Balaena mysticetus (Svalbard-Barents Sea (Spitsbergen) subpopulation)

Subpopulation of Balaena mysticetus Linnaeus, 1758

See also global assessment for this species and subpopulation assessment for the Okhotsk Sea stock.

East coast of Greenland (Denmark) across the Greenland Sea, the Barents Sea, and the Kara Sea to Severnaya Zemlya (Russian Federation), and south at least occasionally to northern Iceland and the coast of Finnmark (Norway) and Jan Mayen (Norway) (Rice 1998).

Pre-whaling subpopulation size:

This subpopulation was originally by far the most abundant of the bowhead whale subpopulations, but was heavily depleted by pre-modern commercial whaling from 1611 to the last recorded capture in 1911 (Ross 1993). The only record of catches by modern whaling refers to four taken by modern whaling near Svalbard in 1932 (Ruud 1937). Based on the catch record, a minimum initial subpopulation size was estimated by Woodby and Botkin (1993) at 24,000 whales. A modeling exercise (Allen and Keay 2006) resulted in an estimate of 52,000 but this may be too high given it assumed a net reproductive rate considerably lower than that currently observed in the Bering-Chukchi-Beaufort Seas subpopulation (see global assessment for this species). 

Current subpopulation size

There is no quantitative estimate of current subpopulation size, but the available evidence suggests that it is small. Jonsgård (1982) reported no live sightings on surveys between Greenland and Svalbard and around Svalbard in 1980, but one dead probable bowhead. Based on post-war sightings of only seven individuals in Norwegian and adjacent waters up to 1990, Christensen et al. (1992) suggested that the subpopulation numbered “in the tens”. However, the Norwegian record may have given a somewhat exaggerated impression of rarity, due to lack of coverage within the pack ice.

Moore and Reeves (1993) list 37 sightings between 1940 and 1990, mainly near Svalbard and Franz Josef Land (Russian Federation). The records include two sightings (Belikov et al. 1989) of apparently quite large winter aggregations near Franz Josef Land in 1981 (“several tens of individuals”) and 1983 (“about 66 animals”). Gilg and Born (2005) list 23 definite and probable sightings off East Greenland during 1940–2004, including a probable sighting of ten individuals in 2003. Seven sightings totalling about 20 individuals were reported in the Greenland Sea in April 2006 (Wiig et al. 2007). While the number of sightings records has increased over time this may reflect increased effort rather than increasing abundance. Among the recently reported observations, no calves or small individuals have been reported. The proportion of the subpopulation that comprises mature animals is unknown. A value of 44% has been estimated for the Bering-Chukchi-Beaufort Seas stock.

The seasonal distribution is strongly influenced by pack ice (Moore and Reeves 1993). During the winter bowhead whales occur in areas near the ice edge, in polynyas, and in areas of unconsolidated pack ice. During the spring these whales use leads and cracks in the ice to penetrate areas that were inaccessible during the winter due to heavy ice coverage. During the summer and autumn they concentrate in areas where zooplankton production is high or where large-scale biophysical processes create local concentrations of calanoid copepods (Finley 1990, Finley et al. 1998).

Small to medium-sized crustaceans, especially krill and copepods, form the bulk of the bowhead's diet (Lowry et al. 2004). They also feed on mysids and gammarid amphipods, and the diet includes at least 60 species. Bowheads skim feed at the surface and feed in the water column. It has recently been suggested that they also feed near the bottom, but probably do not directly ingest sediments as gray whales routinely do.