Exploring The Occurrence And Potential Associated Risk Factors For Pilchard Orthomyxovirus (POMV) In Tasmanian Farmed Atlantic Salmon
Funder
Fisheries Research and Development Corporation
Funding Amount
$209,295.62
Summary
Following basic epidemiology principles, no infectious disease occurs ‘randomly’ and its occurrence follow logical and predictable patterns. The presence of an infectious agent is unlikely sufficient to explain these patterns and most aquatic diseases result from the complex interaction between the agent, the host and its environment. Therefore, the targeted outcome for a POMV control plan is threefold: 1. Decrease transmission between infected and susceptible fish groups – this requires ide ....Following basic epidemiology principles, no infectious disease occurs ‘randomly’ and its occurrence follow logical and predictable patterns. The presence of an infectious agent is unlikely sufficient to explain these patterns and most aquatic diseases result from the complex interaction between the agent, the host and its environment. Therefore, the targeted outcome for a POMV control plan is threefold: 1. Decrease transmission between infected and susceptible fish groups – this requires identifying risk factors associated with the introduction, spread, and maintenance of the pathogen within the industry; 2. Decrease the number of susceptible fish – this mainly requires identifying risk factors associated with the susceptibility of the host (e.g. husbandry-related stress) and the development of a safe and effective prophylaxis; 3. Decrease the amount of virus in the environment - this requires detecting infected fish cage(s) early to implement timely control strategies. Diagnostic capacity to confirmed POMV outbreak has been developed and is currently used in routine by the industry. A vaccine against POMV is currently under development at the Tasmanian Aquatic Animal Health and Vaccines Centre of Excellence and will be available in the future. However, little is known about risk factors specific to POMV and about its full economic impact. We define as a ‘risk factor’ any attribute of the agent, the host or its environment that increases the risk and intensity of a disease outbreak. Most of the environmental risk factors (including farming practices) facilitate the introduction, transmission, or maintenance of the pathogen; while the host risk factors affect the susceptibility of the host and its capacity to become diseased. Like the closely related ISAv, the magnitude and occurrence of POMV outbreaks appeared to be highly variable. This supports the existence of additional factors other than the POMV infection that contribute to the intensity of an outbreak. It is anticipated that by identifying and intervening on some of the manageable risk factors, the frequency and the severity of POMV outbreaks can be reduced. Objectives: 1. Describe the occurrence of POMV outbreaks in the Tasmanian salmon industry 2. Quantify the direct financial impact of POMV mortality to the Tasmanian salmon industry 3. Identify potential management, environmental and stock risk factors directly or indirectly increasing the risk and intensity of a POMV outbreaks Read moreRead less
Minor Use Permit For Oxytetracycline In Marine And Freshwater Crustaceans
Funder
Fisheries Research and Development Corporation
Funding Amount
$75,000.00
Summary
This project will develop a Minor Use Permit application for oxytetracycline for use in crustacean aquaculture comprising: - a human health assessment focusing on worker exposure to OTC through mixing and administration - an environment assessment comprising use of existing trigger values with estimated release volumes of chemicals to understand environmental safety and to develop environmental release conditions - an efficacy and safety summary based on published information As ....This project will develop a Minor Use Permit application for oxytetracycline for use in crustacean aquaculture comprising: - a human health assessment focusing on worker exposure to OTC through mixing and administration - an environment assessment comprising use of existing trigger values with estimated release volumes of chemicals to understand environmental safety and to develop environmental release conditions - an efficacy and safety summary based on published information Assembly of these and all other relevant data into a Minor Use Permit application and submission to APVMA. Objectives: 1. Obtain a minor use permit for oxytetracycline use in crustacean aquaculture Read moreRead less
The Feasibility Of A Financial Safety-net: Investigating Financial Mechanisms To Protect Oyster Growers From Disease Outbreaks
Funder
Fisheries Research and Development Corporation
Funding Amount
$100,000.00
Summary
The oyster industry have long recognised their exposure to the unpredictable nature of the environment. Considerable time, effort and resources have been invested in risk mitigation activities. Examples such as Selective Breeding Programs, Quality Assurance Programs, Environmental Management Systems and innovations in growing techniques and animal husbandry are all designed to improve the attritubes of stock and to mitigate the likelihood & severity of a disturbance. It has been identified howev ....The oyster industry have long recognised their exposure to the unpredictable nature of the environment. Considerable time, effort and resources have been invested in risk mitigation activities. Examples such as Selective Breeding Programs, Quality Assurance Programs, Environmental Management Systems and innovations in growing techniques and animal husbandry are all designed to improve the attritubes of stock and to mitigate the likelihood & severity of a disturbance. It has been identified however, that there has been minimal investment in last resort options that support growers through worst-case scenarios.
While state & federal disaster arrangements are well established to support primary producers following declared natural disasters, the same mechanisms do not exist for disease outbreaks. Attempts to establish an aquatic deed (officially known as the aquatic EADRA - Emergency Aquatic Disease Response Arangement) have so far failed, and traditional stock insurance (such as that available to cattle producers, or ranched tuna) is not readily available to oyster farmers.
