Sturgeons of four ages per weights (1 plus , 2 plus , 3 plus , 4 plus) were subjected to a progressive change from freshwater to saline waters (33 ppt) and then maintained 30 days at this salinity level. Parameters as survival rate, weight changes, body composition, osmolarity and main ionic and urea concentration in blood samples were periodically monitored. As a whole, physiological parameters mainly related with blood osmolality increased as environmental salinity did, until they reached a plateau between 21st and 32nd days (salinities, 26.8 ppt and 30.5 ppt, respectively). An overall consideration of the results led us to conclude that age 2 plus results the most favourable for these purposes. Although more in depth studies are required, this first approach resulted in a very encouraging balance.