Ringed seal
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Ringed Seal ( Pusa hispida ) |
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| ( Schreber , 1775) |
The ringed seal ( Pusa hispida , Syn . : Phoca hispida ) is the most common seal species in the Arctic . In addition to the Arctic Ocean , this close relative of the seal also lives in the northern parts of the Baltic Sea .
features
The name ringed seal is based on the fact that the fur is provided with light-colored rings that surround dark spots on a gray background. Adult animals are on average 135 cm long and 70 kg heavy; the ringed seals of the Baltic Sea are larger with over 140 cm in length and 100 kg in weight. Males are usually slightly larger than females. In general, ringed seals have good eyesight and excellent hearing and smell.
distribution
Four subspecies inhabit very different habitats, but all of them are in polar or sub-polar regions. The polar sea ringed seal ( P. h. Hispida ) is the most common seal in the Arctic Ocean , where it is at home on the drift and pack ice; a special freshwater population seeks Nettilling Lake on Canada's Baffin Island over and over again . The Baltic ringed seal ( P. h. Botnica ) lives in the cold areas of the Baltic Sea, for example on the coasts of Sweden , Finland and Estonia ; only very rarely do individual ringed seals get lost as far as the German Baltic coasts. There are also two notable freshwater subspecies: P. h. ladogensis in Lake Ladoga , Russia , and P. h. saimensis in Lake Saimaa, Finland .
Way of life
Ringed seals do not form colonies, but live as solitary animals; occasionally one sees them moving through the sea in loose groups. They are very well adapted to a year-round life in the Arctic Ocean, as they can still keep ice holes open with the claws of their front fins even when the surrounding ice layer is more than two meters thick. However, they always expand existing holes and do not create their own.
The diet consists of crustaceans , smaller fish and krill . There is significantly less consumption during labor and coat change times. Ringed seals usually stay underwater for two to five minutes, but if necessary they can dive 45 minutes and up to 90 meters without having to breathe. Not only do they benefit from a high percentage of red blood cells, but also the ability to adjust blood circulation and reduce the heart rate from normally 80 to 90 beats per minute to 10 to 20 beats.
By counting the dentin annual rings of the teeth, the maximum life expectancy was determined to be 43 years. The sexual maturity occurs five to ten years. From the age of ten the female is fully fertile . The mating season is in April. The implantation of the fertilized egg occurs only about 80 days later, and the subsequent gestation period is nine months. The female gives birth to one young at a time. The birth usually takes place in mid-March to early April (in the case of the freshwater subspecies in May) on firm ice in birth caves made of snow. To do this, the expectant mother looks for natural hollows and digs a suitable cave herself in a snowdrift above a breathing hole in the ice. The baby seal, cared for only by its mother, is suckled for five to eight weeks and very soon learns to dive, as this is the only way it can escape the polar bears and arctic foxes that are chasing after it . As soon as the ice breaks - at the end of June, at the beginning of July - the mother leaves her cub to itself.
Subspecies
Arctic Ringed Seal ( P. h. Hispida )
It is estimated that around seven million of these animals live in the Arctic Ocean - mostly in the immediate vicinity of open water and on floating pack ice, where crevices and polynyas offer them escape routes and openings to breathe and they can escape their natural predators.
Among the enemies of ringed seals include polar bear , arctic fox , walrus , Arctic wolf , wolverine , sharks , several species of gulls , dogs and not least the man. For example, about 26 percent of the young are hunted by arctic foxes in their burrows. Polar bears, for whom the ringed seal is the most important prey animal, eat an average of one seal per week; however, the polar bear does not pose a threat to the ringed seal population either. The ringed seals provide the Eskimos with skin, meat and maktaaq (bacon) as traditional game . Ringed seals, on the other hand, are of no interest for commercial hunting, as they only appear individually and not in groups.
Baltic ringed seal ( P. h. Botnica )
In the 19th century some lived hundreds of thousands of ringed seals in Finland and in the Gulf of Bothnia . The stocks were brought to the brink of extinction through mass slaughter. Even after the ringed seals were placed under protection, the population continued to decline. The cause was identified as the discharge of poison into the Baltic Sea, which made the seals sterile. The current population is estimated at 7,000 to 10,000 animals. The problem of poison discharges persists, especially near Russian coasts; on the Finnish and Swedish coasts, stocks are showing the first signs of recovery.
