August 5, 2008
Herpes Kills French Oysters
French oysters are falling prey to a herpes virus, after an oyster crisis team found they have been concentrating too hard on developing sexual organs rather then their natural defenses.
Ifremer, France's main marine research institute established the crisis team on July 3. Researchers are trying to find why 40 to 100 percent of oysters aged 12 to 18 months are dying in all but one of France's breeding areas.
On Monday, a spokesperson for Ifremer said the team had established that a virus called Oyster Herpesvirus type 1, or OsHV-1, was killing young oysters. There is no known cure for OsHV-1.
If was also found unfavorable weather conditions had weakened the mollusks.
"We had a warm winter followed by a rainy spring, which caused high levels of planktonic plant life to develop," said Johanna Martin.
"This meant that the oysters were particularly well fed and spent a lot of energy developing their sexual organs to the detriment of their natural reserves, leaving them vulnerable to OsHV-1," she said.
The investigation continues, and Ifremer admits that other factors as toxic seaweed or Vibrio Splendidus, another virus present in France this year, could have contributed.
According to Ifremer data, France produces about 110,000 tons of oysters a year. It is the world's fourth biggest producer after China, which alone accounts for 83 percent of world production, followed by Korea and Japan.
All of France's oyster breeding areas, of which 90 percent are on the western coast, are affected by high mortality rates except one area at Arcachon in the southwest. Scientists do not know why Arcachon oysters have been spared.
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