|Scientific Name:||Cystophora cristata|
|Species Authority:||(Erxleben, 1777)|
Cystophora antillarum Gray, 1849
Phoca cristata Erxleben, 1777
|Taxonomic Notes:||Morphometric and allozyme analyses, as well as molecular genetics analyses, suggest that Hooded Seals are a single panmictic population (Wiig and Lie 1984, Sundt et al. 1994, Coltman et al. 2007). Three breeding stocks are commonly recognized: Gulf of Saint Lawrence and the Front (east coast of Canada); Davis Strait; and the West Ice (north of the island of Jan Mayen) (Sergeant 1974, Lavigne and Kovacs 1988).|
|Red List Category & Criteria:||Vulnerable A3c ver 3.1|
|Facilitator/Compiler(s):||Lowry, L., Ahonen, H., Pollock, C.M., Chiozza, F. and Battistoni, A.|
Although there is no reliable, current estimate for Hooded Seal abundance, the population is thought to be relatively large, numbering some few hundreds of thousands. The West Ice stock has been surveyed four times in the last 15 years, most recently in 2012, and it has been declining at a rate of 3.7%/year. The stock in Canadian waters increased during the 1980s and 1990s but the rate of increase was declining over time and with no surveys since 2005 there is no way to know the recent or current trend. However, with changing sea ice conditions reducing the pack ice habitat needed by all Hooded Seals for pupping and molting, there is good reason to believe that numbers in all stocks might be declining. Assuming that the entire population will decline at 3.7%/year (which is the West Ice rate of decline currently), the three generation reduction would be 75% which qualifies Hooded Seals for listing as Endangered under criterion A3c. Even if the overall rate of decline were only 1%/year the three generation decline would be 32%, which would qualify Hooded Seals as being Vulnerable. Given that the population is still relatively large, and there are uncertainties about the rate of future decline we opt for the more modest listing of Vulnerable under criterion A3c for Hooded Seals at this time.
|Previously published Red List assessments:|
|Range Description:||Hooded Seals are found at high latitudes in the North Atlantic, and seasonally they extend their range north into the Arctic Ocean. They breed on pack ice and are associated with it much of the year, though they can spend significant periods of time pelagic, without hauling out (Lavigne and Kovacs 1988, Folkow and Blix 1999, Anderson et al. 2009, Folkow et al. 2010, Kovacs et al. 2011a). There are four major pupping areas: near the Magdalen Islands in the Gulf of Saint Lawrence, north of Newfoundland in an area known as the Front, in central Davis Strait, and in the West Ice in the Greenland Sea near the island of Jan Mayen (Sergeant 1974). Hooded Seals sometimes wander extensively; young animals have come ashore as far south as Portugal and the Canary Islands in Europe and south into the Caribbean in the West Atlantic (Kovacs and Lavigne 1986, Rice 1998). They have also been found outside the Atlantic Region, in the North Pacific and even as far south as California (Burns and Gavin 1980, Dudley 1992, Fay 1995). Since the mid 1990s, large numbers of vagrant Hooded Seals have been found outside the Arctic in some years (Mignucci-Giannoni and Haddow 2002, Harris and Gupta 2006). Stranded Hooded Seals are increasingly common on Sable Island, Canada, and along the New England coast and in the Saint Lawrence River area, particularly in years with sparse sea ice conditions (Harris et al. 2001, Lucas and Daoust 2002, Truchon et al. 2013).|
Native:Canada; Greenland; Iceland; Norway
Vagrant:Antigua and Barbuda; Bahamas; Bermuda; Denmark; France; Germany; Ireland; Portugal; Puerto Rico; Russian Federation; Saint Barthélemy; Spain; Svalbard and Jan Mayen; Turks and Caicos Islands; United Kingdom; United States
|FAO Marine Fishing Areas:|
Atlantic – northeast; Atlantic – northwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Hooded Seal populations are usually assessed based on aerial survey counts of pups at whelping areas in the pack ice, combined with population models to extrapolate to total population size. In Canadian waters, pup production estimates for the Front have been: 1978—26,000 (Winters and Bergflodt 1978); 1984—62,400 (Bowen et al. 1987); 1985—61,400 (Hay et al. 1985); 1990—83,100 (Hammill et al. 1992); and 2005—107,013 (Hammill and Stenson 2006). These figures indicate an increase of 5.2%/year during 1978-2005, 2.6%/year during 1984-2005, and 1.7%/year during 1990-2005. Pup production estimates for Gulf region in Canada have been: 1991—2,006 (Hammill et al. 1992); 1998/99—2,000 (ICES 2001); and 2005—6,620 (Hammill and Stenson 2006). Comparing counts in 1991 and 2005 suggests that the number of animals in the Gulf increased by 8.5%/year during that period. Only two