Fish Habitat Management
The term “habitat” refers to all components of the environment necessary for fish to spawn, breed, feed, and grow to maturity. Many parts of the environment contribute to healthy fish habitat, including water quality, water level regimes, nutritional inputs in the form of critical chemical elements, cover for young fish and predators, and substrate for the production of various invertebrates which contribute to the complex food chain in a fishery. Maintenance of healthy fish habitat is necessary to ultimately produce productive fish populations with favorable growth, abundance, and size characteristics, which are beneficial for Tennessee anglers. In addition to monitoring fish populations, TWRA biologists also monitor water quality and enhance habitat through the installation of structures to improve physical stability and complexity of the environment. As reservoirs age in Tennessee, much of the physical habitat that was present at impoundment is lost to natural degradation. Stands of trees eventually erode, and other structures such as roadbeds, rock walls, and natural outcropping can become covered by sedimentation.
Fish require water which is not only clean of pollutants that can be toxic to fish, but also contain chemical nutrients which are necessary to produce the microscopic plants, bacteria, and invertebrates that are the primary producers in the food chain that fish need to survive and grow. Temperature and dissolved oxygen also play a critical role in fish health. TWRA biologists monitor dissolved oxygen and temperature throughout the water column in reservoirs during the warm summer months. This information is used to determine the depth of the thermocline, as well as assess the suitability of the seasonal temperature and oxygen levels for predicting fish distribution and also growth and survival of recently hatched fish. In the unfortunate case of fish kills, the temperature/dissolved oxygen profiles often provide an understanding of the root cause of the kill.
Although sedimentation is a natural process that occurs within reservoirs, activities within the watershed have a profound effect on the rate of sediment which enters a reservoir. Suspended soil particles entering a reservoir can cause turbidity in the water column as well as settle out thus covering spawning habitat and other physical structures within a reservoir. Reduced water clarity from suspended inorganic particles can reduce the ability of sunlight to penetrate the water column, in turn, reducing the depth at which phytoplankton (i.e. microscopic plants) and can exist. These single cell microscopic plants are the beginning of the food chain and their abundance directly affects fish abundance. Reduced depth of sunlight also reduces the ability of larger rooted plants to grow. Monitoring land use practices and its effects on water clarity is an important component of reservoir fisheries management. Often measures are taken to stabilize shoreline areas and provide sediment traps before it can enter a reservoir.
The TWRA has attempted multiple projects to establish native aquatic plants. Many of these have been successful and are ongoing, while others have proved ineffective. Cypress tree plantings have been quite successful in many reservoirs and the established tree stands serve to trap sediment and stabilize shorelines. The roots on mature trees can also serve as nursery cover for small fish during times of inundation.
Shoreline cultivation of grasses has been used to stabilize shoreline and also provide nursery habitat. Grasses can be planted by harrowing and broadcasting or by hydroseeding, during winter months when lakes are drawn down to winter pool. Once the grass becomes established prior to inundation in the spring, they provide nursery habitat for juvenile fishes. The grasses eventually die back but not before providing cover for small fish early in their life cycle. Hydroseeding has been used recently on Boone reservoir to establish shoreline vegetation on the exposed littoral zone. In addition to future nursery habitat, this also serves to protect the exposed shoreline while Boone is being held at a low pool for several years for repairs to the dam.
Reservoirs in Tennessee range in age from almost 40 years to over 100 years old. As reservoirs age, natural woody cover such as standing timber are lost to decomposition. Other physical features such as rock walls and road beds also degrade with time or can become covered with sediment. To replace the intrinsic cover lost over time, TWRA biologist install fish attractors using both natural materials and artificial materials. An ongoing debate has been whether fish attractors simply attract fish or actually raise the net production of fish in a reservoir. In truth, all fish attractors probably have some degree of both of these benefits.
Natural materials include mostly woody debris, such as brush piles, trees, and wooden stake beds, to attract larger fish as well as provide cover for juvenile fish and prey fish. The advantage to natural materials is they are readily adapted by cover oriented fish species, they eventually decompose leaving no synthetic materials in the environment, and they are readily colonized by invertebrates providing a food source for juvenile fishes. As woody materials decompose they also provide food for bacteria and other microscopic organisms. The biggest disadvantage to natural materials is the need to replace the materials frequently due to degradation.
