Beluga whale: Difference between revisions
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The '''Beluga''' or '''White Whale''' (''Delphinapterus leucas'') is an [[Arctic]] and sub-Arctic species of [[cetacean]]. It is one of two members of the family [[Monodontidae]], along with the [[Narwhal]]. This [[marine mammal]] is commonly referred to simply as the '''Beluga''' or '''Sea Canary''' due to its high-pitched twitter.<ref>Harris, Patricia; Lyon, David; (April 8, 2007) [[Boston Globe]] ''[http://news.google.com/archivesearch?hl=en&um=1&ie=UTF-8&tab=wn&q=the+high-pitched+twitter+of+beluga+whales+(aptly+nicknamed+%22canaries+of+the+sea%22), Enter close quarters: colonial to nuclear subs.]'' Section: Travel; Page 8M.</ref> It is up to 5 m (15 ft) in length and an unmistakable all |
The '''Beluga''' or '''White Whale''' (''Delphinapterus leucas'') is an [[Arctic]] and sub-Arctic species of [[cetacean]]. It is one of two members of the family [[Monodontidae]], along with the [[Narwhal]]. This [[marine mammal]] is commonly referred to simply as the '''Beluga''' or '''Sea Canary''' due to its high-pitched twitter.<ref>Harris, Patricia; Lyon, David; (April 8, 2007) [[Boston Globe]] ''[http://news.google.com/archivesearch?hl=en&um=1&ie=UTF-8&tab=wn&q=the+high-pitched+twitter+of+beluga+whales+(aptly+nicknamed+%22canaries+of+the+sea%22), Enter close quarters: colonial to nuclear subs.]'' Section: Travel; Page 8M.</ref> It is up to 5 m (15 ft) in length and an unmistakable all-white color with a distinctive protuberance on the head. Belugas from the [[Cook Inlet]] in [[Alaska]] have been placed under the protection of the [[Endangered Species Act]] by the U.S. federal government.<ref name="reuters"/> |
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==Taxonomy and evolution== |
==Taxonomy and evolution== |
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The earliest known ancestor of the Beluga is the prehistoric ''[[Denebola brachycephala]]'' from the late [[Miocene]] period. One single fossil has been found on the [[Baja California peninsula]], indicating that the family once existed in warmer waters. The fossil record also indicates that in comparatively recent times the Beluga's range has varied with that of the ice pack–expanding during [[ice age]]s and contracting when the ice retreats. |
The earliest known ancestor of the Beluga is the prehistoric ''[[Denebola brachycephala]]'' from the late [[Miocene]] period. One single fossil has been found on the [[Baja California peninsula]], indicating that the family once existed in warmer waters. The fossil record also indicates that in comparatively recent times the Beluga's range has varied with that of the ice pack–expanding during [[ice age]]s and contracting when the ice retreats. |
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The [[Red List of Threatened Species]] gives both Beluga and White Whale as common names, though the former is now more popular. The English name comes from the [[Russian language|Russian]] белуга (''beluga'') or белуха (''belukha'') which derives from the word белый (''belyy''), meaning "white". It is sometimes referred to by scientists as the Belukha Whale in order to avoid confusion with the [[beluga sturgeon]]. The whale is also colloquially known as the Sea Canary on account of the high-pitched squeaks, squeals, clucks and whistles. |
The [[Red List of Threatened Species]] gives both Beluga and White Whale as common names, though the former is now more popular. The English name comes from the [[Russian language|Russian]] белуга (''beluga'') or белуха (''belukha''), which derives from the word белый (''belyy''), meaning "white". It is sometimes referred to by scientists as the Belukha Whale in order to avoid confusion with the [[beluga sturgeon]]. The whale is also colloquially known as the Sea Canary on account of the high-pitched squeaks, squeals, clucks and whistles. |
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A Japanese researcher says he has taught a Beluga to "talk" by using these sounds to identify three different objects, offering hope that humans may one day be able to hold conversations with sea mammals.<ref>{{cite web | url = http://www.meeja.com.au/index.php?display_article_id=221 | title = Japanese whale whisperer teaches beluga to talk | publisher=www.meeja.com.au | date=2008-09-16 | accessdate=2008-09-16 }}</ref> |
A Japanese researcher says he has taught a Beluga to "talk" by using these sounds to identify three different objects, offering hope that humans may one day be able to hold conversations with sea mammals.<ref>{{cite web | url = http://www.meeja.com.au/index.php?display_article_id=221 | title = Japanese whale whisperer teaches beluga to talk | publisher=www.meeja.com.au | date=2008-09-16 | accessdate=2008-09-16 }}</ref> |
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This whale is unmistakable when adult: it is all white or whitish grey. Calves, however, are usually gray.<ref name=princeton/> The head is unlike that of any other cetacean. Like most [[toothed whales]] it has a [[melon (whale)|melon]], an oily, fatty lump of tissue found at the center of the forehead. But the Beluga's melon is extremely bulbous and even malleable.<ref name="encyc"/> The Beluga is able to change the shape of its head by blowing air around its [[Paranasal sinus|sinuses]]. Again unlike many dolphins and whales, the [[vertebra]]e in the neck are not fused together, allowing the animal flexibility to turn its head laterally. The [[rostrum (anatomy)|rostrum]] has about 8 to 10 teeth on each side of the jaw. |
This whale is unmistakable when adult: it is all white or whitish grey. Calves, however, are usually gray.<ref name=princeton/> The head is unlike that of any other cetacean. Like most [[toothed whales]] it has a [[melon (whale)|melon]], an oily, fatty lump of tissue found at the center of the forehead. But the Beluga's melon is extremely bulbous and even malleable.<ref name="encyc"/> The Beluga is able to change the shape of its head by blowing air around its [[Paranasal sinus|sinuses]]. Again unlike many dolphins and whales, the [[vertebra]]e in the neck are not fused together, allowing the animal flexibility to turn its head laterally. The [[rostrum (anatomy)|rostrum]] has about 8 to 10 teeth on each side of the jaw. |
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It has a dorsal ridge rather than a [[dorsal fin]].<ref name=princeton/> The absence of the dorsal fin is reflected in the genus name of the species - ''apterus'' is the Greek word for "wingless". The evolutionary preference for a dorsal ridge rather than a fin is believed by scientists to be adaptation to under-ice conditions, or possibly as a way of preserving heat.<ref name=encyc/> |
