Improving Siting and Construction : Criteria for Oyster Reef Restoration

The Chesapeake Bay, named Chesepiooc, the “great shellfish bay,” by the Algonquin speaking native Americans of the region, was once one of the most productive oyster (Crassostrea virginica) producing estuaries in the world. With the advent of canning and the development of the railroad system, huge national and international markets were established for Chesapeake Bay oysters (United States Secretary of the Interior 1866,Wennerston 1981). From 1894 to 1912 annual oyster harvests in Virginia alone ranged from 5 to 7.5 million bushels (Hargis and Haven 1988). Shells from harvested oysters were not replaced on oyster grounds but sold for a variety of commercial purposes ranging from road projects to chicken feed. This tremendous, largely unregulated, harvest of oysters and shell, wreaked havoc on oysters and their habitat (Wennerston 1981, Rothschild et al 1994). In recent years, considerable attention has been paid to the historical anecdotal reports of mariners who reported that Chesapeake Bay oysters once grew in large reef-like colonies. These stories suggest that Chesapeake Bay oyster reefs were once three dimensional structures which breached the surface of the water at low tide. It is believed that the three dimensional structure of these reefs favorably altered the environment for oysters by raising oysters off the bottom into the more favorable upper water column which increased oxygen, water temperature, and food availability for the oysters. Based upon these reports and beliefs, three dimensional oyster reef habitat restoration efforts in Virginia began in 1993. Studies by the Virginia Institute of Marine Science indicated that the greatest oyster survival rates could be found on reefs created from oyster shell and thus reef restoration focused upon the deployment of large mounds of oyster shell. These shell mounds, or reconstructed reefs, were primarily situated upon areas surveyed in the 1970s (Haven and Whitcomb 1978 & 1983) which were classified as hard oyster bottom. These hard oyster bottom areas were considered to be “reef footprints.” Reconstructed reef shape and orientation was based upon the shape and orientation of these “footprints” as well as knowledge of the local site, history of reefs in the area, and navigational and social issues that are unique to the local area. These siting procedures have changed little since 1993. While the application of these concepts has continued in the field with the aim of increasing viable oyster habitat while decreasing the costs of restoration, research has also continued examining options and techniques for increasing oyster reef success. Much of this research has focused upon understanding the natural function of oyster reefs as they historically existed in hope of applying this knowledge to restoration efforts. This paper outlines some of the things which have been learned through these endeavors and ways which these lessons can be applied to continuing restoration efforts to increase restoration success