FOOD OF THE SHORE FISHES OF CERTAIN WISCONSIN LAKES. 277 



chastes; the bream and white bass on Cyclops and other entomostracans; the perch and 

 black bass on the larger insect larvae, adult insects, and amphipods; the blunt-nosed 

 minnow on mud; the tadpole cat on oligochaetes. 



An examination has been made of Tables 2,3, and 4 and ten others similar to them. 

 Each of these tables concerned four or more species of fishes captured at the same time 

 and place. The following' 22 species (506 individuals) appear one or more times in 

 them: Abramis crysoleucas , Amhloplites rupestris, Amiatus calva, Ameiurus melas, Ameiu- 

 rus nebulosus, Boleosoma nigrum, Catostomus commersonii, Cyprinus carpio, Esox lucius, 

 Etheostoma ioutxE, Fiindulus diaphanus menona, Labidesthes sicculus, Lepomis incisor, 

 Micropterus salmoides, Notropis heierodon, Perca flavescens, Percina caprodes, Pimcphales 

 notatus, Pomoxis sparoides, Roccus chrysops, Schilbeodes gyrinus, and Umbra limi. The 

 different figures in the bottom line of all tables were added to ascertain whether specific 

 foods were likely to be eaten by one or more fish. The results were as follows: Items 

 appearing once in any one table, 356; twice, 93; thrice, 45; four or more times, 11. 

 This shows that, though fishes may feed on the available foods, different species captured 

 at the same time and place have not eaten the same things. 



All things, then, indicate that fishes select food from their environment. In some 

 cases the powers of selecting and rejecting are remarkable. A perch may have its whole 

 alimentary canal packed full of Daphnias, when the surrounding water contains Daph- 

 nias mixed with greater quantities of algae. Only the animal plankton is taken. The 

 young sucker is able to take such minute living objects as Difflugia, Arcella, and rotifers 

 from a muddy bottom, rejecting fine particles of silt. 



CLASSES OF FOODS UTILI25ED BY FISHES. 



The foods found in fishes occurring along the shores of Wisconsin lakes fall into nine 

 classes. In order of their importance these rank as follows: (i) Insect larvse, oligo- 

 chsetes and leeches, 28.7 per cent; (2) entomostracans, 19. i per cent; (3) fishes and frogs, 

 13.8 percent; (4) insect pupae and adults, 11. 7 percent; (5) amphipods, isopods, and 

 mites, 12.7 percent; (6) plants, including algae, 4.2 percent; (7) mud, silt, and fine 

 debris, 2.6 per cent; (8) molluscs, 2 per cent; and (9) crayfishes, i.i per cent. The per- 

 centages were obtained from the last line of Table i. 



In the following paragraphs fishes are arranged under each class in the order of their 

 importance. Every species taking food in a particular class is not always recorded but 

 they all appear in Table i. It must be remembered that there is a preponderance of 

 young fishes in the data from which these results are figured. An examination of more 

 adults would doubtless increase classes 3, 6, 8, and 9. 



I. Fishes feeding upon insect larvcB, oligochmtes, and leeches. — Boleosoma nigrum, 77.6 

 per cent; Ameiurus melas, 59.6 per cent; Schilbeodes gyrinus, 57.9 per cent; Persina 

 caprodes, 54 per cent; Catostomus commersonii, 51.5 per cent; Etheostoma flabcllarc, 50.5 

 percent; Ambloplites rupestris, 46 per cent; Cyprinus carpio, 42.5 per cent; Etheo- 

 stoma iowce, 28.6 percent; Micropterus dolomieu, 2,7-7 percent; Lepomis incisor, 35.7 

 per cent; Cottus ictalops, 35.3 per cent; Perca flavescens, 35.1 per cent; Roccus chrysops, 

 30.8 per cent; Ameiurus nebmosus, 30.2 per cent; Fundulus diaphanus menona, 26.4 per 

 cent; Umbra limi, 25.9 percent; Eucalia inconstans, 24.1 percent; Micropterus sal- 

 moides, 23.7 percent; Pimephales notatus, 21.5 percent; Pomoxis sparoides, 18.4 per 

 cent; EupomoUs gibbosus, 16.2 percent; Notropis heterodon, 15 percent. 



