Appendix B

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This appendix provides background information to assist with implementing the Guidelines for Assessing the Translocation of Live Aquatic Organisms in Victoria, and outlines the types of risk to the environment from translocations and describes the specific risks associated with them.

Three simple and measurable endpoints (Hayes 1997) are used to assess the risk¹ arising from translocation proposals:

• the likelihood and consequences of escape and/or release;
• the likelihood and consequences of survival; and
• the likelihood and consequences of establishment (of a feral population).

Each of the risks associated with each endpoint is assessed through the series of questions for closed or semi-closed systems such as aquaculture (Table 1) and open systems such as the wild release for angling, biodiversity conservation or other purposes (Table 2). These risks should be used as a guide when preparing risk assessments for proposed translocation of live aquatic biota.

In assessing the risks of a translocation, the challenge is to assess the reversibility of the proposed introduction and any adverse effects it may have. It is important to recognise that the risks include, in addition to the species in question, associated aquatic habitats, organisms, parasites and diseases.

After determining the potential risks of a translocation, the aim is to avoid unnecessary risks, reduce high risks and to manage residual risks.

¹ The risk assessment process outlined in this policy conforms with that outlined in the National Policy For The Translocation Of Live Aquatic Organisms and is consistent with Australia – New Zealand Standard 4360.

Application of risk assessment

Subject to law

Proposals to translocate aquatic organisms into and within Victoria must comply with relevant Victorian and Commonwealth law. A species will only be considered as a candidate for translocation if possession of the species does not conflict with restrictions imposed under legislation. Such legislation may relate to the survival of a species or to the ecosystem in which it occurs or where the presence of the species could adversely affect the Australian environment. Proposals must also comply with bilateral or multilateral agreements that may exist for multi-State river basins.

Issues of scale

It is not possible, nor potentially relevant, to undertake a prior assessment of every proposed individual translocation of a live aquatic organism. Proposals perceived to involve greater risk may also require considerably more robust analysis and direct research to answer particular questions.

Uncertainty

Assessment of potential risk is by its nature an uncertain process. The degree of uncertainty will vary between proposals and it may not be possible to answer all questions outlined in Tables 1 and 2. The final decision will be a 'risk-weighted assessment' of the proposal as agreed in Commonwealth Intergovernmental Agreement on the Environment.

Authoritative risk assessment

This risk assessment must be conducted by a person(s) recognised as having relevant expertise in assessing the risks posed by the translocation of live aquatic organisms. It will be the responsibility of the proponent to organise and fund preparation of the risk assessment and demonstrate the assessor's expertise.

Background risk

Where a particular situation or risk (e.g. disease outbreak, existence of a feral population, prior stocking or likelihood of introduction by other means) already exists in receiving waters, it will be considered in assessing the impact on the receiving waters from a further translocation of the organism. Existing risk abatement regimes that mitigate the risks to the receiving waters will be considered when assessing the translocation proposal.

Risk thresholds

The extent to which risks are accepted and tolerated is likely to evolve with changing perceptions and understanding of the risk and changes in the value of the area that may be affected by the risks. In reflecting community values and the level of scientific certainty, the risk thresholds established by Victorian legislation and strategy usually define those risks that are unacceptable or intolerable². As outlined in the Victorian River Health Strategy (Department of Natural Resources and Environment, 2002), for example, this is determined individually or collectively by various environmental, social or economic considerations, including:

• Protecting social assets such as human health and recreation.
  
  Example 1: The electric eel (Electrophorus electricus) poses a threat to human-safety because of the electric shock it can produce. Importation into Victoria and possession in the State is prohibited through its listing as a noxious aquatic species under the Fisheries Act 1995 (the Act).
  
  Example 2: The sharp, brittle edges of the shell of the Pacific oyster (Crassostrea gigas) can injure the feet of people who step on it. For this and other reasons, aquaculture of the Pacific oyster is not permitted in the wild in Victoria.
• Protecting environmental assets such as: endangered fish, areas of importance for their indigenous flora and fauna, and river catchments that contain stream networks in good ecological condition.
  
  Example 1: To ensure the protection of the endangered trout cod (Maccullochella macquariensis) and Macquarie perch (Macquaria australasica), predatory exotic fish are not stocked in Seven Creeks or in areas that would lead to their immediate introduction to Seven Creeks.
  
