Basic Oyster Facts

Here are some oyster basics:

The native eastern oyster, Crassostrea virginica, usually lives in water depths of between 8 and 25 feet and naturally forms three-dimensional intertidal reefs.




An oyster orients itself with the flared edge of its shell tilted upward. The left valve is cupped, while the right valve is flat. The shell opens periodically to permit the oyster to feed on plankton.




Oysters usually mature by age one. They are protandric, which means that in the first year they spawn as males, but as they grow larger and develop more energy reserves in the next two to three years, they spawn as females.

An increase in water temperatures triggers the male oyster to release sperm and the female to release eggs into the water. This triggers a chain reaction of spawning which clouds the water with millions of eggs and sperm. A single female oyster produces 10 to 100 million eggs annually.



The eggs are fertilized in the water and soon develop into larvae, or veligers, which are drawn to the chemicals released by older oysters on the bottom. Oysters need to settle in a suitable spot, such as another oyster’s shell. Juvenile attached oysters are called “spat.”


BACK TO A VIRGINIA OYSTER LOVERS PARADISE HOMEPAGE:

Oysters Carry a Special Promise

A single oyster filters as much as 50 gallons of water per day.

Oysters are delicious to our taste buds, economy and environment. This is the take-home message of a three-page profile of oystering in the current year-end special issue of the authoritative Economist magazine.

Still a big deal in Willapa and Netarts bays, oysters offer some surprising benefits, as The Economist makes clear. Primarily focusing on Chesapeake Bay on the Atlantic Coast, this article heightens our feelings of gratitude and protectiveness for oystering as it is practiced around here.

For one thing, oystermen in the Chesapeake have always relied on a sort of natural propagation process and public ownership of oyster beds. In contrast, here on the West Coast the practice has been to proactively farm-raise oysters on privately owned or leased grounds. Our relatively sophisticated aquaculture techniques are now being taken up in Maryland, where oysters are increasingly being recognized as playing a critical role in purifying water.

A senior scientist on the Chesapeake told The Economist, "The oyster is pretty particular about what it eats, but it's not particular about what it filters." This means that water contaminants, especially things like nitrogen-based fertilizers, are taken out of the water column by oysters and processed back into a form that returns to the atmosphere. Phytoplankton that oysters eat would otherwise die and be consumed by bacteria, which use up oxygen needed by fish and crab. A single oyster filters up to 50 gallons of water a day.

All is not well for Oregon and Washington oysters. Changes in ocean chemistry, climatic conditions and possibly other factors are making it harder to grow fat and healthy oysters here. There hasn't been a robust natural reproductive seed-set process in nearly five years in Willapa Bay. We're obviously better off here than in Chesapeake, where the oyster population stands at only one percent of its pre-1980 level. But we still need to get our scientific and political assets fully engaged in making sure that oysters remain a key part of our economy and gastronomy.

"Oyster farming," the magazine noted, " is one of the few situations in which both economics and the environment win."

BACK TO A VIRGINIA OYSTER LOVERS PARADISE HOMEPAGE: