Food & Beverage
Apr 1, 2015
Oyster and other shellfish have been abundant in the Portuguese rivers and shores but throughout the years, various diseases almost sentenced its extinction. Recently, aquaculture has restored their existence.
Aquaculture of the ostra crassostrea gigas is thriving on the Portuguese coast. There are oyster beds now in most tidal marshlands like the Ria Formosa (Olhão, Tavira, Ilha Culatra, Cacela Velha) and further in the West, for example, in the Vale da Lama.
In the low tide, dressed in high rubber boots the workers march to the endless rows of what looks like neatly arranged cushions on high-legged benches. They are actually rugged mesh sacks with ever increasing holes filled completely with oysters of ever increasing size. In the Algarve, it takes one to one-and-a-half years for an oyster to be fully-grown. In France, it takes up to four.
Oysters are propagated from seed. Yes, oyster seed, called "cultch", are filled into fine-mesh sacks and deposited on these benches in the marsh. A juvenile oyster is between 2mm to 6mm in size and a grown one reach the expected marketable weight of 65 to 90 gr.
This process and period, as well as the final size and appearance of an oyster, depend on the quality of water and ambient temperatures. That's the reason why the largest French aquaculture enterprise grows a substantial part of their production in Algarvean waters.
As the oysters grow in their appropriate sacks, nature makes the selection by sorting out weaknesses and strengths.On mechanical sifting machines, the faster growing ones are separated from the smaller ones and put into the next size mesh sack before being returned to their marine beds – the debris is discarded. This process is repeated until the oysters are fully grown. It is back-breaking work, for these sacks are heavy.
All bivalves are highly sensitive to quality of water. They feed on microscopic phytoplankton that can sometimes produce naturally occurring marine biotoxins. These can cause serious and even fatal illness when consumed, here in the Algarve meticulous supervision is done by the State run laboratories IPIMAR, who take weekly analyses. It is good to know that there were two weeks in April 2011 when sales and consumption of all sea food, including oysters, was forbidden due to an invasion of biotoxins.
Climate change has a lot to answer for even in this "industry". MythsHere in the Algarve there is no end to the oyster season – in fact, there is NO seasonal passing of oysters not even when the "Rs" vanish from the months.That is one of the many myths surrounding the bi-valves. This myth is grounded in practical reasoning: as oysters procreate in the summer months (in this hemisphere those without an "R") they are then not as fat, hence the interruption of commercial marketing. But they certainly are not inedible during this period - it is all just a matter of taste. Some people even prefer the sweeter taste of a lactating oyster. When the male oysters grow milky once a year, the opposite gender can incubate up to one million larvae.
Their frisky "love life" is very interesting: some oysters repeatedly change their gender from male to female and back, giving rise to yet another myth that eating oysters lets one experience the masculine and feminine sides of love.The better known myth that eating raw oysters increases libido is somewhat borne out by scientific fact. Oysters contain dopamine, a neurotransmitter that helps govern brain activity and influences sexual desire in both men and women, and local wisdom has it that oysters are the Viagra of the poor.
It is no myth to say that oysters are beneficial to your health. They contain high levels of zinc, complex sugars and proteins. Omega 3 fatty acids, copper and vitamins E and B12 are complemented by low calories and low saturated fat content.
The latest data concerning 2009, reveal a thousand tons production, and the producers insure an increase in 2010.