Paper: Assessment of Blacklip Rock Oyster spat growth and survival in nursery systems

Paper: Assessment of Blacklip Rock Oyster spat growth and survival in nursery systems
  • Author Samantha J. Nowland and Brien H. Roberts
  • Publish date 4 July 2023
  • Type Report
  • Documents
  • Aquaculture
  • First Nations led business development

Summary

This research investigated the growth and survival of blacklip rock oyster spat (juvenile oysters) in two nursery systems, providing important baseline information to support the development of a commercial tropical oyster aquaculture industry in northern Australia.

Conducted at the Darwin Aquaculture Centre as part of the CRCNA-funded Northern Australian Tropical Rock Oyster research and development project, the study compared recirculating upweller and downweller nursery systems to determine their suitability for rearing hatchery-produced oysters.

Both systems demonstrated comparable growth and high survival rates, with oysters reaching the recommended 5 mm size for deployment to ocean-based farms approximately 59 days after hatching. Survival rates reached 97% in the downweller system and 92% in the upweller system.

The findings provide practical guidance for hatchery operators on nursery management and production timeframes, helping address a key knowledge gap in the commercial cultivation of blacklip rock oysters.

This research contributes to the growing evidence base supporting a sustainable tropical rock oyster aquaculture industry across northern Australia.

Projects

Tropical Rock Oyster research and development NT

Tropical Rock Oyster research and development NT

This project established a collaborative, cross-jurisdictional approach to address the most significant technical and regulatory challenges facing northern Australia’s fledgling Tropical Rock Oyster (TRO) industry. The project was delivered by research teams in Western Australia (A.2.1819053WA) and the Northern Territory and comprised three sub-projects, each targeting specific research needs: Sub-Project 1 – Species Identification, Pathogen Screening and Translocation Risk assessment (NT) This research standardised oyster common names and assessed the need for designated farming and translocation zones across northern Australia. It considered risks associated with genetic pollution of wild populations, existing knowledge of tropical ecosystems and oyster diseases, insights from the pearl industry, and current practices in edible oyster aquaculture in other regions of Australia. The findings provided a strong scientific base for biosecurity planning, management and operational procedures for the developing industry, while also and identifying key issues for further research and development. Sub-Project 2 – Securing commercial spat (juvenile) supply Early hatchery development work in the Northern Territory and Western Australia revealed that Tropical Rock Oysters have different larval requirements compared to the commercially produced Sydney Rock Oyster (SRO) and Pacific Oyster (PO). As a result, existing hatchery manuals for SRO and PO were found to be ineffective for TRO spat production. Researchers utilised the Darwin Aquaculture Centre’s hatchery infrastructure and expertise to refine culture techniques for the Blacklip Rock Oyster. Hatchery trials focused on improving larval settlement procedures, including experiments on salinity levels, settlement timing, and the effectiveness of chemical and substrate cues. Additional work included conditioning broodstock and evaluating optimal hatchery systems. Sub-Project 3 – Optimisation of grow-out methods and gear technology This sub-project investigated optimal grow-out methods and gear technologies for Blacklip Rock Oyster production. Farming trials were conducted using intertidal systems at two sites: South Goulburn Island (supported by the Yagbani Aboriginal Corporation) and Groote Eylandt (supported by the Anindilyakwa Land Council). The trials included: Trial 1 Assessed the impact of three basket heights in the tidal range (standard, low and dynamic) and two stocking densities (standard and half of standard) on oyster growth, survival and basket biofouling. Data collected included growth rates, shell shape, survival and biofouling. Trial 2 Compared the performance of different gear types in producing marketable Blacklip Rock Oysters. This trial provided data on oyster growth and shape, as well as qualitative insights into the operation, maintenance, and performance of each system.

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