Beluga whale

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Beluga whale
Belugas or white whales

Belugas or white whales

Systematics
Order : Whales (cetacea)
Subordination : Toothed whales (Odontoceti)
Superfamily : Dolphin-like (Delphinoidea)
Family : Pilot whales (Monodontidae)
Genre : Delphinapterus
Type : Beluga whale
Scientific name of the  genus
Delphinapterus
Lacépède , 1804
Scientific name of the  species
Delphinapterus leucas
( Pallas , 1776)

The white whale ( Delphinapterus leucas ) or beluga ( Russian белуха belucha , from белый bely = "white") is a species of the green whale that lives in arctic and subarctic waters. Like the closely related narwhals , they have no dorsal fin ; their bluish-white to creamy-white color is striking.

Look

Outline drawing
Beluga skull - clearly visible the conical teeth and the mobile cervical vertebrae

Beluga whales are between three and a maximum of six meters long and weigh between 400 and 1000 kilograms; the males are usually larger and heavier than the females. The body looks massive and is rectangular in the shoulder area. The head is relatively short and has a bulging thickening that develops in the course of life and contains an organ called a melon . The neck can usually be recognized by a section of the neck and the head is quite mobile thanks to the non-grown cervical vertebrae . The fluke (caudal fin) is relatively wide and becomes increasingly ginkgo-leaf-shaped with the age of the animals . The flippers (pectoral fins) are rounded and rectangular, the outer edge rolls up in older animals. The eyes are very small and lie just behind the corners of the mouth, the ear opening is almost invisible. The crescent-shaped blowhole is just before the neck.

As with all whales , the skin is hairless and has a thick top layer. This epidermis is between 5 and 12 centimeters thick in white whales and is therefore above average for whales, as are the layers below. The subcutaneous tissue is formed into a layer of fat that is between 2 and 22 centimeters thick, depending on the nutritional status, gender and time of year. The teats of the females lie in special pockets and are only visible in old or suckling animals.

The beluga got its name from its coloration, which changes in the course of its life. Newborn beluga whales tend to be slate gray to brown and after about a year they acquire a blue-gray color that they keep until they are five years old. During this time they are called "blues". Then the animals become completely white, although a bluish tinge can remain, especially in females. Since the belugas are often on the edge of the pack ice , their white coloring is probably useful as camouflage protection against polar bear attacks .

An important characteristic of the beluga whales is their teeth. They are evenly conical and the front teeth are bent over, especially in young animals. Of these teeth, beluga whales have 10 to 22 in the upper jaw and 6 to 22 in the lower jaw; a differentiation into different tooth types is, as with all toothed whales, not possible.

Beluga whales are able to change their facial expressions through a number of physiognomic features that serve for communication. For example, you can pull the corner of your mouth up or down, which is not an expression of joy or displeasure, and even pucker your lips.

distribution

Spread of the beluga
Beluga at the confluence of the Churchill River and Hudson Bay

Belugas are found in most arctic and sub-arctic waters, especially on the coasts of Alaska , Canada, and Russia . The southernmost deposits are in the Sea of ​​Okhotsk and the Sea of ​​Japan in Asia and in the area of ​​the St. Lawrence Estuary in Canada.

In Europe, their occurrence is limited to the far north of Norway in the area of ​​the Varangerfjord , the Barents Sea and the waters of the Kola peninsula and around the Franz-Joseph-Land and Spitzbergen archipelagos . However, sporadic finds are also known around Iceland , Great Britain and even from the Baltic Sea . On May 16, 1966, a single animal was even spotted in the Rhine . After the whale, known as Moby Dick , had escaped stalking by interested biologists for several weeks and was about 400 kilometers upstream near Bonn , it swam back into the sea on June 16, 1966, in parts escorted by two police vehicles.

Immigration into rivers is very common in the beluga. In the Loire , the Elbe and in almost all Siberian rivers one came across individual animals or small groups. This immigration is mostly related to the seasonal migrations of the animals or their gatherings for mating in front of the estuaries. They can be observed in all populations and are probably used to find feeding grounds, mating sites or calving sites.

Way of life

The beluga whales prefer quiet coastal areas with moderate depth, especially sea bays or the estuary of larger rivers. The surf belt of the seas is avoided. Often they can also be found in the drift ice area or on the edge of the pack ice ; they probably only pass the open sea during their hikes.

