The Relation of Shellfish to Fish in Oneida Lake 27 



THE SUPPLY OF FISH FOOD AVAILABLE ix OXEIDA LAKE 



The scientific study of the food relations of fresh water 

 animals is of comparatively recent date. One of the fore- 

 most students of the food of fish has stated that of all the 

 circumstances of life none affect it so powerfully and so 

 vitally as its food supply. A study of the food of any ani- 

 mal soon develops into a consideration of all the animals, 

 plants, and general agencies which affect the life of the 

 animal in any manner. Another noted student has said that 

 " barring enemies and artificial hinderances to increase, such 

 as overfishiiig, fish will multiply up to the limit of the food 

 supply, but can never overstep that limit. If the food supply 

 can be increased, an increase in the number of fish will 

 naturally follow." Failure to realize this law has probably 

 caused many failures in attempts to stock bodies of water 

 with fish. 



But few studies of limited areas have been carried 011 in 

 this country for the purpose of ascertaining rather precisely 

 the amount of fish food in a body of water. In Europe, 

 however, the floating microscopic food in inland and marine 

 waters has been studied, but only one quantitative study of 

 the bottom animals of a lake has been seen. The most nota- 

 ble study of marine bottom food has been carried 011 at the 

 Danish Biological Station, under the direction of Dr. C. G. 

 Joh. Petersen, who realized that to understand fully the 

 conditions governing the habits of fish, especially as regards 

 their food, a knowledge must be gained of the variety and 

 amount of the possible food supply. In other words, a bio- 

 logical survey of the fish habitat is necessary. For the pur- 

 pose of carrying on this work, Dr. Petersen devised an in- 

 strument which he called a " bottom sampler." With this 

 apparatus it was possible to bring up from the bottom of the 

 sea a small sample of the bottom one-tenth of a meter square 

 (about four inches) with the bottom layers one to two milli- 

 meters (1/25 to 1/13 inch) thick, in their natural position. 

 A large number of these bottom samples were obtained, and 

 the animals in each were counted. By this .means it was 

 possible to find the average amount of food present in an 



