Updated: July 2020
The ringed seal (Phoca (pusa) hispida) is the smallest of all living seal species and the most common species in the Arctic. Males reach a length of 1.5 m and a weight of 95 kg, and females 1.4 m and 80 kg (Bonner 1994). The ringed seal has a north circumpolar distribution and is strongly ice-adapted/associated. It is the most ice-adapted of seals and occurs throughout the Arctic Ocean, including the North Pole (Reeves 1998). The name of the ringed seal refers to the light-coloured rings on the dark grey pelt that are visible on adult animals.
The NAMMCO Scientific Committee reviewed the status of the ringed seal in 1996 (NAMMCO 1997) and initiated the compilation of papers and studies reflecting the available knowledge on the species, which became the first volume in the NAMMCO Scientific Publications series, Ringed seals in the North Atlantic, edited by Mads Peter Heide-Jørgensen and Christian Lydersen.
There are estimated to be around 5 million ringed seals (extrapolated from the density of ringed seals documented on various types of ice).
Ringed seals have a circumpolar distribution throughout the Arctic, including the North Pole and the subarctic, and also range widely into adjacent seas.
Ringed seals have been hunted by indigenous peoples for food and leather in Alaska, Canada, Greenland and Russia. There is also limited sport hunting in northern Norway.
There are both national and regional management regimes.
A hunting licence is required in Canada, Greenland and Russia, but there is no restriction on season or numbers that can be taken. Hunting is closed in Svalbard during the breeding season and there is a quota system for sport hunters in northern Norway.
At present there is little evidence of depletion, but the species is/will be challenged by the impacts of climate change, with a predicted reduction in distribution range and numbers.
In the most recent assessment (2016) the species is listed as ‘Least Concern’ on the global IUCN Red List. It is listed as ‘Vulnerable’ on the Norwegian national red list and as “Least Concern” in the Greenlandic Red List.
Scientific name: Pusa/Phoca hispida (Schreber 1775) *
Norwegian: Ringsel, snadd
English: Ringed seal, fjord seal, jar seal
*Note: the genus name has moved back and forth between Pusa and Phoca in recent decades, with the most widely used being Pusa.
Up to 45 years (Lydersen 1998)
Adult individuals reach between 1.10 and 1.60 m in length and weigh between 50 and 110 kg in winter when they are fattest (Rosing-Asvid 2010), males being somewhat larger than females (Bonner 1994). There is considerable geographical variation in size within and among areas (Reeves et al. 1992)
MIGRATION AND MOVEMENTS
Ringed seals are completely adapted to ice-covered waters and do not migrate to open water areas in the winter. However, individual seals may relocate over considerable distances (few thousand km) and substantial migrations, either north-south or inshore-offshore, have been suggested (e.g., Reeves 1998)
Ringed seals are opportunistic feeders, preying on a wide variety of fish, crustaceans and cephalopods, with polar cod being a common prey species of adults, while younger seals feed heavily on amphipods and euphausiids. There are important regional and seasonal differences in diet, reflecting habitat-specific prey availability (Kelly et al. 2010b, Kovacs 2014)
The ringed seal is the smallest of all living seal species. It is the most common seal of the Arctic and the most strongly ice-adapted/associated.
The ringed seal belongs to the family of true seals, also called phocids, which are earless seals. The name ringed seal refers to the light-coloured rings on the dark grey pelt that are visible on adult animals and prominent on the back and sides. Ringed seal pups begin shedding their fine, woolly and white lanugo (the hair of fetal and newborn seals) at about 2 months of age. It is replaced by a largely unspotted coat that is silver on the belly and dark grey on the back, the same colour as adult coats. Animals with this coat are called silver-jars, and they acquire rings on their pelage gradually with age.
The ringed seal body is fusiform in shape (i.e. tapering at both ends). In winter, when seals are the fattest, their girth can exceed 80% of the body length (Reeves et al. 1992). Their muzzle is short and their head cat-like. Males are slightly larger than females. In the spring, male’s faces appear to be much darker than those of females because of an oily secretion from glands in the facial region. At other times of the year, the sexes are difficult to distinguish.
The adults have strong, sharp fore-claws, which are used to maintain breathing holes in the fast ice.
Pups are born with a full complement of permanent adult teeth.
Ringed seals are divided into five subspecies on the basis of geographical isolation:
- Phoca hispida hispida of the Arctic Ocean (the Arctic ringed seal)
- P. hispida ochotensis of the Sea of Okhotsk and northern Japan
- P. hispida botnica of the Baltic Sea and two living in fresh water lakes
- P. hispida ladogensis of Lake Ladoga in Russia
- P. hispida saimensis of Lake Saimaa in Finland
The subspecies Phoca hispida hispida, the Arctic ringed seal, which inhabits all of the circumpolar Arctic Ocean, is the only subspecies present in the NAMMCO area and the focus of the information presented on this website.
LIFE HISTORY AND ECOLOGY
Survival rates are not well known but ringed seals are relatively long-lived and can live to be over 40 years old (McLaren 1958, Lydersen 1998). Their average life span is about 15–28 years (Kelly et al. 2010b).
Female ringed seals begin to reach sexual maturity at age 3–5, but the timing is variable and some may not mature until they are 7–8 years old, with geographic and temporal variability depending on animal condition and population structure (Reeves 1998, Sipilä & Hyvärinen 1998, Krafft et al. 2006b, Kovacs et al. 2008, Kelly et al. 2010b, Kovacs 2014). The mean age at sexual maturity for females has decreased significantly in several areas compared to earlier periods (Krafft et al. 2006b, Kovacs 2014, see also ‘Current abundance and Trends‘).
Ringed seal females usually produce a single pup each year, although this may not happen if conditions are not favourable (Kingsley and Byers 1998, Kovacs et al. 2008, Kelly et al. 2010). Reproductive success depends on many factors including prey availability, the relative stability of ice, and sufficient snow accumulation prior to the commencement of breeding so that the birth lair can be constructed (Kovacs et al. 2008).
Males mature about 2 years later than females at 5–7 years (Krafft et al. 2006b, Kelly et al. 2010b) and likely do not participate in breeding before they are between 8–10 years old (Kovacs et al. 2008).
Ringed seals can begin to moult as early as late April, with the number of moulting seals increasing in May and peaking in June. The seals spend a lot of time (up to 60%) hauled out on ice basking in the sun both just before and during moulting. This behaviour is attributed to the need to maintain an elevated skin temperature (Kelly et al. 2010ab). Feeding activity is at a minimum during the spring moult and ringed seals lose a lot of weight and are therefore thin in the summer (Ryg et al. 1990, Rosing-Asvid 2010). Consequently, they sink more easily when hunted in the early summer. In August–September, they begin to put on weight again and by December, they have returned to their maximum weight.
HABITAT AND MOVEMENTS
Ringed seals occur in areas of landfast and drifting pack ice over virtually any water depth. While they prefer areas of landfast ice for breeding, they may also breed successfully in areas of stable pack ice, such as Baffin Bay and the Greenland Sea. Unlike other northern seals such as harp and hooded seals, the ringed seal is completely adapted to ice-covered waters and does not migrate to open water areas in the winter (Reeves 1998). Instead, ringed seals are able to maintain several breathing holes in ice that may be over 2 m in thickness by using their strong sharp fore-claws and teeth to scratch through the ice. This allows them to thrive in areas where even other ice-associated seals cannot reside. During the summer, ringed seals forage in areas of pack ice or open water and may haul out on land where no ice is available.
Summer and autumn
In the summer and autumn, when land-fast ice is not available, ringed seals show considerable diversity in their distribution patterns (Kovacs 2014). Some animals remain in the general vicinity of their breeding sites while others disperse along coastlines, concentrating their time near glacier fronts. Some spend time in open water far from the coast, while others move north to the southern edge of the permanent ice (Teilmann et al. 1999, Gjertz et al. 2000, Born et al. 2002, Freitas et al. 2008a). Ringed seals are more mobile and have larger ‘home ranges’ during the open-water season than at other times of the year (Born et al. 2004).
During the fast-ice seasons, each ringed seal uses several haul-out lairs and additional breathing holes within its home range and travels between them quite regularly. A seal’s lairs are usually only a few hundred meters apart, although those used by males are spread over greater distances on average than those of females. During the reproductive season, females spend more time on average out of the water than males and both sexes shift from hauling out during the night in early spring to hauling out during day in late spring, with more time spent on the surface during the latter period (Kelly & Quakenbush 1990, Carlens et al. 2006).
It is still unclear whether ringed seals show fidelity to natal sites, or are faithful to breeding sites as adults. This may depend on the quality of the sites (predictable ice stability, sufficient snow to construct lairs, good food availability). There could also be regional and subspecies differences in site fidelity. Ringed seals show a high degree of spatial fidelity (territoriality) in the Baltic (Härkönen et al. 2008). Prime habitat for ringed seals may be used over long periods of time, but there are also reports that strongly suggest that there is considerable mobility among ringed seals in some areas (Kovacs 2014).
Ringed seals can travel significant distances, i.e. well over 1000 km (Kapel et al. 1998, Ridoux et al. 1998). However, satellite tracking studies show that individuals tagged at any one location display variable dispersal patterns, with some individuals remaining local throughout the open-water season, while others move offshore or northward to the permanent pack-ice (Teilmann et al. 1999, Gjertz et al. 2000, Born et al. 2004).
The seasonality of ice cover strongly influences ringed seal movements, as well as foraging, reproductive behaviour, and vulnerability to predation (Kelly et al. 2010b).
The diet of ringed seals has been well documented across the species’ range, especially in the marine environment (Belikov & Boltunov 1998, Lyersen 1998, Siegstad et al. 1998, Wathne et al. 2000, Holst et al. 2001, Andersen et al. 2004, Carlsen et al. 2006, Stenman and Pöyhönen 2005, Dehn et al. 2007, Agafonova et al. 2007, Labansen et al., 2007, 2011, Vincent-Chambellant 2010, Kelly et al. 2010b, Kovacs 2014 for review).
Ringed seals are opportunistic feeders and prey on a wide variety of fish and invertebrates, but strong preferences for particular types of prey are evident. Diet is thus determined by the combination of preferences and the regional and seasonal availability of various type of prey. Gadoid fishes dominate the diet at least from late autumn through the spring in many areas, with polar cod (Boreogadus saida) being the most commonly consumed species. This small fish occurs both in ice-free and ice-covered waters, especially at the ice edge, with young polar cod sometimes living in spaces within the sea ice. Other gadoid fish are also seasonally important in some areas, such as Arctic (Arctogadus glacialis) and safron (Eleginus gracilis) cod and navaga (Eleginus nawaga), as well as redfish (Sebastes sp.), capelin (Mallotus villosus), smelt (Osmerus sp.) and herring (Clupea sp.).
Invertebrates, both crustaceans and cephalopods, become more important in most areas during the open-water season. Ringed seals around Greenland live mostly in the ice-filled regions of North and East Greenland, where the bulk of the diet is polar cod and parathemisto (a kind of amphipod).
