Gulping down oysters has long been a favourite New Year's Eve ritual for the French, but as winters get warmer and summers get drier many growers worry there will soon be fewer of the prized mollusks to go around. Inside a wooden hanger redolent of salt and the sea, around a dozen of his workers are sorting, weighing and packing oysters into crates in the Brittany port of Cancale. Le Moal and other farmers along this stretch of France's Emerald Coast say the long drought which struck swathes of the country this summer took a heavy toll, leading to smaller harvests, and smaller shellfish. Without summer rains that wash crucial minerals into the oyster beds, "there's no plankton, the main food for oysters, so they don't grow," explained fellow oysterman Bertrand Racinne, weaving his way between baskets and stacked crates.
"In the end, we have oysters but not enough of the big ones," said Racinne, who like most growers sells more than half his yearly production in December. Cold weather normally encourages a needed rest for oysters to mature, said Yoann Thomas of France's IRD research institute. But this winter has so far been unusually warm and, paradoxically, too rainy. Rains may bring minerals that favour plankton growth -- but they also mean the mollusks spend too much energy eating. This year's harvest are likely to start the spring "fragile and vulnerable", warned Racinne. Scientists point in particular to a Herpes virus, OsHV-1, that has been present in French oyster waters since 1991 but has become more aggressive recently, for reasons still unknown.
Since 2008, up to 75 per cent of young oysters have been lost in some years, said Fabrice Pernet at the Ifremer ocean research institute in Brest. But warmer waters would reduce this window of opportunity, he said, and new pathogens could arrive if carried north by fish and other sea life fleeing rising temperatures further south. Erratic and extreme weather conditions are likely to become more frequent unless aggressive steps are taken to limit climate change caused by human activities, scientists warn. Not every oyster farmer is convinced, however, saying the bigger risks are pollution, oyster beds that are becoming too densely packed and the increased use of genetically modified species. "Mortality rates change every year, depending on the region... but nobody can really explain why," said Alexandre Prod'homme, another grower in Cancale.