Introductions of non-indigenous crayfi sh species have had profound ecological impacts in conservation of native crayfi sh species. For example, half of native crayfi sh species in North America pose a conservation concern (Taylor et al. 2007) due, among other factors, to the introduction of non-indigenous crayfi sh (Hill and Lodge 1999, Klocker and Strayer 2004, Lodge et al. 2000a). Introductions of non-indigenous species threaten native and managed ecosystems worldwide (Bradley et al. 2009, Wilcove et al. 1998) and create ecological and economic harm, including loss of native species and alteration of ecosystem functions (general: D’Antonio and Vitousek 1992, Zavaleta 2000, crayfi sh: Gherardi 2013, Twardochleb et al. 2013). The annual cost of damage and control of introduced species can be estimated in billions of dollars (Pimentel et al. 2000, Pimentel et al. 2001, Pimentel et al. 2005). Prevention of future invasions is the most cost effective form of ecosystem management (Broennimann and Guisan 2008, DiTomaso 2000, Mullin et al. 2000, Rejmánek and Pitcairn 2002, Westbrooks 2004) because once non-indigenous species are established, they become diffi cult to eradicate (Genovesi 2005), and this has been particularly true for crayfi sh (Cecchinelli et al. 2012, Frings et al. 2013, Gherardi et al. 2011, Peay et al. 2006).