adapting to many of the changes in the river. The 

 fishery of the river reached its peak in 1908, when about 

 24 million pounds of fish were taken commercially. 

 Carp made up nearly two-thirds of this catch. 



The great increase in the commercial fishery starting 

 at the turn of tlie century appeared to result from the 

 increase in water because of the diversion from Lake 

 Michigan, the increased nutrients made available to 

 fish-food organisms, and the population explosion of 

 the carp. 



Since 1908 the Illinois River fishery has been de- 

 clining (Fig. 7) ; data in this depth are not available 

 for sport fishes. 



The gains in water area available to fish, brought 

 about by the diversion of Lake Michigan water, began 

 to be offset after 1907 by the drainage of bottomland 

 lakes. The 1913 area was about the same as it was in 

 1897, prior to diveision (Forbes & Richardson 1919: 

 154). In addition to these losses due to draining, condi- 

 tions were further aggravated by the increase in sedi- 

 mentation discussed earlier. Pollution from the Chicago 

 and the Peoria-Pekin metropohtan areas has had serious 

 efl'ects on the fish and fish-food organisms since the peak 

 of the fishery in 1908. The upper river was more dras- 

 tically affected than the part below Utica. Between 

 1912 and 1917 pollution completely wiped out the fish 

 life above this city (Thompson 1928:301). 



Forbes & Richardson (1913:517, 521-522) stated 

 that near Morris (Marseilles Pool) in August and Sep- 

 tember of 1912 the river "was practically destitute of 

 fishes, and the few taken were in close pro.ximity to the 

 Mazon slough. Moreover, some of the bullheads were 

 'fungused' or in otherwise unwholesome condition. 



"The only other vertebrates taken here were a single 

 frog, two sna]jping turtles, and a soft-slielled turtle. The 

 search for moUusks yielded seven species of mussels, all 

 the specimens dead, however, except for one collection 

 made in Mazon slough. ... In August and September, 

 1912, [Marseilles] conditions were similar to those found 

 at Morris at the same time. Set-nets were raised every 

 day from August 13 to 17, but witiiout result; and a 

 dozen half-pound sticks of dynamite were exploded, hut 

 no fish were taken. . . . On the night of August 19, a 

 heavy rain, which flooded the small creeks, washed fishes 

 out into tlie river, where they became sick from sewage 

 and could be picked up easily with a dip-net." 



In the summer of 1923 the ri\er was practically 

 anaerobic as far down as Cliillicothe, with conditions 

 virtually impossible for the existence of fish (Greenfield 

 1925:24-25). 



There has been a change toward the better in the 

 upper river since then. Today fish are found living in 

 the river above Utica. The goldfish (Carrasius auratiis) , 

 an exotic fish not present in tlie river prior to 1908, now 

 occurs commonly in the upper reaches, together with 

 carp, black bullheads (Iclalurus mclas) , emerald shiners 

 (Notropis atherinoides) , and other less abundant species. 

 The return of fish life to this part of the river dining 

 the late 1930's followed the better treatment of Ciiicago 

 wastes and the slowing of the river's current following 

 the building of the navigation dams. 



From a comparison of modern studies with those 

 made befoie 1908, it appears that we may have lost 18 

 species of fish from the Illinois River (Starrett & Smith, 

 unpublished) . Many species now occur less abundantly 

 than in former years. 



25.0 



COMMERCIAL FISH YIELDS FROM 

 ILLINOIS RIVER 1894-1964 



1894 1897 1899 



1921 1922 



' 1931 ^ 1950 1955 I960 1964 



YEAR 



I 



Fig. 7.- — Changes in 

 coninurcial fish yield in 

 the Illinois River from 

 1894 to 1964. (Data 

 based on published fed- 

 eral fisheries statistics 

 and observations made 

 by the Illinois Depart- 

 ment of Conservation 

 and Natural History 

 Survey. Data for 1 955, 

 1960, and 1964 from 

 Starrett, Lopinot & 

 11, nth. im])iiblished. ) 



15 



