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Bowhead Whales

Balaena mysticetus

Description
Habitat and Range
Life History
Relationships with People
Population Status
Ecological Concerns

Bowheads evidently sense their surroundings mainly by sound, which travels five times faster and much farther in water than in air. Sounds produced by the environment or by the whales reverberate differently under different ice conditions. Bowheads are excellent navigators of ice-choked waters, although they sometimes get trapped by ice and drown. Bowheads make a wide variety of sounds with a voice covering seven octaves. Like humpbacks, they may "sing" in deep undulating tones, often with two notes at once. During migration they evidently call not only to help navigate but also to maintain cohesion of small herds dispersed over perhaps a half dozen square miles.

Females probably become sexually mature at 10 to 15 years of age, there after giving birth every three to four years. A single calf is born during spring migration following a pregnancy of about one year.

Other than people, the bowheads' only natural enemies are killer whales (Orcas). When threatened the unaggressive bowhead dives and, when possible, retreats under the ice.

It is likely the villagers exploited a distinct stock of bowheads which summered along the Chukotkan coast of the Bering and Chukchi seas. But Chukotkan Native whaling ended early in this century after the stock was apparently exterminated by commercial whalers. Now the bowhead is hunted only by Alaskan Eskimos from nine villages extending from St. Lawrence Island in the Bering Sea to Barter Island in the Beaufort Sea. Most hunting is done from walrus-skin covered open boats called umiaks.

The culture and social structure of Eskimo villages centered around the whale hunt, and still does to an important degree. Whaling captains are typically village leaders. Landing a whale may be the biggest community event of the year, with everyone helping to beach it, followed by an elaborate process of butchering, sharing, celebrating, and preparing for next year's hunt.

In 1848 Captain Thomas Roys' successful exploratory hunt in the Bering Sea touched off six decades of whaling during which more than 18,000 bowheads are estimated to have been killed and the population drastically reduced. At first whalers operated during summer near the Chukotka coast of the Bering Sea and in the Chukchi Sea. As whale numbers declined, explorations into the Beaufort Sea found more whales to exploit. The whaling industry expanded the industrial revolution into remote waters. It nearly eliminated not only the whales but also for a time, walruses. Whaling ended about 1910 because of market changes. In the 1930's bowheads came under protection of the International Convention for the Regulation of Whaling, and, in the 1970's, of the US Marine Mammal and Endangered Species acts.

Improved censusing methods soon boosted the bowhead population estimate to 3,800. In the 1980's federal funding was cut for research but the North Slope Borough, representing its Eskimo inhabitants, funded continued studies. With the addition of acoustic methods the 1986 population estimate was boosted to 7,800 (range of 5,700-10,600). The Eskimo quota was correspondingly increased. In line with an anthropological study indicating a current need for 41 whales, the quota was raised in 1992 to 41, or a maximum of 53 whales struck.

Offshore oil exploration is occurring in the Beaufort and Chukchi seas, and may soon begin in the Gulf of Anadyr. Research is addressing the effects of these activities on bowheads. Does increased background noise interfere with whales' ability to hear other sounds? Do whales react to noises in key areas by abandoning them? Whales avoid loud sounds from vessels and seismic research, moving away when noise sources are as far as 25 miles distant. There were indications of reduced bowhead use of the Canadian Beaufort area where oil exploration was active.

Although whales as a group may be less affected by oil than some other marine mammals, bowheads run special risks because oil spilled in polar regions tends to accumulate at the ice edges, the preferred habitat of these whales. One of their primary feeding methods involves skimming the water, often at the surface, making them more likely to ingest oil.

An even greater threat than oil may be synthetic toxins, for example chlorine compounds like DDT and PCB'S, which tend to accumulate in ecosystems for long periods and resist breaking down. High levels of these compounds have been found in the blubber of several whale species. Although the detrimental effects of chlorine compounds on whales has not been proven, birth abnormalities have been reported in seals in association with high levels of these chemicals.

A recent study by the National Marine Fisheries Service concluded that the Beringian bowhead stock was increasing. However, because of uncertainty about the potential effects of industrial development in the Arctic, and because this stock represents over 90 percent of the remaining world population, continued protection under the US Endangered Species Act has been recommended, with a listing as "threat ened" rather than "endangered." For now bowheads remain a powerful presence in Beringian seas.