Ringed seals resemble harbor and spotted seals, but are decidedly plumper (axillary girth may reach 80% of length). They also have a smaller, somewhat rounded head and muzzle, and a conspicuously short and thick neck. The muzzle is short, slightly broader than thick, and blunt. The vibrissae are light-colored and beaded. The eyes are relatively large and conspicuous. More than in other northern phocids, the size of the head and muzzle, and the close-set, forward-facing, eyes impart a cat-like appearance. The foreflippers are relatively small and slightly pointed, as in the harbor seal.
The background coloration is variable, but normally is medium to dark gray above and light gray to silver below. Ringed seals are conspicuously marked with light gray to off-white rings that encircle “spots” of the darker dorsal and lateral background pelage coloration. The spots are the same color as, or slightly darker than, the background color of the coat. Some ringed seals can be so heavily marked that many rings and spots fuse creating a confused paint-splattered appearance. The lighter colored sides have a variable number of dark spots that do not appear to be encircled by rings because of the paler lateral and ventral pelage. Pups are born with a woolly, thick, whitish lanugo. Fur of the succeeding coat is finer and slightly longer than that of adults, and is dark gray above, merging to silver below. There may be a few scattered dark spots on the undersides of these juveniles, and few, if any, rings on the back. At this stage, they are known as “silver jars.”
The dental formula is: I 3/2, C 1/1, PC 5/5.
Adults are up to about 1.65 m in length. Weight is 50-70 kg, with a maximum of 110 kg. Pups average about 60-65 cm and 4-5 kg at birth.
There are five recognized subspecies: P. h. hispida, in the Arctic basin; P. h. ochotensis, in the Seas of Okhotsk and Japan; P. h. saimensis, in Lake Saimaa; P. h. ladogensis, in Lake Ladoga; and P. h. botnica, in the Baltic Sea.
Can be Confused With
Ringed seals share their extensive range with seven other phocids. They are not likely to be confused with bearded, harp, hooded, gray or ribbon seals because of differences in size, coloration, and head shape, but care may be required to positively distinguish them from other seals with rings, spots or spot-like markings, such as harbor and spotted seals. Separating these species requires paying attention to coloration and markings, noting the relative size and shape of the head, and to the overall body size and shape.
Spotted and harbor seals are very similar in build and length. Adults of both are longer than ringed seals, and the neck, head and muzzle appear proportionately longer than in ringed seals. Spotted seals breed on sea ice and give birth to pups in a longer grayish lanugo coat like ringed seals. However, most spotted seals have no rings, and when they do they are usually only evident on the most heavily spotted individuals. Spotted seals have their pups on the surface of the ice, whereas ringed seals have their pups in lairs under snow layers on sea ice, and inside pressure ridges.
Harbor seals on land do not pup on sea ice, and do not regularly use ice except in areas where glaciers discharge ice into bays and fjords and it is a semi-permanent feature. Except in rare cases or when pups are born prematurely, the coloration of harbor seal pups is essentially the same as in adults and subadults. Harbor seals generally have some rings, but when present, always have a mixture of rings and spots and are far less uniformly marked with rings than most ringed seals.
Ringed seals have a circumpolar distribution throughout the Arctic basin, Hudson Bay and Straits, and the Bering and Baltic seas. The distribution of ringed seals is strongly correlated with pack and land-fast ice, and areas covered at least seasonally by ice. Adults use land-fast ice for breeding, molting, and over-wintering habitat.
Ecology and Behavior
Nearly all ringed seals breed on the fast ice. Females excavate lairs in snow, in pressure ridges, and other snow-covered features. These lairs have access to the water, and provide camouflage and some protection from polar bears, which are the chief predator. Pupping generally occurs from March through April, and earlier in the Baltic Sea. Males are thought to be territorial, and possibly annually monogamous.
Many adults remain in the same localized areas year-round. Out of water, ringed seals are generally wary, regularly scanning for predators, such as polar bears and humans.
Feeding and Prey
Ringed seals consume a wide variety of small prey, including many species of fishes, and planktonic and benthic crustaceans. These opportunistic feeders are known to have over 72 different species in their diet. In deep water, they forage in the water column and along the underside of ice floes, while in shallow water they often forage along the bottom with polar cod being a preferred prey species. Ringed seals forage either singly or in small groups.
Threats and Status
The vast geographic range occupied by ringed seals, coupled with their solitary nature and the difficulties of conducting population assessments in remote polar areas, make it difficult to estimate ringed seal population levels. Estimates of the world-wide population range from 4 to 7 million, with most authors expressing caution over the accuracy of both local area and range-wide figures. P. h. saimensis, of Lake Saimaa, Finland, and P. h. ladogensis, found in Lake Ladoga, Russia, are both restricted to only these land-locked bodies of water, and occur in very low population numbers (approximately 200 and 5,000 respectively).
Native peoples of the Arctic hunt ringed seals for food and skins, and have done so for thousands of years. Direct human interaction and conflicts are otherwise minimal. Existing subsistence harvests, and the commercial use of skins from some of these harvests, such as occurs in Greenland, do not appear to be negatively affecting any ringed seal populations. Most ringed seals take few commercially important prey species, with notable exceptions in Greenland and in the White and Barents seas. The Baltic Sea population, P. h. botnica, is surrounded by large human population centers and may suffer from exposure to pollutants that compromise their immune system and lead to higher rates of disease that negatively affect reproduction.
The effects of global warming and the projected decreased extent and duration of sea ice cover associated with warming of the Arctic could have dire consequences for ringed seal survival. Several studies have already demonstrated decreased reproductive success in response to poor sea ice conditions in localized areas.
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