Seasonal meso- and microhabitat selection by the northern snakehead (Channa argus) in the Potomac river system

The northern snakehead (Channa argus) is a large piscivorous fish that is invasive in eastern Europe and has recently been introduced in North America. We examined the seasonal habitat selection at meso- and microhabitat scales using radio-telemetry to increase understanding of the ecology of this species, which will help to inform management decisions. After the spawning season (postspawn season, September-November), northern snakeheads preferred offshore Eurasian water-milfoil (Myriophyllum spicatum) beds with shallow water (similar to 115 cm) and soft substrate. In the winter (November-April), these fish moved to deeper water (similar to 135 cm) with warmer temperatures, but habitat selection was weak at both scales. Northern snakeheads returned to shallower water (similar to 95 cm) in the prespawn season (April-June) and used milfoil and other cover. Habitat selection was the strongest at both meso- and microhabitat scales during the spawning season (June-September), when fish preferred macrophytes and cover in shallow water (similar to 88 cm). Our results help to identify habitats at the risk of invasion by northern snakeheads. We suggest that control efforts and future research focus on shallow waters, and take into consideration the seasonal habitat preferences.