Saimaa ringed seal

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Saimaa ringed seal
Prepared Saimaa ringed seal in the Natural History Museum in Helsinki

Prepared Saimaa ringed seal in the Natural History Museum in Helsinki

Systematics
Subordination : Canine (Caniformia)
without rank: Seals (Pinnipedia)
Family : Dog seals (Phocidae)
Genre : Pusa
Type : Ringed Seal ( Pusa hispida )
Subspecies : Saimaa ringed seal
Scientific name
Pusa hispida saimensis
Nordquist , 1899

The Saimaa ringed seal ( Pusa hispida saimensis , synonym : Phoca hispida saimensis ) (Finnish saimaannorppa ) is a subspecies of the ringed seal . With a population of only about 400 animals, it is one of the most threatened seals in the world.

Appearance

The Saimaa ringed seal is the darkest of all ringed seals and is slightly smaller than the Baltic ringed seal . Adults are between 85 and 160 cm long and weigh between 40 and 90 kg, with the males being slightly larger than the females. They are dark gray and have gray-black spots surrounded by white rings. Their lower surface is light gray. Young animals are born with a gray lanugo , which is later replaced by a darker coat.

Distribution area

distribution and habitat

The Saimaa ringed seal, along with the Ladoga ringed seal, is one of the two subspecies of the ringed seal that only occurs in freshwater . Their habitat is in the subpolar zone in the eponymous Saimaa lake system of eastern Finland , which is divided into numerous smaller lakes that are connected by water arms. The lake system covers an area of ​​4,460 km², includes around 13,710 islands and peninsulas and has a coastline of around 15,000 km. The lakes are 17 m deep on average, with the deepest point being 82 m. The main areas where the Saimaa ringed seals give birth and raise their young are the two national parks, Linnansaari and Kolovesi . Since the species is more isolated, it has no natural enemies with the exception of humans. Experts estimate that under natural circumstances there could be room for up to 6,000 seals in this area.

Way of life

The gender distribution of the Saimaa ringed seals is 1: 1. The animals become sexually mature at around 3 to 7 years of age, their life expectancy is a little over 20 years.

The pregnancy lasts eleven months. The female hollowed out a shelter in snowdrifts on the ice and made another hole in the ice through which she could enter the lake water. The young are born in late February or early March. In a long-term observation by the National Veterinary and Food Research Institute (EELA) from 1980 to 1999, the newborn seals weighed an average of 4.7 kg, with the lightest boy weighing 3.3 kg and the heaviest 7.3 kg. They are around 55 to 65 cm tall at birth. In 2004 65 young animals were born, whereby this was a record result due to a snowy winter. On average, 50 to 60 seals are born each year. They spend the first few weeks in the shelter and only feed on breast milk. As soon as the weather becomes milder, the boys learn to swim and dive. In the summer they are finally weaned.

Population development

It is estimated that there were fewer than 1,000 Saimaa ringed seals as early as 1893, although exact numbers are unknown. A large decline was particularly evident during the 1950s when the seal was hunted as a pest, which is why it was placed under protection in 1955. Nevertheless, the number of stocks continued to decline due to modern fishing methods and environmental toxins such as mercury, which is why further regulations were issued to protect the animals.

The development of the Saimaa ringed seal has been closely monitored since 1980. In 1983, Helle estimated the number at that time to be 100 to 150 animals. Sipilä and Hyvärinen gave a number of 150 to 160 seals in 1988, while Helle assumed 160 to 180 animals for the same year. Sipilä only came to this number in 1991. Of these, around 38 to 40 females were likely to have been of reproductive age, and according to Sipilä around 18 to 26 young were born every year. For the first time in 1995 the population was estimated at over 200 seals and in winter 2011 310 individuals were already counted. The Finnish WWF assumed a population of 400 animals in 2018.

