To help establish an improved basis for ecologically sustainable aquaculture development and ecosystem based resource management, there is a strong research need to a) determine what Pacific oysters, blue mussels and cockles consume in the unique, typically large, shallow, high salinity and apparently low productivity waters of South Australian (SA) bays, and b) understand the temporal and spatial fluctuation in food availability, and c) the relationship between food availability and Pacific oyster farm productivity. This need is driven by:
1) bivalves could not be included in the modeling of carrying capacity of Spencer Gulf mainly due to the lack of knowledge on the trophic function and feeding physiology of oysters;
2) the oyster industry has been experiencing average Pacific oyster mortalities between stocking and harvesting on an ongoing basis of 35% (up to 50%) in some areas, and believe this loss is associated with a complex interaction between food availability, oyster condition and a variety of biological, chemical and physical stressors; and
3) an interest of the State Government, industry and potential new aquaculture entrants to maximize the use of existing lease allocations and diversify the bivalve species farmed as a risk management strategy for a potential OsHV-1 µvar outbreak in SA. Additional Pacific oyster or new species stock will potentially increase competition for the limited available food.
Final report
For ecosystem-based management to be successful and carrying capacities to be determined, a detailed understanding of the abiotic and biotic components of the ecosystem, their interactions and how they drive productivity within the local region is required. In the FRDC - PIRSA Initiative II project 2009-046 titled ‘Carrying capacity of Spencer Gulf: hydrodynamic and biogeochemical measurement modelling and performance monitoring’ bivalves were excluded because of a lack of knowledge about commercial bivalve feeding within the Gulf. The current report aimed to help fill this knowledge gap by supplying information on what bivalves are feeding on temporally and spatially in selected South Australian (SA) bays, seasonal patterns in bivalve food availability, trophic interactions between key commercial bivalve species and what factors are influencing Pacific Oyster performance.
