Image for All about Abalone Ganglioneuritis. Booth lashes ‘gorging Green’

In 2002-03 a herpes-like virus and a “spherical virus” with a diameter of 100-130 nanometres was reported in diseased abalone (Haliotis diversicolor) in Taiwan (Chang et al., 2005) and in Guangdong Province, China (Wang et al., 2004).

In December 2005/January 2006, a disease outbreak causing high mortality rates in abalone occurred in two land-based abalone farms in Victoria (Hooper et al., 2007); another two other marine-based farms developed the same disease, but to a lesser extent. This was the first detection of a viral disease associated with high mortality in abalone in Australia. The disease was called Abalone Viral Ganglioneuritis (AVG) and was associated with a herpes-like virus in damaged nerve tissues – the virus now called Abalone Herpes Virus (AbHV). AbHV has steadily spread along the south-western Victorian coastline causing declines in wild abalone populations. The spread of the virus in Victoria was very much more like that of an epidemic in a naïve population, and mimics the spread of the virus in Taiwan.

Tasmania’s incidents with AVG

In 2008 a severe form of the disease - Abalone Viral Ganglioneuritis - was detected at an abalone processing plant on the east coast (Mornington, near Hobart) when abalone in holding tanks developed the paralysis typical of this disease. Samples from these abalone were also sent to the Australian Animal Health Laboratory in Geelong to test for the presence of the AbHV using the Taqman PCR test for the genetic sequences unique to this virus; the PCR results were strongly positive. Abalone tested at the Mornington processing plant were positive by histology for the disease AVG and positive for the AbHV by the PCR DNA test.

In the weeks after the disease was confirmed in the processing plant, a state-wide survey of wild abalone found no signs of disease or declines in the wild abalone population. It was believed that the abalone held at the Mornington processing plant originated only from Tasmanian waters.

In late 2008 1625 abalone were sampled from open waters around the entire coast of Tasmania. All abalone had no clinical signs of disease and were classified as negative by histological examination (i.e. absence of any ganglioneuritis). In a Taqman PCR test for the presence of AbHV, 1498 of 1625 samples (92.18%) were negative (no virus present); 126 of 1625 samples (7.75%) returned ‘Ct’ (cycle threshold) values between 35.8 and 40 – i.e. they were deemed ‘indeterminate’ and a single abalone (0.06%) returned a Ct value of 34.36 which was considered a ‘low-grade positive’. This abalone was collected in the D’Entracasteaux Channel; initially this result was termed as ‘inconclusive’.

On 31 July 2009 the Tasmanian CVO wrote to me: ‘the wild PCR positive is unlikely to be a false positive’…‘material from the wild PCR positive was inoculated into naive abalone of which a couple (2) converted to AbHV-PCR positive at lower Ct values (i.e. stronger positive) than the original sample.’ Mr Andrewartha believed that the one PCR positive result from Tasmania was a true-positive, however, subsequent sampling from the location where the abalone was collected failed to detect any other PCR positive abalone.

What could this mean for the Tasmanian abalone fishery?

The first outbreak of AVG in Tasmania was at an abalone processing plant at Mornington in 2008 and it then reappeared at the plant again 2009. [No information on the second outbreak is known.] In late 2010, another abalone processing plant was closed - presumably due to the detection of AVG-affected abalone. [Information on this incident is unclear.]

In January 2011 a land-based abalone farm at Bicheno was quarantined after the disease AVG was confirmed and PCR test results confirmed the presence of AbHV in the farmed abalone. [Information on the severity of the disease in these farmed fish is unclear.] The abalone farm discharged water from the holding tanks directly into the sea.

Diving in the sea close to the abalone farm and the Bicheno-Gulch Maine Sanctuary area did not detect any diseased abalone, however, samples from an unknown number of wild abalone were ‘low-level’ PCR-positive for AbHV (two sets of wild abalone samplings by Wednesday 19 January).

There are two possibilities:

(1) AbHV is a naturally-occurring virus of Tasmanian abalone and farming/containment of abalone causes the disease to be expressed, or

(2) AbHV is an exotic and new virus to Tasmania and its initial detection in abalone processing plants or aquaculture farms is cause for concern.

The problem in accepting the first possibility is the absence of tests result demonstrating that the virus existed in Tasmanian abalone populations prior to its presence at the Mornington processing plant (Crane et al 2009) and only one wild abalone in 1625 giving a PCR-positive result after the Mornington incident in 2008.

In all the Tasmanian incidents the presence of the ganglioneuritis lesions in abalone in the presence of positive AbHV DNA has occurred in captive abalone.

In the most recent incident - at Bicheno – wild abalone close to the discharge from the abalone farm have tested positive for the AbHV DNA test.

Presuming that AbHV is naturally occurring, the detection of the virus in wild abalone could be a direct consequence of contamination of amplified virus from seawater discharge from the infected abalone farm or coincidental.

If the first possibility is correct, the virus may not produce any disease and therefore inconsequential to wild abalone around Bicheno.

