UK oysters: threat or Xmas opportunity?

But assessing the risk of norovirus, which can cause symptoms such as vomiting and diarrhoea, is complicated by scientists’ inability to distinguish between infectious and non infectious material.

Andrew Wadge, chief scientist at the Food Standards Agency, said: ‘This research is the first of its kind in the UK. It will be important to help improve the knowledge of the levels of norovirus found in shellfish at production sites. ​

“The results, along with data from other research, will help us work with producers to find ways to reduce the levels of norovirus in shellfish, and work within Europe to establish safe levels.”​

Mortality​

Meanwhile, rising mortality rates in French oyster beds, due to the oyster herpes virus, could create lucrative opportunities for UK producers.

The virus has devastated production in France just before Christmas, which accounts for about 70% of total oyster sales.

David Jarrad, assistant director of the British Shellfish Association and owner of River Exe Shellfish Farms, told FoodManufacture.co.uk: “French production is being absolutely devastated. UK producers are facing a choice between cashing in and taking the money or holding onto stock and selling in the​ [traditional UK] summer period to their regular buyers.” ​

The UK price of oysters has increased by about 30% at wholesale and 50% at retail over the past 18 months.

“Further, more severe, shortages over the summer and next Christmas are already expected. After that no one can say,”​ Jarrad explained.

The virus appeared in UK waters this year, turning up in north Kent oyster beds, but it seems to have been contained successfully. There have been no further reports of infections and there have not been any mortalities in the Kent beds, said Jarrad.

Lethal​

Although not fatal to humans, the herpes virus has proven to be lethal to oysters. French authorities are trying new methods of cultivation, such as growing the oysters more slowly and higher up the shoreline. They are also experimenting with virus-resistant strains from Japan and the United States.

With no solution in sight for French growers, the entire European industry is largely reliant on the three oyster hatcheries in the UK, said Jarrad.

The hatcheries have already been overstretched for some time by requests for young virus-free oysters. No matter how quickly the virus is defeated, the strain on the supply situation will increase, he predicted.

Oysters are traditionally grown for between three and five years. So, even if the current experiments are successful, it will be some time before the solution is scientifically confirmed, he said.