Department of Primary Industries Parks Water & Environment

Presented by Kevin Ellard

Update of the Tasmanian Pacific Oyster Health Surveillance Program

Background

•  Program first established in 1990

•  Coordinated via DPIPWE laboratory based around submission by producers

•  Program re-written 2007 to ensure it complied with OIE principles (World Organization for Animal Health)

•  Introduction of sample collection and testing program in 2010/11

•  Similar programs exist for salmonid &abalone industries

Department of Primary Industries Parks Water & Environment

Current Program: Objectives

•  Meet OIE requirements

•  Detection and diagnosis of infectious disease within Pacific oyster production

•  Demonstrate freedom of disease for market access

•  provide justification for State border

•  provide a basic level of assurance regarding the health status of seed stock

Department of Primary Industries Parks Water & Environment

Current Program: Structure

•  Attempts to Focus on clinically affected stock

•  Priority for submissions from growers of poorly performing or sick stock

•  Active collection of stock by DPIPWE during second 6 month period

•  Introduction of sampling for OsHV-1 during 2010/11

Department of Primary Industries Parks Water & Environment

Current Program: Structure

Testing target

• 600-700 farmed oysters from across Tasmanian leases

• Target figure must include 60 oyster from each lease supplying broodstock to hatcheries

• Twice yearly sampling of 60 oyster spat from each hatchery

• Laboratory testing histopathology (+ others as required) and PCR for OsHV-1

Department of Primary Industries Parks Water & Environment

Department of Primary Industries Parks Water & Environment

2010/11 data Submissions   Number   Mean  

Micro.   2   44   22  

Mol. Biol.   37   1532*   41  

Parasit.   2   220   110  

Histopath.   54   4336   80  

Submissions   Number  Active   41   1652*  Passive   2   44  

Hatchery Cert.   11   2650  

Total   54   4346  

Department of Primary Industries Parks Water & Environment

2011/12 data Submissions   Number   Mean  

Micro.   3   84   28  

Mol. Biol.   42   44392   1057  

Parasit.   0   0   0  

Histopath.   52   44363   853  

Clin Path.   1   10   10  

Submissions   Number  Active   29   751  

Passive   21   49  

Hatchery Cert.   5   44340  

Total   55   45140  

Department of Primary Industries Parks Water & Environment

Issues

July Aug Sep Oct Nov Dec Jan Feb Mar Apr May June Total

2010/11 1 0 1 2 0 0 2 0 0 3 35 0 44

2011/12 2 0 0 2 1 0 0 1 0 8 20 0 34

0

5

10

15

20

25

30

35

40

45

50

Number of oysters tested each month 2010/11 & 2011/12

Department of Primary Industries Parks Water & Environment

Findings

0

1

2

3

4

5

6

7

8

9

Dig. gland path.

Vibrio infecion

Post spawn. Change

Shell blistering

Excess. biofouling

Invert. infestation

Gastritis Gut epith. Path.

Trichodina Abnormal shells

Abnormal meat

Case 1

Department of Primary Industries Parks Water & Environment

•   Low numbers (1 in 10 000) of 2 yo inter-tidal oysters that had bulging shaped shells.

•   The bottom shell grew with a curve causing poor shell seal at the valve.

•   When shucked, the oysters have a firm pointed raised process extending from the inner shell wall through the base of the adductor muscle.

Case 1

Department of Primary Industries Parks Water & Environment

•   The firm deposits at the base of the adductor muscles in some oysters, suggested the deformed valves were difficult to close and place excessive strain on the adductor muscle and its shell attachment.

•   Affected oysters would eventually die because they couldn’t effectively close their shells.

Case 1

Department of Primary Industries Parks Water & Environment

•   Factors that influence shell growth include water temperature, turbidity, salinity and soluble calcium. Because most of these factors would be constant across the lease, changes in turbidity, due perhaps to strong currents/tides, may be responsible for the exaggerated shell growth in this small population of susceptible oysters.

Department of Primary Industries Parks Water & Environment

Future Objectives

•   To get better representation of clinically affected oysters

•   To produce 5 yearly reports on the health status of the industry

•   To incorporate the surveillance program into an industry biosecurity program

•   To obtain establish recognition of the program with NSW, and other, authorities

Department of Primary Industries Parks Water & Environment

Program Contributors DPIPWE Animal Health Laboratories •  Graeme Knowles ,Veterinary Pathologist

•   Belinda Jones, Technical Officer

•   Jim Lentern, Laboratory Manager

•   Stephen Pyecroft ,Veterinary Pathologist (Branch Manager)

DPIPWE AH&W Branch •   Rob Chandler Stock Officer •   Glen Graves Stock Officer •   Kevin Ellard Veterinary Officer

Our thanks to all Tasmanian oyster producers

Department of Primary Industries Parks Water & Environment