Saimaa ringed seal

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Saimaa ringed seal
Pusa hispida saimensis ca 1956.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Clade: Pinnipedia
Family: Phocidae
Genus: Pusa
Species:
Subspecies:
P. h. saimensis
Trinomial name
Pusa hispida saimensis
(Nordquist, 1899)
Phoca Hispida Saimensis Distribution.PNG
Synonyms
Phoca hispida saimensis

The Saimaa ringed seal (Pusa hispida saimensis, Finnish: Saimaannorppa) is a subspecies and glacial relict of ringed seal (Pusa hispida). [2] They are among the most endangered seals in the world, having a total population of only about 400 individuals. [3] The only existing population of these seals is found in Lake Saimaa, Finland (hence the name). They have lived in complete isolation from other ringed seal species for around 9,500 years and have diverged into a morphologically and ecologically different subspecies of ringed seal. [4] 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 Ladoga seal and the Baikal seal, is one of the few living freshwater seals.

Contents

Distribution

Habitat

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 180 by 140 km (112 by 87 mi). 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 14,850 kilometres (9,230 mi), and a surface area of 4,279 km2 (1,652 sq mi). [5] It is relatively shallow, having an average depth of 17 metres (56 ft) [6] and a maximum depth of 85.8 m (281 ft). [5] The freshwater lake freezes over between the months of November and May, leaving the seals both an ice habitat and an open water habitat. [7] During summer months when the ice is melted, these islands provide ample space for the seals to molt and breed.

Range

Saimaa ringed seals are named as such due to their only habitat being Lake Saimaa, Finland. Thus, their range is restricted only to the waters of Lake Saimaa and its surrounding banks.

Appearance

A stuffed Saimaa ringed seal at the Finnish Museum of Natural History. Pusa hispida saimensis at the Finnish Museum of Natural History 20110824.jpg
A stuffed Saimaa ringed seal at the Finnish Museum of Natural History.

An adult Saimaa ringed seal is between 85 and 160 centimetres (2.79 and 5.25 ft) in length and weighs between 50 and 90 kilograms (110 and 200 lb); males usually being larger than females. They are coloured dark gray, with a gray-black dorsal with circular white rings. The bottom of the seal is light gray. The Saimaa ringed seal is darker in color than any other ringed seal.

Diet

The Saimaa ringed seal does not have an incredibly varied diet. They are generalist feeders and eat exclusively fish. [8] The fish consumed consist primarily of small schooling fish averaging 8.6 cm in length and up to 21 cm in length, [8] while it has been shown that the pups eat slightly smaller fish than the average. [8] The majority of their diet consists of vendace, smelt, perch, and roach. [9] The pups’ diet varies markedly from the adults in that their diet consists primarily of perch and roach found in the shallow water [10] 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. [8] However it has recently been proven that the Saimaa ringed seal has minimal to no effect on the fishing industry. They do not prey on the local endangered salmon species (Salmo salar m. Sebago, S. trutta m. lacustris, and Salvelinus alpines). [8] Although they do prey on the valuable vendace population, the proportion of the vendace population to the amount consumed by the seals indicates that they do not compete with the local fishing industries. [8]

Behavior

Reproduction

Saimaa ringed seals become mature between the ages of 4 and 6. Their pregnancy rate is between 80 and 95 percent. Ringed seals' gestation lasts 11 months. Their pups are between 55 and 65 centimetres (1.80 and 2.13 ft), and 4 to 5 kilograms (8.8 to 11.0 lb) at birth. The Saimaa ringed seal's longevity is just over 20 years.

