Sea of ​​Japan water salinity. Designation of the largest ports. What rivers flow

In size, it is inferior to the sea and, its area is up to 1,062 tons km2, and the deepest depression reaches up to 3745 m. It is generally accepted that the average depth is 1535 m. Large depths with a geographical position indicate that the sea belongs to the marginal oceanic seas.

There are medium and small islands in the sea. The most significant of them are Rishiri, Oshima, Sado, Momeron, Russian. Almost all islands are located along the mainland in the eastern part.

The coastline is slightly indented, the outlines of Sakhalin Island are especially simple. with the Japanese islands has a more indented coastline. The main major ports of the sea are Vostochny Port, Wonsan, Kholmsk, Vladivostok, Tsuruga, Chongjin.

Currents of the Sea of ​​Japan

Tides in the Sea of ​​Japan

In different areas of the sea, the tides are expressed differently, they are especially distinct in the summer and reach up to three meters in the Korea Strait. To the north, the tides decrease and do not exceed 1.5 m. This is due to the fact that the bottom has a funnel shape. The greatest fluctuation is observed in the northern and southern extreme areas of the sea in summer.

I offer you interesting video"Parallel world - the Sea of ​​Japan" from the series "Russian underwater expeditions".

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Physical and geographical characteristics and hydrometeorological conditions

The Sea of ​​Japan is located in the northwestern part of the Pacific Ocean between the mainland coast of Asia, the Japanese Islands and Sakhalin Island at the geographical coordinates 34°26"-51°41" N, 127°20"-142°15" E. According to its physical and geographical position, it belongs to the marginal oceanic seas and is fenced off from adjacent basins by shallow water barriers. In the north and northeast, the Sea of ​​Japan connects with the Sea of ​​Okhotsk straits Nevelskoy and Laperouse (Soya), in the east - with the Pacific Ocean by the Sangar (Tsugaru) Strait, in the south - with the East China Sea by the Korean (Tsushima) Strait. The shallowest of them, the Nevelskoy Strait, has a maximum depth of 10 m, and the deepest Sangar Strait is about 200 m. Subtropical waters coming through the Korea Strait from the East China Sea have the greatest influence on the hydrological regime of the basin. The width of this strait is 185 km, and the greatest depth of the threshold is 135 m. The second largest water exchange, the Sangar Strait, has a width of 19 km. The La Perouse Strait, the third largest in terms of water exchange, has a width of 44 km and a depth of up to 50 m. The surface area of ​​the sea surface is 1062 thousand km 2, and the total volume of sea water is 1631 thousand km 3.

The nature bottom topography The Sea of ​​Japan is divided into three parts: northern - north of 44° N, central - between 40° and 44° N. and southern - south of 40 ° N.L. The bottom surface of the northern bathymetric step, which is a wide trench, gradually rising to the north, merges at 49 ° 30 "N with the surface of the shallows of the Tatar Strait. The basin of the central part with maximum depths for the sea (up to 3700 m) has a flat bottom and is elongated from west to east, northeast. From the south, its boundary is defined by the Yamato Sea Rise. The southern part of the sea has the most complex bottom relief. The main geological feature here is the Yamato Sea Rise, formed by two ridges elongated in an east-northeast direction and located between between the Yamato Rise and the slope of Honshu Island lies the Honshu Basin with depths of about 3000 m. depths of 120-140 m.

A feature of the bottom morphology of the Sea of ​​Japan is a poorly developed shelf, which stretches along the coast in a strip from 15 to 70 km in most of the water area. The narrowest shelf strip with a width of 15 to 25 km is noted along south coast Primorye. The shelf is most developed in the bay Peter the Great, in the northern part of the Tatar Strait, the East Korean Bay and in the area of ​​the Korea Strait.

The total length of the coastline of the sea is 7531 km. It is slightly indented (with the exception of Peter the Great Bay), sometimes almost straight. A few islands lie mostly near Japanese islands and in the Gulf of Peter the Great.

The Sea of ​​Japan is located in two climatic zones: subtropical and temperate. Within these zones, two sectors with different climatic and hydrological conditions are distinguished: the severe cold northern sector (partially covered with ice in winter) and the soft, warm sector adjacent to Japan and the coast of Korea. The main factor that forms the climate of the sea is the monsoon circulation of the atmosphere.

The main baric formations that determine atmospheric circulation over the Sea of ​​Japan are the Aleutian Depression, the Pacific Subtropical High, and the Asian Atmospheric Action Center located above the mainland. Changes in their position during the year determine the monsoonal nature of the climate in the Far East. In distribution atmospheric pressure over the Sea of ​​Japan, determined by the main baric formations, the following features are found: a general decrease in pressure from west to east, an increase in pressure from north to south, an increase in the excess of winter pressure values ​​over summer pressure in the direction from northeast to southwest, as well as a pronounced seasonal variability. In the annual course of pressure, most of the sea is characterized by the existence of a maximum pressure in winter and a minimum in summer. In the northeastern part of the sea - near the northern half of about. Khonshu, oh Hokkaido and off the southern coast of Sakhalin have two pressure maxima: the first - in February and the second - in October, with a minimum in summer. The amplitudes of the annual pressure variation, as a rule, decrease from south to north. Along the mainland coast, the amplitude decreases from 15 mb in the south to 6 mb in the north, and along the coast of Japan, from 12 to 6 mb, respectively. The absolute amplitude of pressure fluctuations in Vladivostok is 65 mb, and on about. Hokkaido - 89 mb. To the southeast, in the central and southern parts of Japan, it increases to 100 mb. The main reason for the increase in the amplitudes of pressure fluctuations in the southeast direction is the passage of deep cyclones and typhoons.

The above features of the distribution of atmospheric pressure determine General characteristics wind regime over the Sea of ​​Japan. Near the mainland coast in the cold season, strong winds of the north-western direction prevail with speeds of 12-15 m/s. The frequency of these winds in the period from November to February is 60 - 70%. In January and February, the frequency of prevailing winds at some points on the coast reaches 75 - 90%. From north to south, wind speeds gradually decrease from 8 m/s to 2.5 m/s. Along the insular east coast, the winds of the cold season are not as pronounced in direction as they are off the mainland coast. Wind speeds are less here, but also decrease on average from north to south. Every year, in late summer and early autumn, tropical cyclones (typhoons) enter the Sea of ​​Japan, accompanied by hurricane-force winds. During the cold season, the frequency of storm winds caused by deep cyclones sharply increases. In the warm period of the year, south and southeast winds prevail over the sea. Their frequency is 40 - 60%, and the speeds, as in winter, on average decrease from north to south. In general, the wind speed in the warm season is much less than in winter. During the transitional seasons (spring and autumn), the direction and speed of the wind undergo significant changes.

For open areas of the northwestern regions of the sea, winds of northwestern and northern directions are predominant in winter. In the direction to the southwest, the winds turn from northwest to west, and in the areas adjacent to southern Sakhalin and Hokkaido, from northwest to north and even to northeast. In the warm season, such a regular picture of the general structure of the wind field cannot be established for the entire sea. However, it is found that in the northern regions of the sea, winds of eastern and northeastern directions prevail, and in the southern regions - southerly directions.

In the Sea of ​​Japan air temperature regularly changes both from north to south, and from west to east. In the northern, more severe climatic zone, the average annual temperature is 2°, and in the south, in the subtropics - +15°. In the seasonal course of air temperature, the minimum takes place in the winter months (January - February), and the maximum - in August. In the north, the average monthly temperature in January is about -19°, and the absolute minimum is -32°. In the south, the average monthly temperature in January is 5°, and the absolute minimum is -10°. In August, in the north, the average temperature is 15 °, and the absolute maximum is + 24 °; in the south, respectively, 25° and 39°. Temperature changes from west to east have a smaller amplitude. The west coast is colder throughout the year than the east coast, with temperature differences increasing from south to north. In winter they are larger than in summer, and average 2°, but at some latitudes they can reach 4 - 5°. The number of cold days (with an average temperature below 0°) decreases sharply from north to south.

On the whole, the sea has a negative (about 50 W/m) annual radiative heat balance on the surface, which is compensated by a constant heat inflow from the waters flowing through the Korea Strait. The water balance of the sea is determined mainly by its water exchange with adjacent basins through three straits: Korea (tributary), Sangar and La Perouse (drain). Compared to the value of water exchange through the straits, the contribution to the water balance of precipitation, evaporation, and continental runoff is negligibly small. The continental runoff, due to its insignificance, exerts its influence only in the coastal regions of the sea.

The main factors determining hydrological regime the Sea of ​​Japan, are the interaction of its surface waters with the atmosphere against the background of changing climatic conditions and water exchange through the straits with adjacent water basins. The first of these factors is decisive for the northern and northwestern parts of the sea. Here, under the action of the northwestern monsoon winds, which bring cold air masses from the continental regions in the winter season, surface waters cool significantly as a result of heat exchange with the atmosphere. At the same time, an ice cover is formed in the shallow areas of the mainland coast, Peter the Great Bay and the Tatar Strait, and convection processes develop in the adjacent open areas of the sea. Convection covers significant layers of water (down to depths of 400-600 m), and in some abnormally cold years it reaches the bottom layers of the deep-water basin, ventilating the cold, relatively homogeneous deep water mass, which makes up 80% of the total volume of sea water. Throughout the year, the northern and northwestern parts of the sea remain colder than the southern and southeastern parts.

Water exchange through the straits has a dominant effect on the hydrological regime of the southern and eastern half of the sea. The subtropical waters of the Kuroshio branches flowing through the Korea Strait throughout the year warm the southern regions of the sea and the waters adjacent to the coast of the Japanese Islands up to the La Perouse Strait, as a result of which the waters of the eastern part of the sea are always warmer than the western.

This section summarizes the main information about the spatial distribution and variability of sea water temperature and salinity, water masses, currents, tides and ice conditions in the Sea of ​​Japan, based on published works and analysis of the Atlas's graphic material. All values ​​of air and water temperature are given in degrees Celsius (o C), and salinity - in ppm (1 g/kg = 1‰).

On maps of the horizontal distribution of water temperature on the surface, the northern and southern parts of the sea are clearly separated by thermal front, whose position during all seasons of the year remains approximately constant. This front separates the warm and saline waters of the southern sector of the sea from the colder and fresher waters of the northern part of the sea. The horizontal temperature gradient on the surface across the front changes throughout the year from maximum values ​​of 16°/100 km in February to minimum values ​​of 8°/100 km in August. In November-December, north of the main front, a secondary front forms parallel to the Russian coast with a gradient of 4°/100 km. The temperature difference within the entire sea area in all seasons remains almost constant and equal to 13-15°. The warmest month is August, when temperatures in the north are 13-14°, and in the south, in the Korea Strait, they reach 27°. The lowest temperatures (0 ... -1.5 0) are typical for February, when ice forms in the northern shallow areas, and in the Korea Strait the temperature drops to 12-14 °. Quantities seasonal changes surface water temperatures generally increase from southeast to northwest from minimum values ​​(12-14 0) near the Korea Strait to maximum values ​​(18-21 0) in the central part of the sea and near the bay. Peter the Great. Relative to the average annual values, negative temperature anomalies occur from December to May (during the winter monsoon), and positive ones - from June to November (summer monsoon). The strongest cooling (negative anomalies up to -9°) occurs in February in the area of ​​40-42° N, 135-137° E, and the greatest heating (positive anomalies over 11°) is observed in August near Petra Bay Great.

With increasing depth, the range of spatial changes in temperature and its seasonal fluctuations at different horizons narrows significantly. Already at the horizon of 50 m, seasonal temperature fluctuations do not exceed 4-10 0 . The maximum amplitudes of temperature fluctuations at this depth are observed in the southwestern part of the sea. At a horizon of 200 meters, the average monthly values ​​of water temperature in all seasons increase from 0-1 0 in the north of the sea - up to 4-7 ° in the south. The position of the main front here does not change with respect to the surface front, but its meandering is manifested in the area between 131° and 138° E. In the central part of the basin to the north of the main front, the temperature at this horizon is 1-2 0 , and to the south it increases abruptly to 4-5°. At a depth of 500 m, the temperature within the entire sea varies slightly. It is 0.3-0.9 ° and practically does not experience seasonal variations. The frontal separation zone does not manifest itself at this depth, although in the area adjacent to the coast of Japan and Korea, there is a slight increase in temperature due to the transfer of heat to the deep layers by eddy formations that are actively formed in this area of ​​the sea.

Of the regional features of the horizontal temperature distribution, upwelling zones, eddy formations, and coastal fronts should be noted.

Upwelling near the southern coast of Primorye is intensively developed in late October - early November, however, individual cases of its rapid manifestation can be identified in September - early October. The diameter of the cold water spot in the upwelling zone is 300 km, and the temperature difference between its center and the surrounding waters can reach 90. The occurrence of upwelling is due not only to an increase in deep-water circulation, but also, mainly, to the monsoon change of winds, which is timed precisely for this period of time. Strong northwest winds blowing from the mainland create favorable conditions for the development of upwelling in this area. At the end of November, under the influence of cooling, the stratification in the upwelling zone is destroyed and the temperature distribution on the surface becomes more uniform.

IN coastal zone In the northwestern part of the Sea of ​​Japan (in the region of the Primorsky current), the frontal section is formed at the beginning of summer against the background of a general increase in the temperature of the surface layer. The main front runs parallel to the coastline. In addition to it, there are secondary fronts oriented perpendicular to the coast. In September-October, the main front is present only in the northern part of the sea, and to the south there are separate patches of cold water, limited by fronts. It is possible that the appearance of cold water cells near the coast is due to the rapid cooling of the surface layer in shallow water areas. These waters, after the final destruction of the thermocline, spread towards the open part of the sea in the form of continuous intrusions.

