Early Spring Distribution of Bowhead Whales in the Bering Sea

Brueggeman, John J.

doi:10.2307/3808236

Cited by 16 publications

(12 citation statements)

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“…obs.). Antarctic killer whales were found in ice up to 3/10 coverage, but not in denser pack (Condy, 1977), whereas bowheads are found in up to 7/10 ice (Brueggeman, 1982). Consequently, the ice may provide a refuge for bowheads.…”

Section: Natural Mortalitymentioning

confidence: 99%

Life history of the bowhead whale, Balaena mysticetus (Mammalia: Cetacea)

et al. 1984

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This paper synthesizes data collected from bowhead whales (Balaena mysticetus) landed by Alaskan Eskimos between 1973 and 1982. From these data, and from the literature, length at birth has been estimated to be 4‐4.5 m, length at one year to be 8‐2 m, length at sexual maturity to be 14 m in females, and maximum length to be 20 m. Sexual activity, possibly mating, has been observed in March through May and the length of gestation is estimated to be 13 months. The calving period appears to extend from March through August, with the peak in births occurring in May. Lactation may extend for one year. Evidence has been provided for a pregnancy rate (percentage pregnant in mature female catch) of 015 and it has been suggested that calving occurs every three to six years. Gross annual reproductive rate (based on calf sightings) is estimated to be at least 3–6%. Sources of mortality are discussed. The sex ratio of animals taken by Eskimos is 0.83: 1.00 (females to males) and is not significantly different from unity. Summary The conclusions drawn in each of the preceding sections are likely to be re‐evaluated as more information becomes available. Still, it is suggested that the length at birth is 4–4.5 m, length at one year is 8.2 m, length at sexual maturity is 14 m in females, and the maximum attainable length is 20 m. Conception is most likely to occur in late winter while the whales congregate in Bering Sea polynyas, whereas the peak in calving appears to occur in May. Consequently, it has been hypothesized that the gestation time is greater than one year, but less than two. By analogy with other right whales and sparse data collected, the duration of lactation is assumed to be one year, although this is arguable. The pregnancy rate of mature females, calculated from ovarian data, is 0.15, projecting a calving interval of approximately seven years. The gross annual reproductive rate generated from field data is 3.6–12.4%. The sex ratio of the harvested animals is 0.83: 1.0, and it is assumed that this does not reflect the whole population. Whatever changes are yet to be made in the understanding of the bow‐head life history, all of the traits delineated are consistent with those predicted for slowly reproducing animals, the quintessential K‐strategist. We are most grateful to the scores of field biologists who have helped us count whales and sample those landed by the Eskimos, and who have contributed ideas and enthusiasm. In addition, we thank R. Tarpley for information on ovaries collected in 1982, J. Breiwick for running several sex ratio estimates, and H. Marsh for her generous assistance with the ovarian histology. Under contract to us R. Davis and W. Koski of L.G.L., environmental research associates, provided the photogrammetric measurements. An earlier, less complete version of our paper was submitted in 1982 as an unpublished report (document SC/34/PS1) to the International Whaling Commission, resulting in many valuable comments from members of the Scientific Committee. P. Best, D. Chapman, and an anonymous...

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Section: Natural Mortalitymentioning

confidence: 99%

Life history of the bowhead whale, Balaena mysticetus (Mammalia: Cetacea)

et al. 1984

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“…Bowheads can retreat under the ice when alarmed and reportedly can break ice 30 -60 cm thick by lifting (Marquette, 1986;Würsig and Clark, 1993). They exploit leads through dense ice, but prefer areas of loose ice (30 -50% cover) and open water just beyond, particularly in summer (Braham et al, 1980;Brueggeman, 1982;Reeves and Leatherwood, 1985;Marquette, 1986). Hence, bowheads are highly migratory, forced southward with the advance of the pack ice in the late fall and advancing northward with its retreat in the summer; their annual migrations roughly define the oscillation of the floe edge.…”

Section: Bowhead Distribution and Habitatmentioning

confidence: 99%

A History of Sea Ice in the Canadian Arctic Archipelago Based on Postglacial Remains of the Bowhead Whale (Balaena Mysticetus)

