28 ILLINOIS BIOLOGICAL MONOGRAPHS [28 



Spawning occurs in the fall, usually early in November, at which time 

 the fish come into the shallow water along the shore or ascend the rivers 

 to lay their eggs. Development follows very slowly, the young fish hatching 

 sometime early in the spring, probably just prior to the breaking up of the 

 ice. The young ciscos go immediately into deep water. The food consists 

 almost entirely of plankton organisms, principally Cyclops, Daphnia, 

 Diaptomus, Bosmina, Chydorus, rotifers and other organisms of a similar 

 nature, as well as large numbers (in one case 376) of Sayomia albipes 

 larvae. From an economic point of view, the cisco is a valuable food fish, 

 particularly in the winter when the meat is firm and solid. Every effort, 

 including the artificial propagation of the species, should be exerted to 

 save these fish which are rapidly nearing the point of extermination. While 

 the fish remain in deep water they have but few natural enemies; when they 

 come into the shallower regions they are preyed upon voraciously by large 

 pickerel (Esox lucius) and to a lesser extent by the gar (Lepisosteus osseus). 



5. Oncorhynchus tschawytscha (Walbaum). California Salmon, or Chinook. 



Like the whitefish, this fine species was introduced into Oconomowoc 

 lake, but without success. The state fish commission reports show that in 

 1877, 4,800 fingerling California salmon were planted in this lake, and in 

 1879, 1,500 somewhat larger individuals were liberated in Nagawicka lake. 

 Some of the fish were caught in the years immediately following, but the 

 fish never reproduced and are now entirely extinct. The lakes are not cold 

 enough to accommodate these fish, so that such transplantations are utterly 

 fruitless. 



6. Salmo sebago (Girard). Landlocked Salmon. 



In 1879 the reports of the state fish commisson at Madison show 

 that 12,000 of these fish, in fingerling size, were planted in Nagawicka lake. 

 Like the above species a few were caught shortly after the transplantation 

 occurred, these weighing in the neighborhood of a pound to a pound and a 

 half, but the species failed entirely to establish itself and quickly became 

 extinct. 



7. Salmo irideus (Gibbons.) Rainbow Trout. 



The rainbow trout is not a native species in southern Wisconsin, but, 

 notwithstanding this fact, the transplantation of the fish into the suitable 

 trout streams of the county has resulted in the firm establishment of the 

 species. Planted in such admirable streams as Rosenow's creek, flowing 

 into Lac La Belle on the east, and Scuppernong creek farther south, the 

 rainbows have bred and successfully maintained themselves amid the 

 water-cress beds and the clear, cold spring water. Traveling down stream, 

 the fish have entered various lakes, so that at least two — Lac La Belle and 

 Dutchman's — contain the species in some numbers. I believe that I have 

 taken the record rainbow for the county: a fish weighing four and three- 

 quarters pounds, from Dutchman's lake, August 29, 1912. Since then many 



