Larval prawns are fed on cultured phytoplankton and zooplankton, including brine shrimp (Artemia salina). Some formulated, microparticulate diets are also available for larval prawns.
Formulated diets are used as soon as postlarvae are stocked into nursery or growout ponds. Initially, diets developed for poultry or trout were used, but these have now been completely replaced by specially formulated penaeid diets because of better performance.
Penaeid prawn diets are usually based on fishmeal and Soya bean, and often include small quantities of squid or other mollusc meal. These are well digested and utilized by prawns and supplies a well balanced mix of essential amino acids for growth and development.
Although there are abundant supplies of protein rich meals from terrestrial animals and plants in Australia, very few fishmeal or squidmeal products or other aquatic protein meals are produced.
Diseases and predators:
To protect native species and reduce the risk of vertical transmission of diseases, no live penaeids are allowed into Australia. So far, this appears to have prevented the introduction of major Penaeid viral diseases such as Infectious Hypodermal Haematopoietic Necrosis Virus (IHHN), Yellow Head and White Sport viruses, which have caused very serious disease problems in countries that permitted importation.
Monodon Baculo Virus (MBV) had been recorded in Australia although this appeared to be a problem in hatcheries where prawns are cultured under sub-optimal conditions. Although viral, bacterial, fungal and protozoan infections have occurred in Australian prawn hatcheries and ponds, there have been no serious epidemics reported.
Predatory fish are usually excluded from ponds by proper screening of incoming waters, but predatory birds, especially the black cormorants, have caused major problems in some areas.
Commercial farm development potential and sustainable aquaculture strategy Ten major estuaries from the Tweed River down to Manning River, have recently been investigated by the New South Wales Fisheries following a joint program of government agencies and representatives of the aquaculture industry, to evaluate areas suitable for land-based commercial aquaculture development.
The project involved risk analysis of potential sites as well as formulation of specific environmental codes of practice as a strategic process to ensure a viable and environmentally sustainable aquaculture industry.
Geographical Information Systems (GIS) technology was utilised to map suitable sites. It is envisaged that this risk mapping process will help direct the investment community to short-listed areas in these estuaries where the proponent can undertake specific site assessment.
This approach will be the basis for the future commercial development of viable and sustainable aquaculture industries for the estuarine farming of endemic prawns and finfish species in NSW.
Marketing:
For annual nationwide commercial prawn catches the Commonwealth Bureau of Rural Science’s Fishery Status Reports. Much of the fishery’s catch is exported. In NSW, black tiger prawn farms recorded a 463 tonne production valued at more than $6 million for 1998. Mostly, the prawns are marketed as a value-added product (cooked prawns) for local markets, mainly Sydney and Brisbane.
Conclusions:
There now exists excellent opportunity for the prawn industry to boom in NSW because of the Government’s recent approaches to streamline regulatory frameworks controlling aquaculture development, to ensure an economically viable and ecologically sustainable aquaculture industry.
Problems such as urgent establishment of commercial prawn hatcheries in NSW, identification of suitable sites for prawn farm development, bridging the gap between research and the industry, and code of best practice, were being addressed to by the Government’s inter-agency Steering Committee also recently established.
The challenge for the prawn farming industry throughout Australia is to reduce production costs, maintain high product quality and remain competitive. Problems with broodstock availability and quality, and the maturation of broodstock in captivity, will also need to be solved to ensure that availability and quality of postlarvae do not restrain the prawn farming industry.
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