Morphofunctional characteristics of the gonads in females of the pontic shad Alosa immaculata in modern ecological conditions of the lower Nistru in the spring-summer period

Pontic shad (Alosa immaculata) is a migratory gregarious fish that spawns in the Don, Dnieper, Dniester, Danube and other rivers. The species is of valuable commercial importance. This work analyzes changes in the reproductive functions of the commercially valuable species of pontic shad (Alosa immaculata) under conditions of fragmentation of the river Dniester. Currently, the age composition, as well as the linear weight indicators of the spawning pontic shad population, turned out to be similar to the data of previous years. Oogenesis of Dniester’s pontic shad is characterized by asynchronous development of germ cells and portioned release of eggs. Spawning of spawners begins in the third ten days of May, at a water temperature of 18°C and ends in July. In the lower Dniester in April and July were revealed in some females’ destructive changes in the development of vitellogenin oocytes, which will negatively affect the population size of migratory herring.