Солтүстік Мұхиттың Бофорт теңізі

Marginal sea of the Arctic Ocean north of the Northwest Territories, the Yukon, and Alaska

The Beaufort Sea ('/b//oʊ//f//ər//t/; ) is a marginal sea of the Arctic Ocean, located north of the Northwest Territories, Yukon, and Alaska, and west of the Canadian Arctic Archipelago. The sea is named after Sir Francis Beaufort, a hydrographer. Sea ice would often rotate for several years in the Beaufort Gyre, the dominant ocean current of the Beaufort Sea, growing into sturdy and thick multi year ice. Claims that the seacoast was populated about 30,000 years ago have been largely discredited (see below); present population density is very low. The sea contains significant resources of petroleum and natural gas under its shelf, such as the Amauligak field. They were discovered in the period between the 1950s and 1980s, and since the latter part of that period their exploration has become the major human activity in the area. The traditional occupations of fishing and whale and seal hunting are practiced only locally, and have no commercial significance. As a result, the sea hosts one of the largest colonies of beluga whales, and there is no sign of overfishing as of now. To prevent overfishing in its waters, the US adopted a precautionary commercial fisheries management plan in August 2009. In April 2011, the Canadian government signed a memorandum of understanding with the Inuvialuit as a first step in developing a larger ocean management plan. The Canadian government announced in October 2014 that no new commercial fisheries in the Beaufort Sea will be considered until research has shown sustainable stocks that would be made available to Inuvialuit first. The Canadian government designated blocks of the Beaufort Sea as Marine Protected Areas (MPAs). The Anguniaqvia niqiqyuam MPA surrounds the Parry Peninsula in the Amundsen Gulf, and the Tarium Niryutait MPA is located at the Mackenzie River delta and estuary. The protected areas are set to protect species and habitats for the Inuvialuit community.

There is an unresolved dispute involving a wedge shaped slice on the International Boundary in the Beaufort Sea, between the Canadian territory of Yukon and the U. S. state of Alaska. Canada claims the maritime boundary to be along the 141st meridian west out to a distance of , following the Alaska–Yukon land border. This follows the natural prolongation principle, which holds that that a nation's maritime boundary should reflect the 'natural prolongation' of where its land territory reaches the coast. The position of the United States is that the boundary line should be perpendicular to the coast out to a distance of , following a line of equidistance from the coast. The equidistance principle argues that a nation's maritime boundaries should conform to a median line that is equidistant from the shores of neighbouring nations. This difference creates a wedge with an area of about that is claimed by both nations. This dispute has taken on increased significance due to the possible presence of natural reserves within the wedge, which according to Canada's National Energy Board may contain of gas, which would cover the national consumption for 20 years, and more than of oil. Because of this, Canada argues that "special circumstances" apply to this border, a position that the U. S. rejects. On 20 August 2009, United States Secretary of Commerce Gary Locke announced a moratorium on commercial fishing of the Beaufort Sea north of Alaska, including the disputed waters. In July 2010, US–Canada negotiations have started in Ottawa with the next meeting planned in 2011. A joint geological survey of the area has been initiated, and the issue was marked as settled by the CIA World Factbook, though no official document has been released by September 2010.

On August 20, 2009 United States Secretary of Commerce Gary Locke announced a moratorium on fishing the Beaufort Sea north of Alaska. The moratorium was imposed in anticipation that global warming would make those waters accessible to commercial fisheries. The moratorium stirred controversy in Canada because the region where the USA announced the moratorium included a large wedge shaped region of disputed waters.

