WITH the National Carp Control Plan’s (NCCP) research program now over half way through, some interesting, and at times unexpected, findings are beginning to emerge. Over the past 18 months, Australia’s leading universities, research institutions and expert organisations have been working to deliver independent and rigorous science to inform development of a plan for the control of carp in Australia, including the possible release of the carp virus (CyHV-3).
NCCP National Coordinator Matt Barwick says that the issue of carp control in Australia has prompted widespread discussion and debate, with many valid points raised by stakeholders and the wider community, and that sharing some of the early lessons from the research will contribute to this important discussion.
“While all research will go through an extensive independent peer review process before being included in the final plan and made public, the NCCP is able to start sharing some of the insights emerging from the program which will help to address gaps in knowledge and future decision making,” says Mr Barwick.
Here are a few examples of what the science is telling us?
- Larger than expected carp biomass variations
[Project: A carp biomass estimate for eastern Australia]
With on-ground fieldwork to estimate carp biomass in different habitats using electrofishing, mark-recapture, fyke netting, and surveying of environmental DNA now complete, summary statistics indicate that carp density varied considerably between sample locations – with carp biomass in some sites sampled revealing carp biomass below, and some well above, the threshold at which ecological impacts occur as a result of carp.
What this means: Identifying where carp density influences ecology is important for informing where priority areas lie. This work will also critically inform water quality modelling and clean up strategies in different habitat types, if the carp virus is approved for release.
- Decomposition no impact on fertiliser quality
[Project: Assessment of options for utilisation of virus-infected carp]
A recent commercial scale trial into alternate uses for carp biomass found that highly decomposed carp were still usable for producing high quality fertiliser. Further, opportunities exist for processing carp waste on-site, limiting need for transport or storage, thereby helping to keep costs low.
What this means: Carp biomass can be processed into fertiliser regardless of the state of decomposition. Other appropriate utilisation methods continue to be explored including composting and insect feed.
- Investigations continue into virus spread
[Project: Development of hydrological, ecological, and epidemiological modelling to inform a CyHV-3 release strategy for the biological control of carp in the Murray Darling Basin]
With mortality rates from the carp virus understood to be strongly influenced by multiple factors including water temperature, virus concentration and carp schooling behaviour, computer modelling points to few highly specific scenarios in which biocontrol may result in high levels of carp knock-down. These investigations have highlighted a need to further understand exactly how the carp virus is likely to spread from one fish to another. What this means: Additional lab trials are required to investigate factors that may influence effectiveness of the virus as a biocontrol method in more detail.
- Research into dead carp impacts on water quality ongoing
[Project: Investigation of nutrient interception pathways to enable circumvention of cyanobacterialblooms following carp mortality events]
While research by Australian National University scientists has confirmed that the carp virus cannot infect humans [Project: Cyprinid herpesvirus 3 and its relevance to humans], several separate and additional investigations are underway to understand how dead carp might impact on different aspects of water quality. A systematic and quantitative risk assessment project is also exploring different areas of ecological and social risk.
What this means: While factors such as water movement and areas of high carp biomass can be used to identify potential clean-up hot spots, the NCCP acknowledges community concerns about water quality and is committed to providing greater understanding around water quality, and risk of bacteria and microorganisms causing secondary issues.
“The NCCP welcomes robust discussion as it ensures a thorough investigation of concerns can be undertaken. Insights into our learnings will not only inform this debate, but help direct our ongoing research efforts,” Mr Barwick says, “In terms of progress, it’s exciting to receive incoming data to help us learn more about the prospects for potentially controlling carp in Australia safely and effectively.”
“One of the common concerns raised by stakeholders is that more time is needed to review the research findings and ensure the right recommendations are made in relation to carp control. This is an important consideration for our nation, and one that must deliver long term improvements to our waterways. If an extension is needed, as we’re discovering, then we will seek to secure more time.”
“It is important to remember no decision has been made in relation to carp control, or the possible release of the carp virus. The NCCP is designed to enable risks to be identified and explore ways to manage them. This information will then inform the decision-making process. The Fisheries Research and Development Corporation (FRDC) is not involved in the actual decision-making itself – this will be made by governments. Our role is to deliver a comprehensive program of research and stakeholder engagement to inform the development of a plan to control carp in Australia.”
