The mass spawning process begins by selecting a group of oysters and removing them from the conditioning system. Selected oysters are placed on the spawning table and water is turned on to the oysters at the same temperature, 20 degrees Celsius (74 degrees Fahrenheit), they were taken from. This is to lessen any stressors the oysters encountered when moved. After an hour, the water temperature is increased on the oysters. The water temperature continues to be gradually increased over a few hours until a temperature of 30 degrees Celsius (86 degrees Fahrenheit) is attained. If the oysters have not spawned naturally at this point, oyster gonad will be introduced into the water column to stimulate the oysters. Once the oysters filter and detect the gonad in the water, they will start to release their own gonad and kick off the spawning frenzy. This process is called mass stimulation.

Oysters are sexed by how they spawn, and what they release. Males will emit sperm out from the dorsal side of their shell. Sperm is white in color and is released in a cloudy or milky stream. Males will release sperm in a continuous flow for an extended period of time. Females clap their valves together to release eggs in a puff from the front of their shells. Eggs are white in color and are approximately 40 microns in size. A cloud of eggs looks similar to very small sugar granules suspended in a glass of water. Females can clap every 30 seconds up to an hour, producing anywhere from 2 to 70 million eggs per spawning event. The fecundity, or amount of eggs a female can produces, depends on the female’s size, age, health, condition, and if it’s the first or last spawn of the season.

Once the sex of the oyster is determined, the spawning oyster is removed from the spawning table and placed into a smaller Rubbermaid dish pan filled with water at the same temperature of the larger table. All females are placed in one container and all of the males into another. This is done to collect the eggs and the sperm, get a diverse genetic gene pool, and to prevent polyspermy, the occurrence when too many sperm fertilize one egg. Polyspermy results in over fertilization and the eggs will not be viable. One spawning event can last up to one hour, with the total time of the acclimation of the oysters at three to four hours.

Once the oysters are done spawning, the adults are carefully removed from the spawning tubs and measured. The egg mixture is transferred into a large 30 Liter bucket and diluted with filtered ambient water at the correct salinity and temperature. The eggs are counted using a microscope to tally the number of eggs found in one milliliter of the diluted egg mixture. Once the estimated number of eggs is determined, the proper amount of sperm is added to the buckets. The eggs will be allowed to fertilize for ten minutes and will be checked to see how they progress under the microscope. If the eggs are not fertilized more sperm will be added, but if 90-95% of the eggs are starting to undergo cell division, the eggs will be transferred into large larval tanks for grow-out.