Table of Contents
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Overview
Brief Summary
Description
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Mammal Species of the World
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- Original description: Pallas, P.S., 1776. Reise durch verschiedene Provinzen des Russischen Reichs, p. 85. St. Petersbourg, viii, Pt. 2, nxxvi.
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Biology
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Comprehensive Description
Biology
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Arctic Ocean Diversity
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Description
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Distribution
Range Description
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Range Description
Population Identity:
Based on studies of mitochondrial DNA, Cook Inlet belugas are genetically distinct from the other four Beluga subpopulations that occur in western and northern Alaska (O?Corry-Crowe et al. 1997, G. O?Corry-Crowe pers. comm.). There have been only two Beluga sightings recorded in the region between Cook Inlet and the nearest Beluga subpopulation in Bristol Bay (Frost and Lowry 1990, Laidre et al. 2000), suggesting that the 900 km long Alaska Peninsula is an effective barrier to movement and that the Cook Inlet subpopulation is geographically and reproductively isolated from Beluga subpopulations to the west (see Figure 1 in the attached PDF). A thorough review of survey effort in the Gulf of Alaska (Laidre et al. 2000) produced regular sightings of belugas in only two regions, Cook Inlet and Yakutat Bay. The Beluga group in Yakutat Bay is very small, probably numbering only 10?20 individuals (Laidre et al. 2000, O'Corry-Crowe et al. 2006). The demographic and genetic relationships between belugas in Cook Inlet and Yakutat Bay are currently poorly known, but since animals are seen in both areas year round (Hubbard et al. 1999, Moore et al. 2000, Laidre et al. 2000) and there have been very few sightings in the intervening 700 km long region (Laidre et al. 2000) it is possible that the Cook Inlet subpopulation is also isolated from the whales in Yakutat Bay. The occurrence of belugas in Yakutat Bay will not be considered further in this evaluation.
Dedicated aerial surveys for belugas have been conducted mostly in the summer concentration areas, Yakutat Bay and Cook Inlet. However, the adjacent and intervening areas of the Gulf of Alaska are frequently surveyed by marine mammal researchers studying other species, and are regularly traversed by fishermen and other coastal residents who commonly report unusual marine mammal sightings. We consider the lack of reported sightings in these regions to be a reliable indication that the Cook Inlet Beluga subpopulation is geographically isolated.
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Geographic Range
Beluga whales inhabit the arctic and sub-arctic waters along the coast of Canada, Alaska, Greenland, Norway, and the Soviet Union. About 500 of them inhabit the waters of the St. Lawrence River.
Biogeographic Regions: arctic ocean (Native ); pacific ocean (Native )
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Distribution
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North-West Atlantic Ocean species (NWARMS)
http://www.marinespecies.org/aphia.php?p=sourcedetails&id=2901
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Distribution
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UNESCO-IOC Register of Marine Organisms
http://www.marinespecies.org/aphia.php?p=sourcedetails&id=1318
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Distribution
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UNESCO-IOC Register of Marine Organisms
http://www.marinespecies.org/aphia.php?p=sourcedetails&id=1318
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North-West Atlantic Ocean species (NWARMS)
http://www.marinespecies.org/aphia.php?p=sourcedetails&id=2901
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Jan Haelters
http://www.marinespecies.org/aphia.php?p=sourcedetails&id=141792
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van der Land, J. (2001). Tetrapoda, in: Costello, M.J. et al. (Ed.) (2001). European register of marine species: a check-list of the marine species in Europe and a bibliography of guides to their identification. Collection Patrimoines Naturels, 50: pp. 375-376
http://www.marinespecies.org/aphia.php?p=sourcedetails&id=1406
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MEDIN (2011). UK checklist of marine species derived from the applications Marine Recorder and UNICORN, version 1.0.
http://www.marinespecies.org/asteroidea/aphia.php?p=sourcedetails&id=149081
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Kedra, M. (2010). A Checklist of marine species occurring in Polish marine waters, compiled in the framework of the PESI EU FP7 project.
http://www.marinespecies.org/aphia.php?p=sourcedetails&id=149084
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Lesage, Veronique, Jean-Francois Gosselin, Mike Hammill, Michael C.S. Kingsley, Jack Lawson (2007). Ecologically and Biologically Significant Areas (EBSAs) in the Estuary and Gulf of St. Lawrence - A marine mammal perspective. DFO Can. Sci. Advis. Sec. Res. Doc. 2007/046: 1-96.
http://www.marinespecies.org/cetacea/aphia.php?p=sourcedetails&id=151497
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National Distribution
Canada
Origin: Native
Regularity: Regularly occurring
Currently: Present
Confidence: Confident
Type of Residency: Year-round
United States
Origin: Native
Regularity: Regularly occurring
Currently: Present
Confidence: Confident
Type of Residency: Year-round
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Global Range: Arctic and sub-Arctic waters of North America and Eurasia. Southernmost regular range in the Western Hemisphere: St. Lawrence River estuary (isolated resident population), Gulf of Alaska, James Bay (Stewart and Stewart 1989). See Reeves and Mitchell (1989) for information on status in Ungava Bay and eastern Hudson Bay. See Richard (1993) for information on status in western and southern Hudson Bay. See Doidge and Finley (1993) for information on status of the Baffin Bay population. See also IUCN (1991) for further details regarding distribution.
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Range
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Physical Description
Morphology
Physical Description
The beluga is also known as the white whale for its milky white skin. It is the only species of whale that is entirely white, although it is born gray and fades gradually with age. These whales lack a dorsal fin, but have a shallow ridge along their back. Their appendages are narrower and pointier than that of the narwhal. Belugas also have a melon-shaped head, which is the center for echolocation. They are 3 to 5 meters and length and weigh an average of 1.6 tons (3500lbs). Fifty percent of their weight is fat, a marked increase relative to other non-arctic whales, whose body is only twenty percent fat. The blubber is 10cm thick in belugas. Belugas are sexually dimorphic, with the males being slightly larger than the females. Females average 1,350 kg and males 1,500 kg in weight.
Average mass: "1,350-1,500" kg.
Range length: 300 to 460 cm.
Average length: 400 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
Average mass: 1.43e+06 g.
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Size
Size in North America
Length:
Range: 3.4-4.9 m males; 3.3-4 m females
Weight:
Range: 800-1,500 kg males; 540-790 kg females
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Diagnostic Description
Morphology
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North-West Atlantic Ocean species (NWARMS)
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Ecology
Habitat
Habitat and Ecology
Belugas occur seasonally (mainly in summer) in coastal waters as shallow as 1-3 m deep but also in deep offshore waters (>800 m). They typically enter estuaries and sometimes move upstream into rivers; there are records of individuals or small groups ranging hundreds of kilometers from the sea. They occupy estuaries, continental shelf and slope waters, and deep ocean basins in conditions of open water, loose ice, and heavy pack ice. Belugas generally prefer to overwinter in shallow or coastal areas, usually with light or highly moveable ice cover (Barber et al., 2001; Richard et al. 2001; Suydam et al. 2001; Heide-Jørgensen et al. 2003a) and may occur as fully Arctic populations (Richard et al. 1998b; Richard et al. 2001; Suydam et al. 2001) or sub-Arctic populations (Hobbs et al. 2005).