  Example 2: A management objective for areas scheduled under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (the EPBC Act), or areas managed under the provisions of that Act, is the preservation and protection of indigenous flora and fauna within particular areas. To assist in achieving this objective, the EPBC Act requires that exotic flora and fauna be either exterminated, eradicated or controlled within such areas.
  
  Example 3: There are relatively few exotic species in the streams of catchments east of the Snowy River. Stocking fish into these systems is not permitted because of the long-standing administrative agreement on the values of these streams. For some catchments, this administrative agreement is explicitly reinforced by the Victorian Heritage River Act 1992, which requires all reasonable steps to ensure that areas, known as essentially natural catchments, are maintained in an essentially natural condition.
• Protecting economic assets by reducing the risk of disease and the threat to ecosystem services
  
  Example 1: Ecosystems provide services of considerable economic benefit such as the removal of nutrients introduced to water bodies from licensed discharges, catchment run-off and the production of fish for human consumption. For these reasons, species such as the sabella worm and the Northern Pacific seastar (Asterias amurensis) are declared as noxious aquatic species under the Fisheries Act 1995.

² Standards Australia International and Standards New Zealand (2000) describe the concepts of tolerability and acceptability in more detail.

Making decisions

Decisions regarding translocation proposals are based on the risk being acceptable. This may include restrictions on the numbers, sizes, origins, genotypes or other characteristics of the live aquatic organisms in question, quarantine protocols, improvements to security of containment facilities and contingency planning.

The views of the 'land' manager obtained during the translocation evaluation process will be an important consideration in determining the acceptability of risk.

Environmental risk

Environmental risks associated with the translocation of aquatic organism can be divided into the following main categories:

• environmental/ecological issues;
• disease and parasite introduction; and
• chemical release.

Environmental/ecological issues

The translocation of aquatic organisms may create several environmental/ecological risks:

• genetic shift in wild populations;
• establishment of feral populations;
• environmental impacts from the release of the species; and
• translocation of associated species (e.g. parasites).

Many of these risks are discussed in the National Strategy for the Conservation of Australia's Biological Diversity (the National Biodiversity Strategy) (Department of the Environment, Sport and Territories, 1996).

Genetic shift in wild populations

Translocated species that escape or are deliberately released into the wild may breed with other distinct populations of the same species, possibly resulting in a genetic shift in the local population. Similarly, hybridisation between endemic species and translocated species where the species are genetically compatible may occur. This is a particular risk associated with inappropriate stocking of native species for stock enhancement.

Genetically modified organisms (GMOs) pose specific concerns where their modifications may provide a competitive advantage over unmodified wild organisms (potentially resulting in displacement of the latter). Traits of GMOs may also be transferred to local populations through inter-breeding. However, GMO technology may also be used to reduce the risks posed to receiving waters from escapes by producing animals that are incapable of breeding or have specific dietary requirements that preclude that organism's survival in the wild.

The risk of genetic shift in wild populations can be minimised by ensuring that the translocated organisms are of the same genetic stock as local populations. This may be achieved by sourcing broodstock from that area or from connected populations.

Risk may also be minimised by reducing the number of organisms translocated. If lower numbers are translocated, there is less reproductive potential and consequently less potential for genetic shift. Given the high fecundity of many aquatic organisms, however, this may not have a significant impact on managing the genetic risks.

On a similar note, translocating organisms with relatively lower fecundity may also reduce reproductive potential and therefore reduce the risk of genetic shift.

Although it rarely occurs to a significant degree in nature, hybridisation, for example trout cod-Murray cod (Maccullochella peelii peelii) or estuary perch (Macquaria colonorum)- Australian bass (Macquaria novemaculeata), could increase with inappropriate stockings.

Establishment of feral populations

Feral populations are populations that successfully establish in an area because of the escape or release of non-endemic or exotic organisms. This may be a population of the plants or animals being translocated or a population of a secondary organism that was translocated along with the primary organism (e.g. attached parasites or species in the transport medium).

Feral populations can result from the escape or release of zygotes (fertilised eggs) or gametes (eggs and sperm) of translocated species to natural water bodies.

Through competition, predation and environmental modification, feral populations can have a range of adverse environmental effects on endemic communities. Examples of species that have established feral populations include European carp (Cyprinus carpio), redfin perch (Perca fluviatilis), marron (Cherax tenuimanus), yabbies (Cherax destructor), Murray cod, trout cod, Macquarie perch, freshwater catfish (Tandanus tandanus), oriental weatherloach (Misgurnus anguillicaudatus), tilapia (Tilapia and Sarotherodon sp.), mosquito fish (Gambusia sp.), swordtails (Xiphophorus sp), trout (Salmo, Oncorhynchus and Salvelinus sp.) and cord-grass (Spartina sp.).

