Richtlijnen voor Bonamia-vrije broedhuizen voor platte oesters in Nederland

Samenvatting

The flat oyster (Ostrea edulis) was a common species in the North Sea, Zuiderzee and estuaries in the southwest of the Netherlands until the end of the 19th century. Then fisheries became too intense and quickly decimated the population in the North Sea to only a few specimen at the end of the 20th century. Flat oyster beds are a threatened habitat for which protection is recommended. Oyster beds are a key element in the North Sea by providing hard substrate in a soft sediment environment. Oyster reefs are important for biodiversity, benthic-pelagic coupling, regulation of water quality and enhancement of fish production. As flat oysters are no longer present in large quantities restoration projects in the North Sea depend on oyster supply from elsewhere. Production of oysters in a hatchery with recognition of the disease free status according to EU regulations prevents introduction of non-indigenous species and pathogens. There are two important pathogens for O. edulis: the parasites Marteilia refringens and Bonamia ostrea. Bonamia ostreae occurs in the Netherlands, M. refringens does not occur in the Netherlands. The report presented here contains guidelines for a monitoring protocol that can help Dutch hatcheries in obtaining a formal Bonamia-free status as a compartment and guidelines for biosecurity measures for those Dutch hatcheries. This is not an official protocol to acquire the Bonamia-free status. Next to following the protocol a recognition as aquaculture facility and supplying documents to the NVWA is needed. This includes a documented biosecurity plan that takes into account the specific characteristics of that aquaculture facility and identifies risk reducing measures for each biosecurity risk.