Eastern Sakhalin Research Articles

Life History and Production of the Western Gray Whale's Prey, Ampelisca eschrichtii Krøyer, 1842 (Amphipoda, Ampeliscidae).

Ampelisca eschrichtii are among the most important prey of the Western North Pacific gray whales, Eschrichtius robustus. The largest and densest known populations of this amphipod occur in the gray whale’s Offshore feeding area on the Northeastern Sakhalin Island Shelf. The remote location, ice cover and stormy weather at the Offshore area have prevented winter sampling. The incomplete annual sampling has confounded efforts to resolve life history and production of A. eschrichtii. Expanded comparisons of population size structure and individual reproductive development between late spring and early fall over six sampling years between 2002 and 2013 however, reveal that A. eschrichtii are gonochoristic, iteroparous, mature at body lengths greater than 15 mm and have a two-year life span. The low frequencies of brooding females, the lack of early stage juveniles, the lack of individual or population growth or biomass increases over late spring and summer, all indicate that growth and reproduction occur primarily in winter, when sampling does not occur. Distinct juvenile and adult size cohorts additionally indicate growth and juvenile production occurs in winter through spring under ice cover. Winter growth thus requires that winter detritus or primary production are critical food sources for these ampeliscid populations and yet, the Offshore area and the Eastern Sakhalin Shelf ampeliscid communities may be the most abundant and productive amphipod population in the world. These A. eschrichtii populations are unlikely to be limited by western gray whale predation. Whether benthic community structure can limit access and foraging success of western gray whales is unclear.

Geomorphological aspects of the problem of protecting the shores of the Sakhalin Island

The presence of the frozen grounds on the coasts including the barrier lagoon ones, thermo-abrasion observed on some sites, the presence of shore ice and icings lasting up to the end of May, allow to consider the shores of the north-western and eastern Sakhalin as subarctic type. It was determined that during last 50 years more than 15 км 2 of accumulated plain was lost as a result of shore erosion only in the north and south-east of Sakhalin Island. The spatial structure of erosion has existed in its general outline since the 1930s. Since 1940 the extension of eroded shores has enlarged nearly two times. The spatial rhythms of erosion with wave length about 30 and 60 km determine the main regularities of shore erosion pattern. The formation of non-uniformity of beach structure and accordingly the irregular distribution of its wave-decreasing properties along the shore were considered. On the seashore of Sakhalin more than thirty sites were found, where quasi-rhythmic forms of shore relief were observed. But all the deformations of underwater relief were observed only in the frames of rated close depth. The special attention was devoted to the changes of wave-suppression characteristics of the beach during beach deposits freezing and under the open sea influence. The freezing of the 40-50 cm of the upper parts of shore profile and decrease of wave-suppression characteristics (mainly drainage and roughness), caused by this, occurred during this period before the formation of the shore ice and icings (1.5–2 months). According to the observations the height of swash zone increases by 30–45%. The calculations showed that the height of wave run-up for bank slope of storm bar may increase owing to freezing by 2–2.5 times.

Spatial distribution and long-term dynamics of biomass of demersal fish in the zone of the Eastern Sakhalin current (Sea of Okhotsk)

According to bottom trawl surveys of 1988–2012, spatial distribution, structure, and dynamics of biomass of demersal ichthyocenosis in the northeastern waters of Sakhalin are analyzed. It is shown that the shelf zone is of decisive importance for formation of fish aggregations in this region. Main fish aggregations in the region are confined to the zone of widened shelf near northeastern lagoons of the island at 52°–53° N. Demersal ichthyocenoses are represented mainly by mass species of Gadidae, Pleuronectidae, and Cottidae. Main trends of long-term dynamics of fish biomass of eastern Sakhalin waters are similar to those in waters of northeastern (Kamchatka) and southeastern (south Kurils) parts of the Sea of Okhotsk. Long-term data indicate a tendency for an increase in the total biomass of fish in the periods of sea warming that are favorable for appearance of strong-year classes in mass species.

