Abstract: Siberian sturgeon Acipenser baeri is one of the most popular fresh water aquaculture species in China, and its artificial spawning is succeeded. In order to provide information that may improve fry rearing techniques, the allometric growth of A. baeri from newly hatched larvae (age, 0 day) to 53-day old juveniles and the significance of priority development of some organs were studied by using digital photomicrography and computer software (Image-Pro Plus 51) to measure and analyze the growth characteristics. The results showed that there were 3 inflexion points of full body length (FL) increase occurred at the ages of 9, 28 and 37 days, and thus, the FL increase might be divided into 4 periods. The mean FL increase rate of each period was 083, 079, 268 and 171 mm·d-1, respectively, with that of the third period being significantly higher than those of the rest periods. The relationship between body mass (BW) increase and age could be characterized by Gaussion equation (correlation coefficient R2=099). The relationship between BW and FL was BW=02×10-5FL272, which meant that the body mass of the larvae and juveniles had a negative allometric growth. During early development, some important organs also grew in allometry. The eye diameter increase firstly reached to the inflexion point at the age of 3〖KG-*2〗-〖KG-*7〗4 days, which might infer that eyes had priority to develop, and thus, young fish might have ability to escape from predators immediately after hatching. Mouth width increase reached to the inflexion point at the age of 17〖KG-*2〗-〖KG-*7〗18 days, which implied that active feeding enhanced hereafter. The growth inflexion points of pectoral fin, dorsal fin, and pelvic fin were at the ages of 16〖KG-*2〗-〖KG-*7〗17, 13〖KG-*2〗-〖KG-*7〗14, and 21〖KG-*2〗-〖KG-*7〗22 days, respectively, indicating that the swimming ability of young fish improved since then. These priority developments of important organs might help fish with active feeding and escaping from predators as early as possible, and thus, a higher survival rate might achieved during early development. To improve the artificial fry rearing techniques of A. baeri, specific conditions should be provided in time, according to the periodicity and priority of organ development, and consequently, important organs might have priority to develop normally, and the survival rate of early life stage might increase.

Key words: Molecular ecology, Soil microorganism, DNA extraction