Grading seed and juvenile oysters

Farm of oysters

Grading seed and juvenile oysters is an essential part of oyster farming. It involves sorting oysters based on size and/or age to ensure proper growth, optimal conditions and effective management of oyster populations. The grading process allows oyster farmers to monitor and control the development of oysters, ultimately improving the overall yield and quality of the harvest.

Seed oysters are very young oysters, typically in their larval or spat stage. Grading seed oysters is crucial for providing the best environment for them to grow and reach their optimal size. The grading process involves sorting the oysters based on size and sometimes age. Oyster farmers commonly grade seed oysters into different size classes, such as micrometres, millimetres and centimetres.

The grading process allows oyster farmers to separate the smaller, slower-growing oysters from the larger, faster-growing ones. This separation can be useful for managing space in oyster beds or nursery systems, promoting uniform growth and reducing competition among oysters.

oysters in a grader

Juvenile oysters

Juvenile oysters are older than seed oysters but have yet to reach their full market size. Grading juvenile oysters is essential to ensure that they have the right conditions for continued growth and to prevent overcrowding, which can hinder development. Farmers typically grade juvenile oysters into different size classes based on their shell length or width, as follows:

Small: Usually the smallest size class for juveniles
Medium: Oysters with moderate growth
Large: Closer to market size but still need to mature fully

By grading juvenile oysters, farmers can plan their cultivation practices more effectively and optimise resources to encourage healthy growth. This can include transferring oysters to different areas with specific conditions or providing them with supplemental feed to support their development.

The SED Graders water grader

Mortality rates are a significant challenge in the grading of seed and juvenile oysters. Typical farms experience a mortality rate of around 45% of oysters from seed to sale size. The barrel and shaker method causes a lot of stress on the young oyster, and hand grading is labour-intensive and expensive.

The SED Graders water grader is a game changer for many oyster growers. It replicates the way juvenile oysters behave underwater. The water grader is fully automatic and frees oyster farmers and workers from the laborious task of grading.

An operator can fill the hopper or seed table single-handedly. The grader then automatically sorts the oysters underwater into three sizes and delivers them to collection points via three small conveyors. The automated system is exceptionally gentle on the oysters and grades with superior accuracy to human grading.

The water grader is faster, less expensive than labour and has greatly improved mortality rates compared to traditional grading methods.

“The SED Water Grader is fantastic! It’s made a huge difference to our output. We see new growth within a week of grading and I can grade and re-bag 40,000 oysters in half a day by myself.” Jane Clout – Kooringal Oysters Qld

Customed designed for your farm

The team at SED Graders will custom design a water grader to suit your specifications. We deliver our automation technology nationally and internationally and have various production equipment to support your grading needs.

We manufacture our water graders from stainless steel and build them to last in remote and hostile oyster farming environments. Their innovative design allows for easy operation and minimal servicing.

You’ll find it easy to manage small repairs, and our SED Graders team provides after-sales support worldwide, including remote access TeamViewer support.

For seed and juvenile oysters, the SED Graders water grader reduces mortality rates to as low as 1.5%, which will make a big difference to your next harvest.

A man supervising the oyster machine operator

SED Graders Australian and family-owned

SED Graders is an Australian and family-owned company. We provide worldwide after-sales support and fully train you to use and optimise the vision grader for maximum output.

Contact us for any questions, and when your farm is considering a SED Graders oyster grading machine or upgrading your current machine, we can advise the perfect solution tailored to your needs.


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