8 results

National Pacific Oyster Breeding Program: Completing POMS Resistance in Spat and Transition to Selection for Traditional Commercial Traits

Project number: 2020-096
Project Status:
Completed
Budget expenditure: $177,609.59
Principal Investigator: Andrew Trotter
Organisation: University of Tasmania (UTAS)
Project start/end date: 21 Jan 2021 - 29 Jul 2022
Contact:
FRDC

Need

Commercial in confidence. To know more about this project please contact FRDC.

Objectives

Commercial in confidence

Future oysters CRC-P: Advanced understanding of POMS to guide farm management decisions in Tasmania

Project number: 2016-804
Project Status:
Completed
Budget expenditure: $694,773.00
Principal Investigator: Christine D. Crawford
Organisation: University of Tasmania (UTAS)
Project start/end date: 2 Jan 2017 - 29 Jun 2019
Contact:
FRDC

Need

The OsHv-1 virus was first detected in Tasmanian oysters in January 2016 with massive mortality of oysters on farms in several major oyster growing areas, including Pittwater, Pipeclay Lagoon, Blackman Bay and Little Swanport. In other regions such as Bruny Island and Great Swanport the virus was found in oysters but mortalities were low. Reasons for these differences between oyster growing areas are unknown and there is an urgent need for Tasmanian oyster farmers to have region and site specific information on the period of infection of the virus in Tasmania and to better understand the POMS virus dynamics, leading to the development of a predictive framework and early warning for oyster farmers of POMS disease outbreaks. Oyster farmers in Tasmania also desperately need support to develop farm management techniques that enable them to operate successfully in POMS infected areas, especially during the next few years while selective breeding for POMS resistance is being developed.

Objectives

1. To determine i) the periodicity of infection of OsHV-1 virus in Tasmania, ii) advance the understanding of the drivers of POMS disease outbreaks, and iii) develop a predictive framework that allows the Tasmanian oyster industry to forecast danger periods for POMS.
2. To develop farm husbandry and handling protocols to maximise oyster production in POMS infected growing areas by investigating oyster survival in relation to: i) subtidal versus intertidal culture, ii) high water flow areas compared with low flow, iii) reduced handling, iv) size and timing of spat onto growout farms, and v) stocking density.
3. To enhance commercial production of Pacific oysters in a POMS infected area through analysis of past farm production and management records, and a contemporary study of farm production systems and oyster survival.

Final report

ISBN: Print: 978-1-922352-09-5 Electronic: 978-1-922352-10-1
Authors: Christine Crawford Sarah Ugalde
Final Report • 2019-08-01 • 4.07 MB
2016-804-DLD.pdf

Summary

The objectives of our research have been to determine the high-risk periods for POMS infection and to develop a predictive framework so that the farmers can forecast danger periods for POMS. This includes developing a better understanding of where the virus exists in the environment and the factors that drive POMS disease outbreaks. We also aimed to work with the oyster industry to develop farm husbandry and handling protocols that maximise oyster production in POMS infected growing areas. Additionally, we surveyed the oyster farmers affected by POMS to get an overall view of the impact of POMS, especially socio-economic aspects.
 
Our research supports other studies that warm water temperature is a major driver of POMS outbreaks, with temperatures in south-eastern Tasmanian growing areas of 19 °C and above for around one week providing a high risk for a disease event to occur. The risk period for POMS disease outbreaks ranges from mid-November to late March. Other environmental factors likely to be important include water movements and density of infected oysters in a water body. Growing areas with extensive intertidal flats and poor water circulation, such as Pittwater, or with a high biomass of farmed and feral oysters in a relatively small area, such as Pipe Clay Lagoon, have shown to be more susceptible to POMS disease than the other farming areas. As feral oysters in Pipe Clay had a relatively high prevalence of OsHV-1, they may be contributing to the reservoir host of the virus.
 
Studies on farming practices conducted in close collaboration with oyster growers suggest that density of oysters in culture containers has limited effect on mortality rates, and that some
handling is required during the POMS season to reduce biofouling and maintain stocking densities conducive to good growth and survival. Younger and smaller oysters are more susceptible to infection that larger and older juvenile and adult oysters. For oysters of the same age cohort, fast growers had higher mortalities than slow growers.
 
