Through existing farming practices it is apparent that there are several factors which may be limiting production and ultimately revenue.

Firstly, there is a need to identify an “ideal production strategy” to achieve forecast production levels. As temperature significantly affects YTK growth, feed conversion ratios and health, it is essential that the relationship between growth and temperature is investigated in fish of various sizes. This information will enable CST to make informed decisions on size and time of stocking YTK into sea cages. It is anticipated that this will improve production through shortening the production cycle and will reduce the standing biomass in the water, ultimately increasing farm profitability.

Secondly, maturation may be a constraining factor in YTK production, reducing somatic growth. There are also flesh quality concerns which threaten sales of YTK harvested in November-December, a period when males exhibit maturation. However preliminary analysis of work carried out in Seafood CRC project 2008/901 suggests that male maturity did not have a significant deleterious effect on the flesh quality at that time. Though there are numerous strategies to manage maturation it is initially necessary to characterise the occurrence of maturation and the factors controlling it. With this information, appropriate mitigation strategies can be introduced resulting in economic benefits to the YTK industry.

Lastly, as production is poised to increase, it is imperative that substantial markets are developed for YTK product. One way of increasing sales is to ensure product sold is consistently of the highest possible quality. By attaining knowledge on the quality attributes, shelf-life and nutritional content of the product, producers will be able to tailor a product to specific market requirements. Likewise, as processing techniques and cold chain supply routes are diverse, it is imperative that information is attained on how these influence the quality of the product.

The 1998 survey indicated that the biomass of C. mosaicus in Port Phillip Bay was not large enough to supply the 1500 tonnes wet weight required by the Australian Company. Biomass estimates for some strata were as little as 0.6% of the estimates during 1997 (Hudson and Walker 1998). However, anecdotal reports indicated that large aggregations of C. mosaicus occurred in Corner Inlet during 1998 and a survey during March 1999 indicates a very high biomass present during 1999. This highlights the high inter-annual variability in abundance of jellyfish and need for flexibility to harvest jellyfish from different regions, depending on size and distribution of the stocks. Stock Assessments are needed for the various regions before harvesting begins. This information is essential to assure investors of the viability of the resource.

The 1997, 1998 and 1999 surveys indicate that new sampling methods are required for providing more efficient field survey work and more robust estimates of abundance. The current method has the major limitations that the setting of sampling strata boundaries and counting of jellyfish depend on being able to see the jellyfish in the water column from the surface. Because the vertical distribution of C. mosaicus varies with weather condition and time of day (Hudson et al. 1997), there is a need to develop a sampling unit where sampling depth within the water column can be carefully controlled.

To provide for more reliable biomass estimates and for development of harvest strategies, there is a need for morphological, fecundity and size at maturity data of C. mosaicus. Also, there is a need to establish whether or not C. mosaicus harvested from Port Phillip Bay meet Australian national health standards. Other fish and shellfish harvested from Port Phillip Bay have been shown to be contaminated with various toxicants (Phillips 1976, Walker 1982, Walker et al. 1982, Fabris et al. 1995, Wu and Groves 1995, Walker et al. 1998). There is a need to test C. mosaicus for heavy metals, organochlorines, hydrocarbons and tributyltins in localities in Port Phillip Bay where these contaminants are known to occur.

Funding for the jellyfish research during 1997, 1998 and 1999 is from several sources. The 1997 survey and the harvesting, processing and export trials were funded by the National Seafood Centre ($15,000), Fisheries Victoria ($10,000), Business Victoria ($10,000), and Beijian Gaizhou Aquatic Products Industrial Corporation ($15,000), and the 1998 surveys of Port Phillip Bay and Westernport Bay were funded by Business Victoria ($10,000). The 1999 surveys of Port Phillip Bay, Westernport Bay and Corner Inlet are being funded by FRDC ($15,000) and Fisheries Victoria ($10,000).

This FRDC application for funds covers development of a 'jellyfish sampling unit' during 1999, and survey and collection of biological samples in Port Phillip Bay, Westernport Bay and Corner Inlet during 2000, 2001 and 2002. It is proposed that Fisheries Victoria meet the cost of the chemical laboratory analyses ($97,500) and FRDC meet the other costs ($322,832).

References
Anon. (1997). Fishery Statistics- catches and landings. FAO Yearbook 80 1995.
Fabris, G. J., Monahan, C.A., Werner, G. F., and Theodoropoulos, T.(1995). Impact of Shipping and Dredging on Toxicants in Port Phillip Bay. CSIRO Port Phillip Bay Environmental Study. 30 pp.

