NOTES ON THE FOOD AND PARASITES OF SOME FRESH-WzVTER- 

 JISHES FROM THE LAKES AT MADISON, WIS. 



By William S. Marshall and N. C. Gilbert. 



The following observations regarding the food of some of our fresh- 

 water fishes and the parasites living on or within them were nearly all 

 made during the spring, summer, and autumn of 1902 and 1903. The 

 fishes were examined principally for their parasites, but in connection 

 with that examination it was decided to note the food contents of each, 

 since this could easily be done after the fish had been opened for para- 

 sites. The work originally planned was much more extensive than the 

 following notes would indicate, but the removal of one of us from 

 Madison brought it to an end before very much had been accomplished. 

 Doubting that there would be opportunity to continue and complete 

 the work as it had been laid out, it was thought best to publish the 

 following notes, although Imt very few specimens of some species of 

 fishes have been examined. The stomach contents were not kept, and 

 we have only our original notes to refer to, wliich makes impossible a 

 more exact determination of all we found. 



The lakes from which the fishes were taken are adjacent to JNIadi- 

 S9n. Lake Mendota, the largest, bordering in part on the University 

 grounds and being thus easy of access, furnished the most of our 

 material. Lakes Monona and Wingra were both visited, but only a 

 comparative!}^ small number of fishes was taken from either. A few 

 of the black bass were sent to us from Round Lake, Washburn County, 

 Wis. 



The fishes were in part caught with hook and line, })ut the greatest 

 number were taken with a trammel net. A map of Lake Mendota 

 was platted so that w^e could record quite accuratch' the part of the 

 lake from which each fish was taken, this information to be used in 

 determining what difl^^erences, if any, the bottom, plants, depth, etc., 

 made upon the food of the fish and, through the food, upon the kind 

 of y^arasites found. Our notes have been caref ull}^ examined with this 

 in view, but without any definite results, the fish from one part of the 

 lake averaging, as a rule, the same as the fish from any other part. 

 This does not, however, hold true for perch caught near the shore 



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