It has a dorsal ridge rather than a [[dorsal fin]].<ref name=princeton/> The absence of the dorsal fin is reflected in the genus name of the species - ''apterus'' is the Greek word for "wingless". The evolutionary preference for a dorsal ridge rather than a fin is believed by scientists to be an adaptation to under-ice conditions, or possibly as a way of preserving heat.<ref name=encyc/> As in other cetaceans, the thyroid gland is relatively large compared to terrestrial mammals (three times per weight as a horse) and may help to sustain higher metabolism during the summer estuarine occupations. |
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The body of the Beluga is round, particularly when well-fed, and tapers less smoothly to the head than the tail; the sudden tapering to the base of the whale's mobile neck gives it the appearance of shoulders, unique among cetaceans. The tail fin grows and becomes increasingly ornately curved as the animal ages. The flippers are broad and short - making them almost square-shaped. |
The body of the Beluga is round, particularly when well-fed, and tapers less smoothly to the head than the tail; the sudden tapering to the base of the whale's mobile neck gives it the appearance of shoulders, unique among cetaceans. The tail fin grows and becomes increasingly ornately curved as the animal ages. The flippers are broad and short - making them almost square-shaped. |
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==Distribution== |
==Distribution== |
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[[Image:Beluga 1 1999-07-03.jpg|thumb||Beluga at the mouth of Churchill River into Hudson Bay, Canada]] |
[[Image:Beluga 1 1999-07-03.jpg|thumb||Beluga at the mouth of Churchill River into Hudson Bay, Canada]] |
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The Beluga inhabits a discontinuous circumpolar distribution in Arctic and sub-Arctic waters ranging from 50° N to 80° N, particularly along the coasts of [[Alaska]], [[Canada]], [[Greenland]] and [[Russia]]. The southernmost extent of the range includes isolated populations in the [[St. Lawrence River]] estuary and the [[Saguenay River|Saguenay fjord]], around the village of [[Tadoussac, Quebec]], in the Atlantic and the [[Amur River]] delta, the [[Shantar Islands]] and the waters surrounding [[Sakhalin Island]] in the [[Sea of Okhotsk]].<ref name="Burkanov">Artyukhin Yu.B. and V.N. Burkanov (1999). Sea birds and mammals of the Russian Far East: a Field Guide, Мoscow: АSТ Publishing – 215 p. {{ru icon}} </ref> |
The Beluga inhabits a discontinuous circumpolar distribution in Arctic and sub-Arctic waters ranging from 50° N to 80° N, particularly along the coasts of [[Alaska]], [[Canada]], [[Greenland]], and [[Russia]]. The southernmost extent of the range includes isolated populations in the [[St. Lawrence River]] estuary and the [[Saguenay River|Saguenay fjord]], around the village of [[Tadoussac, Quebec]], in the Atlantic and the [[Amur River]] delta, the [[Shantar Islands]] and the waters surrounding [[Sakhalin Island]] in the [[Sea of Okhotsk]].<ref name="Burkanov">Artyukhin Yu.B. and V.N. Burkanov (1999). Sea birds and mammals of the Russian Far East: a Field Guide, Мoscow: АSТ Publishing – 215 p. {{ru icon}} </ref> |
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In the spring the Beluga moves to its summer grounds, bays, estuaries and other shallow inlets. These summer sites are detached from one another and a mother will usually return to the same site year after year. As its summer homes become clogged with ice during autumn, the Beluga moves away for winter. Most travel in the direction of the advancing ice-pack and stay close to the edge of it for the winter months. Others stay under the iced area–surviving by finding ice leads and [[polynya]]s (patches of open water in the ice) in which they can surface to breathe. Beluga may also find pockets of air trapped under the ice. The remarkable ability of the Beluga to find the thin slivers of open water where the dense ice pack may cover more than 96% of the sea surface is still a source of mystery and great interest to scientists. It is clear that the [[Animal echolocation|echo-location]] capabilities of the Beluga are highly adapted to the peculiar acoustics of the sub-ice sea and it has been suggested that Beluga can sense open water through echolocation. |
In the spring the Beluga moves to its summer grounds, bays, estuaries and other shallow inlets. These summer sites are detached from one another and a mother will usually return to the same site year after year. As its summer homes become clogged with ice during autumn, the Beluga moves away for winter. Most travel in the direction of the advancing ice-pack and stay close to the edge of it for the winter months. Others stay under the iced area–surviving by finding ice leads and [[polynya]]s (patches of open water in the ice) in which they can surface to breathe. Beluga may also find pockets of air trapped under the ice. The remarkable ability of the Beluga to find the thin slivers of open water where the dense ice pack may cover more than 96% of the sea surface is still a source of mystery and great interest to scientists. It is clear that the [[Animal echolocation|echo-location]] capabilities of the Beluga are highly adapted to the peculiar acoustics of the sub-ice sea and it has been suggested that Beluga can sense open water through echolocation. |
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In |
In 1849, while constructing the first railroad between [[Rutland, Vermont|Rutland]] and [[Burlington, Vermont|Burlington]], [[Vermont]], workers unearthed the bones of a mysterious animal in the town of [[Charlotte, Vermont|Charlotte]]. Buried nearly 10 feet below the surface in a thick blue clay, these bones were unlike those of any animal previously discovered in Vermont. Experts identified the bones as those of a Beluga. Because Charlotte is far inland (over 150 miles from the nearest ocean), early naturalists were at a loss to explain the bones of a marine mammal buried beneath the fields of rural Vermont. Today, the Charlotte whale aids in the study of the geology and the history of the Champlain Basin<ref>http://www.uvm.edu/whale/</ref>, and the Beluga is identified as the official Vermont State Fossil (making Vermont the only state whose official fossil is that of a still extant animal). |
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On |
