Arctic ringed seal

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Arctic ringed seal
Pusa hispida hispida NOAA 1.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Clade: Pinnipedia
Family: Phocidae
Genus: Pusa
Species:
P. hispida
Subspecies:
P. h. hispida
Trinomial name
Pusa hispida hispida
(Schreber, 1775)

The Arctic ringed seal (Pusa hispida hispida) is a subspecies of ringed seals (Pusa hispida). Arctic ringed seals inhabit the Arctic Ocean, and are the most abundant and wide-ranging seal in the Northern Hemisphere. The ringed seal species is the smallest true seal, and gets its name from a distinctive patterning of light spots on dark grey colored fur. The ringed seal is commonly preyed upon by Polar bears, Arctic foxes, and Killer whales. Population estimates and survival rates are unknown, but average life expectancy is 15-28 years.  Ringed seals have long been a component of the diet of indigenous people of the Arctic. Arctic ringed seals have been listed as threatened on the Endangered Species Act since 2012, and increasingly face loss of their habitat due to shrinking ice and snow cover.

Contents

Physical characteristics

The Arctic ringed seal shares a striking similarity with other species of ringed seals. It is characterized by a small head, a snout that resembles a cat's with whiskers, and a sturdy, elongated body. Its coat is typically dark with a silver-colored belly, marked by silver rings along its back and sides. This feature is what gives it the common name 'ringed seal'. They have strong claws on their fore flippers, which they use to pierce ice to create breathing holes. Depending on subspecies and sex, adult seals can vary in size, measuring from 100 to 175 cm (39.5 to 69 in) and weighing from 30 to 140 kg (70 to 310 lb). The seal averages about 5 ft (1.5 m) long. This species is the smallest species in the true seal family. [1]

Taxonomy and phylogeny

Ringed seals are members of the Phocidae family. [2] Researchers propose that the Phocidae family diverged from Pinnipeds, a monophyletic group of aquatic carnivores. Pinnipeds diverged from their terrestrial relatives around 40 million years ago. Pinnipeds originated in the Arctic, and diverged 20-25 million years ago into three families: Phocidae (true seals), Otariidae (sea lions), and Odobenidae (walruses). Members of the Phocidae group, which include ringed, Baikal, and Caspian seals, have adapted to breeding on sea ice. Molecular, biogeographic, and morphological approaches to classification of Pusa hispida remain incomplete.

The Arctic ringed seal, Pusa hispida hispida, is one of 5 recognized ringed seal subspecies. [1] There have been up to 10 proposed subspecies, but current data only supports 5. The other four subspecies are found in the Sea of Okhotsk (Pusa hispida ochotensis), the Baltic Sea (Pusa hispida botnica), Lake Ladoga in Russia (Pusa hispida ladogensis), and Lake Saimaa in Finland (Pusa hispida saimensis). Ringed seals were geographically isolated from each other during the Last Glacial Maximum, during which land bridges and thick sea ice separate populations and pushed some populations southward. This expanded the range of ringed seals and created subspecies, which are discrete breeding populations. There is low genetic differentiation between species. There is some thought that Pusa h. hispida, the Arctic subspecies, may include multiple different subpopulations. More research into the Arctic population structure is needed to confirm. [2]

Distribution and abundance

Arctic ringed seals exhibit circumpolar distribution around the Northern Hemisphere. [3] They have historically been found in most seasonally ice covered seas. The Arctic ringed seal is the most abundant out of all the ringed seal subspecies. Their distribution is divided into five regions. These regions are the Greenland Sea and Baffin Bay, Hudson Bay, Beaufort Sea, Chukchi Sea, and the White, Barents and Kara Seas. These regions do not reflect their full distribution since estimates of Arctic ringed seal populations are not available in certain areas. It can be difficult to accurately assess ringed seals' abundance, due to difficulty in tracking their trends in movement. This is due to the remoteness of their habitat, time spent below ice, and their wide range of seasonal movements. Population estimates in the five regions have not been conducted since the late 1900s for most regions. Based on aerial surveys in 2007-2008, the Hudson Bay ringed seal population estimate is 53,346 seals. [2] Based on available data for study areas within the Beaufort and Chukchi Seas, scientists estimate that there are about 1 million seals in this region.

