This document summarizes the Tasmanian Pacific Oyster Health Surveillance Program from October 2014. The objectives of the program are to promptly detect infectious disease, demonstrate freedom from disease, and enable market access and border restrictions. The program structure involves investigating clinical events, actively sampling oysters during summer/autumn, and piloting sampling at three ports. Going forward, the program will continue its current structure and conduct detailed sampling of one port annually while working with hatcheries on biosecurity and liaising with interstate markets. Various options are discussed for consideration, including restructuring the program or reducing it to a passive surveillance model.

1. Update of the Tasmanian Pacific
Oyster Health Surveillance Program
October 2014
Presented by Kevin Ellard & Graham Knowles
Biosecurity Tasmania
Department of Primary Industries Parks Water & Environment

2. Current Program: Objectives
Objectives remain unchanged from previous year, these
being:
•Prompt detection and diagnosis of infectious disease
within Pacific oyster production in Tasmania and
•Demonstrate freedom of disease,
in order to
•Enable market access, justification for State border
restrictions, basic assurance of seed stock
Department of Primary Industries Parks Water & Environment

3. Program during 2013/14: Structure
• Priority for
investigation of
clinical events
• Active sampling
stock during
summer/autumn
• Improvements in
reporting and turn-around
times
Department of Primary Industries Parks Water & Environment

4. • Pilot sampling of three
ports
• 160 oysters sampled
• 32 sampling points
• Sampling across range
of sizes
• Temperature >180
Department of Primary Industries Parks Water & Environment

5. Program during 2014/15 and beyond
• Structure of the program to remain the same for
14/15
• Detailed sampling of one port annually (Hobart)
• Continue to work with hatcheries on biosecurity
planning
• Continue to liaise with interstate markets
• Program due for review
Department of Primary Industries Parks Water & Environment

6. Possible options for consideration
• Restructure of DPIPWE
• Review of OIE Aquatic Health Code
• Move towards veterinary performance
standards nationally and internationally
• Keep things as they are
• Nothing
• Reduce to passive program
• Outsource coordination
Department of Primary Industries Parks Water & Environment

7. Possible options for consideration
• Separation of hatcheries and farms
• Biosecurity programs for hatcheries (closed systems)
• Ongoing surveillance for farms and environment (open
systems)
• Must have industry involvement in the
discussions
• Risk assessment of current threats
• Costs, currently program subsidised by gov. by
50%
Department of Primary Industries Parks Water & Environment

8. • This is a collaborative process and our service starts
with a detailed history from you the producer
• Defined testing of oysters at laboratory
1. Gross examination
2. Molecular test (PCR) for Ostreid Herpesvirus-1
(POMS)
3. Histopathology
4. +/- Microbiology
• Report sent to the producer and Dr Kevin Ellard, senior
veterinary officer (aquatic species). Kevin’s role is to
interpret the laboratory findings and offer advice to
producers.
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Laboratory examination

9. • June 2013. Two groups of oysters
• Group A (32 mm), group B (40mm), sourced from 2
different farms, were transferred to an estuarine lease
and set on neighbouring sites on the lease
• Persistently low salinity (10ppt) from July to Sept and
by Oct. salinity was still 10ppt; water temp 12o C
• In Oct. 10% found dead in group B and remaining
oysters had grown slower than group A. All oysters
were now 45-50mm in size.
• Oysters not graded since the transfer
• All larger oysters on farm appeared normal
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10. Case study 1: Poor condition (leydig tissue)
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11. Case summary
• No infectious causes (including OSHV1) of
mortalities or poor condition were found
• Poor adaption to low salinity by group B oysters
may have caused chronic poor growth
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12. Low salinity Research by
DPIPWE Tasmania and Univ.
Tasmania
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13. Case 2: history
•Past 3-4 weeks in June 2014, 5 to 15% mortalities
in 80mm oysters on deep water lease
•Intertidal lease not affected.
•Water temperature 11.6 to 12.5oC over past 2
wks
•Waters relatively calm with little current and no
marked tides
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14. Case 2: loss of condition (leydig tissue) and lack of feeding
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15. Case 2 summary
• No infectious causes (including OSHV1) of mortalities
or poor condition were found
• The overwhelming problem was chronic poor feed
intake causing poor condition
– Factors which affect phytoplankton (feed)
abundance include salinity, water micronutrient
levels, water temperature and currents.
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16. Acknowledgement
• Staff at Biosecurity Tasmania
– including Mt Pleasant Animal Health Laboratory
– Biosecurity Operational Branch
– Animal Health and Welfare Branch
• Tasmanian Pacific oyster growers and Tasmanian
Oyster Research Council
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