(Peale, 1848) - Northern right whale dolphin
Distinctive Characteristics
The northern right whale dolphin and its Southern Hemisphere relative are the most slender of all small cetaceans. At close range, northern right whale dolphins are unmistakable; they are the only small cetaceans in their range with no dorsal fin. The flukes and flippers are small, and the beak is short, but well-defined.
Northern right whale dolphins are primarily black, with a white band from the throat to the fluke notch that widens to cover the entire area between the flippers, and a white spot just behind the tip of the lower jaw. The trailing edges of the flukes have light grey edging above and white below. Young animals have muted colour patterns of dark grey and light grey.
The mouth contains 37 to 54 pairs of sharp, slender teeth in each jaw.
Can be confused with
The slender finless body will allow easy separation from other North Pacific small cetaceans. However, porpoising California sea lions, at a distance, can be confused with northern right whale dolphins.
Size
Measured adults have been up to 2.3 m (females) and 3.1 m (males). Length at birth is unknown, but is thought to be approximately 1 m. Maximum known weight is 115 kg.
Geographical Distribution
The northern right whale dolphin is an oceanic species, inhabiting cold and warm temperate regions of the North Pacific, mostly between about 30°N and 50°N.
Biology and Behaviour
Most herds number between 100 and 200 individuals, but groups of up to 3000 have been seen. These groups commonly mix with other marine mammals, especially the Pacific white-sided dolphins (with which they share a nearly identical range). Northern right whale dolphins are fast swimmers, sometimes creating a great surface disturbance with their low-angle leaps and belly flops. They bowride, especially when accompanied by other species of dolphins.
There appears to be a calving peak in winter to early spring.
Although squid and lanternfish are the major prey items for right whale dolphins off southern California, a variety of surface and mid-water species are taken by this species.
Exploitation
Occasional incidental catches in the eastern Pacific and both direct and accidental catches in the western Pacific do not appear to be seriously affecting stocks. However, in the central Pacific, the northern right whale dolphin appears to be the primary species of small cetacean taken in recent years by the Japanese, Taiwanese, and Korean squid driftnet fisheries, with numbers apparently approaching 20,000 per year.
IUCN Status
Insufficiently known.