Between 4 September and 1 October 2007, 27 sites on the Illinois River waterway and one site in Reach 26 of the Mississippi River were electrofished to monitor fish communities. A total of 8,768 fishes representing 60 species (plus three hybrids) from 14 families were collected during 26.34 hours of sampling. Collections made in 2007 indicated continued high catches of gizzard shad, emerald shiner, and bluegill throughout most of the Illinois River waterway. Common carp and goldfish, which were once dominant, continue to exhibit relatively low in catch rates throughout the Illinois River waterway, contributing only 2.8% of the total catch and 2.9% of the Illinois River Waterway catch. Southern redbelly dace were collected for the first time during project F-101-R sampling along the waterway in 2007. A single specimen was collected from Henry Island (RM 193.8) in Peoria Reach. Silver carp were again collected during project F-101-R sampling at most lower and middle river sites. Silver carp were the most abundantly collected species throughout the waterway in 2007 with 2,921 fish collected comprising 33.3% of the total catch. Silver carp collections in La Grange and Peoria reaches were the highest observed for this species since it was first recorded in 2002. Silver carp collections in La Grange and Peoria reaches were also the highest catches ever recorded for a single species in both reaches in F-101-R sampling. Bighead carp and round goby were collected at new sites in 2007 illustrating further expansion of these invasive species. Bighead carp were collected at Bull’s Island (RM 240.8) in Starved Rock Reach marking the furthest upstream collection of this species in F-101-R sampling. Round goby were collected at two sites, Clark Island (RM 215.3) and Hennepin Island (RM 207.7) in Peoria Reach, marking the furthest downstream collection of this species in F-101-R sampling. The sample from Lambie’s Boat Harbor (RM 170.3, Peoria Reach) yielded the highest collection of total fish (2,293, 26.2% of the total collected from all 28 sites), while the sample from Moore’s Towhead produced the lowest total fish (43, 0.5% of the total collected from all 28 sites). Fish species richness at sites ranged from 27 at Hennepin Island to 10 species at Moore’s Towhead. Fish species richness of the lower, middle, and upper waterway was 32, 49, and 38, respectively. Cyprinid catches continued to remain relatively high in the upper waterway, with emerald shiner being the most abundant, making up 19.6% of the total upper waterway catch. Emerald shiner catch percentages for Dresden, Marseilles, and Starved Rock reaches were 0.9%, 30.6%, and 29.9%, respectively. Important sport fish species such as bluegill, largemouth bass, and channel catfishwere collected in all six waterway reaches in 2007. Bluegill catch per unit effort in number of fish collected per hour (CPUEN) ranged from 116.5 in Dresden Reach to 4.36 in La Grange Reach. Largemouth bass CPUEN ranged from 35.0 in Dresden Reach to 0.2 in La Grange reach. Channel catfish CPUEN ranged from 13.1 in La Grange Reach to 3.6 in Marseilles Reach. In terms of pounds of fish collected per hour (CPUE W), the collection from Peoria Reach yielded the highest biomass at 196.4 pounds per hour while the collection from Marseilles Reach yielded the lowest biomass at 32.6 pounds per hour. Silver carp biomass ranked first over all reaches at 24.1 pounds per hour, comprising 23.5% of the total biomass. Silver carp also ranked first in CPUEW for Alton, La Grange, and Peoria reaches. Catch in weight for silver carp in each reach was 15.2 (40.9% of the total), 32.8 (33.8% of the total), and 46.3 (23.6% of the total), respectively. Bighead carp ranked first and comprised 43.1 % of the total catch in weight for Starved Rock reach with two individuals captured. Channel catfish ranked first in Marseilles and comprised 36.8% of the total catch in weight with a CPUEW of 12.0. Common carp ranked first in and comprised 34.0% of the total catch in weight with a CPUEW of 32.1 for Dresden Reach. Sixteen fishes were observed to have externally visible abnormalities in 2007. Abnormalities were found in fishes of all reaches except La Grange.
|Name||INHS Technical Report 2008 (10)|