Right whales
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A northern right whale ( Eubalaena glacialis ) with calf |
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| Balaenidae | ||||||||||||
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The right whales (Balaenidae) are a family from the order of the whales (Cetacea) with currently four species . They live in the northern and southern seas and feed on plankton . Due to various characteristics, they are clearly differentiated from the other baleen whales (Mysticeti). The approximately 15 to 20 meter tall animals were decimated the most of all whales by hunting. In the past they were often referred to as whale or common whale in German .
anatomy
General morphology
Right whales are rather clumsy. They lack a dorsal fin . The flippers are quite short, but strong.
Significant differences to the closely related furrow whales can be found in the construction of the head. The upper jaw (rostrum) is strongly arched, the jawbone is much narrower than that of furrow whales. The head is proportionally much larger than that of furrow whales. In the bowhead whale , the head can make up 40% of the body length, i.e. about eight meters with a body length of twenty meters. Characteristic are the long, thin, black Barten , which in the Northern capers and the Südkaper are about 2.5 meters and about 4 meters long in the bowhead. Right whales lack the furrows on their throats that allow the furrow whales to expand their mouths widely. All seven cervical vertebrae are fused together . Furthermore, right whales are characterized by an extremely thick layer of fat , which is significantly larger than that of other whales . As inhabitants of mostly very cold seas up to the Southern Ocean, the right whales formed the thick bubbler as an insulation against the cold water.
Northern right whales and southern right whales differ from other whale species and also from closely related bowhead whales by their conspicuous skin growths in the head area. The upper and lower jaws and the eye area are particularly affected. They are of barnacles and Walläusen ( Cyamus settled). A few terms are used to describe the growth on various skin growths:
| Location of the skin growth | designation |
|---|---|
| Growth in front of the blowhole | Sill bar |
| Growth behind the blowhole | Growth behind the blowhole |
| Vegetation on the tip of the upper jaw | Cap |
| Growth on the tip of the lower jaw | beard |
| Vegetation between the cap and the coaming | Rostral support |
| Right behind the beard | Mandibular growth |
| Growth on the upper and lower lip | Lip stain |
| Growth in the immediate vicinity of the eye | Eyebrow |
It is noticeable that the "hats" are more pronounced in bulls than in females. Why this is so is unclear. The hats may play a role in courtship and mating behavior. For scientists, the training of the cap for the identification of individual individuals is helpful. Due to the individual training of the hats, almost the entire north and south caper population has been cataloged in the meantime. This is intended to be used to research age, life cycle and hiking routes.
Height and body mass
Right whales are among the largest mammals ; however, compared to other baleen whales, they are only medium-sized. Northern right whales and southern right whales are about the same size and weight; they are usually about 15 meters long, the maximum body length can reach 18 meters. Their weight is between 50 and 56 tons. With an average of 17 meters, the bowhead whale becomes even larger. The length of extremely large specimens of this species can exceed 20 meters. Such specimens, which are rarely found, then weigh around 80 tons. Usually the average weight of these whales is around 65 tons.
distribution
Right whales prefer to live in cold seas, but on their migrations they also reach warm seas in the subtropics. Almost all waters around the Arctic are inhabited by right whales, as are large parts of the North Atlantic and the North Pacific . The northern Atlantic right whale , the northern Pacific right whale and the bowhead whale live here. The three mentioned whale species also live in the Sea of Okhotsk and on many coasts of East Asia, around all of Japan . However, they are almost completely absent on the north coast of Russia . The southern hemisphere is inhabited by the southern right whale, who inhabits all of the southern seas except for the coasts of Antarctica. The south coast of Australia , parts of the coast of South America and the south coast of Africa belong to the area he inhabits. Despite its wide distribution, the density of the population in this area is low.
Distribution of the Atlantic North Cape
Distribution of the Pacific North Cape
Distribution of the bowhead whale
Distribution of the southern caper
Way of life
Social structure
The social structure of the right whale is largely unexplored. Right whales presumably live solitary or in small groups of three to four individuals. Right whales have been observed to frequently jump out of the water and hit the surface of the water with their fluke. These loud noises probably serve to inform other right whales of their own position.
nutrition
The right whale consumes different species of copepods most often , but the range of diets seems to vary depending on the species. In addition to copepods, the two northern right whales also eat young krill and the swarm-forming larvae of many species of zooplankton . In addition to its normal food, the southern right whale also consumes krill of all stages of development. The food requirement for a single adult right whale is around 1,000 to 2,500 kilograms per day.
