Variation in body size of ringed seals (Pusa hispida hispida) across the circumpolar Arctic: evidence of morphs, ecotypes or simply extreme plasticity?

  • Kit M. Kovacs Norwegian Polar Institute, Fram Centre, Tromsø, Norway
  • John Citta Alaska Department of Fish and Game, Fairbanks, AK, USA
  • Tanya Brown Department of Fisheries and Oceans, Vancouver, BC, Canada
  • Rune Dietz Department of Bioscience, Marine Mammal Research, Aarhus University, Roskilde, Denmark
  • Steve Ferguson Fisheries and Oceans Canada, Winnipeg, MB, Canada
  • Lois Harwood Fisheries and Oceans Canada, Yellowknife, NT, Canada
  • Magali Houde Environment and Climate Change Canada, Montreal, QB, Canada
  • Ellen V. Lea Fisheries and Oceans Canada, Inuvik, NT, Canada
  • Lori Quakenbush Alaska Department of Fish and Game, Fairbanks, AK, USA
  • Frank Riget Greenland Institute for Natural Resources, Nuuk, Greenland
  • Aqqalu Rosing-Asvid Greenland Institute for Natural Resources, Nuuk, Greenland
  • Tom G. Smith EMC Eco Marine Corp, Garthby, QB, Canada
  • Vladimir Svetochev Murmansk Marine Biological Institute, Russian Academy of Sciences, Murmansk, Russia
  • Olga Svetocheva
  • Christian Lydersen Norwegian Polar Institute, Fram Centre, Tromsø, Norway
Keywords: Density-dependence, ecology, food availability, morphometry, pinniped, phocid seal


The ringed seal is a small phocid seal that has a northern circumpolar distribution. It has long been recognized that body size is variable in ringed seals, and it has been suggested that ecotypes that differ in size exist. This study explores patterns of body size (length and girth) and age-at-maturity across most of the Arctic subspecies’ range using morphometric data from 35 sites. Asymptotic lengths varied from 113 to 151 cm, with sites falling into five distinct size clusters (for each sex). Age-at-maturity ranged from 3.1 to 7.4 years, with sites that had early ages of sexual maturity generally having small length-at-maturity and small final body length. The sexes differed in length at some sites, but not in a consistent pattern of dimorphism. The largest ringed seals occurred in western Greenland and eastern Canada, and the smallest occurred in Alaska and the White Sea. Latitudinal trends occurred only within sites in the eastern Canadian Arctic. Girth (with length and season accounted for) was also highly variable but showed no notable spatial pattern; males tended to be more rotund than females. Genetic studies are needed, starting with the “giants” at Kangia (Greenland) and in northern Canada to determine whether they are genetically distinct ecotypes. Additional research is also needed to understand the ecological linkages that drive the significant regional size differences in ringed seals that were confirmed in this study, and also to understand their implications with respect to potential adaptation to climate change.


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Amano M., Hayano A. & Miyazaki N. 2002. Geographic variation in the skull of the ringed seal Pusa hispida. Journal of Mammalogy 83, 370–380, doi: 10.1644/1545-1542(2002)083<0370:GVITSO>2.0.CO;2.

Atkinson S. 1997. Reproductive biology of seals. Reviews of Reproduction 2, 175–194, doi: 10.1530/ror.0.0020175.

Bartholomew G.A. 1970. A model for the evolution of pinniped polygyny. Evolution 24, 546–559, doi: 10.2307/2406835.

Bell R.K. 2012. A review of seal harvests in the Inuvialuit Settlement Region, NWT. Report for the Fisheries Joint Management Committee. Inuvik, NT: Fisheries Joint Management Committee.

Bengtsson O., Lydersen C., Kovacs K.M. & Lindström U. 2020. Ringed seal (Pusa hispida) diet on the west coast of Spitsbergen, Svalbard, Norway: during a time of ecosystem change. Polar Biology 43, 773–788, doi: 10.1007/s00300-020-02684-5.

Blackburn T.M. & Gaston K.J. 1994. Animal body size distributions: patterns, mechanisms and implications. Trends in Ecology and Evolution 9, 471–474, doi: 10.1016/0169-5347(94)90311-5.

