American Fisheries Society 199 



at least the shallower parts of the pondweed zone seemingly 

 at all times. Three species of sunfish were also common 

 here, which in the order of their seeming abundance were : 

 bluegill (Lepomis pallidiis), common sunfish (Eiipotnotis 

 gibhosus), rock bass (Ambloplites rupestris), and blue- 

 spotted sunfish (Lepomis cyanellits). Black bass (Microp- 

 terus salmoides) were frequently seen and a number were 

 taken in our nets. The zone is undoubtedly the chief dwell- 

 ing place of this species in this lake. Darters of each of 

 the three kinds taken by us in Walnut Lake appeared to be 

 much more common in the pondweed zone than on the 

 shoals. Other fish that were present in the pondweed zone 

 at least at times but about which we obtained little infor- 

 mation as to their numbers were : wall-eyed pike, white 

 sucker, yellow catfish {Ameiurus natalis), common bull- 

 head (Aineiurus nebiilosus) , common pike (Esox Indus), 

 and whitefish. 



The importance of this zone as a fish habitat makes a 

 study of the interrelations of the fixshes in it well worth 

 considerable investigation, but on this subject we got little 

 definite information. The food of nearly all of the fishes 

 taken was examined to find the organisms for which they 

 were seeking. These appeared to be chiefly midge larvae 

 and pupae, May-fly larvae {Hexagenia and Heptagenia), 

 entomostracans, caddice worms, Sialis larvae, and crayfish 

 during April and May when most of the collecting in the 

 pondweed zone was done. Perch appeared to be feeding 

 mainly upon these immature midges and upon entomostra- 

 cans. The smaller-mouthed sunfish, bluegills and common 

 sunfish, were eating largely insect larvae, principally those 

 of May-flies, while the large-mouthed sunfish, the blue- 

 spotted sunfish, and the rock bass seemed to be feeding 

 almost entirely on crayfish. The few specimens of the 

 larger predaceous fishes examined, wall-eyed pike, common 

 pike, and black bass, had been eating perch. Although 

 there were many minnows in this region, we obtained no 

 evidence that they were ever fed upon by any of the other 



