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Biologists Investigate Novel Way to Repopulate Brook
Trout Native to the Southern Appalachian Mountains
Each of these hatcheries have different water sources:
the Tennessee Aquarium Conservation Institute uses
recirculating water in their systems; the Tellico Trout
Hatchery uses stream water; and the Erwin Trout
Hatchery is springfed. As part of these efforts, fisheries
biologist Brad Cook and his team, including graduate
student T.J. Johnson, were called in to collect data on
which of these methods is the best.
(Cookeville, Tenn.) The Tennessee Wildlife Resources
Agency (TWRA) and the U.S. Forest Service are
interested in protecting a species of fish that, while not
endangered, is declining in numbers. The brook trout
is the only species native to the
southern Appalachian Mountains, and—thanks to
encroachment from other fish, acid deposition and
dropping pH levels—are now restricted to extreme
While techniques like electrofishing and angling have
been used to remove rainbow trout Oncorhynchs
mykiss, the fish that are competing for the brook trout’s
habitat, methods of restocking are helping supplement
those efforts and repopulate the brook trout in their
home. One method of restocking involves
translocation, or moving fish from other areas to the
new stream. But, genetically, that might not be the best
way. The use of hatcheries to raise brook trout
populations seems to be the most effective way of
In 1992, TWRA began raising southern Appalachian
brook trout at Tellico Trout Hatchery. The Tennessee
Aquarium Conservation Institute, the Tellico Trout
Hatchery, and the Erwin Trout Hatchery are now raising
brook trout for this research project.
The research team collects brood fish each fall from
Sycamore Creek and from Left Pring Hampton Creek.
About 50 male and female adult fish, ranging from five
to ten inches long, are taken to the Tennessee
Aquarium Conservation Institute and the Tellico Trout
Hatchery where the researchers take milt from males
and eggs from females and then place the fertilized
eggs in incubation jars until they hatch.
“The colder the water temperature, the longer it takes
for hatching,” Cook said.
According to Johnson’s data, the spawnings in 2013
were the most productive at the Aquarium Hatchery,
with approximately 53% of the eggs surviving from the
eyed egg stage to the fingerling stage, in which the fish
can be transported back to the river.
“The fingerlings are packed in thick plastic bags and
transported by horse to the streams in September,”
Johnson said. “There they are evenly distributed along
the streams. If they live until March and survive the
winter, we consider the fish as having recruited to the
The researchers mark the fish with pliable plastic tags
to distinguish which hatchery they originated from.
They are careful to restock fish back into the stream
from which they originated, i.e., Left Prong Hampton
Creek fish back into Left Prong Hampton Creek and the
Sycamore Creek fish back into Sycamore. The
researchers revisit the sites 30, 90 and 180 days after
While mortality of stocked fish is possible through
predation and prolonged cold temperatures,
researchers are not sure to what extent this occurs
because flood events can also push them down stream,
in which case they may not be dead. Researchers know
that angling is not a major threat to brook trout because
their size and the difficulty in reaching their habitat
keeps them from being as desirable a catch as other
fishes to most anglers.
“This helps tell us that hatchery propagation and
stocking methods are suitable techniques to establish
these populations of fish,” Cook said. “Eventually, we
hope that we won’t have to stock them, but we’re going
to gather another years’ worth of data before the project
will be complete.
“We’re finding that Sycamore Creek is in need of
restoration, but it’s becoming a good population of
brook trout whereas Left Prong Hampton Creek is
already a good population.
“This project is teaching us a lot about the brook trout’s
habitat and survival needs,” Cook said.
He and Johnson want to publish their work to make
future restocking and restoration efforts more effective.
Johnson has already presented his data at state
meetings. He plans to graduate with a master’s degree
through the project in May 2016.
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