Methods for confirming the accuracy of age determination methods are reasonably well established in fishes, but the millions of routine age determinations which take place every year require their own quality control protocols. In contrast, methods for ensuring accuracy in age determination of monodontids and other marine mammals are still being developed. Here we review the basis and application of bomb radiocarbon to marine mammal age validation, highlighting its value for providing unambiguous estimates of age for belugas and other long-lived animals which form growth bands. Bomb radiocarbon is particularly useful for marine mammals, given that the age of an individual animal can be determined to within ±1-3 years, as long as it was alive during the 1960s. However, ongoing age determinations require careful monitoring to ensure that age interpretations remain consistent across ages and through time. Quality control protocols using reference collections of ageing material, in conjunction with age bias plots and measures of precision, are capable of detecting virtually all of the systematic ageing errors that often occur once age determinations of an animal become routine.
{"title":"Bomb dating, age validation and quality control of age determinations of monodontids and other marine mammals","authors":"S. Campana, R. Stewart","doi":"10.7557/3.2987","DOIUrl":"https://doi.org/10.7557/3.2987","url":null,"abstract":"Methods for confirming the accuracy of age determination methods are reasonably well established in fishes, but the millions of routine age determinations which take place every year require their own quality control protocols. In contrast, methods for ensuring accuracy in age determination of monodontids and other marine mammals are still being developed. Here we review the basis and application of bomb radiocarbon to marine mammal age validation, highlighting its value for providing unambiguous estimates of age for belugas and other long-lived animals which form growth bands. Bomb radiocarbon is particularly useful for marine mammals, given that the age of an individual animal can be determined to within ±1-3 years, as long as it was alive during the 1960s. However, ongoing age determinations require careful monitoring to ensure that age interpretations remain consistent across ages and through time. Quality control protocols using reference collections of ageing material, in conjunction with age bias plots and measures of precision, are capable of detecting virtually all of the systematic ageing errors that often occur once age determinations of an animal become routine.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2014-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71335741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Härkönen, O. Stenman, M. Jüssi, Ivar Jüssi, R. Sagitov, Michail Verevkin
The study reviews earlier investigations on the distribution and abundance of ringed seals ( Phoca hispida botnica ) in the Baltic and presents the first statistically robust results for the entire area. A critical review of earlier counts of ringed seals from the Gulf of Riga and the Gulf of Finland reveals grossly exaggerated population estimates in these regions. This is confirmed by results from the first comprehensive surveys in the entire area carried out during 1994-1996. The estimated hauled-out Baltic population in 1996 was about 5,510 ± 42% (± 95% confidence interval). Of this estimate 3,945 ± 1,732 (70%) were in the Gulf of Bothnia, 1,407 ± 590 (25%) in the Gulf of Riga and about 150 (5%) in the Gulf of Finland. Numbers in the Gulf of Bothnia have increased since 1988, but there are no data on trends in other areas, although numbers are low and half the local population in the Gulf of Finland may have died in a mass mortality in the autumn of 1991.
{"title":"Population size and distribution of the Baltic ringed seal ( Phoca hispida botnica )","authors":"T. Härkönen, O. Stenman, M. Jüssi, Ivar Jüssi, R. Sagitov, Michail Verevkin","doi":"10.7557/3.2986","DOIUrl":"https://doi.org/10.7557/3.2986","url":null,"abstract":"The study reviews earlier investigations on the distribution and abundance of ringed seals ( Phoca hispida botnica ) in the Baltic and presents the first statistically robust results for the entire area. A critical review of earlier counts of ringed seals from the Gulf of Riga and the Gulf of Finland reveals grossly exaggerated population estimates in these regions. This is confirmed by results from the first comprehensive surveys in the entire area carried out during 1994-1996. The estimated hauled-out Baltic population in 1996 was about 5,510 ± 42% (± 95% confidence interval). Of this estimate 3,945 ± 1,732 (70%) were in the Gulf of Bothnia, 1,407 ± 590 (25%) in the Gulf of Riga and about 150 (5%) in the Gulf of Finland. Numbers in the Gulf of Bothnia have increased since 1988, but there are no data on trends in other areas, although numbers are low and half the local population in the Gulf of Finland may have died in a mass mortality in the autumn of 1991.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"1 1","pages":"167-180"},"PeriodicalIF":0.0,"publicationDate":"2014-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71335698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With the purpose of determining the distribution and abundance of ringed seals ( Phoca hispida ) hauling out on the ice, systematic strip census aerial surveys were flown in the Kong Oscars Fjord, Scoresby Sund and adjacent areas (between approximately 70°N and 72°30'N in eastern Greenland) from 7 to 13 June 1984. The study area comprised approximately 18,500 km2 mainly covered with smooth one-year-old shore-fast ice. The survey effort was concentrated in the afternoon during the presumed peak haul-out period. Main emphasis was given to surveying the Kong Oscars Fjord/Davy Sund and the Scoresby Sund/Hurry Fjord areas which were surveyed twice. Average densities in various sub-areas varied between 0.3 and 2.9 seals/km2 and were similar to those reported from other Arctic areas. No significant differences in densities were found between sets of surveys of the same sub-areas. The mean density (2.00 seals/km2, SD=0.22) in the Scoresby Sund area was significantly higher than that found in Kong Oscars Fjord (1.04 seals/km SD=0.15) probably reflecting a higher overall marine productivity in Scoresby Sund. The sum of the point estimates of the visible part of the population in the different sub-areas was 28,882 seals.