Some belugas undertake large-scale annual migrations between summering and wintering sites, while others remain in the same area year-round, shifting offshore only when excluded from coastal habitat by fast-ice formation (Hobbs et al. 2005). Large numbers of migratory belugas occur along the northwestern and northern Alaskan coast, in the Canadian high Arctic, and in western Hudson Bay. At certain times of the year, those whales migrate thousands of kilometers, in some cases as far as 80oN into dense pack ice (Suydam et al. 2001) or thousands of kilometers into the North Water polynya or to the pack ice off West Greenland (Richard et al. 1998a,b; Richard et al. 2001; Heide-Jørgensen et al. 2003a). Non-migratory belugas that generally make seasonal shifts in distribution of less than a few hundred kilometers are found in Cook Inlet, Cumberland Sound, Svalbard, and the Gulf of St. Lawrence (Lydersen et al. 2001; Kingsley 2002; Hobbs et al. 2005).
While the general features of beluga whale habitat can be described for the relatively well-studied populations, the importance of those features is not well understood (Laidre et al. in press). For example, the summer occupation of nearshore/estuarine waters has been ascribed alternatively to feeding (Seaman et al. 1982), to warm water providing a thermal advantage to neonates (Sergeant and Brodie 1969), and to the presence of fresh water and coarse substrates facilitating skin shedding during molt (St. Aubin et al. 1990; Frost et al. 1993). The relative importance of each of those factors likely varies based on the environmental conditions (e.g., water temperatures and prey availability) specific to each of the summering areas (Frost and Lowry 1990a). Similarly, it is unclear why belugas sometimes move into deep, ice-covered waters. One potential reason would be to avoid killer whale (Orcinus orca) predation (Frost et al. 1992). However, the movements into the ice appear excessive for what would be needed to avoid killer whales (Suydam et al. 2001) and actually could expose belugas to predation by polar bears (Ursus maritimus) (Lowry et al. 1987a) as well as increase the risk of entrapment in the ice. It is possible belugas move into ice-covered offshore regions for feeding, primarily on Arctic cod (Boreogadus saida), but few data are available to test this hypothesis. Similarly, the associations of belugas with features such as the continental shelf break (Moore 2000) may be related to oceanographic processes that produce good feeding conditions (Laidre et al. in Press).
Dives may last up to 25 min. and can reach depths of > 800 m. The beluga has a diverse diet, which varies greatly from area to area. Although various species of fish are considered to be the primary prey items (including salmon, herring, and Arctic cod), belugas also feed on a wide variety of mollusks (such as squid and octopus) and benthic crustaceans (shrimps and crabs). Polar bears and killer whales are known predators of belugas throughout their Arctic range (Frost et al. 1992).
Systems
- Marine
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Habitat and Ecology
Systems
- Marine
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Habitat
The habitat of beluga whales includes inlets, fjords, channels, bays, and the shallow waters of the artic seas that are warmed by continuous sunlight. They are also found at the mouths of river during summertime, where they feed, socialize, and deliver their offspring. These waters are usually 8 to 10 degrees celsius.
Range depth: 0 to 350 m.
Habitat Regions: saltwater or marine
Terrestrial Biomes: icecap
Aquatic Biomes: pelagic ; benthic ; coastal ; brackish water
Other Habitat Features: estuarine
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Habitat
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UNESCO-IOC Register of Marine Organisms
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Habitat
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North-West Atlantic Ocean species (NWARMS)
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Water temperature and chemistry ranges based on 3 samples.
Environmental ranges
Depth range (m): 0 - 0
Temperature range (°C): 7.367 - 14.365
Nitrate (umol/L): 1.715 - 3.963
Salinity (PPS): 31.835 - 33.295
Oxygen (ml/l): 6.009 - 7.040
Phosphate (umol/l): 0.419 - 0.635
Silicate (umol/l): 2.009 - 3.312
Graphical representation
Temperature range (°C): 7.367 - 14.365
Nitrate (umol/L): 1.715 - 3.963
Salinity (PPS): 31.835 - 33.295
Oxygen (ml/l): 6.009 - 7.040
Phosphate (umol/l): 0.419 - 0.635
Silicate (umol/l): 2.009 - 3.312
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.
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Habitat Type: Marine
Comments: Inhabits the open ocean as well as shallow coastal waters, rivers, estuaries; shallow waters such as estuaries of large rivers are used in summer.
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Habitat
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Migration
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Population that summers around Somerset Island in eastern Canadian high arctic migrates through Lancaster Sound and winters mainly in Baffin Bay and Davis Strait (Droidge and Finley 1992, 1993). heavy pack ice and landfast ice; in spring may follow ice edges closely, penetrate areas with ice cracks (Stewart and Stewart 1989).
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Trophic Strategy
Food Habits
Belugas feast on a variety of prey including smelt, flatfish, flounder, sculpins, salmon, and cod. They also feed on invertebrates such as crab, shrimp, clams, worms, octopus, squid, and other bottom dwelling creatures. Since they don’t have many big, sharp teeth to grab their prey, they use suction to trap it into their mouths. Consequently, everything must be eaten whole. Prey cannot be too large, therefore, or the beluga will choke on it.
Animal Foods: fish; mollusks; aquatic or marine worms; aquatic crustaceans
Primary Diet: carnivore (Piscivore , Eats non-insect arthropods, Molluscivore )
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Comments: Eats various benthic and pelagic prey in shallow and coastal waters; most important prey varies, includes capelin, various cods, sand lance, char, herring, cisco, whitefish, smelt, burbot, salmon, sculpin, decapods, squid, octopus.
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Associations
Ecosystem Roles
Belugas consume many fish, especially since they travel in herds of between one hundred and a thousand. This undoubtedly causes some regulation of fish populations. Belugas also seem to have a parasite called Pharurus pallasii, thought to infect the hearing organs. However, it is not known if this parasite is harmful to the beluga.
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Predation
The known predators of belugas are killer whales and polar bears. Polar bears will attack belugas in the same way they would attack a seal, which entails lying in wait at breathing holes. Killer whales come around August. Belugas can usually hear killer whales, so this makes it difficult for killer whales to attack them. Also, the conspicuous fin makes it almost impossible for a killer whale to maneuver in ice. Humans used to hunt belugas for their skin and oil, but that is not so common anymore.
Known Predators:
- killer whales (Orcinus orca)
- polar bears (Ursus maritimus)
- humans (Homo sapiens)
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Known predators
Orcinus
Homo sapiens
Ursus maritimus
This list may not be complete but is based on published studies.
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Known prey organisms
benthonic invertebrates
Vertebrata
non-insect arthropods
Actinopterygii
aquatic or marine worms
Mollusca
Crustacea
Based on studies in:
Arctic (Marine)
This list may not be complete but is based on published studies.
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General Ecology
Travels in small groups of 2-10, also forms summer congregations of hundreds or thousands. Mature males tend to travel together, as do females, calves, and immatures (Stewart and Stewart 1989).
