Early development and allometric growth patterns in Siberian sturgeon and their ecological significance

Early development of Siberian sturgeon Acipenser baeri was divided into two different phases, the prelarval stage between hatching (10·4–11·1 mm LT) and first feeding (19·6–21·0 mm LT), and the larval stage between the initiation of external feeding and metamorphosis (28·6–32·4 mm LT). Morphogenesis and differentiation were more intense during the prelarval than larval and early juvenile stages; the prelarval period was characterized by the replacement of embryonic adaptations and functions by definitive ones, such as branchial respiration, exogenous feeding, and active swimming. The positive allometry of the head for feeding, sensorial and respiratory functions (inflexion point at 20·0 mm LT), and the tail for reducing costs of transport, routine swimming and escape reactions from predators (inflexion point at 20·2 mm LT) confirmed the hypothesis that growth patterns of early life stages closely match specific needs.