Barents Sea (BS)

An new aerial line transect survey was carried out in 2015 in the entire area, however not covering Russian areas. Likely stable since 2004.

Status table outtake

Subpopulation size Subpopulation trend Sea ice metrics 1979-2018 Human-caused removals 2013/2014–2017/2018
Estimate and uncertainity Method and type of evidence Year and citation Long term (approx 3 generations) Short term (approx 1 generation) Change in date of spring ice retreat / fall ice advance (days per decade) Change in summer sea ice area (percent change per decade) 5-year mean
Quota (bears per year) Actual (% of total population)
2644
1899-3592
Distance sampling2004Data deficientLikely stable (2004 to 2015)-16.0/25.2-19.6N/A 
See also the complete table (all subpopulations)

Comments, vulnerabilities and concerns

There has been no legal hunting of polar bears in Russia since 1957 and in Norway since 1973. Recent habitat decline has led to late sea ice formation in autumn around some important denning habitat, in such years few females den in these areas. Den distribution may have shifted from E Svalbard to Franz Josef Land in most years. In 2015, the Norwegain part was surveyed. It was indicated that number of local bears in Svalbard was similar to in 2004, and that more bears were up in the pack ice. Possibly, bears could have shifted westward from Russian to Norwegian area in the pack, thus an increase is not conclusive over the last generation. No evidence of large scale reduction in body condition.

Status and delineation

Barents Sea subpopulation mapThe Barents Sea area. See also the complete map (all subpopulations).

The size of the Barents Sea subpopulation was estimated to be 2,650 (95% CI, 1900 – 3600) in August 2004, using mark-recapture distance-sampling (MRDS) with data collected from aerial surveys (Aars et al. 2009). This analysis suggests that earlier estimates based on den counts and ship surveys (Larsen 1972) may have been too high. Ecological data supports that BS grew steadily during the first decade after all hunting ceased in 1973, and then either continued to grow or stabilized. A new survey in the Norwegian extent of BS was conducted in August 2015. The ice edge was located beyond an ice-free gap north of the Svalbard Archipelago. The number of bears encountered in Svalbard indicates that there is a local stock of ~200-300 bears (preliminary results), which did not differ much from the number detected in 2004. The results (J. Aars et al., in prep.) also indicate, in accordance with the results from 2004, that more bears are off-shore in the pack ice in autumn. The total estimated for Norwegian Arctic was just under 1000 bears, considerably higher than the total for the Norwegian side in 2004, but with a confidence interval overlapping with the earlier estimate. During the new survey, the distribution of bears was clumped along the ice edge with most bears close to the Russian border, but access to the Russian portion of BS, for aerial survey, was not permitted. Because of the overlapping confidence intervals, it cannot be concluded that the BS subpopulation has grown.

It is believed that excess hunting in the area before 1973 led to a population size far below the carrying capacity. Consequently, it could be that the current population size is still lower because of an ongoing decline in, carrying capacity. Thus, it is unclear what the trajectory of the subpopulation will be in near future; we do expect that habitat loss will continue. There have not been any dramatic time trends in reproduction or condition parameters in BS, although poor ice years seem to influence these parameters.

Subpopulation boundaries based on satellite telemetry data indicate that BS is a natural subpopulation unit, albeit with some overlap to the east with the Kara Sea (KS) subpopulation (Mauritzen et al. 2002). Overlap between BS and the East Greenland (EG) subpopulation may be limited (Born et al. 1997), although to some degree home ranges of bears from the EG overlap with those of bears from Svalbard in Fram Strait (Born et al. 2012). Genetically, polar bears from BS are similar to those in the EG, KS, and Laptev Sea (LP) subpopulations (Paetkau et al. 1999, Peacock et al. 2015). At a global level, polar bears in BS belong to the Eastern Polar Basin genetic cluster (one of four global genetic clusters); substantial directional gene flow occurs from the Eastern Polar Basin to the Western Polar Basin (Peacock et al. 2015).

At a finer scale, there is evidence to support sub-structuring of polar bears within BS. Studies on individual movement using satellite telemetry and mark-recapture have been conducted in the Svalbard area since the early 1970s (Larsen 1972, 1985, Wiig 1995, Mauritzen et al. 2001, 2002). These data show that some bears associated with Svalbard are very restricted in their movements, but bears specifically from the Barents Sea range widely between Svalbard and Franz Josef Land in the western Russian Arctic (i.e., a ‘pelagic’ type;’ Wiig 1995, Mauritzen et al. 2001). Within the BS boundaries, substructure between local Svalbard bears and pelagic bears is likely increasing as sea ice around the islands disappears for longer durations. Fewer of the pelagic bears use maternity dens in the eastern part of Svalbard (Derocher et al. 2011, Aars 2013), in traditionally important denning areas, and it is likely that many of these bears now den more frequently on Franz Josef Land. Some bears of the pelagic-type from northern Svalbard, move north to the Arctic Ocean in the summer, and return to northern Svalbard in the winter, whereas bears from southeast Svalbard follow retreating ice to the east. Capture-recapture data also show that movement between northwest and southeast Svalbard is rare between springs of different years (Lone et al. 2013).

A new national park on Franz Josef Land was dedicated by the Russian Federation in 2016; this is an important summering area for polar bears.

References

Reference list