Screening potential habitats of non-indigenous freshwater fish using a climate zone habitat suitability assessment

Invasive non-indigenous species have been reported to cause harm to ecosystems, including freshwater ecosystems, and reduce species abundance. As the world became more alert to the introduction of non-indigenous species, the demands for developing preliminary management measures have also increased. Thus, this study aimed to develop a habitat suitability assessment approach for non-indigenous freshwater fish with cost-effective data access. This approach utilized the Köppen-Geiger climate classification maps and fish occurrence data to predict the present (1980–2016) and future (2071–2100) habitat suitability of Oreochromis niloticus and Poecilia reticulata in South Korea. A fuzzy inference system was applied to relate climatic variables based on the Köppen-Geiger climate classification and species occurrence records. The results indicate that the habitat of the two species is limited to sites near sources of thermal pollution (for overwintering) in the present, and habitable area will expand in the future as the temperature increases. This approach is expected to aid non-experts in decision-making processes regarding non-indigenous freshwater fish management by evaluating potential habitats through the transfer of quantitative climate variables into linguistic or intuitive variables. Further augmentation in the climate zone classification method is expected to aid developing management strategies. Additionally, this approach is anticipated to facilitate the application of habitat prediction results by shortening the gap between experts and non-experts.