update of the tasmanian pacific oyster health surveillance program kevin ellard and graham...

Department of Primary Industries Parks Water & Environment

Presented by Kevin Ellard & Graham Knowles

Biosecurity Tasmania

Update of the Tasmanian Pacific Oyster Health Surveillance Program

October 2014

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


Program during 2013/14: Structure

• Priority for investigation of clinical events

• Active sampling stock during summer/autumn

• Improvements in reporting and turn-around times



• Pilot sampling of three ports

• 160 oysters sampled• 32 sampling points• Sampling across range

of sizes• Temperature >180


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


Possible options for consideration

• Keep things as they are

• Nothing

• Reduce to passive program

• Outsource coordination

• Restructure of DPIPWE

• Review of OIE Aquatic Health Code

• Move towards veterinary performance

standards nationally and internationally


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%

• 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

• 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


Case study 1: Poor condition (leydig tissue)


• 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

Case summary


Low salinity Research by DPIPWE Tasmania and

Univ. Tasmania


•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

Case 2: history


Case 2: loss of condition (leydig tissue) and lack of feeding


• 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.

Case 2 summary


• 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

Acknowledgement


update of the tasmanian pacific oyster health surveillance program kevin ellard and graham...

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