A "Frankenstein Effect," the suite of moral and ethical problems encountered when man tries to improve on nature, may soon revisit Lake Superior with a vengeance not seen since the accidental introduction of the sea lamprey. I speak not of the eurasian ruffe, Gymnocephalus cernuus, whose population now numbers in the millions in western Lake Superior, but of well-meaning fishery biologists' attempts to control this exotic invader.

Since its probable introduction via ballast water in the early or middle 1980's, the ruffe has established a breeding population in the Duluth-Superior harbour and has progressively extended its range eastward along the south shore of Lake Superior as far as the Ontonagon River in Michigan. It was also found this fall in the Mission River and in Thunder Bay, Ontario, in the former docking slip of the vessel "Incan Superior."

In response to the ruffe invasion, population irruption and range extension, the Ruffe Control Committee of the national Aquatic Nuisance Species Task Force is proposing an experimental program of chemical control to reduce the rate of the species' downstream advance in the Great Lakes. This poses a difficult dilemma for resource management biologists and all others concerned with the environmental quality of the Great Lakes.

If the European experience with introduced ruffe populations is repeated here, it seems likely that ruffe will be detrimental to our native fishes, especially yellow perch and the whitefishes. We do not anticipate extirpation of these native fish, but there may be substantial reductions in their abundance. This would create special hardships for these fisheries in Lakes Michigan, Huron and Erie, thus, the impetus to attempt to control this nuisance species.

We know we can kill perhaps 50-95% of stream-dwelling and estuarine ruffe with chemical piscicides, but not without sacrificing some of the native fishes in the habitats jointly occupied with ruffe. We also know that recolonization by ruffe of streams thus treated may recur as soon as the year following treatment. Even a 95% kill, impressive as it sounds, is not sufficient to prevent rapid recolonization from adjoining populations.

Ecologists are confident that perturbed communities of organisms are more susceptible to invasion by exotic species than are communities whose native species are healthy and diverse. This is, after all, the basis for plowing agricultural land (native prairie grasses) to provide a competitive advantage for exotic plants (cultivars of wheat and corn). Will chemical ruffe control, including some adverse effects on native fishes, stress these aquatic communities so that future ruffe control will be even more difficult and costly? We know we cannot eradicate ruffe throughout their present range in Lake Superior with any known control methods. Does this imply that once we begin to exert partial controls on the ruffe population, we will be forever obligated to continue these controls, and to accept the associated impacts on native fauna? The ballast water exchange programs in offshore waters of the Atlantic Ocean and internal to Lake Superior in areas known to be inhabited by ruffe may be effective in preventing further introductions to the Great Lakes, but many ecologists believe that it is only a matter of time before ruffe make their way into the lower lakes, and perhaps also into inland waters. If we do nothing other than preventing new introductions of ruffe, will the Lake Superior population come into balance with our established fauna at some level below the numbers already observed in the Duluth-Superior estuary?

Contrast this with the lamprey control problem. Here, we know we could not rebuild or sustain lake trout populations in the absence of effective lamprey control. We have succeeded in restoring Lake Superior lake trout to productive levels through intensive stocking and lamprey controls that began over three decades ago. Lake whitefish populations in Lakes Michigan and Huron have responded dramatically to lamprey reductions. We also know that TFM, the primary lamprey piscicide, can attain a very high degree of lamprey control with minimal impact on native fishes (with the exception of native lampreys), and very modest impact on benthic invertebrates. Lamprey control in the Great Lakes is certainly one of the most successful programs of its kind, and we still anticipate having to continue it indefinitely.

The time has come to choose a path for future management of Great Lakes resources. Meetings will soon be held in the region to receive public comment on the proposed ruffe control program. Will we engage in a control activity that we believe to be futile simply for the purpose of "buying time" until we can devise methods that are more environmentally benign? Or will we accept, for now, the consequences of "biological pollution" already wrought on the system through our negligence in applying a zero discharge philosophy?

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Date created: December 15, 1995
Last modified: December 15, 1995
Copyright © 1995, George R. Spangler
Maintained by: G. Spangler
GRS@fw.umn.edu