Beluga whale

• 1. Introduction

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  In 1849, railroad crews laying the first line between Rutland and Burlington in Vermont dug up the bones of a beluga whale in the town of Charlotte. The workers did not know that, of course. They only knew that nearly ten feet below the surface, in thick blue clay, lay the remains of an animal unlike anything previously found in the state. Experts later identified the bones as belonging to Delphinapterus leucas, a pale whale of the Arctic and sub-Arctic seas.

  The real puzzle was the location. Charlotte lies more than 150 miles from the nearest ocean, among ordinary farm fields. Early naturalists could not explain how a marine mammal ended up buried there.

  That riddle raises a wider set of questions about the beluga. How did an Arctic whale come to rest beneath rural Vermont? How does a pale, round-bodied animal manage to thrive beneath sheets of sea ice? And what has happened to a species that people have hunted for centuries, captured for display, and now travel to watch?

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• 2. Ancient Ancestors

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  Mitochondrial DNA studies suggest that all modern cetaceans last shared an ancestor between 25 and 34 million years ago. Later, between 11 and 15 million years ago, the group containing dolphins, porpoises and the beluga's own family split away from other toothed whales. The beluga's family, the Monodontidae, parted from the dolphins first and from the porpoises afterwards, which makes both groups its closest relatives.

  In 2017, researchers sequenced a beluga genome. The assembled sequence ran to 2.327 billion base pairs and encoded a predicted 29,581 genes. The authors estimated that the beluga and the killer whale match each other by 97.87 percent across their genomes.

  The fossil record names a few early relatives. Denebola brachycephala lived in the late Miocene, roughly nine to ten million years ago. Bohaskaia monodontoides followed in the early Pliocene, three to five million years ago. Fossils from Baja California and Virginia show that this family once lived in warmer water than its descendants do today.

  The strongest evidence is a monodontid called Casatia thermophila, about five million years old. Its fossil lay beside the remains of tropical species such as bull sharks and tiger sharks.

  In more recent times, the beluga's range seems to have followed the polar ice. It widened when ice packs spread during ice ages and narrowed when they retreated. The Vermont bones seemed to cut against that pattern, since Charlotte is hundreds of kilometres from any coast.

  The answer was the Champlain Sea. The Charlotte bones were preserved in its sediments. That sea was an arm of the Atlantic reaching far into the continent, created by rising water at the end of the ice ages some 12,000 years ago. Today the Charlotte whale is the official Vermont State Fossil. Vermont is the only state whose official fossil belongs to an animal that is still alive.

  The species itself was first formally described in 1776 by Peter Simon Pallas. It belongs to the toothed whales, and its only living partner in the Monodontidae is the narwhal. The Irrawaddy dolphin was once placed in the family too, but recent genetic evidence assigns it to the dolphin family, Delphinidae.

  A single skull with traits intermediate between beluga and narwhal supports the idea that the two species can hybridise. Documented hybrids had a beluga father and a narwhal mother. One, and perhaps as many as three, were killed and harvested during a subsistence hunt. The surviving skull has unusual teeth, which suggest the hybrid fed on the seabed much as walruses do. Whether such hybrids could breed is still unknown.

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• 3. Built for the Ice

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  The Russian word belyj, meaning white, is the root of the name beluga. The scientific name says the same thing in Greek. Leucas means white, and Delphinapterus means dolphin without a fin. The beluga is the only cetacean that regularly appears in this colour, which is why it is also called the white whale.

  Calves are not born white. They arrive grey, and by the time they are a month old they have turned dark grey or blue-grey. Pigment then fades gradually, and the full white colouring arrives at seven years old in females and nine in males. The pale skin is an adaptation that lets belugas blend into the polar ice, which helps against their main predators, polar bears and killer whales.

  The skin has another unusual feature. In winter the outer layer thickens and can turn yellowish, mainly on the back and fins. When belugas reach summer estuaries, they rub themselves on riverbed gravel to strip it off. The annual molt removes damaged tissue and harmful bacteria that might otherwise let pathogens in.

  Adult males measure between 3.5 and 5.5 metres and usually weigh 1100 to 1600 kilograms, occasionally reaching 1900. Females measure 3 to 4.1 metres and weigh 700 to 1200 kilograms. Both sexes reach full size by about ten years old. Males run about 25 percent longer than females and are sturdier.

  Between 40 and 50 percent of a beluga's body weight is fat, compared with about 30 percent in cetaceans that do not live in the Arctic. The layer covers everything except the head and can be 15 centimetres thick. It insulates against water between 0 and 18 degrees Celsius, and it serves as a food reserve when meals are scarce.

