The Perch Puzzle

by Craig Bihrle

North Dakota Outdoors Nov. 1995

Winter's Bite During North Dakota's open water season, walleye, a member of the perch family, attract more attention than any other fish. But by late November, waxworms replace fatheads as the bait of choice, and antsy ice anglers tentatively probe recently frozen water for secure support. It's perch-fishing time, and conventional wisdom says the earlier you get at them, the better.

"Perch is probably the number one winter fishery in the state," says Greg Power, central district fisheries supervisor for the Game and Fish Department.

Not many lakes offer the opportunity for truly large perch - those weighing three-quarters of a pound or more. But numbers seem more desirable than size. People like to catch lots of fish, and as long as those fish are big enough to keep, most anglers are happy. Perhaps that's why perch are so popular in winter. In the right lake they can dunk a bobber all day long and yield nice frying fillets as well.

Wrong Lakes, Right Lakes

The popularity of perch as a winter fishery dictates that the Game and Fish Department try to manage certain lakes to sustain quality perch populations. Some lakes need little help. Others can benefit from a transplant of perch from other lakes, manipulating water levels, or introducing large predators (walley or northern pike) to keep perch numbers from expanding too fast. And then there's lakes, perhaps a majority of those in North Dakota, that can't or won't support a quality long-term perch fishery no matter what people do.

Managing perch is a challenge. Meeting angler expectations of "A lot of big fish that are easy to catch," says eastern district fisheries supervisor Lynn Schlueter, must be balanced against what each lake can provide.

"It is important that fishery managers try to provide what the public wants," Schlueter added, "but sometimes what is wanted cannot be provided in that particular lake."

"Each lake has its own carrying capacity and its own capability of producing a certain type of fishery," Power said. "Some aren't geared toward perch....It all comes down to the food chain. Some lakes have it and some lakes don't." While perch will eat minnows and other fish smaller than themselves - young of-the-year gamefish, for instance - their primary diet is aquatic invertebrates. Gammarus, or freshwater shrimp, are a favorite. Part of the reason Devils Lake perch grow so large is because of abundant freshwater shrimp, but not all lakes can produce shrimp, and not all lakes with shrimp produce good perch fisheries.

Without an adequate food base, perch won't grow to a size - the breaking point seems to be around the 7-8-inch mark where they are desirable to anglers.

A good case in point is Fish Creek Dam, a small reservoir about 30 miles southwest of Mandan. When Fish Creek was chemically eradicated in 1992, it contained perhaps hundreds of thousands of yellow perch, most of which measured six inches or less. While an angler could catch perch all day long at Fish Creek, hardly anyone fished there for several years because the perch were too small.

It was a classic example of a stunted population (when they're bad they're horrid) - the fish found enough food so they could live and reproduce, but there were so many perch there wasn't enough food for any of them to reach a quality size.

Fish Creek had been eradicated previously because of a stunted perch population. Game and Fish then stocked other species to create a new fishery, but someone illegally introduced perch back into the lake. Once that happens - and it has happened at other lakes around the state perch will likely reproduce, Power said. That first year class may do well. But once the population multiplies, the cycle starts again and within just a couple of years small perch dominate the lake. They don't grow large enough for angler harvest, and they limit the potential for other fish populations.

Other lakes in which stunted perch populations have been eradicated recently include Hooker Lake in the Turtle Mountains (1992) and Velva Sportsmen's Pond in Ward County (September I995). Perch were illegally introduced into those lakes as well.

(Photo by Harold Umber)

On the positive side is Devils Lake, which from the late 1970s to around 1990 was a perch angler's dream. The lake harbored lots of perch, and they were big. In fact, so many perch weighing more than a pound-and-a-half (perch qualifying weight for the Whopper Club) came out of Devils Lake that the Game and Fish Department increased the minimum Whopper Club weight for Devils Lake perch to 1.75 pounds in 1980 and two pounds in 1982.

Ice fishermen came from throughout the Midwest to catch buckets of big perch. In the early 1990s, due primarily to poor reproduction caused by the drought and low water levels, perch numbers in Devils Lake dropped off, but it still attracts considerable perch fishing effort.

Basic Biology

Yellow perch are members of the perch family, which also includes walleye and sauger.

Unlike walleye and sauger, which spawn over gravel or rubble bottom structure, perch prefer to spawn on or near underwater weeds. Lakes without submerged vegetation are unlikely to support perch reproduction. Weeds also provide escape cover for young perch, and they are food for the aquatic bugs perch eat.

But lakes with too much vegetation can overpopulate with perch, as excess weeds may provide too much protection from predators. Perch are not a fast growing fish. Under normal conditions it takes about three years for them to reach 7-8 inches long and attract significant interest from anglers. In four years they may grow to 9-11 inches, and perhaps beyond a foot in six or seven years. Age seven is about as old as perch get in North Dakota.

In lakes where perch are stunted, they may live a half dozen years and not even reach six inches in length.

