Oyster farmers should know by the end of October how their shellfish are doing during their autumn growth period and be able to give indications of quantity and quality for the key Christmas and New Year market.
Signs are promising this year after a good spring, but nothing is certain until the second autumn growth is complete. With consumption in France peaking over the Christmas and New Year festivities, it is vital that production peaks in time.
Oysters are marketed in five grades, with the biggest being number one, and the smallest number five.
“By far the biggest market is for number three sized oysters, and we try to get as many of those for the December season as possible,” Laurent Chiron, the president of the Groupement Qualité Huîtres Marennes-Oléron, who has his own business at L’Eguille-sur-Seudre, not far from Royan, told The Connexion.
“So far we have had a good growth period in the spring, where the rain and the temperature helped to produce lots of plankton, but we will only really know where we stand at the end of October.”
Marennes-Oléron is the largest of France’s seven producing areas, of Normandy, North Brittany, South Brittany, West-Central, Marennes-Oléron, Arcachon, and the Mediterranean. It produces 20 million tonnes of France’s annual crop of 100 million tonnes.
Of the seven it is the only one to finish off the oysters in claires, shallow baths dug out of clay, initially used to produce salt.
The oysters are moved there from the sea for minimum periods of between 14 and 28 days, with the density of the shellfish per metre squared also varying from one kilogramme per metre square to three kilogrammes per metre square.
As the sea water in most claires is renewed during the highest tides of the month only, the level of salt in the water is normally lower than in the sea and estuaries as the seawater is diluted by rainwater. This also promotes the rapid growth of algae and plankton not found in the sea, including green algae which gives some Marennes-Oléron oysters their unique jade green colour.
“Our oysters are usually not as salty tasting as others, with sweeter, nutty flavours coming to the fore,” said Laurent Chiron. “It was realising that we have such special circumstances here, a terroir, which pushed us to get official recognition.”
As well as being the only oysters with Indication Géographique Protégée status, granted by the European Union and covering oysters produced over 3,000 hectares, some of the oysters have French Label Rouge quality labels as well.
These are given to oysters following strict rules during their growth. One Label Rouge is given to the Huître Fine de Claire Vert which has jade green gills from the algae and plankton in the claires, a fair amount of flesh with a soft to firm consistency, and a salty then sweet taste with a medium finish.
The other is for the most expensive Pousse en Claire, where the minimum period in the claires is four months with a maximum density of five oysters per metre square.
Originally grown not for the market but as curiosities for the family and friends, Pousse en Claire have a very firm, nearly crisp flesh, a pronounced “marshy” flavour, which is sweet over salt, and a long finish in the mouth.
Other oysters from the region are the Fine de Claire which do not have much flesh, have a soft consistency and a delicate taste with a short finish, and the Speciale de Claire where the oysters are selected for a curved shell giving a lot of flesh, with a sweet taste and a long finish.
Oyster growers all over France had a bad scare in 2010, when there was an episode of extremely high mortality among one year-old oysters – oysters reach market usually after two-and-a-half or three-and-a-half years.
This led to big price rises for 2012, 2013 and 2014, but since then prices have stabilised.
“I expect that the prices this year will be stable, or even a bit lower than last year,” said Mr Chiron. “This year I know some of our producers, especially with their beds out to sea, had episodes of die-off but it was very selective, touching some people and not their neighbours.”
Scientists investigating the phenomenon suspect bacteria living in the mud of the estuary to be behind it, but do not know why it suddenly proliferated or why some oysters seem more resistant to it than others. The bacteria does not harm humans.
“The thinking now is that oysters which have recently been moved are more susceptible and it is chance, whether they have been moved when the bacteria is growing or not,” he said.
“At the moment we do not think we have to change the type of oyster which is what some people were proposing. There is no way we can give our oysters antibiotics, it is the one animal raised by humans which cannot be treated by antibiotics at all.”
Marennes-Oléron is also unique in France in that all its natural oysters are “captured” at sea, on special tubes looking like insulators used on high-voltage lines.
Other regions get most of their oysters from specialist breeders, who also supply some growers in Marennes- Oléron with the triploid oysters, which have been on the markets in summer for 20 years.
Bred to have three chromosomes, using complicated methods in hatcheries they do not turn “milky” during the summer breeding season.
They are also quick growing but the advantages have to be weighed against the price of buying them in.
France consumes most of the 100 million tonnes of oysters it produces. Around 20 million tonnes are exported, mainly to Asia, and at the same time around 20 million tonnes are imported, mainly from Ireland, Spain and Portugal.
Often called the vignerons (grape growers) of the sea, oyster farmers are usually from families who have been in the business for generations.
Like grape growing, the work is a mixture between manual labour and specialist knowledge.
Work includes picking off tiny oysters, putting them in sacks, taking the sacks out to sea at low tide, lifting checking and moving the sacks to different areas, and then harvesting when they have grown.
And, again like wine, marketing the end product can make the difference between success and failure.
Many growers in Marennes-Oléron now have their own “cabanes” the name originally given to the huts used to store equipment, but now converted into basic restaurants where clients can eat just harvested oysters.
They have proved to be so successful that restaurant owners are now crying foul, saying too many of their clients are going to the “cabanes” which they claim do not have to meet the same standard as the restaurants.
Mr Chiron disputes this: “We are inspected every week by the prefecture, to make sure our oysters are safe. You do not see restaurants checked every week.”
Tiger (prawn) economy too
Around 20 producers in Marennes Oléron have started raising Asian tiger prawns as part of their business. The claires have to be maintained and sometimes stay empty between batches of oysters.
“During this time there is a huge growth of algae and plankton, which has to be cleaned away before the oysters come in.
“As an experiment we tried putting the prawns in and they thrived, as well as keeping the claires clean. The prawns are put in the claires as babies, smaller than a finger nail in the Spring and grow up to 20 cm by August. Any which are not harvested die off as soon as the first autumn cold spell arrives.
“I find them delicious and they do bring in extra revenue in the summer,” said Mr Chiron.
The producers are divided between the “ranchers” like Mr Chiron, who do not stock densely and leave the prawns to find their own food, and the “farmers” who stock more densely and feed the prawns with bio-granules, specially prepared by a Brittany firm.