New data on the systematics of the Palaearctic species of the Dolichopus longisetus Negrobov, 1977 group (Diptera, Dolichopodidae)

Three new species of the Dolichopus longisetus Negrobov, 1977 group, Dolichopus kasakhstaniensis sp. n. from Kazakhstan, Dolichopus venturii sp. n. from Italy, and Dolichopus shamshevi sp. n. from various regions of Eastern Siberia, Amurskaya Province, Primorskii Territory, and Sakhalin Island, are described.

Reconstructed summer temperatures over the last 400 years based on larch ring widths: Sakhalin Island, Russian Far East

A new ring-width record from the eastern flanks of the Eastern Sakhalin Range, Sakhalin Island, Russian Federation is significantly correlated with summer temperatures and allows for the reconstruction of May–July average temperatures for the past 400 years. The reconstruction explains 37 % of the variance in May–July temperatures and shows a strong cooling between 1680 and 1710 CE coincident with the Maunder solar minimum and in agreement with other independent tree-ring reconstructions and glacier histories from sites along the margin of the Sea of Okhotsk. While recent decades are among the warmest in the record they are rivaled by periods centered on 1650 and 1850 CE. Warming in the observational record and the reconstruction is consistent with the influence of the declining strength of the Siberian High and loss of sea ice over the same interval. Decadal (17–25 year) variability persists throughout the reconstruction. At interannual timescales the Sakhalin reconstruction is most strongly correlated with local and central North Pacific sea surface temperatures over the past 120 years, whereas at decadal timescales there is an additional association with Asian land surface temperatures.

Distributions of dissolved organic carbon and nitrogen in the western Okhotsk Sea and their effluxes to the North Pacific

The Okhotsk Sea is considered the only ventilation source area for North Pacific Intermediate Water (NPIW), which is widely distributed in the low and middle latitudes of the North Pacific. Previous studies have confirmed high levels of dissolved organic carbon (DOC) in NPIW, yet the amounts and the processes driving DOC export from the Okhotsk Sea are poorly understood. In this study, concentrations of DOC and dissolved organic nitrogen (DON) were measured in the western Okhotsk Sea during the summer of 2006, and additional DOC measurements were made during the late spring of 2010. Results indicate that DOC transport to the intermediate waters (26.7–27.0 σθ) occurs through two processes. The first process involves the spread of water discharged from the continental shelf (Dense Shelf Water), which contributes to a DOC and turbidity maxima in the 250–300m layer of Okhotsk Sea Mode Water (OSMW) located off the eastern Sakhalin coast. The second process involves diapycnal mixing in the Kuril Basin and the Bussol’ Strait, where DOC is transported to a depth greater than 800m. The ratio of DOC:DON in OSMW was significantly higher in the Kuril Basin and Bussol’ Strait than off of the Sakhalin coast, which suggests that the transport of terrigenous organic matter from the bottom occurs in the former regions. DOC and DON efflux from the Okhotsk Sea to the intermediate layer in the North Pacific water (26.7–27.0 σθ) were estimated to be 68–72TgCyr−1 and 5.4TgNyr−1, respectively, for which the DOC transported by diapycnal mixing accounts for 37%. We conclude that diapycnal mixing in the Kuril Basin and Bussol’ Strait regions could play a significant role in regulating the quality and quantity of DOC exported to the intermediate water in the North Pacific.

Igneous rocks of the Val’za terrane in the Eastern Sakhalin Mountains

Igneous rocks of the Val’za terrane in the Eastern Sakhalin Mountains

Tectonic zoning of the sedimentary cover in the Deryugin basin of the Sea of Okhotsk based on structural-material (lithophysical) indicators