To acquire food, right whales simply swim with their mouths open through schools of zooplankton. In contrast to this, furrow whales eat “gulps”; they pull the water into their mouths and then push it out again, causing the zooplankton to cling to the whiskers. The right whale dives to feed mostly last around 8 to 12 minutes, but rarely do they catch their prey on the surface. They only do this if a higher yield can be expected there. The two northern right whales keep in physical contact with some members of their group while searching for food, the reason for this has not yet been established with certainty.
Vocalizations
So far , the whale song of right whales has not been adequately researched; the repertoire of all calls is probably much larger than previously known. There are at least two different sounds: contact calls, which animals use to communicate over long distances, and calls which cows use to attract bulls. Humpback whales produce coherent, repeated sequences of sounds that could be referred to as “songs”, whereas right whales produce deep, single tones in rapid succession, the frequency of which is in the range of 50 to 500 Hertz . A call, the purpose of which is not yet known, is emitted when catching prey: This sounds like a gurgling and is in the frequency range of 2 to 4 kilohertz. Bowhead whales produce simpler sounds than the southern right whale and the two species of northern right whales.
Reproduction and development
Since in the long reproductive cycle of the right whale there are usually two to three years between two litters, often less than a third of all females in a region are ready to conceive. This third attracts the bulls by means of acoustic signals. The mating usually takes place in the period from late autumn to spring of the respective hemisphere . When the bull arrives, the female tries to delay mating by swimming away or by swimming on her back and stretching her flippers . The cops' recruitment consists in pushing the rivals away. The hat may also play a role, but nothing is known about this. The females are fertilized by different males, these probably lead a sperm competition. This is also indicated by the fact that the testes of right whales, especially the southern right whale, are the heaviest in the world, sometimes weighing over 800 kilograms. They also have the largest testicles in relation to their body size among the baleen whales .
After a gestation period of 10 to 13 months, a maximum of 17 months, the female calves and gives birth to a single, 4 to 5 meter long young. The calf seldom moves away from the female, almost never more than a body length. The fast-growing calves are weaned after about a year and are then usually 8 to 9 meters long. Sexual maturity occurs around 9 years of age, but very precocious females sometimes calve around 6 years of age. Right whales can get very old, a female has been sighted regularly since at least 1935 and is probably well over 80 years old. Based on the annual rings of the bony ear capsule, the age of the oldest known specimen, a male bowhead whale, was determined to be 211 years at the time of his death. This would have made it older than many of the giant tortoises known for their age such as Harriet (176 years) and Tuʻi Malila (188 or 192). The exact age of the turtle Adwaita has not yet been determined, if the age of 256 years is not confirmed, this bowhead whale is probably the oldest known vertebrate.
The mortality rate of right whale calves is around 17% in the first year of life, 3% of the calves die in the following 3 years. After that, the death rate is extremely low.
hikes
At the moment, knowledge about the migration routes of right whales is still very poor. According to Eskimos , they move separately by age and gender.
Right whales of the northern hemisphere
The most important winter casting areas for right whales in the Atlantic Ocean in the northern hemisphere are on the coasts of the US states of Georgia and Florida . It is not clear where the remaining specimens calve. Two-thirds of the total northern caper population is often sighted in the Gulf of Maine during spring, summer and fall. Analyzes of various data and observations suggest that there is a second, as yet unidentified summer area.
The best researched so far is the bowhead whale migration. This is based on the water currents from water channels in the drift ice. They overwinter mainly in the Bering Sea and also calve there. They summer in other areas, such as Cape Bathurst, the Amundsen Golf, in the Mackenzie Delta and on the coast of Yukon.
Southern right whale
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Southern right whales calve on the southern coasts of South Africa , Argentina and Australia, as well as around some New Zealand islands such as Dog Island. The summer areas are only partially known. The southernmost sighting so far took place in the Antarctic Arctic Ocean .
