Factors affecting the establishment success of the invasive piscivorous chub in small irrigation ditches in northern Kyushu, Japan

Habitat matching is an important factor for the establishment of alien fishes in recipient environments. The piscivorous chub, Opsariichthys uncirostris uncirostris, originally exclusively inhabited large water areas; however, the species has been introduced and established in small irrigation ditches on Kyushu Island. The evaluation of the habitat use of the piscivorous chub suggested that this alien fish uses the lentic-type irrigation ditches as a nursery ground and the lotic-type ditches as a spawning ground. This finding implies that the establishment of the piscivorous chub may require connectivity between lentic and lotic habitats.