Sakhalin Bay Research Articles

Pacific salmon monitoring results in Sakhalin Bay in 2023

The purpose: getting up-to-date information about the summer anadromous migration in 2023 and the qualitative indicators of Pacific salmon in the Sakhalin Bay (Khabarovsk Territory).Methods used: the work was carried out in accordance with the methods generally accepted in fisheries research.Result: Up-to-date information about the beginning of spawning approaches of pink salmon and chum salmon in the Sakhalin Bay has been obtained. The number of fishing areas and the dynamics of pink salmon catch in the southern, central and northern parts of the Sakhalin Bay are indicated. It is noted that the commercially significant approaches of pink salmon began from the southern part of the bay. The main biological characteristics of pink salmon and chum salmon suitable for the rivers of the Sakhalin Gulf in 2023 are given.Practical significance: Information on the migration of Pacific salmon in the Sakhalin Bay and their qualitative indicators will be used in the preparation of materials justifying the projected catch volumes in subsequent years, as well as in the regulation of Pacific salmon fishing in the Sakhalin Bay area.

Results of monitoring on pacific salmon in the Sakhalin Bay in 2023

Results of monitoring on pacific salmon in the Sakhalin Bay in 2023

Observations of western gray whales by ship-based whalers in the 19th century

Animals belonging to the small, endangered population of western gray whales (Echrichtius robustus) are observed today primarily during the summer open-water season in feeding areas off the northeastern coast of Sakhalin Island, Russia. The migration route(s) and wintering area(s) used by this population are largely unknown. Gray whales once had a fairly extensive distribution in the Sea of Okhotsk but little detailed information has been published on when and where they occurred. Open-boat, ship-based whalers from the United States and a few other countries conducted an intensive hunt for bowhead whales (Balaena mysticetus) and North Pacific right whales (Eubalaena japonica) in the Sea of Okhotsk from the 1840s to 1870s. According to entries in voyage logbooks, the American whalers regularly encountered (and sometimes hunted) gray whales in the far northeastern corner of the Okhotsk Sea (Shelikhov Bay, Gizhiginskaya Bay and Penzhinskaya Gulf) between early May-late August. They also observed gray whales in summer along the northern coast of the sea (especially Tauskaya Bay), around the Shantar Islands, in Sakhalin Bay, off Cape Elizabeth at the northern tip of Sakhalin Island and along the west coast of the Kamchatka peninsula. No evidence was found in the logbooks studied of gray whales (and indeed of whaling effort) off northeastern Sakhalin Island where most observations of gray whales occur in the present day.

Macrozoobenthos of the Sakhalin bay of the Sea of Okhotsk in the zone of influence of Amur river waters

Structure, quantitative indicators, distribution features and main communities of macrozoobenthos of Sakhalin Bay (the Sea of Okhotsk) are described. Mollusks (mainly bivalves), crustaceans and sea urchins determined the total macrozoobenthos biomass. The main regularities of the macrozoobenthos distribution in the bay are given. Two zones are distinguished by hydrological characteristics, distribution of the composition and quantitative characteristics of macrozoobenthos, benthic communities, and according to the data of ordination analysis: the zone of localization of the runoff lens of the Amur River with a water salinity of less than 26 psu and the zone of distribution of typical marine waters. 9 benthic communities are described: the »estuarine-lagoonal» communities of Archaeomysis grebnitzkii + Haustorioides magnus + Potamocorbula amurensis, Potamocorbula amurensis, Macoma balthica + Cyrtodaria kurriana, Siliqua alta, the typically »marine» communities of Nephtys caeca, Serripes groenlandicus, Balanus crenatus and the communities of transitional type Saduria entomon and Echinarachnius parma, which are found in both hydrological zones. Predominantly filter feeders, with a significant role of detritus feeders and detritus feeders – filter feeders, form the trophic structure of macrozoobenthos. Trophic communities dominated by filter feeders - detritus feeders and detritus feeders are represented in the coastal area of the western part of the water area, the group of filter-feeders is localized seaward. Trophic communities with a predominance of filter feeders - detritus feeders and detritus feeders are represented in the entire depth range of the eastern part of the water area. Water salinity, soil type and depth are the main factors affecting the distribution and abundance of macrozoobenthos.

