There are 24 varieties of sturgeons worldwide therefore 24 different varieties producing eggs which is known as caviar.
There is often confusion between quality and name of variety. The most known is Beluga, Sevruga, Oscietre wich do not correspond to three qualities of caviar but to three varieties of fishes. The sturgeon breeding in France is the Siberian one.
The acipenser sturio (one of the 24 varieties) lived in the wild state of the Gironde estuary and it was very exploited and fished from the 20s to the 60s because its flesh was very appreciated. Day by day fishermen learnt to prepare eggs. There never had been kilos of product and there are not other elements indicating that this caviar was of good quality.
The excessive exploitation of these sturgeons and the modifications of the Garonne installations provoked its almost disappearance in the 70s. The CEMAGREF (center of agricultural mechanization, rural genius waters and forests) public body is in charge of reintroduction of this variety. Because assessments were done during a scientific exchange with Soviet Union in earlier 80s, CIMAGREF imports adults and alevins of Siberian sturgeons. The great advantage of this variety is to spend its whole life in fresh water. Sturio is a migrant which run the Gironde to spawn.
When the assessments were ended and control (masters degree) of the reproduction was noticed, the scientists of CEMAGREF stopped going with reproduction at the end of 80s. Some fishes breeders approached these works and learned now to breed Siberian sturgeon which is the only authorized variety.