Crawdads Add “Fuel” To Ozarks Streams - by Bob Distefano

Story by: Guest Contributor

First posted on 02-06-2009

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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