Spatial Distribution and Provenance of Detrital Minerals of Surface Sediment in the Okhotsk Sea

The Okhotsk Sea is a distinctive marginal sea in the northwestern Pacific Ocean, which is characterized by the prevalence of seasonal sea ice in winter. Sediment is sourced from the around region through sea ice transportation, rivers input, and volcanic eruptions. Surface sediments of the Okhotsk Sea shelf vary greatly in grain size, and the sand content is generally high, which is conducive to source-to-sink studies using ice-rafted detritus (IRD),detrital minerals and single mineral geochemistry methods. In this paper, the 63–125 μm grain size fraction was selected for the detrital minerals analysis of surface sediments (top 0–10 cm) from 58 sediment stations and 15 stations samples has been chosen for garnet chemistry. These stations are mainly located in the south central Okhotsk Sea. The distribution and composition of the heavy minerals are influenced by material derived from the Amur River, the north shelf (Okhotsk-Chukotka volcanic belt), Sakhalin Island, the Kamchatka Peninsula, and the Kuril Islands. The detrital mineral results show that hornblende, epidote and garnet are terrigenous material indicators. High contents of fresh hypersthene can be used as an indicator of volcanic eruption materials. And high content of abraded hypersthene can be used as an indicator of Okhotsk-Chukotka volcanic materials. In the northern Okhotsk Sea, the southward moving sea ice produced in Sakhalin Bay collides with the sea ice produced off the east coast of Sakhalin Island, which causes the sea ice to accumulate to the southeast. This results in the deposited ice-rafted debris having a southeastward facing fan shape, and the geochemical analysis of the garnet supports this conclusion. From west to east, the amount of material from Sakhalin Island gradually decreases, while the amount of material from the Amur River and Chukchi-Kamchatka increases.

МИНЕРАЛЬНЫЙ СОСТАВ ОСАДКОВ КАК ИНДИКАТОР ИСТОЧНИКОВ ПОСТАВКИ И ОСОБЕННОСТЕЙ РАСПРЕДЕЛЕНИЯ ОБЛОМОЧНОГО МАТЕРИАЛА В ОХОТСКОМ МОРЕ

The mineral composition of the heavy subfraction from surface sediments of the Okhotsk Sea was studied using both two detailed profiles (Magadan-Kuril Islands and Shantar Islands-Central Basin) and data from the Sakhalin Bay. The obtained data were analyzed using the methods of multivariate statistics, which allowed to identify the main associations of heavy minerals and to show regional differences in mineral complexes of marine sediments. A significant effect of solid Amur River discharge on sedimentation processes is traced. The main processes responsible for the formation of the mineral appearance of studied sediments are determined. Two large regional sources of clastic material – the Amur-Sakhalin and Kuril-Kamchatka supplying provinces – had a major influence on the formation of mineral composition of the sediments.

Distribution, fishery and some features of biology for Sclerocrangon salebrosa and Argis lar (Caridea, Crangonidae) in the northwestern Okhotsk Sea

