Barents Sea (BS)

An aerial line transect survey was carried out in 2004 in the entire area. No trend information.

Status table outtake

Size Sea ice metrics Human-caused removals 2010–2014
Estimate /
95% CI
Year Method Change in spring ice retreat / Change in fall ice advance (days per decade) Change in summer sea ice area (percent change per decade) 5-yr mean Last year
Potential Actual Potential Actual
2644
1899-3592
2004Distance sampling-16.6/24.2-16.0NA1NA1
See also the complete table (all subpopulations)

Comments, vulnerabilities and concerns

There has been no hunting  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.

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

Aars, J. 2013. Variation in detection probability of polar bear maternity dens. Polar Biology 36: 1089-1096.

Aars, J., Marques, T. A., Buckland, S. T., Andersen, M., Belikov, S., Boltunov, A. and Wiig, Ø. 2009. Estimating the Barents Sea polar bear subpopulation size. Marine Mammal Science 25: 32-52.

Born, E.W., Laidre, K., Dietz, R., Wiig, Ø., Aars, J. and Andersen, M. 2012. Polar bear Ursus maritimus. Pp 102-115 in: D. Boertmann and A. Mosbech (eds.). The western Greenland Sea: a strategic environmental impact assessment of hydrocarbon activities. Scientific Report from Danish Centre for Environment and Energy No. 22, Aarhus University, 267 pp.

Born, E.W., Wiig, Ø. and Thomassen, J. 1997. Seasonal and annual movements of radiocollared polar bears (Ursus maritimus) in northeast Greenland. Journal of Marine Systems 10: 67-77.

Derocher, A.E., Andersen, M., Wiig, Ø., Aars, J., Hansen, E. and Biuw, M. 2011. Sea ice and polar bear den ecology at Hopen Island, Svalbard. Marine Ecology-Progress Series 441: 273-79.

Larsen, T. 1972. Air and ship census of polar bears in Svalbard (Spitsbergen). Journal of Wildlife Management 36: 562-570.

Larsen, T. 1985. Polar bear denning and cub production in Svalbard, Norway. Journal of Wildlife Management 49:320-326.

Lone, K., Aars, J. and Ims, R.A. 2013. Site fidelity of Svalbard polar bears revealed by mark-recapture popsitions. Polar Biology 36: 27-39.

Mauritzen, M., Derocher, A. E. and Wiig, Ø. 2001. Space-use strategies of female polar bears in a dynamic sea ice habitat. Canadian Journal of Zoology 79: 1704-1713.

Mauritzen, M., Derocher, A. E., Wiig, Ø., Belikov, S. E., Boltunov, A. N., Hansen, E. and Garner, G. W. 2002. Using satellite telemetry to define swpatial population structure in polar bears in the Norwegian and western Russian Arctic. Journal of Applied Ecology 39: 79-90.

Paetkau, D., Amstrup, S.C., Born, E.W., Calvert, W., Derocher, A.E., Garner, G.W., Messier, F., Stirling, I., Taylor, M. K., Wiig, Ø. and Strobeck, C.1999. Genetic structure of the world's polar bear populations. Molecular Ecology 8: 1571-1584.

Peacock, E., Sonsthagen, S.A., Obbard, M.E., Boltunov, A., Regehr, E.V., Ovsyanikov, N., Aars, J., Atkinson, S.N., Sage, G.K., Hope, A.G., Zeyl, E., Bachmann, L., Ehrich, D., Scribner, K.T., Amstrup, S.C., Belikov, S., Born, E., Derocher, A.E., Stirling, I., Taylor, M.K., Wiig, Ø., Paetkau, D., and Talbot, S.L. 2015. Implications of the circumpolar genetic structure of polar bears for their conservation in a rapidly warming Arctic. Plos One 10: e112021.

Pertoldi,C., Sonne, C., Wiig, Ø., Baagøe, H.J., Loeschcke, V. and Bechshøft. T.Ø. 2012. East Greenland and Barents Sea polar bears (Ursus maritimus): adaptive variation between two populations using skull morphometrics as an indicator of environmental and genetic differences. Hereditas 149: 99-107.

Wiig, Ø. 1995. Distribution of polar bears (Ursus maritimus) in the Svalbard area. Journal of Zoology 237: 515- 529.