An update on the freshwater exotic fauna in the Mediterranean region of Baja California, Mexico

Exotic species introductions are a major threat to biodiversity. The first step to their control involves identifying their presence, distribution, and impacts on native species and their habitats, especially in highly diverse regions. We update and document new records of exotic freshwater fauna from the Baja California Mediterranean region. We found 157 locality records of 17 exotic aquatic species; 16 genera and 15 families were recorded. Five species are new records for the region: Malaysian trumpet snail (Melanoides tuberculata), black bullhead catfish (Ameiurus melas), common carp (Cyprinus carpio), spiny softshell turtle (Apalone spinifera), and red-eared slider (Trachemys scripta). The catfish, carp, and softshell turtle have been previously reported from Baja California, but only from the Colorado River and adjacent Mexicali Valley, while the snail and slider represent new state records. Of the 157 locality records, 71 were found in published literature and 86 represent new records from field observations, collected specimens and citizen science observations. Based on discussions with local ranchers and landowners, some exotic species were introduced for food or aesthetic purposes, emphasizing the need for environmental programs to stop these actions.