  Belugas have no dorsal fin, only a hard dorsal ridge. That shape is believed to help them swim under ice, or possibly to hold in heat. The ridge, together with the head, can break through ice up to 8 centimetres thick.

  The pectoral fins are small, rounded and oar-shaped, and they act mainly as rudders. Veins wrapped around the arteries feeding the fin muscles widen or narrow to gain or shed heat. The tailfin contains no bones at all, only dense fibrous tissue. Even the thyroid gland is remarkable, weighing three times as much as a horse's, which supports a higher metabolism in summer estuaries.

  How long all of this lasts was long misjudged. Early work, which counted layers in teeth and assumed one or two were laid down each year, suggested belugas rarely lived beyond 30 years. A 2006 radiocarbon study showed the layers form only once a year, which put lifespans at 70 or 80 years. The oldest living beluga on record was 79.

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• 4. Sound and Senses

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  Seven neck vertebrae that are not fused give the beluga a head that moves independently of its body. Most whales and dolphins have fused neck bones. The beluga can nod and turn its head sideways without rotating its body, which widens its field of view and helps in catching prey and dodging predators. The same flexibility lets it show a wider range of facial expressions than most cetaceans, whose smiles are fixed.

  Above the face sits the melon, an organ of fatty tissue used for echolocation. In the beluga it is large, bulbous, lobed and visible as a rounded forehead. It is also malleable, and the whale changes its shape by blowing air around its sinuses to focus outgoing sound. The melon's fats are mainly isovaleric acid, at 60.1 percent, plus long-chain branched acids at 16.9 percent. That mix is very different from the whale's body fat.

  The whale sends out rapid sequences of clicks, and the melon works as an acoustic lens that projects them forward in a beam. Sound moves through water at nearly 1.6 kilometres per second, about four times faster than in air. Returning echoes reveal an object's distance, speed, size, shape and even internal structure. Belugas use this to navigate beneath thick ice and to find open water or trapped pockets of air for breathing.

  The hearing range runs from 1.2 to 120 kilohertz, with greatest sensitivity between 10 and 75. Humans hear roughly 0.02 to 20 kilohertz. Most sound probably arrives through the lower jaw, where a fatty deposit connects to the middle ear. Researchers do not know whether the small external ear openings behind the eyes work or are leftovers.

  Vision is weaker than a dolphin's, though belugas can see both in and out of water. Glands at the corner of each eye release an oily gel that lubricates the eye and washes out foreign bodies. Retinas with cones and rods suggest they can see in low light. The mouth contains areas that may sense taste, and belugas react at once if they detect blood in the water. Their brains lack olfactory bulbs and nerves, so they probably cannot smell.

  The sea canary nickname comes from the sounds. Belugas lack vocal cords, and the calls probably come from air moving between nasal sacs near the blowhole. They are among the most vocal cetaceans, with a repertoire of up to 11 sounds, including cackles, whistles, trills and squawks. They also grind their teeth, splash and clap their jaws to signal.

  Noise shapes the calls. One individual in San Diego Bay produced maximum frequencies of 40 to 60 kilohertz. After it was moved to Kaneohe Bay in Hawaii, its maximum rose to 100 to 120 kilohertz, a change thought to answer the louder surroundings.

  Some belugas have even mimicked people. A Japanese researcher claimed to have taught a beluga to identify three objects using speech-like sounds. Canadian researchers described a beluga, which died in 2007, that seemed to talk when it was a subadult. A beluga named NOC could copy the rhythm and tone of human language, and wild belugas have been reported imitating voices.

  Whether such sounds amount to language is debated. A 2015 study found that European beluga signals share physical features with vowels. The sounds stayed stable over time but differed by place, and the farther apart two populations lived, the more their sounds diverged.

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• 5. Diving and Feeding

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  At 22 kilometres per hour, a beluga can keep up a sprint for only about 15 minutes. Usually it swims at 3 to 9 kilometres per hour, slower than killer whales or bottlenose dolphins, because its body is less hydrodynamic and its tail moves in a limited way. Belugas are unusual among cetaceans in being able to swim backwards. They do not leap out of the water, and they spend only 5 to 10 percent of their time at the surface.

  Most dives stay around 20 metres, yet the whales are capable of much more. Wild belugas have been recorded below 700 metres, and the deepest recorded dive passed 900 metres. Captive animals have been tracked at depths between 400 and 647 metres. A dive normally lasts 3 to 5 minutes, but can stretch past 20.

