Embryonic Development and Survival of Siberian Sturgeon x Russian Sturgeon (Acipenser baerii x Acipenser gueldenstaedtii) Hybrids Cultured in a RAS System

Simple Summary Sturgeon (Acipenseridae) fish are a valuable fish in aquaculture not only because of the taste of their meat, but also because of the caviar obtained from the production process. Sturgeon species differ from teleosts in the main stages of the life cycle, in particular embryonic development. Therefore, research regarding the controlled reproduction and egg incubation are key during breeding and hybridization programs of sturgeon species. Moreover, sturgeon hybrids are characterized by high values of performance, breeding, and reproductive parameters, and their rearing is often more economically efficient than the rearing of purebred species Therefore in this study we analyzed selected stages of embryonic development in Siberian sturgeon (Acipenser baerii) and hybrids of Siberian sturgeon and Russian sturgeon (Acipenser baerii x Acipenser gueldenstaedtii). The embryo survival rate was higher in group B hybrids i.e., female [Siberian sturgeon x Russian sturgeon] x male Siberian sturgeon than in the control group (Siberian sturgeon), whereas group A hybrids i.e., female [Siberian sturgeon x Russian sturgeon] x male Siberian sturgeon were characterized by lower survival rates than the group C embryos (control). These results suggest that the survival of hybrid embryos could be determined by individual traits, such as gamete (eggs and sperm) quality and genetic factors. The aim of this study was to describe the selected stages of embryonic development in Siberian sturgeon (Acipenser baerii) and hybrids of Siberian sturgeons and Russian sturgeons (Acipenser baerii x Acipenser gueldenstaedtii). For this purpose, embryos representing nine distinct developmental stages (stage 1-2.0 hpf, stage 2-5.5 hpf, stage 3-13.0 hpf, stage 4-20.0 hpf, stage 5-24.0 hpf, stage 6-26.0 hpf, stage 7-35.0 hpf, stage 8-55.0 hpf, and, stage 9-160.0 hpf; hpf-hours postfertilization) were sampled from each group (group A, group B, and group C) during incubation. Stages of embryogenesis were identified based on a 30-point scale of embryonic development in sturgeons. A total of 13 developmental stages were identified, including early cleavage, blastula formation, early and late gastrulation, onset of neurulation, beginning of organogenesis, and prelarvae. During gastrulation, the survival of hybrid embryos was highest in group B (93.8%) and lowest in group A (86.7%). Embryonic deformation was not observed during experimental incubation. The archived data relating to the embryonic development of Siberian sturgeon x Russian sturgeon hybrids could be applied to identify the individual stages of embryogenesis in hybrid sturgeons during egg incubation.