Ecological Risk Screening Summary - Signal Crayfish (Pacifastacus leniusculus) - High Risk

Species that are considered high risk have a well-documented history of invasiveness in at least one location globally and are of establishment concern for the contiguous United States based on a climate matching analysis.

Pacifastacus leniusculus, signal crayfish, is a crustacean that is native to the Columbia River basin in the Northwestern United States and southwestern Canada. This species has high fecundity and a long lifespan. P. leniusculus is a carrier of Aphanomyces astaci, the crayfish plague, a listed disease according to the World Organisation for Animal Health. It has been introduced and established nonnative populations outside its native range in the United States, Europe, and Japan. Impacts of these introductions include reductions in the biomass of macroinvertebrates and decreases in the abundance of native crayfish, fish, and amphibians. Eleven States may regulate this species to some extent. The History of Invasiveness for Pacifastacus leniusculus is classified as High. The climate matching analysis for the contiguous United States indicates establishment concern outside its native range. Areas of high match were found in the west, including the species’ native range. Most of the remainder of the contiguous United States had medium climate matches except for areas of southern Florida and the Gulf Coast. The Certainty of Assessment for this ERSS is classified as High due to the amount and quality of information available. The Overall Risk Assessment Category for Pacifastacus leniusculus in the contiguous United States is High.