PARENT SESSION
Oral Session # 44: Resource Management I: Theory; Aquatic Systems.
Presiding: C Swan
Wednesday, August 6. 8:00 AM to 11:30 AM, SITCC Meeting Room 106.
Experimental removal of exotic rainbow smelt (Osmerus mordax) from Sparkling Lake, Wisconsin.
Roth, Brian *,1, Lischka, Stacy1, 2, Hrabik, Thomas2, Krueger, Damon2, Mercado-Silva, Norman1, Magnsuon, John1, 1 Center for Limnology, Madison, Wisconsin, USA2 Department of Biology, Duluth, Minnesota, USA
ABSTRACT- As part of a larger National Science Foundation-funded research project, we are attempting to eradicate the exotic rainbow smelt (Osmerus mordax) from Sparkling Lake, Vilas County, Wisconsin. Rainbow smelt have caused the near extirpation of native yellow perch (Perca flavescens) and cisco (Coregonus artedi) as well as a collapse in natural walleye ( Stizostedion vitreum)reproduction in Sparkling Lake and other lakes in northern Wisconsin. Remediation is an attractive option, but biocides and pathogen introduction are undesirable. As a consequence, we designed an eradication program based on selective overexploitation of spawning smelt and increased predation on both juvenile and adult populations. We used gillnets to capture smelt during the last three summers and fyke nets to capture reproductive adults during the last two springs. In addition, the Wisconsin Department of Natural Resources has stocked more than 400 adult walleye, 5,500 extended growth fingerlings, and 1.3 million fry in Sparkling Lake the last three years as an effort to increase the predator population. Fishery regulations on Sparkling Lake were altered to protect adult walleye. We used a mass-balance model and fish Bioenergetic simulations to assess the relative effect of gillnets, fyke nets, and predators on the smelt population, estimated prior to the eradication effort at over 750,000 fish. Our results indicate that the current walleye population is capable of consuming only a small fraction of the smelt population. Gillnets captured more smelt than predators, but are ineffective compared to fyke nets, which captured nearly 500,000 smelt the last two springs. The long-term effects of increased predation have yet to be determined. However, Bioenergetics simulations reveal that the walleye population must be substantially increased to successfully maintain a low smelt population.
Key words: rainbow smelt, eradication, exotic species, walleye