DeRyke and Scott 



43 



Labidesthes sicculis Cope. (Skipjack) — Table XVI. 



The foregoing tables indicate at a glance that the greatest variety of 

 food has been taken in the region of the heavy vegetation. We find general 

 gains in heavy vegetation in the use of entomostraca, snails, and plant tissue. 

 There has been a loss in the per cent using beetle larvae and may-fly larvae, 

 while the per cent using the other insect larvae remains about the same in 

 both scant vegetation and heavy vegetation. The use of insects remains 

 about the same in both. A decided decrease in the use of amphipods and 

 cray-fish has occurred among the fish in heavy vegetation. 



It is interesting to note that the gains made in the use of particular foods 

 are all gains in use of food which is dependent upon the plants for their 

 food. This suggests that the fish are not extremely selective in food habits 

 but avail themselves of the food present at a particular time in their en- 

 vironment. In this respect we may note that the bluegills when feeding among 

 scant vegetation have the per cent using mites (an undesirable food) about 

 doubled. 



Labidesthes sicculus (skipjack) also shows remarkable corroboration of 

 this statement. Among the scant vegetation not one has taken insect larvae 

 or snails, but the percentage of those eating these foods among the heavy 

 vegetation is rather high. However, they do show a degree of selection in 

 foods where an abundant supply of many kinds exist. They seem to choose 

 foods suitable to their needs from the foods present. As an example of this 

 we find where there are perch and common sunfish in the same environment, 

 the sunfish live almost wholly on snails while the perch depend upon other 

 available foods. The selective food habits of the perch have been ably dis- 

 cussed by Pearse and Achtenbery ('17 and '18). 



INFLUENCE OF BOTTOM ON FOODS UTILIZED 



The following- tables have been arranged to show the per cent of fish 

 eating a particular food on a sand or marl bottom as compared with the 

 per cent of fish eating the same food on a mud bottom. 



Perca flavescens Mitchill. (Yellow perch) — Table XVII. 



