The Australian opossum or phalanger (Trichosurus vulpecula) was first liberated at Riverton, Southland, in 1858 with the idea of starting a skin trade. Since then innumerable recorded and unrecorded liberations have been made all over New Zealand, in Stewart Island and the Chatham Islands and in the outlying islands. There are now few areas without opossums, exceptions being the high country and northern Northland. There were at first very few complaints, but as opossums became established and increased in numbers and distribution they came to cause trouble, especially when combined with other animals, in native and man-made forests, in orchards and gardens, and in catchment areas. Admittedly hundreds of thousands of skins were exported each year, but on balance it appears that the harmful effect of opossums outweighs the profits from the sale of skins.
Legislation on the management and control of opossums reflects the changing attitude towards this species. A period of absolute protection from the date of introduction till 1920 was followed by a period of limited protection, when skins were taken by licence during a short open season. In 1947 all protection was removed and in 1951 a bounty system was introduced. This was followed in 1956 by further legislation which declared the opossum a “noxious animal”. At present the bounty system has been discontinued and opossum control is entrusted in part to rabbit boards and in part to the New Zealand Forest Service. Trapping, used almost exclusively in the past, has recently been largely replaced by poisoning with 1080 (sodium fluoroacetate), or cyanide, and by shooting.