The oyster seed grown in the tidal upweller doubles in volume every 7 days due to the 4 knot current in the channel where it is located. Due to this, the seed must be sieved or graded every week.
Each of the bins is poured into the appropriate size mesh sieve.
And hand sieved. This allows us to keep the correct sizes and densities stocked in all of the tidal upweller bins.
Once the oysters are approximately 1 inch in size, they are moved from the tidal upweller to our shallow water site. Here the grading is done by machine. This is our tumbler/grader. There are various sizes of mesh screens that can be changed on the machine. We can get a maximum of 3 different sizes of sorted oysters with one pass through the machine.
This tumbler/grader makes the task of keeping up with sizing the oysters much easier. The other advantage to this machine is the tumbling action keeps the oysters cleaner. As the oysters pass through, much of the fouling of barnacles etc. are knocked off as the oysters bang into each other. Also, the tumbling motion gently chips the edges off the oysters encouraging a nice cup shaped shellfish.