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a sample of 142 fish., That only the larger fish were being sampled is strongly 

 suggested; however, the same age distribution was common to all types of samples, 

 including those taken by rotenone. The explanation must be that each successive 

 year class was smaller than the previous so that its size was small or large 

 as compared with a more abiindant, previous year class, or a smaller succeeding 

 year class . 

 ■^ By 1955 the population had assumed a more normal structure due to a greater 

 spawn of white crappies in 1954 than in previous years. Of the total of 74 fish 

 aged, 56 were of the 1954, 8 of the 1953, and 10 of the 1952 year class » However, 

 the 1954 year class was by no means large and gained its prominence only due to 

 the weakness of the preceding year classes » 



From the small numbers present in Heyburn, as compared with populations in 

 other reservoirs, one would not consider the lake as overpopulated by this species. 

 With consideration of the slow growth, however, one must assume that the numbers 

 exceed the supply of food and/or other requirements, vAich is, in effect, over- 

 population. It is therefore extremely doiibtful that the white crappie will ever 

 assume any importance to the Heyburn angle r« 



The black crappie is rare and of no significance in the Heyburn fishery. 

 Known to have little affinity for turbid conditions, the species will probably 

 disappear completely in future years. The situation was again different at 

 Upper Spavinaw„ Black crappies greatly outnumbered the white, and collections 

 of both species during both years consisted chiefly of yearling individuals, 

 rather than older fish. Wire trap catches in 1954 indicate the relative 

 abundance of the two, wherein 136 lifts yielded 1,110 black crappies and only 

 124 white crappies. 



