Seasonal movement, dispersal, and home range of Northern Snakehead Channa argus (Actinopterygii, Perciformes) in the Potomac River catchment

Knowledge of the movement behaviour and dispersal ability of non-native species can aid in their management by informing risk assessments and the development of control strategies. To improve understanding of the seasonal movement and dispersal behaviour of Northern Snakehead (Channa argus), we implanted 49 fish in the Potomac River with radio tags and tracked movements from October 2006 to 2007. In addition, we tested the hypotheses that activity level, dispersal ability, and home range size varied with fish size. Home range was calculated for 24 fish. Of these, 19 exhibited stable home ranges averaging 1.2 km(2) in size. Thirteen fish (31% of survivors) dispersed an average distance of 18 km between 30 April and 7 June, mostly upstream (92%) and across the main river channel. Fish moved greater distances during the pre-spawn season compared to the spawning season. There was no relationship between fish length and any behavioural measure. Upstream dispersal was restricted by barriers such as dams; therefore, Northern Snakehead can likely disperse greater distances than observed here. Our observations demonstrate the invasiveness of Northern Snakehead by showing that a large portion of adults dispersed over considerable distances, suggesting spread may be rapid in large, open freshwater systems.