Artificial spawning in cultured sterlet sturgeon, Acipenser ruthenus L., with special emphasis on hermaphrodites

For the first time, hermaphrodites have been reported in farmed sterlet sturgeon. Few sequential and simultaneous hermaphrodites have been observed. Most of the time both gametes proved to be functional in either mating. Embryonic survival of self-fertilised eggs ranged from 0% to 70%. Progeny was obtained twice. Out of 102 (1994) to 76 (2000) individuals representing an equilibrated sex ratio, 2 to 4 individuals, respectively, were hermaphrodites. The number of hermaphrodites increased with the age of the fish. Anatomical and physiological aspects are discussed. The modelling of our data demonstrates that fertilisation depends on gamete interaction, of which practical consequences are discussed. Artificial reproduction of hermaphrodite fish was confirmed by genetic analysis. Microsatellite analysis produced a homozygous excess of two alleles, both polymorphic loci.