Southern Kuril Research Articles

Fish Species Composition of Bottom Gillnet Catches by Japanese Fishing Vessels Operated in Russian Zone of Kunashir Strait in 1998–2014

Overall, 85 fish species assigned to 56 genera, 27 families, and 13 orders were observed in the bottom net catches from the Kunashir Strait in 1998–2014. The highest number of species (18) represented the family Pleuronectidae, while the family Cottidae involved the lower number of species (14). Thus, 35 species were found in the Nemuro Strait (including the Kunashir Strait) for the first time. Considering the information in the literature, the total number of fish species in the strait separating the Southern Kuril Islands from the Hokkaido Island increased to 173.

Morphology and Specific Features of Formation of Thermal Lake Utinaya Banya (Iturup Island, Southern Kuril Islands)

Abstract —This paper describes a set of studies performed at a thermal manifestation (Lake Utinaya Banya) on the Iturup Island (Kuril Islands). These studies include bathymetric survey of the lake basin, geometric leveling across the lake, pitting, sampling of thermal waters from the lake and springs, hydrochemical research, and isotopic analysis of oxygen and hydrogen in the lake water. It is suggested by the shape of the lake basin (close to lenticular with a significant concentric depression), the underwater gas-hydrothermal vents, the bank along the perimeter of the lake basin, and the presence of several layers of clastic deposits at the top of the rampart that the lake was formed by a hydrothermal eruption. The lake temperature has remained constant over the years and ranges on average from 25 to 15 °C, depending on the season. The water of Lake Utinaya Banya is represented by acidic, sulfate calcium, and low-mineralized waters.

Partial Melting under Shallow-Crustal Conditions: A Study of the Pleistocene Caldera Eruption of Mendeleev Volcano, Southern Kuril Island Arc

Abstract The southern part of the Kuril Island Arc is one of the world’s most active modern volcanic zones, with widespread felsic caldera volcanism, but it has been less well studied compared with other arcs. The Mendeleev caldera-forming eruption (40 ka) on Kunashir Island, southern Kurils, is one of the most explosive Pleistocene eruptions to have occurred in this region. This study aimed to establish the origin and storage conditions of magma preceding the Pleistocene caldera eruption of Mendeleev volcano. Mineralogical and melt inclusion analyses reveal that the primary melts had felsic compositions and that the early stage of magmatic evolution involved amphibole breakdown into a two-pyroxene, plagioclase, and Fe–Ti oxide assemblage under pressure–temperature conditions of 107–314 MPa and 807–932°C. The caldera-forming products are represented by dacitic pumice composed of plagioclase + augite + hypersthene+ quartz + Fe–Ti oxides and melt with uniform low-K rhyolite composition. Pre-eruptive magma was stored in a reservoir at 77–195 MPa (3.0–7.6 km depth) and 830–890°C under H2O-saturated conditions. The mechanism of magmatic evolution implies the following two-step scenario: (1) generation of magma by the partial melting of an amphibole-bearing substrate accompanied by the formation of early Mg-rich clino- and orthopyroxene, plagioclase, Fe–Ti oxides, and peritectic rhyolitic melt; and (2) crystallization of late plagioclase and quartz directly from these partial melts. Local or regional extension during the Pleistocene, accompanied by increasing heat flow in the supra-subduction mantle, generated an active mafic intrusion into the upper crust. This process was accompanied by abundant subaerial eruptions of basaltic volcanoes and could have caused intense heating and partial melting of upper-crustal rocks. Our results indicate that the partial melting of amphibole-bearing substrates in island arcs may serve as a universal mechanism for the generation of silicic magmas during powerful caldera eruptions in young island arcs.

ADDITION TO THE MOSS FLORA OF THE SOUTHERN KURILE ISLANDS (RUSSIAN FAR EAST)

As a result of identification the moss collections from Shikotan, Kunashir, Iturup and Urup islands (Southern Kuril Islands, Russian Far East) collected by T.I. Koroteeva, V.E. Fedosov, A.V. Shkurko, N.S. Liksakova, and A.K. Ezhkin in 2015–2021, new species for the islands were revealed: 6 ones for Urup, 8 for Iturup, 10 for Kunashir, and 19 for Shikotan. For the first time, 4 species new for the Kuril Islands were discovered, including three new for the Sakhalin Region (Forsstroemia cryphaeoides, Haplocladium intermedium, Rhizogemma staphylina, Meteorium buchananii). Another 3 species found in the islands are new for the Southern Kuriles (Dicranum fragilfolium, Gollania turgens, Hygroamblystegium varium). Most of the discovered species are rare in both the Sakhalin Region and the Russian Far East. To date, the moss flora of the Southern Kurils numbers 468 species and is the richest bryoflora in Russia.