On June 9, 2006 the carcass of a young Beluga was found in the [[Tanana River]] near [[Fairbanks, Alaska|Fairbanks]] in central Alaska, nearly 1,700 kilometres (1,100 miles) from its nearest natural ocean habitat. As Beluga sometimes follow migrating fish, Alaska state biologist Tom Seaton speculated that it had followed migrating [[salmon]] up the river at some point in the prior fall. |
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==Behavior== |
==Behavior== |
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The Beluga is a highly sociable creature. Groups of males may number in the hundreds, but mothers with calves generally mix in slightly smaller groups. When pods do aggregate in [[Estuary|estuaries]], they may number in the thousands. This can represent a significant proportion of the entire Beluga population and is the time when they are most vulnerable to hunting. |
The Beluga is a highly sociable creature. Groups of males may number in the hundreds, but mothers with calves generally mix in slightly smaller groups. When pods do aggregate in [[Estuary|estuaries]], they may number in the thousands. This can represent a significant proportion of the entire Beluga population and is the time when they are most vulnerable to hunting. |
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Beluga pods tend to be unstable, meaning that Belugas tend to move from pod to pod. Pod membership is rarely permanent. Radio |
Beluga pods tend to be unstable, meaning that Belugas tend to move from pod to pod. Pod membership is rarely permanent. Radio tracking has shown that Belugas can start out in a pod and within a few days be hundreds of miles away from that pod. The closest social relationship between Belugas is the mother-calf relationship. Nursing times of two years have been observed and lactational anestrus may not occur. Calves often return to the same estuary as their mother in the summer, meeting with their mother sometimes even after becoming fully mature. |
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Beluga are also known for being rather playful, as well as spitting at humans or other whales. It is not unusual for an aquarium handler to be sprayed down by one of his charges whilst tending a Beluga tank. Some researchers believe that this skill may be utilized to blow away sand from crustaceans at the sea bottom. Unlike most whales, it is capable of swimming backwards.<ref>{{cite web|title=Georgia Aquarium - Beluga Whale|url=http://www.georgiaaquarium.org/exploreTheAquarium/webcam-beluga.aspx|accessdate=2008-10-12}}</ref> |
Beluga are also known for being rather playful, as well as spitting at humans or other whales. It is not unusual for an aquarium handler to be sprayed down by one of his charges whilst tending a Beluga tank. Some researchers believe that this skill may be utilized to blow away sand from crustaceans at the sea bottom. Unlike most whales, it is capable of swimming backwards.<ref>{{cite web|title=Georgia Aquarium - Beluga Whale|url=http://www.georgiaaquarium.org/exploreTheAquarium/webcam-beluga.aspx|accessdate=2008-10-12}}</ref> |
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===Diet=== |
===Diet=== |
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The Beluga is a slow-swimming [[mammal]] |
The Beluga is a slow-swimming [[mammal]] that feeds mainly on [[fish]]. It also eats [[cephalopod]]s ([[squid]] and [[octopus]]) and [[crustacean]]s ([[crab]] and [[shrimp]]). Foraging on the seabed typically takes place at depths of up to 1,000 feet, but they can dive at least twice this depth. Generally a feeding dive will last 3–5 minutes, but Belugas have been observed submerged for up to 20 minutes at a time.<ref name=MarineBio>{{cite news | url=http://www.marinebio.org/species.asp?id=159 | title=Delphinapterus leucas: Beluga Whale | publisher=[[Marine Bio]] | accessdate=2008-08-26 }} </ref> |
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===Reproduction=== |
===Reproduction=== |
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Calves are born over a protracted period that varies by location. In the Canadian Arctic, calves are born between March and September, while in [[Hudson Bay]] the peak calving period is in late June and in [[Cumberland Sound]] most calves are born from late July to early August.<ref>{{cite journal|title=Spring Sightings of Narwhal and Beluga Calves in Lancaster Sound, N.W.T|author=Cosens, S. & Dueck, L.|date=June 1990|pages=1–2|journal=Arctic|volume=31|issue=2|url=http://pubs.aina.ucalgary.ca/arctic/Arctic43-2-127.pdf}}</ref> |
Calves are born over a protracted period that varies by location. In the Canadian Arctic, calves are born between March and September, while in [[Hudson Bay]] the peak calving period is in late June and in [[Cumberland Sound]] most calves are born from late July to early August.<ref>{{cite journal|title=Spring Sightings of Narwhal and Beluga Calves in Lancaster Sound, N.W.T|author=Cosens, S. & Dueck, L.|date=June 1990|pages=1–2|journal=Arctic|volume=31|issue=2|url=http://pubs.aina.ucalgary.ca/arctic/Arctic43-2-127.pdf}}</ref> |
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Newly |
Newly born calves are about {{convert|1.5|m|ft|lk=on}} long, weigh about {{convert|80|kg|lb|lk=on}}, and are grey in color. The calves remain dependent on their mothers for at least two years. Male Belugas reach sexual maturity between four and seven years, while females reach sexual maturity between six and nine years. The Beluga can live for more than 50 years.<ref name=princeton/> |
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==Population, threats, and human interactions== |
==Population, threats, and human interactions== |
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[[Image:Delphinapterus leucas with hand.jpg|thumb|right]] |
[[Image:Delphinapterus leucas with hand.jpg|thumb|right]] |
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The global population of Beluga today stands at about 100,000. Although this number is much greater than that of other cetaceans, it is much smaller than historical populations before decades of over-hunting. There are estimated to be 40,000 individuals in the [[Beaufort Sea]], 25,045 in [[Hudson Bay]], 18,500 in the [[Bering Sea]] and 28,008 in the Canadian Low Arctic. The population in the St. Lawrence estuary is estimated to be around |