estimates are available for Davis Strait, 19,000 pups in 1984 (Bowen et al. 1987) and 3,346 in 2005 (Hammill and Stenson 2006); this suggests a decline of 8.2%/year. Hammill and Stenson (2006, 2007) concluded that these estimates suggest a moderate increase both in pup production and population size between the mid 1980s and 2005 in the northwest Atlantic as a whole. Surveys carried out at all three whelping areas in 2005 produced an estimate of 116,900 pups born. The size of the whole population, modeled based on the pup counts, was estimated as 592,000 (Waring et al. 2007). No more recent survey information is available for the northwest Atlantic breeding areas (ICES 2013a) and the down-turn in the number of animals in the Davis Strait in the 2005 survey is concerning, especially given its magnitude and the continued high hunting levels of this species in West Greenland.|
Hooded Seals in the West Ice have shown, and continue to show, a declining trend. Pup production estimates have been: 1997—23,762 (ICES 2013a); 2005—15,250 (Salberg et al. 2008); 2007—16,140 (ICES 2013a); and 2012—13,655 (Øigård et al. 2014). Comparing the estimates for 1997 and 2012 indicates a population decrease of 3.7%/year and a reduction in population size of 43% in 15 years (1.2 generations using the generation time of 12.8 years calculated by Pacifici et al. 2013). The most recent estimate of the total size of this population is 82,830 (SE=8,028) and models suggest a continued decline of approximately 7% per year in the coming decade (Øigård et al. 2014). This stock is less than 10% of its abundance observed some 60 years ago (ICES 2013a). Overhunting was clearly involved in the collapse of this stock as quotas were being set for a population size much larger than it actually was. However, the cause of the significant, on-going decline in this population is thought to be related to climate change induced alternation of its sea ice breeding habitat and increased predation by Polar Bears and Killer Whales in the pupping areas (Øigard et al. 2014) but prey availability might also be an issue.
Summing the most recent estimates for all stocks (three regions in the northwest Atlantic–2005; West Ice stock–2012) gives a total Hooded Seal population size estimate of approximately 675,000. However, with no recent surveys in Canada or Greenland this estimate cannot be considered reliable.
Available data show clearly that the Greenland Sea population has declined in recent years. With no surveys in the past 10 years, the trend for the northwestern stocks is unknown. Pup counts at the Front increased through until 2005, but with the rate of increase declining over time. With 15 years between surveys, it is possible that the population had peaked and started to decline before 2005. Since 2005, there have been several years with bad ice conditions when few Hooded Seals were sighted on the ice and it is not known whether any successful reproduction at all took place for the Gulf segment of the population (Stenson and Hammill 2014). Given the available data, the best estimate for the current population trend for Hooded Seals is -3.7%/year.
Because of their preference for heavy sea ice conditions for breeding, it is unlikely that Hooded Seals will continue to breed in their southern-most breeding areas in future. This species has been deemed one the most sensitive Arctic/subarctic marine mammal species to the impacts of climate change (Laidre et al. 2008).
|Current Population Trend:||Unknown|
|Habitat and Ecology:||Hooded Seals are a sexually dimorphic ice-breeding pinniped. Adult males average 2.5 m in length and weigh 300 kg (Kovacs and Lavigne 1986), with large animals reaching over 400 kg (Kovacs 2002). Adult females are smaller, averaging 2.2 m and 160 kg, but can reach 300 kg. Pups are born at approximately 1 m in length and 24 kg (Kovacs and Lavigne 1992).|
Hooded Seals pup on pack ice late in the spring season, when the pack is already breaking up. The breeding season for this polygynous species is very short, usually lasting only about 2.5 weeks. Males attend a single female and her pup at a time, sequentially re-establishing with a new female if the male is competitively successful (Kovacs 1990). Mating takes place in the water (Boness et al. 1988). Hooded Seals have the shortest lactation period of any mammal, with most pups nursing for only four days (Bowen et al. 1985). Pups weigh an average of 48 kg at weaning, and on average double their birth mass in the short nursing period (Kovacs and Lavigne 1992, Lydersen et al. 1997). The short reproductive period is energetically advantageous to both males and females, with relative losses in body mass being small for both sexes compared to other phocid Seals (Kovacs and Lavigne 1992, Kovacs et al. 1996, Lydersen and Kovacs 1999).
