches of giant perch were common during the 1980s and 1990s, the fishery collapsed in the late 1990s—a result of the predacious northern pikeminnow. Following efforts in the early 2000s by Idaho Fish and Game, the glory days returned to Cascade. For over a decade, the perch fishery exploded, with incredible numbers of monster perch leaving the lake in buckets. A slow decline in catch rates over the last several years has led anglers to speculate that the lack of a perch harvest limit is the cause. Yet biologists again cite predation as the likely culrit. Idaho Fish and Game reports the perch fishery is still world class, for fish in the 13- to 16-inch range.
In case you already hadn’t noticed, people and nearly every aquatic predator—and that includes other perch—all love to munch on the yummy little critters. Indeed, as Bethke likes to say: “There’s one very good reason Rapala keeps painting crankbaits that look exactly like a perch.”
*In-Fisherman Field Editor Cory Schmidt is an astute multispecies angler and longtime contributor to all In-Fisherman publications.