Phocoenacide – The Killing of Harbor Porpoise (Phocoena phocena) by Fish Eating Southern Resident Killer Whales (Orcinus orca).

• Main Author: Giles, Deborah
• Format: Text
• Language: English
• Published: Western CEDAR 2017
• Subjects: Fresh Water Studies; Life Sciences; Marine Biology; Natural Resources and Conservation; Killer Whale; Orca; Orcinus orca; Killer whale
• Online Access: https://cedar.wwu.edu/ssec/2016ssec/species_food_webs/96

Southern Resident fish-eating killer whales have been observed "mugging" and killing harbor porpoise without subsequent predation on the animal carcass. While occasional porpoise killings by L-pod and K-pod members had been documented by staff of the Center for Whale Research since regular monitoring started in 1976, prior to 2005, J-pod was never seen engaging in this “mugging” behavior. However, in 2005, multiple different members of J-pod were documented killing harbor porpoises on four separate occasions during the month of July. Since 2005, several different research groups have recorded additional mugging episodes by members of all three Southern Resident Killer Whale pods. Pooling long-term datasets from myriad research groups allows for robust analysis of this novel behavior with the aim of understanding why this behavior is occurring as well as possible implications for the local harbor porpoise population.