In terms of tectonics, the Deryugin basin (Fig. 1) is a part of the epi-Mesozoic Okhotsk plate comprising the heterogeneous basement that is mainly pre-Cenozoic (the lower structural stage) and the sedimentary cover that is mainly represented by the Paleogenic-Neogenic-Quaternary deposits with the Upper Cretaceous sedimentary rocks observed locally without a visible hiatus (the upper structural stage). The acoustic basement (AB) is composed of the metamorphosed Upper Cretaceous-Paleogenic silty-clayey-siliceous deposits (the western part of the region), amphibolites, gneisses, crystalline schists, weakly metamorphosed sandstones, siltstones, and mudstones (often siliceous), as well as intrusive and effusive rocks of basic, intermediate, and rarely persilic composition (the eastern part of the region). AB is generally dated as Mesozoic–Paleozoic. Results of tectonic zoning of the sedimentary cover based on material (lithophysical) indicators (Fig. 2) are represented in the format of maps showing lithophysical complexes (LC) within the limits of four regional seismo-stratigraphic complexes/structural layers (RSSC I-IV) corresponding to the following time intervals: the pre-Oligocene К2–P1-2 (RSSC I), the Oligocene – Lower Miocene P3–N11 (RSSC II), the Lower – Mid Miocene N11–2 (RSSC III), and the Upper Miocene – Pliocene N13–N2 (RSSC IV). Diverse lithological-facies associations composing the RSSCs are grouped into the following lithophysical complexes (LC): 1 - coal-bearing silty-clayey-sandy terrigenous, 2 - sandy-silty-clayey terrigenous, 3 - silty-clayey-siliceous, and 4 - sandy-silty-clayey volcanic [Sergeyev, 2006]. In the studied area (Fig. 2), the deposits of the pre-Oligocene RSSC are identified in limited areas within its northern, northwestern, and southwestern parts; they are represented by coal-bearing silty-clayey-sandy terrigenous and silty-clayey-siliceous LCs. Other RSSCs (II, III, and IV) in this area represented mostly by sandy-silty-clayey terrigenous and silty-clayey-siliceous LCs, and only the extreme southwestern part along the eastern Sakhalin coast contains narrow bands of the coal-bearing silty-clayey-sandy LC. The sandy-silty-clayey volcanic LC is absent in the Deryugin basin. Tectonic zoning of the sedimentary cover based on structural indicators is carried out with reference to the sediment-thickness map [Sergeyev, 2006] that was significantly revised in its segment showing the area of the Deryugin basin. Results of such zoning are represented in the format of a structural-tectonic map (Fig. 3) showing orientations and morphology of the structural elements of the sedimentary cover, the thickness of the sedimentary cover, and amplitudes of relative uplifts and troughs. With reference to the structural-tectonic map (see Fig. 3), the structural elements of different orders are grouped by their sizes, spatial positions and orientations and thus comprise structural zones (Fig. 4) that include relative uplifts and troughs that are considered as structural elements of smaller sizes (Fig. 5). Tectonic zoning of the sedimentary cover based on structural-material (lithophysical) indicators (Fig. 7–10) is carried out with reference to the maps of the lithophysical complexes of the four regional seismo-stratigraphic complexes/structural layers (see Fig. 2) and the map of high-order structural elements in the sedimentary cover (see Fig. 5).

A new climatology of the Okhotsk Sea derived from the FERHRI database

This paper introduces a new hydrographic climatology of the Okhotsk Sea; this climatology was constructed from the Far Eastern Regional Hydrometeorological Research Institute (FERHRI) database. The FERHRI database has a volume of data three to five times larger than the data used in previous studies because unpublished Russian observation data have been included in the FERHRI database. After removing erroneous data from the database by pertinent quality control methods, the climatology for 1/4° × 1/4° grids is produced by applying objective analysis procedures. Features similar to those in previous studies are seen in the intermediate layers in the Okhotsk Sea, whereas our climatology provides values that fill in gaps in previous climatologies. It is obvious from the monthly climatologies that temperature and salinity distributions evolve in accordance with seasonal variations in the Eastern Sakhalin Current and inflow from the North Pacific. We also reconstructed climatologies for the winter mixed layer and dense shelf water from data obtained from the temperature minimum waters identified as the remnants of these two layers. Free access to the 1° × 1° versions of all climatologies constructed in this study is available through the website.