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Life History and Behavior
Behavior
Communication and Perception
Communication is achieved by using the melon for echolocation. Belugas have a high frequency level of communication. Their voices are so loud that they sound like birds, which is why they were once nicknamed “sea canaries”. They are considered to be among the most vocal species of cetaceans. They use their vocalizations for echolocation, mating, and communication. Their voices sound like chirps, whistles, and squawks. Belugas also use body language such as grinding their teeth or splashing around. Some communication undoubtedly occurs when babies are in contact with their mothers.
Communication Channels: tactile ; acoustic
Perception Channels: visual ; acoustic ; echolocation ; vibrations
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Cyclicity
Life Cycle
Development
There is either thought to be spontaneous ovulation with an extremely long gestation period or delayed implantation with a shorter gestation period, but it is unknown. Their development is similar to that of most other mammals. (Lentifer 1988)
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Life Expectancy
Lifespan/Longevity
The life span for females is thought to be about 32 years and that for males about 40 years. Predation and ice entrapment are common causes of premature death.
Range lifespan
Status: wild: 32 to 40 years.
Typical lifespan
Status: wild: 25 to 30 years.
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Lifespan, longevity, and ageing
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Reproduction
Reproduction
The mating system of these whales has not been described.
Belugas tend to mate from late February to early April. The males chase down the females, making all sorts of noises. The male throws down his tail and bends violently, then he throws his head up and down as his melon vibrates to ward off any other males who might attempt to mate with this female.
The male and female swim in harmony and caress each other, until she swims underneath his belly. She puts her belly up against his and they continue to swim in harmony with each other. They mate only with absolute consent. (Paine, 1995)
Gestation lasts about fourteen months. However, it is a possibility that these creatures have delayed implantation. A calf is born during the summer months of May through July. The calf is very well developed and has a grayish coloration. The nursery pod stays around during the delivery and then all of them take off except a young teenage nursemaid. This usually happens near rivers because the water is ten degrees warmer there. This is important for the calf, which does not have as much blubber as a full grown adult. The baby stays in-between the two females as they swim pulling him with the current. The calf is totally dependent on the mother’s milk for a year, but lactation lasts 1.5 to 2 years.
It takes 4 to 7 years for females to sexually mature, and it takes 7 to 9 years for males. (Bonner, 1989)
Females reproduce every 2 to 3 years. Females stop reproducing in their early twenties. (Lentifer, 1989)
Breeding interval: Female belugas generally reproduce once every two to three years.
Breeding season: Breeding occurs from late February through early April.
Range number of offspring: 1 to 1.
Average gestation period: 14 months.
Range weaning age: 12 to 24 months.
Range time to independence: 12 to 24 months.
Range age at sexual or reproductive maturity (female): 4 to 7 years.
Range age at sexual or reproductive maturity (male): 7 to 9 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization ; viviparous ; delayed implantation
Average birth mass: 66000 g.
Average gestation period: 416 days.
Average number of offspring: 1.
Offspring are precocious, and able to swim along side their mothers from birth. The mother provides protection and guidance for the offspring, as well as milk. A female beluga can lactate for up to two years.
Parental Investment: precocial ; pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)
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Mates generally in spring. Gestation lasts 14-15 months. Single young (rarely 2); births peak in late March in western Greenland, late June in western Hudson Bay and Bering Sea, July in the Gulf of St. Lawrence. Lactation lasts 20-24 months. Age of first pregnancy: 4-7 years (Stewart and Stewart 1989). Calving interval probably is 3 years for most adult females. Females live up to about 20 years, males to about 30 years.
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Molecular Biology and Genetics
Molecular Biology
Barcode data: Delphinapterus leucas
There are 2 barcode sequences available from BOLD and GenBank. Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species. See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
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Statistics of barcoding coverage: Delphinapterus leucas
Public Records: 2
Species: 7
Species With Barcodes: 1
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Conservation
Conservation Status
IUCN Red List Assessment
Red List Category
Red List Criteria
Version
Year Assessed
Assessor/s
Reviewer/s
Justification
The species was assessed previously (1996) as Vulnerable (VU A1abd). The main reason for the change to Near Threatened is that the decline criterion for Vulnerable is not met for some of the largest subpopulations, and they have a disproportionate effect on the assessment of the species as a whole. Also, estimates of current population size for several of the larger stocks are substantially higher than previous estimates (due to better survey methods and not necessarily because of increases in numbers).
Across the global range of belugas, subpopulations are subject to differing levels of threat and warrant individual assessment. Some subpopulations clearly qualify for threatened status and only one of these – the Cook Inlet subpopulation – has been assessed thus far (as CR) (Lowry et al. 2006). Those other potentially threatened subpopulations (e.g. West Greenland, eastern Hudson Bay, St. Lawrence River, Ungava Bay) that are well-defined and well-studied should be assessed separately as soon as feasible.
History
- 1996Vulnerable(Baillie and Groombridge 1996)
- 1994Insufficiently Known(Groombridge 1994)
- 1990Insufficiently Known(IUCN 1990)
- 1988Insufficiently Known(IUCN Conservation Monitoring Centre 1988)
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IUCN Red List Assessment
Red List Category
Red List Criteria
Version
Year Assessed
Assessor/s
Reviewer/s
Contributor/s
Justification
Evaluation for Listing as Endangered:
The Cook Inlet Beluga subpopulation qualifies for listing as Endangered under the following IUCN criteria:
Criterion A2b. Based on an index of abundance showing that the population has likely declined by 75% in the last 26 years (approximately 1.5 generations).
Criterion D. The population is estimated to number 207 mature individuals, well below the 250 threshold.
Evaluation for Listing as Critically Endangered:
The Cook Inlet Beluga subpopulation qualifies for listing as Critically Endangered under the following IUCN criterion:
Criterion C2a(ii). The population is estimated to number 207 mature individuals. There is a 71% probability that the growth rate of the population is negative, with the best estimate indicating that the population is declining by 1.2% per year. All of the mature individuals are in one subpopulation.
Based on the information above, the proposed listing is Critically Endangered: C2a(ii). Key to this decision ? i.e., to list as Critically Endangered rather than Endangered ? is the fact that the population is continuing to decline even after the only identified cause of the decline (excessive hunting) has been controlled. Other factors must be affecting the dynamics of this population, and those factors have not yet been identified.
In making this assessment the members of the IUCN SSC Cetacean Specialist Group were consulted.
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Conservation Status
Currently, beluga populations have been estimated at 60,000 to a 100,000 so there is no need for conservation efforts, although it couldn’t hurt.
US Federal List: no special status
IUCN Red List of Threatened Species: critically endangered
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National NatureServe Conservation Status
Canada
Rounded National Status Rank: N3 - Vulnerable
United States
Rounded National Status Rank: N3 - Vulnerable
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NatureServe Conservation Status
Rounded Global Status Rank: G4 - Apparently Secure
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Status
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Status
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Trends
Population
Alaska
Cook Inlet: The number of beluga whales in Cook Inlet is estimated from counts by aerial observers and aerial video group counts (Hobbs et al. 2000b; Lowry et al. 2006). 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.
