First records of Mauremys sinensis in Portugal: a consequence of inadequate policies applied to the exotic pet market

Commercial success of a pet species predicts its invasiveness, making the most traded species more likely to become introduced. Turtles are among the most traded species, making it critical to monitor their introduction, and in Portugal several invasive turtle species have been detected in nature. This study reports the first official record of Mauremys sinensis and lists its unofficial records in Portugal. This is a critically endangered species in its native range but invasive out of its native range. Two M. sinensis individuals (one adult male and a juvenile) were found in a lake near Évora, alongside native Mauremys leprosa. Additionally, iNaturalist database analysis revealed 14 citizen science records of this species in 10 municipalities in Portugal since 2021 These records were located from North to South of continental Portugal but also in the Madeira Island. The presence of invasive turtles can impact native species through competition, predation, disease transmission, and hybridization. Pet trade is the primary source of these species, and legislation has been ineffective in preventing their introduction. This study also highlights the need for comprehensive strategies, including whitelists and blacklist, to address the invasive pet trade, protect native ecosystems, and prevent further introductions of species like M. sinensis.