Dall’s porpoises are also known to feed at night when lipid-rich mesopelagic prey such as Myctophidae and Bathylagus, both present in the Dall’s porpoise
samples, migrate upwards from depths in excess of 200 m. In contrast shiner perch, present only in harbour porpoise samples, is a species associated with shallow nearshore habitats. Resource partitioning is also likely to occur in accordance with seasonal prey availability.