Ecological Risk Screening Summary - Yabby (Cherax destructor) - High Risk

Species that are considered high risk have a well-documented history of invasiveness in at least one location globally, and a high or medium climate match to the contiguous United States.

Cherax destructor is a freshwater crayfish native to Southeastern Australia. C. destructor is an opportunistic feeder that can be found in a wide range of habitats and water conditions. This species is common in aquaculture and is gaining popularity as an aquarium species and in research. C. destructor is used as bait by recreational anglers and is sold live as a delicacy for restaurants in Australia and Europe. The history of invasiveness is high. C. destructor has been introduced for aquaculture and possibly as discarded bait from recreational fishermen. It has been reported as introduced and established in Western Australia, Tasmania, Italy and Spain. There are currently no reported introductions of this species in the United States. C. destructor is listed as federally injurious by USFWS and prohibited from importation; it is also a prohibited species in multiple States. It has been reported as a possible vector for crayfish plague and Thelohania parastaci. There is evidence from Australia that introduction of C. destructor has resulted in thelohania infection in the native, endemic crayfish. In addition, it rapidly expands its range after introduction and has been shown to compete with native crayfish species resulting in species displacement and it contributed to the listing of a native species as endangered. C. destructor can damage property, mainly farm irrigation channels with its burrowing behavior; burrows in the banks collapse when water levels drop, destabilizing the bank. The overall climate match for the contiguous United States was high. Most of the contiguous United States had medium to high climate matches; low matches were found in northern New England, Midwest, Plains, and areas of the Pacific Northwest. The certainty of assessment is high due to abundant and high quality information. The overall risk assessment category for Cherax destructor is high.