“Here is the phytoplankton room, this is where we will prepare food for animals,” shows Florian Breton, director of the hatching, facing several dozen jars ranging from clear water to dark brown.
A stone’s throw from the small wearing of Tinduff, in the harbor of Brest, this maritime cooperative has developed unique expertise in Europe: reproduction and breeding of the Bivalve Pecten Maximus mollusque, whose flesh and coral are very popular with French restaurateurs.
Born in 1983, this hatching is “a tool that was created by fishermen” after a fall in the resource, recalls Philippe Perrot, vice-president of the Fisheries Committee of Finistère.
Decimated by overfishing and cold winters, the scallops deposit of the Brest Rade collapsed in the 1960s and 70s, touching a floor with 62 tonnes of shells landed in 1968, very far from the record of 2,600 tonnes of 1952.
Eager to save a routing fisheries, scientists and professionals then go to Japan to study the reproductive techniques developed on local mollusc species.
“How do we lay a scallop shell? How do we raise a larva? We did not know how to do it at the time,” said Breton.
IFREMER scientists then succeed in making the first eggs of this hermaphrodite animal, much more difficult to raise than its cousin the oyster.
Since then, 300 to 400 adult shells have been removed each year in the natural environment and placed in large bins filled with sea water and sediment. “We are going to give them the cottage and the cover, play on the temperature, the photoperiod, so that they mature, make their oocytes,” explains Florian Breton.
Once the male and female gametes are mixed, the fertilized eggs are placed in incubation bins, where they turn into a larva that swims, grows and then gets attached to the bottom.
In the large hangar of the Tinduff nursery, hundreds of thousands of post -larns, with discernible shell with a magnifying glass, dot the bottom of cylinders aligned in sea water.
After two to three months spent in nursery, seven million post -larns will continue their growth in submerged cages at the entrance to the Brest harbor.
– “essential resources” –
It is only a year after their birth, when they have reached the size of about three centimeters, that the small shells will be sown over half a dozen French deposits (Granville, Saint-Malo, Morlaix, Brest, Quiberon, Noirmoutier and La Rochelle).
Anecdotal with regard to French fishing, dominated by the enormous deposits of the bays of Saint-Brieuc and Seine, the production of hatching, however, plays an essential role in maintaining local fishing.
Depending on the year, sowing shells can thus represent between 30% and 70% of the Brest harbor catches. “Today is an essential resource. Because if sowing was stopped, the fished volume would decrease sharply,” notes Florian Breton.
In 2024, the thirty shells of the harbor landed 135 tonnes of scallops at the Criée de Brest. “This year, I think that we are around 40% of my fishing which comes from the spats of the hatch. It is not negligible!”, Confirms Phillipe Perrot.
Concarneau’s deposit (Finistère), now ravaged by the proliferation of octopus, could thus be reconstructed if the cephalopod came to disappear, notes Mr. Breton.
A real insurance against the collapse of stocks, the hatching has also developed a technical platform for science support for a few years, with studying programs the impact of the work of wind turbines at sea or the effects of toxic phytoplankton on the development of the shell.
