State of the Environment Report 2007
Introduced marine species are those that have moved from their natural environment to an area where they can potentially threaten human health, economic values or the environment. Introduced species are a global problem, and second only to habitat change and loss in reducing global biodiversity (Millennium Ecosystem Assessment, 2005). Most introduced marine species are benign, causing no known adverse effects. However some species become invasive in a new environment (see 'Introduced animals').
The introduction of new species can be deliberate or accidental. There have been very few deliberate introductions to the marine environment in WA. Accidental introductions are primarily due to vessel movements and transport activities. In the past, the use of ballast water has allowed many introduced species to be transported around the world and released into new environments. Quarantine measures for ballast water are now in place to prevent incursions. Introduced species also arrive naturally via marine debris and ocean currents. Hull fouling or biofouling (the growth of organisms such as barnacles, mussels, marine worms or seaweeds) is another way in which marine species can be transported around the world. The potential for international commercial ships to act as vectors for spreading marine species is well recognised, but other vessels or equipment can also transport marine species, including dredges, oil rigs, aquaculture gear, illegal fishing boats, recreational vessels and international yachts. Tributyltin (or TBT) paint has been widely used to prevent organisms adhering to hulls, but the compound is highly toxic to many marine species. Tributyltin paints are currently banned internationally for vessels under 25 m in length, and plans are in place to phase it out on larger vessels.
The impacts of introduced marine species can include predation on native and farmed species, prolific colonisation, increased competition for habitat and food, altered nutrient cycles, and a loss of diversity in native species. In addition to environmental consequences, some introduced marine species have the potential to harm human health (e.g. cholera, paralytic shellfish poisoning), affect commercial fish and seafood species and increase fuel consumption of ships (hull fouling organisms). Aquarium species can become invasive if released into the marine environment and may act as vectors for spread of diseases.
Over 250 species are likely to have been introduced to Australian marine waters (CRC Reef Research Centre, n.d.). The exact number is unknown due to inadequate survey and taxonomic work.
The Department of Fisheries records 92 species being present in WA (some are presented in Table M3.1) (Department of Fisheries, 2005). CSIRO has recorded 43 introduced marine species using the National Introduced Marine Pest Information System (Centre for Research on Introduced Marine Pests, 2002). There are many gaps in knowledge and the information is not current. Irrespective of which data source is used, the number for introduced marine species in WA represents a significant increase from the 26 reported in 1998 (Government of Western Australia, 1998a). Detection procedures have significantly improved over the period.
![Table M3.1: Examples of introduced marine species currently found in WA. [Data source: Department of Fisheries (2005a; 2005b); Hayes et al. (2005). .]](/site/files/images/Table-M3.1_Large.jpg)
None of the introduced marine species known to currently be in WA appear on the Global Invasive Species Database of the worst invasive species from across the world; however two species on the list have previously been recorded (Global Invasive Species Database, 2007). The green crab (Carcinus maenas) was discovered in WA in 1965 at Blackwall Reach in the Swan River (Table M3.2), but it has not been found in recent years. In addition, the blue mussel (Mytilus edulis) is found in WA waters but there is current debate about whether or not it is the same as the European species of the same name (which is known as an invasive species). While it is possible the species occurs naturally in Australia, it is also possible that it arrived with European settlers. It is farmed in Western Australia but isn't known to invade native ecosystems in the same way as the European species.
An attempt to introduce the Pacific oyster (Crassostrea gigas) to Oyster Harbour Albany was made in 1947, in an attempt to establish a new commercial industry. This introduction was unsuccessful - a good thing for WA because the oyster is established in the wild elsewhere in Australia, and is able to outcompete native oyster species.
Limited studies have found introduced marine species at various locations around WA (Table M3.2). Wide scale surveys for the State are lacking and ongoing monitoring is not generally undertaken (except for biosecurity monitoring by quarantine services). Environmental approvals for maritime facilities sometimes have requirements for baseline and ongoing surveys for introduced marine species. The Department of Fisheries is currently collating the information known about introduced marine species in Western Australia, but this information is not yet available. Some port facilities have not yet been surveyed for introduced marine species (notably Dampier) and the distribution of many introduced species remains unknown. Poor baseline data also means it is sometimes difficult to distinguish introduced from native species (these species are known as cryptogenic).
