Oyster Gardening

(Published September 2001)

Shellfish have been cultured by humankind for millennia. Recently, Virginians and Marylanders have discovered how easy it is to “garden” oysters.

Basically, oysters require moving water of appropriate salinity and adequate oxygen content, and food they can filter from the water. Our local waterways provide these requirements in abundance, and many local waterways once supported flourishing reefs. Over the last decade many schemes to grow oysters artificially have evolved, but they all follow the rule “Moving water, up out of the mud, and room to grow”. The most common scheme is to employ a “Taylor Float” of sturdy plastic mesh hanging from a PVC pipe frame for flotation. Flotation can also be provided by plastic bottles or a sheet of styrofoam insulation. Some type of top is necessary to keep birds, crabs and otters out, and to provide shade so algae are discouraged from fouling the oysters. It is also possible to grow oysters in cages on the bottom elevated above the mud. Tending the oysters at least monthly, to remove leaves, pine needles, crabs, etc., to stir them up and separate shells that have grown together, and to remove mud that may have accumulated, is also advised.

Two oyster diseases, “MSX” and “Dermo” kill adult oysters (they do not affect humans), so initiating a “garden” in the fall is the best strategy. In this way the spat can grow for about 20 months before they become susceptible to disease during their second summer. Each fall workshops are held where floats are constructed and spat are distributed, and attendance is a good way to get started.

There are several good reasons to grow oysters even if you don’t like to eat them. First, and foremost, oysters filter algae out of the water, clarifying it. If our waterways can be made clearer, submerged aquatic vegetation (SAV) can become re-established and provide important habitat for many organisms like crabs and fish of commercial and recreational importance. Second, the oysters can be used as “seed” on artificial reef sanctuaries which have been and continue to be constructed. Oyster gardeners can obtain free spat if they want to participate in this program, which is sponsored by the Chesapeake Bay Foundation. Oyster gardeners can also enroll in a program at the Virginia Institute of Marine Science to track the mortality of different strains of oysters which are being developed, some of which, hopefully, will prove to be disease-resistant. And finally, oyster gardens are an important source of spat which will encourage the re-growth of local reefs.

There are several words of warning, however. A (free) permit is required so that the State can track the magnitude of the effort and ensure that no hazard to navigation exists. Also, it is quite common for our waterways to be restricted for the harvesting of all kinds of shellfish, whether or not they are grown artificially. The restriction exists because of high levels of fecal coliform bacteria, especially toward the headwaters of our creeks and rivers. Virginia is extremely strict about coliform bacterial levels to ensure that live oysters eaten locally or exported to out-of-state do not cause illness. The source of the bacterial contamination is not known with certainty, although wildlife (especially raccoons), water birds and pets are implicated, as well as privies and non-functional septic systems. The restrictions do not apply to fish or crabs, and should not discourage people from starting oyster gardens because it is possible to move the edible oysters to unrestricted waters so they can purify themselves. But growing oysters just for “seed” is good for the creeks, fun, and a great learning experience for children and grandchildren (as well as everyone else). You can find the location of restricted waters at the Shellfish Sanitation Division of the Virginia Department of Health website.

For more information about oyster gardening, contact TOGA (Tidewater Oyster Gardeners Association) at www.oystergardener.org. The VIMS web page at www.vims.edu/abc/green, and the Chesapeake Bay Foundation at www.cbf.org are also good sources of additional information.