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Pilchard mortality events in Australia and related world events

Project number: 1999-227

Project Status:

Completed

Budget expenditure: $59,025.44

Principal Investigator: Will Zacharin

Organisation: Department of Primary Industries and Regions South Australia (PIRSA)

Project start/end date: 20 Oct 1999 - 15 Apr 2004

Contact:

FRDC

TAGS

SPECIES

Need

The lack of a consolidated report on the 1995 pilchard mortality event hampered the Joint Pilchard Scientific Working Group in its investigation of the 1998 mortality event. It remains uncertain that the response to the 1998 mortality was efficient and it poses the risk that should another event occur in the future, it too will be met with a poorly-coordinated response. Such a response may not yield adequate data or appropriate data for researchers and fisheries managers around Australia. There is also a risk that scientific investigations may be duplicated, resulting in an inefficient use of industry and public resources.

The lack of a detailed analysis of the events of both 1995 and 1998 and of similar events in other parts of the world compound the difficulties involved in an evaluation of the implications of the mortalities to commercial fisheries and other species which depend wholly or in part on access to pilchards, eg sea lions and penguins.

Objectives

1. Prepare a comprehensive report of pilchard mortality events in Australian waters prior to 1995 and in waters world wide to the present time

2. Provide a summary of the 1995 pilchard mortality event

3. Prepare a comprehensive and competent technical report on the pilchard mortality event in 1998

4. Describe and evaluate the coordinating and managing approaches taken in 1995 and 1998 pilchard mortality events

5. Assess the implications of the pilchard mortality events

6. Evaluate the conclusions which can be drawn from various hypothese as to the cause, origin, trigger and epizootiology of the events

7. Assess options for managing future pilchard mortality events

Final report

ISBN: 0-759-01316-0

Author: Alexandra Gaut

Aquatic Animal Health Subprogram: generation of diagnostic reagents for pilchard herpes virus

Project number: 1999-226

Project Status:

Completed

Budget expenditure: $92,510.71

Principal Investigator: Bryan Eaton

Organisation: CSIRO Australian Animal Health Laboratory

Project start/end date: 20 Oct 1999 - 20 Feb 2003

Contact:

FRDC

TAGS

Need

Fletcher et al. (1997) suggest that the size of the outbreak in 1995 are consistent with infection of a naïve Australian pilchard population by an exotic herpes virus to which they had never previously been exposed. The use of imported pilchards to feed caged southern bluefin tuna in South Australian waters provides a potential source of such a virus. This is one explanation that highlights the need for a panel of diagnostic reagents and tests to screen imported pilchards for the presence of the herpes virus.

Herpes viruses are well-known to cause latent infections whose existence remains unknown until a predisposing environmental factor leads to their recrudescence. The factor most commonly recognised in virus reactivation is stress tha tcan itself be induced by a variety of stimuli including infection by another, unrelated microorganism. Fletcher et al. (1997) suggest that the severity of the disease observed in Australian pilchards and its emanation from a single geographic locality are not consistent with reactivation of a latent infection. However, we can not at this time rule out the possibility that the herpes virus is endemic and present in a latent state in Australian pilchards and is activated following infection by and, as yet, unidententified microorganism that spreads from a point source in South Australia. Imported pilchards may or may not be the source of such microorganism. There is a need to rule out involvement of other microorganisms in the death of the pilchards and to use the panel of diagnostic reagients and tools mentioned above to determine if Australian pilchards are latently infected by a herpes virus. Mortalities observed in the juvenile fish populuation in 1998 but not in 1995 raise questions about the role of herpes virus in the recent outbreak. There is a need to determine if herpes virus is present in dead juvenile fish.

Fletcher. W.J., Jones, B., Pearce, A.F. and Hosja (1997). Environmental and biological aspects of the mass mortality of pilchards (Autumn 1995) in Western Australia. Fisheries Research Report No 106, Fisheries Department of Western Australia.

