WINTER/SPRING 2019 • VOLUME 41
motion. Tides and currents also move the larvae. Within a
month the larvae settle on the bottom to locate a hard, clean
surface for attachment. Other oyster shells are their favorite
surface. Oyster shells that are purposely placed to attract
oyster larvae are called “cultch.”
Larvae must find a clean surface for attachment, or they
will sink into the bottom and die. After attachment occurs,
the small oysters are known as spat. Oysters feed by filtering
food particles from the water. Large, healthy oysters can pump
nearly four gallons of water per hour through their gills,
which have an ability to separate silt from food particles. This
process can also remove various pollutants from the water.
Most oysters are either male or female, but
hermaphroditism also occurs. Like many fish and plants,
some oysters alternate their sex according to the season
or with changes in water temperature. This is known as
sequential hermaphroditism. Most intertidal oysters grow as
part of oyster clusters, with succeeding generations attaching
to former ones. Clusters can reach a foot in thickness, but
only the outermost oysters survive. Eventually, the lowest
oysters will be pushed into the mud and suffocate. It takes
about three years for oysters to reach harvestable size in
South Carolina. Harvesting is done by hand at low tide, and
harvesters are encouraged to leave smaller oysters in place so
they can reach maturity.
A New York nonprofit has undertaken a project to rebuild
oyster reefs that will clean the polluted New York Harbor and
revive its ecosystem. Since 2014 the Billion Oyster Project has
restored about 30 million oysters to local waters. Although
that is only a small fraction of the original reefs, it is still
significant. In 2018 the number of wild oysters that attached
to Billion Oysters Project’s reefs increased dramatically. This
needs to occur for the restoration project to succeed.
Over 70 New York City restaurants partner with the Project
by saving their oyster shells rather than tossing them. A
collection partner for the Project carts them off to Governors
Island, a small island near the Statue of Liberty. The shells
are left there for at least a year, allowing the elements to
cleanse them of organic matter naturally. Then they are sent
to the New York Harbor School, a maritime-focused public
high school on Governors Island, where students hatch baby
oysters and attach them to the cleaned shells. The shells and
larvae are then placed off New York’s coastline. At this point,
the Billion Oyster Project has created 12 reefs, some close to
shore and others in deeper waters.
Virginia and Maryland initiated a similar project in 1994.
It has met with great success in restoring much of the former
oyster population. These small creatures are amazing. Not
only do they provide culinary delight, but they also contribute
significantly to the health of our maritime ecosystem. NK
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