1915] 
Pearse: Food of Small Shore Fishes 
11 
on fish (station 5, 66%) Corixa (1, 49), insects (6, 44.1; 8, 58.3), 
and dipterous larvae (8, 57.5). Eucalia inconstans ate 37.2% 
Cyclops at station 12, 24.3 insect larvae at 11. 
In order to discover what foods were used if the favorite diet 
was not available, i.e., which foods were “rivals,” a comparison 
was made for each species between the largest items of food in 
the collections from different stations. The “maximum” for each 
locality is the largest single item of food taken. The following 
alternatives formed the maxima in two species of fishes : Copepoda 
vs. Hyalella, insect larvae vs. Cladocera, insect larvae vs. Cope- 
poda. The following alternatives were each used by only one 
species: Ostracoda vs. Cladocera, Ostracoda vs. plants, Copepoda 
vs. plants, Copepoda vs. insects, Cladocera vs. Hyalella, Clado- 
cera vs. Copepoda, Cladocera vs. mud, Cladocera vs. fish, fish 
vs. insect larvae, insect larvae vs. Hyalella. It is thus apparent, 
among small fish at least, that each species has a more or less 
pronounced taste for a particular article of food. Lepomis pallidus, 
Labidesthes sicculus, and Fundulus diaphanus menona show the 
greatest number of maxima (4) and would therefore trespass 
most on the favorite foods of other small fishes. Micropterus 
salmoides and Eucalia inconstans each show three maxima, No- 
tropis heterodon and Perea flavescens, two; Umbra limi, one. The 
species of fish which have the greatest variety of maxima are 
generally those which are found in the greatest variety of habitats, 
and those which show the least variety are most restricted in 
their range. The fishes of ponds and marshes are of course more 
restricted in their migrations and their ultimate survival in such 
situations depends more upon breeding than feeding conditions 
(Shelf ord, Tl). Fishes in large lakes and streams have a great 
variety of habitats and hence can range through several and yet 
find suitable breeding grounds when necessary. Notwithstanding 
the opportunities offered by lakes and rivers some fish (e. g., 
Cottus, Umbra, Boleosoma, Boleichthys) which live in them do 
not have a wide range. The four examples just given are fish 
which show a varied diet, but have a strong preference for or 
aptitude for catching a particular sort of food. In Lake Mendota 
the fish which are most abundant in numbers are those which 
have the most varied food habits, except Notropis which eats 
mud when other food is lacking. 
