AMMPA Standardized Information:
Last updated 10/11/12
Cetacea (current grouping unranked)
- Cetacea is one of only two scientific orders of large aquatic mammals that live their entire lives in water (Sireniais the other). Cetaceans include all whales, dolphins and porpoises.
- The word “cetacean” is derived from the Greek word for whale, kētos.
- Living cetaceans are divided into two suborders: Odontoceti (toothed whales) and Mysticeti (baleen whales).
Odontoceti (current grouping unranked)
- The scientific suborder, Odontoceti, is comprised of toothed whales.
- The word “Odontoceti” comes from the Greek word for tooth, odontos.
- These whales also have only one blowhole opening.
- The structural differences in the skulls and the melons of Odontocetes enable specialized echolocation (Hooker, 2002).
- With the exception of the sperm whale, toothed whales are smaller than most baleen whales.
- Belugas, along with their closest living relative, the narwhal (Monodon monoceros), are the only living members of the family Monodontidae.
- The word “Monodontidae” comes from the Greek for “one tooth,” a reference to the tusk of the male narwhal. This is a misnomer for beluga whales because they possess many teeth (Reeves et al., 2002).
- Belugas are the only living member of the genus Delphinapterus.
- Delphinapterus derives from the Greek words delphinos (“dolphin”), a (“without”) and pteron (“fin” or “wing”). Belugas lack a dorsal fin, hence the name “dolphin without a fin.”
- In spite of how the name ‘Delphinapterus’ sounds, belugas are not dolphins, which is a term reserved for members of the family Delphinidae (Leatherwood et al.,1988).
- The genus and species (see below) were identified in 1776 by Pallas.
- The species name comes from the Greek word for “white,” leukos, referring to the color of the adult beluga.
- The common name beluga comes from the Russian word for “white”, beloye (O’Corry-Crowe, 2009).The name has led to some confusion with the beluga sturgeon (a white sturgeon), a freshwater fish from which beluga caviar is derived.
Early whales evolved over 50 million years ago from primitive mammals that returned to the sea (Barnes, 1990).
Recent mitochondrial and nuclear DNA analyses suggest that cetaceans are distant cousins of even-toed ungulates (artiodactyls) and that hippopatamids are the closest living relative to cetaceans (Berta and Sumich, 1999; Reynolds et al., 2000; Milinkovitch et al., 1993).
Around 35 million years ago, both odontocete and mysticete cetaceans evolved and diversified rapidly; most likely due to new food resources resulting from oceanic change (Fordyce, 2002).
The earliest fossil monodontid is that of an extinct beluga (Denebola brachycephala), which lived along the coast of Baja California, Mexico, about 10 million years ago (O'Corry-Crowe, 2008). Less than 4 million years ago, now-extinct monodontids lived only in temperate and subtropical waters.
The earliest fossil of a beluga and narwhal as we know them today were found in Canada. Delphinapterus leucas fossils, less than 2 million years old and found in northeastern North America, show that the distribution of the beluga changed as the glacial cover of the oceans altered (Berta and Sumich, 2003; O'Corry-Crowe, 2002).
Belugas are only found in the Northern Hemisphere—in Arctic and subarctic waters. Discrete populations are found off the coasts of Alaska, Canada, Russia, Norway and Greenland (Martin, 1996). Occasionally, belugas travel much farther south; lone belugas have been sighted in Long Island Sound and near Cape Cod and in the Delaware River in New Jersey (Frady, 2004; Katona et al., 1993; www.msnbc.msn.com/id/7486673/ns/us_news-environment/t/whale-still-hanging-out-delaware-river/#.UAblMWHWZOU).
Though all living belugas belong to the same species and are generally confined to Arctic regions, they are further classified by “stocks” (or subpopulations) (COSEWIC, 2004; IWC, 2000; Martin and Richard, 2001). These may be genetically isolated from others stocks. Stocks are also identified by distribution and migration patterns, morphological characteristics, and DNA. All stocks are found in the waters of Alaska, Canada, Russia, Norway and Greenland (IWC, 2000). Stocks vary in population size with some as small as a few hundred animals and others perhaps as large as 30,000 animals (Hobbs and Sheldon, 2008; Angliss and Outlaw, 2005; IWC, 2000; DFO, 2005; COSEWIC, 2004).
Some beluga populations make seasonal migrations, while others remain in a relatively small areas year-round (Nowak, 1991; Leatherwood and Reeves, 1983). Belugas migrate south as the ice pack advances in the autumn. They leave areas of pack ice and move to shallow, brackish estuaries and river mouths in the summer. This indicates that belugas can move freely between salt and fresh water, something most other cetaceans cannot do (Martin, 1996). In addition, belugas have been sighted in depths that vary from extremely shallow to deep underwater trenches (Schreer and Kovacs, 1997).
Belugas experience water temperatures that range from 0° C (32° F) to more than 16° C (61° F), but are closer to freezing much of the year (Leatherwood et al., 1988; Smith et al., 1994). Some waters are so cold that when a beluga rests at the surface, the water freezes and forms an ice dome molded by the beluga’s back. These domes then remain intact when the whale swims away (Leatherwood et al., 1988). Belugas are extremely comfortable among sea ice; satellite-tagged belugas have traveled from the northwest coast of Alaska north through sea ice concentrations of almost 100% (Suydam et al. 2001).
