Ice entrapment mortality may slow expanding presence of Arctic killer whales
- 249 Downloads
Killer whales (Orcinus orca) occur seasonally in the eastern Canadian Arctic during the summer months. Increasing killer whale sightings throughout the region, and incursions into areas where they have not historically been observed, have been linked with declining sea ice, which has raised questions about the potential ecological impacts of a greater killer whale presence in the Arctic. Here we report on four killer whales that died of starvation after overwintering in southeastern Hudson Bay. This incident is similar to two other reported killer whale ice entrapments in Hudson Bay in 2011 and 2013, which together exceed the incidence of such events over the previous century. The six confirmed, and up to 16 more assumed, deaths due to ice entrapments over the past decade almost certainly represent significant levels of mortality for the population(s) of killer whales in the Canadian Arctic. Ice entrapments of naïve killer whales exploring new Arctic territory may therefore offer a natural check on range expansions in the region, particularly in convoluted inland bays and inlets into which they pursue previously inaccessible prey, but fail to exit prior to ice formation.
KeywordsBioenergetics Climate change Distribution Histopathology Orcinus orca Stable isotopes
The Sanikiluaq Hunters and Trappers Association tracked sightings and organized sample collection by J. Kavik, L. Takatak, and N. Arragutainaq. S. Etheridge and J. Taylor (Animal Health Center, Abbotsford B.C) assisted with histopathology. K. Johnson (University of Windsor Great Lakes Institute for Environmental Research) performed stable isotope analysis. We thank J. Ford, J. Higdon, and C. Watt for reviewing earlier versions of this manuscript. This research was funded by Fisheries and Oceans Canada, the Nunavut General Monitoring Plan, the Nunavut Wildlife Management Board, and the Natural Sciences and Engineering Research Council of Canada.
Compliance with Ethical Standards
Conflict of interest
The authors have no conflicting interests to declare.
Ethics approval was not required for sampling of dead animals.
- Christensen I (1982) Killer whales in Norwegian coastal waters. Rep. Internatl. Whaling Comm. 32:633–641Google Scholar
- Doniol-Valcroze T, Hammill MO, Turgeon S, Postma LD (2016) Updated analysis of genetic mixing among Nunavik beluga summer stocks to inform population models and harvest allocation. DFO Can Sci Advis Sec Res Doc 2016/008. iv + 13 p.Google Scholar
- Ford JKB, Ellis GM (1999) Transients: mammal-hunting killer whales of British Columbia, Washington, and Southeastern Alaska. University of British Columbia Press, Vancouver, Canada, p 96Google Scholar
- Higdon JW, Westdal KH, Ferguson SH (2014) Distribution and abundance of killer whales (Orcinus orca) in Nunavut, Canada—an Inuit knowledge survey. J Mar Biol Assoc UK 94:1293–1304.Google Scholar
- Lowry LF, Nelson RR, Frost KJ (1987) Observations of killer whales, Orcinus orca, in western Alaska: Sightings, strandings, and predation on other marine mammals. Ont. Field Nat. 101:6–12Google Scholar
- Myrick AC, Yochem PK, Cornell LH (1988) Toward calibrating dentinal layers in captive killer whales by use of tetracycline labels. Rit Fisk. 11:285–296Google Scholar
- Pitman RL, Ensor P (2003) Three forms of killer whales (Orcinus orca) in Antarctic waters. J. Cetace. Res. Manage. 5:131–139Google Scholar
- Reeves RR, Mitchell E (1988) Distribution and seasonality of killer whales in the eastern Canadian Arctic. Rit Fisk. 11:136–160Google Scholar
- Schmidt-Nielsen K (1997) Energy metabolism. Animal physiology: adaption and environment. Cambridge University Press, Cambridge, pp 169–214Google Scholar
- Williams R, Krkošek M, Ashe E, Branch TA, Clark S, Hammond PS, Hoyt E, Noren DP, Rosen D, Winship A (2011) Competing conservation objectives for predators and prey: estimating killer whale prey requirements for Chinook salmon. PLoS ONE 6(11):e26738. https://doi.org/10.1371/journal.pone.0026738 CrossRefPubMedGoogle Scholar