Beluga whales feed almost exclusively on animal food. The composition of their food is the most varied of the whales examined so far. In total, over a hundred different food animals are known; the spectrum ranges from hollow animals to squid , mussels , crustaceans and arthropods to larger bony fish such as cod and salmon . The whales eat their food mainly in shallow sea depths of a maximum of ten meters by searching the bottom for organisms; however, they can also hunt in open water. The maximum documented diving depths are around 200 meters; however, it is very likely that these are rarely achieved. The diet of the beluga also changes with age. If in the newborns and the “blues” it still consists mainly of crustaceans such as the sand shrimp (genus Crangon ), it shifts more towards the fish with increasing age.

Reproduction and development

Beluga whale with calf

The males of the Belugas become sexually mature at around eight to nine years of age, the females at around five years of age. In males, the time of growing up is hormonally directly linked to a completely white color and a sudden enlargement of the testicles from about 130 cubic centimeters to at least 360, but on average 900 cubic centimeters.

The mating takes place in the months of April to May, further north also in July in the area of ​​the calving grounds. Estuaries are preferred because the water there is usually up to ten degrees Celsius warmer. There can then be gatherings of several thousand animals from all ages; in 1974, for example, over 5,000 belugas were counted in the delta of the Mackenzie River .

Females ready to mate usually attract several males who follow them. The copulation begins with an in-circuit Swim mates with the ventral side, followed by a longer copulation follows. After mating, the female forms a vaginal plug in, ovulation ( ovulation ) is only triggered by the pairing.

The gestation period for the beluga whales is around fourteen and a half months. The newborns are between 1.40 and 1.70 meters long and weigh between 45 and 75 kilograms. For the first breaths, the mother snouts them over the surface of the water, after which they always stay in their immediate vicinity, usually with body contact. Tooth eruption begins at the end of the second year of life, up to this point in time the young animals are suckled by the mother ( breast milk with around 23% fat and 16% protein). After weaning, the mother mates again, but her young usually stays with her for up to two years.

In one case, DNA tests showed that a conspicuous whale skull belonged to an animal that had emerged from a mating of a female narwhal with a male beluga.

Behavior, communication

School of beluga whales

Belugas are very gregarious and social animals and usually live in family groups or small groups. They are usually found in smaller schools of around ten individuals (over 50 percent of the observations), sometimes as individual swimmers (around 16 percent of the observations); however, there are also isolated groups with more than a hundred animals. The large groups that form during the mating season, sometimes with more than a thousand animals, are an exception during the seasonal encounters.

The beluga whales communicate via acoustic signals that are generated in the area of ​​the nasal passage to the blowpipe. The repertoire of the beluga whales is extremely large and ranges from humming noises to squeaking noises to very high-pitched chirping noises. The frequency range used extends from 0.7 to over 20 kilohertz. Many of the sounds are obviously intended to evoke conspecifics and are emitted , for example, by stranded whales . In the past, whalers called the belugas the "canaries of the seas" because of their "joy in singing" and their enormous repertoire.

Man and beluga whale

Hunting and culture

Traditional hunt for beluga whales

The beluga whale is still hunted , but the number of animals shot has fallen sharply in recent years. Essentially, the beluga is hunted by Eskimos for traditional reasons and for personal use ( native hunt ). While the Eskimos used everything from the whale until the beginning of the 20th century - bones, tendons and fibers for house, sledge, boat and tool construction, skin and entrails as covering and packaging material, meat and bacon (Tran) as food for Humans and sled dogs and as energy suppliers (fuel) - this has changed fundamentally in the meantime. Today, the beluga is primarily important to them as a supplier of the Maktaaq , which is considered a special delicacy , the whale skin with the layer of fat under the epidermis (blubber, rind). They also use the appropriate parts of the whale as food for sled dogs.

Commercial hunting, fishing competition

The white whale is practically only caught commercially in northern Russia. Relevant for the decline in commercial whale hunting was the increasing pollution with DDT , PCB , lead , cadmium , titanium and mercury of the organisms consumed by the whales , especially near the coast , which can be detected in the meat and fat of the whales and is increasingly causing diseases. In the case of the beluga population living in the polluted estuary of the Saint Lawrence River , z. B. often cancers of the digestive tract.

In 1929, a lack of knowledge of the natural fluctuations in fish stocks, especially halibut and salmon, meant that every fisherman off Newfoundland was paid premiums for shooting belugas, as well as an extra premium if they could produce a beluga fin. Since the belugas were blamed for the catastrophic collapse of the fishing industry off the east coast of Canada, the Ministry of Fisheries was not afraid to drop bombs in a chartered plane in the Saint Lawrence River.

