EXECUTIVE SUMMARY 



Between 26 August and 1 9 September 1 996, 26 sites on the Illinois River 

 Waterway and one site on Reach 26 of the Mississippi River were electrofished to 

 monitor fish communities. A total of 5,062 fish representing 41 species (plus two 

 hybrids) from 1 1 families were collected during 24.75 h of sampling. Our monitoring 

 indicated the abundance of an important forage species, gizzard shad, and the 

 continued recovery of several sport fishes such as white bass and bluegill. Gizzard 

 shad represented 48.4% of the total catch in numbers and was present at all 27 

 sites, followed by white bass (8.9%, 20 sites), and bluegill (8.1%, 25 sites). 

 Common carp and goldfish, often regarded as indicators of polluted or degraded 

 river environments, comprised only 6.4% and 0.2% of the total catch, respectively. 

 Mud darter and silverband shiner were collected for the first time during project F- 

 1 01 -R sampling from Henry Island (RM 1 93.9, Peoria Reach). The sample from 

 Pekin (RM 1 54.9, La Grange Reach) yielded the most fish (524, 1 0.4% of the total 

 collected from all 27 sites). Species richness at sites ranged from 20 at Detweiller 

 Marina (RM 170.7) in Peoria Reach to 8 at Bulls Island (RM 240.7) in Starved Rock 

 Reach. Species richness of the lower, middle, and upper wateoA/ay was 23, 38, and 

 23, respectively. In 1996 we noticed a decline in small cyprinid abundance in the 

 upper waterway compared to that observed in 1 995. Although emerald shiner 

 ranked second by relative abundance (7.7%) in Starved Rock Reach, the catch in 

 numbers (CPUEn) was only 11.50 in 1996, compared to 438.50 in 1995. Also, 

 bullhead minnow were not collected in any upper waten^'ay reach in 1996, and 

 bluntnose minnow were not collected in either Starved Rock or Marseilles reaches. 

 Emerald shiner and bullhead minnow were among the most abundant species 

 collected in these reaches in 1995. Important sportfish species such as channel 

 catfish and largemouth bass were collected in all three waterway segments in 1996. 

 Channel catfish CPUE^ in Alton Reach (lower waterway) was 19.40, which is the 

 highest catch rate for this species in this reach since 1989. Largemouth bass 

 CPUEn was highest in Peoria Reach (7.38) but catches were also high in Dresden 

 and Alton Reaches where CPUE^ was 6.00 and 5.80, respectively. As in previous 

 years, common carp continued to be an abundant species in La Grange Reach of 

 the middle watenA'ay (CPUEn=36.36), but the species was not abundant in the upper 

 wateoA'ay. However, when considering the catch rate in terms of pounds of fish 

 collected per hour (CPUEw), common carp was the dominant species in all except 

 Starved Rock and Alton Reaches. Common carp CPUEw ranged from 71.15 in La 

 Grange Reach to 4.93 in Starved Rock Reach. Smallmouth buffalo CPUE^ was 

 highest in Starved Rock Reach, and channel catfish CPUE^ was highest in Alton 

 Reach, at 8.97 and 19.06, respectively. Sediment-contact fishes (e.g., common 

 carp) had a higher incidence of externally-visible abnormalities than water-column 

 fishes (e.g., bluegill). The highest incidence occurred in the upper waterway, where 

 34.2% of benthic fishes had abnormalities in 1 996. This indicates that stressful 

 factors are associated with sediments in the Chicago-Joliet area. 



