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6 Foreign Nonindigenous Carps and Minnows (Cyprinidae) in the U.S.-A Guide to their Identification Eradication attempts are often poorly documented (typically in the gray or unpublished literature), making it difficult to evaluate their success. Additionally, reports of eradications from selected sites do not always include information on whether the species continued to survive in other parts of the drainage. The confusion and short- age of information complicate the task of tracking and accurately mapping changes in the distribution of introduced populations. For example, Dill and Cordone (1997) reported that a reproducing population of Tench was eliminated from a small farm pond in the Trinity River drainage in California, but did not comment on whether the species was known to exist or was reproduc- ing elsewhere in that drainage. A later report (Moyle 2002) indicated there were no recent records for Tench in the Trinity River. Thus, it is unclear whether the local eradication effort reported by Dill and Cordone (1997) removed the only reproducing population of Tench or whether other reproducing populations of Tench throughout the drainage simply died out over time. Distribution by state,-ln addition to providing the distribution of each species by drainage, we also include distribution information for all 50 states. States color- coded green represent those from which the species has been recorded at least once from natural waters within state borders. 1n some instances, the record of occur- rence may be nonspecific, with no information about the precise drainage or location within the state where the species was reported, released, or captured. In such cases, the entire state is shaded green but no drainage is shaded. 1n contrast to the HUC units described above, the state colors do not provide information concerning the population status of the species (that is, reproduc- ing versus non-reproducing). If a foreign cyprinid is known only from one site in a drainage, then the entire drainage is color coded (either red or pink). Many HUC units cross state boundaries. For additional information on state-by-state occurrence of foreign cyprinids, see appendix A. Water bodies included in the coverage.- Distributions delineated on the maps pertain only to records from the wild, including habitats that are natural (rivers, lakes) or artificial (canals, farm ponds, reservoirs). Maps do not include records based on captive indoor settings or outdoor ponds and tanks at aquaculture facilities, as the focus of the database is to document wild-caught non-native fishes. However, it has become increasingly evident that documentation of the location of aquaculture facilities as well as the fish stocks cultured there is important due to the likelihood of escape from outdoor ponds to nearby open systems. Unfortunately, this data is often difficult to obtain. Source of map distribution data.-Data used to create these maps were primarily derived from the Nonindigenous Aquatic Species (NAS) database at the U.S. Geological Survey and from the closely related publication on nonindigenous fishes by Fuller and others (1999). The database is built from a variety of sources, including scientific literature, published and unpublished reports, and museum specimens. The database also relies on information from personal communications with scientists and others, as these sources are often the most recent (or only) documentation of a species' occurrence in a particular area. We have attempted to make the maps in this guide as up-to-date as possible. Nevertheless, we may not be informed of all occurrences of nonindig- enous cyprinids. Moreover, the distribution of non- native fishes frequently changes over time, with many species expanding their ranges. Consequently, readers are reminded that distributions of introduced species are constantly in flux, so those who are attempting to identify a fish should not rule out a particular species simply because the map shows that it has not previously been reported from the area. Most of the distribution data provided in this guide can be found by querying the NAS database (http://nas.er.usgs.gov/queries). Summary collection information, including date, can be obtained by click- ing on the dip-net icon. Detailed information about each collection can be found by clicking on the speci- men 10. The database is constantly updated as new records are added and earlier records are reviewed and corrected. 1ndividuals who have relevant infor- mation concerning the collection of nonindigenous cyprinids are asked to report their findings to state game and fish agencies and to the NAS database (appendix C; See subsection "Reporting the Discoverytof Non indigenous Fishes" at end of Introduction).