CHANGES IN GEODYNAMIC SITUATION MANIFESTED IN SOIL RADON AND TEMPERATURE VARIATIONS AND ABNORMAL NATURAL PHENOMENA IN THE ZONE OF KATAV-IVANOVSK EARTHQUAKE (05.09.2018), THE SOUTHERN URALS

The strongest earthquake in the Urals registered during the period of instrumental observations, with a magnitude of ML-5.4 occurred in the area of Katav-Ivanovsk city, Chelyabinsk region, on 05.09.2018. In October 2018, Institute of Geophysics, the Ural Branch RAS organized temperature and radon observations. The conducted studies have shown that the behavior patterns of the volume radon activity (VRA) established for the tectonic event preparation in the subduction zone (Southern Kuriles), are also true for the South Ural region. The natural phenomena caused by the earthquake 2018 preparation are analyzed. During the observation period from 28.11.2018 to 23.05.2019, there was an increase in temperature with a gradient of 0.02°C per month. The observed patterns of VRA abnormal behavior before aftershocks in the Katav-Ivanovsk area are typical for the compression zone in the radon monitoring area. It is noted that the assumed compression deformations were manifested in the hydrogeodynamic field at least 10 years before the event proper. The proximity of earthquake foci to the identified aseismic zone within the boundaries of the East European Platform, the Pre-Ural Regional Trough, and the Bashkir anticlinorium indicates the most likely places of seismic events. The arranged temperature and radon monitoring network in the epicentral zone by observing aftershocks has shown the possibility of tracking the earthquake preparation process.

The phylogenetic position of Maritrema afanassjewi Belopol'skaya, 1952 (Digenea, Plagiorchiida: Microphallidae), a parasite of the Ussuri brown bear, Ursus arctos lasiotus Gray, 1867 (Carnivora, Ursidae)

Adult digeneans of Maritrema afanassjewi Belopol'skaya, 1952 parasitize birds and mammals along the North Pacific coasts and were previously studied in terms of morphology. However, morphological features not supported by molecular characterization are considered an insufficient tool for the identification of evolutionary lineages of microphallid digeneans. Here we provide the first data on the phylogenetic position of this species inferred from sequences of the 28S rRNA gene and the ITS2 locus of the nuclear DNA, as well as additional morphometric data. The trematodes were isolated from the intestine of the Ussuri brown bear ( Ursus arctos lasiotus Gray, 1867) on Iturup Island (the southern Kuril Islands). This is the second record of M. afanassjewi in the brown bear. The phylogeny based on the 28S rRNA gene was poorly resolved for this parasite species. The analyses based on the ITS2 locus dataset showed that M. afanassjewi was a low-supported sister to Maritrema subdolum Jägerskiöld, 1909.

Pink salmon fishery in the Far-Eastern fishing basin in 2022: preliminary studies, forecast, interpretation of the fishing season results

Results of marine trawl surveys for accounting of pink salmon in 2021 and 2022 and the main results of the salmon fishery in 2022 are presented. The main stages of forecasting of the pink salmon fishery in the Far Eastern basin are described. Differentiation of mixed aggregations of pink salmon is discussed. In 2022, specialists of Kamchatka Branch used for the first time a new method based on variability of SNP loci, along with the traditional methods (morphological express-method and genetic method based on mtDNA analysis). This method provided additional dividing the mixed aggregations of autumn pink salmon in the Sakhalin-Kuril area to the herds from southern Kuril Islands and from eastern Sakhalin. The fishery forecasts for pink salmon were adjusted several times during the fishing season. These adjustments had no a significant effect for the catch increasing in the Okhotsk Sea basin, but allowed to land 10,500 t additionally in the Bering Sea.

On coho salmon <i>Oncorhynchus kisutch</i> from Iturup Island

Results of biological analysis are presented for 162 specimens of coho salmon caught at the coast and in the rivers of Iturup Island (southern Kuril Islands) during their spawning migration in August-October, 2021. Almost all females and males close to puberty in the current year spent one year in the sea and were aged 1.1+ (66.7 %) and 2.1+ (30.0 %). The fish that spent two years in the sea were single – 1 specimen aged 1.2+ and 3 specimens aged 2.2+ (2.5 %). Taking into account the age of puberty and the body weight (2.63 kg for females and 2.44 kg for males, on average) the spawners reproduction in short streams is assumed. The high value of the gonad-somatic index (up to 20–22 % for some females) is other evidence that all these fish cannot run to other spawning areas but at least a part of them should spawn in the water bodies of Iturup Island. Indeed, some coho salmon were captured directly in the rivers. Beside the spawning fish, two actively feeding coho females aged 0.0+ (0.55 kg) and 1.0+ (1.11 kg) were caught with fixed nets.