Hooded Seals moult in July, with each breeding stock congregating on sea ice north of their respective whelping areas. If mixing does occur, the degree to which it takes place is unknown. Following the moulting period they disperse in the North Atlantic (Folkow and Blix 1999, Folkow et al. 1996, Andersen et al. 2009, Kovacs et al. 2011a). Apart from the breeding and moulting periods when Hooded Seals form loose aggregations in specific areas, they are thought to live quite solitary lives. However, little is known about them outside those periods. Groups of females and young animals have been seen at the northern ice edge in summer, but it is not known whether the groups are socially facilitated or solely the result of concentrations of prey. Hooded Seal longevity is 25-30 years (Kovacs 2002).
Hooded Seals are very capable divers that spend extensive periods at sea without hauling out (e.g., Folkow and Blix 1999, Andersen et al. 2013). Most of their dives are from 100-600 m in depth and last 5-25 minutes, however, very deep dives to over 1,000 m and dives lasting almost an hour have been recorded (Folkow et al. 1996, Lydersen et al. unpubl. data). Similar to Elephant Seals, Hooded Seals perform drift dives, in which buoyancy controls their movements through the water column (Andersen et al. 2014). Hooded Seals feed on a wide variety of fish and invertebrates, including species that occur throughout the water column (Andersen et al. 2013). Examples of typical prey are pelagic Amphipods (Parathemisto sp.), Greenland Halibut, members of the Cod family such as Polar and Atlantic Cod, Redfishes, Sand Eels, Herring, Capelin, Squid (e.g., Gonatus fabricii), and Shrimp (Haug et al. 2004, 2007).
A recent study of foraging habitat selection by Hooded Seals in the Northwest Atlantic documented significantly different preferences by adult males and females with the former occupying areas with complex seabed relief while the latter concentrated their foraging search effort along shelf areas (Andersen et al. 2013). Productivity (measured as chlorophyll a) was the most important single factor influencing habitat selection across all age groups.
Polar Bears and Killer Whales are known Hooded Seal predators (Lavigne and Kovacs 1988). These predators are thought to be having increased impacts on Hooded Seals in the West Ice following the deterioration of breeding ice used by this species (Foote et al. 2013, Øigård et al. 2014); Greenland Sharks also take at least young Hooded Seals (Leclerc et al. 2012).
|Continuing decline in area, extent and/or quality of habitat:||Yes|
|Generation Length (years):||12.8|
|Movement patterns:||Not a Migrant|
|Congregatory:||Congregatory (and dispersive)|
|Use and Trade:||
Hooded Seals were subjected to intense commercial hunting in the 19th and 20th centuries. Harvests were often conducted in association with Harp Seal harvests and commercial fisheries for Greenland Sharks. Norway, the Soviet Union (now Russia), Canada, and Greenland have all been involved in the commercial harvests of this species. Following World War II the hunt was primarily focused on pups because of their highly prized blue-back pelt, however, many adult females were taken while defending their pups until killing of mothers in the breeding areas was prohibited in the various areas (Lavigne and Kovacs 1988).
The abundance estimate for Hooded Seals in the Northwest Atlantic is now a decade old; the last survey was conducted in 2005 (ICES 2013a), and the stock is now treated as a data-poor stock in terms of management protocols. Total allowable catch was set at 8,200 in 2007 and remained unchanged through to 2015 despite the lack of new information on stock sizes or trends in the region. However, Canadian catches are reported to be very low, some few 10s of animals per year.
Hooded Seals are also harvested in Greenland at a current level of a few thousand animals per year. It is assumed that most of those animals are from the northwest Atlantic breeding groups (Davis Strait, Gulf, and Front) given that most of the harvest takes place in West Greenland. However, some animals are also taken on the east coast of Greenland, and these animals are likely from the West Ice stock.
