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Eastern Oysters

The shoreline of a body of water is surrounded by large clusters of oysters.

The Eastern oyster (Crassostrea virginica) occurs in coastal waters of the Atlantic Ocean and Gulf of Mexico, from Canada to Mexico. These bivalves are primarily found in areas in estuaries, brackish water occurs where fresh water from tidal creeks and rivers meets saltwater from the Gulf and ocean.

There are several other oyster species in the state of Florida, including the flat-tree oyster, radial purse oyster, and Atlantic thorny oyster. 

Ecosystem Services

Reef structures formed are formed by both living oysters and their shells. These reefs are complex and provide refuge for hundreds of other species, including the juvenile stages of several species of fishes, which is why oysters are considered a foundation species. The biodiversity and high abundance of prey on the reefs also supplies a food source for larger predators. These reefs also act as a protective barrier to the shoreline by reducing erosion from wave action.  Oysters are filter-feeders and can clean large volumes of water over a relatively short period. By removing chemicals and other pollutants in the water oysters improve the surrounding water quality.

Oysters as food

The bulk of eastern oyster harvesting in Florida occurs on the Gulf coast, primarily in the Panhandle and Big Bend regions. Many coastal communities were built on harvesting oysters. Historically, fishers from Apalachicola harvested over 90% of the oysters sold in Florida and 10% of the nationwide supply.  Today, harvest of oysters has fallen around the state to about 10% of the average annual landings that occurred from 1990 – 2012, and the number of counties where oysters are harvested has declined by half since the 1980’s. There’s a growing interest in oysters as an aquaculture product due to the declining wild populations.

Molluscan Fisheries Publications - Eastern Oysters
Eastern oyster research publications.

Eastern Oyster Biology

The Eastern oyster is a keystone species, which provides essential habitat for many different organisms - large and small. 

Low view of a shoreline covered in oyster shells with mangrove roots and trees in the background.
A man sits on the edge of a boat that is floating in the water holding two long strings.

Monitoring Metrics

Fish and Wildlife Research Institute (FWRI) biologists conduct a variety of monthly, quarterly, and annual population monitoring that includes reproductive development, juvenile spat settlement, disease prevalence and intensity, condition index, oyster density, and adult oyster mortality.  Monitoring projects vary depending on goals including monitoring the fishery, working with restoration partners, and oysters serving as indicators of healthy ecosystems.

Regional Work

View of a shoreline next to the water that is bordered by mangrove trees and many clusters of oysters.

One of the goals of the Comprehensive Everglades Restoration Plan (CERP) is to manage water quality within south Florida estuaries. Oysters are included in this monitoring program as a target species because of their wide distribution, historical context, and essential habitat value.


View down a strip of land running into a body of water that is covered in oysters.

Historically most oysters harvested in Florida came from Apalachicola Bay. Currently the Suwannee Sound – Cedar Key region provides much of the harvest in Florida and is also a leader in aquaculture development. In 2021, FWRI received grants from the National Fish and Wildlife Foundation (NFWF) and Florida Trustee Implementation Group (TIG) to fund two projects in the Suwannee Sound – Crystal River area. Oyster survey, recruitment, and water quality monitoring data from the TIG project will contribute to the development of a map-based habitat suitability index for oysters. This will show what areas are most likely to support oysters based on environmental conditions and be a useful tool for guiding future restoration projects. 

A group of at least two dozen oysters sit on a white deck with a blue ruler in the middle.

In 2012, the federal government declared a fishery disaster in Apalachicola Bay. In 2015, FWRI received permanent funding from state revenue for an oyster monitoring program as well as supplemental funding related to the disaster declaration. These funds allowed for additional staff and start-up funds for equipment and outfitting a laboratory in Eastpoint, Florida. Biologists then began monitoring the oyster populations in Apalachicola Bay.