It has been employed for the last 30-40 years.
Stock depends on natural spatfall, which is collected on tarred and concreted hardwood sticks.
These are 1.8 metres long and 2.5 centimetres square. Smaller sticks would be too flexible in waves which would dislodge the oysters. Larger sticks would be too heavy both to be supported in the mud and to handle. This method went through a phase of using fibro slats to collect and grow the spat. When spread out, the fibro sticks are held upright between two pairs of nails.