Brook trout are making a comeback in Great Smoky Mountains National Park.
By Amy Leinbach Marquis
Several times a year in Great Smoky Mountains National Park, fisheries biologist Steve Moore straps a 35-pound generator onto his back, wades into a stream, and plunges two charged poles below the surface, delivering 650 volts of energy to the water. (Rubber boots and waders prevent him from zapping himself.) One by one, Moore and his team sort through stunned fish that float to the surface. If the stream is small enough, they remove and kill the rainbow and brown trout that invaded these waters a century ago. In larger, deeper sections, they’ll scoop up as many native brook trout as possible, shuttle them to safe waters, then release an EPA-approved antibiotic called antimycin to kill off the remaining offenders.
The idea of electrocuting and poisoning fish might not sit well with some park lovers. I know—I was raised by a fly-fishing father and an environmentally conscious mother just a day’s drive from the Smokies. I have the fondest memories of scrambling down steep, wooded banks with my dad to reach prime trout habitat, quietly searching for snails in leaf litter, and picnicking in the trunk of our hatchback Honda. The idea of causing such destruction to my childhood haunts gives me serious heartburn.
But the fact is, native brook trout—those colorful little fish that made my dad’s eyes sparkle like sunlight on water—are finally making a comeback after a century-long decline. And we have Moore’s techniques to thank for it.
The problems began in the early 1900s, when large-scale logging operations began rumbling through Tennessee and North Carolina’s Smoky Mountains, clear cutting on steep mountainsides and along stream banks. Soil eroded into waterways, burying trout eggs laid in the gravel. Once-shaded streams heated up in the sun, killing scores of brook trout that can’t survive temperatures above 68° F. It wasn’t long before the species disappeared from every stream below 3,000 feet.
Thankfully, brook trout had some friends in their corner—anglers—who took notice of the decline and demanded that the loggers repair the damage. The companies responded. But what seemed like a good solution in 1910—restocking streams with non-native rainbow trout from the western United States, brown trout from Europe, and brook trout from the northern United States—only pushed the natives closer to the brink when the newbies out-competed and interbred with brook trout. Stocking of these non-native fish continued for decades before biologists recognized the damage and halted the program completely. By then, only a relentless management program could help the native species recover.
Enter Steve Moore, a curious graduate student at the time, who set out to test the effectiveness of electrofishing. His research revealed that the technique works best in small, shallow streams, and that larger, deeper waters require additional help from antimycin. His approach revolutionized the way biologists manage fisheries across the country.
Such aggressive tactics, however, bear consequences. Not only do they kill the fish that aren’t supposed to be there; native brook trout and insects occasionally perish in the process, too. “I don’t like losing any of the good guys,” Moore says. “I’ve spent nearly 30 years trying to save native brook trout in the Smokies. But it’s better to lose a small number for the long-term gain of the entire population.”
Case-in-point: Although Moore lost approximately 200 native fish after treating a three-quarter-mile section of a stream, as many as 1,800 brook trout are swimming that very same stretch today. And that’s along just one mile of roughly 32 miles of park streams that have been successfully restocked.
But all the restoration efforts in the world won’t save the species if the water is polluted—and nearby coal plants, large-scale agriculture, and automobiles continue to spew toxins into the environment. In April 2011, thanks to pressure from the Environmental Protection Agency, southeastern states, and conservation groups (including NPCA), the Tennessee Valley Authority helped slow that trend by phasing out dozens of dirty units and installing modern pollution controls in the region’s coal-fired power plants. Recent monitoring in Great Smoky Mountains shows that although sulfates have decreased significantly, nitrates haven’t. As a result, streams are becoming more acidic and, basically, uninhabitable.
The good news? Park staff are working on a plan that moves the region toward cleaner air and water. Organizations like Trout Unlimited fill the funding void by raising money and rallying volunteers to measure water acidification, electroshock streams, and catch—and eat—as many non-native trout as possible prior to a chemical treatment.
“I’m pleasantly surprised that so many anglers got behind this effort,” Moore says. “These guys believe in us, and that’s very gratifying.”
Plenty of work remains in the park—35−40 miles worth, in fact. And biologists aren’t sure how rising water temperatures associated with climate change might affect the species down the road. But the fact that native trout are making a slow, steady comeback today can only help their success in the future.
“Our predecessors didn’t know any better when they destroyed habitat and stocked non-native fish,” Moore says. “Now we have the opportunity to turn back the clock and do the right thing for a species on the brink.”
And that’s an effort that would make my father smile.