338 BULLETIN OF THE BUREAU OF FISHERIES. 
(Pomoxis sparoides), 183; largemouth black bass (Micropterus salmoides), 305; pumpkin- 
seed (Eupomotis gibbosus), 428; bluegill (Lepomis incisor), 1,238. 
This gives a rough approximation of the number of food fishes caught in Lake 
Mendota each year and may serve as a standard for lakes of similar size, depth, and 
situation. The old fishermen claim that many more fish were caught 15 years ago 
and state that a single man sometimes secured over 800 perch in a day. At present 
the usual catch of a professional fisherman, fishing through the ice with a line and two 
hooks, is from 200 to 400 per day. 
Lake Wingra not only has smaller perch, but fewer of them. ‘This is clear from the 
eatch per hour in gill nets (Tables 2 to 5; figs. 3 to 5). The reasons for lesser size have 
already been discussed, and apparently the same reasons set a smaller limit to num- 
bers. The differences between the sizes and numbers of perch in the two lakes are 
due to variations which interfere with growth and allow fewer individuals to survive in 
Lake Wingra. 
SUMMARY. 
1. The habits of perch in a small, shallow, and muddy lake were compared with 
those of perch in a neighboring large, deep, and clean lake. Perch were the most abun- 
dant fishes in both, but, in proportion to the size of the lake, there were more in the 
larger lake. 
2. The perch is a versatile feeder but usually gets its food on or near the bottom. 
The percentage by volume of the foods eaten by 1,147 adults was as follows: Chiro- 
nomid larve, 25.2; cladocerans, 22.1; Corethra larve, 6.4; silt and bottom débris, 6; 
chironomid pupa, 5.9; fish, 5.2; amphipods, 3.6; Sialis larve, 3.4; caddisfly larve, 2.1; 
oligochetes, 1.5; crayfishes, 1.5; odonate nymphs, 1.4; clams, 1.2; alge, 1.2; snails, 1.1; 
ephemerid nymphs, 0.9; calcium carbonate crystals, 0.5; leeches, 0.4; hemipterous 
adults, 0.3; mites, 0.3; chironomid adults, 0.2; Corethra adults, 0.2; Corethra pupa, 
0.2; copepods, 0.1; ostracods, 0.09. 
3. There are more or less marked seasonal variations in all constituents of the 
perch’s food. In general, foods are eaten in proportion to their abundance and avail- 
ability; but this is not always the case. 
4. An adult perch eats about 7 per cent of its own weight each day. Digestion is 
three times more rapid in summer than in winter. 
5. Perch do not take any abundant food but select certain things. There are daily 
and seasonal variations. Individuals feeding in shallow water eat a greater variety than 
those from greater depths. Perch contain food which is available at the depths where 
they are caught, which indicates that extensive vertical migrations are infrequent. 
6. Food varies with age. During youth there is a change from Cyclops and other 
entomostracans to Hyalella and insect larva. At the end of the first summer the food 
of young perch is much like that of adults. 
7. As judged by the rate of increase in young perch when fed on a single food the 
following varieties rank in the order given, the best being first: Earthworms, ento- 
mostracans, chironomid larva, amphipods, fish, small amounts of various foods, liver 
and flour, adult insects. 
8. In the small lake investigated insects were the most important constituent of 
the food. In the larger lakes insects and entomostracans were equally important. 
