Early development and allometric growth patterns of beluga Huso huso (Linnaeus, 1758)

Hatchery reared beluga (Huso huso) were observed from hatching until the juvenile stage in order to analyse their early development and allometric growth patterns using bivariate and multivariate allometric analyses for different body regions (e.g. head, trunk, tail) and test whether there existed similarities in the growth patterns of beluga compared to other fish species, especially other sturgeon species belonging to the genus Acipenser. Results from Principle Component Analysis on morphometric characters (total length, head length, head height, trunk length, rostrum length and eye diameter) in specimens showed that there were shifts in the relative growth of these characters in early development (length at metamorphosis, Lₘ). A first stage comprised of hatching to 17.03 ± 0.14 mm in total length (Lₘ₁), a second stage was between 17.03 and 25.41 ± 0.21 mm (Lₘ₂), and a third developmental stage at larger sizes (larvae larger than Lₘ₂). Most morphological (feeding, swimming, sensorial and respiratory systems) and morphometric changes in beluga development took place during the second growth stanza, which may be considered as a transitional period from the larval to the juvenile stage, whereas at larger sized fish may be considered as early juveniles. The allometric growth of beluga matched developmental and behavioral events (e.g. swimming‐up, schooling and free benthic swimming) observed in the early ontogeny of this species, and showed the priority of growth of the cephalic and tail regions in beluga pre‐larvae for feeding and respiratory functions, and the tail for cruising and escape reactions prior to the full development of the digestive system. This study provides information on the ontogeny of the species, establishing a reference for its normal development that might be useful for evaluating the suitability and quality of fish produced for restocking purposes and improving the current beluga management plans.