area Winter 1984 Winter 1990 Winter 1995 Winter 2000
Pyhäselkä 13 13 8-10 3-5
Orivesi 9-10 13-15 11-15 10-14
Pyyvesi - Enonvesi 6-7 5-8 6-8 15-18
Joutenvesi 8-10 13-18 13-18 20-30
Kolovesi 5-6 13-16 13-16 22-28
Haukivesi 32-37 41-55 44-54 48-58
Pihlajavesi 14-19 35-40 40-46 55-65
Tolvanselkä - Katosselkä 4-5 13-19 15-25 16-24
Lietvesi 8-9 13-16 8-12 7-10
Luonteri 1-2 2 2 2
Petranselkä 9-12 3-4 4-7 11-15
Ilkonselkä 4th 4th 3-4 2-3
Saimaa Lake District 113-134 164-210 167-217 211-272

Danger

During the long-term observation by EELA, found carcasses (in total 182 in the period 1977-2000) were examined and it was established that the main cause of death of the Saimaa ringed seal is the fishing nets in which the animals get caught and suffocate or drown. 53.3% of the animals died in this way, followed by a child mortality rate of 39%. Only 5% of the seals died of natural causes.

Of the 550 young animals observed during the same period, 12.9% died at birth or before they were two weeks old. Reasons for this include the rise or fall of the water level and mild winters, which means that the seals' hiding places often collapse too early and bury the young. In 1982, 1983, 1988, 1989 and 1996 31% of the baby seals observed were found dead in their burrows, while in stable years it was only 8.4%.

Protective measures

5 Finnish marks

The Saimaa ringed seal has been under protection since 1955 in order to be saved from extinction. The IUCN leads the Saimaa ringed seal since January 2009 as critically endangered (dt. In danger of extinction ). In the Bern Convention , the Saimaa ringed seal is listed in Appendix II ( strictly protected ).

In Finland, two national parks (Linnansaari and Kolovesi) have been established for the protection of the seals, with additional protection zones. It is not allowed to build Mökkis and houses in their vicinity . The use of motor boats is also severely restricted, and in spring certain deep bays are not even allowed to be used with paddle boats. Fishing is also restricted in the Saimaa lake system, so the use of bait hooks and traps was banned and compensation was paid to professional fishermen who refrain from laying nets during the summer months. Tero Sipilä suspects that a complete abandonment of fishing nets during the summer months could ensure the survival of 10 to 15 more young animals per year.

Artificial water level regulation by the nearby power station is now only planned in winter with the seals in mind. A major problem currently is water pollution from chlorinated hydrocarbons and increased boat traffic and tourism.

literature

Web links

Commons : Pusa hispida saimensis  - Collection of images, videos and audio files

Individual evidence

  1. ↑ a b WWF Finland: Saimaa Ringed Seal (en), October 23, 2018, accessed on September 17, 2019
  2. ^ E. Kuusisto: Basins and Balances. In: Saimaa a living lake. 1999, Tammi, Helsinki, pp. 21-39
  3. ↑ a b Helsinki Times: Saimaa's seals on the brink of extinction. Issue 13, 2009
  4. ↑ Eero Helle, Heikki Hyvärinen, H. Pyysalo, K. Wickström: Levels of Organochlorine Compounds in an Inland Seal Population in Eastern Finland. 1983, Mar. Pollut. Bull. 14: 256-260.
  5. ↑ Tero Sipilä, Heikki Hyvärinen: Status and biology of Saimaa (Phoca hispida saimensis) and Ladoga (Phoca hispida ladogensis) ringed seals. In: M.-P. Heide-Jorgensen, C. Lydersen (Ed.): Ringed seals in the North Atlantic. 1998, NAMMCO, Sci. Publ. 1: 83-99
  6. ↑ Tero Sipilä: Saimaanhyljealueiden suojelutavoitteet. In: WWF Suom. Rah. Rap. N: o 5. 1991, WWF, Helsinki.
  7. ↑ eduskunta .fi: Saimaannorpan suojelu ja luontodirektiivin tayttyminen
  8. ↑ Bern Convention, Appendix 2: Phoca hispida saimensis