Highly mobile large-bodied organisms are adapted to seasonal variation associated with polar environments. We used satellite tracking data from 27 bowhead whales Balaena mysticetus of the Eastern Canada-West Greenland population to test for movement and habitat selection of the highly variable sea ice landscape that encompasses near-complete coverage in winter to nearcomplete absence in summer. We demarcated 2 bowhead whale seasons based on movement behaviour identified from inflection points of polynomial regression analysis of movement rate: winter (28 December to 15 March, 16.6 ± 2.65 km d ). Resource selection functions were used to evaluate bowhead whale seasonal selection of sea ice landscape (coverage, thickness, and floe size). Movement and habitat use differed between Nunavut tagging sites likely as a consequence of sexual and reproductive segregation. Whales selected relatively low ice coverage, thin ice, and small floe areas in winter close to the maximum ice extent, presumably to reduce risk of ice entrapment while remaining within ice. In contrast, whales selected high ice coverage, thick ice, and large floe size areas in summer, presumably to reduce risk of killer whale predation while providing enriched feeding opportunities. Our results indicate that this largebodied animal can moderate use of the large-scale fluctuations in seasonal sea ice typical of polar environments.

Nine bowhead whales (Balaena mysticetus) were instrumented with satellite transmitters in West Greenland in May 2002 and 2003. Transmitters were either encased in steel cans or imbedded in floats attached to wires. Transmitters mounted in steel cans had a high initial failure rate, yet those that were successful provided tracking durations up to seven months. Float tags had a low initial failure rate and initially provided large numbers of positions; however, they had deployment durations of only 2–33 d. All tracked whales departed from West Greenland and headed northwest towards Lancaster Sound in the end of May. Three tags with long tracking durations (197–217 d) recorded movements of whales (1 ♂, 2 ♀) into December in 2002 and 2003. All of these individuals remained within the Canadian High Arctic or along the east coast of Baffin Island in summer and early fall. By the end of October, all three whales moved rapidly south along the east coast of Baffin Island and entered Hudson Strait, an apparent wintering ground for the population. One of the whales did not visit Isabella Bay on east Baffin Island, the locality used for abundance estimation from photographic reidentification of individuals. The movements of whales tagged in this study raise critical questions about the assumed stock discreteness of bowhead whales in Foxe Basin, Hudson Strait, and Davis Strait and indicate current estimates of abundance are negatively biased.

Five bowhead whales (Balaena mysticetus) were instrumented with satellite transmitters in northwestern Disko Bay, West Greenland, in May 2001. Best results were obtained when tags were deployed with a pole rather than a pneumatic gun. At least three of the tagged whales remained in the northwestern part of the bay for one to two weeks after tagging. A male and a female whale moved from Disko Bay to northern Canada. They left Disko Bay 11 days apart and took different routes across Baffin Bay to the southern part of the North Water polynya, just east of the entrance to Lancaster Sound. The whales crossed the central part of Baffin Bay relatively rapidly (travel time of 9-10 days, 3.1 and 4.5 km/h). Dive behaviour of one whale was monitored and showed changes in dive depths, dive rates, and surfacing times in different localities, indicating behavioural changes probably related to feeding. The whales were presumably feeding in both Disko Bay in May and in the southern part of the North Water (southeast of Bylot Island) in June. This study confirms whalers' observations that bowhead whales move between West Greenland and the east coast of Baffin Island.

Skin biopsy samples from 806 bowhead whales Balaena mysticetus collected between 1995 and 2010 at 4 locations in Nunavut, Canada, and at 1 locality in West Greenland were used for determination of sex and sexual segregation of bowhead whales in the Baffin Bay stock. There was a significant dominance of females in the Disko Bay samples (78%), whereas the sex ratio in aggregations in Nunavut was not significantly different from 50:50. Data on the body length of whales suggest that primarily large mature whales without calves occupy Disko Bay, whereas primarily mothercalf pairs are found in Foxe Basin. On a broader scale, Baffin Bay is more widely used by adult males and resting or pregnant females from Disko Bay, while Prince Regent, Gulf of Boothia, Foxe Basin, and northwestern Hudson Bay are also used by nursing females, calves, and sub-adults. The most parsimonious explanation for the large-scale spatial segregation of sexes in bowhead whales is that mature females without calves utilize Disko Bay as a foraging ground during certain parts of their reproductive cycle. Acoustic recordings of singing males indicate that Disko Bay may also be a mating ground, where some males may be following estrous females into the bay.

Surveys of belugas were flown during March 1993 in Lancaster Sound and the North Water of Baffin Bay. Most belugas were observed along the shore leads off southeastern Devon Island and in the polynya at the mouth of Jones Sound. Our results confirm other published winter observations that belugas regularly occupy the North Water's leads and polynyas in winter. Walruses, narwhals, and bowhead whales were also seen during these surveys; their presence confirms the use of the North Water wintering area by several other marine mammal species.