Firstly I appreciate the correspondence received in regards to the Proposal to permit the cultivation of triploid Pacific oysters in NSW estuaries. Your views and concerns have been reviewed. You are receiving this letter to help provide an understanding of the situation and the decisions that have been made at this current time.
The devastation that QX disease has caused throughout the Hawkesbury river region is a primary concern. Hawkesbury river oyster farmers produce over half of all NSW oysters. It’s incredibly important not only on an ecological standpoint but also from an economic position to take all necessary measures to not only look into preventing QX but also other alternatives to keep the Hawkesbury river oyster industry alive.
Previously researchers have looked into disease prevention strategies for QX disease. This incorporated the use of disease zoning to help control spread. However due to the multiple factors that fuel QX, such as environmental stressors as well as the parasite Marteilia sydneyi, the disease continued to spread throughout the region. There was also an implication as spat is required to be transferred between estuaries in order to increase populations. This enabled the QX disease to spread further and faster than anticipated.
The proposal to permit the cultivation of triploid Pacific oysters in NSW is the next step in helping to get oyster farmers back on their feet. As expressed through your correspondence there were many concerns in regards to the introduction of this species in NSW estuaries such as the possibility that Pacific oysters could become reproductively capable. Farmers will be provided with literature in regards to maintaining their farms and fisheries officials will monitor the farms for the first 4 years of cultivation. With effective management the prevention of uncontrolled spread should not be a long-term problem.
The benefits for this proposal far outweigh the concerns in this instance. Summarized below are the main key benefits that have shaped the decision to implement this permit.
- At this present time the cultivation of Pacific oysters in the Port Stevens region has been a success. There have been no major ecological impacts in regards to cultivating this species observed to date.
- As Hawkesbury River oysters are such a large percentage of commercial farmed oysters in NSW it is important to find an alternative with proven resistance to mass mortality diseases such as QX and Winter mortality. The Pacific oyster is resistant to both of these diseases.
- Pacific oysters are found to be 4.1% heavier, have a higher dry meat and condition index than Sydney Rock Oysters after a period of 2.5 years of growth. This indicates a fast growing, possibly larger product than previously grown, with a high standard of quality.
- Pacific oysters grow to the standard market size 6-18 months faster than Sydney Rock Oysters, providing a larger supply to customer demand.
- Oyster farmers have the potential to earn a higher living, as these oysters can be cultivated all year without any disease related disturbances. Farmers also have the potential to reduce overall costs in regards to disease prevention and loss of income due to outbreak.
It is with great consideration and intensive research that this next step in oyster disease control is implemented in the Hawkesbury river region. The underlying factor is that without the introduction of Pacific oysters, the Hawkesbury River oyster populations will inevitably die out. This would not only be a major loss to the income and livelihood of oyster farmers in the region but also to the estuary environment and consumer.
Mr Neill Blair,
Minister for NSW Department of Primary Industries.
20th May 2015.
Port Stephens Fisheries Institute
Locked Bag 1, NELSON BAY NSW 2315
Tel: 024982-1232 Fax: 02 4982 1107
ABN 72 189 919 072 www.dpi.nsw.gov.au
- Green, T., Raftos, D., O’Connor, W., Adlard, R.D., Barnes, A.C., 2011. Disease Prevention Strategies for QX Disease (Marteilia sydneyi) of Sydney Rock Oysters (Saccostrea glomerata). Journal of Shellfish Research, Vol 30, pp.47-53.
- Nell, J.A., Cox, E., Smith, I.R., Maguire, G.B., 1994. Studies on triploid oysters in Australia. I. The farming potential of triploid Sydney rock oysters Saccostrea commercialis (Iredale and Roughley). Aquaculture, Vol 136, pp. 243-245.