The global population of Beluga today stands at about 100,000. Although this number is much greater than that of other cetaceans, it is much smaller than historical populations before decades of over-hunting. There are estimated to be 40,000 individuals in the [[Beaufort Sea]], 25,045 in [[Hudson Bay]], 18,500 in the [[Bering Sea]], and 28,008 in the Canadian Low Arctic. The population in the St. Lawrence estuary is estimated to be around 1,000.<ref>[http://web.archive.org/web/20080130031849/http://www.wdcs.org/dan/publishing.nsf/allweb/1B8A4EB4B9FA1BBF80256D11004B2EA2 Portrait of endangered beluga whales in Quebec]</ref> It is considered an excellent sentinel species and indicator of the health of, and changes in, the environment. This is because it is long lived, on top of the food web, with large amounts of fat and blubber, relatively well studied for a cetacean, and still somewhat common. |
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The Beluga's natural predators are the [[ |
The Beluga's natural predators are the [[polar bear]], who hunt when the whales become encircled by ice during winter. The bears take particular advantage of situations when Belugas become trapped by ice and are thus unable to reach the ocean. The bears swipe at the Belugas and drag them onto the ice. The [[Orca]] is the other significant natural predator of the Beluga.<ref name=audobon/> |
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Because the Beluga congregates in river estuaries, human-caused pollution is proving to be a significant danger to its health. Incidents of [[cancer]] have been reported to be rising as a result of the [[St. Lawrence River]] pollution. The bodies of the Beluga inhabiting this area contain so many contaminants that their carcasses are treated as toxic waste.{{Citation needed|date=July 2009}} Reproductive pathology has been discovered in the population here and many suspect organochlorines to be responsible. Levels between 240 [[Parts per million|ppm]] and 800 ppm of [[Polychlorinated biphenyl|PCB]]s have been found, with males typically having higher levels.<ref>J Great Lakes Res.,19 & Arch. Environ. Contam. Toxicol.,16 & Sci. Total Environ.,154</ref> It is not known what the long-term effects of this pollution will be on the affected populations. |
Because the Beluga congregates in river estuaries, human-caused pollution is proving to be a significant danger to its health. Incidents of [[cancer]] have been reported to be rising as a result of the [[St. Lawrence River]] pollution. The bodies of the Beluga inhabiting this area contain so many contaminants that their carcasses are treated as toxic waste.{{Citation needed|date=July 2009}} Reproductive pathology has been discovered in the population here and many suspect organochlorines to be responsible. Levels between 240 [[Parts per million|ppm]] and 800 ppm of [[Polychlorinated biphenyl|PCB]]s have been found, with males typically having higher levels.<ref>J Great Lakes Res.,19 & Arch. Environ. Contam. Toxicol.,16 & Sci. Total Environ.,154</ref> It is not known what the long-term effects of this pollution will be on the affected populations. |
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[[Image:Beluga, Weißwal (Delphinapterus leucas).jpg|thumb|left|A Beluga resurfaces]] |
[[Image:Beluga, Weißwal (Delphinapterus leucas).jpg|thumb|left|A Beluga resurfaces]] |
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Belugas were amongst the first whale species to be brought into captivity. The first Beluga was shown at Barnum's Museum in [[New York City |
Belugas were amongst the first whale species to be brought into captivity. The first Beluga was shown at Barnum's Museum in [[New York City]] in 1861. Today it remains one of the few whale species kept at [[Aquarium|aquaria]] and sea life parks across North America, Europe, and Asia. Its popularity there with visitors reflects its attractive color, and its range of facial expressions. While most cetacean "smiles" are fixed, the extra movement afforded by the Beluga's unfused cervical vertebrae allows a greater range of expression. Most Beluga found in aquariums are caught in the wild, though captive breeding programs have enjoyed some success. |
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Indirect human disturbance may also be a threat to the species. While some populations have come to tolerate small boats, others have been known to actively try to avoid ships. [[Whale-watching]] Beluga has become a huge and booming activity in the St. Lawrence and [[Churchill River (Hudson Bay)|Churchill River]] areas. |
Indirect human disturbance may also be a threat to the species. While some populations have come to tolerate small boats, others have been known to actively try to avoid ships. [[Whale-watching]] Beluga has become a huge and booming activity in the St. Lawrence and [[Churchill River (Hudson Bay)|Churchill River]] areas. |
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[[Papillomavirus]]es have been found in the gastric compartments of Belugas in the St. Lawerence River. [[Herpesvirus]] as well has been detected on occasion in Belugas. Encephalitis has sometimes been observed and the protozoa ''Sarcocystis'' can infect the animals. Ciliates have been observed to colonize the blowhole yet may not be pathogenic or especially harmful.<ref>{{cite book|title=CRC Handbook of Marine Mammal Medicine|author=Dierauf, L. & Gulland, F.|page=26, 303, 359|year=2001|publisher=CRC Press|isbn=0849308399}}</ref> |
[[Papillomavirus]]es have been found in the gastric compartments of Belugas in the St. Lawerence River. [[Herpesvirus]] as well has been detected on occasion in Belugas. Encephalitis has sometimes been observed and the protozoa ''Sarcocystis'' can infect the animals. Ciliates have been observed to colonize the blowhole yet may not be pathogenic or especially harmful.<ref>{{cite book|title=CRC Handbook of Marine Mammal Medicine|author=Dierauf, L. & Gulland, F.|page=26, 303, 359|year=2001|publisher=CRC Press|isbn=0849308399}}</ref> |
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''Erysipelothrix rhusiopathiae'' gram positive/variable bacilli, likely from contaminated fish in the diet, can endanger captive Belugas causing [[Anorexia (symptom)|anorexia]], dermal plaques, and lesions. This may lead to death if not diagnosed early and treated with antibiotics.<ref>{{cite book|title=CRC Handbook of Marine Mammal Medicine|author=Dierauf, L. & Gulland, F.|page=316–317|year=2001|publisher=CRC Press|isbn=0849308399}}</ref> |
''Erysipelothrix rhusiopathiae'' gram positive/variable bacilli, likely from contaminated fish in the diet, can endanger captive Belugas, causing [[Anorexia (symptom)|anorexia]], dermal plaques, and lesions. This may lead to death if not diagnosed early and treated with antibiotics.<ref>{{cite book|title=CRC Handbook of Marine Mammal Medicine|author=Dierauf, L. & Gulland, F.|page=316–317|year=2001|publisher=CRC Press|isbn=0849308399}}</ref> |
