Turner and Kraats. — Food of Large-Mouth Bass 377 



throughout the summer in the same locahties with the bass; 

 and likewise Amphipoda and Entomostraca, of apparently the 

 same or very similar kinds, were generally present. Yet the 

 young bass consumes largely first one, then another, and later 

 still another of these foods. It might be urged that the bass 

 is by nature a selective feeder, choosing certain definite kinds 

 of food. But this would not furnish adequate reason for a 

 definite change in diet. The young bass is not a random 

 feeder, on the other hand, otherwise the stomach contents 

 would offer more promiscuous collections of food. Neither 

 is there any marked change in habit or mode of living that 

 would correspond to the periods of change in diet. 



The results of a careful study of the lengths of the chief 

 different articles of food, together with the lengths of the 

 young bass, are shown in Table 2. 



It seems that the size of the food as compared with the 

 size of the bass is the most important factor. It is likewise 

 the same factor which brings about a change in the diet later. 

 It will be noted from Table 2 that the 10-15 mm. bass eat 

 Cladocera which average only .35 mm. in length and that 

 with an increase in size of the fish, larger species of Cladocera, 

 such as Daphnia and Camptocercus and others, are eaten. The 

 same general correlation is shown in the size relationship of 

 the Copepoda and of the midge larvae. Some very minute 

 amphipods appear in fish 12 mm. in length, but in 45 mm. 

 fish the average is 4.31 mm. The table shows that in bass 

 45 mm. in length the average size of all food animals is ap- 

 proximately 4 mm. to 4.5 mm. Corixa have not been taken, 

 up to this time, although they were present abundantly in 

 the waters. The species is one in which the adult is only 

 about 4.5 to 5 mm. long; a number of old nymphs, 4 mm, 

 long or slightly longer, were found in the food. 



Corixa nymphs and adults become important in the food 

 of fish 45 mm. in length and upward, and it seems reasonable 

 that the bass turned to them at this stage because it had at- 

 tained a size when 4 mm. animals were not too large to be 



