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Identifying the genetic structure of introduced populations of northern snakehead (Channa argus) in Eastern USA.

With new introductions of invasive species occurring at an alarming rate, resource managers must be able to rapidly determine the source of introduction if there is to be a chance of preventing further spread or future invasions. The first North American populations of reproducing northern snakehead (Channa argus) were detected in Maryland in 2002 and have continued to spread into new watersheds. We used four microsatellite markers to describe genetic characteristics of four established C. argus populations in Eastern U.S.A., a collection of samples of unknown origin from a Chinatown market in Manhattan, New York, and of a C. argus population of uncertain status in the Upper Hudson River. We aimed to determine the probable source of the introduction of C. argus to the Upper Hudson River basin and to clarify the genetic structure of C. argus populations in northeast U.S.A., overall. Results from population structure analysis infer two distinct genetic groups among the specimens sampled. Measures of genetic distance suggest the C. argus population in the Upper Hudson is most similar to the population in the Lower Hudson near Queens, NY. Results conclude that the Potomac River and Chesapeake Bay basins represent one genetic population, which suggests that introductions to the Chesapeake Bay were sourced from the Potomac population and/or that the Bay does not represent a barrier to C. argus dispersal. Overall, our analysis provides evidence of multiple introductions into U.S. waters and human mediated secondary spread from these founding populations.