Pacific oyster mortality syndrome richard whittington

Pacific oyster mortality syndrome(POMS)

First steps towards integrated management within infected estuaries

Richard Whittington, Paul Hick, Olivia Evans, Navneet Dhand, Ana Rubio & Ika Paul-PontFaculty of Veterinary Science - University of Sydney

Oysters Tasmania meeting Smithton 18th October 2014

The plan

1. POMS in Europe2. Australian POMS situation3. Research

– from spat rearing to on-farm grow-out, – priorities to plug remaining gaps– how this links to the POMS breeding program

4. Request for farmers to help collect data

1. POMS in Europe

History of POMS“Summer mortality” in Pacific oysters

Country Year Age group Mortality Cause

Japan 1960’s adult variable unknown

USA 1980’s all variable unknown

France 1980’s young variable OsHV-1

OsHV-1 occurs in USA, Japan, and some European countries, without mass mortality

“Summer mortality” in Pacific oystersCountry Year Age group Mortality Cause

Japan 1960’s adult variable unknown

USA 1980’s juvenile variable unknown

France 1980’s juvenile variable OsHV-1

France 2008 larvae, spat massive OsHV-1 microvar

UK, Ireland, Spain >2008 larvae, spat massive OsHV-1 microvar

New Zealand April 2010 spat and adult massive OsHV-1 microvar

OsHV-1 occurs in USA, Japan, and some European countries, without mass mortality

What is OsHV-1 uvar?

• It is a marine herpesvirus• not related to human herpesvirus • cannot infect warm blooded animals• no risk to human health

• There are two important marine herpesviruses • abalone herpesvirus• ostreid herpesvirus

– OsHV-1 reference strain – the original strain– OsHV-1 microvar (uvar) – a new mutant strain

Baie de ArchachonAugust 2012

Oysters in France

The French experience

Impact of POMS in France since 2008

Response1. big players produce 10x more spat and

grow the 10% that survive 2. market price has increased3. focus is on a breeding program

– private hatcheries, mass selection– government program, selection based

on lab challenge with OsHV-1 and three species of vibrio

50% of the industry has been lost, especially small farmers

government compensation exists

incentive to reduce losses?

“Summer mortality”

Larvae < 1 month:

all dead

Spat / Juvenile <18 months:

>90% dead

Adults > 18 months:

10-40% dead

whoi.edu

POMS behaviour in Europe

Seasonal pattern of OsHV-1 µvar

2009 – Disease progresses from south to north in summer as water temperatures increases

France since 2008

French research - IFREMER

• Breeding program

• POMS remains a huge issue in 2014, 6 years after it emerged and despite millions of Euros spent in research

• Research will be ongoing

Dr Tristan Renault

2. Australian POMS situation

Port Jackson – Sydney HarbourNov 2010

Botany Bay – Georges RiverNov 2010

0

50

km

POMS in Australia 2010 to 2013

Broken Bay – Hawkesbury RiverJan 2013

Commercial production abandoned

Hawkesbury - Sequence of events 2013

Day 1 - 21st Jan• 10 am – first mortality in spat• 5 pm - mass mortality event • 7pm - samples delivered to DPI

Day 2 - 22nd Jan• Outbreak investigation commenced• Broken Bay Oyster Association

– voluntary quarantine of river– supported an outbreak investigation

• 7pm DPI lab confirmed POMS

Mullet Creek

Day 3 - 23rd Jan• 10 million dead oysters• $3 million loss locally• $0.6 million hatchery loss• Casual staff laid off• Banks called in debt

Day 7- 28th Jan• Businesses, boats, equipment sold

Day 8 – 29th Jan• Minister visits affected oyster growers

Real time outbreak investigation

1. Passive surveillance to monitor spread• farmer observations of mortality

2. Active surveillance• identify risky oyster movements in last 2 weeks• whole river survey to identify infected bays/leases• detailed assessment of all dead stock• water tests

1st question. Where?

Broken Bay Oysters, Hornsby Shire Council, University of SydneyCurrent as at 7 February

29 Jan

15 Feb

Index case21 Jan

24 Jan

29 Jan

25 Jan

2nd question. Who died?

Extreme mortality

Moderate to high mortality

3rd question. When?

Date Sites Sample size OsHV-1 qPCR

26-Oct-11 M,P 30 Negative

7-Dec-11 M,P 30 Negative


4-Jan-12 M,P 30 Negative

18-Jan-12 M,P,R,K 30 Negative

15-Feb-12 M,P,R,K 30 Negative

15-Mar-12 M,P 30 Negative

20-Apr-12 M,P 30 Negative

10-May-12 M,P 30 Negative

5-Jun-12 M,P,R,K 30 Negative

3-Aug-12 M,P,R,K 30 Negative

20-Sep-12 P 30 Negative

1-Oct-12 P 30 Negative


18-Oct-12 M 21 Inconclusive


26-Nov-12 M,P 30 Negative

13-Dec-12 M 30 Inconclusive


7-Jan-13 M,P 30 Inconclusive 4 Positive 1 M

21-Jan-13 M,P 30 Positive

2-Feb-13 P 30 Positive

15-Feb-13 P 30 Positive

21st Jan13

18th Oct 12

26th Oct 11

3 months

Sentinel oysters (6 pools of 5) each time

4th question. How did it spread?

