Please click here for a printable version of the handling notes for oyster seed:

Explanatory notes on ‘Stock Count sheet’

GSFCode: At GSF each batch of seed is identified with a unique batch Code, enabling us to trace the seed back in our records.  Each time we send out seed we hold a small sample in order to measure growth and survival after one month.
A shipment of seed may consist of several Codes which are counted and packed separately to enable you to check our counts and to keep them separate if you wish.
At least, we recommend you keep a sample of each Code separate so that we can compare your growth and survival with our results.  If you are trying to bag to a certain number per bag, be aware that you will have to re-measure the volume or weight required for each Code.

Size: This is the size of screen in mm that the seed has been graded on eg G7 for 7mm.

Unit weight:  This is the average weight of a single seed oyster/ clam within the batch. This is determined by weighing and counting 3 samples of about 200 seed and calculating the average or mean as shown on the sheet.

Unit weights can vary a lot.  When seed has been newly graded it is going to be lighter than seed that has been held for one or two weeks.  When seed is growing fast it tends to be lighter for the same grade size.  For example, G7 seed can be between 0.15 and 0.25 grams when freshly graded or 0.25 – 0.4 grams 2 weeks after grading.

Net weight: This is the total weight of all the oyster seed of a particular code in the current dispatch.

Number: Is calculated by dividing the net weight by the unit weight  Oyster seed that is attached to other seed (“doubles”) are not included in the count.

Check weights. When packing, a single sample is counted and the net weight recorded.  The resulting count is not as accurate as the original count but it serves as a check and  the Daily % weight gain shows how the seed are growing. This weight for each code is totalled as Total despatch weight and the Total Boxes shown.

Suggested stocking and handling oyster seed

G7       Max 1000 about 200g/bag                      4mm mesh bag
G10     Max 500 about 250g/bag                      7mm mesh bag
G13     Max 500 about 500g/bag                      9mm mesh bag
NB stocking will depend on time of year/ expected growth of stock and frequency of grade.

We recommend turning every 4 weeks in growing season.  G7 seed and smaller should be graded every 4-6 wks.  G13 can be graded just once a year in the winter.


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