Systematics
External system
Due to various morphological differences between the furrow whales and right whales, which were mentioned under general morphology, right whales are classified in their own family . An interesting point is the classification of the pygmy right whale ( Caperea marginata ). Despite the name and some morphological parallels to the right whales, this is placed in its own family Neobalaenidae.
Internal system
As of today, there are four species in the family of right whales:
- Northern Atlantic right whale ( Eubalaena glacialis )
- Northern Pacific right whale ( Eubalaena japonica )
- Southern right whale ( Eubalaena australis )
- Bowhead whale ( Balaena mysticetus )
Previously, Eubalaena glacialis and Eubalaena japonica as a subspecies of the kind Eubalaena glacialis out. More recent DNA studies, however, substantiated the thesis that the two are two separate species.
Humans and right whales
whaling
Today's right whale populations are drastically reduced residual populations due to hunting. More than a thousand years ago, the Basques were the first to recognize good prey in the right whales and hunt them. With their weapons they developed the basis for whalers of the 20th century. Industrial whaling reduced the number of animals almost to extinction. A whale family has never been more decimated. In the more intensely hunted southern hemisphere, the hunt mostly took place at the southern capers' throwing sites and in some bays. First the calf was killed to make it easier to kill the mother. The prey was pulled on land or into shallow water and used there. The beards were always removed because they had a high market value. If the catchers were also interested in the oil, they loosened the bubbler , cut it up and made the oil with large cast iron pans.
Northern and southern right whales were protected on an international level around 1935. Despite this, Soviet Union whalers hunted thousands of specimens in the South Atlantic, Indian Ocean and Pacific until 1960.
The English name for right whales, which is still “ right whale ” today , goes back to the fact that right whales were the right prey because they were slow and large, due to their fat content after death they floated on the surface (ie did not sink) and a lot Beards and oil supplied.
Much knowledge about bowhead whales and their hunt comes from a report by William Scoresby, who published it under the name Report on the Arctic Territories . Bowhead whales were often hunted, especially when the hand harpoon was still used for hunting.
- “ […] Less lively, slower in its movements and less aggressive than any other similarly sized species, in short, it is easy to capture. ",
Scoresby established the popularity of bowhead whale hunting around 1820. There are also records of various economic aspects of the beards. Harmer reports that a ton of the so-called whalebone fetched peak prices of £ 2,250 at times. Some of the one and a half tons of whale produced by a bowhead whale were worth £ 3,375. Because of all these advantages, a lively hunt quickly started, which resulted in a sharp decline in populations, although a fishing ship usually caught no more than 7 to 10 whales per season. As the coastal populations became smaller and smaller, the whalers had to go out to sea in order to get enough prey. From 1850 the stocks were so small that hunting was no longer worthwhile. They were completely eradicated in the European Arctic Ocean.
Threats and Protection Today
After the ban, intensive protection was provided immediately; marine parks have now been set up for the southern right whale off South Africa , Argentina , New Zealand and Australia , and special regulations regulate the protection and handling of right whales. The population of the southern caper seems to be recovering, the population there comprises around 10,000 animals with a growth rate of 6 to 7% (as of 2008). Mostly with a focus on the dwindling stocks of the northern hemisphere, however, recent estimates predict the extinction of the right whale in 200 years, as threat factors such as shipping will most likely maximize in the future. In reality, however, little is known about the North Pacific population in particular.
Since all right whales prefer to stay near the coast, they are particularly affected by the expanding shipping traffic. Large fishing nets also pose a threat. About 38% of all deaths are due to collisions with ships. Since December 2008, larger ships off the east coast in the USA have had to reduce their speed to ten knots (19 kilometers per hour) in order to protect the endangered right whales from collisions and injuries caused by propellers. 8% of all dead right whales drown in fishing nets. Studies have shown scars on 60% of all specimens of the two northern right whales, which were caused by the indirect influence of the fishing industry, especially by fish traps designed for catching crustaceans. The US fishing industry is now trying to use alternative fishing methods to reduce the number of casualties.
