To manage the introduction of potential diseases into South Australia, the PIRSA Aquaculture SA have protocols in place to control the importation of fish species, including marron, into our state.
This allows the marron industry to operate in a relatively disease free environment. There are two main health issues that are present within the South Australian marron industry.
Thelohania:
Thelohania is a microsporidian which affects the tail musculature of the marron. It is also known as “chalky tail” due to the thelohania organism causing the tail muscle to become white and chalky in appearance.
Thelohania is mainly found in wild populations therefore stressing the importance of obtaining broodstock or juveniles from registered growers rather than from wild populations which increases the risk of introducing the parasite into an aquaculture pond.
Temnocephids:
Temnocephids are an ectocommensal (external parasite) that reside on the exoskeleton of the marron. They are often associated with low salinity and nutrient rich waters. Eggs of temnocephalids are laid on the underside of the tail of the marron and sometimes within their gill cavity.
Temnocephalids are rarely harmful to marron unless they are present in extremely high densities. Presence of adult temnocephalids or their eggs within the gill chamber of the marron may cause respiratory problems.
Their appearance may also reduce the market appearance of the marron. Adult temnocephalids can easily be removed by washing the marron in a salt bath for a couple of minutes. However the eggs of temnocephalids are extremely adherent and remain even after steaming and boiling.
The Future of Marron Farming:
There are programs in place to ensure the successful development of the marron farming industry.
Code of Practice:
There is a Code of Practice for the Growing of Freshwater Crayfish (yabbies Cherax destructor AND marron Cherax tenuimanus) in South Australia. The Code of Practice was produced by the Australian Freshwater Crayfish Growers Association South Australia (AFCGA-SA), the PIRSA Aquaculture SA and the Environment Protection Authority (EPA).
It provides guidelines to marron growers on site selection, pond construction and waste water management to ensure that the industry develops in an environmentally sound manner.
The Code of Practice for the Growing of Freshwater Crayfish can be obtained from a AFCGA representative, the Aquaculture SA PIRSA and the EPA.
A Code of Practice for Post Harvesting Techniques of freshwater crayfish (marron and yabbies) has been developed to ensure that a premium quality product will be delivered to the market place.
Research Pond Project:
In 1997 the South Australian branch of the Australian Freshwater Crayfish Growers Association (AFCGA-SA) was awarded grant funding through the Rural Industry Adjustment and Development Fund (RIADF) to establish four research trial ponds. The purpose of these ponds was to conduct
research projects relevant to the industry that will aid in refining and establishing best practice procedures and therefore improve production and participation in freshwater crayfish aquaculture.
The four research ponds are situated on established freshwater crayfish farms located throughout the state on Kangaroo Island, Fleurieu Peninsula and the upper South East. Each pond is divided into 24 enclosures and equipped with an airlift aeration system. Research will incorporate both marron and yabbies. Research undertaken within the ponds investigated:
- Diet and feeding regimes
- Stocking rates and regimes
- Importance of habitats
Research was being coordinated and conducted by AFCGA-SA in conjunction with the Aquaculture Group in Primary Industries and Resources South Australia (PIRSA), South Australian Research and Development Institute (SARDI), the University of Adelaide and Flinders University. This research is now being managed by the Australian Freshwater Crayfish Growers Association.
Production in the Future:
Marron farming has a promising future in South Australia. With larger commercial operators entering the industry combined with the establishment of improved management practices due to further research and development within the industry, production is expected to increase in the future.
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