The Beluga Whale (Delphinapterus leucas) and the Narwhal (Monodon monoceros) are the only two species in the cetacean family Monodontidae (Rice 1998). While these are well defined taxa, Heide-Jørgensen and Reeves (1993) described a skull from West Greenland of what apparently was a Narwhal-Beluga hybrid. Some early Russian researchers split Belugas into three species or subspecies, but that approach was rejected by Kleinenberg et al. (1964) and Rice (1998).

While Belugas occur broadly in Arctic and Subarctic waters, their distribution, movements, and life history characteristics suggest the existence of numerous subpopulations or management stocks using a diverse range of habitats (e.g., Frost and Lowry 1990, Heide-Jørgensen and Wiig 2002). Studies using genetic markers have confirmed the existence of at least 21 subpopulations that are largely demographically isolated (O’Corry-Crowe et al. 1997, 2010; Brown-Gladden et al. 1999, de March et al. 2002, Laidre et al. 2015). The pattern of subpopulation isolation in the Pacific likely results from relatively rapid dispersal into new habitats following recession of the last Pleistocene ice sheets (O’Corry-Crowe et al. 1997). Land masses and heavy sea ice cover limit interchange between subpopulations across the Arctic, as does strong site fidelity, but climate oscillations in the Holocene may have provided relatively recent opportunities for subpopulations to mix (O’Corry-Crowe et al. 2010).

The Beluga Whale is widely distributed in a number of distinct subpopulations, most recently set at 21 (NAMMCO in prep.), but the number varies according to the source or authority. Combining the most current abundance estimates for the various subpopulations results in a total of more than 195,000 whales. Given that there are no estimates for most of the Russian High Arctic, total abundance is likely more than 200,000. At least four subpopulations number more than 20,000 individuals. Some subpopulations are reduced below historical levels and some small subpopulations are declining but data are not adequate to assess overall population reduction or trend. As a species, Beluga Whales do not meet any IUCN criteria for threatened categories and are listed as Least Concern.

Belugas in Cook Inlet have been assessed by IUCN as a separate subpopulation and are classified on the Red List as Critically Endangered (Lowry et al. 2012). Several other subpopulations are small, declining, and/or occupy restricted areas, and warrant Red List assessment at the subpopulation level.

Kleinenberg et al. (1964) correctly noted that “The Beluga is widely distributed throughout the northern seas.” More recent and more detailed mapping (e.g., Reeves et al. 2014) confirms that Belugas are widely distributed in Arctic regions, occurring nearly throughout northern waters of Russia, Alaska, Canada, West Greenland, and Svalbard. Gaps in the distribution occur off North and East Greenland and perhaps in central Russia. Sightings and telemetry studies show that Belugas occur north of 80° N latitude at Svalbard (Vacquié-Garcia et al. 2017), and north of western Russia (Belikov and Boltunov 2002) and Alaska (Suydam et al. 2001). Subpopulations in the Okhotsk Sea and the Gulf of Saint Lawrence occur in Subarctic waters as far south as 50° N (Shpak et al. 2010) and 47° N (Lefebvre et al. 2012) respectively. Belugas have been recorded as vagrant at Japan, New Jersey and Washington State USA, Iceland, Faroe Islands, Ireland, Scotland, France, the Netherlands, and Denmark (Rice 1998).

The global Beluga population consists of multiple subpopulations with varying degrees of differentiation and abundance (hereafter the terms subpopulation and stock are used interchangeably). Due to the lack of sampling, particularly in Russia, the total number of subpopulations is not precisely known. In 1999, the International Whaling Commission’s (IWC) Scientific Committee organized information on Belugas on the basis of 29 provisional management stocks (IWC 2000), and a recent (March 2017) Global Review of Monodontids hosted by the North Atlantic Marine Mammal Commission (NAMMCO) developed a list of 21 stocks (NAMMCO in prep.).

