Edited by Jennifer Sills
CyHV-3 monitoring in Japanese rivers
since 2004, when there was mass carp
death in Lake Biwa, has shown a continued
high prevalence of infection without obvious ill-effects (10).
Before a costly and irreversible large-scale
CyHV-3 release, further assessments should
provide convincing evidence that the virus
is not already present in Australia and that,
through contained, small-scale field trials, it
can achieve sustainable reductions in free-living Australian carp populations without
harming native ecosystems. We also support
development of alternative approaches, such
as release of daughterless fish, for long-term
control of invasive carp populations (11).
Jonathan Marshall,1,2 Andrew J. Davison,3
R. Keller Kopf,4 Maxime Boutier,5 Philip
Stevenson,6 Alain Vanderplasschen5*
1Queensland Department of Environment and
Science, Water Planning Ecology, Brisbane, QLD
4001, Australia. 2Australian Rivers Institute, Griffith
University, Nathan, QLD 4111, Australia. 3
MRC-University of Glasgow Centre for Virus Research,
Glasgow, G61 1QH, UK. 4Institute for Land, Water,
and Society, Charles Sturt University, Albury, NSW
2640, Australia. 5Department of Parasitic and
Infectious Diseases, University of Liège, Liège,
B-4000, Belgium. 6School of Chemistry and
Molecular Biosciences, University of Queensland,
St. Lucia, QLD 4072, Australia.
1. R. K. Kopf et al., Nat. Ecol. Evol. 1, 172 (2017).
2. Australian Government, Department of Agriculture
and Water Resources, National Carp Control Plan
3. M.Boutier etal., Adv.Virus Res. 93,161(2015).
4. K. A. McColl et al., J. Fish. Dis.40, 1141 (2017).
5. World Organisation for Animal Health, “OIE-Listed
diseases, infections and infestations in force in
2018” ( www.oie.int/en/animal-health-in-the-world/
6. J.Lighten, C.van Oosterhout, Nat. Ecol. Evol. 1,87(2017).
7. K. L. Rakus et al. , Fish Shellfish Immunol.26, 737 (2009).
8. A. Ronen et al., Vaccine21, 4677 (2003).
9. K. Rakus et al., Cell Host Microbe 21, 244 (2017).
10. K.Uchii et al., FEMS Microbiol. Ecol.87,536(2014).
11. R. Thresheretal. , Nat.Biotech.32, 424 (2014).
Waterbirds targeted in
Millions of migratory birds arrive each
autumn at Fereydunkenar International
Wetland (FIW) in Iran due to its rich ecosystem (1). FIW comprises 5427 ha located
in the southern Caspian Sea and includes
Fereydunkenar, Sorkhrud, and Azbaran
lagoons, which are designated as Wetlands
of International Importance in the Ramsar
Convention on Wetlands (2). However, an
estimated 3000 of these birds are currently
being killed daily by local hunters in FIW
(3) to sell at the local market, facilitated by
the recent adoption of more efficient type
of net (1).
This could have catastrophic effects on
the species that depend on this ecosystem.
For example, the last remaining individual
of the western population of the Critically
Endangered Siberian crane (Leucogeranus
leucogeranus) (4) winters in the FIW each
year, where it is not protected (5). Of the
three Siberian cranes that entered FIW in
2007, two were killed (6).
Despite the global importance of the
FIW to Critically Endangered species, Iran’s
Department of the Environment has thus
been unable to curb the illegal activities
that threaten this ecosystem. Armed locals
show a great deal of resistance to wildlife
rangers in the FIW when they attempt to
enforce existing laws to curtail hunting
(7). To bring poaching under control, the
Iranian government should increase police
presence and enforcement in the area
and introduce new national legislation to
control trade in endangered species at local
markets. In addition, the international community (particularly the UN Convention on
Biological Diversity) should pressure Iran to
enforce such laws by imposing fines on the
government if migratory birds are killed.
Finally, experience has shown the
The Australian government is
grappling with ways to control carp.
Biocontrol of invasive
carp: Risks abound
Introduced common carp (Cyprinus
carpio) infest many Australian waterways
and dominate their ecosystems (1). To
reduce carp numbers and aid native species recovery, the Australian Government
has proposed the release of cyprinid
herpesvirus 3 (CyHV-3; koi herpesvirus)
(2). This virus, presumed to be absent from
Australia, can devastate farmed carp (3, 4).
Because of its economic impact, the World
Organization for Animal Health requires
notification when the virus is identified
(5). Safety concerns have been raised over
the release of CyHV-3, including potential
infection of threatened native fish and
environmental damage due to decomposing carp (4, 6). However, our knowledge
of CyHV-3 pathogenesis, carp biology, and
Australian river ecology suggests that a
more likely problem is low efficacy.
Resistance-conferring genetic polymorphisms have been described in carp (7).
CyHV-3 virulence also shows strong environmental dependence: Disease develops
at 16° to 28°C, whereas temperatures above
30°C block infection and lead to immunity
(8). Infected carp seek out warm water
refuges, which are abundant in Australian
rivers (9). The high fecundity of carp may
then allow rapid repopulation of any
depleted waterways by immune or genetically resistant individuals. Moreover, there
is little published evidence that Australian
carp are currently free of the virus:
Genetic analysis indicates that CyHV-3
was infecting carp elsewhere before their
introduction into Australia, and the lack
of recorded CyHV-3–associated mass carp
deaths in Australia may simply reflect a
lack of environmental cofactors. Of note,