A study conducted from 1980-84 revealed that Saimaa ringed seals make burrowed dens close to the shore and they reproduce once a year due to their longevity. [11]

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. [12]

Diving

Diving is an important behavior for aquatic mammals as it is something they rely on for behaviors 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. [13] 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. [7]

The average dive depth ranges from 10 to 15 m; however, their maximum dive depths were limited by environmental depth. [7] The Saimaa ringed seal has also been observed to have seasonal hauling-out patterns. In May and June, when the seals are molting, they are observed to haul out both day and night; however, in late summer they are observed to haul out only at night. [13]

The Saimaa ringed seal is able to complete its dives and navigate in its environment due to its highly developed vibrissae, also known as whiskers. Using their vibrissae, they are able to detect sound and pressure waves in their otherwise dark environment. [14]

Conservation

1986 Finnish commemorative stamp designed by Pirkko Vahtero to the issue "EUROPA 1986 - Nature Conservation"; drawing with a Saimaa ringed seal in binocular view FIN 1986 MiNr0985 pm B002.jpg
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 U.S. 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 unfavorable 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 in a slight growth. The number of breeding-aged females was 87. [15] 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. [16]

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. [17] 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. [18]

In 2016, one Act and Mutual Agreement between authorities and owners of fishing waters replaced earlier two 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 5 km radius from nesting sites. [19]

Breeding success of Saimaa ringed seal depends on sufficient ice and snow cover. The loss of snow and ice caused by the 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. [20] Snowdrifts were tested for three winters, and from 2014, they have been used regularly. [21] [22] In addition, artificial lairs are also in development for winters when there is no snow on ice due to climate change. [23] Conservation experts expect to produce 100 of these boxes for dispersal and maintenance by the local citizenry. [23]

Recent estimates place the current population at between 420 and 430 individuals. [24]

The Saimaa ringed seal lives mainly in two Finnish national parks, Kolovesi and Linnansaari. [25] 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. [26] [27] It shows a live image of a place that is occasionally visited by a Saimaa ringed seal. [26] The purpose of Norppalive is to raise awareness of the Saimaa ringed seal. [28] In 2016, Norppalive gathered at its best 180,000 simultaneous viewers [26] and a total of more than two million viewers. [28] One of the most well-known ringed seals found in live broadcasts is Pullervo, which has gained the status of Finland's most famous Saimaa ringed seal. [26] [29]

See also

Related Research Articles

<span class="mw-page-title-main">Pinniped</span> Taxonomic group of semi-aquatic mammals

Pinnipeds, commonly known as seals, are a widely distributed and diverse clade of carnivorous, fin-footed, semiaquatic, mostly marine mammals. They comprise the extant families Odobenidae, Otariidae, and Phocidae, with 34 extant species and more than 50 extinct species described from fossils. While seals were historically thought to have descended from two ancestral lines, molecular evidence supports them as a monophyletic lineage. Pinnipeds belong to the suborder Caniformia of the order Carnivora; their closest living relatives are musteloids, having diverged about 50 million years ago.

<span class="mw-page-title-main">Baikal seal</span> Species of freshwater seal

The Baikal seal, Lake Baikal seal or nerpa is a species of earless seal endemic to Lake Baikal in Siberia, Russia. Like the Caspian seal, it is related to the Arctic ringed seal. The Baikal seal is one of the smallest true seals and the only exclusively freshwater pinniped species. A subpopulation of inland harbour seals living in the Hudson Bay region of Quebec, Canada,, as well as the Saimaa ringed seal and the Ladoga seal, are also found in fresh water, but these seals are part of species that also have marine populations.

<span class="mw-page-title-main">Ringed seal</span> Species of carnivore

The ringed seal is an earless seal inhabiting the Arctic and sub-Arctic regions. The ringed seal is a relatively small seal, rarely greater than 1.5 m in length, with a distinctive patterning of dark spots surrounded by light gray rings, hence its common name. It is the most abundant and wide-ranging ice seal in the Northern Hemisphere, ranging throughout the Arctic Ocean, into the Bering Sea and Okhotsk Sea as far south as the northern coast of Japan in the Pacific and throughout the North Atlantic coasts of Greenland and Scandinavia as far south as Newfoundland, and including two freshwater subspecies in northern Europe. Ringed seals are one of the primary prey of polar bears and killer whales, and have long been a component of the diet of indigenous people of the Arctic.