There is no evidence that Arctic ringed seals were historically distributed in other regions. Various studies were conducted in the 1900s to determine population sizes. In 1979, the Greenland Sea and Baffin Bay region was estimated to have 787,000 seals. The population estimate for seals is about 220,000 seals in the White, Barents, Kara, and East Siberian Seas. This data was compiled in the late 1900s. [4]

Note: There is no available range map for the Arctic ringed seal subspecies. See ringed seal wikipedia page for range map of entire species.

Habitat and seasonal behavior

Arctic ringed seals are uniquely adapted to live on ice, and the seasonality of ice cover strongly influences ringed seal behaviors. [4] Specifically, ice cover affects their movements, foraging, reproductive behavior, and vulnerability to predation. As water freezes in the late fall, ringed seals surface to breathe in the remaining open water. Once the ice becomes too thick, they create breathing holes by scraping the ice with their claws. [1] The breathing holes can be maintained in ice 2 m or greater in thickness. They form subnivean lairs over the breathing holes, which are used mainly for pupping, and nursing young. As snow builds up around them, the seals breathe through the holes. According to tracking records, Arctic ringed seals breeding exhibits inter-annual fidelity to breeding sites. That is, they have a tendency to return to breeding sites that were previously used. These snow caves serve as refuge from low temperatures. These low temperatures can be dangerous to pups, and the lairs also hide the seals from predators.

As temperatures warm, ringed seals transition to laying on the surface of the ice near breathing holes. The number of seals on the surface of the ice starts to increase during spring as the  snow melts. Ringed seals are usually solitary, however they may gather in groups around breathing holes during the molting season each spring. Throughout most of its range, seals use ice as a location for resting, pupping, and molting.

Currently there is no specified critical habitat for the ringed seal. There is a proposed map [5] for the critical habitat as of March 2019. The Endangered Species Act requires designation of a critical habitat for species within one year of listing. Various wildlife groups, including the Center for Biological Diversity, have taken legal action against the National Marine Fisheries Service for failing to designate a critical habitat for Ringed Seals.

Icebergs in the High Arctic - 20050907.jpg

Ecology and behavior

Reproduction and life history

Male ringed Seals reach sexual maturity as late as 7 years old. [4] For females, sexual maturity can be as late as 9 years, but it can be as early as 3 years for both sexes. Ringed seals breed annually, but the timing varies based on the region. Though the timing varies with latitude, pupping usually occurs in late March through April in the Arctic. Much is unknown about the breeding system, but it is thought to be polygynous. Mating occurs while females are still nursing their pups, and mating is believed to happen near birth lairs. Males are reported to have territorial tendencies during the breeding season, producing a strong, gasoline-like scent to mark their breathing holes and lairs.  After a 9 month gestation period, female seals give birth to a single pup. At birth they pups are approximately 60-65 cm in length and weigh 4.5-5.0 kg. The pups are born with a white natal coat of blubber, known as the “lanugo,” that provides insulation until it sheds after 4-6 weeks. The pups nurse for as long as 2 months in stable shorefast ice, but for as little as 3-6 weeks in moving ice. During nursing, Arctic ringed seals spend about 50% of their time in the water, and practice developing deep diving skills. Pups are normally weaned before the spring ice breaks up, and pups are four times their birth weights at weaning. Ringed seals live about 25-30 years, and are solitary with territorial tendencies for most of their lives besides breeding.

Nerpichii vzgliad.jpg

Diet

Ringed seals eat a wide variety of small prey that span several trophic levels. Scientists have some disagreement over their exact diet. Analysis reveals their diet varies depending on a variety of factors, such as location, season, life stage, and sex. [6] Research suggests a latitudinal gradient as well. Arctic cod is most often reported as the primary prey species. [2] Herring, redfish, snailfish, sand lance, and Atlantic salmon are also common prey items. Mating and molting occur in the spring, during which shrimp and invertebrates become more important to the diet. During summer and fall, seals feed on prey such as sand lance during the open water season, to prepare fat reserves for the winter. In the fall, prey from the cod family tend to make a higher percentage of the seal’s diet from late fall through spring. If females don't get adequate blubber reserves from feeding, they will suppress ovulation for that year. [2] This ensures they always have enough energy reserves needed for reproduction. Feeding is usually a solitary behavior, during which they may dive to depths of 35 to 150 feet and stay submerged for up to 39 minutes. [1] The mechanism of food consumption is unclear. Some studies report that seals eat small fish by swallowing them whole, while others suggest that seals filter food with their teeth.