This situation has escalted following the Qx outbreak in Port Stephens, NSW. Despite suffering catastophic losses, oyster farmers in this estuary have received little support, beyond fee waivers and assistance associated with flooding events in the region. In 2019, the estuary hosted ~45 oyster farming businesses with an annual GVP of well-over $10m. Almost all of these businesses are now operating part-time, and even the most productive and profitable of growers have needed to find off-farm work to supplement their income. With considerable infrastructure in the water, farmers are unable to walk away from leases, as tipping fees alone are estimated to exceed $5m.
Understandably growers around the state have been rocked by the outbreak, the associated response and lack of financial support, and as a result have been reassessing their own exposure to risk. One thing that has also become clear, is that industry needs to take charge of their own future and look at measures to support their recovery, reestablishment or dignified exit following disease incursions.
This application seeks funding support for NSW Farmers to drive this process. This will involve the development and administration of a tender and contracting process to deliver an options document exploring the advantages and drawbacks of various financial support mechanisms current available and their appropraiteness for implementation in the oyster industry. This will include the investigation of solutions that are estbalished in other states, and other agricultural sectors. It is anticipated that recommedations put forward will be broadly split into 1) mechanisms that can be implemented at the farm/enterprise level, 2) mechanisms that may be implemented at the state/sector-wide level.
The options paper will provide valuable information which may inform the actions of fishing & aquaculture sectors around the country. Objectives: 1. By October 2024, obtain insights into potential financial support mechanisms, and their suitability for implementation in the NSW oyster industry. Read moreRead less
Safeguarding Our Sydney Rock Oyster Industry Against QX Disease
Funder
Fisheries Research and Development Corporation
Funding Amount
$200,000.00
Summary
Outbreaks of QX disease in Port Stephens in 2022 and 2023 mark the continued spread of this disease into Sydney rock oyster (SRO)-producing estuaries in NSW and QLD over the last 50 years. In severe years, QX can cause up to 90% mortalities in affected stock, therefore this disease poses a major threat to an industry that is of substantial economic, historic and cultural value. Despite the apparent presence of the causative agent (M. sydneyi) in nearly all estuaries undertaking SRO produc ....Outbreaks of QX disease in Port Stephens in 2022 and 2023 mark the continued spread of this disease into Sydney rock oyster (SRO)-producing estuaries in NSW and QLD over the last 50 years. In severe years, QX can cause up to 90% mortalities in affected stock, therefore this disease poses a major threat to an industry that is of substantial economic, historic and cultural value. Despite the apparent presence of the causative agent (M. sydneyi) in nearly all estuaries undertaking SRO production, disease only occurs in some, and biosecurity protocols further complicate SRO farming as stocks from high-risk estuaries cannot be moved into estuaries that have a lower QX disease risk profile.
Reasons behind the expression of QX disease in some estuaries but not others currently remain unknown. In France, a related parasite, M. refringens, was originally thought to be a widespread cause of marteiliosis in the European flat oyster (Ostrea edulis) as well as mussels belonging to the genus Mytilus. M. refringens O (oyster) type and M (mussel) type, which were originally described due their differential pathogenicities in the respective hosts, have more recently been found to constitute separate species, with M type being renamed as Marteilia pararefringens. A similar situation may exist in Australia with M. sydneyi constituting more than one species and with the more pathogenic strains being responsible for QX disease outbreaks. Historically these questions could not be meaningfully answered due a lack of genetic information about M. sydneyi; however NSW DPI has recently undertaken a genome sequencing project on M. sydneyi that can facilitate strain comparison. Therefore, one aim of this project is to characterise Marteilia strains from estuaries where disease occurs, and compare with those from estuaries where disease does not occur, to better inform biosecurity policies. If the M. sydneyi strains are identical across estuaries, then this may enable biosecurity policy to be modified to allow oyster translocations across so called “high” and “low” risk estuaries. However, if strains do differ across high and low risk estuaries, then any biosecurity policy will be aimed at protecting estuaries not currently experiencing QX outbreaks from the introduction of high pathogenicity strains.
QX disease remains as the primary known threat for SRO production. Due to significant knowledge gaps in how this disease is transmitted, the use of selectively bred QX resistant oysters is the main management tool used to enable cultivation to continue in estuaries where the disease is enzootic. QX survival is a quantitative and a responsive trait where applied breeding offers a good solution to increase QX survival with significant economic benefits for industry. QX survival breeding is reliant on field challenges however, this method works well to increase resistance. Best results for improving QX survival are achieved through a combination of breeding and management practices to minimise impacts. It is recommended to use oysters selected for QX survival as a risk management strategy to reduce stock losses before a QX disease outbreak occurs in an estuary. When oysters selected for QX survival are used in estuaries affected by QX, it is important to deploy spat when M. sydneyi infections have ceased and harvest these oysters prior to a second disease exposure. This relies on specific timing of commercial hatchery production and fast oyster growth which is a trait under selection in combination with QX survival. Field exposures that run over two seasons of QX disease are now used to increase survival following consecutive outbreaks. Other diseases or factors that compromise SRO health prior to or during M. sydneyi infections also reduce the effectiveness of breeding.
