Rare fish virus found in rivers
Scientists are working to discover what risk the virus poses
Traces of a disease which is potentially fatal to freshwater fish have been found in seven rivers.
Environment Agency experts said they had found antibodies to tench rhabdovirus, which in the past has killed significant numbers of fish.
A spokesman said the agency did not know how serious these findings were and further tests would be carried out.
Rivers in Yorkshire, Nottinghamshire, Lincolnshire, Worcestershire, Lancashire and Derbyshire are affected.
Nigel Hewlett, senior fish health scientist for the Environment Agency, said the virus had previously been thought to be rare in the wild.
Rivers with positive results
River Nidd, Yorkshire
River Wharfe, Yorkshire
River Witham, Lincolnshire
River Trent, Nottinghamshire
River Teme, Worcestershire
River Douglas, Lancashire
River Wye, Derbyshire
It has been found twice in England and Wales. In 1999 it killed fish in five waters, all supplied with bream from a source in Northern Ireland, and in 2004 it was found at an agency fish farm.
Since then, scientists have been testing river waters for the virus.
Mr Hewlett said: "These findings suggest the virus may be more widespread than we originally thought, but, as it does not appear to have caused fish mortalities, it may not prove to be a serious risk."
Dafydd Evans, head of fisheries, said: "All these rivers are extremely valuable and popular fisheries and we have no evidence the virus has had an impact.
"More work is needed on the disease, however, and we will be working closely with other agencies to get a better understanding of its distribution, what impact it can have and what risk this poses to fisheries."
He added the agency did not intend to impose immediate restrictions on fish movements