Return of the native Brook trout

Issue 4 > NPS Profile page 1 > page 2 > page 3 > page 4
Water turns green with dye added to Antimycin.

Biologists add green dye to Antimycin to track its progress in the stream.

NPS photo.

On a cool, foggy morning, the fisheries crew began their day’s work, hiking uphill along the babbling Lynn Camp Prong near Tremont to take their place at stream-treatment stations. The crew this day consisted of fisheries biologists Steve Moore and Matt Kulp, seasonal fisheries employees, biologists from agencies throughout the southeast, and a representative of the Environmental Protection Agency (EPA). The treatments were a new way for the Smokies to remove unwanted species—in this case, rainbow trout—from the water and restore the habitat for the once-abundant native brook trout.

At designated pools and turns in the river, people broke off from the group singly or in pairs and carried their gear to the streamside, where a stand with 5-gallon buckets filled with a piscicide—a fish pesticide to remove non-native fish—sat poised over the water. When everyone in the group had reached their stations, the biologists farthest upstream released a green flourescein dye into the water. Then they turned a valve on the buckets, and the piscicide—in this case an antibiotic called Antimycin A—began dribbling into the stream. As the dye traveled downstream past other stations, the biologists at each station turned on their valves to release more Antimycin, thus beginning a continuous eight hour treatment for that section of stream. Soon the top reaches of the water shimmered with the green dye marking the antibiotic. As the piscicide flowed downstream, leaves and the tumbling cold water broke down compounds within it, but release stations at set points released more to maintain the antibiotic’s concentration at eight parts per billion.

Water below the detox station turns a rusty red color.

A water strider ripples a pool turned red below the Antimycin detoxification station.

NPS photo.

The progress of the antibiotic was slow. The green dye that flowed with the Antimycin crept downstream for hours. Finally, Fisheries biologist Matt Kulp and the EPA representative saw what they had been waiting for: the roaring white of the waterfall shifted to roiling neon green. This meant that the antibiotic had reached the end of the treatment section, and it was time to turn on the detoxification station.

With the turn of a valve, jugs of potassium permanganate dribbled deep purple liquid into the water. This chemical neutralized any remaining antibiotic so that fish downstream would be safe from the piscicide’s effects. It also turned deep pools along the lower reaches of Lynn Camp Prong an eerie red hue. Graduate students from Tennessee Tech collected aquatic macroinvertebrates below this detoxification station to monitor the effects of the neutralizing chemical on these tiny organisms.

This was one long day among many in an effort to restore Smokies streams for native brook trout. Read about how this day fit into the bigger picture of healthy streams and trout on page 2: Removing and Restoring Fish: the long-term project.

Did You Know?