AUTHORS: Eric R. Larson, University of Illinois; Caitlin C. Bloomer, University of Illinois; Don Eaton, Minnesota Department of Natural Resources; Denver Link, University of Minnesota; Reagan Oller, University of Illinois; Gretchen J.A. Hansen, University of Minnesota
ABSTRACT: The signal crayfish (Pacifastacus leniusculus), native to the Pacific Northwest of North America, is among the most invasive crayfish species globally, with populations widely established throughout Europe and Japan. Signal crayfish have never been detected from eastern North America, although previous research has identified the Upper Mississippi and Great Lakes watersheds as environmentally suitable for this invasive species. In October of 2023, ten signal crayfish individuals were trapped from a lake in west central Minnesota by a commercial bait harvester. We report here molecular surveillance of this possible, incipient signal crayfish invasion. Mitochondrial DNA (mtDNA) barcoding identified the collected crayfish as P. leniusculus, resembling non-native populations of the species known from the Lake Tahoe area of California and Nevada. We collected environmental DNA samples in summer and autumn of 2024, including through sampling kits distributed to lake association volunteers, and used quantitative PCR with a signal crayfish-species primer and probe assay to survey for evidence of this species in the original lake and neighboring freshwater ecosystems. Our preliminary results are relevant to management responses for this novel, potentially impactful invasive species in the Midwest.