Blackburn T.M., Gaston K.J. & Loder N. 1999. Geographic gradients in body size: a clarification of Bergmann’s rule. Diversity and Distributions 5, 165–174, doi: 10.1046/j.1472-4642.1999.00046.x.

Boucher N.P., Nichole P., Derocher A.E. & Richardson E.S. 2020. Spatial and temporal variability in ringed seal (Pusa hispida) stable isotopes in the Beaufort Sea. Ecology and Evolution 10, 4178–4192, doi: 10.1002/ece3.6186.

Burnham K.P. & Anderson D.R. 2003. Model selection and multimodel inference: a practical information‐theoretic approach. Cham: Springer Nature.

CAFF 2017. State of the Arctic marine biodiversity report. Akureyri: Conservation of Arctic Flora and Fauna International Secretariat.

Calder W.A. 1984. Size, function, and life history. Cambridge, MA: Harvard University Press.

Crawford J.A., Frost K.J., Quakenbush L.T. & Whiting A. 2012. Different habitat use strategies by subadult and adult ringed seals (Phoca hispida) in the Bering and Chukchi seas. Polar Biology 35, 241-255, doi: 10.1007/s00300-011-1067-1.

Crawford J.A., Quakenbush L.T. & Citta J.J. 2015. A comparison of ringed and bearded seal diet, condition and productivity between historical (1975–1984) and recent (2003–2012) periods in the Alaskan Bering and Chukchi seas. Progress in Oceanography 136, 133–150, doi: 10.1016/j.pocean.2015.05.011.

Davis C.S., Stirling I., Stobeck C. & Coltman D.W. 2008. Population structure of ice-breeding seals. Molecular Ecology 17, 3078–3094, doi: 10.1111/j.1365-294X.2008.03819.x.

Dietz R., Heide-Jørgensen M.-P., Teilmann J., Valentin N. & Härkönen T. 1991. Age determination in European harbour seals Phoca vitulina L. Sarsia 76, 17–21, doi: 10.1080/00364827.1991.10413461.

Fedoseev G.A. 1975. Ecotypes of the ringed seal (Pusa hispida Schreber, 1777) and their reproductive capabilities. Rapports et Procès-Verbaux des Reunions du Conseil International pour l’Exploration de la Mer 169, 156–160.

Ferguson S.H., Stirling I. & McLoughlin P. 2005. Climate change and ringed seal (Phoca hispida) recruitment in western Hudson Bay. Marine Mammal Science 21, 121–135, doi: 10.1111/j.1748-7692.2005.tb01212.x.

Ferguson S.H., Xinhua Z., Young B.G., Yurkowski D.J., Thiemann G.W., Fisk A.T. & Muir D.C.G. 2018. Geographic variation in ringed seal growth rate and body size. Canadian Journal of Zoology 96, 649–659, doi: 10.1139/cjz-2017-0213.

Ferguson S.H., Young B.G., Yurkowski D.J., Anderson R., Willing C. & Nielsen O. 2017. Demographic, ecological, and physiological responses of ringed seals to an abrupt decline in sea ice availability. PeerJ 5, e2957, doi: 10.7717/peerj.2957.

Ferguson S.H., Yurkowski D.J., Young B.G., Fisk A.T., Muir D.C.G., Zhu X. & Thiemann G.W. 2020. Comparing temporal patterns in body condition of ringed seals living within their core geographic range with those living at the edge. Ecography 43, 1521–1535, doi: 10.1111/ecog.04988.

Ferguson S.H., Yurkowski D.J., Young B.G., Willing C., Zu Z.H., Muir D.C.G., Fisk A.T. & Thiemann G.W. 2019. Do intraspecific life history patterns follow interspecific predictions? Population Ecology 61, 371–382, doi: 10.1002/1438-390X.12008.

Finley K.J., Miller G.W., Davis R.A. & Koski W.R. 1983. A distinctive large breeding population of ringed seals (Phoca hispida) inhabiting the Baffin Bay pack ice. Arctic 36, 162–173.

Furgal C.M., Kovacs K.M. & Innes S. 1996. Characteristics of ringed seal, Phoca hispida, subnivean structures and breeding habitat and their effects on predation. Canadian Journal of Zoology 74, 858–874, doi: 10.1139/z96-100.

Gaston K.J. 2000. Global patterns in biodiversity. Nature 405, 220–227, doi: 10.1038/35012228.