Predation

Polar bear after unlucky hunt for a seal.jpg

Polar bears are the primary predator of ringed seals. [2] Ringed seal pups are especially vulnerable, and make easy kills for polar bears. Analysis of fatty acid signatures found that ringed seals are the predominant prey species for polar bears. [7] While the ice lairs provide some protection, Arctic foxes are also a threat, as the foxes can enter the birth lairs and eat the pups. They will also eat the ringed seal remains leftover from the polar bear kills. Greenland sharks and the occasional Atlantic walrus also may prey on ringed seals in the water.  Pups have several behaviors that are adaptive responses to predation pressure. These include their time spent practicing diving, use of breathing holes, prolonged lanugo stage, and ability to hide in snow caves.

Conservation

Major threats

The major threat to ringed seals is habitat loss due to global climate change. [1] Ringed seals depend on floating sea-ice platforms for reproduction. This leaves them extremely vulnerable to the effects of rising sea temperatures. The effects of a warming climate are most extreme in northern regions, where these arctic ringed seals inhabit. This is due to the albedo effect, in which melting snow and ice reduces the amount of sunlight reflected back. [2] This means that more solar radiation is absorbed by the water, further increasing sea temperatures. Major declines in sea ice are predicted for July and November after 2050. It would take many years to restore previous ice thickness, and the loss of ice over multiple years makes it unlikely that the Arctic will return to previous conditions. [8] This would be detrimental to ringed seals’ reproduction, foraging, and way of life. The ringed seal has a long gestational period and is only able to produce only a single pup each year. This reproductive habit makes them especially vulnerable to environmental challenges. Ringed seals need accumulated snow and stable ice to build their birth lairs. This habitat can be affected by warming temperatures, affecting the time period that the pups have to grow and mature in protection. By 2100, scientists predict that April snow cover will not be sufficient to form and occupy birth lair. They also predict that this will result in increased pup and adult mortality.

It has been proposed that increased temperatures could lead to increased biological productivity. This trend could benefit ringed seals in the short term. However, this can lead to increased vulnerability of seal pups to predation. Additionally, ocean acidification reduces seawater pH and absorption of the carbonate ions in the water. The waters of the Arctic are some of the most vulnerable to ocean acidification. The impact of ocean acidification on ringed seals could be at lower trophic levels. Seals rely on these trophic levels for food, leading to negative impacts on the seals’ dietary habits.

Human interactions

Ringed seal fur-skin (Phoca hispida), 'Ring-Seal'.jpg

Ringed Seals have been hunted by humans for thousands of years. For indigenous peoples in the Arctic, seals have long been an important component of their diet. Early Paleoskimo sites in Arctic Canada reveal signs of harvested ringed seals dating back from c. 300-3500 BC.  They are still an important resource for many northern coastal communities. Subsistence harvesting of Arctic ringed seals occurs, but in sustainable levels.

Additionally, there are many human-related threats to ringed seals. These include commercial fishing, ship traffic, petroleum drilling, pollutants, and human-aided global warming. [2] Ringed Seals are also vulnerable to oil spills. The former Trump administration was looking to expand offshore oil drilling in the Arctic. They were also expanding fossil fuel production in the Alaska National Wildlife Refuge. Drilling for oil in the ringed seal’s habitat threatens their health and safety. [9]

Conservation efforts

In the United States, ringed seals have been listed as threatened under the Endangered Species Act since 2012. They also are included under the Marine Mammal Protection Act. The only population that lives in US waters are the Arctic subspecies, which reside in the Alaskan waters. They are only allowed to be harvested by Alaskan Natives for subsistence hunting. [2] There is very little overlap between the ringed seals' habitat and US commercial fishing. Therefore, human-caused mortality rates are unknown. The Act prohibits all other forms of hunting of ringed seal. However, as of March 2019, there is no designated critical habitat for ringed seals, preventing these seals from getting vital habitat protection.

In Russia, the Franz Josef State Nature Reserve protects large swaths of ringed seal habitat in the Russian Arctic. This reserve spans the White and Kara seas, a region home to many ringed seals. Additionally, there have been quotas in place and licensing of hunting for decades.

Ringed seals are listed as a species of “Least Concern” on the IUCN Red List. [10] The Red List assessment notes that the conservation status of ringed seals should be reassessed within a decade. This is in part due to the impact of climate change on ringed seals. The European Red List also assesses the conservation status of European species according to IUCN guidelines.The IUCN Red List does not have an Action Recovery Plan at this time, nor a Systematic monitoring scheme. This may be due to the ringed seals' current listing of “Least Concern." US Fish and Wildlife Services does not list any candidate information, species status assessments, recovery plans, conservation plans, or 5 year reviews for this species. A recovery plan will likely be added in the future as their habitat deteriorates due to climate change.

