If you are an oyster farmer, it is important for you to have an accurate inventory all of the time and that begins when you take delivery of oyster seed.
In this blog post, I’m going to show the weighing method used at the Auburn University Shellfish Lab for estimating how seed are counted. While not 100% accurate, it is easy to get a very good estimate of how many oyster seed are in an order regardless of size.
The U.S. Department of Agriculture and Farm Service Agency programs require records of seed purchases and oyster sales to participate, and it is just a fundamental business practice to know what inventory you have on hand at any one time.
Oyster seed is typically sold by size, such as R2, R6, R12, and increase in price as they get larger. This means seed that retain on a 2-millimeter screen (R2s) are seed that do not fall through a 2-millimeter mesh (they are at least that size or larger) and so forth.
To get started, you're going to need a scale (Figure 1) that can handle much smaller weights and do that accurately.
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.
Next, place a container on the scale, and set it to zero so that it is not included in the calculations (Figure 2). Then, add all of the seed in your order to the container (Figure 3), and put the weight in a spreadsheet adding a heading called, “Total Weight of Delivery (g).” Be sure to convert grams to kilograms and vice versa as needed.
Now, you can begin taking small samples to weigh and count individually, and put those numbers in a “Sample Weight (g)” cells. Set up a seed counting spreadsheet with room for five samples, however you may want to use more or do the process more than one time because the more samples you use the greater percentage of confidence you will have in the estimated total.
Remember to count only live single oysters and not doubles since those are not marketable. Your supplier may handle doubles differently, so it is important to know beforehand.
Add your counts by sample number in a spreadsheet with a heading “Number of Seed.”
Once you have weighed and counted the samples, set the spreadsheet to calculate, and show the total in “Estimated Number of Seed” for your order.
The spreadsheet can be set to do this by simply taking the Total Weight of Delivery (g) and dividing it by the Average Weight of the samples.
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 you order. Getting an estimate after you receive your order is a very simple process and a good business practice.
You can also check out the video below for more information.
Meet the author
Russell "Rusty" Grice
Oyster Aquaculture Business Specialist
Rusty joined Sea Grant in 2016. He helps oyster farmers navigate requirements for starting farms, and he helps streamline the harvest reporting process for existing farms. His focus is on... Read more
Phone: 251-229-0826
Email: [email protected]