<span class="mw-page-title-main">Saimaa</span> Largest lake in Finland and the fourth largest in Europe

Saimaa is a lake located in the Finnish Lakeland area in southeastern Finland. At approximately 4,279 square kilometres (1,652 sq mi), it is the largest lake in Finland, and the fourth-largest natural freshwater lake in Europe.

<span class="mw-page-title-main">Bearded seal</span> Species of Arctic dwelling marine mammal

The bearded seal, also called the square flipper seal, is a medium-sized pinniped that is found in and near to the Arctic Ocean. It gets its generic name from two Greek words that refer to its heavy jaw. The other part of its Linnaean name means bearded and refers to its most characteristic feature, the conspicuous and very abundant whiskers. When dry, these whiskers curl very elegantly, giving the bearded seal a "raffish" look.

<span class="mw-page-title-main">Harp seal</span> Species of mammal

The harp seal, also known as Saddleback Seal or Greenland Seal, is a species of earless seal, or true seal, native to the northernmost Atlantic Ocean and Arctic Ocean. Originally in the genus Phoca with a number of other species, it was reclassified into the monotypic genus Pagophilus in 1844. In Greek, its scientific name translates to "ice-lover from Greenland," and its taxonomic synonym, Phoca groenlandica translates to "Greenlandic seal." This is the only species in the genus Pagophilus.

<span class="mw-page-title-main">Hawaiian monk seal</span> Species of carnivore

The Hawaiian monk seal is an endangered species of earless seal in the family Phocidae that is endemic to the Hawaiian Islands.

<i>Phoca</i> Genus of carnivores

Phoca is a genus of the earless seals, within the family Phocidae. It now contains just two species, the common seal and the spotted seal. Several species formerly listed under this genus have been split into the genera Pusa, Pagophilus, and Histriophoca. Until recently, Phoca largha has been considered a subspecies of Phoca vitulina but now is considered its own species. For this reason, the fossil history of the genus is unclear, and it has formerly been used as wastebasket taxon for a number of fossils of uncertain affinity.

<span class="mw-page-title-main">Caspian seal</span> Species of seal endemic to the Caspian Sea

The Caspian seal is one of the smallest members of the earless seal family and unique in that it is found exclusively in the brackish Caspian Sea. It lives along the shorelines, but also on the many rocky islands and floating blocks of ice that dot the Caspian Sea. In winter and cooler parts of the spring and autumn season, it populates the northern Caspian coastline. As the ice melts in the summer and warmer parts of the spring and autumn season, it also occurs in the deltas of the Volga and Ural Rivers, as well as the southern latitudes of the Caspian where the water is cooler due to greater depth.

<span class="mw-page-title-main">Ribbon seal</span> Species of mammal

The ribbon seal is a medium-sized pinniped from the true seal family (Phocidae). A seasonally ice-bound species, it is found in the Arctic and Subarctic regions of the North Pacific Ocean, notably in the Bering Sea and Sea of Okhotsk. It is distinguished by its striking coloration, with two wide white strips and two white circles against dark brown or black fur.

<span class="mw-page-title-main">Spotted seal</span> Species of mammal

The spotted seal, also known as the larga seal or largha seal, is a member of the family Phocidae, and is considered a "true seal". It inhabits ice floes and waters of the north Pacific Ocean and adjacent seas. It is primarily found along the continental shelf of the Beaufort, Chukchi, Bering and Okhotsk Seas and south to the northern Yellow Sea and it migrates south as far as northern Huanghai and the western Sea of Japan. It is also found in Alaska from the southeastern Bristol Bay to Demarcation Point during the ice-free seasons of summer and autumn when spotted seals mate and have pups. Smaller numbers are found in the Beaufort Sea. It is sometimes mistaken for the harbor seal to which it is closely related and spotted seals and harbor seals often mingle together in areas where their habitats overlap.