The summer grounds of belugas generally include an estuary. Belugas show a high degree of site fidelity, with stocks returning to the same estuaries year after year (COSEWIC, 2004). Genetic evidence also suggests that the stocks have been visiting separate estuaries for long periods, perhaps since glaciers receded at the end of the last Ice Age, with only limited genetic exchange between the different groups (O'Corry-Crowe, 2008). Rubbing is frequently observed in these areas and is tied to the seasonal epidermal molt of the beluga (Smith et al., 1992). The completion of the molting process and the benefit of warm waters to dependent neonate calves with their thin blubber layer may be the most important reasons for the belugas’ migration into estuaries Females and their calves are especially tied to the estuary and are the first to return after a disturbance, such as boats or hunting (O'Corry-Crowe et al., 1997).
Belugas have the most varied diet of any small whale (Gurevich, 1980). Diet varies with season and location, and food intake changes with water temperature (Balsiger, 2003). Belugas are opportunistic feeders, preying upon over 100 species of fish and invertebrates throughout their range (Gurevich, 1980). Known prey of belugas include: marine fish (Arctic cod, salmon, herring, haddock, Arctic char, flounder, smelt, sole, sculpin, skates and halibut), freshwater fish (trout, whitefish, northern pike, grayling and tomcod), cephalopods (squids and octopuses), other mollusks (clams, mussels and snails), crustaceans (shrimp and crabs), marine worms and even zooplankton (Balsiger, 2003; Katona et al., 1993; Kleinenberg et al., 1969; Martin, 1996; Reidenberg and Laitman, 2002). Because of their expandable forestomach, belugas can process a large amount of food at once. One whale was found in the Cook Inlet with 12 adult coho salmon in its stomach, weighing a total of 62 lbs (28 kg) (Balsiger, 2003).
Anatomy and Physiology
The white color for which belugas are named does not appear until an animal reaches maturity. Calves are born a light brown-grey color, which darkens before turning the characteristic white (Kleinenberg et al., 1969). In adults, dark pigment is often present on the top of the dorsal ridge and along the edges of the flukes and pectoral flippers (Kleinenberg et al., 1969; Martin, 1996). Belugas appear to use their white coloration as camouflage by hiding amongst sea ice to avoid predation by killer whales. The change in color is not related to sexual maturity, although these events may occur at the same time (Kleinenberg et al., 1969; St. Aubin et al., 1990).
A beluga’s shape is predominantly the result of its thick blubber layer, which causes a rounded midsection that tapers to a relatively small head and tail. Beluga pectoral flippers are also small in proportion to the whales’ body size (O'Corry-Crowe, 2002; Reeves et al., 2002). The blubber often results in lumpy sides and undersides, especially in large males (Reeves et al., 2002).
Belugas possess a dorsal ridge rather than an actual fin (O'Corry-Crowe, 2002). A dorsal fin would be prone to injury from ice, and would be a site for heat loss (Katona et al., 1993).
The head of a beluga is dominated by the melon, a fat filled area that obscures the upper jaw and assists in echolocation (Reeves et al., 2002).
The neck of a beluga is very flexible, unlike most other cetaceans whose neck vertebrae are fused. This rare characteristic assists belugas in maneuvering as they hunt in very shallow water and to escape from predators (O'Corry-Crowe, 2002).
Average Age to Reach Adult Mass
Female belugas attain their adult size at around 7 years of age.
Males continue to grow, achieving their larger mass at about 14 years of age (Kastelein et al., 1994).
Average Adult Length
An estimated average length for an adult male beluga is 12–15 feet (3.7–4.6 m) long.
Females average 11–13 feet (3.4–4.0 m) in length (Balsiger, 2003; Katona et al., 1993; Martin, 1996; O'Corry-Crowe, 2002; Reeves et al., 2002; Richard, 2002).
Average Adult Weight
An estimated average weight for an adult male beluga is 1600–2500 pounds (725–1134 kg).
Females average 1100-2000 pounds (499–907 kg) (Balsiger, 2003; Katona et al., 1993; Martin, 1996; O'Corry-Crowe, 2002; Reeves et al., 2002; Richard, 2002). Size can vary greatly between different populations of belugas; climate is probably a factor in determining the body size of belugas in different populations (Martin, 1996; Sergeant and Brodie, 1969).
A beluga's thick skin forms a barrier of protection against abrasion by ice in the arctic environment. The temperature of the beluga's skin is only a degree or two warmer than the surrounding water. Belugas have particularly thick skin; it is 10 times thicker than dolphin skin and 100 times thicker than the skin of many terrestrial mammals. Below the skin, blubber insulates the internal organs and tissues (Doige, 1990; Castellini, 2002).
Belugas are the only cetacean to undergo an annual molt. Typically, growth and replacement of the epidermis (outer layer of skin) of cetaceans is a continuous process. In belugas, it is a cyclical process that may be driven by their seasonal migrations between frigid arctic oceans and relatively warm estuarine waters.
