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Farming methods for rock oysters

Stick cultivation

This method involves keeping the sticks used for spat collection, removing excessive spat and leaving the remaining oysters to mature. The sticks used for spat collection are separated and laid out more extensively onto the racks. Sticks are spaced 15–20cm apart and then fixed to the racks.

A disadvantage with this system is that if the oysters are not thinned out they will grow in clumps and produce smaller and irregular-shaped oysters. Moving the oysters from the sticks to an alternative method has advantages, as the oysters tend to reach a larger and more regular size.

To avoid young oysters attaching to the crop (overspatting), you should place the sticks in the water column above or below the optimum levels for spat settlement. This can be determined by simple experimentation.

Tray cultivation: single seed

Tray culture uses wood, aluminium or plastic frames with bases of galvanised wire or plastic mesh. The mesh size is determined by the size of the oyster. The tops of the trays are usually covered with a wire mesh or netting, which you can remove to inspect the stock.

The tray is designed so that the height of the frame is equivalent to the height of one oyster only. This maximises the water flow to each oyster in the tray and reduces the likelihood of the oyster being flipped over.

As with the stick method, overspatting should be avoided by placing the trays in the water column above or below the optimum settlement region for spat.

BST adjustable longline: single seed

A line is tensioned between two anchoring posts with intermediate posts to keep it above the bottom. From this line, a series of PVC mesh bags are suspended with clips. You can quickly change the position of the line by adjusting the height of the intermediate posts. Bags can be removed or attached using stainless steel or plastic clips. Bags of any size can be made up to suit, depending on the size and quantity of oysters farmers wish to place in them.

Rack and basket system: single seed

Bags of PVC mesh with two sticks running lengthwise through either end are suspended between a rack structure. They look somewhat like a stretcher.

Sub-tidal system

Oysters are suspended in the water and remain below the water at all times. Various furniture may be used to accommodate the oysters, including trays suspended on buoys or pyramid-like structures with horizontal trays.

An advantage of this system is that the oysters are able to feed uninterrupted. However, as they are not pre-stressed to being out of the water, as with other methods, their shells tend to be thinner and care must be taken post-harvest to ensure the shells are not damaged, and the oysters remain alive and in sound condition.

Maximising rock oyster production

You can maximise rock oyster production by assessing the use and efficiency of your oyster areas. Find out about management strategies in our policy for maximising rock oyster production. This policy provides information on Fisheries Queensland's requirements under the Fisheries Act 1994 and seeks to apply the principles of ecologically sustainable development.

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