{"title":"Abundance of ringed seals ( Phoca hispida ) in the Kong Oscars Fjord, Scoresby Sund and adjacent areas in eastern Greenland","authors":"E. Born, J. Teilmann, F. Rigét","doi":"10.7557/3.2985","DOIUrl":"https://doi.org/10.7557/3.2985","url":null,"abstract":"With the purpose of determining the distribution and abundance of ringed seals ( Phoca hispida ) hauling out on the ice, systematic strip census aerial surveys were flown in the Kong Oscars Fjord, Scoresby Sund and adjacent areas (between approximately 70°N and 72°30'N in eastern Greenland) from 7 to 13 June 1984. The study area comprised approximately 18,500 km2 mainly covered with smooth one-year-old shore-fast ice. The survey effort was concentrated in the afternoon during the presumed peak haul-out period. Main emphasis was given to surveying the Kong Oscars Fjord/Davy Sund and the Scoresby Sund/Hurry Fjord areas which were surveyed twice. Average densities in various sub-areas varied between 0.3 and 2.9 seals/km2 and were similar to those reported from other Arctic areas. No significant differences in densities were found between sets of surveys of the same sub-areas. The mean density (2.00 seals/km2, SD=0.22) in the Scoresby Sund area was significantly higher than that found in Kong Oscars Fjord (1.04 seals/km SD=0.15) probably reflecting a higher overall marine productivity in Scoresby Sund. The sum of the point estimates of the visible part of the population in the different sub-areas was 28,882 seals.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"1 1","pages":"152-166"},"PeriodicalIF":0.0,"publicationDate":"2014-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71335688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The ringed seal ( Phoca hispida ) has always been a staple in the diet and household economy of Inuit in Canada. The present paper was prepared at the request of the NAMMCO Scientific Committee to support their assessment of ringed seal stocks in the North Atlantic Basin and adjacent arctic and subarctic waters. Specifically, our objective was to evaluate recent and current levels of use of ringed seals by Canadian Inuit. Annual removals probably were highest (possibly greater than 100,000) in the 1960s and 1970s, a period when sealskin prices were particularly strong. Catches declined substantially in the 1980s following a collapse in sealskin prices, presumably related to the European trade ban on skins from newborn harp and hooded seals ( Phoca groenlandica and Cystophora cristata , respectively). Recent catch levels throughout Canada (1980s and early 1990s) are believed to be in the order of 50,000 to 65,000 ringed seals, with a total average annual kill (including hunting loss) in the high tens of thousands. No reliable system is in place to monitor catches of ringed seals, so any estimate must be derived from a heterogeneous array of sources.
