As noted in Chapter 2, discursive processes in risk assessment need a structure that ensures the integration of technical expertise, regulatory requirements and public values. A series of regional workshops, chaired by the author, and communiqués with industry, directed by the author, were conducted during 2002–2004. The industry required alternative infrastructure materials that are durable, recyclable, economical and practical. Product life cycle management was a key component in assessing alternative materials (Smith et al., 1993). Successful alternative materials / products were needed to deliver cost savings to the oyster industry, be convenient to use and outlast treated timber in the estuarine environment.
The program identified the following objectives for alternatives to replace the phase- out of tar treated timber:
• at least as cost-effective as Tar Treated timber, but preferably cheaper and more durable; an ideal alternative would also be compatible with existing oyster farming infrastructure to reduce the costs of implementation
• is an effective oyster culture material
• allows present production rates with current staffing and investment levels • has a clear waste management pathway that is available in all oyster farming
districts and preferably includes recycling of waste materials
• has little or no environmental impact when used in estuarine environments, and in particular does not leach toxic compounds into estuarine waters and sediments
• is safe for oyster industry workers to use and does not have any serious health and safety concerns.
5.8.1 Present Trends in Material Replacement
Since the commencement of the project in 2002, significant advances have been made in the development of cost-effective HDPE fluming for wooden post and rail and its use has become widespread in the industry. This fluming provides long-term (manufacturer suggests 15–20 years) protection to low cost renewable timbers and
eliminates the need for use of tar or other protectants. Very significant advances have also been made in plastic trays and basket technology. Unlike traditional wooden trays, these containers do not require annual drying, cleaning and recoating with tar, offering significant cost savings (R. Moxham, personal communication, April 2005). This combined with increased market demand for single-seed oysters and commercial availability of S. glomerata selected hatchery stock has motivated widespread use of plastic containers in the oyster industry.
In August 2004, oyster farmers were requested, in their annual production returns, to provide present estimates of oyster lease infrastructure (expressed as a percentage of the total for that type of equipment) that was composed of plastic. Figure 29 shows the summary of percentages for each type of infrastructure. There was a very significant increase in the use of oyster containers that do not use tar (e.g. plastic trays and baskets) up from 10 per cent in 2002 to over 50 per cent of industry indicating primary use of this equipment in 2004. There was also a marked increase in the use of alternative material for post and rail. Subsequent development of cost-effective and structurally sound food grade PVC (using organic stabilisers) sticks completed the range of tar-alternative products, commercially available, for the various components of oyster farming infrastructure used in the NSW oyster industry ( C. gigas AG Tar Replacement subcommittee, personal communication, December 2004).
Figure 29. Industry use of tar for components of lease equipment as a percentage of enterprise infrastructure (Source: DPI Fisheries, 2004)
Permit Holders Tar Usage
'03-'04 0% 20% 40% 60% 80% 100%
Markers Post Rail Trays
Infrastructure % P e rmi t H o ld e rs 0-10% 11-90% 91-100% Tar Use
As a result of this inclusive risk assessment process that engaged sectors of government and private industry in a collaborative arrangement, the industry moved rapidly to develop alternative lease infrastructure materials in an active and innovative design and evaluation program with the plastics industry. Products needed to meet the objectives defined during the risk assessment process. Timber Alternatives in the NSW Oyster Industry Project won the NSW Fish Markets National Seafood award for Environmental Excellence in 2003. An example of the outcome of this risk-based policy is shown in Figure 30 for a traditional lease configuration built using recyclable plastic products.
Figure 30. Oyster lease in the Hawkesbury River built entirely from plastic (Courtesy: Rob Moxham)
5.8.2 Floating Cultivation
In an effort to enable productivity to increase, deepwater (hanging) culture research for S. glomerata production commenced in NSW in 1973 (Medcof and Malcolm, 1974). The practice of growing oysters sub-tidally on rafts and other floating infrastructure in suitable locations is now increasing and new types of plastic cultivation infrastructure have encouraged this trend. Regular crop drying / treatment is required to control mudworm in floating cultivation techniques. New floating surface-cultivation methods using HDPE and poly-urethane floats (Figure 31) have reportedly been able to minimise mudworm and overcatch and offers promise in suitable protected areas (S. McOrrie, DPI Fisheries, personal communication, May 2005). The last part of the production process in floating cultivation systems needs to be intertidal to harden shells and
enable the development of strong adductor muscles, to keep the shells tightly closed, which extends the post-harvest shelf life of live oysters (Crawford, 2003).
Figure 31. Plastic floating cultivation (Courtesy: S. McOrrie)
5.9 Conclusion
Results in Chapter 5 demonstrate that policy based on a risk assessment framework optimise outcomes for strategic management of the NSW oyster industry. The risk assessment framework applied to oyster lease infrastructure in the NSW oyster industry resulted in the development of a phasing out program for hazardous tar treated timber and successful development and adoption of recyclable plastics for farming oysters. It has provided significant benefits to the industry from an overall farm management and profit perspective and reduced lease construction and maintenance requirements. It has also facilitated adoption of single-seed technology, reduced the risk of lease areas falling into a derelict state and will mitigate lease sediment contamination and hazardous waste disposal issues of tarred oyster sticks. This ‘step-change’ in cultivation practices in the NSW oyster industry also adds to the ‘clean-green’ image as they strive to ‘walk the talk’.