FOLLOWING a report from a shellfish farmer of unusual mortalities in farmed Pacific oyster (Magallana [syn. Crassostrea] gigas) at a farm site in the River Exe in Devon, a Fish Health Inspector from the Centre for Environment, Fisheries and Aquaculture Science (Cefas) visited the affected site in the Exe.
Samples taken from the affected site were confirmed as positive for oyster herpesvirus-1 microvariant (OsHV-1 µvar), and a new containment area covering the tidal waters and coastal zone around the River Exe has been declared.
This has also incorporated The River Teign containment area previous controlled by CD22/2015.
In accordance with The Aquatic Animal Health Regulations (England and Wales) 2009, movements of shellfish out of the containment area covering the River Exe and River Teign (including surrounding coastline), have been restricted, following the confirmation of oyster herpesvirus-1 microvariant (OsHV-1 µvar).
Cefas acting on behalf of Defra has issued a Confirmed Designation prohibiting the movement of Pacific oysters from the containment area and applied the following additional control measures.
The measures are:
• You must apply to the Fish Health Inspectorate for permission if you wish to move any Pacific oysters out of the Confirmed Designation area, including movements into purification centres (depuration plants).
• You must notify the Fish Health Inspectorate of any increased or unexpected mortality observed in shellfish stocks.
In addition, England continues to have OsHV-1µVar control areas in Essex, Kent and Suffolk; Butley Creek; and Poole Harbour.
There are no implications for human health.
Any suspicion of the presence of OsHV-1µVar in Pacific oysters should be immediately reported to:
The Inspectorate office is open, Monday to Thursday, 9am to 5pm, Friday: 9am to 4.30pm.
The Fish Health Inspectorate (FHI), based at Cefas’ Weymouth laboratory, is dedicated to maintaining and improving fish and shellfish health in England and Wales.
Its primary role is to act for Defra and Welsh Government (WG) in undertaking statutory duties resulting from national legislation in the area of fish and shellfish health.
The FHI is responsible for health certification of fish and shellfish movements from other countries, and runs an enforcement programme aimed at preventing the illegal importation of these animals.
Oyster herpesvirus-1 microvariant (OsHV-1 µvar). is a notifiable disease under The Aquatic Animal Health (England and Wales) Regulations 2009. Outbreaks of this disease have been subject to statutory control in GB since 2010.
CD15.2023, issued under the Aquatic Animal Health, England and Wales Regulations 2009 restricts the movement of live shellfish, into and out of the designated area without the prior written consent of the Fish Health Inspectorate at Cefas and applies additional specific biosecurity measures.