THE Environment Agency announced today that its own Calverton and Leyland fish farms are to be cleared and disinfected following confirmation that fish at both sites have been infected with the Tench Rhabdovirus. This is a rare virus that affects freshwater fish.


The decision follows results of extensive testing that confirms that both farms have been exposed to the virus this summer. By taking this action now the Environment Agency can prevent the virus from being released into the environment and infecting wild fish stocks. This will ensure that the sites are up and running again with a minimum delay and only one year¹s break in production.


Following fish mortalities in July, CEFAS (Centre for Environment, Fisheries and Aquaculture Science) carried out tests, which showed that fish from some tanks at Calverton had been infected with the virus. All the fish from the infected tanks were destroyed and the site was closed to all movements as a precaution.


From the initial results, the Environment Agency believed that the virus was confined to one set of isolated tanks, and the site remained closed while further samples were collected.  Because of the Environment Agency¹s concern about this virus, which can have serious implications for wild fishstocks, it asked CEFAS to employ recently developed technology to give the best possible diagnosis of the level of infection. Results from these tests were confirmed in early December, showing positive results in a number of ponds and a range of species across the site.


In June, before the disease was detected, a batch of roach was transferred from Calverton to Leyland. As a precaution, no movements were permitted from Leyland and fish samples were taken for testing. The results reveal that a proportion of the fish at Leyland have come into contact with the virus.


The Environment Agency has taken It is important to note that to the best of itsknowledge, the Agency has not stocked out any fish that have come into contactwith the virus. independent scientific advice from CEFAS and Stirling University Institute of Aquaculture throughout the incident.  Both have noted the Environment Agency¹s robust approach. These experts have also recommended enhanced disease safeguards which will be adopted when fish production recommences next year.


Dafydd Evans, the Environment Agency’s Head of Fisheries said:

“It is a great shame that these farms have to suspend their production but Tench Rhabdovirus is associated with fish mortalities in fish farms and fisheries, and fish from infected sites are not allowed to be stocked into the wild. We intend to destroy all stocks in a humane manner, dispose of the fish and disinfect both farms following advice from CEFAS, Industry and in line with our own procedures.”


“The comprehensive testing that has been carried out demonstrates how very seriously we have taken this outbreak. The additional tests were a precaution and would not normally be required on private fish farms. Our testing has used the latest technology and has gone beyond what we would ask fish suppliers in the private sector to do and we will continue to deal with this in the same professional manner.”