The most active eddy formations are formed on both sides of the front and, covering a significant water column, introduce anomalies into the field of the horizontal temperature distribution.

The absence of water exchange between the Sea of ​​Japan and neighboring basins at depths of more than 200 m, as well as active ventilation of deep layers due to autumn-winter convection in the northern and northwestern regions, lead to a clear division of the water column into two layers: active layer, characterized by seasonal variability, and deep, where both seasonal and spatial variability are almost non-existent. According to existing estimates, the boundary between these layers is located at depths of 300-500 m. Extreme depths (400-500 m) are confined to the southern part of the sea. This is due to the downward movement of water observed here in the center of the vast anticyclonic meander of the East Korea Current, as well as to variations in the position of the frontal zone at its northern and eastern boundaries. Up to a horizon of 400 m, seasonal temperature fluctuations are traced off the coast of Japan, which is a consequence of the subsidence of waters in anticyclonic gyres formed during the interaction of the Tsushima current with the continental slope. High penetration depths of seasonal temperature fluctuations (up to 400-500 m) are found in the Tatar Strait. This is mainly due to convective processes and significant seasonal variability of surface water parameters, as well as to intra-annual variability of the intensity and spatial position of the Tsushima Current water branch. Off the coast of southern Primorye, seasonal variations in water temperature appear only in the upper three hundred meter layer. Below this limit, seasonal temperature fluctuations are almost not traced. As can be seen from the vertical sections of the temperature field, the characteristics of the active layer undergo significant changes not only in the seasonal course, but also from region to region. The waters of the deep layer, which occupies about 80% of the volume of the sea, are weakly stratified and have a temperature of 0.2 to 0.7°.

The thermal structure of the waters of the active layer consists of the following elements (layers): quasi-homogeneous layer(VKS), seasonal jump layer temperature and main thermocline. The characteristics of these layers in different seasons in the sea have regional differences. Off the coast of Primorsky Krai in the summer, the lower boundary of the UQL is at a depth of 5-10 m, and in southern regions in the sea, it deepens to 20–25 m. In February, the lower boundary of the UML in the southern sector is at depths of 50–150 m. The seasonal thermocline intensifies from spring to summer. In August, the vertical gradient in it reaches a maximum of 0.36°/m. In October, the seasonal thermocline collapses and merges with the main thermocline, which is located throughout the year at depths of 90-130 m. In the central regions of the sea, the noted patterns persist against the background of a general decrease in contrasts. In the northern and northwestern parts of the sea, the main thermocline is weakened, and sometimes completely absent. The seasonal thermocline begins to form here with the beginning of the spring warming of the waters and exists until the winter period, when it is completely destroyed by convection within the entire water column of the active layer.

Horizontal distribution of salinity

Large-scale features of salinity distribution on the surface are determined by the water exchange of the sea with neighboring sea basins, the balance of precipitation and evaporation, ice formation and ice melting, as well as continental runoff in coastal areas.

In the winter season, on most of the sea surface, the salinity of the waters exceeds 34, which is mainly due to the inflow of high-salinity waters (34.6) from the East China Sea. Less saline waters are concentrated in the coastal regions of the Asian continent and islands, where their salinity decreases to 33.5-33.8. In the coastal areas of the southern half of the sea, the salinity minimum on the surface is observed in the second half of summer and early autumn, which is associated with heavy rainfall in the second half of summer and desalination of water brought from the East Kamchatka Sea. In the northern part of the sea, in addition to the summer-autumn decrease, a second salinity minimum is formed in spring during the period of ice melting in the Tatar Strait and Peter the Great Bay. The highest salinity values ​​in the southern half of the sea fall in the spring-summer season, when the inflow of Pacific waters, saline at this time, from the East China Sea intensifies. Characterized by a gradual delay in salinity maxima from south to north. If in the Korea Strait the maximum occurs in March-April, then off the northern coast of Honshu Island it is observed in June, and near the La Perouse Strait - in August. Along the mainland coast, the maximum salinity occurs in August. The most saline waters are located near the Korea Strait. In spring, these features are mostly preserved, but the area of ​​low salinity values ​​in coastal areas increases due to the melting of ice and an increase in continental runoff, as well as the amount of precipitation. Further, by summer, following the entry into the sea through the Korea Strait of freshened surface waters of the East China Sea due to the abundance of precipitation, the general background of salinity in the sea water area decreases to values ​​less than 34. In August, the range of salinity variability within the entire sea is 32.9-33.9. At this time, in the north of the Tatar Strait, salinity decreases to 31.5, and in some parts of the coastal zone - to 25-30. In the autumn, with amplification northern winds there is a surge and mixing of the waters of the upper layer and a slight increase in salinity is observed. The minimum seasonal changes in salinity on the surface (0.5-1.0) are observed in the central part of the sea, and the maximum (2-15) - in the coastal areas of the northern, northwestern parts and in the Korea Strait. At greater depths, along with a general increase in salinity values, there is a sharp decrease in the range of its variability both in space and in time. According to long-term average data, already at a depth of 50 m, seasonal changes in salinity in the central part of the sea do not exceed 0.2-0.4, and in the north and south of the water area - 1-3. At the 100 m horizon, horizontal changes in salinity fit into the range of 0.5, and at the 200 m horizon (Fig. 3.10) in all seasons of the year they do not exceed 0.1, i.e. values ​​characteristic of deep waters. Somewhat higher values ​​are observed only in the southwestern part of the sea. It should be noted that the horizontal salinity distributions at depths greater than 150–250 m are very similar: the minimum salinities are confined to the northern and northwestern parts of the sea, and the maximum salinities are confined to the southern and southeastern parts. At the same time, the haline front, which is weakly expressed at these depths, completely repeats the outlines of the thermal one.

Vertical distribution of salinity

The vertical structure of the salinity field in different parts of the Sea of ​​Japan is characterized by significant diversity. In the northwestern part of the sea, a monotonous increase in salinity with depth is observed in all seasons of the year, with the exception of winter, when it is practically constant throughout the entire water column. In the southern and southeastern parts of the sea, during the warm period of the year, an intermediate layer of increased salinity is clearly distinguished below the freshened surface waters, formed by highly saline waters (34.3-34.5) entering through the Korea Strait. Its core is located at depths of 60-100 m in the north and somewhat deeper - in the south of the sea. To the north, the salinity in the core of this layer decreases and reaches 34.1 on the periphery. In the winter season, this layer is not expressed. At this time of the year, vertical changes in salinity in most of the water area do not exceed 0.6-0.7. In a limited area located to the east of the Korean Peninsula at depths of 100-400 m, an intermediate layer of low salinity is distinguished, which is formed in the winter season due to the subsidence of surface waters in the frontal section zone. The salinity in the core of this layer is 34.00-34.06. Seasonal changes in the vertical structure of the salinity field are clearly visible only in the upper 100–250 m layer. The maximum depth of penetration of seasonal salinity fluctuations (200-250 m) is noted in the zone of distribution of the waters of the Tsushima current. This is due to the peculiarities of the intra-annual variation of salinity in the subsurface Pacific waters entering the sea through the Korea Strait. At the top of the Tatar Strait, off the coast of Primorye, Korea, as well as in the area to the south and southwest of the hall. Peter the Great, seasonal salinity variations appear only in the upper 100-150-meter layer. Here, the influence of the waters of the Tsushima Current is weakened, and intra-annual changes in the salinity of the surface water layer, associated with the processes of ice formation and river runoff, are limited to the waters of bays and bays. This area with minimum values ​​of the depth of manifestation of seasonal salinity fluctuations is interspersed with zones with higher values, the origin of which is associated with the penetration of branches of high-salinity waters of the Tsushima Current to the northwestern shores of the sea. A general idea of ​​the vertical structure of the salinity field is given by the spatial sections of the distribution of this characteristic and the tabular values ​​given in the atlas.

water masses

In accordance with the considered features of the spatiotemporal variability of temperature and salinity, the water column of the Sea of ​​Japan is composed of various water masses, the classification of which is carried out mainly according to the extreme elements of the vertical distribution of salinity.

By vertical the water masses of the open part of the Sea of ​​Japan are divided into surface, intermediate and deep. superficial the water mass (its varieties: PSA - subarctic, PVF - front zones, PST - subtropical) is located within the upper mixed layer and is bounded from below by the seasonal thermocline. IN southern warmth In the cold northern sector, it is formed as a result of mixing of waters coming from the East China Sea and the coastal waters of the Japanese Islands, and in the cold northern sector (PSA) - by mixing of coastal waters freshened by continental runoff with waters of open areas of the adjacent part of the sea. As shown above, during the year the temperature and salinity of surface waters vary in a wide range, and their thickness varies from 0 to 120 m.

In the below intermediate During the warm period of the year, a water mass of increased salinity is released in the water layer in most of the sea (its varieties: PPST - subtropical, PPST - transformed), the core of which is located at a depth of 60-100 m, and the lower boundary at a depth of 120-200 meters. Salinity in its core is 34.1-34.8. In a local area to the east of the coast of the Korean Peninsula, at depths of 200-400 m, a water mass of low (34.0-34.06) salinity is sometimes released.

Deep the water mass, usually called the water of the Sea of ​​Japan itself, covers the entire lower layer (deeper than 400 m) and is characterized by uniform temperature (0.2-0.7 °) and salinity (34.07-34.10). The high content of dissolved oxygen in it indicates an active renewal of the deep layers by surface waters.

IN coastal areas in the northwestern part of the sea, due to significant freshening by continental runoff, aggravation of tidal phenomena, wind upwellings and winter convection, a specific coastal water structure is formed, represented by a vertical combination of surface waters (SS) that are less saline than the waters of adjacent areas of the open sea, and have more significant fluctuations in temperature, as well as subsurface water (SSW) of higher salinity and low temperature, formed during winter convection. In some areas (Tatar Strait, Peter the Great Bay), during intense ice formation in winter, highly saline (up to 34.7 and very cold (up to -1.9 0) water mass (LS) is formed. Spreading near the bottom, it can reach the edge of the shelf and drain along the continental slope, participating in the ventilation of the deep layers.

In the part of the shelf, where freshening by continental runoff is small, the water stratification is weakened or even destroyed by tidal mixing. As a result, a weakly stratified shelf structure is formed, consisting of a relatively cold desalinated surface shelf water mass (SH) and a relatively warm and desalinated deep water shelf modification (DSW). With certain directions of the prevailing winds, this structure is distorted by the upwelling phenomenon. In winter, it is destroyed by a more powerful mechanism - convection. The waters formed in the zones of tidal mixing are drawn into the circulation existing in the northwestern part of the sea and propagate beyond the area of ​​their formation, usually considered as the “waters of the Primorsky current.”

Note: In February, the surface and deep water masses of the subarctic structure do not differ in their thermohaline characteristics.

Water circulation and currents

The main elements of the water circulation scheme given in the atlas are the warm currents of the southern and eastern and cold currents of the northwestern sectors of the sea. Warm currents are initiated by the influx of subtropical waters entering through the Korea Strait and are represented by two streams: the Tsushima Current, consisting of two branches - calm-seaward and more turbulent, moving under the very shore of the island of Honshu, and the East Korean Current, propagating in a single stream along the coast of the Korean Peninsula. At a latitude of 38-39 ° N The East Korean current divides into two branches, one of which, going around the Yamato Rise from the north, follows the direction of the Sangar Strait, the other, deviating to the southeast, closes the anticyclonic circulation near the southern coast of Korea with part of the water, and the other merges with the seaward branch Tsushima current. The union of all branches of the Tsushima and East Korean currents into a single flow occurs at the Sangar Strait, through which the main part (70%) of the incoming warm subtropical waters is carried out. The rest of these waters move further north towards the Tatar Strait. Upon reaching the La Perouse Strait, the bulk of this flow is carried out of the sea, and only an insignificant part of it, spreading within the Tatar Strait, gives rise to a cold current that spreads into southbound along the mainland coast of Primorye. Divergence zone at 45-46°N this current is divided into two parts: the northern - the Limannoye (Shrenk) current and the southern - the Primorsky current, which is divided into two branches south of Peter the Great Bay, one of which gives rise to the cold North Korean current, and the other turns south and, in contact with northern flow of the East Korea Current, forms a large-scale cyclonic gyre centered at 42°N, 138°E. over the Sea of ​​Japan basin. The cold North Korean Current reaches 37° N, and then merges with the powerful flow of the warm East Korean Current, forming, together with the southern branch of the Primorsky Current, a frontal separation zone. The least pronounced element general scheme circulation is the West Sakhalin Current, following in a southerly direction from latitude 48 ° N.L. along the south coast of Sakhalin and transferring part of the water flow of the Tsushima Current, which separated from it in the waters of the Tatar Strait.

During the year, the noted features of water circulation are practically preserved, but the power of the main currents changes. In winter, due to a decrease in the inflow of water, the speed of both branches of the Tsushima current does not exceed 25 cm/s, and the coastal branch has a greater intensity. Overall Width currents of about 200 km remain in summer, but the velocities increase to 45 cm/s. The East Korean Current also intensifies in summer, when its velocities reach 20 cm/s and its width is 100 km, and attenuates in winter to 15 cm/s and decreases in width to 50 km. The velocities of cold currents throughout the year do not exceed 10 cm/s, and their width is limited to 50-70 km (with a maximum in summer). In the transitional seasons (spring, autumn), the characteristics of the currents have average values ​​between summer and winter. The current velocities in layer 0-25 are almost constant, and with a further increase in depth, they decrease to half the surface value at a depth of 100 meters. The atlas contains schemes of water circulation on the surface of the Sea of ​​Japan in different seasons, obtained by calculation methods.

