Overcatch cold shock treatment

The overcatch cold shock treatment designed by SED Graders is gaining industry traction and investment from several stakeholders interested in developing a treatment bath that can benefit oyster farmers in Australia and internationally.

Australia’s thriving oyster industry faces a constant challenge known as ‘overcatch’ or ‘fouling,’ costing the industry substantial labour, crop losses and reduced product prices. In a groundbreaking initiative, Queensland is at the forefront of a study and trials comparing the effectiveness of existing overcatch treatments with the innovative SED Graders cold shock system.

(Photo is a prototype for treating whole baskets. Smaller developments will be available) 

Engineered to fit into existing grading lines


The SED Graders team has engineered a prototype ‘cold shock treatment’ unit that seamlessly integrates with SED Graders Vision grading lines. This technological leap offers a significant advantage – the ability to treat overcatch during routine grading, eliminating the need for additional labour.

Let’s delve into the details of this revolutionary system and how it could reshape the future of oyster farming.

The heart of this system lies in its ability to use icy saltwater to ‘shock kill’ small oysters, barnacles and weeds, up to approximately 12mm in diameter. The precision in targeting overcatch without harming the host oysters is what sets it apart. The operator can activate the system when they detect overcatch during the regular grading process through a SED Vision Grader.

Incorporating the right infeed equipment, including a SED washer, the cold shock treatment unit could function as a stand-alone item. This versatility opens up new possibilities for oyster farmers, providing them with a powerful tool to combat overcatch in various settings.

Safety and efficiency


Host oysters, surprisingly resilient, can withstand immersion in the cold salt water for 30 to 60 seconds, the ideal duration to effectively eliminate overcatch. The inline integration with the grading system adds an extra layer of safety and convenience, making the process significantly safer and more straightforward than traditional methods like dipping oysters in hot water.

The ambitious study project has garnered substantial support and co-investment from key players in the industry.

The Queensland Department of Agriculture and Fisheries (DAF), Fight Food Waste Cooperative Research Centre (FFWCRC), and the Australian Government’s Fisheries Research and Development Corporation (FRDC) have joined forces with industry partners such as Kooringal Oysters, Moreton Bay Rock Oysters, Gold Coast Oysters and SED Graders.

This collaborative effort signifies the industry’s recognition of the potential impact of the cold shock treatment system on mitigating overcatch and improving overall efficiency in oyster farming.

A significant advantage to oyster farmers worldwide


As the trials progress, the oyster industry eagerly anticipates the potential transformation brought about by the SED Graders cold shock system. With its ability to integrate with existing grading lines, offer a safe and efficient treatment process, and garner significant support from industry leaders and research institutions, this innovation can revolutionise how oyster farmers combat overcatch.

SED Graders is an Australian, family-owned company. We are dedicated to delivering comprehensive worldwide after-sales support and providing thorough training to enable you to operate and optimise our state-of-the-art vision oyster grader, maximising its output potential.

For any inquiries or when contemplating the acquisition of a SED Graders oyster grading machine or upgrading your existing equipment, we invite you to contact us. Our expert team is poised to offer tailored solutions aligned precisely with your unique requirements and operational goals.

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