Soviet catches of right whales Eubalaena japonica and bowhead whales Balaena mysticetus in the North Pacific Ocean and the Okhotsk Sea

Both bowhead Balaena mysticetus and North Pacific (NP) right whales Eubalaena japonica were reduced to low levels by historical whaling. Despite their protected status, it is known that the USSR illegally killed both species in the NP and Okhotsk Sea (OS). Here, we pro- vide revised Soviet catch totals, as well as other new information on the distribution and other details of these catches. Right whale catches were made from 1962 to 1968 in the eastern NP and in 1967 and 1968 in the OS. Our best estimate of total right whale catches is 661, consisting of 529 for the eastern NP (compared to the previously published figure of 372) and 152 for the OS (cf. a previous figure of 136). Catches were distributed in the Bering Sea (BS, 115), eastern Aleutian Islands (28), Gulf of Alaska (GOA, 366), OS (132), and other areas (20). Detailed information on catches of 112 right whales taken in May/June 1963 shows a broad distribution in offshore waters of the GOA, consistent with 19th century historical whaling records. Other major areas in which right whales were caught include south of Kodiak Island, western Bristol Bay (southeastern BS), and the central OS off eastern Sakhalin Island. The best estimate of bowhead whale catches in the OS in 1967 and 1968 is 145 animals, although this is contingent upon certain assumptions regard- ing species identity. Of these, 79 were killed in the Shantar Islands region and 66 in Shelikhov Bay. The catches of both species primarily involved large mature animals, thus greatly inhibiting recovery of the populations concerned.

Fungal assemblages of submarine soils of the eastern Sakhalin shelf

This study reports on the biodiversity of facultative marine fungi in submarine soils of the eastern Sakhalin shelf for the first time. A total of 69 species that belong to 29 genera were isolated and identified. Fungal species associations of a freshened area and an oilfield adjacent to Piltun Bay were identified. The change in fungal species diversity along an environmental gradient was studied. This study showed that the adaptation of marine fungal assemblages to the presence of petroleum hydrocarbons in the environment was similar to that of micromycete communities of terrestrial soils.

Geodynamics of ophiolites and formation of hydrocarbon fields on the shelf of eastern Sakhalin

A model is proposed showing the formation of hydrocarbon fields on the shelf of eastern Sakhalin as being caused by sustained (from the Late Cretaceous to the present) extension in the adjacent deepwater Deryugin Basin with exposure of the upper mantle rocks at the bottom of the sedimentary basin. The thrust faults and detachments formed through this process facilitated the penetration of seawater into ultramafic rocks, thus providing large-scale serpentinization accompanied by generation of hydrocarbons. Extension in the Deryugin Basin was compensated by horizontal shortening at its margins, and as a result, by the formation of ophiolitic allochthons as constituents of the accretionary prism of eastern Sakhalin. Hydrocarbons were injected and pumped in the root zones of the allochthons, giving rise to their westward migration and the formation of petroleum pools in fault-line and underthrust traps on the shelf of Sakhalin Island. The Deryugin Basin is a petroleum-collecting area for oil and gas fields localized in the upper part of its western margin. More broadly, the work considers interrelations between hydrocarbon generation and the geodynamics of tectonic couples of ophiolitic allochthons and adjacent deepwater basins of marginal seas, in particular, in the western Pacific.

Wild and hatchery reproduction of pink and chum salmon and their catches in the Sakhalin-Kuril region, Russia

In the Sakhalin-Kuril region hatchery culture of pink and chum salmon is of great importance compared to other regions of the Russian Far East. During the last 30 years the number of hatcheries increased two-fold, and significant advances were made in hatchery technologies. As a result, chum salmon capture in regions where hatcheries operate (southwestern and eastern Sakhalin coasts, and Iturup Island) was 9 times as high during 2006–2010 than during 1986–1990, whereas wild chum salmon harvest markedly declined. Recent dynamics in pink salmon catch appear to track trends in natural spawning in monitored index rivers, suggesting natural-origin pink salmon play a dominant role in supporting the commercial fishery. It remains uncertain as to whether hatcheries have substantially supplemented commercial catch of pink salmon in this region, and I recommend continued research (including implementing mass marking and recovery programs) before decisions are made regarding increasing pink salmon hatchery production. Location of hatcheries in spawning river basins poses problems for structuring a management system that treats hatchery and wild populations separately. Debate continues regarding the existence and importance of density-dependent processes operating in the ocean environment and the role hatcheries play in these processes. Loss of critical spawning habitat for chum salmon in the Sakhalin-Kuril region has lead to significant declines in their abundance. I conclude by recommending increases in releases of hatchery chum salmon numbers in the region to help recover depressed wild populations and provide greater commercial fishing benefits in the region.