Tidal phenomena

Tidal motions in the Sea of ​​Japan are predominantly formed by the semidiurnal tidal wave M, which is almost purely standing, with two amphidromic systems located near the boundaries of the Korea and Tatar Straits. Synchronous fluctuations in the tidal profile of the sea level and tidal currents in the Tatar and Korea straits are carried out according to the law of a two-nodal seiche, the antinode of which covers the entire central deep-water part of the sea, and the nodal lines are located near the boundaries of these straits.

In turn, the relationship of the sea with adjacent basins through three main straits contributes to the formation of an induced tide in it, the influence of which, based on morphological features (the shallowness of the straits compared to the depth of the sea), affects the straits and areas immediately adjacent to them. Semidiurnal, diurnal and mixed tides are observed in the sea. The greatest level fluctuations are observed in the extreme southern and northern regions of the sea. At the southern entrance to the Korea Strait, the tide reaches 3 m. As you move north, it quickly decreases and does not exceed 1.5 m near Pusan. In the middle part of the sea, the tides are small. Along eastern shores Korea and Russian Primorye before entering the Tatar Strait, they are no more than 0.5 m. In the Tatar Strait, the magnitude of the tides is 2.3-2.8 m. The increase in the magnitude of the tides in the northern part of the Tatar Strait is due to its funnel-shaped shape.

In the open areas of the sea, semidiurnal tidal currents with velocities of 10-25 cm/s are mainly manifested. The tidal currents in the straits are more complex, where they also have very significant velocities. Thus, in the Sangar Strait, tidal currents reach 100–200 cm/s, in the La Perouse Strait, 50–100 cm/s, and in the Korean Strait, 40–60 cm/s.

Ice conditions

According to ice conditions, the Sea of ​​Japan can be divided into three areas: the Tatar Strait, the area along the coast of Primorye from Cape Povorotny to Cape Belkin, and Peter the Great Bay. In winter, ice is constantly observed only in the Tatar Strait and Peter the Great Bay, in the rest of the water area, with the exception of closed bays and bays in the northwestern part of the sea, it is not always formed. The coldest region is the Tatar Strait, where more than 90% of all ice observed in the sea is formed and localized in the winter season. According to long-term data, the duration of the period with ice in Peter the Great Bay is 120 days, and in the Tatar Strait - from 40-80 days in the southern part of the strait, to 140-170 days in its northern part.

The first appearance of ice occurs at the tops of bays and gulfs, closed from the wind, waves and having a desalinated surface layer. In moderate winters, in Peter the Great Bay, the first ice forms in the second decade of November, and in the Tatar Strait, in the tops of Sovetskaya Gavan, Chekhachev and Nevelskoy Straits, primary ice forms are observed already in early November. Early ice formation in Peter the Great Bay (Amur Bay) occurs in early November, in the Tatar Strait - in the second half of October. Later - at the end of November. In early December, the development of ice cover along the coast of Sakhalin Island is faster than near the mainland coast. Accordingly, in the eastern part of the Tatar Strait at this time there is more ice than in the western part. By the end of December, the amount of ice in the eastern and western parts equalizes, and after reaching the parallel of Cape Surkum, the direction of the edge changes: its displacement along the Sakhalin coast slows down, and along the mainland it becomes more active.

In the Sea of ​​Japan, the ice cover reaches its maximum development in mid-February. On average, 52% of the area of ​​the Tatar Strait and 56% of the Peter the Great Bay are covered with ice.

The melting of ice begins in the first half of March. In mid-March, the open waters of Peter the Great Bay and the entire seaside coast to Cape Zolotoy are cleared of ice. The boundary of the ice cover in the Tatar Strait recedes to the northwest, and in the eastern part of the strait, ice is clearing at this time. Early clearing of the sea from ice occurs in the second decade of April, later - in late May - early June.

Hydrological conditions of the hall. Peter the Great and coastal

zones of Primorsky Krai

Peter the Great Bay is the largest in the Sea of ​​Japan. It is located in the northwestern part of the sea between the parallels 42 0 17 "and 43 ° 20" N. sh. and meridians 130°41" and 133°02" E. e. The waters of Peter the Great Bay are limited from the sea side by a line connecting the mouth of the Tumannaya River (Tyumen-Ula) with Cape Povorotny. Along this line, the width of the bay reaches almost 200 km.

The Muraviev-Amursky peninsula and a group of islands located to the south-west of it, Peter the Great Bay is divided into two large bays: Amursky and Ussuriysky. Amur Bay represents the northwestern part of Peter the Great Bay. From the west, it is bounded by the coast of the mainland, and from the east - by the mountainous Muravyov-Amursky peninsula and the Russky, Popov, Reinike, and Rikord islands. The southern boundary of the Amur Bay is the line connecting Cape Bruce with the islands of Tsivolko and Zheltukhin. The bay extends in a northwesterly direction for about 70 km, and its width, averaging 15 km, varies from 13 to 18 km. Ussuri Bay occupies the northeastern part of Peter the Great Bay. From the northwest, it is bounded by the Muravyov-Amursky Peninsula, Russky Island, and the islands lying to the southwest of the latter. The southern boundary of the bay is considered to be a line connecting the southern ends of the Zheltukhin and Askold islands.

The area of ​​Peter the Great Bay is about 9 thousand km2, and the total length of the coastline, including the islands, is about 1500 km. On the vast water area of ​​the bay there are many different areas islands, concentrated mainly in the western part of the bay in the form of two groups. The northern group is located southwest of the Muravyov-Amursky Peninsula and is separated from it by the Bosphorus-Vostochny Strait. This group consists of four large and many small islands. Russky Island is the largest in this group. The southern group - the Rimsky-Korsakov Islands - includes eight islands and many islets and rocks. The most significant in it is the island of Big Pelis. In the eastern part of the bay there are two more big islands: Putyatina, located in the middle of Strelok Bay, and Askold, lying to the south-west of Putyatina Island.

most significant strait is the Bosphorus-East, separating the Russky Island from the Muravyov-Amur Peninsula. The straits between the Rimsky-Korsakov Islands are deep and wide; between the islands adjacent directly to the Muravyov-Amursky peninsula, the straits are narrower.

The coastline of Peter the Great Bay is very winding and forms many secondary bays and coves. The most significant of them are the bays of Posyet, Amursky, Ussuriysky, Strelok, Vostok and Nakhodka (America). Slavyansky Bay, Tabunnaya, Narva and Perevoznaya bays jut into the western shore of the southern part of the Amur Bay. The coastline of the northeastern part of the Amur and northwestern parts of the Ussuri Bay is relatively slightly indented. On the eastern shore of the Ussuri Bay, the bays of Sukhodol, Andreeva, Telyakovsky, Vampausu and Podyapolsky stand out. Capes protruding far into the sea form rocky, mostly steep coasts, bordered by stones. The largest of peninsulas are: Gamow, Bruce and Muravyov-Amursky.

Bottom relief Peter the Great Bay is characterized by developed shallow water and a steep continental slope cut by underwater canyons. The continental slope runs 18 and 26 miles south of the Askold and Rikord Islands almost parallel to the line connecting the mouth of the Tumannaya River and Cape Povorotny. The bottom in Peter the Great Bay is quite flat and gradually rises from south to north. In the eastern part of the bay, the depths reach 100 m or more, and in the western part they do not exceed 100 m. Seaward from the entrance to the bay, the depths increase sharply. On the continental slope, in a strip 3 to 10 miles wide, the depths vary from 200 to 2000 m. The secondary bays - Amur, Ussuri, Nakhodka - are shallow. In the Amur Bay, the bottom topography is quite even. Extensive shallows stretch from the shores of the bay's summit. From the northwestern coast of Russky Island to the opposite shore of the bay, an underwater rapid stretches with depths of 13-15 m. At the entrance to the Ussuri Bay, the depths are 60-70 m, then they decrease to 35 m in the middle part of the bay and to 2-10 m at the top . In the Nakhodka Bay, the depths at the entrance reach 23-42 m, in the middle part 20-70 m, and the top of the bay is occupied by shallow water with depths of less than 10 m.

Meteorological regime Peter the Great Bay, determine the monsoon circulation of the atmosphere, geographical position area, the impact of the cold Primorsky and warm Tsushima (in the south) currents. From October-November to March, due to the action of the formed baric centers of the atmosphere (the Asian maximum of atmospheric pressure and the Aleutian minimum), cold continental air is transferred from the mainland to the sea (winter monsoon) . As a result, frosty, slightly cloudy weather with a small amount of precipitation and a predominance of northerly and northwesterly winds sets in Peter the Great Bay. In spring, the wind regime is unstable, the air temperature is relatively low and long periods of dry weather are possible. The summer monsoon operates from May-June to August-September. In this case, sea air is transported to the mainland and observed warm weather with relatively high rainfall and fog. Autumn in Peter the Great Bay is best time years - usually warm, dry, with a predominance of clear, sunny weather. Warm weather lasts in some years until the end of November. The generally stable monsoonal weather pattern is often disrupted by intense cyclonic activity. The passage of cyclones is accompanied by an increase in cloudiness to continuous, rainfall, deterioration in visibility and significant storm activity. The average annual rainfall in the Vladivostok region reaches 830 mm. Atmospheric precipitation is minimal in January and February (10-13 mm). The summer period accounts for 85% of the annual precipitation and in August an average of 145 mm falls. In some years, precipitation, comparable in amount to monthly norms, can be bursty, short-term in nature and lead to natural disasters.

In the annual course of long-term average monthly values atmospheric pressure the minimum (1007-1009 mb) is observed in June-July, and the maximum (1020-1023 mb) in December-January. In the Amursky and Ussuriysky bays, the range of pressure fluctuations from maximum to minimum values ​​gradually increases with distance from coastal areas to more continental ones. Short-term changes in pressure during the daily course reach 30-35 mb and are accompanied by sharp fluctuations in wind speed and direction. The actually recorded maximum pressure values ​​in the Vladivostok region are 1050-1055 mb.

Average annual t air temperature is approximately 6 °. The coldest month of the year is January, when the average monthly air temperature in the northern part of the Amur and Ussuri bays is -16°…-17°. At the top of the Amur and Ussuri bays, the air temperature can drop to -37°. The warmest month of the year is August, when the average monthly temperature rises to +21°C.

During the winter monsoons, from October-November to March, winds northern and northwestern directions. In the spring, when the winter monsoon changes to the summer monsoon, the winds are not very stable. In summer, southeasterly winds prevail in the bay. Calm is more often observed in summer. The average annual wind speed varies from 1 m/s (at the top of the Amur Bay) to 8 m/s (Askold Island). On some days the wind speed can reach 40 m/s. In summer, the wind speed is less. In the peaks of the Amur and Ussuri bays, the average monthly wind speed is 1 m/s, in bays and gulfs - 3-5 m/s. Storms are mainly associated with cyclonic activity and are observed mainly in the cold season. The largest number of days with a storm wind is observed in December-January and is 9-16 per month. In the peaks of the Amur and Ussuri bays, storm winds are not observed annually.

They come to Peter the Great Bay typhoons, originating in tropical latitudes, in the region of the Philippine Islands. Approximately 16% of all tropical cyclones originating there predominantly in August-September come to the Sea of ​​Japan and Primorsky Krai. Their paths of movement are very diverse, but none repeats the trajectory of the other exactly. If the typhoon does not enter Peter the Great Bay and is still observed only in the southern part of the Sea of ​​Japan, it still affects the weather in this area: heavy rains and the wind intensifies to a storm.

Hydrological characteristic

Horizontal temperature distribution

Surface water temperatures experience significant seasonal variability, mainly due to the interaction of the surface layer with the atmosphere. In spring, the water temperature in the surface layer in the water area of ​​the bay varies within 4-14°. At the tops of the Amur and Ussuri bays, it reaches 13-14° and 12°, respectively. In general, the Amur Bay is characterized by higher temperatures than the Ussuri Bay. In summer, the waters of the bay warm up well. At this time, it reaches 24-26° in the tops of the Amur and Ussuri Bays, 18° in the America Bay, and 17° in the open part of the bay. In autumn, the temperature drops to 10-14° in the secondary bays and to 8-9° in the open part. In winter, the entire mass of water cools, its temperature fluctuates from 0 to -1.9 °. Negative temperatures occur throughout the shallow waters, as well as in secondary bays. The position of the 0° isotherm approximately coincides with the 50-meter isobath. At this time, the waters of the open part of the bay are warmer than the coastal ones and are characterized by positive temperature values. With increasing depth, the range of temperature change decreases and already at a depth of 50 m does not exceed 3 °, and at depths of more than 70 meters, seasonal changes almost do not appear.

Vertical temperature distribution

In the warm period of the year (April-November) there is a monotonous decrease in temperature with depth. At this time, a layer of seasonal thermocline is formed on the subsurface horizons - everywhere, except for shallow water, where the entire water column warms up and mixes well. In autumn, from the beginning of the winter monsoon and cooling, cold deep waters rise in shallow water and a second layer of temperature jump forms at a depth of 40 m. In December, both layers of the temperature jump are destroyed under the influence of convection, and the temperature remains constant throughout the entire winter period (from December to March) within the entire water column of the bay.