The surveys of oyster growers on the impacts of POMS on their farming operations has shown that mortalities from POMS have rapidly declined from an average of 67% of stock in 2016 to 9% in 2018/19. Changes to farming practices that have occurred during this time include a large increase in stock selectively bred for POMS disease resistance, reduced and more careful handling of oysters during the summer POMS season, selling a higher percentage of stock before the POMS high risk period, and purchasing spat when temperatures are declining.
Environment
PROJECT NUMBER • 2014-032
PROJECT STATUS:
COMPLETED

Improved understanding of Tasmanian harmful algal blooms and biotoxin events to support seafood risk management

The 2012 Tasmanian biotoxin event represents a paradigm shift for seafood risk management in Tasmania and Australia as a whole. The causative dinoflagellates are extremely difficult to identify by routine plankton monitoring, and are toxic at very low cell concentrations (50-100 cells/L). Sampling...
ORGANISATION:
University of Tasmania (UTAS)

Seafood CRC: protecting the safety and quality of Australian oysters with integrated predictive tools

Project number: 2007-719
Project Status:
Completed
Budget expenditure: $57,723.00
Principal Investigator: Mark Tamplin
Organisation: University of Tasmania (UTAS)
Project start/end date: 30 Dec 2007 - 30 Jun 2009
Contact:
FRDC

Need

Molluscan shellfish are high-valued seafood products that require careful supply chain management to guarantee both product safety and quality. Together, storage time and temperature exert the greatest influence on microbial food safety and must be controlled during oyster production, processing, transport and storage. The microbiological safety status of oysters is initially controlled by testing, monitoring and classifying growing waters as safe for harvest. As stated above, Vibrio species are a natural component of marine and estuarine environments, unlike faecal bacteria which are typically introduced into growing waters by land run-off. Consequently, it is prudent to assume that all live shellfish may potentially contain naturally-occurring Vibrio spp. Of these, V. parahaemolyticus is the most common species which can cause human infection if present in high numbers. This risk can be controlled by proper cold chain management, but may reach unacceptable levels with the loss of temperature control. This is particularly a concern for the oyster producer who has carefully managed the growth and characteristics of the oyster to yield the highest value, and who then looses control of value and the brand due to mismanagement down-stream. Even when human illness is an isolated event, the negative consequences can easily be spread across the entire industry. Thus, a proactive strategy is required to control and predict risk, with added benefits for also maintaining product quality. This can be achieved, in part, by producing a tool (proposed Refrigeration Index) that allows companies to monitor real-time conditions of the cold chain and thus the safety and quality of a highly-valued seafood product. The likely impact will include: 1) improved product safety, 2) an optimised cold chain, 3) higher product quality, 4) greater access to export markets and 5) a more cooperative regulatory environment.

Objectives

1. To produce a validated and robust Vibrio parahaemolyticus model that is approved by Australian and international regulatory bodies to manage the live oyster cold chain, control the risk of Vibrio diseases and provide greater access to national and international markets.
Environment
PROJECT NUMBER • 2005-072
PROJECT STATUS:
COMPLETED

Water use across a catchment and effects on estuarine health and productivity

This research has shown that the profitability of both agriculture on land and aquaculture in the estuary is affected by changing freshwater flows. To assess the value of water to different users across a catchment we developed a generic water accounting framework and populated it with available...
ORGANISATION:
University of Tasmania (UTAS)
Industry
PROJECT NUMBER • 2002-409
PROJECT STATUS:
COMPLETED

Pathogenic Vibrio parahaemolyticus in Australian oysters

This project was designed to produce a “snapshot” of the prevalence of the bacterium Vibrio parahaemolyticus in Australian oysters during March and April of 2002. V. parahaemolyticus occurs in two main forms: pathogenic and non-pathogenic. In the past 3 years there have been several...
ORGANISATION:
University of Tasmania (UTAS)
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