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Investigating Steller Sea Lion Populations
Investigating Steller Sea Lion Populations
Published: 2014/12/19
Channel: NOAA Fisheries
Steller Sea Lion Fight
Steller Sea Lion Fight
Published: 2015/11/18
Channel: Cowichan
Encounter with Steller sea lions at Hornby Island
Encounter with Steller sea lions at Hornby Island
Published: 2015/09/06
Channel: Ben Hollis
Dead Steller Sea Lion   by Rob Cook
Dead Steller Sea Lion by Rob Cook
Published: 2015/05/28
Channel: Rob Cook
Steller sea lion show @Marineland, Antibes (30.08.2013) -Video1
Steller sea lion show @Marineland, Antibes (30.08.2013) -Video1
Published: 2013/10/10
Channel: Amalia Trita
Steller Sea Lions In Jeopardy
Steller Sea Lions In Jeopardy
Published: 2008/02/06
Channel: ResearchChannel
Bull Steller Sea Lions Fight Oregon Coast
Bull Steller Sea Lions Fight Oregon Coast
Published: 2017/02/15
Channel: The Lethargic Sloth
Transient killer whales attacking a Steller sea lion in Juneau, Alaska
Transient killer whales attacking a Steller sea lion in Juneau, Alaska
Published: 2015/08/02
Channel: Andrew Harpster
Bigg
Bigg's (transient) Killer Whales on an EPIC Steller Sea lion hunt! San Juan Island, WA
Published: 2017/05/17
Channel: Western Prince Whale Watching - Friday Harbor, San Juan Island
Steller Sea Lions
Steller Sea Lions
Published: 2015/11/18
Channel: Cowichan
The Gift of a Steller Sea Lion Encounter - when THEY, find you.
The Gift of a Steller Sea Lion Encounter - when THEY, find you.
Published: 2014/02/16
Channel: themarinedetective
Steller sea lion on the santa cruz one mile buoy
Steller sea lion on the santa cruz one mile buoy
Published: 2017/04/09
Channel: michael nelson
Tag - Steller Sealions at the Vancouver Aquarium
Tag - Steller Sealions at the Vancouver Aquarium
Published: 2010/07/17
Channel: neil fisher
Transient Killer Whales Battling a Huge Steller Sea Lion
Transient Killer Whales Battling a Huge Steller Sea Lion
Published: 2013/06/27
Channel: Wild Northwest Beauty Photography
Steller Sea Lions Hunting Salmon in Alaska
Steller Sea Lions Hunting Salmon in Alaska
Published: 2011/08/04
Channel: Lindblad Expeditions-National Geographic
Sea LIon Caves  The Surf, Steller Sea Lions & More,  Florence Oregon
Sea LIon Caves The Surf, Steller Sea Lions & More, Florence Oregon
Published: 2013/07/23
Channel: Matthew Washam
Steller Sea Lion Takes Off with a GoPro
Steller Sea Lion Takes Off with a GoPro
Published: 2012/06/20
Channel: Vancouver Aquarium
Scuba Diving with Steller Sea Lions British Columbia 4K
Scuba Diving with Steller Sea Lions British Columbia 4K
Published: 2016/01/17
Channel: Becky Kagan Schott
Meet Astro, the Celebrity Steller Sea Lion!
Meet Astro, the Celebrity Steller Sea Lion!
Published: 2008/10/09
Channel: Mystic Aquarium
Steller sea lion  and sea otter, Valdez, Alaska, USA
Steller sea lion and sea otter, Valdez, Alaska, USA
Published: 2011/06/09
Channel: André Hedinger
Killer whale attack on Steller Sea Lion
Killer whale attack on Steller Sea Lion
Published: 2011/04/22
Channel: SéanBán
Ashley Stellar Sea Lion
Ashley Stellar Sea Lion
Published: 2016/04/25
Channel: AshleyRoomN3
Steller
Steller's sea lion (Eumetopias jubatus)
Published: 2009/01/21
Channel: Wildscreen Arkive
Steller sea lion, Eden, gives birth to pup at Alaska SeaLife Center
Steller sea lion, Eden, gives birth to pup at Alaska SeaLife Center
Published: 2013/06/28
Channel: AKSeaLifeCenter