Salinity distribution

The orographic conditions of the bay and the influence of continental runoff create a peculiar regime of salinity distribution and variability. The water in some coastal areas of the bay desalinates to brackish, and in open areas it is close to the salinity of the adjacent part of the sea. The annual course of salinity is characterized by a minimum in summer and a maximum in winter. In spring, on the surface, the minimum salinity values ​​are confined to the top of the Amur Bay, where they are 28. At the top of the Ussuri Bay, salinity is 32.5, while in the rest of the water area it rises to -33-34. In summer, the surface layer is exposed to the greatest freshening. At the head of the Amur Bay, salinity is 20%, and in general in coastal waters and secondary bays it does not exceed 32.5 and increases in open areas to 33.5. In autumn, the horizontal distribution of salinity is similar to that in spring. In winter, salinity is close to 34 throughout the entire water area of ​​the bay. At depths of more than 50 meters, salinity varies within the water area of ​​the bay in the range of 33.5-34.0.

With increasing depth, salinity, as a rule, increases (spring-autumn) or remains constant (winter). In the bottom layer of the bay, due to the process of salinization during the formation of ice in the winter months, high-density waters are formed with a temperature of less than -1.5°C and a salinity of 34.2-34.7. In extremely ice years, high-density waters, spreading near the bottom, reach the edge of the shelf, roll down the slope and ventilate the deep layers of the sea.

water masses

In the winter season, in the Peter the Great Bay, the characteristics of water within the entire thickness correspond to the deep water mass of the Sea of ​​Japan (temperature is less than 1 °, salinity is about 34). In the near-bottom 20-meter layer during this period of time, a water mass of increased density with low (up to -1.9 °) temperature and high (up to 34.8º) salinity is released, which disappears already in mid-March, mixing with the surrounding waters.

In the summer season, due to an increase in heat inflow and continental runoff, the water column is stratified. In coastal areas, especially in areas where fresh water flows from river mouths, there is an estuary water mass with low (average 25) salinity, high (average 20°) temperature in the summer season, and depth of distribution up to 5-7 meters. The water masses of the open areas of the bay are divided by a seasonal thermocline into: surface coastal, which extends to the limit from the surface to a depth of 40 m and has indices in summer: temperature - 17-22 °, salinity - 30-33; subsurface - up to a depth of 70 m with a temperature of 2-16 ° and salinity of 33.5-34.0; and deep shelf - below the horizon of 70 m to the bottom with a temperature of - 1-2 ° and a salinity of about 34.

currents

The water circulation in the Peter the Great Bay is formed under the influence of the constant currents of the Sea of ​​Japan, tidal, wind and runoff currents. In the open part of the bay, the Primorsky Current is clearly visible, which propagates in a southwestern direction at velocities of 10-15 cm/s. In the southwestern part of the bay, it turns south and gives rise to the North Korean Current, which is most pronounced on subsurface horizons. In the Amursky and Ussuriysky bays, the influence of the Primorsky current is clearly manifested only in the absence of wind, when an anticyclonic water circulation is formed in the Ussuriysky bay, and a cyclonic one in the Amursky one. Wind, tidal phenomena and the runoff of the Razdolnaya River (in the Amur Bay) cause a significant restructuring of the current field. Schemes of the main components of the total currents of the Amur and Ussuri Bays, given in the atlas, show that the greatest contribution is made by wind currents, which in the winter season enhance the anticyclonic circulation in the Ussuri Bay, and change it to cyclonic in summer. During the passage of cyclones, the velocities of the total currents on the surface can reach 50 cm/s.

Tidal phenomena

A semidiurnal tidal wave enters Peter the Great Bay from the southwest and spreads to the secondary bays of Posyet, Ussuriysky and America. She circles the bay in less than one hour. The time of the onset of high water of the semidiurnal tide is slowed down in closed bays and secondary bays separated by islands and peninsulas. The maximum possible tide level (during the day) in the bay is 40-50 cm. The most well-developed tidal level fluctuations are developed in the Amur Bay, in its northwestern region, where the maximum level slightly exceeds 50 cm, and least of all - in the Ussuri Bay and the strait between about. Putyatin and the mainland (tide up to 39 cm). Tidal currents in the bay are insignificant and their maximum velocities do not exceed 10 cm/s.

Ice conditions

The ice regime of the area practically does not prevent regular navigation throughout the year. In the bay, ice occurs in the winter season in the form of fast ice and drift ice. The beginning of ice formation begins in mid-November in the bays of the Amur Bay. At the end of December, most of the bays of the Amur and partly of the Ussuri bays are completely covered with ice. Drifting ice is observed in the open part of the sea. The maximum development of the ice cover reaches in late January - mid-February. From the end of February, the ice situation becomes lighter, and in the first half of April, the bay water area is usually completely cleared of ice. IN harsh winters, especially in the first ten days of February, the ice reaches great concentration, which excludes the possibility of navigation of ships without the use of an icebreaker.

Hydrochemical characteristics

In this version of the atlas, hydrochemical characteristics are presented in the form of maps of the distribution of average annual values ​​of dissolved oxygen (ml/l), phosphates (μM), nitrates (μM), silicates (μM) and chlorophyll (μg/l) at different horizons for winter, spring , summer and autumn without additional description. In the source of data used (WOA"98), the time frames of the hydrological seasons are defined as follows: Winter: January-March. Spring: April-June. Summer: July-September. Autumn: October-December.

Hydrological-acoustic characteristics

The main changes in sound speed values, both seasonal and spatial, occur in the 0-500 m layer. The difference in sound speed values ​​in the same season on the sea surface reaches 40-50 m/s, and at a depth of 500 m - 5 m/s. With. The maximum values ​​are noted in the southern and southeastern parts seas, and the minimum - in the northern and northwestern. The range of seasonal changes in the speed of sound in both zones is approximately the same and reaches 35-45 m/s. The frontal zone runs from the southwest to the northeast through the central part of the sea. Here, in the 0-200 m layer, the maximum horizontal gradients of sound speed values ​​are observed at any time of the year (from 0.2 s‾¹ in summer to 0.5 s‾¹ in winter). At the same time, the maximum changes in the horizontal sound speed values ​​are observed in summer at a depth of 100 m.

According to the vertical distribution of the speed of sound in the southern and southeastern parts of the sea, we can distinguish:

• the upper homogeneous layer, the thickness of which varies from 50 to 150 m during the year, with sound speeds of more than 1490-1500 m/s;
• a jump layer of sound speed values ​​with large negative gradients (on average 0.2-0.4 s‾¹), extending to a depth of 300 m;
• layer 300-600 m with minimum values ​​(and gradients) of sound speed;
• deeper than 600 m, there is a constant increase in the speed of sound, mainly due to an increase in hydrostatic pressure.

The PZK axis is located at depths of 300–500 m, and off the coast of Japan at 40º N. sh. drops to 600 m. The sound channel extends from the surface to the bottom.

In the northern and northwestern parts of the sea, a homogeneous layer, but with minimal sound speeds (less than 1455 m/s) is formed in winter and is associated with winter convection. The layer thickness can reach 600 m, thus forming a surface sound channel. In the rest of the year, changes in sound speed with depth are characterized by negative gradients, increasing from spring to autumn up to 0.5–0.8 s constant value of the gradient. The UZK axis with minimum sound speeds of 1455-1460 m/s in this part of the sea comes to the surface in winter, and from spring to autumn it gradually drops to a depth of 200-300 m. When moving south in the front area, the UZK axis sharply deepens to 300 m In the central part of the sea, the width of the sound channel in winter does not exceed 1000-1200 m, in spring it increases to 1500 m, and in summer and early autumn it is determined only by the depth of the place.

The nature of our planet is beautiful and amazing. You can admire its beauty forever.

One of the most attractive, unknown, unpredictable elements for a person at all times was water. Among the variety of rivers, seas and oceans, the Sea of ​​Japan is an interesting object for study, the resources of which belong to several countries and play an important role in their development.

Description

This sea belongs to the Pacific Ocean. Along with the Bering and Okhotsk, it is listed as one of the largest and deep seas Russia. It is of great importance in the implementation of transport and freight traffic, is a source of mineral resources. The Sea of ​​Japan is also distinguished by a high level of harvesting of commercial fish species.

Its area stretches over an area of ​​approximately 1,100 square kilometers, with a volume of 1,700 cubic kilometers. The average depth of the Sea of ​​Japan is 1550 meters, while the greatest depth is over 3500 meters.

The sea is connected to other seas and the ocean by straits. Nevelsky connects it with the Sea of ​​Okhotsk, Korean with East China. Shimonoseki separates the Sea of ​​Japan and the Inland Sea of ​​Japan, and is also connected to the Pacific Ocean through the Sangar Strait.

Location

The Sea of ​​Japan lies between mainland Asia and the Korean Peninsula. It washes the land of several countries: Russia, Japan, North Korea, the Republic of Korea.

A characteristic of the Sea of ​​Japan is also the presence of small islands, such as Popov, Okushiri, Russian, Oshima, Putyatin, Sado and others. Basically, the cluster of islands is concentrated in the eastern part.

The waters form bays, for example, Sovetskaya Gavan, Ishikari, Peter the Great. As well as capes, the most famous of them are Cape Lazarev, Korsakov, Soya.

The Sea of ​​Japan has many shipping ports. Some of the most significant are Vladivostok, Nakhodka, Aleksandrovsk-Sakhalinsky, Tsuruga, Chongjin and others. They organize the transportation of goods not only across the Sea of ​​Japan, but also beyond its borders.

Climate

The weather characteristics of the Sea of ​​Japan are temperate and subtropical climate, steady winds.

Geographical position and large extent divided it into two climatic parts: the northwestern and southeastern zones.

The water temperature in different parts depends on the circulation of flows, heat exchange with the atmosphere, the time of year, and also on the depth of the Sea of ​​Japan. In the northern and western parts, the water and air temperatures are much lower due to the influence of the cold Sea of ​​Okhotsk. The waters and air masses that came from the Pacific Ocean play an important role in the eastern and southern zones, so the temperatures are much higher.

In winter, the sea is prone to hurricanes, storms, the duration of which can be several days. The autumn period is typical strong winds that form high, powerful waves. In the summer season, stable warm weather prevails in both climatic zones.

Characteristics of the waters

In winter, the water temperature in different areas varies greatly. The northern part is characterized by an ice cover on the surface, while in the southern part the approximate temperature is 15 degrees.

In summer, the northern waters of the Sea of ​​Japan warm up to 20 degrees, the southern ones - up to 27.

The water balance consists of two important components: the amount of precipitation, the evaporation of water from the surface, and the exchange of water, which is carried out with the help of straits.

Salinity is made up of the resources of the Sea of ​​Japan, water exchange with other seas, the Pacific Ocean, precipitation, ice melting, season, and some other factors. The average salinity is about 35 ppm.

The transparency of water depends on its temperature. In winter, it is higher than in the warm period of the year, therefore, in the northern part, the density is always higher than in the southern part. According to this principle, the saturation of water with oxygen is distributed.

Development of transport routes

The role of the Sea of ​​Japan in the organization of cargo transportation is very important both for Russia and for other countries.

Maritime transport and cargo transportation is highly developed, which is of great importance for Russia. The Trans-Siberian Railway ends in the city of Vladivostok. Here the unloading of railway and loading of sea transport is carried out. In the future, passengers and cargo are sent by sea to other ports of different countries.

Fishing

Fish resources of the Sea of ​​Japan are characterized by high productivity, diversity, including a large number of fish species. Its waters accommodate more than 3,000 inhabitants. Their population depends on the climate conditions in different areas.

In the warm southeastern part, mackerel, saury, sardine, horse mackerel, anchovies, flounder, and some other varieties of fish are common. Here you can also meet a large number of octopuses. Squid and crabs live in the central regions. In the northwest, salmon, pollock, cod, and herring are caught. The sea also abounds with trepangs, mussels, oysters.

Recently, industries have been actively developing in which breeding of crayfish, sea urchins, as well as the cultivation of algae, seaweed, kelp, mollusks, scallops. These aquacultures are also resources of the Sea of ​​Japan.

In addition to commercial species, the Sea of ​​​​Japan is rich in other inhabitants. Here you can meet seahorses, dolphins, whales, seals, sperm whales, white whales, small sharks and other types of marine life.

Ecology

Like the resources of the Sea of ​​Japan, environmental problems need to be studied separately. The impact of the life of the population on the environment in different areas is different.

The main source of pollution is the discharge of industrial and domestic effluents. The greatest negative impact is exerted by the release of radioactive substances, products of oil refining, chemical and coal industries, and metalworking. Wastes from various industries flow into the waters of the Sea of ​​Japan.

The extraction and transportation of oil is associated with great risks for the environment. In the event of a leak, the oil stain is quite difficult to remove. It causes enormous damage to the ecology of the sea and its inhabitants.

Transport waste from numerous ports, sewage from cities that fall into the sea also cause considerable harm.

Studies of the water of the Sea of ​​Japan show a rather high level of pollution. The composition contains many chemical elements discarded by industries, as well as heavy metals, phenol, zinc, copper, lead, mercury, ammonium nitrogen compounds and other substances. All this contributes to a huge pollution of the environment.

The leaders of the countries with which the sea borders are taking targeted operational and preventive actions in order to preserve the unique nature, cleanliness and its inhabitants. It is necessary to control, stop, severely punish cases of releases of chemical and oil wastes into the waters. Enterprises and sewerage required in without fail equip with cleaning filters.

These control measures will be able to prevent environmental pollution, protect numerous inhabitants from death, and also preserve the health of people.

The Sea of ​​Japan is one of the most valuable resources that must not only be actively used, but also protected from the negative consequences of human life.

The information provided will help assess the resources of the Sea of ​​Japan, study its characteristics, recognize its inhabitants, and clarify environmental aspects.

