PS 11-152 - Evaluating the prevalence of crayfish species and owner knowledge in the pet retail trade throughout the Great Lake Basin

Abstract: Crayfish found in the global aquarium trade include several invasive species that are known to displace native crayfishes, have pronounced negative effects on aquatic ecosystems, and serve as disease vectors. Within the Great Lakes Basin, the sale of crayfish is inconsistently regulated across jurisdictions and poorly covers species with great morphological variability such as rusty crayfish (Faxonius rusticus), red swamp crayfish (Procambarus clarkii), yabbies (Cherax spp.), and the parthenogenic marbled crayfish (P. virginalis), which are easily confused with the highly marketable Florida Everglades crayfish (P. alleni). Currently there is little understanding of species prevalent in the aquarium trade. When combined with varying identification skills of aquarium retail employees and inconsistent regulatory structures, there is a substantial risk of human-facilitated release associated with the retail pet pathway. We hypothesized that the pet retail trade in the Great Lakes Basin is a major invasion pathway for non-native crayfishes, which would be associated with high prevalence and morphological variety of crayfish in stores, diverse taxonomic nomenclature and trade names, and low shop owner awareness of crayfish biology and legality. We surveyed over 400 aquarium retailers across the Great Lakes Basin states to document: 1) crayfish species sold, 2) the names crayfish species were sold as, and 3) the knowledge or awareness of store employees regarding state-specific invasive crayfish species. We found six crayfish species including native and non-native crayfishes; however, the distribution of these species was not equal across states. 100 stores were positive for the presence of non-native crayfishes, representing 25% of the stores we surveyed. Additionally, we recorded a low awareness of crayfish species of concern amongst pet store employees. We conclude that pet stores serve as an invasion pathway within the Great Lakes Basin. We identify two species likely to be broadly introduced without stronger regulation including P. clarkii, which may easily escape detection due to the diverse colors and names available for this species, and P. virginalis owing to its close resemblance to female P. alleni. We further recommend surveillance efforts be increased in certain states to address low overall shop owner awareness and high prevalence of these species in the trades.