Prawn Nurseries; their role in improving efficiencies and yields for prawn farms in Australia
Nursery systems are additional phases in the culture of prawns between larval production at the hatchery and final grow out in the pond.
Introducing nursery phases to Australian prawn production offers greater control over the crop for longer periods of time. Greater control affords the farmer the ability to manipulate growing environments and to more effectively assess production by way of efficiencies.
Post larval care in nursery tanks or raceways can improve the quality of the stock that is put into the ponds by benefiting from:
Access to the post larvae (PL) for assessment of health and development: PL raised in higher densities in tanks can be simply collected for visual observations and laboratory testing. The behaviour of PL in the nursery environment is easy to assess.
High quality commercial nursery diets: The nursery environment allows farmers to easily manage feeding by monitoring waste and gut contents. Efficiency in feeding means that the farmer can benefit from more expensive, higher quality feeds that are available for nurseries but inefficient in the ponds.
Reducing water management costs: Smaller water volumes in nurseries can easily be affected by water exchange, probiotics and siphoning of wastes, requiring less water than pond rearing of PL. Smaller volumes of water are cheaper and easier to move and can be treated to remove pathogens and pollutants.
Maintaining optimal water conditions: Nurseries can be housed in greenhouses to reduce temperature variability and provide warmer conditions in cooler production periods. Water parameters in nurseries are more easily manipulated due to controlled conditions and smaller volumes of water.
Improving biosecurity: Housing nurseries in greenhouses, treating incoming water and ease of disease monitoring provide greater biosecurity than pond rearing of PL. Controlled nursery systems also allow for effective quarantine of infected stock to prevent the disease spreading to the ponds.
Protecting stock from predation: The biosecurity benefits of nurseries also protect stock from predation by fish and birds that could otherwise gain access to ponds.
Growing PL to be bigger and stronger in nursery environments means that the animal gets a head start in the pond. Bigger, stronger PL are more tolerant of the stresses of the pond environment and stocking these improved PL can result in improved pond production.
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