The study of this sea has been going on for a long time. Nevertheless, many questions and problems remain that require research and action.

Refers to the Pacific Ocean, or rather, to its western part. Located near Sakhalin Island, between Asia and Japan. Washes South and North Korea, Japan and the Russian Federation.

Although the reservoir belongs to the ocean basin, it is well isolated from it. This affects both the salinity of the Sea of ​​Japan and its fauna. The overall balance of water is regulated by outflows and inflows through straits. It practically does not participate in water exchange (the contribution is small: 1%).

It is connected with other water bodies and the Pacific Ocean by 4 straits (Tsushima, Soyu, Mamaia, Tsugaru). is about 1062 km 2. The average depth of the Sea of ​​Japan is 1753 m, the greatest is 3742 m. It is difficult to freeze, only its northern part is covered with ice in winter.

Hydronym - generally accepted, but disputed by the Korean powers. They claim that the name is, literally, imposed Japanese side around the world. In South Korea, it is called the East Sea, while North Korea uses the name East Sea of ​​Korea.

The problems of the Sea of ​​Japan are directly related to the environment. They could be called typical, if not for the fact that the reservoir washes several states at once. They have different policies on the sea, so the influence of people also varies. Among the main problems are the following:

• industrial production;
• release of radioactive substances and oil products;
• oil slicks.

Climatic conditions

The Sea of ​​Japan is divided into three parts by glaciation:

• Tatar vs.;
• Gulf of Peter the Great;
• area from Cape Povorotny to Belkin.

As already described above, ice is always localized in a part of a given strait and bay. In other places, it practically does not form (if we do not take into account the bays and northwestern waters).

An interesting fact is that initially ice appears in places where there is fresh water from the Sea of ​​Japan, and only then it spreads to other parts of the reservoir.

Glaciation in the south lasts about 80 days, in the north - 170 days; in the Gulf of Peter the Great - 120 days.

If the winter is not marked by severe frosts, then the areas are covered with ice in early-late November; if temperature drops to critical levels are observed, then freezing occurs earlier.

By February, the formation of the cover stops. At this moment, the Tatar Strait is covered by about 50%, and the Gulf of Peter the Great - by 55%.

Thaw often begins in March. The depth of the Sea of ​​Japan contributes to the rapid process of getting rid of ice. It may start at the end of April. If the temperature is kept low, then thawing begins in early June. First, parts of the Gulf of Peter the Great are "opened", in particular, its open water areas, and the coast of the Golden Cape. While the ice begins to recede in the Tatar Strait, it thaws in its eastern part.

Resources of the Sea of ​​Japan

Biological resources are used by man to the maximum extent. Fishing is developed near the shelf. Valuable fish species are herring, tuna and sardines. In the central regions, squids are caught, in the north and southwest - salmon. The algae of the Sea of ​​Japan also play an important role.

Flora and fauna

The biological resources of the Sea of ​​Japan in different parts have their own characteristics. Due to the climatic conditions in the north and northwest, nature has moderate characteristics, in the south the faunistic complex prevails. Near the Far East there are plants and animals that are characteristic of a warm-water and temperate climate. Here you can see squids and octopuses. In addition to them, there are brown algae, sea urchins, stars, shrimps and crabs. Yet the resources of the Sea of ​​Japan squeak with diversity. There are few places where you can find red ascidians. Scallops, ruffs and dogs are common.

Sea problems

The main problem is the consumption of sea resources due to the constant fishing for fish and crabs, algae, scallops, sea urchins. Together with state fleets, poaching is flourishing. The abuse of fish and shellfish production leads to the constant extinction of any species of marine animals.

In addition, careless fishing can lead to death. Due to fuel and lubricant waste, sewage and oil products, fish die, mutate or become contaminated, which poses a great danger to consumers.

A few years ago, this problem was overcome thanks to coherent actions and agreements between the Russian Federation and Japan.

Ports of companies, enterprises and settlements are the main source of water pollution with chlorine, oil, mercury, nitrogen and other hazardous substances. Due to the high concentration of these substances, blue-green algae develop. Because of them, there is a danger of contamination with hydrogen sulfide.

tides

Complex tides are characteristic of the Sea of ​​Japan. Their cyclicity in different areas is significantly different. Semi-diurnal is found near the Korean Strait and near the Tatar Strait. Daily tides are inherent in areas adjacent to the coast Russian Federation, Republic of Korea and North Korea, as well as near Hokkaido and Honshu (Japan). Near Peter the Great Bay, the tides are mixed.

The tide level is low: from 1 to 3 meters. In some areas, the amplitude varies from 2.2 to 2.7 m.

Seasonal fluctuations are also not uncommon. They are observed most often in summer; there are fewer in winter. The nature of the wind, its strength also affects the water level. Why are the resources of the Sea of ​​Japan highly dependent.

Transparency

Throughout the sea, the water is of different colors: from blue to blue with a green tint. As a rule, transparency is maintained at a depth of up to 10 m. There is a lot of oxygen in the waters of the Sea of ​​Japan, which contributes to the development of resources. Phytoplankton is more common in the north and west of the reservoir. On the surface of the water, the oxygen concentration reaches almost 95%, but this figure gradually decreases with depth, and already by 3 thousand meters it is 70%.

Bottom relief. Soils. By the nature of the underwater relief, the Sea of ​​Japan is a deep depression. This basin begins from the parallel of the La Perouse Strait and ends at the southern limits of the sea. In the northern part of the basin, the bottom is relatively flat with prevailing depths of 3300-3600 m. In the south, the basin is divided by an underwater ridge into two parts: western and eastern. This range is oriented along the meridian of the Oka Islands and extends into the sea to its middle. At the northern end of the ridge there are two underwater heights: Shunpu with a minimum depth of 417 m and Yamato - 287 m. These two heights are separated by an underwater saddle. By their nature, the Shunpu and Yamato uplands are of volcanic origin; pumice and volcanic (melted) glass can be found on their slopes.

The shores of Primorye, North Korea and the southern part of Hokkaido are steep. Depths of 2000 m are located 60 miles from the coast of Primorye, in some places 15, and sometimes 4-7 miles. So, in North Korea, between the capes of Kazakov and Boltin, the two thousandth isobath is 7-10 miles from the coast, and at the southwestern tip of Hokkaido, at Cape Motsuta (Kutuzov), even 4 miles.

Unlike other seas surrounding the Soviet Union, no large rivers flow into the Sea of ​​Japan. Of the few rivers, predominantly mountainous, the largest river. Tumynjiang (Tumyn-Ula).

On the western coast of Sakhalin there are only streams, often with waterfalls. Rivers flowing from the central mountain ranges Hokkaido and Honshu and flowing into the Sea of ​​Japan are very short. Even the most important rivers, the Ishikari, the Teshiogawa in Hokkaido, the Shinanogawa and Magamigawa in Honshu, are no more than 350 km long and are accessible only to small boats.

The basin of the rivers of the Sea of ​​Japan several times less area the sea itself. For other seas, for the most part, the opposite relationship is observed: for example, the basin of rivers flowing into the Caspian Sea is more than 8 times larger than the area of ​​the sea itself.

This circumstance affects the nature of the soils that make up the bottom of the Sea of ​​Japan. They form under conditions of limited input of solid particles from the mainland.

Sea bottom soils are extremely diverse. This is due to the peculiarities of the geological processes that took place in the sea, the complexity of the bottom relief, the richness and heterogeneity of the organic world. The solid remains of living beings, falling continuously as rain on the seabed, are one of the main sources of sedimentation in the Sea of ​​Japan. The most common are silty deposits. They are found at depths of more than 3000 m.

With a decrease in depth in the silt, the admixture of sand increases. Sandy silt (silt with a small admixture of sand) occupies vast areas in the central part of the sea at depths of 2000-3000 m. It is also characteristic of the continental slope (a relatively narrow area where the bottom abruptly changes from the coastal continental shoal to great depths of the sea). Above, silty sand is distributed, confined mainly to the continental shelf. It is found on banks and in the bays of Peter the Great, Olga, Vladimir. In the coastal parts of the continental shoal, sand predominates, which borders the shores of a large part of the sea with a strip of 5-10 miles.

There are pebbles and gravel along the coast. However, often pebble-gravel soils are also found far from the coast. The “seaside pebble belt”, first described by N.I. Tarasov, is characteristic. This belt stretches in a relatively narrow strip 10-15 miles from the coast of Primorye and is one of the ancient submerged coastlines Sea of ​​Japan.

In some places in the Sea of ​​Japan, outcrops of rocky soil are observed. Most often they are found near rocky shores, on the banks of the Yamato Seamount and on the Musashi Bank, northwest of about. Hokkaido. Sometimes these bedrock outcrops can be traced at great depths (about 1000 m). In such cases, they are confined to the steepest parts of the continental slope with a bottom inclination of up to 7–10° or more, for example, near the southwestern tip of Hokkaido and south of Peter the Great Bay.

flow system. In the Sea of ​​Japan, as in the vast majority of the seas of the northern hemisphere, there is a counterclockwise circulation of water.

A branch of the warm current Kuro-Sivo-Tsushima current enters the Sea of ​​Japan through the Korea Strait (Kuro-Sivo is a continuation of the northern trade wind current, which originates under the influence of the northeast trade wind of the Pacific Ocean, blowing throughout the year. The trade wind current crosses the ocean from east to west between 10 and 20 ° N. Reaching the Philippine Islands, it is divided into several branches, the main of which is directed north, comes to the island of Taiwan and from here follows further north under the name Kuro-Sivo (in translation - blue current, so it is named for its exceptionally pure blue color.) When approaching the southern shores of Kyushu, the current divides into several branches, one of which, the Tsushima Current, penetrates into the Sea of ​​Japan.). To meet him, adhering to the mainland coast, the cold Primorskoye is moving from north to south. These currents play a huge role in the life of the sea.

The Tsushima Current enters the Sea of ​​Japan through both passages of the Korea Strait. The bulk of the water flows in through the Krusenstern pass, a smaller part - through the Broughton pass.

Leaving the Korea Strait behind, the Tsushima Current approaches the Japanese shores. A much smaller part of its waters rushes to the north as a separate branch, towards about. Ulleungdo, from which it goes further under the name of the East Korean current, gradually deviating to the east, crosses the sea and flows into the Sangara Strait from the western side, connecting with the main branch of the Tsushima current.

The main flow of the Tsushima Current, directed along the Japanese Islands, has a low speed. On the site of Tsushima - Noto Peninsula, the speed is only 1/2-1/3 knots (Knot is a unit of speed equal to 1.85 km / h). Encountering on its way numerous obstacles in the form of banks, capes protruding far into the sea, the current forms many local eddies.

About three quarters of the waters of the Tsushima Current enters the Pacific Ocean through the Sangar Strait, where the current is always directed from the Sea of ​​Japan to the Pacific Ocean. At high tide, its highest speed is more than

7 knots, and at low tide it drops sharply. At northern shores the strait, with fresh east winds, as well as at a strong ebb, even a current from the Pacific Ocean to the Sea of ​​\u200b\u200bJapan arises.

The rest of the Tsushima Current follows northward along the western shores of Hokkaido and, having reached the La Perouse Strait, exits mainly into the Sea of ​​Okhotsk. Off the southwestern coast of Sakhalin, the current is greatly weakened. Nevertheless, the slow movement of waters along the western shores of Sakhalin can be traced to the northern borders of the sea (On the approaches to the Sangar Strait, the speed of the Tsushima Current is 1-1.5 knots. In the Tatar Strait, the current velocities are very small and do not exceed 1/4-1/2 knots ).

As we move from south to north, the waters of the Tsushima current cool down, giving up their heat to the air, and they arrive north to a large extent modified.

This is what happens in the summer. In winter, the picture changes dramatically.

In the Korea Strait, the bulk of the Tsushima waters are directed through the Broughton Passage, in the Krusenstern Passage the current is negligible, and in the dead of winter it stops altogether. Off the western shores of Kyushu and off the southwestern shores of Honshu, even reflux from the Sea of ​​Japan to the East China. The East Korean current also weakens due to the winter monsoon and does not penetrate far to the north. This is explained by the strong northern and northwestern winds of the winter monsoon, which have a decelerating effect on the Tsushima Current. Only when the north wind gives way to the south (this happens when cyclones pass through the Sea of ​​Japan), the Tsushima current resumes again, but it is possible that in the deep layers there is always a constant, albeit weak, flow of water to the north.

Regarding the Primorsky current, it was believed that it begins in the Sea of ​​Okhotsk, in the Amur estuary, therefore it was called "estuary". Later, Russian researchers proved that water from the Sea of ​​Okhotsk does not flow through the Nevelskoy Strait. In summer, they cannot penetrate into the Sea of ​​Japan, since its level is higher than in the Sea of ​​Okhotsk. The southern winds of the summer monsoon constantly prop up the waters in the Tatar Strait, thereby preventing the penetration of the waters of the Sea of ​​Okhotsk and the fresh water of the Amur. Only in winter, when northwestern winds drive water into the Sakhalin Bay of the Sea of ​​Okhotsk, conditions are created for the inflow of a certain amount of sea water and fresh Amur water into the Sea of ​​Japan. However, in winter, the flow of water through the Nevelskoy Strait is so small that it cannot create any significant current.

The coastal current, named so by a major researcher domestic seas K. M. Deryugin, originates in the area between Sovetskaya Gavan and De-Kastri Bay. Further, it is directed from north to south along the coast of the Soviet Primorye and North Korea. Even in the old sailing directions, it was noted that during the accident of one ship south of De-Kastri Bay, discarded barrels of kerosene were found two months later south of Peter the Great Bay. The Primorsky current brought them here. Along the southeastern coast of Korea, this current is not clearly visible in the surface layers, but it is possible that here it passes at some depth.

