Biological characteristics of small-scaled scorpion fish in coastal waters of Sevastopol in modern times

The article presents the analysis of parameters of the biomonitor species ‒ small-scaled scorpion fish at the dif-ferent organization levels as part of the study of the current status of fish and their habitat conditions in a coastal zone of Sevastopol. In spite of the similarity of the size and mass values in species caught in the different bays there has been found regularity in the fish size: the Balaklavskaya Bay > the Kruglaya Bay > the Streletskaya Bay. The indexes of the gills and liver of Scorpaena porcus from the Streletskaya Bay were higher in the older fish group compared to those in other water areas, which was considered as an adaptive response to unfavorable habitat conditions. At the same time, high values of the hepatosomatic index, fish size and weight, glucose content in blood in this benthic species from the Balaklavskaya Bay indicated a better natural food supply. Thus, the values of the parameters studied in fish from different bays often differed slightly, which proves the similar living conditions and satisfactory state of the bays of Sevastopol today. This was also evidenced by the results of a more sensitive analysis - the morphometric parameters of the gills: the length and width of the filaments, as well as the density of their distribution on the gill arch did not differ significantly in species of the same size from different bays. However, comparing inter-annual changes in population parameters it was found that the size of scorpion fish species, especially females, has decreased in 2021 compared to 2017–2019. The fish weight decreased in the Balaklavskaya Bay by 8–10 g, in the Kruglaya Bay ‒ by 20 g, and in the Streletskaya Bay in 2021 individuals weighed almost half as much as in previous years. The conducted bioindicative studies have showed a deterioration of the ecological status of the water areas of the Crimea.