258 



BULLETIN OF THE BUREAU OF FISHERIES. 



mouth black bass, i ; carp, + ; large mouth black bass, ' + ; pumpkinseed,* + . These fig- 

 ures probably are almost correct with two exceptions : There are doubtless schools of carp 

 too large to be caught in the nets used; and the pickerel, because it is fairly abundant 

 and probably moves about more in search of food, is captured more often than the 

 other fishes considered. There seems to be no question that the cisco is far more 

 abundant than any other species. 



Table 3. — Summary of Gill-Net Catches in Green Lake, 1919, Giving Depth and Catch per 



Hour. 



It is interesting in this coimection to compare the results for Lake Mendota during 

 the summer of 1919. Lake Mendota has a maximum depth of 25.6 m. It differs from 

 Green Lake ecologically in that its lower water stagnates (Birge and Judaj^ 1911)- 

 This means that the deeper parts (below 8 to 15 m.) are without oxygen during August, 

 September, and October. The important ecological feature in this lake as a habitat 

 for fishes is the fact that the water above the thermocline is well aerated and warm, 

 while that below is without oxygen and comparatively cool. The temperatures of the 

 water in Lake Mendota during the period work was being done in Green Lake are avail- 

 able through the courtesy of President E. A. Birge, of the University of Wisconsin. 



While the writer was working in Green Lake, Leslie Tasche was setting a string of 

 five nets (precisely like those used in Green Lake) in Lake Mendota. The summary of 

 some of his catches will serve as a basis for comparison between the two lakes. The 

 nets were set in Lake Mendota on the steep slope off the end of Picnic Point, where gen- 

 eral conditions are much like those in Green Lake. 



1 This species is included because young or adults were caught in the lake by other methods of fishing than gill nets; -f- 

 indicates an amount less than o. i per cent, throughout this paper. 



