卷 65, 编号 6 (2025)

The variety of life strategies among representatives of the genus Salvelinus suggests the existence of resident (lacustrine or riverine) and migratory forms. Resident brook populations of char are characterized by small size and short lifespan (up to 8–11 years), low fecundity, and often a juvenile (pedomorphic) appearance. Such populations are most common among the northern Dolly Varden trout S. malma, less common among the southern Dolly Varden trout S. curilus, and are extremely rare among the Arctic char S. alpinus. In 2024, an unusual population of dwarf char S. alpinus complex was discovered in a small watercourse in the upper Kolyma River basin. The fish were collected in shallow channels of the Enkon River in the middle of a wide, flat valley (aufeis) in the middle reaches of the Burkandi River at an altitude of approximately 950 m above sea level. The captured dwarf brook char specimens are characterized by extremely slow growth, a juvenile appearance, and a short lifespan compared to lacustrine stocks. Similar stocks can be expected to be found in other sections of watercourses isolated from the main channel by physical barriers. In northeastern Asia, potential habitats for similar dwarf char populations may include sections of rivers and streams located above the aufeis, which are common in this area.

The main factors determining the long-term dynamics of the stock and the state of the Azov population of the great sturgeon Acipenser huso Linnaeus, 1758 are analyzed. Data on the dynamics of stocks, commercial catches, and features of spawning migrations of great sturgeon in the basin of the Sea of Azov are presented. An assessment of the effectiveness of measures for artificial reproduction of great sturgeon in conditions of loss of natural reproduction is given. It is shown that the scale of artificial reproduction of great sturgeon did not ensure the accumulation of older age groups in the population and the formation of a spawning stock under the influence of illegal, unreported, unregulated fishing. Currently, artificial reproduction of the great sturgeon in the basin of the Sea of Azov supports only the existence of the species.

Biological parameters of the fish, gonadal state, and ultrastructure of oocyte envelopes and spermatozoa have been studied in Japanese goatfish Upeneus japonicus from Nha Trang Bay. The females are larger than the males: their body length–body weight ratios are significantly different. The ovarian state indicates continuous oogenesis. The average batch fecundity is 3301 oocytes. The females (50% of the fish) reach sexual maturity at a fork length of 104 mm. The egg envelope includes a single-layer zona radiata and a chorion. In the ovulated oocytes, their thickness is 2.0—2.5 and 0.1—0.3 μm, respectively. The spermatozoon head has a pointed bend in its apical sharpened part. Among other studied species of the family Mullidae, a similar spermatozoon structure is observed in U. tragula and U. heterospinus.

Biochemical parameters (level of lipid peroxidation and oxidized proteins, glucose content; activity of superoxide dismutase, catalase, peroxidase, aminotransferases and cholinesterase) and histopathological parameters of the liver are studied for European black scorpionfish Scorpaena porcus, red mullet Mullus ponticus, and the East Atlantic peacock wasse Symphodus tinca. Most of the biochemical and histopathological responses in the fish liver were non-specific; they depended on the biological characteristics of the species, ecological group, and parasite infestation. High values of lipid peroxidation and oxidized proteins, superoxide dismutase activity, and the occurrence of melanomacrophage centers in the liver of the European black scorpionfish are a consequence of the more pronounced toxic effect of the environment, caused by constant contact with contaminated sediments. A response to parasitic invasion and the development of secondary inflammation, represented by the highest levels of lipid peroxidation, peroxidase activity, and the presence of melanomacrophage centers, was found in the liver of the bottom-pelagic East Atlantic peacock wasse. The aminotransferase and cholinesterase activities and glucose content increased in a number of studied fish species in order of increasing their natural mobility. Five types of histopathological changes of the liver were detected, related to three types of responses (circulatory disorders, regressive changes and inflammatory responses). Most of the histopathological changes were corresponded to the first factor of significance and were reversible, which indicated a satisfactory condition of the fish and a weak toxic effect of the environment.