Scour ponds from unusually large tsunamis on a beach-ridge plain in eastern Hokkaido, Japan

Scour ponds from unusually large tsunamis cut across the crest of a beach ridge in Kiritappu marsh, eastern Hokkaido. No fewer than ten of these ponds were imaged by photogrammetry as elongate topographic depressions as large as 5 m by 30 m. Sediments in these ponds are underlain by unconformities that were detected with ground-penetrating radar and observed directly in cores and a slice sample. Sediment deposits in the ponds contain peat and volcanic ash layers, the ages of which suggest that the scouring occurred during tsunamis generated by spatially extensive thrust ruptures along the southern Kuril trench, most recently during the early seventeenth century and its predecessor during the thirteenth–fourteenth century. Some of the ponds appear to have been formed during one tsunami and refreshed during later successors. This evidence of recurrent erosion suggests that the shoreline may retreat as part of earthquake-related cycles of coastal uplift and subsidence.

The present-day stress field along the Northwest Pacific Wadati-Benioff zone constrained by focal mechanisms of moderate earthquakes

The present-day stress field in the northwest Pacific Wadati-Benioff Zone (WBZ) has been investigated on the basis of earthquake focal mechanism catalog covering the period from 2012 to 2021. Our catalog contains 201 focal mechanism solutions (Mw 4.0–5.9) compiled from the F-net network along three profiles (southern Kurile trench, central Japan trench and northern Izu-Bonin trench). According to the spatial variations in the stress regimes, we outlined 12 subvolumes for three profiles. Our results present that the maximum compressive stress is, slab-normal in trench-outer rise regions and nearly strike-normal and sub-horizontal in the depth range 0–70 km. At intermediate depths, a two-planar stress pattern is observed (70–200 km) in southern Kurile and central Japan trench WBZ, with the maximum compressive stress closely parallel to the slab in upper plane and slab-normal in lower plane, respectively. However, the southern Kurile trench WBZ exposes an extension stress regime in 200–300 km depth range. At depths below 300 km, northern Izu-Bonin trench WBZ shows a stress regime of pure compression. We infer the dominant forces may be the slab blending in the shallow trench-outer rise regions, slab pull and ridge push at shallow depths, and the slab resistance provided by the mantle to the penetration of the slab at deep depths. Whereas the two-planar stress pattern may be caused by the unbending of the slab, and the unusual stress state along the junction of the trench WBZ at intermediate depths may be influenced by lateral deformation due to increasing slab’s dip.

Some data on the fishery, distribution and size composition of saffron cod Eleginus gracilis Tilesius, 1810 near the Southern Kuril Islands

Data on harvesting, seasonal dynamics, structure of coastal and marine fishery, size and age composition of saffron cod catches near the Southern Kuril Islands are given. Summer–autumn distribution and size composition of saffron cod aggregations is considered based on the data of bottom trawl surveys. Distribution of saffron cod is shown almost everywhere near Kunashir Island, the Lesser Kuril Ridge and Pacific coast of Iturup Island. Harvesting is provided throughout the year, but mainly at December fishing for bottom and demersal fish species in the South Kuril Strait and May–June fishing with small fixed nets near Kunashir. Although catches of saffron cod have increased in recent years, the species is still under exploited commercially.

Russian settlement on the island of Urup (1795–1805) and its influence on Japan’s policy towards Ainu from southern Kurils

Based on comparative study of published Russian and Japanese sources, the article describes the history of the Russian settlement on the island of Urup in 1795–1805. First, it clarifies the goals of the foundation of the settlement and the reasons for its liquidation. Founded at the initiative of the Siberian merchant Grigorii Shelekhov, the Russian settlement played an important role both in Russo-Japanese relations and in the policy of the Japanese government towards the Ainu and their lands, especially in the southern Kuril Islands, at the turn of the 18th and 19th centuries. Russians founded the settlement in the view of future trade opportunities with Japan, since, a few years earlier, the Russian envoy Adam Laxman had received a permission to enter the port of Nagasaki to continue negotiations. In the beginning, Russians managed to start exchange of Japanese goods and supplies with the Ainu. After Japanese governmental expedition reached Iturup in 1798, however, information about relations between the Russians and the Ainu led to the transfer of the northeast Hokkaido, Kunashir, and Iturup under the direct control of the bakufu, as well as influenced the nature of Japanese policy towards the local population, the Ainu. The desire to expel the Russians from Urup and thereby stop their relations with the Ainu of the southern Kuril Islands led to the decision of the Japanese government to turn Iturup into a natural fortress and forbid the locals to leave the island, and the Russians and Ainu of the northern and middle Kuril Islands to come there. At the same time, the long stay of Russian settlers on Urup prevented the spread of Japanese influence north of Iturup.