Hooded Seals have been harvested in the West Ice (Greenland Sea, north of Jan Mayen) for centuries. This hunt increased substantially after World War II, to levels that were clearly not sustainable. Regulatory measures were introduced in 1958 to reduce effort, and quotas were imposed in 1971 (Sergeant 1976, ICES 2006). Based on catch per unit effort analyses and mark-recapture pup production estimates it was assumed that the stock increased from the 1960s through to the 1990s at an unknown rate (Ulltang and Øien 1988). In hindsight this almost certainly was not the case (ICES 2013a). Aerial surveys in 1994 failed to produce an abundance estimate (Øritsland and Øien 1995). Recent modelling efforts suggest that a very substantial decrease in population abundance took place from the late 1940s up to the early 1980s (ICES 2006). This decline has continued through to the present and predictions suggest an ongoing decline of 7% over the coming decade (Øigård et al. 2014). Total pup production in this stock was estimated to be 24,000 in 1997 and this number dropped to 15,250 in 2005 (Salberg et al. 2008) and has continued to decline to 13,655 in 2012, despite a complete cessation of commercial harvesting (Øigård et al. 2014).
By-catch of Hooded Seals in coastal net fisheries has been reported from the USA, from trawl fisheries off Norway and Newfoundland, and from salmon drift nets used off Greenland (Woodley and Lavigne 1991, Reeves et al. 1992, Waring et al. 2005). Competition for food with commercial fisheries and other predators has been suggested as a factor that may limit population growth or lead to declines of Hooded Seals (Reijnders et al. 1993). This factor may be playing a role in the continuing decline of Hooded Seals in the Northeast Atlantic given that abundance of Redfish, which are favoured prey of Hooded Seals, has declined in the late 1990s in both the Barents and Norwegian Seas due to excessive fishing pressure. No targeted catch is allowed for some Redfish species in this region and juvenile fish are being protected to attempt to promote recovery (ICES 2013b).
Impacts of oil spills on Hooded Seals have not been reported; however as an ice breeding species, they might be at risk of mortality from spills during the pupping season when newborn and newly weaned pups could be fouled (St. Aubin 1990). Hooded Seals have been exposed to Morbillivirus (Duignan et al. 1997), but are not known to have suffered fatalities during the mass die-offs of Harbour Seals in European waters from phocine distemper virus in 1998 and 2002. Subsequent testing revealed antibodies to the virus in 18-24% percent of the Hooded Seals sampled indicating exposure to the virus (Harkonen et al. 2006). Hooded Seals in the northeast Atlantic have high organohalogen contaminant burdens that are thought to be impacting thyroid homeostasis (Villanger et al. 2013).
The Hooded Seal is a pack ice species, and is dependent on ice as a substrate for pupping, moulting, and resting and as such is vulnerable to reduction in extent or timing of pack ice formation and retreat (Tynan and DeMaster 1997, Johnston et al. 2005, Learmonth et al. 2006, Kovacs and Lydersen 2008, Laidre et al. 2008). The very short, intense breeding season of Hooded Seals that is timed right at the end of the sea ice season, has likely put them at heightened risk of impacts arising from changes in the duration of the sea ice season (Kovacs et al. 2011b, 2012; Stenson and Hammill 2014). The Barents Sea region’s sea ice cover is declining at twice the rate of other arctic areas with a shortening of >20 weeks having taken place in the last few decades (Laidre et al. 2015), so it is not surprising that the West Ice stock is the first to be heavily impacted.
The productivity of the ice-edge ecosystem is also dependent on the dynamics and seasonality of arctic ice, and alterations to the cycle of formation and retreat of the ice could be having negative effects on important Hooded Seal prey. For example, Polar cod abundance has declined markedly in the last decade in the Barents Region within a broad, rapid “borealization” of the fish community in this sector of the Arctic (Fossheim et al. 2015). Decreases in sea ice cover could also lead to more shipping and development of extraction based industries in the Arctic (gas, oil, mining, etc.) which in turn could negatively affect Hooded Seals through increased exposure to contaminants and pollution, increased disturbance, and increased risk of shipping accidents and spills (Pagnan 2000).
Predation by Polar Bears is thought to be an increasing issue of concern with respect to the West Ice stock’s conservation status. Polar Bear diets have shown an increase in Hooded Seal consumption by 9.5% per decade since the mid-1980s in East Greenland along with a concomitant decrease in the consumption of Ringed Seals (McKinney et al. 2013). These changes are likely primarily due to changes in sea ice distribution and extent (but could also reflect a declining Ringed Seal population).