Trawl fishery of shrimps Sclerocrangon salebrosa and Argis lar in the Sakhalin Bay of the Okhotsk Sea has started in 2014 and develops rapidly. Meanwhile, spatial distribution of these species is not known well and their biology and stock dynamics are not studied. State of the fishery and distribution patterns of S. salebrosa and A. lar in the northwestern Okhotsk Sea are investigated on the data collected by the authors aboaed commercial fishing vessels and in the accounting trawl survey conducted aboard RV Dmitry Peskov in summer of 2019, as well as some features of their biology are considered. In total, 542 commercial trawl catches collected in 2015–2019 with horizontal opening 36 m from the depth of 39–140 m and 147 trawl catches collected during the survey with horizontal opening 16 m from the depth of 11–321 m are analyzed; 21,590 shrimp specimens caught within the period from June 23 to November 2 are examined. During 2014–2019, the number of shrimp fishing vessels in the Sakhalin Bay has increased from 1 to 6, their annual landing — from 78.7 to 642.0 t (376 t of S. salebrosa and 266 t of A. lar in 2019). Their mean catch per unit effort varied from 48 to 108 kg/hr of trawling for S. salebrosa and from 40 to 87 kg/hr for A. lar, with the average catch per trawling 379 and 346 kg, and average daily catch 1380 and 1144 kg, respectively. Night catches of S. salebrosa were in 2.7 times higher than the daily catches, on average (104.7 ± 45.7 kg/hr vs 39.1 ± 31.8 kg/hr); night catches of A. lar were in 2.0 times higher than the daily catches (80.2 ± 39.0 kg/hr vs 39.6 ± 34.2 kg/hr). Portion of A. lar in the summary catches of two species varied from 4 to 88 %, on average 48 %; besides, by-catch of fish (flounders, saffron cod, pollock, cod, sculpins, herring) and humpy shrimp Pandalus goniurus was considerable. So, the portion of the most valuable species (sculptured shrimp S. salebrosa) did not exceed ⅓ of the total catch, on average. The actual annual catches exceeded significantly the recommended volumes in 2017–2019, up to 164 % for S. salebrosa and 156 % for A. lar. According to results of the trawl survey in 2019, spatial distribution patterns for S. salebrosa and A. lar coincide in details in the northern Okhotsk Sea: both species are distributed at the depth between 20–145 m, with the densest aggregations (> 60 % of both stocks) located between Bolshoi Shantar Island and the northern tip of Sakhalin, southward from 55о 30′ N, where their biomasses reach 434 kg/km2for S. salebrosa and 68 kg/km2 for A. lar. Total commercial stocks of these species within the North Okhotsk Sea fishery district were assessed in 2019 as 16.0 . 103 t for S. salebrosa and 3.8 . 103 t for A. lar. Reproductive cycles of S. salebrosa and A. lar females in the Okhotsk Sea are fundamentally the same as the cycle of former species in Peter the Great Bay (Japan Sea), with their total duration of 48 months including 24 months for the gonads development until spawning and 24 months from the spawning to hatching of larvae. In the Okhotsk Sea, spawning of S. salebrosa and A. lar occurs most likely in spring; mass hatching of their larvae — in summer.

Distribution of Desalinated Waters of the Amur Estuary in the Okhotsk Sea According to Satellite Observations

The distribution of the desalinated waters of the Amur Estuary in the Northwestern ​​Okhotsk Sea during the summer period was analyzed using satellite data on sea level, salinity, temperature and concentrations of suspended organic carbon. There is good agreement between the spatial distribution of surface water salinity (data from the SMAP satellite) and the sea level (AVISO data) in the study area. The identification of the waters of the Amur Estuary by the surface water temperature and the concentration of suspended organic carbon is limited to the Sakhalin Bay and the coastal waters of Sakhalin Island. An increase (decrease) in the flow of the Amur River during the spring-summer flood leads to an increase (decrease) in sea level in the northern part of the Sakhalin Bay in July. Strengthening of the northwestern (southeastern) winds in September reduces (increases) the inflow of waters with low salinity and elevated sea level to the area north of the Sakhalin Bay.

СЕЗОННАЯ ИЗМЕНЧИВОСТЬ ГИДРОЛОГИЧЕСКИХ ХАРАКТЕРИСТИК НА СЕВЕРО-ВОСТОЧНОМ ШЕЛЬФЕ О. САХАЛИН

The long-term mean temperature and salinity distributions on 5 standard oceanological sections on the northeast shelf of Sakhalin were analyzed for 4 months of the navigation period (July-October) including a radical restructuring of hydrological conditions in the transition from summer to autumn. The data of soundings performed during the pollock ichthyoplankton surveys were used to study oceanological conditions in June. The low salinity water formed by the Amur River runoff are shown to appear on the northeastern shelf in the first half of June after the heavy ice breaking in the southern Sakhalin Bay. Low salinity water and ice are pushed off toward the deep sea under the influence of the southern winds typical for a warm season, and an oceanological front is formed near the 52°N. This front prevents the low-salinity water from flowing southward until the second half of September, when changes into a winter monsoon with the prevailing northerly winds take place. This promotes destruction of hydrological front and deepening of the cold intermediate water layer. The waters with the 4–6°C temperature and salinity of about 31 psu occur at the shelf edge along the northeastern Sakhalin coast. A powerful stream with the relatively warm low salinity water is being formed along the shore that reaches the southeastern part of Sakhalin and northern coasts of Hokkaido Island.