{"title":"Catch history of ringed seals ( Phoca hispida ) in Canada","authors":"R. Reeves, G. Wenzel, M. Kingsley","doi":"10.7557/3.2983","DOIUrl":"https://doi.org/10.7557/3.2983","url":null,"abstract":"The ringed seal ( Phoca hispida ) has always been a staple in the diet and household economy of Inuit in Canada. The present paper was prepared at the request of the NAMMCO Scientific Committee to support their assessment of ringed seal stocks in the North Atlantic Basin and adjacent arctic and subarctic waters. Specifically, our objective was to evaluate recent and current levels of use of ringed seals by Canadian Inuit. Annual removals probably were highest (possibly greater than 100,000) in the 1960s and 1970s, a period when sealskin prices were particularly strong. Catches declined substantially in the 1980s following a collapse in sealskin prices, presumably related to the European trade ban on skins from newborn harp and hooded seals ( Phoca groenlandica and Cystophora cristata , respectively). Recent catch levels throughout Canada (1980s and early 1990s) are believed to be in the order of 50,000 to 65,000 ringed seals, with a total average annual kill (including hunting loss) in the high tens of thousands. No reliable system is in place to monitor catches of ringed seals, so any estimate must be derived from a heterogeneous array of sources.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"1 1","pages":"100-129"},"PeriodicalIF":0.0,"publicationDate":"2014-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71335643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The ringed seal ( Phoca hispida ) is the most important game for the Inuit hunters of Greenland, providing many of the basic needs in the original culture. It is distributed all around Greenland with the main distribution north of 69°N on the west coast and north of 66°N on the east coast. During 1974-76, studies were conducted in the most important ringed seal catching area, Upernavik, Northwest Greenland, and a total of 7,089 ringed seals were sampled. The methods used for catching ringed seals were categorised into five different groups. The most common hunting method used in the municipality of Upernavik during 1974-76 was netting under the ice, accounting for almost half of the total annual catch. Seals shot on the ice and seals shot at the ice edge accounted for one fifth and one tenth of the annual catch, respectively. In this region seals shot in open water made up about one fifth of the annual catch of ringed seals, while netting in open water contributed only a few percent. Of the seals sampled in Upernavik in 1974-76, 60% were males and 40% were females. In the ringed seal samples collected all around Greenland in the 1980s and 1990s the males comprised 56% and the females 44% (n=923). Similar ratios were found for all age classes and for all hunting methods suggesting either a skewed sex ratio in the ringed seal stock(s) around Greenland or a difference in availability to the hunters of male and female ringed seals. In tagging experiments a higher mobility was found for females than for males, which suggests differences in the behaviour of the two sexes. Catch and trade statistics on ringed seals are reviewed and evaluated for the period of 1954 until 1994, and the seasonal and regional variation is examined. The peak season for ringed seal hunting in Greenland as a whole is from January through May. This is particularly evident for the northern regions, where relatively few ringed seals are taken during the open water season from June to September. In the southern regions, however, the great majority of ringed seals are caught in open water. In all regions, the catch of ringed seals showed great annual and long-term variation. The variations were not identical in all regions, but similar trends were found for Northwest and Central West, and for Southwest and South. From 1954 to 1994 there was a general, significant increase in the reported catches of ringed seals in west Greenland. For Greenland overall, the catch of ringed seals was around 43,000 per year in the 1950s, peaked in the late 1970s at almost 100,000 per year, but since decreased to about 70,000 in the early 1990s.
{"title":"Exploitation of ringed seals ( Phoca hispida ) in Greenland","authors":"J. Teilmann, F. O. Kapel","doi":"10.7557/3.2984","DOIUrl":"https://doi.org/10.7557/3.2984","url":null,"abstract":"The ringed seal ( Phoca hispida ) is the most important game for the Inuit hunters of Greenland, providing many of the basic needs in the original culture. It is distributed all around Greenland with the main distribution north of 69°N on the west coast and north of 66°N on the east coast. During 1974-76, studies were conducted in the most important ringed seal catching area, Upernavik, Northwest Greenland, and a total of 7,089 ringed seals were sampled. The methods used for catching ringed seals were categorised into five different groups. The most common hunting method used in the municipality of Upernavik during 1974-76 was netting under the ice, accounting for almost half of the total annual catch. Seals shot on the ice and seals shot at the ice edge accounted for one fifth and one tenth of the annual catch, respectively. In this region seals shot in open water made up about one fifth of the annual catch of ringed seals, while netting in open water contributed only a few percent. Of the seals sampled in Upernavik in 1974-76, 60% were males and 40% were females. In the ringed seal samples collected all around Greenland in the 1980s and 1990s the males comprised 56% and the females 44% (n=923). Similar ratios were found for all age classes and for all hunting methods suggesting either a skewed sex ratio in the ringed seal stock(s) around Greenland or a difference in availability to the hunters of male and female ringed seals. In tagging experiments a higher mobility was found for females than for males, which suggests differences in the behaviour of the two sexes. Catch and trade statistics on ringed seals are reviewed and evaluated for the period of 1954 until 1994, and the seasonal and regional variation is examined. The peak season for ringed seal hunting in Greenland as a whole is from January through May. This is particularly evident for the northern regions, where relatively few ringed seals are taken during the open water season from June to September. In the southern regions, however, the great majority of ringed seals are caught in open water. In all regions, the catch of ringed seals showed great annual and long-term variation. The variations were not identical in all regions, but similar trends were found for Northwest and Central West, and for Southwest and South. From 1954 to 1994 there was a general, significant increase in the reported catches of ringed seals in west Greenland. For Greenland overall, the catch of ringed seals was around 43,000 per year in the 1950s, peaked in the late 1970s at almost 100,000 per year, but since decreased to about 70,000 in the early 1990s.