108 





Co 



mmon sucker 



The common sucker runs upstream to spawn early in 

 the spring. It prefers swift water and gravel bottoms, 

 scattering its eggs freely in the current. The sucker 

 will spav-'n to some extent in lakes if there are no 

 outlets and inlets. Work done in New York indicates 

 that temperatures from 57° to 63° F. are best for 

 hatching eggs. The incubation period is then 5 to 7 

 days. At 70° F. mortality is high and the incubation 

 period is 4 days. At 40° F. none hatched in more than 

 14 days. As many as 47,800 eggs were taken from one 

 female. 



The common sucker has diversified feeding habits. 

 It seems to feed on any food that may appear in the 

 water, including fish and fish eggs. It is largely an 

 animal feeder in Lake Nipigon. This species is some- 

 times divided into size-groups upon the basis of diet, 

 as follows: (1) Rotifer-eating stage, at a length of 

 0.7 inch; (2) cl adocera-eat ing stage, at a length of 

 1.2 inches; (3) insectivorous stage, more than 2 inches 

 in length. The common sucker has been known to feed on 

 mud, plants, mollusks, insects, entomostracans, diatoms, 

 desmids, rotifers, crustaceans, and protozoans. Stom- 

 ach analyses showed 100 percent insects in some collec- 

 tions, 100 percent higher plants in others, 95 percent 

 mollusks in one collection, and 50 percent drift in 

 other stomachs examined. The average percentages of 

 various food items found in stomachs examined by 

 several workers are as follows: insects, 39.0; crusta- 

 ceans, 3.3; mollusks, 10.3; surface drift, 2.1; plank- 

 ton, 26.3; higher plants, 9.7; miscellaneous, 8.8; and 

 bryozoans, 0. 5. 