Preferred prey size
Most ringed seal prey is small and preferred prey tend to be schooling species that form dense aggregations. Fishes are usually in the 5–10 cm range and crustacean prey in the 2–6 cm range, but larger prey may be taken on occasion. Typically, ringed seals prey upon no more than 10–15 species in any one area, with 2–4 species considered as important prey.
Differences in prey composition
There seem to be age- and sex-related differences in prey composition. Adult ringed seals prefer to feed on pelagic schooling fish in most areas, while younger animals feed heavily on smaller prey such as amphipods and euphausiids. Adult females tend to eat smaller cod than adult males or juveniles.
Competition with other species
Ringed seals are the only Arctic seal that regularly maintains breathing holes in fast ice. They therefore occupy a vast area of habitat that is impenetrable to other seal species for much of the year. During the open water season, and in areas of pack ice, they may occur with other seal species such as walruses (Odobenus rosmarus rosmarus), harp seals (Pagophilus groenlandicus), hooded seals (Cystophora cristata) and bearded seals (Erignathus barbatus), and also whales such as belugas (Delphinapterus leucas), narwhals (Monodon monoceros) and bowhead whales (Balaena mysticetus). The diets of all these species, except for walruses and bearded seals, may overlap with that of ringed seals and thus competition may be a factor affecting distribution and abundance in some areas.
Polar bears (Ursus maritimus) are by far the most important predator of ringed seals (Kelly et al. 2010, Kovacs 2014). Polar bears prey on little else but ringed seals, and commonly kill a seal every 2–6 days (Lydersen 1998, Reeves 1998, Rosing-Asvid, 2010, Iversen et al. 2013). There are approximately 26,000 polar bears in the Arctic, which each year take hundreds of thousands of ringed seals (Stirling and Lunn 1997). They kill seals at their breathing holes or in their subnivean lairs (i.e. lairs in the area between the surface of the ground and the bottom of the snowpack) by crashing through the snow roof. They also stalk seals lying on the ice in the spring and summer, in ice cracks, and even in open water. Polar bears tend to be most successful at killing pups and sub-adult seals, but adult seals are also taken.
Ringed seals are also preyed upon by walrus (Odobenus rosmarus), killer whales (Orcinus orca), glaucous gulls (Larus hyperboreus) and Greenland sharks (Somniosus microcephalus) (Lydersen 1998, Ridoux et al. 1998, Kelly et al. 2010b, Leclerc et al. 2012, Lydersen & Kovacs 2013). In addition, pups are taken by Arctic (Alopex lagopus) and red (Vulpes vulpes) foxes, wolves (Canis lupus), wolverines (Gulo gulo) ravens (Corvus corax) and dogs in the spring (Reeves 1998, Kelly et al. 2010b, Kovacs 2014).
Health and Parasites
Although there is limited information on health parameters and disease for ringed seals (Tryland et al. 2006), these have been recently reviewed by Kelly et al. (2010b) and Kovacs (2014). Arctic phocids do not seem to have experienced any of the epizootic events with morbillivirus that have affected seals on the European coast. Many different parasites have been detected in ringed seals, the most common being helminths in the gastro-intestinal tract (Kelly et al. 2010 and Kovacs 2014). In Svalbard, the abundance of nematodes and acantocephalans in the digestive tract varies with sampling location and seal age and sex, influenced by the fish availability as prey and the age class exploited by the different seal groups (Johansen et al. 2010). Parasite burdens can be quite high in ringed seals, although they seldom debilitate healthy seals.
Ringed seals occur throughout the Arctic, north to the pole. They are the only northern seal that can maintain breathing holes in thick sea ice (over 2 m in thickness). This special ability allows them to have an extensive distribution in the Arctic and sub-Arctic and to thrive in areas where even other ice associated seals cannot reside.
In the North Atlantic, the ringed seal occurs in marine areas virtually everywhere where there is seasonal ice cover (Reeves 1998, Kelly et al. 2010b, Kovacs 2014). Their global distribution has expanded and contracted with changing sea‐ice cover, and today they inhabit all the seasonally ice‐covered seas of the Northern Hemisphere, as well as some fresh water lakes.
In the Western Atlantic, ringed seals occur as far south as northern Newfoundland, northward to the pole and throughout the Canadian Arctic archipelago. They occur throughout Greenland, but are most abundant where fast ice occurs. Ringed seals occur around Svalbard and Franz Josef Land, and are occasionally encountered in the Faroe Islands and off northern Iceland. In the Eastern Atlantic, ringed seals inhabit the entire Eurasian Arctic coast, including the coastal waters of the White Sea and southeastern Barents Sea, the Gulf of Bothnia and the Baltic Sea. Freshwater populations of ringed seals occur in Lake Ladoga in Russia and Lake Saimaa in Finland (Sipilä & Hyvärinen 1998), as well as in Nettilling Lake in Nunavut, Canada.
Extralimital records extend far south on both sides of the Atlantic, to New Jersey in the west and to France and Portugal in the east (Ridoux et al. 1998). A young seal tagged in Brittany in France, was found one year later in a Greenland shark stomach off Iceland, showing that at least some of these, usually young, vagrants may actually have the navigational skills to return to normal habitat (Ridoux et al. 1998).
Habitat and Movements
The ringed seal is the most strongly ice-adapted/associated seal species. Throughout most of its range, it does not come ashore and uses sea ice as a substrate for resting, pupping, and moulting (Kelly et al. 2010a). It comes out of the water exclusively on sea ice, except in marginal seas and freshwater lakes where ice disappears seasonally.
Ringed seals occur in areas of landfast and drifting pack ice over virtually any water depth. While they may prefer areas of landfast ice for breeding, they may also breed successfully in areas of stable pack ice, such as Baffin Bay and the Greenland Sea. Unlike other northern seals such as harp and hooded seals, the ringed seal is completely adapted to ice-covered waters and does not migrate to open water areas in the winter (Reeves 1998).
Ringed seals are able to maintain several breathing holes in ice that may be over 2 m in thickness by using their strong sharp fore-claws and teeth to scratch through the ice. This allows them to thrive in areas where even other ice-associated seals cannot reside. During the summer, ringed seals forage in areas of pack ice or open water, and may haul out on land where no ice is available.
In the summer and fall, when land-fast ice is not available, ringed seals show considerable diversity in their distribution patterns (Kovacs 2014). Some animals remain in the general vicinity of their breeding sites, while others disperse along coastlines, concentrating their time near glacier fronts. Some spend time in open water far from the coast, while others move north to the southern edge of the permanent ice (Teilmann et al. 1999, Gjertz et al. 2000, Born et al. 2002, Freitas et al. 2008a). Ringed seals are more mobile and have larger ‘home ranges’ during the open-water season than at other times of the year (Born et al.2004).
During the fast-ice seasons, each ringed seal uses several haul-out lairs and additional breathing holes within its home range and travels between them quite regularly. A seal’s lairs are usually only a few hundred meters apart, although on average, the lairs of males are spread over greater distances than those of females. During the reproductive season, females spend more time on average out of the water than males and both sexes shift from hauling out during the night in early spring to hauling out during the day in late spring, with more time spent on the surface during the latter period (Kelly & Quakenbush 1990, Carlenset al. 2006).
Whether ringed seals show fidelity to natal sites, or are faithful to breeding sites as adults, is unclear. It is also not clear to what extent this depends on the quality of the sites (predictable ice stability, sufficient snow to construct lairs, good food availability) or whether there are regional and subspecies differences. Prime habitat for ringed seals may be used over long periods of time, but there are also reports that strongly suggest that there is considerable mobility among ringed seals in some areas (Kovacs 2014). Ringed seals have, however, shown a high degree of spatial fidelity (territoriality) in the Baltic (Härkönen et al. 2008).
Ringed seals can travel significant distances, well over 1000 km (e.g., Kapel et al.1998, Ridoux et al. 1998). However, satellite tracking studies show that individuals tagged at any one location display variable dispersal patterns, with some individuals remaining local throughout the open-water season, while others move offshore or northward to the permanent pack-ice (Teilmann et al. 1999, Gjertz et al. 2000, Born et al. 2004).
The seasonality of ice cover strongly influences ringed seal movements, as well as foraging, reproductive behaviour, and vulnerability to predation (Kelly et al. 2010b).
STOCK AREAS AND SUBSPECIES
There is no definitive genetic or other information to differentiate stocks of Arctic ringed seals. Their distribution is virtually continuous and there are few geographical barriers that would prevent their dispersion. Indeed, individual tagged ringed seals have been shown to move very long distances on occasion (Kapel et al. 1998, Ridoux et al. 1998, Teilmann et al. 1999). As an example, from seals tagged in Resolute Bay four individuals travelled 2,500 kilometres to southeast Baffin Island, and another covered 3,000 kilometres, swimming to Frobisher Bay via Greenland (Polar Blog, Canadian Geographic, July 2014).
On the basis of geographical isolation, ringed seals are divided into five subspecies: Pusa hispida hispida of the Arctic Ocean (the Arctic ringed seal), P. hispida ochotensis of the Sea of Okhotsk and northern Japan, P. hispida botnica of the Baltic Sea and the two last living in fresh water lakes, P. hispida ladogensis of Lake Ladoga in Russia, P. hispida saimensis of Lake Saimaa in Finland. The latter four subspecies are well supported. Genetic structuring within the Arctic subspecies, however, has yet to be thoroughly investigated and it may prove to be composed of multiple distinct populations (Kelly et al. 2010b).
Ringed seals cannot create breathing holes in the thick multi-year ice found in large parts of the Arctic Ocean and in the Canadian Archipelago north of Baffin Island. This type of ice therefore operates as a natural barrier for ringed seals. Since they prefer to stay in the vicinity of ice, long stretches of open waters will also contain few ringed seals. The Arctic ringed seals therefore consist of several populations, between which there is little interchange (Rosing-Asvid 2010).
On a North Atlantic scale, the NAMMCO Scientific Committee (NAMMCO 1997a) has recognised 3 stock management areas (see map below), based primarily on the low likelihood of mixing between the areas. While there is presently no genetic or other evidence to confirm such stock divisions, they are useful in determining and managing the status of North Atlantic ringed seals.
Area 1 is centred on Baffin Bay and includes northeastern Canada and West Greenland. It is separated from Area 2, which includes East Greenland and the Greenland Sea east to Svalbard, by the Greenlandic land mass. Area 3 includes the Barents and Kara Seas east to the Severnaya Zemlya, where it was considered that ice conditions and low productivity would limit the movements of ringed seals.
Current Abundance and Trends
Ringed seals are the most abundant high arctic seal and although no accurate global estimate is available, the species is thought to number at least a few million animals (Reeves 1998).
Counting ringed seals
Ringed seals are difficult to count. Other ice breeding seals, such as harp (Pagophilus groenlandicus) and hooded (Cystophora cristata) seals, birth and rear their pups on the surface of the ice. Aerial surveys for these species are conducted to count the pups during breeding season and pup counts are then converted to total population estimates. Ringed seals give birth in lairs under the snow, which are practically invisible from the ice surface. While they commonly haul out on the ice during the moulting period in late spring, it is unlikely that the entire population would be on the ice surface at any given time. Aerial, ground- or ship-based surveys can detect only those seals that are on the ice or at the surface of the water and this proportion is usually unknown. Therefore, estimates of ringed seal abundance are not available for most areas.