Objectives

1. Prepare a panel of diagnostic reagents and a set of protocols to detect herpes virus in affected Australian pilchards

2. Provide reagents and protocols to State laboratories and offer training in their use to screen Australian and imported pilchards for the presence of the virus

3. Develop cultured pilchard cell lines and use sesceptible cells to grow pilchard herpes virus.

4. Investigate the cause of juvenile pilchard deaths by pathological and ultrastructural examination of juvenile fish.

Final report

Author: Bryan Eaton

The development of a model of the spread of the pilchard fish kill events in southern Australian waters

Project number: 1999-225

Project Status:

Completed

Budget expenditure: $46,251.00

Principal Investigator: Alexander Murray

Organisation: CSIRO Oceans and Atmosphere Hobart

Project start/end date: 28 Jun 1999 - 16 May 2001

Contact:

FRDC

TAGS

SPECIES

Need

The mass mortality events are very economically and ecologically damaging. Economic damage occurs acutely in the short-term due to the need to close the fishery during events and damage also occurs in the longer term owing to the removal of large numbers of fish during the event.

No model exists of the spatial propogation of a viral epidemic in an exploited fish population, we will derive such a model. This model will be aimed less at predicting the spread of a particular mass mortality event and more at the understanding of the dynamics of the event. Using the model we will be able to assess hypothesises concerning the factors which control the mass mortality and hence focus future study on the most sensitive processes. The model will also show the conditions under which these events may recur. We will also be able to assess the potential for management intervation to halt an ongoing epidemic or prevent further outbreaks. The model will also integrate all the aspects of the spread of the mass mortality events, showing linkages within the existing data and showing those areas for which adaquate data is lacking.

It should also be noted that damaging epidemics among wild caught and farmed marine fisheries are not infrequent and that modified versions of the model may have future applications to other fisheries.

Objectives

1. We will construct a 1-D SIR (Susceptible, Infected, Removed) model of the spread of the pilchard mass mortality events of 1995 and 1998/9

2. We will analyse the effect of different modes of local transmission on the mass mortality's dynamics.

3. We will produce a literature review of similar mass mortalities and the modelling approaches used to analyse them.

4. We will refine the SIR model to include different transmission process functions and data obtained by other pilchard mortality study projects, in particular the Fisheries WA lead study on viral transmission.

5. We will review the observations, including those obtained in concurrent studies, to provide the tightest possible constraints on the ranges of model parameters.

6. We will analyse the effects of fisheries management strategies on pathogen transmission, in particular we will test the viability of a 'fire break' policy.

7. We will construct a simple model of the recovery of the fishery to investigate the period required for the stocks to become vulnerable to renewed mortality.

8. We will develop a Graphical User Interface (GUI) to display the local and geographical spread of pathogens.

9. We will produce an initial report detailing the approaches used both by us and other modellers of epidemics.

10. We will produce a final report detailing the final form of the model produced and incorporating analysis of model structure, parameters and results.

11. We will present this work at a nationally significant scientific meeting in 2000.

Final report

ISBN: 0-643-06233-5

Author: Alexander Murray

Developing techniques for enhancing prawn fisheries, with a focus on brown tiger prawns (Penaeus esculentus) in Exmouth Gulf

Project number: 1999-222

Project Status:

Completed

Budget expenditure: $612,622.32

Principal Investigator: Neil Loneragan

Organisation: CSIRO Oceans and Atmosphere Hobart

Project start/end date: 26 Jun 2000 - 1 Feb 2006

Contact:

FRDC

SPECIES

Tiger Prawns

Need

Prawn fisheries throughout Australia are intensively fished and some have shown signs of overfishing. In some cases, the current stocks of prawns are now lower than those which would produce maximum yields. The enhancement of Australian penaeid prawn fisheries has the potential to be a useful management tool to increase fishery yields, rebuild over-exploited stocks, and reduce fluctuations in catch due to variable recruitment. Stock enhancement also has the ability to improve the management of fisheries by collecting more precise information about the biological characteristics of the stock (e.g. survival and growth, production in nursery grounds, migration pathways and factors affecting fluctuation in populations).