The speed of the Primorsky current ranges from 1/4 to 1/2 knots, but can be more at times. In summer, the current approaches the coast, forming local turbulences in its bends. In winter, the nature of the current changes: numerous branches depart from it into the open sea.

The content of salts and gases. Transparency and color of water. Sea water differs from the water of rivers, lakes and other land bodies of water in a number of ways. The bitter-salty taste makes it unsuitable for drinking; it does not dissolve ordinary soap and cannot be used in steam boilers, as it forms a lot of scale. This is because sea water is a weak solution of various salts.

The amount of dissolved salts, expressed in grams per kilogram of sea water, is called its salinity. Usually in the open ocean, away from estuaries major rivers, water contains 35 grams of salts in 1 kg of water, or 35 thousandths of a kilogram. Thousandths of a whole are usually called ppm and denoted by "° / oo". Therefore, the average salinity of the World Ocean is 35% o.

Some salts are found in sea water in large quantities, such as sodium chloride (NaCl) and magnesium chloride (MgCl); together they make up 89% of all dissolved salts by weight, while others - in negligible amounts, measured in thousandths of a gram per ton of water. Thus, the content of silver in sea water is only 0.0002 g per ton of water, and gold is only 0.000005. However, the total amount of gold and other rare metals in the oceans is estimated at several billion tons.

The salinity of the seas is both less and more than the ocean. In the seas, surrounded on all sides by countries with a hot climate and having a small flow of rivers, the salinity is greater than that of the ocean. For example, in the Red Sea, surrounded by deserts, salinity reaches 41%o. In most seas the globe due to the flow of rivers, the salinity is less than that of the ocean.

In the Sea of ​​Japan, although the flow of the rivers flowing into it is extremely small, the salinity is also less than that of the ocean. This is due to the fact that salinity is determined not only by the flow of rivers, but also by the ratio between precipitation and evaporation, and precipitation in this sea exceeds evaporation, which is why its salinity is less than oceanic, although not by much. On average, the salinity of the waters of the Sea of ​​Japan is 34°/oo, slightly lower under the mainland coast, and higher near the eastern coast. In the Sea of ​​Japan there are no areas with strongly freshened water, in this it differs sharply from all other seas washing the Soviet Union.

The salinity of the sea during the year varies slightly. Its largest seasonal fluctuations are in the north of the sea in the Tatar Strait, where it varies from 34% in autumn and winter to 32% in spring. The decrease in salinity in spring is associated with the desalination effect of ice melting. In the depths of the sea, below 300-500 m, there are no seasonal fluctuations.

In addition to salts, various gases are dissolved in sea water: oxygen, nitrogen, carbon dioxide, and sometimes hydrogen sulfide. They enter the sea from the atmosphere and as a result of the vital activity of animals, plant organisms, as well as complex chemical processes occurring at the bottom or in the water column. Oxygen is of the greatest importance for the development of life in the sea. It enters the water either from the air or is released during respiration. marine plants. Oxygen is consumed for the respiration of animal organisms and for the oxidation of various substances, and sometimes it is released into the atmosphere with an excess of it in the surface layers.

The amount of gases dissolved in sea water is very small and variable. The most saturated with oxygen are the surface layers of the sea, in which the smallest plant organisms - phytoplankton - intensively develop, and higher plants - sea grasses - off the coast. A large amount of oxygen is absorbed by the surface layers of the sea, it gets to the depths as a result of the mixing of sea water by waves, as well as when immersed in chilled or saline waters on the surface.

The waters of the Sea of ​​Japan from the surface to the deepest depths are highly saturated with free oxygen. This indicates an intensive exchange between surface and deep waters, which occurs mainly in winter, when surface waters cool down and sink to a depth already heavier, deep water comes out in their place.

The processes of vertical mixing and enrichment of deep waters with free oxygen occur most intensively in the northern part of the Sea of ​​Japan, where, in addition to cooling, the increase in the density of the surface water layer is also affected by ice formation, during which salts precipitate into the water, and sea ice becomes almost fresh. That is why in the Sea of ​​Japan, not only surface, but also deep waters are highly enriched with free oxygen.

The transparency and color of sea water are determined by the substances dissolved and suspended in it. It has been established that the less impurities in the water, the bluer its color. There are few solid substances in the water of the Sea of ​​Japan, so the color of its waters depends mainly on the content of plankton - microscopic organisms suspended in the water. The abundant development of plankton explains the change in the color of sea water from blue to green and even yellow and brown. In spring, with the rapid development of plankton, the color of the sea acquires yellowish-green and even brownish-green hues. This happens mainly near the seaside and Korean coasts.

In most areas, the waters of the Sea of ​​Japan are blue-green. In the southeast, in the zone of the Tsushima current, the color of the water is intense blue, and in the north, in the Tatar Strait, greenish. The blue color of sea water corresponds to high transparency, and green, yellowish and brown - low. The transparency of sea water is usually determined by the depth at which a submerged white disk with a diameter of 60 cm begins to disappear from the eyes.

In the zone of the Tsushima current, water transparency is high and reaches 30 m, in the central part of the sea it is 15-20 m, and near the western coast in spring, with intensive development of plankton, it drops to 10 m.

Water temperature. In terms of water temperature and its change with depth, the Sea of ​​Japan is unlike any of the other seas washing the shores of the Soviet Union. Judging by the surface temperatures in the summer, this is a warm sea. At the depths, the water is cold, only one or two tenths of a degree above zero. First of all, the amazing uniformity of the temperature of the deep layers is striking. Starting from 400-500 m in the eastern part of the sea and from 200 m in the western part, the water temperature is 0.1-0.2°.

The absence of negative water temperatures near the bottom at great depths of the sea is characteristic (the freezing point of sea water at a salinity of 34-35 ° / oo is minus 1.7-1.8 °). Meanwhile, it would seem that the water masses, having cooled down to -1.7° in winter in the northern regions of the sea, should slide to the depths of the central basin of the sea. Of course, at the same time they mix with the surrounding waters and their temperature rises somewhat, but since cold waters enter the depth every winter for a long time, a gradual cooling of the deep waters should be observed. However, this does not happen: no cooling trend has been noticed. Obviously, deep waters reach their thermal equilibrium, that is, the cooling caused by the inflow of waters with negative temperatures from the northern part of the sea is compensated to a certain extent by the influx of the internal heat of the earth, as well as the inflow of heat from surface layers southern warm part of the sea.

Let us consider in more detail the distribution of water temperature over the area of ​​the sea and how it changes with depth, as well as from season to season.

In the figures showing the distribution of temperatures on the sea surface in February and August, attention is drawn to the location of isotherms oriented from the southwest to the northeast. The large temperature contrast between the western and eastern parts of the sea is clearly visible. This contrast is especially pronounced in winter, and in the south it is little pronounced, and in the north it is very sharp. So in February, on the 42° parallel in the east of the sea, the temperature reaches 5-6°, and in the west, south of Peter the Great Bay, it drops to zero and below.

In summer, the difference between the western and eastern parts of the sea is somewhat smoothed out, but only in the surface layers; with depth, the temperature contrast increases: near the mainland coast, the water temperature at a depth of 50 m is 2-3 °, and in the east of about. Honshu 12-16°. At depths of 300-500 m, this contrast somewhat decreases, and at 1000-1500 m it disappears completely.

To characterize the variability of water temperature from season to season, we will use the graphs of the annual temperature variation, built on the basis of long-term average data for different parts of the sea. On fig. (p. 47) shows the annual temperature variation in the Korea Strait at a point 20 miles northwest of Cape Kawajiri. Here, for many years, the temperature of the water was observed at various depths. This graph is typical for the Tsushima current passing in the Korea Strait through the Krusenstern passage. The minimum temperature at all depths is observed in March, the maximum on the sea surface - in August, at a depth of 25 m - in September, 50 m - in October, and 75 m - in November, that is, it lags from horizon to horizon.

A different character of the annual temperature variation is observed in the same strait near the Korean coast. Up to 25 m, it is almost the same as at a point northwest of Cape Kawajiri. But for greater depths, significant differences emerge. Already at 50 m June-July there is a decrease in water temperature, and at 75, 100 and 120 m a sharp decrease in temperature is observed throughout the warm half of the year. This is due to the influx of cold waters from the north. Some increase in temperature from the surface to the bottom occurs as a result of wind mixing of waters.

Of great interest are temperature fluctuations in a particular area of ​​the sea from year to year. In a number of places these fluctuations are especially great. They greatly affect the life and behavior of the inhabitants of the sea. With sharp and unusual changes in temperature, some of them are forced to migrate to other places, and many organisms die.

In the Korea Strait, especially in the Krusenstern passage, where the main branch of the Tsushima current flows, temperature fluctuations are small from year to year. The average monthly water temperature in a severe year differs from the temperature of the same month in a warm year by only 2-4°.

A different picture is observed in the open sea. For example, to the west of Wakasa Bay, the temperature can fluctuate from year to year by 6-8° and even more. This is due to a change in the location of the axis of the Tsushima current. Indeed, if the main stream of the warm current shifts to the left or right of its usual position, then where it has shifted, the water temperature will increase. In this place, a focus of large positive temperature anomalies (deviations from the long-term average) is formed. In the region of the usual position of the current axis, the water will become colder, and a zone of negative anomalies will appear there.

Large fluctuations in temperature from year to year are observed in the zone of the Primorsky Current, especially off the coast of North Korea. But this is connected not so much with a change in the axis of the Primorsky current, but with fluctuations in the "heat reserve" in the current itself. Fluctuations in the heat reserve of the Primorsky current are associated with the severity of winters in the Tatar Strait, where it originates. The heat reserve of the Primorsky current in spring and summer depends to a large extent on the severity or mildness of the preceding winter in the region of the current's sources. This dependence makes it possible to predict temperature fluctuations off the coast of North Korea and in the area of ​​Peter the Great Bay.

Ice. In the Sea of ​​Japan, only the northern part is covered with ice. The border of floating ice stretched from the Korean port of Chongjin (Seishin) northward along the coasts of Korea and Soviet Primorye to Cape Belkin (46°N). First, it goes at a distance of 5-10 miles from the coast, and then 15-25 miles. At Cape Belkin, the border turns to the east, then approaches the northwestern coast of Hokkaido in the area of ​​Cape Kamui.

The bays of northeast Korea in winter are usually covered with only a thin crust of ice, which is easily broken up by wind and waves and carried out to sea. Such ice presents no serious obstacles to navigation. Only in severe winters severe frosts and small winds, the ice cover in the bays of Tedinman (Gashkevich), Nadzhinman (Kornilov), etc., reaches a considerable thickness. So on January 12, 1933, at an air temperature of about minus 20 °, the Kornilov Bay was so heavily ice-bound that the local steamship service between the ports of Chongjin and Ungi (Yuki) was stopped. The ice lasted about 10 days, and five days later, from January 27, Kornilov Bay was covered with ice again until February 10. At this time, cargo from the ships was unloaded directly onto the ice.

In very severe winters, ice can appear in the open part of the Gulf of Korea and in the bays of the southeast coast of Korea. The western part of the Peter the Great Bay, at the tops of the Amur and Ussuriysky bays, is usually bound by strong ice, which seriously impedes navigation, and the help of port icebreakers is required.

In the bays of the Soviet Primorye with a wide entrance and the general direction of the longitudinal axis coinciding with the prevailing winter winds (northern or northwestern), the ice is easily broken by them and carried into the sea.

Along the mainland coast from Cape Povorotnoy to Cape Belkin, only primary forms of ice are found: lard, sludge, snezhura, and finely broken ice. north of the cape Belkin they become heavier. In the middle part of the Tatar Strait, coarse and finely broken ice and fragments of ice fields are usually widespread, which are in continuous movement under the influence of winds. For short periods of time, when calm, ice floes can freeze and form large fields that break up at the first fresh wind. The northwest winds of the winter monsoon squeeze the ice from the mainland and drive it to the Sakhalin coast.

The ice of the Tatar Strait is a serious hindrance to navigation. To maintain it in winter, the help of linear icebreakers is required, especially on the approaches to Aleksandrovsk, where the ice reaches considerable thickness and is strongly ruffled. Ice in the northern part of the sea appears in November, first in freshened rivers and closed bays, and then usually in early December in the open sea. In April, the ice quickly breaks down and disappears.

In the narrowness of the Strait of La Perouse, between Cape Crillon and Cape Soya, ice is not observed every year. In the spring, in the second half of March - April, these are mainly the ice of the Sea of ​​\u200b\u200bOkhotsk; they head south along the eastern shores of Sakhalin and end up in Aniva Bay. There they circulate, penetrating into the Sea of ​​Japan only with the tide. However, conditions may arise in which ice blown by easterly winds from Aniva Bay drifts far to the north along the western shores of Sakhalin, posing a serious threat to the set nets. This happens when easterly winds give way to strong southerly winds that carry the ice north to the region of Nevelsk and even Kholmsk. This situation is created when cyclones do not follow their usual path from southwest to northeast, but along the mainland coast from south to north.

The removal of ice can be foreseen in advance if meteorologists serving the spring season near southwestern Sakhalin, in addition to storm warnings, have data from aerial reconnaissance of ice in the La Perouse Strait and reports from coastal posts about the movement of ice to the north. With timely information about the ice threat, it was possible to sink expensive fixed nets and avoid cutting them off with ice.

