Key Questions and Current State of Knowledge

The current project began with five questions:

i.  Can we develop guidelines for shell management from first principles?

ii.  Can we test them against extant reef systems that exhibit stability?

iii.  Can we map current stable systems and use them as management reference points to guide future actions?

iv.  Can we make such data and guidelines widely available to aid federal, state and non-profit efforts to restore and stabilize oysters in the Chesapeake Bay?

v.  Can we present the current state of the Virginia Bay oyster habitat in a single, coherent report that tracks the past decade and sets the stage for activity in years to come?

At the outset we proffered the position that the answer to all these questions is yes. The objective of the proposed effort is to reach that goal. A brief review of our current knowledge provides an introduction to the work completed in this project and reported on here. Subjects are addressed in the numerical listing above.

       i.         Can we develop guidelines for shell management from first principles? Yes. Mann and Powell (2007) provided a discussion of the principles involved in developing dual reference points. Several reports focusing on the James River (Mann et al. 2009b), Great Wicomico River (Southworth et al. 2010) and the Piankatank River (Harding et al. 2010) use an “accounting” procedure based on mortality estimates to generate reef specific shell budgets for limited periods based on long term oyster stock assessment data collected in VMRC-VIMS collaborative studies. Mann et al. (2009a) use a theoretical approach based on virtual oyster populations and rates of sea level rise to estimate oyster population demographics and shell production rates that would be required for stable reef structures over periods of decades to centuries. Recently Powell at al. (2012) provided a more complex model of reef accretion and loss including a feedback loop that decreases shell loss rates when shell resources are low – a preservative mechanism. Soniat et al. (in press) present a working example of a fishery management protocol based on no net shell loss for resources managed by the Louisiana Department of Fish and Wildlife. Collaborative assessment and experimental efforts with colleagues in Maryland, New Jersey and Louisiana are improving our understanding of how shell both accumulates and disappears in extant oyster reef systems.

     ii.         Can we test them against extant reef systems that exhibit stability? Yes, but this is not complete or up to date. We continue to use accounting approaches for selected reef systems that are assessed annually in joint VMRC-VIMS surveys (now at approximately 1650 samples annually covering 180 distinct reefs over 8900 acres in all the major Virginia sub estuaries of the Chesapeake Bay). What is missing from this analysis to date is to extend this analysis of temporal reef stability to the entire Virginia resource. This effort is described in the following report.

    iii.         Can we map current stable systems and use them as management reference points to guide future actions? Yes. The first Virginia Oyster Restoration Atlas was generated over a decade ago as a joint VMRC-VIMS effort with support from the US Army Corps of Engineers. This has been progressively updated in both paper form, with the most recent edition being printed in 2009, and on the World Wide Web. The effort is described on the VIMS Molluscan Ecology Restoration page which provides direct connection to the Map Atlas.  It also connects to the Virginia Oyster Stock assessment and Replenishment Archive, that provides more detailed information on a reef by reef basis of BOTH population and shell status. We now complete annual updates of both oyster and shell resources on a geo-referenced GIS layer that the user can peruse at various levels of enquiry.

    iv.         Can we make such data and guidelines widely available to aid federal, state and non-profit efforts to restore and stabilize oysters in the Chesapeake Bay? Yes. The Map Atlas and VOSARA sites are the bases of the process. In this site we comprehensively describe current survey and research methods that are the foundation of our long term restoration focused effort, present them in a format compatible with world wide web presentation, and offer a simple planning and evaluation tool for field and management use.

     v.         Can we present the current state of the Virginia Bay oyster habitat in a single, coherent report that tracks the past decade and sets the stage for activity in years to come?  Yes. There has not been a single, comprehensive overview document addressing the Virginia oyster resource since the landmark volume by Haven, Hargis and Kendall (1981). In the following we present a summary of our quantitative stock assessment surveys since their initiation in 1993. 

Link to Data Collection and Archive