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.
The only exclusively freshwater seal species is the Baikal seal, locally named nerpa ( нерпа ). [1] The Baikal seal has inhabited Lake Baikal for roughly two million years, the closest relative to it being the Arctic ringed seal whence it has likely descended. [2] The manner by which the baikal seal reached Lake Baikal is still not fully understood, theories include their entrance into the lake via travel up the Yenisei River or perhaps via large lakes which existed in Siberia during the Pleistocene.
While the Baikal Seal is the only unique species pinniped to live in a purely freshwater environment for the duration of their lives, various species of typically saltwater seals may occasionally frequent freshwater environments or include isolated populations in near coastal freshwater lakes.
Two subspecies of Ringed seals live solely in freshwater lakes. The Ladoga seal inhabits Lake Ladoga in the Leningrad Oblast and Republic of Karelia. The seals became isolated in Lake Ladoga from the Baltic ringed seal (Pusa hispida botnica) as early as 8,800 BP due to the gradual isostatic rebound of the region following the end of the Weichselian Glaciation. [3] Modern populations of the Ladoga seal only stand at around 2,000 to 3,000 individuals, a significant decline from the estimated 20,000 seals which inhabited Lake Ladoga before hunting decreased the population. [4] [5]
The Saimaa ringed seal is closely related to the Ladoga ringed seal, the populations likely became isolated from the Baltic ringed seal around the same time. The Saimaa ringed seal lives solely within Saimaa, a large freshwater lake in the regions of South Savo, South Karelia, and North Karelia in Finland. Current estimates place the size of the population at between 420 and 430 individuals, an increase from the roughly 100 to 150 individuals present in 1983. [6] [7]
Harbor seals (common seals) are also known to enter estuaries and freshwater rivers in pursuit of their prey. [8] In addition a unique subspecies in Quebec and an isolated population of harbor seals in Alaska are known to inhabit freshwater lakes for the duration of the year. The Ungava seal (Phoca vitulina mellonae) is a subspecies of the harbor seal which lives solely within the landlocked and fresh water environment of Lacs des Loups Marins, Petit Lac de Loups Marins, and Lac Bourdel in northern Quebec. [9] This subspecies of harbor seal is currently listed as endangered by the IUCN due to the current population being as low as only 100 to 300 individuals. [10] [11]
Another freshwater isolated population of harbor seals exists in Iliamna Lake, Alaska. [12] These seals represent an isolated population of the Pacific Harbor Seal (Phoca vitulina richardsi), the survival of this population is due to the existence of a number of islands within the lake for the seals to pup on, away from potential predators on the shoreline of the lake. [13] The diet of these seals is primarily composed of Salmonids in the summer with the diet of these seals remaining obscure throughout the remainder of the year. [14] This population has been recorded at around 400 individuals, though following particularly harsh winters in the 1970s, the population is thought to have dropped to as low as only 50 individuals. [13] [15] The harbor seals of Iliamna Lake were first noted in historic records in the 1800s, thus they have been present there for a minimum of 200 years. The oldest possible date for their arrival in the lake is thought to be approximately 5,000 BP, prior to this the lake would have been less accessible due to the outflowing river flowing steeply down a glacial moraine. Any date older than between 12,600 and 16,000 BP can be entirely precluded because of the existence of glacial ice where the lake now exists. [16]
California sea lions and Steller sea lions can also live in fresh water for extended periods of time, such as near the Bonneville Dam, nearly 240 kilometres (150 mi) up the Columbia River and at the bottom of the Willamette Falls on the Willamette River. [17] [18] In 2004, a healthy sea lion was found sitting on a road in Merced County, California, almost a hundred miles upstream from the San Francisco Bay and half a mile from the San Joaquin River. [19]
The earless seals, phocids, or true seals are one of the three main groups of mammals within the seal lineage, Pinnipedia. All true seals are members of the family Phocidae. They are sometimes called crawling seals to distinguish them from the fur seals and sea lions of the family Otariidae. Seals live in the oceans of both hemispheres and, with the exception of the more tropical monk seals, are mostly confined to polar, subpolar, and temperate climates. The Baikal seal is the only species of exclusively freshwater seal.
Lake Ladoga is a freshwater lake located in the Republic of Karelia and Leningrad Oblast in northwestern Russia, in the vicinity of Saint Petersburg.
Pinnipeds, commonly known as seals, are a widely distributed and diverse clade of carnivorous, fin-footed, semi-aquatic, and 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 clade Caniformia of the order Carnivora; their closest living relatives are musteloids, having diverged about 50 million years ago.
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.
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.
Iliamna Lake or Lake Iliamna is a lake in southwest Alaska, at the north end of the Alaska Peninsula, between Kvichak Bay and Cook Inlet, about 100 miles (160 km) west of Seldovia, Alaska. It shares a name with the Iliamna River, which flows into it, and the nearby community of Iliamna, Alaska.
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.
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.
The Saimaa ringed seal is a subspecies and glacial relict of ringed seal. They are among the most endangered seals in the world, having a total population of only about 400 individuals. The only existing population of these seals is found in Lake Saimaa, Finland. 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. 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.
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 longfin smelt is a smelt that is found in several estuaries and lakes along the northern Pacific coast of North America.
The Ladoga ringed seal is a freshwater subspecies of the ringed seal found entirely in Lake Ladoga in northwestern Russia. The Ladoga ringed seal 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.
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.
The Ungava seal is a subspecies of harbor seal, endemic to a small series of freshwater lakes in the Ungava Peninsula, located in northern Quebec. It is noted for being one of the few examples of freshwater seals. It was thought that fewer than 100 individuals remained in 2020. The Ungava seal is currently classified by the International Union for Conservation of Nature as endangered.
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.
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.
Lacs des Loups Marins is a lake in the north of the province of Quebec in Canada. It is located about 150 km east of Hudson Bay and about 20 km northeast of Lac à l'Eau Claire.
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.