Program Info

The Oyster Technical Working Group (TWG) was formed after the Deepwater Horizon oil spill to design work plans for monitoring oyster resources in the northern Gulf of Mexico. It included experts and trustee agency and BP representatives. The Oyster TWG conducted quadrat sampling in Louisiana, Alabama, Mississippi and Florida from 2010 through the spring of 2014 (and in Alabama only in 2015) to assess injury to and potential recovery of oyster resources.
Counts of live and dead oysters in three size categories per 0.25m^2 or per 1m^2 (spat, 10-25mm; seed, 25-75mm; market, >75mm); counts of other species per 0.25m^2 or per 1m^2; oyster shell height (mm); oyster biomass by size category (g/0.25m^2 or g/1m^2)
To find the oyster quadrat abundance datasets in the DIVER database, search for the keyword "oyster" and filter results by the "samples" data category. Note that oyster size data from 2010 and 2011 were excluded from the edited files for SEACAR because they were collected by dredge or for other purposes than abundance sampling (e.g., gonadal development and disease assays). Sample locations with coordinates outside of a managed area, but within 5m of a managed area boundary were considered within the managed area (and their corresponding points are shown within the managed area boundary on all SEACAR maps).
Public databases, NRDA technical reports, scientific publications, Final Programmatic Damage Assessment and Restoration Plan and Final Programmatic Environmental Impact Statement
Quadrat sampling locations chosen based on both historical sampling and previously randomly selected areas. At each sample location four haphazardly placed 1m^2 or 0.25m^2 quadrats were assessed, except for nearshore/intertidal surveys, for which quadrat placements were selected as random distances along transects perpendicular to the shoreline. All oyster material was collected within the quadrat area down to 3-4cm into the reef. The samples were kept on ice until processing when the abundance of oysters 10-25mm (spat), 25-75mm (seed) and >75mm (market) was enumerated. Sizes were verified with rulers and calipers. The process was repeated for live and dead oysters. The shell heights of the first 20 randomly selected oysters in each size category were measured to the nearest mm. Other associated species were also enumerated (#/1m^2 or #/0.25m^2). Each sorted category was also weighed to produce biomass estimates (g/1m^2 or g/0.25m^2).
2015 sampling was conducted only in Alabama.
Data Location
Data Format
Oyster/Oyster Reef
SEACAR Citation
NRDA Oyster Technical Working Group. (2014). Deepwater Horizon NRDA Oyster Technical Working Group Oyster Quadrat Abundance Sampling. Updated 09/17/2020. Distributed by: SEACAR Data Discovery Interface, Office of Resilience and Coastal Protection, Florida Department of Environmental Protection.
Alternative Citation

indicates priority attributes


Export Standardized Data

Habitat(s) : Indicator(s) Last Updated File Download
Oyster/Oyster Reef : Density, Size Class 07/08/24 02:34 PM Download File - Oyster -
DIP Document N/A Download File - DIP

Office of Resilience and Coastal Protection Managed Areas

Apalachicola Bay, Apalachicola NERR, Yellow River Marsh


Oyster/Oyster Reef - Density
Oyster/Oyster Reef - Size Class
Oyster/Oyster Reef - Additional Indicators

Documentation and Data provided by program

File Type File Name Added On Details
Data 05/05/20 06:19 PM View Details
Data AllOysterTWG_SRDedit_AB.xlsx 06/17/20 07:52 PM View Details
Data AllOysterTWG_SRDedit_SH.xlsx 06/17/20 07:52 PM View Details
Protocols NRDA_OysterTWG_QuadSizes.xlsx 06/17/20 07:52 PM View Details
Protocols 05/05/20 06:19 PM View Details