BOWHEAD WHALES ALONG THE CHUKOTKA COAST IN AUTUMN

Citation
Se. Moore et al., BOWHEAD WHALES ALONG THE CHUKOTKA COAST IN AUTUMN, Arctic, 48(2), 1995, pp. 155-160
Citations number
26
Categorie Soggetti
Geografhy,"Multidisciplinary Sciences
Journal title
ArcticACNP
ISSN journal
00040843
Volume
48
Issue
2
Year of publication
1995
Pages
155 - 160
Database
ISI
SICI code
0004-0843(1995)48:2<155:BWATCC>2.0.ZU;2-G
Abstract
Bowhead whales (Balaena mysticetus) were seen in autumn 1992 and 1993 only along the northern coast of Chukotka, Russia, although an extensi ve area of the Chukchi Sea was searched during ship cruises. Single-da y counts of 76 and 50 bowheads were made on 1 October 1992 and 3 Octob er 1993, respectively, with only a few whales seen on other days. Whal es seen between Cape Schmidt and Cape Vankarem on 1 October 1992 appea red to be feeding, but there was no means to detect or sample subsurfa ce forage that year. On 3 October 1993, bowheads appeared to be feedin g in an area where a 5 m x 8 km patch of zooplankton was identified, v ia acoustics, at 25-30 m in water 35 m deep. A vertical-tow sample nea r the patch indicated the euphausiid Thysanoessa rachii, a common bowh ead prey species, was abundant in the water column. The location of th e zooplankton patch corresponded with a sharp salinity (proxy density) gradient. In addition, whale distribution coincided with a surface th ermal boundary, identified by satellite-borne Advanced Very High Resol ution Radiometer (AVHRR) imagery. The confinement of bowhead sightings to the northern coast of Chukotka in 1992-93 corresponds to reports f rom autumn surveys in 1979, 1980 and 1990, while the association of wh ales with physical oceanographic fronts is similar to findings from a study of bowhead feeding areas in the southern Beaufort Sea. These obs ervations suggest that the Chukotka coast may be an important feeding or staging area for the Bering Sea stock and that oceanographic patter ns influencing whale occurrence may be identifiable from standard ocea nographic measurements.