By Dan Klepal
The Cincinnati Enquirer

The Sloan's crayfish is running out of rocks to hide under.

A "threatened" species, the tiny Sloan's crayfish live in fewer than a dozen streams in Southwest Ohio and Indiana.

And their numbers are thought to be dropping, as the lobster-shaped creature - a main food source for small-mouth and rock bass - continues to be muscled out by pollution, construction projects and a bigger, more aggressive crayfish that is taking over some of those streams.

SLOAN'S CRAYFISH

Sloan's crayfish The Sloan's crayfish is a threatened species because it lives in only about a dozen streams in Southwest Ohio and Indiana. The crayfish: Live under rocks in smaller streams with clean water. Eat insects. Molt three times a year. Hatch young in early summer. The female first carries the eggs, then the young for several weeks. Are an important link in the food chain between fungus/bacteria on the bottom of the stream and fish and birds who eat them. Source: Ohio EPA

One of the Sloan's last strongholds is Paddy's Run, a small stream near State Route 748 in Butler County that forms the headwaters of the Great Miami River.

That's where Roger Thoma will be fishing for them today.

Ohio Department of Transportation (ODOT) officials want to straighten Route 748 and replace a culvert in the stream. That work will kick up a lot of sediment on the stream's bottom, and could end up killing however many Sloan's are living there.

Thoma plans to move a lot of rocks in hopes of snagging a few Sloan's in his net, so they can be safely moved upstream before the heavy lifting of the road project begins.

These aren't the type of crayfish you'd toss in a gumbo. There are thousands of different species of crayfish. Adult Sloan's measure less than one inch long.

Thoma, a fisheries biologist with the Ohio Environmental Protection Agency (OEPA), has studied Ohio's crayfish for decades. He says the Sloan's crayfish has a special place in his heart.

"There are a lot less now than there used to be, and I got interested in them because they are a disappearing species and I want to figure out how to stop that," Thoma said. "We're getting to the point where populations could be wiped out if something terrible were to happen."

"It's dangerous when they're all sitting in one place."

Other people, particularly fishermen, should care about the Sloan's plight. Because they are a staple food for bass, it would be a major kink in the food chain of several sport fishing streams if the Sloan's were to disappear.

The Sloan's are also like a canary in a coalmine - they need clean water to survive, so they are excellent indicators of the health of the streams they live in.

There's another reason to care, too, said Whitney Stocker, a biology professor at Dennison University and another expert on Ohio crayfish.

"You just don't want to lose the genetic diversity that's out there," Stocker said. "Any one species lost is irreplaceable and a crime. This world exists because of diversity. We've caused so much extinction in the last couple of hundred years, it's impossible to predict what the result will be."

Brenda Bradds, a transportation department spokeswoman, said the road project was set to go when EPA realized that it could affect the crayfish. ODOT then had to apply for a permit before proceeding. The $350,000 project is now scheduled to begin in October 2004.

Thoma said changes in Ohio's land has allowed the Sloan's competition - the larger and more aggressive rusty crayfish - to take over.

"As we change our land use and take trees off and plant row crops and put housing up, all those things that result in pollution, the nutrients in streams go way up and allows the rusty to move in," Thoma said. "That forces out the Sloan's."

E-mail dklepal@enquirer.com