Entanglement of Steller Sea Lions in Marine Debris: Identifying Causes and Finding Solutions
Entanglement of Steller Sea Lions in Marine Debris: Identifying Causes and Finding Solutions
Published: 2013/03/15
Channel: Kim Raum-Suryan
Diving with Steller Sea Lions Alaska
Diving with Steller Sea Lions Alaska
Published: 2014/09/08
Channel: Peter Lloyd
Crittercam: Stellar Sea Lions
Crittercam: Stellar Sea Lions
Published: 2008/09/10
Channel: oceancontent
Steller Sea Lion
Steller Sea Lion
Published: 2017/04/17
Channel: Daniel Kim
Vancouver Aquarium Steller Sea Lion
Vancouver Aquarium Steller Sea Lion
Published: 2008/02/20
Channel: dlmb137
Vancouver Island Steller Sea Lions
Vancouver Island Steller Sea Lions
Published: 2016/11/25
Channel: Cars show Island
Steller Sea Lion (Eumetopias Jubatus)
Steller Sea Lion (Eumetopias Jubatus)
Published: 2010/02/04
Channel: Animal education
Steller sea lions in Nevelsk, Sakhalin, Russia
Steller sea lions in Nevelsk, Sakhalin, Russia
Published: 2017/04/28
Channel: Peter VAN DER WOLF
Alaska Sealife Center Woody the 1600 lb Steller Sea Lion
Alaska Sealife Center Woody the 1600 lb Steller Sea Lion
Published: 2011/02/11
Channel: Lee Mayhan
Male Steller
Male Steller's Sea Lion Growling
Published: 2008/12/14
Channel: showbrd
Steller Sea Lion viewing aboard the Sikumi
Steller Sea Lion viewing aboard the Sikumi
Published: 2009/03/31
Channel: Chelsea McCarthy
Leo the Steller Sea Lion Pup Makes Friends
Leo the Steller Sea Lion Pup Makes Friends
Published: 2015/01/15
Channel: The Marine Mammal Center (California)
Woody the Steller Sea Lion
Woody the Steller Sea Lion
Published: 2010/06/18
Channel: Anitradief
Steller Sea Lion at Shoals Pt. Sitka, Alaska
Steller Sea Lion at Shoals Pt. Sitka, Alaska
Published: 2013/09/26
Channel: Paul Davis
Using Unmanned Aircraft to Survey Steller Sea Lions
Using Unmanned Aircraft to Survey Steller Sea Lions
Published: 2012/06/12
Channel: AbundantOceans
Steller Sea Lions: a turf fight at Blackney Pass
Steller Sea Lions: a turf fight at Blackney Pass
Published: 2016/10/12
Channel: Zeba Knight
Steller Sea Lion Encounter Out of Friday Harbor
Steller Sea Lion Encounter Out of Friday Harbor
Published: 2013/10/14
Channel: Jeffrey Ventre
Steller Sea Lion
Steller Sea Lion
Published: 2010/11/11
Channel: Mimi Peterson
Steller Sea Lions Roaring off Coast of Friday Harbor - HD
Steller Sea Lions Roaring off Coast of Friday Harbor - HD
Published: 2011/09/15
Channel: RyDonAnimals85
Steller Sea Lions Sneaking Up On a Deck Load of Pollock
Steller Sea Lions Sneaking Up On a Deck Load of Pollock
Published: 2013/03/12
Channel: Mike Haskins
A Steller Sea  Lion scratching  himself
A Steller Sea Lion scratching himself
Published: 2017/03/30
Channel: uracrowley
The Case of Stones in Steller Sea Lion Stomachs
The Case of Stones in Steller Sea Lion Stomachs
Published: 2014/05/06
Channel: themarinedetective
California Sea Lions
California Sea Lions
Published: 2011/12/05
Channel: Margy Lutz
Killer Whales vs Great White Sharks on Steller Sea Lions
Killer Whales vs Great White Sharks on Steller Sea Lions
Published: 2017/03/09
Channel: UCSC Animal Physiology
Sea Lion Rookery in Alaska
Sea Lion Rookery in Alaska
Published: 2009/10/07
Channel: John Swanson
Territorial Steller Sea Lions in Alaska
Territorial Steller Sea Lions in Alaska
Published: 2016/09/23
Channel: MyLife3636
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WIKIPEDIA ARTICLE

