Advertisement

Polar Biology

, Volume 35, Issue 1, pp 149–154 | Cite as

Unusual narwhal sea ice entrapments and delayed autumn freeze-up trends

  • Kristin Laidre
  • Mads Peter Heide-Jørgensen
  • Harry Stern
  • Pierre Richard
Short Note

Abstract

Sea ice entrapments of narwhals (Monodon monoceros) occur when rapid changes in weather and wind conditions create a formation of fast ice in bays or passages used by whales. Between 2008 and 2010, four entrapments of narwhals were reported in Canada and Greenland. In each case, large groups (40–600 individuals) succumbed in the sea ice at three separate summering localities, two of these where entrapments had never before been reported. We examined long-term trends in autumn freeze-up timing (date when sea ice concentration rises above some threshold) on the 6 largest narwhal summering areas using sea ice concentration from satellite passive microwave data (1979–2009). We found strongly positive and significant trends (P < 0.001) in progressively later dates of autumn freeze-up in all summering areas. Autumn freeze-up occurs between 0.5 and 1 day later per year, or roughly 2–4 weeks later, over the 31-year time series. This indicates that sea ice conditions on narwhal summering areas are changing rapidly. The question remains whether entrapment events on summering areas are random or whether narwhals are adapting to changes in sea ice freeze-up by prolonging their summer residence time.

Keywords

Climate change Narwhal Natural mortality Sassat Sea ice entrapment 

Notes

Acknowledgments

This work was supported by a NASA ROSES grant (Grant no. NNX08AF71G) (KLL, HS), the Greenland Institute of Natural Resources (MHJ), and Fisheries and Oceans Canada (PR). Thanks to the hunters in Greenland and Canada, Blair Dunn, and Jack Orr for providing details on narwhal entrapments. Thanks to Steve Ferguson, Keith Reid, and Sue Moore for thoughtful reviews of the paper.

References

  1. Amstrup SC, Stirling I, Smith TS, Perham C, Thiemann GW (2006) Intraspecific predation and cannibalism among polar bears in the Southern Beaufort Sea. Polar Biol 29:997–1002CrossRefGoogle Scholar
  2. Barber DG, Hanesiak JM, Chan W, Piwowar J (2001) Sea-ice and meteorological conditions in Northern Baffin Bay and the North water polynya between 1979 and 1996. Atmos-Ocean 39:343–359CrossRefGoogle Scholar
  3. Cavalieri DC, Parkinson C, Gloersen P, Zwally HJ (1996, updated 2008) Sea ice concentrations from Nimbus-7 SMMR and DMSP SSM/I passive microwave data, 1979–2007. Boulder: National Snow and Ice Data Center. Digital mediaGoogle Scholar
  4. Cooper LW, Ashjian CJ, Smith SL, Codispoti LA, Grebmeier JM, Campbell RG, Sherr EB (2006) Rapid seasonal sea-ice retreat in the arctic could be affecting Pacific Walrus (Odobenus rosmarus divergens) recruitment. Aquatic Mamm 32:98–102CrossRefGoogle Scholar
  5. DFO (Department of Fisheries and Oceans Canada) (2010a) Stock definition of Belugas and Narwhals in Nunavut. DFO Can Sci Advis Sec Sci Advis Rep 2009/079. Available from http://www.dfo-mpo.gc.ca/csas-sccs/
  6. Dietz R, Heide-Jørgensen MP, Richard P, Orr J, Laidre KL, Schmidt HC (2008) Movements of narwhals (Monodon monoceros) from Admiralty Inlet monitored by satellite telemetry. Polar Biol 31:1295–1306CrossRefGoogle Scholar
  7. Heide-Jørgensen MP, Richard P, Ramsay M, Akeeagok S (2002) Three recent ice entrapments of Arctic cetaceans in West Greenland and the eastern Canadian High Arctic. NAMMCO Sci Publ 4:143–148Google Scholar
  8. Heide-Jørgensen MP, Dietz R, Laidre KL, Richard P, Orr J, Schmidt HC (2003) The migratory habits of narwhals. Can J Zool 81:1298–1305CrossRefGoogle Scholar
  9. Heide-Jørgensen MP, Laidre KL, Burt ML, Borchers DL, Marques TA, Hansen RG, Rasmussen M, Fossette S (2010) Abundance of narwhals (Monodon monoceros L.) on the hunting areas in Greenland. J Mammal 91:1135–1151CrossRefGoogle Scholar
  10. IPCC (Intergovernmental Panel on Climate Change) (2007) Climate change 2007: synthesis report. Contribution of working groups I, II, and III to the fourth assessment report of the Intergovernmental Panel on Climate Change. Intergovernmental Panel on Climate Change, GenevaGoogle Scholar
  11. Kwok R (2007) Baffin Bay ice drift and export: 2002–2007. Geophys Res Lett 34. doi: 10.1029/2007GL031204
  12. Laidre KL, Heide-Jørgensen MP (2005) Arctic sea ice trends and narwhal vulnerability. Biol Con 121:509–517CrossRefGoogle Scholar
  13. Laidre KL, Heide-Jørgensen MP (2011) Life in the lead: extreme densities of narwhals in the offshore pack ice. Mar Ecol Prog Ser 423:269–278CrossRefGoogle Scholar
  14. Laidre KL, Stirling I, Lowry L, Wiig Ø, Heide-Jørgensen MP, Ferguson S (2008) Quantifying the sensitivity of arctic marine mammals to climate-induced habitat change. Ecol Appl 18:S97–S125PubMedCrossRefGoogle Scholar
  15. Maykut GA (1986) The surface heat and mass balance. Chapter 5 In: Untersteiner N (ed) The geophysics of sea ice, NATO ASI Series, vol 146. Plenum Press, New York, pp 395–463Google Scholar
  16. Perovich DK, Richter-Menge JA (2009) Loss of ice in the Arctic. Ann Rev Mar Sci 1:417–441PubMedCrossRefGoogle Scholar
  17. Porsild M (1918) On ‘Savssat’: A crowding of arctic animals at holes in the sea ice. Geogr Rev 6:215–228CrossRefGoogle Scholar
  18. Regehr EV, Hunter CM, Caswell H, Amstrup SC, Stirling I (2010) Survival and breeding of polar bears in the southern Beaufort Sea in relation to sea ice. J Animal Ecol 79:117–127CrossRefGoogle Scholar
  19. Richard PR, Laake JL, Hobbs RC, Heide-Jørgensen MP, Asselin N, Cleator H (2010) Baffin Bay narwhal population distribution and numbers: aerial surveys in the Canadian High Arctic, 2002–2004. Arctic 63:85–99Google Scholar
  20. Rode KD, Amstrup SC, Regehr EV (2010) Reduced body size and cub recruitment in polar bears associated with sea ice decline. Ecol Appl 20:768–782PubMedCrossRefGoogle Scholar
  21. Siegstad H, Heide-Jørgensen MP (1994) Ice entrapments of narwhals (Monodon monoceros) and white whales (Delphinapterus leucas) in Greenland. Meddr Grønland Biosci 39:151–160Google Scholar

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Kristin Laidre
    • 1
  • Mads Peter Heide-Jørgensen
    • 2
  • Harry Stern
    • 1
  • Pierre Richard
    • 3
  1. 1.Polar Science Center, Applied Physics LaboratoryUniversity of WashingtonSeattleUSA
  2. 2.Greenland Institute of Natural ResourcesNuukGreenland
  3. 3.Fisheries and Oceans CanadaFreshwater InstituteWinnipegCanada

Personalised recommendations