Despite these difficulties, aerial surveys of fast-ice areas during the spring have been conducted and are the most widely used method of assessing the abundance of ringed seals, although it is widely recognized that such counts are underestimates (see Reeves 1998, and more recently e.g. Frost et al. 2004, Moulton et al. 2005, Bengtson et al. 2005, Krafft et al. 2006a). Surveys must be timed to coincide with peak haul-out season and correction factors are still required to account for the number of animals that are not visible at the time of the survey because they are either in the water, or in some cases, still in their snow lairs.
A variety of methods have been employed to attempt to correct counts to population estimates (Reeves 1998, Bengtson et al. 2005, Kelly et al. 2006, Krafft et al. 2006a) but calibration issues remain (Carlens et al. 2006, Krafft et al. 2006a). Most if not all abundance surveys to date should probably be considered indices of abundance (Kovacs & Lydersen 2006, Kovacs 2014).
Counts of breathing holes and/or birth lairs using trained dogs have also proven to be an effective method in some areas (Hammill & Smith 1990, Lydersen 1998). Some estimates of abundance have also been derived by calculating the number of ringed seals required to support the predation of polar bears and humans in the area. The abundance of polar bears is usually more accurately known than the abundance of ringed seals. For example, Kingsley (1998) used a population estimate for polar bears in Baffin Bay, estimates of their food requirements, and the human harvest by Canada and West Greenland, to estimate that there must be at least 1.2 million ringed seals in the area to support this level of predation. Kingsley (1990) used a similar approach to calculate that there must be at least 4 million seals in the Canadian Arctic.
The remoteness and dynamic nature of ringed seal sea‐ice habitat, time spent below the surface, along with their broad distribution and seasonal movements makes surveying ringed seals expensive and logistically challenging. It is therefore very difficult to assess their population size and trend (Kelly et al. 2010b).
The NAMMCO Scientific Committee (NAMMCO 1997a) derived an approximate estimate of the abundance of ringed seals in NAMMCO Area 1 (Northeastern Canada – Baffin Bay – West Greenland, see ‘Distribution‘) of approximately 1.3 million seals, based on extending existing estimates to areas of similar habitat. This estimate has a large contribution from pack ice areas, where knowledge of ringed seal density is particularly poor. Nevertheless, it is similar to the estimate by Kingsley (1998) for roughly the same area.
ABUNDANCE AND TRENDS
Because of the difficulties in deriving estimates of abundance, there is little information on trends in abundance for most areas.
Short-term fluctuations in the numbers of young seals produced have been documented (eg. Kingsley and Byers 1998) and are likely related to annual variations in ice conditions. Seasonal reductions in abundance in the vicinity of hunting communities have also been noted (Reeves 1998). The only areas where population reductions that can definitely be related to over-harvesting have been noted are in the Okotsk Sea and the Baltic Sea. Both these areas were subject to large-scale commercial harvesting in the past. This harvesting has since been reduced (Okotsk Sea) or has ceased (Baltic Sea) and ringed seal populations are now thought to be recovering in these areas (Reeves 1998). Some small lake populations have also been affected by hunting (Sipilä & Hyvärinen 1998).
The table below gives the most recent abundance estimates for ringed seals in different areas, as well as the conservation status in these areas.
Ringed seal abundance and conservation status
|Areas||Year||Estimate||Status of ‘populations’||Causes // Concerns||References|
|Arctic ringed seal||A few million||Least concern (IUCN Red list)||Large population size, broad distribution // Climate change||Reeves, 1998; Kovacs et al., 2008|
|Canadian Arctic Archipelago||N/A||Unknown|
|Greenland Sea & Baffin Bay||1979||787,000||Stable since 1979||Large population size, broad distribution // Climate change||Finley et al., 1983|
|Hudson Bay, western part||1995||280,000||Lunn et al., 1997|
|2007-08||53,400 on ice||Ferguson & Secretariat, 2009|
|Beaufort & Chukchi Seas||from 1981||1,000,000, incl. pack ice||Kelly et al., 2010b, based on several surveys|
|White, Barents & Kara Seas||from 1975||220,000|
|Russian Arctic coast||N/A||Unknown|
|Okhotsk ringed seal||1968-90||676,000 – 855,000||Likely stable||Hunting // Climate change||Fedoseev, 2000|
|Baltic ringed seal||1996||10,000||Dramatic ↓ until the 1970s. Presently ↑ in Bothnia Bay, ↓ in the Gulf of Riga, stable in the Gulf of Finland||Swedish & Finnish extermination efforts, low fertility due to organochlorines // Climate change||Härkönen et al., 1998, 2008; Harding & Härkönen, 1999; Karlsson et al., 2007|
|Lagoda ringed seal||2001||3,000 – 5,000||↓||By-catch // Climate change||Verevkin, 2002; Agafonova et al., 2007|
|Saimaa ringed seal||2005||< 300 (1)||↓||By-catch // Climate change||Sipilä, 2006; Sipilä & Kokkonen, 2008|
Ringed seals are the most abundant high arctic seal and although no accurate global estimate is available, the species is thought to number at least a few million animals (Reeves 1998).
ARCTIC RINGED SEALS
Arctic ringed seals do not form large seasonal aggregations (as some other seal species do) and often occupy areas of pack ice that are extremely remote and inaccessible to hunters. These factors decrease their vulnerability to overexploitation. Harvests in Canada, Greenland and Russia have been sustained for hundreds or even thousands of years with little evidence of depletion. On the other hand, reliable information on ringed seal numbers is lacking for most areas, so it is not possible to describe trends in the populations.
The NAMMCO Scientific Committee concluded in 1996 that harvests of arctic ringed seals in the Baffin Bay area (Area 1) were likely sustainable, but cautioned that more information was needed on ringed seal distribution and numbers, especially in pack ice areas (NAMMCO 1997). Harvests in other areas of the North Atlantic are currently considered to pose no threat to the populations.
The persistence of the Arctic ringed seal, and other subspecies, will however be challenged by the impacts of climate change, which are already apparent in the Arctic (e.g., Meier et al. 2004, Rosing-Asvid 2006, 2010, Kelly et al. 2010, Lydersen et al. 2007, 2010, 2014, Kovacs et al. 2008, 2012, Kovacs 2014). Habitat loss and deterioration caused by decreases in sea-ice and snow cover will, for example, lead to increases in pup mortality from premature weaning, hypothermia and predation. Other indirect impacts are also expected, including changes in the food web, increased predation and increased disturbance by human activities. See under ‘Other human impacts‘ for more detail.
It is predicted that within the foreseeable future, climate changes will mean that the number of Arctic ringed seals will decline substantially and they will no longer persist in a substantial portion of their range (Kelly et al. 2010). Kovacs (2014) stresses the importance of developing and implementing an Arctic ringed seal monitoring program, given the ecological and subsistence importance of this species in the Arctic.
Both the international programs CAFF (Conservation of Arctic Flora and Fauna) and AMAP (Arctic Monitoring and Assessment Program) under the Arctic Council have specifically requested that all of the Arctic countries launch scientific monitoring programs on ringed seal population structure, trends in abundance, vital rates and age structures because of this species’ value as an ‘indicator species’ for monitoring global climate change and contaminant patterns. Today only Norway has a national program for ringed seal monitoring.
OKHOTSK, BALTIC, LAGODA AND SAIMAA RINGED SEALS
Commercial harvests in the Sea of Okhotsk and predator‐control harvests in the Baltic Sea, Lake Ladoga, and Lake Saimaa caused dramatic population declines in the past but have since been restricted. Current harvest levels appear to be low and sustainable. Kovacs et al. (2008) and Kelly et al. (2010) provide status reviews for these four subspecies, which are summarized below.
No recent population data are available for the Sea of Okhotsk population and the current population trend is unknown, however it is thought to be stable. Climate change impacts, including decreases in sea-ice quality and extent, are likely to have negative consequences. The range of the population is bounded by land to the North and the opportunity to contract its range with the ice is limited.
The Baltic Sea population is presently depleted. However, some recovery has been observed in recent years (Härkönen et al. 1998), with a positive population trend in the Gulf of Bothnia, which is the primary breeding area (Karlsson et al.2007). Climate change is likely to also have an impact on this subspecies. Current sea ice trends in the Baltic and projections for the next 30 years pose a major threat to all southern populations in the Baltic, with only the Gulf of Bothnia likely to retain fairly good winter sea-ice habitat for ringed seals (Meier et al. 2004).
The Lake Ladoga population is depleted and likely decreasing. Mortality due to by-catch in fishing gear accounts for 10-16% of the population annually (Verevkin et al. 2006), which is unsustainable. Climate change will likely lead to a decrease in ice habitat and increased pup mortality. As it is a landlocked population, Ladoga ringed seals cannot disperse to a new habitat.
The Lake Saimaa population is severely depleted and considered to be endangered, with less than 300 seals remaining. Population growth rates vary across the different regions of the lake and are positive in some areas and negative in others. This means that even though the overall population may increase, seals may no longer be present in some regions of the lake (Sipilä 2006). By-catch is a significant source of mortality (Sipilä and Kokkonen 2008), which adds to the consequences of reproductive failure in recent years due to poor ice conditions. Continued degradation of ice and snow habitat will likely further threaten the survival of this population.
STATUS ACCORDING TO OTHER INTERNATIONAL ORGANISATIONS
Ringed seals have no special conservation status under the Convention on International Trade in Endangered Species of Fauna and Flora (CITES) and are not listed in any appendix.
On the IUCN “Red list”, the ringed seal is listed as Least Concern in an assessment made in 2008. However this assessment stipulates that “given the risks posed by climate change to all Ringed Seal subspecies, including the Arctic Ringed Seals, this species should be reassessed within a decade” (Kovacs et al. 2008).
The World Wildlife Fund (WWF) not only sees the Greenlandic Inuit hunt of seals, including ringed seals, as an important component of Greenland culture and economy, but considers the Inuit sealing to be sustainable and directly supports it. WWF (2013) calls for the EU to address the impacts of their import bans as well as to inform the European public about the Inuit exemption. It suggests that “with financial support from the EU, the existing certification label be considered expanded to guarantee e.g. sustainability of the hunt, full utilization of catches and animal welfare to meet increasing demands from conscious consumers in the EU as well as worldwide”.
In Canada, the ringed seal has been listed as “Not at Risk” by COSEWIC/COSEPAC in 1989, and has not been reviewed since.
Ringed seals inhabit the waters of two NAMMCO member states—Greenland and Norway. Only the Arctic ringed seal is present in these areas.
Humans have hunted ringed seals in the Arctic since the arrival of people to the region and they remain a fundamental subsistence resource for many northern coastal communities today (ACIA 2005, Hovelsrud et al. 2008, Kovacs et al. 2008, Kelly et al. 2008). Subsistence and commercial harvests of Arctic ringed seals have been large in the past, however there is no evidence to suggest that they have contributed to large‐scale population declines. Commercial harvests in the Sea of Okhotsk and predator‐control harvests in the Baltic Sea, Lake Ladoga, and Lake Saimaa caused population declines in the past but have since been restricted (Kelly et al. 2010).
