404 



POSSIBLE REMEDIAL MEASURES 



1. Artificial regulation of zvater levels on the most important 

 breeding grounds, especially during the critical period of such sea- 

 sons as 1900, 1901, 1902, 1904, 1906, and 191 1; aud provision of 

 better means of escape for the fry at the beginning of the critical 

 period, by ditching. It is possible that something could be accom- 

 plished in both these directions by cooperation of the Fish Commis- 

 sion with some of the better-situated agricultural drainage districts. 



2. Protection of grozving fry against enemies, particularly bass, 

 gar, and pike. The State Fish Commission has already taken up the 

 question of gar extermination ; but until some suitable method of 

 segregation in the Illinois river backwaters of the angling (bass) 

 and commercial (carp and buffalo) interests is adopted, the bass 

 will continue to be a very destructive enemy of the fry of the two 

 commercial species — carp and buffalo. 



3. Protection of eggs ogainst destruction by fungus. Our ob- 

 servations show clearly that destruction by fungus is least among 

 eggs spawned in clean water, bearing a naturalized growing aquatic 

 or semi-aquatic vegetation. As a result of the higher water-levels 

 since the opening of the Chicago Drainage Canal, in 1900, the breed- 

 ing grounds of the carp have been pushed back, to a great extent, 

 into newly made marshes, not yet adapted to submergence, and still 

 choked every spring with dead and rotting land plants. It is pos- 

 sible that in time this matter will adjust itself to a certain extent. 

 Such a readjustment would be assisted by any measures taken to 

 insure, artificially, greater permanence of levels in these areas. 



