most notable. In 1996, only 2 bluntnose minnow, 43 emerald shiner, and 23 red 

 shiner were collected compared to 407 bluntnose minnow, 1076 emerald shiner, and 

 161 red shiner in 1995. Also, no bullhead minnow were collected in 1996 whereas 

 616 were collected on the upper waterway in 1995. Other relatively large declines in 

 abundance were gizzard shad and bluegill; 420 gizzard shad were collected in 1996 

 compared to 1369 in 1995, and 43 bluegill were collected in 1996 compared to 500 

 in 1 995 Abundances of fishes at sites in 1 996 were more similar to those observed 

 in 1 994 in the upper watervv'ay, although overall species richness in 1 996 (23) was 

 much lower than in 1994 (31). Species richness in 1996 ranged from 8 at Bull's 

 Island (RM 240.7) to 14 at the mouth of the Du Page River (RM 277.3) and Treats 

 Island (RM 279.9). The species richness of upper waterway sites were more similar 

 to sites on the lower Illinois River (Table 2), although species composition at lower 

 river sites was somewhat different than that of the upper waterway. 

 Catch Rates in Number of Individuals Collected per Hour by Reach . 



In the following data summary, discussion is restricted either to species that 

 each separately accounted for over 1 0% of the total catch or to species that were of 

 special significance. At all reaches in 1996, the gizzard shad ranked first by relative 

 abundance in number offish collected per hour. 



Alton (lower river). The 95% lists (species were added to the list until 95% 

 of the total catch rate in numbers was obtained) for Alton, La Grange, and Peoria 

 Reaches were similar, although CPUEfj varied among reaches. Eleven species 

 accounted for 94.5% of the total catch in Alton Reach (Tables 6 and 7). Overall, 



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