FAMILY PERCIDAE 207 



Figure 37. Yellow perch, Perca flavescens, 6 inches long. 



wholly carnivorous and prefer a diet of minnows, but eat aquatic insects, 

 the young of other fishes, crayfishes, and other animal matter as well. 

 Their extreme voracity makes them a nuisance in many waters. 



When free from parasites perch are excellent food fishes, but they are 

 not very popular with anglers in most parts of Minnesota. Incredible 

 numbers of them can be easily caught in most Minnesota and Wiscon- 

 sin lakes. They bite readily on worms, minnows, and other baits, and 

 are often termed "bait stealers." In some lakes they apparently com- 

 pete with the more desirable game fishes to such an extent that such 

 lakes have been termed "perch-bound." Where they are excessively 

 abundant they are very small, probably because of crowded condi- 

 tions. The competition for food in such cases retards growth. Cannibal- 

 ism, which would be a welcome antidote for such a condition, does not 

 occur because of the similarity in size of the individuals comprising 

 the perch population. Undoubtedly perch are an obstacle in artificial 

 stocking, for they may consume newly introduced fry as fast as they 

 are placed in the lake. 



Perch usually spawn early in May, though spent females have been 

 found in central Minnesota lakes as early as the first part of April 

 when the ice was just beginning to melt. The spawning season lasts 

 from 2 to 4 weeks. When the water temperatures are between 45° and 

 50° F. the eggs are deposited in the water and settle in heavy, adhe- 

 sive bands over sticks and water weeds on sandy bottoms. Spawn- 

 ing usually occurs at night. The spawn is deposited in hollow, ribbon- 

 like bands several inches wide and plaited like the bellows of an accor- 

 dion. These masses may be drawn out to a length of some feet. Smith 

 (1907) stated that one fish in an aquarium at the Bureau of Fisheries 

 in Washington, D.C., deposited a string 88 inches long, the weight of 

 which after fertilization was 41 ounces, although the weight of the 

 fish before discharging the eggs had been only 24 ounces. The relative 

 heaviness of the fertilized eggs was obviously due to water absorbed 