Anticipated conservation actions

The IUCN recommends conservation actions which manage and protect the species, land, and water. Specifically, there needs to be effort to protect and manage the site, including resources and habitat. [11] Procuring critical habitat designation under the Endangered Species Act would promote population recovery. More research must be done on population size, distribution, and trends, in order to design effective conservation plans. [1]

Related Research Articles

<span class="mw-page-title-main">Earless seal</span> Family of mammals

The earless seals, phocids, or true seals are one of the three main groups of mammals within the seal lineage, Pinnipedia. All true seals are members of the family Phocidae. They are sometimes called crawling seals to distinguish them from the fur seals and sea lions of the family Otariidae. Seals live in the oceans of both hemispheres and, with the exception of the more tropical monk seals, are mostly confined to polar, subpolar, and temperate climates. The Baikal seal is the only species of exclusively freshwater seal.

<span class="mw-page-title-main">Fur seal</span> Subfamily of mammals

Fur seals are any of nine species of pinnipeds belonging to the subfamily Arctocephalinae in the family Otariidae. They are much more closely related to sea lions than true seals, and share with them external ears (pinnae), relatively long and muscular foreflippers, and the ability to walk on all fours. They are marked by their dense underfur, which made them a long-time object of commercial hunting. Eight species belong to the genus Arctocephalus and are found primarily in the Southern Hemisphere, while a ninth species also sometimes called fur seal, the Northern fur seal, belongs to a different genus and inhabits the North Pacific. The fur seals in Arctocephalus are more closely related to sea lions than they are to the Northern fur seal, but all three groups are more closely related to one another than they are to true seals.

<span class="mw-page-title-main">Pinniped</span> Taxonomic group of semi-aquatic mammals

Pinnipeds, commonly known as seals, are a widely distributed and diverse clade of carnivorous, fin-footed, semiaquatic, mostly marine mammals. They comprise the extant families Odobenidae, Otariidae, and Phocidae, with 34 extant species and more than 50 extinct species described from fossils. While seals were historically thought to have descended from two ancestral lines, molecular evidence supports them as a monophyletic group. Pinnipeds belong to the suborder Caniformia of the order Carnivora; their closest living relatives are musteloids, having diverged about 50 million years ago.

<span class="mw-page-title-main">Baikal seal</span> Species of freshwater seal

The Baikal seal, Lake Baikal seal or nerpa is a species of earless seal endemic to Lake Baikal in Siberia, Russia. Like the Caspian seal, it is related to the Arctic ringed seal. The Baikal seal is one of the smallest true seals and the only exclusively freshwater pinniped species. A subpopulation of inland harbour seals living in the Hudson Bay region of Quebec, Canada,, as well as the Saimaa ringed seal and the Ladoga seal, are also found in fresh water, but these seals are part of species that also have marine populations.

<span class="mw-page-title-main">Ringed seal</span> Species of carnivore

The ringed seal is an earless seal inhabiting the Arctic and sub-Arctic regions. The ringed seal is a relatively small seal, rarely greater than 1.5 metres (5 ft) in length, with a distinctive patterning of dark spots surrounded by light gray rings, hence its common name. It is the most abundant and wide-ranging ice seal in the Northern Hemisphere, ranging throughout the Arctic Ocean, into the Bering Sea and Okhotsk Sea as far south as the northern coast of Japan in the Pacific and throughout the North Atlantic coasts of Greenland and Scandinavia as far south as Newfoundland, and including two freshwater subspecies in northern Europe. Ringed seals are one of the primary prey of polar bears and killer whales, and have long been a component of the diet of indigenous people of the Arctic.

<span class="mw-page-title-main">Bearded seal</span> Species of Arctic dwelling marine mammal

The bearded seal, also called the square flipper seal, is a medium-sized pinniped that is found in and near to the Arctic Ocean. It gets its generic name from two Greek words that refer to its heavy jaw. The other part of its Linnaean name means bearded and refers to its most characteristic feature, the conspicuous and very abundant whiskers. When dry, these whiskers curl very elegantly, giving the bearded seal a "raffish" look.

