 While a recirculating system can be used, a flow-through system is generally better because the natural diversity of phytoplankton is a better diet for conditioning oysters.By setting up this separate system, the farmer can mimic the transition from winter to summer quicker than real-time, and essentially convince the oyster that it is time to spawn whenever the farmer needs more larvae.When the farmer actually wants to spawn the oysters, he or she will put a batch of oysters in a tray and rapidly heat and cool the water to induce spawning.