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Ecological Associations 335 



Species Associated With Various Stream Habitats 335 



Species of Rivulets and Small Creeks 335 



Species of Large Creeks 335 



Species of Small Rivers 336 



Species Associated With Various Ecological Factors 336 



Species Associated With Other Species 337 



Notropis dorsalis — Ericymba hiiccata 337 



Notropis chrysocephalus — Erimyzon oblongus 338 



Catostomus commersoni — Phenacobius mirabilis 338 



Miscellaneous Associations 338 



General Abundance and Occurrence 339 



Average Number of Species Per Station 339 



Average Number of Fish Per 100 Square Yards 340 



Average Weight of Fish Per 100 Square Yards 340 



Distribution and Stream Size 340 



Relationships With Stream Size 340 



Number of Species and Stream Size 341 



Number of Fish and Stream Size 342 



Fish Weight and Stream Size 342 



Frequenc)' Distribution and Stream Size 342 



Conclusions on Relationships 346 



Distribution and Pollution 346 



Areas of Chronic Pollution 348 



The Bonevard 348 



West Branch 349 



East Branch 352 



Lower Salt Fork 352 



Copper Slough, Phinney Branch 352 



Upper Sangamon 352 



Upper Kaskaskia 353 



Chemistry of Polluted Waters 353 



Fish Anomalies Caused by Pollution 353 



Fish Kills 353 



Ingression Into Polluted Waters 354 



Specific Tolerance to Pollution 354 



Distribution and Water Enrichment 355 



Natural Soil Fertility 355 



Fertilizers on the Watershed 355 



Domestic Sewage 355 



Fisheries 356 



Sport Fishing 356 



Commercialized Sport Fishing 357 



Bait Collecting 357 



Summary 357 



Literature Cited 360 



Species Distribution Maps 361 



Index 376 



This paper is a joint contribution from two sections of the Illinois Natural History Survey: 



the Section of Aquatic Biology, represented by Dr. R. Weldon Larimore, Aquatic Biologist, and 

 the Section of Faunistic Surveys and Insect Identification, represented by Dr. Philip W . Smith, 

 Associate Taxonomist. 



Printed by authority of the State of Illinois, IRS Ch. 127, Par. 5SA2. 

 (65400— 7M— 12-62) 



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