BORDEAUX - The oyster industry organizes a conference Wednesday to Sunday World in Arcachon (Gironde) where experts will discuss the four years mortality affecting up to 75% of young oysters in France, a phenomenon related to climate change also observed in other countries.
In total, approximately 370 oyster industry professionals - producers, scientists, experts, institutions - from 25 countries (New Zealand, Australia, China, Korea, Japan, USA, Mexico, Namibia, Morocco in particular) will be attending.
For five days, the issue of mortality of oysters and its consequences for operators will be the focus of this conference, a world first. Organized at the initiative of the regional shellfish (SRC) Aquitaine Arcachon, its objective is to "find lasting solutions."
"Oysters are in the world, a fragile resource that is not going very well and this is largely due to climate change," explains Sébastien Chantereau, general secretary of the National Committee of shellfish (CNC).
Thus, ocean acidification, rising temperatures, anoxia (lack of oxygen) of water in some areas ... related to global warming have an impact on oysters, which are true "sentinels of the environment like bees are to the earth," says Chantereau.
France, Ireland, Portugal and Spain, but also since 2010 in Australia and New Zealand, the mortality is largely due to the presence of herpes OsHV-1.
It is "the main pathogen detected regularly during mortality events (...). It is associated with mortalities in hatchery nursery as well as in the natural environment," says the French Research Institute for the Exploitation of the Sea (Ifremer).
"Between 1995 and 2007, mortality rates have remained relatively stable at the national level and situated at around 15%," according to Ifremer, but "2008 showed a sharp increase, and since the rate remains high (.. .) reaching 63% national average in 2011. "
"After four years of crisis, we need to exchange in order to understand what happens and enjoy the returns of'' experienced professionals to anticipate future crises," said Olivier Laban, president of the CBC Arcachon- Aquitaine.
"We need to share our experiences as professional practices are the only levers that act to reduce this mortality," says Chantereau.
"The industry must consider all possibilities of change in farming practices and more generally in livestock management, to minimize the risk of transmitting the virus," said Benedict Beliaeff, head of the Department of Biological Resources and Environment Ifremer .
For him, "parallel to these preventive measures, genetic selection is a way to go. It is more resistant families identify and implement plans to cross restocking and improving the capture."
"Finding a strain that is resistant to this virus will be long, an import of a new strain would be faster but the rules prohibit us today," says Laban.
In the 70s, an unprecedented epidemic had decimated the Bassin d'Arcachon oysters, which were then largely of Portuguese origin.
Professionals had decided to import a variety of mass oysters from Japan, thus saving the Bay of Arcachon oyster.
With some 130,000 tonnes produced annually, France is the fifth largest producer. The Bassin d'Arcachon congress website, some 350 companies produce 8 to 10,000 tons of oysters per year.