What Do Jumbo Perch Eat?
November 28, 2017
Sweet-tasting yellow perch of jumbo proportions are coveted catches across the Ice Belt. Yet not all lakes hold equal populations of these finned footballs. Due to a number of factors, perch abundance may boom in one fishery and bottom out in another. Anglers who understand what it takes to fuel a rising tide of jumbo perch can improve their odds of putting portly perch on ice — as well as figure out where to find perch in a particular lake.
Factors affecting perch size and abundance include fishing pressure, year-class strength, seasonal die-offs, predation, and forage abundance. Of these, the food factor is a driving force in how fast fish grow and where they're located at any given time.
"Diet is certainly one of the major variables contributing to perch size," says Randy Hiltner, North Dakota Game and Fish fishery supervisor for the state's northeast fisheries district, which includes legendary Devils Lake. The spectacular perch population in this 160,000-acre plains paradise is propelled largely by massive amounts of tasty invertebrates, including bite-sized amphipods commonly called scuds or freshwater shrimp. This all-you-can-eat shrimp feast helps Devils Lake perch reach the 10-inch mark in around 5 years. "The shrimp are only an inch or less in length, but when you get enough of them you have a lot of energy available and good growth rates," Hiltner explains. "Perch eat other invertebrates such as water boatmen, too, but their primary focus is freshwater shrimp."
In Devils Lake, Hiltner says you find shrimp virtually top to bottom, shore to shore. "They're widespread and there are plenty in habitats preferred by perch so fish don't have to wander far to find a meal," he says. "We see schools of jumbo perch roaming mudflats in the main-lake basins, rooting out invertebrates. This helps buffer mortality due to natural predators and fishing pressure because perch aren't concentrated in one spot."
Hiltner is careful to point out that forage and fishing pressure are only part of the equation. "If perch numbers get too high, the population tends to get stunted," he says. "Not exceeding a lake's carrying capacity is critical to attaining good growth rates."
Year-class strength is also a factor with many fish species, and perch are no exception. "Highly variable reproductive success limits perch populations," he says. "They may have a strong year-class and then not have another good hatch for 5 or 6 years, which means that the fish from one good spring carry the lake for a while."
Hiltner also says there's no magic formula for predicting a banner hatch. "It's hard to nail down," he says. "It's dependent on living and non-living forces including wind, water temperature, and egg predation. All the stars have to align for perch to pull off a strong year-class."
When they do, however, it's a safe bet that the lake will produce above-average ice fishing when those fish mature — which means checking with local fishery biologists for year-class and growth-rate data that can help you locate bumper crops of perch other anglers might miss.
Finding jumbo perch and catching them are two different matters, of course, especially when the fish are well fed. "Abundant forage can be a double-edge sword for anglers," he says. "If there's enough food for perch to fill their bellies without working too hard, they can be challenging to catch. This can be the case at Devils Lake at times, although there are also days that make up for it."
Upper Michigan's Lake Gogebic is another top destination for obese perch, which locals fondly call "teeter pigs." As in Devils Lake, Gogebic perch wax fat on invertebrates, though in this case we're talking juvenile mayflies, or wigglers. "Wigglers are high in calories and make excellent forage," says George Madison, area fishery manager with the Michigan Department of Natural Resources. So abundant are Gogebic's mayflies, he adds, that the nearby national weather service office in Marquette has mistaken hatches for storm clouds.
Gogebic's profusion of mayflies also helps make up for a lack of minnow prey. "Walleyes are so abundant, there are few minnows," Madison explains. "The walleyes also keep the perch population low. Very few perch survive past 8 inches, but those that do get enormous."
He cautions that Gogebic isn't a numbers game. "This isn't like Saginaw Bay or Bays de Noc, where you go for a bucket of perch," he says. "Creel surveys indicate most anglers get skunked, with three fish being a decent day on the lake. But, thanks to the lake's clear water, Gogebic perch exhibit a bright yellow-green barred coloration that makes them some of the most beautiful trophies around."
Not all mega-perch factories run on invertebrates, of course. Diet studies on Lake Michigan, for example, revealed that perch measuring less than 7 inches are adept at consuming fish eggs, while their larger counterparts feed heavily on non-native round gobies and alewives.
Likewise, small fish fuel the food chain in southern Ontario's mighty Lake Simcoe — a perennial jumbo perch powerhouse that routinely produces 11- to 13-inchers, plus a few in the 15-inch range. In-Fisherman friend and perch fan Wil Wegman, a well-known author, guide, and conservationist, reports that round gobies have become so abundant, few predatory fish fail to capitalize on these bottom-dwelling baitfish, including perch.
"And cisco, or lake herring, have rebounded from the brink of extinction to the point the season was reopened to anglers in 2015," he says. "Young ciscoes, which suspend almost anywhere in the water column, are so abundant and widespread that they, too, have become a significant food choice for opportunistic perch."
Sometimes a new addition to the perch's food base can spark dramatic changes in a lake's perch population. For example, In-Fisherman Field Editor Gord Pyzer reports how the arrival of non-native species altered perch dynamics in Lake of the Woods.
About the time Pyzer was retiring from his post as a district manager for the Ontario Ministry of Natural Resources in Kenora, the invasive spiny water flea began showing up in force. "Today, they've gained a massive hold in Lake of the Woods, to the detriment of local zooplankton, phytoplankton, and certain species of fish," he says.
Perch are one of those species. "Spiny water fleas have had a significant impact on yellow perch," he says. "Numbers of perch have been drastically reduced population-wise, but fish size has ballooned."
Thanks to their spiny appendages, the fleas are virtually inedible to small gamefish. "But it seems that once the perch get big enough, they turn the table on the fleas and eat them," he says. "As a result, Lake of the Woods has been transformed from a 'numbers' fishery into one of the finest trophy perch fisheries anywhere."
Pyzer promises it's not uncommon to stumble onto schools of fish rivaling the size of perch anywhere on the planet. "We're talking schools of 13-, 14-, and 15-inch fish with huge bodies and humpbacks," he says. "They're the size of small walleyes, and it's not uncommon to catch 40, 50, even 70 or 80 perch — once you find them."
In fact, that's the trick. With a million acres of water to work with, pinpointing pods of jumbos can be a needle-in-a-haystack affair, especially for the uninitiated.
During summer, Pyzer simplifies the search by keying on clouds of water fleas, which he says resemble balls of baitfish. "The closer the fleas are to bottom, the better the fishing," he adds, noting that the flea infestation has not triggered changes to his normal perch presentations.
The flea factor subsides once the lake's surface solidifies. "The fleas have had a major impact in terms of late-fall perch congregations and locations," he says. "But at least from my experience, something happens once ice covers the lake. I suspect the fleas and perch segregate in terms of preferred winter habitat, so their paths don't cross or overlap like they do in the fall.
"I typically find so many spiny water fleas in the stomachs of perch in late fall that I can't hold them all in my hand — I get overflowing handfuls from a single big fish. But in the winter, I never see fleas in their stomachs. It's interesting, to say the least."
Under the ice, perch switch their attention to another one of Lake of the Woods' exotic species, the rusty crayfish. "The lake has an unbelievable number of these invasive crayfish, and perch target them almost exclusively in winter," Pyzer says. "I'm sure it's a case of 'abundance' rather than 'preferred' forage, because perch smack the living daylights out of a shiner-dressed jig or small spoon."
Pyzer's observation brings up a great point on how matching the hatch isn't always the best call. Although it's definitely food for thought, this angle remains a story for another day.
*Dan Johnson, Isanti, Minnesota, is a frequent contributor to In-Fisherman publications and director of All Creation Outdoor Media.