Quantifying Invasiveness Risk of Non-Native Freshwater Fishes in South Korea Under a Changing Climate

Biological invasions pose a serious threat to native biodiversity, and climate change intensifies the risk of non-native species invasion in human-altered environments, particularly in freshwater ecosystems. In South Korean freshwaters, the number of non-native fish species increased significantly since the early 1950s. We screened risk of invasion by 43 freshwater fish species in South Korea using the Aquatic Species Invasiveness Screening Kit (AS-ISK). Of these species, 26 (~ 61%) posed a high to very high risk of invasiveness. Black bullhead Ameiurus melas, brown bullhead Ameiurus nebulosus, North African catfish Clarias gariepinus, green sunfish Lepomis cyanellus, black carp Mylopharyngodon piceus, round goby Neogobius melanostomus, and Chinese sleeper Perccottus glenii were very high risk under current and predicted climate conditions. Striped snakehead Channa striata, longear sunfish Lepomis megalotis, smallmouth bass Micropterus dolomieu, white perch Morone americana, Eurasian perch Perca fluviatilis, and rudd Scardinius erythrophthalmus were high risk only under predicted climate conditions. Present risks were generally consistent with previous qualitative assessment, with some discrepancies, likely due to unobserved or under-reported invasive traits of some species or a better ability of the present semi-quantitative approach to estimate potential risks. Our results will inform South Korean decision-making to potentially enhance regional cooperation across East Asia against transboundary introductions of aquatic invasive species.