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"1 1","pages":"130-151"},"PeriodicalIF":0.0,"publicationDate":"2014-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71335681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Saimaa ( Phoca hispida saimensis ) and Ladoga ( P. h. ladogensis ) seals are subspecies of ringed seals that live in freshwater lakes. The founding populations for these two subspecies became separated from Arctic ringed seals ( P. h. hispida ) during the last ice age. The Saimaa seal population currently numbers approximately 200 seals with 36 - 40 pups born annually. The Ladoga seal population contains at least 5,000 seals. The weight of adult animals in Lake Saimaa is 45-100 kg (mean 62 kg) and in Lake Ladoga adults weigh 32-56 kg (mean 47 kg). The lanugo of Saimaa seals is grey. Normally pups in Lake Ladoga are born with white lanugo, although some pups have been found that have black hairs in the natal pelt. Adult Saimaa seal vary a lot in colour, ranging from dark to pale animals, but all colour morphs have regular ringed patterns on the pelt. Ladoga seals are usually quite dark, with irregular, light ringed patterns. Saimaa seals are usually found hauled out alone or in pairs along shorelines. Ladoga seals haul out in herds of up to 300 animals, and are very vocal when they are hauled out. The lairs of Saimaa seals are situated in snowdrifts adjacent to shorelines of islets, which are the only places where snow piles up in Lake Saimaa. Most Ladoga seal lairs are situated near hummocked or ridged ice along the shoreline of the lake, but some lairs are also found along the shorelines of islets in northern Lake Ladoga. Saimaa seals are an endangered population. The main threats to these seals are fisheries conducted using nets and destruction of breeding habitat. The Ladoga seal is vulnerable, and it also is threatened by fishing. Mercury in both lakes presents an anthropogenic risk factor, but present levels probably do not affect the breeding of either seal population.
{"title":"Status and biology of Saimaa ( Phoca hispida saimensis ) and Ladoga ( Phoca hispida ladogensis ) ringed seals","authors":"T. Sipilä, H. Hyvärinen","doi":"10.7557/3.2982","DOIUrl":"https://doi.org/10.7557/3.2982","url":null,"abstract":"Saimaa ( Phoca hispida saimensis ) and Ladoga ( P. h. ladogensis ) seals are subspecies of ringed seals that live in freshwater lakes. The founding populations for these two subspecies became separated from Arctic ringed seals ( P. h. hispida ) during the last ice age. The Saimaa seal population currently numbers approximately 200 seals with 36 - 40 pups born annually. The Ladoga seal population contains at least 5,000 seals. The weight of adult animals in Lake Saimaa is 45-100 kg (mean 62 kg) and in Lake Ladoga adults weigh 32-56 kg (mean 47 kg). The lanugo of Saimaa seals is grey. Normally pups in Lake Ladoga are born with white lanugo, although some pups have been found that have black hairs in the natal pelt. Adult Saimaa seal vary a lot in colour, ranging from dark to pale animals, but all colour morphs have regular ringed patterns on the pelt. Ladoga seals are usually quite dark, with irregular, light ringed patterns. Saimaa seals are usually found hauled out alone or in pairs along shorelines. Ladoga seals haul out in herds of up to 300 animals, and are very vocal when they are hauled out. The lairs of Saimaa seals are situated in snowdrifts adjacent to shorelines of islets, which are the only places where snow piles up in Lake Saimaa. Most Ladoga seal lairs are situated near hummocked or ridged ice along the shoreline of the lake, but some lairs are also found along the shorelines of islets in northern Lake Ladoga. Saimaa seals are an endangered population. The main threats to these seals are fisheries conducted using nets and destruction of breeding habitat. The Ladoga seal is vulnerable, and it also is threatened by fishing. Mercury in both lakes presents an anthropogenic risk factor, but present levels probably do not affect the breeding of either seal population.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"1 1","pages":"83-99"},"PeriodicalIF":0.0,"publicationDate":"2014-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71335630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents a review of available published and unpublished material on the ringed seal ( Phoca hispida ) in the western part of the Russian Arctic, including the White, Barents and Kara seas. The purpose of the review is to discuss the status of ringed seal stocks in relation to their primary habitat, the history of sealing, and a recent harvest of the species in the region. The known primary breeding habitats for this species are in the White Sea, the south-western part of the Barents Sea, and in the coastal waters of the Kara Sea, which are seasonally covered by shore-fast ice. The main sealing sites are situated in the same areas. Female ringed seals become mature by the age of 6, and males by the age of 7. In March-April a female gives birth to one pup in a breeding lair constructed in the shore-fast ice. The most important prey species for ringed seals in the western sector of the Russian Arctic are pelagic fish and crustaceans. The maximum annual sealing level for the region was registered in the first 70 years of the 20th century: the White Sea maximum (8,912 animals) was registered in 1912; the Barents Sea maximum (13,517 animals) was registered in 1962; the Kara Sea maximum (13,200 animals) was registered in 1933. Since the 1970s, the number of seals harvested has decreased considerably. There are no data available for the number of seals harvested annually by local residents for their subsistence.
