Study on Embryo Development in Sterlet (Acipenser Ruthenus) Reared in a Recirculating Aquaculture System

Abstract

Sterlet (Acipenser ruthenus) is a sturgeon that hold an important place in aquaculture, being a species that can be raised both outdoors in fishponds and indoors in recirculating aquaculture systems (RAS). Knowledge of this species' biology has enabled the development of breeding technology in RAS; however, it is not yet fully optimized, and certain aspects of the technological process still require improvement. One of these is related to the artificial reproduction in order to produce the sterlet larvae. The aim of this study was to highlight the particularities of the embryo development in the sterlet during incubation, the studied embryos being obtained from sterlet breeders raised exclusively in the RAS. Eggs and sperm were collected during the 2024 breeding season, following the stimulation of ovulation and spermiation with pituitary suspension prepared from carp pituitary glands. After fertilization, the eggs were incubated at an average temperature of 17.3°C in a Zuger jar. Embry development was monitored by taking at regular time intervals 20 - 30 eggs from the incubator and studying them with a stereo magnifier. Embryo development was staged as follows: the zygote period (0-2h 15ʹ), the cleavage period (2.5-9 h), the blastula period (9-17 h), the gastrula period (17-32 h), the neurula period (32 -44 h), the organogenesis (44-100 h) and the hatching period (100-124 h). The main features observed were recorded, photographed and described.