**The title, authors, and abstract for this completion report are provided below.  For a copy of the completion report, please contact the GLFC via e-mail or via telephone at 734-662-3209**



Round goby and dreissenid effects on young-of-the-year smallmouth bass

Daniel D.Wiegmann2, Jeffrey G. Miner3, Christopher J. Winslow2
2Graduate Program in Ecology, Evolution, and Conservation Biology
Department of Biological Sciences
Bowling Green State University
Bowling Green, OH 43402

3 jminer@bgsu.edu

4 cjwinsl@bgsu.edu



The effects of invading species on community structure depend upon how invasives affect particular life stages of native species. Timing of recruitment and factors that regulate smallmouth bass (Micropterus dolomieu) population size are poorly understood, especially in the presence of invasives. To quantify overall interactions and thus predict population shifts on this important sport fish in Lake Erie, we focused our research on an early life stage (young-of-the-year smallmouth bass, YOYSMB). We quantified how two invasives, dreissenids (zebra mussels Dreissena polymorpha and quagga mussels D. bugensis) and round gobies (Neogobius melanostomus, RG), affect growth and behavior of YOYSMB. Dreissenids can indirectly aid YOYSMB by providing structural complexity increasing invertebrate prey. RG may directly influence YOYSMB by interfering with habitat use (impacting foraging/increasing
predation) and indirectly by reducing invertebrate food found among dreissenids. Mesocosms in and along Lake Erie, varying densities of YOYSMB, dreissenids, and RG were designed to quantify the effects of dreissenids and RG on the growth of YOYSMB. Additionally, analysis of diet and a behavioral
trial were used to assess habitat use and possible alterations to YOYSMB behavior by RG – does eviction from refuges and the benthos alter YOYSMB diet and increase exposure to predators? The experiments included measures of high intraspecific competition among YOYSMB and interspecific competition between YOYSMB and RG.

The results of this study suggest that intraspecific and interspecific competition with RG are nearlyequivalent in terms of their effect on YOYSMB growth. Because Lake Erie RG are at high densities, competitive effects on YOYSMB are probably substantial. Diet data suggest that YOYSMB diet is altered by having RG present in the community. RG force behavioral and therefore diet changes similar to those seen under high levels of intraspecific competition. Results from our experiments provide essential data necessary to address cumulative effects (throughout ontogeny) of invasives and provide fisheries management with tools to assess impacts.