3 results

Assessment of gamma irradiation as a feasible method for treating prawns to inactivate White Spot Syndrome Virus

Project number: 2017-190
Project Status:
Completed
Budget expenditure: $220,000.00
Principal Investigator: Stephen J. Wesche
Organisation: Department of Primary Industries (QLD)
Project start/end date: 24 Feb 2018 - 30 May 2019
Contact:
FRDC
TAGS
White Spot Disease
Vaccine
Rac Qld
Disease
Agriculture
SPECIES
Prawns

Need

Achieving the mandated dose rate of 50 kGy for prawns harvested from the White Spot Disease control zone in SE QLD is proving to be problematic and industry are requesting a reduction in the permitted irradiation dose rate for prawns sourced from Moreton Bay to somewhere between 15 and 25 kGy. A reduction in treatment dose, if successful, would provide a viable option for industry to continue trade in uncooked prawns sourced from Moreton Bay.

There appears to be only three scientific papers relevant to the subject of using gamma irradiation for inactivation of WSSV (Heidareh et al. 2014, Kakoolaki et al. 2015, Motamedi-Sedeh et al. 2017). The studies were conducted with the aim of determining the doses required to inactivate the Iranian isolate of WSSV with gamma irradiation for the purposes of vaccinating cultured prawns. While the listed scientific papers suggest gamma irradiation at a dose of around 13-15 kGy is effective at inactivating WSSV, their experimental protocols and results are not clearly transferable. In these studies aliquots of free virus were exposed to different gamma irradiation doses. Irradiation of WSSV inside infected host tissues was not performed, and data on whether the surviving prawns were infected with WSSV were not presented. None of these papers are therefore directly applicable to the situation relating to irradiation treatment of WSSV in-situ inside infected prawns.

Given the absence of information on irradiation doses for inactivation of WSSV in the Department of Agriculture (2014) review document, and the absence of research in Australia or overseas to validate alternative irradiation doses that completely inactivate WSSV, new research is urgently required to determine the minimum safe irradiation dose for inactivation of WSSV in prawns with the results verified by controlled challenge trials in a bio-secure facility.

Objectives

1. To determine minimal effective dose of gamma irradiation to render WSSV non-infectious in prawns.

Final report

ISBN: 978-0-7345-0470-8
Authors: Stephen Wesche Kerrod Beattie Nicholas Moody
Final Report • 2021-07-01 • 2.54 MB
2017-190-DLD.pdf

Summary

White spot syndrome virus (WSSV) was detected in diseased farmed prawns by Biosecurity Queensland’s Biological  Sciences  Laboratory  and  confirmed  by  the  CSIRO  Australian  Centre  for  Diagnostic  Preparedness (ACDP) Fish Diseases Laboratory in November/December 2016. This exotic aquatic disease incursion resulted in the infection of all prawn farms, under production, along the Logan River, Queensland. Subsequent WSSV detections in prawns and crabs in northern Moreton Bay resulted in the issuing of a Movement Control Order and  subsequent  WSSV  biosecurity control order  under  the  Biosecurity  Act  2014,  which  prohibited  the movement of potential carriers (e.g. polychaete worms and decapod crustaceans) from Moreton Bay. These restrictions  included  wild  caught  prawns  from  Moreton  Bay  which  were  distributed  nationally  as  bait  for recreational  fishing.  Industry  established  protocols  to  treat  these  prawns,  for  distribution  as  bait,  using gamma  irradiation to  a  dose  of  50 kilogray (kGy).  However,  this  treatment  understandably  resulted  in increased costs of the final product, raising concerns that this would make imported commodity prawns a more likely source of bait for recreational fishing and consequently a biosecurity risk for introduction of exotic diseases.
 
The  primary  objective  of  this  project  was  to  determine whether gamma  irradiation treatment of WSSV infected prawns at a dose lower than 50 kGy would inactivate the virus as the bait wholesale industry indicated that a reduction in treatment dose to 25 kGy or lower would be required to provide meaningful cost benefits. Given  the  absence  of  information  on  irradiation  doses  for inactivation  of  WSSV, this collaborative project involving Department of Agriculture and Fisheries, Queensland, CSIRO ACDP, Steritech and industry, conducted research to evaluate the effect of reduced doses of gamma irradiation (10 kGy, 15 kGy, 20 kGy and 25 kGy) on inactivation of WSSV in infected prawns. 

Seafood CRC: controlling biofouling of pond aerators on marine prawn farms

Project number: 2011-734
Project Status:
Completed
Budget expenditure: $42,600.00
Principal Investigator: David Mann
Organisation: Department of Primary Industries (QLD)
Project start/end date: 23 Oct 2011 - 12 Oct 2013
Contact:
FRDC
TAGS
Sustainability
Recirculation System
Modelling
Innovation
Economic
SPECIES
Prawns

Need

Biofouling of aeration equipment is a significant farm management issue and production cost for Australian marine prawn farms. Defouling aeration equipment has a high labour demand and once fouled the energy efficiency of paddle-wheels and other aerating equipment can be markedly reduced, leading to elevated electricity costs and shorter equipment life. The estimated cost of biofouling is a minimum of $1,000 per hectare per crop when considering the additional labour, maintenance and electricity costs that it creates. This cost figure however does not include the impact of aerator fouling on prawn production levels which potentially could be far greater. The industry uses up to 10x aerators per hectare and they consume 70-80% of total farm energy use. It is estimated that at the peak of the production season around 6,000 2hp aerators are in use in ponds across the prawn industry alone.