In addition to fish attractors made from natural materials, the TWRA also installs fish attractors made from artificial materials including plastic and concrete. The biggest advantage of these materials over woody debris is the longevity of the structure which can last for decades. Although not as easily colonized by aquatic invertebrates as woody materials, with time most plastic and concrete materials will become colonized with these important food items. The materials used are often dictated by availability and cost.
In addition to fish attractors made completely from either natural or synthetic materials, many of the installations are composites of both types of materials. These structures have the advantage of being readily colonized by invertebrates and juvenile fish while having a lifespan greater than natural materials alone.
Tennessee anglers often want to know if they are allowed to place their own fish attractors in public waters.
Fish attractor installations are allowed, but permits are required by either the Tennessee Valley Authority (TVA) or the United States Army Corps of Engineers (USACE), depending on which agency has operational jurisdiction over a given reservoir or river. Allowable materials and locations of angler-installed fish attractors are specified by the permits.
USACE:
For waterbodies regulated by the Army Corps of Engineers, the Resource Managers' office should be contacted for each specific reservoir.
Center Hill Reservoir
Cordell Hull Reservoir
Cheatham Reservoir
Dale Hollow Reservoir
J. Percy Priest Reservoir
Old Hickory Reservoir
Angler Surveys
Fisheries management in Tennessee is based on information collected with sound methodology using the most contemporary techniques available within the community of fisheries professionals. Although the methods we use for obtaining information are sound and proven, there is no way to circumvent the inherent variability common to biological data. It is, however, possible to validate our findings by comparing the results of multiple techniques. Commonly, we use angler surveys to complement fish community surveys.
Angler surveys rely on fishermen to provide information about a fishery, including effort, catch, preferences, demographics, and economics. The information we collect through angler surveys gives us an unbiased sample of the angling population that we use in addition to our fishery-independent assessments to select the best management plans to accommodate the widest variety of anglers.
Just as no single sampling method can be used to describe every fish population, no single angler survey method can adequately represent all anglers or all components of a fishing experience. We therefore use several angler survey techniques to gain a comprehensive picture of the sportfishing population in Tennessee. The methods are described below:
Telephone Surveys
The TWRA contracts annually with the University of Tennessee (UT) to do an annual random survey of licensed anglers.
A list of licensed anglers is provided to the Human Dimensions Research Lab at UT. From that list, a large random sample of anglers is contacted by telephone. The anglers are asked questions such as where they live, where they like to fish, the type of fishing they do, which species they like to fish for, and their satisfaction with fishing in Tennessee. The anglers are also invited to provide comments and suggestions concerning the management of Tennessee Fisheries.
The Advantages of this type of survey are:
Provides unbiased, randomly collected information about the entire angling population in Tennessee.
Low cost per interview
Good response rates
The Disadvantages Include:
Recall Bias - This means that an angler may be asked questions about a fishing experience that occurred weeks, maybe even months, before the interview. The angler may not be able to accurately answer all of the questions due to the passage of time.
A particular portion of the angling population may choose not to respond
On-Site Angler Creel Surveys
Each year, representatives from the TWRA approach anglers while they are fishing to ask them about their fishing experience that day. This process is known as a creel survey.
The "creel clerks" ask anglers questions about the amount of time they have been fishing, what they are fishing for, what they have caught or released, where they are from, and questions about how much money was spent on the fishing trip. The information obtained is very useful to TWRA fishery biologists to make informed decisions regarding the management of the state's resources.
Currently, the TWRA employs 11 full-time creel clerks who conduct creel surveys on 17 reservoirs throughout Tennessee. Annually, they collect between 10,000 and 15,000 interviews. In addition to reservoirs, various seasonal stream and tailrace surveys are conducted on an as-needed basis. The TWRA also contracts with the Tennessee Technological Institute from time to time to conduct specialized surveys where new research is the main focus.
The creel clerks may approach anglers by boat while they are in the process of fishing. This type of survey is known as a "roving creel survey". At other times, the creel clerk may wait at a boat ramp or pier to interview anglers at the completion of a fishing trip. This is known as an "access point creel survey". If you are approached by a creel clerk, please take a few minutes to respond to an interview. This process allows you to have a voice in the management of Tennessee's fishery resources.
Advantages of Creel Surveys:
No recall bias - anglers are not required to remember effort and catch from past fishing events
High response rates
Creel clerks are able to directly observe caught species. This allows for accurate identification and measurement of harvested fish.
