Risk assessment of the crayfish pet trade based on data from the Czech Republic

The pet trade in freshwater crustaceans, including crayfish, has grown rapidly in recent decades and become an important pathway for introducing new non-indigenous species into Europe. This paper provides the first overview of non-indigenous crayfish species (NICS) traded as ornamental and their potential impact in the Czech Republic, which is the second leading importer into Europe. The paper presents a full list of traded crayfish species, their market availability, and trade names or misnomers used in the country. In total, 27 crayfish species from all three families are advertised and marketed, of which Astacus astacus is the only indigenous species. Only three NICS were recognized as very common on the market. The invasiveness and risk associated with ornamental crayfish trade were assessed using the Freshwater Invertebrate Invasiveness Scoring Kit. Five NICS were classified into the high-risk category, the highest score being for Procambarus fallax f. virginalis. The invasiveness of crayfish indigenous to North America is significantly greater than that of crayfish from the rest of the world, and therefore regulation in this regard is recommended.