Prawn stocks can vary greatly from year to year because of environmental fluctuations and this leads to highly variable catches. Fishery managers must therefore adopt conservative harvest strategies to prevent fishers from reducing stocks to dangerous levels in years when recruitment is low. However, the harvesting and processing sector tend to be on average, over-capitalised, in order to cope with years of high recruitment. Enhancement of prawn stocks through releasing juvenile prawns has the potential to reduce fluctuations in stocks. It provides a possible way of adjusting the catching and processing capacity to more stable levels of prawn stocks, which would reduce the need for over-capitalisation.

For stock enhancement to be successful, the biology and ecology of the target animal must be thoroughly understood (including the production of the postlarvae/juveniles, environmental requirements, carrying capacity, and all factors that contribute to mortality), and methods must be available to monitor and assess the success of the releases. Much ecological information for stock enhancement is now available for many commercially important species of penaeid prawn in Australia, and novel approaches to tagging prawns (e.g. stable isotopes, rare alleles and reporter genes), release strategies, and assessment of carrying capacity are being developed. However, the utility of stock enhancement as a management tool for Australian fisheries, particularly prawns, has not been assessed.

The feasibility study of Exmouth Gulf has shown that it is an ideal fishery in which to evaluate the effectiveness of stock enhancement for Australian prawn fisheries. It also found that the enhancement of tiger prawns in Exmouth Gulf is potentially viable and that the risks of introducing disease and affecting the genetic composition of the wild population are likely to be low and manageable. Before proceeding to commercial scale releases, it is important to establish techniques for such releases on a smaller scale. Prawn fisheries throughout Australia are intensively fished and some have shown signs of overfishing. In some cases, the current stocks of prawns are now lower than those which would produce maximum yields. The enhancement of Australian penaeid prawn fisheries has the potential to be a useful management tool to increase fishery yields, rebuild over-exploited stocks, and reduce fluctuations in catch due to variable recruitment. Stock enhancement also has the ability to improve the management of fisheries by collecting more precise information about the biological characteristics of the stock (e.g. survival and growth, production in nursery grounds, migration pathways and factors affecting fluctuation in populations).

The farm production of prawns in arid environments, where evapouration rates are high and freshwater is scarce, has not been attempted in Australia. However, there are proposals for this to take place in the Exmouth Gulf region (Cape Sea Farm). The results from our proposed research in Exmouth Gulf will provide new information on the production of juvenile prawns at much higher densities than previously attempted in Australia. We anticipate the development of successful techniques that would be suitable for a broad range of environments, apart from the arid conditions at Exmouth Gulf.

The M.G. Kailis Group of companies has demonstrated it’s commitment to this project by advancing funds ($23, 000) to commence work on the project before July 1999. The beneficiaries of stock enhancement would be expected to contribute to the costs of research and monitoring, and ultimately pay for the enhancement at commercial scales. Therefore, stock enhancement must be cost-effective and a cost-benefit analysis using a bioeconomic model, is an essential part of any enhancement project. The bioeconomic model developed during the feasibility study (FRDC 98/222) will be revised as the results of the current proposal become available. It will then be used to assess the commercial viability of large scale enhancement and optimise the design of the experimental enhancement (Stage 3). The results of the feasibility study suggest that it would be possible to enhance the tiger prawn fishery in Exmouth Gulf by about 100 t with releases of about 7 to 10 million juveniles.

Objectives

1. Minimise the costs of producing large numbers of juvenile prawns through research on techniques to intensively grow larvae to juvenile prawns (1 g), and developing methods of harvest, transport and release

2. Maximise the possibility of the success of releasing juvenile prawns in the environment by surveying the critical nursery habitats of brown tiger prawns in Exmouth Gulf (including the juvenile prawns and their predators)

3. Ensure that the cost and success of prawn enhancement can be rigorously evaluated by developing release protocols and monitoring strategies, and by refining the bioeconomic model developed in Stage 1

4. Minimise the risks of large changes in the genetic composition of the tiger prawn stocks and introducing disease to the wild population

Final report

Final Report • 2017-09-29 • 4.42 MB

PROJECT NUMBER • 1999-217

PROJECT STATUS:

COMPLETED

Stable isotope tracing of the contribution of seagrass production to subtropical fisheries species occurring outside seagrass areas

Results from this project affect the relative importance coastal managers will place on different estuarine habitats. Until now primary production from mangrove forests has been ranked highly for its presumed contribution to fisheries species occurring seaward of mangroves. This project...

