Dall’s Porpoise (Phocoenoides dalli)
– maximum length of 2.2 metres
– body black, conspicuous white patch on lower flanks
– small, triangular in shape with white tip and black base
– trailing edge is white
– ‘chunky’ robust body
– creates a distinct ‘rooster-tail’ splash when traveling quickly, does not bring body entirely out of the water
– during slow dives shows a distinctive sharp curve to the hind quarter as it disappears under water (distinguishes it from harbour porpoise).
– travels in group sizes of 10 to 20
– fastest cetacean in BC, at speeds up to 55 km/hr.
Can Be Confused With
– harbour porpoise, ‘baby’ killer whale
Dall’s porpoise are found only in the North Pacific Ocean and adjacent seas (Bering Sea, Okhotsk Sea and Sea of Japan). They range from coastal waters to deep offshore waters (see map below).
Details of migrations are poorly known, however, Dall’s porpoise are year-round resident though-out much of their range, generally moving north for the summer and south for the winter.
Dall’s porpoise feed mainly on small schooling fishes (herring, anchovies, mackerels and sauries) and cephalopods (octopuses, squid, and cuttlefish).
A single calf is born mainly from late June to September. Gestation estimates range from 7 to 11.4 months. Nursing continues for only a few months. Not all adult females become pregnant every year; nonbreeders may segregate from breeders. Males are sexually mature at 5-8 years, females at 3-7 years, depending on location. Life expectancy is approximately 13 years.
Hybridization between Dall’s porpoise and harbour porpoise occurs occasionally in BC waters with harbour porpoise as the paternal parent and Dall’s porpoise as the maternal parent. Hybrids tend to appear more similar to Dall’s porpoise in body shape, diving characteristics and behaviour, but they lack the white side patches and the colouring is more similar to the harbour porpoise.
Between 2000 and 2006, 11 Dall’s porpoise have been found dead-stranded in the inner south-coast waters having died of Cryptococcus gattii, a fungus that causes serious diseases in wildlife and humans.
STATUS IN CANADA
COSEWIC: Not at risk (1989)
BC Provincial Red List: Yellow (Apparently secure and not at risk of extinction)