- NATURAL RESOURCE MANAGEMENT VISION FOR THE NORTHERN AGRICULTURAL REGION OF WESTERN AUSTRALIA
Biosecurity & Invasive SpeciesAustralia’s native plants and animals evolved over millions of years in relative isolation. Since European settlement, many non-native plants, animals, pathogens and other organisms have been introduced deliberately or accidentally. Most introduced species do not become invasive, but those that establish, spread and cause environmental, economic, cultural or social harm can have significant impacts.
Invasive species include weeds, feral animals, pest insects and other invertebrates, introduced marine pests, and diseases, fungi and parasites. They can threaten native species and ecological communities, reduce agricultural productivity, damage waterways and coastal environments, spread disease, alter habitats and increase land degradation.
The success of an invasive species can be influenced by many factors, including favourable environmental conditions, high reproductive or dispersal capacity, disturbance of natural ecosystems and the absence of predators, competitors or diseases that limit the species in its natural range. Climate change and land-use change can also alter the distribution, abundance and impacts of invasive species.
At the national level, invasive species are recognised as a major threat to Australia’s biodiversity. Several invasive species and diseases are listed as Key Threatening Processes under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act).
Preventing new invasive species from entering and becoming established is generally more effective and less costly than attempting to control them after they have spread. Early detection and rapid intervention are therefore important components of biosecurity.
Where an invasive species is already established, management may focus on eradication where this is feasible, containment to prevent further spread, reducing populations or impacts, and protecting priority environmental, agricultural, cultural and social assets.
Control methods vary according to the species, environment and management objective. Feral animal management may include baiting, trapping, exclusion fencing, shooting and biological control. Weed management can include manual or mechanical removal, grazing, herbicide treatment, hygiene measures and biological control. Integrated management commonly uses several techniques over time.
Biological control has played an important role in managing some widespread invasive species in Australia. Examples include the use of biological control agents to reduce rabbit populations and the introduction of biological control agents for weeds such as Paterson’s Curse (Echium plantagineum).
Good biosecurity hygiene is also important. Seeds, soil and plant pathogens can be transported between locations on footwear, vehicles, machinery, tools and other equipment. Cleaning equipment and vehicles when moving between sites can reduce the risk of spreading weeds and plant diseases.
Invasive species do not respect property or administrative boundaries, so their effective management often requires a tenure-blind approach, i.e. coordinated management across different land tenures and ownership boundaries. This requires cooperation between governments, landholders, Traditional Owners, community organisations, industry, biosecurity groups and natural resource management organisations to manage invasive species at an appropriate landscape scale.
National biosecurity coordination is supported by the National Biosecurity Strategy, while approaches to established pest animals and weeds are guided by the Australian Pest Animal Strategy 2017–2027 and the Australian Weeds Strategy 2017–2027. The Western Australian Government provides information on the management of invasive species in WA.
Invasive plants, animals and diseases can affect places, species and natural resources of cultural significance to Aboriginal people. Changes to culturally important plants and animals, waterways and landscapes can affect cultural practices, knowledge, food resources and connections to Country.
Traditional Owners and Aboriginal organisations play an important role in invasive species management through Caring for Country. Cultural knowledge and contemporary land-management approaches can be used together to identify changes in Country, establish management priorities and undertake activities such as weed management, feral animal control, cultural burning and monitoring.
Recognising Traditional Owners’ knowledge, cultural values and priorities can improve invasive species planning and ensure management is appropriate to the Country on which it occurs. Weed and feral animal management can also support Aboriginal ranger programs, employment, training, intergenerational knowledge sharing and the continued practice of caring for Country.
Invasive species management is therefore not only an environmental, agricultural or economic issue. It also concerns relationships between people, Country and natural resources, and the knowledge and priorities of Traditional Owners should be incorporated into planning and management where appropriate.
A range of introduced animals occur within the Northern Agricultural Region (NAR), including mammals, birds, freshwater fish and terrestrial and aquatic invertebrates. Their impacts vary considerably. Some introduced animals have relatively limited environmental impacts, while others are significant agricultural or environmental pests.