• Within the river system?1. local oyster movements

• within 2 days of the onset of the outbreak (i.e. on or after Jan 19th)• incubation period < 10 days (oysters moved 19th Jan died 29th Jan)

2. tide and current (16 km upstream tidal movement)

• To the Hawkesbury?1. Oyster movements?

• no record of any, except certified OsHV-1 negative spat2. Oceanic source?

• tiny amount of virus arrived October 2012• massive dose arrived between 17th and 19th January 2013

– incubation period for mass mortality 2-4 days

Connectedness

US Navy 1943

Connectedness

Thirroul Beach NSW 2011Driftwood carrying oyster shell Thirroul Beach NSW 2014

Pumice (origin New Caledonia) carrying oyster spat

Connectedness

3. Targeted research on POMS

Research objective – “to continue farming around POMS”

• What factors drive the disease?• Can we exploit them?

Breakthroughs needed for:1. Hatchery production 2. Spat rearing3. Growout –juveniles/adults

Broken Bay Hawkesbury River Control site until 2013

Botany Bay Georges River Infected since 2010

10 Km

New South Wales

SYDNEY

Bruce Alford – Broken Bay Oysters

Len Drake – Endeavour oystersResearch sites

POMS research sites

Georges River tray trials 2011-2012

Spatial pattern:Non uniform transmissionUneven mortality

Percent mortality:

Georges River tray trials 2011-2012

30

1 2

3 4

5 6

7 8

9 10

11 12

13 14

15 16

55 67

50 97

47 97

18 74

8 92

8 42

13 33

3 24

OsHV-1 is not evenly distributed in water - it is attached to something

plankton vector hypothesis

Georges River field trials 2011-2012 and 2012 2013

A

B

C

It might be possible to get OsHV-1 out of seawater

November 2011

November 2011

February 2012

n=2000 spat/treatmentFlow rate= 5L/min/tank

No food supplyDaily sampling / mortality check

Co-funding: FRDC, University of Sydney, Tasmanian Oyster Research Committee, Oysters Australia through Seafood CRC

Hatchery/Safe spat rearing trials 2013 and 2014

10,000 L holding tanks

Submersible pumps

Floating basket with control spat

Safe spat rearing500 spat

Filtered water

Filter + UV

Aged water

Control water

Trial 1 Trials 2-7

Daily filter clean

Daily spat examination

4157

741

578

4157

941

580

4158

141

582

4158

341

584

4158

541

586

4158

741

588

4158

941

590

4159

141

592

4159

341

594

4159

541

596

4159

741

598

4159

941

600

4160

141

602

4160

341

604

0%

20%

40%

60%

80%

100%

2nd safe spat rearing trial - 30 Oct 2013

River controlUpweller controlFilter 100/5 µmAged waterFilter 100/5 µm + UV

Date

Cum

ulati

ve m

orta

lity

Safe spat rearing trials 2013 and 2014

Safe spat rearing:• Age seawater for 48 hours before use, or• Filter seawater to 5 micron

Hatchery-Safe spat rearing trials 2013 and 2014

Mortality %

When is it safe to put spat in the estuary?

• 500 spat placed at multiple sites • every 2 weeks Aug 2013 to May 2014• each lot checked 2 to 4 weeks later• 21 lots all together

Olivia Evans PhD student

39

Georges River – Window of Infection

1

23

4

5 1 = Mangroves2 = Pelican Gut3 = Sylvania Waters4 = Never Fail Bay5 = Lime Kiln Barr6 = Site A7= Site B8 = Site C

C

A

B

40

Mortality Data : Georges River

1

23

4

5 Wild Sites:1 = Oyster Shed Mangroves2 = Pelican Gut3 = Sylvania Waters4 = Never Fail Bay5 = Lime Kiln Barr

Farmed Sites:Site ASite BSite C

August 2013

A

C

B

RESULTS:

41

1

23

4



September 2013

A

C

B


42

1

23

4



October 2013

A

C

B


43

1

23

4



November 2013

A

C

B


44

1

23

4



December 2013

A

C

B


45

1

23

4



January 2014

A

C

B


46

1

23

4



February 2014

A

C

B


47

1

23

4



March 2014

A

C

B


48

1

23

4



April 2014

A

C

B


49

1

23

4



May 2014

A

C

B


50

Hawkesbury River – Window of Infection

1

2

34

5

1 = Patonga2 = Porto Bay3 = Mullet Creek4 = Marra Marra5 = Kimmerikong

51

RESULTS:Mortality Data Window : Hawkesbury River

1

2

34

5


August 2013

52

1

2

34

5


September 2013

Mortality Data Window : Hawkesbury River

53

1

2

34

5


October 2013


54

1

2

34

5


November 2013


55

1

2

34

5


December 2013


56

1

2

34

5


January 2014


57

1

2

34

5


February 2014


58

1

2

34

5


March – May 2014


59

Window of infection summaryRIVER First mortality Last mortality

Georges October 2013 April 2014

Hawkesbury October 2013 February 2014

• Risk of mortality is not constant throughout the season• Risk is not the same in different bays or estuaries• It is safe between May and September

What can you do to keep farming during the risky window?