Bristol Bay: Most recently (1994), the number of beluga whales in Bristol Bay was estimated at 1,555 (Lowry and Frost 1999). This estimate was based on a maximum count of 503 animals, which was corrected using radio-telemetry data for the proportion of animals that were diving (Lowry and Frost 1999) and for the proportion of newborns and yearlings not observed due to their small size and coloration. Surveys in 1999 and 2000 resulted in maximum counts of 690 and 531, which can be extrapolated to population estimates of 2,133 and 1,642, respectively (L. Lowry, University of Alaska Fairbanks pers. comm. to K. Laidre, 1/07).
Eastern Bering Sea: Aerial surveys of Norton Sound, the summering site for the eastern Bering Sea stock, were conducted in 2000. Preliminary analyses produced an uncorrected estimate of 5,868 animals; when corrected for animals not visible at the surface and for newborn and yearling animals not observed due to their small size and dark coloration, the estimated population size for Norton Sound is 18,142 (CV=0.24) (R. Hobbs, AFSC-NMML pers. comm. 01/07; Angliss and Outlaw 2005).
Eastern Chukchi Sea: Frost et al. (1993) estimated the minimum size of the eastern Chukchi stock of belugas at 1,200, based on counts of animals from aerial surveys conducted during 1989-91. The total corrected abundance estimate for the eastern Chukchi stock is 3,710.
Shared Alaska/Canada
Eastern Beaufort Sea/Beaufort Sea: The most recent aerial survey, conducted in July 1992, resulted in an uncorrected estimate of 19,629 (CV=0.229) (Harwood et al. 1996). The corrected population estimate was 39,258 animals (Angliss and Outlaw 2005).
Canada
Cumberland Sound: This stock numbers about 1,500 animals and is thought to have increased since the 1980s (COSEWIC 2004)
Ungava Bay: The Ungava Bay stock is too small to estimate. Hammill et al. (2004) recently estimated it at <50 animals; none were seen on a survey conducted in 2001.
West Hudson Bay: There are estimated to be more than 23,000 belugas in western Hudson Bay and more than 1,300 along the southern Hudson Bay coast (Richard 1991).
East Hudson Bay: Belugas in Eastern Hudson Bay have declined from 4,200 (SE 300) in 1985 to 3,100 (SE 800) in 2004 (corrected estimates) (Hammill et al. 2005).
St Lawrence River: The St. Lawrence subpopulation is estimated to be in the order of 900-1,000 individuals. There is no evidence of a significant trend in abundance since 1988 (COSEWIC 2004).
Eastern High Arctic/Baffin Bay: A survey in 1996 estimated 21,213 belugas (95% CI 10,985 to 32,619) in the waters surrounding Somerset Island: Barrow Strait, Peel Sound and Prince Regent Inlet (Innes et al. 2002). This estimate takes into account both whales missed by observers and those that might have been unavailable for detection due to diving behavior. It includes whales that move to West Greenland during the winter.
Shared Canada/Greenland
West Greenland: Aerial surveys flown in late winter in West Greenland between 1981 and 1994 found that beluga numbers had decreased by 62% during that period, probably because of overharvesting (Heide-Jørgensen and Reeves 1996). Further surveys in 1998 and 1999 confirmed the decline and found 7,941 (95% CI: 3650-17278) belugas in West Greenland, including whales missed by the observers and whales that were submerged during the survey (Heide-Jørgensen and Acquarone 2002). Heide-Jørgensen et al. (2003) estimate that approximately 30% of the Eastern Canadian high Arctic/Baffin Bay beluga stock migrates to West Greenland for overwintering.
Svalbard
Belugas have never been surveyed around Svalbard. Pods numbering into the thousands are sighted irregularly around the archipelago, and pods ranging from a few to a few hundred individuals are seen regularly (Gjertz and Wiig 1994; Kovacs and Lydersen 2006).
Russia
Eastern and Central Russian Arctic: There are no rigorous abundance estimates for the Eastern and Central Russian Arctic (Boltunov and Belikov 2002). Rough estimates of a few thousand in Anadyr Gulf and a few thousand in the western Chukchi and eastern East Siberian Seas were summarized in a table compiled by the IWC Scientific Committee (IWC 2000). In addition to those animals, belugas from Alaskan stocks (e.g. eastern Bering Sea, eastern Chukchi Sea, and Beaufort Sea stocks) move into eastern Russian waters during the winter. The IWC table mentioned above (IWC, 2000) indicates a rough estimate of 18,000-20,000 in the Okhotsk Sea.
Western Russian Arctic: Belugas in the Western Russian Arctic occupy four major areas: (1) southern Barents and White seas, (2) southern Barents and Kara seas, (3) coastal waters of the Kara Sea, and (4) western portion of the Laptev Sea. They may share wintering grounds to some extent. Surveys have not yet been conducted in the Barents and Kara seas and the number of belugas inhabiting these regions is unknown. The White Sea hosts a resident population of belugas numbering about 1,000 over-wintering individuals. In summer, this number is augmented by animals from the Barents Sea.
Population Trend
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Population
Differences in survey design and analytical techniques prior to 1994 rule out a precise statistical assessment of trends using the first available population estimate. Simply comparing the estimate of 1,293 in 1979 to 278 in 2005 indicates a 78% decline in 26 years, but with unspecified confidence.
The 1994-2005 surveys were statistically defined, and allow rigorous evaluation of the decline and the underlying population dynamics during the more recent period. A Bayesian inference was conducted on the underlying rate of increase, Rmax, and the true 1994 population size, using the Taylor and DeMaster (1993) model for density dependent population growth with the conventional shape parameter value z=2.3898, an assumed value of K=1,300 (based roughly on the earliest survey estimate), fitting to the 1994 through 2005 time series of population estimates, reported coefficients of variation of the respective estimates, and the harvest estimates (D. Goodman unpublished). The results of annual estimates of population size from the model are shown in Figure 3 (see the attached PDF). Comparing the mode of the Bayesian distribution for the 2005 population size (329) to the 1979 estimate indicates a decline of 75% over the 26-year period.
In the present model, Rmax represents the growth rate that the population would exhibit in the absence of crowding and the absence of harvest, all other things (including favorability of the environmental state) being equal, as revealed from observed growth in the given data set. Thus, Rmax does not necessarily indicate the potential growth rate under optimal conditions. The Bayesian analysis used broad independent uniform priors for the two unknown parameters, and a normal likelihood for the observation error in the census. The Bayesian analysis yielded a posterior distribution for Rmax that is abnormally low (see Figure 4 in attached PDF) compared to the expectation that a small cetacean population should have a value of Rmax in the range from 2% to 6%, with the average expected to be around 4% (Wade 1999). Based on this analysis the probability is 99% that Rmax for the Cook Inlet Beluga subpopulation is less than the expected average normal value, and the probability is 93% that Rmax is lower than the expected normal range. The probability is 71% that Rmax is actually negative for this population over the period covered by the data (1994?2005). The modal estimate of Rmax from the Bayesian inference is -1.2, indicating a population that is declining by about 1% per year. If these underlying dynamics continue, and the future harvest is zero, there is a 22% probability that the population will be further halved from its 2005 abundance within 30 years.
