The National Carp Control Plan (NCCP) is presently considering strategies that will effect widespread control of a dominant invasive freshwater fish, the Carp (Cyprinus carpio). Carp have a significant negative impact on social, environmental and economic ($500 million per year) outcomes in aspects of water quality, amenity and biodiversity. Carp dominate the Murray–Darling Basin, making up 80-90 per cent of the fish biomass in places. In Australia, the use of a biological control agent, the naturally occurring carp herpesvirus, could significantly reduce the number of carp in our freshwater systems [1-3]. The NCCP will map out the best approach to manage the required work safely with a key step towards the potential strategic release of carp herpesvirus being community consultation.
One common theme amongst community comments about carp control is “Can we fish them all out through overfishing?” Proponents cite examples of over-exploited commercial fisheries worldwide that have collapsed. This reaction is particularly prevalent amongst the commercial fishing sector of the community . Similar arguments are made against investment in many ‘technologies’ for many vertebrate pest-control strategies; particularly where the pest-animals have a value in an exploitative industry or where effective alternatives are lacking. Other fish-examples include Asian carp species in the Mississippi Basin (Visser 2017), Lionfish in the Caribbean (Downey 2017) and Aripaima or Paiche invading Bolivia (Snyder 2017).
Existing studies of the feasibility of Carp control by removal are few in Australia [5, 6] particularly in peer reviewed literature . There is a clear need for peer-reviewed evaluation (including a plain-speech, magazine article version) of the potential for commercial, or subsidised, fishery exploitation to effectively control carp populations in Australia. The proposed research will inform the community consultation process about the potential for deliberate overfishing to complement or to be an effective alternative to virus release.
Critical factors are expected to include, but not be limited to:
• Achieving a high enough exploitation rate
• Commercial viability/budget available for subsidy
• Accessibility/vulnerability of the whole population (refuge dynamics)
• Spatial complexity/connectivity and temporal variability in abundance
The study uses the Australian developed Carp population dynamics software, CarpSim–to explore the limits of any identified critical factors and review the scale, circumstances for (and likelihood of) successful Carp control through commercial exploitation. The study further develops models adapted from existing published CarpSim models to describe exploited Australian carp populations.