The molting process may be controlled by environmental cues such as temperature and salinity (St. Aubin et al., 1990). By molting, belugas remove the thick surface layer of the skin that may increase the resistance to the smooth flow of water over the whale. After the molt, the flow of water over the beluga’s skin would be smoother, which would make them more hydrodynamic (Smith et al., 1990).
A thick insulating layer of blubber is one of the beluga's greatest adaptations to life in the Arctic. It allows them to stay warm even when the water is at freezing temperatures.
Compared to other odontocetes, belugas have an unusually thick layer of blubber, accounting for 40–50% of their body weight. Among all other cetaceans, only the Northern right whale has a similar body composition. Belugas have been reported to have blubber thickness of up to 10.6 inches (27 cm), but 4 inches (10 cm) is more typical (Balsiger, 2003; Kleinenberg et al., 1969; Richard, 2002). A beluga’s blubber layer varies in thickness seasonally.
Belugas can use their lips to form the shape of an “O” with their mouth, a characteristic not shared by any other whale.
A beluga’s tongue forms a seal around fish, allowing it to swallow prey without having any water go down the throat. This helps to reduce salt intake and prevent dehydration. The tongue also allows the beluga to capture prey by using suction. Similar to other cetaceans, a beluga's tongue is used as a straw for nursing when they are young. It curls, and goes up against the roof of their mouth. It has a water-tight seal due to scalloped edges around the edge of their tongue. The edges fade over time.
Belugas can create a very powerful spit by forcing water out of their mouth. This is used to blow away sand, silt, and mud when hunting for benthic prey (Kleinenberg et al., 1969; Martin, 1996).
Belugas use their teeth to grasp their prey, rather than for chewing. Their teeth are conical in shape and the upper and lower teeth are interposed. This allows the whales to grasp prey efficiently (Kleinenberg et al., 1969).
A young beluga's teeth appear when the animal is between 1 to 2 years of age and all teeth have at least partially appeared by the end of a beluga's third year (Brodie, 1971; Kleinenberg et al., 1969).
Belugas have only one set of teeth throughout their lives. The number of teeth varies with sex and age and can range from 30 to 40.
The size of the teeth depends on the size of the animal; maximum sizes of 5 cm (2 in) long and 1.8 cm (0.7 in) thick have been recorded. In addition, beluga teeth vary in pattern of wear as a result of their feeding from the sea floor. In some older animals, the teeth may be worn down to the gums (Kleinenberg et al., 1969).
Belugas have very acute hearing, especially at higher frequencies. They can detect sounds within the range of 1.2 to 123 kHz with their range of best hearing between 32 and 108 kHz (Klishin et al., 2000). For comparison, the range of hearing of a young, healthy human is 15–20,000 Hz (0.015 – 20 kHz) (Grolier, 1967; White, et al., 1978; Cutnell and Johnson, 1998).
Studies have shown that belugas can hear as well in water as deep as 984 feet (300 m), as they can at the surface (Ridgway et al., 1997). Belugas greatly exceed the capabilities of other odontocetes in frequency tuning and are able to detect echolocation signals in high levels of background noise and reverberation (Klishin et al., 2000).
Belugas were nick named “sea canaries” by early whalers due to their extensive repertoire of sounds. Their sounds have been likened to bird calls, oxen mooing, the sound of rubbing a wet finger on glass, deep sighing, a woman’s shrill cry, the grunting of pigs and even badly played musical glasses (Fish and Mowbray, 1962).
Belugas were the first cetacean to have their vocalizations recorded and systematically described (Schevill and Lawrence, 1949). Researchers now understand that the sound repertoire of belugas is composed of the predominant sound types among toothed whales: (1) whistles, or narrow-band, frequency modulated vocalizations, believed to be social signals and (2) pulsed sounds or trains of broad band pulses. Some researchers (e.g. Faucher 1988, Karlsen et al. 2002; Belikov and Belkovitch, 2003; Vergara and Barrett-Lennard 2008, 2010) identified mixed calls in belugas, consisting of either a whistle and a pulsed component or two pulsed sounds, produced synchronously in the same vocalization.
Studies on beluga vocalizations revealed that
- Vocalizations were more numerous during periods of social interaction than other behavioral states (Sjare and Smith, 1986).
- Some of the whistles that belugas produce are used for short-range communication and others are used for long-range communication between uncoordinated groups (Belikov and Bel’kovich, 2006).
- Broad-band pulsed vocalizations can be used as contact calls, both in the aquarium and in the wild and play an important role in establishing or maintaining contact between mothers and calves (Vergara et al., 2010). The identification of beluga call types allows researchers to be better positioned to evaluate the effects of human-related noise on the animals’ communication signals.
- Belugas are adept vocal mimics and are able to imitate organic and artificial sounds. Belugas in human care settings often imitate sounds in their environments, including human speech (Eaton, 1979; Ridgway et al., 1985). The ability of individuals to imitate sounds that are not part of their repertoire suggests that they may use vocal learning in developing their natural vocalizations (Tyack 1993).
