Oyster drill threatens Dutch oyster sector

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Oyster drill threatens Dutch oyster sector

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27 oktober 2015

The Dutch production of the Japanese oyster is threatened by the oyster drill and a type of herpes virus. Together with the Dutch oyster sector and the ministry of Economic Affairs, Wageningen University & Research helps to find answers to the challenges the sector is facing.

Every year, the Dutch oyster sector produces up to 20 million Japanese oysters (C. Gigas), amounting to a value of around 5 million euro. In Zeeland province, the Japanese oyster is generally known as ‘Zeeuwse Creuse’.

Zeeuwse Creuse

The first challenge the sector faces is the oyster drill (Urosalpinx cinerea; Ocinebrellus inornatus). This is a small sea snail that, as its name indicates, drills a hole in the oyster and eats the flesh. They mostly do this to young Japanese oysters, more commonly known as ‘Zeeuwse Creuse’. The exact mortality rate in the Oosterschelde and Wadden Sea caused by the oyster drill still needs to be investigated. Such data are highly wanted for estimating the oyster drills’ potential damage to the sector.

No danger to public health

Another problem is the herpes virus (OsHV1-μvar). Already in 2008, this virus was found in France, the EU’s largest oyster producer. In the Netherlands, the virus was first found in the Oosterschelde and has subsequently emerged in the Wadden Sea. The mortality caused by herpes is not exactly known. This type of herpes virus is not harmful to human beings, but can cause serious mortality in young oysters. Estimations vary from 15 to 90%.

Young oysters prey of oyster drills

The combined impact of the oyster drill and the herpes virus may cause a substantial decrease in the population of Japanese oysters in the Oosterschelde. This could severely impact the oyster sector and ultimately the consumer as well. Therefore, the Dutch government and the oyster sector asked Wageningen University & Research to map oyster mortality rate and potential economic damage. In collaboration with the stakeholders, a strategy will be drafted to reduce risk of mortality as much as possible. There is ongoing cooperation in the Knowledge Circle Oyster Production, in which oyster farmers and scientists exchange knowledge and experiences and join forces to combat the challenges that the sector faces.