All pacific oysters for commercial grow outcome from a hatchery. Most are supplied from 4 to 10mm long and are single seed, (all separated).
The 4mm oysters are placed into seed trays with small plastic mesh and are either suspended just below the water’s surface or on inshore racking.
After a period of 6 to 8 weeks, they are graded and the quickest grown commonly known as (front runners) are placed into 6mm baskets and then the constant job of grading oysters starts. Oysters will be graded between 5 and 7 times by the time they reach the most popular market size (buffet).
Oysters take anywhere from 18 months to 3 years to grow to a marketable size depending on the techniques used.
Constant grading ensures that the oyster shell remains in a good shape, which in turn will maintain good meat quality. Grading also improves the growth rate as the more even they are maintained in the basket the better rate of growth is achieved.
Oysters are grown in 2 distinct areas in the water column. Firstly the most common method used has been the rack and rail method where baskets are placed on wooden rail structures. These oysters are periodically out of the water when the tide is sufficiently low enough to expose the railing and the oysters are therefore not feeding.
The second method used is for the oysters is deep water or sub-tidal, generally, 45-55mm oysters are placed into either baskets or cages which are then suspended clear of the seabed. This method allows the oysters to feed all the time and growth is much quicker, however, they need to be graded and handled on average every 6 weeks to avoid soft and out-of-shape shells.
Oysters eat small microscopic larvae and are not artificially fed therefore good water quality is of huge importance to the oyster farmer.