>> Articles >> An alien species is a species introduced by humans
Invasive Alien Species
An alien species is a species introduced by humans – either intentionally or accidentally - outside of its natural past or present distribution, however not all alien species have negative impacts, and it is estimated that between 5% and 20% of all alien species become problematic. It is these species that are termed ‘invasive alien species’ (IAS).
"An invasive alien species (IAS) is a species that is established outside of its natural past or present distribution, whose introduction and/or spread threaten biological diversity” Convention on Biological Diversity.
Invasive alien species are a major driver of biodiversity loss. In fact, an analysis of the IUCN Red List shows that they are the second most common threat associated with species that have gone completely extinct, and are the most common threat associated with extinctions of amphibians, reptiles and mammals.
Invasive alien species can also lead to changes in the structure and composition of ecosystems leading to significant detrimental impacts to ecosystem services, affecting economies and human wellbeing. For example, the water hyacinth Eichhornia crassipes, a native to South America is spreading across Africa, Asia, Oceania and North America. It is a fast growing floating aquatic plant forming dense mats on the water surface, limiting oxygen and preventing sunlight reaching the water column. Infestations have led to reduced fisheries, blocked navigation routes, increased cases of vector bourne diseases, reduced hydropower capacity and affecting access to water.
Due to the increase in the movement of people and goods around the world, the opportunity for the introduction of species outside of their natural range is on the increase. The different ways in which species are transported from one place to another, are called ‘pathways’. Common pathways include the release of fish for fisheries into the wild, escape from farms and horticulture, within ship ballast water and the spread through man-made corridors such as canals.
What is being done?
In 2010 almost all of the world’s governments adopted the Convention on Biological Diversity Strategic Plan for Biodiversity, which included 20 headline ‘targets’ referred to as the Aichi Targets. One of these targets (#9) is specifically related to IAS.
This international commitment to addressing IAS was re-affirmed in 2015 through the 2030 Agenda for Sustainable Development which includes 17 goals (SDGs) each with specific targets.
What is IUCN doing to address IAS?
IUCN’s work on IAS is focused primarily on achieving Aichi T9. To do this IUCN has been working in three major areas, providing scientific knowledge, engaging in and supporting national and regional policy development, and action on the ground.
The overarching aim of all IUCN policy engagement work related to IAS is to provide technical and scientific advice to work towards achieving Aichi Target 9. IUCN aims to encourage and mainstream invasive species issues across different fora, including national governments, international policy instruments such as the Convention on Biological Diversity, the private sector and civil society.