However, if the second possibility is correct, further monitoring will be required to determine whether wild abalone develop clinical signs of AVG as well as testing positive for the virus. On-going monitoring of wild abalone in the Bicheno area will be required. Human transfer of abalone out of the declared infected zone at Bicheno must be avoided.

In Victoria, animal health authorities offered the theory that AVG was caused by an endemic pathogen, however, this was not supported by the severity of the disease in wild abalone populations, and the spread of the virus in the wild bears the hallmarks of an exotic pathogen. The similarity of the disease to the Taiwanese/South China disease is acknowledged. The mechanism for the introduction of such a new pathogen into wild abalone populations and its detection in aquaculture farms requires careful investigation.

At this stage, as a precaution it is of utmost importance to prevent any removal of wild abalone from the restricted area around Bicheno.

Determining whether AbHV is new, exotic and potentially pathogenic or naturally-occurring, associated with captivity and inconsequential in wild abalone is of paramount importance.

References:

Chang P.H., Kuo S.T., Lai S.H., Yang H.S., Ting Y.Y., Hsu C.L. & Chen H.C. 2005. Herpes-like virus infection causing mortality of cultured abalone Haliotis diversicolor supertexta in Taiwan. Dis Aquat Org. 65:23-27.

Crane M. St J., Corbeil S., Fegan M. & Warner S. 2009. Final Report: Aquatic Animal Health Subprogram: Development of molecular diagnostic procedures for the detection and identification of herpes-like virus of abalone (Haliotis spp.). Fisheries Research and Development Corporation Project Number 2007/006.

Wang J., Guo Z., Feng J., Liu G., Xu L., Chen B. & Pan J.. 2004. Virus infection in cultured abalone, Haliotis diversicolor Reeve in Guangdong Province, China. J Shellfish Res. 23:1163-1168.

Prepared by: David Obendorf
Registered veterinarian

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Image from Abalone Council of Australia website, HERE: of Chris-Wright-Deputy-Consul-Jayne-Gallagher-Seafood-CRC-Dean-Lisson-ACA-Chairman-Bryan-Green-MHA-Tasmanian-Fisheries-Minister-Shanghai-2010

Kim Booth: MR

MINISTER GREEN GORGES ON ABALONE, WHILE INDUSTRY BIOSECURITY STARVES
If AVG is Endemic, Where Were Significant Detections in 2008, Following 1000+ Tests? 
Kim Booth MP
Greens Primary Industries spokesperson

The Tasmanian Greens today queried assertions that Abalone Viral Ganglioneuritis (AVG) may be endemic to Tasmania, given that when more than 1000 abalone were tested for AVG in 2008 the virus was only detected in one fish, with concerns that this single detection was a false-positive that could not subsequently be replicated.

Greens Primary Industries spokesperson Kim Booth MP said that Primary Industries Minister Bryan Green has turned a blind eye to the risks posed by AVG, and to Tasmanian biosecurity issues in general [1], and called on the Minister to spend less time and funds on abalone-related junkets to China [2], and more on imposing effective biosecurity measures on all farms, recreational fishers, and fishing vessels involved in Tasmania’s lucrative abalone industry.

Mr Booth also said it is a very strange coincidence that while the government claimed that AVG was not present in wild fisheries in 2008, despite tests on more than 1000 fish, it has now only been detected in the wild at a fishery that just happens to be offshore from the latest farm-related outbreak.

“AVG is either endemic to Tasmania, or it is an introduced exotic disease, and the fact that it was only detected once in over 1000 tests conducted on wild fish in 2008, and that that particular test result could not be replicated at that time and may well have been a false-positive, strongly indicates to me that the disease is exotic, and is being spread by totally inadequate biosecurity measures,” said Mr Booth.

“It is very convenient for this Minister, who has utterly failed in his duty to impose proper biosecurity protocols in this industry and many others, for AVG to suddenly become an endemic disease in Tasmania. If it was endemic, why were there no significant detections in 2008, and why is it now coincidentally being detected offshore from the location of a farm-related outbreak?”

“The abalone fishery is too important to lose and we cannot affords to continue ignoring the known threats.”

“Minister Bryan Green has been repeatedly accused of failing to implement proper biosecurity protocols for a whole range of primary industries, and he needs to be held to account if this latest outbreak of AVG is related to inadequate biosecurity measures in the abalone industry, as appears to be the case.”

“The Greens are calling on the Minister to spend less time and funds on junkets to China, and more on developing a range of proper biosecurity protocols for abalone farms around Tasmania, in particular the mandatory imposition of closed loop systems with zero waste discharge or, at the very least, the requirement that all waste is given full tertiary treatment before being discharged, as well as boat and equipment-cleaning protocols for recreational and commercial abalone fishermen,” said Mr Booth. 

References:

The primary industry sector is concerned that many of the decisions that the State Government make in relation to biosecurity are done without consultation with industry and that risks, priorities and strategies in relation to biosecurity are seemingly undertaken in isolation of industry input.