Disadvantages of On-Site Creel Surveys:
It can be difficult to relate the information to the entire fishing population. For example, a reservoir creel survey would not represent stream or pond anglers.
High cost per interview
Online and Mail-In Tournament Surveys, BITE Program
The Tennessee Wildlife Resources Agency's BITE (Bass Information from Tournament Entries) program is a coordinated effort between the Agency and organized bass clubs that hold fishing tournaments in Tennessee.
Tournament organizers voluntarily submit their tournament data to the TWRA Fisheries Management Division via an online reporting form or a mail-in tournament report card. The information on the report form or card supplies information such as the location of the tournament, number of participants, total catch, and size and weight structure of the tournament catch. Annually, the information collected from tournament organizers is compiled into a report that benefits both the TWRA as well as tournament anglers.
The Advantages include:
Information about bass stocks is compiled for major reservoirs
Information about otherwise unknown tournament efforts is provided to biologists
Tournament anglers benefit by receiving information about bass tournament catches around Tennessee.
Disadvantages include:
Information is provided only for a very specific portion of the fishing population.
Catch, effort, and size structure may be proportionally greater than in the general fishing population
TWRA reservoir biologists spend many hours each year monitoring sport fisheries and forage fish communities. Because looking at the entire population of fish in a lake is virtually impossible, biologists must depend on sampling to get a snapshot of population status and make predictions about how it will look in the future. Different sampling methods (electrofishing, nets, trawls) are used to sample fish populations. Targeted species surveys may be conducted to obtain information about fish population size structure, recruitment, growth, density, and mortality.
Information gathered from sampling surveys is coupled with information about the human and habitat components of sport fisheries and used to make management recommendations for harvest restrictions and/or stocking. Hatchery managers also use these gears to collect broodstock from wild populations, which can be used in hatcheries to produce fish for stocking. The following section briefly describes sampling gear used by TWRA reservoir fisheries and hatchery staff.
Boat mounted electrofishers are used in Tennessee reservoirs to fulfill various sampling objectives.
Bass, crappie, and sunfish are highly vulnerable to this gear and surveys are normally conducted during the spring months.
A sampling design is chosen which reflects habitat diversity within a lake and fish are collected after being stunned by the shocking boat's electrical field.
Dip netters at the front of the boat pick up the fish and hold them in livewells for later analyses.
Gill nets are used for a variety of fish species that are difficult to sample with electrofishing gear.
TWRA uses them to collect sauger, walleye, white bass, striped bass, and Cherokee bass.
Most netting surveys are conducted during the winter months and may be targeted at pre-spawn runs.
Like other sampling methods gill net samples yield important insight into natural spawning success, success of stocking programs, and sizes of fish available to anglers.
Like electrofishing, seining is an active sampling method that allows biologists to look at forage availability, and survival of young sport fish.
Seines are really long, fine-meshed nets that are dragged through the water in shoreline areas.
Seine hauls have also been used by TWRA to evaluate stocking success of striped bass.
Often the work does not stop in the field for TWRA reservoir crews.
Fish samples often must be processed in the lab, species identified, and counted.
In addition, otoliths (ear bones) are routinely used by TWRA biologists to determine age structure and growth rates for sport fish populations.
Data must be entered into computer databases, analyzed, and summarized for reports.
The scenes below illustrate some of these activities.
Small Lakes and Ponds Management and Design
Good fishing doesn't just happen! A pond that consistently produces good catches of fish is a result of proper planning, construction, and management.
Tennessee has approximately 200,000 ponds and small lakes that provide over 100,000 acres of potential fishing water. In fact, these waters account for nearly one-fourth of all fishing trips made in Tennessee annually. Ponds and small lakes are often the "stepping stones" for Tennessee youngsters who later become dedicated anglers and conservationists. With proper planning and management, these waters have the potential to provide many enjoyable hours of good fishing.
A good pond depends on location, design, construction, stocking, and management. After the pond is completed, success or failure depends on the landowner's use of necessary practices to establish and maintain good fish populations. Recreational fishing in ponds and small lakes can benefit tremendously from a small amount of management effort. Proper stocking of the right species and number, a balanced harvest of mature fish, proper fertilization (if needed), water quality management, and aquatic weed control are basics that the pond/small lake owner should understand. Many unmanaged (or mismanaged) ponds could produce many more pounds of fish than they currently do if good management practices were followed.