(Photo by Craig Bihrle)

Booms and Busts

Like many other fish species, perch populations rise and fall in cycles driven by water levels. When water from spring runoff floods vegetation, good perch spawning habitat is created. Stable water in lakes with residual cattails or bulrushes also aids perch spawning and recruitment of small fish.

But when lake water levels decline, leaving vegetation high and dry, perch spawning is curtailed. Without a spawn, there is no new year-class of fish to replace those caught by anglers or dying of old age. Two or three consecutive reproduction busts can greatly reduce an otherwise strong perch fishery. This situation leads to increased angling pressure on just one or two older year classes, which can be quickly fished down.

Such was the case with many North Dakota lakes, including Devils Lake, during the drought.

Now, the water cycle has switched to the plus side. Perch are finding flooded weeds in which to spawn. Formerly good lakes won't come back overnight, but the outlook is promising. "I think in the next few years we're going to see an explosion of interest and effort in perch fishing," Greg Power said.

Managing the Interim

Even during the drought years, North Dakota had lakes with lots of perch. While some of these lakes had stunted populations, they served an important purpose: providing fish for transplant to other lakes. Over the years, Department biologists have learned that stunted perch can grow rapidly when moved to another body of water that contains the right requirements. "It is not unusual," says fisheries biologist Gene Van Eeckhout, Jamestown, "to hear reports of 3/4 to 1 1/4 pound perch coming out of renovated (eradicated) lakes a year or two after fingerlings and/or subadults were stocked."

For many years, Blacktail Dam provided perch for stocking in numerous lakes throughout North Dakota. In recent years, Brush and Strawberry lakes in McLean County have provided perch for this purpose. They've been put in lakes to supplement a lack of natural reproduction, and they've been used to start perch populations in lakes that had winterkilled or were chemically eradicated.

It is unfortunate, however, that Brush and Strawberry have perch at all. At one time, these McLean County lakes were two of the top bluegill lakes in North Dakota. They grew big bluegills, and lots of them. But they don't grow big perch. Sometime in the mid-1980s perch were illegally introduced into both lakes. They reproduced successfully. The population exploded. Now both lakes have hundreds of thousands of stunted perch, and the quality bluegill fisheries are a thing of the past.

Few perch in Brush Lake grow beyond six inches, and most are smaller. Scale samples indicate five-inch fish from Brush could be two years old or five years old. Though great numbers of these fish have been moved elsewhere, the perch populations in these two lakes have changed little.

While transplanting perch to other lakes often helps the receiving lakes, removing perch has not generally proven effective in turning around lakes with stunted populations.

To give Mother Nature a little help at Devils Lake, in the early 1990s Game and Fish for the first time actually took eggs from perch and incubated them at Valley City National Fish Hatchery. When the eggs hatched, the fry were released in Devils Lake. Supplemental stocking couldn't replace natural reproduction, but it helped. For the last couple of years, hatchery-produced perch fry and fingerlings have been stocked in a number of state lakes.

Game Fish or Prey?

Depending on the lake in which they are stocked, perch may have a dual purpose. Not only are they a popular fish with anglers they are also a food source for larger game fish such as northern pike and walleye.

Many North Dakota lakes are managed as pike/perch fisheries. In some lakes, perch are stocked primarily as food source, but if the right conditions exist, some will grow large enough to attract angler interest as well.

If predators can't keep perch in check when they're small, the perch can get out of hand. In turn, they may become a predator on stocked or naturally-reproduced game fish. Too many large predators, on the other hand, can limit a perch population's potential to provide opportunity to anglers. "Balance" is what fisheries managers strive to accomplish, Schlueter says, but weather, angling pressure and illegal introductions are all factors that can disrupt that balance.

The Long Run

Managing perch is a complex business. They can be a dream come true, or a nightmare.

Fisheries biologists are still learning what it takes to nurture a healthy perch population.

For instance, the size of a lake may be an important factor in determining whether it can sustain a quality perch fishery. Biologists feel that small lakes those less than 50 acres - are not well suited to perch. Efforts to manage those lakes will more often concentrate on other fish.

Trying to manage small lakes for more than one panfish species, i.e. bluegill, crappie and perch, is often detrimental to a lake. "In situations where I have some control, such as winterkill or lake renovation," says Van Eeckhout, "I'm going with one panfish species to try to avoid some of the problems that occurred in the past. This is frequently unpopular with the angling public because they want bluegill, crappie and perch, as well as northern and walleye, etc., etc. But it just isn't working when we stock all these species in every lake."

Not every lake can grow lots of big perch. Says Greg Power: "We're still learning. We're developing that lake-specific information, and in time we hope to understand why some lakes produce perch better than others, and what we can better manage those lakes over the long haul.

"Each lake is different, and how you manage them has to be different."

CRAIG BIHRLE is associate editor of North Dakota OUTDOORS. Return to ND OutDoors

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