Stocks are generally based on nearshore areas (principally fjords, bays, and estuaries) where Belugas congregate during part of the open water season. Satellite telemetry, genetic studies, and organochlorine analyses have shown that Belugas have strong matrilineally driven fidelity to those areas (O’Corry-Crowe et al. 1997, 2002; Richard et al. 2001, de March et al. 2002, Innes et al. 2002, Palsbøll et al. 2002). Some stock boundaries overlap spatially and seasonally during winter and during the spring and fall migrations (Hauser et al. 2014). For stocks that winter in the Bering Sea, limited satellite tracking data suggest that areas used generally do not overlap in the same year, suggesting that Belugas from different stocks have traditional winter ranges that are mostly exclusive (Citta et al. 2017).

While good abundance estimates are available for some Beluga subpopulations, the sizes of others are virtually unknown or only roughly approximated (Laidre et al. 2015). Available information is summarized below.

Okhotsk Sea

Belugas occur in two well-separated regions of the Okhotsk Sea. In the northeastern region, they summer along the coast and in estuaries of Shelikhov Bay and winter along the ice edge of the Bay and northwestern Kamchatka. Based on surveys in 2010, Shpak and Glazov (2013) estimated there were 1,333 surface-visible Belugas in the northeastern Okhotsk Sea, resulting in an estimate of 2,666 total whales when corrected for availability bias (animals not seen because they were diving). In the western Okhotsk Sea, Belugas occur in the northern Sakhalin Bay and Amur River region as well as several smaller bays along the Shantar coast (Ulbansky Bay, Udskaya Bay, Tugursky Bay and Nikolskaya Bay. There Shpak and Glazov (2013) estimated 4,780 visible Belugas and 9,560 in total. The population trend is unknown in both regions.

Alaska and Western Canada

Five subpopulations of Belugas are known to occur in the Bering, Chukchi, and Beaufort seas. All five winter in the Bering Sea (Citta et al. 2017). The eastern Chukchi Sea and eastern Beaufort Sea subpopulations migrate northward in spring and spend summer and early fall well north of Bering Strait (Richard et al. 2001, Suydam 2009, Hauser et al. 2014), while the Bristol Bay, Anadyr Gulf, and eastern Bering Sea subpopulations remain in the Bering Sea south of Bering Strait (Citta et al. 2016, NAMMCO in prep., Alaska Beluga Whale Committee (ABWC) unpublished data).

Bristol Bay Belugas have been counted using aerial surveys conducted periodically between 1993 and 2016. Correction factors to account for animals missed were applied to counts made in 2004 and 2005 (Lowry et al. 2008) which produced an abundance estimate of 2,887 whales (Muto et al. 2016). Similar correction factors applied to the 2016 count resulted in a population estimate of 3,166 whales (ABWC unpublished data). Lowry et al. (2008) reported that counts of Bristol Bay Belugas increased by 4.8% per year during 1993-2005 (95% confidence interval (CI) 2.1–7.5%). The estimate based on 2016 counts was similar to 2004/05 suggesting that the increasing population trend had leveled off (ABWC unpublished data).

Belugas in Anadyr Gulf have never been surveyed adequately. An analysis of Beluga sightings obtained opportunistically during a survey for Pacific Walruses (Odobenus rosmarus divergens) conducted in the western Bering Sea in April 2006 estimated 15,125 Belugas in the area (with availability correction factor applied). However, the survey did not cover all areas known to be used by Anadyr Belugas, and it is possible that individuals from other subpopulations were also in the survey area. The maximum count along the coast in Anadyr Bay was 241 whales, and expert opinion suggests that the total Anadyr subpopulation is about 3,000 whales with fairly stable abundance (NAMMCO in prep.).

Aerial surveys for Belugas were flown in the eastern Bering Sea periodically during 1992-2001. Data collected in 2000 were used in distance sampling analysis that resulted in an estimate of 3,497 surface-visible Belugas in the survey area. The total abundance estimate was 6,994 whales (95% CI 3,162-15,472) when a correction factor for availability was applied (Lowry et al. in press). There are currently no data with which to estimate population trend, but another survey of the subpopulation was conducted in 2017.