To evaluate taxa based on Red List Criteria, IUCN defines population size as the number of mature individuals. There are no data available on the sex and age composition of the Cook Inlet Beluga subpopulation or on the age at which animals attain sexual maturity. Such information is available from other harvested Beluga subpopulations, and although the data may be subject to biases from non-random distribution of sex/age classes and harvest selectivity it can be used to estimate the number of animals that are mature. Critical to this determination is the ability to accurately determine the age of individuals, which for Beluga whales and other toothed cetaceans is typically done by counting growth layer groups (GLGs) in their teeth. For Beluga whales it has generally been assumed that two GLGs are deposited each year (Burns and Seaman 1986, Heide-Jørgensen et al. 1994, Suydam 1999). Hohn and Lockyer (1999) questioned that assumption, citing what they regarded as convincing evidence of a one GLG/yr deposition rate. However, examination of teeth from two known age captive animals has confirmed the two GLG/yr assumption (Goren et al. 1987, Heide-Jørgensen et al. 1994) and we will assume that is the true situation. For the eastern Bering and eastern Chukchi seas, Burns and Seaman (1986) estimated the first age of sexual maturity to be 4?7 years old for females. Heide-Jørgensen and Teilmann (1994) produced estimates of 4?7 years old for first age of maturity for females and 6?7 years old for males for West Greenland belugas. Based on the life table in Burns and Seaman (1986), 63% of belugas in western Alaska would be 6 years old and older. However, the proportion capable of reproduction may be somewhat less if reproductive senescence occurs in older females (Burns and Seaman 1986, Suydam 1999). The Bayesian inference procedure described above delivered a posterior distribution for the 2005 population size (see Figure 5 in the attached PDF). This shows a 95% probability that the population is in the interval 278?388. Using the mode of the Bayesian distribution of population sizes (329) and the estimate of 63% mature gives an estimate of 207 mature individuals in the population.
Generation Time:
Generation time, estimated as the average age of parents of the current cohort, cannot be calculated directly for Cook Inlet belugas because data on reproductive characteristics and age distribution are lacking for that population. Elsewhere in Alaska, the age of first parenthood for female belugas is 5-8 years (Burns and Seaman 1986). Males probably are physiologically capable of breeding at about the same age (Heide-Jørgensen and Teilmann 1994). Maximum ages recorded by Burns and Seaman (1986) were 35 years for females and 38 years for males. These estimates may be biased low due to tooth wear (Heide-Jørgensen et al. 1994). Based on the life table in Burns and Seaman (1986), the average age of belugas 6 years and older was 16.1 years. We have no way to determine if these vital parameters are similar for Cook Inlet belugas. Nonetheless, we consider 16 years to be the best available estimate of the average age of parents in the Cook Inlet subpopulation, and the generation time.
Population Trend
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Threats
Known or potential threats include a variety of human activities in addition to hunting: oil and gas development, expansion of fisheries (with possible implications for bycatch and resource depletion), hydroelectric development (in Hudson Bay), and industrial and urban pollution. Climate change will likely increase the scale and distribution of these activities. Hydroelectric development may affect belugas because of their dependence on estuarine conditions. Areas such as the McKenzie Delta and West Greenland are subject to oil exploration, which often includes seismic surveys, offshore drilling, and artificial island construction. These activities are undertaken in the summer months in the same areas occupied by belugas at this time of year. In a study of responses of belugas to ice-breaking ships, the belugas typically moved rapidly along ice edges away from approaching ships and showed strong avoidance reactions to approaching ships at distances of 35-50 km (Finley et al. 1990).
Climate change is another potential threat. Belugas may experience climate-induced geographic shifts or altered reproductive success due to persistent changes in extent of sea ice (Tynan and DeMaster, 1997, Laidre et al In Press). Belugas are also susceptible to savssats or ice entrapments when sea ice conditions change rapidly.
Threats from contaminants are of concern in some areas. Studies of the small, geographically isolated subpopulation in the St. Lawrence River have found that concentrations of both total PCBs and chlorinated PCB congeners are much higher in these belugas than in Arctic belugas. Some scientists believe that the increased occurrence of opportunistic bacterial infections, parasitic infestation, gastric ulcers and other disorders in St. Lawrence belugas is evidence of a link between immune system dysfunction and PCB exposure (Martineau et al., 1994).
To summarize, in some parts of the species’ range, particularly in Canada and Greenland, intensive hunting represents an ongoing major threat, and in a few instances this is compounded by the less direct and less easily quantified threats (realized and potential) of disturbance by vessel traffic (e.g. St. Lawrence estuary, river mouths in eastern Hudson Bay), habitat modification (e.g. large hydroelectric dams in rivers flowing into Hudson Bay and James Bay), contaminants (e.g. St. Lawrence estuary), climate change (including secondary effects from opening of Arctic and sub-Arctic waters to year-round ship traffic, oil an gas development, commercial fishing), and possibly incidental catch in fisheries (e.g. St. Lawrence estuary).
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Shelden et al. (2003) reviewed data on Killer Whale predation in Cook Inlet, and although they accounted for 21 belugas killed by killer whales between 1985 and 2002 they concluded that predation was a small contribution to overall mortality. However, because this population is currently at a very low size, normal fluctuations in prey availability and predation may affect its ability to recover.
Prior to 1972 there were periodic commercial and sport hunts for Beluga in Cook Inlet (Mahoney and Shelden 2000, NMFS 2003), but those activities ceased with passage of the Marine Mammal Protection Act (MMPA). Native Alaskans have hunted belugas in Cook Inlet from earliest times (Huntington 2000, Mahoney and Shelden 2000). During much of the last century, subsistence removals appear to have been modest. A number of factors, including rapid human population growth and improvements in equipment, resulted in an increase in subsistence hunting in Cook Inlet during the 1980s. By the mid to late 1990s, the harvest was unsustainable. It has been estimated that an average of 67 whales were removed each year from 1994-1998, and that level was considered sufficiently high to account for most of the decline in abundance observed during that period (NMFS 2003). There was no legal harvest allowed in 1999. Since 2000, NMFS has entered into annual co-management agreements with Alaska Native organizations to allow a limited hunt, and five whales total were harvested during 2000-2005 (Angliss and Lodge 2004, B. Mahoney pers. comm.). Other factors must be invoked to account for the abnormally low underlying growth rate (Rmax) exhibited by the population, or to account for the failure to show signs of recovery since the reduction of the harvest to very low levels.
