Oyster

The American or Eastern oyster, or Crassostrea virginica, is found intertidally and subtidally in estuaries (sounds, bays, bayous, tidal creeks) from Brunswick, Canada through the Gulf of Mexico.

Biology

Bivalve mollusk with two asymmetric shells attached at hinge. Shell weight and shape vary greatly depending on age, location and growing conditions. Shell color usually gray-brown. Left shell, attached to substrate, is usually more deeply cupped. Muscle scar purple in color and found inside the shells where adductor muscle attaches.

Oysters are filter feeders and capture phytoplankton, dissolved organic material and other appropriately sized particles from the water column as food. Adults accumulate glycogen reserves (fatten) during the winter months and develop ripe gonads during early-late spring. Rising coastal water temperatures stimulate external spawning of eggs and sperm by adults generally in the late spring/early summer. Planktonic, swimming life stages include trochophore larvae, which develop within the first 24 hrs after fertilization, then into shelled, veliger stages (D-hinge, umbo, late umbo and pediveligers). Tides and currents carry the larvae throughout the estuary for 12-21 days until pediveligers settle and crawl to find suitable hard substrate to attach and undergo metamorphosis into sedentary stage (spatfall). Spat (<1 inch) grow to seed (>1) and adult sizes (>2) with increasing shell size. Adults form vast reef communities providing critical estuarine habitat.

Oysters are euryhaline and can survive in nearly freshwater, but salinities <10ppt inhibit gonadal development. Spatfall increases with increasing salinity, but predation and disease stymie recruitment to seed and adult sizes above 15ppt, depending on location within the estuary.

 

Read more below, or download our fact sheet: Guide to Buying Live Oysters

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whole oysters spilling out of canvas sack

Market size is generally >3 inches, but varies by state and harvest/farming method and market demand. Generally served raw on the half-shell and lightly cooked in many recipes.

 

Live or raw oysters can be purchased in sacks, mini-sacks and by count (dozen). When purchasing live unshucked oysters, make sure the commercial fisherman or processor is properly licensed to sell and a harvest tag is attached to the sack or stamped on the box to trace origin.

 

General Tips:

  • Throw out any oysters with open shells
  • Refrigeration temperature must be 45o F or less
  • Live oysters should be consumed or frozen within 7-10 days from initial harvest 

After purchase, move your live oysters directly to an ice chest for safe transporting. 

To safely transport: 

  1. Start by adding a layer of ice in the bottom of the chest. 
  2. Place a layer of oysters on the ice. 
  3. Add alternating layers of ice and oysters. 
  4. Finally, add a good layer of ice on top. 

 

Be sure to open the plug and prop the ice chest so that water runs out. Oysters should not be in standing water at any time. Additional ice should be added as needed. 

Taste The Difference When It’s Fresh From The Sea