‘Overcatch’ or ‘fouling’, whereby juvenile oysters (wild spat) or other aquatic organisms attach themselves to semi-mature oysters, is the largest farming challenge for Sydney rock oyster (SRO; Saccostrea glomerata) growers in Australia and represents a major barrier to efficient and sustainable production (Wayne Hutchinson, FRDC, personal comm.; Durr & Watson, 2010). Without timely intervention, fouling often renders the oysters unmarketable, leading to substantial proportions of product being discarded or having growth rates considerably slowed (Watson et al. 2009; Adams et al. 2011). It is estimated that 30–50% of SRO grown in Qld and northern NSW are wasted as a result of fouling with a potential value of $13–30 million/annum (Tim Prowse, QOGA, personal comm.; FRDC, 2022); this is either because the products become unsellable or due to losses associated with current overcatch control treatments. The inability to effectively manage overcatch has contributed considerably to the decline of Qld’s oyster industry over the last century, and similarly remains a significant financial impost to NSW oyster growing operations (de Nys et al. 2002; Cox et al. 2012).

At present, oyster growers typically attempt to mitigate the impacts of overcatch using methods like air drying and heat immersion; but both are labour intensive, have no clear guidelines or benchmarked specifications to support new growers in their implementation, and can result in significant mortalities or even total crop losses if undertaken incorrectly (Fitridge et al. 2012; 2014; Mayrand et al. 2015). While two relatively new technologies exist that hold promise for successfully managing overcatch, namely the ‘cold shock’ hypersaline system and FlipFarm system (Cox et al. 2012; Jackson, 2021), these have not yet been widely trialled or adopted in Australian oyster growing regions. There is thus a pressing need to better understand the optimal parameters for effectively eliminating overcatch while retaining host oyster health in commercial production settings.

The proposed project will respond to this longstanding need by evaluating and comparing the efficacy, practicality and cost-effectiveness of these various existing and emerging overcatch control methodologies under the same commercial environment, location and stock. Trials of these four treatments (air drying, heat immersion, cold shock system, FlipFarm system) will be carried out at established oyster leases in Qld’s Moreton Bay region, which is particularly prone to the impacts of fouling and therefore offers the ideal location to determine the efficacies of different methods in controlling overcatch in on-farm settings. The location also has no pre-existing incidences of QX disease that is currently decimating many other SRO growing regions in NSW and Southern QLD. The findings from this work will provide essential outputs, including validated methods and Best Management Practices (BMPs), which will be widely disseminated to the national oyster industry through various relevant forums.

With the Qld government in particular seeking to rejuvenate its oyster industry (McDougall, 2020), and the entire Australian oyster industry looking to expand and boost production (Oysters Australia, 2020), the timing of this project is optimal. The results will not only assist new growers entering the industry, but they will also provide essential learning to established growers throughout Australia who experience significant oyster losses and labour costs associated with overcatch management. The project also aligns with the Oysters Australia Strategic Plan 2020–2025 to (i) increase the sustainable, efficient production of oysters and their management on farm; (ii) manage industry risks; and (iii) increase industry knowledge, skills and networks. It will further help to meet the objectives of the FRDC’s R&D Plan 2020–2025, particularly Outcome 1 (i.e., ‘growth for enduring prosperity’), by providing the oyster industry with genuine opportunities to reduce crop losses, increase profitability, expand production and enhance their reputation in a stewardship context. From a broader societal perspective, the project outcomes will be crucial in building a properly functioning circular economy in the oyster industry, by preventing the creation of waste in the first place.

Genomics is routinely used across many livestock and plant breeding industries. It is now practical, within certain considerations, to consider applying genomic selection to aquaculture breeding programs due to significant cost reductions in the last decade. Its use in aquaculture breeding programs is increasing and genomics has already been researched for oyster breeding by USC (Vu et al. 2021a; Vu et al. 2021b).

Genomic selection has the potential to reduce the cost of estimating breeding values, which presently is a costly and challenging exercise with SROs and also may potentially increase genetic progress and selection accuracy for the SRO BP. The research proposed in this application will evaluate if it is possible to increase genetic progress for the productivity traits of QX disease resistance and growth as well as the product quality trait of meat condition. Increased QX survival and growth are particularly important traits for the SRO industry at this current time due to Port Stephens, the second largest SRO producing estuary in NSW, reeling from the impact of QX disease outbreaks. Climate change resilience is a new trait being investigated for incorporation into the breeding program for industry to respond to this threat. We would also like to assess whether genomics can provide a pathway to increase selection for resilience.

This project has been developed in line with the Oysters Australia Strategic Plan 2020 and the FRDC R&D Plan 2020-2025. The outcomes from this project will assess the feasibility of increasing selection accuracy for traits that improve productivity (growth and meat condition) as well as reduce impacts caused by QX disease and climate change through breeding for resilience. The outcomes will assess the possibility to improve genetic selections for multiple traits such that oysters can be selected on their ability to adapt to new climate conditions, survive QX disease whilst having faster growth and better meat condition. Additionally, this project will build new knowledge skills and networks through a NSW DPI, The University of the Sunshine Coast and The University of New South Wales alliance as well as create post-doctoral study opportunities. These meet the goals in Program 1, 2 and 3 outlined in the 2020-2025 Oysters Australia Strategic Plan.

With respect to the FRDC R&D Plan 2020-2025, this project will build capacity and create knowledge through developing skills and networks between NSW DPI, The University of the Sunshine Coast and The University of NSW to breed oysters that offer oyster businesses greater profitability, reduced risk and that can adapt to changing environments.

This project will explore alternative methods to what is presently used for SRO breeding to assess feasibility of genomic selection and what might be required today to move towards genomic selection in the future. This project will start compiling a reference library for SROs that can be used in the future and promote innovation in SRO breeding to integrate the technology developed from this project. Moreover, costs associated with genomic selection are reducing which increases the value proposition for incorporation into the future. The ultimate success and transfer of outcomes from this project to end user beneficiaries will be through incorporation of these new technologies into the SRO breeding program.

QOGA has identified core research priorities that need to be addressed to improve productivity and reverse the steady decline in production.

This project will partner with QOGA and other stakeholders to address the identified need to establish new oyster farming options, technologies, and production systems. The RD&E requires a dual focus, to both improve viability of the current SRO sector, and initiate commercialisation of new TRO varieties for expansion beyond SEQ.

Recent flood events have emphasised the urgent requirement to further improve the quality and availability of QX resistant SRO stock. It is a QOGA priority to have QX resistance validation trials conducted in Qld to determine the most viable SRO options for SEQ. Validation will be undertaken in collaboration with NSW DPI (building on FRDC 2016/802) and will link with farm-based growout trials conducted at strategic sites, assessing performance relative to location and system. Outcomes will also form a benchmark for direct comparison with newly identified lineages.

With the identification of new TRO varieties (FRDC 2018-118), QOGA advocates that both BRO and LGRO require thorough investigation and the development of targeted hatchery and growout research including farm-based production trials. This aligns with QOGA’s need to access additional culture species options with increased temperature tolerance (essential for northern expansion and climate-change security) and potential QX resistance.

A research hatchery has recently been established to address QOGA’s request for a dedicated R&D hatchery. The hatchery is already producing priority oyster strains (SRO & BRO) and is capable of undertaking this required research and meeting the industry’s immediate requirement to access spat.

To efficiently address the Qld oyster industry’s stated priority needs, this project will undertake research that combines new genomic sequencing and hatchery technologies, best practice production processes and expert local oyster farmer knowledge.