Introduced and feral animals of particular management importance within and around the NAR include European rabbits (Oryctolagus cuniculus), European red foxes (Vulpes vulpes), feral cats (Felis catus), feral pigs (Sus scrofa), and feral goats (Capra hircus).
These animals can affect native biodiversity through predation, competition, grazing, habitat degradation and disease transmission. They can also affect agricultural production through predation on livestock, competition for pasture, crop damage and damage to infrastructure.
The impacts of several of these species are recognised nationally as Key Threatening Processes under the EPBC Act. Commonwealth Threat Abatement Plans and other national guidance provide frameworks for reducing the impacts of invasive animals on threatened species and ecological communities.
Introduced animals other than mammals are also important. The Mediterranean fruit fly (Ceratitis capitata), for example, is an introduced and declared pest in Western Australia and is a significant horticultural pest. Introduced freshwater fish, birds and invertebrates can also compete with native species, alter ecosystems or affect agricultural production.
Polyphagous shot-hole borer (Euwallacea fornicatus) is an emerging biosecurity threat to regional Western Australia. The invasive beetle, first detected in metropolitan Perth in 2021, attacks a wide range of trees and plants by boring into their trunks and branches and introducing a Fusarium fungus. In susceptible trees, the fungus disrupts the movement of water and nutrients, causing dieback and potentially tree death. Although the pest is currently concentrated in the Perth metropolitan area, its spread into the Northern Agricultural Region could threaten susceptible native vegetation, urban and community tree canopies, horticulture and other agricultural plantings. The beetle does not travel far on its own but can be transported over long distances in infested firewood, green waste, woody plant material and live plants. Preventing human-assisted spread into regional areas, together with early detection and reporting, is therefore important for protecting the NAR’s environmental and agricultural assets.
Under Western Australia’s Biosecurity and Agriculture Management Act 2007 (BAM Act), Recognised Biosecurity Groups (RBGs) support community-led and coordinated management of widespread established declared pests.
Several RBGs operate across parts of the NAR. These include the Northern Biosecurity Group, covering Chapman Valley, Northampton and Greater Geraldton; the Midlands Biosecurity Group, covering Moora, Dandaragan, Coorow, Carnamah, Three Springs, Mingenew and Irwin; and the Central Wheatbelt Biosecurity Association, which includes Dalwallinu, Koorda, Morawa and Perenjori. The Carnarvon Rangelands Biosecurity Association also covers pastoral properties within Northampton and Greater Geraldton.
RBG priorities vary according to local conditions and pest distributions. Their work supports landholders to meet their responsibilities for managing declared pests and encourages coordinated management across property boundaries.
Western Australia’s State Barrier Fence remains an important component of pest animal management. Originally developed to restrict the movement of rabbits, the fence now plays an important role in restricting the movement of wild dogs from pastoral areas into south-west agricultural areas. It also helps reduce the impacts of large emu movements into agricultural areas.
Preventing invasive animals from establishing on offshore islands is particularly important because island ecosystems can be highly vulnerable to introduced predators, competitors and other pests. Exotic rodents such as rats and house mice can have severe impacts on seabirds, reptiles, invertebrates and other native fauna, particularly on islands that provide important breeding and refuge habitat.
Along the Turquoise Coast, a chain of offshore islands, islets and rocks extends from near Lancelin north towards Dongara. Many are protected within 13 nature reserves collectively known as the Turquoise Coast Island Nature Reserves, and many lie within or adjacent to Jurien Bay Marine Park. The islands provide important habitat and breeding sites for seabirds, Australian sea lions (Neophoca cinerea) and other native fauna.
Further north, biosecurity is especially important for the Houtman Abrolhos Islands, an archipelago of more than 200 islands, islets and rocks off the Geraldton coast and one of the most significant seabird breeding areas in the eastern Indian Ocean. The islands also provide habitat for threatened and conservation-significant species. Introduced pests are recognised as a major threat to these island ecosystems.
