Vol 63, No 1 (2023)

Comparative morphological studies of type and identified specimens of four species of genus Cottocomephorus Pellegrin, 1900 confirmed the presence of morphological differentiation between species of this genus (C. grewingkii, C. alexandrae, C. comephoroides, and C. inermis). Morphological similarity of the species was reconstructed using cladistic analysis. Two main clades were identified, of which the basal position was occupied by the clade C. grewingkii. Another clade includes three species (C. alexandrae, C. comephoroides, and C. inermis). For species identification, we created a table with the most significant diagnostic features.

The analysis of 17 microsatellite loci reveals five general forms of Arctic charr Salvelinus alpinus in large lakes Lama and Kapchuk (Norilo-Pyasinskaya water system, Taimyr) connected by the river. Three of them are represented by sister pairs, and, thus, eight reproductively isolated forms are defined. The immature individuals of different forms are hardly identified by external morphology. For the morphological differentiation of the five general forms, multivariate analyses of morphometric parameters of the body, otolith shape indices, and wavelet coefficients describing otolith contours are applied. All analyses show that goggle-eyed charr (“pucheglazka”) substantially differs from the other forms. The relationships between the four other general forms are variable depending on the method of analysis. Besides, a certain difference is observed in the data evaluating the left and right otolith shapes. The total correct jack-knifed classification of the forms in the linear discriminant analyses is 55.9% for morphometric indices and reaches 56.1 and 61.4% for the left and right otolith shapes assessed by wavelet transform. The overall morphological similarity of the forms can be explained by their parallel evolution in a restricted number of available trophic niches.

The purplegray sculpin Gymnocanthus detrisus occurs at the depths between of 17 and 595 m at the temperature from –1.1 to+13.2°C off the mainland coast of the Russian waters of the Sea of Japan. In the warm period, the fish are concentrated in the middle and lower parts of the shelf, mainly at a temperature of 1.2–2.0°C, in the cold period, in the lower part of the shelf and the upper part of the continental slope at 0.6–1.4°C. The water area in the north (the waters of the Tatar Strait) is intensively used only in the warm season. The main aggregations are formed in the south (Peter the Great Bay) and in the areas of the central part of the surveyed region. Juveniles are more eurythermal than adult individuals and more adults prefer the shelf zone in all seasons, where the temperature regime is less stable than on the mainland slope.

For the first time, we represent a comparative characteristic of the growth of, presumably, the freshwater form of the whitefish Coregonus lavaretus in the Ural tributaries of the Pechora River. The growth rate of the whitefish in the studied rivers varies significantly, which testifies the assumption of existence of several local groups in the Pechora river system, confined to different parts of the river basin. In the Ilych and Kosyu rivers as well as in the upper reaches of the Pechora River (Northern Urals), the calculated body lengths and linear growth rates do not differ significantly. Similar growth rates have been observed for the whitefish from the plain tributaries of the Pechora (lower reaches of the Kosyu and Usa rivers). In the rivers of the Subpolar Urals, the variability of whitefish growth rates is significantly higher. The specific growth rate of the subadult whitefish positively correlates with the benthos biomass in the watercourse (ρs = 0.57 according to Spearman, p = 0.04), while the dependence on climatic conditions is less significant.

The results of previous studies on the population structure of the sockeye salmon Oncorhynchus nerka of Western Kamchatka are revised based on the analysis of the variability of 45 single nucleotide polymorphism loci using both own data (seven samples from the water bodies of the western coast of the Kamchatka peninsula) and the data obtained by other researchers (seven samples from the basin of Lake Kurilskoye and one sample from the Bystraya River, basin of the Bolshaya River). All materials were re-analyzed to clarify the existing ideas about the origin and formation of the populations of sockeye salmon of the Western Kamchatka complex, as well as to reconstruct the historical and modern demographic and genetic processes that occur in these populations. According to the results of genetic differentiation tests, principal component analysis, and discriminant analysis of the principal components the sample set of lake sockeye salmon from the Ozernaya River (reproduction in the basin of Lake Kurilskoye) and Plotnikova River (predominantly the downstream migrants from Lake Nachikinskoye) differed the most from the other samples, represented mainly by river sockeye salmon. The results of the principal component analysis and the topology of the phylogenetic network for the sample sets from the basin of Lake Kurilskoye revealed their division in accordance with the periods of spawning grounds filling and with the geographical variability of the spawning periods of sockeye salmon in the lake basin.

The most distinct features of reproductive biology of lumpfish Cyclopterus lumpus are defense and care for the clutch of fertilized eggs. In order to reveal the processes of male lumpfish defense of offspring, the quantitative assessment of temporal distribution of its behavior events under changing environmental conditions has been performed. Male behavior four types such as care for an egg clutch, defense behavior, locomotion, and rest are identified. Defense behavior is most variable, depending on the characteristics of an aggressor. It has been shown that the external factors affect the time taken for care rather than any change in certain actions. Under the favorable conditions, the male actions to care for an egg clutch represent repeating cycles, when the overall time spent on them may reach 99% of all time. Under the unfavorable conditions (strong currents and potential predators), the time of cycles tends to decrease to 55%. The environmental factor effects on the lumpfish behavior are described in terms of an algorithm of behavior, which can be used in modeling the energy intakes of a male lumpfish in the period of caring for offspring.

The biochemical composition of the muscles of two fish species, European smelt Osmerus eperlanus and the Common (Caspian) kilka Clupeonella cultriventris, that were successively invaded and naturalized in the Rybinsk Reservoir in the second half of the 20th century, differs significantly in the fatty acid content. The sum content (mg/g) of eicosapentaenoic (20:5n-3) and docosahexaenoic (22:6n-3) polyunsaturated fatty acids in the muscle tissue of the kilka is almost four times higher than that in European smelt. Given that smelt and the kilka are similar in their ecological and morphological characteristics and do not differ significantly in the composition of their diet in the Rybinsk Reservoir, it is obvious that the observed differences primarily result from the phylogenetic aspect. The obtained data on the composition of the fatty acids of the invaders show that the replacement of one alien species with another (European smelt with the kilka) significantly changed the quality of production of an important link in the trophic web of the reservoir.

Two species of the Emmelichthyidae family, Emmelichthys ruber and Erythrocles monodi, have been recorded in the western Atlantic. The species E. monodi is reported for the first time in Mexican waters, based on a specimen of 403 mm standard length, captured south of Veracruz, which corresponds to the first record of the family in Mexico and its southwestern distribution range of the Gulf of Mexico.