Market-driven risks: Assessing exotic testudines trade and invasion potential

Testudines are popular pets, often becoming introduced species. Propagule pressure is crucial for invasion success but difficult to quantify. Since the pet trade is a major source, it can serve as a proxy. While CITES regulates some species, much of the international trade remains unrecorded, including illegal sales. This study examines exotic pet testudines availability in legal and illegal markets, analyses social media trade, explores the link between propagule pressure and wild populations, and assesses the representativeness of online markets using Portugal as a case study. Data were collected from pet stores, online platforms, and a Facebook group. A Relative Market Pressure (RMP) index was developed as a proxy for propagule pressure, considering trade frequency across different platforms. Results demonstrate significant variations in species composition among trade types. Online trade, especially social media, played a major role, with many prohibited species available. Human population density was a strong predictor of exotic turtle occurrence in the wild. This study highlights the importance of monitoring both physical and online trade. The RMP index is proposed as a useful tool for assessing propagule pressure. Stronger enforcement, adoption programs for invasive species, and turtle size sale restrictions are recommended to reduce releases and mitigate invasion risks.