Pacific White-sided Dolphins inhabit temperate oceanic waters across the North Pacific, as well as shelf and slope waters of the North Pacific continental margins (see distribution plots in Carretta et al. 2006 and Best et al. 2015), and in some inland waterways in British Columbia (Heise 1997a, Morton 2000, Ashe 2015) and southeast Alaska (Dahlheim et al. 2009).

Pacific White-sided Dolphins feed on a wide variety of small pelagic schooling fishes (e.g. lanternfish, anchovies, saury, horse mackerel, herring, and hake) as well as salmon and cephalopods (Heise 1997b, Morton 2000). They commonly occur in association with other marine mammal species, particularly Northern Right Whale Dolphins (Lissodelphis borealis), Risso's Dolphins (Grampus griseus), and California Sea Lions (Zalophus californianus) (Brownell et al. 1999).

Pacific White-sided Dolphins inhabit temperate waters of the North Pacific and some adjacent seas including the Sea of Japan, southern Okhotsk Sea, southern Bering Sea, and southern Gulf of California (Brownell et al. 1999, Black 2018). Their range includes continental slope waters of the western North Pacific as far south as southern China and Taiwan, shelf and slope waters of the eastern North Pacific from the Gulf of Alaska southward to Baja California, Mexico, and deep offshore waters of the North Pacific between about 35˚N and 47˚N latitude (Hobbs and Jones 1993, Black 2018). Pacific White-sided Dolphins generally inhabit productive continental shelf and slope waters within 185 km of shore (Black 2018). 

Distribution appears to change seasonally in many places, probably linked to changes in water temperature and distribution of prey. The probability of sighting Pacific White-sided Dolphins in southeast Alaska appears to increase in spring (Dahlheim et al. 2009). Along the continental shelf of British Columbia (BC), Canada, Pacific White-sided Dolphin abundance showed no major seasonal differences in density among spring, summer, or fall surveys (Best et al. 2015). On a finer spatial scale, Morton (2000) reported an increase in sighting probability of this species in the fjords of BC in spring and fall. 

Similarly, Pacific White-sided Dolphin sightings off southern California peaked during cooler water temperatures of spring (Henderson et al. 2014), which is likely to be due in part to the strong correlation of the Pacific Decadal Oscillation with fluctuations in the occurrence of small pelagic fish (Lehodey et al. 2006). 

The Pacific White-sided Dolphin is listed in Appendix II of the Convention on International Trade in Endangered Species.

The most significant international conservation measure for this species was the United Nations moratorium on high-seas driftnet fishing implemented in 1993. In the eastern North Pacific, the U.S drift gillnet fishery has been required since 1996 to use acoustic warning devices (pingers) to reduce cetacean bycatch; however, low levels of bycatch of this species have continued (Carretta et al. 2017).