Classification: 

Dall's porpoises have been widely utilize over the years and remain one of the main species hunted by Japanese fishermen with catch rates as high as 40,000 individuals a year.

Two subspecies are currently recognised; P. d. dalli, (Dalli's type) which is more widespread, and P. d. truei (Truei's type) which is restricted to the western sector of the species range.

Although both display a dappled appearance, these two subspecies show change in both colour and size.

 

 

Appearance: 

The Dall's porpoise is the largest species of porpoise and has a strong and well-knit body.

It has a small head with a short beak with an overturned mouthline and a  flat forehead.

The forward-leaning, triangular dorsal fin has a wide base and might have a hooked tip.

The pale white/grey spot on the top looks like 'frosting' and it is a unique characteristic of this animal. Small rounded flippers are close to the head and it has a thick tailstock and keel which is more overstated in males.

The notched flukes sometimes have a white upper trail edge. Colour change between subspecies.

The dalli-subspecies is black with a bright white patch extend along the side and belly from just below the dorsal fin to the middle of the tail stock while the white patch on the truei-subspecies starts further forward , just in front of the flippers.

Due to their unique colour, Dall's porpoises are not easily confused with other species of cetacean.

 

 

Behaviour: 

The Dall's porpoise has a very ‘un-porpoise-like' behaviour.

Most members of this Family are quiet and shy, preferring to avoid boats while the Dall's porpoise actively search for large fast moving boats.

The Dall's porpoise is the fastest swimming small cetacean, and in short explode can reach speeds of up to 55 km/h, surfacing quickly creating a unique spray of water called a ‘rooster tail'.

They are anxious bow-riders but will not stay long with boats moving slower than 20 km/h.

 Generally found in groups of fewer than 20 animals, polymerization of more than 1,000 individuals have been seen.

Often found to partner with Pacific white-sided dolphins and long-finned pilot whales.

Dall's porpoises are mainly an oceanic species however they can be found in more coastal waters where deep water is closer to the shore.

They feed at night on fish and cephalopods in waters as deep as 500m.