Translocation of aquatic organisms is recognised as a potentially threatening process to the environment particularly where species are translocated outside their natural range.
In preparing this translocation protocol, a comprehensive assessment of the environmental risks of translocating live aquatic organisms to freshwater open systems was undertaken by an expertise-based risk assessment panel.
The results of this risk assessment are summarised in the following section and fully described in Appendix A. In general, risks associated with the translocation of aquatic organisms relate to:
- the escape of translocated species;
- establishment of populations of introduced and nonendemic species;
- genetic shifts in wild populations;
- disease and parasite introduction; and chemical release.
As aquaculture in open systems presents opportunities to utilise a range of species, often outside of their natural range, it is important to identify and manage the risks associated with this activity. Aquaculture and fishing industries should take a pro-active role in managing this issue to ensure risks are appropriately managed and community confidence is maintained.
The number and diversity of species grown and the range of systems used in Victoria makes assessment of the specific risks associated with individual translocations complex. While risk profiles associated with each species vary, species may be grouped into similar risk categories for management purposes:
- translocations of endemic species;
- translocations of established species; and
- translocations of non-established species.
These categories are based on an assessment of environmental risks including disease, genetic impact and history of establishing populations in Victoria and elsewhere. There are several key translocation pathways through which stock are moved into and out of commercial flow-through, commercial static and non-commercial static aquaculture systems (Figure 3):
- environment to aquaculture system;
- aquaculture system to aquaculture system; and
- aquaculture system to non-commercial private waters.
This protocol only considers the environmental (i.e. ecological, genetic, disease and parasite) risks associated with translocations to commercial systems. An extensive range of pathways and species may be the subject of translocation applications. Persons seeking authorisation to stock must demonstrate their ability to undertake the proposed translocation in accordance with this protocol.
This process begins with the submission of an application in line with the process described in the Guidelines for Assessing Translocations of Live Aquatic Organisms in Victoria. In providing advice on a proposed translocation, the Translocation Evaluation Panel reserves the right to consider information that is not provided by the proponent.
The risk-assessment base-case:
In assessing the risks of a proposed translocation, it is necessary to characterise the aquaculture system into which aquatic animals will be stocked. The following characteristics broadly represent commercial flow-through systems and commercial static systems in Victoria and thus provide the base cases for risk-assessment.
In considering the associated risks with translocations to commercial freshwater open systems on private land, the base-case was based on naked risks i.e. worst case scenarios and no controls in place.
Risk assessment methods and results:
The methods and results of the risk assessment are detailed in Appendix A and summarised below. Commercial flow-through systems Eight specific risks were identified for commercial flow through systems.
Of these, the establishment of endemic or introduced species of fish or infectious disease or pathogen outside of their natural or established range, are considered high risk.
The risk of a species being introduced outside of its natural range but not becoming established is considered to be significant risk. The risks of an introduced species being released within its established range, release/ establishment of an infectious disease or pathogen within its known range and the release of an infectious disease or pathogen outside of its known range are considered moderate risks.
Commercial static systems:
Twelve specific risks were identified for commercial static systems. Of these, the risk of an introduced species or infectious disease or pathogen becoming established outside of its established range and selected or domesticated endemic species interbreeding with a local population are considered high risk.
Establishment of an endemic species outside its natural range is considered to be significant risk. Escape of an introduced species within its established range, the escape of endemic or introduced species outside of natural or established range without becoming established, and interbreeding of endemic species with the local population are considered moderate risks.
Risks common across systems:
Ten risks common to commercial flow-through systems and commercial static systems were identified. Establishment of infectious diseases and pathogens and non-target organisms through the discharge of transport water, use of live feeds, inappropriate disposal of mortalities or on equipment and personnel are considered to be high risk.
Release of chemicals, pollutants, or domesticated endemic, non-endemic or introduced species during the translocation are considered moderate risks.
Aquatic animal disease:
The introduction into Victoria of any of the notifiable diseases listed in Appendix B could cause severe biological and economic consequences to aquaculture and recreational fisheries.
Two notifiable diseases are known to occur in Victorian waters: epizootic haematopoietic necrosis virus and goldfish ulcerative disease. The fungal disease, epizootic ulcerative syndrome (EUS), which infects fish in freshwater and estuarine systems, has been detected on one occasion in Victoria and eradicated.
Outbreaks of EUS in New South Wales, east of the Great Dividing Range (Callinan et al. 1999), have caused significant economic damage.
Introduced and non-endemic species:
Populations of introduced and non-endemic fish can result from escape or release of these species. Twelve introduced species, including European carp and mosquitofish (i.e. Gambusia sp.), both declared as noxious species in Victoria, have become established in Victoria (Arthington 1991). Both species have expanded well beyond the initial points of stocking or escape.
Endemic species may also become established in areas where they are not naturally found. For example, Murray- Darling Basin species, including Murray cod, golden perch, silver perch, trout cod and Macquarie perch, have established populations outside of their natural range but have not extended significantly beyond the point of the original translocation (Cadwallader and Backhouse 1983).
Following escape or release, the establishment of an aquatic species depends upon its ability to survive, grow, reach reproductive maturity and successfully reproduce in the new environment. Factors that affect the likelihood of establishment include the presence of environmental requirements to complete the species’ life cycle and its food and habitat requirements. Prevention of escape is the most effective method for preventing the establishment of such populations.
Development of controls to manage or mitigate risks:
In accordance with the principles of risk assessment and management, controls were developed that are considered commensurate to the level of risk. To facilitate this, risks were first examined for each of a number of open aquaculture production systems:
- commercial flow-through
- commercial static
- non-commercial static.
Further pathways were then identified:
- Species e.g. Salmonids vs. endemic fish
- Supply source e.g. interstate vs. within State
- Fish distribution e.g. endemic fish within or outside of natural range,
- Presence of established populations in potential receiving waters.
The combination of these pathways provide a number of risk scenarios. Scenarios with a common risk profile were then aggregated and a range of specific controls developed across each scenario group.
Wherever possible, controls were developed to be outcome orientated rather than prescriptive in nature. Notwithstanding the above, some controls are detailed in order to be clearly measurable.
Biosecurity controls have been developed to reflect best practice operational standards and as such also serve to assist management of business or enterprise risk.
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