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==Conservation status== |
==Conservation status== |
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As of 2008, the Beluga is listed as "near threatened" by the [[IUCN]]. This is due to uncertainty about the global number of Belugas over parts of its range (especially the Russian Arctic) and the expectation that if current conservation efforts cease, especially management of hunting, the Beluga population is likely to qualify for "threatened" status within five years. Prior to 2008, the Beluga was listed as "vulnerable", which represented a higher level of concern. The reason given by IUCN for the change in status is that some of the largest subpopulations are not declining and because improved census methods have indicated that the population size is larger than previously estimated.<ref name=iucn>{{IUCN2008| assessors=Jefferson, T.A., Karczmarski, L., Laidre, K., O’Corry-Crowe, G., Reeves, R.R., Rojas-Bracho, L., Secchi, E.R., Slooten, E., Smith, B.D., Wang, J.Y. & Zhou, K.| year=2008| id=6335| title=Delphinapterus leucas |downloaded=[[2008-10-07]]}}</ref> |
As of 2008, the Beluga is listed as "near threatened" by the [[IUCN]]. This is due to uncertainty about the global number of Belugas over parts of its range (especially the Russian Arctic) and the expectation that if current conservation efforts cease, especially management of hunting, the Beluga population is likely to qualify for "threatened" status within five years. Prior to 2008, the Beluga was listed as "vulnerable", which represented a higher level of concern. The reason given by IUCN for the change in status is that some of the largest subpopulations are not declining and because improved census methods have indicated that the population size is larger than previously estimated.<ref name=iucn>{{IUCN2008| assessors=Jefferson, T.A., Karczmarski, L., Laidre, K., O’Corry-Crowe, G., Reeves, R.R., Rojas-Bracho, L., Secchi, E.R., Slooten, E., Smith, B.D., Wang, J.Y. & Zhou, K.| year=2008| id=6335| title=Delphinapterus leucas |downloaded=[[2008-10-07]]}}</ref> |
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Subpopulations are subject to differing levels of threat and warrant individual assessment. The Cook Inlet subpopulation of the Beluga is listed as "Critically Endangered" by the |
Subpopulations are subject to differing levels of threat and warrant individual assessment. The Cook Inlet subpopulation of the Beluga is listed as "Critically Endangered" by the IUCN as of 2006.<ref>{{cite web | url = http://www.iucnredlist.org/details/6335 | title = The IUCN Red List of Threatened Species | publisher = [[International Union for Conservation of Nature and Natural Resources]] | accessdate=2008-10-17}}</ref> The Cook Inlet Beluga population was listed as Endangered under the [[Endangered Species Act]] in October 2008.<ref>{{cite web|url=http://www.nmfs.noaa.gov/pr/pdfs/fr/fr73-62919.pdf|title=Endangered and Threatened Species; Endangered Status for the Cook Inlet Beluga Whale|date=[[2008-10-22]]|publisher=[[National Oceanic and Atmospheric Administration]]|accessdate=2009-08-26}}</ref> <ref name="reuters">{{cite news|url=http://www.reuters.com/article/domesticNews/idUSTRE49G6JD20081017|title=Beluga whales in Alaska listed as endangered|last=Rosen|first=Yereth|date=October 17, 2008|work=[[Reuters]]|accessdate=2008-10-17}}</ref><ref>{{cite news|url=http://ap.google.com/article/ALeqM5gJx0IzvRt6GWrUBb90Foe4URCGagD93SD0DO0|title=Government declares beluga whale endangered|last=Herbert|first=H. Josef|date=October 17, 2008|agency=Associated Press |accessdate=2008-10-17}}</ref> |
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This was due to overharvesting of Beluga's prior to 1998, and the population has failed to show expected signs of recovery even though the reported harvest has been small. The most recent published estimate at the time of the present assessment (May 2008) was 302 (CV=0.16) in 2006 (Angliss and Outlaw 2007). In addition, the [[National Marine Fisheries Service]] had indicated via a web posting that the point estimate from the 2007 aerial survey was 375. |
This was due to overharvesting of Beluga's prior to 1998, and the population has failed to show expected signs of recovery even though the reported harvest has been small. The most recent published estimate at the time of the present assessment (May 2008) was 302 (CV=0.16) in 2006 (Angliss and Outlaw 2007). In addition, the [[National Marine Fisheries Service]] had indicated via a web posting that the point estimate from the 2007 aerial survey was 375. |
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Revision as of 21:10, 7 September 2009
Beluga[1] | |
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Size comparison against an average human | |
Scientific classification | |
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Genus: | Delphinapterus
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Species: | D. leucas
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Binomial name | |
Delphinapterus leucas (Pallas, 1776)
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Beluga range |
The Beluga or White Whale (Delphinapterus leucas) is an Arctic and sub-Arctic species of cetacean. It is one of two members of the family Monodontidae, along with the Narwhal. This marine mammal is commonly referred to simply as the Beluga or Sea Canary due to its high-pitched twitter.[3] It is up to 5 m (15 ft) in length and an unmistakable all-white color with a distinctive protuberance on the head. Belugas from the Cook Inlet in Alaska have been placed under the protection of the Endangered Species Act by the U.S. federal government.[4]
Taxonomy and evolution
The Beluga was first described by Peter Simon Pallas in 1776. It is a member of the Monodontidae family, which is in turn part of the toothed whale suborder.[1] The Irrawaddy Dolphin was also once considered to be in the same family; however, recent genetic evidence suggests otherwise.[5] The only other species within the Monodontidae family besides the Beluga is the Narwhal.[6]
The earliest known ancestor of the Beluga is the prehistoric Denebola brachycephala from the late Miocene period. One single fossil has been found on the Baja California peninsula, indicating that the family once existed in warmer waters. The fossil record also indicates that in comparatively recent times the Beluga's range has varied with that of the ice pack–expanding during ice ages and contracting when the ice retreats.
