Regularities of oogenesis and spermatogenesis of commercially valuable fish species in the water bodies of the Dagestan part of the Middle Caspian Sea

Abstract

Based on our own research and literature data, it was proved that the features of vacuole location, size, and variability in the periods of early and late trophoplasmic growth require the closest attention. There are also certain inconsistencies of gametogenesis between different species of fish within the family. These consist in the fact that for fish species that have a shorter spawning period (roach, pike and perch), the general specificity of the annual cycles of development of the sex glands is characterized by the absolute termination of spermatogenesis by the period of the beginning of spawning, the absence of maturation or new formation of sexual products in this process. Individuals with extended spawning (for gouster and silver carp) are characterized by such features as the presence of an additional wave of spermatogenesis, which begins and ends during the spawning period, the incomplete development of sexual products by the beginning of spawning and the continuation of the process of their maturation in individual cysts of the testes throughout the spawning period (for bream and fish), continuous spermatogenesis,which allows the use of reproductive products at any time from spring to fall of the annual cycle, and under favorable conditions — throughout the year (for carp and catfish). In the experimental aspect, the obtained results can be applied in conducting a large-scale selection of female fish, based on the size of ovulated oocytes and individual selection according to the average statistical size of the latter. In fishery plan the above mentioned is required in connection with obtaining eggs from fish with batch spawning and asynchronous development of oocytes.