Echolocation is a biological sonar that provides more information than any human-made sonar (Lammers and Castellote, 2009). During echolocation, a beluga produces sound in the form of clicks. These clicks reflect off of objects in the environment and return to the animal in the form of echoes. The echoes are received by the fat-filled canal in the lower jaw. The animal can then process these echoes, allowing it to perceive information about the object, such as size, shape, speed, density, direction and the material of which it is composed (Harley et al., 1995).
Belugas have a sophisticated sonar system. They have better abilities than bottlenose dolphins to discriminate targets in clutter (Turl et al. 1991) and in the presence of masking noise (Turl et al. 1987), and have the ability to change the frequency of their clicks in response to background noise (Au et al., 1995; Tyack, 1999).
The melon is the fatty region on top of a beluga's skull. It is critical to focusing and projecting echolocation signals and is the means by which the sounds a beluga makes are ultimately projected to the water. The melon can function as an “acoustic lens,” focusing sound into a beam the way a flashlight's lens and reflector focus light (Cranford et al., 1996; Pabst et al. 1999).
Belugas have the ability to change the physical shape of their melon, which may allow them to control sound transmission (Frankel, 2002). The fat composing the melon is distinct; it cannot be broken down to produce energy, indicating its importance.
Belugas have good vision both above and below the water, although their visual acuity range is slightly less than in measurements of other odontocetes. Recent findings suggest beluga whales possess visual acuity between 14.1’ to 16.9’(Balsiger, 2003; Mass and Supin, 2002). Like other odontocetes, they can focus in either air or water, an adaptation made possible by their specially adapted lens and cornea (Mass and Supin, 2002).
For belugas, which are sometimes hunted by the polar bear, the ability to see in both air and water is especially important.
Belugas' eyes do contain both rod and cone cells. However, like all other cetaceans, they have only one type of cone. They lack the short wavelength sensitive cone. Since two or more types of cones are usually necessary to distinguish colors, belugas probably have monochromatic vision and do not see much color if any at all. This is most likely a result of adaptation to dim lighting conditions underwater (Griebel and Peichl, 2003; Levinson and Dizon, 2003).
Smell, Chemoreception and Taste
Belugas lack a sense of smell, which would be of limited use in water. However, chemoreceptors on the base of a beluga's tongue function in a similar way to taste buds, and allow the animal to detect chemicals suspended in water (Kleinenberg et al., 1969). Chemoreceptors may also perform a social function, enabling one beluga to locate others nearby. In addition, belugas may be able to detect changes in the salinity of water (Dudzinski et al., 2002; Muir et al., 1990).
Belugas have well-developed skin sensitivity. The most sensitive areas are inside the mouth, the tip of the rostrum, the insertion of the pectoral flipper, and the abdomen (Dudzinski et al., 2002). The sense of touch plays an important role in tactile oriented social behavior.
Swimming, Diving and Thermoregulation
Generally, belugas are slow swimmers, mostly swimming between 2–6 mph /h (3–9 km). They have been recorded swimming at speeds of 9.3–17.1 mph (15–27.5 km/h) (Richard et al., 1998; Richard et al., 2001; Shaffer et al., 1997).
When compared with other toothed whales, belugas are not capable of sustained high-speed swimming at the surface (Shaffer et al., 1997). Belugas tend to swim faster while migrating than during molting or feeding (Suydam et al., 2001).
Belugas (and all other cetaceans) have several adaptations to conserve oxygen, as well as several adaptations to minimize or eliminate the effects of harmful nitrogen related conditions, such as the bends and nitrogen narcosis, which can be experienced by human scuba divers.
Belugas store half the total oxygen in the blood, as opposed to humans, who hold half the total oxygen in the lungs (Berta and Sumich, 2003). Moreover, belugas, like other cetaceans, use approximately 75% of their total lung capacity, while humans use only 10-15%. This allows belugas to load more oxygen and unload more carbon dioxide in each breath (Wartzok, 2002).
Belugas also have more blood per unit weight than terrestrial animals, with blood accounting for 13% of their body weight (127.5 ml/kg), compared to 8% for a human (Elsner, 1999; Shaffer et al., 1997). They also have a higher hemoglobin level than terrestrial mammals, allowing them to carry more oxygen per unit of blood (Ridgway, 1972; Ridgway et al., 1997).
Belugas are also able to store oxygen in myoglobin in their muscles. During a dive, belugas exhibit bradycardia, or a slowing of the heart rate, from about 100 beats per minute down to 12–20 (Ridgway, 1972). This reduces the heart’s oxygen requirements and slows the circulation of blood throughout the body.
Average Breath Hold/Dive Time Reported
Typical feeding dives rarely last longer than 18–20 min; most range between 9 and 18 minutes (Heide-Jørgensen et al., 1998; Reidenberg and Laitman, 2002; Schreer and Kovacs, 1997). Trained belugas have been taught to dive for up to 17 minutes without extended surface times (Shaffer et al., 1997).
Maximum Breath Hold/Dive Time Reported
The maximum dive duration recorded was 25 minutes (Schreer and Kovacs, 1997).
