The Spotted seal is a "true seal" with a small body, a rounded head and short flippers. The coats of adults have dark spots over light gray to silver. As pups they are pure white. These ice dwellers form seasonal family groups and prefer open seas.
Spotted seals are found in areas around the North Pacific Ocean, from Alaska’s coast, through the Bering Sea, and to the Sea of Okhotsk, Yellow Sea, Sea of Japan, and Bohai Sea. They can also be found as far to the north as the Arctic Ocean, to the west to about 170 degrees east, as well as eastward to Canada in the Mackenzie River Delta. This species inhabits the southern edge of pack ice from winter until early summer, and then moves into coastal areas, such as river mouths, for late summer and autumn. It usually hauls out and breeds on ice, but sometimes comes ashore on sand bars and beaches, and at some sites along the coast of Asia, they will breed on small, remote islands.
Detailed studies on the Spotted seal are difficult, as these animals are wary and do not tolerate humans well, quickly entering the water when sensing a possible threat. They are solitary for parts of the year, gregarious at other times. They are frequently seen at haul-out sites on ice or on the shore where several individuals or a large group leaves the water to gather. Usually haul-outs are near abundant food sources. Such groups are sometimes called “onshore associations” or OAs. Four types of OAs are seen during the year. These are: preliminary, reproductive, molting, and recovery, the last being a phase to rehabilitate after the reproduction and molting phases, which are energy intensive. OAs can vary in the gender and age of individuals during the year as the purpose of the OA changes.
Spotted seals are annually monogamous instead of polygynous, which is unusual among seals. Mating pairs form when females are ready to bear a pup from the mating of the previous year. The pair stays together until the pup is weaned and the female mates again. Breeding is usually around April or May, in the spring, but can take place in Asian waters as early as January. A single pup is produced the following spring. Gestation will last 7 to 9 months, though delayed implantation after breeding may extend the pregnancy to nearly a year. When 2 to 4 weeks old pups are weaned, their lanugo has been shed and they are able to leave the ice to start learning to forage in the water. Females reach maturity at 3 to 4 years of age and males usually at 4 to 5 years old.
Commercial harvesting of fish is a threat to Spotted seals because of competition for prey species with fisheries. Injuries and entanglements from fishing gear are another problem, especially off the Japanese coast and in the Sea of Okhotsk. Fishermen in some areas shoot small numbers of these animals, and small culls also take place to limit the damage to fisheries. Poor environmental conditions injure or kill this species, mainly pups that get caught between the sheets of pack ice that collide. A newer, potentially bigger risk is from gas and oil exploration and extraction, which could destroy their habitat and cause direct disturbance to seals as well as the risk of oil spills and pollution. The biggest threat is the predicted reduction of sea ice dye to climate change.
According to the IUCN Red List, the total Spotted seal population size is around 640,000 individuals, with over 460,000 seals in the Bering Sea; in the Sea of Okhotsk -180,000 individuals, and around 3,300 individuals in the Sea of Japan and the Yellow Sea. Currently spotted seals are classified as Least Concern (LC) on the IUCN Red List.
As piscivores, Spotted seals may have an influence on populations of fish.