Some feral populations may have been planned and authorised (e.g. recreational stocking, biological control programs or native species enhancement).

In closed and semi-closed systems, the risk of feral populations becoming established can be minimised through adequate containment of adults, juveniles, zygotes and gametes combined with appropriate contingency planning.

Where containment is considered inadequate, an assessment of the species' ability to establish feral populations is required and would include consideration of the following criteria:

• the natural range of the species and similarities, for example climatic conditions, weather patterns, between the natural range and target location;
• the current range of the species including its history, if any, of establishing feral populations elsewhere;
• the known environmental requirements for all stages of the lifecycle if these requirements will be met in the receiving waters;
• the food requirements for all stages of the lifecycle and if these requirements will be met in the receiving waters; and
• the habitat requirements for all stages of the lifecycle, for example the need for a specific type of breeding site, and if these requirements will be met in the receiving waters habitat requirements.

Risks of establishing feral populations may be minimised through the translocation of only one sex (in dioecious, non-sequential hermaphroditic species) or infertile individuals or those with reduced fertility (e.g. triploids, hybrids).

Environmental impacts from escaped organisms

Regardless of their ability to establish self sustaining populations in receiving waters, translocated organisms may survive long enough in natural waterways to create environmental impacts including competition, displacement, predation and habitat alteration. This can have resultant impacts at the individual, population, community and ecological process level.

Translocated organisms that escape to natural water bodies may compete with and displace local species, potentially causing long-lasting changes to the community structure. Additionally, translocated organisms may prey on endemic species.

In many cases, endemic species will be at greater risk to the translocated predator because there has been no predator-prey co-evolution between the species. This may be particularly devastating if the local species are not normally preyed on, and consequently, have not developed defence mechanisms or appropriate behaviour patterns.

Translocated organisms may alter the habitats of natural waterways in many ways, including:

• the creation of burrows and destabilisation of banks (e.g. yabbies);
• disturbance of aquatic vegetation with consequential effects on erosion, water quality and habitat of native species (e.g. European carp);
• predation of native species (e.g. trout);
• the overgrowth of the surface of the water body (e.g. water hyacinth Salvinia molesta); and
• the removal or depletion of food supply.

In closed and semi-closed systems the risk of adverse environmental impacts may be reduced through adequate containment of adults, juveniles, zygotes and gametes, combined with appropriate contingency plans to address escapes of stock.

In open systems, or where containment is minimal, an assessment of the species' potential for environmental impacts that is based on a thorough understanding of the ecology of both the translocated species and the target region is required.

Translocation of associated species

There may be a risk that associated species including larvae and juvenile animals will be translocated along with the target species. This may include species that are:

• similar in appearance to the organism;
• on, or in, the target organism; or
• on, or in, the transport medium.

Specific instances of this apply to shellfish spat and finfish fingerlings being translocated from hatcheries (e.g. mussels (Mytilus galloprovincialis and M. edulis) and abalone (Haliotis sp.), golden perch (Macquaria ambigua) and silver perch (Bidyanus bidyanus), Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss)).

Translocation of associated species may also take place through the movement of species located external (i.e. epifauna and ecto-parasites on shells, gills and scales) and internal (e.g. endo-parasites, microalgal cysts) to the target organism.

The risks of translocation of other species can be minimised through appropriate certification of hatchery stock. In closed and semi-closed systems, appropriate quarantine, containment and contingency plans will minimise the risk of release of associated species to natural water bodies. Risks can be further minimised for filter feeders through depuration procedures and treatment before release.

With most translocations, the organisms will be transported in a medium, typically water. The fate of this medium also needs to be considered as it may contain undesirable organisms. This is of particular concern if the stock comes from an area where parasites, algal blooms or disease outbreaks are current or common and these organisms are not present in the receiving waters.

Risk can be reduced by appropriate treatment and disposal of transport media, including the appropriate treatment (e.g. cleaning, drying.) of transport equipment (e.g. cages, ropes, nets, racks, tanks).

Disease and parasites

The principal cause for concern in this risk category is the possible introduction of an exotic pathogen (bacteria, viruses, ecto- and endoparasites, fungi) into the natural water bodies and subsequent infection of existing species. The translocation of endemic pathogens to new areas is also a primary concern.

