State of the Environment Tasmania Home
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Introduced Species Index of Biodiversity issues


    Threatening Processes

        At a glance

        The issue

        Introduced species are foreign species (e.g. roses, blackberries, foxes, wasps, root rot) that have arrived accidentally or have been introduced intentionally. Once introduced species have established self-supporting populations in the wild, they are termed naturalised or feral.

        Since Tasmania was colonised by European settlers, hundreds of foreign plants and animals have been introduced into Tasmania.

        Many introduced species such as crop plants, farm animals and game animals are economically beneficial, and others such as pets (that are managed responsibly) and ornamental plants are harmless to the environment.

        However, approximately 16% of the naturalised species in Tasmania have become a significant problem to primary production and/or the natural environment and are known as pests.

        Examples of plant pests (i.e. weeds) in Tasmania include blackberries, gorse, serrated tussock and Japanese kelp. Examples of animal pests include foxes, feral cats, the mainland yabby (which inhabits inland waters) and the northern Pacific seastar. Separate Issue Reports discuss Plant Pests (Weeds) and Diseases and Animal Pests in more detail.

        This 'At a glance' section provides an overview of the issue of introduced species. More detailed information is available in the Introduced Species Issue Report. Two indicators are presented in this Issue Report, including Introduced Species that are Naturalised and Quarantine Seizures per Passenger %.

        A recommendation is presented on Weeds, Pests and Diseases.

        Favourable news

        • Various pest management programs in the DPIWE, Forestry Tasmania, Inland Fisheries Service and the CSIRO Division of Marine Research are being conducted (see Animal Pests and Plant Pests (Weeds) and Diseases for further details).
        • From the 1st July 2001 new ballast water arrangements came into force for all international vessels visiting Australia. Permission must now be granted in writing from a quarantine officer before ballast waters can be discharged in Australian ports or waters. This is discussed in more detail in Marine Pests and Diseases Issue Report.
        • An action plan to prevent the introduction of the European red fox into Tasmania and to maintain Tasmania's fox-free status was developed by DPIWE in 2001. The Tasmanian Fox Free Taskforce was established in 2001 and is undertaking a co-ordinated fox eradication program in key areas of the State.
        • A national threat abatement strategy for Phytophthora cinnamomi is currently being implemented in Tasmania to combat the spread of the disease.

        Unfavourable news

        • Seven hundred and sixteen naturalised vascular-plant species are known from Tasmania. Long-term trend data show that between 1878 and 2000 (122 years) the number of naturalised plant species increased seven times from 104 to 716 species. Of the 716 species, 162 are considered to be weeds in Tasmania.
        • There are seven naturalised non-vascular plants known from Tasmania, all of which are macroalgae (e.g. large seaweeds such as Japanese kelp) found within the marine environment.
        • Sixty naturalised vertebrate animal species are known from Tasmania, most of which are birds (31 species), mammals (17 species) and fish (9 freshwater and 2 saltwater species). Only one introduced reptile species is known from Tasmania.
        • Most of the naturalised invertebrate species in Tasmania belong to the group Arthropoda (67%). Examples include insects, spiders, crabs and centipedes. The other two main groups are Rotifera (25%), which are freshwater microfauna and the Mollusca (3.5%), which include the bivalves, snails, squid and octopus. Although only 1.3% of the introduced invertebrate species are regraded as environmental pests, they cause widespread economic and environmental problems.
        • Urochordata (e.g. ascidians, sea squirts, salps, tunicates) are non-vertebrate chordates, which live in the marine environment. Up until 2001, three naturalised species of urochordata had been recorded in Tasmanian waters.
        • There is only one known naturalised fungal species in Tasmania (Amanita muscaria).
        • There are three known naturalised species belonging to the Kingdom Chromista. Two species of toxic dinoflagellates, which produce potent toxins that can threaten marine ecosystems. The other is root rot (Phytophthora cinnamomi), which significantly threatens susceptible plant communities.
        • In the 2001-02 financial year there were 324.05 tonne of quarantine seizures for 1,591,171 visitors (0.2 kg per passenger).

        Uncertain news

        • The number of naturalised species is likely to be underestimated for groups that are comparatively less well-researched. Knowledge is greater for vascular plants and vertebrate animals compared to non-vascular plants, invertebrates and species belonging to the Kingdoms Fungi (true fungi) and Chromista. For example, between 5-30% of species only belonging to the Fungi Kingdom have been described.
        • There are no known naturalised frog species in Tasmania. However, there is concern that individual frogs may be entering the State via fresh food produce. If frogs from mainland Australia are introduced into Tasmania they may carry Chytrid fungus, which is being attributed to frog decline worldwide.
        • As this is the first year that data for quarantine seizures per passenger have been collected in such a format it is not possible to determine the percentage increase or decrease of seizures per passenger between 1997 and 2002.

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        Last Modified: 14 Dec 2006
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