In addition to monitoring fish population through annual surveys, TWRA biologists
also monitor fish habitat changes and work to maintain healthy habitat conditions.
Water level changes are monitored throughout the year and water quality is monitored
throughout the summer when high temperatures and low dissolved oxygen can pose a threat
to sport fish and food fish. Fish kills are documented by TWRA's Environmental
Services Divisions after on-site surveys conducted by regional habitat biologists.
In addition, TWRA staff meet with reservoir and tailwater regulators (i.e. Tennessee
Valley Authority and U.S. Army Corps of Engineers) several times annually to discuss
opportunities for data sharing and enhanced habitat protection.
TWRA's habitat enhancement projects for reservoirs fall into several categories:
shoreline stabilization, aquatic macrophyte establishment, and fish attractor
construction. Each of these categories has different objectives, but all are aimed
at maintaining current conditions or improving conditions for fish and fishing. Over
the years, TWRA has partnered with the public, TVA, and the Corps to work
towards this end.
Bank and Shoreline Stabilization
Tree plantings are one way that TWRA has worked to keep reservoir habitat in
equilibrium. Planting trees in shoreline fluctuation zones helps stabilize banks
and keep them from sloughing off into the water from wave action and flows. Reservoir
biologists have long planted such water tolerant plants as bald cypress and button bush
to keep shorelines intact and minimize erosion. This is especially useful in reservoirs
with a lot of overbank habitat and little rock in the fluctuation zone. Trees are
obtained from private nurseries and may be grown out at TWRA workbases so that they
can withstand the elements and herbivores (e.g. beavers and deer) better when planted.
Cypress trees in particular have extensive root systems which hold the shoreline
together
and the roots themselves may serve as nursery habitat for young fishes.
Aquatic Macrophyte Establishment and Shoreline Seeding
Aquatic plants are known to enhance survival of juvenile fishes and reduce
sedimentation in reservoirs through their root systems. Unfortunately, most
species are not tolerant of the widely fluctuating water levels that occur on
almost all Tennessee reservoirs. Drawdown zones are harsh environments with
uncertain periods out of water and a variety of terrestrial and aquatic herbivores
anxious to eat the tender stalks. The objective of TWRA biologists is to get enough
plats to survive that spread into other areas is possible. It is important to use
only native species which are adapted to local climates and do not have the potential
to become unmanageable. Some plant types commonly used are water celery, American
lotus, water willow, and various bulrush species.
TWRA biologists planting aquatic macrophytes in Old Hickory Lake
TWRA fisheries managers have long tried to grow grasses in drawdown zones to
provide nurservy habitat for juvenile fishes when reservoir water levels come up
in the spring. Seeding of water tolerant species like reed canary grass and abruzi
rye can be effective in drawdown zones that have adequate soils and area. Dry
embayment areas are usually seeded in the fall or winter to allow time for growth
prior when water level rises will occur.
Grasses growing in exposed drawdown zone after TWRA seeding at Kentucky Lake
Like macrophyte establishment, the costs of seeding can be high in both dollars
and manpower and failures are common. Likewise, planting projects in reservoirs
have not been successful on a wide enough scale (in any state) to have proven,
positive effects on sport fish populations. However, macrophytes are an important
part of natural aquatic ecosystems and we strive to establish them where we can even
in artificial environments like reservoirs. Like other state game agencies, TWRA is
working to refine techniques that can be used to establish plants, and considers its
work with live plants experimental.
Project E.C.H.O. was started in 2001 by TWRA biologists working on Kentucky Lake.
It is a pilot program that allows the Agency to experimental work with macrophyte
establishment and grass seeding in a cooperative setting. Local schools are directly
involved in plant rearing, planting, plot maintenance, plot monitoring, and shoreline
seeding. Several other state and federal agencies are also involved as cooperators,
providing funding and manpower to the projects. Embayments are picked for study sites
and school groups are assigned to work with these areas.
High School student participants in Project E.C.H.O.
Artificial Habitat Structures
TWRA biologists construct different types of fish attractors that can be placed
in reservoirs. These devices do not normally enhance sport fish populations, but
do provide structure around which fish can aggragate. Bass, crappie, and sunfish
utilize these attractors and anglers may key on these sites to increase their fishing
success.
The most common type of fish attractors used are sunken trees which can be weighted
down to the bottom of a lake. TWRA's Christmas tree habitat project in east Tennessee
is a great example of how the Agency partners with anglers to build fish attractors.
Stake beds for crappie are also used in lakes with dense crappie populations and the
right combination of bottom slope and composition. Like, tree attractors, stake beds
are marked by TWRA so that anglers know where they are located.
TWRA field staff installing crappie stakebeds at Kentucky Lake
Setting up Christmas trees for fish attractor construction
Spawning benches are a relatively new type of fish attractor for smallmouth bass.
Unlike tree attractors or stakebeds, spawning benches have the potential to enhance
smallmouth populations by providing more spawning habitat. They have been used in
several deep reservoirs (e.g. Dale Hollow, Center Hill, Norris) to provide covered
areas under which smallmouth build their nests. Research has shown that spawning
benches built on rocky points are the most utilized by smallmouth bass.
Tennessee Tech graduate students installing experimental smallmouth bass spawning benches at Dale Hollow Lake.
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