Mar., 1920] Food and Fish Associates of Young Perch 151 



the bottom. The young fry of two fish which are strictly bottom 

 feeders (Etheostoma flabellare and Cottus ictalops) were taken 

 with the young of the perch and their diet consisted mainly of 

 large larvas of insects, fish eggs, and amphipods while the young 

 perch were eating only entomostraca and a few chironomid 

 larvse. The young perch were clearly not deriving their food 

 from the bottom at this time. Consequently it seems that the 

 change in the behavior of the perch fry as it changes from a 

 generalized feeder to a bottom feeder contributes to the change 

 in the diet. 



6. Summary. 



1. The young perch of from 26 to 50 millimeters in length is 

 found generally distributed in the shore waters at a depth of two 

 to five feet in July in the vicinity of the Bass Islands, 



2. The diet of the young perch consists wholly of copeopds in 

 its younger stages but gradually changes to insect larvas. 



3. The change in diet is apparently associated with a 

 change in feeding behaviour, changing from a generalized or 

 surface feeder to a bottom feeder. 



4. The young perch is associated at this time with a great 

 number of the adults of minnows, several species of darters 

 (Percina caprodes zebra, Cottogaster coplandi, Diplesion blenni- 

 oides, and Etheostoma flabellare) a few adults of rock bass, 

 small-mouthed bass, white bass, sunfish, perch and brook 

 silversides and with the fry of the small-mouthed bass, 

 large-mouthed bass, rock bass, sunfishes, darters (Percina 

 caprodes zebra, Etheostoma flabellare), minnows, brook silver- 

 sides and perch. 



5. The perch fry studied here have few enemies among their 

 fish associates. 



