Sack
of Milk is the English interpretation of “sac-a-lait”,
the Cajun French name for crappie. The fish are called “white
perch” in north Louisiana, but in both places they are
so esteemed for their mild, sweet flesh that the Louisiana
legislature has declared them the official state freshwater
fish.
Actually,
two species of crappie exist in Louisiana, the white crappie
and the black crappie. Both are often found and caught together
in the same waters, although each has specific preferences.
Black crappie prefer clear, still lake or back-swamp waters.
White crappie prefer the moving water of rivers and bayous
and are much more common than black crappie in turbid, muddy
waters. Both species tend to concentrate around some kind
of cover, such as brush, fallen trees and stumps.
Black
crappie are darker in color with black flecks scattered randomly
on their silver sides. In white crappie, the black flecks
are arranged in vertical bars. White crappie usually have
5 or 6 spines in their dorsal fins and black crappie usually
have 7. The most reliable way to differentiate the two is
that in the ski-jump-nosed white crappie, the distance from
the tip of the nose to the front base of the dorsal fin is
longer than the length of the entire base of the dorsal fin.
For black crappie the lengths are equal.
Both
species eat insects, insect larvae, grass and river shrimp,
and any small fish. White crappie especially prey on minnows
and other fish, including their own young. Crappie begin to
actively spawn when water temperatures reach 61°F. This
is earlier than the other members of its family, bass and
bream.
Wherever
they are found, crappie populations go up and down noticeably,
with good catches some years, followed by years of very poor
catches. In Louisiana, this cycle seems to be more noticeable
in man-made lakes and reservoirs than in rivers, the Atchafalaya
Basin, or in freshwater marshes. But even in these areas,
a population cycle may be noted.
Scientists
have found that at least two things affect these population
cycles. When good conditions produce a very successful spawn,
a large brood known as a dominant year class, survives. The
next year, this dominant year class devours its own young,
as well as other fish, and few young crappie survive. This
holds true for several years, although each year fewer fish
of the dominant year class exist. Finally, their numbers become
so low that they cannot control the young crappie and another
dominant year class develops. Few crappie live beyond age
5. The result is a couple of years of poor fishing with many
small fish followed by a couple of good years. This phenomenon
is especially true in ponds and small lakes under 10 acres.
Environmental
conditions also affect crappie populations. Research done
in Iowa indicates that water level and clarity affect the
success of crappie year classes. High water levels at the
time of the spawn were found to result in high numbers of
larval crappie. The only exceptions to this relationship were
in years of low clarity (muddy) water. Larval crappies were
never found when waters were very muddy during spawning season.
The biologists concluded, based on previous research, the
adult crappie abandoned their nests when muddy water creates
low light conditions on the bottom. They did note that actual
suffocation of the eggs may also have occurred.
Changing
regulations like size and creel limits may not work to stabilize
crappie populations. Oklahoma biologists using predictive
models have found that improving the harvest by regulation
is more the exception rather than the rule for crappies. They
concluded that only under conditions of fast growth and low
natural death rates would management with minimum size limits
improve crappie populations. Even then, anglers would have
to accept decreased harvest in numbers of fish to get an increased
average weight.
Biologist
recommendation is to never stock crappies in ponds smaller
than 10 acres. In spite of these recommendations, some pond
owners stock crappie. Research done in ponds, again in Oklahoma,
indicates that crappies compete with bass for food and serve
as food for bass, making their management difficult. They
found that the most important factor in producing good crappie
fishing was a large population of bass to feed on small crappies
(under 8 inches) to reduce their numbers.
In order
to keep the population of bass high, the number of bass harvested
by fishermen has to be kept low. High bass numbers means that
few bass in the population will grow larger than 15 inches
because of competition. Also, the few large bass produced
should not be harvested because they are effective crappie
predators.
Very
few fishermen want to lower their catch of bass, and in fact
most fishermen would like a pond to produce as many large
bass as possible. The researchers also point out that even
if bass populations are kept high, the unpredictability of
crappie spawning success from year to year makes management
for large crappies difficult.
The researchers
concluded that trying to produce quality crappie fishing in
small ponds with public access is not likely to work. They
indicated that it is possible in closely managed private ponds.
They also pointed out that a pond managed for productive crappie
fishing would probably also produce high-quality bluegill
populations.
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