Several rivers such as the Kongakut River in Alaska and the Firth River in Yukon empty into the Beaufort. The major river to flow into the sea is the Mackenzie, Canada's longest, which empties into the Canadian part of the sea, west of Tuktoyaktuk. The coastal shelf area is rather narrow, especially near and east of Point Barrow in the Alaskan part of the sea, and contains numerous submarine valleys. It becomes wider near the delta of the Mackenzie River but nowhere exceeds Near the coast, the depths are shallower than but they rapidly increase northwards up to a few kilometers, transforming into a massive platform which is geologically similar to that of the oceans. There are many small islands in the sea and in the delta of the Mackenzie River. A few larger ones lie west of the Mackenzie River, such as Herschel Island ( off the shore, area ) and Barter Island ( from the coast, area ). The coasts are low, with the maximum elevations between
The channels of the Mackenzie River thaw earlier, in late May–early June. This thawing increases the average water discharge from about
Hidden changes in the ice cover of the Beaufort Sea were discovered in 2009. Whereas the ice area remain stable, as detected by the observation satellites, so as the associated water temperature and salinity, the ice structure has changed recently. The new ice, called rotten ice, is thinner and much weaker structurally. The sea water has a stable temperature and is separated into four distinct layers as follows. The top are surface water which has a temperature of in summer and in winter. The next layer is formed by the inflows from the Pacific Ocean and Bering Sea coming through the Bering Strait; it extends up to the North Pole. The warmest, deep Atlantic layer has the temperatures between 0 and 1 °C (32 to 34 °F), and water at the bottom is a bit colder at −0.4 to −0.8 °C (31.3 to 30.6 °F). The water currents form the clockwise directed Beaufort Gyre, that results in south westerly and westerly currents near the shores. The Mackenzie River partly affects this circulation inducing minor eastwards streams near its mouth. The river annually brings about 15 million tonnes of sediments which are rich in dolomite and calcium carbonate. Those deposits are spread over the sea and mixed with mud and gravel. The delta of Mackenzie River contains numerous lakes and ponds which are inhabited by muskrat. Major fish species include polar cod (Boreogadus saida), Arctic cod (Arctogadus glacialis), saffron cod (Eleginus gracilis), Arctic char (Salvelinus alpinus), chum salmon (Oncorhynchus keta), Arctic cisco (Coregonus autumnalis), least cisco (Coregonus sardinella), lake whitefish (Coregonus clupeaformis), broad whitefish (Coregonus nasus), Pacific herring (Clupea pallasii), fourhorn sculpin (Myoxocephalus quadricornis), inconnu (Stenodus leucichthys) and flatfish. The eastern part of the sea is a major habitat of beluga whales with an estimated population of 39,000. This population is stable and might even be increasing; it is not affected by the offshore oil exploration in the area. Belugas spend summer in the coastal area and Mackenzie River delta, which are free of ice then, and in winter migrate long distances to the polynyas of the deep sea. Genetic analyses have confirmed that belugas of the Beaufort Sea are clearly distinct from those of other Canadian and Alaskan waters, despite often sharing a common wintering habitat. The food chain of the Beaufort Sea is relatively simple: It starts with phytoplankton and epontic algae (single cell algae associated with the lower interface of sea ice), which provide energy to zooplankton, and epontic and coastal amphipods. The latter serve as a food for seabirds and fish, primarily as polar cod and Arctic char. Polar cod is a major food of Arctic char, beluga, narwhal, seabirds and seals, which are dominated by the bearded seal (Erignatus barbatus) and ringed seal (Pusa hispida). Bearded seal and walrus also feed on benthic invertebrates. On top of the food pyramid stands the polar bear, which feeds primarily on seals, but also on any large marine mammals when it has a chance, such as carcasses and whales trapped in ice fields.

"There is only one proposed Early Entry site in eastern Beringia that still has proponents, Bluefish Caves in the Porcupine River Basin, Yukon Territory, Canada. Claims of great antiquity in the area [e. g., 30kya] have a convoluted history. A caribou tibia flesher, the most diagnostic human implement from the Old Crow basin, had been dated at near 28 kya. When redated using accelerator mass spectrometry (AMS) of small amounts of remnant collagen the bone produced a 1.8 kya date (Yesner 1996b:255)". There is no evidence for anomalous occupation of Beaufort coasts in the context of Arctic cultures generally, including the arrival about 4,000 years ago by Paleo Eskimos such as the Dorset culture, around 1,000 years ago by the Thule and finally by the modern Inuit. From early ages, they practiced fishing – bones of Arctic char were found at the 4,000 years old settlements. While originally they lived nomadic life, later, they started to form permanent settlements. Their population is increasing, but the unemployment rate is relatively high. The major settlements along the Beaufort Sea are Tuktoyaktuk (population 930 in 2009) in Canada and Prudhoe Bay, Alaska. Although Prudhoe Bay is permanently populated by only a few people, there are thousands of contract workers in the area employed on petroleum production at the Prudhoe Bay Oil Field, which is on the coastal lowland known as the North Slope. Artificial islands, such as Endicott and Northstar, have been raised near the shores in 1987 and 2001, respectively. The crude oil is transported through the Trans Alaska Pipeline System to the southern port of Valdez. These activities resulted in dredging of about 46.5 million m3 of sea bottom soil, as well as discharge of drilling muds which contained barite, clay, caustic soda, and heavy metals zinc, copper, lead, chromium, cobalt, nickel, cadmium and mercury. About of oil was produced in 1986. A major gas field, named Taglu Gas Field, was discovered in the Mackenzie River delta in 1971, followed by the Parson Lake field and Niglintgak field. The estimated gas reserves of these fields are , and , respectively. Moreover, further into the sea from the Mackenzie delta lies the Amauligak field. This, the largest known oil deposit of the Beaufort Sea, was discovered in 1984, and is estimated to contain of oil and of gas. The development of these fields is hindered by their remote location. This problem was alleviated for Prudhoe Bay by constructing the Trans Alaska Pipeline, but is limiting regular commercial production at Mackenzie River deposits. However, the project has stalled after that. In July 2017, the U. S. Bureau of Ocean Energy Management approved a plan to allow Eni, an Italian multinational oil and gas company, to drill four oil exploration wells on Spy Island, one of four artificial islands in the Beaufort Sea.

Stan Rogers references the Beaufort Sea in his popular Canadian Folk Song "Northwest Passage".