Stocks
The population of the bowhead whale currently amounts to 10,000 specimens, appears to be stable not least because of its remoteness in northern seas and has increased by almost 30% compared to the population of 8,200 animals in 1993. The northern right whale lives in less remote habitats with a higher rate of hunting and danger, so its population has increased from a few animals after the hunt for right whales ended to only around 300 to 350 individual animals. No details are known about the presumably small population of the Pacific North Cape. The southern right whale has a stable population of around 7000 individuals
Right whales and Eskimos
The Eskimos of the Arctic have long hunted bowhead whales . Harpoons with ivory or stone tips were used in the past . The 10,000 to 20,000 individuals that existed before the commercial hunt were not endangered despite the hunting by the Eskimos and the population was stable. In the 19th century, however, a number of American and European hunting ships decimated the population in the Bering Sea to a few thousand specimens, and a few hundred animals lived outside the Bering Sea. In 1915 the hunt was largely stopped, but the Eskimos continued to hunt. Despite the discontinuation of hunting by Europeans and Americans, the eastern populations in particular did not fully recover. This is probably due to various factors such as inbreeding due to small populations, but probably the most important cause was the change in hunting methods of the Eskimos. These have been using harpoons with HE shells since 1880, so in 1977 the Scientific Committee of the International Whaling Commission (IWC) recommended an end to the hunt. After massive protests by the Eskimos, which emphasized their cultural and economic dependence on whaling, they were granted a limited hunting permit, which should be assigned and enforced by the Alaska Eskimo Whaling Commission. The western populations are now growing at an annual rate of 3% despite the catch of the Eskimos. According to a calculation with the population from 1993 (8,200 animals), it is concluded that 56 whales can be shot annually without any problems.
swell
literature
- Scott D. Kraus, David E. Gaskin and John Craighead George: Glattwale in: David MacDonald (Ed.): The large encyclopedia of mammals , Könemann Verlag, Königswinter 2005, ISBN 3-8331-1006-6 (German translation of the English original edition from 2001)
- Bernhard Grzimek (Ed.): Grzimeks Tierleben Säugetiere 2 , Bechtermünz Verlag, Augsburg 2000, ISBN 3-8289-1603-1 (unchanged reprint of the original edition from 1980)
Web links
- Right whales on Animal Diversity Web
- Balaena mysticetus in the endangered Red List species the IUCN 2006. Posted by: Cetacean Specialist Group, 1996. Accessed on November 3 of 2006.
- Eubalaena glacialis in the endangered Red List species the IUCN 2006. Posted by: Cetacean Specialist Group, 1996. Accessed on November 3 of 2006.
- Eubalaena japonica in the endangered Red List species the IUCN 2006. Posted by: Cetacean Specialist Group, 1996. Accessed on November 3 of 2006.
- Eubalaena australis in the endangered Red List species the IUCN 2006. Posted by: Cetacean Specialist Group, 1996. Accessed on November 3 of 2006.
References and comments
- ↑ Illustrated natural history of the animal kingdom. First volume: Natural history of the mammals . JJ Weber, Leipzig, 1847/48.
- ↑ To http://animaldiversity.ummz.umich.edu/site/accounts/information/Balaenidae.html
- ^ According to MacDonald (2005), p. 270.
- ↑ Threatened Giants , Spiegel Online , October 26, 2008
- ↑ "Speed limit should save whales" the daily newspaper December 9, 2008
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^ Numbers according to the Red List of Threatened Species, compiled by the IUCN. Detailed information linked below, they also served as sources for the numbers in this article:
- Balaena mysticetus in the endangered Red List species the IUCN 2006. Posted by: Cetacean Specialist Group, 1996. Retrieved on November 11 of 2006.
- Eubalaena glacialis in the endangered Red List species the IUCN 2006. Posted by: Cetacean Specialist Group, 1996. Retrieved on November 11 of 2006.
- Eubalaena japonica in the endangered Red List species the IUCN 2006. Posted by: Cetacean Specialist Group, 1996. Retrieved on November 11 of 2006.
- Eubalaena australis in the endangered Red List species the IUCN 2006. Posted by: Cetacean Specialist Group, 1996. Retrieved on November 11 of 2006.
