FOOD OF THE SHORE FISHES OP CERTAIN WISCONSIN LAKES. 25 1 



Collections were made with a miniature fyke net, dip net, minnow seine, and gill 

 net. When they could not be examined within an hour or two, the fishes were placed in 

 95 per cent alcohol and kept until examined. In examining the food, the entire contents 

 of the alimentary canal were pressed out on a strip of glass, moistened, and then teased 

 apart with needles under a binocular microscope. Insect fragments were turned over 

 to an expert entomologist for identification. As the constituents of the food were identi- 

 fied, they were written in the permanent record. As each fish was completed, the per- 

 centage by volume of each constituent was estimated. All figures in this paper refer to 

 such volumetric percentage estimates. 



During the work assistance was rendered by a number of persons, and it is a pleasure 

 to acknowledge this indebtedness. Dean E. A. Birge and Mr. Chancey Juday, of the 

 Wisconsin Geological and Natural History Survey, loaned equipment and extended 

 other courtesies. Miss Henrietta Achtenberg worked four months computing averages 

 and rewrote part of the manuscript. Dr. John Lowe and Mr. Alvin Cahn furnished some 

 rare fishes for examination. Mr. A. F. Shira and Mr. Juday read the manuscript and 

 made a number of helpful suggestions. Invaluable assistance was rendered by Dr. R. A. 

 Muttkowski, who identified all the insects. 



II. DESCRIPTION OF FOODS. 



All figures following foods are given in volumetric percentages; -I- indicates a trace. 

 The lengths are given in millimeters and exclude the caudal fin. The species are arranged 

 alphabetically according to their scientific names. Under each species the records are 

 arranged according to dates, and the stations (see chart) where collections were made 

 are given in each case. 



Abramis crysoleucas (Mitchill). Golden shiner, roach, bream. 



Station 5; August 18, 1915; number examined, 2. Length: Maximum, 94; minimum, 92.5; average, 



93.2. Food: Hyalella, 42.5; Bosmina, 0.5; Camptocerus, 1.5; filamentous algae, 40.5; fine siltand d6bris, 



15- 



Station 5; August 18; number examined, 5. Length: Maximum, 31.3; minimum, 23.5; average, 



28.1. Food: Helea larva, i; Tanypus cameus larva, 4; insect, 3; water mites, 1.2; ostracods, 4; Cyclops, 

 3^; Canthocamptus, 2; Cladocera unidentified, 14; Bosmina, 14; Pleuroxus, 1.4; Chydorus, 3; Simoce- 

 phalus, 7; rotifers, 0.8; plant tissue, 4.8; seeds, 0.8; WolfBa, 3; Volvox, 2.2; Closterium, 0,4; Pandorina, 0.4. 



Summary. — Food: Dipterous larvae, 5; insects, 3; water mite, 1.2; ostracods, 4; copepods, 35; Clado- 

 cera, 39.4; rotifers, 0.8; plants, 8.6; flagellates, 3. 



Station 18; August 18; number examined, 23. Length: Maximum, 75; minimum, 34; average, 



39.3. Food: Tanypus monilis pupae, 12.4; Cyclops, 20; Daphnia longispina hyalina, 65; Simocephalus, 

 2.1. 



Station 5; August 25; number examined, 10. Length: Maximum, 68; minimum, 27.5; average 



33.2. Food: Chironomus lobiferus larvas, 5.5; water mites, 2; Cyclops, 0.2; Bosmina, 88.5; Ceriodaphnia, 

 3.5; algal filaments, o.i; Volvox, o.i. 



Station22; April I, i9i6;numberexamined, I. Length: 152. Food: Caddis-flycase, 0.5; ostracods, 

 90; Cyclops, 0.5; Daphnia pulex, i; filamentous algae, 8. 



Suvimary. — Insect larvae, 0.5; Entomostraca, 91.5; plants, 8. 



Station 18; April 13; number examined, 3. Length: Maximum, 137; minimum, 114; average, 

 122.6. Food: Larvae sp., 6.6; Chironomus sp. larvae, 2.3; C. lobiferus larvae, 0.3; Orthocladius flavus 

 larvae, 0.3; Copotomus interrogatus adult, i; Chironomus sp. adult, 38.3; Hyalella, 15; Cyclops, i; snail 

 remains, 1.6; Valvata tricarinata, 15; Lemna, 15; debris, 3.3. 



Summary. — Food: Insect larvae, 9.5; adult insects, 39.3; amphipods, 15; copepods, i; Mollusca, 

 16.6; plants, 15; ddbris, ^.^. 