The protection of the beluga whales is considered sufficient due to decreasing hunting and global whale protection measures. An important contribution supplies also of tourism after Walbeobachtungsprogramme have also become of belugas in easily accessible coasts in Canada and Alaska very popular. On the other hand, increasing activities for the extraction of crude oil in polar waters, which lead to increasing disturbance of the animals and pollution of their habitats, prove to be problematic .

Environmental pollution

The white whale population of the St. Lawrence River is particularly suitable for considering pollution. First, the belugas are very isolated from the other occurrences here. Second, the region is one of the most polluted in the world. Heavy metals , especially mercury and lead, are introduced by agriculture and industry . Likewise, organic chlorine compounds such as PAH , PCB and DDT and their metabolites, to name just a few. The St. Lawrence River is a kind of "catch basin" for the runoff from the most highly industrialized region in the world. In addition, it is known to be naturally polluted by mercury. Therefore, it is important to know how high the difference between naturally occurring and anthropogenic is caused mercury exposure. So could i.a. Outridge (2001), Martineau (2002) or e.g. B. Béland (1996) show that there has been a constant content of natural mercury since the 13th century, but that anthropogenic pollution has increased significantly. Martineau (2002) also demonstrated that there is a connection between the economic location of the St. Lawrence River and the pollution of the belugas living there. It was found that the advancing industrialization also caused an increase in pollution in the world's oceans. However, it has not been clarified exactly what the human-caused proportion is, which should be investigated using different methods.

Hard tissue vs. soft tissue

Analyzes of the teeth were available to show the changes in the concentration of mercury in the beluga populations over time. In contrast to bones, these are subject to gradual growth and not constant change, so that the trace elements that accumulate over time are more likely to be retained. Even after death, these elements can be analyzed better than in bones, where chemical change processes still take place. The accumulation of Hg in teeth is accordingly viewed as an indicator of the stress on the soft tissue of the beluga. Nevertheless, tissue samples from the liver and kidneys were also examined and compared with the results of the dental analysis. These results showed that the mercury concentrations in the teeth of the belugas corresponded to 46-61% with the values ​​from other tissue parts of the body (including the kidneys, liver and muscles). The proportion of mercury therefore increases equally in soft tissue and hard tissue , so that the numbers correlate and the results can be interpreted in the same way.

In addition, the teeth should be included in studies, as they can also provide information about the age of the animal due to the agreement of the concentrations of mercury, which can also be done after death. Accordingly, the examination of teeth facilitates research in this area, since materials from a bygone era are required for a retrospective study. Since these are preserved longer and are not subject to a strong process of decomposition, as is the case with other organs, they are particularly suitable for a corresponding analysis. Tissue databases have only been known for a few decades. Therefore it is hardly possible to get soft tissue samples from the time before 1800. With hard tissue such as teeth, this problem is hardly present.

Method and results

According to the Arctic Monitoring and Assessment Program (AMAP) 2011, heavy metal pollution in belugas, seals, polar bears and birds of prey has increased tenfold over the past 150 years. In order to be able to understand the changes in the mercury concentrations in the affected waters, Outridge, Martineau and Belánd carried out studies on the belugas, which were intended to put the values ​​from pre-industrial times until today into context. The stranded belugas and their carcasses were autopsied for over 17 years and possible causes of death, such as B. parasitic infections, cancers and viral infections examined.

In the period from 1983 to 1999, 128 stranded beluga whales were analyzed, of which 23 animals were found to be cancerous, with 21 different types of cancer in question, of which 18 types were already in the terminal stage. Since 1982, Béland and Martineau have autopsied another 73 belugas at the University of Montreal's Faculty of Veterinary Medicine, Canada, within 15 years. Of these, around 40% of the autopsied animals had tumors and around 45% of the adult dams had insufficient milk production, which was due to inflammation, necrotic tissue or tumors in the mammary glands. The most common cause of cancer in the St. Lawrence Belugas was gastrointestinal epithelial carcinoma.

