DEVELOPING SPATIALLY-EXPLICIT ASSESSMENT TOOLS FOR EASTERN OYSTER IN CHESAPEAKE BAY

Abstract

Decreasing abundance of the eastern oyster Crassostrea virginica in Chesapeake Bay is of concern because of its ecological, economic, and cultural importance. The objective of my study was to develop methods for conducting stock assessments of eastern oysters in Maryland waters of Chesapeake Bay that estimate abundance, recruitment, and fishing mortality at regional scales. First, I evaluated how spatial patterns in autocorrelation of recruitment and adult relativity density varied over time by fitting semivariogram models to survey data for each year. This information was then used to determine appropriate scales for my second objective which was to develop a stage-based model for the lower Potomac River using data from the Maryland Department of Natural Resources fall dredge survey and fishery data from the Potomac River Fisheries Commission. Estimated abundance declined to approximately 39% of that in 1990. The analyses will provide a platform for regional management of eastern oysters.