Dive time is influenced by descent rates and dive depth. The descent rate remains constant throughout the descent. This suggests that belugas use echolocation to determine how deep they must dive to reach the bottom before initiating the dive (Martin and Smith, 1999).
Maximum Dive Depth Recorded
The deepest recorded dive was to 3300 feet (1000 m) (Martin and Smith, 1999).
Belugas normally migrate, hunt and interact in groups and are rarely found alone (Balsiger, 2003; Leatherwood et al., 1988). Belugas typically form groups numbering from 2 to several dozen animals (Gurevich, 1980; Katona et al., 1993; Krasnova et al., 2006). The structure of a group is fluid, with individuals moving between different groupings.
Beluga pods can contain animals of the same sex and age class, but may vary in structure and size seasonally (Gurevich, 1980). Males most often travel in groups of 10-15 individuals that tend to stay away from others (Krasnova et al., 2006; Smith et al., 1994). Adult females are found with their calves and other juveniles or they may form groups of their own (Martin, 1996; Richard, 2002). Older subadult belugas often form their own groups (Richard, 2002). Segregation by age and sex may be more distinct at certain times of the year, during migrations or when feeding (Loseto et al., 2006; Martin, 1996; O'Corry-Crowe, 2002).
In general, belugas will hunt in a manner that requires the lowest energy expenditure to gain the greatest nutritional rewards. They are more successful hunters when feeding on large schools of fish (Balsiger, 2003). Belugas may also hunt cooperatively to conserve energy and use man-made structures to increase the success of a hunt. A recorded example includes one whale which waited along a dock while a second whale chased fish along the dock toward the waiting whale (Balsiger, 2003).
Diving is important to foraging behavior. Belugas will dive deeply to the seabed in search of benthic prey (Martin and Smith, 1999; Richard et al., 1998). Belugas are very successful bottom feeders. Their flexible necks allow them to scan a broader area of the sea bottom, while spit and suction behaviors aid in capture of prey (Martin and Smith, 1999; O'Corry-Crowe, 2002; Ridgway and Carder, 1998).
Studies of brain activity of several odontocete species, including belugas, show that these animals engage in unihemispheric slow wave sleep (USWS) during which one half of the brain goes into a sleep state, while the other maintains visual and auditory awareness of the environment and allows the animal to resurface for respiration. This ability may help to avoid predators as well as maintain visual contact with cohorts/offspring). (Lyamin, et al., 2008; Lyamin, et al., 2004; Lyamin et al., 2002; Ridgway, 2002; Ridgway, S.H. 1990;Wagemann et al., 1990).The sleeping hemisphere switches with the non-sleeping hemisphere many times during the sleeping period. Cetaceans have the ability to swim while sleeping, but a common resting behavior seen is logging, in which the whale lays still at the surface of the water (Goley, 1999).
Reproduction and Maternal Care
The reproductive cycle of the beluga is seasonal, although there is some slight variability between regions (Reidenberg and Laitman, 2002). Most breeding occurs from April to May, although in some areas breeding may start as early as February and end as late as early June (Brodie, 1971; Katona et al., 1993; Kleinenberg et al., 1969; Martin, 1996; O'Corry-Crowe, 2002; Reidenberg and Laitman, 2002).
Studies with belugas in zoological parks and aquariums have also shown seasonal variation in the production of reproductive hormones. These studies make it possible to determine conception dates. Most conceptions in zoos and aquariums occur between March and May (Robeck et al., 2005). It is thought that ovulating females probably mate with several different males during the breeding season (Martin, 1996).
Studies with beluga whales in zoos and aquariums, which allow researchers to follow the development of the fetus from conception until birth, have shown that the gestation period ranges from about 15-16 months (Robeck et al., 2005).
Most calving takes place from late spring to early summer, mostly in the months of April-July (Balsiger, 2003; COSEWIC, 2004; Kleinenberg et al., 1969; O'Corry-Crowe, 2002; Richard, 2002; Sergeant, 1973; Smith et al., 1994). Calving season and peak calving may vary between stocks (Cosens and Dueck, 1990).
Belugas give birth to one calf at a time. There has never been a record of multiple live births in belugas (Kleinenberg et al., 1969). The intense maternal investment in the calf would make it very difficult, if not impossible, for a female beluga to simultaneously nurse two calves.
An average beluga birth lasts eight hours (Robeck et al., 2005). When born, calves weigh between 136.7 and 196.2 lbs (62–89kg) (Robeck et al., 2005). At birth male calves average 5 feet 1 inch (154 cm) long and females average 5 feet 3 inches (161 cm) long (Robeck et al., 2005).
Newborn beluga calves are immediately capable of swimming and shallow diving, although female belugas have been observed carrying their calves on their backs when they are very young. Belugas are not born with a thick layer of blubber (Martin, 1996). A thick outer layer of skin cells insulates calves on birth. This is shed soon after birth as the calf builds up its blubber layer. This shedding also causes a change in skin color (Doidge, 1990).
Average Years between Offspring
Females give birth every 2–4 years, most often once every 3 years (Brodie, 1971; Katona et al., 1993; Martin, 1996; O'Corry-Crowe, 2002; Richard, 2002).
