Killer whales (Orcinus orca) in the Canadian Arctic: Distribution, prey items, group sizes, and seasonality

Abstract

Killer whales (Orcinus orca) have a global distribution, but many high-latitude populations are not well studied. We provide a comprehensive review of the history and ecology of killer whales in the Canadian Arctic, for which there has previously been little information. We compiled a database of 450 sightings spanning over 15 decades to document the historical occurrence, distribution, feeding ecology, and seasonality of killer whales observed throughout the region. Sighting reports per decade increased substantially since 1850 and were most frequent in the eastern Canadian Arctic. The mean reported group size was 8.3 (median = 4, range 1-100), but size varied significantly among regions and observed prey types. Observations of predation events indicate that Canadian Arctic killer whales 1 Current address: LGL Limited environmental research associates, PO Box 13248 Station A, St. John's, Newfoundland A1B 4A5, Canada. E93E94 MARINE MAMMAL SCIENCE, VOL. 28, NO. 2, 2012 prey upon other marine mammals. Monodontids were the most frequently observed prey items, followed by bowhead whales (Balaena mysticetus), phocids, and groups of mixed mammal prey. No killer whale sightings occurred during winter, with sightings gradually increasing from early spring to a peak in summer, after which sightings gradually decreased. Our results suggest that killer whales are established, at least seasonally, throughout the Canadian Arctic, and we discuss potential ecological implications of increased presence with declining sea ice extent and duration.

Diet of beluga whales, Delphinapterus leucas, in Alaska from stomach contents, March-November

“…These adaptations and their distribution may serve as defenses against killer whales (Frost and Lowry, 1990). Killer whales appear to avoid ice likely because their large dorsal fi n limits their ability to surface and breathe in broken ice covered water (Matthews et al, 2011;Higdon et al, 2012). The migratory stocks of belugas may rely on sea ice as escape habitat while the resident stocks may rely on shallow water.…”

Time series data for Canadian arctic vertebrates: IPY contributions to science, management, and policy

“…Long-term monitoring of arctic vertebrate populations has been essential not only for developing policy and regulating harvest Peacock et al 2010;Higdon et al 2011), but also for input to international climate change analyses (Arctic Climate Impact Assessment ACIA 2005), regional land use planning and environmental assessment (Mallory and Fontaine 2004), and downlisting/uplisting species (Stirling and Parkinson 2006;Robertson et al 2007). Funding and logistical support during IPY made significant contributions to longterm time series for arctic vertebrates, including the standardization of metadata, establishment of long term archives and improving access to collected data.…”

“…The GWAMM IPY project summarized killer whale (Orcinus orca) sightings from Canadian arctic waters and provided a unique dataset capable of determining long-term trends in sighting frequency, changes in distribution and relative abundance, and evidence of food habits (Higdon 2007;Higdon and Ferguson 2009;Higdon et al 2011). Inuit hunters throughout the eastern Arctic have reported recent increases in killer whale sightings and are concerned about the effects of increased predation on culturally-important marine mammals, and a research program was established in 2005 in response to these observations and concerns (Higdon 2007).…”

“…Inuit hunters throughout the eastern Arctic have reported recent increases in killer whale sightings and are concerned about the effects of increased predation on culturally-important marine mammals, and a research program was established in 2005 in response to these observations and concerns (Higdon 2007). A large spatial database of sighting reports has been developed (detailed in Higdon 2007;Higdon et al 2011). To date, analyses of database records has provided important information on the spatiotemporal distribution and relative abundance of killer whales in different areas of the Canadian Arctic (Higdon 2007;Higdon et al 2011), which has also been used to plan field research (e.g., Matthews et al 2011).…”

“…A large spatial database of sighting reports has been developed (detailed in Higdon 2007;Higdon et al 2011). To date, analyses of database records has provided important information on the spatiotemporal distribution and relative abundance of killer whales in different areas of the Canadian Arctic (Higdon 2007;Higdon et al 2011), which has also been used to plan field research (e.g., Matthews et al 2011). Inuit knowledge was collected via 105 semidirected interviews in 11 Nunavut communities from 2007-2010 .…”