Ladoga ringed seal ( P. h. Ladogensis )
The ringed seals of Lake Ladoga are particularly endangered by the discharge of poison and fishing nets in which they get caught again and again. They have been under unrestricted protection since the 1980s, but since the local inland fishermen view the seals as competitors in fishing, there is an unreported number of illegal killings. Nevertheless, 5000 ringed seals are now living in Lake Ladoga again.
Saimaa ringed seal ( P. h. Saimensis )
→ Main article: Saimaa ringed seal
The ringed seals of Lake Saimaa ( called Norppa in Finland ) were placed under protection in 1955 and thus saved from extinction; through the discharge of mercury and hunting, this subspecies was reduced to 180 individuals. After the establishment of two national parks in the 1980s and increased conservation efforts, the population is currently growing by around 2% per year. It now stands at 270 animals and is still considered extremely vulnerable.
Threat and protection
While the polar sea ringed seal is currently not endangered in its population, the other subspecies are worse off. The threat of warming in the Baltic Sea will cause the shelf ice duration to shrink over the next few decades, and it is still unclear to what extent the seal population in the Baltic Sea will be affected.
In March 2008, the WWF warned of a mass death of baby seals in the Baltic Sea. “Since the winter of 2007/08 is the least ice-poor in 300 years on the Baltic Sea, the newborn ringed seals have to go into the water earlier than usual, where without the protective layer of fat they are threatened with death from starvation and freezing. How many of the 1500 young animals will survive the winter is unclear ”.
The Saimaa ringed seals are also endangered by warm winters. If the snow melts too early, the cubs can be buried in their collapsing snow caves or they can lose protection from predators before they have learned to swim and dive.
The World Conservation Union IUCN sees the world population of this species - but named as “Pusa hispida” - not endangered (“Least Concern”); However, more recent assessments are said to have been made, according to which the Baltic Sea and Ladoga ringed seals are to be regarded as endangered and the Saimaa ringed seal as threatened.
The Federal Republic of Germany does not have the species in its national red list. However, there is one entry at the state level for the state of Hamburg; but it dates back to 1985.
In the Bern Convention , the ringed seal “Pusa hispida” is designated under Appendix III as a wild animal in need of protection, which, however, may be hunted or used in exceptional cases. The Ladoga and Saimaa ringed seals, on the other hand, are listed in Appendix II as strictly protected wild animals.
At the level of the European Union, protective measures are taken for some subspecies with the Fauna-Flora-Habitat Directive No. 92/43 / EEC. The Saimaa ringed seal is listed in appendix IV and II, whereby it is declared as strictly protected animal species of Community interest, for whose conservation protected areas must be designated. In addition, this protective measure is to be regarded as a priority. The Baltic ringed seal is also in Appendix II, which is intended to secure its protected areas. However, it is not classified as a priority species.
The Federal Republic of Germany lists the Ladoga ringed seal as specially protected by the Federal Nature Conservation Act and the Federal Species Protection Ordinance and the Saimaa ringed seal as strictly protected by the Federal Nature Conservation Act.
literature
- Ronald M. Nowak: Walker's Mammals of the World . 6th edition. Johns Hopkins University Press, Baltimore 1999, ISBN 0-8018-5789-9 (English).
- Seals of the Northwest Territories . Ed. Department of Resources, Wildlife and Economic Development, Yellowknife (1st edition 1992)
Individual evidence
- ^ Seal pups drama in the Baltic Sea , WWF press release of March 10, 2008.
- ↑ Helsingin Sanomat : Lauha sää uhkaa saimaannorpan poikasia, March 18, 2007 ( mild weather threatens the young of the Saimaa ringed seal )
- ↑ Online query of the ringed seal in the Red List of Endangered Animals in Germany and its federal states. science4you, accessed February 4, 2010 .
- ↑ Bern Convention. Council of Europe, accessed February 4, 2010 (Appendices I-IV).
- ↑ Directive 92/43 / EEC (Fauna-Flora-Habitat Directive) in the consolidated version of January 1, 2007 , accessed on February 4, 2010
- ↑ Appendix 1 of the Federal Species Protection Ordinance
Web links
- Pusa hispida in endangered species red list of the IUCN 2009. Posted by: Kovacs, K. Lowry, L. & Härkönen, T. (IUCN SSC Pinniped Specialist Group), 2008. Retrieved on 4 February, 2010.
- WISIA Tracing Service for Endangered Species. In: WISIA Online. German Federal Agency for Nature Conservation, accessed on February 4, 2010 .