Gametogenesis in two-year-old Siberian sturgeon hybrids in industrial fish farming

Abstract

The paper presents a comparison of gonad development of two-yearold Siberian sturgeon × Amur sturgeon interspecific hybrid and Siberian sturgeon × Kaluga fish interspecific hybrid bred using a combination technology with a twoyear cycle in a recirculating aquaculture system of the Experimental Selection and Breeding Farm “Yakot” and in flow-through tanks 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). To determine the synchronism of gonad development, a histological analysis of cranial, medial, and caudal portions of the testes and ovaries was performed at the end of breeding, with a thermal constant of 12,217 degree days. The study of gametogenesis in SS×KF and SS×AS hybrids showed that gonad maturity in the two-yearold hybrids corresponded to early maturity stage II. An examination of germ cell development in the left and right gonads during the early stages of gametogenesis revealed a similar pattern. The hybrids showed normal gonad development early in maturity. In females, the main parameter is cytological sex determination: the presence of zygotene oocytes and single-layer follicle basophilic oocytes. In males, secondary sperm cell multiplication occurs in the forming cysts. Early spermatogenic wave is observed in some cases, which suggests normal germ cell development in the studied hybrids. The studies show normal reproductive system development in females and males of the studied SS×KF and SS×AS hybrids at the age of two years.