Coastal Programs
It is a fundamental business practice to know what inventory you have on hand at any one time. However, knowing how many oyster seeds you receive is important for other reasons. Some states require records indicating the number of oyster seeds you deploy each year. In addition, the US Department of Agriculture and Farm Service Agency programs require records of your seed purchases and oyster sales to participate. It is important to have an accurate inventory all the time, and that begins when you take delivery of oyster seed. The following information describes a simple weighing method that provides a good estimate of how many oyster seed are in an order, regardless of seed size.
The Process
Oyster seed is typically sold by size, such as R2, R6, and R12, and increase in price as they get larger. For example, R2 seed retain or do not fall through a 2-millimeter screen. To get started, you need a scale that can handle small weights accurately, such as one that will measure to one hundredth of a gram (figure 1).
The first step is to gently dab the seed with a paper towel to remove any remaining moisture so that you are not counting water in the total weight of the seed. Next, place a container on the scale, and set the scale to zero (tare), so that the weight of the container is not included in the calculations (figure 2).
Then, add all the seed in your order to the container (figure 3). Put the weight in the tool where it says Total Weight of Delivery. Be sure to enter the weight in grams.
-
- Figure 1
-
- Figure 2
-
- Figure 3
Now you can begin taking small samples to weigh and count individually. Put those numbers in the Sample Weight cells (figure 4). The seed counting tool has room for five samples. However, you may want to use more to increase the accuracy of the estimated total.
Take a small container, place it on the scale, and tare it. Then, place a small sample of seed in the container. Record the weight in grams under Sample Weight. Next, count the number of seed in the container and place that number in Number of Seed. Repeat this process for the four additional samples, or more if desired. It is recommended to use at least 30 oysters per sample.
Remember to count only live, single oysters and not doubles, since those are not marketable (figure 5). Your supplier may handle doubles differently, so it is important to know that beforehand. Add your counts by sample number to the tool under Number of Seed. Once you have weighed and counted the samples, the tool will calculate and show the total for your order in Estimated Number of Seed.
-
- Figure 4
-
- Figure 5
-
- Figure 6. How many oyster seed do you think are in this order? There are approximately 1.5 million R2 oyster seed.
The tool is simply taking the total weight of delivery and dividing it by the average weight of the samples. For example, table 1 displays the results of five weighed samples. If the total weight of the delivery was 4,000 grams and the average sample weight was 0.0039073, then the estimated number of seed would be approximately 1,023,725.
Table 1. Weighing Method to Estimate Number of Oyster Seeds
| Sample | Sample Weight (grams) | Number of Seed | Total |
|---|---|---|---|
| 1 | 0.2079 | 51 | 0.0040765 |
| 2 | 0.2005 | 50 | 0.0040100 |
| 3 | 0.1871 | 47 | 0.0039809 |
| 4 | 0.1994 | 56 | 0.0035607 |
| 5 | 0.1876 | 48 | 0.0039083 |
| Average Seed Weight Per Sample = 0.0039073 |
More Information
The purchase of oyster seed is one of the largest expenses farmers have each year, and it is important to understand how your supplier counts seed for your order. Getting an estimate after you receive your order is a simple process and a good business practice. Reach out to Alabama Cooperative Extension System specialists with any questions. More information is also available in a demonstration video at https://www.youtube.com/watch?v=AvPSsvZ5tRE.