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 do...to 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.
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Last modified Feb. 7, 1996