Pusa hispida

18.

Ringed Seal

Pusa hispida

French: Phoque annelé / German: Ringelrobbe / Spanish: Foca anillada

Other common names: Fjord Seal, Jar Seal; Arctic Ringed Seal (hispida); Baltic Sea Ringed Seal (botnica); Lake Ladoga Ringed Seal (ladogensis); Sea of Okhotsk Ringed Seal (ochotensis); Lake Saimaa Ringed Seal (saimensis)

Taxonomy. Phoca hispida Schreber, 1775,

“Man fangt ihn auf den Kiisten von Gronland und Labrader” (= Greenland and Labrador).

Several subspecies have been proposed based on geographicalisolation. Five subspecies recognized.

Subspecies and Distribution.

P. h. hispida Schreber, 1775 — Arctic Ocean.

P h. botnica Gmelin, 1788 — Baltic Sea.

P. h. ladogensis Nordqvist, 1889 — Lake Ladoga (W Russia).

Ph. ochotensis Pallas, 1811 — Sea of Okhotsk and N Japan (Hokkaido).

P. h. saimensis Nordqvist, 1889 — Lake Saimaa (S Finland).

Descriptive notes. Total length 110-160 cm; weight ¢.50-90 kg. Newborns are 60-65 cm in length and weigh 4.5-5.5 kg.

Ringed Seals are relatively small and plump phocid carnivores. They have robust nails on foreflippers used to abrade ice to excavate birth lairs and to keep breathing holes open in winter. Offspring are born with a woolly lanugo (fine, soft hair) that is shed when hey are c.2-3 weeks old. It is replaced by a relatively unspotted pelage that is gray dorsally and lighter silver ventrally. Pelage of an adult Ringed Sealis dark dorsally and lighter ventrally, with extensive rings covering back, top of head, and sides and with dark blotches on lower sides and ventrum.

Habitat. Mainly associated with seasonal sea ice and fast ice (ice fastened to land) of Arctic and subarctic coastlines, islands, and bays. For example, south of Saint Lawrence Island, Alaska, in late winter, Ringed Seals and Walruses (Odobenus rosmarus) preferred large ice floes (more than 48 m in diameter), and Spotted Seals (Phoca largha) preferred small ice floes (less than 20 m in diameter). Ringed Seals depend on such areas to haul-out and give birth, nurse offspring, and molt. Small numbers of Ringed Seals live in freshwater: the “Lake Saimaa Ringed Seal” (P. h. saimensis) in southern Finland and the “Lake Ladoga Ringed Seal” (P. h. ladogensis) in western Russia.

Food and Feeding. The diet of Ringed Seals is relatively diverse and varies depending on geographical area, marine habitat types, and regional composition offish and invertebrate communities. Most prey is small and includes zooplankton and nekton, epibenthic cephalopods and fish, and mid-water schooling fish. Although groups of Ringed Seals can occur near concentrations of schooling fish—their preferred prey—they appear to hunt and capture prey alone without any direct interactions among conspecifics. Arctic cod (Boreogadus saida and Arctogadus glacialis), saffron cod (Eleginus gracilis), redfish (Sebastes spp.), capelin (Mallotus villosus), sculpin (Cottidae), and herring (Clupea spp.) are often reported to be their most important prey species. Invertebrate prey seems to become more important in the open-water season and often dominates diets of young Ringed Seals. Large amphipods (e.g. Themisto libellula), krill (e.g. Thysanoessa inermis), mysids (e.g. Mysis oculata), shrimps (e.g. Pandalus spp., Eualus spp., Lebbeus polaris, Crangon septemspinosa), and cephalopods (e.g. Gonatus spp.) are eaten by Ringed Seals and can be very important in some regions at least seasonally. Fatty acid composition of blubber of Ringed Seals from subsistence harvests near Little Diomede Island, Alaska (USA), differed from that of sympatric Bearded Seals (Erignathus barbatus), Ribbon Seals (Histriophoca fasciata) and Spotted Seals, suggesting dietary separation. Such comparisons of fatty acids are not only useful as an index of diet but also as a benchmark to assess future climate change. Most foraging dives of Ringed Seals are less than 100 m deep, although they occasionally dive to 300 m, or a little more.

