European Carp (Cyprinus carpio) is an introduced fish species first established in Australia’s rivers in the 1960s. In large parts of the Murray-Darling Basin and in many rivers and streams across Australia, carp is now the dominant species. Carp have been identified as a priority pest species, both in Australia and internationally. This invasive species has changed the riverine ecosystem in Australia dramatically in the last 50 years. A reduction of this invasive species needs modern technology accompanied by long-term techniques to substantially reduce carp biomass and keep future levels low. This can be achieved by the release of a species specific virus that occurs naturally overseas and has the potential to reduce carp numbers by more than 70% after release. Follow on techniques (e.g., genetic manipulation generating daughterless carp) would help to achieve a long-lasting reduction of carp in Australian river systems thereby aiding recovery of aquatic habitats damaged by carp.
CSIRO Land and Water, together with CSIRO Health and Biosecurity and RMIT University, combine the necessary knowledge and technology to develop a combined hydrological – demographic – epidemiological modelling tool to guide a national release strategy of the carp herpesvirus. It is a unique system both nationally and world wide.
Carp are bottom feeders stirring up sediment and increasing water turbidity, thus reducing sunlight necessary for growth of aquatic vegetation. The sediment also smothers vegetation and native fish eggs, which can impact on food availability and reproduction of invertebrates and small-bodied fish. It also increases nutrient levels in the water increase the risk of harmful algal blooms. Carp is shaping its own habitat and are meanwhile the dominant fish species in large parts of Australian inland waters.
To reduce this pest species the National Carp Control Plan is being prepared and explores a possible release of the cyprinid herpesvirus-3 which is highly specific to a single species – common carp. Multi-disciplinary research projects including social scientists, economists, biologists, water-quality experts, veterinarians and risk assessment specialists are investigating the challenges, risks, costs, opportunities and potential benefits of carp biocontrol.
To inform a virus release strategy, more accurate predictions of virus transmission between carp to effectively kill them using demographic-epidemiological modelling, needs to be developed based on the best knowledge of their physical environment such as spawning habitat, flow, and water temperature. For this part of the National Carp Control Plan, we apply a combination of techniques describing the connectivity of wetlands using satellite remote sensing, hydrological modelling of flow and prediction of water temperature in river systems. The model system is currently developed for the Lachlan catchment in New South Wales.
The projects integrate the technologies of different fields, such as remote sensing for inundation mapping, hydrology for flow simulation, physical limnology for water temperature estimation, and combine these with the most advanced simulation tools for demographics of carp populations in large river systems and the epidemiology of carp herpesvirus.
The establishment of this tool will guide the release strategy of carp herpesvirus for an efficient reduction of invasive European carp biomass in Australian aquatic systems. The simulation tool will allow a detailed analysis of virus efficiency depending on meteorological (water temperature) and hydrological (flow rates) drivers on a basin wide scale. It also yields information on the timing and location of dead carp biomass, allowing risk estimation of negative ecological effects which will aid the planning of removal of dead carp.