Research Document - 2007/048

Status of knowledge on killer whales (Orcinus orca) in the Canadian Arctic

By Higdon, J.

Abstract

Killer whales or orcas (Orcinus orca) are widely distributed throughout the Canadian Arctic, where they likely prey on a large variety of marine mammal species, including those important to the Canadian Inuit. It is therefore important to gain a better understanding of the distribution, ecology, and potential predation impacts of eastern killer whales. Inuit hunters in the Canadian eastern Arctic have reported a recent increase in killer whales sightings, with similar increases reported off Newfoundland and West Greenland. These increases may be due to increased sighting effort, a change in killer whale distributions, population increases, or some combination thereof. This report presents an extensive review on killer whales in Arctic Canada, defined as the Labrador Sea north and west through Nunavut to the Yukon coast. A GIS-database of killer whale sightings has been compiled, which currently holds 485 records (excluding > 200 sightings in the North Atlantic). While there are a number of biases inherent in this database (i.e., inshore versus offshore observer effort, group size determination, predation observations), a summary of the data is nonetheless instructive in cataloguing knowledge on killer whales in the Canadian Arctic.

The majority (87%) of killer whale sightings occurred in the summer (June-September), although scattered records occur throughout the year. Most sightings have been reported in the southwest Greenland and Lancaster Sound regions. Group sizes reported ranged from one to up to over 100 animals, and most sightings (82%) involved more than one killer whale. Median group size was three whales. A total of 122 records included information on predation events, with narwhal (Monodon monocerus) the dominant prey species, followed by beluga (Delphinopterus leucas) and bowhead (Balaena mysticetus) whales. The largest source of killer whale mortality in the Arctic is direct human killing, especially by Greenland Inuit. These harvest levels have increased considerably in recent years and may be unsustainable.

Further study on killer whales in the eastern Canadian Arctic, which is clearly required, is now in the initial stages. A sighting network and photoidentification database are in development, acoustic monitoring has been started, and future plans call for dedicated field work to photograph, record and biopsy sample killer whales. Inuit hunters will be a critical component of Arctic killer whale research. In summer 2007 intensive research will be conducted in Repulse Bay, which has been identified as a focal area for killer whale research, consisting of collection of Inuit traditional knowledge, deployment of two autonomous acoustic recorders, and dedicated field surveys.

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