478 Illinois State Laboratory of Natural History. 



THE FOOD OF ADULT FISHES. 



An analysis of our facts made with reference to the kinds 

 of fishes eating each of the principal articles in the dietary of 

 the class and showing the relative importance of these elements 

 in the food of the various species, will exhibit the competitions 

 of fishes for food more clearly and precisely than my earlier 

 discussions, and also the nature and the energy of the restraints 

 imposed by fishes on the multiplication of their principal food 

 species. 



PISCIVOROUS FISHES. 



The principal fish-eaters among our species those whose 

 average food in the adult stage consists of seventy-five per 

 cent, or more of fishes are the burbot 1 , the pike-perch 2 or wall- 

 eyed pike, the common pike 8 or "pickerel," the large-mouthed 

 black bass, 4 the channel cat, 5 the mud cat, 6 and the gars. 7 

 Possibly also the golden shad 8 will be found strictly ichthy- 

 ophagous, this being the case with the four specimens which I 

 studied. 



Those which take fishes in moderate amount the 

 ratios ranging in my specimens from twenty-five to sixty- 

 five per cent. are the war-mouth (Chaeoobryttus), the 

 blue-cheeked sunfish, 9 the grass pickerel, 10 the dog-fish, 11 the spot- 

 ted cat, 12 and the small miller's thumb 13 . The white 14 and strip- 

 ed bass, 15 the common perch, 16 the remaining sunfishes (those 

 with smaller mouths), the rock bass, 17 and the croppie, 18 take 

 but few fishes, these making, according to my observations, 

 not less than five nor more than twenty-five per cent . of their 

 food. 



Those which capture living fishes, to a trivial extent, 

 at most, are the white perch or sheepshead, 19 the gizzard 



1 Lota maculosa. 2 Stizostedion vitreum. 3 Esox lucius. 4 Mi- 

 cropterus salmoides. 5 Ictalurus furcatus. 6 Leptops olivaris. 7 Lepi- 

 dosteus. 8 Clupea chrysochloris. 9 Lepomis cyanellus. 10 Esox vermic- 

 ulatus. n Amia calva. 12 Ictalurus punctatus. 13 Uranidea richard- 

 sonii. u Roccus chrysops. 15 Roccus interruptus. 16 Perca lutea. 

 17 Ambloplites rupestris. 18 Pomoxys. 19 Aplodinotus. 