Numerous conservation measures, international management plans, harvest quotas, agreements, and treaties have been developed for the conservation of Hooded Seals dating back to the 1870s. Molting Seals in the Denmark Strait have been protected since 1961. Harvest quotas at Jan Mayen began in 1971. Hunting was banned in the Gulf of St. Lawrence in 1972 and quotas were placed on the rest of the Canadian harvest beginning in 1974. A European Economic Community ban on importation on Seal products in 1985 reduced the harvest of blueback Hooded Seals through the loss of the primary market for the furs (Lavigne and Kovacs 1988, Reeves et al. 1992). Greenlandic hunting is not limited, and might be at levels that are not sustainable, given deteriorating breeding conditions. The northeast Atlantic stock has experienced close to a 90% decline and the decline is ongoing. Population information for the northwest Atlantic is a decade old, leaving trends unknown for this segment of the population.
Based on population size, geographic range, habitat specificity, diet diversity, migration, site fidelity, sensitivity to changes in sea ice, sensitivity to changes in the trophic web, and maximum population growth potential Hooded Seals were rated to be among the top three arctic marine mammal species in terms of sensitivity to climate change (Laidre et al. 2008). This species should be re-evaluated as soon as new data are available for Canada and Greenland.
Andersen, J.M., Stenson, G.B., Skern-Maurizen, M., Wiersma, Y.F., Rosing-Asvid, A., Hammill, M.O. and Boehme, L. 2014. Drift Diving by Hooded Seals (Cystophora cristata) in the Northwest Atlantic Ocean. PLoS ONE 9(7): e103072.
Andersen, J.M., Wiersma, Y.F. and Stenson, G. 2009. Movement patterns of hooded seals (Cystophora cristata) in the Northwest Atlantic Ocean during the post-mout and pre-breeding seasons. Journal of Northwest Atlantic Fisheries Science 42: 1-11.
Andersen, J.M., Wiersma, Y.F., Stenson, G.B., Hammill, M.O., Rosing-Asvid, A. and Stern-Mauitzen, M. 2013. Habitat selection by hooded seals (Cystophora cristata) in the Northwest Atlantic Ocean. ICES Journal of Marine Science 70: 173-185.
Boness, D. J., Bowen, W. D. and Oftedal, O. T. 1988. Evidence of polygyny from spatial patterns of hooded seals (Cystophora cristata). Canadian Journal of Zoology 66: 703-706.
Bowen, W. D., Myers, R. A. and Hay, K. 1987. Abundance estimation of a dispersed, dynamic population: hooded seals (Cystophora cristata) in the northwest Atlantic. Canadian Journal of Fisheries and Aquatic Sciences 44: 282-295.
Bowen, W. D., Oftedal, O. T. and Boness, D. J. 1985. Birth to weaning in four days: extraordinary growth in the hooded seal (Cystophora cristata). Canadian Journal of Zoology 63: 2841-2846.
Burns, J.J. and Gavin, A. 1980. Recent records of hooded seals, Cystophora cristata Erxleben, from the western Beaufort Sea. Arctic 33: 326-329.
Coltman, D. W., Stenson, G., Hammill, M. O., Haug, T., Davis, S. and Fulton, T. L. 2007. Panmictic population structure in the hooded seal (Cystophora cristata). Molecular Ecology 16: 1639-1648.
Dudley, M. 1992. First Pacific record of a hooded seal, Cystophora cristata Erxleben, 1777. Marine Mammal Science 8: 164-168.
Duignan, P. J., Nielsen, O., House, C., Kovacs, K. M., Duffy, N., Early, G., Sadove, S., St. Aubin, D. J., Rima, B. K. and Geraci, J. R. 1997. Epizootiology of morbillivirus infection in harp, hooded, and ringed seals from the Canadian Arctic and western Atlantic. Journal of Wildlife Diseases 33: 7-19.
Fay, F.H. 1995. An earlier Pacific record of a hooded seal. Marine Mammal Science 11: 415.
Folkow, L. P. and Blix, A. S. 1999. Diving behaviour of hooded seals (Cystophora cristata) in the Greenland and Norwegian Seas. Polar Biology 22: 61-74.
Folkow, L. P., Martensson, P. E. and Blix, A. S. 1996. Annual distribution of hooded seals (Cystophora cristata) in the Greenland and Norwegian Seas. Polar Biology 16: 179-189.
Folkow, L.P., Nordoy, E.S. and Blix, A.S. 2010. Remarkable development of diving performance and migrations of hooded seals (Cystophora cristata) during their first year of life. Polar Biology 33: 433-441.
