Phocoenoides dalli
Dall's Porpoise [+]

Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Family: Phocoenidae
Genus: Phocoenoides
species: Phocoenoides dalli
+ITIS +WoRMS +Conservation Status

Description & Behavior

Dall's porpoises, Phocoenoides dalli (True, 1885), are robust (particularly males) and muscular cetaceans with relatively small heads that slope steeply to short indistinct beaks. In spite of the stocky body, they are a relatively small porpoise that average only 1.8 m in length for males with a maximum length of 2.29 m. Females average 1.8 m in length with a maximum length of 2.1 m. Weight averages 123 kg for both males and females with a possible maximum weight of about 160 kg. There are 19-23 small teeth in each side of the upper jaw and about 20-24 teeth in each side of the lower jaw, which extends beyond the upper jaw. Each spade-shaped tooth is separated by rigid, protruding growths known as "gum teeth" thought to be used to aid the small teeth in grasping slippery prey such as squid. There is a hump is present on the dorsal side and another hump, more prominent in males, found in front of the flukes on the ventral side. The dorsal fin is located slightly forward the center of the body and is triangular in shape. The small flippers are rounded at the tips, and the small flukes are pointed with a slight median notch. Dall's porpoises have a unique black or dark blue iris with a deep, iridescent blue-green pupil.

Dalls porpoises

This porpoise is black on the dorsal side with oval-shaped white markings along the flanks and white on the ventral side. The flukes are bordered by a band of white and the dorsal fin also has white markings of various shapes, although they can also be solid black or white.

There are two subspecies of Dall's porpoise, Phocoenoides dalli:

1. Dall's porpoise (dalli-phase), P. dalli dalli
2. Dall's porpoise (truei-phase), P. dalli truei

Dall's porpoises are extremely fast swimmers reaching speeds of up to 30 knots. They enjoy bow riding and they create a bow wave of their own known as a "rooster tail," which creates a hollow airspace in the water that allows the porpoise to continue breathing while swimming. In spite of their tendency to bow ride, this species can also be elusive when it comes to human interaction. They are typically found in groups of 10-20 individuals, but groups of up to 200 have been observed feeding. They often associate with Pacific white-sided dolphins and pilot whales.

World Range & Habitat

Dall's porpoise, Phocoenoides dalli, are limited to the North Pacific, ranging from Baja California north to Alaska and the Bering Sea and across into Japanese waters. The tend to prefer colder waters with temperatures of less than 15°C. Many are year-round residents throughout their range.

» GBIF occurrence data in Google Earth [Requirements | Tips] | Ocean Biogeographic Information System (OBIS) [World Map] | [about]

Feeding Behavior (Ecology)

Dall's porpoises, Phocoenoides dalli, feed on squid in some parts of their range, but in other areas they feed on small schooling fishes such as capelin, herring, and sardines. Deep-water species such as hake and deep-sea smelt are also prey of Dall's porpoise in some areas. In the northwest Pacific they feed primarily on lanternfish. They are known to consume about 12.7-13.6 kg of food daily, primarily at night.

Life History

Dall's porpoises, Phocoenoides dalli, reach sexual maturity at about 1.9 m or at 8 years of age for males and about 1.7 m or 7 years for females. Calving takes place primarily in summer, although births in U.S. Coastal populations occur year-round. Gestation is between 10-12 months and calves are born averaging 1 m in length and weighing about 25 kg. They are nursed for 2 years. The calving interval for females is around 3 years. Life expectancy for Dall's porpoises is estimated to be less than 20 years.

Comments

Dall's porpoises, Phocoenoides dalli, are still abundant throughout their range; however in Japan, large numbers are caught in gillnet fisheries and coastal whaling operations. They are also hunted for food by the Japanese. They are threatened by the Japanese high seas salmon fishery, where as many as 8,000-10,000 porpoises die as bycatch during the 2-month fishing season. Although Dall's porpoises do not feed on salmon, it is thought that they become entangled while feeding on deep-sea species that come to the surface at night. It has also been suggested that the plastic and nylon netting used in the salmon fisheries is not detected by Dall's porpoise sonar. Unfortunately, the majority caught are females, many of which are pregnant or nursing. Efforts are underway to protect Dall's porpoises, an important endeavor given the extent of the fishing industry in their range.

References & Further Research

BioOne ~ CITES ~ Discover Life ~ GBIF ~ Google Scholar ~ ITIS ~ IUCN RedList ~ MarineBio Network ~ NCBI ~ SCIRIS ~ SIRIS ~ Tree of Life Web Project ~ Wikipedia

ACS Dall's porpoise Cetacean Fact Sheet - American Cetacean Society
Jefferson, T.A., S. Leatherwood, and M.A. Webber, FAO species identification guide, Marine mammals of the world, Rome, FAO. 1993. 320 p. 587 figs.
Whale and Dolphin Conservation Society (WDCS)

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Citation: Phocoenoides dalli, Dall's Porpoise - MarineBio.org. Retrieved , from .

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Phocoenoides dalli Dall's Porpoise [+]