Habitat Selection And Spatiotemporal Patterns Of Movement In A Fluvial Population Of White Sucker (catostomus Commersoni) - Jeremy Michael Shiflet

The responses of fishes to ongoing stream restoration projects throughout the southeastern United States are largely unknown. White suckers are thought to be an important competitor with brook trout, a target restoration species, and their response to canopy cover could be an important predictor of restoration success. Because stream restoration can be lengthy, I simulated future canopy cover by artificially shading five pools (80 to 90%). I then measured the short-term (30 days) responses of white sucker populations in control (un-shaded) and treatment (shaded) pools. After 30 days, white sucker densities (#/100m2) remained similar in un-shaded (control) pools but were significantly reduced in artificially shaded pools. Recapture rate of tagged white suckers was significantly different between un-shaded (42%) and shaded pools (17%). The percentage change in density was not significantly different between un-shaded and shaded pools after 30 days. Mean total length of captured white suckers was similar among groups and proved not to be a confounding factor. I also followed a small group of white suckers using radio transmitters to monitor non-spawning movements. Radio tagged white suckers were found to be predominantly sedentary with a few long-distance movements interspersed. The largest movement observed for a white sucker in this study was 1,300 m upstream. A preference was not found for either upstream or downstream movement. Estimates of average daily movement for 24 radio tagged white suckers averaged 0 m with no significant differences in average daily movement among the 24 fish. A significant positive correlation was found between daily white sucker movement and average daily stream flow. Instream PIT tag antennas recorded 455 white sucker movements. Movements after sunset accounted for 92% of all records. This project gathered insightful knowledge of the preferred habitat and movement tendencies of a fluvial population of white sucker. As riparian canopy matures along this restored stream white suckers may chose to leave the study in search of un-shaded pools. A large exodus of white suckers may alter existing fish communities in the study area. The magnitude and direction of these alterations are unknown and monitoring is necessary and will be continued.

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