-37- 



have been insignificant and to have had no important influence on the experiment, 



The presence or absence of carp had little influence on total weight of 

 the companion fishes. Considering only the 11 turbid ponds (Table 7)^ the aver- 

 age weight of bass, bluegills and channel catfish combined was 97 pounds Y^er 

 acre in the carp ponds and S2 pounds per acre in the ponds without carp. The 

 greater weight in the carp ponds was due to a greater weight of channel catfish 

 and young bluegills, which more than compensated for a smaller weight of bass 

 and adult bluegills. Considering the species separately, the carp exerted 

 varying influences. Growth of bass and adult bluegill was less in the carp 

 ponds than in the turbid ponds without carp, in spite of their lower average 

 turbidity. Total weight of bass was also less in the carp ponds, but total 

 weight of bluegills was greater due to the abundance of young produced in the 

 carp ponds- Channel catfish production averaged higher in the carp ponds than 

 in either the clear or the turbid ponds without carp, due to the much higher 

 survival (75 percent, as compared with 35 in the clear, and 47 in the turbid 

 ponds without carp)o The evidence that the presence of carp in some way en- 

 hances the production of catfish is too strong to ignore. The beneficial 

 influence may be due to the elimination of aquatic weeds by carp and/or their 

 reduction in numbers of aquatic insects known to prey on young catfish. The 

 greater yield of young bluegills in the carp ponds may have been brought about 

 in the same way. 



Weight gains by carp had no apparent relation to turbidity within the 

 rather small range of turbidities created. As might be expected, the gains 

 were generally proportional to the initial weight of carp stocked (Table 9). 

 The small gains in weight made by carp in ponds 15 and 16 suggests that the 

 initial weights stocked were near the carrying capacity of these ponds for 



