Sydney Rock Oyster Breeding Program

The Sydney Rock Oyster breeding program started in the 1990s to increase industry productivity, provide management options to industry in times of oyster diseases, and establish a platform to respond to future needs and threats such as climate change. Over the past 30 years the program has changed in terms of breeding goals and methods used to achieve them. The program has become one of the most successful oyster breeding programs of its type.

The benefits

Disease Resistance

The breeding program has developed oysters with higher survival rates against diseases like QX disease. The program is considered a biosecurity necessity and an insurance policy.

Growth times

Selectively bred Sydney Rock Oysters grow faster than their wild counterparts. This means they reach market size more quickly, reducing the time and cost for farmers.

Marketability

Breeding decisions consider meat quality to ensure that oysters are appealing for consumers.

Sustainability

By improving disease resistance and growth rates, the breeding program helps ensure the long-term sustainability of the Sydney Rock Oyster industry in New South Wales.

Targets

The current industry goal is to produce commercial oysters with an average survival of greater than 70% for spat through one QX disease outbreak and 30% faster growth without changing meat condition, when compared to a wild Sydney Rock oyster.

Progress

When compared with wild Sydney Rock Oysters, as of April 2024 the program reports:

An average of 80% survival rate for spat exposed to a single QX outbreak
25% faster growth than wild Sydney Rock Oysters
No loss in meat condition

March 2026 update

NSW DPIRD completed the QX assessment trials on the Sydney Rock Oyster Breeding Program 2023 year-class families in July across three sites: the Georges River, Karuah River and Tilligerry Creek, as well as a fourth site, the Hawkesbury River, that was led by industry. The mean Estimated Breeding Values (EBVs) for the year class were 88% survival for spat and 82% survival for adults, following a single exposure to QX disease. The EBV for survival following dual exposure to QX disease over two seasons could not be calculated for this year class, as a strong dual exposure was not received across the field trials. NSW DPIRD will aim to determine the EBV for survival following dual exposure to QX disease for the 2024 year-class families. EBVs for commercially important traits of growth and condition were also calculated for the 2023 year-class families and were 23% and 2% higher than a wild oyster, respectively. Six families from the year-class have currently been released for hatchery crosses. Their EBVs can be found on the CSIRO Sydney Rock Oyster database.

NSW DPIRD 2025 Sydney Rock Oyster Breeding run produced 41. The focus of the run remained on enhancing QX resistance, while maintaining commercially important traits of fast growth and condition.

A Technical Review of the breeding program funded by Fisheries Research Development Corporation began in July 2025. Led by Nick King and Rob Banks, representatives from DPIRD, CSIRO, industry groups and hatcheries were consulted. The final report is available here: Project 2024-056 | oystersaustralia.

More information

Newsletters

Producing the Sydney Rock Oyster "thoroughbreds"

Enquiries

For enquiries regarding the breeding program, contact Dr Laura Parker laura.parker@dpi.nsw.gov.au at the Department of Primary Industries and Regional Development.

Information on spat availability can be found on the NSW Oysters website.