<span class="mw-page-title-main">Harp seal</span> Species of mammal

The harp seal, also known as Saddleback Seal or Greenland Seal, is a species of earless seal, or true seal, native to the northernmost Atlantic Ocean and Arctic Ocean. Originally in the genus Phoca with a number of other species, it was reclassified into the monotypic genus Pagophilus in 1844. In Greek, its scientific name translates to "ice-lover from Greenland," and its taxonomic synonym, Phoca groenlandica translates to "Greenlandic seal." This is the only species in the genus Pagophilus.

<span class="mw-page-title-main">Hawaiian monk seal</span> Species of carnivore

The Hawaiian monk seal is an endangered species of earless seal in the family Phocidae that is endemic to the Hawaiian Islands.

<span class="mw-page-title-main">Weddell seal</span> Species of mammal

The Weddell seal is a relatively large and abundant true seal with a circumpolar distribution surrounding Antarctica. The Weddell seal was discovered and named in the 1820s during expeditions led by British sealing captain James Weddell to the area of the Southern Ocean now known as the Weddell Sea. The life history of this species is well documented since it occupies fast ice environments close to the Antarctic continent and often adjacent to Antarctic bases. It is the only species in the genus Leptonychotes.

<span class="mw-page-title-main">Caspian seal</span> Species of seal endemic to the Caspian Sea

The Caspian seal is one of the smallest members of the earless seal family and unique in that it is found exclusively in the brackish Caspian Sea. It lives along the shorelines, but also on the many rocky islands and floating blocks of ice that dot the Caspian Sea. In winter and cooler parts of the spring and autumn season, it populates the northern Caspian coastline. As the ice melts in the summer and warmer parts of the spring and autumn season, it also occurs in the deltas of the Volga and Ural Rivers, as well as the southern latitudes of the Caspian where the water is cooler due to greater depth.

<span class="mw-page-title-main">Ribbon seal</span> Species of mammal

The ribbon seal is a medium-sized pinniped from the true seal family (Phocidae). A seasonally ice-bound species, it is found in the Arctic and Subarctic regions of the North Pacific Ocean, notably in the Bering Sea and Sea of Okhotsk. It is distinguished by its striking coloration, with two wide white strips and two white circles against dark brown or black fur.

<span class="mw-page-title-main">Saimaa ringed seal</span> Freshwater seal found in Finland

The Saimaa ringed seal is a subspecies and glacial relict of ringed seal. They are among the most endangered seals in the world, having a total population of only about 400 individuals. The only existing population of these seals is found in Lake Saimaa, Finland. They have lived in complete isolation from other ringed seal species for around 9,500 years and have diverged into a morphologically and ecologically different subspecies of ringed seal. The population is descended from ringed seals that were separated from the rest when the land rose after the last ice age. This seal, along with the Ladoga seal and the Baikal seal, is one of the few living freshwater seals.

<span class="mw-page-title-main">Ross seal</span> Species of mammal

The Ross seal is a true seal with a range confined entirely to the pack ice of Antarctica. It is the only species of the genus Ommatophoca. First described during the Ross expedition in 1841, it is the smallest, least abundant and least well known of the Antarctic pinnipeds. Its distinctive features include disproportionately large eyes, whence its scientific name, and complex, trilling and siren-like vocalizations. Ross seals are brachycephalic, as they have a short broad muzzle and have shorter fur than any other seal.

<span class="mw-page-title-main">Spotted seal</span> Species of mammal

The spotted seal, also known as the larga seal or largha seal, is a member of the family Phocidae, and is considered a "true seal". It inhabits ice floes and waters of the north Pacific Ocean and adjacent seas. It is primarily found along the continental shelf of the Beaufort, Chukchi, Bering and Okhotsk Seas and south to the northern Yellow Sea and it migrates south as far as northern Huanghai and the western Sea of Japan. It is also found in Alaska from the southeastern Bristol Bay to Demarcation Point during the ice-free seasons of summer and autumn when spotted seals mate and have pups. Smaller numbers are found in the Beaufort Sea. It is sometimes mistaken for the harbor seal to which it is closely related and spotted seals and harbor seals often mingle together in areas where their habitats overlap.

<span class="mw-page-title-main">Ladoga ringed seal</span> Freshwater seal found in northwestern Russia

The Ladoga ringed seal is a freshwater subspecies of the ringed seal found entirely in Lake Ladoga in northwestern Russia. This pinniped was isolated in freshwater lakes and separated from the Arctic ringed seal as a result of the isostatic rebound of the region following the end of the Weichselian Glaciation.

