Possible Pacific White-sided Dolphin Sighting (Lagenorhynchus obliquidens)

Unusually active marine mammals seen near Unalaska may actually be Pacific white-sided dolphins.

Observation by Julieanne Renee Berikoff:

A local called the environmental department at the Tribe early in the afternoon to notify us that there was unusual behavior from porpoises in Unalaska Bay. As we drove out to the landfill, there was a herd of porpoises continuously jumping. In addition, their whole bodies were jumping out of the water, which the local porpoises don’t do. They were swimming between the landfill and the spit area. As we observed them from afar with binoculars, it was hard to identify if they were just Harbor porpoises or Dall's porpoises. It could have possibly been a new species that has come to Unalaska. Porpoises out in Unalaska are one of the smallest marine animals that only grow up to 6 ft in length and weigh around 160 pounds. Many of them don't swim far from the coastline. They also aren't too interactive in the bay such as the ones we observed. I am curious if it was a lost herd of porpoises from somewhere else or if they were other species that are starting to come to Unalaska because of climate change.

Asia Beder, Fisheries Biologist with the Alaska Department of Fish and Game, writes:

Thank you for reaching out. I unfortunately did not see this event, and it is hard to identify the species based on the photo. Although harbor porpoises are generally pretty docile, I have personally seen one jump out of the water here. They are usually in pretty small groups though. It would be helpful to have an estimate of how many individuals were spotted during this event. I have heard stories about a large group of either dolphins or porpoises making their way into the bay many years ago and putting on a good show around this same area (landfill/spit/Summers Bay). I also have had fishermen report large groups of Pacific white-sided dolphins zooming around their vessels when they're out fishing farther from shore towards Akutan, so a group could have potentially come into the bay. Whatever the species, I expect food brought them into the bay.

Melissa Good, Marine Advisory Program Agent with University of Alaska Fairbanks Sea Grant, writes:

Without additional photos, it is difficult to say what species this is; however, we may have some clues that lean towards Pacific white-sided dolphins. Harbor porpoises have an average size of 5 ft, 120 lbs, and are commonly observed in Unalaska Bay. They generally travel alone or in small groups and are considered shy. Pacific white-sided dolphins are common in the region and are often seen just outside of Unalaska Bay, though they rarely come into Unalaska Bay. They are quite a bit larger than the harbor porpoises having an average length of 7.5 ft and reaching 300 lbs. They are well-known for being bowriders and often travel in large groups. Herring have recently been spotted inside of Unalaska Bay close to town and it would not be much of a stretch to think Pacific white-sided dolphins came in chasing prey.

Comments from LEO Editors:

Alaska is home to two species of porpoise, the Dall porpoise (Phocoenoides dalli) and the harbor porpoise (Phocoena phocoena), and one species of dolphin, the Pacific white-sided dolphin (Lagenorhynchus obliquidens). The Alaska Department of Fish and Game describes Pacific white-sided dolphins as being playful and acrobatic, known to entertain with leaps, flips, and somersaults. Their seasonal movements are not yet well-understood, but some groups are known to migrate up the Pacific coast to Kodiak, occasionally making appearances near the Aleutians and in the Gulf of Alaska.