Antarctic toothfish Dissostichus mawsoni and Weddell seals Leptonychotes weddellii are important mesopredators in the waters of the Antarctic continental shelf. They compete with each other for prey, yet the seals also prey upon toothfish. Such intraguild predation means that prevalence and respective demographic rates may be negatively correlated, but quantification is lacking. Following a review of their natural histories, we initiate an approach to address this deficiency by analysing scientific fishing catch per unit effort (CPUE; 1975–2011 plus sporadic effort to 2018) in conjunction with an annual index of seal abundance in McMurdo Sound, Ross Sea. We correlated annual variation in scientific CPUE to seal numbers over a 43 year period (1975–2018), complementing an earlier study in the same locality showing CPUE to be negatively correlated with spatial proximity to abundant seals. The observed relationship (more seals with lower CPUE, while controlling for annual trends in each) indicates the importance of toothfish as a dietary item to Weddell seals and highlights the probable importance of intra- and inter-specific competition as well as intraguild predation in seal-toothfish dynamics. Ultimately, it may be necessary to supplement fishery management with targeted ecosystem monitoring to prevent the fishery from having adverse effects on dependent species.

Cerebral vein thrombosis, also called superior sagittal sinus thrombosis, is a well recognized clinical and radiologic entity associated with a variety of medical disorders. We report a patient with fatal cerebral vein thrombosis following myelography, in whom the cause was familial antithrombin III (AT3) deficiency. Unsuspected AT3 deficiency should be considered in cases of unexplained cerebral venous thromboses.

Carvings that represent polar bears (Ursus maritimus) are commonly found in Dorset Paleo-Eskimo archaeological sites across the eastern Arctic. Relational ecology, combined with Amerindian perspectivism, provides an integrated framework within which to comprehensively assess the connections between Dorset and polar bears. By considering the representational aspects of the objects, we reveal an ethology of polar bears encoded within the carvings’ various forms. Reconstructing the experiences and perceptions of Dorset as they routinely interacted with these creatures, and placing these interactions in socioeconomic, environmental, and historical context, permits us to decode a symbolic ecology inherent in the effigies. To the Dorset, these carvings were simultaneously tools and mnemonics (symbols). As tools, they were used to directly access the predatory and spiritual abilities of bears or, more prosaically, to teach and remind of the variety of proper hunting techniques available for capturing seals. As symbols, however, they were far more powerful, signaling how Dorset people conceptualized themselves and their place in the universe. Symbolic of an ice-edge way of life, the effigies expose the role that this special relationship with polar bears played in the creation of Dorset histories and identities.

The preservation and conservation of living resources was one of the original stated objectives of the Antarctic Treaty, 1959. The harvesting of animals near bases for food, especially Weddell Seals Leptonychotes weddelli received particular attention at the Fourth Meeting of SCAR, 1960 (Polar Record,1961) and several regulations were suggested including: a permit required before killing, records to be kept of animals killed, and use of alternative food where possible. Annex D, Section (b)i states “… Without detailed biological research it is impossible to assess the permissible annual crop which the various [Weddell] seal colonies would stand, but it is certain that this figure is being seriously exceeded in many areas.”

Wildlife observations recorded at several offshore hydrocarbon exploration sites in the Beaufort Sea were examined to evaluate the hypothesis that polar bears Ursus maritimus are attracted to drill rigs, will be judged to represent a threat to humans there, and consequently will have to be deterred or destroyed. When polar bears came south with the pack ice in the autumn, they approached drillships or artificial islands, probably because they became curious or were attracted by unfamiliar smells. However, these bears did not usually remain in the area.

In late winter, when most of the natural leads are frozen, the movement of compacted annual ice from east to west past permanent offshore drill rigs creates open cracks on the downstream side. Because of the open water there, seals are more abundant, more accessible, or both, and bears are attracted because of better hunting conditions. In mid to late winter some bears may remain in the area for several days or longer while hunting seals. This positive reinforcement may lead these bears to be attracted to other offshore rigs in the future. In the last five years four bears attracted to offshore rigs have been shot; thus the hypothesis was found to be valid. To date, the population is not under threat, but this could change if the number of offshore drill rigs operating through the winter were to increase.

Between late March and May, from 1971 through 1979, we surveyed 74,332 km2 of sea-ice habitatin the eastern Beaufort Sea and Amundsen Gulf in the western Canadian Arctic. We defined seven sea-ice habitat types and recorded sightings of polar bears and their tracks in each to determine their habitat preferences. 791 bears (including cubs) and 6454 sets of tracks were recorded. 42.3%, 39.7%, and 15.6% of the bears were seen on floe-edge, moving ice, and drifted fast-ice habitats, respectively. Significant differences in habitat preferences were shown by bears of different sexes and age classes. Adult females accompanied by cubs of the year were the only group that showed a strong preference for fast ice with drifts, probably because they could feed adequately there while avoiding adult males that might prey upon their cubs. The highest densities of seals are found in floe-edge and moving ice habitats and this likely explains the predominance of bears there. Lone adult females and females with two-year-old cubs, adult males, and subadult males were found two and one-half to four times more frequently than predicted in floe-edge habitat. Since there are no data to suggest seals are more abundant along the floe edge than in moving ice habitat, the preference of these groups of adult polar bears for the floe edge in spring may be related to reproductive behavior.

The Arctic Ocean is the home of three major groups of mammals that depend on the sea for survival and show varying degrees of adaptation for maritime life. Most fully adapted are the whales (Cetacea), which never leave the water, and the seals and walruses (Pinnipedia) that feed entirely at sea but emerge onto land or ice for pupping and basking. Less exclusively marine are two species of the order Carnivora—Polar Bears (Ursus maritimus), that seldom live far from the sea because they feed almost entirely upon seals, and Arctic Foxes (Alopex lagopus), some of which move out onto the sea ice during the winter, mainly to scavenge on the remains of seals killed by Polar Bears.

Through the 1950s and 1960s there was a marked increase in recorded numbers of polar bears being killed for their hides, giving rise to world-wide concern that the species might be endangered. At a meeting in Fairbanks, Alaska 1965, representatives of circumpolar arctic nations discussed conservation of polar bears and concluded that international coordination of research and management efforts was essential. Subsequent meetings of scientists engaged in polar bear research were organized every two years by the International Union for the Conservation of Nature and Natural Resources, facilitating exchanges of views and cooperation; as a result, in 1973 the International Agreement on the Conservation of Polar Bears and their Habitats was signed in Oslo, Norway. This paper describes some of the research and management undertaken in the years leading up to the agreement, and initiatives that are continuing because of it.

Polar bears Ursus maritimus have a circumpolar distribution that is directly tied to the Arctic sea ice. Although they are wide-ranging, polar bears do not belong to a single population but rather are comprised of 19 largely discrete subpopulations, 13 of which are fully or partly under Canadian jurisdiction. These subpopulations are used to manage the sustainable harvest of polar bears in Canada but for conservation purposes the species is currently considered a single biological unit. Long-term climate warming has reduced the availability of sea ice that polar bears require for feeding, movement and reproduction, and continued declines in ice extent and duration are forecast to have significant negative effects on polar bears in some areas. Under the Canadian Species at Risk Act separate legal protection may be given to intraspecific groups (so called designatable units, DUs) that are genetically, geographically and/or biogeographically distinct. We examined the conservation status of polar bears across their Canadian range and compared large-scale ecosystem properties across subpopulations. We found that threats to the conservation of polar bears are not spatially uniform and we identified five DUs that captured broad patterns of polar bear biodiversity. We conclude that the use of DUs provides a biologically-sound framework for the conservation of polar bears.