Other factors that could have an adverse effect on Cook Inlet belugas include fishery interactions, contaminants and noise associated with oil and gas exploration and production, vessel traffic, and municipal activities such as waste management and urban runoff (Moore et al. 2000, NMFS 2003). In the course of a review of subsistence harvest management, NMFS concluded that the available evidence could not persuasively attribute much past influence to these non-harvest factors and further asserted that they were unlikely to affect the Cook Inlet Beluga subpopulation in the foreseeable future (NMFS 2003). The NMFS analysis did not recognize that the subpopulation was failing to recover as expected or that the evident Rmax was abnormally low. The quality and quantity of data for describing impacts or predicting effects of such factors on belugas vary greatly. Levels of heavy metals, PCBs, and chlorinated pesticides are much lower in Cook Inlet belugas than in other Beluga stocks in Alaska (Becker et al. 2000). Observer programs and other reports indicate that current incidental take in commercial fisheries is very low (Moore et al. 2000, Angliss and Lodge 2004). However, evaluating the effects of noise is complicated, determining the impact of municipal discharges may not be possible, and no data are available to describe or predict the effects of an oil spill on belugas. Nonetheless, the fact remains that Cook Inlet is no longer a remote, pristine area. Over 350,000 people live in the municipality of Anchorage and the two adjacent boroughs, and there are two large military bases in the area (NMFS 2003). The analysis by NMFS concluded that: "A significant part of the habitat for this species has been modified by municipal, industrial, and recreational activities in Upper Cook Inlet" (NMFS 2003, p. 88). A number of other significant habitat modifications are likely to occur in the near future.
Random demographic, environmental, and genetic factors can accelerate or even cause the extinction of small populations. Catastrophic events such as mass die-offs due to stranding, disease, or acute exposure to toxic substances (e.g., oil spills) could push depleted populations of belugas to extinction (O?Corry-Crowe and Lowry 1997). Mass strandings of belugas are relatively common in the shallow tidal areas of upper Cook Inlet. Although most stranded individuals manage to swim away on the rising tide, some are known to die (Moore et al. 2000). The viability of small populations is further compromised by the increased risk of inbreeding and the loss of genetic variability through drift, which reduces their ability to cope with disease and environmental change (Lacy 1997, O?Corry-Crowe and Lowry 1997). Estimates of genetic variation do not, at present, suggest that Cook Inlet belugas are highly inbred or that a critical amount of genetic variation has been lost through drift (O?Corry-Crowe et al. 1997, G. O?Corry-Crowe unpublished data), but this subpopulation is already in a size range where eventual loss of genetic variability is expected.
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Comments: Population decline in Gulf of St. Lawrence (from 5000 to 500) and elsewhere is attributed to loss of suitable habitat, pollution, and especially historic over-exploitation (Stewart and Stewart 1989, IUCN 1991, Dold 1993). This population shows a high rate of intestinal cancer, possibly related to water pollution (Farnsworth, NY Times, 22 August 1995). Lungworms may be an important cause of morbidity and mortality of young in the St. Lawrence estuary (Measures et al. 1995). The Southeast Baffin Island population is thought to be declining as a result of excessive harvest (Richard 1991). There is also concern that excessive harvest, especially in western Greenland, may be threatening the Baffin Bay population that summers around Somerset Island (Droidge and Finley 1992, 1993). Potentially threatened also by development of hydrocarbon resources and increased disturbance from ship traffic.
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Threats
In some parts of the Beluga Whale’s range, particularly in Canada and Greenland, intensive hunting represents an ongoing threat to Belugas. In a few instances this is compounded by the less direct and less easily quantified threats of disturbance by vessel traffic (e.g., St. Lawrence estuary, river mouths in eastern Hudson Bay), habitat modification (e.g., large hydroelectric dams in rivers flowing into Hudson Bay and James Bay), contaminants (e.g., St. Lawrence estuary), and possibly incidental catch in fisheries (wherever entangling gear overlaps the animals’ range) (IUCN 2009).
Global climate change may also have serious negative impacts on Beluga Whales. The most serious impacts of climate change on Belugas may not come directly from the effects of weather conditions, but rather indirectly from the role that regional warming and reduced sea ice play in changing human activities. Extensive ice cover and extreme winter conditions (including both darkness and cold) have always limited human activities in the Arctic, and many regions have remained inaccessible to ships and other vessels. As Arctic ice cover declines and the passages between northern landmasses become more navigable, humans will gain easier access to formerly pristine areas that have long served as refuges for Belugas (IUCN 2009).
The number of vessels sailing through the Arctic for gas and oil exploration/extraction, commercial shipping (for both transportation and tourism), and fishing has already increased. Further reductions in sea ice are likely to accelerate this trend in coming decades. With the increase in ship traffic, ship strikes are likely to become an increasingly significant cause of Beluga injury and death. Belugas detect and respond to the presence of icebreaking ships over great distances (up to 50 km). Industrial noise (e.g., from ships, seismic surveys, and offshore drilling), likely disrupts Beluga behaviour and may impair the ability of Belugas to communicate, forage efficiently and generally sense their environment. Noise-producing activities are already ongoing or planned in many areas used by large populations of Belugas, including the Beaufort and Chukchi seas, West Greenland, and Hudson Bay (IUCN 2009).
Pollution may become an increasingly significant problem for Belugas with increasing industrialization and urbanization of the Arctic. Many toxic contaminants become concentrated as they move up the food chain. Because Belugas and other cetaceans are at or near the top of the food chain and have long life spans, they accumulate relatively high concentrations of certain toxins in their blubber and other organs. These may contribute to a range of health problems in the animals themselves and are also of concern to the people who hunt Belugas for food (IUCN 2009).
Loss of sea ice and increased ocean temperatures will affect the distribution, composition, and productivity of prey communities and in turn influence the ability of Belugas to find and catch suitable prey. Given the great uncertainties about how Arctic and sub-Arctic ecosystems function and about how they will be affected by climate change, it is difficult to confidently predict impacts of climate change on Beluga prey populations (IUCN 2009).
As weather patterns become more unpredictable and extreme due to climate change, it is possible that Belugas and other Arctic whales will become more susceptible to ice entrapment. Such events have always occurred and are assumed to contribute to natural mortality in most Beluga populations. However, it is feared that the frequency and scale of the mortality from ice entrapment will increase as the climate changes (IUCN 2009).
As Arctic waters become warmer and patterns of circulation, salinity, and nutrient input change, species that previously were not present in the Arctic will be able to move farther north and remain there for longer. This could have two major types of effects on Belugas. First, species such as Minke and Humpback whales as well as seals and other predators may directly compete with Belugas for food resources. Second, species such as Killer Whales may have more opportunities to prey on Belugas. Both of these factors could negatively affect Beluga populations (IUCN 2009).
One population (or "distinct population segment" in the curious language of the U.S. Endangered Species Act), the Cook Inlet Beluga Whale of Cook Inlet in southeastern Alaska, was listed as endangered by the U.S. National Oceanic and Atmospheric Administration (NOAA) in October of 2008. In December of 2009, NOAA proposed designating more than a third of Cook Inlet as critical habitat for the remaining ~300 Cook Inlet Beluga Whales.
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Management
Conservation Actions
It is listed on CITES Appendix II.
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Conservation Actions
In June 1991, NMFS added the Cook Inlet Beluga subpopulation to the list of taxa considered candidates for listing as threatened or endangered under the U.S. Endangered Species Act (ESA) (U.S. Federal Register 56:26797). An ESA status review was initiated in November 1998 (U.S. Federal Register 63:64228). NMFS received two petitions in March 1999 requesting that Cook Inlet belugas be listed as endangered under the ESA. In June 2000, NMFS published a determination that listing the Cook Inlet subpopulation under the ESA was not warranted because they believed that no factor other than harvest had been identified at that time as having a significant adverse effect on the population (U.S. Federal Register 65:38778), and that harvest had been dealt with through the ongoing regulation of subsistence hunting.
