Non-native fish introductions in the Czech Republic - species inventory, facts and future perspectives.

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 unintentional fish introductions; all species introduced as contaminants 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.