A. Fishery Independent data - These data are derived from the annual dredge survey conducted by the Maryland Department of Natural Resources. An oyster dredge, 30 inches wide and 18 inches tall, is deployed from the R/V Miss Kay. Two tows are made with the dredge, averaging about 230 feet in length. A half bushel of oysters is retained from each the two tows, and then measured to provide length-frequency data as well as oysters for disease diagnostics.

B. Fishery Dependent data
B1. Public/Commercial fishery - These data are based on the annual oyster landings as reported to the Maryland Department of Natural Resources Fisheries Statistics Division. One bushel of oysters was assumed to contain 350, 3.5 inch oysters. A market oyster is 3 inches or 76 mm from its beak to its hinge (shell length).
B2. Private fishery - Oysters harvested from leases are subject to harvest taxes like that of the public fishery. One bushel of oysters harvested was assumed to contain 350 market oysters.

C. Restoration Efforts
C1. Reefs - unexploited sanctuaries -These data are from dive surveys being conducted on constructed oyster reefs and within oyster sanctuaries by personnel from the University of Maryland.
C2. Replenishment areas - exploited shellplants and reefs - These data are from the annual replenishment reports produced by the Maryland Department of Natural Resources Shellfish Repletion program.

The amount of oysters produced by oyster gardeners in Maryland is small relative to those in Virginia. Thus, oyster gardening efforts have not been included in these calculations for Maryland tributaries.

Annual estimates of oyster populations within Maryland's basins made with these data categories are available for:

Annual basin estimates of oyster population numbers and biomass (g dry tissue) are useful for describing trends in Maryland's oyster population over time. View graph of Maryland oyster numbers and biomass in the period 1994-2002.