Early estimates of the size of the eastern Chukchi Sea Beluga stock relied on June-July counts of whales in and near coastal lagoons with correction factors applied to account for animals missed. Those studies resulted in abundance estimates of roughly 2,000-4,000 whales (Seaman et al. 1988, Frost et al. 1993, Muto et al. 2016). Subsequent tagging of whales with satellite depth recorders (SDRs) showed that during summer they had a very broad distribution, including considerable time spent in offshore areas where they were missed during coastal lagoon surveys (Suydam 2009). Further analysis of SDR data from eastern Chukchi Sea and eastern Beaufort Sea Belugas (Hauser et al. 2014) showed there is a date range and region where data from offshore marine mammal surveys (Aerial Surveys of Alaskan Marine Mammals (ASAMM); Clarke et al. 2013) could be used to estimate abundance of the eastern Chukchi subpopulation. That analysis (Lowry et al. 2017) estimated there were 5,547 (CV 0.22) surface-visible Belugas in the study area in 2012. Data from SDRs were used to develop correction factors to account for animals that were missed because they were outside of the study area or diving too deep to be seen, resulting in a total abundance estimate of 20,752 whales (CV 0.70). Trend in abundance is unknown but there are several other years of ASAMM survey data that could be analyzed to look for changes over time.

The most recent estimate of abundance for the eastern Beaufort Sea Beluga stock is 39,258 whales (Muto et al. 2016). This number was derived from aerial surveys conducted in the Mackenzie Delta and eastern Beaufort Sea in 1992 that estimated 19,629 (CV 0.23) surface visible Belugas (Harwood et al. 1996) and a correction factor to account for submerged whales. Synoptic surveys for Belugas were conducted in the region only in 1992, but Beluga sightings were recorded during offshore Bowhead Whale (Balaena mysticetus) surveys in 1982, 1984, 1985, and 2007-09. The number of Belugas counted at the surface was substantially higher during the 2007-09 surveys but it is unclear whether this was due to a shift in distribution or population increase (Harwood and Kingsley 2013).

An isolated subpopulation of Belugas occurs in Cook Inlet, Alaska where they reside throughout the year (Hobbs et al. 2005, Goetz et al. 2012, Shelden et al. 2015a). Sightings are occasionally made outside of Cook Inlet in the Gulf of Alaska (Laidre et al. 2000), and there is a small group (< 20 animals) that is apparently resident in Yakutat Bay approximately 600 km to the east (O’Corry-Crowe et al. 2015) and is considered to be part of the Cook Inlet stock (Muto et al. 2016). Beluga abundance in the Inlet, including corrections for availability and sightability, is determined using aerial counts and video analysis of whale groups (Hobbs et al. 2000). The 2014 survey produced an estimate of 340 whales (CV 0.08; Shelden et al. 2015b). Abundance declined by nearly 50% between 1988 and 1994, and by about 1.3%/year during 1994-2014 (Hobbs et al. 2015, Shelden et al. 2015b).

Eastern Canada and Greenland

There are currently three main population centers for Belugas in Arctic Canada, High Arctic-Baffin Bay (HA-BB), Cumberland Sound, and Hudson Bay. A subpopulation that once occurred in southwest Greenland in winter is likely extirpated (NAMMCO in prep.). HA-BB Belugas summer mostly in nearshore waters around Somerset Island (Koski and Davis 1980, Smith and Martin 1994) and winter in northern Baffin Bay and off West Greenland (Doidge and Finley 1993, Heide-Jørgensen and Laidre 2004). An aerial survey of the Canadian High Arctic in summer 1996 produced an availability-adjusted abundance estimate of 21,213 whales (95% CI 10,985-32,619; Innes et al. 2002). A 2012 winter survey off West Greenland resulted in a corrected estimate of 9,072 Belugas (CV 0.32) (Heide-Jørgensen et al. 2017). Modeling by Innes and Stewart (2002) indicated a major decline in HA-BB Beluga abundance occurred between 1981 and 1994. Current trend in abundance is unknown.