ORGANISATION:

Griffith University Nathan Campus

TAGS

Sustainability

Offshore

Laboratory Procedures

SPECIES

Links between seagrass habitats, piscivorous fishes and their fish prey

Project number: 1999-215

Project Status:

Completed

Budget expenditure: $35,000.00

Principal Investigator: Michael J. Keough

Organisation: University of Melbourne

Project start/end date: 28 Nov 1999 - 1 Jul 2001

Contact:

FRDC

TAGS

SPECIES

Need

The FRDC recently commissioned a review of the importance of seagrass habitats to fisheries sustainability in which Connolly et al. (in press) identified the "gaps in our understanding and future research needs" and made "recommendations for future research" (In Press: Report No. 98/223).

Connolly et al. (in press; point seven, section 6.4. Gaps in our understanding and future research needs) suggest that the nature of the links between fish and processes such as "feeding, protection from predators and amelioration of physical disturbance" within seagrass habitats are "poorly known". "Hard data on links between seagrass and fishery species are needed urgently" (Connolly et al., in press; section 6.5. Summary of recommendations for future research). Connolly et al. (in press) identify a need for "small scale manipulative experiments", "conducted over a large enough spatial scale" so that we can increase our capacity "to predict the effects of changes in seagrass extent on commercial fish". It is important to understand the importance of "processes linking seagrass with fish" in order to be "able to predict the effects of seagrass changes on fisheries" (Connolly et al., in press; section 6.5. Summary of recommendations for future research).

Connolly et al. (in press) also suggest that "dietary and isotope studies of piscivorous fish are required " because the role of small, non-commercial species in food chains for commercial species is only known in localized areas" (section 6.4. Gaps in our understanding and future research needs, point 12, section 6.5. Summary of recommendations for future research). Isotope studies will also address the need for research which compares the ecology (e.g. extent of assimilation of food from seagrass beds) of fishery species that spend all or only part of their life associated with seagrass" (point 3, section 6.5. Summary of recommendations for future research).

Cappo et al. (1998) reiterate Connolly et al. (in press) in suggesting that information is needed about the role of predation in structuring fish assemblages within seagrass beds. "There is a surprising lack of basic life-history information for most of the major fishery species in Australia", and "consequently a paucity of information on "critical" habitat requirements and processes such as post-recruitment mortality" (section 1.3.4 Lack of knowledge of links between life-histories and habitats).

Objectives

1. Quantify the contribution of fishes, which may or may not be economically valuable, within seagrass beds to the dietary composition of piscivorous fish, some of which e.g. Yank flathead (Platycephalus speculator), Rock flathead (Platycephalus laevigatus) and Australian Salmon (Arripis sp.) form commercially valuable fisheries.

2. Identify how piscivorous fish influence the abundance of juvenile fish within seagrass beds, some of which, e.g. the King George whiting, form valuable commercial and recreational fisheries.

3. Describe and quantify, using carbon and nitrogen isotope analysis, the strength of links between seagrass beds, juvenile fish inhabitants and their fish predators.

Final report

Author: Dr Jeremy S. Hindell Dr Michael J. Keough Dr Gregory P. Jenkins

1999-215-DLD.pdf

Summary

This project has increased our understanding of the importance of seagrass habitats to larger, commercially valuable, species of fish by combining experimental and correlative scientific principles. We found that many small fish use seagrass habitats for nutrition and to avoid predation by large predatory fish. Some of these small fish also form important parts of the diets of commercially important species, such as Australian Salmon. The importance of predatory fish varied, however, from site to site, suggesting that seagrass habitats may need to be evaluated individually. The primary outcomes of this study will be important in identifying seagrass habitats that are especially valuable as feeding and nursey sites for commercially valuable fish in Port Phillip Bay. The type of information presented in this study will help understand how and why various nearshore marine habitats may be used by various species of fish, and how best to ensure their protection and future sustainability.

