18 UNIVERSITY OF WISCONSIN STUDIES 



DISTRIBUTION OF FISHES IN LAKE GENEVA 



Lake Geneva is the clearest of the lakes studied in Wis- 

 consin (Table I). Its shores are for the most part rocky and 

 steep. There is comparatively little aquatic vegetation. 



Table V gives the results of catches with gill nets at various 

 depths in Lake Geneva. Of the eleven species caught, six did 

 not extend below a depth of fifteen meters: common sucker, 

 pickerel, pumpkinseed, bluegill, largemouth black bass, brook 

 trout. The rock bass and wall-eyed pike ranged down to 20 

 meters; the smallmouth bass to 25 meters; and the perch to 35 

 meters. The cisco was caught at depths of 15 to 25 meters. It 

 will be noted that there were twice as many fishes caught from 

 five to ten meters below the surface as were caught between the 

 surface and a depth of five meters. There are probably a num- 

 ber of factors contributing to this peculiarity in distribution, but 

 doubtless it is due chiefly to the rocky shores and the clearness 

 of the water. The rocks make it difficult for plants to gain a 

 foothold, and the clearness of the water makes it possible for 

 plants, which are much frequented by fishes, to grow at greater 

 depths. 



Judged by the catch per hour in gill nets the abundance of 

 the eleven species was as follows: Perca flavescens, .977; Am- 

 bloplites rupestris, .781; Micropterus dolomieu, .589; Leucichthys 

 artedisisco, .279; Stizostedion vitreum, .252; Catostomus commer- 

 sonii, .171; Esox Indus, .129; Eupomotis gibbosus, .058; Lepomis 

 incisor, .022; Micropterus salmoides, .010; Sahelinus fontinalis, 

 .009. 



The absence of fishes in deep water is doubtless due to lack 

 of oxygen. Birge and Juday (1911, p. 148) on September 25, 

 1906 found about .5 c.c. or less of oxygen per liter below 30 me- 

 ters, and (p. 230) that there was little plankton in the deeper 

 water. There is no doubt that there was a lack of oxygen in the 

 deeper water while the writer was fishing in Lake Geneva dur- 

 ing August, 1920. 



A trot line was set on six nights in favorable places along the 

 shores of Lake Geneva. A total of 504 2/0 Kirby hooks caught 

 one rock bass. 



Nine hauls were made with the seine over a total of about 

 1,940 meters of shore. The following fishes were caught, the 



