Dall’s porpoise are known for the distinctive ‘rooster tail’ fan-shaped splash they make while swimming. They are the biggest porpoise and are known for their black and white coloration.
Dall’s porpoises have no beak and a relatively small head with a thick and robust body thickening toward the tail. Their flippers and small and round. The dorsal fin is triangular, angles forward and is tipped in gray. They have black bodies with white lateral patches on their sides and underside.
They are oftentimes confused for young orcas because of their black and white coloration. But unlike orcas, they do not have eye or saddle patches. Their markings and coloration vary by geographic location and life stage.
There are 11 populations of Dall’s porpoise in the North Pacific, and there are two distinct subspecies based on distinguishable color patterns:
Phocoenoides dalli truei is abundant in the western part of their range in the waters off Japan and the Kuril Islands.
Phocoenoides dalli dalli ranges across the North Pacific from northern Japan to the Bering Sea and into California. The white patch of the truei-type is bigger than that of the dalli-type.
Dall’s porpoises are named after the American naturalist who first recorded them—William Healey Dall (1845-1927).
They are the fastest swimmers of the small Cetaceans. They reach speeds up to 34 miles per hour!
North Pacific Ocean (US West Coast from the US-Mexico border to the Bering Sea in Alaska and the Sea of Japan)
Cold northern waters more than 600 feet deep. Offshore, inshore and nearshore oceanic waters.
Small schooling fish such as herring, mid and deep water fish, cephalopods (squid and octopus), crustaceans (crab and shrimp)
Transient orcas and humans
Dall’s porpoise often feed at night when their prey migrates toward the surface. They have small teeth which they use for grasping their prey. Their dive times are short at around 2 to 4 minutes.
They travel in groups averaging up to 12 individuals but they can be found in larger groups numbering into the hundreds or thousands. They are sometimes seen swimming alongside large whales.
They are often attracted to fast moving vessels and bow-ride ships. When they surface during swimming they create a distinctive “rooster tail” spray.
Similar to Orcas, Dall’s porpoise emit low frequency clicks which are thought to be used for echolocation.
Dall’s porpoises produce a single calf after a 10-12 month gestation period, usually in the summer months. Calves nurse for less than 1 year before weaning.
Japanese fishermen hunt between 15,000 – 20,000 Dall’s porpoises annually for meat. Other threats include entanglement, hunting, habitat loss, environmental contaminants, underwater noise.
Dall’s porpoises in US waters are divided into the Alaska stock with a population of 83,000 and California/Oregon/Washington stock with an estimated population of 100,000. They are considered reasonably abundant. Across the North Pacific there are estimated to be 841,000 individuals.
All populations are protected under the Marine Mammal Protection Act (Marine Mammal Protection Act).
