Invasive Crayfish in Maine: Potential Impacts on Fish, Plants and Benthic Invertebrates

Presentation (pdf document)

Dr. Karen A. Wilson, Aquatic Systems Group and the Department of Environmental Science, University of Southern Maine, 350 Commercial St., Portland, Me 04101, 207-228-1674, kwilson@usm.maine.edu

There are over 350 crayfish species in North America, most with discreet native distributions and low range overlap between species. More northerly regions have far fewer species, but the activities of humans, and, in some cases, natural range expansions, have resulted in more and more species establishing in northern areas. Most of these crayfish species are introduced through “bait bucket liberations,” and some escape from aquaculture facilities. Crayfish are trophic generalists, eating everything from plant material to benthic insects to fish and their eggs. As a result, when crayfish are abundant, they can have significant effects on aquatic food webs. In this talk I will discuss the long-term negative impacts of one particularly invasive species, the rusty crayfish, on northern Wisconsin Lakes where they became ultra-abundant in the 1980s and 1990s. I will then discuss the known distribution of rusty crayfish and other invasive crayfish in Maine, and the potential for additional spread in the state. I will conclude with reasons why the State of Maine should consider a crayfish control program to prevent the introduction and spread of invasive crayfish species similar to efforts to control invasive aquatic plants.