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Extensive larval rearing is carried out in earthen ponds ranging from 0.1 to 1 hectare surface area. Ponds designed with a maximum depth of 1.8 metres and a central concrete raceway into which the entire pond drains, enable easy harvesting (see Shelley (1993) for details). Inlet water should be pre-filtered to 300µm to filter out potential predators and eggs of other fish species.
Ponds to be used for larval rearing should be filled and fertilised with a combination of organic and inorganic fertilisers 8 to 10 days before the larvae are stocked. Fertiliser regimes for extensive pond culture varies across Australia, and the natural productivity of the seawater and pond soil at each site must be taken into account when determining the correct fertiliser regime. Table 3 provides the recommended fertilisation rates for northern Queensland. Schipp (1996) details rates for the Northern Territory. Farmers should develop their own application schedule based on these two examples.
| 1,2 |
Di-ammonium Phosphate (DAP) 5.3 kilograms (kg) / megalitre (ML) |
| 3 |
Lucerne 450 kg per hectare (ha) |
| 6 |
DAP 5.3 kg/ML |
| 8 |
Add newly hatched larvae |
| 10 |
Lucerne 150 kg/ha |
| 12 |
DAP 5.3 kg/ML |
| 14 |
Lucerne 150 kg/ha |
| 18 |
DAP 5.3 kg/ML |
| 20 |
Lucerne 150 kg/ha |
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Reference: Rimmer (1991) |
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