Ecological Risk Screening Summary - Big water crayfish (Cambarus robustus) - Uncertain Risk

Cambarus robustus, Big Water Crayfish, is a large crayfish that is native to the Great Lakes and Ohio River drainages in the northeastern and midwestern United States. Introductions have been reported in Ontario, Quebec, Vermont, Connecticut, Michigan, Massachusetts, and New York. There was no information found regarding this species in trade, although bait release is suspected as a pathway for nonnative introductions. No research has been conducted on the impacts of Cambarus robustus where introduced, therefore, the History of Invasiveness is Data Deficient. The climate matching analysis for the contiguous United States indicates establishment concern for this species outside its native range. The climate match was predicted to be high in regions adjoining the native range as well as in scattered areas of the Rocky Mountains. The Certainty of Assessment for this ERSS is Low due to an insufficient amount of information regarding the impacts of introductions and uncertainty about the taxonomic identification of introduced populations. The Overall Risk Assessment Category for Cambarus robustus in the contiguous United States is Uncertain.

Species that are considered uncertain risk need a more in-depth assessment beyond the Risk Summary to better define the species’ risk to U.S. environments.