Some issues of ecology and biology of brown king crab (Lithodes aequispinus, Bеnedict, 1895) in the east part of the Sea of Okhotsk

Analysis of the distribution of size-functional groups of brown king crab on the continental spole in the eastern part of the Sea of Okhotsk was provided based on the data collected in 1998–2003. Aggergation rates were evaluated for males and females. Size structure of the population depended on the depth and site. Recommendations for maximum efficient fishery are provided.

On the intraspecific competition of yellowfin sole Limanda aspera (Pallas, [1814]) (Pleuronectidae) in the eastern part of the Sea of Okhotsk

Based on the longterm observations for 1963–2019, the article provides an assessment of the yellowfin sole generation mortality dynamics depending initial abundance and population dynamics in view of abundance and biomass. Individual growth and matiration rates were evaluated in generations with different initial abundance and in different states of population dynamics. Results indicated about intraspecific competition in yellowfin sole in the eastern part of the Sea of Okhotsk, expressed in specifics of the dynamics of stock abundance, growth and maturation. Forming generation stock abundance in early and later ages has different character. The more exceeding number of parental eggs spawned, the more generation abundance of yearlings getting exactly compensated by mortality (complete compensation). Older generations demonstrate the phenomen of “overcompensation”, when mortality of generations appeared in the years of higher egg production exceeds fertility. In the period of population growth and stabilization at a high level the period of the Yellowfin sole abundance fluctuation cycle gets shorter and the amplitude – smaller. Effects of intraspecific competition on the growth of individuals are revealed. Negative effects of the competition authentically revealed in elder age groups were not observed in younger age groups. An increase of the Yellowfin sole abundance brings negative effects on maturation rate of males with almost no such effects on females. To the greatest extent such effects can be seen in young age groups, at the beginning and middle stage of maturation.

Some data on the biology of stone cockscomb Alectrias alectrolophus (Stichaeidae) from the Tauysk Bay of the Sea of Okhotsk

On the basis of the materials collected in the period of 2010–2018 the features of biology: the size-age structure, linear growth pattern and body mass growth of the stone cockscomb Alectrias alectrolophus from the Tauysk Bay, the Sea of Okhotsk, have been studied. In the intertidal zone, in the period from May to September, individuals of this species the body length 31.2–133.4 mm and body weight 0.1–12.8 g at the age of up to 6+ years are found in large quantities. The size and age characteristics, rates of growth of females and males are quite similar, but in general, females are slightly larger than males.

Spring distribution of capelin Mallotus villosus catervarius in the eastern part of the Sea of Okhotsk in 2000–2019

Data on the local distribution of capelin in the eastern part of the Sea of Okhotsk in 2000–2019 are very limited. Maps of the distribution were made based on results of complex pelagic surveys in 2000–2019. It is demonstrated, that spring distribution of capelin in the Eastern Sea of Okhotsk varied depending temperature conditions in each particular year. Major aggregations of capelin were observed within Shelikhov Gulf in spring. In the “cold” years these aggregations were in the south-western part of the West Kamchatkan shelf, and in the “warm” years – in the north-western part. In sense of bathymetric distribution the main body of the capelin aggregations was observed in the upper part of the shelf at the depth <125 m at the temperatures bit lower zero.

Gobies of the Sculpins family (Cottidae) as a promising commercial objects for fishing in the northern part of the Sea of Okhotsk

On the basis of materials collected in 2012-2020, the ecology, the current state of the stock and some features of the biology of gobies of the Sculpins family living in the northern part of the Sea of Okhotsk, as well as the dynamics of their catch, are considered. The prospects for industrial development are shown.

Probability assessment of possible ice encounters during the petroleum hydrocarbons transportation in the Sea of Okhotsk

The increase in freight traffic along the Northern Sea Route necessitates the study of the ice regime of the freezing seas of Russia, including the Far Eastern ones (Bering Sea, the Sea of Okhotsk and the Sea of Japan). This paper, on the basis of the analysis of the Sea of Okhotsk’s ice cover and the location of the edges of the Sea of Okhotsk’s ice massif, evaluates the probability of an encounter with ice for the ships in transit during cargo transportation on the Northern Sea Route through the Far Eastern seas along two basic routes from the southern tip of the Kamchatka Peninsula: 1) traverse Cape Lopatka–Sea of Okhotsk–La Perouse Strait; 2) traverse Cape Lopatka–Sangarsky Strait. It was shown that at the stage of ice cover maximum development in the Sea of Okhotsk (February-March), route No. 2 was the most adequate and the safest for ships of ice class Arc4 and below. The section of route No. 1 with a 70 % ice encounter probability was 421 km long in February and 382 km long in March. That section of the route was dominated by very cohesive first-year thin ice up to 70 cm thick with inclusions of first-year ice of average thickness (up to 120 cm).

Transformation of baroclinic tidal waves in the conditions of the shelf of the Far Eastern seas

This work is devoted to the study of the regimes of transformation of baroclinic tidal waves under the conditions of the Far Eastern seas within the framework of a fully nonlinear numerical model. Two sections were selected to study the features of wave dynamics – in the Sea of Okhotsk (Sakhalin Island shelf) and in the Bering Sea (near Cape Navarin). On the basis of the performed calculations, regional and seasonal features of the transformation of baroclinic waves and the structure of the flow induced by them were revealed. It is shown that the dynamics in the winter season is less intensive. The rotation effect on the formation of solibore in the studied conditions is analyzed. The obtained estimates of wave amplitudes and velocities are consistent with the published data of field observations in the Sea of Okhotsk. For the Bering Sea, the conditions are shown to be favorable for the generation of intensive internal waves, which indirectly confirms the hypothesis of influence of such waves on the formation of underwater sand dunes.

Trace element composition of the Southwestern Sakhalin Chum Salmon

The study is devoted to the microelement composition of organs and tissues of chum salmon (Oncorhynchus keta), which came for spawning in September 2018 in the r. Lovetskaya on the southwestern coast of Sakhalin. Samples of organs and tissues of fish, prepared in Sakhalin, were frozen and delivered to Vladivostok for chemical analysis. Trace elements were determined from acid mineralizates by atomic absorption on a Shimadzu AA 6800. It was found that the content of microelements indicating anthropogenic impact on the environment (Zn, Cu and Ni) in the Sea of Japan chum was significantly higher than the content of those in the Okhotsk Sea fish. So, for example, the amount of zinc in the muscles of the Sea of Japan chum salmon was 2.5 times higher than in those of the Sea of Okhotsk fish. In the liver, the effect was even greater - the difference between the content of this element in the Sea of Japan and the Sea of Okhotsk reached 19 times. At the same time, in the organs and tissues of the Okhotsk chum salmon, which crossed the impact geochemical zone in the Kuril-Kamchatka region at least twice during its life cycle, the content of lead and cadmium, witnesses of underwater and surface volcanism in the Kuril straits, prevailed. The content of lead in the muscles of chum salmon from r. Raidovaya was 4 times more than in the muscles of chum salmon from the river. Lovetskaya; in the liver, the difference was 5 times.