Oyster spat live12/29/2023 When oysters reach about 20 mm they are transferred to nets suspended on floating longlines in open seawater in sheltered bays. ![]() Oysters are filter feeders and extract plankton from seawater. This is process is called ‘upwelling’ and results in fast growth, oysters can grow to 15 - 20 mm in three to four months. These seed oysters are held in floating crates, through which water is pumped in an upward motion. Better grow-out times are achieved using Chilean spat, bought at 7 - 12 mm size. Spat can be bought at about 2.5 - 3 mm but this results in a long grow-out time. The purpose of oyster nurseries is to rapidly grow small oyster seed or ‘spat’ for transfer to grow-out trays, bags or nets with mesh apertures of 7 - 12 mm. Grading the size of oysters is done throughout the production, from spat size to final harvest. The final stage is conditioning and grading. The third phase is grow-out from juvenile to harvest size. ![]() The second stage is the nursery rearing of spat from 1 - 15 mm. Small quantities of spat are also produced in Kleinzee, in South Africa’s Northern Cape Province. In South Africa, the most oyster spat is imported from Guernsey, Chile, Europe, Namibia or the United States. Larval rearing and spat production is the first stage. The Oyster Farming Processīasically, the process of farming oysters consists of four stages: These nets are suspended from floating long-lines, which are anchored to mooring blocks. Seed oysters, also called ‘spat’, are stocked into lantern nets, which are spaced 1,5 m away from each other. The long-line system is widely used in South Africa oyster farms. There is, however, a land-based oyster farm in Kleinzee, which produces oyster seed, and a small government-run oyster farm, using oyster racks, was established in the Keiskamma estuary. ![]() In South Africa, the bulk of oysters are produced in offshore-based mariculture farms. Pacific oysters, the most widely farmed oyster species, can be produced in land-based, estuary or offshore-based production systems. © Commonwealth Scientific and Industrial Research Organisation CSIROFor oyster farming in South Africa, spat is mostly imported.
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