Norris Reservoir Striped Bass Controversy in Tennessee.


The striped bass "success story in freshwater reservoirs" has not been without controversy.
In several states, anglers have suspected that the stripers feed on native gamefish and / or over compete with them for food despite scientific evidence they do not.

Biologists and fishermen alike became worried about these huge fish eating black bass and other game fish.
Biologists at several universities and state and federal agencies quickly determined through repeated scientific experimentation that this was not the case.

In Tennessee and elsewhere study after study revealed that striped bass in
reservoirs preyed almost exclusively on gizzard and threadfin shad.

 (D. petenense) (Stevens1958; Kohler and Ney 1981; Moore et al. 1985).

One of the hottest controversy was on Norris Reservoir in Tennessee.
The reservoir was dammed in 1939 and experienced the normal explosion in fish after impoundment, but 15 years later, fish populations showed a dramatic decline.

Striped bass have been stocked in over 100 reservoirs
in the southern United States since the 1970s.

Originally, they were native to the coastal waters
and rivers from New England to Florida
and in the northern Gulf from the Florida Panhandle
 to eastern Louisiana.

 Many reservoirs develop very large
populations of shad, especially gizzard shad,
that grow too large for largemouth bass to eat.
Striped bass grow large enough to eat these shad
and are open-water fish, as are shad.

With that realization, the boom
in stocking striped bass
in reservoirs began.

Such a decline is normal in most reservoirs, but in Norris, it was dramatic. In the 1940s, saugers were so plentiful that biologists suggested allowing anglers to use gill nets to catch more of them. By 1975, the sauger fishery was considered "insignificant." Walleye, black bass and crappie (sac-a-lait) also declined. Anglers concerned with declining gamefish populations met with Game and Fish Commission biologists in 1970 to express their concern.

 Before that meeting in 1966, striped bass stocking began at a rate of almost 9 fish per acre. The stocking rate was increased to 14 stripers per acre in 1975, and to 30 per acre in 1991.

In the meantime, angler concerns increased. In 1988, another meeting was held with the Tennessee Wildlife Resources Agency (TWRA) to express more concern. In response, TWRA reduced crappie limits to 20 per day and began stocking crappie. However, bass and crappie populations didn't improve and fishermen's concerns were giving way to anger with TWRA.

Agency biologists cited many studies that showed that striped bass in reservoirs feed almost totally on shad, and they formed a task force of biologists and interested parties to work on the issue.

However, most of the decisions of the task force were pushed by TWRA biologists, and in 1994, fishermen convinced that stripers were the cause of the decline in other gamefish, formed the Tennessee Sportsman's Association (TSA), with over a 1,000 dues-paying members. Concerns expressed over 20 years before hardened in anger that made compromise very difficult. TSA conducted an anti-TWRA campaign, involving the press, billboards and bumper stickers.

In 1995,  TSA was behind two bills in the legislature that would have stopped striped bass stocking and lifted all limits on their catch.
Both bills failed, but in 1995, TWRA put a moratorium on striped bass stocking.

In 1996, three more such bills were introduced.

Again, the bills failed.

The Wild Turkey Federation, the Tennessee Striped Bass Association, Quail Unlimited, the Tennessee Smallmouth Bass Association, and the Tennessee Conservation League all campaigned that fish and wildlife management decisions were best left to biologists, not politicians.

The politicians agreed.

Mississippi State University Striped Bass Study

In 1996, TWRA commissioned a study by "out-of-state" Mississippi State University biologists on striped bass interactions with other fish in Norris Reservoir.

Their report stated that striped bass preyed very little on other gamefish in the reservoir during the period of their study.

After the study, TWRA formed the Norris Lake Fishery Advisory Committee, composed of equal members from all fisheries interests. The group developed a plan that included resuming stocking of stripers at a reduced rate, increased stocking of walleye and crappie, created more stringent limits on largemouth bass, smallmouth bass, and sunfish, and more liberal limits on spotted bass.

Although fisheries management in the reservoir is still controversial, some of the controversy has eased because the close involvement of all user groups by TWRA. The Norris Reservoir conflict is seen as justifying the need for fish and game management agencies to pay more attention to the human part of modern fisheries management.

Source: Angler Conflicts in Fisheries Management:  Case Study of the Striped Bass Controversy at Norris Reservoir, Tennessee. T.N. Churchill, P.W. Bettoli, D.C. Peterson, W.C. Reeves and B. Hodge. Fisheries. Vol 27, No 2. American Fisheries Society. 2002 

See Full Report
Angler Conflicts in Fisheries Management: A Case Study of the Striped Bass
Controversy at Norris Reservoir, Tennessee Fisheries Management

Effects of Simulated Removal of Striped Bass from a Southeastern Reservoir

Scott W. Raborn, Leandro E. Miranda, and M. Todd Driscoll

Mississippi Cooperative Fish and Wildlife Research Unit, Post Office Box 9691, Mississippi State, Mississippi 39762, USA

Abstract.—Since the introduction of striped bass Morone saxatilis and hybrids of striped bass and white bass Morone chrysops into reservoirs, much concern has been directed at the possibility of these predators competing with other sport fishes for limited prey.

 If density of striped bass is reduced or eliminated through modifications of the stocking program, the prey not consumed by striped bass may be shifted to other sport fishes.

The resulting increase in biomass of other sport fishes would be a function of the amount of added prey, the percent of this additional prey eaten by other sport fishes, and the efficiency with which the prey is converted into biomass.

We used bioenergetics models to estimate annual striped bass prey consumption in Norris Reservoir, Tennessee.

Total annual consumption was estimated at 52 kg/ha (estimated range = 17–100 kg/ha), clupeids accounting for the majority (94%), followed by lepomids (4%) and other food items (2%).

Existing biomass of black basses Micropterus spp., crappies Pomoxis spp., and percids Stizostedion spp. was about 65 kg/ha (estimated range = 35 − 106 kg/ha).

Given the complete removal of striped bass, modeling indicated that the most probable increase in the biomass of these sport fishes would be about 3% with a 75% probability that it would be less than 12%.

Thus, not even the complete removal of striped bass would measurably increase the biomass of other sport fishes.


MSU Study Findings:
 The MSU study (Miranda et al. 1998) made several important findings.

  1. Predation by striped bass on game fish in Norris Reservoir was deemed negligible during the study period.

  2. Direct competition between striped bass and other game fish was also negligible in Norris Reservoir during the study period.

  3. Potential did exist for competition between striped bass and other predators during periods of low forage abundance at the density of striped bass observed during the study.

  4. MSU researchers concluded that low forage abundance may become critical after winter shad kills which have occurred periodically throughout the history of Norris Reservoir.  It was possible that striped bass would compete with other game- fish for food after periods of winter shad kills.

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