  During a dive, the heart rate falls from about 100 beats a minute to between 12 and 20. Blood is diverted away from certain organs toward the brain, heart and lungs. The blood carries 5.5 percent dissolved oxygen, similar to a Weddell seal and more than land mammals. One study found 16.5 litres of oxygen in the blood of a single female. Muscles hold oxygen too, because their myoglobin levels are several times those of land mammals.

  In the Beaufort Sea, belugas eat mainly Arctic cod. Stomachs of belugas caught near Greenland held rose fish, Greenland halibut and northern shrimp. In Alaska, Coho salmon is the staple, and in Bristol Bay the main fish are the five species of salmon, with sockeye most common. The belugas are opportunistic feeders, so diet follows location and season, and they feed mostly in winter. Their blubber is thickest in late winter and early spring and thinnest in the fall.

  Their teeth number 36 to 40 and are blunt, so the whales grip prey rather than chew. Because they cannot bite pieces off, they use suction and swallow food nearly whole, so prey that is too big risks lodging in the throat. On the seabed, some animals suck up water and blow it out to expose creatures hidden in silt. Their flexible necks help while they search the ocean floor at depths of 20 to 40 metres.

  Teamwork improves the catch. In the estuary of the Amur River, groups of six or eight belugas surround a shoal of salmon, block its escape, and then take turns feeding. Belugas also accompany bowhead whales while the larger whales feed on krill or plankton, and the two species can help each other watch for predators. The belugas also gain something else. Bowheads can break through ice from below by headbutting it, which opens breathing holes.

  Captive belugas eat 2.5 to 3 percent of their body weight a day, between 18.2 and 27.2 kilograms. Like wild animals, they eat less in the fall.

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• 6. Pods and Calves

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  Radio tracking has shown that a beluga can start in one pod and be hundreds of miles from it within a few days. Pods hold between two and 25 animals, averaging ten, and they are unstable, with members moving from group to group. Researchers sort them into nurseries of mothers and calves, bachelor groups of males, and mixed groups. Most pods were not built around close maternal relatives. They mixed kin and non-kin, and unrelated adult males often travelled together.

  Play is constant. Belugas chase each other, rub against each other, and surface and dive in synchrony in a behaviour called milling. In captivity, one whale was seen blowing bubbles while another popped them. Others copy one another like a game of Simon says, and some show affection with mouth-to-mouth contact. Wild belugas often swim beside boats and play with wood, plants, dead fish and bubbles they have made.

  During the breeding season, adults have been seen carrying objects on their heads and backs, including plants, nets and even the skeleton of a dead reindeer. Captive females have carried floats and buoys after losing a calf, and experts regard the behaviour as a substitute.

  Most mating takes place from February to May. Gestation lasts an estimated 12 to 14.5 months, though captive females suggest it can reach 475 days. Females usually bear one calf every three years, and the average age at first birth is 8.5 years. No births have been recorded in females older than 41. Calves are born over a long season. In the Canadian Arctic they arrive between March and September, and in Hudson Bay the peak is late June.

  A newborn is about 1.5 metres long, weighs about 80 kilograms and is grey. It can swim beside its mother immediately and nurses underwater. Milk from captive females averages 28 percent fat and 11 percent protein. Most calves keep nursing until about 20 months, although some nurse for more than two years. Teeth appear around the end of the first year, and the calf begins adding shrimp and small fish to its diet.

  Calves have help from outside the mother-calf pair. Alloparents, which are females other than the mother, care for them, and captive animals have been seen producing milk spontaneously and over the long term. In the wild, calves form groups called kindergartens while their mothers forage, and an alloparent called an aunt can look after them. A 2014 study found that most belugas swam in formation with both parents and alloparents.

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• 7. Rivers and Seasons

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  On the 9th of June 2006, a young beluga carcass was found in the Tanana River near Fairbanks, Alaska, nearly 1700 kilometres from the nearest ocean. Alaska state biologist Tom Seaton guessed that the whale had followed migrating salmon upriver the previous autumn. Belugas do sometimes follow fish, and groups or individuals have turned up hundreds or thousands of kilometres from the sea.

  Some belugas travel as far as 6,000 kilometres a year, and the routes are passed from parents to offspring. In autumn, when summer sites ice over, they move to open sea beside the pack ice. They survive there by surfacing through polynyas, which are open patches in the ice. When the sheet ice melts, they head for shallow coastal water only one to three metres deep. The timing of the journey follows daylight, not the condition of the sea ice.

  Rivers draw them for good reasons. Time in a river stimulates metabolism and helps renew the skin. Estuaries also serve as safe nurseries, since killer whales do not reach newborn calves there. Calves often come back to the same estuary as their mother, and may meet her there even once fully grown. The whales most often ascend the Northern Dvina, Mezen, Pechora, Ob and Yenisei in Asia, the Yukon and Kuskokwim in Alaska, and the Saint Lawrence in Canada.

