<sod>Narwhals can live up to at least 50 years.<ref name= Macdonald/> Almost all modern predation of narwhals is by humans; other predators are [[polar bears]], which attempt to swipe narwhals at breathing holes and mainly target young whales, and [[killer whale]]s (orcas) which can group together to overwhelm narwhals.<ref>{{cite web|url=http://news.sciencemag.org/plants-animals/2012/01/killer-whale-menu-finally-revealed|title=Killer whale menu finally revealed|author=Morell V|date=30 January 2012|publisher=Science|accessdate=24 June 2015}}</ref>  [[Greenland shark]]s and [[walrus]]es may take a few small young or weak and wounded adults, though this is likely quite rare.<ref name= Macdonald/> When it comes to escaping predators such as orcas, narwhals typically use prolonged submergence to hide under the ice rather than relying on speed.<ref name="autogenerated1"/><eod>
<sod>Narwhals can live up to at least 50 years.<ref name= Macdonald/> Mortality often occurs when the narwhals suffocate after they fail to leave before the surface of the Arctic waters freeze over in the late autumn.<ref name= Macdonald/><ref name="autogenerated3">{{cite journal|author1=Laidre K., Heide-Jorgensen, M.P. |author2=Stern, H. |author3=Richard, P.  |lastauthoramp=yes |doi=10.1007/s00300-011-1036-8 |url=http://staff.washington.edu/klaidre/docs/Laidreetal_2012.pdf |title=Unusual narwhal sea ice entrapments and delayed autumn freeze-up trends |year=2011 |journal=Polar Biology |volume=35 |pages=149}}</ref> Open water is formed in ice-covered water by fracturing events induced by strong winds, but when these conditions are absent ice can quickly form. The last major entrapment events occurred when there was little to no wind. Narwhals are mammals and need air to breathe, so when open water is no longer accessible and the ice is too thick for them to break through, they can drown. Maximum [[Oxygen|aerobic]] swimming distance between breathing holes in ice is less than {{convert|1,450|m|ft|abbr=on|sp=uk}} which limits the use of foraging grounds and these holes must be at least {{convert|0.5|m|ft|abbr=on|sp=uk}} wide to allow an adult whale to breathe.<ref name="autogenerated1">{{cite journal|title=Extreme physiological adaptations as predictors of climate-change sensitivity in the narwhal, ''Mondon monceros''|doi=10.1111/j.1748-7692.2010.00408.x|year=2011|last1=Williams|first1=Terrie M.|last2=Noren|first2=Shawn R.|last3=Glenn|first3=Mike|journal=Marine Mammal Science|volume=27|issue=2|pages=334}}</ref> The events can trap groups as large as 600 individuals. Most entrapment events occur in narwhal wintering areas such as [[Disko Bay]]. In the largest entrapment in 1915 in [[West Greenland]], over 1,000 narwhals were trapped under the ice.<ref>{{cite journal|author=Porsild, M. |year=1918|title=On 'Savssat': A crowding of Arctic animals at holes in the sea ice|journal= Geogr Rev |volume=6|pages=215–228|jstor=207815|doi=10.2307/207815|issue=3}}</ref><eod>