Population structure of chum salmon Oncorhynchus keta in the Russian Far East, as revealed by microsatellite markers

Chum salmon populations in the Russian Far East have a complex multi-level genetic structure. A total of 53 samples (2446 fish) were grouped into five major regional clusters: the southern Kurils, eastern Sakhalin, southwestern Sakhalin, the Amur River, and a northern cluster. The northern cluster consists of chum salmon populations from a vast geographical region, including Chukotka, Kamchatka, and the continental coast of the Sea of Okhotsk. However, the degree of its genetic differentiation is low, 1.9%. In contrast, the southern population cluster exhibits much higher variation; for example, differentiation between chum salmon groups within Sakhalin Island reaches 4.6%, and the differentiation between Iturup Island and Sakhalin Island chum salmon is 7.7%. This suggests that southern populations of Asian chum salmon have a more ancient evolutionary history than northern populations. In contrast to the available data, our study indicates a great deviation of southwestern Sakhalin populations from other Sakhalin chum salmon. The Russian Far East chum salmon are genetically diverse and show statistically significant differentiation even within small geographic localities. This can be used to assign samples of unknown origins to definite local populations.

Deep subsidence of the early catagenesis zones of organic matter in the sedimentary rocks of Northeastern Sakhalin shelf at high thermal regime of the basin

Heat flux measurements in the shelf zone of Northern Sakhalin reveal strong heating of the sedimentary complexes with a temperature gradient of the order of 36 ° C/km along the entire length of the Okhotsk Sea margin of the North Sakhalin basin [2]. However, despite the high thermal regime of the lithosphere in the region, the fact that initial stages of catagenesis gradations PC3‐MC1 ( R o = 0.50‐0.64%) are confined to great depths (3800‐5000 m) is a characteristic property of the deep distribution of the organic matter catagenesis of sedimentary rocks in the boreholes of Northern Sakhalin. It is likely that this fact is related to a high rate of sediment accumulation in the Neogene-Quaternary time. In order to check this supposition and estimate the rate of variations in the degree of transformation of organic matter (OM) in the deeper layers of the basin, we applied the modeling system of GALO basins and reconstructed numerically the history of subsidence and temperature evolution of the rocks of the sedimentary cover in the northeastern part of the Sakhalin shelf in Kaigano-Vasyukanskii area of Sakhalin-5 region (Fig. 1). In addition to the traditionally considered Cenozoic complex, our model of the sedimentary section of the basin includes Upper Cretaceous formations, whose thicknesses were estimated from the seismic data (table). The peculiarity of the shelf region considered here was in the fact that it was located on the one hand within the continental margin of the Okhotsk Sea Plate and on the other hand near the complex of the accretion prism of Eastern Sakhalin [1]. Although the close location of the accretion cline (and consequently the underthrust zone) predetermines the domination of compression stresses over the territory of the basin and consequently the nonisostatic response of the basin lithosphere to the load of water and sediments, there is sufficient evidence of active fracture tectonics in the northeastern shelf of Sakhalin with notable weakening of the lithosphere in the Late Cretaceous and Cenozoic (see below). Therefore, we considered two limiting versions of the basin development. In the first of them, we assumed that numerous fractures and displacements along the fractures significantly weakened the lithosphere strength in the region studied. Under these conditions, the local isostatic response of the lithosphere to the load of water and sediments existed during the entire history of the basin, which we consider started in the Late Cretaceous (and possibly excluded a few relatively short periods). In the second alternative version of the basin formation, we assumed that the local isostatic response of the basin lithosphere to the load of water and sediments existed only during the last 34 Ma starting from the time of the Kuril arc formation, which absorbed the main part of the regional compression stresses. The initial heat flux in the basin in the second version was assumed notably lower than in the first one. Of course, in both versions of the basin development, modern temperature distributions and OM maturity with depth (the values of the reflecting property of vitrinite, R o , %) calculated in the model were close to the values measured in the regions of the basin considered here and in the neighboring regions (Fig. 2). The main modeling results of the thermal history of the basin and variation in the OM maturity are shown in Fig. 3 for the first version of the basin development, which assumed an isostatic response of the lithosphere to the load of water and sediments and consequently high heat flux (approximately 160 mW/m 2 ) in the beginning of the Late Cretaceous. In such a model, intense subsidence of isotherms in the Pre-Cenozioc period of the basin development (Fig. 3) is determined