Ensuring appropriate and timely aerator defouling is conducted is a significant farm issue. Manual defouling is one of the least desired tasks on the farms as it is dirty, laborious and workers are susceptible to multiple skin cuts that are prone to infection. Consequently it can be difficult to maintain staff to undertake this task for any length of time.
There is no data available on the impact of biofouling on the aeration efficiency, for example the oxygen transfer rate, and this information is critical to maximising benefit from mitigation strategies from both a practical and economic stand point.

The relevant industry body, the APFA through the R&D Committee, has assessed prevention of aerator biofouling as a priority issue and has recommended that the project commence as close as possible to the start of the current production season.

The proposed project falls within the Seafood CRC Theme – ‘Aquaculture Innovation’ as the objective is to improve production efficiency.

Objectives

1. Review biofouling control options and select those with greatest potential for application on prawn farms.
2. Assess the impact of aerator biofouling on prawn farms.
3. Transfer methods for implementing aerator biofouling controls to the prawn farming industry.
4. Evaluate selected biofouling control options under commercial conditions.

Final report

ISBN: 978-0-7345-0438-8
Author: David Mann
Final Report • 2013-11-01 • 1,006.29 KB
2011-734-DLD.pdf

Summary

Biofouling of aeration equipment is a significant farm management issue and production cost for Australian marine prawn farms. Defouling aeration equipment has a high labour demand and once fouled, the energy efficiency of paddle-wheels and other aerating equipment can be markedly reduced, leading to elevated electricity costs and shorter equipment life. The estimated cost of biofouling is a minimum of $1,000 per hectare per crop when considering the additional labour, maintenance and electricity costs that it creates.

The project was designed to assist the Australian prawn farming industry improve aeration efficiency through providing farms with new information pertinent to cost-efficient management of their aerator fleet. The project focussed on the impact of biofouling on aeration and measures to control its accumulation, though broader aspects of aeration were also considered.

On-farm monitoring of aerators determined a huge variation in aerator electrical performance within and among farms. Around 60% of the electrical use variability among paddlewheels is due to biofouling accumulation. This also means that around 40% of differences among paddlewheels is attributable to mechanical factors such as degree of wear and tear.

The overarching output from the research conducted under this project is an improved understanding and quantification of the problem of biofouling in the use of aerators in marine prawn ponds. Farms are under pressure to become increasingly efficient production systems and the information arising from this project will substantially contribute to the farm knowledge base drawn on to optimise strategies that reduce aerator fleet management costs.

Seafood CRC: prawn Industry black spot management: problem size and appropriate research

Project number: 2008-793
Project Status:
Completed
Budget expenditure: $35,280.61
Principal Investigator: Steve L. Slattery
Organisation: Department of Primary Industries (QLD)
Project start/end date: 23 Aug 2009 - 14 Jan 2010
Contact:
FRDC
TAGS
Workshop
Stakeholder
Innovation
Fishing Gear
Aquaculture
SPECIES
Prawns

Need

The ACPF workshop identified the R&D Priority 2 – Quality Assurance Action item "Black spot project to be developed by SARDI/QDPI, in conjunction with the CRC"

There is a need to better define the issues surrounding the effective use of metabisulphite and 4-hexylresorcinol by the Australian Prawn Industry, and to refine the associated research requirements. This relates specifically to the reduction in dip effectiveness with successive dips and the development of on-boat dip concentration meter – a “metameter”.

Objectives

1. To determine the significance of melanisation (black spot) in prawns to poducers and processors
2. To assess the need for further research on metabisulphite dipping and on the development of a dip meter
3. To assess the need for further research on 4-hexylresorcinol dipping.

Final report

ISBN: 978-0-7345-0411-1
Author: Steve Slattery and Dr. Richard Musgrove
Final Report • 2010-07-01 • 374.40 KB
2008-793-DLD.pdf

Summary

Summary:

The wild prawn capture industry is under increasing competition from imported and domestic aquaculture product. One problem facing the industry is the frequent occurrence of black pigment on the head and tail surfaces. This condition is known as black spot and can be prevented by treating the prawns with any of a number of different chemicals such as sodium metabisulphite.

This project aimed to 1) determine the significance of black spot in prawns to producers and processors 2) assess the need for further research on metabisulphite dipping and on the development of a dip meter and 3) assess the need for further research on 4-hexylresorcinol dipping.

A questionnaire was developed for industry members to complete. Interviews were conducted mostly in person or by phone with wild capture prawn industry members in various prawn fisheries around Australia. The results showed that the black spot issues varied with each fishery and that sodium metabisulphite was the chemical of choice for preventing black spot in the wild prawn fishing industry. There were many different ways this chemical was applied but the fishers did not always have the confidence that they were using it effectively.

The planned outcomes and benefits of this project were the identification of issues surrounding metabisulphite and 4-hexylresorcinol use and efficiency in the Australian Prawn fishery, including shelf-life and market perception. The survey identified that fishers are not sure which dip methods were effective for the various prawn fisheries. Research and training would provide them with the latest details on what chemical to use and how to use them. Additionally, easy to use sensor and test methods would ensure that sufficient residue of chemicals are present in the product so that it will be protected while being handled by retailers and consumers.

Keywords: prawns, industry development

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