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Steller sea lion
Steller sea lions (Eumetopias jubatus) on rocks.jpg
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Suborder: Caniformia
Clade: Pinnipedia
Family: Otariidae
Genus: Eumetopias
Gill, 1866
Species: E. jubatus
Binomial name
Eumetopias jubatus
Schreber, 1776
Eumetopias jubatus distribution2.jpg
Range of Steller sea lions (purple = overall range, red = breeding rookeries)

The Steller sea lion (Eumetopias jubatus) also known as the northern sea lion and Steller's sea lion, is a near threatened species of sea lions in the northern Pacific. It is the sole member of the genus Eumetopias and the largest of the eared seals (Otariidae). Among pinnipeds, it is inferior in size only to the walrus and the two elephant seals. The species is named for the naturalist Georg Wilhelm Steller, who first described them in 1741. The Steller sea lion has attracted considerable attention in recent decades due to significant, unexplained declines in their numbers over a large portion of their range in Alaska.

Description[edit]

Steller sea lion skull

Adult animals are lighter in color than most sea lions, ranging from pale yellow to tawny and occasionally reddish. Steller sea lion pups are born almost black, weighing around 23 kg (51 lb), and remain dark for several months. Females and males both grow rapidly until the fifth year, after which female growth slows considerably. Adult females measure 2.3–2.9 m (7.5–9.5 ft) in length, with an average of 2.5 m (8.2 ft), and weigh 240–350 kg (530–770 lb), with an average of 263 kg (580 lb).[2][3] Males continue to grow until their secondary sexual traits appear in their fifth to eighth year. Males are slightly longer than the females; they grow to about 2.82–3.25 m (9.3–10.7 ft) long, with an average of 3 m (9.8 ft).[4] Males have much wider chests, necks, and general forebody structure and weigh 450–1,120 kg (990–2,470 lb), with an average of 544 kg (1,199 lb).[5][6][7] Males are further distinguished from females by broader, higher foreheads, flatter snouts, and thick mane of coarse hair[8] around their large necks. Indeed, their Latin name translates roughly as "maned one with the broad forehead".

Ecology[edit]

Relative sizes of sleeping Steller sea lion pup, adult female, and male on Yamsky Islands in the northeast Sea of Okhotsk

The range of the Steller sea lion extends from the Kuril Islands and the Sea of Okhotsk in Russia to the Gulf of Alaska in the north, and south to Año Nuevo Island off central California. They formerly bred as far south as the Channel Islands, but have not been observed there since the 1980s. Based on genetic anаlyses and local migration patterns, the global Steller sea lion population has traditionally been divided into an eastern and western stock at 144°W longitude, roughly through the middle of the Gulf of Alaska.[9][10] Recent evidence suggests the sea lions in Russia in the Sea of Okhotsk and the Kuril Islands comprise a third Asian stock, while the sea lions on the eastern seaboard of Kamchatka and the Commander Islands belong to the western stock.

