In New Zealand "Undaria pinnatifida" is a very serious weed, and is one of the 100 worst invasive species in the world. It was first seen in Wellington Harbour in 1987. It probably arrived accidentally in the late 1980s, on ships from Asia, in ballast water. It is native to cold temperate coastal areas of Japan, Korea and China, but recently it has also spread to France, Britain, Spain, Italy, Argentina and Australia.