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Relevance to Humans and Ecosystems
Benefits
Economic Importance for Humans: Negative
Belugas hinder fishermen from getting any fish. Much of the hunting of belugas has died down since the seventies.
Negative Impacts: crop pest
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Economic Importance for Humans: Positive
Belugas were once hunted for food and other items such as oil. These provided humans with a profit. Now, because of their large social groupings, they provide ecotourists with entertainment.
Positive Impacts: food ; ecotourism ; research and education; produces fertilizer
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Economic Uses
Comments: Long subjected to subsistence harvest, and formerly to commercial harvest, throughout range (IUCN 1991). Currently harvested by subsistence hunters (e.g., Alaskan natives and Canadian Inuit, and Greenland natives). Displayed in some marine aquaria.
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IUCN Red List Category
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IUCN (2008) Cetacean update of the 2008 IUCN Red List of Threatened Species.
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Wikipedia
Beluga whale
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 meters (16 ft) in length and an unmistakable all-white color with a distinctive protuberance on the head. From a conservation perspective, the beluga is considered "near threatened" by the International Union for Conservation of Nature; however the subpopulation from the Cook Inlet in Alaska is considered critically endangered and is under the protection of the United States' Endangered Species Act.[2][4] Of seven Canadian beluga populations, two are listed as endangered, inhabiting eastern Hudson Bay, and Ungava Bay.
Contents |
Taxonomy
In 1776 Peter Simon Pallas first described the beluga.[1] It is a member of the Monodontidae family, which is in turn part of the toothed whale suborder.[1] The Irrawaddy dolphin was once placed in the same family; however, recent genetic evidence suggests otherwise.[5] The narwhal is the only other species within the Monodontidae family besides the beluga.[6]
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 its high-pitched squeaks, squeals, clucks and whistles. A Japanese researcher says he taught a beluga to "talk" by using these sounds to identify three different objects, offering hope that humans may one day be able to communicate effectively with sea mammals.[7]
Description
Male belugas are larger than females. Males can reach 5.5 metres (18 ft) long, while females grow to 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 most dolphins, but is smaller than most other toothed whales.[citation needed]
The adult beluga is rarely mistaken for another species, because it is completely white or whitish-gray in color. Calves, however, are usually gray.[8] Its head is unlike that of any other cetacean. Like most toothed whales it has a melon—an oily, fatty tissue lump found at the center of the forehead. 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. Unlike many dolphins and whales, the vertebrae in the neck are not fused together, allowing the animal to turn its head laterally. The rostrum has about 8 to 10 teeth on each side of the jaw and a total of 34 to 40 teeth.
Belugas have 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 the Greek word for "wingless." The evolutionary preference for a dorsal ridge rather than a fin is believed 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 (proportionally three times as large as a horse's thyroid) and may help to sustain higher metabolism during the summer estuarine occupations.
Its body is round, particularly when well-fed, and tapers less smoothly to the head than the tail. The sudden tapering to the base of its neck gives it the appearance of shoulders, unique among cetaceans. The tail fin grows and becomes increasingly and ornately curved as the animal ages. The flippers are broad and short—making them almost square-shaped.
Range and habitat
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 their 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 discontinuous. A mother usually returns to the same site year after year. As its summer homes clog with ice during autumn, the beluga moves away for winter. Most travel in the direction of the advancing icepack and stay close its edge for the winter months. Others stay under the icepack—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 air pockets trapped under the ice. The beluga's ability to find the thin slivers of open water within a dense ice pack that may cover more than 96% of the surface mystifies scientists. Its echo-location capabilities are highly adapted to the sub-ice sea's peculiar acoustics and it has been suggested that belugas can sense open water through echo-location.
In 1849, while constructing the first railroad between Rutland and Burlington in Vermont, workers unearthed the bones of a mysterious animal in the town of Charlotte. Buried nearly 10 feet (3.0 m) 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 over 150 miles (241 km) 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 this fossil is now the official Vermont State Fossil (making Vermont the only state whose official fossil is that of a still extant animal).
On June 9, 2006, a young beluga carcass was found in the Tanana River near Fairbanks in central Alaska, nearly 1,700 kilometers (1,056 mi) from the nearest ocean habitat. Belugas sometimes follow migrating fish, leading Alaska state biologist Tom Seaton to speculate that it had followed migrating salmon up the river at some point in the prior fall.
Life history
Belugas are highly sociable. Groups of males may number in the hundreds, while mothers with calves generally mix in slightly smaller groups. When pods aggregate in estuaries, they may number in the thousands. This can represent a significant proportion of the entire population and is when they are most vulnerable to hunting.
Pods tend to be unstable, meaning that they tend to move from pod to pod. 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. Mothers and calves form the beluga's closest social 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 her sometimes even after becoming fully mature.
Belugas can be playful—they may spit at humans or other whales. It is not unusual for an aquarium handler to be drenched by one of his charges. Some researchers believe that spitting originated with blowing sand away from crustaceans at the sea bottom.
Unlike most whales, it is capable of swimming backwards.[12]
Males reach sexual maturity between four and seven years, while females mature at between six and nine years. The beluga can live more than 50 years.[8]
Reproduction
Female belugas typically give birth to one calf every three years.[8] Most mating occurs between February and May, but some mating occurs at other times of year.[6][8] It is questionable whether the beluga has delayed implantation.[6] Gestation last 12 to 14.5 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.[13]
Newborns 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.
Ecology
Feeding
The beluga is a slow swimmer 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 (300 m) but they can dive at least twice this depth. A typical feeding dive lasts 3–5 minutes, but belugas submerge for up to 20 minutes at a time.[14]
Predation
Polar 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 its other significant natural predator.[9]
Relation to humans
Belugas were among the first whale species in 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 apparent expression. Most belugas found in aquariums are caught in the wild, though captive breeding programs enjoy some success.
Both the United States Navy and the Russian Navy have used belugas in anti-mining operations in Arctic waters.[15] In one instance, a captive beluga helped bring a distressed diver who was performing a stunt in his pool up to the surface, possibly saving the diver's life.[16] Another time, a captive beluga brought a cramp-paralized diver from the bottom of the pool up to the surface by holding her foot in its mouth, certainly saving the female diver's life.[17]
Population and threats
The global population of belugas today stands at about 100,000. Although this number is much greater than that of many other cetaceans, it is much smaller than pre-hunting populations. 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.[18] It is considered an excellent sentinel species (indicator of environment health and changes). This is because it is long-lived, on top of the food web, bearing large amounts of fat and blubber, relatively well-studied for a cetacean, and still somewhat common.