Steller sea lions congregate on rocks in the Gulf Islands of British Columbia
Adult bull, females, and pups near Juneau, Alaska

In the summer, Steller sea lions tend to shift their range somewhat southward. Thus, though no reproductive rookeries are in Japan, several consistent haulouts are found around Hokkaidō in the winter and spring. Vagrants have been spotted in the Yellow Sea and Bohai Gulf and along the coast of Korea and China.[1][11]

Steller sea lions are skilled and opportunistic marine predators, feeding on a wide range of fish and cephalopod species. Important diet components include walleye pollock,[12][13] Atka mackerel,[12] halibut,[13] herring, capelin,[14] flatfish[14][15] Pacific cod,[12][13] rockfish,[14][15] sculpins,[14] and cephalopods.[12] They seem to prefer schooling fish and remain primarily between intertidal zones and continental shelves. They are also known to enter estuarine environments and feed on some brackishwater fish such as sturgeon. Very occasionally, they have been known to prey on northern fur seals, harbor seals, and sea otter pups. They are near the top of the marine food chain, but are susceptible to predation by killer whales and great white sharks.

Reproductive behavior and life history[edit]

Reproductively mature male sea lions aggregate in May on traditional, well-defined reproductive rookeries,[16][17] usually on beaches on isolated islands. The larger, older males establish and defend distinct territories on the rookery.[16][17] A week or so later, adult females arrive, accompanied occasionally by sexually immature offspring, and form fluid aggregations throughout the rookery. Like all other otariids, Steller sea lions are polygynous. However, unlike some other species, they do not coerce individual females into harems, but control spatial territories among which females freely move about.[16] Steller sea lions have used aquatic, semiaquatic, and terrestrial territories. Males with semiaquatic territories have the most success in defending them.[17] The boundaries are defined by natural features, such as rocks, faults, or ridges in rocks, and territories can remain stable for 60 days.[16] Though Steller sea lion males are generally tolerant of pups, one male filmed on Medny Island in Russia was documented killing and eating several pups in a first ever recorded incident of cannibalism. Though researchers are uncertain as to the motives or reasons behind said attacks, it is suggested that the bull involved may have an abnormal personality akin to being psychotic.[18]

Steller sea lion pup (Kuril Islands, Russia)

Pregnant females give birth soon after arriving on a rookery, and copulation generally occurs one to two weeks after giving birth,[16][17] but the fertilized egg does not become implanted in the uterus until the fall. Twins are rare.[19] After a week or so of nursing without leaving the rookery, females begin to take progressively longer and more frequent foraging trips, leaving their pups behind, until at some point in late summer the mother and pup both leave the rookery. Reproductive males fast throughout the reproductive season,[20] often without entering the water once from mid-May until August, when the structure of the reproductive rookeries begins to fall apart and most animals leave for the open seas and disperse throughout their range.

The age at weaning is highly variable; pups may remain with their mothers for as long as four years. Incidents of mothers feeding daughters that are simultaneously feeding their own newborn pups have been documented, an extremely rare occurrence among mammals.

Interactions with humans[edit]

Steller sea lions haul out on Amak Island
Steller sea lions near Vancouver Island

Steller sea lion were hunted for meat and other commodities by prehistoric communities everywhere their range intersected with human communities.[1] Aside from food and clothing, their skin was used to cover baidarkas and kayaks. A subsistence harvest on the order of 300 animals or less continues to this day in some native communities in Alaska.[1]

Historically, the sea lion has had only very slight commercial value. For example, in the 19th century, their whiskers sold for a penny apiece for use as tobacco-pipe cleaners.[21]

Steller sea lions are sometimes killed intentionally by fishermen,[1] as they are seen as competitors and a threat to fish stocks.[1] Killing sea lions is strictly prohibited in the U.S.A. and Russia, but in Japan, a fixed number are still removed annually, ostensibly to protect their fisheries. In Canada, commercial hunting is prohibited, but limited hunting permits are occasionally granted if local culling is required; for example nuisance animals destroying fish farms.[citation needed]

