Population ecology and habitat use of the invasive northern snakehead (Channa argus) in Arkansas

The Northern Snakehead (Channa argus), a predatory invasive species, was discovered in the Big Piney Creek drainage in eastern Arkansas in 2008.  In March, 2009, Arkansas Game and Fish Commission and US Fish and Wildlife Service launched a large effort to eradicate Northern Snakehead from over 200 square kilometers using rotenone distributed by ground and air crews.  A total of 787 individual snakeheads were collected at 28 sites.  Snakehead density ranged from 0.002 to 0.02 individuals per square meter of stream and was not significantly different from the density of the ecologically similar native Bowfin (mean 0.0086 bowfin/m2, mean 0.01 snakehead/m2; P=0.629), suggesting niche overlap between the two species.  A length frequency histogram revealed a stable, growing population with a large number of young-of-year and several adult age classes.  Preliminary results suggest snakeheads are reproductively mature by age one and all females in the population are able to reproduce in a given year.  Specimens were collected in all habitat types searched, except for areas of high flow in Big Piney Creek.  Presence of Northern Snakeheads displays no correlations to biotic or abiotic conditions, suggesting the species was successfully dispersing throughout the Big Piney Creek drainage by March, 2009.