Average Age at Sexual Maturity
Females generally reach sexual maturity between 5–7 years of age.
Males mature later, at the age of 8–9 years (Balsiger, 2003; Burns and Seaman, 1988; Katona et al., 1993; Martin, 1996; O'Corry-Crowe, 2002; Richard, 2002).
Sexually mature males may not become socially mature until several years later, when they reach a size that allows for competition with fully grown males (O'Corry-Crowe, 2002).
Female belugas in the wild may begin producing calves from the age of 5 or 6, while the youngest female to calf in a zoological park or aquarium was 6.9 years of age at time of conception (McAlpine et al., 1999; Robeck et al., 2005). Males in human care first reproduce at around the age of 9 years, which is consistent with information gathered on wild belugas (Robeck et al., 2005).
Belugas Breeding in Zoological Parks and Aquariums
Belugas in zoological parks and aquariums provide the unique opportunity to study reproduction, growth and development of animals of known age. Breeding and calving have occurred in these facilities since 1981 (O'Brien et al., 2008). As of 2011, there were 37 belugas in 7 North American aquariums that manage this group of animals as one breeding population—over half of which were born in a zoological park or aquarium.
Longevity and Mortality
Tooth Aging of Cetaceans
The ages of whales and dolphins have been commonly determined by counting Growth Layer Groups (GLGs)—the layers of dentine (core of the tooth) and cementum (outer covering of the tooth) that are created as the animals age (Brodie et al., 1990). This method is similar to counting the rings on a tree trunk.
Scientists have long believed that cetaceans deposit one GLG each year except for beluga whales (Sergeant, 1959, Brodie et al., 1990; Martin, 1996) which deposit 2 GLGs per year. However, recent research conducted on wild beluga whales suggests that every GLG deposited is equivalent to one year of life (Stewart 2006). Attempts to validate this have been inconclusive to date; however, one GLG per year deposition rate is the more probable interpretation in most cases (Lockyer et al., 2007). Research published prior to 2006 on biological characteristics of beluga such as the age of maturation were based on the two GLG per year deposition rate and therefore should likely be considered inaccurate.
Estimated life expectancies of beluga whales in the wild vary from one population and one study to another. Using data from published studies and adjusting results to conform to the one GLG per year deposition rate, it was determined that the adult life expectancy of beluga whales in human care is not different than that of beluga populations in wild (Willis 2011). The oldest belugas in zoological parks and aquariums are currently living and are over 40 years of age, and thus the longevity for this species is undetermined.
Current data indicate that, after they reach one year of age, beluga whales in the wild are expected to live, on average, for 25–30 years (Balsiger, 2003; Burns and Seaman, 1988; Harwood and Smith, 2002; Katona et al., 1993; Martin, 1996; O’Corry-Crowe, 2002; Reeves et al., 2002).
The beluga whale’s natural predators include polar bears and killer whales (Lowry et al., 1987; Shelden et al., 2002). Researchers have determined that neither killer whales nor polar bears are currently a significant threat to beluga populations in comparison to human impacts.
Other Natural Threats to Belugas
It is not uncommon for groups of belugas to become trapped in areas that ice over, often restricting them to small holes in the ice for breathing. If the ice does not break up in time for them to escape, the whales face suffocation or starvation. In an unusual incident in 1984-85, 2,500–3,000 belugas were trapped in Russia’s Senjavin Strait. Solid ice stretching for 12 miles blocked the path to open water. An estimated 1,000 belugas died during the event from hunting, hunger, lack of air or injuries. The efforts of the Russian icebreaker prevented the deaths of more of the animals (Ivashin and Shevlyagin, 1987).
The worldwide population of beluga whales, found in arctic and subarctic waters along the northern coasts of Alaska, Canada, Greenland, Norway and Russia, have been listed by the International Union for the Conservation of Nature (IUCN) as “Near Threatened.” IUCN’s higher rankings are “Critically Endangered, Endangered, and Vulnerable.” IUCN is the world’s oldest and largest global environmental organization and is a leading authority on the environment and sustainability.
Although belugas worldwide are not endangered, there are three isolated populations of beluga whales that are endangered and another considered threatened because of human activities such as noise, pollution, shipping vessel traffic, and industrial activity that cause disease, reduce habitat quality and contaminate the food supply.
The only beluga stock listed as endangered in the United States is the Cook Inlet population in Alaska. www.nmfs.noaa.gov/pr/species/mammals/cetaceans/belugawhale.htm
Canada’s Committee on the Status of Endangered Wildlife in Canada (COSEWIC) has analyzed the status of many of the Canadian beluga populations. Its listings, with the dates of evaluations, are as follows:
- St. Lawrence population, endangered (1983 and 1997 evaluations)
- Southeast Baffin Island-Cumberland Sound population, endangered (1990)
- Ungava Bay population, endangered (1988)
- Eastern Hudson Bay population, threatened (1988)
- Eastern High Arctic/Baffin Bay population, special concern (1992)
- Western Hudson's Bay population, not at risk (1993)
- Beaufort Sea-Arctic Ocean population, not at risk (1985)
COSEWIC reports that “several of these populations were reduced by commercial exploitation in the past, some more so than others. At present, subsistence hunting in some parts of the Arctic is a concern because of its potential for continued decline or lack of recovery of the depleted populations. Other potential effects on these populations include habitat loss from shore development, build-up of toxic contaminants and disturbance by commercial shipping, ice breaking and whale watching activities” (www.dfo-mpo.gc.ca/science/publications/uww-msm/articles/beluga-eng.htm).
