-23= 



compared for the sunfisheSj but less complete records obtained by seining 

 other ponds confinned these general proportions. The data show a higher 

 average weight of young bass in intermediate ponds than in the clear ponds. 

 It is of course impossible to separate completely the various causal factors 

 in such returns. It is possible that the intermediate turbidities may in 

 some way favor the reproduction and/or survival of bass,^ as has been suggested 

 by Doan (1941) for sauger^ In this instance, however, competition from the 

 companion sunfishes in the manner described by Bennett (1954) is believed to 

 have had an important influence on the yield of bass since the weights and 

 numbers of young sunfishes were vastly greater in the clear than in the in- 

 termediate ponds. 



An attempt was made to determine the level of turbidity above which 

 reproduction became severely restricted. The exact level of course was not 

 determinable because such factors as age of pond and condition of the bottom 

 seemed to have additional influence „ It was observed, for instance, that newer 

 ponds with firm^ unsilted bottoms produced young at higher average turbidities 

 than older ponds having soft^ silt-laden bottoms. The greater fertility 

 common to new ponds was undoubtedly an additional factor,, The accuracy of 

 the determination was further limited by the fact that turbidities of individ- 

 ual ponds varied considerably from time to time, A completely accurate deter- 

 mination could be made only by use of completely controlled conditions and 

 by observing the turbidity at the exact time of spawning. Since dates of 

 spawning were not observed and since they undoubtedly varied from pond to 

 pond, particularly for the sunfishes, the average turbidities compiled over 

 the two year period are believed to offer the most reliable basis for this 

 determination. Upon this basis, the critical level appeared to lie between 