The primary industry sector is also disappointed that although the biosecurity issue is raised repeatedly with government by all primary industry sectors it is ignored and failure to adequately allocate financial resources to biosecurity consistently occurs. Too often the cost of biosecurity is attributed to one sector (fruit fly- fruit industry, phylloxera- wine industry etc), where as in reality the cost of barrier control needs to be attributed to all industries as well as the greater community in relation to fire ants and other potential “community” pests and diseases.
[1] Excerpt from “Biosecurity For Our Future,” Primary Industry Biosecurity Action Alliance, Recommendations, published July 2010 (Report attached).

“On that night I have to admit I had to indulge in an eight-course abalone meal, which was sensational.  It was highly regarded by those people in attendance.  I can say to you that no stone has been left unturned here.  The Grey Group are extremely professional.  The presentation they gave us leading up to the launch was amazing.  The artwork associated with it and the quality of the presentation was absolutely sensational and I look forward to this trial being completed.”

TASMANIAN HOUSE OF ASSEMBLY HANSARD
Abalone Exports
Wednesday 1 September 2010 - Part 1 - Pages 1 - 29
ABALONE EXPORTS

[11.00 a.m.]
Ms WHITE (Question) - Can the Minister for Primary Industries and Water provide the
House with details on the work being done to maintain and expand exports of Tasmanian
abalone , in particular to China?
Mr Hidding - Is this the full report?
Mr GREEN - No, it is not the full report. There is plenty to report on that sojourn to China
but this is particularly about abalone . I was very pleased to work with the Abalone
Council of Australia to participate in a launch of wild-caught abalone from Australia, but
it was particularly significant from a Tasmanian context, given that we produce about
60 per cent of Australia’s wild-caught abalone and of course Dean Lisson is the chair of
the Australian Abalone Council which means that the Tasmanian connection is obviously
very prominent. I was pleased to attend the launch in Shanghai at a restaurant that hosted a
number of importers and chefs. There are an amazing number of very high-end restaurants in
Shanghai and it was extremely good to have all of those people in attendance at such a
significant launch.
The key here is that Tasmania and Australia have a sustainable abalone production. Last
year, for example, we exported 1 800 tonnes of live and processed abalone from Tasmania
alone which was worth about $94.67 million. We face competition, obviously, from Chile
and New Zealand so that is why it is important we are on the front foot in marketing into
these high value-end restaurants who are demanding a high quality product from Australia.
The Abalone Council of Australia has been able to work in partnership with the
Commonwealth Fisheries Research Centre and has attracted funds to the tune of $1.8 million.
They are working with the Grey Group, which is a worldwide advertising consulting firm that
has a large office in Shanghai to develop this product to a level that allows that high value to
be extracted through effectively what they call a ‘white corridor’ into China. Most of the
product that leaves Tasmania’s and Australia’s shores now goes through Hong Kong and it is
hard to maintain the product integrity as a result of what they call that ‘grey channel’ into
China. Often canned abalone , for example, that comes from Australia ends up with a
different label on it, like peas, and then once it gets into mainland China ends up with an
abalone label back on it but the integrity of the product itself is lost as a result.
What the CRC is trying to do is get to a point where we have an absolutely legitimate channel
going into China for that high-value product that extracts as much value for Australia and the
wild-caught industry but also opens up opportunities for other high-value products to enter the
Chinese market, and I thought the significance of this whole launch was just that. While this
$1.8 million is being spent specifically on wild-caught abalone from an Australian
perspective, it highlighted to me that if this works there are great opportunities for other highvalue
products from Australia and indeed Tasmania to enter China in a way that they have not
been able to in the past.
We are working closely with the Chinese Government at a very high level to continue to build
relationships. The Deputy Premier and I had a meeting just a couple of days ago about that.
We are working to make sure that our relationship with China is sound. We have done a lot
of work, particularly from the mining industry’s point of view, that I am sure the member for
Braddon, Mr Brooks, will be interested in at some stage. If he would like to ask me another
question about Grange Resources, for example, I would be happy to talk about that.
Suffice to say that Dean Lisson and the Australian Abalone Council are playing an
extremely important role in opening up a legitimate corridor into China now and for the
future. This is an important 18-month trial. On that night I have to admit I had to indulge in
an eight-course abalone meal, which was sensational. It was highly regarded by those
people in attendance. I can say to you that no stone has been left unturned here. The Grey
Group are extremely professional. The presentation they gave us leading up to the launch was
amazing. The artwork associated with it and the quality of the presentation was absolutely
sensational and I look forward to this trial being completed.
Mr Hidding - One final thing.
Mr GREEN - Yes.
Mr Hidding - You should place on the record that you were only able to be there because of
the extraordinary pair we gave you.
Mr GREEN - I know and I do thank the Opposition. That is exactly right. You did give me
a pair to stay, otherwise I would not have been in China for that extra couple of days, which
did drag it on a little, but thank you very much for that. It was extremely important and the
Abalone Council of Australia appreciated it, and that of Tasmania as well. It was a fantastic
launch. It was great to be part of it. I felt very proud of our industry and I hope that it goes
very well.