Final Report • 2017-09-29 • 4.42 MB

1999-215-DLD.pdf

Summary

The effect of barramundi Nodavirus on important freshwater fishes

Project number: 1999-205

Project Status:

Completed

Budget expenditure: $149,525.00

Principal Investigator: Ian Anderson

Organisation: Department of Primary Industries (QLD)

Project start/end date: 11 Jul 1999 - 18 Jan 2005

Contact:

FRDC

TAGS

SPECIES

Need

Susceptibility of freshwater fishes to barramundi nodavirus.

- There is a need to address concerns about the risk of possible lethal transmission of barramundi nodavirus to freshwater fishes already under threat in their natural habitat.
- Important freshwater fishes will be exposed to the nodavirus from cell cultures to determine their susceptibility.
- By using the OVL isolation facility in Townsville, well outside the Murray-Darling region, there is minimal risk to the natural fish populations.
- Confirmation that barramundi nodavirus can cause lethal infections in freshwater fishes will strengthen the application of strict licence conditions on barramundi farming in southern Australia.
- Confirmation that barramundi nodavirus does not affect freshwater fishes will possibly allow expansion of the barramundi farming into regions needing new sustainable economic development.

A barramundi infection model.

- To establish a realistic virus dose and route of infection for the challenge trials, an infection model using barramundi will be developed.
- OVL has ready access to barramundi larvae and fry of all ages.
- The model is also necessary to help quantify the effect of virus exposure to disinfectants and different environmental conditions.

What is the viability of barramundi nodavirus?

- Fish health management requires good information on how to effectively decontaminate facilities following outbreaks of VNN.
- Knowledge of the persistence of barramundi nodavirus in the environment will allow fisheries managers to decide on effective conditions for barramundi farming licences that minimise the risk of transferring virus outside the culture facility.

Sensitivity of the cell culture isolation system.

- While sensitive detection tests are available, the barramundi cell line offers a more practical diagnostic method that can be used by any laboratory with cell culture/ virology capability.
- An evaluation of the cell culture isolation system’s ability to detect virus in carrier (no disease) fish, and standardization of the cell culture presentation, is required before the method can be recommended.

Objectives

1. To establish a standard infection model for barramundi nodavirus in barramundi larvae and fry.

2. To more accurately define the range of fish species that can actually be infected by barramundi nodavirus, the effect of the virus on these fishes and the infectious dose.

3. To determine the sensitivity of the barramundi nodavirus to a range of environmental conditions and to disinfectants.

4. To evaluate the cell culture isolation system as a method of detecting nodavirus in asymptomatic carrier fish.

Final report

ISBN: 0 7345 0295 8

Author: Ian Anderson

Summary

This project has confirmed the knowledge that management of barramundi translocations outside their natural range requires fisheries authorities take into account the risk that barramundi nodavirus may lethally infect native freshwater fishes. The project has shown barramundi nodavirus can multiply and spread throughout the body of freshwater fishes, and that the spread of infection from fish to fish is a possibility in freshwater.

The project has created knowledge on the Australian application of a sensitive molecular detection test for nodavirus in healthy fishes. This knowledge has lead to industry and government support for further research on diagnostic test development for nodaviruses which will lead to a national Standard Diagnostic Procedure. Further, this knowledge has led the barramundi hatchery sector to support a research project applying the molecular detection test to screen captive barramundi breeders for nodavirus with the aim to produce nodavirus-free barramundi fry.

Summary

Summary

Summary

Summary

Summary

Rock Lobster Post Harvest Subprogram: rock lobster autopsy manual

Project number: 1999-202

Project Status:

Completed

Budget expenditure: $34,490.00

Principal Investigator: Louis Evans

Organisation: Curtin University

Project start/end date: 5 Sep 1999 - 7 Jan 2005

Contact:

FRDC

TAGS

SPECIES

Southern Rock Lobster

Tropical Rock Lobsters

Need

With the increasing interest of lobster processors to keep lobsters for extended time periods prior to sale, and of the lobster industry in general in lobster aquaculture, there is a need for information on lobster health management. It is well recognised that a range of diseases and conditions occur in wildstock lobsters (Evans & Brock, 1994) and that health management problems are likely to be encountered in enhancement and aquaculture of spiny rock lobsters. In order to prevent disease outbreaks, or effectively deal with such conditions should they occur, reference material is required for use by personnel involved in enhancement and aquaculture programs. At present there is very little published information on health management of spiny rock lobsters held in captivity. A valuable first step to address this need would be the publication of a manual describing the approach to be used to investigate lobster health problems along with photographic material on disease conditions likely to occur in captive lobsters. Such a manual would be used by operators of holding/culture facilities or by fish health personnel involved in disease investigations. An autopsy manual with illustrations of common parasitic and disease conditions found in Australian lobsters would also be of interest to lobster fishers.