Despite relative isolation from humans, a number of current human activities are negatively affecting beluga whales. These include habitat alteration in estuarine environments as a result of hydroelectric development in rivers (Katona et al., 1993; Leatherwood and Reeves, 1983). Other long term threats are competition with fisheries, off-shore oil exploration, vessel traffic, and pollution. (Balsiger, 2003; Caron and Smith, 1990; Finley et al., 1990; Leatherwood et al., 1988; Seaman at al., 1982; Thomas et al., 1990).
The majority of the research currently being conducted with beluga whales involves conservation and management of the species, through stock identification and distribution and genetic research (Brown Gladden et al., 1997; Reeves et al., 2002). There are over 150,000 belugas worldwide—a number much lower than historical population sizes. Large scale commercial hunting in the past has contributed to the decline. The whales’ use of estuaries and return to the same rivers makes them particularly vulnerable to overharvesting. Belugas have a low rate of reproduction, which limits population recovery (Caron and Smith, 1990; COSEWIC, 2004; Kingsley, 1998).
There are now moratoriums on hunting whales in the United States and Canada. Both countries make exceptions for limited subsistence hunting of belugas by people of native descent because of the importance of the whales to their survival and culture (MacLean et al., 2002). In both countries, the government and native groups cooperate to manage beluga populations.
Toxic chemicals pose one of the most serious long-term threats to some beluga populations. Adult belugas washing ashore in Canada’s St. Lawrence River contain such high levels of PCBs and DDTs that they are considered hazardous waste under Canadian law (Beland et al., 1993). Because belugas are at the top of the food chain in their environment, they consume more highly contaminated prey (Loseto et al., 2008; Wilson et al., 2005). These toxins are passed by mothers to their calves through the milk (Stern et al., 1994). Researchers examining St. Lawrence beluga carcasses report an annual cancer rate for the animals higher than any other population of cetacean and similar to that of humans. (Martineau et al., 2002)
Because beluga whales have very acute hearing, especially at higher frequencies, noise can be threat to the animals.
Human-caused (anthropogenic) underwater noise from a number of sources has increased significantly over the past decades (e.g. hydrocarbon and seismic exploration, ocean dredging, military activities, commercial shipping, fishing vessels, passenger ferry traffic and recreational boats) (Richardson et al. 1995; Erbe and Farmer 2000; Tyack 2008).
Anthropogenic noise can disrupt echolocation and mask environmental sounds that the animals use for navigation and to identify predators and prey. It can trigger avoidance reactions and stress responses (Erbe and Farmer 2000; Tyack 2008). These sounds can interfere with the animals’ acoustic communication (Erbe and Farmer 1998), which is critical to vocalizations used to maintain contact between mothers and calves (McKillop et al. 2010, Vergara, 2011).
Beluga whales are facing increasing threats from climate change in their Arctic environments as sea temperatures change, water salinity levels drop because of melting ice, icy polar habitats are lost, and krill populations, a main source of food for the whales, decline.
Further reduction of sea ice cover could increase human activities in previously inaccessible Arctic areas, attracting shipping, oil and gas exploration and production, and commercial fishing. These activities would increase the risks of pollution, environmental and noise disturbance (Hovelsrud et al., 2008). In addition, decreased sea ice would affect the Arctic food web, forcing a change in marine mammals' feeding habits (Bluhm and Gradinger, 2008).
Sea ice and extremely cold water serve as barriers to other species of marine mammals not now found in the Arctic. Warmer waters may increase competition for prey, the potential risk of disease (Burek et al., 2008; Moore et al., 1995) and leave beluga populations more vulnerable to predation by killer whales (Shelden et al., 2002). Inuit people in the eastern and northwestern Hudson Bay and the Hudson Strait have already seen effects of climate change on beluga behavior. With less sea ice, belugas are reportedly declining in numbers along the coast and are instead migrating in water currents farther offshore (Ragen et al., 2008).