The Cumberland Sound Beluga subpopulation remains in the Cumberland Sound area throughout the year (Richard and Stewart 2008). Aerial surveys were conducted in typically used portions of the Sound in 2014, and abundance was estimated using a combination of visual surveys and photographic counts. The total abundance estimate (corrected for availability bias) was 1,151 whales (95% CI 761–1,744; Marcoux et al. 2016). Marcoux and Hammill (2016) constructed a model of this subpopulation using survey data collected during 1980-2014 and harvest data for 1920-2015. Results indicated that current abundance is substantially reduced compared to 1960 and that abundance is still declining.

Four Beluga stocks occur in the Hudson Bay region. The eastern Hudson Bay (EHB) and western Hudson Bay (WHB) stocks summer in the regions for which they are named and winter principally in Hudson Strait (NAMMCO in prep.). Although some interbreeding occurs on the wintering grounds (Turgeon et al. 2012), genetic studies show that the two groups are distinct (deMarch et al. 2003). Colbeck et al. (2012) found that cultural transmission of migration routes exists which likely acts to minimize interchange between the groups. Systematic aerial surveys of EHB Belugas have been flown seven times since 1985. Surveys flown in 2015 produced an availability-corrected estimate of abundance of 3,819 whales (CV 0.43; Gosselin et al. 2017). Modeling of the series of survey estimates and harvest data for 1972-2016 indicates that abundance declined during 1974-2002, but has been stable since then (Hammill et al. 2017). Abundance of WHB Belugas was most recently estimated from visual and photographic aerial surveys flown in summer 2015. The availability-corrected estimate of total abundance was 54,473 whales (95% CI 44,988-65,957; Matthews et al. 2017). Because of bad weather conditions, this estimate did not include the Ontario coast where nearly 15,000 whales were estimated in 2004 (Richard 2005). A comparison of surface abundance estimates from 2015 and 2004 for five strata surveyed in both years showed that 2015 counts were about 6% higher (NAMMCO in prep.). Belugas use James Bay in large numbers during the summer and remain in that region during winter (Bailleul et al. 2012). The 2015 aerial survey estimated availability-corrected abundance as 10,615 (CV 0.25; Gosselin et al. 2017). Estimates from similar surveys conducted from1985 to 2011 ranged from 4,720 to 19,439 whales so the trend in abundance is unclear. Belugas were once abundant in Ungava Bay, with summer aggregations in and near several rivers. Numbers are now greatly diminished with no animals sighted on-transect during aerial surveys conducted there since 1983 (NAMMCO in prep.). However, some Belugas still occur occasionally in the area as indicated by off-transect sightings during aerial surveys (Kingsley 2000) and land-based sightings (Doidge et al. 1994). Using data from surveys conducted during 1985-2008, Doniol-Valcroze and Hammill (2012) estimated Ungava Bay Beluga abundance to be 32 individuals (95% CI 0-94).

 A relict subpopulation of Belugas occurs in the Saint Lawrence River estuary (SLE) that is isolated from all other subpopulations both geographically and genetically (Brown Gladden et al. 1999; de March and Postma 2003). Both the core range used in summer and the total range of SLE Belugas have shrunk considerably since the 1930s (Mosnier et al. 2010). The size of the SLE subpopulation is believed to have declined from 7,800 whales in the 1866 to about 1,000 in 1985 (Hammill et al. 2007). Abundance has been monitored since 1988 using photographic aerial surveys. An integrated population model using survey counts and vital rates indicated that abundance increased slowly between the 1960s and early 2000s then declined to an estimated 889 in 2012 (Mosnier et al. 2015).

Svalbard and Russian Arctic

The Svalbard Beluga subpopulation is geographically isolated and genetically differentiated from subpopulations to the east and west (O’Corry-Crowe et al. 2010). During the ice-free season Belugas in the archipelago are found very nearshore, often at the faces of glaciers (Lydersen et al. 2001). During winter, sea ice formation causes them to move offshore somewhat but they remain in the Svalbard area (Lydersen et al. 2002). Currently there is no abundance estimate for Svalbard Belugas but the first ever survey was to be conducted in summer 2017 (NAMMCO in prep.).

