Non-Native Oysters

The eastern oyster Crassostrea virginica is native to the Chesapeake Bay and coastal waters from Canada to the Gulf of Mexico. Though a prolific species, C. virginica populations in the Bay have been subjected to overfishing, habitat loss and, for some years now, parasitic disease, especially Dermo and MSX, which has devastated oyster populations.

The resulting economic losses have severely impacted harvesters, processors, equipment suppliers and other support businesses. The ecological impacts have also been immense, though only over the last decade have we come to appreciate the importance of oysters and oyster reefs in helping to protect water quality and provide habitat for diverse species.

Though not harmful to human health, MSX and Dermo are so virulent and pervasive in the Chesapeake that large-scale efforts to rebuild sustainable populations have not had much success. This is especially so in Virginia's portion of the Bay where high salinities are conducive to disease. While rehabilitation efforts to restore the native oysters are ongoing - there is evidence of success in hatchery-bred strains such as CROSBreed that are resistant to disease - some stakeholder interests have been arguing for the introduction of a non-native species that is inherently resistant to MSX and Dermo.

Researchers initially focused on Crassostrea gigas, a species native to Japan and also the primary commercial species grown on the west coast of the U.S. as well as in major oyster fisheries throughout the world. More recently, scientists at the Virginia Institute of Marine Science (VIMS) have been studying the potential of Crassostrea ariakensis, another Asian species. All research and field trials in Virginia have been limited to employing infertile (triploid or tetraploid) oysters in Bay waters.