A dolphin that lives in groups in the temperate North Pacific.
It has a black back, white belly and grey sides, with a pale stripe extending from the eye toward the tail.
Off British Columbia, Pacific white-sided dolphins were seen with fish-eating northern resident killer whales. In August 2020, researchers tagged nine killer whales with cameras, microphones and motion sensors, and used drones. Four whales were filmed with dolphins over four days. Killer whales turned toward dolphins and followed them on 25 foraging dives. Drones recorded dolphins chasing and eating small salmon. In one event, dolphins ate scraps from an adult Chinook salmon caught by a whale.
Dolphin echolocation overlapped with whale hunts, suggesting the whales might use those sounds as search clues. This may be opportunistic cooperation, but mutual benefits were not measured. It covered one area during a short summer period, so its wider range and seasonality remain unknown.
IUCN Red List · Least Concern (LC) · Global species-level assessment
The IUCN global assessment dated 11 May 2018 lists the Pacific white-sided dolphin as Least Concern (LC), with its population trend unknown. A global category does not combine local changes into a single trend. The assessment records substantial historical bycatch in high-seas drift-net fisheries, captures in Japanese coastal nets, and fishery interactions in the eastern North Pacific. It also reports a decline in density at one Southern California survey area from 2004 to 2013, while the species-wide trend remains unknown. NOAA’s 2023 assessment of the North Pacific stock in Alaska likewise says abundance and trend are unknown because surveys are old and fishery observer coverage is limited. In U.S. waters, the species is protected under the Marine Mammal Protection Act, with measures aimed at reducing fishing-gear interactions and underwater noise.