Revised Mesozoic–Cenozoic orogenic architecture and gold metallogeny in the northern Circum-Pacific

The orogenic collages of the northern Circum-Pacific between Japan and Alaska revealed an endowment of about 450 Moz Au in various deposit types and diverse Mesozoic–Cenozoic tectonic settings. The area consists of predominantly late Paleozoic to Cenozoic turbidite to island arc terranes as well as Precambrian cratonic terranes that can be grouped into the Kolyma–Alaska, Kamchatka–Aleutian, and Nipponide collages. The latter can be linked via the Mongol–Okhotsk suture with the late Paleozoic to early Mesozoic terranes in the Mongolides. The early Yanshanian magmatic arc terranes in the fossil Kolyma–Alaska collage host copper–gold porphyry deposits, which have only recently received much attention. Exploration has revealed a large and growing gold endowment of more than 30 Moz Au in some individual deposits, with smaller role of epithermal deposits. This mineralization, formed at 140–125 Ma, is partly coeval with the collisions of magmatic arcs with the passive margin sequences of the Siberian craton and related granitoid magmatism. About 200 Moz of gold is known in the Kolyma–Alaska collage in the Mesozoic orogenic gold deposits and related Quaternary placers. The Central Kolyma, Indigirka, South Verkhoyansk, and North Chukotka subprovinces of the collage revealed an endowment of more than 10 Moz Au each. A similar and coeval event in the Mongolides in relation to the collision between Siberia and North China is largely reflected in still poorly dated intrusion-related gold deposits clustered along the Mongol–Okhotsk suture. The overlapping Yanshanian magmatic arcs in Transbaikalia and northeast China and the Okhotsk–Chukotka magmatic arc in the Russian Far East stitch the Kolyma–Alaska collage with the Paleozoic Central Asian supercollage and adjacent cratons. While the Okhotsk–Chukotka arc reveals a relatively simple and broad oroclinal pattern, the Yanshanian arcs in Mongolia, and NE China form a tightly deformed giant Z-shaped feature that was bent in response to the southward movement of the Siberian craton and northward translation of the Nipponides and North China craton to close the Mongol–Okhotsk suture in late Jurassic to Cretaceous times. The Yanshanian arcs host mostly small to medium-sized 100–70 Ma Au–Ag deposits, with the largest endowment discovered in the Baley district in Transbaikalia and at Kupol in the northern part of the Okhotsk–Chukotka arc. Some intrusion-related gold deposits were formed synchronously with this arc magmatism, with the largest known examples in the Tintina belt in Alaska formed at 104 and 93–91 Ma. The Kamchatka–Aleutian collage is still evolving in front of the westward-subducting Pacific plate. It's late Cretaceous to Paleogene magmatic arc rocks form immature island arc terranes, extending from the Aleutian islands towards the Nipponides via Kamchatka peninsula, Kuril islands and eastern Sakhalin. However, in the Nipponides, the Sikhote–Alin portion of the magmatic arc overlaps the Mesozoic turbidite terranes. The oroclinal pattern of this more than 8000 km-long magmatic arc indicates its westward translation in agreement with the movement of the Pacific plate so that the arc is presently colliding with itself along the island of Sakhalin, a seismically active intraplate lineament and a boundary between the Nipponide and Kamchatka–Aleutian collages. This magmatic arc is usually interpreted to be of intra-oceanic origin, with subsequent docking to Asia from the south; however, presence of the Sea of Okhotsk cratonic terrane between Sakhalin and Kamchatka suggests that it may be rather considered as an external arc system that separated from the rest of Asia due to backarc spreading events, therefore, forming the most external arc system at the active margin with the Pacific plate. The subduction-related events in the collage produced numerous late Mesozoic to Cenozoic 1–3 Moz gold epithermal deposit in Kamchatka and Sikhote–Alin as well as Au–Cu porphyry deposits, with currently largest gold endowment in the pre-Tertiary Pebble Copper deposit in Alaska. The westward translation of the Kamchatka–Aleutian collage might have controlled the emplacement of this porphyry deposit, as well as up to 30 Moz into intrusion-related gold deposits at 70–65 Ma in the Kuskokwim belt, immediately north from the porphyry cluster.

