Through the Cincinnati Nature Center, I attended a demonstration at which biologists from the Ohio Department of Natural Resources sampled fish from a local creek to get a snapshot of its overall condition. They focused on a large pool — one of the few left in the rocky streambed at this time of year, when rainfall is scarce — and stunned the fish with a mild electric current (we could see most of them swim off a couple of minutes after going limp). The biologists waded through the pool and collected the fish with a net, and then scooped them into a clear plastic pitcher filled with water so we could observe them up close.
In a quick sampling, they found 16 different species: bluegill, green sunfish, rainbow darters, rosy-faced shiners, large-mouth bass, creek chub, white suckers, minnows and others. Most were no bigger than a remote car key, but the presence of so many different species indicated a healthy ecosystem, the biologists said. Despite concerns about pollutants in runoff from nearby houses and commercial development, they rated the stream health an “A.”