The distribution of the desalinated waters of the amur estuary in the okhotsk sea according to satellite observations

The distribution of the desalinated waters of the Amur Estuary in the Northwestern ​​Okhotsk Sea during the summer period was analyzed using satellite data on sea level, salinity, temperature and concentrations of suspended organic carbon. There is good agreement between the spatial distribution of surface water salinity (data from the SMAP satellite) and the sea level (AVISO data) in the study area. The identification of the waters of the Amur Estuary by the surface water temperature and the concentration of suspended organic carbon is limited to the Sakhalin Bay and the coastal waters of Sakhalin Island. An increase (decrease) in the flow of the Amur River during the spring-summer flood leads to an increase (decrease) in sea level in the northern part of the Sakhalin Bay in July. Strengthening of the northwestern (southeastern) winds in September reduces (increases) the inflow of waters with low salinity and elevated sea level to the area north of the Sakhalin Bay.

ПАЛЕОМАГНЕТИЗМ И ПЕТРОХИМИЯ ПЕСЧАНИКОВ ГОРИНСКОЙ И ПИОНЕРСКОЙ СВИТ ЖУРАВЛЕВСКО-АМУРСКОГО ТЕРРЕЙНА (СЕВЕРНЫЙ СИХОТЭ-АЛИНЬ)

The first paleomagnetic and petrochemical data on the Lower Cretaceous sedimentary rocks of the Komsomolsk Series from the Zhuravlevka–Amurian turbidite paleobasin are presented. The rocks are collected in coastal outcrops of Sakhalin Bay (54.09° N, 140.05° E). The studies reveal that (1) the petrochemical characteristics of the sedimentary rocks of the Gorinskaya and Pionerskaya formations (Berriasian–Valanginian) do not contradict the model of their formation in a setting of the transform continental margin; (2) the paleolatitude at which they attained pre-folding paleomagnetic direction (Dec = 303°, Inc = 27°, Ks/Kg = 6.2) was 10–18° N; (3) in the post-Valanginian time, before 95 Ma B.P., the block including these rocks moved northward by 3900–4800 km along the Eurasian transform continental margin at a mean rate of about 10–13 cm/yr.

Regularities of reproduction for pink salmon Oncorhynchus gorbuscha from the Iska River

Reasons for rapid rise of pink salmon landings in the Sakhalin Bay (Okhotsk Sea) in the early 21 century are analyzed. Dependence of its juveniles and adults numbers on the number of their parents is well described with Ricker equation, and the recruitment depends linearly on the number of juveniles in the river. Several factors of the pink salmon reproduction are compared between the early 21 century and previous period. There is found that recent in­crease of the catches could not be reasoned by favorable changes of environments, decreasing of juveniles mortality either in the river or in the sea, extending of spawning grounds, growth of spawning stock or number of juveniles. The only possible reason for significant rise of the landings could be an increasing by-catch of transitory stocks.

Movements of spotted seals (Phoca largha) in the Sea of Okhotsk according to satellite tagging data

For the first time, satellite tagging of spotted seals (Phoca largha) has been performed in three regions of the Sea of Okhotsk: Chkalov Island in Sakhalin Bay, Ptichy Island, and the Bolshaya River mouth on the western coast of Kamchatka. As a result, regions inhabited by the seals in different periods of their life cycle and differences in the pattern of water area use by animals from different regions have been revealed. The seals from the western Kamchatka coast have covered greater distances during the observation period, compared to the animals from Sakhalin Bay. In the reproductive period, the seals from the western coast spread over the entire northern part of the Sea of Okhotsk, whereas the animals from the Sakhalin Bay move only to the Tatar Strait, the Sea of Japan. None of tagged seals has been located in the “reproductive center” at the eastern coast of Sakhalin. The seals tagged in different regions of the Sea of Okhotsk have never been located in the same place during the entire annual cycle, suggesting that the sea is inhabited by two reproductively isolated groups of ringed seals.

