A Guide to Site Selection
This guide provides the fundamental steps to identifying a site suitable for oyster gardening.
1. Are the waters in the Virginia shellfish growing area with sufficent average salinity? The gardening site should be in the Bay or tributary with salt or brackish water. Usually visible signs of sufficent salinity will be the presence of crabs, naturally occuring oysters, barnacles and jellyfish. Also, you may ask neighbors for advice about oysters or oyster gardening in the vicinity. This link shows the shellfish growing areas in Virginia. This link shows the average summer salinity in the Bay. We generally advise that salinity should average above 10 parts per thousand for oyster gardening. However, successful oyster aquaculture can be conducted at salinities between 5 and 10 ppt. Salinities in this low range, however, may inhibit spawning. There is always a risk that extreme rain events may render the water too fresh for too long a time, and result in mortality. TOGA has some refractometers you may borrow for measuring salinity. However, it's best to use the map because it reflects a long-term average.
2. Water depth? It is preferable that water depth be at least 1 foot at low tide. Under normal weather conditions, it does not hurt the oysters to be exposed to the air at extreme low tide. However, there is a risk of the oysters freezing at extremely low tide and temperature. So, in the winter, the deeper the water the better. If your oysters appear to be frozen, or are encased in ice, it is best not to move them because the movement may further endanger them. It is best to wait until they are in liquid water to move or handle them.
3. Are the waters condemned? Condemned waters do not necessarily mean that you cannot oyster garden. Opening this link, you may then click on the map for a specific locality you are interested in. Search for the name of the body of water in which you are interested. That link will give you a downloadable PDF (including a map) that shows you where those waters are condemned, and give detailed information as to the the type of condemnation. If the waters you are interested in are not shown, then they are clear of condemnation. Remember, these condemnations change from time to time. The figure below is an example of a condemnation map.
In the figure, the areas with single hash lines are condemned for bacteria considered too high for commercial sales of oysters taken directly from these waters. The condemnation is based on a 30 month averaging of samples of water that are tested for E coli. These oysters however, may be sold commercially if "relayed" in non-condemned waters for 15 days under certain conditions and controls.
The areas with crossing hash lines show where oysters may not be removed for any reason. Not an area for oyster gardening.
The dotted area is seasonably condemned. This usually happens near a Marina. Be sure to read the detailed instructions as to what time of the year is considered safe for harvesting from those waters.
Example Condemnation Map. (Downloadable PDF will include map and detailed instructions.)
Water treatment plant. No oysters may be removed.
Bacteria. You may oyster garden.
Seasonally Condemned. Read instructions for when to harvest.