Maryland's Historic Oyster Bottom

Maryland's Historic Oyster Bottom

A Geographic Representation of the Traditional Named Oyster Bars


The oyster bottom described and depicted in this publication does not represent the official Natural Oyster Bars defined by statute in the Annotated Code of Maryland. As such, the charts and depictions shown within should not be construed as the boundaries of the current legal oyster bars. These depictions are representations of the historic bottom as charted prior to the present legally designated Natural Oyster Bars. For information concerning the legal oyster bar definitions, consult the Maryland Natural Resources Police Hydrographic Operations at DNR’s Matapeake Facility. Maryland Department of Natural Resources

This document presents a description and background for a newly created digital data file of the historic oyster bars of Maryland. These oyster bars are not the legally defined oyster bar boundaries of current Maryland law, but rather the traditional boundaries and names of the historic oyster bottom where generations of watermen have harvested oysters. This project has attempted to integrate all the available data sources into a single spatial data file. The rapid expansion of Geographical Information Systems (GIS) technology has allowed for the generation of a spatial (mappable) data set that can be viewed, used and updated on a personal computer. Printed output of this digital file is contained within this publication.

Before 1983, the legally defined oyster bars of Maryland (referred to by statute as "Natural Oyster Bars") were identified by name. These named oyster bars were a complex lot of approximately one thousand individual oyster bars. Their original codification came from an early 20th century survey by C.C. Yates. The location of oyster bars was originally based on local knowledge which was then verified and charted by the Yates survey. Oyster bar names came from local custom. The charts of this survey were the original legal basis for Maryland’s oyster bars. Over the years many additions, along with a few deletions of the originally charted oyster bars, were made to legally define oyster bottom.

The present locations and classifications of the legally defined "Natural Oyster Bars" were formally adopted in 1983. Extensive changes to the original charted bar boundaries were made, and coded numbers replaced names of individual oyster bars. These new legally defined "Natural Oyster Bar" boundaries were developed in an attempt to simplify the complex oyster bar boundaries of the historic oyster bar locations.

Of key interest today is that the original named oyster bar boundaries provide the best evidence of the location of the historic oyster bottom of Maryland. Examination of today’s oyster harvest clearly hows that much of what was classified as productive oyster bottom at the turn of the century is no longer capable of producing an economically viable harvest. An additional reason for maintaining knowledge of these named oyster bar locations is the fact that watermen still reference their harvest locations by the historic names. Maryland Natural Resources personnel also generate monitoring data based on the named oyster bars, because they are the best reference to true oyster bottom.

Charting and publication of the named oyster bars are not new issues. Natural Oyster Bar charts generated before 1983 demark the named bars. Other investigators have published valuable charts and listings of these locations. There is, however, great difficulty in clearly establishing a definitive listing of all named oyster bars, because the bar names and locations have been generated by local custom. Naming conventions and locations can be highly variable and are a key difficulty in assembly of this type of information.

Integration of the named oyster bar file in a digital GIS format allows for viewing and printing the oyster bars at any size or scale supported by the original accuracy of the data. The spatial data file also includes attribute data such as alternate names and bar size in acres. Another benefit of this format is that the map can be used in conjunction with other data files such as the shoreline of Chesapeake Bay or the bathymetry or bottom type of the bay. For the purposes of this publication, charts of all of the named oyster bars are included as an appendix. Tabular listings of the oyster bars with supplemental information are also included within the full document, the data found in Appendix D of the Md Oyster Bars publication (of particular interest may be the center coordinates for each oyster bar). The actual data file is still available for users through the Department of Natural Resources by contacting the Cooperative Oxford Laboratory at 410-226-0078 or by email

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