The belugas stranded on the Saint Lawrence River were between the ages of 21 and 25, whereas the belugas in northern Alaska often reach the age of 38 years. It turned out that 10-year-old belugas from 1993 had a mercury level 2.1 times higher than those from pre-industrial times. In the 40-year-olds it was 9.1 and in the over 60-year-olds even 17.7 times higher exposure could be determined. On average, the belugas from 1960/61 between the ages of 10 and 60 were found to be 3.1-4.5 times higher than those from pre-industrial times between the 15th and 17th centuries. 67 - 78% of this is attributed to anthropogenic influences in the Belugas from 1960/61 and 52 - 94% in the individuals from 1993.

Overall, the results of the analyzes showed that approx. 80 - 95% of the mercury pollution in the belugas, which had already reached the age of ten, can be traced back to anthropogenic influences.

The mercury exposure (Hg)

An increase in mercury pollution (Hg) in the arctic waters of North America and West Greenland not only pollutes the beluga whales, whose cancer rate is very high in the St. Lawrence River area as a result. The following table gives an overview of the level of mercury concentrations in the various tissues of the belugas.

-
organs Hg concentration [μg / g]
Dermis 0.29
epidermis 1.5
Muscle tissue 1.4
Total concentration in the skin 0.84
Bubble 0.12
Annual total recording 131,400

However, the balance of the uptake and excretion of mercury must be considered at this point . The annual general excretion of Hg is approx. 70%, that of the moult is approx. 0.42 - 2% of the total annual intake. The exposure figures suggest that not all of the ingested quantities of the toxic mercury can be excreted and thus accumulate in the animals' organism over time, which explains the high number of cancerous or dead individuals.

Consequences of the mercury exposure

The chemicals mentioned, such as mercury, PAH , PCB and DDT and their metabolites, are fat-soluble , can not be broken down during metabolism and are deposited in the fatty tissue of the animals. Above all, the problem of mercury accumulation arises not only from the fact that Hg is harmful to the animal itself, but is also particularly dangerous for consumers of beluga meat. This is also due to the natural food chain , in which carnivores absorb the chemicals from other already contaminated animals and pass them on to other animals in an even higher concentration. B. the beluga is also most heavily burdened as an end consumer. Because of this, it must be pointed out that the consumption of beluga meat should be avoided even in natural areas. This is particularly problematic for the local Eskimos , who use the belugas as their traditional main source of food. In the meantime, the white whales of the St. Lawrence River are protected, but the polluted population is not able to recover because the chemicals have settled over many decades and the dams have attached them to their offspring in the form of polluted, concentrated milk be passed on.

Trivia

  • The Beluga is the namesake for the Airbus A300-600ST (" Airbus Beluga ").
  • Beluga is the name of two ships of Greenpeace .
  • The well-known beluga caviar does not come from the beluga whale, but from Hausen .
  • A beluga also appears in the error messages from Twitter .
  • A trusting Beluga who appeared in northern Norway in April 2019 was wearing a harness with a camera holder, so he was suspected of Russian espionage; in a poll he was nicknamed Hvaldimir .
  • The above-mentioned white whale Moby Dick , sighted in the Rhine near Bonn in 1966, is the namesake of a tourist ship in Bonn in the form of a whale.
  • A name for the beluga that used to be common among whalers was "Butzkopf".

