Australian government scientists have proposed a plan to give herpes to carp in what some would argue is the least fun way: without any sex at all!
Why God why, you ask? Because common carp (Cyprinus carpio) have reaped serious damage on Australia waterways, with populations getting out of control, ripping up vegetation, increasing sediment, and hunting native plants and animals. While the idea of controlling carp with a virus has been mulled over since 2016, in January of this year, government scientists formally asked for approval to kill the problematic non-native carp by releasing Koi Herpesvirus (KHV) into the continent’s largest freshwater supply.
Some scientists, however, say this herpes idea may be a pile of carp.
“Viral biocontrol is highly questionable and, as our study shows, it is unlikely to reduce carp numbers in the long term,” said Dr. Jackie Lighten of the University of Exeter in an interview with ScienceDaily. “Based on our findings, we believe the plan to control Australia’s carp with KHV is dead in the water.”
In a study published in the Journal of Applied Ecology, Lighten and other researchers created realistic simulation models, similar to those used to analyze and help prevent the spread of COVID-19, showing that even if 95 percent of carp were wiped out by KHV, some would still be resistant to the virus and they’d be able to rapidly breed, with one fish producing over a million eggs in one breeding cycle. The model also showed that even if there were future outbreaks of the virus, it wouldn’t be effective in controlling carp populations long term. The risks seem to outweigh the rewards too, says Lighten, since releasing a pathogen into water creates major health risks among humans and other animals, especially considering Australia’s struggle with freshwater shortages and the drying up Murray-Darling basin, which continues to be under stress.
“If the current global COVID-19 pandemic has reminded us of anything, it’s that viruses are hard to predict and manage,” said Lighten. “It is madness that the release of a high pathogenic virus is being considered as one of the first steps to restore a damaged and fragile ecosystem.”
The Australian government has been trying to manage common carp populations for decades, with the economic hit from carp estimated at Aus$500 million a year. To mitigate this, in 2016 the government created the National Carp Control Program (NCCP) led by the Fisheries Research and Development Corporation (FRDC), and put up Aus$15 million to examine possible carp control solutions using a virus.
In 2019, the NCCP released a progress report claiming that integrated modelling was used to measure the virus’s impact on carp reduction, and that Australia’s national science research agency CSIRO found that the herpes virus could reduce populations by 40 to 60 per cent, with population suppression lasting up to a decade, maybe more.
And in 2016, the FRDC also tested the effects of the virus on 13 native fish species as well as turtles, mice, frogs and chickens, according to a news article published in Nature, determining that the virus was safe for them. They concluded that the only real danger was posed for common carp and ornamental koi, where the mortality rate is over 70 percent.
However, other scientists have taken issue with some of the NCCP’s findings, saying that some of the conclusions are questionable and viral DNA was detected in at least 10 test species, meaning maybe it’s more transmittable to other animals than they surmised.
Cock van Oosterhout, a co-author on the study with Lighten and a professor of evolutionary genetics at the University of East Anglia, also criticized the NCCP for not using a better modelling method to study the impact of the virus before proposing its release into the water supply.
“The modelling strategy that we took is a very powerful way to assess how disease can spread among individuals within a population,” van Oosterhout said. “It is widely accepted as the current gold standard in projecting disease outcomes but, worryingly, the NCCP chose to ignore this approach.”
This isn’t the first time scientists have urged the Australian government not to give carp herpes over the last five years, having published an article in the journal Science back in February of 2018 expressing similar facts and sentiments.
While the Australian government still hasn’t reached a decision about whether it will move forward with the herpes plan, according to the Australian government’s NCCP website, the NCCP is “one of several important inputs that will inform a decision by the Australian, state and territory governments on the carp virus,” and “a final decision on carp biocontrol will require further public consultation and regulatory approval.”
In other words, when it comes to carp herpes, only time will tell whether the Australian government will take the bait.