Recent incursions into WA marine waters include the thaid snails into the port of Geraldton and black striped mussels in Broome (Mytilopsis sallei). In both cases, early detection and removal of the animals prevented the establishment of these potential pests. Once a species becomes established in the marine environment, it is almost impossible to eradicate.
The risks posed by introduced marine species depend on various factors, including the impact of the introduced species on native organisms and commercial activities; proven invasiveness of the organism; ecological conditions to which the organism is adapted; volume and source of ballast water transported; survivorship of organisms during a voyage; and effectiveness or otherwise of detection and prevention programs.
There are many species that have the potential to be introduced to WA and become invasive (Table M3.3). National and state agencies are very aware of the potential problems posed by these animals and emergency action plans can invoked if they are found in WA waters. Several introduced species already found in WA (Table M3.1) have been assessed by CSIRO as medium priority ranked species (ie. has a reasonably high impact and/or invasive potential). The highest priority ranked species are not currently found in WA (Table M3.3), but they do have potential to spread widely if they become established. The analysis considered the movements of international and interstate commercial shipping only and did not include the movements of small recreational and commercial vessels (Hayes et al., 2005). The inclusion of hull fouling potential (coupled with the large number) of these vessels would undoubtedly have an influence on the relative ranking of potential domestic target species.
Approximately 98 million tonnes of ballast water were discharged in WA waters during the 5812 commercial vessel visits in 2003-04 (A Morley, Australian Quarantine Inspection Service, pers. comm.). The Central West Coast marine region includes the ports of Fremantle and Geraldton. This region records the most ballast discharged in WA (519 860 tonnes), but is somewhat biased because only large commercial ships with the last port of call in Australia were included (Hayes et al., 2005). The ballast water discharged by smaller craft is largely unknown, but when considered cumulatively is likely to be significant.
The amount of ballast water discharged is not necessarily a large risk factor now that improved and more rigorous customs procedures apply. Australian Quarantine Inspection Service mandatory ballast water reporting requirements apply to all ships arriving in Australian ports from overseas. This means that all vessels intending to discharge at Australian ports are required to exchange their ballast water at sea, prior to entering Australian waters. However, potential gaps exist including incomplete exchange of ballast water at sea and vessels traveling from other Australian ports that currently do not have to report. Inspections for introduced marine species is lacking outside major ports (especially pleasure craft or illegal boats).
International Convention for the Control and Management of Ships' Ballast Water and Sediments: begun in 2004 with the intent to prevent, minimise and ultimately eliminate the transfer of harmful aquatic organisms and pathogens through the control and management of ship's ballast water and sediments. Australia signed the convention in 2005, and it will be ratified once it is signed by 30 countries representing 35% of world merchant shipping.
Australian Quarantine and Inspection Services: has a compulsory risk assessment procedure which must be undertaken by every vessel entering Australian waters before ballast discharge can occur. Vessels must keep accurate records of ports visited, size of ballast tanks, source of ballast water, location at beginning and end of ballast exchange and Australian ports to be visited. Australian Quarantine and Inspection Services officers conduct ballast water verification inspections on-board vessels to ensure compliance with Australia's ballast water management requirements.
The Australian Quarantine and Inspection Service is currently developing a legislative framework for managing the biofouling risk of all international vessels arriving in Australia. Currently, only voluntary protocols are in place for the management of biofouling on international vessels less than 25 m in length and vessels of any length apprehended for illegal activities or rescued.
Centre for Research on Introduced Marine Pests: CSIRO has previously operated a specialised marine pest section, that was focused on bio-fouling and ballast water. The Centre set up the National Introduced Marine Pest Information System (NIMPIS) database, which was last updated in 2005. The Centre has now been closed.
The National Introduced Marine Pests Coordinating Group: is responsible for developing the National System for the Prevention and Management of Marine Pest Incursions and has coordinated the development of an intergovernmental agreement between the Commonwealth and the states. It includes representatives from State and Territory agencies, marine industries, scientists and conservation groups. The group is currently developing policy instructions for the proposed Biosecurity and Agriculture Management Bill and provides the basis for drafting instructions to give effect to the Ballast Water Management Arrangements.