Foote, A.D., Newton, J., Avila-Arcos, M.C., Kampmann, M.-L., Samaniego, J.A., Post, K.,Rosing-Asvid, A., Sinding, M.-H.S. and Gilbert, M.T.P. 2013. Tracking niche variation over millennial timescales in sympatric killer whale lineages. Proceedings of the Royal Society B 280(1768): 20131481.
Fossheim, M., Primicderio, R., Johannesen, E., Ingvaldsen, R.B., Aschan, M.M. and Dolgov, A.V. 2015. Recent warming leads to a rapid borealization of fish communities in the Arctic. Nature Climate Change doi:10.1038/NCLIMATE2647.
Hammill, M. O. and Stenson, G. B. 2006. Abundance of Northwest Atlantic hooded seals (81960-2005). DFO CSAS.
Hammill, M. O. and Stenson, G. B. 2007. Application of the precautionary approach and conservation reference points to the management of Atlantic seals. ICES Journal of Marine Science 64: 701-706.
Hammill, M. O., Stenson, G. B. and Myers, R. A. 1992. Hooded seal Cystophora cristata) pup production in the Gulf of St Lawrence. Canadian Journal of Fisheries and Aquatic Sciences 49: 2546-2550.
Härkönen, T., Dietz, R., Reijnders, P., Teilmann, J., Harding, K., Hall, A., Brasseur, S., Siebert, U., Goodman, S. J., Jepson, P. D., Rasmussen, T. D. and Thompson, P. 2006. A review of the 1988 and 2002 phocine distemper virus epidemics in European harbor seals. Diseases of Aquatic Organisms 68: 115-130.
Harris, D. E. and Gupta, S. 2006. GIS-based analysis of ice-breeding seal strandings in the Gulf of Maine. Northeastern Naturalist 13: 403-420.
Harris, D. E., Lelli, B., Jakush, G. and Early, G. 2001. Hooded seal (Cystophora cristata) records from the southern Gulf of Maine. Northeastern Naturalist 8: 427-434.
Haug, T., Nilssen, K. T. and Lindblom, L. 2004. Feeding habits of harp and hooded seals in drift ice waters along the east coast of Greenland in summer and winter. Polar Research 23: 35-42.
Haug, T., Nilssen, K. T., Lindblom, L. and Lindstrom, U. 2007. Diets of hooded seals (Cystophora cristata) in coastal waters and drift ice waters along the east coast of Greenland. Marine Biology Research 3: 123-133.
Hay, K., Stenson, G. B., Wakeham, D. and Myers, R. A. 1985. Estimation of pup production of hooded seals (Cystophora cristata) at Newfoundland during March 1985. Can. Atl. Fish. Sci. Adv. Comm.
International Council for Exploration of the Sea. 2001. Report of the Joint ICES/NAFO Working Group on Harp and Hooded Seals. 2-6 October 2000, Copenhagen, Denmark. ICES CM 2001/ACFM:08.
International Council for Exploration of the Sea. 2006. Report of the ICES/NAFO Working Group on Harp and Hoodes Seals. ICES Advisory Committee on Fishery Management, Copenhagen, Denmark.
International Council for Exploration of the Sea. 2013a. Report of the working group on harp and hooded seals (WGHARP), 26-30 August 2013, PINRO, Murmansk, Russia. International Council for Exploration of the Sea CM 2013/ACOM:20.
International Council for Exploration of the Sea. 2013b. Report of the ICES Advisory Committee 2013: The Barents Sea and the Norwegian Sea. International Council for Exploration of the Sea Advice, 2013. Book 3.
IUCN. 2016. The IUCN Red List of Threatened Species. Version 2016-1. Available at: www.iucnredlist.org. (Accessed: 30 June 2016).
Johnston, D. W., Friedlaender, A. S., Torres, L. G. and Lavigne, D. M. 2005. Variation in sea ice cover on the east coast of Canada from1969 to 2002: climate variability and implications for harp and hooded seals. Climate Research 29: 209-222.
Kovacs, K. M. 1990. Mating strategies of male hooded seals (Cystophora cristata). Canadian Journal of Zoology 68: 2499-2502.
Kovacs, K. M. 2002. Hooded seal Cystophora cristata. In: W. F. Perrin, B. Wursig and J. G. M. Thewissen (eds), Encyclopedia of Marine Mammals, pp. 580-583. Academic Press, San Diego, California, USA.
