One of the key threats to species and island ecosystems worldwide is invasive species. Since the arrival of humans on Pacific islands, they have deliberately brought with them species that are useful for their survival. Unwanted species were accidentally introduced. Some of the unwanted species, and in rare cases useful species, get out of control and can cause enormous ecological, economic or health problems. These are called "invasive" species, also known as "pest" species. Invasive species are usually highly adaptable. They can live in a wide range of environments. They breed fast, spread easily, and quickly become widespread. When they arrive in a new country, they have usually left the diseases and predators that would have kept their numbers under control back in their home country.
The Pacific is a leader in using a regional approach to address invasive species. The Guidelines for Invasive Species Management in the Pacific, developed by SPREP and SPC at the request of and with the collaboration of its member countries, and endorsed by them in 2008, provides a framework for national and regional efforts to manage invasive species. The Pacific has also developed two networks for improving invasive species management in the region: the Pacific Invasives Partnership (PIP) is a coordinating body for international agencies that provide services to Pacific countries and territories, and the Pacific Invasives Learning Network (PILN) is a network for invasive species workers in the countries and territories themselves. The Invasive Species programme coordinates both networks and develops and manages multi-country invasive species projects. It further assists its member countries and territories to develop their invasives programmes and projects, such as by providing expertise and access to funds.