The Red List of Threatened Species gives both Beluga and White Whale as common names, though the former is now more popular. The English name comes from the Russian белуга (beluga) or белуха (belukha), which derives from the word белый (belyy), meaning "white". It is sometimes referred to by scientists as the Belukha Whale in order to avoid confusion with the beluga sturgeon. The whale is also colloquially known as the Sea Canary on account of the high-pitched squeaks, squeals, clucks and whistles.
A Japanese researcher says he has taught a Beluga to "talk" by using these sounds to identify three different objects, offering hope that humans may one day be able to hold conversations with sea mammals.[7]
Description
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Male Belugas are larger than females. Males can reach 5.5 metres (18 ft) long, while females grow to as much as 4.1 metres (13 ft).[8] Males weigh between 1,100 and 1,600 kilograms (2,400 and 3,500 lb) while females weigh between 700 and 1,200 kilograms (1,500 and 2,600 lb).[9] This is larger than all but the largest dolphins but smaller than most other toothed whales.
This whale is unmistakable when adult: it is all white or whitish grey. Calves, however, are usually gray.[8] The head is unlike that of any other cetacean. Like most toothed whales it has a melon, an oily, fatty lump of tissue found at the center of the forehead. But the Beluga's melon is extremely bulbous and even malleable.[6] The Beluga is able to change the shape of its head by blowing air around its sinuses. Again unlike many dolphins and whales, the vertebrae in the neck are not fused together, allowing the animal flexibility to turn its head laterally. The rostrum has about 8 to 10 teeth on each side of the jaw.
It has a dorsal ridge rather than a dorsal fin.[8] The absence of the dorsal fin is reflected in the genus name of the species - apterus is the Greek word for "wingless". The evolutionary preference for a dorsal ridge rather than a fin is believed by scientists to be an adaptation to under-ice conditions, or possibly as a way of preserving heat.[6] As in other cetaceans, the thyroid gland is relatively large compared to terrestrial mammals (three times per weight as a horse) and may help to sustain higher metabolism during the summer estuarine occupations.
The body of the Beluga is round, particularly when well-fed, and tapers less smoothly to the head than the tail; the sudden tapering to the base of the whale's mobile neck gives it the appearance of shoulders, unique among cetaceans. The tail fin grows and becomes increasingly ornately curved as the animal ages. The flippers are broad and short - making them almost square-shaped.
Distribution
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The Beluga inhabits a discontinuous circumpolar distribution in Arctic and sub-Arctic waters ranging from 50° N to 80° N, particularly along the coasts of Alaska, Canada, Greenland, and Russia. The southernmost extent of the range includes isolated populations in the St. Lawrence River estuary and the Saguenay fjord, around the village of Tadoussac, Quebec, in the Atlantic and the Amur River delta, the Shantar Islands and the waters surrounding Sakhalin Island in the Sea of Okhotsk.[10]
In the spring the Beluga moves to its summer grounds, bays, estuaries and other shallow inlets. These summer sites are detached from one another and a mother will usually return to the same site year after year. As its summer homes become clogged with ice during autumn, the Beluga moves away for winter. Most travel in the direction of the advancing ice-pack and stay close to the edge of it for the winter months. Others stay under the iced area–surviving by finding ice leads and polynyas (patches of open water in the ice) in which they can surface to breathe. Beluga may also find pockets of air trapped under the ice. The remarkable ability of the Beluga to find the thin slivers of open water where the dense ice pack may cover more than 96% of the sea surface is still a source of mystery and great interest to scientists. It is clear that the echo-location capabilities of the Beluga are highly adapted to the peculiar acoustics of the sub-ice sea and it has been suggested that Beluga can sense open water through echolocation.
In 1849, while constructing the first railroad between Rutland and Burlington, Vermont, workers unearthed the bones of a mysterious animal in the town of Charlotte. Buried nearly 10 feet below the surface in a thick blue clay, these bones were unlike those of any animal previously discovered in Vermont. Experts identified the bones as those of a Beluga. Because Charlotte is far inland (over 150 miles from the nearest ocean), early naturalists were at a loss to explain the bones of a marine mammal buried beneath the fields of rural Vermont. Today, the Charlotte whale aids in the study of the geology and the history of the Champlain Basin[11], and the Beluga is identified as the official Vermont State Fossil (making Vermont the only state whose official fossil is that of a still extant animal).
On June 9, 2006 the carcass of a young Beluga was found in the Tanana River near Fairbanks in central Alaska, nearly 1,700 kilometres (1,100 miles) from its nearest natural ocean habitat. As Beluga sometimes follow migrating fish, Alaska state biologist Tom Seaton speculated that it had followed migrating salmon up the river at some point in the prior fall.
