Controlling ‘river rabbits’: virus plan for carp

TARGET: The author, Anthony Rex Conallin, holds a female carp, which is capable of spawning up to one million eggs several times a year.
TARGET: The author, Anthony Rex Conallin, holds a female carp, which is capable of spawning up to one million eggs several times a year.

Just as rabbit numbers have been reduced with introduced viruses, CSIRO scientists are studying a virus that could help to control numbers of invasive carp, or “river rabbits”, in our waters.

The research is part of the National Carp Control Plan, a federal government initiative undertaking research, community consultation and comprehensive planning to determine the feasibility of releasing the cyprinid herpes virus 3 (CyHV-3) in Australia.

Common carp, sometimes referred to as European or Asian carp, are a formidable introduced pest, particularly in the Murray-Darling Basin where they can make up a staggering 8kg of every 10kg of fish. Carp, like rabbits, are prolific breeders – one female carp can produce up to a million eggs and can spawn multiple times a year.

In high numbers carp cause significant damage to aquatic environments, primarily by stirring up the mud as they feed. The most obvious effect is an increase in the muddiness of the water (turbidity), which fundamentally changes the environment to suit carp at the expense of native animals and plants. Degradation of environments by carp also affects humans in many ways, including increased costs to treat drinking water. Despite concerted efforts to control carp over the past 40 years, none have proven successful over large areas or time scales.

However, testing of the virus, is showing great promise with no indication that any native fish or other aquatic animals are susceptible. Not even introduced goldfish, which are closely related to carp, can catch it.

The virus is easily transferrable, has a high kill rate (70-100 per cent) and short incubation period (kills within six days), so the effects will be immediate and far reaching. Subsequently, an effective release and clean-up strategy is a major focus to ensure public safety and inconvenience is minimised.

The plan is being developed in collaboration with regional organisations such as Murray Local Land Services, which will play a key role at a local level.

The first round of community consultation has just been completed, with 80 meetings held around the basin. The draft plan is due out for public comment in June 2018, coinciding with more consultation. The final plan is due for review by government in December 2018 with a decision made in early 2019. For more details, visit www.carp.gov.au

-Murray Local Land Services