CULLOWHEE — Biologists from the Mountain Aquaculture Research Center at Western Carolina University have identified eight additional streams that contain Southern Appalachian brook trout in the second phase of a three-year study of wild brook trout populations in the Pigeon River watershed.
Of 23 streams sampled in the study, biologists have identified 15 streams as having pure strains of Southern Appalachian brook trout. The streams are primarily in remote sections of the Middle Prong/Shining Rock Wilderness Area in Haywood County.
Aquaculture Research Center biologists and N.C. Wildlife Resources Commission biologists plan to submit a joint proposal to the National Fish and Wildlife Foundation for a grant to make similar studies of approximately 50 streams in the Tuckasegee River watershed in Jackson County.
University of Tennessee biologists have conducted studies in Great Smoky Mountains National Park streams, also identifying brook trout that are genetically different from the more widely dispersed northern brook trout.
Led by Peter Galbreath, director of the Aquaculture Research Center at WCU, biologists collected brook trout by electroshocking. An electric charge is applied to a pool or stretch of stream to stun fish so they can be collected easily and placed in a holding net. Biologists then used a biopsy needle to take a sample of muscle tissue from the trout. Both the electroshocking and tissue sampling are non-lethal, and the fish are released back into the stream.
“They tolerated the sampling quite well,” Galbreath said. “We didn’t lose a single trout.”
At the laboratory, tissue samples were ground into a “soup” of cellular proteins and enzymes, Galbreath said. Using a process called electrophoresis, samples were placed on acetate film coated with cellulose and exposed to an electric charge that spread proteins to positive and negative sides of the film.
“The process is sort of like spreading a deck of cards face down, with part of the deck going one way, and the other part going the opposite way, each card representing a different protein or enzyme,” Galbreath said.
The gels then were treated with a solution of substances that showed where enzymes migrated, “the equivalent of turning a particular card face up, following the deck of cards analogy,” Galbreath said. “Due to slight differences in the patterns, the process permitted us to distinguish which brook trout populations were of native Southern Appalachian origin and which had interbred with trout of northern origin,” he said.
“Electrophoresis is very effective as a diagnostic tool for identifying the different strains of brook trout,” Galbreath said. What the procedure does not show, he said, is why northern and southern brook trout are different. “An intriguing question, though extremely complicated to analyze, is did southern brook trout evolve to adapt in a significant way to the warmer temperatures and more acidic conditions found in Southern Appalachian streams,” Galbreath said. (Northern brook trout streams are not only cooler but also more alkaline because of natural limestone runoff in the streams.)
“A major importance of our trout studies,” Galbreath said, “is that they mesh with the national movement to recognize genetic diversity and the need to preserve native species.”
Of the 23 streams that Galbreath and his assistants sampled, six showed a mix of northern and southern brook trout genetics, and two streams contained only northern brook trout. The remaining 15 streams contained pure populations of the region’s unique Southern Appalachian brook trout.
“We found more native brook streams than I expected,” Galbreath said. “Some of the streams were not very far from human habitation, and we expected the percentage of populations of mixed genetic origin to be higher. We were surprised the number was so low.”
Despite a long history of northern brook trout being stocked in the Pigeon River system, Galbreath said, “it is evident that hatchery brook trout were rarely successful in establishing themselves or interbreeding with native brook trout.”
Joseph Moore of Grafton, Va., a graduate biology student, assisted Galbreath and Jerry West, professor of biology at WCU, in the initial study. Laura Spell of Pittsboro, also a graduate student, and Nathan Adams, a research technician at the aquaculture center, assisted Galbreath in the second study.
Findings from the two studies will be presented at the annual meeting of the North Carolina chapter of the American Fisheries Society in January 2000 and at the 2000 mid-year Southern Division of the American Fisheries Society meeting in February. Manuscripts of the studies have been submitted for publication in peer-reviewed scientific journals as well, Galbreath said.
Results of the studies also have been shared with the N.C. Wildlife Resources Commission and other interested agencies. Wildlife Commission fishery biologists said the studies will be valuable in helping the commission formulate appropriate sport fishing regulations and decide if a brook trout population in a certain stream need protection.
Funds for the studies were provided by two grants from the Pigeon River Fund.