Gelman A., Carlin J.B., Stern H.S. & Rubin D.B. 2003. Bayesian data analysis. 2nd edn. Boca Raton, FL: CRC Press.

Gelman A., Huang J. & Vehtari A. 2014. Understanding predictive information criteria for Bayesian models. Statistics and Computing 24, 997–1016, doi: 10.1007/s11222-013-9416-2.

Gjertz I. & Lydersen C. 1986. Polar bear predation on ringed seals in the fast-ice of Hornsund, Svalbard. Polar Research 4, 65–68, doi: 10.3402/polar.v4i1.6921.

Hamilton C.D., Lydersen C., Ims R.A. & Kovacs K.M. 2015. Predictions replaced by facts in a changing Arctic: a keystone species’ behavioural responses to declining sea ice. Biology Letters 11, article no. 20150803, doi: 10.1098/rsbl.2015.0803.

Hamilton C.D., Lydersen C., Ims R.A. & Kovacs K.M. 2016. Coastal habitat use by ringed seals Pusa hispida following a regional sea-ice collapse: importance of glacial refugia in a changing Arctic. Marine Ecology Progress Series 545, 261–277, doi: 10.3354/meps11598.

Hamilton C.D., Vacquié-Garcia J., Kovacs K.M., Ims R.A., Kohler J. & Lydersen C. 2019. Contrasting responses to climate change by two Arctic marine mammal species. Biology Letters 15, article no. 20180834, doi: 10.1098/rsbl.2018.0834.

Hammill M.O. & Sauvé C. 2017. Growth and condition in harp seals: evidence of density-dependent and density-independent influences. ICES Journal of Marine Sciences 74, 1395–1407, doi: 10.1093/icesjms/fsw237.

Harding K.C., Salmon M., Teilmann J., Dietz R. & Härkönen T. 2018. Population wide decline in somatic growth in harbour seals—early signs of density dependence. Front Ecology and Evolution 6, article no. 59, doi: 10.3389/fevo.2018.00059.

Hartigan J.A. & Wong M.A. 1979. Algorithm AS 136: a k-means clustering algorithm. Applied Statistics 28, 100–108, doi: 10.2307/2346830.

Harwood L.A., Smith T.G., Alikamik J., Lea E.V., Stirling I., Wright H., Melling H. & Zhu X. 2020. Long-term, harvest-based monitoring of ringed seal body condition and reproduction in Canada’s western Arctic: an update through 2019. Arctic 73, 206–220, doi: 10.14430/arctic70428.

Harwood L.A., Smith T.G. & Auld J.C. 2012. Fall migration of ringed seals (Phoca hispida) through the Beaufort and Chukchi seas, 2001-02. Arctic 65, 35–44, doi: 10.14430/arctic4163.

Harwood L.A., Smith T.G., Auld J.C., Melling H. & Yurkowski D.J. 2015. Seasonal movements and diving of ringed seals, Pusa hispida, in the western Canadian Arctic, 1999-2001 and 1020-11. Arctic 68, 193–209, doi: 10.14430/arctic4479.

Harwood L.A., Smith T.G. & Melling H. 2000. Variation in reproduction and body condition of the ringed seal (Phoca hispida) in western Prince Albert Sound, NT, Canada, as assessed through a harvest-based sampling program. Arctic 53, 422–431, doi: 10.14430/arctic872.

Harwood L.A., Smith T.G., Melling H., Alikamik J. & Kingsley M.C.S. 2012. Ringed seals and sea ice in Canada’s western Arctic: harvest-based monitoring 1992–2011. Arctic 65, 377–390, doi: 10.14430/arctic4236.

Heide-Jørgensen M.P., Stewart B.S. & Leatherwood S. 1992. Satellite tracking of ringed seals Phoca hispida off northwest Greenland. Ecography 15, 56–61, doi: 10.1111/j.1600-0587.1992.tb00008.x.

Holst M. & Stirling I. 2002. A comparison of ringed seal (Phoca hispida) biology on the east and west sides of the North Water Polynya, Baffin Bay. Aquatic Mammals 28, 221–230.

