Non-native ﬁsh introductions in the Czech Republic – species inventory, facts and future perspectives By J. Musil 1 , P. Jurajda 2 , Z. Ada´mek 3 , P. Horky´ 1 and O. Slavı´k 1 1 Department of Aquatic Ecology, T. G. Masaryk Water Research Institute, Prague, Czech Republic; 2 Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Brno, Czech Republic; 3 Department of Aquaculture and Hydrobiology, Research Institute of Fish Culture and Hydrobiology Vodn ˇany, University of South Bohemia in C ˇ eske´ Bude ˇjovice, Vodn ˇany, Czech Republic Summary The Czech Republic has experienced a number of inter- and intra-continental introductions (42 introduced species total), with 29 species historically conﬁrmed and 20 species still present in the wild. Fourteen species have become established, representing 27% of the current ﬁsh fauna. Pond aquaculture and recreational ﬁsheries are the two major pathways of introduction and spread, and they are responsible for 80% and 36% of all introduced ﬁsh, respectively. Over the last decade, there has been a signiﬁcant increase in the management practice of stocking recreational ﬁsheries with non-native ﬁsh, particularly alarming in salmonid waters. Pond aquaculture is associated with high risk in terms of the numbers of uninten- tional ﬁsh introductions; all species introduced as contami- nants of carp stocks have become established (Lepomis gibbosus, Ameiurus melas) and then widespread (Pseudorasbora parva, Carassius gibelio) and have been evaluated as invasive. Here, the historical chronology and facts regarding ﬁsh introductions in the Czech Republic are given, in addition to the current distribution of established populations. Present issues and future perspectives concerning the control of non- native ﬁsh and are brieﬂy discussed. Introduction Human interventions are responsible for many species becom- ing extinct, critically endangered or vulnerable, especially in freshwater ecosystems (e.g. Cambray, 2003). Freshwater ﬁsh are threatened by habitat fragmentation and degradation, overexploitation and species introductions and translocations (e.g. Moyle and Light, 1996; Cowx and Collares-Pereira, 2002; Leprieur et al., 2006). The loss of aquatic biodiversity caused by non-native species has been reported many times (e.g. Vitousek et al., 1997; Gido and Brown, 1999; Bianco and Ketmaier, 2001; Cowx and Collares-Pereira, 2002). Non-native species are presently considered as probably the greatest threat to biodiversity conservation after habitat destruction (Cam- bray, 2003). The international community has recognised the need to protect biodiversity (e.g. IUCN Red List), and biodiversity conservation has become politically important (Cowx and Collares-Pereira, 2002). In this context, European Union countries are engaged in avoiding or mitigating any activities that might potentially result in adverse eﬀects on ecosystems (e.g. WDF 2000 ⁄ 60 ⁄ EC, Habitats Directive 92 ⁄ 43 ⁄ EEC, Council Regulation 708 ⁄ 2007). The Czech Republic has experienced a number of inter- and intra-continental species introductions and translocations; the stocking of non-native species in the wild is a widespread management practice. The purpose of this study is: (i) to provide a comprehensive inventory of all non-native species ever introduced into the Czech Republic, with the current distribution of known established populations and (ii) to explore pathways by which species are likely to be introduced and how these pathways contribute to the number of non- native species present in the wild, and (iii) the recent use of non-native ﬁsh is examined and ecological impacts are reviewed to show how the present status of non-native ﬁsh is likely to threaten aquatic ecosystems, with a brief discussion of future perspectives and the need for ecosystem-based manage- ment. Materials and methods Inventory of non-native ﬁsh introductions The present revision of the non-native ﬁsh of the Czech Republic (Table 1) includes all species of trans-boundary introduction origin, excluding reintroduced and translocated species from within country, occasional records of subtropical and tropical aquarium ﬁsh, and species likely to have been native historically or known in nearby, connecting river systems: (i) Danube river basin – Russian sturgeon, Acipenser gueldenstaedtii; stellate sturgeon, Acipenser stellatus; and ship sturgeon, Acipenser nudiventris (Kottelat and Freyhof, 2007); (ii) Elbe river basin – Northern whiteﬁn gudgeon, Romanogo- bio belingi (Kottelat and Freyhof, 2007). As the origin of carp (Cyprinus carpio) on the European continent remains disputed (Froufe et al., 2002), it was included in the list of species. Based on recent revision by Van Damme et al. (2007), bitterling (Rhodeus amarus) is also included among non-native ﬁsh. All deﬁnitions used to classify and evaluate the species and population status (Table 1) follow criteria summarised by Copp et al. (2005a). Data collection and analyses To analyse the history and pathways of introductions and speciesÕ establishment status and to review ecological impacts associated with non-native ﬁsh in the wild, both historical information and recent information were processed from all available bibliographic sources. Only a selection of the most important literature is given due to limited space. Data on the recent distribution of established ﬁsh populations in the wild (Fig. 1) were extracted from S ˇ anda (2006) and Hanel and Lusk J. Appl. Ichthyol. 26 (Suppl. 2) (2010), 38–45 doi: 10.1111/j.1439-0426.2010.01500.x Ó 2010 Blackwell Verlag, Berlin ISSN 0175–8659 Applied Ichthyology Journal of