No international governing body regulates the harvest of ringed seals. Advice on sustainable hunting and management of ringed seals is given by the North Atlantic Marine Mammal Commission (NAMMCO).
In most areas, there are relatively few restrictions on the hunting of ringed seals. In Canada, Greenland, Norway and Russia, a licence is required, but there are almost no restrictions on season or the number of animals that can be taken (Belikov & Boltunov 1998, Reeves et al. 1998, Teilmann & Kapel 1998). In Alaska, there are no limitations on the subsistence take of ringed seals. Total allowable catches (or TACs) are not set for ringed seals in Canada, but any commercial harvests are regulated by licenses and permits and wastage is specifically prohibited.
In Norway, licensed hunters can shoot ringed seals in Svalbard from 20 May – 20 March. They are protected during their breeding season, as well as throughout the year in Svalbard national parks and nature reserves. Sport hunting of ringed seals is permitted on the Norwegian mainland. Individual hunters must have a licence and quotas on how many may be taken are set.
The general lack of catch quotas in most areas means that there has often been no requirement for hunters to register their catch. While records of commercial trade in sealskins exist for some areas, these likely represent a variable and sometimes small proportion of the number of seals that are actually taken. Hence historical catch records for ringed seals are in many cases poor and incomplete. This situation is, however, changing. Greenland has, for example, been collecting complete harvest statistics for all species since 1992 under the Piniarneq system (Teilmann & Kapel 1998). Harvest studies are also a part of some native land claims in Arctic Canada (Reeves et al. 1998).
There are no national restrictions in Greenland, but permits are used to control the harvest and hunting of ringed seals is regulated in nature reserves and many municipalities (Government of Greenland 2012). Everyone engaged in hunting in Greenland must have a valid hunting license, either a full time license or a leisure license. Being a full time hunter requires that at least 50% of your income comes from hunting. Full time hunters can be licensed to hunt species that leisure hunters are not allowed to hunt, such as baleen whales and polar bears.
Since 2009, only full time hunters may sell sealskins to the tannery Great Greenland A/S (Government of Greenland 2012a). A hunter must submit a yearly catch report to the Ministry of Fisheries, Hunting and Agriculture. This makes it possible to monitor and evaluate the catch levels of the four different species of seals, both at local and national levels.
Ringed seals are the “daily bread” of many northern peoples. The Inuit of Greenland and Arctic Canada are heavily dependent on ringed seals for food, and on their skins for clothing and for sale. In some areas of the Arctic, the widespread and year-round existence of ringed seals is what has made the presence of human life possible.
Ringed seals, or “natseq”, can be hunted year-round, even during the dark months, and this has made them the most reliable source of daily necessities for the lives of northern peoples. Ringed seals have provided a stable supply of meat and blubber for food, heating and lighting, as well as skins for essential commodities such as boots (“kamiks”), clothing, tent coverings, bladder floats (“avataqs”) and other equipment essential for the survival and success of Inuit hunting communities.
Even the means of transportation to hunting grounds has been facilitated through the use of ringed seal products. Skins from ringed seals and bearded seals (Erignathus barbatus) are used to cover the fragile frames of the kayaks and were also formerly used to cover the larger boats or “umiaks” that were used for transportation of whole families. Seal meat is also the essential “fuel” for the dogs that pull the sleds (Heide-Jørgensen & Lydersen 1998). Particularly in North and East Greenland, ringed seals remain a very important as a source of food for both humans and sled dogs (Rosing-Asvid 2010).
The seals also play a highly significant role in Greenlandic mythology.
REPORTED CATCHES IN NAMMCO MEMBER COUNTRIES
|Greenland||2019||Labrador - Baffin Bay - West Greenland||36572|
|Norway||2019||Northern Norwegian Coast||4|
|Norway||2018||Northern Norwegian Coast||4|
|Norway||2017||Northern Norwegian Coast||16|
|Norway||2016||Northern Norwegian Coast||0|
|Norway||2015||Northern Norwegian Coast||0|
|Norway||2014||Northern Norwegian Coast||0|
|Norway||2013||Northern Norwegian Coast||0|
|Norway||2012||Northern Norwegian Coast||13|
|Norway||2011||Northern Norwegian Coast||5|
|Norway||2010||Northern Norwegian Coast||1|
|Norway||2009||Northern Norwegian Coast||9|
|Norway||2008||Northern Norwegian Coast||2|
|Norway||2007||Northern Norwegian Coast||2|
|Norway||2006||Northern Norwegian Coast||0|
|Norway||2005||Northern Norwegian Coast||5|
|Norway||1992-2004||Northern Norwegian Coast||N/A|
This database of reported catches is searchable, meaning you can filter the information by for instance country, species or area. It is also possible to sort it by the different columns, in ascending or descending order, by clicking the column you want to sort by and the associated arrows for the order. By default, 30 entries are shown, but this can be changed in the drop-down menu, where you can decide to show up to 100 entries per page.
Carry-over from previous years are included in the quota numbers, where applicable.
You can find the full catch database with all species here.
For any questions regarding the catch database, please contact the Secretariat at firstname.lastname@example.org.
A Falling Income
Ringed seal skins have commercial value, although this is considerably less today than it has been in the past (Reeves et al. 1998, Teilmann & Kapel 1998, Belikov & Boltunov 1998). The sale of the skins of young ringed seals continues to be an important source of cash income in Arctic Canada and Greenland (Rosing-Asvid 2010). This has, however, been drastically reduced in the last decades due to the anti-sealing campaigns and the resulting 1983 and 2009 bans on seal skins in the EU. These bans have been implemented despite the sustainability of Greenlandic seal hunting. Although the Inuit exemption renders it possible to export sealskins from Greenland to the EU and place them on the market if the skins are certified according to Regulation no 737/2010, the hunters and the sealskin business in Greenland have been negatively affected by the EU bans.
EU SEALSKIN BAN AND THE INUIT EXEMPTION
In 1983, the European Economic Community imposed an import ban on all whitecoat products (Kovacs 2015). The ban, which was initially for 2 years, has been extended since then and was expanded in 2009 to include juvenile (beater) pelts (Hammill et al. 2015).
Exceptions to the ban include products resulting from Inuit/indigenous harvests, products for the sole purpose of sustainable management of marine resources, and products for the personal use of travellers to the EU. Furthermore, the ban does not apply to seal products trans-shipped through the EU to non-EU destinations (DFO 2016b).
In order for seal products to be exempt from the ban and placed on the market in the EU, the Inuit or indigenous harvest must meet certain conditions. The hunt must:
- be traditionally conducted by the community
- contribute to the community’s subsistence in order to provide food and income and not be primarily conducted for commercial reasons
- pay due care to animal welfare, while taking into account the community’s way of life and the subsistence purpose of the hunt (EUR-Lex 2016).
Other Human Impacts
Beyond hunting and direct utilisation, human activities can also impact ringed seal populations through climate change, pollution, habitat destruction and by-catch in commercial fisheries.
CLIMATE AND OCEANOGRAPHIC CHANGES
Climate change denotes changes in major weather patterns over a long time-scale and results from both natural variability and the influence of human activities. It is by far the most serious threat to Arctic biodiversity and exacerbates all other threats (CAFF 2013).
A potential long-term and alarming threat to ringed seals is human-induced global warming or climate change. Both the observed and the projected effects of a warming global climate are most extreme in northern high‐latitude regions (ACIA 2005, CAFF 2013). It has now become clear in the region that climate change is occurring and that the Arctic has already undergone significant physical environmental changes due to global warming (ACIA 2005, CAFF 2013, Kovacs 2014 for review).
There has, for example, been a decrease in the extent, duration and area of Arctic sea ice since the 1970s (Johanessen et al. 1995, Jeffries et al. 2013). This has led to a decrease in the condition and survival of polar bears in Western Hudson Bay in Canada (Stirling et al. 1999), probably because of reduced access to their major prey, the ringed seal.
The observed and projected changes with significant potential to affect the ringed seal’s range and habitat (both its physical and biological components) are changes in sea ice, snow cover, ocean temperature, ocean pH (acidity), and associated changes in ringed seal predator and prey species.
Ringed seals are the most ice-associated/adapted pinnipeds in the Arctic and are perhaps the most vulnerable of the high-arctic pinnipeds. This is due to their reliance on sea ice as a platform for resting, whelping, nursing, and moulting, and their dependence on snow cover to provide protection from cold and predators and to successfully rear their young. Ice and snow cover are changing and will continue to do so as the climate warms. Numerous authors have studied and/or warned against the possible impact that global warming will have on ringed seals (Stirling et al. 1999, Stirling & Smith 2004, Meier et al. 2004, Ferguson et al. 2005, Stirling 2005, Rosing-Asvid 2006, 2010, Learmonth at al. 2006, Lydersen et al. 2007, 2010, 2014, Sipilä et al. 2007, Freitas et al. 2008b, Härkönen 2008, Kovacs & Lydersen 2008, Laidre et al. 2008, Moore & Huntington 2008, Kovacs et al. 2012).
The impacts of climate change on ringed seals and other Arctic species will be both direct and indirect and are reviewed in Kelly et al. (2010b) and Kovacs (2014). The impacts of climate change and the potential resilience of species are complex, but it is necessary to assess these factors so that suitable conservation actions can be taken (Moore & Huntington 2008).
A reduction in the extent and duration of ice cover would directly reduce the habitat available to ringed seals. It might also lead to poor condition of pups and higher pup mortality due to the early destruction of birth lairs. In the southern Baltic Sea, a series of nearly ice-free winters from 1989–1995 led to very high pup mortalities (Härkönen et al. 1998). Insufficient snow cover to protect pups in lairs in the spring will also likely lead to higher mortality due to increased predation. In warm years, ringed seal pups are more exposed to predation from polar bears due to a higher density of lairs on the smaller area of available sea ice and the fact that the lairs are weaker because there is less snow. The seals may also experience periods of thaw that can destroy their lairs and expose the pups (Hezel et al. 2012, Rosing-Asvid 2010). Ice is also needed by ringed seals for moulting, resting, and in some populations foraging, but the type of ice and its stability is not as important for the seals outside of the breeding season. Although northern ringed seals still exhibit a clear preference for areas with considerable ice coverage (e.g. Freitas et al., 2008).
Beyond the direct changes to their habitat, climate change will pose risks to ringed seals by inducing indirect changes. These include changes to their forage base (species and density shifts, and distributional shifts of prey species, etc.), increased competition from temperate species, increased predation rates from polar bears and arctic foxes (at least initially) as well as killer whales, increased disease and parasite risks, greater potential for exposure to increased pollution loads and impacts via increased human traffic and development in previously inaccessible, ice-covered areas (Kelly et al. 2010b, Kovacs 2014).
It is predicted that within the foreseeable future, the number of Arctic ringed seals will decline substantially and they will no longer persist in a substantial portion of their range (Kelly et al. 2010). Kovacs (2014) stresses the importance of developing and implementing an Arctic ringed seal monitoring program, given the ecological and subsistence importance of this species in the Arctic. See under ‘‘Stock Status’ for more details.
