Between 22 August and 26 September 2005, 27 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 7,676 fish representing 56 species (plus 2 hybrids) from 13 families were collected during 26.58 hours of sampling. Collections made in 2005 indicated a continued abundance of gizzard shad and bluegill throughout most of the waterway with higher numbers of freshwater drum in the lower waterway. Common carp and goldfish, species which were once dominant, continue to remain relatively low in abundance throughout the Illinois River Waterway, contributing only 1.4% and 0.3% of the total catch respectively. Blacknose daces, creek chubs, and common shiners were collected for the first time during project F-101-R sampling along the waterway. Blacknose daces were collected from two sites, Bull’s Island (RM 240.8, Starved Rock Reach) and Bull’s Island Bend (RM 241.5, Starved Rock Reach). Creek chubs were only collected from one site (Bull’s Island), while common shiners were collected at four sites in four reaches; the Mouth of the DuPage River (RM 277.4, Dresden Reach), Waupecan Island (RM 260.6, Marseilles Reach), Bull’s Island Bend, and Hennepin Island (RM 207.6, Peoria Reach). Silver carp were again collected during project F-101-R sampling. Every site in the lower and middle waterway, except Lambie’s Boat Harbor (RM 170.3, Peoria Reach) produced silver carp in 2005. The sample from Bull’s Island yielded the highest collection of total fish (635, 8.3% of the total collected from all 28 sites). Species richness at sites ranged from 25 at Hennepin Island to 13 at Turkey Island (RM 148.0, La Grange Reach). Species richness of the lower, middle, and upper waterway was 30, 44, and 42 respectively. In 2005, cyprinid numbers continued to remain relatively high in the upper waterway, with emerald shiner being the most abundant cyprinid making up 9.8% of the total upper waterway catch. Bluegill ranked highest overall in relative abundance for the entire upper waterway (28.9%) and first in all three reaches as well. Bluegill catch percentages for Dresden, Marseilles, and Starved Rock reaches were 11.6%, 8.6%, and 8.7%, respectively. Important sport fish species such as bluegill, largemouth bass, and channel catfishwere collected in all six waterway reaches in 2005. Bluegill catch per unit effort in number (CPUEN) ranged from 164.00 in Dresden reach (upper waterway) to 9.85 in La Grange Reach (lower waterway). Largemouth bass CPUEN ranged from 41.00 in Starved Rock Reach (upper waterway) to 0.54 in La Grange reach (middle waterway). Channel catfish CPUEN ranged from 7.03 in Alton reach (lower waterway) to 0.41 in Marseilles Reach (upper waterway). In terms of pounds of fish collected per hour (CPUE W), silver carp ranked first over all reaches comprising 20.3% of the total biomass. Silver carp also ranked first in Alton and La Grange Reaches and comprised 8.4% and 6.7% of the total catch in weight, respectively. Bigmouth buffalo ranked first and comprised 5.4% of the total catch in weight for Peoria reach with a CPUEw of 18.19 pounds per hour. Smallmouth buffalo ranked first and comprised 1.0% of the total catch in weight for Starved Rock reach, common carp ranked first and comprised 2.7% of the total catch in weight for Marseilles reach, while largemouth bass ranked first and comprised 2.9% of the total catch in weight for Dresden Reach with a CPUEw of 9.75 pounds per hour. No fish collected in 2005 exhibited externally visible abnormalities, which may indicate improved water quality, especially in the upper waterway.
|Name||INHS Technical Report 2009 (07)|