Modeling smallmouth bass consumption of round goby in Lake Erie: implications for predator growth and contaminant transfer.
Gene W. Kim, Ph.D. student, Roy A. Stein, Elizabeth A. Marschall, and Susan W. Fisher (Department of Entomology ). Funded by: Ohio Sea Grant.

Exotic species continue to invade and spread. Recently, round gobies have spread rapidly throughout all of the Great Lakes. The invasion by round gobies into areas occupied by zebra mussels Dreissena polymorpha creates problems. Singularly, each of these species can have negative effects on native species via consumption and competition for limited food resources. Taken together, however, these two exotic species can greatly alter energy and contaminant dynamics. They can return contaminants destined for sediment deposition back into the sport-fish food web. Ingestion of zebra mussels by round gobies can complete a food chain from contaminated algae and sediments to zebra mussels to round gobies to smallmouth bass. The recent population explosion and inclusion of round gobies into diets of many sport fishes has raised concern among fishery managers. This concern arises from uncertainty about how the inclusion of round gobies will affect predator growth rates and contaminant concentrations in this growing smallmouth bass fishery.

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Gene Kim can be emailed at kim.985 "at" osu.edu

Matt Gearhiser with a smallmouth bass in an observation chamber. All the experiments were video taped for later analyses.

A smallmouth bass (left) and round goby (right). Round gobies are non-indigenous to the Great Lakes, but are now extremely abundant.

Cristal Williams checking water quality in a temporary holding tank for smallmouth bass used in the behavioral experiments.

To address this, we have completed and are working on the following:

• We have completed a laboratory behavior experiment, to assess preference by smallmouth bass on round gobies. These results have been presented at scientific meetings and manuscript is being written.
   
• We have completed bomb calorimetry for about 150 round gobies from Lake Erie. We will combine these data with our experimental data.
   
• In 2001-3, we completed field sampling of our sites for smallmouth bass, round gobies, and zebra mussels. We have finished analyzing these samples for PCB concentrations and are statistically analyzing the data and preparing a manuscript.
   
• Dietary PCB uptake in smallmouth bass fed PCB-spiked round gobies. This experiment is completed. About 30 smallmouth bass were fed PCB-spiked round gobies for a 30-d uptake and a 105-d depuration period. The PCB analysis is complete. We currently are statistically analyzing the PCB concentrations and preparing a manuscript.