O’Connor WA, Raftos DA, Dove MC, Kan A and Johnston K (2010) Securing and enhancing the Sydney rock oyster breeding program. Final Report to the Seafood CRC for project 2006/226.

Summary

The NSW, Sydney rock oyster industry has gone through major changes in the past five years that has seen it begin to use hatchery-produced seed (juvenile oysters). Hatchery seed production has also allowed the Sydney rock oyster industry to use oysters from a Sydney rock oyster breeding program. Sydney rock oyster farmers’ have established a company (Select Oyster Company) to manage extension of the NSW DPI Sydney rock oyster breeding program to industry. This project developed oyster culture techniques to protect QX resistant Sydney rock oysters and investigated genes for QX (Queensland Unknown) disease resistance. To do this, pair-mated Sydney rock oyster families created from a single male and female oyster were produced. A strong link between the parents used to produce oysters and mortality caused by QX disease was found. Deep freezing oyster eggs and sperm (cryopreservation) is a tool that can help hatchery operations by providing eggs or sperm on demand and removing the need to maintain adult breeding oysters. This project assessed the potential for cryopreservation of Sydney rock oyster eggs and sperm and developed a Standard Operating Procedure for sperm. Successful cryopreservation of Sydney rock oyster eggs was also achieved in this project but further work on egg freezing is required. Ways to produce triploid oysters was also investigated in this project. Triploid oysters have three sets of chromosomes instead of two. Normally oysters only have two sets of chromosomes. Triploid oysters have the advantages of being unable to reproduce in the wild, grow at a faster rate and have good meat condition at times when diploid oysters have poor meat condition. Triploid oysters are commonly produced in hatcheries by using chemicals shortly after eggs have been fertilised. We looked at using temperature changes and high pressure to produce triploid oysters instead of using chemicals. Using temperature changes and high pressure worked to induce triploidy, however survival of the oyster larvae following the temperature and high pressure shock was too low for large scale hatchery production of triploids.