Breeding. Female Ringed Seals give birth in March-April in small caves or lairs that they excavate below the surface of sea ice and fast ice under hummocks formed by pressure ridges. They nurse their offspring for c.4-6 weeks and mate near the time offspring are weaned. The fertilized egg develops briefly and then remains freefloating and dormant for c.2-3 months before it attaches to the uterine wall and development and growth resume. Adult male Ringed Seals appear to be territorial around breathing holes near a birth lair and are vocally and physically aggressive underwater to defend access to holes and females against other males. Females are sexually mature at c¢.4-6 years old and males at about seven years old. Maximum longevity is up to 45 years.

Activity patterns. Male and female Ringed Seals begin feeding intensely just after the breeding season to regain body mass that they lost and restore their condition to prepare to molt. Ringed Seals molt in June—July and fast for a couple of weeks while they are hauled out on ice floes or, in Lake Saimaa, on land. Between molting and breeding seasons and breeding and molting seasons, Ringed Seals appear to dive and forage constantly, hauling out on ice floes and forming sea ice for brief periods to rest.

Movements, Home range and Social organization. Ringed Seals are mostly solitary throughout the year, although they do loosely aggregate in large numbers where ice is limited during breeding and molting seasons, or when feeding near large concentrations of schooling fish. Juvenile Ringed Seals are known to wander quite far south to New Jersey (USA) and Portugal in the North Atlantic Ocean and Zhejiang (China) and California (USA) in the North Pacific Ocean, particularly in summer.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Nevertheless, the IUCN classification concludes that the population trend of the Ringed Seal is unknown and that a realistic assessment of its conservation is seriously affected by difficulties in obtaining accurate population estimates because of its widespread and variable distribution, much of it in remote, high-latitude Arctic sea ice, which is very difficult to survey. For example, although some estimates suggested that the population of the “Arctic Ringed Seal” (P. h. hispida) might have been 6-7 million in the 1970s and 2-5 million in the early 2000s, consensus seems to indicated a much smaller overall population now. Growing concern over the loss of sea ice throughout Arctic distribution of the Ringed Seal as a result climate change, among other more localized factors, has prompted the listing of all five subspecies of the Ringed Seal as endangered or threatened under the US Endangered Species Act. Numbers of the Lake Saimaa Ringed Seal in southern Finland have declined from several thousand to ¢.200-250 individuals from poaching, pollution (e.g. mercury), and changes in ice coverage. It has been protected under Finnish Law since 1955 and has been listed as a foreign endangered species under the US Endangered Species Act since 1993. Poaching, fisheries bycatch (10-16% of the annual mortality), and substantial pollution in the lake have negatively affected the Lake Ladoga Ringed Seal; its population was estimated at ¢.9000 individuals in the late 20" century and ¢.3000-5000 individuals in 2007. It is listed as rare in the Red Data Book of the Russian Federation and hunting has been prohibited since 1980;it waslisted as a foreign endangered species under the US Endangered Species Act in 2012. The Arctic Ringed Seal, the “Baltic Sea Ringed Seal” (P. h. botnica), and the “Okhotsk Ringed Seal” (P. h. ochotensis) were listed as foreign threatened species under the US Endangered Species Act in 2012. The population of Arctic Ringed Seal in Alaskan waters, under the jurisdiction of US Marine Mammal Protection Act, is estimated at 249,000 individuals, and subsistence harvest is regulated. Humans have hunted Ringed Seals for thousands of years for food, oil, and skins for clothing and covers for kayaks. Villagers in Greenland, Canada, and coastal Russia kill tens of thousands of Ringed Seals annually for subsistence—all regulated by the respective governments. Clearly, improved methods to assess population numbers and trends are needed to clarify the overall conservation status of the Ringed Seal.

Bibliography. Burns (1970), Carlens et al. (2006), Cooper et al. (2009), Gjertz et al. (2000b), Hammill (2009), Kelly & Quakenbush (1990), Kelly & Wartzok (1996), Kovacs et al. (2008), Labansen et al. (2007), McLaren (1958b), Quakenbush & Sheffield (2007), Simpkins et al. (2003), Smith (1987).