Like treasures, eight large mother-of-pearl from the Mediterranean are delicately extracted from a pond north of Perpignan, heading for the laboratory.
Engaged in a race against time, researchers are trying to save this second largest mollusc in the world, threatened with extinction.
“Today, it only survives in certain lagoons.
At sea, there is no longer a real population capable of reproducing, only a few individuals here and there,” laments Serge Planes, research director at the CNRS.
Since 2016, a parasite (Haplosporidium pannaé) has decimated almost all the large pen shells, an endemic species of the Mediterranean that can measure 1m20 in height and live for around forty years.
"We started the work in 2018, trying to treat the sick mother-of-pearl", explains Pascal Romans, head of the aquariology service at the Oceanological Observatory of Banyuls-sur-Mer and research engineer at Sorbonne University.
Very quickly, scientists refocused on the idea of conservation and reproduction of healthy individuals in captivity.
First objective: manage to trigger spawning, even outside the natural reproduction period, "by playing on the environmental parameters in aquariums such as temperature or salinity", explains Pascal Romans.
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Flanked by a mask and a diving suit, Titouan Morage, research engineer at the Center for Island Research and Environmental Observatory (CRIOBE) in Perpignan, carefully scans the bottom of the Salses-Leucate pond, straddling the departments of Aude and Pyrénées-Orientales.
It extracts eight molluscs.
Wrapped in cotton, the large mother-of-pearl will make the trip to the marine research animal house hosted by the Canet-en-Rousillon aquarium.
There, wedged at the bottom of a basin in pairs, they are subjected by the researcher to a temperature shock which will promote the release of gametes.
"We managed to obtain reproduction phenomena, and fertilized eggs became larvae", says Titouan with satisfaction.
But, finding the food sequence allowing them to pass from the larval stage to the so-called “colonization” stage, with the formation of the shell and its attachment to the sandy bottom, is not yet won.
In the long term, the team dedicated to this program hopes to be able to accumulate a large stock of pearl oysters in captivity, in order to repopulate the natural environment.
Beyond its real usefulness for man or the seabed, it is the “heritage” aspect that this attempt to save the species represents.
“Why are we so worried about the disappearance of the panda?
It's kind of the equivalent.
It is a symbol of the capacity or not of man to prevent the degradation of natural environments”, indicates Serge Planes.