Effectiveness of legislative tools to stop biological invasions: freshwater turtles’ invasion in Europe as a study case

Abstract

Invasive species pose significant threats to biodiversity, human health, and economic systems. Freshwater turtles are popular as pets, but when released or allowed to escape into the wild, they can become invasive. A prominent example is the red-eared slider Trachemys scripta, which is recognized as a globally invasive species. Legislative tools, such as the European Union Regulation 1143/2014 on the prevention and management of invasive alien species, aim to combat these threats. This framework includes the implementation of Commission Implementing Regulation 1141/2016, which banned the trade of listed invasive species, including T. scripta. This study evaluates the effectiveness of Regulation 1143/2014 on T. scripta invasion and its consequences on other freshwater turtle invasions, using data from the CITES database and the GBIF platform. While T. scripta imports into the EU ceased after 2016, the species continues to establish and expand in the wild. This suggests that the trade ban had minimal impact on already established populations, highlighting the need for additional measures to reduce and control its spread. Simultaneously, imports and records of other freshwater turtle species have risen, indicating a shift in trade dynamics. These species are increasingly being introduced, potentially exacerbating the biological invasion problem. Despite limitations inherent to CITES and GBIF data, our findings suggest that the current European legislation has not been effective in mitigating T. scripta invasions and may have unintentionally contributed to the introduction of other invasive turtles. We recommend that the European Union develop invasive species lists tailored to each biogeographic regions of Europe to enhance the effectiveness of legislation.