This species inhabits mainly offshore deep waters colder than 18°C (Miyashita and Kasuya 1988), but may also occur in narrow channels and fjords in the western North Pacific (Jefferson 1988; Rice 1998).

Sex-biased dispersal is known to occur in this species, and this may have relevance in assessing the impact of takes on regional populations (Escorza Trevino and Dizon 2000).

Dall's porpoises are apparently opportunistic feeders, taking a wide range of surface and midwater fish and squid, especially soft-bodied species like lanternfish (myctophids) and gonatid squid. Occasional krill, decapods, and shrimps found in porpoise stomachs are not considered normal prey (Houck and Jefferson 1999; Jefferson 2002).