Biological Survey — Oswego Watershed 81 



ing to watch. They suck up a mouthful of the debris from the 

 bottom, eject this from the mouth, then dart forward and gobble 

 up bits of desirable food. This preferential type of feeding has 

 not before been attributed to carp. The young fish living in 

 aquaria frequently resort to top feeding, working here and there 

 with their mouths just below the surface of the water sucking up 

 bits of floating matter. This is probably an unusual type of feed- 

 ing for young carp in their natural haunts, for the fish lives near 

 the bottom. Observations made on the stomachs of little carp 

 taken at different hours during the day, indicate that they have 

 rapacious appetites which keep them busy foraging for food at all 

 hours of the day. 



Young carp are very active, strong swimmers and their inquisi- 

 tive natures keep them continually exploring the domain in which 

 they live. But being more timid than our common game fish it is 

 difficult to observe them. Their tendency to live in dense growths 

 of flora and to bury themselves in the mud indicates that the young 

 fish may be to some extent negatively phototrophic, in which case 

 their behavior differs from the adult, which shows no aversion to 

 light. The instincts seem to be poorly developed in the young carp, 

 for our observations show no indications of pugnacity or on the 

 other hand of a tendency to be gregarious. A characteristic occa- 

 sional darting about aimlessly through the water might be at- 

 tributed to play. 



The Food of the Young Carp. — Pearse* reports on the food of 

 42 young carp, ranging from 15 mm. to 460 mm. These were taken 

 between the dates of July 12 and September 14, with one specimen 

 secured April 22. The collections extended over two summers. 

 The summary of the food in percentages of these 42 is as follows : 



Food : insect larvae, 39.7 ; insect pupae, 6.8 ; adult insects, 3.5 ; 

 mites, 1.8; amphipods, 6.9; cntomostracans, 20.9; snails, 6,9; 

 oligochaetes, 2.8; rotifiers, 1.1; protozoans, -f- ; algae, 0.8; plant re- 

 mains, 4.9 ; silt and debris, 1.5. 



While several hundred young carp were taken during the sum- 

 mer the study of food contents was made on only 87. The collec- 

 tions were from both the south and north shores and Frenchman's 

 island. Fish taken from such widely separated regions should show 

 variations in their food, if the fish were merely taking what was 

 available or were omniverous, but we find a great similarity in the 

 stomach contents of the young fish taken from these widely sepa- 

 rated localities. Animal food dominates throughout the period 

 with the ostracocls, copepods, snails, and chironomid larvae per- 

 sisting as the most important food. It is interesting to discover 

 that the same conditions obtained in these young as are found 

 in the adults, for many had the stomach empty and some the en- 

 tire intestinal tract. Such conditions cannot be due to the scarcity 

 of food for there was a continued abundance of these food or- 

 ganisms throughout the summer. 



The following individual studies introduce the summary in 



* Pearse, A. S. The Food of the Shore Fishes of Certain Wisconsin Lakes. 

 Bull. U. S. Bur. Fisheries, vol. 35, 1918. 