The Beluga subpopulation in the White Sea is genetically differentiated from other subpopulations (NAMMCO in prep.). In summer, the whales are seen in several aggregation areas in the major bays (Andrianov et al., 2009, Glazov et al. 2010a, Alekseeva et al., 2012). While some investigators believe that in winter Belugas move to the Barents Sea, they are seen in the White Sea in March (Glazov et al. 2010b) and all of the Belugas tracked with satellite-linked tags have stayed in the White Sea (Glazov et al. 2012, Svetochev and Svetocheva 2012, Kuznetsova et al. 2016). Aerial surveys for belugas were flown in the White Sea in July six times during 2005-2011. The abundance estimate for 2011 was 5,593 whales (CV 0.14), and estimates from prior years ranged from 5,009 to 7,464 (Solovyev et al. 2012a). Available data suggest that abundance is stable.

Belugas have been recorded at many other locations along the Arctic coast of Russia, including the Kara, Barents, Laptev, and East Siberian seas as well as Nova Zemlya and Franz Josef Land (Kleinenberg et al. 1964, Solovyev et al. 2012b). A compilation of observations made during 1958-1995 from sea ice reconnaissance flights showed many sightings in coastal and offshore waters from the Barents Sea to the Kara Sea but few observations in the East Siberian Sea (Belikov and Boltunov 2002). Boltunov and Belikov (2002) considered that the primary summer habitats are near Franz Josef Land and in the Kara Sea and western Laptev Sea, and that most of Belugas from this region winter in the Barents Sea. There are no estimates of current abundance, but given the size of the area and the number of animals taken by historical whaling (Boltunov and Belikov 2002), it is likely that Belugas were once numerous there.

Population Summary

Summing the various estimates above gives a total of approximately 195,000 Belugas in the surveyed subpopulations. Because no abundance estimates are available for Svalbard and the Russian High Arctic and the estimate for the White Sea is not corrected for availability, it is nearly certain that total rangewide abundance is more than 200,000. Taylor et al. (2007) calculated that in a pristine Beluga population 68% of all individuals would be mature. Using that value the total number of mature Belugas is estimated at about 136,000. The number of mature Belugas in the largest subpopulation, WHB, is about 37,000.

Generation time is an important parameter for several of the IUCN Red List criteria, and calculations of generation time require an accurate method for determining or estimating ages of individuals. For Beluga Whales, this has been done primarily by counting layers in the teeth of harvested or stranded animals. Counts of growth layer groups (GLGs) have usually been converted to age in years assuming there were two GLGs formed each year (Brodie 1971, Sergeant 1973, Burns and Seaman 1988, Heide-Jørgensen et al. 1994). Formation of two GLGs per year was supported by examination of teeth from captive, known age, individuals (Brodie 1982, Goren et al. 1987, Heide-Jørgensen et al. 1994). Stewart et al. (2006) measured the incorporation of atomic bomb radiocarbon into Beluga tooth GLGs, and used those measures to estimate age. When those estimates were compared to ages based on formation of one GLG versus two GLGs/year, the data fit the one GLG/year assumption. Lockyer et al. (2007) examined 10 teeth from captive Belugas and found clear support for one GLG/year in six of the specimens, but results for the others were equivocal. Hohn et al. (2016) considered that the bomb radiocarbon study and long-term photoidentification studies showed that GLG deposition is “unquestionably annual.” (also see Matthews and Ferguson 2014). However, Brodie et al. (2013) continued to argue for two GLGs/year, based on field observations of Beluga life history parameters in Cumberland Sound, captive animal studies, and suggested problems with studies that support one GLG/year. Using the assumption of two GLGs/year, Taylor et al. (2007) estimated generation time for belugas as 16.4 years for a population in a pre-disturbance state. If one GLG/year is actually the case, generation time would be much longer, but calculations using that assumption have not been done.

