Oyster Seed PRODUCTION
Where do oyster seeds come from?
In the wild, one female oyster can produce about 20 million eggs! Some environmental cues that can induce spawning are a change in water temperature, food availability or salinity. Once fertilized, the eggs float in
the water column for a day or so before becoming swimming larvae. Around day 10, oyster larvae develop an eye spot and by day 14, they have a foot and are looking for a place to settle. They swim downward and
find a suitable substrate to attach on, usually an oyster shell. Oyster larvae secrete glue that helps them stick to their new home and then undergo metamorphosis, becoming spat.
How do we produce our oyster seed?
At Down East Mariculture, we like to say that we “baby our babies”. Our setting tanks are filled with seawater from beautiful Jarrett Bay. To help keep out anything that might be harmful to the young spat, the seawater is
filtered down to 1 micron (a grain of sand is approximately 500 microns). The filtered seawater is constantly recirculating through the tanks and drips
downward in the silos, encouraging setting. We control the temperature, salinity, pH and lighting to create optimal conditions for our larvae to set. Nine silos, with fine nylon screens on the bottom, are placed in each tank. A thin layer of micro-cultch (ground up oyster shell) is spread evenly on the screens. With a warm, dark environment, and the water dripping downward, the larvae make their way to the bottom of the silo and set on the micro-cultch.
While in the setting tanks, our babies are fed twice a day. The tanks are drained and cleaned every 48 hours and replenished with fresh 1 micron filtered seawater. When they are ready, the spat are moved to our grow-out tanks, where they now filter seawater from the bay and we no longer need to feed them algae.
In our grow-out tanks, water is constantly pumped in from Jarrett Bay, at a high rate, to ensure optimum food and oxygen for growth. We wash our oyster seed daily and they are sorted by size every 4-5 days. Our constant care produces healthy, fast growing oyster seed that farmers can usually grow to market size in 9-13 months.