State of the Environment Tasmania Home
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Animal Pests Index of Biodiversity issues


    Threatening Processes

        At a glance

        Mainland Yabby

        The issue

        An animal pest is an introduced animal with an established self-supporting population in the wild (also known as feral or naturalised) that is a threat to human health, primary production and/or the natural environment. Pests that specifically impact on environmental values, such as native plants and animals, are termed environmental pests.

        The introduction of the European red fox is one of the major environmental changes since the previous SoE report, but it also represents a potentially defining event in Tasmania's environmental history. It has the potential to result in the loss of Tasmania's status as a marsupial stronghold. The Nature Conservation Strategy Final Report noted that the establishment of the European fox in Tasmania (May 2001) is now certain to cause the decimation and likely extinction of Tasmania's small mammal and ground-dwelling bird populations, as has happened throughout mainland Australia (State Biodiversity Committee 2002).

        Animal pests represent one of the most serious threats to Tasmania's biodiversity, both on land and in water. In 2001, there was a total of 1,012 (60 vertebrates, 952 invertebrates) known naturalised animal species in Tasmania.

        This 'At a glance' section provides an overview of the animal pest issue. More detailed information and references are available in the Animal Pests Issue Report. Five indicators are included in the main report relating to naturalised species, environmental pests, and management plans (see Indicators).

        A recommendation is also provided on Weeds, Pests and Diseases.

        Favourable news

        Most of the favourable news in the following section relates to programs to respond to specific animal pest species such as the fox. A measure of success (and favourable news) will be whether, in five years, Tasmania is able to regain its fox-free status.

        • The State Government has formed The Fox Free Tasmania Taskforce to prevent the establishment of foxes in Tasmania. The Taskforce are undertaking a coordinated eradication program in key areas of the State. Field courses have been conducted for farmers and other landholders and a communications strategy has been implemented.
        • 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. To help the quarantine officers assess which ships are a larger risk, a decision support system has been introduced, available the world wide web. Alternately, the vessels can discharge their ballast waters at sea or use an on-board treatment system.
        • A carp eradication program has been ongoing at Lake Crescent and Lake Sorell.
        • The need for a vertebrate pest eradication strategy (with on-ground eradication program) for Tasmania's offshore islands has been identified and funding options continue to be explored.
        • A study of the impact of feral pigs on Flinders Island (Underwood 2000) has been undertaken and eradication measures commenced in cooperation with the local community.
        • Vertebrate pest management on Macquarie Island has been conducted since 1974. Quarantine strategies have been developed to prevent further introductions to the island.
        • An Australian Government-funded goat eradication program has been carried out in key areas of the State during the past five years and has achieved localised success.
        • A two-year project by the University of Tasmania to examine the impact of feral Pacific oysters on assemblages of native species commenced in 1999.

        Unfavourable news

        • Of the 1,012 naturalised animal species in Tasmania, 44 (32 vertebrates, 12 invertebrates) are considered to be environmental pests. However, only six of the 44 have been formally declared as pests on either the Living Marine Resources Management Act 1995 and/or the Inland Fisheries Act 1995. These are European carp (Cyprinus carpio); eastern Gambusia (Gambusia holbrooki); mainland yabby (Cherax destructor); European shore crab/green crab (Carcinus maenas); giant fan worm (Sabella spallanzanii) and the northern Pacific seastar (Asterias amurensis).
        • Since the last SoE Report in 1997, three new species recognised as pests have been recorded in Tasmania: foxes (Vulpes vulpes), ferrets (Mustela furo) and eastern Gambusia (Gambusia holbrooki), which is a type of fish.
        • The European red fox represents the single most devastating threat to Tasmania's native mammals and birds. The commercial livestock industry would also be at risk. For example, it is estimated that domestic stock comprises 80% of all food eaten by the estimated 10-30 million foxes, which occur on mainland Australia. In 1998, Tasmania's commercial livestock industry was valued at around $348 million per annum. The economic losses of livestock from fox attacks could equate to as a much as $34.5 million per annum in Tasmania's sheep industry alone (wool and slaughter).
        • Of the total 44 environmental pests that exist in Tasmania, only 14 are covered by control/eradication plans (i.e. management plans, management programs and/or strategies). Of the 32 environmental vertebrate pests, only three species have active, on-the-ground management plans. Many of these programs are for individual areas and do not cover the full geographic distribution of the relevant species. For example, only 0.18% of the feral cat and black rat range is covered by a management plan, and only 3% of the rabbit range.
        • Tasmania's outer islands serve as safe havens for the preservation of species that may otherwise become threatened on mainland Tasmania in the future. However, 59 of Tasmania's outer islands already have vertebrate pests. Island ecosystems are particularly vulnerable to the affects of naturalised species. On some islands for example, introduced pests have caused major declines and extinctions of native species, especially sea birds. Only three of the 59 islands in February 2002 had active pest management actions in place: Flinders, Macquarie and Bruny islands.

        Uncertain news

        • No studies are known in Tasmania that estimate the economic impacts of the effects of animal pests (e.g. foxes) to the nature-based tourism industry.
        • There is very limited information available on populations and distribution of pest species and changes over time. It has not been possible to present distribution maps in this SoE Report for common pest species.
        • There is uncertainty about animal introductions that may be poised to become pests in the future.
        • There is very limited information available on many invertebrate pest species and potential consequences for native species (e.g. the impacts of predation by the European wasp on native bees, and the consequences for native plants that are only able to be pollinated by native bees).

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        Last Modified: 14 Dec 2006
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