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FINDINGS FROM TIE FARM PONDS 



Relation of Turbidity to Total Yield 



Turbidity was found to have a definite relation to total production of 

 fishes. The clear ponds yielded not only a much greater weight of fishes 

 but also greater numbers of large fishes. This presentation is limited to 

 those ponds for which total population estimates were made at the end of the 

 second growing season. Production figures for individual ponds are presented 

 in Table 2 together with the weights and percentages of separate components 

 of the populations. The correlation between yield in pounds of fish per acre 

 and turbidity was -0.762, which was significant at the .01 level. The re- 

 gression of yield on turbidity was P = 142.1 -0.502A, where P = pounds of 

 fish per acre and A = average turbidity in parts per million. 



By way of further analysis, the 12 ponds were separated into the following 

 three classifications of turbidity: 1) clear ponds, with average turbidities 

 of less than 25 ppm; 2) intermediate ponds, with a range of turbidities from 

 25 to 100 ppfti; and 3) muddy ponds, with turbidities in excess of 100 ppm. It 

 may be seen in Table 2, and graphically in Figure 1, that the average total 

 weight of fishes in the clear ponds was 161.5 poxinds per acre, as compared 

 with 94 in the intermediate and only 29.3 in the muddy ponds. The differences 

 were due to faster growths made in the clearer waters and to the vastly greater 

 amoiints of reproduction in the clear ponds, particularly by the bluegill and 

 redear sunfish. 



Estimates were also made of the numbers and weights of the different 

 sizes of fish produced in the three categories of ponds. Table 3 shows that 

 for bass of desirable length (10 inches or longer), the muddy ponds yielded 