literature

  • Pierre Béland: Environmental toxins - the fall of the belly whales in the Saint Lawrence River . In: Spectrum of Science. 7, 1996, p. 84.
  • Mimi Breton, T. Smith: The Beluga. (= Underwater World). Dept. of Fisheries and Oceans Canada, Ottawa Ont 1990, ISBN 0-662-17987-0 (English).
  • Wolfgang violence : whales and dolphins - top performers of the seas . Springer Verlag, Berlin / Heidelberg 1993, ISBN 3-540-56668-6 .
  • Wolfgang violence: the white whale . (= The New Brehm Library . Volume 497). Westarp Sciences, Hohenwarsleben 2001, ISBN 3-89432-836-3 .
  • International Whale Committee: IWC - Report of the sub-committee on small cetaceans . In: Report of the… annual meeting of the Scientific Committee of the International Whaling Commission. IWC, Cambridge 42.1992, pp. 185-193; 43.1993, pp. 130-132 (English).
  • Marine Mammal Commission: Cook Inlet Beluga Whale (Delphinapterus leucas) . In: Marine Mammal Commission, Annual Report for 2002. Washington DC 2002, pp. 58-63.
  • Daniel Martineau, inter alia: Cancer in Wildlife, a Case Study: Beluga from the St. Lawrence Estuary Québec, Canada. In: Environmental Health Perspectives. Vol. 110. 2002, pp. 285-292 (English).
  • Paul Leyhausen : cetaceans. In: Brockhaus. Grzimek's encyclopedia. Volume 4, Brockhaus, Leipzig / Mannheim 1997, ISBN 3-7653-6141-0 .
  • Tony Martin: Beluga Whales . Voyager Press, Stillwater MN 1996, ISBN 0-89658-306-6 (English).
  • DW Morgan: The vocal and behavioral reactions of the beluga "Delphinapterus leucas" to playback of its sounds. In: Behavior of marine animals. Volume 3: Cetaceans. Plenum Press, New York 1979, ISBN 0-306-37573-7 (English).
  • J. Niethammer, F. Krapp (Ed.): Handbook of Mammals in Europe. Volume 6: Marine Mammals. Part 1A: whales and dolphins 1. AULA-Verlag, Wiebelsheim 1994, ISBN 3-89104-559-X .
  • PM Outridge: Teeth as biomonitors of soft tissue Mercury Concentrations in Beluga . In: Environmental Toxicology and Chemistry. Vol. 19, No. 6, 2000, pp. 1517-1522 (English).
  • PM Outridge et al .: A Comparison of Modern and Preindustrial Levels of Mercury in the Teeth of Beluga in the Mackenzie Delta, Northwest Territories, and Walrus at Igloolik, Nunavut, Canada . In: Arctic. Vol. 55. No. 2. 2002, pp. 123-132 (English).
  • R. Wagemann, H. Kozlowska: Mercury distribution in the skin of beluga (Delphinapterus leucas) and narwhal (Monodon monoceros) from the Canadian Arctic and mercury burdens and excretion by moulting. In: Science of the Total Environment . Volumes 351-352, December 1, 2005, pp. 333-343, doi: 10.1016 / j.scitotenv.2004.06.028 (English).

Web links

Wiktionary: Beluga whale  - explanations of meanings, word origins, synonyms, translations
Commons : Beluga  album with pictures, videos and audio files

Individual evidence

  1. White whale sighted in the Baltic Sea , shz.de / Eckernförder Zeitung from November 19, 2012, accessed on September 10, 2018.
  2. The whale on the Rhine
  3. Mikkel Skovrind et al .: Hybridization between two high Arctic cetaceans confirmed by genomic analysis , Scientific Reports, Volume 9, 2019, Article No. 7729. doi: 10.1038 / s41598-019-44038-0 (English).
  4. Martineau et al .: Cancer in Wildlife, a Case Study. Beluga from the St. Lawrence Estuary, Quebec, Canada. In: Environ Health Perspect . 110, 2002, pp. 285-292. PMID 11882480 (English).
  5. ^ To this end, the Musée de la mémoire vivante (Museum of Living Memory) in Saint-Jean-Port-Joli, Quebec organized a special exhibition entitled; see The Last Beluga Fisherman .
  6. a b c P. M. Outridge et al .: A Comparison of Modern and Preindustrial Levels of Mercury in the Teeth of Beluga in the Mackenzie Delta, Northwest Territories, and Walrus at Igloolik, Nunavut, Canada. In: Arctic. Vol. 55. No. 2, 2001, pp. 123-132 (English).
  7. a b c d Daniel Martineau et al .: Cancer in Wildlife, a Case Study: Beluga from the St. Lawrence Estuary Québec, Canada. In: Environmental Health Perspectives. Vol. 110, 2002, pp. 285-292 (English).
  8. a b c d Pierre Béland: Environmental toxins - the fall of the white whales in the St. Lawrence River. In: Spectrum of Science. 1996, 7, p. 84.
  9. PM Outridge et al. 2001, p. 126 f.
  10. a b P. M. Outridge: Teeth as biomonitors of soft tissue Mercury Concentrations in Beluga. In: Environmental Toxicology and Chemistry. Vol. 19, No. 6, 2000, pp. 1517-1522 (English).
  11. ^ A b R. Wagemann, H. Kozlowska: Mercury distribution in the skin of beluga (Delphinapterus leucas) and narwhal (Monodon monoceros) from the Canadian Arctic and mercury burdens and excretion by moulting. In: Science of The Total Environment. Volumes 351-352, December 1, 2005, pp. 333-343.
  12. Wolfgang violence: The white whale. Hohenwarsleben 2001.
  13. www.mobydick-bonn.de
  14. peter-hug.ch/butzkopf