Seafood CRC: safe spat rearing experiment
Oysters Australia Ltd
The production cycle of Pacific Oysters in Australia currently depends on hatchery production of spat, mainly in Tasmania. Experience in France and other European countries is that OsHV-1 affects mainly hatchery spat and juvenile oysters, with near total losses of affected batches being common. However, the observations in Australia and New Zealand are that oysters from spat through to adult stages are susceptible. The results from trials conducted in FRDC projects 2011/053 and 2012/032 have already revealed that mortality in adult stock can be kept below 50% by placing stock in cultivation structures 300 mm above standard growing height. The trials described in this report are the first to examine strategies to enable survival of spat and juvenile oysters.
The objective of this study was to obtain information about simple and practical methods to treat/disinfect water so as to develop a method for hatcheries to safely produce and rear spat in infected estuaries during the risk period for disease expression, and for hatcheries or farmers to hold spat in land based facilities during the seasonal window of infection.
1. Confirmation of the efficacy of water treatments for maintaining viable spat during a POMS transmission season in an infected environment
2. Information to benefit commercial hatcheries to enable production of spat from eggs through highly susceptible larval stages, in the face of POMS
3. Information to benefit growers who receive spat from hatcheries during a POMS transmission season
4. Information which can be integrated with husbandry (growing height modifications) to reduce mortalities in adult oysters and enable production of C. gigas in the face of POMS
5. Information which can be used to plan trials on how spat might be grown to a specific size (as distinct from just maintained) during a POMS transmission season in an infected environment