Antarctic Biosecurity Policy Effectively Manages the Rates of Alien Introductions

Reducing the rates and impacts of biological invasions is a major policy goal of international biodiversity agreements. Yet the extent to which this goal is being achieved and the agreements hence successful in this respect remains unclear. Here we use a comprehensive record of alien species introduction in the terrestrial Antarctic, including its surrounding Southern Ocean Islands, spanning 115 years (1900-2015), to quantify the impact of biosecurity policy on alien species introduction rates in the region, where invasive alien species are a primary environmental conservation threat and management priority. We show that although many parts of the Antarctic have been colonized by non-indigenous taxa, recent rates of introduction appear to be slowing or static in most parts, compared with increases in the past. Our results vindicate the regional Antarctic focus on biosecurity measures, but also demonstrate the need for stricter enforcement due to rapid socio-environmental changes.