33] STUDY OF SOUTHERN WISCONSIN FISHES— CAHN 33 



of poor keeping quality. Though the average weight is about two pounds, 

 I have taken specimens weighing 3f and A\ pounds. The smaller in- 

 dividuals are occasionally found in the stomachs of wall-eyed pike and 

 pickerel, and less frequently in the black and green bass. While the species 

 may prefer clear water and a gravel bottom, the fact that they are found in 

 water rendered turbid by the activity of the carp, speaks for a wide range 

 of tolerance if no actual impurities exist. They can not stand pollution. 



20. Moxostoma breviceps (Cope). Short-headed Red-horse. 

 Somewhat less common than the preceding, though of the same dis- 

 tribution, this species is not separated ordinarily by local fishermen. I have 

 taken the species in all of the rivers named for the preceding, but the fish 

 are more numerous in Rock river and in the Rubicon river in Dodge county 

 to the north. 



Family cyprinidae 



21. Cyprinns carpio (Linn). German Carp; Leather Carp. 



"The day will come when the people of the state (Wisconsin) will thank 

 the men who have introduced and planted this extra fine species of fish 

 (carp)." So said Dr. Lapham in a paper published in 1882. Since that time, 

 this "extra fine" species of fish has spread to almost every lake in the county, 

 and is in all the river systems. So abundant has it become in certain lakes 

 (Lac La Belle) that periodic seining is necessary to save the game fish and 

 their protecting weed beds. There is no mystery as to how the carp has 

 become so widely distributed: young carp were formerly used as bait 

 (being easily caught in the rivers) and being tenacious of life, the minnows 

 left over were thrown overboard, to live and establish themselves. It is 

 difficult to name a single lake in the county that does not contain carp. 

 The only one of the larger lakes in which I have never seen a carp is 

 Oconomowoc lake, on which I have lived for twenty-two summers. Yet 

 Okauchee which flows into it, and Fowler into which Oconomowoc flows, 

 both contain carp, and the rivers between are alive with them. The 

 average size of carp in the county is from four to six pounds, though I have 

 weighed specimens from Lac La Belle that went to 31 pounds, and the 

 Rock river contains specimens up to 42 pounds. The fish prefer soft- 

 bottomed lakes, in which they nose around, much like so many pigs. The 

 result is the uprooting of the vegetation, the destruction of weed beds, 

 and the dispersal of the game fish that habitually frequent such beds. 

 Not only this but the water is muddied by the digging to such an extent 

 that in many cases it is opaque. This sediment of course tends to settle 

 over deposit-eggs, and many are destroyed. I had opportunity in 1924 to 

 examine the entire fauna of a large lake as it was drained, and in a future 

 paper I shall show just how the carp affects a lake. 



Spawning is in late May or early June, the carp coming into the shallow 

 waters and depositing their eggs in tremendous numbers on the shallow 