Dyke¹,

Hooper²,

Savelle³

1996

ARCTIC

164

242

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ABSTRACT. The bowhead whale (Balaena mysticetus) is a planktivore of the baleen group of whales adapted to live in the loose edges of the north polar sea ice. Its annual migrations roughly track the advance and retreat of the floe edge. The distribution and radiocarbon ages of bowhead subfossils in the Canadian Arctic Archipelago show that the range of the whale has expanded and contracted abruptly several times over the last 10.5 thousand years (ka). Each expansion or contraction was followed by nearly stable conditions that persisted for millennia.These changes in the geographic range of the bowhead are defined by > 400 radiocarbon dates. The paleo-ranges are the basis for reconstructing summer sea-ice minima. Using this criterion, postglacial time is divided into four intervals: (1) 10.5-8.5 ka B.P.-A large bowhead population extended in the summer all the way to retreating glacier margins and ultimately from the Beaufort Sea to Baffin Bay; meltwater-driven outflows probably cleared the inter-island channels of sea ice; this interval terminated when the present interglacial circulation pattern was established; (2) 8.5-5 ka B.P.-Bowheads were excluded from most of the archipelago because the channels failed to clear of sea ice; summer sea-ice conditions for most of this time were more severe than during historical times; (3) 5-3 ka B.P.-Bowheads reoccupied the central channels of the Arctic Islands, and their range extended beyond historical limits; and (4) 3-0 ka B.P.-Sea ice excluded whales from the central channels, as it does today.This paleoenvironmental record based on bowhead whale distributions is more complex than that revealed in the δ 18O, conductivity or the percent-melt records of the Devon and Agassiz ice cores. A reconciliation of the two data sets may indicate the following general summer climatic conditions: 10-8 ka B.P.-warm summers with maximum postglacial warmth; 8-5 ka B.P.-cool, dry summers; 5-3 ka B.P.-cool, wet summers; 3-0 ka B.P.-cold, dry summers.Key words: bowhead whale, sea ice, ocean currents, climate change RÉSUMÉ. La baleine boréale (Balaena mysticetus) est un planctivore du groupe des baleines à fanons adapté à la vie dans les écotones fluctuants de la banquise polaire septentrionale. Ses migrations annuelles suivent approximativement l'avance et le retrait de la zone de dislocation. La distribution et la datation au radiocarbone de subfossiles de la baleine boréale dans l'archipel canadien Arctique montrent que l'aire de la baleine s'est plusieurs fois étendue et rétrécie soudainement au cours des derniers 10,5 milliers d'années (Ka). Chaque extension ou rétrécissement a été suivi de conditions relativement stables qui ont duré plusieurs millénaires.Ces variations de l'aire géographique de la baleine boréale sont définies par la datation au radiocarbone > 400. Les paléo-aires constituent la base à partir de laquelle on reconstruit les minima de banquise estivale. En se servant de ce critère, on divise le temps postglaciaire en quatre intervalles: 1) de 10,5 à 8,5 Ka BP -En été...

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“…Bowhead whales summer in the Beaufort Sea and migrate through the northern Bering and Chukchi Seas in spring and fall (Braham, 1984;Miller et al, 1986;Moore and Clarke, 1992). They inhabit the Bering Sea from approximately November through April, with considerable temporal and spatial variation in occurrence, likely dependent on pack ice cover (Brueggeman, 1982;Brueggeman et al, 1987). Killer whales frequent the Bering and Southern Chukchi Seas, at least during the summer months, however, two sightings were reported from the Beaufort Sea (Leatherwood et al, 1986;Lowry et al, 1987b).…”

Section: Killer Whale Attacksmentioning

confidence: 99%

Frequency of Killer Whale (Orcinus Orca) Attacks and Ship Collisions Based on Scarring on Bowhead Whales (Balaena Mysticetus) of the Bering-Chukchi-Beaufort Seas Stock

George¹,

Philo²,

Hazard³

et al. 1994

ARCTIC

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ABSTRACT. Bowhead whales of the Bering-Chukchi-Beaufort Seas stock harvested by Alaskan Eskimos were examined for scars from killer whale and ship-collision injuries. We estimated that the frequency of scars from killer whale attacks ranged from 4.1% to 7.9% (depending on our confidence that the whale was properly examined) while about 1% exhibited scars from ship collisions. The frequency of killer whale scars was considerably lower than for bowhead whales of the Davis Strait stock and for other baleen whales where data are available, and was significantly lower (P < 0.05) for whales < 13 m. Patterns for both types of scars were quite similar to those reported for other cetacean species. Spaces between rake marks were within the range of interdental measurements from four killer whale skulls. The occurrence of attempted killer whale predation and ship strikes inferred from scars has not prevented the BCBS stock from increasing.

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Early Spring Distribution of Bowhead Whales in the Bering Sea

Cited by 16 publications

References 0 publications

Life history of the bowhead whale, Balaena mysticetus (Mammalia: Cetacea)

Life history of the bowhead whale, Balaena mysticetus (Mammalia: Cetacea)

A History of Sea Ice in the Canadian Arctic Archipelago Based on Postglacial Remains of the Bowhead Whale (<i>Balaena Mysticetus</i>)

Frequency of Killer Whale (<i>Orcinus Orca</i>) Attacks and Ship Collisions Based on Scarring on Bowhead Whales (<i>Balaena Mysticetus</i>) of the Bering-Chukchi-Beaufort Seas Stock

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