Kovacs, K.M., Aguilar, A., Aurioles, D., Burkanov, V., Campagna, C., Gales, N.J., Gelatt, T., Goldsworthy, S.D., Goodman, S.J., Hofmeyr, G.J.G., Härkönen, T., Lowry, L., Lydersen, L., Schipper, J., Sipilä, T., Southwell, C., Thompson, D. and Trillmich, F. 2012. Global threats to pinnipeds. Marine Mammal Science 28: 414-436.
Kovacs, K. M. and Lavigne, D. M. 1986. Cystopora cristata. Mammalian Species 258: 1-9.
Kovacs, K. M. and Lavigne, D. M. 1992. Mass transfer efficiency between hooded seal (Cystophora cristata) mothers and their pups in the Gulf of St. Lawrence. Canadian Journal of Zoology 70: 1315-1320.
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.
Kovacs, K.M., Biuw, M., Nøst, O.A., Dodd, P., Hansen, E, Zhou, Q., Fedak, M. and Lydersen, C. 2011a. Seal’s used as “research assistants” in the polar oceans. In: O. Orheim and K. Ulstein (eds), International Polar Year 2007-2008: The Norwegian Contribution, pp. 100-103. Research Council of Norway, Oslo.
Kovacs, K. M., Lydersen, C., Hammill, M. O. and Lavigne, D. M. 1996. Reproductive effort of male hooded seals (Cystophora cristata). Canadian Journal of Zoology 74: 1521-1530.
Kovacs, K.M., Moore, S., Overland, J.E. and Lydersen, C. 2011b. Impacts of changing sea-ice conditions on Arctic marine mammals. Marine Biodiversity 41: 181-194.
Laidre, K.L., Stern, H., Kovacs, K.M., Lowry, L., Moore, S.E., Regehr, E.R., Ferguson, S.H., Wiig, Ø., Boveng, P., Angliss, R.P., Born, E.W., Litovka, D., Quakenbush, L., Lydersen, C., Vongraven, D. and Ugarte, F. 2015. Arctic marine mammal population status, sea ice habitat loss, and conservation recommendations for the 21st century. Conservation Biology 29: 724-737.
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: S97-S125.
Lavigne, D.M. and Kovacs, K.M. 1988. Harps and hoods: ice-breeding seals of the northwest Atlantic. University of Waterloo Press, Ontario, Canada.
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: 431-464.
Leclerc, L.M.E., Lydersen, C., Haug, T., Bachmann, L., Fisk, A.T. and Kovacs, K.M. 2012. A missing puzzle piece in Arctic food web puzzle? Stomach contents of Greenland Sharks sampled off Svalbard, Norway. Polar Biology 35: 1197-1208.
Lucas, Z. and Daoust, P.-Y. 2002. Large increases of harp seals (Phoca groenlandica) and hooded seals (Cystophora cristata) on Sable Island, Nova Scotia, since 1995. Polar Biology 25: 562-568.
Lydersen, C. and Kovacs, K. M. 1999. Behaviour and energetics of ice-breeding, North Atlantic phocid seals during the lactation period. Marine Ecology Progress Series 187: 265-281.
Lydersen, C., Kovacs, K. M. and Hammill, M. O. 1997. Energetics during nursing and early postweaning fasting in hooded seal (Cystophora cristata) pups from the Gulf of St Lawrence, Canada. Journal of Comparative Physiology B 167: 81-88.
McKinney, M.M., Iverson, S.J., Fisk, A.T., Sonne, C., Rigét, F.F., Letcher, R.J., Arts, M.T., Born, E.W., Rosing-Asvid, A. and Dietz, R. 2013. Global change effects on the long-term feeding ecology and contaminant exposures of East Greenland polar bears. Global Change Biology 19: 2360-2372.
Mignucci-Giannoni, A. A. and Haddow, P. 2002. Wandering hooded seals. Science 295: 627-628.
Øigård, T.A., Haug, T. and Nilssen, K.T. 2014. Current status of hooded seals in the Greenland Sea. Victims of climate change and predation? Biological Conservation 172: 29-36.
Øristland, T. and Øien, N. 1995. Aerial surveys of harp seal and hooded seal pups in the Greenland Sea pack ice. In: A.S. Blix, L. Walløe and Ø. Ulltang (eds), Whales, seal fish and man, pp. 77-87. Elsevier, Amserdam.
Pacifici, M., Santini, L., Di Marco, M., Baisero, D., Francucci, L., Grottolo Marasini, G., Visconti, P. and Rondinini, C. 2013. Generation length for mammals. Nature Conservation 5: 87–94.