In recent years, Steller sea lions have been known to enter the Columbia River estuary and feed on white sturgeon, several salmon species and rainbow trout, some of which are also listed under the U.S. Endangered Species Act. They enter the Columbia River primarily in the late winter and spring, occasionally going as far upstream as Bonneville Dam.[22] Though not as abundant as the California sea lion, they are still a concern for those agencies charged with managing the fish populations. Since the Steller sea lions are themselves protected under the Marine Mammal Protection Act,[1] managers are compelled to use nonlethal deterrence methods, such as rubber bullets and noisemakers. Deterrence by the public is strictly forbidden.

Steller sea lion releasing air underwater

Recent decline and subsequent recovery[edit]

While the populations of the eastern and Asian stocks appear stable, the population of the western stock, particularly along the Aleutian Islands, was estimated to have fallen by 70–80% since the 1970s. As a consequence, in 1997, the western stock of Steller sea lions was listed as endangered and the eastern stock was listed as threatened under the Endangered Species Act.[23][24] They have since been the object of intense study and the focus of much political and scientific debate in Alaska.

One suspected cause of their precipitous decline was overfishing of Alaska pollock, herring, and other fish stocks in the Gulf of Alaska. This stems largely from the “junk-food hypothesis” representing a shift in their diet from fatty herring and capelin to leaner fare such as pollock and flounder, thereby limiting their ability to consume and store fat.[25] Other hypotheses include increased predation by orcas[26] and sharks,[27] indirect effects of prey species composition shifts due to changes in climate, effects of disease or contaminants, shooting by fishermen, and others. The decline is certainly due to a complex of interrelated factors which have yet to be defined by the research effort.[28][29]

In October 2013, the eastern Steller sea lion was taken off the U.S. Endangered Species List after a major population comeback over the past several years.[30]

References[edit]

