146 The Ohio Journal of Science [Vol. XX, No. 5, 



migrate and by the abundance of its food supply. Conse- 

 quently it may be found anywhere in moderately shallow 

 water. Later its food consists mainly of insect larvae. These are 

 more apt to be found in localities with considerable vegetation 

 and it may be that the slightly greater numbers and larger sizes 

 of the fry are found in places containing vegetation because the 

 change in food drives them from the clean beaches where insect 

 larvae are few to the richer vegetation-bearing shallows. 



As regards the fish associates of the young perch, there are 

 none that put any serious obstacle in the way of its existence. 

 The only adults taken in the same habitats were carp, sunfish, 

 minnows, brook silversides, several species of darters, and an 

 occasional white bass or small-mouthed bass. None of these 

 are fish eaters to any great extent except the basses and only 

 seven adults were taken in the forty- two localities. An exam- 

 ination of the stomachs of three of these showed only a small 

 fish content. Considering the other fish fry with which the 

 young perch is associated, the small-mouthed bass, large- 

 mouthed bass, white bass, sunfishes, log perch and minnows — 

 there are none which are pisciverous to any extent. The 

 largest fry of the small mouthed bass were eating the very 

 young fry of other fish, but these were mainly the fry of min- 

 nows and darters. The young perch keeps pace with the small- 

 mouthed bass in growth so that it is doubtful if the young 

 small-mouthed bass ever becomes a menace to the young perch. 

 All the young fish mentioned are using the same food 

 (Entomostraca) at this time and so are in a sense competitors 

 but the waters examined swarmed with Entomostraca so that 

 all the young fish were abundantly supplied. 



In point of numbers the young perch fry were surpassed by 

 the fry of the small-mouthed bass and of the log perch in a 

 ratio of about four to one while the young minnows were most 

 abundant. Locally, the young brook silversides, white bass and 

 sunfish were more abundant than the perch, but they, like the 

 fry of the rock bass, small-mouthed bass, fantailed darter, 

 Diplesion blennioides and miller thumb had a local distribution. 



The association and constant occurrence of the young of the 

 four species, minnows, small-mouthed bass, log perch and perch 

 may be attributed to three causes: (1) A wide distribution of 

 the adults. (2) A generalized food habit with a general distri- 

 bution of the food supply. (3) A generalized type and large 

 number of breeding places. 



