Great Smoky Mountains National Park officials are making plans for a second attempt to kill non-native trout with fish poisons as a way of restoring brook trout populations to some streams.

Although last year’s brook trout restoration program in the Great Smoky Mountains National Park was halted due to unsatisfactory results, fisheries biologists are poised to implement a similar plan this September.

GSMNP fisheries biologist Matt Kulp said the park was confident it knew the reason for last year’s failure, and plans had been modified to ensure success this year.

The Appalachian brook trout is a distinct subspecies and is threatened across much of its range. Native brookies are displaced by the larger, introduced rainbow and brown trout in streams where they cohabitate. The park is mandated to try and restore native species where possible. Park biologists believe the re-establishment of native brook trout is feasible in the upper reaches of several streams within the park.

Last October, park biologists initiated a program in Sams and Starkey creeks using the fish poison antimycin to remove non-native rainbow and brown trout from suitable brook trout habitat. Treatment was started on Oct. 23, 2000. Trout had been placed in “live cars” at designated sites in the streams so biologists could monitor the effects of the antimycin. Biologist were puzzled when fish downstream in the live cars showed no impact as late as the next morning.

Treatment was resumed on Oct. 24, and a station at the confluence of Sams and Starkey creeks was added. Later that day, live cars above the confluence still showed little adverse impact but one, 100 meters below the confluence, showed heavy impact.

Park staff met on Oct. 25 to discuss the dilemma. With too many questions to answer and allotted time periods running out, the park decided to terminate the project, evaluate the effort and determine appropriate future actions.

Kulp said biologists believe the main difference between the small area below the confluence (where the antimycin was effective) and the upper reaches of the streams was the amount of leaf litter. The channel below the confluence was open. The streams above the confluence were covered with heavy leaf litter.

According to Kulp, the protocol for the project in the GSMNP was modeled after successful programs in western parks. The overlooked variable was leaf fall. It is not a factor in the west where there are few deciduous trees, he said.

Kulp said discussions with the manufacturer pointed out that antimycin would bind to fatty compounds. Biologists think the antimycin was binding to the cellulose in the fallen leaves.
“Where the channel was clear, the antimycin worked as designed,” Kulp said.

He said the park will initiate the project at the end of September this year to avoid the problem of leaf litter. Kulp said surveys performed in the section of creek where the antimycin was effective showed little or no effect on the aquatic insect community. He also said salamanders and crayfish showed little or no effect from the antimycin.

Based on information gathered from the 2000 effort, the 2001 restoration plan has been modified. The two primary modifications are the switch to a September date and the use of electrofishing rather than antimycin in approximately 900 meters of Sams Creek and 600 meters of Starkey Creek. These areas will be electro-fished because of the collection of two specimens of a rare caddisfly, Neophylax kolodskii, from the area in 2000.

Stations will be placed in a manner to effectively treat about 300 meters of stream. Application rates will be either eight parts per billion (ppb) for eight hours or 10 ppb for six hours. Pre- and post-treatment surveys will be conducted within a week of the 2001 treatment. Long-term monitoring will be initiated in November 2001.

The park will continue efforts to prioritize streams for future restoration efforts. According to park officials, public comment prior to the 2000 effort was 85 percent in favor of native brook trout restoration.

 

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The Smoky Mountain News