Until recently, the advancement of the conservation plan of the critically endangered European sturgeon (Acipenser sturio) was limited since the attempts to reproduce fish of the ex situ stock were not very successful. From 2007 to 2010, 32 females reached maturity but reproduction trials provided limited numbers of individuals. From 2011, the situation has evolved positively. In 2011 the progenies of five out of nine females were obtained: a total of about 270,000 larvae. In 2012 and 2013, the results were even better with respectively 830,000 and 530,000 larvae, obtained from 16 out of 25 hormonally stimulated females. That success was probably linked to a combination of several improvements: (i) diet in quality and quantity ensuring a normal gonad development, (ii) control of the environment (i.e., salinity and temperature), (iii) more extended monitoring of oocytes' morphometric characteristics and physiological state of ovarian follicles, (iv) new protocol of individual hormonal stimulation. Most of the juveniles produced were released in nature to support the remaining population. The others were included in the ex situ stock.