Changes are indeed already taking place in the Arctic: see for example the figures below taken from the The Arctic Report Card: update for 2013 – Sea Ice (Perovitch et al.2013) and Greenland Ice sheet (Tedesco et al. 2013) in Jeffries et al. (2013).
The levels of persistent organic pollutants (POPs), mercury, and radionuclides are particularly high in communities that have traditional dietary habits (e.g. Polder et al. 2003). This can be linked to the high contaminant loads in the marine mammals they consume.
Contaminant loads in ringed seals have been investigated in most parts of the species’ range (although not in the Sea of Okhotsk), which reflects the ringed seal’s importance in the diets of coastal people and polar bears (Dietz et al. 1998, Hyvarinen et al. 1998, Muir et al. 1999, Bang et al. 2001, Fisk et al. 2002, 2005, Sonne et al. 2002, 2009, Rigét et al. 2005, 2006, Dietz 2008, Wolkers et al. 2008, Sonne et al. 2009, Routti et al. 2009, Kelly et al. 2010b, Kovacs 2014).
The Arctic Monitoring and Assessment Programme (AMAP) was established in the 1990s to address the risks and trends in contaminants in the Arctic, and ringed seals were selected as a key monitoring species because of their broad circumpolar distribution, high abundance, high trophic status and their frequency in the diet of coastal peoples (Wilson et al. 1998).
Pollutants such as organochlorine (OC) compounds and heavy metals have been found in all ringed seal populations, with males tending to have higher toxic loads than females for many substances. Relatively high levels of chlorinated hydrocarbons have been found in the blubber of ringed seals in some areas, probably as a result of atmospheric transport to the Arctic (Reeves 1998). OC contamination is also greater in the European Arctic than in the Canadian or U.S. Arctic (Borgå et al. 2005). In addition, metals including cadmium, mercury, zinc and selenium have been found to accumulate in other tissues (Dietz et al. 1998).
Mercury contamination is a particular problem for some freshwater populations and is thought to have contributed to elevated mortality of ringed seal pups in Lake Saimaa (Sipilä & Hyvärinen 1998, Kostamo et al. 2002). Environmental contaminants have also been implicated as a factor in the reduced fertility of Baltic Sea seals, which has inhibited the recovery of the population (Härkonen et al. 1998, Harding & Härkönen 1999). For most other areas, however, there is little evidence that contaminants are an immediate threat to ringed seals (Kovacs 2014) and following restrictions on the use and release of POPs into the environment, levels of these substances are dropping rapidly in the Baltic and in the Arctic (e.g. Kostamo et al. 2002, Wolkers et al. 2008).
A suite of new-use chemicals previously unreported in the Arctic has recently been documented in arctic biota including ringed seals. However, little information exists for these compounds in terms of spatial patterns, food web dynamics, or species differences in levels (Kovacs 2014). Kovacs underlines that although levels of these compounds are currently low, there is concern because some are increasing rapidly in concentration in some areas (e.g., polybrominated diphenyl ethers, Riget et al. 2006) and some have unique toxicological properties. Some of these compounds were presumed to have low potential for long-range transport and were therefore not expected to make their way into arctic biota. Kovacs (2014) also stresses that a better understanding of the effects of contaminants exposure is needed, especially given the risks of climate change stresses.
This is important because in addition to their direct toxicity, anthropogenic contaminants can increase susceptibility to disease and decrease resilience in marine mammals (Reijnders & de Ruiter-Dijkman 1995).
HABITAT DISTURBANCE AND ACOUSTIC POLLUTION
Reduction in sea ice cover due to global warming (see above) will likely lead to increased human activity in the Arctic in the form of shipping and resource extraction industries, with an associated increase in the threat of marine accidents, pollution discharge and human created noise.
Increased oil exploration, exploitation and possible oil spills, drilling and shipping are potential threats to ringed seals in some areas. Ice breakers may directly disrupt the ice habitat of ringed seals, although this would only affect a small area in relation to the total habitat available.
Noise from shipping and industrial activities may disturb ringed seals and disrupt their activities, possibly leading to the abandonment of prime habitat (Reeves 1998). To date, the rather isolated and inaccessible habitat of ringed seals had provided them some protection from these threats.
Habitat disturbance, through manipulation of water levels, recreational snow machine operation, boating, tourism, shoreline construction, wind farms, etc., have been highlighted as specific threats for the Lakes Ladoga and Saimaa ringed seals (Sipilä & Hyvärinen 1998, Agafonova et al. 2007). Routine day-tourism seems to have caused the desertion of at least two previously used haulout sites at Lake Ladoga (Agafonova et al. 2007, Verevkin et al. 2006). As many as 2,000 wind generators are planned to be erected in Bothnian Bay, the main breeding area for Baltic ringed seals, although the impacts on ringed seals from the disturbance associated with the construction and operation of wind farms are unknown.
BY-CATCH AND COMPETITION WITH FISHERIES
Arctic ringed seals have little interaction with commercial fisheries, both because they do not consume commercial fish species to any great extent, and because their distribution does not coincide with intensive fisheries in most areas. They are therefore seldom caught in fishing gear. However, capture in fishing gear and other negative impacts associated with fisheries is a major problem for the ringed seals in Lakes Saimaa and Ladoga (Sipilä & Hyvärinen 1998, Agafonova et al. 2007, Kovacs et al. 2012) and in the Baltic Sea (Härkonen et al. 1998). Young seals seem particularly susceptible to capture in nets. By-catch alone accounts for 10-16% of the annual mortality of the Lake Ladoga population (Verevkin et al. 2006).
Research on ringed seal populations in Greenland has been ongoing for many years. Early research focused on monitoring the harvest (catch statistics, life history parameters, diet, contaminants). Some abundance surveys were also conducted, where movements were studied using conventional tagging. During recent years, ringed seals have been studied through tagging with satellite linked data-loggers.
These tracking studies shows that some areas hold a high concentration of local stationary seals, whereas other areas are visited by migratory seals that swim long distances. It is a large and expensive task to identify the movement patterns of ringed seals throughout their distribution area. Fortunately, for this research, oceanographers have become aware that satellite transmitters on seals can produce temperature and salinity profiles, even in ice-filled waters where it can be impossible or very expensive and difficult to get around by boat.
A dedicated tagging program was initiated in 2012 for obtaining oceanographic data in two fjord systems with stationary seals and large productive outlet glaciers (Kangia – the Icefjord near Ilulissat in west Greenland and Sermilik with the Helheim glacier near Tasiilaq in East Greenland). This project is a collaboration between physical oceanographers from New York University and biologists from the Greenland Institute of Natural Resources. The main purposes are to further the understanding of how the hydrographic conditions affect the outlet glaciers, and to study how the behaviour (and prey) of ringed seals inhabiting these fjords change with changing environmental conditions (temperature and salinity of the water).
Three satellite relay data loggers (SRDLs) that measure Conductivity/Temperature/Depth (CTD) are deployed annually in each fjord. Ringed seal diet in these two fjords are also studied, based on stomach content analysis from seals caught as part of the local subsistence hunt. In 2019, this study was complemented with data obtained from tags on Greenland halibut, creating the possibility to collect and examine data pertaining to the habitat use, movement and ecology of both seals and halibut in the Ilulissat Icefjord, Disko Bay (National Progress Report Greenland 2019).
As part of an environmental study program financed by the oil industry, and in collaboration with the University of Aarhus, ringed seals were also tagged in the coastal waters of Northeast Greenland in August 2017 and analysis of this data was ongoing in 2019 (National Progress Report Greenland 2019).
Ringed seals in Svalbard have been the subject of research efforts on a wide variety of topics intermittently since the early 1980s. Prominent in these research efforts has been the Norwegian Polar Institute (NPI), which has been looking at population parameters, diet, habitat use, reproductive and general ecology, reproductive energetics, abundance in different fjords, diving behaviour and physiology, and contaminant burdens. This body of research provides the basis for a data time series that will permit assessment of population and ecological trends.
In 2002, NPI began a dedicated monitoring programme for ringed seals as part of MOSJ (Monitoring of Svalbard and Jan Mayen), designed to explore important aspects of ringed seal population biology and ecology and provide the first comparative data in a time series for the population (Kovacs & Lydersen 2006). This work focuses on density and abundance of ringed seals in selected fjords, trends in population parameters (age structure and vital rates), diet, genetics, condition and ‘health status’ (blubber-reserves, serum chemistry, parasite infestations), and contaminant burdens (POPs, heavy metals, toxaphenes).
The project ICE Ecosystems is a research programme that focuses on Arctic species that are dependent on ice during some part of their life cycles and are threatened by future climate change: ice fauna, zooplankton, polar cod, polar bears, ringed seals and ivory gulls. As part of the ICE ringed seal programme from 2010 to 2012, 38 ringed seals off Svalbard were instrumented with advanced satellite tags to get information on the life of the seals and their use of the sea ice outside the breeding and moulting periods. In 2013, tagging continued using various combinations of satellite tags and sensors that were deployed on males and females of different age classes.
The satellite tags used in this research programme provided standard information on where the seals were, how deep they were diving and for how long. They also provided hydrographic data (salinity and temperature) as well as information providing insights into primary production (chlorophyll levels) in the regions where the seals swim and dive. Samples have also been collected in Kongsfjorden, for various ecotoxicological studies.
Sea ice has continued to decline markedly within the archipelago in recent years, with no sea ice formation at all taking place in most of Svalbard’s fjords in the winter of 2011 and spring of 2012. Instrumented animals tracked via ARGOs and GPS systems will document their responses to these unique conditions, which are likely precursors of what ringed seals will experience elsewhere in the decades to come (Lydersen & Kovacs, in Kovacs 2014).
In 2019, 23 ringed seals were collected from the Isfjorden area in Svalbard by researchers from NPI and data on morphometrics, age, sex and various tissues were delivered to the Norwegian Environmental Specimen Bank.
Arctic Climate Impact Assessment (ACIA). (2005). Cambridge, UK, Cambridge University Press. 1042 pp. Available at http://www.acia.uaf.edu./pages/scientific.html
Agafonova, E.V., Verevkin, M.V., Sagitov, R.A., Sipilä, T., Sokolovskay, M.V. and Shahnazarova, V.U. (2007). The ringed seal in Lake Ladoga and the Valaam Archipelago. Baltic Fund for Nature of Saint- Petersburg Naturalist Society, St. Petersburg State University & Metsähallitus, Natural Heritage Servives, Vammalan Kirjapaino OY., Vammala, Finland.
