Use of artificial structure as fish habitat in a western Illinois reservoir (Spring Lake, Macomb, Illinois)

My study was conducted at Spring Lake, a drinking water reservoir in McDonough County, Illinois, that is managed by the Illinois Department of Natural Resources and allows for public access fishing. I constructed three types of artificial fish habitat (2-, 6-, and 10-branches) out of polyvinylchloride (PVC) in an effort to concentrate fish (especially white crappie Pomoxis annularis) for angler harvest to help increase the quality of the fishery. Nine pairs of structures (3 of each branch type) were placed in Spring Lake and sampled with static DC electrofishing one time each month from May through October 2008. A nearby site (within 10 meters) with similar depth but no structure was shocked along with each structure to act as a control.;I collected 11 fish species and 875 total fish. T-tests were used to compare catch rates and mean size between the PVC structures and the control areas. The mean catch was significantly higher on the PVC structures compared to control sites for bluegills Lepomis macrochirus, white crappie, and largemouth bass Micropterus salmoides, but not for gizzard shad Dorosoma cepedianum. There was no significant difference in the mean size for all 4 species between PVC and control sites. A linear regression revealed no relationship between the number or size of fish and the number of branches on the PVC structures. Bluegills used the PVC structures significantly more in the dam area of Spring Lake than in other areas of the lake, while gizzard shad used the PVC structures significantly more in the west end of the lake. These results suggest that PVC structures, which are non-organic and thus do not degrade water quality, can be effective fish attractors in drinking water reservoirs.