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11. BERING SEA
The portions of Bering Sea here treated include the coast and islands of Alaska northward of the Aleutian Islands. Excepting a few localities, this territory has not been surveyed, and the charts of it are only compilations from various sources, with corrections made from later information received; the charts are necessarily imperfect and must not be followed implicitly, especially when in the vicinity of the coast. Then, too, the currents are much influenced by the winds, and are imperfectly known and difficult to predict, so that positions by dead reckoning are uncertain and safety depends upon constant vigilance.
Northward and eastward of the 100-fathom (183 m) line the waters of Bering Sea shoal gradually to the coast. There are no dangers in the open sea, unless the Pribilof Islands, St. Lawrence Island, St. Matthew Island, King Island, and Diomede Islands be considered as such. These, being volcanic in character and rocky, are generally bold-to, and in approaching them in thick weather the lead cannot be depended upon at all times to keep clear of them. The coast of the mainland from the head of Bristol Bay to St. Michael, including Nunivak Island, is characterized by extensive banks, formed by deposits from the rivers, which extend many miles from shore, in some cases out of sight of land. Some of these shoals are believed to be quite steep-to on their seaward faces, making it unsafe to shoal the water to less than 10 fathoms (18.3 m) when in their vicinity.
In this region, where fog and thick weather are the rule during the season of navigation, safety, when near the coast, depends on the use of the lead, which, on account of the generally regular bottom, will indicate the approach to danger. In general, all the shores of Bering Sea and the Arctic Ocean are shallow, and when coasting it should be observed as a rule to keep the lead going constantly, and when north of St. Michael never to shoal the water to less than 5 fathoms (9.1 m) unless feeling the way in to the land. Between St. Michael and the head of Bristol Bay the water should not be shoaled to less than 10 fathoms (18.3 m) under the same conditions.
There are few aids to navigation. All of the rocky islands and rocky cliffs of the mainland are frequented by thousands of birds, whose numbers, constant cries, and flight may serve to indicate the approach to shore at these places in thick weather.
The coast of Alaska from the head of Bristol Bay to Point Barrow and eastward has driftwood, which is brought down from the interior by the rivers and carried by the northerly currents of the sea. Good water can always be found in the vicinity of highland. Salmon are plentiful during the open season in all the streams as far north as Kotzebue Sound, and cod are plentiful in the vicinity of the passes and in Bristol Bay.
Ice.-Except in bays and sheltered places, the ice of Bering Sea is detached fields, floes, and cakes, which are continually kept in motion, breaking up, piling, and telescoping by the action of variable winds and currents. At no time is the sea one solid sheet of ice, and in the winter, while it is forming, it is more scattered than in the spring, when the northerly movement has begun and it packs closer together. The general southern limit of ice is from Bristol Bay to the vicinity of St. George Island, and thence about west-northwest to the Siberian shore. The southern edge is ragged and very much scattered, and continued northerly winds sometimes drive fields of it far southward. As a rule, no heavy ice will be encountered south of the Pribilof Islands, and the ice in their vicinity is likely to be nothing more than detached fields.
During the winter of 1923-24 continued northerly winds drove the ice into Isanotski Strait, completely blocking the strait and closing it to navigation for a short period. During the following spring a steamer bound south from Nome was impeded by ice during the latter part of June.
In December 1918 a steamer succeeded in reaching the Pribilof Islands with cargo, which was discharged after much delay. A small cargo of seal skins and products was loaded for the return trip.
In February 1929 the Coast Guard cutter Chelan made the voyage from Unalaska to Pribilof Islands and return without encountering ice. While such freedom from ice is certainly unusual, these instances indicate the extreme conditions that may obtain during a mild winter.
The ice conditions in Bristol Bay have so far received little notice. Reports have been received that the bay is usually free from heavy ice between the middle of May and June 10. In 1899 the steamer Jeanie, of 1,000 tons and a draft of 18 feet (5.5 m) reached Clark Point, in Nushagak River, on April 4 and was discharged on April 15. At this time the ice in the river above Fort Alexander remained solid, but two weeks afterwards it broke up and came down the river in large pieces, which would have endangered any vessel at anchor. In approaching the Nushagak River some ice was encountered about 75 miles from Cape Constantine, but not sufficient to seriously interfere with navigation. On May 10, 1896, a vessel bound for Bristol Bay was brought up by the ice, which extended from Port Moller to St. George Island, and she was not able to reach the Nushagak River until 30 days later. It is within reason to believe that some years Bristol Bay is open to navigation all winter, though the rivers and sheltered bays are closed.