Holst M., Stirling I. & Calvert W. 1999. Age structure and reproductive rates of ringed seals (Phoca hispida) on the northwestern coast of Hudson Bay in 1991 and 1992. Marine Mammal Science 15, 1357–1364, doi: 10.1111/j.1748-7692.1999.tb00898.x.

Hooten M.B. & Hobbs N.T. 2015. A guide to Bayesian model selection for ecologists. Ecological Monographs 85, 3–28, doi: 10.1890/14-0661.1.

Iacozza J. & Ferguson S.H. 2014. Spatio-temporal variability of snow over sea ice in western Hudson Bay, with reference to ringed seal pup survival. Polar Biology 37, 817–832, doi: 10.1007/s00300-014-1484-z.

Katsanevakis S. 2006. Modelling fish growth: model selection, multi-model inference and model selection uncertainty. Fisheries Research 81, 229–235, doi: 10.1016/j.fishres.2006.07.002.

Kellner K. 2019. jagsUI: a wrapper around “rjags” to streamline “JAGS” analyses. R package version 1.1.1. Accessed on the internet at

Kelly B.P. & Wartzok D. 1996. Ringed seal diving behaviour in the breeding season. Canadian Journal of Zoology 74, 1547–1555, doi: 10.1139/z96-169.

Kelly B.P., Badajos O.H., Kunnasranta M., Moran J.R., Martinez-Bakker M., Wartzok D. & Boveng P. 2010. Seasonal home ranges and fidelity to breeding sites among ringed seals. Polar Biology 33, 1095–1109, doi: 10.1007/s00300-010-0796-x.

Kingsley M.C.S. & Byers T.J. 1998. Failure of reproduction in ringed seals (Phoca hispida) in Amundsen Gulf, Northwest Territories in 1984-1987. In M.P. Heide-Jørgensen & C. Lydersen (eds.): Ringed seals of the North Atlantic. NAMMCO Scientific Publications 1. Pp. 197–210. Tromsø: North Atlantic Marine Mammal Commission.

Kleiber M. 1975. The fire of life. An introduction to animal energetics. Huntington, NY: Kreiger Publishing Company.

Kovacs K.M., Lydersen C., Overland J.E. & Moore S.E. 2011. Impacts of changing sea-ice conditions on Arctic marine mammals. Marine Biodiversity 41, 181–194, doi: 10.1007/s12526-010-0061-0.

Krafft B.A., Kovacs K.M., Frie A.K., Haug T. & Lydersen C. 2006. Growth and population parameters of ringed seals (Pusa hispida) from Svalbard, Norway, 2002–2004. ICES Journal of Marine Sciences 63, 1136–1144, doi: 10.1016/j.icesjms.2006.04.001.

Krafft B.A., Kovacs K.M. & 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 355, 199–206, doi: 10.3354/meps335199.

Laidre K.L., Stern H., Kovacs K.M., Lowry L., Moore S.E., Regehr E.V., Ferguson S.H., Wiig Ø., Boveng P., Angliss R.P., Born E.W., Litovka D., Quakenbush L., Lydersen C., Vongraven D. & Ugarte F. 2015. Arctic marine mammal population status, sea ice habitat loss, and conservation recommendations for the 21st century. Conservation Biology 29, 724–737, doi; 10.1111/cobi.12474.

Laws R.M. 1956. Growth and sexual maturity in aquatic mammals. Nature 178, 193–194, doi: 10.1038/178193a0.

Laws R.M. 1959. Accelerated growth in seals, with special reference to the Phocidae. Norsk Hvalfangst-Tidende 48, 425–452.

Leclerc L-M.E., Lydersen C., Haug T., Bachmann L., Fisk A.T. & 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, 1197–1208, doi: 10.1007/s00300-012-1166-7.

Lindstedt S.L. & Boyce M.S. 1985. Seasonality, fasting endurance and body size in mammals. American Naturalist 125, 873–878, doi: 10.1086/284385.

Lowry D.B. 2012. Ecotypes and the controversy over stages in the formation of new species. Biological Journal of the Linnean Society 106, 241–257, doi: 10.1111/j.1095-8312.2012.01867.x.

Lowry L. 2016. Pusa hispida. The IUCN Red List of Threatened Species 2016: e.T41672A45231341. Accessed on the internet at on 1 November 2020.

