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Mayo, K.R., J.H. Selgeby, and M.E. McDonald, 1998. A Bioenergetics Modeling
Evaluation of Top-down Control of Ruffe in the St. Louis River, Western Lake Superior,
US EPA.
Reprinted from Journal of Great Lakes Research (1998) 24 (1998) 24(2):
329-342
A Bioenergetics Modeling Evaluation of Top-down
Control of Ruffe in the St. Louis River, Western Lake Superior
Abstract
Ruffe (Gymnocephalus cernuus), were accidentally introduced into the St. Louis
River estuary, western Lake Superior, in the mid 1980s and it was feared that they might
affect native fish through predation on eggs and competition for forage and habitat. In an
effort to control the abundance of ruffe and limit dispersal, a top-down control strategy
using predators was implemented in 1989. We used bioenergetics modeling to examine the
efficacy of top-down control in the St. Louis River from 1991 to 1994. Five
predators-northern pike (Esox lucius), walleye (Stizostedion vitreum vitreum),
smallmouth bass (Micropterus dolomieui), brown bullhead (Ictalurus nebulosus),
and yellow perch (Perca flavescens)-were modeled to determine their consumption
of ruffe and four other native prey species-spottail shiner (Notropis hudsonius),
emerald shiner (Notropis atherinoides), yellow perch (Perca flavescens),
and black crappie (Pomoxis nigromaculatus). Although predators ate as much as 47%
of the ruffe biomass in 1 year, they were not able to halt the increase in ruffe
abundance. The St. Louis River is an open system that allows predators to move freely out
of the system, and the biomass of managed predators did not increase. A selectivity index
showed all five predators selected the native prey and avoided ruffe. The St. Louis River
has several predator and prey species creating many complex predator-prey interactions;
and top-down control of ruffe by the predators examined in this study did not occur.
Contact: Kathleen Mayo, US EPA, Reg 9, 75 Hawthorne Street CMO-3, San
Francisco, CA 94105
Keywords: Ruffe, Bioliogical_control, Population_dynamics
Product Type: Research, Control
User Type: Resource_Management
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