• Adults – partial solution– Intertidal culture – raise growing height if you can– Otherwise it is a research priority

• Spat – no solution yet– Remains a research priority

November

May

October

2 month old

7 month old

15 month old

Rack and rail – traysLong-line - basketsFloating - baskets

7,600 - 18,000 oysters 3 ages/sizes

Every oyster examined every 7 to 14 days

Field trials 2011-2012 and 2012 2013

Standard height‘Low’

+300 mm‘High’

Adults and spat 2011-2012 and 2012 2013

Adults

+300 mm high growing height • mortality <50%

Cum

ulati

ve m

orta

lity

(%)

Low

High (+300mm)

Consistent findings were obtained at all 3 sites and in both summers

• No benefit in raising growing height in either baskets or trays• Same results in trays, hanging baskets and floating systems• Spat are just too susceptible – most die

• This remains the biggest hurdle

Spat 2012-2013

Other important observations

• Oysters that survive an outbreak are “immune” and survive the next outbreak

• OsHV-1 can be detected at a low level in some oysters more than 1 month before an outbreak– these are almost certainly the oysters that survive– can we exploit this?

• Age and size – but which is more important?

• Temperature patterns for POMS

France: water temperature and disease

Georges River summer 2012-2013 Sites A, B, CAverage weekly water temperature

31 Jul2012

21 May2013

15oC Mortality in tray and baskets trials2 month period without disease that is not explained by French data

Conclusions1. we need to intepret water temperatures under Australian conditions2. we need to standardise the way we measure water temperature3. we may be able to predict risk periods

Exploitable discoveries from research

1. Removal of virus from water

2. There is a safe window

3. Age and size are important

4. Survivors are “immune”

5. Growing height

• Safe spat rearing

• Normal cultivation possible

• Growout and fattening

This knowledge directly complements the POMS breeding program

May-October: safe period

Novel cultivation practices from the hatchery through to commercial harvest

Integrated approach

Spat - November-May: (year 1)

1. Spat held in OsHV-1 free estuaries, or2. Spat held in safe land-based systems

October

• Spat in the River • Trial fast growing

cultivation systems (FLUPSY)

1. Oysters that reach market size sell2. Other adult oysters high height (<50% will die)

5 months

November

May

October

Adults - November-May (year 2)

Survivors are immune – grow them at standard height

6 months

Safe spat rearing

market

Hatchery

Further research is needed now

November

May

October

Solve problem of spat culture during window of infectionSolve problem of grow-out for farmers who cannot raise growing heightPredict risk periods for Tasmania and South Australia

1. Exploit resistance due to age and size2. Artificially condition spat to survive3. Genetically resistant spat

November

May

October

Proposal to FRDC in current call for new projects

Species diversificationSensitive/Resistant

Dilution effectCash flow

BiosecurityActive surveillance

Quarantine protocolsControl of movements /

transfers

ResearchSelective breedingResistance PO

Other traitsReliable supply

Timeframe

EpidemiologyPathogenicityImmunology

Farming practicesHusbandry techniques

Fast growing systemsDensity

Complementary approaches

STRATEGIESfor POMS

Review business models particularly debt levels to cope with sudden cessation of cash flow

4. Request for help

• 10 farmers from different parts of Tasmania• Temperature probes on oyster leases• Duration – up to 3 years• Inconvenience – a bit• Benefit – knowledge about temperature

profiles relative to estuaries in NSW where we know POMS can occur: risk prediction

Secure yellow cap tube to floor of basket with cable tie

Pool noodle float secured inside basket with cable ties

Basket attached to long line ropein such a way that it is able to floatfreely at all times

Richard Whittington Ms Olivia Evans Dr Navneet Dhand

Dr Ika Paul-PontAnn-Michele Whittington

Anna Waldron Vickie Patten Dr Ana Rubio

The University of Sydney Oyster Team

Alison Tweedie

Dr Paul Hick

Acknowledgements

Funding agencies & collaborators• FRDC, University of Sydney• NSW I&I• Sydney CMA - BBWQIP• Hornsby Shire Council• Siminis Oyster Systems• Tasmanian Oyster Research Committee• Oysters Australia • Shellfish Culture Tasmania

Oyster growers• Broken Bay Oysters - Bruce Alford, John Stubbs,

Rob Moxham, Steve Jones• Endeavour Oysters – Bob, Len and Ted Drake,

Robert Hill and Keith Duggan• Leon and Angela Riepsamen, Grenwell Point

Thank you for your attention

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Pacific oyster mortality syndrome richard whittington