Lowther A., Fisk A., Kovacs K.M. & Lydersen C. 2017. Interdecadal changes in the marine food web along the west Spitsbergen coast detected in the stable isotope composition of ringed seal whiskers. Polar Biology 40, 2027–2033, doi: 10.1007/s00300-017-2122-3.

Luque S.P. & Ferguson S.H. 2010. Age structure, growth, mortality and density of belugas (Delphinapterus leucas) in the Canadian Arctic: responses to environment? Polar Biology 33, 163–178, doi: 10.1007/s00300-009-0694-2.

Luque S., Ferguson S.H. & Breed G. 2014. Spatial behaviour of a keystone Arctic marine predator and implications of climate warming in Hudson Bay. Journal of Experimental Marine Biology and Ecology 461, 504–515, doi: 10.1016/j.jembe.2014.10.002.

Lydersen C., Fisk A.T. & Kovacs K.M. 2016. A review of Greenland shark (Somniosus microcephalus) studies in the Kongsfjorden area, Svalbard Norway. Polar Biology 39, 2169–2178, doi: 10.1007/s00300-016-1949-3.

Lydersen C. & Gjertz I. 1986. Studies of the ringed seal (Phoca hispida Schreber 1775) in its breeding habitat in Kongsfjorden, Svalbard. Polar Research 4, 57–63, doi: 10.3402/polar.v4i1.6920.

Lydersen C. & Gjertz I. 1987. Population parameters of ringed seals (Phoca hispida, Schreber, 1775) in the Svalbard area. Canadian Journal of Zoology 65, 1021–1027, doi: 10.1139/z87-162.

Lydersen C. & Hammill M.O. 1993. Diving in ringed seal (Phoca hispida) pups during the nursing period. Canadian Journal of Zoology 71, 991–996, doi: 10.1139/Z93-131.

Lydersen C., Vaquie-Garcia J., Lydersen E., Christensen G.N. & Kovacs K.M. 2017. Novel terrestrial haul-out behaviour by ringed seals (Pusa hispida) in Svalbard, in association with harbour seals (Phoca vitulina). Polar Research 36, article no. 1374124, doi: 10.1080/17518369.2017.1374124.

MacNeil M.A., McMeans B.C., Hussey N.E., Vercsei P., Svavarsson J., Kovacs K.M., Lydersen C., Treble M.A., Skomal G.B., Ramsey M. & Fisk A.T. 2012. Biology of the Greenland shark Somniosus microcephalus. Journal of Fish Biology 80, 991–1018, doi: 10.1111/j.1095-8649.2012.03257.x.

Mansfield A.W. 1967. Seals of Arctic and eastern Canada. Fisheries Research Board of Canada Bulletin 137. Ottawa: Fisheries Research Board of Canada.

Martinez-Bakker M.E., Sell S.K., Swanson B.J., Kelly B.P. & Tallmon D.A. 2013. Combined genetic and telemetry data reveal high rates of gene flow, migration, and long-distance dispersal potential in Arctic ringed seals (Pusa hispida). PLoS One 8, e77125. doi: 10.1371/journal.pone.0077125.

McLaren I.A. 1958. The biology of the ringed seal, Phoca hispida, in the eastern Canadian Arctic. Bulletin of the Fisheries Research Board of Canada 118. Ottawa: Fisheries Research Board of Canada.

McLaren I.A. 1993. Growth in pinnipeds. Biological Reviews of the Philosophical Society 68, 1–79, doi: 10.1111/j.1469-185x.1993.tb00731.x.

McMeans B.C., Aarts M.T., Lydersen C., Kovacs K.M., Hop H., Falk-Petersen S. & Fisk A.T. 2013. The role of Greenland sharks (Somniosus microcephalus) in an Arctic ecosystem: assessed via stable isotopes and fatty acids. Marine Biology 160, 1223-1238, doi: 10.1007/s00227-013-2174-z.

Panik M.J. 2014. Growth curve modeling: theory and applications. Hoboken, NJ: John Wiley & Sons.

Pauly D. 1981. The relationships between gill surface area and growth performance in fish: a generalization of von Bertalanffy’s theory of growth. Berichte der Deutschen Wissenchaftlichen Kommission für Meeresforschung 28, 251–282.

Peters R.H. 1983. The ecological implications of body size. Cambridge: Cambridge University Press.