  Not every group migrates. Resident populations stay in defined areas such as Cook Inlet, the Saint Lawrence estuary and Cumberland Sound. In Cook Inlet, the belugas stay in the innermost waters through summer and autumn. In winter they disperse to deeper water in the middle of the inlet without leaving it. Populations in Ungava Bay and on both sides of Hudson Bay spend the winter together beneath the ice in Hudson Strait.

  Counts vary widely among the 22 recognised stocks. Western Hudson Bay holds about 55,000 belugas, and the Eastern Beaufort Sea about 39,300. Cook Inlet has around 300 and the Saint Lawrence River estuary 889. Ungava Bay has only 32 and may be functionally extinct, while the southwest Greenland stock is extinct. Worldwide, the population is thought to be around 200,000. Yakutat Bay is not counted as a true stock, because belugas have been there only since the 1980s and fewer than 20 stay year-round.

  A few strays go much farther south, reaching Irish and Scottish waters, Orkney and the Hebrides, and Japan. One beluga became a resident of Lake Notoro in Hokkaido, living in its brackish water from 2014. On the 25th of September 2018, a lone beluga appeared in the Thames Estuary and was nicknamed Benny by newspapers. Local experts concluded in 2019 that it had left.

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• 8. Hunted and Held

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  In 1928, the Government of Quebec offered a reward of 15 dollars for every dead beluga. Fishermen in the Saint Lawrence estuary blamed the whales for eating large quantities of cod, salmon and tuna. A 1938 study by the Quebec Department of Fisheries began to examine that claim. The killing went on into the 1950s, until the whales' supposed appetite was found to be overestimated and not harmful to fish stocks.

  Native peoples in North America and Russia have hunted belugas for many centuries. Commercial whalers from Europe, America and Russia took them in the 18th and 19th centuries. Oil from the melon was used as a lubricant for clocks and machinery and as lighthouse fuel until mineral oil replaced it in the 1860s. The cured skin, the only cetacean skin thick enough to serve as leather, went into horse harnesses, belts for sawmills, shoelaces and some of the first bulletproof vests.

  The totals were huge. Scottish and American whalers killed more than 20,000 belugas in Lancaster Sound and Davis Strait between 1868 and 1911. Canada took 54,000 from 1731 to 1970. Russia's hunts peaked at 4,000 a year in the 1930s and 7,000 a year in the 1960s, totalling 86,000 between 1915 and 2014. Today some Inuit in Canada and Greenland, Alaska Native groups and Russians may still hunt belugas, since aboriginal whaling is excluded from the 1986 International Whaling Commission moratorium. About 1,000 animals are killed each year.

  The Red List of the International Union for Conservation of Nature rated the beluga near threatened in 2008. The Cook Inlet group is critically endangered and protected under the United States Endangered Species Act. In Canada, the eastern Hudson Bay, Ungava Bay and Saint Lawrence River populations are endangered.

  Nature adds its own pressure. In one documented incident, a polar bear weighing 150 to 180 kilograms captured a beluga of 935 kilograms trapped under ice. A Soviet researcher stationed at Novaya Zemlya reported a bear killing thirteen belugas in a row. Killer whales hunt young and adult belugas alike, and when they appear, belugas crowd into shallows where hunters can reach them.

  Pollution is worse in the Saint Lawrence. Local carcasses hold so many contaminants that they are handled as toxic waste. Among 129 adults examined between 1983 and 1999-27 percent had cancer, a rate comparable to humans and some domesticated animals. Ship noise matters too. Belugas detect icebreakers up to 50 kilometres away and flee along the ice edge for as far as 80 kilometres.

  Belugas were among the first whales kept in captivity. The first was displayed at Barnum's Museum in New York City in 1861. Canadian waters supplied most for much of the 20th century, until the Churchill River capture ban in 1992. Russia is now the largest supplier. A beluga costs up to US$100,000, though the price has dropped to US$70,000. In 2018, according to Ceta Base, 81 captive belugas lived in Canada and the United States.

  The United States Navy ran a program from 1960 to 1992 that used belugas for tasks such as retrieving lost objects and carrying cameras in their mouths. The Soviet Navy trained them for anti-mining work. On the 24th of April 2019, fishermen near the Norwegian island of Ingøya found a tame beluga wearing a Russian equipment harness.

  In 2019, two 12-year-old belugas named Little White and Little Grey, retired from a marine park in China, moved to a sea pen sanctuary in Iceland. Both were caught in Russia and raised in captivity, and they do not know how to live in the wild.

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