Juveniles of pink and chum salmon in the Iska River (Sakhalin Bay, Okhotsk Sea) in the fresh-water period

Juveniles of pink and chum salmon are investigated in the Iska River flowing into the Okhotsk Sea. The pink juveniles begin their seaward migration in May, with the ice melting, the migration lasts about 40 days, approximately from May 20 to July 5. The seaward migration of chum juveniles begins in the same time but ends in 5-10 days later. The portion of pink salmon fry with the remains of yolk sac is 82-94 %; even in the end of their migration it is rather high, up to 76 %. This species juveniles begin to feed in the river, in particular in «dry» years, the portion of feeding fry increases with disappearance of the yolk sac up to 78 % (by the stomach fullness). Both pink and chum juveniles migrate at night only. Hydrological conditions influence on the timing of migration: it is close to normal dates in conditions of high water level and strong water flow but delayed in conditions of low water discharge (that’s why the portion of juveniles feeding in the river is higher in those years). Year-to-year dynamics of the juveniles and spawners abundance is traced for the 1951-2012. The pink salmon escapement to the Iska changed from 11.0 · 10 3 (in 2004) to 1344.4 · 10 3 (in 1958) ind., on average 280.0 · 10 3 ind. for even years and from 22.7 · 10 3 (in 1959) to 2005.8 · 10 3 (in 2007) ind., on average 372.9 · 10 3 ind. for odd years. The number of pink salmon downstream migrants changed from 0.8 · 10 6 (in 1954) to 40.9 · 10 6 (in 1964), on average 10.9 · 10 6 ind. for even years and from 1.0 · 10 6 (in 2005) to 41.8 · 10 6 (in 1957), on average 8.9 · 10 6 ind. for odd years.

Spatial variability in iron nutritional status of large diatoms in the Sea of Okhotsk with special reference to the Amur River discharge

Abstract. The Sea of Okhotsk is known as one of the most biologically productive regions among the world's oceans, and its productivity is supported in part by the discharge of iron (Fe)-rich water from the Amur River. However, little is known about the effect of riverine-derived Fe input on the physiology of the large diatoms which often flourish in surface waters of the productive continental shelf region. We conducted diatom-specific immunochemical ferredoxin (Fd) and flavodoxin (Fld) assays in order to investigate the spatial variability of Fe nutritional status in the microplankton-sized (20–200 μm; hereafter micro-sized) diatoms. The Fd index, defined as the proportion of Fd to the sum of Fd plus Fld accumulations in the cells, was used to assess their Fe nutritional status. Additionally, active chlorophyll fluorescence measurements using pulse–amplitude-modulated (PAM) fluorometry were carried out to obtain the maximum photochemical quantum efficiency (Fv/Fm) of photosystem II for the total micro-sized phytoplankton assemblages including diatoms. During our observations in the summer of 2006, the micro-sized diatoms were relatively abundant (> 10 μg C L−1) in the neritic region, and formed a massive bloom in Sakhalin Bay near the mouth of the Amur River. Values of the Fd index and Fv/Fm were high (>0.9 and >0.65, respectively) near the river mouth, indicating that Fe was sufficient for growth of the diatoms. However, in oceanic waters of the Sea of Okhotsk, the diatom Fd index declined as cellular Fld accumulation increased. These results suggest that there was a distinct gradient in Fe nutritional status in the micro-sized diatoms from near the Amur River mouth to open waters in the Sea of Okhotsk. A significant correlation between dissolved Fe (D-Fe) concentration and the Fd index was found in waters off Sakhalin Island, indicating that D-Fe was a key factor for the photophysiology of this diatom size class. In the vicinity of the Kuril Islands between the Sea of Okhotsk and the Pacific Ocean, micro-sized diatoms only accumulated Fld (i.e., Fd index = 0), despite strong vertical mixing consistent with elevated surface D-Fe levels (>0.4 nM). Since higher Fe quotas are generally required for diatoms growing under low-light conditions, the micro-sized diatoms off the Kuril Islands possibly encountered Fe and light co-limitations. The differential expressions of Fd and Fld in micro-sized diatoms helped us to understand how these organisms respond to Fe availability in the Sea of Okhotsk in connection with the Amur River discharge.

On the deep structure of the North Sikhote-Alin and North Sakhalin fold structures junction area

A gravity field interpretation is performed for the North Sikhote-Alin and North Sakhalin fold structures junction area using the COSCAD-3D software package, and petrodensity and petromagnetic maps are compiled, thus making it possible to obtain new data on the petrophysical features and the deep structure of the area under study. As a result of the complex geophysical and petrophysical data’s interpretation, a sketch map of the disjunctive tectonics is compiled and the circular structure featuring a unique rock fill caused by the influence exerted by the mantle’s deep structure is identified and can be considered as a magma chamber structure with the center being in the North Sakhalin Bay.