  1. ^ a b c d e f g Gelatt, T. and Sweeney, K. (2016). Eumetopias jubatus. The IUCN Red List of Threatened Species doi:10.2305/IUCN.UK.2016-1.RLTS.T8239A45225749.en
  2. ^ Steller Sea Lions, Eumetopias jubatus. marinebio.org
  3. ^ Steller Sea Lions. Northwest Regional Office. noaa.gov
  4. ^ Loughlin, Thomas R; Perez, Michael A; Merrick, Richard L (1987). "Eumetopias jubatus" (PDF). Mammalian Species. 283 (283): 1–7. JSTOR 3503908. doi:10.2307/3503908. 
  5. ^ Kindersley, Dorling (2001). Animal. New York City: DK Publishing. ISBN 0-7894-7764-5. 
  6. ^ Keranen, Danielle. Eumetopias jubatus. Steller sea lion. Animal Diversity Web
  7. ^ Olesiuk, Peter F, and Bigg, Michael A. (~1984) Marine mammals in British Columbia.
  8. ^ "Steller Sea Lion (Eumetopias jubatus)". NOAA Fisheries. Retrieved 21 May 2017. 
  9. ^ Alaska Marine Mammal Stock Assessments, 2009. (PDF) . Retrieved on 2011-09-16.
  10. ^ Allen, B. M., and R. P. Angliss (revised 25 November 2008) NOAA-TM-AFSC-206. STELLER SEA LION (Eumetopias jubatus): Eastern U. S. Stock. (PDF).
  11. ^ "Steller Sea Lion (Eumetopias jubatus)" Seal Conservation Society Accessed 2013-04-25
  12. ^ a b c d Sinclair, E. H.; Zeppelin, T. K. (2002). "Seasonal and Spatial Differences in Diet in the Western Stock of Steller Sea Lions (Eumetopias jubatus)". Journal of Mammalogy. 83 (4): 973–990. JSTOR 1383503. doi:10.1644/1545-1542(2002)083<0973:SASDID>2.0.CO;2. 
  13. ^ a b c Keyes, M. C. (1968). "The nutrition of pinnipeds", pp. 359–395 in R. J. Harrison, R. C. Hubbard, R. S. Peterson, C. E. Rice, and R. J. Schusterman (eds.) The behavior and physiology of pinnipeds. Appleton, Century-Crofts, New York.
  14. ^ a b c d Mathisen, O. A.; Baade, R. T.; Lopp, R. J. (1962). "Breeding Habits, Growth and Stomach Contents of the Steller Sea Lion in Alaska". Journal of Mammalogy. 43 (4): 469–477. JSTOR 1376909. doi:10.2307/1376909. 
  15. ^ a b Fiscus, C. H.; Baines, G. A. (1966). "Food and Feeding Behavior of Steller and California Sea Lions". Journal of Mammalogy. 47 (2): 195–200. JSTOR 1378115. doi:10.2307/1378115. 
  16. ^ a b c d e Gentry, R. L. (1970). "Social Behavior of the Steller’s Sea Lion". Ph. D. Thesis, University of California, Santa Cruz, CA.
  17. ^ a b c d Sandergen, F. E. (1970). 'Breeding and Maternal Behavior of the Steller’s Sea Lion (Eumetopias jubatus) in Alaska', M. S. Thesis, University of Alaska, College.
  18. ^ http://news.nationalgeographic.com/2017/08/sea-lions-cannibalism-russia-killing/
  19. ^ Alaska Department of Fish and Game, "Life History". Adfg.alaska.gov. Retrieved on 2011-12-17.
  20. ^ Riedman, M. (1990). The Pinnipeds: Seals, Sea lions, and Walruses. Los Angeles, University of California Press. p. 200 ISBN 0-520-06497-6.
  21. ^ Haynes, Terry L. and Mishler, Craig (1991) The subsistence harvest and use of Steller sea lions in Alaska. Technical paper no. 198. Alaska Dept. of Fish and Game, Division of Subsistence. Juneau, Alaska
  22. ^ Seal & Sea Lion Facts of the Columbia River & Adjacent Nearshore Marine Areas (PDF), NOAA, March 2008 
  23. ^ Steller Sea Lion. US National Marine Fisheries Service .
  24. ^ Steller sea lion (Eumetopias jubatus). U.S. Fish & Wildlife Service.
  25. ^ Biodiversity: Pity the copepod. The Economist (2012-06-16). Retrieved on 2012-10-27.
  26. ^ Horning, M; Mellish, J. A. (2012). "Predation on an Upper Trophic Marine Predator, the Steller Sea Lion: Evaluating High Juvenile Mortality in a Density Dependent Conceptual Framework". PLoS ONE. 7 (1): e30173. PMC 3260237Freely accessible. PMID 22272296. doi:10.1371/journal.pone.0030173. 
  27. ^ Horning, Markus; Mellish, Jo-Ann E. (2014). "In cold blood: evidence of Pacific sleeper shark (Somniosus pacificus) predation on Steller sea lions (Eumetopias jubatus) in the Gulf of Alaska". Fishery Bulletin. 112 (4): 297. doi:10.7755/FB.112.4.6. 
  28. ^ Clover, Charles. 2004. The End of the Line: How overfishing is changing the world and what we eat. Ebury Press, London. ISBN 0-09-189780-7
  29. ^ Dalton, Rex (2005). "Is this any way to save a species?". Nature. 436 (7047): 14–6. PMID 16001032. doi:10.1038/436014a. 
  30. ^ "Sea Lion Species Removed from Endangered Species List". Yahoo News. Retrieved 27 October 2013. 

Further reading[edit]

  • Heptner, V. G.; Nasimovich, A. A; Bannikov, Andrei Grigorevich; Hoffmann, Robert S, Mammals of the Soviet Union, Volume II, part 3. Washington, D.C. : Smithsonian Institution Libraries and National Science Foundation

External links[edit]

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