The Houtman Abrolhos Islands National Park Management Plan 97 (2022) provides the current management framework for the national park and includes strategies to prevent the introduction and spread of non-native plants, animals and pathogens. The national park is managed by the Department of Biodiversity, Conservation and Attractions (DBCA) under the Conservation and Land Management Act 1984, while other parts of the islands and surrounding waters are subject to separate fisheries and reserve management arrangements.
Specific biosecurity requirements also apply to the Abrolhos Islands. Visitors and vessel operators are expected to ensure that clothing, footwear, vessels, equipment and supplies are free of soil, weed seeds, insects and animals such as house mice and Asian house geckos before travelling to the islands. DBCA also recommends that vessels maintain rodent bait stations as part of measures to reduce the risk of rodents reaching the islands.
Preventing the introduction and establishment of invasive species on islands is generally more effective than attempting eradication after establishment. Biosecurity, surveillance, appropriate pest-control measures and rapid response are therefore important components of protecting the Turquoise Coast islands, Houtman Abrolhos Islands and other offshore islands and seabird breeding sites associated with the NAR.
Introduced plants occur throughout the Northern Agricultural Region in agricultural landscapes, roadsides, waterways, coastal environments, towns and areas of native vegetation. Some introduced plants remain relatively localised or have limited impacts, while others become invasive weeds capable of causing substantial environmental or agricultural damage.
Environmental weeds can displace native plants, change vegetation structure and habitat, alter fire regimes and increase bushfire risks to people, property and infrastructure, affect waterways and coastal environments, and interfere with ecological processes. Agricultural weeds can reduce crop and pasture productivity, contaminate agricultural products and increase production costs.
A number of invasive plants of concern occur within the NAR, including species of prickly pear and other Opuntia cacti, Arum Lily (Zantedeschia aethiopica), Paterson’s Curse (Echium plantagineum) and African Boxthorn (Lycium ferocissimum). Other weeds can be important locally depending on their distribution, environmental impacts and management feasibility. African Boxthorn is one of the species recognised as a Weed of National Significance within the NAR.
Weed status and management requirements can change as new information becomes available. In Western Australia, the legal status and control category of declared plants is maintained through the Western Australian Organism List (WAOL) administered by the Department of Primary Industries and Regional Development.
Under the BAM Act, declared pests may be assigned control categories including:
Not every introduced plant is a declared pest or a significant environmental weed. Management priorities should therefore take account of legal status, invasiveness, distribution, potential impacts and the feasibility and benefits of control.
Introduced diseases, fungi and parasites can have significant effects on Australia’s native plants and animals as well as agricultural species. Native species may have little resistance to newly introduced pathogens, and some diseases can spread rapidly or be extremely difficult to eradicate after becoming established.
Diseases and pathogens relevant to biodiversity conservation in the Northern Agricultural Region include chytridiomycosis, disease caused by Phytophthora cinnamomi and psittacine beak and feather disease.
H5 high pathogenicity avian influenza (H5 bird flu) is an emerging biosecurity and conservation threat to the Northern Agricultural Region. Australia confirmed its first detections of H5 bird flu in wild migratory seabirds in Western Australia in June 2026, and further detections have also occurred in several Australian states.
The NAR contains important coastal, wetland and island habitats that support resident and migratory birds, including internationally significant seabird breeding colonies at the Houtman Abrolhos Islands. The Houtman Abrolhos Lesser Noddy (Anous tenuirostris melanops) has been assessed as being at extreme risk from H5 bird flu. It also presents a potential new threat to Australian sea lions (Neophoca cinerea) which are particularly vulnerable to additional pressures because they are endangered and have small, dispersed breeding populations. H5 bird flu also poses a significant biosecurity risk to poultry and other domestic birds and can infect some mammals, including domestic pets, particularly where they are exposed to infected birds or contaminated environments.
Surveillance has been increased in Western Australia’s Mid West, with government agencies monitoring priority coastal and island locations. Monitoring has included Lancelin and Edwards Island within the NAR. People should avoid handling sick or dead birds or other wildlife and report unusual illness or mortality in wildlife to the relevant authorities. Biosecurity, surveillance and rapid reporting are important for detecting the disease and reducing risks to wildlife and poultry.
