2/27/2006
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| Crayfish provide the foundation for Ozarks streams' smallmouth bass and goggle-eye populations, according to ground-breaking studies conducted by the Missouri Department of Conservation. (Missouri Dept. of Conservation photo) |
Crawdads Add "Fuel" To Ozarks Streams
Without these pint-sized lobsters, fishing would not be half as much
fun.
JEFFERSON CITY-Fuel is plentiful in Ozarks streams, and anglers are reaping
the benefits. The fuel isn't petroleum, but crustaceans.
A study by the Missouri Department of Conservation concludes that the main
energy source for Missouri's most prized Ozarks sport fish is the lowly
crayfish. That, says the agency, is one good reason to ensure that Ozark
streams remain clean and healthy.
In recent years, fisheries biologists have learned much about managing
smallmouth bass and goggle-eye, also known as rock bass. They have proved
the benefits of special regulations designed to produce more and larger
fish. Now they have evidence that managing these fishes'
environment-including the animals they eat-is just as important to producing
quality fishing.
During the 1990s, Conservation Department biologists examined the stomach
contents of more than 25,000 smallmouth bass and goggle-eyes on portions of
the Jacks Fork and Big Piney rivers that were managed especially for those
species. They found that crayfish make up more than 60 percent of smallmouth
bass food and 78 percent of goggle-eye food. The great majority of the
crayfish consumed were medium-sized, not large or small. In short, crayfish
are the fuel on which Ozarks smallmouth and goggle-eye fisheries run.
Crayfish make up the bulk of both species' diets. Young bass and goggle-eye
also eat large numbers of stoneflies and mayflies. Like crayfish, these
creatures are sensitive to changes in their environment. The most important
threat is loss of habitat due to sedimentation-mud and other materials
washing into streams. Anything that reduces water quality also ultimately
reduces the number and size of smallmouths and goggle-eye.
Fisheries biologists also wanted to learn whether fishing regulations that
increased the number of large bass and goggle-eye would cause a dip in
crayfish numbers. They discovered that Jacks Fork and Big Piney crayfish
populations-which are some of the most abundant in the world-held up well to
larger predator numbers. They responded by reproducing more rapidly.
The study is the first in the world to systematically track the relationship
between fishing regulations, sport fish populations and the abundance of
their prey. The knowledge gained will help ensure that Missouri's fishing
resources don't run out of fuel.
-Bob Distefano-
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