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Habitat Monitoring and Enhancements

TWRa bouy

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.

Planting on Old Hickory

TWRA fisheries managers have long tried to grow grasses in drawdown zones to provide nursery habitat for juvenile fishes when reservoir water levels come up in the spring. Seeding of water tolerant species like reed canary grass and abruzzi 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 the 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.

Project ECHO Students

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 staff installing crappie stake beds 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