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Japan Sea and Okhotsk Sea

The Japan Sea is a marginal sea located in the western Pacific Ocean nearly entirely enclosed by Asian mainland and offshore islands. (Photo: Nasa, SeaWiFS, 30.04.1999)

The Japan Sea is a marginal sea located in the western Pacific Ocean nearly entirely enclosed by Asian mainland and offshore islands. The Japan Sea has a lively seafloor structured by different basins, rises and seamounts. Geologically, the Japan Sea represents a back-arc basin between the Asian mainland and the island-arc of Japan created by subduction volcanism.

 

The Japan Sea is connected by the Korea Strait to the East China Sea in the south, by the La Pérouse Strait to the Okhotsk Sea in the north, and to the Pacific Ocean in the east via narrow passages in the Japan island chain. Prominent circulation features in the Japan Sea include different warm currents from the south and cold currents from the north. The warm Japan Current flowing northeastwards through the sea modifies the regional climate thereby making Vladivostok the only ice-free port of Pacific Russia

 

The climate of the Japan Sea varies form subtropical in the south to sub Arctic/Arctic conditions in the north. Parts of the northern sea area are temporarily ice-covered during winter.

 

In respect to the large number of animal and plant species, the Sea of Japan is Russia’s richest body of water. Due to the wide temperature range, living conditions in the sea are suitable for subtropical fauna and even Arctic species. Besides many different algae and sea grasses, numerous fish and shrimp species occur year round. The best known species is the Kamchatka crab with a leg span of as much as 150 centimeters and a mean weight of 7 kilogram. Starfish and sea urchins as well as oysters and mussels complete the rich fauna.

 

Among over 360 fish species, herring is an important commercial factor and sardine places second in the catches of the Russian fishery fleet. The most valuable commercial fishing and cultivation project in the Japan Sea is that of the Japan Sea pecten (a mussel). Further commercial marine species include octopus and squid.

 

The former Soviet Union dumped radioactive waste in the Sea of Japan from the 1950s until the early 1990s. Faced by strong resentment through Japan, the United States and other countries, the Russian government announced that it would suspend the dumping since the Sea of Japan is a fertile fishing ground for surrounding countries including Russia itself.

 

 

The Okhotsk Sea is a semi-enclosed sub Arctic sea located in the northwestern Pacific Ocean between the Siberian mainland in the west and Kamchatka Peninsula to the east. (Photo: Nasa, SeaWiFS, 18.06.1999)

The Okhotsk Sea

 

The Okhotsk Sea is a semi-enclosed sub Arctic sea located in the northwestern Pacific Ocean between the Siberian mainland in the west and Kamchatka Peninsula to the east. Via the sounds between the Kuril Islands the Okhotsk Sea is connected to the Pacific Ocean. Different straits link the Okhotsk Sea to the Japan Sea. The shallow Okhotsk shelf spreads far out into the sea, which then steeply deepens to the Kuril basin in the south.

 

The most prominent surface circulation feature is the Soya Current, an extension of the Tsushima Current that flows through the southern part of the Okhotsk Sea. The shear between this current and the calmer coastal waters frequently produces eddies of around 10 to 50 kilometers in diameter. The Okhotsk Sea is a region of large tidal sea level oscillations and strong tidal currents.

 

The climate of the Okhotsk Sea differs only little from Arctic conditions. From October to April, the region is influenced by very cold and dry northerly Monsoon winds. During this period, the Sea of Okhotsk is generally almost entirely covered with sea ice. Freezing starts in coastal areas and a closed fast ice cover develops within few weeks. Offshore winds generate polynyas and flaw leads producing large amounts of frazil ice, which consolidate to drifting floes (for more see: Laptev Sea).

 

Due to the convergence of nutrient-rich cold and warm currents, the southern Kuril coastal waters are some of the richest in the World. Economically valuable fish include pollock, cod, mackerel, flounder, halibut and salmon. Other fish species like tuna and sardines migrate northward from subtropical waters. Most of the migration routes for salmon pass through the southern Kuril Islands. More species of economic value are crabs, shrimps, sea urchins, squid, sea slug and scallop.

 

Coastal and marine ecosystems make up to 10 per cent of the preserved territories. Otters and seals inhabit the coastal regions of the Okhotsk Sea, hauling out on protected shores to breed. One of Kamchatka’s largest breeding grounds for seals is safeguarded. Nine rare species of whales inhabit the seas, as well as the only population of sea otters found in the western Pacific. The sea otter's thick fur keeps them warm even in the icy waters during winter.

 

Few of the most serious present threats to the natural system of the Okhotsk Sea include extensive timber harvesting in the coniferous forests of Kamchatka river valleys and industrial fishing or hunt for rare species of marine mammals like seals, sea otter and whales in coastal waters. Regular ranger patrols, the creation of a coastal buffer zone and scientific monitoring help to improve protection of the endangered ecosystems.

 

 

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