The information regarding ice conditions in Kuskokwim Bay and River is very meager. In general, however, this region may be expected to be clear of ice about June 1.
In 1925 the ice on the river broke on May 23 and went out at Eek Island on May 29. On June 5 large pieces of ice were encountered just below the mouth of the river. Local residents stated that this was the latest the river has been clear of ice for the last 15 years. See also page 404.
In the spring, beginning with April, there is a general northward movement of the ice, the shores clearing ahead of the center of the sea; but it sometimes hangs in the bays and around the islands later than in the open sea. Seasons vary, the movement and position of the ice depending greatly on the direction of the winds. Generally, however, by June 1 the whole body of ice is well up with St. Lawrence Island, and a passage opens to its west side. The eastern side of the sea is likely to be obstructed a little later than the western side, and ice is often met between St. Lawrence Island and Nunivak Island in the early part of June. The breaking out of the rivers toward the latter part of May clears the shores, but the ice is likely to hold in Norton Sound several weeks later.
In general, for a vessel not fitted to encounter ice, Norton Sound is not navigable before the middle of June, often not before June 20 to 25, and has been known to be as late as July 10. On entering the sound about this time, strips of ice are often encountered after the sound can be said to be navigable. From the deck these may appear extensive and solid, but from aloft clear water may be seen beyond and through them. At the opening of navigation the ice is likely to be heaviest and to remain longest on the north shore, and, in general, it is the last of June before that part of the sound is altogether clear.
In the fall young ice begins to form on the rivers, and in the bays and sheltered place after October 1, and grows stronger and spreads according to the severity of the advancing season. Navigation is considered unsafe in Norton Sound after October 15.
CURRENTS, Bering Sea.There has been no systematic study of the currents of the Bering Sea, and the almost constant fogs prevent the navigator from adding much to our meager knowledge concerning them.
Most reports indicate that during the open season there is a general drift northward along the Bering Sea coast and thence through Bering Strait into the Arctic Ocean. But during the winter ice moves from the Arctic into the Bering Sea.
The northward drift is probably not more than 12 knot in places well northward of the Aleutian Island passes; the flow increases off the Yukon Delta and attains a more or less constant strength of 1 to 2 knots through Bering Strait. The effects of wind and atmospheric pressure are said to materially affect or blot out this condition at times. The current in the locality of a disturbed area will generally set with a strong wind or toward an atmospheric depression, and such current may prove of value as a storm warning.
Strong tidal currents flow alternately in both directions through the eastern Aleutian Island passes (p. 303) and probably through the entire Aleutian chain. Tidal effects on currents are also felt in the bays, sounds, and in the vicinity of islands of Bering Sea, see below.
The following observations apply to the season of navigation in Bering Sea :
Between St. Matthew and Nunivak Islands the set of the irre is northward ; with prevailing northeast winds it sets northwest, and with northwest and southwest winds, northeast. This northerly current continues and increases between St. Lawrence Island and the mainland, being stronger toward the mainland north of the mouth of the Yukon River, where it amounts to about 1 knot, except in the early summer, when, increased by the freshets in the Yukon, it may amount to 2 knots or more. A strong northward current setting on the Yukon flats has been observed, amounting at times to 242 knots. The current sets north across Norton Sound to Sledge Island and then follows the coast to Bering Strait. It is strongly marked between Sledge Island and Bering Strait.
In Bering Strait the current sets north, and when not influenced by wind its velocity is from 1 to 2 knots. Protracted northerly gales which prevail in the autumn change its direction to southward, but on the cessation of the wind, it quickly set north again. Strong southerly gales increase its velocity to 3 knots. The current is stronger east of the Diomede Islands than west of them.
Captain Covell, of the Coast Guard cutter Bear, makes the following remarks concerning currents in this locality: “After a southeast gale in the Bering Sea, during which the water is banked up against Siberia, a very marked current sets in the opposite direction. The reverse is true for a southwest gale. The exact interval between the gale and the strong countercurrent is, so far, undetermined. Of the existence of this countercurrent under such conditions, there is no doubt, and it demands consideration.” A current sets strongly from Cape Newenham through Etolin Strait.
Tidal currents. In the southern part of Bering Sea, inside the 100-fathom (183 m) line, and through the various passes in the Aleutian Islands, the tidal current sets northward or northeastward on the flood, and southward or southwestward on the ebb. In some of the passes it sometimes has a velocity of 9 knots; when clear of the passes its maximum velocity is about 212 knots. At the Pribilof Islands, Nunivak, St. Matthew, and St. Lawrence Islands the tidal currents have considerable velocity. The flood current sets eastward and northward and the ebb westward and southward. In Bristol Bay the tidal currents have considerable velocity. They have also considerable velocity at the Kuskokwim River and north to the mouth of the Yukon, especially in Etolin Strait and about Cape Vancouver.
