SHELLFISH SPECIES

The Pacific oyster, Crassostrea gigas, was introduced from Japan specifically for aquaculture. In Canada, the Pacific oyster is farmed exclusively in British Columbia. Oyster farming dates as far back as the 1920s. The Pacific oyster is now the most widely cultured oyster throughout the world. In 2005, 7,638 tonnes of Pacific oysters were produced in Canada at a value of $8 million.

Basic description

Pacific oysters are large, fast-growing, cupped oysters with deep, elongated, thick and rough shells. The shell colour ranges from muddy brown to light gray and contains some purple streaks and spots. The meat is creamy white with a dark fringe around the mantle at times, although the colour of the meat as well as the shell can vary by region and season. Oysters have a mild, sweet flavour with a firm and plump texture. Pacific oysters, like most bivalve shellfish, are filter feeders. They eat microscopic organisms in the surrounding environment.

While the Pacific oyster can grow to over 30 cm (12 inches) it is normally harvested at 15 cm (6 inches) or less. The average cultured Pacific oyster is harvested when it reaches between 8 and 10 cm (3–4 inches) in length. There are three grades of oysters – choice, standard and commercial – with choice being the highest valued product. The shell and meat are both taken into account for these rankings. Cultured oysters are generally sold per count or by weight in varying sizes (extra small, small, medium, large).

Background

Oysters have been a favorite of food lovers and romantics throughout the centuries. The oyster has maintained a timeless mystique when it comes to passion. When Aphrodite, the Greek goddess of love, sprang forth from the sea on an oyster shell and promptly gave birth to Eros, the word "aphrodisiac" was born. Roman emperors literally paid for them by their weight in gold. The dashing lover Casanova also started his evening meal by eating dozens of oysters. Please read the Fisheries and Oceans Canada fact sheet entitled, Oysters: ‘Myths’ and Facts (link provided below) for more information regarding the passions associated with oysters.

Canadians can enjoy fresh oysters twelve months of the year. Oyster aquaculture, or farming, complements the supply of oysters at your local seafood counter when wild, commercially-harvested oysters are not available. Oysters are generally harvested at the time of year when they are in peak condition, when their meat is at its "fattest". Oysters need a period in the spring to recuperate from the winter before they reach a condition ideal for the retail market. Also, oysters spawn in the summer, which can alter their flavour and texture.

It is rumoured that oysters were the first sea animal to be transported from one area to another and cultivated as food. Commercial-scale oyster farming began early in the 20th century on both coasts, where cultivation consisted of collecting wild seed and spreading them on beds where they could be protected from public harvest and predation.

In the 1950s, the industry started collection of wild juvenile oysters on "spat collectors," which were placed on "nursery" grounds and grown to market size. Some species are also produced in hatcheries where broodstock are spawned and the larvae raised under controlled growing conditions. In both cases, when the juveniles are large enough to be transferred to grow-out sites they are removed from the collectors and transferred for spreading on "beds" (sites that have been prepared for the spreading of juvenile oysters or clams) or to holding bags, cages, or rope lines for grow-out to market size.

Last Updated : 2007-08-28

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