Optimal stocking density for Sydney and Pacific oyster cultivation
University of Sydney (USYD)
A means of quantifying the optimal stocking density of oysters relative to their food resources (quantity and nutritional quality) is a necessary feature in the sustainable management of the oyster industry at a time of increasing demand both for a greater volume of production and improved production efficiency. This has been recognized by the industry as a major need for there to be further development of production. It is also urgent because of increasing scrutiny and regulation under principles of ecologically sustainable development. Maximal development can only be sustainable if local carrying capacity is well understood. Of the various ways, in theory, of arriving at quantification of optimal densities, an approach which concentrates upon the oyster and its food, measured initially at the scale of the individual lease, is practical and feasible. Once this relationship is defined, it may then with confidence be extended to a variety of habitat conditions, since it will be based upon the fundamental physiological properties of the species. This proposal aims to define these relationships via rigorous physiological determinations, coupled with appropriate field studies and modelling. The proposed product will be a tool of value to the oyster farmer and to those concerned with planning and approving the expansion of leases within coastal habitats.
1. To establish a functional relationship between stocking density, individual growth rate and yield for Sydney rock and Pacific oysters in an estuarine embayment in the Port Stephens estuary.
2. To generalise this relationship for relevance to other habitats by determining the interactions between available food, the feeding physiology and the growth of these oysters.
3. To use these formal relationships to demonstrate the optimal stocking densities for oyster cultivation in a variety of different environmental conditions.
4. To investigate the influence that feral oysters have upon such optimal density estimates.
5. To relate stocking density to the quality of the marketed oysters and investigate possible economic implications.
Principal Investigator: A.J. Underwood, B.L. Bayne, P.J.C. Honkoop & J.P. Scandol