There is no definitive genetic or other information to differentiate stocks of Arctic ringed seals. Their distribution is virtually continuous and there are few geographical barriers that would prevent their dispersion. Indeed, individual tagged ringed seals have been shown to move very long distances on occasion (Kapel et al. 1998, Ridoux et al. 1998, Teilmann et al. 1999). Lately seals tagged in Resolute Bay migrate even longer distance long distances: four travelled 2,500 kilometres to southeast Baffin Island, and another covered 3,000 kilometres, swimming to Frobisher Bay via Greenland (Polar Blog, Canadian Geographic, July 2014).
On the basis of geographical isolation, ringed seals are divided into five subspecies : Pusa hispida hispida of the Arctic Ocean (the Arctic ringed seal), P. hispida ochotensis of the Sea of Okhotsk and northern Japan, P. hispida botnica of the Baltic Sea and the two last living in fresh water lakes, P. hispida ladogensis of Lake Ladoga in Russia, P. hispida saimensis of Lake Saimaa in Finland. The latter four subspecies are well supported; genetic structuring within the Arctic subspecies, however, has yet to be thoroughly investigated, and it may prove to be composed of multiple distinct populations (Kelly et al. 2010b). Ringed seal cannot create breathing holes in the thick multi-year ice found in large parts of the Arctic Ocean and in the Canadian Archipelago north of Baffin Island. This type of ice therefore operates as a natural barrrier for ringed seals and, since they prefer to stay in the vicinity of ice, long stretches of open waters will also contain few ringed seals; the Arctic ringed seals therefore consist of several populations, between which there is little interchange (Rosing-Asvid 2010).
Distribution of ringed seals, with the Arctic ringed seal (Phoca hispida hispida) in grey. (After Rosing-Asvid 2010)
On a North Atlantic scale, the NAMMCO Scientific Committee (NAMMCO 1997a) recognised 3 stock areas (see map below), based primarily on the low likelihood of mixing between the areas. While there is presently no genetic or other evidence to support such stock divisions, they are useful in determining the status of North Atlantic ringed seals.
Area 1 is centred on Baffin Bay and includes northeastern Canada and West Greenland. It is separated from Area 2, which includes East Greenland and the Greenland Sea east to Svalbard, by the Greenlandic land mass. Area 3 includes the Barents and Kara Seas east to the Severnaya Zemlya, where it was considered that ice conditions and low productivity would limit the movements of ringed seals.