PRELIMINARY COMPARISON OF GEOGRAPHIC PRELIMINARY COMPARISON OF GEOGRAPHIC INFORMATION SYSTEM (GIS) ANALYSIS OF INFORMATION SYSTEM (GIS) ANALYSIS OF

PATENT TONG AND BAR CLEANING OYSTER PATENT TONG AND BAR CLEANING OYSTER POPULATION ESTIMATES IN THE UPPER POPULATION ESTIMATES IN THE UPPER

CHESAPEAKE BAYCHESAPEAKE BAY

Allen, S, H. Lane, J. Goodwin, M. Chen, M. L. Kellogg, Allen, S, H. Lane, J. Goodwin, M. Chen, M. L. Kellogg, K. T. PaynterK. T. Paynter

MEES Program, 0105 Cole Field House, University of Maryland, MEES Program, 0105 Cole Field House, University of Maryland, College Park, MD 20742 College Park, MD 20742

IntroductionIntroduction

• Oysters are of vital importance to the Oysters are of vital importance to the health of the Chesapeake Bayhealth of the Chesapeake Bay

• Oyster abundance in the bay has been Oyster abundance in the bay has been on the decline since the late 1800’son the decline since the late 1800’s

• Currently, there is no standard method Currently, there is no standard method for population estimationfor population estimation

Goal: Pilot StudyGoal: Pilot Study

Explore methods of oyster population Explore methods of oyster population estimationestimation

ObjectivesObjectives

• Ground truth patent tong sub-sampling Ground truth patent tong sub-sampling

• Estimate & compare oyster bar Estimate & compare oyster bar populations using two methods populations using two methods (Leslie/DeLury and GIS)(Leslie/DeLury and GIS)

• Determine the feasibility & reliability of Determine the feasibility & reliability of estimates based on patent tong estimates based on patent tong samplingsampling

Patent TongingPatent Tonging

• Modern method of Modern method of oyster harvestingoyster harvesting

• Allows for sampling Allows for sampling of a greater area of a greater area than with diversthan with divers

Washington, D.C.Washington, D.C.

Patent Tong SurveyPatent Tong Survey

• Created a grid over the oyster bar that Created a grid over the oyster bar that was to be Bar Cleanedwas to be Bar Cleaned

• Conducted transects along grid lines Conducted transects along grid lines with the Patent Tong boat. with the Patent Tong boat.

• All Patent Tong grab locations were All Patent Tong grab locations were marked with a GPSmarked with a GPS

• All oysters collected were counted and All oysters collected were counted and measured measured

Patent Tong SurveyPatent Tong Survey

• Created a grid over the oyster bar that Created a grid over the oyster bar that was to be Bar Cleanedwas to be Bar Cleaned

• Conducted transects along grid lines Conducted transects along grid lines with the Patent Tong boatwith the Patent Tong boat

• All Patent Tong grab locations were All Patent Tong grab locations were marked with a GPSmarked with a GPS

• All oysters collected were counted and All oysters collected were counted and measured measured

What is GIS?What is GIS?

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

GIS Oyster Bar Population GIS Oyster Bar Population EstimatesEstimates

• Raw patent tong data = number of Raw patent tong data = number of oysters per sampling pointoysters per sampling point

• Oyster bar population was estimated Oyster bar population was estimated using Inverse Distance Weighting (IDW) using Inverse Distance Weighting (IDW) interpolationinterpolation

Initial Population EstimatesInitial Population Estimates

• GIS Inverse Distance Weighting Interpolation GIS Inverse Distance Weighting Interpolation of Patent Tong dataof Patent Tong data

GIS IDW GIS IDW Estimation Estimation

(bu)(bu)

Spaniards Spaniards PointPoint 358358

DurdinDurdin 9898

Carpenter's Carpenter's IslandIsland 2424

Bar CleaningBar Cleaning

• Important for oyster Important for oyster restoration in restoration in Maryland portion of Maryland portion of the Chesapeake the Chesapeake

• Removal of as many Removal of as many existing oysters as existing oysters as feasible from an feasible from an oyster baroyster bar

