To promote even growth and provide optimal growing conditions, oysters are brought in to the farms onshore facility and graded usually between 4-6 times throughout their life to manage their growth and ensure their baskets are not fouled to promote good water and food flow.
Various grading methods are employed including: by hand, gentle water shakers, vibration shakers, tumblers, and automatic computerised pneumatic grading machines. Grading oysters into consistent sizes and the removal of any dead oyster shell is important for: promoting healthy and strong growth; hardening and shaping shells; and discouraging mortalities.
As they grow bigger, fewer oysters are placed in each basket to allow sufficient room for growth. For instance, a spat tray may contain several thousand spat sized oysters initially and following several grades, and by the time they are ready for market, they have as little as 50-60 oysters per container.