Andersen, S.M., Lydersen, C., Grahl-Nielsen, O. and Kovacs, K.M. (2004). Autumn diet of harbour seals (Phoca vitulina) at Prins Karls Forland, Svalbard, assessed via scat and fatty-acid analyses. Canadian Journal of Zoology, 82(8), 1230–1245. https://doi.org/10.1139/z04-093
Bang, K., Jenssen, B.M., Lydersen, C. and Skaare, J.U. (2001). Organochlorine burdens in blood of ringed and bearded seals from north‐western Svalbard.Chemosphere, 44(2), 193–203. https://doi.org/10.1016/S0045-6535(00)00197-1
Belikov, S.E. and Boltunov, A.N. (1998). The ringed seal (Phoca hispida) in the western Russian Arctic. NAMMCO Scientific Publications, 1, 63–82. https://doi.org/10.7557/3.2981
Bengtson, J.L., Hiruki-Raring, L.M., Simpkins, M.A. and Boveng, P.L. (2005). Ringed and bearded seal densities in the eastern Chukchi Sea, 1999-2000. Polar Biology, 28, 833–845. https://doi.org/10.1007/s00300-005-0009-1
Bonner, N. (1994). Seals and sea lions of the world. London: Blandford, 224 pp.
Borgå, K., Gabrielsen, G.W., Skaare, J.U., Kleivane, L., Norstrom, R.J. and Fisk, A.T. (2005). Why do organochlorine differences between arctic regions vary among trophic levels? Environmental Science and Technology, 39(12), 4343‐4352. https://doi.org/10.1021/es0481124
Born, E.W., Teilmann, J. and Riget, F. (2002). Haul-out activity of ringed seals (Phoca hispida) determined from satellite telemetry. Marine Mammal Science, 18(1), 167–181. https://doi.org/10.1111/j.1748-7692.2002.tb01026.x
Born, E.W., Teilmann, J., Acquarone, M. and Riget, F.F. (2004). Habitat Use of Ringed Seals (Phoca hispida) in the North Water Area (North Baffin Bay). Arctic, 57(2), 129–142. https://doi.org/10.14430/arctic490
Conservation of Arctic Flora and Fauna (CAFF). (2013). Arctic Biodiversity Assessment. Status and trends in Arctic biodiversity. Conservation of Arctic Flora and Fauna, Akureyri. Available at http://www.caff.is/publications/view_category/10-arctic-biodiversity-assessment
Carlens, H., Lydersen, C., Krafft, B.A., and Kovacs, K.M. (2006). Spring haul-out behavior of ringed seals (Pusa hispida) in Kongsfjorden, Svalbard. Marine Mammal Science, 22(2), 379–393. https://doi.org/10.1111/j.1748-7692.2006.00034.x
Dehn, L.‐A., Sheffield, G., Follmann,E., Duffy, L., Thomas, D. and O’Hara, T. (2007). Feeding ecology of phocid seals and some walrus in the Alaskan and Canadian Arctic as determined by stomach contents and stable isotope analysis. Polar Biology, 30, 167–181. https://doi.org/10.1007/s00300-006-0171-0
Dietz, R. (2008). Contaminants in marine mammals in Greenland — with linkages to trophic levels, effects, diseases and distribution. DSc Thesis. University of Aarhus, Denmark, Copenhagen, Denmark. 120 p. Available at https://www2.dmu.dk/Pub/Doctor_RDI.PDF
Dietz, R., Paludan-Müller, P., Agger, C.T. and Nielsen, C.O. (1998). Cadmium, mercury, zinc and selenium in ringed seals (Phoca hispida) from Greenland and Svalbard. NAMMCO Scientific Publications, 1, 242–273. https://doi.org/10.7557/3.2992
Fedoseev, G.A. (2000). Population biology of ice‐associated forms of seals and their role in the northern Pacific ecosystems. Center for Russian Environmental Policy, Russian Marine Mammal Council, Moscow, Russia. 271 p. (Translated from Russian by I. E. Sidorova).
Ferguson, S., and Secretariat, C.S.A. (2009). Review of aerial survey estimates for ringed seals (Phoca hispida) in western Hudson Bay. DFO Canadian Science Advisory Secretariat, Science Advisory Report 2009/004. Available at http://www.dfo-mpo.gc.ca/csas-sccs/Publications/SAR-AS/2009/2009_004-eng.htm
Ferguson, S.H., Stirling, I. and Mcloughlin, P.M. (2005). Climate change and ringed seal (Phoca hispida) recruitment in western Hudson Bay. Marine Mammal Science, 21(1), 121–135. https://doi.org/10.1111/j.1748-7692.2005.tb01212.x
Finley, K. J., Miller, G. W., Davis, R.A. and Koski, W.R. (1983). A distinctive large breeding population of ringed seals (Phoca hispida) inhabiting the Baffin Bay pack ice. Arctic, 36(2), 162–173. https://doi.org/10.14430/arctic2259
Fisk, A.T., de Wit, C.A., Wayland, M., Kuzyk, Z.Z., … and Muir, D.C.G. (2005). An assessment of the toxicological significance of anthropogenic contaminants in Canadian arctic wildlife. Science of the Total Environment, 351–352, 57‐93. https://doi.org/10.1016/j.scitotenv.2005.01.051
Fisk, A.T., Holst, M., Hobson, A., Duffe, J., Moisey, J. and Norstrom, R.J. (2002). Persistent organochlorine contaminants and enantiomeric signatures of chiral pollutants in ringed seals (Phoca hispida) collected on the east and west side of the Northwater polynya, Canadian Arctic. Archives of Environmental Contamination and Toxicology, 42, 118‐126. https://doi.org/10.1007/s002440010299
Freitas, C., Kovacs, K.M., Fedak, M.A. and Lydersen, C. (2008a). Ringed seal post-moulting movement tactics and habitat selection. Oecologia, 155(1), 193–204. https://doi.org/10.1007/s00442-007-0894-9
Freitas, C., Kovacs, K.M. and Lydersen, C. (2008b). Predicting habitat use by ringed seals (Phoca hispida) in a warming Arctic. Ecological Modelling, 217(1–2), 19–32. https://doi.org/10.1016/j.ecolmodel.2008.05.014
Frost, K.J., Lowry, L.F., Pendleton, G. and Nute, H.R. (2004). Factors affecting the observed densities of ringed seals, Phoca hispida, in the Alaskan Beaufort Sea, 1996–1999. Arctic, 57(2), 115–128. https://doi.org/10.14430/arctic489
Furgal, C.M., Innes, S. and Kovacs, K.M. (2002). Inuit spring hunting techniques and local knowledge of the ringed seal in Arctic Bay (Ikpiarjuk), Nunavut. Polar Research, 21(1), 1–16. https://doi.org/10.3402/polar.v21i1.6470
Gjertz, I., Kovacs, K. M., Lydersen, C. and Wiig, Ø. (2000). Movements and diving of adult ringed seals (Phoca hispida) in Svalbard. Polar Biology, 23, 651–656. https://doi.org/10.1007/s003000000143
Government of Greenland. (2012). Ministry of Fisheries, Hunting and Agriculture. Management and utilization of seals in Greenland. 39pp.
Hammill, M.O. and Smith, T.G. (1990). Application of removal sampling to estimate the density of ringed seals (Phoca hispida) in Barrow Strait, Northwest Territories. Canadian Journal of Fisheries and Aquatic Sciences, 47(2), 244–250. https://doi.org/10.1139/f90-027
Harding, K.C. and Härkönen, T.J. (1999). Development of the Baltic grey seal (Halichoerus grypus) and ringed seal (Phoca hispida) populations during the 20th century. Ambio, 28(7), 619–627. Available at https://www.researchgate.net/publication/279587941
Härkönen, T. (2008). Vikaresälen pressad av mildare klimat. Havet 2008, 89–90. Available at http://www.havet.nu/dokument/havet2008-vikaresal.pdf [In Swedish]
Harkonen, T., Jüssi, M., Jüssi, I., Verevkin, M., Dmitrieva, L., Helle, E., Sagitov, R. and Harding, K.C. (2008). Seasonal activity budget of adult Baltic ringed seals. PLoS ONE, 3, e2006. https://doi.org/10.1371/journal.pone.0002006
Härkönen, T., Stenman, O., Jüssi, M., Jüssi, I., Sagitov, R. and Verevkin, M. (1998). Population size and distribution of the Baltic ringed seal (Phoca hispida botnica). NAMMCO Scientific Publications, 1, 167–180. https://doi.org/10.7557/3.2986
Heide‐Jørgensen, M.P. and Lydersen, C. (1998). Ringed Seals in the North Atlantic. NAMMCO Scientific Publications, 1, 5–8. https://doi.org/10.7557/3.2978
Hezel , P. J., Zhang, X., Bitz, C. M., Kelly, B. P., and Massonnet, F. (2012). Projected decline in spring snow depth on Arctic sea ice caused by progressively later autumn open ocean freeze-up this century. Geophysical Research Letters, 39(17), L17505. https://doi.org/10.1029/2012GL052794
Holst, M., Stirling, I. and Hobson, K.A. (2001). Diet of ringed seals (Phoca hispida) on the east and west sides of the North Water Polynya, northern Baffin Bay. Marine Mammal Science, 17(4), 888–908. https://doi.org/10.1111/j.1748-7692.2001.tb01304.x
Hovelsrud, G.K., McKenna, M. and Huntington, H.P. (2008). Marine mammal harvests and other interactions with humans. Ecological Applications, 18(sp 2), 135‐147. https://doi.org/10.1890/06-0843.1
Hyvärinen, H., Sipilä, T., Kunnasranta, M. and Koskela, J.T. (1998). Mercury pollution and the Saimaa ringed seal (Phoca hispida saimensis). Marine Pollution Bulletin, 36(1), 76‐81. https://doi.org/10.1016/S0025-326X(98)90037-6
Iversen, M., Aars, J., Haug, T., Alsos, I.G., Lydersen, C., Bachmann, L. and Kovacs, K.M. (2013). The diet of polar bears (Ursus maritimus) from Svalbard, Norway, inferred from scat analysis. Polar Biology, 36(4), 561–571. https://doi.org/10.1007/s00300-012-1284-2
Jeffries, M.O., Richter-Menge, J.A. and Overland, J.E. (eds.). (2013). Arctic Report Card 2013. Available at https://www.arctic.noaa.gov/Report-Card
Johanessen, O.M., Miles, M.W. and Bjørgo, E. (1995). The Arctic’s shrinking sea ice. Nature, 376, 126-27. https://doi.org/10.1038/376126a0
Johansen, C.E., Lydersen, C., Aspholm, P.E., Haug, T. and Kovacs, K.M. (2010). Helminth parasites in ringed seals (Pusa hispida) from Svalbard, Norway with special emphasis on nematodes: Variation with age, sex, diet, and location of host. Journal of Parasitology, 96(5), 946–953. https://doi.org/10.1645/GE-1685.1
Kapel, F.O., Christiansen, J., Heide-Jørgensen, M.P., Härkönen, T., Born, E.W., Knutsen, L.Ø., Riget, F. and Teilmann, J. (1998). Netting and conventional tagging used to study movements of ringed seals (Phoca hispida) in Greenland. NAMMCO Scientific Publications, 1, 211–228. https://doi.org/10.7557/3.2990
Karlsson, O., Härkönen, T. and Bäcklin, B.-M. (2007). Seals on the increase [In Swedish – Sälar på uppgång]. Havet 2007, 84–89. Available at http://www.havet.nu/dokument/Havet2007-salar.pdf
Kelly, B. P., Badajos, O.H., Kunnasranta, M. and Moran, J. (2006). Timing and re‐interpretation of ringed seal surveys. Coastal Marine Institute University of Alaska Fairbanks, Final Report. 60 p. Available at https://www.researchgate.net/publication/292158758
Kelly, B. P., Badajos, O.H., Kunnasranta, M. and Moran, J., Martinez-Bakker, M., Wartzok, D. and Boveng, P. (2010a). Seasonal home ranges and fidelity to breeding sites among ringed seals. Polar Biology, 33, 1095–1109. https://doi.org/10.1007/s00300-010-0796-x
Kelly, B.P., Bengtson, J.L., Boveng, P.L., Cameron, M.F., Dahle, S.P., Jansen, J.K., Logerwell, E.A., Overland, J.E., Sabine, C.l., Waring, G.T. and Wilder, J. M. (2010b). Status Review of the ringed seal (Phoca hispida). U.S. Dep. Commer., NOAA Tech. Memo. NMFS-AFSC-212. 250pp. Available at http://www.afsc.noaa.gov/Publications/AFSC-TM/NOAA-TM-AFSC-212.pdf
Kelly, B.P. and Quakenbush, L.T. (1990). Spatiotemporal use of lairs by ringed seals (Phoca hispida). Canadian Journal of Zoology, 68(12), 2503–2512. https://doi.org/10.1139/z90-350
Kingsley, M.C.S. (1998). The number of ringed seals (Phoca hispida) in Baffin Bay and associated waters. NAMMCO Scientific Publications, 1, 181–196. https://doi.org/10.7557/3.2988
Kingsley, M.C.S. (1990). The status of the ringed seal, Phoca hispida, in Canada. Prepared for the Committee on the Status of Endangered Wildlife in Cananda. Canadian Field-Naturalist, 104, 138–145.
