Distances between subnivean lairs used by a single seal may be up to a couple of miles (Kelly and Quakenbush 1990). Polar bears, arctic foxes, and humans are the only significant predators (Frost and Lowry 1981); polar bear sometimes may kill one-third or more of the pups in an area (Reeves et al. 1992). Avian predation on pups might be an important factor limiting the southern breeding range (Reeves et al. 1992). In the Sea of Okhotsk, mortality rate is about 35% in the first year, average of 11% for each of the next 12 years (Reeves et al. 1992).