PRELIMINARY COMPARISON OF GEOGRAPHIC INFORMATION SYSTEM (GIS) ANALYSIS OF PATENT TONG AND BAR CLEANING OYSTER POPULATION ESTIMATES IN THE UPPER CHESAPEAKE BAY Allen, S, H. Lane, J. Goodwin, M. Chen, M. L. Kellogg, K. T. Paynter MEES Program, 0105 Cole Field House, University of Maryland, College Park, MD 20742

Introduction Oysters are of vital importance to the health of the Chesapeake BayOysters are of vital importance to the health of the Chesapeake Bay Oyster abundance in the bay has been on the decline since the late 1800’sOyster abundance in the bay has been on the decline since the late 1800’s Currently, there is no standard method for population estimationCurrently, there is no standard method for population estimation

Goal: Pilot Study Explore methods of oyster population estimation

Objectives Ground truth patent tong sub-samplingGround truth patent tong sub-sampling Estimate & compare oyster bar populations using two methods (Leslie/DeLury and GIS)Estimate & compare oyster bar populations using two methods (Leslie/DeLury and GIS) Determine the feasibility & reliability of estimates based on patent tong samplingDetermine the feasibility & reliability of estimates based on patent tong sampling

Patent Tonging Modern method of oyster harvestingModern method of oyster harvesting Allows for sampling of a greater area than with diversAllows for sampling of a greater area than with divers

Washington, D.C.

Patent Tong Survey Created a grid over the oyster bar that was to be Bar CleanedCreated a grid over the oyster bar that was to be Bar Cleaned Conducted transects along grid lines with the Patent Tong boat.Conducted transects along grid lines with the Patent Tong boat. All Patent Tong grab locations were marked with a GPSAll Patent Tong grab locations were marked with a GPS All oysters collected were counted and measuredAll oysters collected were counted and measured

Patent Tong Survey Created a grid over the oyster bar that was to be Bar CleanedCreated a grid over the oyster bar that was to be Bar Cleaned Conducted transects along grid lines with the Patent Tong boatConducted transects along grid lines with the Patent Tong boat All Patent Tong grab locations were marked with a GPSAll Patent Tong grab locations were marked with a GPS All oysters collected were counted and measuredAll oysters collected were counted and measured

What is GIS? GIS is a computer system capable of assembling, storing, manipulating, and displaying geographically referenced information (spatial data).

GIS Oyster Bar Population Estimates Raw patent tong data = number of oysters per sampling pointRaw patent tong data = number of oysters per sampling point Oyster bar population was estimated using Inverse Distance Weighting (IDW) interpolationOyster bar population was estimated using Inverse Distance Weighting (IDW) interpolation

Initial Population Estimates GIS Inverse Distance Weighting Interpolation of Patent Tong dataGIS Inverse Distance Weighting Interpolation of Patent Tong data GIS IDW Estimation (bu) Spaniards Point 358 Durdin98 Carpenter's Island 24

Bar Cleaning Important for oyster restoration in Maryland portion of the ChesapeakeImportant for oyster restoration in Maryland portion of the Chesapeake Removal of as many existing oysters as feasible from an oyster barRemoval of as many existing oysters as feasible from an oyster bar

Bar Cleaning Allows for destructive sampling of an oyster barAllows for destructive sampling of an oyster bar Three oyster bars were exhaustively dredgedThree oyster bars were exhaustively dredged Total number of bushels recovered was recordedTotal number of bushels recovered was recorded

Initial Population Estimates Bar Cleaning dataBar Cleaning data Leslie and DeLury ModelsLeslie and DeLury Models Bar Cleaning Removal (bu) D initial population (bu) L initial population (bu) Spaniards Point Durdin Carpenter's Island

Results Bar Cleaning Removal(bu) D initial population(bu) L initial population (bu) (bu) GIS initial population (bu) (bu) Spaniards Point Durdin Carpenter's Island Oyster Bar Population Estimates

Linear Fit D initial population (bu) = GIS initial population (bu) Summary of Fit RSquare RSquare Adj Root Mean Square Error Mean of Response2185 Observations (or Sum Wgts)3 Bivariate Fit of D initial population (bu) By GIS initial population (bu)

Results Bar Cleaning Removal(bu) D initial population(bu) L initial population (bu) (bu) GIS initial population (bu) (bu) Spaniards Point Durdin Carpenter's Island GIS initial population (bu) L initial population (bu) D initial population (bu) GIS initial population (bu) L initial population (bu) D initial population (bu) Correlation Matrix Oyster Bar Population Estimates

Future Direction Need more data (oyster bars)Need more data (oyster bars) Determine the relationship between oyster bar population estimates - bar cleaning and patent tong samplingDetermine the relationship between oyster bar population estimates - bar cleaning and patent tong sampling Any suggestions are welcomeAny suggestions are welcome

Acknowledgments Maryland Waterman’s Assoc.  Larry Simns, Jeff Baker Oyster Recovery Partnership The Paynter Lab