Kingsley, M.C.S. and Byers, T. (1998). Failure of reproduction in ringed seals (Phoca hispida) in Amundsen Gulf, Northwest Territories in 1984-1987. NAMMCO Scientific Publications, 1, 197–210. https://doi.org/10.7557/3.2989
Kostamo, A., Hyvärinen, H., Pellinen, J. and Kukkonen, J.V.K. (2002). Organochlorine concentrations in the Saimaa ringed seal (Phoca hispida saimensis) from Lake Haukivesi, Finland, 1981-2000. Environmental Toxicology and Chemistry, 21(77), 1368–1376. https://doi.org/10.1002/etc.5620210706
Kovacs, K. (ed.). (2014). Circumpolar ringed seal (Pusa hispida) monitoring. Norwegian Polar Institute, Report Series 143. 45pp. Available at http://brage.bibsys.no/xmlui/bitstream/id/195705/Rapport143.pdf
Kovacs, K.M., Aguilar, A., Aurioles, D., Burkanov, V., … and Trillmich, F. (2012). Global threats to pinnipeds. Marine Mammal Science, 28(2), 414–436. https://doi.org/10.1111/j.1748-7692.2011.00479.x
Kovacs, K., Lowry, L. and Härkönen, T. (IUCN SSC Pinniped Specialist Group). (2008). Pusa hispida. The IUCN Red List of Threatened Species. Version 2014.2. Available at http://www.iucnredlist.org/details/full/41672/0
Kovacs, K.M. and Lydersen, C. (2006). Population biology of ringed seals in Svalbard, Norway. Polar Research in Tromsø, 3–4.
Kovacs, K.M. and Lydersen, C. (2008). Climate change impacts on seals and whales in the North Atlantic Arctic and adjacent shelf seas. Science Progress, 91(2), 117–150. https://doi.org/10.3184/003685008X324010
Krafft, B.A., Kovacs, K.M., Andersen, M., Aars, J., Lydersen, C., Ergon, T. and Haug, T. (2006a). Abundance of ringed seals (Pusa hispida) in the fjords of Spitsbergen, Svalbard, during the peak molting period. Marine Mammal Science, 22(2), 394–412. https://doi.org/10.1111/j.1748-7692.2006.00035.x
Krafft, B. A., Kovacs, K. M., Frie, A. K., Haug, T. and Lydersen, C. (2006b). Growth and population parameters of ringed seals (Pusa hispida) from Svalbard, Norway, 2002–2004. ICES Journal of Marine Science, 63(6), 1136–1144. https://doi.org/10.1016/j.icesjms.2006.04.001
Krafft, B.A., Kovacs, K.M. and Lydersen, C. (2007). Distribution of sex and age groups of ringed seals Pusa hispida in the fast-ice breeding habitat of Kongsfjorden, Svalbard. Marine Ecology Progress Series, 335, 199–206. https://doi.org/10.3354/meps335199
Krupnik, I., Aporta, C., Gearheard, S., Laidler, G.J. and Kielsen Holm, L. (eds.). (2010). SIKU: Knowing Our Ice: Documenting Inuit Sea Ice Knowledge and Use. Springer Science and Business Media. https://doi.org/10.1007/978-90-481-8587-0
Labansen, A.L., Lydersen, C., Haug, T., and Kovacs, K.M. (2007). Spring diet of ringed seals (Phoca hispida) from northwestern Spitsbergen, Norway. ICES Journal of Marine Science, 64(6), 1246–1256. https://doi.org/10.1093/icesjms/fsm090
Labansen, A.L., Lydersen, C., Levermann, N., Haug, T. and Kovacs, K.M. (2011). Diet of ringed seals (Pusa hispida) from Northeast Greenland. Polar Biology, 34(2), 227–234. https://doi.org/10.1007/s00300-010-0874-0
Laidre, K.L., Stirling, I., Lowry, L.F., Wiig, Ø., Heide-Jørgensen, M.P. and Ferguson, S.H. (2008). Quantifying the sensitivity of Arctic marine mammals to climate-induced habitat change. Ecological Applications, 18(sp 2), 97–125. https://doi.org/10.1890/06-0546.1
Learmonth, J.A., Macleod, C D., Santos, M.B., Pierce, G.J., Crick, H.Q.P. and Robinson, R.A. (2006). Potential effects of climate change on marine mammals. Oceanography and Marine Biology: An Annual Review, 44, 431–446. Available at https://www.researchgate.net/publication/228351576
Leclerc, L.-M., Lydersen, C., Haug, T., Bachmann, L., Fisk, A.T. and Kovacs, K.M. (2012). A missing piece in the Arctic food web puzzle? Stomach contents of Greenland sharks sampled in Svalbard, Norway. Polar Biology, 35(8), 1197–1208. https://doi.org/10.1007/s00300-012-1166-7
Lunn, N. J., Stirling, I. and Nowicki, S.N. (1997). Distribution and abundance of ringed (Phoca hispida) and bearded seals (Erignathus barbatus) in western Hudson Bay. Canadian Journal of Fisheries and Aquatic Sciences, 54(4), 914–921. https://doi.org/10.1139/f96-346
Lydersen, C. (1998). Status and biology of ringed seals (Phoca hispida) in Svalbard. NAMMCO Scientific Publcations, 1, 46–62. https://doi.org/10.7557/3.2980
Lydersen, C., Assmy, P., Falk-Petersen, S., Kohler, J., … and Zajaczkowsk, M. (2014). The importance of tidewater glaciers for marine mammals and seabirds in Svalbard, Norway. Journal of Marine Systems, 129, 452–471. https://doi.org/10.1016/j.jmarsys.2013.09.006
Lydersen, C., Freitas, C. and Kovacs, K.M. (2007). Ringed seals need snow and ice. Klima, 1, 38–40.
Lydersen, C. and Kovacs, K.M. (2010). Svalbard’s resident marine mammals and the climate threat. In Bjørge, A., Lydersen, C., Skern-Mauritzen, M. and Wiig, Ø. (eds.), Marine Mammals, 64–67. Fisken og havet, special ed. 2-2010. 95pp.
Lydersen, C. and Kovacs, K. (2013). Walrus Odobenus rosmarus research in Svalbard, Norway, 2000- 2010. NAMMCO Scientific Publications, 9, 175–190. http://dx.doi.org/10.7557/3.2613
Moore, S.E. and Huntington, H.P. (2008). Arctic Marine Mammals and climate change: impacts and resilience. Ecological Applications, 18(sp 2), 157–165. https://doi.org/10.1890/06-0571.1
Meier, H. E. M., Descher, R. and Halkka, A. (2004). Simulated distributions of Baltic Sea-ice in warming climate and consequences for the winter habitat of the Baltic ringed seal. AMBIO, 33(4), 249–256. https://doi.org/10.1579/0044-7447-33.4.249
Miyazaki, N. (2002). Ringed, Caspian, and Baikal seals Pusa hispida, P. caspica, and P. sibirica. In W. F. Perrin, B. Wursig and J. G. M. Thewissen (eds.), Encyclopedia of Marine Mammals, 1033–1037. Academic Press.
McLaren, I. A. (1958). The biology of the ringed seal (Phoca hispida Schreber) in the eastern Canadian Arctic. Bulletin Fisheries Research Board of Canada, 118, 97pp. Available at https://www.researchgate.net/publication/284480542
Moore, S.E. and Huntington, H.P. (2008): Arctic marine mammals and climate change: impacts and resilience. Ecological Applications, 8(sp 2), 157–165. https://doi.org/10.1890/06-0571.1
Moulton, V.D., Richardson, W.J., Elliott, R.E., McDonald, T.L., Nations, C. and Williams, M.T. (2005). Effects of an offshore oil development on local abundance and distribution of ringed seals (Phoca hispida) of the Alaskan Beaufort Sea. Marine Mammal Science, 21(2), 217–242. https://doi.org/10.1111/j.1748-7692.2005.tb01225.x
Muir, D., Braune, B. DeMarch, B., Norstrom, R., Wagemann, R., Lockhart, L., Hargrave, B., Bright, D. Addison, R., Payne, J. and Reimer, K. (1999). Spatial and temporal trends and effects of contaminants in the Canadian Arctic marine ecosystem: a review. Science of the Total Environment, 230(1–3), 83–144. https://doi.org/10.1016/S0048-9697(99)00037-6
North Atlantic Marine Mammal Commission (NAMMCO). (1997a). Report of the Fourth Meeting of the Scientific Committee. In NAMMCO Annual Report 1996, 97–136. Tromsø, Norway. https://nammco.no/topics/annual-reports/
North Atlantic Marine Mammal Commission (NAMMCO). (1997b). Report of Scientific Committee ad hoc Working Group on ringed seals, Tòrshavn, 5–8 February 1996. In NAMMCO Annual Report 1996, 137–153. Tromsø, Norway. https://nammco.no/topics/annual-reports/
North Atlantic Marine Mammal Commission (NAMMCO). (2004). Report of the NAMMCO workshop on hunting methods for seals and walrus. North Atlantic Marine Mammal Commission, Tromsø, Norway. 60pp. https://www.nammco.no/webcronize/images/Nammco/735.pdf
North Atlantic Marine Mammal Commission (NAMMCO). (2006). Report of the NAMMCO workshop to address the problems of “Struck and Lost” in seal, walrus and whale hunting. Copenhagen, Denmark, 78pp. https://www.nammco.no/webcronize/images/Nammco/818.pdf
North Atlantic Marine Mammal Commission (NAMMCO). (2009). Report of the NAMMCO expert group meeting on best practices in the hunting and killing of seals. Copenhagen, Denmark. 30pp. https://www.nammco.no/webcronize/images/Nammco/930.pdf
Perovich, D., Gerland, S., Hendricks, S., Meier, W., Nicolaus, M., Richter-Menge1, J., Tschudi, M. (2013). Sea Ice. In Jeffries, M. O., J. A. Richter-Menge, and J. E. Overland (eds.), Arctic Report Card 2013. http://www.arctic.noaa.gov/reportcard
Pilfold, N.W., Derocher, A.E., Stirling, I. and Richardson, E. (2014). Polar bear predatory behaviour reveals seascape distribution of ringed seal lairs. Population Ecology, 56(1), 129–138. https://doi.org/10.1007/s10144-013-0396-z
Polder, A., Odland, J.O., Tkachev, A., Føreid, S., Savinova, T.N. and Skaare, J.U. (2003). Geographic variation of chlorinated pesticides, toxaphenes and PCBs in human milk from sub-arctic and Arctic locations in Russia. Science of the Total Environment, 306(1–3), 179–95. https://doi.org/10.1016/S0048-9697(02)00492-8
Reeves, R.R. (1998). Distribution, abundance and biology of ringed seals (Phoca hispida): an overview. NAMMCO Scientific Publications, 1, 9–45. https://doi.org/10.7557/3.2979
Reeves, R.R., Stewart, B.S. and Leatherwood, S. (1992). The Sierra Club Handbook of Seals and Sirenians. Sierra Club Books, San Francisco. 359pp.