A new species of the pandalid shrimp genus Pandalus (Crustacea: Decapoda: Caridea) from the Sea of Okhotsk off eastern Sakhalin, Russian Far East

A new species of the pandalid shrimp genus Pandalus (Crustacea: Decapoda: Caridea) from the Sea of Okhotsk off eastern Sakhalin, Russian Far East

Variability of microsatellite DNA and genetic differentiation of populations in the resident form of Dolly Varden Salvelinus malma krascheninnikovi from Sakhalin

Variability in 11 microsatellite loci is followed for nine populations of the resident southern form of Dolly Varden Salvelinus malma krascheninnikovi from Sakhalin. In all studied populations, the level of genetic differentiation is significant with global values of F st and R st 0.182 and 0.329, respectively. On the NJ tree, two clusters are separated significantly: the former is represented by the populations from southwestern Sakhalin (the Novoselka River basin), and the latter includes all populations from southern and eastern Sakhalin. Abrupt size variations (bottleneck events) are suggested for several studied populations, and 50% reductions of allelic richness and average heterozygosity are observed in two lacustrine populations of the Novoselka River basin in comparison to the riverine populations of this basin. The results suggest an occurrence of a comparatively recent gene flow between the populations of resident Dolly Varden from Sakhalin and absence of reproductive isolation between the anadromous and resident forms. The degradation of the majority of Dolly Varden populations can be expected in the near future, and conservation projects should be developed.

A new species of the pandalid shrimp genus Pandalus (Crustacea: Decapoda: Caridea) from the Sea of Okhotsk off eastern Sakhalin, Russian Far East

A new species of the pandalid shrimp genus Pandalus Leach, 1814, Pandalus ivanovi n. sp., is described on the basis of material from the Sea of Okhotsk off eastern Sakhalin, at depths of 150–200 m. It is morphologically closest to Pandalus hypsinotus Brandt, 1851, a commercially important species widely distributed in the northern North Pacific. Because of the strong similarities between the new species and P. hypsinotus, we have examined syntypes of the latter species in order to confirm the specific identity. The new species can be distinguished from P. hypsinotus by the more strongly upturned rostrum, the relatively low postrostral ridge on the carapace, fewer carpal articles of the left second pereopod and the small body size. The coloration in life is also different between the two. There is an indication of protandry in the new species, like other congeneric species.

Summer-autumn ichthyoplankton of the Sea of Okhotsk and the Sea of Japan and special traits of feeding of fish larvae and fry in 2003–2004

In summer-autumn of 2003–2004, the ichthyoplankton of the Sea of Okhotsk comprised 35 species. In this period the most widely distributed and numerous were larvae of the lord Hemilepidotus gilberti, the Pacific stout sand lance Ammodytes hexapterus, and the Sakhalin dab Limanda sakhalinensis. The maximum catches of fish larvae were attributed to coastal waters off eastern Sakhalin and to the shelf of the northern part of the Sea of Okhotsk. In November of 2003, the ichthyoplankton of the Sea of Japan was represented by fish larvae belonging mainly to the boreal ichthyocomplex. The catches consisted predominantly of larvae of the arabesque greenling Pleurogrammus azonus, the ronquil Bathymaster derjugini, and the rockfish Sebastes owstoni. Fish larvae and fry in the northwestern part of the Sea of Japan were caught principally within 43°–45° N and 137°–139° E above the depth 1500–2000 m. The food spectrum of fish larvae in the Sea of Okhotsk and the Sea of Japan comprised over 20 plankters of various size belonging to seven taxa. Irrespective of fish species, the food items common of all fish were copepods Pseudocalanus minutus and Oithona similis. The daily rations were calculated for mass species (Hemilepidotus gilberti, Ammodytes hexapterus, Hexagrammos stelleri, Pleurogrammus azonus, Bathymaster derjugini, and Sebastes owstoni). The larvae of all considered species in the Sea of Japan and in the Sea of Okhotsk fed predominantly in the light period of the day.