The presence of a disease, which causes ganglioneuritis, was first confirmed in early 2006, following reports of unusually high mortality rates from several Victorian abalone aquaculture farms in late 2005. In May 2006 the disease was detected in wild populations in southwest Victoria. Its presence has since been confirmed as far east as Cape Otway, and west as far as the Discovery Bay Marine Park.
The disease causes inflammation of the nervous tissue, resulting in curling of the foot and swelling of the mouth. Please note that the disease poses no known or likely threats to human health.
Increased size limit
The blacklip abalone size limit between the South Australian border and the Hopkins River has been temporarily increased to 130mm to provide additional protection to breeding populations of recovering abalone. Recreational divers taking abalone in this area should continue using their yellow plastic abalone measures, but should use the 130mm measurement for greenlip to ensure they comply with the size limit increase. This temporary measure was developed at the request of the commercial abalone industry and in consultation with all stakeholders.
Crags to Killarney closure
In June 2006, coastal waters off Port Fairy were declared a Control Area under the Victorian Livestock Disease Control Act 1994, as the disease is listed as 'notifiable.'
The Control Area extended from the high water mark 1 km west of The Crags car park to the Killarney Beach car park. Fishing and diving activities in the Control Area were restricted to minimise the risk of human activity transferring the disease to unaffected abalone populations elsewhere in the State.
The Control Area was replaced by a Temporary Abalone Closure, in the form of a Fisheries Notice under the Fisheries Act 1995. It was put in place to protect vulnerable and accessible abalone stocks that have been impacted by the disease from fishing pressure. The temporary closure remained in place until 31 March 2011, while monitoring of abalone recovery was undertaken. The closure was discontinued in recognition of the improving abalone populations and the allocation of commercial quota to these reefs.
The Closure prohibited the:
- Taking of abalone, other shellfish and sea urchins,
- Use of commercial abalone fishing equipment,
- Collection of any substrate.
Restricted Fishing Area between Lion Headland and the Aire River
Waters between Lion Headland and the Aire River were closed to most forms of fishing from 26 June 2009 to 30 September 2009 and subsequently extended to 15 November 2009 . These control measures were introduced to support the efforts of the Victorian Abalone Divers Association (VADA), Seafood Industry Victoria (SIV) and VRFish to curb the spread of the abalone disease.
The closure included all marine waters enclosed by a line running from the southern-most tip of Lion Headland to the mouth of the Aire River and extending to the high water mark between the two points.
The following activities were prohibited within the closure:
- all methods of fishing by commercial and recreational fishers, except line fishing;
- the take or possession of rock lobster, sea urchins, abalone and other shellfish; and
- collection of any substrate
Vessels were still able travel through the area, however the use of anchors was discouraged. Other activites that were still permitted included surfing, swimming, diving (non-extractive) and walking along the shore/rocks. These temporary controls were implemented at the request of VADA, SIV and VRFish. Signs were erected at access points around the closure and flyers distributed amongst stakeholders.
This closure is no longer in place.
The abalone farms have all voluntarily disinfected and decontaminated. Sentinal trials at the two land based farms have shown that the decontamination process was essential. This process was overseen by the former Department of Primary Industries. The farms have been permitted to restock in line with processes consistent with the National guidelines for translocation of aquatic animals. This includes extensive pathology testing and biosecurity arrangements.
Since the initial outbreak of the AVG in 2005, significant resources have been allocated to research. The department hosted a second National Abalone Virus Scientific and Management Forum in October 2007 with the aim to prioritise future research projects.
In November 2007, scientists from the department Attwood facility announced that they had successfully sequenced the DNA of the abalone disease and discovered that it is a unique strain that has not been previously identified. The sequencing of the disease was a crucial step towards developing the PCR test. The PCR test provides greater confidence in the diagnosis of the disease and enables it to now be detected in abalone that are not showing visible symptoms. It may also allow scientists to distinguish between abalone that have been exposed to the disease but are immune and abalone that have not been exposed. The PCR test has since been validated and is now in operation in both Victoria and Tasmania.
Other key research projects that have been completed include the development of biosecurity control measures for all sectors and a biomass estimate near Port Fairy that aimed to assess abalone stocks impacted by the disease and guide future harvesting in these areas. In addition to the commitment and support of the abalone industry, the Fisheries Research & Development Corporation has also contributed over $700,000 to into research to date.
Further research continues to be undertaken to assess the distribution of the disease, mode of infection and taxonomy. The department is continuing surveillance and monitoring of wild abalone populations and aquaculture farms.
Informational video on the abalone disease and biosecurity control measures
To report any signs of the disease please contact the Disease Watch Hotline on 1800 675 888.