A population exposed to a new pathogen may be particularly susceptible and a common response is mass mortalities. The effects may be increased if the population is already stressed, e.g. through habitat degradation or overfishing.

There will be fluctuations in the composition and abundance of species and there is always a risk of extreme virulence that will reduce a population so much that it may not recover. Organisms that survive will show some resistance, which in due course may help the population in re-establishing itself. This, however, does not mitigate the risk of introducing diseases and parasites. There is often a time lag between introducing an infectious agent and the appearance of clinical disease (if environmental conditions are good, there may not be a disease outbreak for some time following introduction).

Parasites and disease are an integral part of any natural system. However, the introduction of a disease or parasite (not necessarily an exotic disease) into a natural water body could change the existing 'pathogen status' of the waters. The introduction may perpetuate or aggravate existing diseases by increasing their incidence, virulence, potency and frequency and may reduce the competitiveness of the affected species. This impact may apply to parasites such as ectoparasites on farmed fish including fungal flora and gut parasites. It may also have significant ramifications for translocation of, or trade in, aquatic organisms or products from the area.

There are many examples of species carrying unwanted diseases. These include goldfish and roach, which may carry the organism causing goldfish ulcer disease (Aeromonas salmonicida); barramundi which may carry a virus (Nodavirus); abalone which may carry the Perkinsus parasite or abalone ganglioneuritis; and redfin which may carry epizootic haematopoietic necrosis virus.

It is important to note that some species in the receiving waters may not be susceptible to the introduced agent but may act as carriers, helping to establish the pathogen without exhibiting clinical signs of infection. If other susceptible species are translocated at a later stage, then disease may break out. Furthermore, many bacteria and parasites do not need a fish host and once introduced into the water system can survive without the presence of susceptible or non-susceptible host.

The risk of transferring parasites and diseases into the environment from an aquaculture facility can be reduced through containment of the farmed species, appropriate treatment of discharged wastes and proper disposal of any transport medium used to transport live aquatic organisms. Risk of parasite and disease transfer can also be reduced through the implementation of health certification processes, appropriate quarantine procedures, targeted surveillance and monitoring programs in hatchery facilities, and disease zoning policies.

Where quarantine or health certification is not practical, for example in the live seafood trade, knowledge of the pest and disease status of the source area will provide information on the likely disease status of stock taken from that region. Similarly, regular surveillance and monitoring of wild stock fisheries can assist in providing early indications of potential parasite and disease problems.

Chemical release and management

Many aquatic species, especially those that are farmed or inhabit polluted waters, may be exposed to drugs and other chemicals. Many of these substances have adverse environmental and marketing consequences. The risk from translocation arises when undesirable chemicals are transported either in the transport medium or as residues in the stock itself.

Risks may be minimised by appropriate treatment and disposal of the transport medium, using contaminant free stock, depuration of shellfish, adoption of appropriate monitoring and testing regimes and adhering to the usage regulations of chemicals registered by the Australian Pesticides and Veterinary Medicines Authority (APVMA). Enclosing facilities within bunds and developing appropriate contingency plans that address events such as flooding will reduce the risk of release of unwanted chemicals to natural waters.

Types of translocations

Translocations can be proposed for a number of purposes including:

• stocking for recreational and commercial fishing and conservation;
• open water aquaculture systems;
• land-based aquaculture systems;
• research and/or display facilities;
• live bait;
• live seafood trade; and
• aquarium trade.

The following discussion provides a general indication of the potential risks that may be involved.

Stocking programs and open water aquaculture systems

Live aquatic organisms translocated to open systems including aquaculture can affect catchment drainage systems. In these cases, the assessment of risk should consider the potential for the species to affect the ecology and general environment of the waters into which they are stocked.

Risks

Genetic shifts or the loss of genetic diversity in wild populations may be a risk if there are existing populations of the translocated species in the receiving waters. Where the stock to be translocated and produced in a hatchery, this risk can be reduced by using broodstock obtained from the area proposed for stocking.

If populations of the translocated species are not present in the target area, the risk of establishing a feral population should be assessed. In some cases, this might be the desired outcome.

As there is little or no ability to contain stock in open systems, translocated species may interact with aquatic and non-aquatic components of the receiving ecosystem. An adequate assessment of translocation risks should therefore be based on a thorough knowledge of the translocated species, its ecology and the ecology of and potential impacts on the receiving waters.

