Historical Review of Introduced Snakeheads in Japan
Abstract.—In Japan, natural populations of three snakeheads have been established: Northern Snakehead Channa argus, Blotched Snakehead C. maculata, and Small Snakehead C. asiatica. Historical literature indicates that C. argus was brought into Japan during the period of national isolation in the early modern period. After the nation’s closure period, the former two species were introduced before World War II for food resources, whereas the last was found in Japan after the war. Channa argus was cultured in irrigation ponds in some prefectures, but ecological invasiveness was a concern because of their predatory nature and nonindigenous origins. When new national legislation controlling invasive alien species began in 2005, three snakeheads appeared on the list of alien species requiring special attention. However, there is little evidence suggesting ecological invasiveness of snakeheads in Japan in recent years. The most recent national list of invasive species in 2016 included no snakeheads. In some water bodies, C. argus is actively used as the ecological agent to control other invasive alien species.