10 History of Fish Management 



However, a team of fishery biologists, employed by the Tennessee Valley 

 Authority to investigate the fish populations of TVA reservoirs,^^' ^^ con- 

 cluded that there was insufiicient evidence to substantiate this belief. 



Fish Cycles in Reservoirs 



The work of the TVA in this direction was strengthened by the studies 

 of others, and, in time, biologists, who had seen fishing in a number of 

 new water-supply reservoirs change from excellent to very poor in a 

 matter of a few years, were ready to predict a reservoir fishing cycle; ^ 



"At the first spawning season (May-June) after the reservoir is filled 

 and stocked with fish, the young of largemouth bass will be very 

 abundant. These will grow rapidly to legal size and produce excellent 

 bass fishing for about three years. Moderate numbers of young crappies, 

 bluegills, and other sunfish and bullheads may be produced during the 

 first spawning period. These will grow rapidly to large average sizes and 

 add to the excellence of fishing. 



"Carp, buflFalo, and suckers, as well as some other fish present in the 

 stream flowing into the impoundment will move into the lake in small 

 numbers and produce some young the first season. 



"During the first few years the reservoir will be clear except immediately 

 following heavy rains, and the recreational attractions other than fishing, 

 such as swimming and boating, will be at their maximum. 



"Reduced recreational values will be apparent in about the length of 

 time that the original spawn of bass survives ( usually four to six years ) . 

 By this time the bass fishing will be largely gone. Crappies and bluegills 

 will be present in such large populations that they will have become 

 small, stunted and unattractive to fishermen; carp and other rough fish 

 will have multiplied so successfully that their bottom-feeding activities 

 will continually stir up the bottom mud. The lake will remain turbid 

 throughout the year, regardless of periods of dry weather, and will have 

 lost much of its attractiveness to fishermen and bathers. Many of the 

 aesthetic values of boating will be gone. The conditions will be entirely 

 the result of changes in the relative abundance of certain fishes, and as 

 the primary function of the reservoir is to supply water, and not recreation, 

 almost nothing can be done to bring back conditions that were obtained 

 in the early years of impoundment." 



As a result of investigations of small impoundments not used for water 

 supply, many examples were available by 1946 to show that the chemical 

 treatment or the draining of such small impoundments to remove un- 

 desirable populations (such as those that developed in water-supply 

 reservoirs) entirely eliminated "aquatic desert" conditions, and that 

 once tliese impoundments were restocked with desirable fish they did 

 become very productive. Thus, the theory of Ellis ^^ that high fish produc- 