Containment of undetected and undesirable associated species translocated along with the target species is not possible in open systems and is a major concern when introducing wild stock. Assessments of risk should be based on knowledge of the status of the receiving waters and source areas. Risks may be further minimised through depuration, transfer to fresh media before release and by ensuring that the transport media and containers are disposed of appropriately after use. To assist in managing this risk, organisms should be transported in media taken from the receiving area. Quarantine periods may be appropriate.

With hatchery-reared stock, certification of disease and parasite status may reduce the risks of translocation. Where certifying the health of stock is not possible, monitoring and surveillance before translocation may be used to certify the status of the stock.

Land-based aquaculture systems, contained research or display facilities

The primary risk issues in issues in land-based, contained research and display facilities are containment of stock, treatment and disposal of wastewater and surplus stock and contingency plans in case of emergency. In determining the adequacy of the risk management processes employed to manage these risks, the consequences of stock escape should be considered. If all of the risk management measures are adequate, the translocation may be approved.

If containment, water treatment and disposal and contingency plans are inadequate, an assessment should be made based on the potential for the species and associated species, parasites and diseases to affect the ecology and general environment of the receiving waters. Where stock for these facilities come from hatcheries, disease status, water quality and information on associated species should be available.

Risks

Aquaculture, research and display centres often hold large numbers of stock that, should they escape, could affect populations of native organisms. The risk arises from the release of mature fish, juveniles, gametes and zygotes and associated species. In closed or semi-closed systems, risk can be minimised through appropriate containment of all life stages, treatment and disposal of wastewater and having appropriate contingency plans in place.

Risks may also minimised by locating and operating the facility with no open connection to any watercourse thus preventing escapees from entering natural water bodies.

If containment is insufficient and there is a risk of stock being released in an emergency, risks may be reduced by using broodstock obtained from local populations. If local broodstock are not available, the potential for the organism to establish a feral population and its impacts on the receiving environment should be considered in the risk assessment.

Managing risks of translocations of associated organisms including parasites and diseases may be addressed by appropriately treating and disposing of wastewater and stock and contingency planning as outlined above. The likelihood of pest and disease outbreak is greater in closed culture systems and research and display facilities where stocking rates can be high. If containment, treatment or contingency plans may be inadequate, and there is potential for organisms or wastewater to enter the natural environment then the likelihood of the stock carrying disease should be assessed. This risk may be reduced through health certification, inspection and quarantine procedures.

Live bait

Because live bait is released into natural water bodies, there are many concerns about its translocation. Although this discussion only deals with live bait, many of the issues raised below are also relevant to the translocation of dead bait. Translocations of live bait are characterised by the movement of small numbers of individuals over relatively short distances. The high fecundity of many aquatic species that are used as bait means that small populations may have a large reproductive potential should they escape. Although animals used for live bait often originate from wild stock, some bait species are cultured.

There is increasing concern over the use of imported organisms not originally destined for the bait market being used as live or dead bait. These animals may not have been screened on the same basis as they would have been if it were known they would be used as bait.

The concerns related to transport medium, disease and associated species are particularly relevant because the stock are often taken from the wild and handled and distributed by the public. Consequently, rigorous handling and waste disposal procedures are not often used.

Risks

Although the material is released to natural water bodies, the number of animals is generally low and the organisms often killed during use. Bait species may, however, establish feral populations if they survive the translocation, are released in sufficient numbers and the environment of the receiving waters is favourable to them. The potential risk may be assessed through an understanding of the species and its habitat requirements.

As individuals often carry out these inadvertent translocations independently and are not subject to an approval process, the implementation of a rigorous policy is difficult. If a substantial release is likely, for example a live bait production facility, the facility should be treated as for a closed aquaculture facility.

Live fish trade

Animals for the live fish trade including shellfish and crustaceans are usually obtained from wild populations or aquaculture operations and transported to processors, markets or restaurants. Although there is legitimate concern about the translocation of live fish, receivers can be encouraged to treat stock and wastewater appropriately.

A major concern is the fate of the stock after it is sold because restaurants and individuals that purchase live product may not dispose of the transport media and offal in a manner that prevents impacts on the aquatic environment.

Risks

As live fish are a valued commodity, it is likely the number of animals that enter natural water bodies will be small. Given the high fecundity of many aquatic organisms, this may not mitigate potential effects. If stock comes from wild populations, issues related to water quality, associated species and disease status are unlikely to be known.