Data on historical sizes of Beluga subpopulations are sparse. Innes and Stewart (2002) estimated the historical carrying capacity (K) of the HA-BB subpopulation as 39,790 whales. Bettridge et al. (2016) estimated K for Sakhalin - Amur Belugas as between 13,200 and 20,800. Cumberland Sound Belugas were estimated to number 3,100 in 1960 (Marcoux and Hammill 2016). Hammill et al. (2017) estimated that there were 6,663 Belugas in EHB in 1974. Abundance of Cook Inlet Belugas in 1979 was estimated at 1,293 (NMFS 2003). Hammill et al. (2007) estimated that there were 7,800 Belugas (standard error 600) in the SLE in 1866. Comparing these figures with those for the most recent abundance estimates given above suggests a reduction of 88% for SLE belugas, and 28-74% for the other five subpopulations. While these comparisons show that some stocks have been substantially depleted and remain in that state, a species-wide reduction in abundance cannot be calculated. The difficulty of such a calculation is compounded by the lack of agreement on calibration of tooth layers for age estimation, which is central to determining generation length and the amount of depletion over time. The combined abundance of those six subpopulations known to be depleted constitutes less than 20% of the current species-wide abundance estimate, and there is no reason to think that all of the remaining subpopulations are similarly depleted.

Belugas are relatively well-studied as a result of carcass sampling conducted in association with hunting (Heide-Jørgensen and Teilmann 1994, Suydam 2009) along with a considerable amount of satellite-linked radio-tracking (Richard et al. 1998a,b, Richard et al. 2001, Lydersen et al. 2001, Heide-Jørgensen et al. 2003a, Hobbs et al. 2005), and aerial survey efforts (Moore, 2000, Belikov and Boltunov 2002, Innes et al. 2002).

Belugas occupy estuaries, continental shelf and slope waters, and deep ocean basins in conditions of open water, loose ice, and heavy pack ice (Hauser et al. 2017). In summer, they are found in coastal waters as shallow as 1–3 m deep and also in offshore waters thousands of meters deep. 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 (Kleinenberg et al. 1964). Belugas generally prefer to overwinter in areas with light or highly moveable ice cover (Barber et al. 2001, Richard et al. 2001, Suydam et al. 2001, Heide-Jørgensen et al. 2003a, Citta et al. 2017) and may occur as fully Arctic subpopulations (Richard et al. 1998b, 2001; Suydam et al. 2001) or Subarctic subpopulations (Hobbs et al. 2005).

Some Belugas undertake large-scale annual migrations between summering and wintering sites (Hauser et al. 2014), 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 80°N 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. 2003). In some areas, beluga distribution appears to be determined by sea ice extent, with belugas shifting offshore during low-ice years to maintain associations with the marginal ice zone (Heide-Jørgensen et al. 2010). 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 St. Lawrence Estuary (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 subpopulations, the importance of those features is not well understood (Laidre et al. 2008). 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 according to the environmental conditions (e.g., water temperatures and prey availability) specific to each of the summering areas (Frost and Lowry 1990). Similarly, it is unclear why Belugas sometimes move into deep, ice-covered waters (Hauser et al. 2016). One potential reason would be to avoid predation by Killer Whales (Orcinus orca) (Frost et al. 1992). However, 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. 1987) as well as increase the risk of entrapment in the ice. It is possible that Belugas move into ice-covered offshore regions for feeding, primarily on Arctic Cod (Boreogadus saida), but few data are available to test this hypothesis (Hauser et al. 2015). Similarly, the associations of Belugas with features such as the continental shelf break and slope (Moore 2000, Hauser et al. 2017) may be related to biophysical processes that produce good feeding conditions (Laidre et al. 2008).

Beluga dives may last more than 20 minutes and can reach depths of more than 900 m (Hauser et al. 2015). 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 (Oncorhynchus spp.), Herring (Clupea spp.), and Arctic Cod), Belugas also feed on a wide variety of mollusks (such as squid and octopus) and benthic crustaceans (shrimps and crabs) (Quakenbush et al. 2015, Kleinenberg et al. 1964). Polar Bears and Killer Whales are known predators of Belugas throughout their Arctic range (Frost et al. 1992).

The Conservation of Arctic Flora and Fauna (CAFF) Arctic Biodiversity Assessment (CAFF 2013) lists threats to arctic marine mammals as harvest, loss of sea ice, human activities, pollution, and disease. Belugas are susceptible to all those threats, but their importance varies among the many Beluga subpopulations.

