Slipping past the barricades: the illegal trade of pet crayfish in Ireland

Abstract

Abstract:The island of Ireland is the largest region in western Europe with no populations of non-indigenous crayfish species, and the native white-clawed crayfish, Austropotamobius pallipes, is widespread. But non-indigenous crayfish are available through the pet trade in Ireland, and the release of pet crayfish is a major route for introducing crayfish into natural ecosystems. Monitoring online classified-advertising websites provided evidence for three non-indigenous crayfish species owned and traded in the Republic of Ireland—Procambarus clarkii, Cherax quadricarinatus and Cambarellus patzcuarensis—in addition to Procambarus fallax f. virginalis, previously determined to be available in the pet trade in the Republic of Ireland. The risks associated with introductions of C. quadricarinatus and C. patzcuarensis in Ireland have not yet been assessed. The invasive potential for both may be limited by low cold tolerance, but C. patzcuarensis is a potential vector for crayfish plague, and C. quadricarinatus may outcompete native A. pallipes in aggressive interactions. The number of species available in Ireland is smaller than in most other European countries, but the number of advertisements per capita and species available in the Republic of Ireland was higher than in England, where one species is legal. This suggests legislation may limit initial imports, but individual pet owners or small businesses continue to sell and trade crayfish that have been transported to Ireland.