{"title":"The ringed seal ( Phoca hispida ) in the western Russian Arctic","authors":"S. Belikov, A. Boltunov","doi":"10.7557/3.2981","DOIUrl":"https://doi.org/10.7557/3.2981","url":null,"abstract":"This paper presents a review of available published and unpublished material on the ringed seal ( Phoca hispida ) in the western part of the Russian Arctic, including the White, Barents and Kara seas. The purpose of the review is to discuss the status of ringed seal stocks in relation to their primary habitat, the history of sealing, and a recent harvest of the species in the region. The known primary breeding habitats for this species are in the White Sea, the south-western part of the Barents Sea, and in the coastal waters of the Kara Sea, which are seasonally covered by shore-fast ice. The main sealing sites are situated in the same areas. Female ringed seals become mature by the age of 6, and males by the age of 7. In March-April a female gives birth to one pup in a breeding lair constructed in the shore-fast ice. The most important prey species for ringed seals in the western sector of the Russian Arctic are pelagic fish and crustaceans. The maximum annual sealing level for the region was registered in the first 70 years of the 20th century: the White Sea maximum (8,912 animals) was registered in 1912; the Barents Sea maximum (13,517 animals) was registered in 1962; the Kara Sea maximum (13,200 animals) was registered in 1933. Since the 1970s, the number of seals harvested has decreased considerably. There are no data available for the number of seals harvested annually by local residents for their subsistence.","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"1 1","pages":"63-82"},"PeriodicalIF":0.0,"publicationDate":"2014-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71335620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Preface- Ringed Seals in the North Atlantic","authors":"S. Grønvik","doi":"10.7557/3.2977","DOIUrl":"https://doi.org/10.7557/3.2977","url":null,"abstract":"","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"1 1","pages":"3"},"PeriodicalIF":0.0,"publicationDate":"2014-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71335527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The ringed seal ( Phoca hispida ) has a circumpolar Arctic distribution. Because of its great importance to northern communities and its role as the primary food of polar bears ( Ursus maritimus ) the ringed seal has been studied extensively in Canada, Alaska, Russia, Svalbard and Greenland as well as in the Baltic Sea and Karelian lakes. No clear-cut boundaries are known to separate ringed seal stocks in marine waters. Adult seals are thought to be relatively sedentary, but sub-adults sometimes disperse over long distances. Stable ice with good snow cover is considered the most productive habitat although production in pack ice has been little studied. Populations appear to be structured so that immature animals and young adults are consigned to sub-optimal habitat during the spring pupping and breeding season. Annual production in ringed seal populations, defined as the pup percentage in the total population after the late winter pupping season, is probably in the order of 18-24%. Most estimates of maximum sustainable yield are in the order of 7%. The world population of ringed seals is at least a few million. Methods of abundance estimation have included aerial surveys, dog searches and remote sensing of lairs and breathing holes, acoustic monitoring, correlation analysis by reference to sizes of polar bear populations, and inference from estimated energy requirements of bear populations. Aerial strip survey has been the method of choice for estimating seal densities over large areas. Adjustment factors to account for seals not hauled out at the time of the survey, for seals that dove ahead of the aircraft, and for seals on the ice within the surveyed strip but not detected by the observers, are required for estimates of absolute abundance. Male and female ringed seals are sexually mature by 5-7 years of age (earlier at Svalbard). Pupping usually occurs in March or early April and is followed by 5-7 weeks of lactation. Breeding takes place in mid to late May, and implantation is delayed for about 3 months. In at least some parts of their range, ringed seals feed mainly on schooling gadids from late autumn through early spring and on benthic crustaceans and polar cod ( Boreogadus saida ) from late spring through summer. Little feeding is done during the moult, which takes place in late spring and early summer. Pelagic crustaceans offshore and mysids inshore become important prey in late summer and early autumn in some areas. Ringed seals have several natural predators, the most important of which is the polar bear in most arctic regions. Arctic foxes ( Alopex lagopus ) kill a large percentage of pups in some areas. From a conservation perspective, the ringed seal appears to be secure. Levels of exploitation of arctic populations have usually been considered sustainable, except in the Okhotsk Sea. Large fluctuations in production of ringed seals in the Beaufort Sea and Amundsen Gulf are thought to be driven by natural variability in environmenta