The Ladoga ringed seal is a freshwater subspecies of the ringed seal found entirely in Lake Ladoga in northwestern Russia. This pinniped was isolated in freshwater lakes and separated from the Arctic ringed seal as a result of the isostatic rebound of the region following the end of the Weichselian Glaciation.

<i>Pusa</i> Genus of mammals

Pusa is a genus of the earless seals, within the family Phocidae. The three species of this genus were split from the genus Phoca, and some sources still give Phoca as an acceptable synonym for Pusa.

<span class="mw-page-title-main">Hauling-out</span> Marine mammal behaviour

Hauling-out is a behaviour associated with pinnipeds temporarily leaving the water. Hauling-out typically occurs between periods of foraging activity. Rather than remain in the water, pinnipeds haul-out onto land or sea-ice for reasons such as reproduction and rest. Hauling-out is necessary in seals for mating and giving birth. Other benefits of hauling-out may include predator avoidance, thermoregulation, social activity, parasite reduction and rest.

<span class="mw-page-title-main">Pagophily</span> Preference or dependence on water ice

Pagophily or pagophilia is the preference or dependence on water ice for some or all activities and functions. The term Pagophila is derived from the Ancient Greek pagos meaning "sea-ice", and philos meaning "-loving".

<span class="mw-page-title-main">Freshwater seal</span> Seal species which live primarily in freshwater lakes

Freshwater seals are pinnipeds which live in freshwater bodies. The group is paraphyletic in nature, the uniting factor being the environment in which these pinnipeds live. The vast majority of all modern seals live solely in saltwater habitats though this is likely due to the rarity of sufficiently large freshwater bodies rather than the limitation of seal biology.

<span class="mw-page-title-main">Harbor seal</span> Species of mammal

The harborseal, also known as the common seal, is a true seal found along temperate and Arctic marine coastlines of the Northern Hemisphere. The most widely distributed species of pinniped, they are found in coastal waters of the northern Atlantic and Pacific oceans, Baltic and North seas.

In biogeography and paleontology, a relict is a population or taxon of organisms that was more widespread or more diverse in the past. A relictual population is a population currently inhabiting a restricted area whose range was far wider during a previous geologic epoch. Similarly, a relictual taxon is a taxon which is the sole surviving representative of a formerly diverse group.

<span class="mw-page-title-main">Wildlife of Finland</span>

The wildlife of Finland is affected by prevailing environmental conditions. The phytogeography of Finland is shared between the Arctic, central European, and northern European provinces of the Circumboreal Region within the Boreal Kingdom. The territory of Finland can be subdivided into three ecoregions: the Scandinavian and Russian taiga, Sarmatic mixed forests, and Scandinavian montane birch forest and grasslands. Taiga covers most of Finland from northern regions of southern provinces to the north of Lapland. On the southwestern coast, south of the Helsinki-Rauma line, forests are mixed as is more typical in the Baltic region. In the extreme north of Finland, near the tree line and Arctic Ocean, montane birch forests are common.

<span class="mw-page-title-main">Arctic ringed seal</span> Subspecies of carnivore

The Arctic ringed seal is a subspecies of ringed seals. Arctic ringed seals inhabit the Arctic Ocean, and are the most abundant and wide-ranging seal in the Northern Hemisphere. The ringed seal species is the smallest true seal, and gets its name from a distinctive patterning of light spots on dark grey colored fur. The ringed seal is commonly preyed upon by Polar bears, Arctic foxes, and Killer whales. Population estimates and survival rates are unknown, but average life expectancy is 15-28 years. Ringed seals have long been a component of the diet of indigenous people of the Arctic. Arctic ringed seals have been listed as threatened on the Endangered Species Act since 2012, and increasingly face loss of their habitat due to shrinking ice and snow cover.

References

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  2. Vertical fatty acid profiles in blubber of a freshwater ringed seal
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  27. Norppalive – WWF
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  29. Norppagalleria – WWF (in Finnish)