Wind waves. Tsunami. The importance of wind waves in the life of the sea is enormous. Sea waves are an important factor in mixing the surface layers of water and enriching them with dissolved oxygen. Waves change the contours of the shores: in some cases they wash them away, in others they contribute to building up, creating beaches and spits. Excitement reduces the speed of ships, lowers their controllability. During severe storms, even large ships can be severely damaged and sink.

Knowledge of the wave elements - height, length, period (Wave period - the time interval between passing through the same point of adjacent crests (or bottoms) of the wave) is necessary for the shipbuilder to calculate the ship's hull strength, buoyancy and stability. It is absolutely necessary to take into account the waves in the design, construction and operation of seaports. The construction of port protective structures should be carried out with strict consideration of the prevailing direction of strong waves and the size of the waves.

The size and shape of the waves in any sea depend not only on the strength and duration of the wind that caused them, but also on the depth of the sea, its size, or, as they say, on the length of the wave acceleration. The seas, the depth of which is commensurate with the lengths of the wind waves acting on its surface, are called "shallow" in oceanography. These include the Aral, Azov, northern part of the Caspian. In the "shallow" seas, the waves are short, high, and very steep.

Seas that are deeper than the wavelength are called "deep"; in them, the depth no longer affects the nature of the excitement. The latter includes the Sea of ​​Japan. Its waves are not particularly large, since in summer the winds are predominantly weak, and in winter, although the winds of the winter monsoon are strong, they blow mainly across the sea and for development big waves lack of acceleration.

However, sometimes gigantic waves arise in the Sea of ​​Japan, but they are not caused by winds, but by underwater earthquakes or eruptions of underwater, and sometimes surface coastal volcanoes. Such waves are called tsunamis in Japanese. Over the past two and a half thousand years, 355 tsunamis have been recorded all over the world, of which 17 occurred on the coast of the Sea of ​​Japan.

Level fluctuations. Tides. Fluctuations in the level of the Sea of ​​Japan are mainly of two types: tidal and surge caused by winds (Level fluctuations associated with sudden changes in atmospheric pressure (seiches), although they are observed in the Sea of ​​Japan quite often, they are not significant - they are off the coast are only a few centimeters and very rarely tens of centimeters).

In winter, the northwest monsoon raises the sea level near the western coast of the Japanese Islands by 20 - 25 cm, and near the mainland coast, the level is also lower than the annual average. In summer, the opposite is true: off the coast of North Korea and Primorye, the level rises by 20-25 cm, and near Japanese shores decreases by the same amount. But since the shores of the Sea of ​​Japan are shallow, fluctuations in the level of the surge character are of little practical importance.

Tidal level fluctuations are of great practical importance in the Sea of ​​Japan. They are not the same in different parts of the sea: the greatest level fluctuations are observed in the extreme south and extreme north of the sea. At the southern entrance to the Korea Strait, the tide reaches 3 m. As you move north, it quickly decreases and already at Busan does not exceed 1.5 m.

In the middle part of the sea, the tides are small. Along the eastern shores of Korea and the Soviet Primorye, up to the entrance to the Tatar Strait, they are no more than 0.5 m. The tides are of the same magnitude near the western shores of Honshu, Hokkaido and southwestern Sakhalin. In the Tatar Strait near Aleksandrovsk, the tides reach 2.3 m, at Cape Tyk - 2.8 m. and smaller sections.

In the Sea of ​​Japan, all the main types of tides are observed: semidiurnal, diurnal and mixed (With semidiurnal tides, the level reaches a maximum and minimum twice a day, with diurnal tides - once, with mixed the nature of the level change periodically changes - the level reaches a maximum and a minimum then twice per day, then once). In the Korean Strait and in the northern part of the Tatar Strait, the tides are semidiurnal, on the coast of Honshu and Hokkaido they are diurnal and only occasionally mixed. On the coasts of the eastern part of Korea and Primorye, mainly diurnal, only in the bays of Korea and Peter the Great mixed.

Vegetation. Plant organisms live in the sea only at depths where sufficient sunlight penetrates for life. Therefore, there are usually no plants deeper than 100 m in the seas.

Vegetation is rich in the Sea of ​​Japan. Its surface layers are inhabited by a huge amount of phytoplankton - microscopic lower plants. These are unicellular organisms, devoid of special organs of movement, but having bristles, processes and other adaptations that help them stay in the water. Some of them, for example, peridinea (flagellate) prefer warm waters, others, such as diatoms, are cold. Therefore, in summer, peridineans predominate, and in winter - diatoms. Numerous species of flagella and diatoms make up the bulk of phytoplankton.

In winter, there is little phytoplankton, it is concentrated in the very surface layer of water (0-15 m), while in summer there is a lot of it and is located in a layer of 5-20 m. During the day, phytoplankton makes passive vertical movements: at night, under the influence of gravity, it settles to a depth, and during the day, releasing oxygen bubbles, it rises as if on floats.

Phytoplankton plays a huge role in the life of the sea: it serves as food for various crustaceans, small fish and other marine animals. In spring and summer, during the period of abundant development of phytoplankton, even the color of the sea changes. The blue color turns into green, sometimes the waters take on yellowish hues.

Near the coast, various types of multicellular algae grow on the seabed. They differ from terrestrial plants in that their rhizomes serve for attachment, but not for nutrition. That is why algae "do not like" to settle on muddy soil, but prefer a solid base: stones, sand, shells.

In shallow water off the coast, green algae predominate, which need a lot of sunlight, at a depth of up to 30 m - brown algae, which are less demanding on light, and red algae (purples) settle even deeper, they need even less sunlight.

The coastal waters of Korea, Soviet Primorye, Sakhalin and Hokkaido are known for the abundance of kelp (seaweed) - one of the genera of brown algae. In China, Korea and Japan, it is eaten. Seaweed is fed to livestock. Previously, it was used for the production of iodine (Currently, iodine is obtained in a more economical way - from inorganic substances). Along the western coast of Sakhalin, in addition to kelp, other representatives of brown algae are often found: alaria and fucus. On thickets of these algae, herring lays eggs during spawning. Red algae are also widespread off the coast of Primorye. Among them, ahnfeltia and phyllophora are of practical importance, from which agar-agar is extracted, which is used in the food and textile industries, medicine and photography.

In the Sea of ​​Japan, at a depth of 4-6 m, Sargassum algae is found, sprawling bushes of which reach 3 m in height. In a vertical position, it is supported by special floats. Most of these algae develop in August and September; sometimes, under the action of floats, they break away from the ground and float to the surface of the sea.

In the Sea of ​​Japan, there are representatives of higher flowering plants that live in shallow water off the coast. They have roots, stem, leaves, flowers and seeds. These include sea grass - zostera, which forms vast and dense forests and phyllospadix (sea flax). Thickets of these plants border the rocky shores of Primorye. They are widely used in the furniture industry as stuffing material for mattresses and upholstered seats.

Animal world. The fauna of the Sea of ​​Japan is abundant and diverse: in terms of the number of species, it significantly exceeds the world of plants. Unlike plants that live only in the surface layer, animals inhabit the sea from the surface to the very bottom.

Marine animals that live in the water column are usually divided into zooplankton and nekton. Zooplankton includes unicellular and small multicellular organisms - ciliates and crustaceans, eggs and larvae of various animals, and many others. All of them lack strong organs of movement. Their specific gravity differs little from the specific gravity of sea water, so they seem to “soar” in the water and are carried along with it. Nekton include large organisms that can move independently sometimes over long distances, such as fish.

Of the zooplankton in the Sea of ​​Japan, copepods are the most widespread. There are especially many small calanus crustaceans 1-2 mm in size, which serve as the main food of the most important commercial fish: herring, sardines, mackerels. Larvae of bottom animals are also abundant: sea shells (mollusks), crustaceans, worms and echinoderms (sea urchins and stars).

The main mass of zooplankton is concentrated in the upper layer of the sea (up to 50 m), its quantity decreases with depth. During the day in different seasons of the year, planktonic organisms sometimes make significant vertical movements. At night and in winter they usually rise from the depths to the surface, during the day and in summer they go down. For example, the deep-water cold-loving crustacean Calanus-cristatus, which lives in summer at a depth of 500-1000 m, moves to the uppermost horizons in winter.

The totality of various benthic organisms is united under the name benthos. The benthos of the Sea of ​​Japan is dominated by molluscs, which are characteristic mainly of the shallow water zone, deeper echinoderms predominate, and even deeper, worms and crustaceans. Bivalve mollusks are plentiful: sea, or Japanese, scallops and oysters; from echinoderms - trepangs, sea urchins, stars and sea cucumbers - sea cucumbers. Starfish are predators: they eat oysters, scallops, and even fish that have “grown up” in fishing nets.

Crustaceans (shrimps, lobsters, lobsters, crabs) and cephalopods: octopuses, cuttlefish and squids are very common in the Sea of ​​Japan. Some of these mollusks live at the bottom of the sea (octopuses), others are active swimmers who have lost all connection with the bottom of the sea. Squids are terrible predators that eat everything living in the sea that they can handle: molluscs, crustaceans and even fish. Sometimes they reach huge sizes and attack such large animals as a sperm whale.

In the Sea of ​​Japan, you can meet a fur seal that comes here for wintering from more northern regions, representatives of earless seals - a seal, a dolphin and even a whale.

Fish. The richness of the species composition of fish in the Sea of ​​Japan can be judged from the following data:

This diversity is determined primarily by the abundance of food and the thermal contrast of the northern and southern, eastern and western parts seas. In the north and north-west of the sea there are species of fish of northern latitudes (gobies, liparids, sea chanterelles, cod, navaga), and in the south there are such representatives of the tropics as flying fish, tuna and moon-fish.

Most fish species live in the southern part of the sea, in the Korea Strait and off the coast of about. Honshu. The northern cold part of the sea is poor in species, but due to the rich food (plankton), some of them are numerous and have long been an object of large-scale fishing.

As we move north from the Korea Strait along the western and eastern coasts of the sea, tropical and subtropical fish species disappear. At the same time, the number of inhabitants of cold waters is increasing. There are only 210 species of fish in the Peter the Great Bay, of which cold-water fish predominate, especially in the autumn-winter period and in spring. Southern fish penetrate this area along with jets of warm currents, some of them come regularly (mackerel, saury), others not every year (tuna), some are found as rare finds (moon fish, hammer fish).

The same can be observed in the eastern half of the sea, near the Japanese islands. Only here the southern fish go a little further north compared to the western part of the sea. This applies to fish living in the surface layers of the open sea, they are carried to the north by the Tsushima Current.

In the extreme north of the sea, in the Tatar Strait, the number of species decreases. By nature, the fauna becomes more cold-water. Newcomers from the south are not numerous (mackerel, saury), they come here seasonally and irregularly.

The Sea of ​​Japan is characterized by the absence of true deep-sea fish. The fish that still live at great depths of the sea are completely different from the fish of the Pacific Ocean that live at the same depths on the eastern side of the Japanese islands. Fish of great depths are the former inhabitants of the shallow coastal zone, which have descended and adapted to new living conditions. These are northern gobies and liparids. The latter were found at a depth of more than 3500 m. It is interesting that in the depths of the Sea of ​​​​Japan a fish with such a transparent skull was found that the brain is visible through it.

The absence in the Sea of ​​Japan of true deep-water fish, common in the Pacific Ocean, confirms that this sea is not a part of the Pacific Ocean, laced from it due to the uplift of the Japanese Islands and Sakhalin, but was formed by failure of a section of the earth's crust. Otherwise, representatives of the deep-sea Pacific fauna would have remained in the Sea of ​​Japan.

For demersal and bottom fish, such as cod and flounder, the Sea of ​​Japan is not entirely favorable, primarily due to the poor development of the continental shelf and the lack of shoals and banks - the favorite habitats of these commercial fish.

The Sea of ​​Japan, characterized by temperature contrasts, is convenient for the life of gregarious commercial fish that stay in the upper layer of the open sea and feed on plankton. Life is especially rich in areas where warm and cold waters meet. Fish such as mackerel, herring are collected in numerous shoals. Heat-loving commercial fish include mackerel and sardine.

The story of the catastrophe in the Far Eastern sardine fishery is instructive. Until 1941, it was the main commercial fish in the Sea of ​​Japan. Millions of centners of fish were caught along the eastern coasts of Korea, Japan and the Soviet Primorye. In 1941, the catch was greatly reduced everywhere, and in 1942 it stopped completely in most areas of the Sea of ​​Japan, with the exception of its southernmost limits.

What is this fish, what is the history of its fishing and what are the reasons for its disappearance?

The sardine reaches a length of 30 cm. It does not differ in taste from its sister - the Atlantic sardine, very fatty and tasty, it sometimes contains up to 40% fat.

Unlike many other heat-loving forms, it reacts most sensitively and painfully even to minor changes in temperature. The Soviet scientist P. Yu. Schmidt cites cases of mass mortality of sardines off the coast of Sakhalin in the summer with a sudden and sharp drop in temperature.

Sardine - an alien from the subtropics. It spawns in the south, mainly off the southwestern shores of the Japanese island. Kyushu. Previously, there were spawning sites along the western and northeastern shores of about. Honshu within the Tsushima current. Spawning occurs in the south in January - February, in the northern regions in March - April at a temperature of 12-15 °.

After spawning, the sardine rushes to fattening in the northern regions of the Sea of ​​Japan, where it finds an abundance of plankton. The rapid development of plankton is confined to the junction of warm and cold waters. Many commercial fish are concentrated here. These places represent the centers of world fishing. The junction of the Gulf Stream and the cold Labrador Current in the area of ​​the Great Newfoundland Bank, the frontal zone of the meeting of the Kuro-Sivo and the cold Kuril Current in the northwestern part of the Pacific Ocean are the richest and longest-known areas of the world fishery.

