HABITS OF YELLOW PERCH. 301 
Aside from the myriads of pelagic animals and small fishes which may serve as food 
for perch, there are, then, 19,926,790,000 macroscopic animals along the shore. 
Though no careful studies of Lake Wingra have been made, its swampy shores and 
muddy, plant-covered bottom must support an equally abundant fauna suitable for 
perch food. 
In order to determine what the perch eat in the two lakes selected for study, an 
attempt was made to examine 10 individuals each week for an entire year. This was 
easily accomplished in Lake Mendota during 1915, and many supplementary exami- 
nations were made throughout the following year. In Lake Wingra weekly examina- 
tions were made during the spring and summer, but in late autumn and winter perch 
July August Sept Oct. Nev. 
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Fic, 3.—Perch caught per hour at various depths in 1-inch mesh gill nets, 3 by 7s feet, left in the water for approximately 24 
hours, Lake Mendota, 1915. -.-.-.-,o to5 m.; , 5 tor10m.; -00-0-, roto15m.;......,15 to 24m. 
could not always be caught regularly. While the lakes were free from ice, most of the 
perch were caught in gill nets and were therefore of fairly uniform size, because the 
dimensions of the mesh selected certain classes. The current opinion among fishermen 
that perch are uniformly larger in Lake Mendota than in Lake Wingra was proven by 
the gill-net catches to be correct (Tables 2 to 5; figs. 3 to 5). In the former lake more 
perch were caught per hour in 1-inch mesh nets than in those of three-fourths-inch mesh; 
and in the latter the opposite was true. During the winter months perch were caught 
through the ice on hooks baited with minnows or perch eyes. At the beginning of the 
work in Lake Mendota most of the fishing was done east of Picnic Point, but after 
June 25, 1915, the routine catches recorded in Tables 2 and 3 were made directly north 
of the University of Wisconsin. Catches were made in all parts of Lake Wingra. 
