1. Role of oyster age vs. oyster size in determining sex ratios on restored oyster reefs in Chesapeake Bay
M. Lisa Kellogg, Marcy E. Chen, Victor S. Kennedy, C. Paul Miller,
Sara E. Rowland, Richard T. Paynter, Kennedy C. Paynter,
Nancy J. Ward, Dawn Goldsmith, Mark W. Sherman, Jacob D. Goodwin, Christopher P. McIntyre, Steven Allen and Kennedy T. Paynter

2. Oyster Reef Restoration in Maryland:
Oyster Recovery Partnership coordinates oyster reef restoration efforts in MD portion of Chesapeake Bay
MDNR, MD Watermen’s Association, ACOE, UMD and various NGOs (e.g. CBF)
In recent years, sanctuaries and managed reserves have been planted annually in Maryland
Sanctuaries focus on ecological restoration
Managed reserves focus on fishery rehabilitation
Almost all spat are produced from wild stock at HPL
Planted as spat on shell
Planted in discrete year classes (i.e. same location rarely planted in subsequent years)

3. Sex Ratios in Oyster Populations:
Oysters are protandric
Generally male when they first mature
Proportion of females increases with increasing age/size
Previous studies found a greater proportion of females associated with:
Increasing distances between individuals (Burkenroad 1931)
Single oysters vs. clumps (Smith 1949)
Settlement on shell vs. settlement on adult oysters (Menzel 1951)

4. Questions: What are the sex ratios of oysters on planted reefs in MD?
Do they exhibit the same patterns as previously studied populations?
What can sex ratio patterns on plantings tell us about possible factors influencing sex ratio patterns of oysters in general?
What are the implications for oyster reef restoration efforts?

5. Questions: What are the sex ratios of oysters on planted reefs in MD?
Do they exhibit the same patterns as previously studied populations?
What do sex ratio patterns on plantings tell us about possible factors influencing sex ratio patterns of oysters in general?
What are the implications for oyster reef restoration efforts?

6. Oyster Reef Restoration in Maryland:
Unique opportunity to examine the relationship between sex ratio and oyster age and/or size in the field
All oysters sampled have similar history
Spat on shell from HPL Hatchery
Known planting dates
Monitoring records show that there has been no significant natural recruitment
Estimates of oyster age are not confounded
No need to use oyster size as a proxy for oyster age

7. Sampling Sites: Magothy River Chester River Choptank River
Chest Neck Point
Chester River
13 sites
Choptank River
12 sites

8. Chester River: Boathouse Emory Hollow Devil’s Playground Strong Bay
Blunts
Devil’s Playground
Chester River:
Boathouse
2005
Emory Hollow
2001, 2002, 2004
Devil’s Playground
Strong Bay
2003 (2), 2004, 2005
Blunts
2002, 2003, 2005 (2)

9. Choptank River: Howell Point Green Marsh Shoal Creek Bolingbroke Sand
Mill Dam
Dixon
The Black Buoy
Bolingbroke Sand
Shoal Creek
Green Marsh
Howell Point
Choptank River:
Howell Point
2001
Green Marsh
2003
Shoal Creek
2001, 2004, 2005
Bolingbroke Sand
2002, 2003, 2005
The Black Buoy
2004, 2005
Dixon
2005
Mill Dam

10. Field Sampling: Quadrat grabs by divers Goal: Actual:
30 cm x 30 cm quadrat = 0.09 m2
All shell material in quadrat collected
Goal:
Minimum of 50 oysters/site
Minimum of 3 quadrats/site
Actual:
39 – 291 oysters collected/site
3 – 22 quadrats collected/site
2214 oysters collected in total

11. Sample Processing: All oysters collected were individually labeled
Data collected:
Shell height (mm) of all oysters
Distances between the ventral shell margins of all oysters in each clump
Sex of all oysters determined by microscopic examination of gonad smears

12. Resulting Data: Individual oyster sex Individual shell heights
Planting year
# of oysters/quadrat
# of oysters/clump
# of single oysters
Distance to nearest neighbor
Distance to nearest neighbor of opposite sex

13. Resulting Data: Individual oyster sex Individual shell heights
Planting year
# of oysters/quadrat
# of oysters/clump
# of single oysters
Distance to nearest neighbor
Distance to nearest neighbor of opposite sex

14. “Natural” Oyster Bars

15. All Oysters – All Sites

16. All Oysters – All Sites

17. 1 Year After Planting

18. 2 Years After Planting

19. 3 Years After Planting

20. 4 Years After Planting

21. 5 Years After Planting

22. “Natural” Oyster Bars

23. Low n for Largest Size Classes

24. Future Directions: Detailed analysis of all current data
Determine influence of other measured factors (e.g. # of oysters/quad, average distance to nearest neighbor, etc.)
Include more info on planting history (e.g. density at time of planting, growth rates, mortality rates, disease history)
Formulate testable hypotheses about factors driving observed patterns
Additional data collection in 2007:
Target bars with older plantings to increase the sample sizes in the larger size classes
Sampling of “natural” oyster bars in vicinity of plantings

25. Charlie Frentz, Director “Mutt” Meritt and Hatchery Crew
Acknowledgements:
Oyster Recovery
Partnership
Charlie Frentz, Director
“Mutt” Meritt and Hatchery Crew