Procedure for H5 avian influenza signs and how to report:
Chytridiomycosis is an infectious disease of amphibians caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd). The disease has contributed to severe declines in frog populations in Australia and internationally and is recognised as a Key Threatening Process under the Environment Protection and Biodiversity Conservation Act 1999.
The fungus has been recorded within the Northern Agricultural Region. Historical investigations of more than 4,000 Western Australian frog specimens found evidence that Bd had spread to Geraldton by 1998, with the documented zone of infection extending to just north of Geraldton. The study did not indicate that every frog population within this area was infected.
Chytrid fungus can be spread through infected amphibians and contaminated water, soil and other moist material. Reducing the movement of potentially contaminated water, mud, footwear and equipment between wetlands and other frog habitats can therefore help reduce the risk of spreading the pathogen.
Phytophthora cinnamomi is a soil-borne water mould, or oomycete, that causes root disease in susceptible plants. It can cause extensive vegetation decline and permanently alter affected ecosystems.
The pathogen can be spread through the movement of infested soil, mud and water, including on vehicles, machinery, footwear and equipment. Once established at a site it is extremely difficult to eradicate.
Good hygiene is therefore essential for reducing its spread. Vehicles, footwear, machinery and equipment should be free of soil and plant material when entering susceptible, uninfested areas. Land managers should also use disease-free plant and soil material and follow appropriate dieback-management procedures.
Disease caused by Phytophthora cinnamomi is listed as a Key Threatening Process under the EPBC Act and is subject to a national threat abatement plan. Further information and training is provided by the Dieback Working Group.
Psittacine beak and feather disease is a viral disease affecting parrots and related species. The virus can suppress immune function and cause characteristic abnormalities of the feathers and beak. Young birds can be particularly vulnerable.
The disease affecting endangered psittacine species is listed as a Key Threatening Process under the EPBC Act. It cannot currently be eradicated from wild populations, so management focuses on reducing risks to threatened species and maintaining resilient populations and habitat.
This is relevant to the NAR because the region provides important breeding and foraging habitat for threatened parrots, including Carnaby’s Cockatoo (Zanda latirostris).
Not all species that cause biosecurity or agricultural management problems are introduced.
Some Australian native species can become locally abundant or expand into areas outside their historical range, particularly where landscapes have been altered by agriculture, urban development, artificial water sources or changes in food availability. In some circumstances these populations can cause significant agricultural, environmental or social impacts.
Management of native animals is more complex than management of introduced pests because native fauna are also protected under biodiversity conservation legislation. Their legal and management status may vary according to species, subspecies, location and whether a population occurs within its natural range.
Corellas provide an important example in Western Australia. The legal and control status of Little Corellas varies between subspecies and between populations occurring within and outside their natural ranges. Management should therefore be based on current DPIRD and Department of Biodiversity, Conservation and Attractions advice rather than assuming that all corellas have the same pest status.
Emus may also cause agricultural impacts when large numbers move into cropping areas. The State Barrier Fence helps reduce the movement of large groups of emus from the rangelands into agricultural areas.
Wild-dog management requires particular care in terminology because wild-dog populations can include dingoes, feral domestic dogs and hybrids. Management objectives and legal requirements should therefore reflect the location, animals involved and relevant Western Australian legislation.
The legal status of pest organisms in Western Australia can change. Current status and control requirements should be checked using the Western Australian Organism List (WAOL) and current DPIRD guidance.
Everyone can contribute to preventing the introduction and spread of invasive species.
Landholders and land managers have responsibilities under Western Australian biosecurity legislation for the management of declared pests. Community members can also help by reporting unusual pests or diseases, avoiding the movement of contaminated soil and plant material, practising good vehicle and equipment hygiene, managing garden plants responsibly and following biosecurity requirements when travelling between properties, natural areas and offshore islands.
Early detection is particularly important. Identifying and responding to a new pest, weed or disease before it becomes widely established can substantially reduce its environmental, agricultural, cultural and economic impacts.
Department of Climate Change, Energy, the Environment and Water (DCCEEW):
Department of Agriculture, Fisheries and Forestry (DAFF)
