DEADLY koi herpes virus (KHV) could indeed be spread by nets, a new scientific study has found. Angler's Mail - No.1 for news - found out all about it.
And the research carried out by the Centre for Environment, Fisheries and Aquaculture Science has found carp becoming resistant to KHV which has been muted by affected fisheries.
Angler’s Mail magazine readers have kept fully up to date with the KHV developments this year. At least 23 waters have been infected this summer including recent cases at popular carp water Thorpe Lea in Surrey and also at Portland Lakes in Hampshire.
The study by CEFAS found 100 per cent of carp that came into contact with the disease were infected with 75 per cent developed clinical disease and the remaining 25 per cent survived by creating antibodies.
The virus shedding into mucus started the day after exposure and continued during the 22-day trial. And although KHV infection did reduce feeding, the test carp still ate over 40 per cent of the daily food ration so could be caught and spread the disease.
Wet infected nets and KHV
Net spreading potential was then tested with infected mucus and the virus remained alive in ‘dark and damp’ conditions, with 100 per cent of the cell cultures were positive.
Drying reduced KHV infectivity to about 20 per cent but KHV did not survive exposure to sunlight in two sets of tests.
There were no positive cells for KHV in both ‘light and damp’, and ‘light and dry’ conditions, something anglers thought was true but has now been proven.
A CEFAS spokesperson said: “Hopefully these experiments show that fish shedding KHV virus feed and are therefore likely to be caught by anglers.
“These can contaminate nets, the virus can survive on these nets, and that KHV can be transmitted to uninfected fish by contact with infected nets.
“Put simply, the use of infected nets is a disease risk to fisheries but moving fish still remains the biggest risk for KHV transmission.”
Small KHV outbreak at Thorpe Lea
Thorpe Lea’s Chloe Beale said: “We have had a small outbreak of KHV causing us to lose a small amount of fish up to 10 lb and this is due to the larger ones having built up immunity to the virus.
“We are now implementing Steri-7 which all landing nets, mats and slings must be immersed in on arrival and departure which kills all bacteria in seconds ensuring no further spread.
“We reopened on October 3 and the fishing has already been outstanding,” she added.
What do you think KHV and about nets? Email your views to amletters@timeinc.com – your comments may appear in the printed Angler’s Mail magazine!