19] STUDY OF SOUTHERN WISCONSIN FISHES— CAHN 19 



for the species, but the drop in level occurs often before the eggs mature 

 and a majority of them are left stranded and never hatch. During the 

 winter the formation of the ice plays an important part in the life of the 

 iish of some lakes — as Mud lake north of Pine lake — where, if the ice 

 forms in excessive thickness and so completely as to leave no free water, 

 thousands of fish of all species are killed from a lack of oxygen. Such lakes 

 are deficient in springs, and with the cutting off of the contact between the 

 water and air, oxygen deficiency occurs. Such a condition a number of 

 years ago completely robbed Washtub lake of its entire larger fish fauna — 

 sunfish, perch, bass, pickerel, carp — leaving it almost a dead lake. Winter 

 fishing through the ice is of great importance as thousands of perch, silver 

 bass, pickerel, cisco, white bass and wall-eyed pike are caught at a time 

 when the species (excepting only the cisco) are heavy with spawn. The 

 result is a serious drain on the fish population, which is offset only to a 

 slight degree by the food value of the fish — most of the fish caught are 

 sold in spite of the law — with the maximum amount of waste and the 

 minimum amount of sport. 



Table 2 



CLIMATOLOGICAL DATA FOR WAUKESHA COUNTY, WISCONSIN 



(City of Waukesha; elev. 864 ft.) 



1913 1914 1915 1916 1917 1918 1919 1920 1921 



Maximum Temperature 97 95 87 103 98 102 101 93 100 



Minimum Temperature -12 -20 -23 -17 -18 -23 -21 -15 -3 



Average Temperature 47.2 43.8 43.6 45.7 42.7 46.5 46.3 45.9 50.2 



Maximum Monthly Precipi- 

 tation 7.06 6.90 10.0 6.60 7.44 5.60 6.97 4.71 9.50 



Month of Maximum Precipi- 

 tation 9 9 6 6 9 5 5 3 9 



Minimum Monthly Precipi- 

 tation 49 ? .65 .41 .38 1.29 .32 .38 .30 



Month of Minimum Precipi- 

 tation 12 ? 12 7 11 9 1 2 1 



Total Precipitation 39.7 32.7 32.68 42.3 35.0 30.4 36.9 30.5 40.4 



Total Snowfall 39.4 47.1 ? 58.0 35.9 71.0 43.7 35.0 31.9 



Mean annual temperature for 25 years 46.0 



Mean annual precipitation for 28 years 30.16 inches. 



LAKE CONDITIONS 



One of the most significant features of the lake environment is the 

 seasonal cycle which the waters undergo. These changes are both thermal 