The Intergovernmental Agreement (IGA) on a National System for the Prevention and Management of Marine Pest Incursions: was signed by WA in 2005 and sets out a framework to address all marine pest risks and includes governance and infrastructure arrangements, measures for prevention (focused on ballast water and biofouling risks), emergency response, ongoing management and control, and supporting arrangements for monitoring, communications, research and development, and evaluation and review. Under the agreement, WA is required to implement legislation that will allow the State to introduce management arrangements that are complimentary to the International Convention for the Control and Management of Ships Ballast Water and Sediments, as well as to the National System.
Actions to implement and complement the National System for the Prevention and Management of Introduced Marine Pests in Western Australia: are underway, coordinated by the Department of Fisheries, to initiate a Statewide program to determine the extent of the existing introduced marine pest problem and develop strategies that can minimise further introductions.
Australian Marine Pest Monitoring Guidelines: sets out guidelines for conducting marine pest monitoring programs in Australia, but is not yet underway.
Introduced marine pest management: In WA, the Department of Fisheries, the Department for Planning and Infrastructure, and individual port authorities have the responsibility and jurisdiction to manage marine pests. Within Western Australia, the Department of Fisheries has been appointed as the lead Agency to develop and implement the necessary management arrangements and biosecurity control activities to, where possible, restrict the introduction and translocation of introduced in relation to fish and the aquatic environment.
Legislation: A Biosecurity and Agriculture Management Bill has been drafted to provide effective biosecurity and agriculture management for Western Australia. It seeks to prevent serious pests, weeds and diseases that impact primary production, the environment or public amenity from entering the State, and to minimise the spread and impact of any that are already present. There will be regulations under the Act developed in relation to minimising the risk of translocating marine pests through ballast water management and vessel biofouling (a requirement under the intergovernmental agreement). The bill was passed by the Lower House of Parliament in 2006 and has been introduced to the Upper House.
The Australian Quarantine and Inspection Service is currently preparing to introduce a legislative framework for the management of the biofouling. The National Introduced Marine Pests Coordinating Group is developing guidelines, voluntary protocols or regulations for managing the marine pest risks from biofouling for aquaculture, commercial fishing, commercial shipping and non-trading commercial vessels, recreational vessels, marine facilities (such as ports, marinas, slipways, shipyards and dry docks) and the petroleum industry.
Research: The CRC Reef Research Centre in Townsville conducted a pilot study to test a variety of methods of sterilising ballast water, including filtration, ultraviolet light, chlorine dioxide dosing and high velocity sonic or shear disintegrator. They have published data on the positive and negative aspects of various treatment methods and on unsuitable treatment methods (Hillman, Hoedt & Schneider, 2004). CSIRO has projects in place to support the updates to the National System for the Prevention and Management of Marine Pest Incursions, conduct ballast water risk assessment, and genetic work on introduced marine algae. The Defence Science and Technology Organisation conducts research on antifouling compounds for use in paints for vessel hulls to replace tributyltin.
Failure to control introduced marine species is likely to result in the loss of biodiversity and decline or extinction of native marine species. The potential economic cost of introduced marine species is enormous, and includes costs of control measures, loss of biodiversity, and damage to fisheries and shipping industries in addition to potential effects on public health and recreational amenity. With further population growth and associated travel, transport and trade, the risk of introducing new species is likely to increase (Convention on Biological Diversity, 2005). Hull fouling needs to be prevented but many of the suggested replacements for tributyltin are also likely to be toxic to native marine species. Current Commonwealth and State legislation does not deal adequately with the threat of introduced marine species as a result of hull fouling on international vessels, or the management of quarantine risks associated with domestic vessel movements. The proposed Biosecurity and Agriculture Management Act should strengthen Western Australia's capacity to act in these areas. Illegal fishing vessels may represent a significant future risk for introduced marine species into Australian waters.
6.9 Establish baseline survey data to distinguish native from introduced marine species.
6.10 Clarify and strengthen governance arrangements for responding to incursions of introduced marine species and their elimination.
