Other threats include natural predators (polar bears and killer whales), contamination of rivers (as with polychlorinated biphenyl (PCBs) which bioaccumulate up the food chain), climate change and infectious diseases.

A Japanese researcher claimed that he taught a beluga to "talk" by using these sounds to identify three different objects, offering hope that humans may one day be able to communicate effectively with sea mammals.

Because Charlotte is over 150 mi (240 km) from the nearest ocean, early naturalists were at a loss to explain the presence of the bones of a marine mammal buried beneath the fields of rural Vermont.

[28] The method used to calculate the age of a beluga is based on counting the layers of dentine and dental cement in a specimen's teeth, which were originally thought to be deposited once or twice a year.

[49] This gives the head a lateral manoeuvrability that allows an improved field of view and movement and helps in catching prey and evading predators in deep water.

[43] Areas in the mouth have been found that could act as chemoreceptors for different tastes, and they can detect the presence of blood in water, which causes them to react immediately by displaying typical alarm behaviour.

[65] Studies of captive females have indicated their milk composition varies between individuals and with the stage of lactation; it has an average content of 28% fat, 11% protein, 60.3% water, and less than 1% residual solids.

[46] They produce a rapid sequence of clicks that pass through the melon, which acts as an acoustic lens to focus the sounds into a beam that is projected forward through the surrounding water.

[117][118] One such example comes from June 9, 2006, when a young beluga carcass was found in the Tanana River near Fairbanks in central Alaska, nearly 1,700 km (1,100 mi) from the nearest ocean habitat.

[119] The rivers they most often travel up include: the Northern Dvina, the Mezen, the Pechora, the Ob and the Yenisei in Asia; the Yukon and the Kuskokwim in Alaska, and the Saint Lawrence in Canada.

[127] There had been several vagrant individuals[128] that have demonstrated seasonal residencies at Volcano Bay,[129][130][131] and a unique whale were used to return annually to areas adjacent to Shibetsu in Nemuro Strait in the 2000s.

Belugas have been easy prey for hunters due to their predictable migration patterns and the high population density in estuaries and surrounding coastal areas during the summer.

[148][149] Previous levels of commercial whaling have put the species in danger of extinction in areas such as Cook Inlet, Ungava Bay, the St. Lawrence River and western Greenland.

[155] L'Isle-aux-Coudres is the setting for the classic 1963 National Film Board of Canada documentary Pour la suite du monde, which depicts a one-off resurrection of the beluga hunt; one animal is caught live, and transported by truck to an aquarium in the big city.

[172][173] A number of killings have been recorded in Cook Inlet, and experts are concerned the predation by killer whales will impede the recovery of this sub-population, which has already been badly depleted by hunting.

The beluga is considered an excellent sentinel species (indicator of environment health and changes), because it is long-lived, at the top of the food web, bears large amounts of fat and blubber, relatively well-studied for a cetacean, and still somewhat common.

[177] These substances have a proven adverse effect on these cetaceans, as they cause cancers, reproductive diseases and the deterioration of the immune system, making individuals more susceptible to pneumonias, ulcers, cysts, tumours and bacterial infections.

[177] Although the populations that inhabit the river estuaries run the greatest risk of contamination, high levels of zinc, cadmium, mercury and selenium have also been found in the muscles, livers and kidneys of animals that live in the open sea.

This condition is thought to be directly related to environmental contamination, in this case by polycyclic aromatic hydrocarbons, and coincides with the high incidence of this disease in humans residing in the area.

[186]: 26, 303, 359  The bacterium Erysipelothrix rhusiopathiae, which probably comes from eating infected fish, poses a threat to belugas kept in captivity, causing anorexia and dermal plaques and lesions that can lead to sepsis.

[156] Individuals are caught in the Amur River delta and the far eastern seas of the country, and then are either transported domestically to aquaria in Moscow, St. Petersburg and Sochi, or exported to foreign nations, including China[147] and formerly Canada.

[195] The program included training them to carry equipment and material to divers working under water, the location of lost objects, surveillance of ships and submarines, and underwater monitoring using cameras held in their mouths.

The latter is possible because while most cetacean "smiles" are fixed, the extra movement afforded by the beluga's unfused cervical vertebrae allows a greater range of apparent expression.

Subsequent recordings confirmed that NOC had become skilled at imitating the patterns and frequency of human speech, and intentionally altered his normal methods of vocalization to achieve these sounds.

[238] The IUCN and NOAA Fisheries cite habitat degradation, oil and gas drilling, underwater noise, harvesting for consumption and climate change as threats to the prolonged survival of beluga whale sub-populations.

[241] For example, the number of vessels in the Arctic for gas and oil exploration, fishing, and commercial shipping has already increased and a continuous trend may lead to higher risks of injuries and deaths for beluga whales.

[241] In addition, it is possible that beluga whales may face by an increased risk of entrapment from leads and cracks freezing, due to the erratic nature of climate change.

Since it is very difficult to know the exact population of belugas because their habitats include inland waters away from the ocean, they easily come in contact with oil and gas development centres.

With the extreme difficulty of studying beluga whales in the wild and the lack of ability to collect biological samples or perform examinations on individuals, managed care facilities play a critical role.

Pour la suite du monde, is a Canadian documentary film released in 1963 about traditional beluga hunting carried out by the inhabitants of L'Isle-aux-Coudres on the Saint Lawrence River.