27] STUDY OF SOUTHERN WISCONSIN FISHES— CAEN 27 



caught in winter by fishermen working through the ice, along with ciscos, 

 from which they apparently were not distinguished. The weight at this 

 time was four and five pounds. During the few years following, the original 

 planting was entirely caught out, and there is no evidence of the whitefish 

 ever having reproduced while in the lake. The writer has examined many 

 thousands of ciscos caught in this lake during the winters but has never 

 seen any sign of the whitefish. It is concluded that the species has become 

 extinct. The inland lakes of southern Wisconsin are not of sufficient depth 

 or coldness to accommodate whitefish, the thermocline forcing the deep 

 (and therefore cold) water species into near-surface water of a temperature 

 too warm for their existence. 

 4. Leucichthys arledi (Le Sueur). Cisco. 



The cisco, a deep water fish, is confined to those bodies of water having 

 a considerable depth. I have taken ciscos from the following lakes: Lac La 

 Belle, Fowler, Oconomowoc, Okauchee, North, Pine, Nagawicka, Upper 

 and Lower Nashotah, Upper Nemahbin, Golden and Dutchman's. Of 

 these, La Belle, Oconomowoc, Okauchee and Pine contain the species in 

 the greatest abundance at the present time. Lower Nashotah and North 

 lake ciscos average the largest in size, while Pine lake is literally full of 

 small ciscos averaging not over a fifth of a pound. In the other lakes 

 mentioned, the numbers are not great. When cisco fishing first began, the 

 average size of the catch was somewhere around two and a half pounds 

 each; today a cisco weighing a pound causes a sensation and is an object 

 of admiration. As a result of observations during winter fishing over a 

 long period of years, I come to the conclusion that Oconomowoc lake alone 

 yields not less than 40,000 ciscos each winter. 



The cisco normally inhabits the deepest and coldest parts of the lake. 

 With the formation of the thermocline, however, the fish are forced up 

 from the depths into water uncongenially warm. During exceptionally hot 

 summers the fish are forced into water so warm that they can not adjust 

 to it, the result being "epidemics" of dead fish, during which seasons 

 literally thousands of ciscos perish in each of the lakes so affected. I have 

 witnessed this in Oconomowoc, Pine and Okauchee lakes during the last 

 six years. The summer of 1925 witnessed such an epidemic in Okauchee 

 lake. On September 1 I counted 72 dead ciscos on ten feet of shoreline! 

 The entire lake shore was strewn with dead fish, and after a careful survey, 

 an average of two and a half fish per foot of shoreline was estimated. Since 

 Okauchee has 8.1 miles of shoreline, it is estimated that on that date there 

 were no less than 116,700 dead ciscos on Okauchee shores. The epidemic 

 lasted for about six days, which gives some idea of the toll taken of the 

 species. During the winter, when the thermocline does not exist, ciscos 

 are normally caught in water 45 to 55 feet deep. 



