Predator and Prey

Ringed seal

May 21, 2011, 10:39 am
Content Cover Image

Ringed seal. Source: NOAA National Marine Mammal Laboratory

The Ringed seal (scientific name: Pusa hispida) is one of nineteen species of marine mammals in the family of true seals. Together with the families of eared seals and walruses, true seals form the group of marine mammals known as pinnipeds..

Ringed seals derive their name from the distinctive rings of shading on their coats.

There are five subspecies:

  • Arctic Ringed Seal (Pusa hispida hispida Schreber, 1775) 
  • Baltic Ringed Seal (Pusa hispida botnica Gmelin, 1788) 
  • Lagoda Ringed seal (Pusa hispida ladogensis Nordquiest, 1899)
  • Saimaa Ringed seal (Pusa hispida saimensis Pallas, 1811) 
  • Okhotsk Ringed seal (Pusa hispida ochotensis Nordquist, 1899)
caption Ringed seal. Source:Steve Amstrup/USGS
Conservation Status

Scientific Classification

Kingdom: Animalia (Animals)
Phylum:--- Chordata
Class:------ Mammalia (Mammals)
Order:-------- Carnivora (Carnivores)
Family:-------- Phocidae (True Seals)
Genus:--------- Pusa
Species:-------- Pusa hispida (Schreber, 1775)

 

Physical description

Ringed seals are the smallest of the true seals. Adult Ringed seals are 1.1 to 1.7 meters in length, and 45 to 100 kg in body mass. Females are typically slightly smaller than males. The Ringed seal is similar in shape and colour to common seals, but it is generally darker. The belly is silver gray color and the dorsal side is pale gray with dark spots that are surrounded with pale coloured rings

Reproduction

Males are thought to be polygynous and probably hold underwater territories.The female Ringed seal matures reproductively at six to eight years of age, and may bear one pup per year. Most mating occurs in late April and early May, which is within one month of parturition. Although mating occurs in May, the blastocyst does not implant until August or September, leading to a total gestation period of approximately 240 days. Ringed seals require solid ice for pupping, which makes the pups more vulnerable to predators.

Behaviour

Adult seals are solitary except for loose feeding aggregations in the water in summer. Starting in mid-May, Ringed seals haul out onto the ice and bask in the sun. They moult at this time and do not feed to any considerable extent. Large groups of seals haul out at well chosen sites and congregate; and seals lying on the ice are vigilant and aggressive.

Distribution

caption Distribution of the Ringed seal. Source: Mirko Thiessen

The Ringed seal is the most common seal in the Arctic. This species is rarely found on the open sea, but instead is prefers areas where the ice is firm. It is found along Pacific Japanese coasts, as well as icy sea margins in Canada, Alaska and Siberia.

  • Arctic Ringed seal: firm ice areas of Arctic Ocean, Bering Sea, Barents Sea, south to Newfoundland and northern Norway, Canada, Alaska, and Siberia.
  • Baltic Ringed seal: northern parts of the Baltic Sea
  • Lagoda Ringed seal: Lake Lagoda in western Russia
  • Saimaa Ringed seal: Lake Saimaa in Finland
  • Okhotsk Ringed seal: Okhotsk Sea and northern Japan

Habitat

The preferred Ringed seal habitat consists of areas that freeze to stable ice in winter. This species lives in darkness under ice for several months during the year. Ringed seals make lairs in the snow and ice for protection from predators and thermal shelter. They can occupy ice covered areas by maintaining breathing holes and cracks in the ice. Ringed seals make their lairs by rubbing away the ice with their fore flippers.

Predators

Ringed seals are preyed on by humans and polar bears in the Arctic. Pups are taken by bears, foxes, and humans when they are in the birth lair. As a result of strong predation, Ringed seal pups spend a large proportion of time in the water and learn to dive at an extremely young age.

Food habits

Ringed seals spend most of their time feeding from late summer to early spring. During the spring and summer, Ringed seals feed on saffron cod (Eleginus gracilis), various shrimps, hypeni amphipods, and euphausiids. In the fall, Ringed seals chiefly consume Saffron cod, and from winter to early spring, Ringed seals feed mainly on Arctic cod (Boreogadus saida).

Conservation status

The Ringed seal is an abundant species, although firm population estimates are not known. The subspecies are:

  • Arctic Ringed seal: population estimates range from 2.5 million to 7.0 million.  Presently there are no measures to protect ithis subspecies. However, the habitat is protected since it is the same habitat as the Polar bear (Ursus maritimus). The ringed seal is an important part of the Polar bear diet.

  • Baltic Ringed seal:  declined until recently reaching a nadir of 5000 to 8000 individuals in the late 1990s. Since then, their numbers have increased at Bothnia Bay (the location of three-quarters of this subspecies), declined further in the Gulf of Riga, and stabilized in the Gulf of Finland (although to a very low population of 300 individuals).
     
  • Lagoda Ringed seal:  has seen a significant decline in population throughout the 20th century and appears to have a current population of 3000 to 5000 individuals. Death incurred in commercial fishing bycatch presents a significant problem for this subspecies. Hunting of seals in Lake Ladoga has been banned since 1980.
     
  • Saimaa Ringed seal:exists now only in small numbers (probably around 250 to 300 individuals, up from less than 200 in the 1980s) and is considered threatened with extinction. This subspecies has been protected since 1955. 
     
  • Okhotsk Ringed seal:  has 800,000 - 1to 1,000,000 individuals

Economic importance for humans

The Ringed seal is used by Inuit peoples for fuel and clothing. Newly moulted ringed seal pups are hunted by Canadian fur traders for their pelts.

Further reading

  1. Pusa hispida (Schreber, 1775) Encyclopedia of Life (accessed July 22, 2010)
  2. Pusa hispida, Felcher, C., 1999, Animal Diversity Web (accessed July 22, 2010)
  3. Pusa hispida, Seal Conservation Society (accessed July 22, 2010)
  4. Pusa hispida, IUCN REd List of Threatened Species (accessed July 22, 2010)
  5. The Pinnipeds: Seals, Sea Lions, and Walruses, Marianne Riedman, University of California Press, 1991 ISBN: 0520064984
  6. Encyclopedia of Marine Mammals, Bernd Wursig, Academic Press, 2002 ISBN: 0125513402
  7. Marine Mammal Research: Conservation beyond Crisis, edited by John E. Reynolds III, William F. Perrin, Randall R. Reeves, Suzanne Montgomery and Timothy J. Ragen, Johns Hopkins University Press, 2005 ISBN: 0801882559
  8. Walker's Mammals of the World, Ronald M. Nowak, Johns Hopkins University Press, 1999 ISBN: 0801857899
  9. Ringed seal, MarineBio.org (accessed July 22, 2010)

 

Glossary

Citation

Life, E. (2011). Ringed seal. Retrieved from http://www.eoearth.org/view/article/155745

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