{"title":"Distribution, abundance and biology of ringed seals ( Phoca hispida ): an overview","authors":"R. Reeves","doi":"10.7557/3.2979","DOIUrl":"https://doi.org/10.7557/3.2979","url":null,"abstract":"The ringed seal ( Phoca hispida ) has a circumpolar Arctic distribution. Because of its great importance to northern communities and its role as the primary food of polar bears ( Ursus maritimus ) the ringed seal has been studied extensively in Canada, Alaska, Russia, Svalbard and Greenland as well as in the Baltic Sea and Karelian lakes. No clear-cut boundaries are known to separate ringed seal stocks in marine waters. Adult seals are thought to be relatively sedentary, but sub-adults sometimes disperse over long distances. Stable ice with good snow cover is considered the most productive habitat although production in pack ice has been little studied. Populations appear to be structured so that immature animals and young adults are consigned to sub-optimal habitat during the spring pupping and breeding season. Annual production in ringed seal populations, defined as the pup percentage in the total population after the late winter pupping season, is probably in the order of 18-24%. Most estimates of maximum sustainable yield are in the order of 7%. The world population of ringed seals is at least a few million. Methods of abundance estimation have included aerial surveys, dog searches and remote sensing of lairs and breathing holes, acoustic monitoring, correlation analysis by reference to sizes of polar bear populations, and inference from estimated energy requirements of bear populations. Aerial strip survey has been the method of choice for estimating seal densities over large areas. Adjustment factors to account for seals not hauled out at the time of the survey, for seals that dove ahead of the aircraft, and for seals on the ice within the surveyed strip but not detected by the observers, are required for estimates of absolute abundance. Male and female ringed seals are sexually mature by 5-7 years of age (earlier at Svalbard). Pupping usually occurs in March or early April and is followed by 5-7 weeks of lactation. Breeding takes place in mid to late May, and implantation is delayed for about 3 months. In at least some parts of their range, ringed seals feed mainly on schooling gadids from late autumn through early spring and on benthic crustaceans and polar cod ( Boreogadus saida ) from late spring through summer. Little feeding is done during the moult, which takes place in late spring and early summer. Pelagic crustaceans offshore and mysids inshore become important prey in late summer and early autumn in some areas. Ringed seals have several natural predators, the most important of which is the polar bear in most arctic regions. Arctic foxes ( Alopex lagopus ) kill a large percentage of pups in some areas. From a conservation perspective, the ringed seal appears to be secure. Levels of exploitation of arctic populations have usually been considered sustainable, except in the Okhotsk Sea. Large fluctuations in production of ringed seals in the Beaufort Sea and Amundsen Gulf are thought to be driven by natural variability in environmenta","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"1 1","pages":"9-45"},"PeriodicalIF":0.0,"publicationDate":"2014-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71335572","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Introduction- Ringed seals in the North Atlantic","authors":"M. Heide‐Jørgensen, C. Lydersen","doi":"10.7557/3.2978","DOIUrl":"https://doi.org/10.7557/3.2978","url":null,"abstract":"","PeriodicalId":30560,"journal":{"name":"NAMMCO Scientific Publications","volume":"1 1","pages":"5-8"},"PeriodicalIF":0.0,"publicationDate":"2014-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71335532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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