Problems of compensative fisheries: increasing the adaptive potential of broad whitefish Coregonus nasus (Pallas) in early ontogenesis by weak magnetic fields. 1. Morphometric analysis

Abstract

The article presents the results of a production experiment with the embryos of Coregonus nasus, delivered at the Sobsk fish hatchery (settlement Kharp, YaNAO). The plant is taking compensatory measures to restore the number of valuable species of whitefishes in the Ob river basin. The purpose of our study was to increase the biological potential of juvenile broad whitefish for their subsequent release to the Ob river. At the last stage of the embryonic period, the embryos were treated with ultra-weak pulsed magnetic fields for several days. In the postembryonic period, the control and experimental juveniles of broad whitefish were fixed for subsequent morphometric and cytological-histological analysis. After conducting a morphometric analysis, we found that already at the early stages of the postembryonic period, the experimental larvae and fry exceeded the control ones in most parameters. Later, these differences persisted. At the same time, the juveniles of the experimental batch showed, as a rule, less variability of morphological characters. Also, the weight of the experimental fry before release to the Ob significantly exceeded the weight of the control fry. We calculated the degree of correlation of morphometric characters in juvenile broad whitefish of both parties in the process of rearing and found that during the first month the correlation of most parameters in the experimental juveniles was lower than in the control. However, with further development, the degree of relationship between the parameters in juveniles in the experiment increased and reached it in the control. Later, the allometric growth of the experimental juveniles began, which caused a decrease in the connection between some characters. We are discussing the features of the development of experimental juvenile fish; activation of its natural mechanisms of autorehabilitation by using weak physical factors. We explain the reasons for the stable, but insignificant differences between the experimental fish fry over the control treatment with an ultra-weak pulsed magnetic field at the last stages of embryogenesis, when the main organ systems are already formed. We conclude that this approach is advisable, starting with fertilization and early embryogenesis.