Pilford N.W., Derocher A.E., Stirling I. & Richardson E. 2014. Polar bear predatory behaviour reveals seascape distribution of ringed seal lairs. Population Ecology 56, 129–138. doi: 10.1007/s10144-013-0396-z.

Plummer M. 2019. rjags: Bayesian graphical models using MCMC. R package version 4-10. Accessed on the internet at

Quinn T.J. & Deriso R.B. 1999. Quantitative fish dynamics. Oxford: Oxford University Press.

R Core Team 2020. R: a language and environment for statistical computing. Vienna: R Foundation for Statistical Computing.

Reimer J.R., Caswell H., Derocher A.E. & Lewis M.A. 2019. Ringed seal demography in a changing climate. Ecological Applications 29, e01855, doi: 10.1002/eap.1855.

Rosing-Asvid A. 2010. Seals of Greenland. Gylling, Denmark: Narayana Press.

Ryg M., Smith T.G. & Øristsland N.A. 1990. Seasonal changes in body mass and body compositions of ringed seals (Phoca hispida) on Svalbard. Canadian Journal of Zoology 68, 470–475, doi: 10.1139/z90-069.

Schnute J.T. & Richards L.J. 1990. A unified approach to the analysis of fish growth, maturity, and survivorship data. Canadian Journal of Fisheries and Aquatic Sciences 47, 24–40, doi: 10.1139/f90-003.

Sergeant D.E. 1973. Feeding, growth and productivity in the Northwest Atlantic harp seal (Pagophilus groenlandicus). Journal of the Fisheries Research Board of Canada 30, 17–29, doi: 10.1139/f73-003.

Sibly R.M. & Brown J.H. 2007. Effects of body size and lifestyle on evolution of mammal life histories. Proceedings of the National Academy of Sciences 104, 17707–17712, doi: 10.1073/pnas.0707725104.

Smith T.G. 1973. Population dyna mics of the ringed seal in the Canadian eastern Arctic. Fisheries Research Board of Canada Bulletin 181. Ottawa: Fisheries Research Board of Canada.

Smith T.G. 1976. Predation of ringed seal pups (Phoca hispida) by the Arctic fox (Alopex lagopus). Canadian Journal of Zoology 54, 1610–1616, doi: 10.1139/z76-188.

Smith T.G. 1980. Polar bear predation of ringed and bearded seals in the land-fast sea ice habitat. Canadian Journal of Zoology 58, 2201–2209, doi: 10.1139/z80-302.

Smith T.G. 1987. The ringed seal, Phoca hispida, of the Canadian western Arctic. Canadian Bulletin of Fisheries and Aquatic Sciences 216. Ottawa: Department of Fisheries and Oceans.

Smith T.G. & Hammill M.O. 1981. Ecology of the ringed seal, Phoca hispida, in its fast-ice breeding habitat. Canadian Journal of Zoology 59, 966–981, doi: 10.1139/z81-135.

Smith T.G. & Harwood L.A. 2001. Observations of neonate ringed seals, Phoca hispida, after early break-up of the sea ice in Prince Albert Sound, Northwest Territories, Canada, spring 1998. Polar Biology 24, 215–219, doi: 10.1007/s003000000198h.

Smith T.G. & Lydersen C. 1991. Availability of suitable land-fast ice and predation as factors limiting ringed seal populations, Phoca hispida, in Svalbard. Polar Research 10, 585–594, doi: 10.3402/polar.v10i2.6769.

Smith T.G. & Taylor D. 1977. Notes on marine mammal, fox and polar bear harvests in the Northwest Territories 1940 to 1972. Fisheries and Marine Services Technical Report 694. Ottawa: Environment Canada.

Stirling I. 2002. Polar bears and seals in the eastern Beaufort Sea and Amundsen Gulf: a synthesis of population trends and ecological relationships over three decades. Arctic 55 Suppl. 1, 59–76.

Stirling I., Archibald W.R. & DeMaster D.P. 1977. Distribution and abundance of seals in the eastern Beaufort Sea. Journal of the Fisheries Research Board of Canada 34, 976–988, doi: 10.1139/f77-150.

Teilmann J., Born E.W. & 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, 1934–1946, doi: 10.1139/z99-163.

