No abstract

No abstract

The work presents the biological characteristics of the females of the Amur sturgeon caught in the Amur River: indicators of the length and body weight of females, the mass and stages of maturity of their gonads, the dimensional mass characteristic of oocytes, indicators of individual absolute and relative fertility. The results of histological examination of gonads are presented. Degenerative changes in the structure of the reproductive system were noted, reducing the effectiveness of natural reproduction.

Despite the rapid development of molecular genetic methods, the use of traditional morphometry for the identification of sturgeon hybrids, which has an obvious advantage when working in field or production conditions, does not lose its significance. The hybrid Acipenser baerii × Huso huso (Lenbel), which is promising for commercial cultivation, is completely insufficiently studied in this regard. The purpose of the work was to make a comparative morphometric analysis of the hybrid and parental species, as well as to determine its identifying features.Experimental and control groups of fish were obtained from producers grown on the farm. It has been established that the hybrid, according to most indicators, occupies an intermediate position between the Siberian sturgeon and the beluga. The difference with the parental species is statistically significant for 32 characters. The hybrid differs from the beluga in 23 plastic indicators out of 30, and in 4 out of 6 meristic indicators; from the Siberian sturgeon — in 18 of 33 plastic characters, and in 5 of 6 meristic ones. At the same time, the hybrid differs from both parents in 14 plastic and 4 meristic characters. In hybrids, the matroclinic effect is significantly manifested: the transgression rate with Siberian sturgeon below 67% was noted only for the width of the snout at the base of the middle pair of antennae (29.2%) and for the width of the gap of the lower lip (21.2%). The main indicators that are promising as test characters for hybrid identification are concentrated mainly in measurements of the head (O, HC, rc, rr, SRc SRr) and mouth (SO, il).

The hybrid of sturgeon "lenbel" (F1 ♀ Acipenser baerii × ♂ Huso huso) was studied by conventional methods for a complex of plastic and meristic signs. It was found that only the horizontal diameter of the eye (O), the greatest height of the head (HC), the distance from the end of the rostrum to the base of the middle antennae (rc) and to the cartilaginous arch of the mouth (rr), the width of the snout at the cartilaginous arch of the mouth (SRr), the width of the mouth (SO) and the width of the break of the lower lip (il) for hybrid and beluga, and the width of the lower lip break (il) and the width of the snout at the base of the middle antennae (SRc) for hybrid and Siberian sturgeon have a transgression index of less than 67%, and can be used to identify the hybrid form. The beluga fingerlings were largely consolidated, and therefore united into a single cluster. Siberian sturgeon and hybrid also form two clearly differentiated clusters, but the intra-group divergence of the hybrid is slightly higher than that of the original forms. In hybrid fingerlings, relative plastic and meristic signs are not related to body size and remain constant during the growing period, that is, they may be specific to it. It is shown that some head measurements can be used for confident identification of the hybrid.