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Black bullhead ( Ictalurus melas ) 29 



Yellow bullhead ( Ictalurus natalis 30 



Channel catfish ( Ictalurus punctatus ) 30 



Flathead catfish ( Pylodictis olivaris ) 30 



White bass ( Morone chrysops ) 31 



Yellow bass ( Morone mississippiensis ) 31 



Rock bass ( Ambloplites rupestris 31 



Green sunf ish ( Lepomis cyanellus ) 31 



Pumpkinseed ( Lepomis gibbosus ) 32 



Warmouth ( Lepomis gulosus ) 32 



Orangespotted sunf ish ( Lepomis humilis ) 32 



Bluegill ( Lepomis macrochirus ) 33 



Longear sunf ish ( Lepomis megalotis ) 33 



Smallmouth bass ( Micropterus dolomieui) 33 



Largemouth bass ( Micropterus salmoides ) 33 



White crappie (Pomoxis annularis) and Black 



crappie ( Pomoxis nigromaculatus ) 34 



Yellow perch ( Perca f lavescens ) 34 



Sauger ( Stizostedion canadense ) and Walleye 



( Stizostedion vitreum vitreum ) 35 



Freshwater drum ( Aplodinotus grunniens ) . 35 



Discussion of electrof ishing results 35 



Temporal distribution 36 



Spatial distirubtion 38 



PART IV: IMPACTS ON THE FISH POPULATIONS OF THE ILLINOIS 



RIVER 43 



Historical Impacts 43 



The Illinois-Michigan canal (1848) 43 



Chicago River reversal (1871) 43 



Low navigation dams (1871-1899) 45 



European carp (1885) 45 



Sanitary and ship canal (1900) 46 



Increased sewage pollution beginning c. 1910 47 



Leveeing and draining (1903-1926) 48 



High navigation dams (1930's) 49 



Changing agricultural practices — beginning c. 1940 ... 50 



Fingernail clam die-off (1955) 53 



Aquatic vegetation die-off (1920's and 1950's) 54 



Summary 56 



Present Impacts 56 



Industrial and municipal wastes 57 



Pesticides 60 



Sediment 62 