The currents of Bristol Bay are usually considered as partly tidal. A northeast storm disguises all other effects and causes a strong current to sweep out of the bay. In normal weather the tidal currents set on and offshore and more or less in and out of the bay, and become more important as the water shoals; the local effects in places are pronounced. Beside the tidal currents, it is considered that Bristol Bay forms the eastern side of a permanent eddy which enters past Cape Newenham flowing eastward and discharges along the north shore of Unimak Island flowing westward. Northward of Unimak Pass it is generally found that there is some current flowing northwestward, which is considered a part of the general northward drift in the Bering Sea.
Fog is most prevalent during spring, summer, and early fall, and it generally begins to clear about the middle of October. In summer fog is almost continuous, but few days are clear from morning to night, and the tops of the mountains can seldom be seen. At the surface of the water it is generally sufficiently clear to make out the shore at a distance of 3 or 4 miles, but at times it is so thick that nothing can be made out, and under such conditions strangers should not attempt to make the land. During the summer months the mist, accompanying southeasterly winds, and fog accompanying southwesterly winds, are considered to be worse on the south side of the Aleutian Islands than on the north side in their immediate vicinity. See remarks on weather, Aleutian Islands, page 306.
It is reported that summer fogs in Bering Sea, while sometimes very dense, often extend less than 100 feet (30 m) above the water. It is, therefore, often possible to make a landfall by sending a man aloft where he will be able to look over the fog. It is also often possible to make high islands and capes by working up to them from leeward and taking advantage of a rift in the fog that prevails to leeward of such features. This rift in the fog is called the “Ookah” by the
natives. It does not exist in the lee of lowland, small islands, or during a calm.
Weather.—The most striking feature about the weather in Bering Sea is its great uncertainty throughout the year. Good weather is rare and not lasting, and the winds cannot be depended upon to remain long in one quarter. The late spring and summer are mild and very foggy, with frequent periods of light weather, comparatively few strong winds, and considerable rain. After September 1 gales become frequent and heavy, fogs gradually lessen, and toward the latter part of the month snow often accompanies the storms. During all the fall, gales are frequent, violent, and from almost any quarter.
During the fall and winter there are often periods of very low barometer (readings below 29.00 being common) accompanied by moderate to strong gales, with rain or snow. These gales, though sometimes very severe, are usually not so strong as would be expected by the fall of the barometer. After December and continuing into the spring there are often periods of moderate weather, and while severe gales occur, they are less frequent than in the fall. Strong winds or gales from any quarter always bring thick weather, rain, or snow. With easterly or southerly winds the rain is continuous, while with westerly or northerly winds the rain or snow occurs at intervals in squalls, and when the wind subsides the weather is likely to be clear.
Southeast gales, with falling barometer and rising temperature, are almost invariably preceded by an unusual clearness of the air; cirrus clouds are seen southwestward, which gradually thicken and overspread the sky. The wind usually shifts to southwestward when the barometer ceases to fall, but it sometimes backs from southeast to northeast, and generally goes to northwest before subsiding. Upon abating, the gale is followed by light westerly winds and comparalively clear weather.
BRISTOL BAY (chart 8802) may be said to include all that part of Bering Sea lying east of a line drawn from Cape Sarichef, Unimak Island, to the Kuskokwim River. Unimak Island and the Alaska Peninsula bound it on the south and east, and separate it from the Pacific Ocean. The Naknek River is at the head of deep-water navigation, while the bay itself terminates in the Kvichak River a few miles northward. The region about Nushagak River, Kulukak Bay, and the Kuskokwim forms its northwest boundary.
The shores are usually low and without distinctive features, but high mountain ranges and volcanic cones extend along the central parts of Unimak Island and the Alaska Peninsula. These rugged snow-covered mountains and lofty peaks would serve as unmistakable landmarks were they not obscured by the almost constant fogs which prevail in that region during the summer months. The shore and objects near the sea level are often seen beneath the fog when the higher lands are obscured, and, therefore, most of the available landmarks are found on or near the beach.
With the exception of Nushagak Bay, Bristol Bay is unsurveyed, and little detailed information is available. The chart is compiled from reports and reconnaissance surveys, some of which were made