Behavior
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The Beluga is a highly sociable creature. Groups of males may number in the hundreds, but mothers with calves generally mix in slightly smaller groups. When pods do aggregate in estuaries, they may number in the thousands. This can represent a significant proportion of the entire Beluga population and is the time when they are most vulnerable to hunting.
Beluga pods tend to be unstable, meaning that Belugas tend to move from pod to pod. Pod membership is rarely permanent. Radio tracking has shown that Belugas can start out in a pod and within a few days be hundreds of miles away from that pod. The closest social relationship between Belugas is the mother-calf relationship. Nursing times of two years have been observed and lactational anestrus may not occur. Calves often return to the same estuary as their mother in the summer, meeting with their mother sometimes even after becoming fully mature.
Beluga are also known for being rather playful, as well as spitting at humans or other whales. It is not unusual for an aquarium handler to be sprayed down by one of his charges whilst tending a Beluga tank. Some researchers believe that this skill may be utilized to blow away sand from crustaceans at the sea bottom. Unlike most whales, it is capable of swimming backwards.[12]
Diet
The Beluga is a slow-swimming mammal that feeds mainly on fish. It also eats cephalopods (squid and octopus) and crustaceans (crab and shrimp). Foraging on the seabed typically takes place at depths of up to 1,000 feet, but they can dive at least twice this depth. Generally a feeding dive will last 3–5 minutes, but Belugas have been observed submerged for up to 20 minutes at a time.[13]
Reproduction
Female Belugas generally give birth every three years.[8] Most mating occurs between February and May, but some mating does occur at other times of year.[6][8] It is questionable whether the Beluga can have delayed implantation.[6] The gestation period is 12 to 14 1/2 months.[8]
Calves are born over a protracted period that varies by location. In the Canadian Arctic, calves are born between March and September, while in Hudson Bay the peak calving period is in late June and in Cumberland Sound most calves are born from late July to early August.[14]
Newly born calves are about 1.5 metres (4.9 ft) long, weigh about 80 kilograms (180 lb), and are grey in color. The calves remain dependent on their mothers for at least two years. Male Belugas reach sexual maturity between four and seven years, while females reach sexual maturity between six and nine years. The Beluga can live for more than 50 years.[8]
Population, threats, and human interactions
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The global population of Beluga today stands at about 100,000. Although this number is much greater than that of other cetaceans, it is much smaller than historical populations before decades of over-hunting. There are estimated to be 40,000 individuals in the Beaufort Sea, 25,045 in Hudson Bay, 18,500 in the Bering Sea, and 28,008 in the Canadian Low Arctic. The population in the St. Lawrence estuary is estimated to be around 1,000.[15] It is considered an excellent sentinel species and indicator of the health of, and changes in, the environment. This is because it is long lived, on top of the food web, with large amounts of fat and blubber, relatively well studied for a cetacean, and still somewhat common.
The Beluga's natural predators are the polar bear, who hunt when the whales become encircled by ice during winter. The bears take particular advantage of situations when Belugas become trapped by ice and are thus unable to reach the ocean. The bears swipe at the Belugas and drag them onto the ice. The Orca is the other significant natural predator of the Beluga.[9]
Because the Beluga congregates in river estuaries, human-caused pollution is proving to be a significant danger to its health. Incidents of cancer have been reported to be rising as a result of the St. Lawrence River pollution. The bodies of the Beluga inhabiting this area contain so many contaminants that their carcasses are treated as toxic waste.[citation needed] Reproductive pathology has been discovered in the population here and many suspect organochlorines to be responsible. Levels between 240 ppm and 800 ppm of PCBs have been found, with males typically having higher levels.[16] It is not known what the long-term effects of this pollution will be on the affected populations.
Belugas were amongst the first whale species to be brought into captivity. The first Beluga was shown at Barnum's Museum in New York City in 1861. Today it remains one of the few whale species kept at aquaria and sea life parks across North America, Europe, and Asia. Its popularity there with visitors reflects its attractive color, and its range of facial expressions. While most cetacean "smiles" are fixed, the extra movement afforded by the Beluga's unfused cervical vertebrae allows a greater range of expression. Most Beluga found in aquariums are caught in the wild, though captive breeding programs have enjoyed some success.
Indirect human disturbance may also be a threat to the species. While some populations have come to tolerate small boats, others have been known to actively try to avoid ships. Whale-watching Beluga has become a huge and booming activity in the St. Lawrence and Churchill River areas.
Because of its predictable migration pattern and high concentrations, the Beluga has been hunted by indigenous Arctic peoples for centuries. In many areas, a pattern of hunting, believed to be sustainable, continues to this day. However, in other areas, such as the Cook Inlet, Ungava Bay, and off west Greenland, previous commercial catches left the populations in great peril. Indigenous whaling continues in these areas, and some populations continue to decline. These areas are the subject of intensive dialogue between Inuit communities and national governments aiming to create a sustainable hunt.