A genetic analysis of the beluga whale Delphinapterus leucas (Cetacea: Monodontidae) from summer aggregations in the Russian Far East

The genetic structure of four summer aggregations of the Beluga Whale, Delphinapterus leucas, in Sakhalin Bay and Udskaya Bay, off the western coast of Kamchatka in the Sea of Okhotsk and in the Anadyr Estuary of the Bering Sea was analyzed through nucleotide sequencing of the mtDNA control region and detection of the allelic composition of nine microsatellite loci in nuclear DNA. It has been shown that each of the aggregations features a unique set of maternal lines, which indicates a high degree of philopatry in this species. Beluga whales of the Anadyr Estuary are genetically isolated from those of the Sea of Okhotsk. Beluga whales of the summer aggregations of Sakhalin Bay and those from Udskaya Bay share a common gene pool and belong to a single population, while the whales that summer off western Kamchatka with great consistency may be attributed to a different population. Comparison of nucleotide sequences of the mtDNA in beluga whales from various waters of the Russian Far East and North America allowed us to propose a hypothesis about how the structure of beluga whale populations formed in the North Pacific during the postglacial period.

The Amur River runoff formation in the Amur liman

Periodical surface currents with the periods of 46.5, 61, and 91 days detected from the satellite data in the Tatar Strait and Sakhalin Bay are presented as an effect of the Amur River runoff transformation in the estuary. The estuary transforms the flow as a flip-flop directing the Amur runoff by turns to the Sea of Japan or to the Sea of Okhotsk. The flip-flop period is six months. From May 23 to November 10, the Amur River flows into the Sea of Okhotsk and from November 10 to May 25, into the Sea of Japan.

Iron nutritional status of the phytoplankton assemblage in the Okhotsk Sea during summer

To clarify the iron (Fe) nutritional status of the phytoplankton assemblage in the Okhotsk Sea, we conducted incubation experiments in summer 2006. Replicate surface seawater samples with the natural plankton community were incubated with three treatments: Fe enrichment; addition of the strong Fe chelator siderophore desferriferrioxime B (DFB) which strips Fe from the biologically accessible pool; and as a control, no addition. To prevent macronutrient limitation, we added surplus nutrients to all treatments. At all 4 stations in Sakhalin Bay near the mouth of the Amur River and around the east of Sakhalin Island, net specific growth rate showed no significant difference between the control and +Fe treatment, and was repressed in +DFB treatment both in large- and small-sized phytoplankton. These findings indicate that these waters contain sufficient bioavailable Fe and that the Amur River plume which is transported by the east Sakhalin current is a major source of the Fe. In the Bussol’ Strait, net specific growth rate in the control was significantly higher than +DFB treatment, suggesting a supply of bioavailable Fe through intense vertical mixing at this site. Iron enrichment treatment stimulated the net specific growth rate of large-sized phytoplankton, indicating that Fe still limits the growth for the large-sized phytoplankton assemblage, but not for small-sized phytoplankton, in this area. An index of Fe availability was defined to quantify the degree of ambient Fe availability in each station, and it revealed the spatial variability of ambient Fe availabilities among the sites.

Influence of the Amur River runoff on the hydrological conditions of the Amur Liman and Sakhalin Bay (Sea of Okhotsk) during the spring-summer flood

Hydrographic and satellite observation data obtained in June 2007 enabled to study the influence of the Amur River runoff on the hydrological conditions of the Amur Liman and the Sea of Okhotsk during the spring-summer flood. Salt waters from the Sea of Japan and fresh Amur River waters mix in the estuary (the Amur Liman). Freshened waters flow from the estuary into the Sea of Okhotsk as a jet-like flow drift, which forms a recirculating anticyclonic gyre in the Sakhalin Bay. The coastal current associated with the Amur River flow was obserwed near Sakhalin Island coast. The computed values of dynamic parameters (Kelvin number K=2, Froude number F = 0.4) showed that the Earth rotation and stratification are important factors in the dynamical balance of the Amur River plume during the spring-summer flood event.