52 UNIVERSITY OF WISCONSIN STUDIES 



copepods. The carp is an omnivorous feeder. Other fishes 

 which show a rather varied diet are top minnow, bluegill, the 

 two species of black bass, a shiner (Notropis heterodon), bream, 

 and blunt-nosed minnow. The yellow perch relies chiefly on 

 three common foods: immature insects, cladocerans, fishes. 



There were several species which showed considerable ability 

 to change their foods with different environments. It is hard 

 to understand why the rock bass ate many crayfishes in all the 

 lakes except Geneva, where crayfishes were most abundant 

 (Tables II-V). In Lake Michigan the black bullhead ate largely 

 of crayfishes, but in Pepin took a variety of foods. The yellow 

 bullhead ate fishes or crayfishes. The ciscoes in Lake Michigan 

 ate Mysis and Pontoporeia, but in Lake Geneva, where Mysis 

 probably does not occur, they were filled with cladocerans, and 

 in Lake Mendota had partaken largely of immature insects. 

 The shiners of the genus Notropis showed differences in food 

 habits in different lakes. In Lake Pepin they fed largely on 

 cladocerans, but in Green, Mendota, and Michigan had turned 

 to immature insects. The white bass in Lake Pepin ate clado- 

 cerans and fishes, but in Lake Mendota fed on adult insects. 





