OYSTER FARMING ON THE KNYSNA LAGOON

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Oysters have been the favourite of gourmets and romantics for thousands of years. The ancient Chinese are thought to have been the first to cultivate them, the Greeks were doing it 6 000 years ago and the Red Indians of North America invented the oyster stew. We know that the Romans were crazy about them - they were required eating at every reputable Roman orgy. And that Casanova, history's greatest lover, owed his ability in the boudoir to them.

... Today they're more popular than ever before.

The Oyster is probably Knysna's favourite delicacy and its best-known export. No visit to South Africa's Favourite Town would be complete without a plateful of them - and it is also an important part of the economy of the Knysna Lagoon.

THE ZOOLOGICAL STUFF

CLASSIFICATION

Oysters are classed as bivalves (each half of the double shell is called a 'valve'). They usually live on rocks in densely packed colonies in the intertidal zone of the sea shore. At high tide they open their shells and feed by filtering water through their gills: when the tide ebbs again, they close their shells, trapping enough water to prevent dehydration.

Oysters species indigenous to the Southern Cape include:

• Red Oyster (Ostrea atherstoni) - found along the coast between Algoa Bay and False Bay;
• Weed Oyster (Ostrea algoensis) - also found between Algoa Bay and False Bay;
• Pearl Oyster (Pinctada capensis) - produces true pearls, and is found between Algoa Bay and False Bay;
• Common Rock Oyster or the Coastal Oyster (Crassostrea margaritacea) - edible, usually eaten raw, and found between the Transkei and False Bay;
• Saccostrea cuccullata - similar in taste to the imported Pacific Oyster;
• Ostrea atherstonii - edible but usually eaten cooked.

REPRODUCTION - THE OYSTER'S, THAT IS!

Oysters reproduce during the summer months by releasing eggs and sperm into the sea in a process known as 'spawning.' The average female oyster can produce up to 150 million eggs per season. After fertilization - a somewhat random affair - the eggs develop into larvae which can swim within about 20 hours and which will continue to move freely for about three weeks. During this time they feed on plankton, bacteria and decaying organic matter. In the later stages of the larval period, a light and gravity sensitive 'eyespot' - made up of fine hairs or 'cilia' - develops. This eyespot is used for selecting a suitable place to settle. The larvae also develop a 'foot' with which they attach themselves to the substrate.

Once they're attached the larvae become known as 'spats' and begin to manufacture their shells by binding calcium and carbonate collected from the sea water. In the normal course of events, the oyster will spend the rest of its life in the same spot and will never move again.

In oyster farming, however, it will travel quite often before it makes its final journey to the dinner table.

OYSTER FARMING IN KNYSNA

First experiments with cultivated oysters began in Knysna in 1946, and in 1948 the Knysna Oyster Company was formed as a joint venture between the Fisheries Development Corporation and Thesen & Co. - a large local business with interests in saw-milling, plantations, shipping and farming. A Dutch farmer, a Mr van Dort, was the Company's first employee. He began to farm using the same methods as those developed in Holland, with oysters imported from Britain, Australia and Portugal. His first oyster beds were built with asbestos roofing tiles in Featherbed Bay, but the presence of octopuses, mussel crackers, oyster drills, starfishes, flatworms and blister worms doomed the experiment to failure.

The Company experimented with many different rack designs, different sites in the lagoon and different species of oyster. All were commercially unsuccessful until, during the 1970's, the Pacific Oyster (Crassostrea gigas) was found to be the perfect species for production in this Lagoon. Their growth rate (they reach harvestable size at 18 months) and taste were exactly suited to the South African market. Oyster beds were established in the area between Belvedere and The Point, and between Brenton-on-Lake and the railway bridge, and production began in earnest.

OYSTER FARMING TODAY

The Knysna Oyster Company now farms 16 hectares of the Knysna Lagoon using the intertidal rack system. Its oysters are well-travelled - they're imported as spats from hatcheries in Chile and France when they're about three months old and about 3 to 4 mm in size. They begin their South African careers in Port Elizabeth where the excellent quality of water in Algoa Bay ensures that they quickly outgrow their nursery. They're then transferred to the Knysna Lagoon, where they're placed in fine mesh plastic bags which are tied to racks in the intertidal zone. This system of being dry at low tide and submerged at high tide prevents both the oysters and the racks from becoming fouled with marine growth.

As they grow in size, the oysters are regularly turned, thinned out and moved into bigger bags to facilitate water flow and feeding. During their stay in the Knysna Lagoon, the oysters develop good, strong shells which close tightly when they're removed from the water.

Finally, the oysters return to Algoa Bay for another three months. During this phase, the meat-to-shell ratio increases very quickly whilst the shells themselves retain their well-defined shape.

When the oysters are ready for harvesting, they're cleaned of mud and sediment with high pressure hoses before being sorted and packed for transport.

COLLECTING INDIGENOUS OYSTERS

Limited numbers of indigenous - or coastal oysters (Crassostrea margaritacea) - are collected by licensed concessionaires who wholesale their catch to the Knysna Oyster Company for retail and export.

Individuals who wish to collect coastal oysters for their own use may take a maximum of 12 specimens - each with a minimum shell width of 5.1 cm - per day. Nobody may sell his or her catch unless he or she has a collector's license.

OYSTER FACTS

Fresh Knysna Oysters carry the Heart Foundation's stamp of approval because of their low cholesterol levels and high levels of Omega-3-fatty acids, which are associated with a reduction in heart disease.

Knysna Oysters are sold according to weight:

• 50-60 g: champagne
• 61-80 g: medium
• 81-100 g: large
• 100 g +: extra large

The Knysna Oyster Company has grown from producing 1.4 million oysters in 1999 to 2.4 million in 2002.

In Knysna and Port Elizabeth, independent scientific agencies test both water quality and the oysters themselves to ensure complete consumer protection against red tides and other toxins.

The Knysna Oyster Company's carefully researched production process means that Knysna Oysters have strong, clean shells with extended shelf life (thanks to their time in the Knysna Lagoon), and superior meat content and the succulent fresh taste of the sea (thanks to their time in Algoa Bay).

Oysters are rich in vitamins A, B2, B12 and C.

Twelve natural oysters yield little more than 100 calories.

Oysters have the same calorie rating as milk - but the calories in milk come from fat and those of the oyster come from protein.

The oyster's high salt content stimulates the gastric juices - which makes it an ideal hors-d'oeuvre.

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