Saimaa ringed seal

The Saimaa ringed seal (Pusa saimensis, Finnish: saimaannorppa) is a species of seal. It is among the most endangered seals in the world, having a total population of only about 500 individuals. The population is descended from ringed seals that were separated from the rest when the land rose after the last ice age. This seal, along with the Baikal seal, the Ladoga seal, and the Ungava seal, is one of the few living freshwater seals.

The Saimaa ringed seal was previously considered a subspecies of ringed seal called Pusa hispida saimensis.

Distribution

Habitat

thumb|The Saimaa ringed seal swimming in [[Rantasalmi in September 2024]]

The Saimaa ringed seal is endemic to their habitat in Lake Saimaa, Finland. The lake lies between the cities of Lappeenranta in the south and Joensuu in the north, spanning an oval of approximately . It consists of numerous larger basins connected by narrower glacier-carved channels, and its geography is maze-like, having 13,710 islands, an approximate coastline length of , and a surface area of .

It is relatively shallow, having an average depth of  and a maximum depth of . The fish consumed consist primarily of small schooling fish averaging 8.6 cm in length and up to 21 cm in length, The pups' diet varies markedly from the adults' in that their diet consists primarily of perch and roach found in the shallow water where they spend most of their time in their earlier months, while the adults consume more vendace and smelt.

It was believed for a long time that the Saimaa ringed seal was competing with the commercial and recreational fishing industries and there were bounties paid on them until the 1940s.

Saimaa ringed seals have two kinds of lairs or dens; they have a haul-out lair where no breeding takes place, and the breeding lair. Breeding lairs are located closer to the shore than haul-out dens.

Diving

Diving is an important behaviour for aquatic mammals as it is something they rely on for behaviours such as foraging and travelling. The duration of their dives increases from spring to autumn, which may be a result of food availability, but it is interesting because they are one of the few landlocked seal species. Many studies have been done to observe Saimaa ringed seal diving, which was discovered to last longer than expected. Their average time for a long dive was recorded at 15 minutes and it was believed to be an aerobic resting dive.

The average dive depth ranges from 10 to 15 m; however, their maximum dive depths were limited by environmental depth.

Conservation

thumb|1986 Finnish commemorative stamp designed by [[Pirkko Vahtero to the issue "EUROPA 1986 - Nature Conservation"; drawing with a Saimaa ringed seal in binocular view]]

The Saimaa ringed seal has been protected by law in Finland since 1955; it is also listed as endangered by the United States government under the Endangered Species Act.

The threatened extinction of the Saimaa ringed seal was long the focus of a major publicity campaign by the Finnish Association for Nature Conservation, and a poster depicting the seal has become a Finnish icon of nature conservation in general.

In 1983, the population was between 100 and 150 seals. In 2005, it was about 270, but as a result of two unfavourable breeding seasons, 2006 and 2007, the number dropped down to 260. In 2013, the population was estimated at just over 300 and the population numbers were slowly growing. The number of breeding-aged females was 87. It was thought that the immediate threat of extinction would be alleviated if the population grew to over 400 individuals.

In spring 2016, 79 pups were found, four of which were dead.

In order to protect the Saimaa ringed seal, there are voluntary fisheries restrictions in a part of their living areas. The most important form of restriction is a ban on fishing nets from April 15 till the end of June in about 15% of the lake; nearly all fishing is recreational. Bycatch mortality has, however, remained high with estimated mortality of 20–30 seals annually, most of them pups of the same year.

In 2010 the European Union required Finland to do more to protect the seals, particularly from net fishing. To reduce the by-catch mortality of seals aged over one year, the use of certain fishing methods has been banned since 2011, which included strong mesh nets, large fish traps, and fish-baited hooks, in the main part of the Saimaa ringed seal's habitat.

In 2016, one Act and Mutual Agreement between authorities and owners of fishing waters replaced two earlier acts. The fishing co-operatives get 1.7 euros per hectare to ensure that fishing limitations are followed. Net fishing (except of vendace nets) is forbidden between mid-April and end of June in certain areas, which have been drawn at a 5 km radius from nesting sites.

Breeding success of Saimaa ringed seals depends on sufficient ice and snow cover. The loss of snow and ice caused by ongoing climate change poses a direct threat to them. Human-made snowdrifts have proved to be successful in improving seals' breeding success during winters with poor snow conditions. Snowdrifts were tested for three winters, and from 2014, they have been used regularly. In addition, artificial lairs are also in development for winters when there is no snow on the ice due to climate change. Conservation experts expect to produce 100 of these boxes for dispersal and maintenance by the local citizenry.

The Saimaa ringed seal lives mainly in two Finnish national parks, Kolovesi and Linnansaari. Strays have been seen in a much larger area, including Savonlinna centre.

Norppalive

Norppalive (literally "Ringed Seal Live") is a live webcast of the Saimaa ringed seal produced by WWF. It shows a live image of a place that is occasionally visited by a Saimaa ringed seal. One of the most well-known ringed seals found in live broadcasts is Pullervo, who has become Finland's most famous Saimaa ringed seal.

References

External links

US National Marine Fisheries Service Saimaa seal web page
Norppalive, WWF Finland Saimaa ringed seal webcam (live in April 2024; in Finnish)