• Cold weather normally encourages a needed rest for oysters to mature.
  • 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”.
  • In 2017 the roughly 4,500 oyster growers in France sold 100,000 tons, at an average price of 5,000 euros per ton.
  • Oyster farmers will see volumes down by 20 to 30 % this year
  • Climate warming is starting to have an impact.
  • Warmer water temperatures are also a risk because they facilitate the spread of viruses that are especially harmful to oyster larvae, or spat, and young oysters.
  • 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% of young oysters have been lost in some years.
  • Oyster farmers had found a solution by putting ten times the amount of spat in the water in autumn, when the virus is not active.
  • But warmer waters would reduce this window of opportunity 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.
  • By 2035 the abnormally high mortality episodes that currently occur every ten years risk happening every two years.
  • But if warming and weather patterns become increasingly volatile, French farmers might have to start changing their growing seasons or move their beds north or further out to sea.