Northern right-whale dolphin

Lissodelphis borealis
Other names: 
  • n/a
Maximum length: 
  • Male: 3.1m
  • Female: 2.6m
  • Calf: 1m
Maximum weight: 
  • Male: 115 kg's
  • Female: Unknown
  • Calf: Unknown
Diet: 
  • Surface and mid-water fish (including lanternfish, hake and sauries)
  • Squid
  • Octopus
Estimated population: 
Unknown
IUCN Listing: 
LC
CITES Appendix: 
II
CMS Appendix: 
Not Listed
Classification: 

Northern right-whale dolphin forms an anti-tropical species pair with the southern right-whale dolphin. Both species were so named because, like right whales, they lack dorsal fins. Before its closure in the 1990s, thousands of northern right-whale dolphins were taken on an annual basis in the North Pacific drift-net fishery. This heavy exploitation, along with other incidental catches, is thought to have severely depleted this population.

Appearance: 

This species has a slender body. It has a short narrow beak and low sloping forehead, separated by a sharp groove, with the lower jaw protruding beyond the upper jaw. It has no dorsal fin, small, narrow, pointed flippers, a slender tailstock, and small pointed flukes. The northern right-whale dolphin is mostly black with a white band running ventrally from the head to the tailstock, widening at the chest. There is also a white patch underneath the jaw. The flippers are black and the flukes are white underneath and black above with grey trailing edges. Juveniles are greyish brown, and adult colouration develops with age. An additional colour morph, with individuals showing more extensive white colouration in a 'swirled' pattern has been documented. Its lack of dorsal fin makes the northern right-whale dolphin easy to identify, however from a distance it may be confused with leaping sea lions.

Behaviour: 

Travelling in pods of between 100 and 200 individuals, northern right-whale dolphins can often be seen in the company of Pacific white-sided dolphins, Risso's dolphins and many other species. They may also be seen in groups of up to 3,000 animals. When swimming slowly they cause little disturbance to the surface water, but they often travel at speed (up to speeds of 25mph) in large groups, porpoising, side-slapping and belly-flopping. Northern right-whale dolphins are highly acrobatic and perform long, low leaps at high speed. They are known to be avid bow riders. This species feeds on small fish and squid in deep waters over and beyond the continental shelf.

Distribution: 

The northern right-whale dolphin is found only in the cool temperate waters of the North Pacific, from 30°N to 50°N. An oceanic species, it is only found close to shore where deep-water is found close to the coast. Large numbers of mortalities have resulted from fisheries using driftnets and purse seines and they are also taken directly in small numbers in small-cetacean hunts in Japan. Other threats may include climate change and prey depletion. There is no global abundance estimate for this species and the IUCN categorises the northern right-whale dolphin as of ‘Least Concern'.

Distribution map: