Opportunistic reconnaissance aerial surveys of Lancaster Sound, Barrow Strait, Peel Sound, and Prince Regent Inlet were conducted between 1974 and 1982 to determine the distribution and abundance of belugas, Delphinapterus leucas, and narwhals, Monodon monoceros. In 1981, two stratified strip-transect surveys were flown. From these we estimate that a total of 6300 – 18 600 belugas and approximately 13 200 –18 000 narwhals summer in Lancaster Sound and adjoining waterways. Improvement in the precision of these estimates would require a substantial increase in survey coverage and may not be justified considering the significant increase in costs. Our review of the results of surveys conducted since 1975 in the same study area, of which most of the information is not yet available in the scientific literature, shows much duplication of effort, little increase in information, and a lack of confidence limits for the estimated numbers.

ABSTRACT. Three adult and three juvenile belugas were fitted with satellite-linked radio tags in eastern Hudson Bay in midAugust 1993, and one adult was tagged in mid-October 1995 in extreme northeastern Hudson Bay. The tags transmitted data on dive behaviour, and the receiving satellite calculated positions by Doppler-shift triangulation. The belugas tagged in summer in eastern Hudson Bay made no directed or long-distance movements while the tags were attached. Their range did not include the Belcher Islands, and belugas observed in aerial surveys of those islands do not appear to belong to the eastern coastal stock. The single beluga tagged in northern Quebec in October moved into the deep water of western Hudson Strait and travelled east along the southern coast of Hudson Strait, slowing up on reaching shallower water off Salluit and near Charles Island. This whale was still off Salluit when the tag stopped transmitting.All the tagged belugas dived intensively while the tags were attached, although there were individual differences, some belugas diving noticeably less than others. Dive behaviour varied over time, with periods lasting several days of concentrated diving interspersed with periods of less intense diving. 'Intense' periods entailed diving for up to 80% of the time. All belugas, even the one that was in deep water in Hudson Strait, showed dive depth characteristics that were consistent with diving usually to the bottom. However, all belugas always-even in deep water-made dives that usually lasted less than 10 min and very seldom lasted more than 12 min. Belugas tagged as pairs of adults and young showed striking correlations of dive behaviour. The data obtained indicate that it would be appropriate to correct aerial surveys by adding 85% to aerial counts.Key words: beluga, Delphinapterus leucas, dive behaviour, migration, movement, Hudson Bay, Hudson Strait, visibility, dive speed RÉSUMÉ. Mi-août 1993, on a équipé trois bélougas adultes et trois bélougas juvéniles de radio-émetteurs en liaison avec un satellite dans l'est de la baie d'Hudson et mi-octobre 1995 on a équipé un adulte aux confins nord-est de la baie d'Hudson. Les émetteurs ont transmis des données sur le comportement en plongée, et le satellite récepteur a calculé les positions par triangulation de décalage Doppler. Les bélougas équipés en été dans l'est de la baie d'Hudson ne se sont pas déplacés vers un endroit particulier ou sur une longue distance pendant que les émetteurs étaient fixés. Leur territoire ne comprenait pas les îles Belcher, et les bélougas observés lors de survols aériens effectués sur ces îles ne semblent pas appartenir au stock côtier oriental. Le seul bélouga équipé en octobre dans le nord du Québec s'est rendu dans les eaux profondes du détroit d'Hudson occidental dont il a longé la côte méridionale vers l'est, ralentissant au niveau des eaux moins profondes au large de Salluit et près de l'île Charles. Cette baleine était toujours au large de Salluit quand l'émetteur a cessé de fonctionner. Tous les bélougas é...

Seven sightings in which mature belugas were seen to persist in carrying inanimate objects leads us to the hypothesis that this might be surrogate behaviour in response to perinatal mortality. The long period of dependence by the calf on its mother would indicate a strong mother–calf bond in this species, which might lead to such an extreme manifestation of protective behaviour.

No abstract