<i>Pusa</i> Genus of mammals

Pusa is a genus of the earless seals, within the family Phocidae. The three species of this genus were split from the genus Phoca, and some sources still give Phoca as an acceptable synonym for Pusa.

<span class="mw-page-title-main">Arctic lemming</span> Species of rodent

The Arctic lemming is a species of rodent in the family Cricetidae.

<span class="mw-page-title-main">Hauling-out</span> Marine mammal behaviour

Hauling out is a behaviour associated with pinnipeds temporarily leaving the water. Hauling-out typically occurs between periods of foraging activity. Rather than remain in the water, pinnipeds haul out onto land or sea ice for reasons such as reproduction and rest. Hauling out is necessary in seals for mating and giving birth. Other benefits of hauling out may include predator avoidance, thermoregulation, social activity, parasite reduction and rest.

<span class="mw-page-title-main">Pagophily</span> Preference or dependence on water ice

Pagophily or pagophilia is the preference or dependence on water ice for some or all activities and functions. The term Pagophila is derived from the Ancient Greek pagos meaning "sea-ice", and philos meaning "-loving".

<span class="mw-page-title-main">Freshwater seal</span> Seal species which live primarily in freshwater lakes

Freshwater seals are pinnipeds which live in freshwater bodies. The group is paraphyletic in nature, the uniting factor being the environment in which these pinnipeds live. The vast majority of all modern seals live solely in saltwater habitats though this is likely due to the rarity of sufficiently large freshwater bodies rather than the limitation of seal biology.

References

  1. 1 2 3 4 5 6 Fisheries, NOAA (2020-04-13). "Ringed Seal | NOAA Fisheries". NOAA. Retrieved 2020-04-18.
  2. 1 2 3 4 5 6 7 8 9 B. P. Kelly, J. L. Bengtson, P. L. Boveng, M. F. Cameron, S. P. Dahle, J. K. Jansen, E. A. Logerwell, J. E. Overland, C. L. Sabine, G. T. Waring, and J. M. Wilder 2010. Status review of the ringed seal (Phoca hispida). U.S. Dep. Commer., NOAA Tech. Memo. NMFS-AFSC-212, 250 p
  3. ↑ Laboratory, National Marine Mammal. "National Marine Mammal Laboratory". www.afsc.noaa.gov. Retrieved 2020-04-18.
  4. 1 2 3 "Regulations.gov Beta". beta.regulations.gov. Retrieved 2020-04-18.
  5. ↑ Fisheries, NOAA (2019-10-31). "Map of Proposed Critical Habitat for the Arctic Ringed Seal | NOAA Fisheries". NOAA. Retrieved 2020-04-18.
  6. ↑ Chambellant, Magaly; Stirling, Ian; Ferguson, Steven (13 May 2019). "Temporal variation in western Hudson Bay ringed seal Pusa hispida diet in relation to environment". Marine Ecological Progress Series.
  7. ↑ Bourque, Jennifer; Atwood, Todd; Divoky, George; Stewart, Connie (January 29, 2020). "Fatty acid-based diet estimates suggest ringed seal remain the main prey of southern Beaufort Sea polar bears despite recent use of onshore food resources". Ecology and Evolution. 10 (4): 2093. Bibcode:2020EcoEv..10.2093B. doi:10.1002/ece3.6043. PMC   7042688 . PMID   32128141.
  8. ↑ Caswell, Hal; Reimer, Jody; Derocher, Andrew; Lewis, Mark (23 January 2019). "Ringed seal demography in a changing climate". Ecological Applications. 29 (3). Bibcode:2019EcoAp..29E1855R. doi:10.1002/eap.1855. PMID   30672632.
  9. ↑ "Lawsuit Launched to Protect Arctic Habitat of Endangered Ice Seals". www.biologicaldiversity.org. Retrieved 2020-04-18.
  10. ↑ Fairbanks), Lloyd Lowry (University of Alaska (2016-01-16). "IUCN Red List of Threatened Species: Ringed Seal". IUCN Red List of Threatened Species. Retrieved 2020-04-18.
  11. ↑ Lowry, Lloyd (2016-01-16). "IUCN Red List of Threatened Species: Ringed Seal". IUCN Red List of Threatened Species. Retrieved 2020-04-18.
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