Home » Uncategorized » Fisheries in Transition: The Oyster Fishery

Fisheries in Transition: The Oyster Fishery

For centuries people have looked upon oysters as an important food source and the elite considered it a delicacy. Though, there are other reasons that they were prized.Oysters have, apparently, always been linked with love.Aphrodite, the Greek goddess of love, sprang from the sea on an oyster shell and bore Eros, thus the word “aphrodisiac” was born. In later centuries, the great lover Casanova was said to start a meal by eating twelve dozen oysters to ready him for the night’s pleasures.In the fossil record oysters appeared during the Triassic period about 200 million years ago and have been an important food source for man since the new Stone Age.The Chinese have raised oysters in ponds for centuries. In 320 B.C. Aristotle speculated in his writing of the ‘Historia Animalium’ that oysters were spontaneously generated from slime. At that time the Greeks served them with wine and the Romans loved then so much that they sent thousands of slaves to the English Channel to collect them. Some Roman emperors were said to pay for them, ounce for ounce, in gold.The oyster we have in Alabama is the eastern oyster (Crassostrea virginica). They are filter feeders and consume algae and other water borne foods by filtering water at a rate of up to five liters per hour. When the oyster beds were in their natural untouched state scientists believe that Mobile Bay’s oysters served as a natural water filtering system that turned over the volume of the bay every few days.The oysters are collected from their beds on the oyster reefs with manually operated tongs. The oystermen work the reefs in small boats, measure the shells for legal size, bag them and haul them into shore.The eastern oyster usually lives in water between 8 and 25 feet. Oysters start spawning in the spring when the water temperature rises above a certain level and again in the early fall when it falls below that point. This triggers a chain reaction of spawning, which clouds the water with hundreds of millions of eggs and sperm. Their free-swimming larvae are called spat which settle on any hard substrate, but they prefer oyster shells. Oysters are hermaphrodites, which change sex when there isn’t enough of the opposite sex around to provide for enough spawn.Oysters mature at an early age (one year). A single female oyster produces 10 to 100 million eggs annually. Over time, as the oysters live and die their shells from reefs with many nooks and crannies that have fifty times the surface area of flat bottom. These reefs provide habitat for a wide range of animals like worms, snails, juvenile crabs, and fish.A common rule of thumb has been to eat oysters only in months that have an “R” in their name. This was during cold weather that prevented spoilage. With refrigeration the danger of decay and food poisoning has been all but eliminated. In ‘non-R’ months oyster tend to be on the flaccid side because they have spent all their stored energy on spawning.Because oysters are filter feeders they take in, along with their food, whatever else is in the water. Because of septic tanks, sewage overflows and runoff from farms the health department closes the oyster reefs when the fecal coliform count gets too high.Hurricanes scour the reefs with their strong currents and wipe off any oysters along with the old shell that is need for the oyster larvae to settle on. These two factors have resulted in highly variable production. From 1950 to 2005 commercial oyster harvest ranged from two million pounds of meat in 1950 to 11 thousand pounds in 1989.Mariculture of oysters had been going on for centuries. In the last 30 years it has intensified to keep up with the increasing demand and the unstable and declining natural harvest.With increased concerns over contamination, uncertain availability and environmental decline the future of the commercial oyster fishery is uncertain. There will always be a local natural harvest fresh market. But, if these trends are not reversed mariculture of the oyster with replace the large-scale natural harvest in the coming years.

Think Global – Act Local!

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

w

Connecting to %s