Комплексные геолого-геофизические исследования по обоснованию внешней границы континентального шельфа России в Охотском и Восточно-Сибирском морях (2006–2009 гг.): обзор

The paper discusses the results of complex geological and geophysical studies of the deep structure of the seabed along the profiles “Magadan – Southern Kurils” (2-DV-M), “Shantar Islands – Northern Kurils” (1-OM) and “Cape Billings – Outer Continental Shelf Limits” (5-AR), carried out in 2006–2009 within the framework of the State program of expeditionary works on substantiation of national sovereignty over the continental shelf in the Sea of Okhotsk and East Siberian Sea. The main executors were the staff of the V.I. Il’ichev Pacific Oceanological Institute of FEB RAS and Federal State Unitary Scientific and Production Company (FSUSPC) Sevmorgeo. A special role was assigned to gas-geochemical studies with the purpose to establish regional background and anomalous gas fields to assess prospects for oil, gas and gas hydrates. As a result of complex geological and geophysical expeditions led by A.A. Merezhko (Sevmorgeo) in the Sea of Okhotsk, it was established that the enclave outside the 200-mile zone in the central part of the water area does not differ in geological structure from the adjacent parts and is a natural continuation of the framing geological structures of the basement. The evidence obtained was sufficient to successfully justify the application to the UN. On March 11, 2014, after careful consideration of the application and draft recommendations, the enclave of international waters in the Sea of Okhotsk was legally assigned to the Russian Federation. Studies in the East Siberian Sea have provided a huge amount of data on lithology, geochemistry and gas potential of bottom sediments in this area.

О сброшенных напряжениях в очагах умеренных и слабых землетрясений: особенности распределения во времени

An analysis has been performed of the change in stress drops over time during the period of foreshock activity of strong earthquakes for two seismically active regions with different geodynamic settings: the Northern Tien Shan and the Southern Kuril Islands. The catalogs of earthquake dynamic parameters, DP (source ones in English publications), in these regions, with a number of events, were used as initial data. The DP catalog for the Northern Tien Shan includes 183 records of source parameters of earthquakes with magnitudes of 2.6–6.0, and the catalog for the Southern Kurils – 264 records. The stress drop values throughout a general sampling were analyzed as well as that in foreshock periods of 500 days length before the strongest earthquakes. For each region 12 such meaningful events have been specified, the magnitudes were М > 5 for the Northern Tien Shan, and М ≥ 6.5 for the Southern Kurils. The median average values of stress drops during 500-day period have been determined. The temporal variations of stress drops have been compared with changes in the b-value parameter (angular coefficient of earthquake recurrence plot) in the same observation periods. The computation of b-value for the case of the Northern Tien Shan involved the catalog data of KNET seismological network (1994–2021, more than 10 000 events), and the catalog of International Seismological Center (ISC, 1964–2000) for the Southern Kurils. In both cases, b-values were determined in 500-day moving interval with one day step. The computation gave the result that the well-known effect of b-value growth before strong earthquakes manifested itself explicitly in the considered regions. It has been established that such increase in b-value is accompanied by a decrease in the averaged stress drop values. The obtained results showed that the monitoring of the stress drop values can be used to identify the non stationary stage of the seismic regime.

Картографирование растительности южной части острова Сахалин по данным дешифрирования снимков спутниковой системы Landsat