Bar CleaningBar Cleaning

• Allows for destructive sampling of an Allows for destructive sampling of an oyster baroyster bar

• Three oyster bars were exhaustively Three oyster bars were exhaustively dredgeddredged

• Total number of bushels recovered was Total number of bushels recovered was recordedrecorded

SPANIARD POINT BAR CLEANING EFFORT

0

10

20

30

40

50

60

0 2 4 6 8 10 12 14 16

Days

CPUE (bushels/boat-day)

Series1

Initial Population EstimatesInitial Population Estimates

• Bar Cleaning dataBar Cleaning data

• Leslie and DeLury ModelsLeslie and DeLury Models

Bar Cleaning Bar Cleaning Removal Removal

(bu)(bu)

D initial D initial population population

(bu)(bu)

L initial L initial population population

(bu)(bu)

Spaniards Spaniards PointPoint 30773077 35343534 32983298

DurdinDurdin 580580 17421742 675675

Carpenter's Carpenter's IslandIsland 544544 12791279 799799

ResultsResults

  

Bar CleaningBar CleaningRemoval Removal

(bu)(bu)

D initialD initialpopulation population

(bu)(bu)

L initialL initialpopulationpopulation

(bu)(bu)

GIS initialGIS initialpopulationpopulation

(bu)(bu)

Spaniards Spaniards PointPoint 30773077 35343534 32983298 358358

DurdinDurdin 580580 17421742 675675 9898

Carpenter's Carpenter's IslandIsland 544544 12791279 799799 2424

Oyster Bar Population EstimatesOyster Bar Population Estimates

1000

2000

3000

4000

D initial population (bu)

0 100 200 300 400GIS initial population (bu)

Linear FitD initial population (bu) = 1098.8594 + 6.788379 GIS initial population (bu)

Summary of Fit

RSquare 0.999715

RSquare Adj 0.999429

Root Mean Square Error 28.45784

Mean of Response 2185

Observations (or Sum Wgts) 3

Bivariate Fit of D initial population (bu) By GIS initial population (bu)

ResultsResults

  

Bar CleaningBar CleaningRemoval Removal

(bu)(bu)

D initialD initialpopulation population

(bu)(bu)

L initialL initialpopulationpopulation

(bu)(bu)

GIS initialGIS initialpopulationpopulation

(bu)(bu)

Spaniards Spaniards PointPoint 30773077 35343534 32983298 358358

DurdinDurdin 580580 17421742 675675 9898

Carpenter's Carpenter's IslandIsland 544544 12791279 799799 2424

11----GIS initial population GIS initial population (bu)(bu)

0.96780.967811--L initial population L initial population (bu)(bu)

0.99990.99990.97190.971911D initial population D initial population (bu)(bu)

GIS initial population GIS initial population (bu)(bu)

L initial population L initial population (bu)(bu)

D initial population D initial population (bu) (bu)

Correlation MatrixCorrelation Matrix

Oyster Bar Population EstimatesOyster Bar Population Estimates

Future DirectionFuture Direction

• Need more data (oyster bars)Need more data (oyster bars)

• Determine the relationship between Determine the relationship between oyster bar population estimates - bar oyster bar population estimates - bar cleaning and patent tong samplingcleaning and patent tong sampling

• Any suggestions are welcomeAny suggestions are welcome

AcknowledgmentsAcknowledgments

Maryland Waterman’s Assoc.Maryland Waterman’s Assoc. Larry Simns, Jeff BakerLarry Simns, Jeff Baker

Oyster Recovery PartnershipOyster Recovery Partnership

The Paynter LabThe Paynter Lab

DeLury Plot for Spaniards Point Oyster Bar

y = -0.0206x + 4.2879

R 2 = 0.9837

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 20 40 60 80 100 120 140 160

Cumulative Effort (boat-day)

ln CPUE (bushels/boat-day)

Spaniards Point

Leslie Plot for Spaniards Point Oyster Bar

y = -0.0219x + 72.235

R2 = 0.9405

0

10

20

30

40

50

60

70

0 500 1000 1500 2000 2500 3000 3500

cumulative catch (bushels)

CPUE (bushels/boat-day)

Spaniards Point