If oyster gardening is a legal pastime in your area, the next step is to determine whether your gardening site is conducive to raising oysters. To evaluate a potential site, consider water salinity, water depth, site exposure, dissolved oxygen, and food availability. The presence of wild oysters at your site is a good sign that your location will support your gardening activities. Additional information can be found in SRAC Publication No. 432, “Cultivating the Eastern Oyster, Crassostrea virginica.”
Salinity
The salinity of the water at your site will influence the growth rate of your oysters and whether they may become exposed to oyster-specific diseases. Generally, oysters require water salinity of at least 8 parts per thousand (ppt). The higher the salinity, the faster oysters grow.
Water salinity is measured as grams of salt per liter of water, or ppt. You can measure salinity at your location using inexpensive equipment such as a hydrometer, which can be found at pet stores that sell saltwater fish. It is a good idea to keep records of the salinity at different times of the year, under varying environmental conditions (for example, after a rainfall), and at different tidal cycles. This could help you make decisions about your oyster gardening activities.
There are two diseases specific to oysters than can have a devastating effect on your crop, though the diseases do not affect humans. Both diseases are caused by protozoans.
The first is MSX (Haplosporidium nelsoni), and the second is Dermo (Perkinsus marinus). MSX organisms cannot live in salinities below 10 ppt. In fact, the pathogen can be completely eliminated from infected oysters if the oysters are held in salinities below 10 ppt for 2 weeks. Dermo can survive in salinities below 10 ppt, but it will not kill oysters at that level. Should the salinity level rise above 10 ppt, Dermo can become quite deadly to oysters.