Hudson, R. J., Bridge, N. F., and Walker, T. I. (1997). Feasibility Study for Development of a Commercial Jellyfish Fishery in Victoria. Final Report to Fisheries Research Development Corporation, 40pp (Marine and Freshwater Resources Institute: Queenscliff).

Hudson, R.J.,and Walker, T.I. (1998). Distribution and abundance of the jellyfish Catostylus mosaicus in Port Phillip Bay and Western Port. Report to Business Victoria and Fisheries Victoria, 16pp (Marine and Freshwater Resources Institute: Queenscliff).

Kingsford, M. J., and Gillanders, B. M. (1995). Fishery and research priorities for Catostylus mosaicus Report for the Australian Nature Conservation Agency. 25 pp. (University of Sydney: Sydney).

Phillips, D. J. H. (1976). The common mussel Mytilus edulis as an indicator of pollution by zinc, cadmium, lead and copper. I. Relationships of metals in the mussel to those discharged by industry. Marine Biology 38, 71-80

Walker, T. I. (1982). Effects of Length and Locality on the Mercury Content of Blacklip Abalone, Blue Mussel Sand Flathead and Long nose Flathead from Port Phillip Bay, Victoria. Australian Journal Marine and Freshwater Research. 33, 553-560.

Walker, T. I., Glover, J. W. and Powell, D. G. M. (1982). Effect of Length Locality and Tissue Type on Mercury and Cadmium content of the Commercial scallop Pecten alba Tate from Port Phillip Bay, Victoria. Australian Journal Marine and Freshwater Research. 33, 547-552.

Walker, T. I., Fabris, G. J., Knuckey, I. A., Hudson, R. J. and Sporcic, M. I. (1998). Webb Dock Marine Ecology Study. Final Report to Melbourne Port Corporation. 99 pp. (Marine and Freshwater Resources Institute: Queenscliff).

Wu, R., and Groves, A. (1995). Cadmium and lead in tissues of scallops from Port Phillip Bay, Australia. Water Science Technology 31, 479-483

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Vibrio species are a notorious pest in all aquaculture systems, producing significant losses in productivity. However, the problem still persists today because the causative agents and associated virulence factors have not been adequately identified and, because little is known about environmental conditions that cause the pathogen(s) to proliferate. Supply of oyster spat is currently failing to meet demand consistently in Australia, with Australian hatcheries only producing seed for the local market of approximately 250 million a year compared to a world market in excess of 10 billion oyster seed. Solving this problem will allow Australian oyster hatcheries to design and implement effective risk management systems, thus increasing supply to expand national and international markets. In addition, the aquaculture industry needs greater human capability and capacity to manage disease in aquaculture operations.

Relevance to industry priorities and Seafood CRC milestones
The associated Program and theme is within Production Innovation – Program Manager Dr Graham Mair - Outcome: Increased profitability and industry value through production innovation.

Specific output and associated milestones include:

1.3 Output: Removal or reduction of key production constraints in selected aquaculture systems
1.3.3 Milestone: Strategic disease management approaches and technologies developed for at least two aquaculture species
1.3.5 Milestone: Production efficiency gains from genetic, health management and nutritional interventions quantified to inform long-term strategies and estimate commercial benefits

The South Australian oyster industry is recognised as a major economic contributor of seafood to the state. In the 2000/01 financial year the total value of the Pacific oyster production in SA was about 12 million dollars. The industry is expected to increase by 10% per annum over the next five years resulting in the production of Pacific oysters worth nearly 20 million dollars by 2006. However, since the mortality of oysters was first noted in SA about three years ago the industry has suffered 5 to 20% losses each year of their marketable stocks, which is equivalent to 0.726 to 2.9 million dollar losses in 2002/03 and 0.96-3.8 million dollar losses in 2006/07 if mortality is not controlled and remains at the same relative level. A less optimistic forecast is that epidemiological factors could result in a much greater and possibly catastrophic rate of increase in losses in the future.

The industry views the need to understand and control the reasons for these losses as a matter of great urgency. However, the farmer’s ad-hoc approaches have failed to identify any clear direction to address the present mortalities. Due to this, the South Australian Oyster Research Council has spent considerable time discussing the matter with various researchers and has decided to support a specific research project to systematically address the issue. This proposal outlines the approaches to be taken.

If this project can achieve a 50% reduction in mortality one year after its completion, the savings to growers will be approximately 0.455-1.9 million dollars in the first year of implementation in 2006/07. These savings are more than the total investment by FRDC to this project ($364,197) and equivalent to half of the entire project cost to all parties (1.144 million dollars).

In addition, minimising the impact of mortality on the Pacific oyster aquaculture industry in SA will also strengthen the confidence of new growers and investors in this industry thereby encouraging its further expansion.