Fishkeepers blamed for KHV outbreak

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Irresponsible fishkeepers who dump unwanted pond fish are being blamed for an outbreak of the deadly fish disease Koi Herpes Virus at a lake in Reading.

Burghfield Match Lake, which is owned by CEMEX Angling, was issued with a foot-and-mouth style Designated Area Order prohibiting the movement of fish in and out of a number of fishing lakes following confirmation of the presence of KHV.

The virus, which is now formally known as Cyprinid herpesvirus 3 (CyHV-3), is believed to be spread through the introduction of infected fish and also potentially through the use of fishing tackle contaminated by fish carrying the disease.

Dumped pet fishBut CEMEX told the Reading Evening Post that it believes pet fish owners are to blame for this outbreak.

"CEFAS has confirmed that as no stocking has taken place at the site for the past three years, the likely source of the infection is an illegal introduction of pet fish from a member of the public.

"It is important to make people aware of the risks associated with transferring pet fish into the wild.

"Anglers need to realise just how easily disease can be transferred and wipe out important fisheries and it is important they now take the necessary precautions to help minimise the risk of further contamination by air drying their nets thoroughly after each fishing session and before entering new water."

Designated Area OrderThe report says that a fence has been erected around Burghfield Match Lake, which costs 10 a day to fish, and the water is expected to be closed for the foreseeable future.

"It looks like 45% of the carp could have gone," Mick Barnes of CEMEX told the Reading Evening Post. "It will be closed for as long as we need to make sure the disease does not get out and to make sure there's no possibility of re-infection."

The Designated Area Order covers Burghfield Match Lake, Burghfield Big Lake, Burghfield Blue Pool, Watersports Lagoon, Barnett's Lagre Pit, Barnett's Small Pit, Farnham Flint, Englefield Lagoon, Pinge Wood Lagoon, Cottage Lane Lakes, Copthorne Hotel Lakes and other waters, excluding the Kennet and Avon Canal, that are within a grid-referenced bounding box.

ImpactKHV affects the Carp, Cyprinus carpio, including Koi and other varieties, and can result in very high levels of mortality.

Fish carrying the virus can appear perfectly healthy and the presence of the virus can be hard to detect. The disease only becomes symptomatic (that is, the symptoms can only be seen) when the water temperatures rise to 15-28 degrees C.

At these warm temperatures, infected fish suffer from bleeding, necrotic gills, white patches on the skin and fins, sunken eyes and hyperactive behaviour. It is normal for a significant proportion of the fish to be wiped out in a short period of time.

Since the disease is so hard to spot in fish carrying the virus when the temperature is below 15 degrees C, it is thought that many outbreaks are caused when waters are stocked with fish unknown to be carrying the virus.

It is not known how long fish can remain carriers of the virus, but it remains possible that this could be measured in years.

Recent research by scienists from Israel has demonstrated the ability of other species, including goldfish, to also carry to the virus and pass it on to carp.