One of the conditions most likely to occur in captive lobsters is bacterial infections by opportunistic pathogens, those bacteria which are ubiquitous and only cause disease when the lobster is weak or when a particularly virulent strain of bacteria is encountered. It is well known that crustaceans can harbour bacteria in their body fluids apparently without causing the animal any harm. Whether the presence of bacteria in the hemolymph of lobsters is indicative of the likelihood of disease outbreaks and future stock mortality is not well understood. In addition to publication of a lobster autopsy manual, this project will provide information which will contribute to understanding and managing bacterial infections in captive lobsters. The information will be obtained from bacterial challenge experiments conducted on lobsters held in aquaria in the laboratory. These experiments will also provide descriptive material for inclusion in the lobster autopsy manual.

The techniques and information described in the autopsy manual can be used to investigate possible problems arising from mortalities of unknown causes, as well provide fishers and factory staff with a reference to consult when lobsters with health problems are encountered during fishing and processing. The autopsy manual will be of value to fish pathologists for use in disease diagnosis as well as to fishers, fish processors and researchers.
Evans L.H. & Brock J.A. 1994. Diseases on spiny lobsters. In "Spiny Lobster Management (Ed. B.F. Phillips, J.S. Cobb & J. Kittaka) pp 461-472. Blackwell Scientific Publications.

The autopsy manual will include details of approach to be followed in conducting an autopsy on a lobster, descriptions of assay methodology, normal ranges for selected immune and physiological parameters, expected deviations from normal in lobsters subjected to excessive postharvest stressors, photographs of gross and microscopic lesions and descriptions of pathogens observed in apparently healthy lobsters as well as in moribund lobsters.

Objectives

1. The publication of an autopsy manual to be used in the lobster industry. The manual will include details of approach to be followed in conducting an autopsy on a lobster, descriptions of assay methodology, normal ranges for selected immune and physiological parameters, expected deviations from normal in lobsters subjected to excessive post harvest stressors, photographs of gross and microscopic lesions and descriptions of pathogens observed in apparently healthy lobsters as well as in moribund lobsters.

Final report

Author: Louis Evans

Summary

Data and information on lobster host defense responses, disease conditions, dissection procedures and laboratory investigation methods were obtained from the FRDC projects 94/134. 07, 96/344, 96/345 and 98/302 and other sources and collated into a publication on the nature and investigation of lobster diseases. Contributions to the book were sought from lobster researchers and fish health personnel from Australia and New Zealand. Following collation and editorial review, the individual chapters were circulated for review and comment. The publication, titled ‘A review of lobster diseases, their investigation and pre-disposing factors’ was published in 2003 and contains the following chapters:

Lobster health and disease concepts (Louis Evans)
Responses to environmental stressors (Louis Evans)
Lobster autopsy procedure and immune assay methods (Louis Evans, Seema Fotedar and Anne Barnes)
Collection and handling of blood samples from spiny lobsters (Brian Paterson, Patrick Spanoghe and Glen Davidson)
Reagents and methodology for immune function tests (Louis Evans & Seema Fotedar)
Review of adult lobster diseases (Frances Stephens, Louis Evans, Seema Fotedar and Brian Jones)
Disease conditions of larval and juvenile spiny lobsters (Ben Diggles and Judith Handlinger)
Biosecurity and food safety issues (Frances Stephens)

