Scientists battle to beat fish killers


With the country in the grips of one of the worst fish diseases in history, experts are desperately seeking the means to protect carp waters from a deadly plague.

No fewer than 49 managed fisheries have been left reeling by Koi Herpes Virus outbreaks since the first reported case in 2003.

And the two struck down last month are unlikely to be the last, with scientists working hard to discover how the invisible killer is able to move between waters.

This week, virologists at the Centre for Environment, Fisheries and Aquaculture Science (Cefas) began experiments to establish whether the disease can be transferred on anglers’ keepnets. AT’s Greg Whitehead was given an exclusive look behind the scenes at Cefas’ state-of-the-art Weymouth laboratory to learn more about how the men and women charged with stopping the outbreaks are getting on.

AT on the inside


There are 11 fish health inspectors, who keep their identities secret in order to continue their undercover fight against carp smuggling.

One of them, who I shall call ‘Inspector X’, was busy with the unpleasant task of using a hacksaw to remove brain tissue samples from the skulls of Burghfield Match Lake’s KHV-infected fish after venue owner CEMEX Angling decided to cull all the carp when the fishery was infected.

Tissue samples are collected to help with ongoing experiments crucial to building a better understanding of the disease.

It’s also the inspectors’ job to investigate disease outbreaks, monitor fish farms and fisheries, and offer invaluable advice to those faced with difficulties.

“KHV has certainly been keeping us busy for the past few years but most of our work is done monitoring fish farms,” said Inspector X.

“The virus is just one of a number of nasty notifiable diseases – essentially untreatable pathogens with the potential to cause significant economic and environmental impacts.”

Other diseases include Spring Viraemia of Carp (SVC), Viral Haemorrhagic Septicaemia (VHS) and gyrodactylosis.

“In 2006 I was called out to investigate a case of VHS on a trout farm in Nidderdale, North Yorkshire,” he said.

“It was the first-ever outbreak of the disease in the UK. The sheer pathogenicity of it was astounding – I’ve never seen fish die so quickly.

Myself and a colleague arrived at 9am and by 11am the next morning we’d culled and sent 20 tonnes of trout for incineration.”

Inspector X then spent the following few months on site, directing the expensive clean-up operation.

These notifiable diseases are typically worse than human illnesses – the most similar being haemorrhagic fevers like Ebola, virulent viruses that spread fast and kill faster.

Notifiables can wipe out a fishery in a matter of days and it’s up to the Fish Health Inspectorate and supporting Cefas scientists to ensure that outbreaks are minimised and dealt with efficiently and professionally when they do occur.

Another key member of the team is senior virologist Keith Way, one of the world’s foremost KHV experts. In Cefas’ bio-secure, underground tank rooms, Keith conducts the latest experiments to discover whether the virus can be transferred on anglers’ nets.

“I infect a tank of naïve carp with KHV and, once they’ve developed the clinical symptoms of sunken eyes, gill necrosis and excessive mucous production, I’ll use water samples and mucus-covered keepnet material from the infected fish to see if they infect another tank of carp,” explained Keith.

A positive result may mean anglers regularly disinfecting their equipment and fisheries having to boost bio-security measures.

The rest of the Cefas facility comprises hi-tech laboratories packed with state-of-the-art equipment for detecting diseases down to the molecular level, including a £250,000 electron microscope and DNA testing gear.

“When we take samples of dead and dying fish out in the field we bring them back here to be rigorously tested,” explained X. “We need anglers and fishery owners to understand the job we do and the kind of professional advice and services we can offer.

Yes, policing fisheries and, where necessary, imposing fish movement controls is a part of what we do, but many of our inspectors come from a fisheries or aquaculture background.

“We create a management programme that is individually tailored to each infected fishery to work through the problems and not only prevent disease spreading further, but also helping the business to get back on its feet as soon as possible,” added X.