Case study of vertical transmission of ostreid herpesvirus‐1 in Pacific oysters and biosecurity management based on epidemiological data from French, New Zealand and Australian hatchery‐propagated seed

In recent decades, mortality caused by ostreid herpesvirus (OsHV-1) and a variant (OsHV-1 μvar) has severely impacted the production of Pacific oyster, Crassostrea gigas, chronologically in France, New Zealand (NZ) and Australia (Jenkins et al., 2013; Keeling et al., 2014; Segarra et al., 2010). This study was conceived based on observations made in several commercial hatcheries and research institutes in these countries where vertical transmission of OsHV-1 μvar has been absent or extremely rare. We have collated data from the production of Pacific oysters across these countries to assess the risk associated with breeding oysters from broodstock grown in OsHV-1 μvar-infected waters. The aim is to provide a reference point for regulatory authorities to use when developing or updating biosecurity management policy associated with the hatchery production of Pacific oysters.