Increasing genetic gains for QX survival has been the primary objective of the breeding program since its inception. A genomics project is currently underway which aims to identify genetic markers for QX disease resistance to increase genetic progress for this trait. Batches of Richmond River Rock oyster (RRRO) produced by NSW DPI have shown high levels of of QX disease survival. Prior studies on RRROs suggest that genetically they are classified as SROs but they appear to have developed significant resistance, presumably due to years of exposure to QX in the Richmond River estuary where the disease in enzootic. Preliminary experimental evidence suggests that RRROs display enhanced survival when exposed to QX disease, justifying their inclusion in the selective breeding program. Therefore, the second aim of this project is to assess QX survival of current RRRO families across multiple years of QX exposure and compare these results to other QX-resistant families in the breeding program. This information will be used in this project to formulate a breeding plan to create additional families using batches of RRROs that have been assessed for QX survival. Objectives: 1. To use previously generated genomic data from M. sydneyi to develop a multilocus sequence typing scheme for Marteilia strains from SROs 2. To screen samples collected from low-risk estuaries for M. sydneyi using qPCR 3. To compare Marteilia MLST profiles of qPCR positive samples from low-risk estuaries with those from M. sydneyi MLST profiles from high-risk estuaries. 4. To create 10 additional families (in addition to the families produced for the 2023 year class breeding run) that have a parent sourced from the Richmond River 5. To assess the QX survival of the 10 additional 2023 year class families as spat, adults and over two seasons at multiple sites 6. To generate QX spat survival estimated breeding values (EBVs) for families with RRRO parents produced for the YC2022 and 2023 year classes 7. To collect performance data (QX survival and growth) that allows comparison of RRROs and commercial families from the Sydney Rock Oyster breeding program over two consecutive seasons of QX disease. Read moreRead less
Assessment Of The Sensitivity Of Australia’s Aquatic Animal Disease Surveillance System Using Scenario Tree Modelling
Funder
Fisheries Research and Development Corporation
Funding Amount
$224,000.00
Summary
The sensitivity of an overall passive surveillance system is difficult to determine due to variability in factors such as disease characteristics, passive surveillance stakeholders and the likelihood that disease events will be reported and investigated. The WOAH Aquatic Animal Health Code also stipulates the primary evidence for historical freedom is passive surveillant information generated by a country’s early detection system that needs to be sufficiently sensitive.
Scenario tree m ....The sensitivity of an overall passive surveillance system is difficult to determine due to variability in factors such as disease characteristics, passive surveillance stakeholders and the likelihood that disease events will be reported and investigated. The WOAH Aquatic Animal Health Code also stipulates the primary evidence for historical freedom is passive surveillant information generated by a country’s early detection system that needs to be sufficiently sensitive.
Scenario tree modelling (STM) can be used to overcome those challenges. STM uses quantitative statistical methods to estimate the sensitivity of various components of the surveillance system (e.g. presentation of disease signs, disease recognition and reporting). These estimates can then be used to identify critical points in the system to which interventions can be targeted to improve the system. STM can be applied to any aquatic disease/industry of interest and there are some successful examples for terrestrial diseases/industries, both in Australia and overseas.
Two aquatic animal disease agents of trade and biosecurity significance, WSSV and megalocytiviruses, will be evaluated as case studies. These diseases are subject to import biosecurity measures and have significant production impacts, as they severely affect farmed and wild aquatic animal species that are valued by many stakeholders (e.g. aquaculture, capture fisheries, recreational fisheries and conservation groups). A sound STM assessment of each case study will support our early detection system through a quantitative evaluation of the speed of the detection, and improve our emergency disease response strategy by determining areas in our passive surveillance that, once strengthened, will provide a greater return on future investment.
As mentioned above, increasing the sensitivity of Australia’s passive surveillance is a national priority. This project is identified in AQUAPLAN 2022-2017 as Activity 3.3. The outcomes of this project are also used for other AQUAPLAN activities, National surveillance strategy (Activity 3.1) and Sector-specific surveillance plans (Activity 3.2). The data produced from this project will provide recommendations for various interventions to improve the overall performance of the passive surveillance system for the participating industries.
More broadly, the Fisheries Research and Development Corporation R&D Plan 2020-2025 identified building capability and capacity for biosecurity as a priority. In alignment with the R&D plan, successful outcomes of this project will improve understanding of disease transmission pathways which will enhance biosecurity practices. It will improve allocation of biosecurity resources (by identifying the most effective and cost-efficient way of investing resources in surveillance to get the best return), minimise biosecurity threats (by enhancing passive surveillance to accelerate an early detection) and improve market access for associated industry producers (by providing quantitative information on their passive surveillance sensitivity as a market access negotiation tool).
Objectives: 1. Quantitatively evaluate the sensitivity of Australia’s passive surveillance system for white spot disease 2. Quantitatively evaluate the sensitivity of Australia’s passive surveillance system for megalocytiviruses Read moreRead less