A re-evaluation of the role of killer whale (Orcinus orca) predation in the decline of sea otters (Enhydra lutris) in the Aleutian Islands ...

• Main Author: Kuker, Kathryn
• Format: Article in Journal/Newspaper
• Language: English
• Published: University of British Columbia 2008
• Subjects: Killer Whale; Orca; Orcinus orca; Aleutian Islands; Killer whale
• Online Access: https://dx.doi.org/10.14288/1.0067029; https://doi.library.ubc.ca/10.14288/1.0067029

Sea otters in the Western Aleutian Islands have experienced a drastic population decline since the 1990s and Estes et al. (1998) hypothesized that killer whale predation is responsible. This hypothesis has not been challenged nor tested empirically. The aim of this study was twofold: 1) to conduct a literature review of the evidence that killer whales caused the sea otter populations to decline, re-examining alternative explanations, and 2) to empirically test the "killer whale prédation hypothesis" by comparing sea otter behavioural responses to artificial killer whale cues (playbacks of killer whale vocalizations and blows) in the Aleutian Islands to the response of sea otters to the same cues in British Columbia, where they do not suffer intensive killer whale prédation. The literature review revealed that the existing data are inconclusive and further research into other possible causes is needed. For example, high contaminant levels observed in sea otters coupled with intensive military occupation in ...