In some instances, non-endemic bivalve molluscs for the seafood trade may be held in natural waters while awaiting consumption. If this is to occur, the translocation should be assessed as for an open aquaculture system.

There is a risk of transporting unwanted parasites and diseases with live seafood. Disease-free certification is impractical with live, wild caught stock, and quarantine is unlikely to be an acceptable technique because of delays in marketing fresh product. Consequently, the only risk management options available are knowledge of the parasite and disease status of the source area and appropriate disposal of remains and transport medium after the seafood has been processed. This is likely to be difficult, because there is little opportunity to enforce any such requirements. The low numbers of animals that might escape to the aquatic environment reduces the environmental risk.

Additionally, there is a risk of movement of undesirable species in the transport media including toxic dinoflagellates and blue green algae. Risks may be minimised through appropriate treatment and disposal of the transport media and containers.

Aquarium trade

The aquarium trade includes marine and freshwater species that are endemic to Australia or exotic species that are translocated to Australia or bred from stock already in the country. Some species are collected from the wild.

Aquarium stock is typically distributed to shops and on-sold to the public and the trade is largely uncontrolled beyond the retail level. The relative simplicity of producing many popular aquarium species in 'backyard culture' facilities increases the risk of introducing parasites and disease. Such facilities are often small scale (and often unknown to authorities) and therefore not subject to the regulatory regimes applied to other aquaculture facilities.

Aquarium species and associated organisms may be transferred throughout Australia as fish-owners move and transport their pets and equipment. As with translocation of live bait, a major risk mitigation strategy is effective education of the public of the environmental concerns that relate to the unauthorised release of aquarium species. As sources of information on risk and the facilities for appropriate disposal of unwanted animals, aquarium retail outlets play a valuable role in this education process.

A hatchery for aquarium species should be assessed as a closed aquaculture system.

Risks

Exotic marine aquarium species listed on Part 1 of the List of Specimens taken to be suitable for live import (the Schedule) of the EPBC Act may, unless genetically modified, be imported into Australia. Additional species may be added to the Schedule following satisfactory evaluation under a risk assessment process that assesses their potential to become pests or to introduce disease and parasites.

The potential for environmental effects has not necessarily been assessed for all aquarium species listed on the Schedule and all risk categories may need to be considered depending on the source of stock and destination of the translocation. For example, more than 15 exotic species have established sustainable populations in Queensland waters. Regulation of the domestic aquarium trade is the jurisdiction of State and Territory Governments. The EPBC Act does not provide a mechanism to 'recall' a species that is removed from the Schedule or which is not listed at all.

Australian States and Territories have taken one or both of two approaches to managing exotic fishes in the aquarium trade: permitted and prohibited species lists. While Victoria's approach is based on the latter, it is recognised that in the absence of these Guidelines, there would be no mechanism to consider the trade in species whose pest and disease status is unknown.

In accordance with A Strategic Approach to the Management of Ornamental Fish in Australia (Department of Agriculture Forestry and Fisheries 2006), all State and Territory jurisdictions agreed to implement consistent noxious aquatic species list that includes species on the agreed national list and those species relevant to the jurisdiction. Species included in the document 'grey list' that, through a risk assessment process are determined to have the potential to become pests or to introduce disease and parasites, will be added to lists of noxious aquatic species.

The environmental risks associated with translocation of aquarium fish and plants will vary. Tropical aquarium species may have limited survival capacity in the cooler waters of southern Australia, but the warmer waters in cooling ponds associated with power stations can provide an ideal environment for many species.

Although aquarium species are generally released in small numbers, the lack of natural predators and the documented survival characteristics of some species suggest they may have a good chance of establishing feral populations in Australian waters if basic habitat requirements are met. This is also relevant to plants bred for the aquarium trade, which are selected for their robustness and vigour. An example is the green alga Caulerpa taxifolia. This aquarium plant, a declared noxious aquatic species under the Act, has entered the marine environment in some parts of the world and despite attempts to control it, has spread rapidly through shallow, littoral environments.

The translocation of disease by aquarium species is of particular concern. There are known cases of aquarium species carrying disease (e.g. goldfish ulcer disease) that can cause significant damage to wild fish stocks and aquaculture operations. Where possible, risk can be minimised by the use of hatchery stock that is appropriately certified as free of parasites and disease. As indicated above, a major potential disease risk arises from organisms produced in facilities that are not subject to licensing or regulation.

Table 1: Translocation risk assessment – closed or semi-closed systems.

Table 2: Translocation risk assessment – open systems.