Reproductive cycles and spermatogenesis in male sterlet in industrial fish farming
Authors:   Branch for Freshwater Fishery of Russian Federation Research Institute of Fishery and Oceanography, Russia, Moscow Region, Rybnoye, Ilyasova V.A. , Melchenkov E.A. ,   Branch for Freshwater Fishery of Russian Federation Research Institute of Fishery and Oceanography, Russia, Moscow Region, Rybnoye, Vorob’yov A.P. ,   Branch for Freshwater Fishery of Russian Federation Research Institute of Fishery and Oceanography, Russia, Moscow Region, Rybnoye, Kalmykova V.V. ,   Branch for Freshwater Fishery of Russian Federation Research Institute of Fishery and Oceanography, Russia, Moscow Region, Rybnoye, Kozovkova N.A. ,   Branch for Freshwater Fishery of Russian Federation Research Institute of Fishery and Oceanography, Russia, Moscow Region, Rybnoye, Archibasov A.A. ,   Branch for Freshwater Fishery of Russian Federation Research Institute of Fishery and Oceanography, Russia, Moscow Region, Rybnoye, Mishchenko A.V. ,   Branch for Freshwater Fishery of Russian Federation Research Institute of Fishery and Oceanography, Russia, Moscow Region, Rybnoye
Published: July 2022

With the advances made in the aquaculture industry, the role of males is becoming increasingly important, since their reproductive capacity determines the outcomes of artificial breeding. The key factor here is the developmental asynchrony of sex cells inherent in sturgeon males, which helps retain spawning readiness in males for longer periods of time without loss of quality of reproductive products produced by them. The paper presents the findings of the studies performed at the Konakovo Division of the Branch for Freshwater Fisheries of the Federal State Budget Scientific Institution “Russian Federal Research Institute of Fisheries and Oceanography” (VNIIPRKH), in a flow-through industrial farm and recirculating aquaculture system (RAS). These studies have confirmed the possibility to control spermatogenesis in sturgeons by changing the temperature during the prespawn period, thus improving the productivity of fish farms by prolonging the breeding season. The histological analysis of sterlet spermatogenesis presented in the paper offers an insight into annual reproductive cycles, natural developmental asynchrony of sex cells, and successive transformations of mature and overmature sperm in cysts and excretory duct. Such phased analysis of the development of sex cells, depending on environmental factors (the effect of water temperature) and considering the patterns of spermatogenesis, made it possible to propose the methods to control spermatogenesis in mass spawning. The design of recirculating aquaculture systems makes it possible to control the environmental conditions and spermatogenesis, and promote spawning in sturgeon males in due time, thus ensuring high-quality reproductive products whenever the farm need them. The histological analysis has not only offered an insight into the gonadal maturity parameters, but also, with partial cyst emptying, has allowed detailed characterization of the development of sex cells in spermatogenesis. Understanding the reproductive capacity of males under various housing conditions will allow defining the timing and duration of spawning, i.e., the prespawn, spawning, and postspawn periods of the annual cycle in sterlet.