Both the United States Navy and the Russian Navy have used Belugas in anti-mining operations in Arctic waters.[17]
Pathogens
Papillomaviruses have been found in the gastric compartments of Belugas in the St. Lawerence River. Herpesvirus as well has been detected on occasion in Belugas. Encephalitis has sometimes been observed and the protozoa Sarcocystis can infect the animals. Ciliates have been observed to colonize the blowhole yet may not be pathogenic or especially harmful.[18]
Erysipelothrix rhusiopathiae gram positive/variable bacilli, likely from contaminated fish in the diet, can endanger captive Belugas, causing anorexia, dermal plaques, and lesions. This may lead to death if not diagnosed early and treated with antibiotics.[19]
Conservation status
![](http://upload.wikimedia.org/wikipedia/commons/thumb/6/68/Faroe_stamp_329_white_whale_%28Delphinapterus_leucas%29.jpg/220px-Faroe_stamp_329_white_whale_%28Delphinapterus_leucas%29.jpg)
As of 2008, the Beluga is listed as "near threatened" by the IUCN. This is due to uncertainty about the global number of Belugas over parts of its range (especially the Russian Arctic) and the expectation that if current conservation efforts cease, especially management of hunting, the Beluga population is likely to qualify for "threatened" status within five years. Prior to 2008, the Beluga was listed as "vulnerable", which represented a higher level of concern. The reason given by IUCN for the change in status is that some of the largest subpopulations are not declining and because improved census methods have indicated that the population size is larger than previously estimated.[2]
Subpopulations are subject to differing levels of threat and warrant individual assessment. The Cook Inlet subpopulation of the Beluga is listed as "Critically Endangered" by the IUCN as of 2006.[20] The Cook Inlet Beluga population was listed as Endangered under the Endangered Species Act in October 2008.[21] [4][22] This was due to overharvesting of Beluga's prior to 1998, and the population has failed to show expected signs of recovery even though the reported harvest has been small. The most recent published estimate at the time of the present assessment (May 2008) was 302 (CV=0.16) in 2006 (Angliss and Outlaw 2007). In addition, the National Marine Fisheries Service had indicated via a web posting that the point estimate from the 2007 aerial survey was 375.
See also
- Baby Beluga, a song and album by children's singer Raffi
- Airbus Beluga, a cargo aircraft.
- Pour la suite du monde, a documentary about traditional Beluga hunting on the Saint Lawrence River
References
- ^ a b Mead, J. G.; Brownell, R. L. Jr. (2005). "Order Cetacea". In Wilson, D. E.; Reeder, D. M. (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. pp. 723–743. ISBN 978-0-8018-8221-0. OCLC 62265494.
- ^ a b Template:IUCN2008
- ^ Harris, Patricia; Lyon, David; (April 8, 2007) Boston Globe Enter close quarters: colonial to nuclear subs. Section: Travel; Page 8M.
- ^ a b Rosen, Yereth (October 17, 2008). "Beluga whales in Alaska listed as endangered". Reuters. Retrieved 2008-10-17.
- ^ Arnold, P. (2002). "Irrawaddy Dolphin Orcaella brevirostris". In Perrin, W., Würsig B. and Thewissen, J. (ed.). Encyclopedia of Marine Mammals. Academic Press. p. 652. ISBN 0-12-551340-2.
{{cite book}}
: CS1 maint: multiple names: editors list (link) - ^ a b c d e O'Corry-Crowe, G. (2002). "Beluga Whale Delphinapterus leucas". In Perrin, W., Würsig B. and Thewissen, J. (ed.). Encyclopedia of Marine Mammals. Academic Press. p. 94-99. ISBN 0-12-551340-2.
{{cite book}}
: CS1 maint: multiple names: editors list (link) - ^ "Japanese whale whisperer teaches beluga to talk". www.meeja.com.au. 2008-09-16. Retrieved 2008-09-16.
- ^ a b c d e f g Shirihai, H. & Jarrett, B. (2006). Whales, Dolphins and Other Marine Mammals of the World. Princeton: Princeton Univ. Press. p. 97–100. ISBN 0-69112757-3.
{{cite book}}
: CS1 maint: multiple names: authors list (link) - ^ a b Reeves, R., Stewart, B., Clapham, P. & Powell, J. (2003). Guide to Marine Mammals of the World. New York: A.A. Knopf. p. 318–321. ISBN 0-375-41141-0.
{{cite book}}
: CS1 maint: multiple names: authors list (link) - ^ Artyukhin Yu.B. and V.N. Burkanov (1999). Sea birds and mammals of the Russian Far East: a Field Guide, Мoscow: АSТ Publishing – 215 p. Template:Ru icon
- ^ http://www.uvm.edu/whale/
- ^ "Georgia Aquarium - Beluga Whale". Retrieved 2008-10-12.
- ^ "Delphinapterus leucas: Beluga Whale". Marine Bio. Retrieved 2008-08-26.
- ^ Cosens, S. & Dueck, L. (June 1990). "Spring Sightings of Narwhal and Beluga Calves in Lancaster Sound, N.W.T" (PDF). Arctic. 31 (2): 1–2.
{{cite journal}}
: CS1 maint: multiple names: authors list (link) - ^ Portrait of endangered beluga whales in Quebec
- ^ J Great Lakes Res.,19 & Arch. Environ. Contam. Toxicol.,16 & Sci. Total Environ.,154
- ^ "The Story of Navy Dolphins". PBS. Retrieved 2008-10-12.
- ^ Dierauf, L. & Gulland, F. (2001). CRC Handbook of Marine Mammal Medicine. CRC Press. p. 26, 303, 359. ISBN 0849308399.
{{cite book}}
: CS1 maint: multiple names: authors list (link) - ^ Dierauf, L. & Gulland, F. (2001). CRC Handbook of Marine Mammal Medicine. CRC Press. p. 316–317. ISBN 0849308399.
{{cite book}}
: CS1 maint: multiple names: authors list (link) - ^ "The IUCN Red List of Threatened Species". International Union for Conservation of Nature and Natural Resources. Retrieved 2008-10-17.
- ^ "Endangered and Threatened Species; Endangered Status for the Cook Inlet Beluga Whale" (PDF). National Oceanic and Atmospheric Administration. 2008-10-22. Retrieved 2009-08-26.
{{cite web}}
: Check date values in:|date=
(help) - ^ Herbert, H. Josef (October 17, 2008). "Government declares beluga whale endangered". Associated Press. Retrieved 2008-10-17.
Further reading
- Outridge, P. M., K. A. Hobson, R. McNeely, and A. Dyke. 2002. "A Comparison of Modern and Preindustrial Levels of Mercury in the Teeth of Beluga in the Mackenzie Delta, Northwest Territories, and Walrus at Igloolik, Nunavut, Canada". Arctic. 55: 123-132.
External links
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