Strategies for Stocking Fish
Although the stocking strategy you choose should be geared to the kind of fishing you want, for the best recreational fishing and table fare, the largemouth bass, bluegill, redear sunfish, and channel catfish (optional) are hard to beat in Tennessee.
New or renovated ponds must be properly stocked because the fish that are originally introduced represent the future sportfish catch and harvest for many years to come. Improper stocking seldom provides desired results. Except for supplemental stocking of channel catfish, a pond that already contains fish generally does not need to be stocked. Fingerling fish (2-4 inches) stocked into a pond that contains adult fish will become fish food. Only stock additional largemouth bass or sunfish if recommended by a fisheries biologist.
Moving fish from your neighbor's pond or a local lake to your pond is not recommended. Many sunfish species are similar in appearance. You could mistakenly stock sunfish that are not desirable in small ponds. Also, there is a good possibility of transmitting fish diseases from pond to pond.
In general, sunfish (bluegill/redear) are stocked in the fall and winter months. Bass are stocked the following spring. The timing is not as critical with catfish and hybrid sunfish combinations, but fingerling survival is always best when fish are stocked into cool water.
Stocking Combinations
Number of fingerling fish per acre, for stocking new or renovated ponds without an existing fish population:
Largemouth bass and bluegill at 75-100 bass/acre and 500 bluegill/acre.
Largemouth bass, bluegill, and redear sunfish at 75-100 bass/acre, 400 bluegill/acre, and 100 redear sunfish/acre.
Largemouth bass, bluegill, and channel catfish at 75-100 bass/acre, 500 bluegill/acre, and 50-75 catfish/acre.
Largemouth bass, bluegill, redear sunfish, and channel catfish at 75-100 bass/acre, 400 bluegill/acre, 100 redear sunfish/acre, and 50-75 catfish/acre.
Channel catfish only at 100-150/acre.
All of the above combinations, except catfish only, must be stocked in ponds larger than 0.25 acres, and preferably in ponds 1 acre or larger. Channel catfish can be stocked alone in smaller-sized ponds at 100-150 per acre, without supplemental feeding.
Stocking hybrid sunfish can offer a good alternative for owners of very small ponds (less than 0.25 acres) up to ponds 3 acres in size. However, it is important for the owner to know that certain conditions are critical and need to be met for the success of ponds stocked with hybrid sunfish. First, do not stock hybrid sunfish in ponds containing other fish, and never stock them in combination with other bream(bluegill and redear sunfish) species. The reason for this is that [redear sunfish] hybrid sunfish will cross-breed with other bream species, and hybrid identity and vigor will soon be lost. Second, hybrid sunfish should always be stocked in combination with a predator fish, such as a largemouth bass or catfish, to control both the small amount of expected hybrid sunfish reproduction (which is not desirable) and wild fish that may accidentally get into the pond. In either case, more food will be available for the stocked hybrids.
It is important to remember that hybrid sunfish management is for the production of large sunfish, and bass growth will be less than desirable. Also, periodic restocking of hybrid sunfish will be necessary to sustain the fishery for more than a few years. The recommended initial stocking rate is 750 hybrid sunfish and 30 largemouth bass per acre, or 400 hybrid sunfish and 100 catfish per acre. Pond owners should keep records of the number of hybrid sunfish removed and, if possible, restock with 3 to 4-inch hybrids when 60 to 75 percent of the original stocked fish have been caught and removed.
Information about Grass Carp
White amur, commonly called grass carp, is another fish species that may be stocked into ponds that have aquatic plant problems. Grass carp feed almost exclusively on aquatic plants and, therefore, can be an effective biological control method when aquatic plants become a nuisance.
Although aquatic plants are beneficial to natural functions in fishing ponds and lakes, they can sometimes interfere with the owner's preferred use of the pond when allowed to spread unchecked. Triploid grass carp may be stocked with other fish species at recommended rates and may be obtained from commercial fish producers. Only triploid (sterile) grass carp are legal to stock in Tennessee.
No special permit is required of the pond owner to stock grass carp at this time, but pond owners should obtain verification from the sellers that they are purchasing triploid grass carp. For more information, including stocking rates for grass carp, see the Aquatic Weed Control - Biological Control section of "Managing Small Fishing Ponds and Lakes in Tennessee".