Summary

Lobster health and disease concepts (Louis Evans)
Responses to environmental stressors (Louis Evans)
Lobster autopsy procedure and immune assay methods (Louis Evans, Seema Fotedar and Anne Barnes)
Collection and handling of blood samples from spiny lobsters (Brian Paterson, Patrick Spanoghe and Glen Davidson)
Reagents and methodology for immune function tests (Louis Evans & Seema Fotedar)
Review of adult lobster diseases (Frances Stephens, Louis Evans, Seema Fotedar and Brian Jones)
Disease conditions of larval and juvenile spiny lobsters (Ben Diggles and Judith Handlinger)
Biosecurity and food safety issues (Frances Stephens)

Summary

Lobster health and disease concepts (Louis Evans)
Responses to environmental stressors (Louis Evans)
Lobster autopsy procedure and immune assay methods (Louis Evans, Seema Fotedar and Anne Barnes)
Collection and handling of blood samples from spiny lobsters (Brian Paterson, Patrick Spanoghe and Glen Davidson)
Reagents and methodology for immune function tests (Louis Evans & Seema Fotedar)
Review of adult lobster diseases (Frances Stephens, Louis Evans, Seema Fotedar and Brian Jones)
Disease conditions of larval and juvenile spiny lobsters (Ben Diggles and Judith Handlinger)
Biosecurity and food safety issues (Frances Stephens)

Summary

Lobster health and disease concepts (Louis Evans)
Responses to environmental stressors (Louis Evans)
Lobster autopsy procedure and immune assay methods (Louis Evans, Seema Fotedar and Anne Barnes)
Collection and handling of blood samples from spiny lobsters (Brian Paterson, Patrick Spanoghe and Glen Davidson)
Reagents and methodology for immune function tests (Louis Evans & Seema Fotedar)
Review of adult lobster diseases (Frances Stephens, Louis Evans, Seema Fotedar and Brian Jones)
Disease conditions of larval and juvenile spiny lobsters (Ben Diggles and Judith Handlinger)
Biosecurity and food safety issues (Frances Stephens)

Summary

Lobster health and disease concepts (Louis Evans)
Responses to environmental stressors (Louis Evans)
Lobster autopsy procedure and immune assay methods (Louis Evans, Seema Fotedar and Anne Barnes)
Collection and handling of blood samples from spiny lobsters (Brian Paterson, Patrick Spanoghe and Glen Davidson)
Reagents and methodology for immune function tests (Louis Evans & Seema Fotedar)
Review of adult lobster diseases (Frances Stephens, Louis Evans, Seema Fotedar and Brian Jones)
Disease conditions of larval and juvenile spiny lobsters (Ben Diggles and Judith Handlinger)
Biosecurity and food safety issues (Frances Stephens)

Summary

Lobster health and disease concepts (Louis Evans)
Responses to environmental stressors (Louis Evans)
Lobster autopsy procedure and immune assay methods (Louis Evans, Seema Fotedar and Anne Barnes)
Collection and handling of blood samples from spiny lobsters (Brian Paterson, Patrick Spanoghe and Glen Davidson)
Reagents and methodology for immune function tests (Louis Evans & Seema Fotedar)
Review of adult lobster diseases (Frances Stephens, Louis Evans, Seema Fotedar and Brian Jones)
Disease conditions of larval and juvenile spiny lobsters (Ben Diggles and Judith Handlinger)
Biosecurity and food safety issues (Frances Stephens)

Aquafin CRC - Atlantic Salmon Aquaculture Subprogram: development of selective enrichment culture-polymerase chain reaction (SEC-PCR) for the detection of bacterial pathogens in covertly infected farmed salmonid fish

Project number: 1999-201

Project Status:

Completed

Budget expenditure: $155,784.00

Principal Investigator: Jeremy Carson

Organisation: University of Tasmania (UTAS)

Project start/end date: 19 Sep 1999 - 30 Jun 2003

Contact:

FRDC

TAGS

SPECIES

Need

The ability to detect infected animals is an essential requirement in animal health monitoring and surveillance. A major problem of testing farmed and wild fish is the absence of simple diagnostic tests for the detection of asymptomatic carrier fish. Where tests are available, they are resource intensive and time consuming such as the heat+corticosteroid stress test for furunculosis in salmonids. This test is used for disease control measures in eastern Canada and has been instrumental in limiting spread of furunculosis to sea cage farms (Olivier 1992). Active surveillance of animal populations is considered an important approach in animal health monitoring (Stark 1996) and is of particular relevance with publication by the Office International des Epizooties of its guidelines in the International Aquatic Animal Health Code (Anon 1997) for defining disease-free status.