The purpose of the research is to determine the factors that have a significant impact on the distribution structure of plant communities over the territory and to draw up a vegetation map. The article pre-sents the analytical results of the vegetation cover diversity and geobotanical mapping of the territory based on the data of decoded satellite images. Materials and methods. The main sources of information for the study are materials of field geobotanical studies and satellite images of medium spatial resolution obtained from the Landsat-8 satellite, which provided an assessment of the current state of forest communities. Modern compilation and design of maps is characterized by the widespread use of GIS technologies and computer analysis methods. To decrypt and process the images, the ENVI, ArcGIS, and QGIS software complexes were used. The final processing and design of the cartographic material was carried out using the Adobe Illustrator program. Results. The southern part of the Sakhalin Island territory was chosen as the object of research, on which a large number of east-asian species, including tree and shrub forms, grow. In the Yuzhno-Sakhalinsk floristic region, the flora of the North-Japanese type prevails, and the presence of northern species characteristic of the dark coniferous taiga zone is noticeably reduced in its composition. Krillionsky district is distinguished by the presence of species common with the Southern Kuril Islands and the Hokkaido Island. The re-sults of studying the spatial distribution of forest landscapes served as a basis for identifying the most resistant to climate change plant communities, as well as those capable of rapid recovery after forest fires. Climatic conditions have been analyzed, which made it possible to identify trends in the long-term dynamics of plant communities in the territory. The analysis of long-term dynamics made it possible to identify the current state of forest communities, predict certain negative natural phenomena (fires, waterlogging, etc.). Conclusions. The dynamics of the state of forest plant communities is clearly determined by the data of satellite surveys. The map, compiled on the basis of the results of space images interpretation, reflects the spatial distribution and state of the vegetation cover of the territory, enables to make an inventory of plant associations, to establish the boundaries of geobotanical regions in their current state.

Проект «Скопа в России»: основные результаты работы в 2019–2023 годах

Проект «Скопа в России»: основные результаты работы в 2019–2023 годах

The topography of the 660-km discontinuity beneath the Kuril-Kamchatka: Implication for morphology and dynamics of the northwestern Pacific slab

The 660-km discontinuity (660) plays a potentially important role in deep slab dynamics and mantle convection. Increasing numbers of seismic observations suggest controversial morphologies of the Pacific slab beneath the Kuril-Kamchatka, highlighting the poorly understood interaction of the slab and mantle discontinuities. Here we collect near-source S-to-P converted waves from a large dataset with several dense seismic networks and systematically image the topography of the 660 around the Pacific slab beneath the Kuril-Kamchatka. We conduct detailed comparisons of the 660 depths and seismicity along some vertical cross sections. In comparison with the discontinuity depth in the IASP91 model, the 660 exhibits broad depressions up to 32–63 km with apparent downward deflections beneath the Kamchatka Peninsula and northern Kuril (region I), supporting slab penetration into the lower mantle; in contrast, the 660 depressions beneath southern Kuril (region II) are less than 21–28 km with a relatively flat configuration, implying a stagnating slab with possible hot entrained mantle materials and/or partial melts below it. We interpret these regional variations in the 660 topography as reflecting local low-temperature anomalies due to different slab morphologies associated with contrasting subduction modes. We suggest compound effects of pressure-driven mantle flow and trench retreat for inducing the inferred subduction mode change of the Pacific slab from region I to region II. Our results can provide more insight into subduction dynamics in the northwestern Pacific.

Modern status, formation and exploitation of walleye pollock stocks off the southern Kuril Islands

The aim of the study is analyze the state and clarify modern status of walleye pollock stocks in the southern Kuril Islands waters.Result: Strong year-classes are revealed, which determined pollock stock dynamics in the South Kuril region in the 2010s — e arly 2020s. It is shown, that the maximum pollock biomass since the early 1990s was observed in the early 2010s, and in the early 2020s decreased to the average level. The organization of fishing and the composition of pollock commercial catches off the southern Kuril Islands are differ at low and high levels of stocks.Novelty: New data on structure and pollock stocks assessment in the South Kuril region since 2011 based on the integrated surveys results are presented. Long-term data on the effectiveness of fishing and the structure of pollock commercial catches in the South Kuril zone are considered.Practical significance: The obtained estimates of the current state and structure of pollock stock will be used for short-term and long-term forecasts.Research methods: walleye pollock stocks assessment in the South Kuril region is based on the annual integrated research expeditions in accordance with the standard methods used in TINRO to monitor pollock stocks.

The Biological Features of Pacific Herring (Clupea pallasii) and Prospects for the Current Herring Fishery on the Shelf of the Southern Kuril Islands

The Biological Features of Pacific Herring (Clupea pallasii) and Prospects for the Current Herring Fishery on the Shelf of the Southern Kuril Islands

The Current Status of the Sakhalin–Hokkaido Herring (Clupea pallasii) Stocks off the Coasts of Sakhalin Island and the Southern Kuril Islands

The Current Status of the Sakhalin–Hokkaido Herring (Clupea pallasii) Stocks off the Coasts of Sakhalin Island and the Southern Kuril Islands