Pagnan, J. L. 2000. Arctic marine protection. Arctic 53: 469-476.
Reeves, R.R., Stewart, B.S. and Leatherwood, S. 1992. The Sierra Club handbook of seals and sirenians. Sierra Club Books, San Diego, CA, USA.
Reijnders, P., Brasseur, S., van der Toorn, J., van der Wolf, P., Boyd, I., Harwood, J., Lavigne, D. and Lowry, L. 1993. Seals, fur seals, sea lions, and walrus. Status survey and conservation action plan. IUCN Seal Specialist Group.
Rice, D.W. 1998. Marine Mammals of the World: Systematics and Distribution. Society for Marine Mammalogy, Lawrence, Kansas.
Salberg A.-B., Haug, T. and Nilssen, K. T. 2008. Estimation of hooded seal (Cystophora cristata) pup production in the Greenlnad Sea pack ice during the 2005 whelping season. Polar Biology.
Sergeant, D. E. 1974. A rediscovered whelping population of hooded seals Cystophora cristata Erxleben and its possible relationship to other populations. Polarforschung 44: 1-7.
Sergeant, D. E. 1976. History and present status of populations of harp and hooded seals. Biological Conservation 10: 95-118.
St. Aubin, D. J. 1990. Physiologic and toxic effects on pinnipeds. In: J. R. Geraci and D. J. St. Aubin (eds), Sea mammals and oil: confronting the risks, pp. 103-127. Academic Press, New York, USA.
Stenson, G.B. and Hammill, M.O. 2014. Can ice breeding seals adapt to habitat loss in a time of climate change? ICES Journal of Marine Science 71: 1977-1986.
Sundt, R. C., Dahle, G. and Naevdal, G. 1994. Genetic-variation in the hooded seal, Cystophora cristata, based on enzyme polymorphism and multilocus DNA-fingerprinting. Hereditas 121: 147-155.
Truchon, M.H., Measures, L., LæHerault, V., Brethes, J.C., Galbraith, P.S., Harvey, M., Lessard, S., Starr, M. and Lecomte, N. 2013. Marine mammal strandings and environmental changes: a 15-year study in the St Lawrence ecosystem. PLOSOne 8(3): e59311. Doi_10.1371/journal.pone.0059311.
Tynan, C. T. and DeMaster, D. P. 1997. Observations and predictions of Arctic climate change potential effects of marine mammals. Arctic 50: 308-322.
Ulltang, Ø. and Øien, N. 1988. Bestandsutvikling ofg status for grønlands-sel og klappmyss (Population estimates and status of harp and hooded seals. In Norwegian). Fiskets Gantg 74: 8-10.
Villanger, G.D., Gabrielsen, K.M., Kovacs, K.M., Lydersen, C., Lie, E., Karimi, M., Sormo, E.G., Jenssen, B.M. 2013. Effects of complex organohalogen contaminant mixtures on thyroid homeostais in hooded seal (Cystophora cristata) mother-pup pairs. Chemosphere 92: 828-842.
Waring, G. T., Josephson, E., Fairfield, C. P. and Maze-Foley, K. 2005. U.S. Atlantic and Gulf of Mexico marine mammal stock assessments – 2005. NOAA Technical Memorandum. NOAA.
Waring, G.T., Josephson, E., Fairfield-Walsh, C.P. and Maze-Foley, K. (eds.). 2007. U.S. Atlantic and Gulf of Mexico marine mammal stock assessments – 2007. NOAA Technical Memorandum NMFS-NE-205.
Wiig, Ø. and Lie, R. W. 1984. An analysis of the morphological relationships between the hooded seals (Cystophora cristata) of Newfoundland, the Denmark Strait and Jan Mayen. Journal of Zoology (London) 203: 227-240.
Winters, G.H. and Bergflodt, B. 1978. Mortality and productivity of the Newfoundland hooded seal stock. International Commission for the Northwest Atlantic Fisheries Research Document 78/XI/91.
Woodley, T. H. and Lavigne, D. M. 1991. Incidental capture of pinnipeds in commercial fishing gear. International Marine Mammal Association Technical Report 91-01: 35 pp.
|Citation:||Kovacs, K.M. 2016. Cystophora cristata. The IUCN Red List of Threatened Species 2016: e.T6204A45225150.Downloaded on 29 June 2017.|
|Feedback:||If you see any errors or have any questions or suggestions on what is shown on this page, please provide us with feedback so that we can correct or extend the information provided|