Our Natural Resources at a Glance - Pests
Pests
Land pests
- Over 80 species of non-native vertebrates have established wild populations in Australia and over 30 of these species are agricultural or environmental pests. Direct short-term agricultural effects caused by these exotic vertebrate species total at least $500 million per year and control costs are at least $60 million. Overgrazing and browsing by introduced herbivores also contributes to land degradation, which lowers the future productive capacity in many areas, but the value of this degradation has not been estimated.
- Major agricultural pest species include grazing species such as rabbits and feral goats which compete with livestock for pasture and cause land degradation through overgrazing.
- Other introduced pests, such as foxes and feral pigs, prey on lambs and other vulnerable livestock. House mice and starlings cause costly damage to grain and fruit crops. Some exotic species pose a risk of spreading diseases. For example feral dogs can help spread hydatids and feral pigs could help spread classical swine fever if this disease breached Australian quarantine.
- Some native species can also be agricultural pests. For example, native cockatoos eat grain and oilseed crops and kangaroos can compete with livestock for pasture.
- Introduced invertebrates are estimated to cost over $4.7 billion in agricultural production losses annually and a further $750 million in control costs. Horticulture, grain, pastoral and beekeeping industries are all affected.
- There is a risk that new exotic species could establish as wild pests in Australia. These could be species already being kept as pets or as display animals in zoos or private collections. Examples of high-risk species are monk parakeets and chipmunks. Both species are well suited to Australian habitats, damage crops overseas and have established exotic populations in other countries. To reduce this risk, quarantine and environmental protection authorities conduct risk assessments on exotic species kept in Australia or proposed for import, and may impose import bans or keeping restrictions on high-risk species. This is combined with barrier control measures to reduce the risk of accidental or illegal introductions of exotic species.
Number of exotic vertebrates introduced to Australia
| Birds | 20 | (plus seven on offshore islands) |
| Mammals | 26 | (plus one on offshore island) |
| Freshwater fish | 23 | |
| Reptiles | 4 | |
| Amphibians | 1 |
More information
Vertebrate pests
Invertebrate pests
Aquatic pests
- Approximately 250 exotic marine species have been identified in Australian waters.
- Marine pests are imported in ballast water tanks or in biofouling communities on vessel hulls.
- Introduced marine pests may impact upon biodiversity (replacing or out competing native species for example), maritime industries and human health.
- Since 2001, the Australian Quarantine and Inspection Service (AQIS) has operated a Ballast Water Decision Support System (BWDSS) to assess the risks posed by foreign ballast water carried by all commercial ships entering Australian waters. AQIS prohibits the discharge of high-risk ballast water except in designated deballasting zones.
- Australian governments are collaborating in the development and implementation of a National System for the Prevention and Management of Marine Pest Incursions that will address risks from all vectors - both domestic and international.
- The Northern Pacific Seastar, established in the Derwent Estuary, Hobart in the late 1980's, is a voracious predator that is of concern to Tasmanian shellfish farmers as it consumes farmed oysters and mussels, causing heavy stock losses. This species has now spread to Port Phillip Bay, Victoria and there is concern over its potential to invade the entire southern Australian coastline.
- Other marine pests include aquarium weeds, the European fanworm and algae that can cause toxic algal blooms.
- The invasion of the Black Striped Mussel into a Darwin marina in 1999 caused major disruption to the tourism industry, significant revenue loss to the marina owner and was eradicated at a cost in excess of $2.2 million.
- 23 species of exotic freshwater fish have established in Australian waterways. Most of these have the potential to expand their current distribution and many are already regarded as significant pests including carp, mosquito fish and tilapia. Introduced fish may prey on native fish or compete with them for food. Species such as carp, which can reach extremely high densities, may disrupt a wide range of ecosystem attributes including water quality.
More information
Invasive marine species: www.daff.gov.au/fisheries/invasive
Invasive marine species: http://crimp.marine.csiro.au
Freshwater fish: www.marine.csiro.au
Freshwater fish: www.nativefish.asn.au/exotics.html
Australian exotic fish: www.asfb.org.au/research/es
Weeds
- Around 2,700 non-native (exotic) plants have established populations in Australia, 68% of which are considered a problem for natural ecosystems, while 47% are considered a problem for agricultural systems.
- Weeds contaminate crops, displace desirable pasture plants, reduce livestock carrying capacity and condition, contaminate wool, act as harbours for diseases or insect pests and can be toxic to livestock.
- The total costs of impacts on agriculture are up to $4.5 billion annually. Weeds are also expensive to control, costing $1.7 billion annually, mainly for cultivation and herbicides.
- Biological control is an option for weeds, but can lead to controversy. Paterson's curse can be toxic to livestock. Successful biological control could save $30 million annually, but could cause beekeepers losses up to $2 million.
- There is a high risk that more exotic plants will establish as weeds in Australia. Some 30,000 plant species are available from 450 nurseries in Australia although this total includes some native plants. Many of the non-native plants have potential to become significant agricultural weeds.
- For example, Spanish thistle and Mexican feather grass are two species available from Australian nurseries that have the potential to seriously modify pastures. There is a need for improved risk awareness and proactive steps to reduce risks of new weeds establishing.
- Quarantine authorities conduct risk assessments on new species of exotic plants proposed for import into Australia and impose import bans on high-risk species.
- The determination of the weeds of national significance (WONS) through the National Weeds Strategy is a system to prioritise weed problems over a range of land uses at a national level. There are currently 20 WONS for which State and Territory governments have legislative and administrative responsibility to control.
- Work has recently been undertaken on agricultural 'sleeper weeds', weeds currently present only in a small area but have the potential to spread widely and have a major negative impact on agriculture. This has involved identifying priority sleeper weeds that could be eradicated before they become major agricultural weeds in Australia.
Origin of weeds in Australia
More information
National Weeds Strategy and WONS: www.weeds.org.au
BRS (inc. sleeper weeds): www.daff.gov.au/brsweeds
CRC for Weed Management: www.weeds.crc.org.au
DAFF: www.daff.gov.au/nrmweeds
...At a Glance
Australia - Our Natural Resources | Foreword | Overview | Water | Climate | Soils | Land Use | Vegetation | Social | Biodiversity | Pests | Government Initiatives | Data and Information sources | Acknowledgements
Last reviewed: 19 Sep 2007
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