Sardine migrations to the north took place in two ways - along the eastern coast of Korea and the western coasts of Honshu and Hokkaido. Numerous flocks, clearly visible from the ship and especially from the plane, the sardine approached the shores of the Soviet Primorye, where they were caught with flowing nets, purse seines in the open sea and, most importantly, with fixed seines near the shore.

The sardine usually reached our shores in the area of ​​Peter the Great Bay in June, and in July-August it penetrated the Tatar Strait, reached De-Kastri Bay, and in October it migrated back, rolling back to the southern limits of the sea.

Iwashi fishing off the coast of Japan began in the middle of the last century, and off the coast of Soviet Primorye only in 1925, when 4400 centners of this fish were first caught. P. Yu. Schmidt wrote: “When I first came to the shores of the Pacific Ocean in 1900, I met Iwashi in Nagasaki, but in Vladivostok, when collecting information about the fishery, no one told me anything about this valuable fish. It was not even in the fish market, where at that time it was possible to get a wide variety of representatives of the ichthyofauna.”

In the thirties, the sardine was the main object of the Soviet fishery in the Sea of ​​Japan. In 1937, its catch reached a record figure - 1,400,000 centners. In the thirties, more than 10 million centners were caught off the coast of Korea, and 12-15 million centners off the coast of Japan.

In 1941, a disaster occurred in the sardine fishery in the Sea of ​​Japan.

What happened to the sardine? There is no complete unanimity on this issue among scientists. The Japanese scientist Yasugawa considers the main reason for the disappearance of the sardine to be extremely unfavorable spawning conditions in 1936-1939, which resulted in a sharp decrease in the number of sardines.

The Soviet scientist A. G. Kaganovsky explains the disappearance of the sardine not only by a change in temperature conditions, but also by qualitative changes in the number of sardines - its grinding. A small sardine is even more sensitive to a decrease in temperature than a large one.

Beginning in 1941, summer temperature conditions in the Sea of ​​Japan were extremely unfavorable for sardines. In the northern and central parts sea ​​surface waters turned out to be 3-4 ° colder than in ordinary years, and from the Korean port of Wonsan to Japanese port In Niigata, a cold layer of water was formed (besides, the sardine was poor in food - plankton), preventing the sardine from entering our waters.

P. Yu. Schmidt also considers the cooling of the waters of the Sea of ​​Japan to be the main reason for the disappearance of the Far Eastern sardine. In support of his view, P. Yu. Schmidt in his book “Pisces of the Pacific Ocean” cites maps of water temperatures in the Sea of ​​Japan compiled by A. M. Batalin. These maps clearly show the significant difference in the physical conditions of the sardine in 1941 and 1942. compared to a normal year, such as 1932.

It was found that off the southwestern coast of Kyushu, in the main sardine spawning grounds, the water was 2-3° colder than normal only in the winter of 1936, and in subsequent winters (1937-1940) it turned out to be normal. Therefore, the unfavorable spawning conditions of 1936 could only affect the generation of that year. Thus, the theories of P. Yu. Schmidt and A. G. Kaganovsky are more correct than Yasugawa.

Now let's talk about the reasons for the cooling of the Sea of ​​Japan in 1941-1944. A. M. Batalii believes that it is partly due to a decrease in the amount of heat delivered to the Sea of ​​Japan by the Tsushima Current. He saw the main reason in the shift of warm currents to the southeast under the influence of the intensified in 1941-1942. winter monsoon.

However, it seems to us that the cooling is associated with very cold winters of the period 1940-1943. In these winters, powerful ice formed in the Tatar Strait, which persisted in the spring longer than usual, and therefore the Primorsky current intensified in these years. The cold waters of the Primorsky current created the barrier that prevented the sardine from breaking through to the shores of the Soviet Primorye.

The fact that the sardine came to our shores in the twenties, during the warming period of the Sea of ​​Japan, and disappeared in the forties, during the cooling period, allows us to assume that over time the sardine will again enter the northern part of the sea. The temperature regime of the Sea of ​​Japan had already reached its usual state several years ago, but it will probably take several more years for the sardine, which is now held in the southernmost reaches of the sea, to gradually spread northward with increasing numbers. It is possible that this process has already begun, as evidenced by the first centners of sardines caught in the north of the sea, off the coast of Sakhalin, in the summer of 1954-1955.

Another heat-loving fish - mackerel - after the disappearance of the sardine became one of the main objects of the Soviet fishery in the Sea of ​​​​Japan. Adult mackerel in commercial quantities is found at water temperatures from 6 to 22 °. Its temperature optimum is 12-16°. Mackerel in January - March lives in the southern part of the sea, adjacent to the Korea Strait, and keeps mainly at the bottom. Here it is caught at depths of 100-150 m with bottom fixed seines and trawls.

In March, the water temperature in this area is 13-14° and is almost the same from the surface to the bottom. In spring, with the beginning of warming, mackerel migrates north for spawning, which lasts from April to July. Mackerel spawns in the coastal strip, in bays and bays or between islands, mainly along the northeastern coast of Korea and in Peter the Great Bay.

The start of mackerel spawning depends on the maturation of its reproductive products, which in turn depends on the water temperature in the area of ​​its wintering. If the temperature there is above normal, then the gametes will ripen earlier, and mackerel will spawn in the nearby bays of the eastern coast of Korea; very few unspawned fish will reach Peter the Great Bay. When the water temperature is low in the wintering area, the maturation of reproductive products is delayed, a significant part of the mackerel, without spawning, reaches Peter the Great Bay, where the main spawning takes place.

After spawning, mackerel moves further north in search of food until it reaches the northern limits of its habitat: Sovetskaya Gavan - Wide Pad. In September - October, she leaves the northern regions and migrates south to the wintering grounds.

Cold-loving fish of the Sea of ​​Japan include cod, flounder, and herring. However, extremely low temperatures are “contraindicated” for them, just as very high temperatures are “contraindicated” for heat-loving fish. Especially badly they tolerate negative temperatures. In winter, when cold waters appear off the coast of Primorye, cod move to depths and come to the coast in summer when it gets warmer. Off the coast of Hokkaido, in summer, when the temperature in the coastal strip rises, cod, on the contrary, migrates from the coast to deeper and colder horizons, and stays off the coast in winter, since the water temperature here is favorable for it.

Unlike the Atlantic cod, which has free-floating eggs, the Pacific cod, like the goby and the stingray, has bottom-dwelling eggs. This biological fitness has developed in the Far Eastern cod due to the fact that it spawns in areas with strong currents and where ice appears in winter. If she did not have bottom caviar, then she would freeze into the ice or be carried by currents and die.

The herring, which lives in the Sea of ​​Japan, like cod, avoids excessively chilled waters, but even more does not tolerate high temperatures. Herring is suitable for spawning on the southwestern shores of Sakhalin in April at a water temperature of 0-4°C. The behavior of fattening (fatting) herring in the Tatar Strait is also highly dependent on temperature. In late May - early June, the development of plankton in the southern part of the Tatar Strait reaches its maximum. It is during this period that shoals of herring rush here for fattening.

The choice of places of abundant fishing, as well as the most efficient fishing gear, to a large extent depends on thermal conditions. In relatively cold years, such as 1946 and 1947, shoals of herring stayed close to the coast all summer and were caught with drift nets (Drift (smooth) nets are usually “swept out” at night, they are kept “afloat” and slowly drift along with the current ) and fixed nets, first in the surface, and then in the bottom layers. In relatively warm years (1948 and 1949), the periods of stay of herring near the coast are greatly reduced, and the fish quickly move to the open sea. Drift net fishing near the coast in such years stops by mid-July, and with fixed nets even earlier. Secondarily, herring comes to the shores in autumn, in September - October, when the waters become colder.

As V. G. Bogaevsky showed, the period of stay of herring in the coastal zone also depends on the thickness of the surface layer of water heated above 10 °. The herring avoids this heated layer and stays lower in the lower temperature waters underlying it. Most of all, it accumulates near the coast during strong northeast winds, when heated water is driven away from the coast, and cold deep waters rise to the surface.

With changes in temperature conditions in the Sea of ​​Japan, rare fish that are not an object of fishing may disappear and appear. According to A.I. Rumyantsev, in the summer of 1949, after a 7-8-year break caused by a sharp cooling in 1941-1944, cases of subtropical and tropical fish were again caught in the area of ​​Peter the Great Bay. So, on September 30, 1949, a conger eel was caught in the Ussuri Bay, which lives off the coast of the southern Japanese islands. On the same day, in the Zarubino area, the so-called caragoid fish, common in the tropical latitudes of the Indian and Pacific oceans, was caught. In August of the same year, three specimens of eastern tuna weighing 245, 261 and 336 kg were caught in Peter the Great Bay, and triggerfish, a representative of the subtropics, were caught near Cape Peschany in the Amur Bay. In the same year, a huge inhabitant of tropical waters, the moon-fish, was found in the waters of Primorye. Her weight reached 300 kg.

These finds testify to the general warming of the waters of the Sea of ​​Japan. The same is said by the first centners of sardines caught in our waters in 1954-1955.

Fish industry. Three countries fish in the Sea of ​​Japan: the Soviet Union, Japan and Korea.

The extraction of fish, sea animals and other products of the sea in the Far East has always been extremely important for our country. The share of fishing in the Far Eastern seas in the postwar years ranged from 20 to 36% of the total production of the Soviet Union.

The raw material resources of the Far Eastern seas make it possible to increase production. This primarily applies to saury, pollock, cod and other fish.

Among the Far Eastern seas, the Sea of ​​Japan until 1941 occupied the first place in terms of the number of fish caught due to the high catches of sardines. After the war, the Sea of ​​Japan gave way to the Sea of ​​Okhotsk and the Kamchatka waters of the Pacific Ocean, where salmon, herring and flounder are caught mainly.

Before the war, a small number of fish species were used in the fishery in the Sea of ​​Japan. These included sardine, salmon (chum salmon, pink salmon, sima), herring, cod, flounder and saffron cod (vakhnya). In the post-war years, fishing for mackerel, pollock, greenlings, smelt, etc. was organized.

Mass fishing of mackerel in the waters of Primorye arose only in 1947, and by 1953 its catch reached 183 thousand centners.

Fishing for flounders in Primorye has existed for a long time. Of the 25 species found in the Far Eastern waters, 19 are caught in Peter the Great Bay (according to P. A. Moiseev). The catches are dominated by yellowfin, sharp-headed and small-mouthed flounders.

This fishery is based on their catch during spring migration from wintering areas to the coast and return migration in autumn. Flounders overwinter at significant depths - from 170 to 250 m and even deeper, avoiding coastal freezing temperatures. Most of all, it accumulates on a bank located southeast of about. Askold.

Flounders are distinguished by relatively low mobility. To determine its migrations, in some places, individual fish were tagged and released back into the sea. Further than 17 miles from the release site, none of the tagged flounders was recaptured.

The fishery mastered the accumulations of flounders in the northern part of the Tatar Strait, the catches of which began to increase after the Second World War and reached 100 thousand centners.

In the Sea of ​​Japan, such an important commercial demersal fish as cod and pollock, another representative of the cod family, is underused.

Until 1941, cod was caught in negligible numbers in the Sea of ​​Japan. After the war, its catch increased due to fishing off the southwestern coast of Sakhalin. Like cod fishing, pollock fishing began in the post-war years. Pollock living in near-bottom and intermediate horizons at depths up to 150-200 m is distributed throughout the Sea of ​​Japan, but especially large concentrations of it are formed off the eastern coast of Korea, in the Gulf of Korea. There in 1946-1948. fishing vessels were sent for expedition fishing. Catches reached 5,000 centners per ship. The total catch of pollock in 1948 amounted to 180 thousand centners. Its reserves in the Sea of ​​Japan are very large and allow a significant increase in production.

Herring lives mainly in the northern part of the Sea of ​​Japan and is caught off the coast of Primorye, Hokkaido and South Sakhalin.

Until very recently, mainly spring spawning herring with a low fat content (up to 5-6%) was caught. Until 1945, spawning herring was caught by the Japanese in huge quantities off southwestern Sakhalin. In 1931, the catch reached 5.5 million centners, then it decreased to 1.5-3 million centners per year. Herring spawning near Sakhalin takes place in April. It approaches the shore quickly and in great numbers. Sakhalin herring catches were: in 1946 - 506 thousand centners, in 1947 - 609; in 1948 - 667, in 1949 - 1135 thousand centners, and since 1950 they began to decline sharply connection with the depletion of the Sakhalin-Hokkaido herring stock. In addition to spawning, there is a fishery for feeding herring, excellent in quality, with a fat content of up to 20%. Salmonids (chum salmon, pink salmon, sim) are caught in the rivers of Primorye and the western coast of Sakhalin during their spawning run.

Saury should be attributed to undeveloped, but very promising objects of fishing. Until 1934, it appeared irregularly in the Sea of ​​Japan, and in subsequent years it began to come up for spawning more regularly and abundantly even to our shores. Saury reacts sensitively to electric light, gathers in the lighting zone, where it is successfully caught with lifting nets.

In the Sea of ​​Japan, the fishery of crabs, mollusks (mainly scallops), marine plants (kelp, seaweed, ahnfeltia, zoster) is developed. Medicines are prepared from kelp, and agar is extracted from anfeltia (red algae). Most marine invertebrates and algae are underexploited by fisheries, and their production can be significantly expanded.