Up to 200 fisheries could have KHV-infected fish

More than 200 stillwater fisheries in the UK have been stocked by fish suppliers believed to be possible sources of the UK's current Koi Herpes Virus outbreak, Practical Fishkeeping has learned.

According to a letter from the Environment Agency sent to Angling Times, there have been 12 confirmed cases of KHV in stillwater fisheries in England so far this year: ten of the fisheries have been legally stocked this year with carp from 26 different suppliers, but the remaining two have not been legally stocked this year; suggesting that either KHV was already present in the fish, or that it was introduced on illegally stocked fish.

Adrian Taylor, Fisheries Policy and Process Manager for the Environment Agency wrote: "We have identified ten different suppliers that have provided fish to one or more of the affected fisheries, and these suppliers received from 26 different sources, some via holding sites. In excess of 200 other fisheries have been stocked by the ten suppliers or 26 source sites."

Taylor told Angling Times that there are several other secondary suppliers and sources that may have provided infected fish to primary suppliers, making it very difficult to trace how the virus has been spread around the UK.

Vaccinated carpA number of carp suppliers in the UK are now offering vaccinated fish for sale to stillwater fisheries, which are believed to have been produced in Israel using the same technique used to vaccinate Israeli Koi for the ornamental fish trade.

The Israeli carp suppliers intentionally infect "naiive" fish with the virus under controlled conditions. They claim that this produces fish which contain antibodies for the virus and resistance against the disease, without being carriers themselves.

However, while the fish certainly do not appear to develop KHV, critics of the technique believe that the fish could pose a risk to naiive fish here and strongly oppose the stocking of the fish in angling lakes. The vaccine is currently not legal in the UK, but it is legal to import vaccinated fish into the country.

Greg Whitehead of Angling Times told Practical Fishkeeping that KHV was now "out there" and it was going to be difficult to trace the source, something exacerbated by the vaccinated fish, which cannot be easily distinguished from carriers when tested under laboratory conditions.

Said Whitehead: "We've spoken to Cefas who said that they've not had a chance to determine whether these inocculated fish were safe, and whether they can develop the disease or transfer it. At the same time, they said that there was no legal means to prevent people importing them and selling them."

Although some carp fisheries in the UK are now offering KHV vaccinated fish, Adrian Taylor of the Environment Agency says that the majority of infected fisheries have not received such fish: "Given that most of the affected sites are not linked to KHV vaccinated fish and that many of those fisheries have received fish from more than one supplier, it is wrong to point to vaccinated fish as the cause of the outbreak."