Brenton, B.D., E.S. Rutherford, K.A. Rose, and D. Singhdermott, 1997.  Individual-Based Model Simulation of the Eurasian Ruffe (Gymnocephalus cernuus) Invasion on Walleye (Stizostedion vitreum) and Yellow Perch (Perca flavescens) Populations in the St. Louis River Estuary, Duluth, MN, U.S.A., University of Michigan, Oak Ridge National Laboratory

Proceedings of the International Symposium on Biology and Management of Ruffe, March 21-23, 1997

Individual-Based Model Simulation of the Eurasian Ruffe (Gymnocephalus cernuus) Invasion on Walleye (Stizostedion vitreum) and Yellow Perch (Perca flavescens) Populations in the St. Louis River Estuary, Duluth, MN, U.S.A.

Abstract
Eurasian ruffe recently invaded North America aquatic ecosystems and were first discovered in the St. Louis River estuary, Minnesota in 1986. Hypothesized effects of ruffe on native percids include depressed growth, abundance, or shift in habitat of yellow perch, and decreased growth of walleye. We used an individual-based bioenergetics model to simulate effects of the ruffe invasion on percid growth and abundance. Initial conditions were derived from St. Louis estuary data and from Oneida Lake, New York, when site-specific data were unavailable. Fifty-year simulations showed that the degree to which walleye prefer yellow perch over ruffe has a pronounced effect on the population dynamics of all three species. When walleye began preying heavily on ruffe at a ruffe-to-yellow-perch abundance ratio (total population of juveniles and adults) of 5, walleye and yellow perch populations were moderately depressed in response to ruffe, and growth rates of all three model species were unaffected. When walleye delayed preying heavily on ruffe until the ruffe-to-yellow-perch abundance ratio was > 40, walleye and yellow perch populations were severely depressed with wide fluctuations in walleye recruitment and survival. We conclude that ruffe will result in moderate to severe declines in native percid abundance dependent upon walleye dietary preference for ruffe.

Contact: Brain D. Brenton, University of Michigan, 212 Museums Annex Building, 1109 N. University, Ann Arbor, Michigan 48109 or bdbrento@umich.edu
Keywords: Ruffe, Population_dynamics, Predators
Product Type: Publications, Conference_proceedings
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