Tikhomirov E.A. 1971. Body growth and development of reproductive organs of the North Pacific phocids. In V.A. Arseniev & K.I. Panin (eds.): Pinnipeds of the North Pacific. Pp. 213–241. Jerusalem: Israel Program for Scientific Translations.

Turesson G. 1922. The species and the variety as ecological units. Hereditas 3, 100–113, doi: 10.1111/j.1601-5223.1922.tb02727.x.

Usher P.J. 2002. Inuvialuit use of the Beaufort Sea and its resources, 1960–2000. Arctic 55 Suppl. 1, 18–28.

Vehtari A., Gabry J., Yao Y. & Gelman A. 2018. loo: efficient leave-one-out cross-validation and WAIC for Bayesian models. R package version 2.0.0. Accessed on the internet at

Vehtari A., Gelman A. & Gabry J. 2017. Practical Bayesian model evaluation using leave-one-out cross-validation and WAIC. Statistics and Computing 27, 1413–1432, doi: 10.1007/s11222-016-9696-4.

Von Bertalanffy L. 1938. A quantitative theory of organic growth (inquiries on growth laws. II). Human Biology 10, 181–213.

Von Duyke A.L., Douglas D.C., Herreman J.K. & Crawford J.A. 2020. Ringed seal (Pusa hispida) seasonal movements, diving and haulout behavior in the Beaufort, Chukchi, and Bering seas (2011-2017). Ecology and Evolution 10, 5595–5616, doi: 10.1002/ece3.602.

Walter R.P., Roy D., Hussey N.E., Stelbrink B., Kovacs K.M., Lydersen C., McMeans B.C., Svavarsson J., Kessel S.T., Porsmoguer S.B., Wildes S., Tribuzio C., Campana S.E., Petersen S., Grubbs R.D., Heath D.D., Hedges K.J. & Fisk A.T. 2017. Origins of the Greenland shark (Somniosus microcephalus): impacts of ice-olation and introgression. Ecology and Evolution 7, 8113–8125, doi: 10.1002/ece3.3325.

Watanabe S. 2010. Asymptotic equivalence of Bayes cross validation and widely applicable information criterion in Singular Learning Theory. Journal of Machine Learning Research 11, 3571–3594.

Wiig Ø., Derocher A.E. & Belikov S.I. 1999. Ringed seal (Phoca hispida) breeding in the drifting pack ice of the Barents Sea. Marine Mammal Science 15, 595–598, doi: 10.1111/j.1748-7692.1999.tb00828.x.

Young B.G. & Ferguson S.H. 2013. Seasons of the ringed seal: pelagic open-water hyperphagy, benthic feeding over winter and spring fasting during molt. Wildlife Research 40, 52–60, doi: 10.1071/WR12168.

Yurkowski D.J., Chambellant M. & Ferguson S.H. 2011. Bacular and testicular growth and allometry in the ringed seal (Pusa hispida): evidence of polygyny? Journal of Mammalogy 92, 803–810, doi: 10.1644/10-MAMM-A-082.1.

Yurkowski D.J., Ferguson S.H., Semeniuk C.A.D., Brown T.M., Muir D.C.G. & Fisk A.T. 2016. Spatial and temporal variation of an ice-adapted predator’s feeding ecology in a changing Arctic marine ecosystem. Oecologia 180, 631–644, doi: 10.1007/s00442-015-3384-5.

Yurkowski D.J., Semeniuk C.A.D., Harwood L.A., Rosing-Asvid A., Dietz R., Brown T.M., Clackett S., Grgicak-Mannion A., Fisk A.T. & Ferguson S.H. 2016. Influence of sea ice phenology on the movement ecology of ringed seals across their latitudinal range. Marine Ecology Progress Series 562, 237–250, doi: 10.3354/meps11950.
How to Cite
Kovacs K. M., Citta J., Brown T., Dietz R., Ferguson S., Harwood L., Houde M., Lea E. V., Quakenbush L., Riget F., Rosing-Asvid A., Smith T., Svetochev V., Svetocheva O., & Lydersen C. (2021). Variation in body size of ringed seals (<em>Pusa hispida hispida</em&gt;) across the circumpolar Arctic: evidence of morphs, ecotypes or simply extreme plasticity?. Polar Research, 40.
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