Date Awarded


Document Type


Degree Name

Master of Science (M.Sc.)


Virginia Institute of Marine Science


Natural resource mangers may find themselves in a conflict of interest over the management of shallow subaqueous bottom when they attempt to promote both hard clam (Mercenaria mercenaria) aquaculture and the growth of submersed aquatic vegetation (SAV) (Zostera marina and Ruppia maritima). This project examines the issue of bottom use conflict along the Lower Eastern Shore of the Chesapeake Bay in a managerial and scientific context in an attempt to develop a solution to this conflict. First, it examines historical trends in clam aquaculture and SAV growth in the study area. Habitat suitability models are then developed to predict optimal habitat for clam aquaculture and SAV and through these, potential conflict between these resources. Comparable Western Shore sites are used for validation of ceratin models. The laws and policies of Virginia and the neighboring states of Maryland and North Carolina are then examined to understand the political reasons for this conflict. Finally, the historical, scientific, and political information is summarized and potential solutions to this conflict are recommended. Results show bottom use by clam aquaculture in Cherrystone Creek along the lower Eastern Shore of the Chesapeake Bay often increased between 1989 and 1997. SAV beds were also generally expanding during this time both in Cherrystone Creek as well as in creeks north of cherrystone where no clam culture was occurring. Habitat models, incorporating biological factors (SAV spreading rates, exposure tolerance, and light requirements) and management factors (water depth and bottom hardness for tending clams, exposure to prevent smothering of clam nets) show large areas of both suitable clam and SAV habitat in the lower portions of the study creeks. Consequently, conflict models show large areas of potential conflict in study creeks where these habitats overlap. Study of the policies, laws, and regulations of Virginia and adjacent states shows that none of these states have adequately addressed this issue. The primary management recommendation of this project is to annually define existing SAV beds and a 50 meter buffer surrounding these beds and restrict use of this area to clam aquaculture. Habitat models which placed “no clam” buffers of 50, 100, 150, and 200 meters around an SAV bed suggested a 50 meter buffer would adequately protect SAV bed expansion while minimizing areas legally restricted but otherwise suitable for clam aquaculture.



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