Because the beluga congregates in river estuaries, pollution is proving to be a significant health danger. Incidents of cancer have been reported to be rising as a result of St. Lawrence River pollution. Local beluga carcasses contain so many contaminants that they are treated as toxic waste.[citation needed] Reproductive pathology has been discovered here, possibly caused by organochlorines. Levels between 240 ppm and 800 ppm of PCBs have been found, with males typically having higher levels.[19] The long-term effects of this pollution on the affected populations is not known.
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Indirect human disturbance may also be a threat. While some populations tolerate small boats, others actively try to avoid ships. Whale-watching has become a 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, hunting continues, and is believed to be sustainable. However, in other areas, such as the Cook Inlet, Ungava Bay, and off western Greenland, previous commercial operations 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.
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.[20]
Erysipelothrix rhusiopathiae 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.[21]
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 number of belugas over parts of its range (especially the Russian Arctic) and the expectation that if current conservation efforts cease, especially hunting management, the beluga population is likely to qualify for "threatened" status within five years. Prior to 2008, the beluga was listed as "vulnerable", a higher level of concern. IUCN cited the stability of the largest subpopulations and improved census methods that indicate a larger population than previously estimated.[2]
To prevent hunting, belugas are protected under the International Moratorium on Commercial Whaling; however, small amounts of beluga whaling are still allowed. Since it is very difficult to know the exact population of belugas because their habitats include inland waters away from the ocean, it is easy for them to come in contact with oil and gas development centers. To prevent whales from coming in contact with industrial waste, the Alaskan and Canadian governments are relocating sites where whales and waste come in contact.
To prevent captive whales from dying, researchers from the Vancouver Aquarium Marine Science Centre are finding ways to prevent fungi from entering the habitats and to constantly check their health. Healthy captive belugas are important because they are one of the only whales found in many marine aquariums. The high numbers of captives adds to the threat to the beluga population, while their carcasses contribute to scientific research.
Subpopulations are subject to differing levels of threat and warrant individual assessment. The Cook Inlet subpopulation is listed as "Critically Endangered" by the IUCN as of 2006.[22] The Cook Inlet beluga population is listed as Endangered under the Endangered Species Act as of October 2008.[4][23][24] This was due to overharvesting of belugas prior to 1998. The population has failed to recover even though the reported harvest has been small. The most recent published estimate as of May 2008 was 302 (CV=0.16) in 2006.[25] In addition, the National Marine Fisheries Service indicated that the 2007 aerial survey's point estimate was 375.
Evolution
The beluga's earliest known ancestor is the prehistoric Denebola brachycephala from the late Miocene period. A single fossil from the Baja California peninsula, indicates that the family once inhabited warmer waters. The fossil record also indicates that in comparatively recent times the beluga's range varied with that of the polar ice packs—expanding during ice ages and contracting when the ice retreats.
See also
- Pour la suite du monde, a documentary about traditional beluga hunting on the Saint Lawrence River
References
- ^ a b c Mead, James G.; Brownell, Robert L., Jr. (16 November 2005). "Order Cetacea (pp. 723-743)". In Wilson, Don E., and Reeder, DeeAnn M., eds. Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Baltimore: Johns Hopkins University Press, 2 vols. (2142 pp.). ISBN 978-0-8018-8221-0. OCLC 62265494. http://www.bucknell.edu/msw3/browse.asp?id=14300105.
- ^ a b c 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. (2008). Delphinapterus leucas. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 2008-10-07.
- ^ 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. http://www.reuters.com/article/domesticNews/idUSTRE49G6JD20081017. Retrieved 2008-10-17.
- ^ Arnold, P. (2002). "Irrawaddy Dolphin Orcaella brevirostris". In Perrin, W., Würsig B. and Thewissen, J.. Encyclopedia of Marine Mammals. Academic Press. p. 652. ISBN 0-12-551340-2.
- ^ a b c d e O'Corry-Crowe, G. (2002). "Beluga Whale Delphinapterus leucas". In Perrin, W., Würsig B. and Thewissen, J.. Encyclopedia of Marine Mammals. Academic Press. p. 94–99. ISBN 0-12-551340-2.
- ^ "Japanese whale whisperer teaches beluga to talk". www.meeja.com.au. 2008-09-16. http://www.meeja.com.au/index.php?display_article_id=221. 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.
- ^ 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.
- ^ 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. (Russian)
- ^ http://www.uvm.edu/whale/
- ^ "Georgia Aquarium – Beluga Whale". http://www.georgiaaquarium.org/exploreTheAquarium/webcam-beluga.aspx. Retrieved 2008-10-12.
- ^ Cosens, S. & Dueck, L. (June 1990). "Spring Sightings of Narwhal and Beluga Calves in Lancaster Sound, N.W.T". Arctic 31 (2): 1–2. http://pubs.aina.ucalgary.ca/arctic/Arctic43-2-127.pdf.
- ^ "Delphinapterus leucas: Beluga Whale". Marine Bio. http://www.marinebio.org/species.asp?id=159. Retrieved 2008-08-26.
- ^ "The Story of Navy Dolphins". PBS. http://www.pbs.org/wgbh/pages/frontline/shows/whales/etc/navycron.html. Retrieved 2008-10-12.
- ^ "Wal Rettet Ertrinkende Taucherin!". http://www.blick.ch/news/ausland/wal-rettet-ertrinkende-taucherin-124805. Retrieved 2009-09-27.
- ^ Christine Lepisto (02 August 2009). "Beluga Whale Saves Diver". http://www.treehugger.com/files/2009/08/amazing-beluga-whale-rescues-diver.php. Retrieved 2010-08-31.
- ^ Portrait of endangered beluga whales in Quebec
- ^ J Great Lakes Res.,19 & Arch. Environ. Contam. Toxicol.,16 & Sci. Total Environ.,154
- ^ Dierauf, L. & Gulland, F. (2001). CRC Handbook of Marine Mammal Medicine. CRC Press. p. 26, 303, 359. ISBN 0849308399.
- ^ Dierauf, L. & Gulland, F. (2001). CRC Handbook of Marine Mammal Medicine. CRC Press. p. 316–317. ISBN 0849308399.
- ^ "The IUCN Red List of Threatened Species". International Union for Conservation of Nature and Natural Resources. http://www.iucnredlist.org/apps/redlist/details/6335/0/full. Retrieved 2008-10-17.
- ^ "Endangered and Threatened Species; Endangered Status for the Cook Inlet Beluga Whale". National Oceanic and Atmospheric Administration. 2008-10-22. http://www.nmfs.noaa.gov/pr/pdfs/fr/fr73-62919.pdf. Retrieved 2009-08-26.
- ^ Herbert, H. Josef (October 17, 2008). "Government declares beluga whale endangered". Associated Press. http://ap.google.com/article/ALeqM5gJx0IzvRt6GWrUBb90Foe4URCGagD93SD0DO0. Retrieved 2008-10-17.
- ^ Angliss and Outlaw 2007.
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.
Source:
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Names and Taxonomy
Taxonomy
Comments: Brennin et al. (1997) examined mtDNA variation in North American populations and detected two distinct groups, one occurring primarily from the St. Lawrence estuary and eastern Hudson Bay and the other primarily in western Hudson Bay, southern Baffin Island, western Greenland, the Canadian High Arctic, and the eastern Beaufort Sea
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