Distribution and Movement Patterns of Killer Whales (Orcinus orca) in the Northwest Atlantic

No abstracts are to be cited without prior reference to the author.

Killer whales (Orcinus orca) occur throughout the northwest Atlantic. A sightings database and photographic catalogue, created mostly from opportunistic sources, is used to examine the occurrence of killer whales in Atlantic Canada. A majority of the sightings are from the Newfoundland and Labrador Region despite comparable observer coverage in adjacent areas such as the Gulf of St. Lawrence and Scotian Shelf, which suggests greater abundance in and habitat preference for Newfoundland and Labrador waters. Killer whales occur in all months of the year and in both near- and offshore regions, although particular sighting patterns may represent local observer effort and awareness. The distribution, movement, and residency patterns of killer whales may be closely linked to that of their prey; they have been observed harassing, attacking, and eating marine mammals, including minke whales (Balaenoptera acuterostrata), dolphins, and seals, and potentially eating fish. Some killer whales appear to remain year round in the Newfoundland and Labrador area and have been sighted during the spring within pack ice, potentially in association with breeding harp seals (Phoca groenlandica). Based on photographic records, individual killer whales in this area have been shown to move hundreds of kilometers within a year. Conversely, although there is no spatial or temporal evidence of seasonal migration, killer whales may be reliably seen in certain areas during particular times of the year, suggesting that long-term site fidelity patterns may exist within this population