A U.S. national survey indicates that people who visit zoos and aquariums are more concerned about climate change than other Americans and are willing to take action to help because they feel a connection with animals. The final report, “Global Climate Change as Seen by Zoo and Aquarium Visitors,” was analyzed by the Climate Literacy Zoo Education Network. CLiZEN is led by the Chicago Zoological Society, which manages the Brookfield Zoo. CZS officials say the survey’s findings suggest that zoo and aquarium visitors are a prime audience for climate change education messages. The survey is part of a $1.2 million planning grant that CZS received from the National Science Foundation Program on Climate Change Education and another grant provided by the Boeing Company. www.czs.org/CZS/clizen
AMMPA Facilities' Contributions to Conservation
The study of belugas in zoological parks and aquariums has increased our understanding of factors threatening the sustainability of the species in the wild, so that steps can be taken to conserve and protect these animals. Much of this research would be impossible to conduct in the wild. The ability to collect regular blood samples and other measurements from these animals has provided substantial and important information on the species (Robeck et al., 2005). This research increases understanding of belugas’ biology, physiology and disease pathogenesis, and creates baseline indicators to better understand issues threatening belugas in our oceans and rivers. Hearing and bioacoustics research helps scientists understand responses, thresholds and the effects of underwater sound levels on these animals. Other research helps explain how beluga whales cope with the increasing pathogens and changing water temperatures in oceans and rivers. Additional studies address nutritional needs and metabolic rates of belugas that face increasing challenges for food sources.
The 2008 health assessments of beluga whales in Bristol Bay, Alaska, benefitted from safe handling methods developed at zoological parks and aquariums.
Georgia Aquarium staffed and sponsored research in Canada’s Bristol Bay in 2011. The research focused on what belugas in the bay eat and their exposure to pollution—diet and pollution have long-term effects on beluga populations. This research helped provide comparisons to the challenges facing the endangered beluga population in Alaska’s Cook Inlet.
Research on belugas in Russia’s Sea of Okhotsk supported by Georgia Aquarium and several other parks and aquariums established the first quantitative information on the daily movements of the belugas in that location.
The belugas cared for at the Mystic Aquarium have cooperated in a number of studies, and new studies are initiated each year. Studies conducted since 2005 include artificial insemination, effects of the exposure of blood to organochlorine contaminants, testing of EKG and ultrasound tags for use on wild cetaceans, beluga cognition, metabolic rate determination, immune system function, body condition and others.
The SeaWorld & Busch Gardens Reproductive Research Center is a collaborative resource that pioneers technology and research to help with the management and conservation of wildlife and ensure genetic diversity in marine mammal populations in parks and aquariums throughout the world. Much of SeaWorld’s recent research with beluga whales is aimed at gaining an understanding of the animals’ reproductive endocrinology, anatomy, behavior and physiology. Tools developed through this reproductive monitoring and assisted breeding research can be integrated into in situ population management and conservation strategies (Steinman, K.J., O’Brien, J. K., Monfort, S. L. and Robeck, T. R., 2012; Osborn, S., Dalton, L., Dold, C. and Robeck, T., 2011; O’Brien, J. K. and Robeck, T. R., 2010; Robeck, T. R., Steinman, K. J., Montano, G. A., Katsumata, E., Osborn, S., Dalton, L., Dunn, J. L., Schmitt, T., Reidarson, T. and O’Brien, J. K., 2010; O’Brien J. K. and Robeck, T. R., 2010; Hill, Heather, 2009; O’Brien, J.K., K.J. Steinman, T. Schmitt, and T.R. Robeck, 2008).
Shedd Aquarium has cooperated with researchers on numbers of studies that were essential to further research with beluga whales in the wild. For one study, the aquarium trained its animals to wear data loggers so scientists could gather information about the meaning of various beluga vocalizations. In cooperation with the Canadian government and other facilities, it trained animals to wear specially designed flipper tags to ensure the tags’ viability and comfort before they were used on belugas in the wild to collect essential data about the animals’ activities and wellbeing. EKG monitoring and interpretation techniques were tested with Shedd’s whales and led to improvements on EKG utilization with stranded and entangled cetaceans. The research also resulted in improved techniques for use of EKGs in monitoring the health of cetaceans in human care.
Shedd has supported researchers studying the immune system of beluga whales in an area of the St. Lawrence River that is heavily polluted and conducting research that provided insights into how animals of various ages adapt to long-term changes in Arctic sea ice conditions. The aquarium has also participated in research into the implications of hormonal changes of animals in the wild, beluga genetics, underwater hearing, the effects of body size on breath-hold capacity, acoustic development in beluga calves, nursing behaviors, and the capability and purpose for the beluga whales’ diverse vocal repertoire. In cooperation with Mystic Aquarium research, Shedd helped investigations into the physiological responses of belugas to environmental and anthropogenic challenges the animals face in the wild and the study of a thyroid hormone and how it is influenced by age, sex, and seasonality. Much of the data generated through these studies was previously unavailable or unknown and have ramifications to the health and wellbeing of animals in the wild.
Shedd coauthored an article about the rescue of a newborn beluga whale in the St. Lawrence Estuary, which chronicled the animal’s care and information collected from the newborn that is important to understanding immunity transfer from mother to calf in the wild. It appeared in the Canadian Journal of Zoo and Wildlife Medicine.
Similarly, the belugas at the Vancouver Aquarium have been involved in studies of social behaviour (Recchia, 1994); masking of beluga whale vocalizations by icebreaker noise (Erbe, 1997, 1998), vocal development of beluga calves (Vergara and Barrett-Lennard, 2008), allonursing or the provision of milk to non-offspring by females (Leung et al., 2010), and contact calls in wild belugas and in human care (Vergara et al., 2010).
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