Invasive Pathways and Prevention: The North American Great Lakes as a Case Study

David Lodge
U.S. National Invasive Species Advisory Committee
Department of Biological Science
P.O. Box 369
University of Notre Dame
Notre Dame, IN 46556-0369
Telephone: (219) 631-6094
Fax: (219) 631-7413
lodge.1@nd.edu

Research on invasive species has often been reactive, quantifying the ecological and economic costs of established invaders. Research has rarely led to successful control or mitigation of nuisance invaders. Even where control is possible, it is expensive, in part because efforts must continue indefinitely. Extirpation is usually impossible. To avoid permanent ecological change or recurring economic costs, research on earlier invasion stages is needed. In particular, increasing research on pathways that transport invasive species is essential to inform prevention. Such research is necessarily interdisciplinary because biological research must be guided by knowledge of trading routes, transportation methods, mathematical modeling, and economic analysis. Interdisciplinary risk assessments must include explicit consideration of pathways, predictions of the identity of future invaders, and estimates of future ecological and economic impacts. Current methods of risk assessment used in North America often fall short of these goals.

The Great Lakes provide a case study in which the identity of historic and current pathways is largely known. In the Great Lakes, steps are being taken to reduce the number of organisms transported by some pathways, e.g., ships' ballast, canals. However, inadequate scientific knowledge has meant that some policy decisions and regulatory actions, e.g., on ballast water management, have been less effective than originally hoped. Further policy development regarding ballast, canals, aquaculture, and bait buckets requires much more sophisticated research underpinning. In many cases, the scientific capacity exists, but has not been adequately mobilized in support of invasive species prevention. In other cases, theoretical and empirical research methods need further development. Greater collaboration among scientists, relevant industries, policy makers, and regulatory agencies is required to prevent invasions.

For more information, see:

Mills, E. L., J. H. Leach, J. T. Carlton, and C. L. Secor. 1993. Exotic species in the great lakes: a history of biotic crises and anthropogenic introductions. Journal of Great Lakes Research 19: 1-54.

Kolar, C. S. and D. M. Lodge. 2001. Progress in invasion biology: predicting invaders. Trends in Ecology and Evolution 16: 199-204.