Hunting for human consumption is the biggest known threat to Belugas across certain portions of their range. The most immediate concerns relate to continuing harvests from small and depleted subpopulations (IWC 2000). The strong philopatry of Belugas, which causes them to return to the same estuaries year after year, makes them highly vulnerable to overexploitation. This behavioural trait is undoubtedly the most important natural factor that has led to the extirpation of Belugas from some parts of their range by a combination of commercial and subsistence hunting (e.g., in southwestern Greenland and some river mouths in Ungava Bay, Canada). In nearly all regions hunting is now being controlled by limiting takes to sustainable levels (see the Conservation Actions section).

Ongoing climate change is resulting in substantial reduction in the seasonal extent and thickness of sea ice in the Arctic (Comiso 2012, Stroeve et al. 2012), as well as changes in timing of sea ice formation and breakup (Laidre et al. 2015). Belugas occur only in regions where sea ice occurs at least seasonally, suggesting a strong connection with sea ice influenced habitat. However, Belugas from some subpopulations spend many months in open water far from any ice while others spend most of their time in regions with sea ice concentrations up to 90%, indicating that the species as a whole has substantial flexibility in its relationships with ice (Hauser et al. 2017). Belugas that occupy ice covered areas may do so for feeding on abundant ice-associated species such as Arctic Cod (Loseto et al. 2009, Hauser et al. 2015). Changes in the distribution and characteristics of sea ice will result in changes in productivity and prey species types and abundance (Laidre et al. 2008, Haug et al. 2017) but the potential costs or benefits to Belugas of such changes are not known. Killer Whales are known predators of Belugas (Frost et al. 1992) and it is generally assumed that concentrated sea ice provides Belugas some degree of refuge from predation. There is good evidence that Killer Whales are expanding their range in Arctic regions where sea ice has been declining (Higdon and Ferguson 2009, Ferguson et al. 2010). Belugas are susceptible to entrapment when sea ice conditions change rapidly and if they cannot escape they may die or be preyed upon by Polar Bears and/or humans (Lowry et al. 1987, Heide-Jørgensen et al. 2002).

Known or potential threats include a variety of human activities in addition to hunting, and climate change is allowing increases in the scale and distribution of some of those activities in areas previously covered with heavy ice. Ongoing and expanding oil and gas development, along with commercial shipping, is likely to impact habitats used by Belugas. Such impacts may be especially acute in shipping routes such as the Northwest Passage which traverses much of the summering habitat of belugas in Canada and Greenland (Reeves et al. 2014). Areas such as the Mackenzie Delta, West Greenland, and the Barents Sea are subject to oil and gas exploration and development, which may include seismic surveys, offshore drilling, and artificial island construction, accompanied by icebreaking and shipping. Much of this activity is undertaken in the summer months in the same areas occupied by Belugas. In a study of responses of Belugas to icebreaking ships, the whales 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, Erbe and Farmer 2000). Expansion of commercial fisheries into new Arctic regions may have implications for bycatch of Belugas in fishing gear and depletion of Beluga prey resources. Construction of dams for hydroelectric development in the Hudson Bay area and along the north shore of the Gulf of St. Lawrence may have affected Belugas because of their dependence on estuarine conditions (Smith et al. 2017).

Pollution from industrial and other sources is pervasive in the world’s oceans and marine mammals are known to accumulate levels of contaminants from those sources that are high enough to cause impacts on health (Ross 2000). Threats from contaminants are of concern for Belugas in some areas. High levels of several contaminants have been found in Belugas sampled in the Canadian Arctic (Braune et al. 2005). Studies of the SLE Beluga subpopulation have found that concentrations of both total polychlorinated biphenyls (PCBs) and chlorinated PCB congeners are much higher than in Belugas in the Arctic. Some scientists believe that the increased occurrence of opportunistic bacterial infections, parasitic infestation, gastric ulcers and other disorders in SLE Belugas is evidence of a link between immune system dysfunction and PCB exposure (Martineau et al., 1994). SLE Belugas also have elevated tissue levels of polybrominated diphenyl ethers (flame retardants) (Lebeuf et al. 2004).