Demonstration of freedom from disease, both covert and overt, within a region or a country, can be an asset when selling live and uncooked product in markets overseas. As global trade develops, Australia will need to demonstrate freedom from disease not just as a marketing strategy but as an essential requirement of trade and as a means of protecting or limiting the spread of disease.

This project aims to develop a hybrid technology derived from the food industry. It will require adaptation and refinement for use with fish pathogens and development of test protocols for screening adequate numbers of fish. The use of specialised enrichment culture media with the sensitive and specific techniques of PCR should provide a useful and sensitive tool in active surveillance of fish populations and fish products. This technology will also have application in screening ornamental fish entering Australia as well as uncooked fish products.

Detection of bacterial pathogens using immunological markers or DNA are termed proxy tests since the presence of the pathogen is inferred. Proxy tests pose two major problems: firstly what is the relationship of the proxy measure to the intact target pathogen and secondly, what is the biological significance of the proxy test? Validation of proxy tests is a recognised problem that if unresolved can seriously restrict the use of such tests (Hiney 1997). The proposed project solves many of these issues of validation: the primary test requires amplification of the target pathogen by culture and hence is not a proxy test. Detection of the target pathogen after culture utilises a secondary proxy test but it can be internally validated by secondary culture as required. The test system will be evaluated against farmed populations of fish to determine the significance of findings, a pre-requisite for external validation. Correlations of this type have not been undertaken previously and the strategies proposed in this project represent a realistic attempt to convert bench tests into practical and robust diagnostic tools.

References:

Anon (1997) International Aquatic Animal Health Code. 2nd edit. Office International des Epizooties, Paris.
Hiney M. (1997) How to test a test: methods of field validation for non-culture based detection techniques. Bull. Eur. Ass. Fish Path. 17:245-250
Olivier G (1992) Furunculosis in the Atlantic provinces: an overview. Bull. Aquacul. Assoc. Canada 92-1: 4-10.
Stark K D C (1996) Animal health monitoring and surveillance in Switzerland. Aus. Vet. J. 73:96-97.

Objectives

1. Develop a procedure for extracting bacterial DNA from the selective enrichment media that is suitable for the PCR process and is suitable for processing multiple samples.

2. Determine optimum conditions for the PCR test to maximise specificity and sensitivity of the procedure.

3. Develop a test procedure based on immuno-ELISA capture that will verify any positive PCR reactions using a secondary confirmatory gene probe and is suitable for testing multiple samples.

4. Optimise the PCR conditions to incorporate a PCR protection system to protect tests against false positive reactions arising from contamination.

5. Optimise the culture conditions and PCR detection process to ensure the minimum test time between sample collection and test result.

6. Test populations of salmonids with the optimised SEC-PCR system to verify test performance and obtain baseline data on carrier prevalence.

Final report

Author: Jeremy Carson and Teresa Wilson

Summary

Bacterial disease is a major cause of stock loss in aquaculture. The severity of infection may range from acute to chronic through to benign. This latter condition, termed covert infection, is insidious, as fish may appear to be outwardly healthy but during periods of stress, these carriers may breakdown leading to spread of infection and development of a disease outbreak.

Several bacterial pathogens, known to exist in Australia and the cause of significant disease episodes in Atlantic salmon and rainbow trout, can cause covert infections including: atypical Aeromonas salmonicida, Lactococcus garvieae, Tenacibaculum maritimum and Yersinia ruckeri.

Early detection of covertly infected fish is considered desirable as it provides a means of determining a suitable disease control strategy such as imposing movement restrictions to prevent the spread of disease, changing management practices to avoid stress or determining the spread of disease in a population at risk of infection. The standard method for identifying carriers is to stress a cohort of fish using a combination of heat andi mmunosuppression to force covertly infected fish to breakdown with disease. This form of testing is undesirable for animal welfare considerations, is difficult to accomplish and takes over three weeks to generate results.

Summary

Summary

Summary

Summary