The French oyster production of Crassostrea gigas is based on two sources of spat: wild-caught (WC) and hatchery-produced (HP). Massive mortality related to the ostreid herpesvirus type 1 (OsHV-1) has affected both sources in France since 2008. We investigated the mortality in juvenile C. gigas due to the horizontal transmission of OsHV-1 within (separated condition) and between (mixed condition) the two spat sources in three environments from April to June 2010. In the separated condition, no mortality was observed in the HP batches, while the WC batches experienced moderate to high mortality (40–80 %). In contrast, the WC and HP batches experienced high mortality in all tested environments for the mixed condition. At the beginning of the trial, the HP... |