Like other marine mammals, Belugas are exposed to a number of diseases that may influence their population status (Gulland and Hall 2005). Significant epizootics have not been recorded in Belugas, but serological screenings document pathogen exposure (e.g., Alekseev et al. 2009) and necropsies find a variety of health issues (e.g., Martineau et al. 1988). Lefebvre et al. (2016) found low level exposure to biotoxins (domoic acid 2 of 15 tested and saxitoxin 1 of 12 tested) in Beluga samples from Cook Inlet. A mass mortality event in summer 2008 in the SLE, which included several Belugas, was linked to an intense bloom of the toxic dinoflagellate Alexandrium tamarense (Starr et al. 2017). Burek et al. (2008) described ways in which climate change could impact disease exposure for arctic marine mammals.

In the past Belugas were hunted commercially at several locations but that is no longer the case. They are legally hunted for food by indigenous communities in several parts of their range, including western and northern Alaska (Frost and Suydam 2010), western and eastern Canada (Harwood et al. 2002, Mosnier et al. 2017), some parts of Russia (D. Litovka pers. comm.), and Greenland (Heide-Jørgensen and Rosing-Asvid 2002, Heide-Jørgensen et al. 2017). Legally-harvested Beluga products may be sold in Alaska Native communities. Some illegal hunting may also occur, particularly in parts of Russia (NAMMCO, in prep.). Russia allows Belugas in the White Sea and in the Sakhalin Bay - Amur River delta region to be live-captured for public display. Numbers taken in the White Sea are small (probably 5-6 or fewer per year, NAMMCO, in prep.). The number live-captured at Sakahlin is more substantial, 0-81 per year during 2000-2017 (Shpak and Glazov 2014, NAMMCO, in prep.). Reeves et al. (2011) calculated the sustainable annual removal of Belugas from the Sakhalin subpopulation to be 29 whales. Records of historical kills were used in a population model to estimate that the Sakhalin - Amur subpopulation meets the definition of depleted under the U.S. Marine Mammal Protection Act, which disallows imports for live display into the U.S. (Bettridge et al. 2016). 

Although Belugas were hunted intensively on a commercial basis for oil and leather in many parts of their range during the 20th century, the only known direct removals at present are for food (subsistence use) and the aquarium trade. The Canada-Greenland Joint Commission on Conservation and Management of Narwhal and Beluga (JCNB) is expected to ensure the conservation of shared stocks of Belugas while NAMMCO is a regional management body to which Canada, Greenland, and Norway belong. Catch limits and other recommendations on conservation of belugas are made on the basis of advice from joint meetings of the JCNB’s Scientific Working Group and NAMMCO’s Scientific Committee Working Group on the Population Status of Narwhal and Beluga in the North Atlantic. Catch levels from hunted Beluga subpopulations range anywhere from less than ten to a few hundred animals per year. There is concern that Cumberland Sound Belugas are being hunted at unsustainable levels (NAMMCO, in prep.). Removals from the Bristol Bay, Eastern Bering Sea, Eastern Chukchi Sea, and Eastern Beaufort Sea subpopulations are considered sustainable (Muto et al. 2016). In both Canada (Richard and Pike 1993) and Alaska (Adams et al. 1993), indigenous peoples’ organizations have entered into co-management agreements with government agencies to work on conservation of Beluga stocks. Harvests from the Eastern Beaufort Sea subpopulation occur in both Alaska and Canada, and that is managed by an agreement between the North Slope Borough (Alaska) and the Inuvialuit Game Council (Canada).

As a species, the Beluga is listed on Appendix II of the Convention on International Trade in Endangered Species. The SLE Beluga subpopulation is listed as endangered and the Cumberland Sound subpopulation as threatened under the Canadian Species at Risk Act. The Cook Inlet Beluga subpopulation is listed as endangered under the U.S. Endangered Species Act. The Sakhalin subpopulation is listed as depleted under the U.S. Marine Mammal Protection Act. In Svalbard, the Beluga is a protected species.