The Australian government is considering using a type of herpes virus as a biological agent to reduce the population of carp in the country鈥檚 waterways.
Since its introduction to Australia in the late 1960s, the common carp听(Cyprinus carpio) has become an ecologically destructive species.
鈥淭heir main impact has been a decline in biodiversity. Native fish and native water plants have declined,鈥� says Ivor Stuart at the Arthur Rylah Institute for Environmental Research, the biodiversity research organisation for the state government of Victoria in Australia.
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He and his colleagues have now estimated the size of the problem. They calculated that, in a year with average rainfall, the population of carp in Australia is roughly 199.2 million 鈥� equivalent to 215,450 tonnes of fish.
鈥淐arp tend to impact the amenity and biodiversity of an aquatic system when they reach 80 to 100 kilograms per hectare,鈥� says Stuart. The researchers found that carp exceed this threshold for biodiversity impact in 54 per cent of wetlands, 70 per cent of rivers and 97 per cent of large lowland rivers.
The estimate was calculated from a database the team created, which was based on 574,145 carp caught at 4831 sites between 1994 and 2018. The researchers also incorporated data from 153 research studies.
Current local control measures include , which can automatically sort carp from other fish species using the fact that carp 鈥� unlike many species 鈥� will jump out of the water when stressed. The devices encourage carp to jump into a cage that non-jumping fish are unable to reach. But while these devices reduce numbers, they aren鈥檛 enough to mitigate the damage that carp do, says Stuart.
The Fisheries Research and Development Corporation (FRDC), on behalf of the Australian government, is currently assessing how feasible it would be to use cyprinid herpesvirus 3 as a broader biocontrol strategy.
Cyprinid herpesvirus-3 is a highly contagious virus that causes death in common and koi carp.
鈥淎ustralia would be a world first in this regard,鈥� says Jennifer Marshall at the FRDC in Melbourne.
鈥淐arp are a much bigger concern here than in most other countries,鈥� she says. 鈥淚n parts of Asia and Europe, carp is native, and used as a food source.鈥�
Biological Conservation