Reeves, R.R., Wenzel, G. and Kingsley, M.C.S. (1998). Catch history of ringed seals Phoca hispida in Canada. NAMMCO Scientific Publications, 1, 100–129. https://doi.org/10.7557/3.2983
Reijnders, P.J.H. and de Ruiter-Dijkman, E.M. (1995). Toxicological and epidemiological significance of pollutants in marine mammals. In Blix, A.S., Walløe, L. and Ulltang, Ø. (eds.), Whales, seals, fish and man, 575–587. Elsevier: Amsterdam. 720pp. https://doi.org/10.1016/S0163-6995(06)80056-9
Rosing-Asvid, A. (2006). The influence of climate variability on polar bear (Ursus maritimus) and ringed seal (Pusa hispida) population dynamics. Canadian Journal of Zoology, 84(3), 357–364. https://doi.org/10.1139/z06-001
Ridoux, V., Hall, A.J., Steingrimsson, G. and Olafsson, G. (1998). An inadvertent homing experiment with a young ringed seal, Phoca hispida. Marine Mammal Science, 14(4), 883–888. https://doi.org/10.1111/j.1748-7692.1998.tb00774.x
Rigét, F., Muir, D., Kwan, M., Savinova, T., Nyman, M., Woshner, V. and O’Hara, T. (2005). Circumpolar pattern of mercury and cadmium in ringed seals. Science of the Total Environment, 351–352, 312–322. https://doi.org/10.1016/j.scitotenv.2004.05.032
Rigét, F., Vorkamp, K., Dietz, R., and Rastogi, S.C. (2006). Temporal trend studies on polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in ringed seals from East Greenland. Journal of Environmental Monitoring, 8, 1000‐1005. https://doi.org/10.1039/B609522D
Rosing-Asvid, A. (2010). Seals of Greenland. Ilinniusiorfik Undervisningsmiddelforlag. 144pp.
Routti, H., van Bavel, B., Letcher, R.J., Arukwe, A., Chu, S.G. and Gabrielsen, G.W. (2009). Concentrations, patterns and metabolites of organochlorine pesticides in relation to xenobiotic phase I and II enzyme activities in ringed seals (Phoca hispida) from Svalbard and the Baltic Sea. Environmental Pollution, 157(8–9), 2428–2434. https://doi.org/10.1016/j.envpol.2009.03.008
Ryg, M., Smith, T. G. and Øritsland, N. A. (1990). Seasonal changes in body mass and body composition of ringed seals (Phoca hispida) on Svalbard. Canadian Journal of Zoology, 68(3), 470–475. https://doi.org/10.1139/z90-069
Siegstad, H., Neve, P.B., Heide-Jørgensen, M.P. and Härkönen, T. (1998). Diet of the ringed seal (Phoca hispida) in Greenland. NAMMCO Scientific Publications, 1, 229–241. https://doi.org/10.7557/3.2991
Sipilä, T. (2006). The past and future size of the Saimaa ringed seal population. In Proceedings from the IVth International Symposium “Dynamics of game animal populations in Northern Europe”, 158‐160, Petrozavodsk, Karelia, Russia.
Sipilä, T. and Hyvärinen, H. (1998). Status and biology of Saimaa (Phoca hispida saimensis) and Ladoga (Phoca hispida ladogensis) ringed seals. NAMMCO Scientific Publications, 1, 83–99. https://doi.org/10.7557/3.2982
Sipilä, T. and Kokkonen, T. (2008). Saimaannorppakannan tila vuonna 2007. Ilmaston muutoksen vaikutus sekä sen aiheuttaman haitan kompensoinnista. Metsähallitus, Etelä- Suomen Luontopalvelut, julkaisematon asiakirja nro 657/41/2008.17 s. [In Finnish].
Sipilä, T., Koskela, J.T. and Kokkonen, T.S. (2007). Global warming – serious threat to Saimaa ringed seal population. Abstract. 17th Biennial Conference on the Biology of Marine Mammals. Cape Town, South- Africa.
Sonne‐Hansen, C., Dietz, R., Leifsson, P., Hyldstrup, L. and Rigét, F.F. (2002). Cadmium toxicity to ringed seals (Phoca hispida): an epidemiological study of possible cadmium‐induced nephropathy and osteodystrophy in ringed seals (Phoca hispida) from Qaanaaq in Northwest Greenland. Science of the Total Environment, 295, 167–181. https://doi.org/10.1016/S0048-9697(02)00092-X
Sonne, C., Aspholm, O., Dietz, R., Andersen, S., Berntssen, M.H.G. and Hylland, K. (2009). A study of metal concentrations and metallothionein binding capacity in liver, kidney and brain tissues of three Arctic seal species. Science of the Total Environment, 407, 6166–6172. https://doi.org/10.1016/j.scitotenv.2009.08.029
Stenman, O. and Pöyhönen, O. (2005). Food remains in the alimentary tracts of the Baltic grey and ringed seals (Abstract). In E. Helle, O. Stenman, and M. Wikman (eds.), Symposium on Biology and Management of Seals in the Baltic Area, 51‐53, 15‐18 February 2005. Helsinki, Finland, Finnish Game and Fisheries Research Institute.
Stirling, I. (2005). Reproductive rates of ringed seals and survival of pups in northwestern Hudson Bay, Canada, 1991–2000. Polar Biology, 28, 381–387. https://doi.org/10.1007/s00300-004-0700-7
Stirling, I. and Calvert, W. (1979). Ringed Seal. Mammals in the Seas, Vol. II pinniped species summaries and report on sirenians, 66–69. FAO Fisheries.
Stirling, I., Lunn, N.J. and Iacozza, J. (1999). Long trends in population ecology of polar bears in western Hudson Bay in relation to climatic change. Arctic, 52(3), 294–306. https://doi.org/10.14430/arctic935
Stirling, I., and Smith. T.G. (2004). Implications of warm temperatures and an unusual rain event on the survival of ringed seals on the coast of southeastern Baffin Island. Arctic, 57(1), 59–67. https://doi.org/10.14430/arctic483
Tedesco, M., Box, J.E., Cappelen, J., Fettweis, X., Jensen, T., Mote, T., Rennermalm, A.K., Smith, L.C., van de Wal, R.S.W. and Wahr, J. (2013). Greenland Ice Sheet. In Jeffries, M. O., J. A. Richter-Menge, and J. E. Overland (eds.), Arctic Report Card 2013. https://www.arctic.noaa.gov/Report-Card
Teilmann, J., Born, E.W. and Acquarone, M. (1999). Behaviour of ringed seals tagged with satellite transmitters in the North Water Polynya during fast-ice formation. Canadian Journal of Zoology, 77(12), 1934–1946. https://doi.org/10.1139/z99-163
Teilmann, J. and Kapel, F.O. (1998). Exploitation of ringed seals (Phoca hispida) in Greenland. NAMMCO Scientific Publications, 1, 130–151. https://doi.org/10.7557/3.2984
Tryland, M., Krafft, B.A., Lydersen, C., Kovacs, K.M., Thoresen, S.I. (2006). Serum chemistry values for free- ranging ringed seals (Pusa hispida) in Svalbard. Veterinary Clinical Pathology, 35(4), 405–412. https://doi.org/10.1111/j.1939-165X.2006.tb00156.x
Verevkin, M. V. (2002). The results of aircraft survey of Ladoga ringed seals. In P.I. Danilov and Vz Zimin (eds.), Dynamics of game animal populations in Northern Europe, 202–204. Proceedings of the 3rd International Symposium (16–20 June 2002, Sortavala, Karenlia, Russia). Petrozavodsk, Sortavala, Karenlia, Russia.
Verevkin, M. V., Medvedev, N. and Sipilä, T. (2006). By-catch mortality of the Ladoga seal (Phoca hispida ladogensis) population. Marine Mammals of the Holarctic, 4th International Conference, 130–33. St Petersburg, Russia.
Vincent-Chambellant, M. (2010). Ecology of ringed seals (Phoca hispida) in western Hudson Bay, Canada. Ph.D. dissertation, University of Manitoba, Winnipeg, Manitoba, Canada. 255pp.
Wathne, J.A., Haug, T. and Lydersen, C. (2000). Prey preference and niche overlap of ringed seals Phoca hispida and harp seals P. groenlandica in the Barents Sea. Marine Ecology Progress Series, 194, 233-239. https://doi.org/10.3354/meps194233
Wilson, S.J., Murray, J.L. and Huntington, H.P. (eds.) (1998). AMAP assessment report: Arctic pollution issues. Oslo: Arctic Monitoring and Assessment Programme. xii, 839pp. Available at https://www.amap.no/documents/doc/amap-assessment-report-arctic-pollution-issues/68
Wolkers, H., Krafft, B.A., van Bavel, B., Helgason, L.B., Lydersen, C. and Kovacs, K.M. (2008). Biomarker responses and decreasing contaminant levels in ringed seals (Pusa hispida) from Svalbard, Norway. Journal of Toxicology and Environmental Health, Part A, 71(15), 1009–1018. https://doi.org/10.1080/15287390801907558
WWF. (2013). Seals in Greenland: – An important component of culture and economy. The Last Ice Area Project. WWF Verdensnaturfonden, Svanevej 12, 2400 København NV.
Yurkowski, D.J., Chambellant, M. and Ferguson, S.H. (2011). Bacular and testicular growth and allometry in the ringed seal (Pusa hispida): evidence of polygyny? Journal of Mammalogy, 92(4), 803–810. https://doi.org/10.1644/10-MAMM-A-082.1