See the announcement here.
Key point, this is not a plan to release the carp herpes virus. It is a report to Federal and State Environment Ministers on the extensive research that has been conducted into the feasibility and risks. It identifies implementation issues including additional research required before deciding to release the virus. The ministers are currently considering the NCCP report and next steps.
The mortality rate won’t give us “Carpaggedon” but the risk of natural selection of fish immune seems lower than we’d been led to fear. Susceptibility to the virus of other species remains open for further research (I need to look more closely at trout. Earlier work seemed very limited).
The full plan is here. The document is huge some 4,000 pages, however the executive summary (9 pages including many pictures) is quite readible and commended to you.
For those who want just a taste, I’ve extracted a section called ‘Key Points’ below:
Introduced European Carp, or common carp, are a serious pest in Australia’s fresh waters, damaging aquatic plants, muddying water, and harming native animals through predation and competition for food.
Research by the National Carp Control Plan (NCCP) has identified that carp occur at high densities across extensive areas of south-east Australia. The national biomass of carp ranges from 200,000 tonnes and possibly up to approximately 1 million tonnes under ideal breeding conditions featuring consecutive high rainfall years.
The NCCP was established to investigate the carp virus’s potential to reduce carp populations at a continental scale. The NCCP completed an extensive research and investigations program involving 19 research projects and five investigations overseen by expert advisory groups and scientists. While many uncertainties remain, and preclude an unequivocal recommendation of feasibility at this point, NCCP research confirms that the carp virus has potential as a biocontrol agent. The body of evidence assembled by the NCCP research program is sufficient to enable Australian governments, should they choose, to proceed with additional targeted planning and research activities to inform an eventual decision on whether or not the virus should be used for biocontrol. Such a pathway could reduce, but would not eliminate, remaining uncertainties.
NCCP modelling indicates that, if successfully deployed, the virus could reduce and suppress carp populations by approximately 40–60% (and by up to 80% in less resilient carp populations). These modelled outcomes depend on some assumptions about how the carp virus will move through Australian carp populations, and on the potential development of resistance or immunity via several possible mechanisms. NCCP research indicates reduction of carp impacts may benefit from an integrated approach in which virus deployment is preceded by targeted harvesting, particularly in high-density carp populations. If the virus is eventually released as a biocontrol agent in Australia, an adaptive management approach is recommended which involves ongoing assessment of epidemiological performance to inform virus release operations. This approach would mitigate against departures from the predicted epidemiology.
Preliminary research indicates Australian carp may not possess the gene variants (alleles) that bestow heritable genetic resistance to the virus, meaning that the carp virus could potentially be effective for considerably more than 10 years. However, this work was exploratory, and did not constitute a comprehensive survey of Australian carp genetics. More broadly, the genetic basis for resistance to the carp virus remains imperfectly understood (though considerable international research in this area is ongoing). One uncertainty regarding genetic resistance is the role carp-Goldfish hybrids could play in its evolution. These hybrids are less susceptible than non-hybrid carp to the disease caused by the virus, and this relative invulnerability could bestow a selective advantage. Therefore, the rate at which genetic resistance to the virus would evolve among Australian carp remains largely uncertain, although the NCCP has developed the genetic tools to improve knowledge in this area. The potential emergence of herd immunity is also an uncertainty.
The carp virus will not infect humans or any other mammal, and there is considerable evidence the carp virus will not infect other non-target species (e.g. native fish). However, a very high level of confidence in the species-specificity of any biological control agent is required before its release. Additionally, concern regarding the virus’s specificity to carp is relatively common in the Australian community. Unless addressed, such concerns could negatively affect social licence for carp biocontrol. For these reasons, additional non-target species susceptibility testing of selected fish species is recommended if governments wish to proceed with activities to inform an eventual decision on whether or not to proceed with carp biocontrol.
Broadscale and long-term water-quality impacts resulting from carp biocontrol operations are unlikely. Local water-quality impacts are likely under particular conditions, and in some ecosystem types (mainly those with low or no flows). Some aquatic habitats in the Murray– Darling Basin (MDB) already have water-quality parameters (particularly dissolved oxygen levels) that are marginal for native fish species. Further degradation of these parameters by decomposing carp could cause fish kills in these areas unless effectively managed. Carcass management strategies and methods can theoretically mitigate water-quality risks as demonstrated in NCCP case studies, noting that capacity to manipulate river flows specifically to benefit carcass management may often be limited or non-existent and physical collection of carcasses presents challenges.
If Australian governments choose to proceed with the additional activities required to inform a final decision, and this process eventually lead to virus release, implementation of carp virus biocontrol would likely involve two to three years of coordinated deployment focused initially on the MDB, with ongoing adaptive management beyond initial deployment.
A future carp biocontrol program would require investment. An NCCP case study of possible virus deployment in the Murray and Murrumbidgee systems roughly estimated that virus deployment and subsequent post-release management would cost around $190 million (at 2019 costings). This area covers more than 30% of the carp biomass in Australia including the highest densities of carp. If governments choose to proceed with activities to inform decision making, more accurate and detailed costings will be required.
Although uncertainties and risks remain, these are likely to be reduced through a pathway of targeted further research, implementation planning, adoption of NCCP recommendations, and by development of detailed post-release monitoring plans and an implementation governance structure that enables adaptive management. At the national scale, further regulatory approvals will be required if governments proceed with the assessment pathway. Community consultation, public communications, and stakeholder engagement are also important given the possible impacts and high level of interest in carp biocontrol.
